bluuebunny/crossref_metadata_2025 huggingface dataset:
Vibration Analysis and Mitigation of Dead-Zone on Systems Using Two-Impulse Zero-Vibration Input Shaping
Authors: Sorensen Khalid L. , Cross Patrick W. , Singhose William E. , Prakash Shashvat
Published: October 2010

Input shaping is an effective method for reducing oscillatory motion in linear systems. Many physical systems, however, exhibit discontinuous dynamics, such as saturation, rate limiting, backlash, and dead-zone. These hard nonlinearities can degrade the vibration reducing properties of shaped signals. This paper investigates the detrimental effects of dead-zone on a class of input-shaped commands. A mitigation strategy is proposed for reducing these detrimental effects when the value of the dead-zone can be estimated. The robustness of this mitigation approach to uncertainties in the dead-zone width is also determined. Theoretical developments are experimentally verified using an industrial 10 ton bridge crane.
Mobility Analysis of Parallel Manipulators and Pattern of Transform Matrix
Authors: Chen Chao
Published: October 2010

The mobility or degrees of freedom is a fundamental issue in mechanisms and robotics. In this work, we investigate the mobility of parallel manipulators from a new point of view, and introduce a new concept, the pattern of transform matrix. It is shown that both general and modified Chebychev–Gruble–Kutzbach formulas are the special cases of the pattern analysis. We further propose a framework upon the pattern analysis of transform matrix to calculate the mobility, to evaluate the property of the motion, and to determine the exact-actuation arrangement. The proposed approach should be general enough to evaluate any existing parallel manipulator. Five parallel manipulators with special geometric conditions and lower mobilities are discussed.
Numerical Techniques for Approximating Lyapunov Exponents and Their Implementation
Authors: Dieci Luca , Jolly Michael S. , Van Vleck Erik S.
Published: October 2010

The algorithms behind a toolbox for approximating Lyapunov exponents of nonlinear differential systems by QR methods are described. The basic solvers perform integration of the trajectory and approximation of the Lyapunov exponents simultaneously. That is, they integrate for the trajectory at the same time, and with the same underlying schemes, as is carried out for integration of the Lyapunov exponents. Separate computational procedures solve small systems for which the Jacobian matrix can be computed and stored, and for large systems for which the Jacobian cannot be stored, and may not even be explicitly known. If it is known, the user has the option to provide the action of the Jacobian on a vector. An alternative strategy is also presented in which one may want to approximate the trajectory with a specialized solver, linearize around the computed trajectory, and then carry out the approximation of the Lyapunov exponents using techniques for linear problems.
Development and Validation of Geometry-Based Compliant Contact Models
Authors: Luo Lianzhen , Nahon Meyer
Published: October 2010

Simulations are often used to evaluate space manipulator tasks that involve contact with the environment, due to the difficulty of performing realistic earth-based experiments. An important aspect of these simulations is the contact model used to determine the interbody forces between two objects in contact. In this paper, we present two compliant contact models for polyhedral contacting objects. These models explicitly consider the distinction between true contact geometry and interference geometry. To account for the energy dissipated during impact, a damping force is included in the two models. Model validation is then performed in three ways: against analytical models, against experimental data, and against finite element method (FEM) models. The results of the validation exercise demonstrate the fidelity of the proposed models.
Coffee Stain Ring Effect and Nonuniform Material Removal in Chemical Mechanical Polishing
Authors: Xin Jianguo
Published: October 2010

When a drop of coffee dries on the counter-top, it leaves a dense, ringlike stain along its perimeter. Solids immersed in a drying drop will migrate toward the edge of the drop and form a solid ring. Such phenomena create ringlike stains and happen for a wide variety of surfaces, solvents, and solutes. It is referred to as the coffee stain ring effect. The phenomenon is caused by the outward microfluidic flow of the solute within the drop, which is driven by the evaporation of solvent. We show that the mechanism for the ring effect contributes to the nonuniform material removal in chemical mechanical polishing (CMP), specifically, at edges of blanket wafers causing the edge effect or at edges and corners of protrusive features on patterned wafers inducing the doming effect; metal dishing and dielectric erosion. By controlling the evaporation profile of the solvent in the slurry layer between the wafer surface and the polishing pad, such as making grooves or embedding the abrasive particles on the pad, or delivering the slurry from the bottom of the pad, one can improve the uniformity of material removal during the CMP process.
Assessment of Solar Power Tower Driven Ultrasupercritical Steam Cycles Applying Tubular Central Receivers With Varied Heat Transfer Media
Authors: Singer Csaba , Buck Reiner , Pitz-Paal Robert , Müller-Steinhagen Hans
Published: October 2010

For clean and efficient electric power generation, the combination of solar power towers (SPTs) with ultrasupercritical steam cycle power plants could be the next development step. The methodology of the European concentrated solar thermal roadmap study was used to predict the annual performance and the cost reduction potential of this option applying tubular receivers with various appropriate high temperature heat transfer media (HTM). For the assessment, an analytical model of the heat transfer in a parametric 360 deg cylindrical and tubular central receiver was developed to examine the receiver’s efficiency characteristics. The receiver’s efficiency characteristics, which are based on different irradiation levels relative to the receiver’s design point, are, then, used to interpolate the receiver’s thermal efficiency in an hourly based annual calculation of one typical year that is defined by hourly based real measurements of the direct normal irradiance and the ambient temperature. Applying appropriate cost assumptions from literature, the levelized electricity costs (LEC) were estimated for each considered SPT concept and compared with the reference case, which is a scale-up of the state of the art molten salt concept. The power level of all compared concepts and the reference case is 50 MWel. The sensitivity of the specific cost assumptions for the LEC was evaluated for each concept variation. No detailed evaluation was done for the thermal storage but comparable costs were assumed for all cases. The results indicate a significant cost reduction potential of up to 15% LEC reduction in the liquid metal HTM processes. Due to annual performance based parametric studies of the number of receiver panels and storage capacity, the results also indicate the optimal values of these parameters concerning minimal LEC.
Using Support Vector Machines to Formalize the Valid Input Domain of Predictive Models in Systems Design Problems
Authors: Malak Richard J. , Paredis Christiaan J. J.
Published: October 2010

Predictive modeling can be a valuable tool for systems designers, allowing them to capture and reuse knowledge from a set of observed data related to their system. An important challenge associated with predictive modeling is that of describing the domain over which model predictions are valid. This is necessary to avoid extrapolating beyond the original data, particularly when designers use predictive models in concert with optimizers or other computational routines that search a model’s input space automatically. The general problem of domain description is complicated by the characteristics of observational data sets, which can contain small numbers of samples, can have nonlinear associations among the variables, can be nonconvex, and can occur in disjoint clusters. Support vector machine (SVM) techniques, developed originally in the machine learning community, offer a solution to this problem. This paper is a description of a kernel-based SVM approach that yields a formal mathematical description of the valid input domain of a predictive model. The approach also provides for cluster analysis, which can lead to improved model accuracy through the decomposition of a data set into multiple subsets that designers can model independently. This paper includes a mathematical presentation of kernel-based SVM methods, an explanation of the procedure for applying the approach to predictive modeling problems, and illustrative examples for applying and using the approach in systems design.
Analytical Determination of Basic Machine-Tool Settings for Generation of Spiral Bevel Gears From Blank Data
Authors: Gonzalez-Perez Ignacio , Fuentes Alfonso , Hayasaka Kenichi
Published: October 2010

An approach for analytical determination of basic machine-tool settings for generation of spiral bevel gears from blank data is proposed. Generation by face-milling is considered. The analytical procedure is based on the similitudes between the conditions of generation between the gear member and its head-cutter and the conditions of imaginary meshing between the gear member and its crown gear. The blank data considered are the number of teeth of the pinion and the gear, the module, the spiral and pressure angles, the face width, the shaft angle, the depth factor, the clearance factor, and the mean addendum factor. These starting data can be established following the directions of the Standard ANSI/AGMA 2005-D03. Once the gear machine-tool settings are determined, an existing approach of local synthesis is applied to determine the pinion machine-tool settings that provide the desired conditions of meshing and contact of the gear drive. The developed theory is illustrated with a numerical example.
Pure Squeeze Motion in a Magneto-Elastohydrodynamic Lubricated Spherical Conjunction
Authors: Chu Li-Ming , Lin Jaw-Ren , Li Wang-Long , Chang Yuh-Ping
Published: October 2010

The pure squeeze magneto-elastohydrodynamic lubrication (MEHL) motion of circular contacts with an electrically conducting fluid in the presence of a transverse magnetic field is explored under constant load condition. The differences between classical elastohydrodynamic lubrication and MEHL are discussed. The results reveal that the effect of an externally applied magnetic field is equivalent to enhancing effective lubricant viscosity. Therefore, as the Hartmann number increases, the enhancing effect becomes more obvious. Furthermore, the transient pressure profiles, film shapes, normal squeeze velocities, and effective viscosity during the pure squeeze process under various operating conditions are discussed.
Elastic Averaging in Flexure Mechanisms: A Three-Beam Parallelogram Flexure Case Study
Authors: Awtar Shorya , Shimotsu Kevin , Sen Shiladitya
Published: October 2010

Redundant constraints are generally avoided in mechanism design because they can lead to binding or loss in expected mobility. However, in certain distributed-compliance flexure mechanism geometries, this problem is mitigated by the phenomenon of elastic averaging. Elastic averaging is a design paradigm that, in contrast with exact constraint design principles, makes deliberate and effective use of redundant constraints to improve performance and robustness. The principle of elastic averaging and its advantages are illustrated in this paper by means of a three-beam parallelogram flexure mechanism, which represents an overconstrained geometry. In a lumped-compliance configuration, this mechanism is prone to binding in the presence of nominal manufacturing and assembly errors. However, with an increasing degree of distributed-compliance, the mechanism is shown to become more tolerant to such geometric imperfections. The nonlinear elastokinematic effect in the constituent beams is shown to play an important role in analytically predicting the consequences of overconstraint and provides a mathematical basis for elastic averaging. A generalized beam constraint model is used for these predictions so that varying degrees of distributed compliance are captured using a single geometric parameter. The closed-form analytical results are validated against finite element analysis, as well as experimental measurements.
Discrete Time Transfer Matrix Method for Dynamic Modeling of Complex Spacecraft With Flexible Appendages
Authors: Rong Bao , Rui Xiaoting , Yu Hailong , Wang Guoping
Published: October 2010

Efficient, precise dynamic analysis for a complex spacecraft has become a research focus in the field of spacecraft dynamics. In this paper, by combining discrete time transfer matrix method of multibody system and finite element method, the transfer equations and transfer matrices of typical elements of spacecrafts are developed, and a high-efficient dynamic modeling method is developed for high-speed computation of spacecraft dynamics. Compared with ordinary dynamic methods, the proposed method does not need the global dynamic equations of system and has the low order of system matrix, high computational efficiency. This method has more advantages for dynamic modeling and real-time control of complex spacecrafts. Formulations of the proposed method as well as a numerical example of a spacecraft with a flexible solar panel are given to validate the method.
Two New Implicit Numerical Methods for the Fractional Cable Equation
Authors: Liu Fawang , Yang Qianqian , Turner Ian
Published: October 2010

The cable equation is one of the most fundamental equations for modeling neuronal dynamics. Cable equations with fractional order temporal operators have been introduced to model electrotonic properties of spiny neuronal dendrites. In this paper, we consider the following fractional cable equation involving two fractional temporal derivatives: ∂u(x,t)/∂t=D0t1−γ1(κ(∂2u(x,t)/∂x2))−μ02Dt1−γ2u(x,t)+f(x,t), where 0<γ1, γ2<1, κ>0, and μ02 are constants, and D0t1−γu(x,t) is the Rieman–Liouville fractional partial derivative of order 1−γ. Two new implicit numerical methods with convergence order O(τ+h2) and O(τ2+h2) for the fractional cable equation are proposed, respectively, where τ and h are the time and space step sizes. The stability and convergence of these methods are investigated using the energy method. Finally, numerical results are given to demonstrate the effectiveness of both implicit numerical methods. These techniques can also be applied to solve other types of anomalous subdiffusion problems.
Quantification of Perceived Environmental Friendliness for Vehicle Silhouette Design
Authors: Reid Tahira N. , Gonzalez Richard D. , Papalambros Panos Y.
Published: October 2010

Quantification of subjective attributes expressed as functions of design variables is a significant challenge in creating product design optimization models. For example, the objective assessment of a vehicle’s environmental friendliness is typically based on fuel economy and emissions. But some design variables such as a vehicle’s silhouette (two-dimensional body shape) may create a subjective perception of environmental friendliness, which may impact consumer preference along with objective metrics. In this paper, we show a method for assessing subjective attributes in the context of design attributes. We focus on perceived environmental friendliness (PEF) and we develop a model of PEF as a function of vehicle silhouette shape variables. The modeling process consists of stimuli development using design of experiments, survey design including direct assessment of the key subjective attribute PEF, elicitation of consumer preference, measurement of purported subjective mechanisms (for the PEF case, whether the design is “inspired by nature”), measurement of respondent characteristics (for the PEF case, environmental attitudes and demographics), statistical analysis of data, and validation. Results for the PEF example indicate that silhouettes perceived as environmentally friendly are the most preferred. Design variables that correlated with PEF were identified and used to generate new designs, which were validated in a follow-up study. Implications of using the general methodology in engineering design are discussed.
Random Field Characterization Considering Statistical Dependence for Probability Analysis and Design
Authors: Xi Zhimin , Youn Byeng D. , Hu Chao
Published: October 2010

The proper orthogonal decomposition method has been employed to extract the important field signatures of random field observed in an engineering product or process. Our preliminary study found that the coefficients of the signatures are statistically uncorrelated but may be dependent. To this point, the statistical dependence of the coefficients has been ignored in the random field characterization for probability analysis and design. This paper thus proposes an effective random field characterization method that can account for the statistical dependence among the coefficients for probability analysis and design. The proposed approach has two technical contributions. The first contribution is the development of a natural approximation scheme of random field while preserving prescribed approximation accuracy. The coefficients of the signatures can be modeled as random field variables, and their statistical properties are identified using the chi-square goodness-of-fit test. Then, as the paper’s second technical contribution, the Rosenblatt transformation is employed to transform the statistically dependent random field variables into statistically independent random field variables. The number of the transformation sequences exponentially increases as the number of random field variables becomes large. It was found that improper selection of a transformation sequence among many may introduce high nonlinearity into system responses, which may result in inaccuracy in probability analysis and design. Hence, this paper proposes a novel procedure of determining an optimal sequence of the Rosenblatt transformation that introduces the least degree of nonlinearity into the system response. The proposed random field characterization can be integrated with any advanced probability analysis method, such as the eigenvector dimension reduction method or polynomial chaos expansion method. Three structural examples, including a microelectromechanical system bistable mechanism, are used to demonstrate the effectiveness of the proposed approach. The results show that the statistical dependence in the random field characterization cannot be neglected during probability analysis and design. Moreover, it is shown that the proposed random field approach is very accurate and efficient.
Simulation-Based Robust Design of Multiscale Products
Authors: Ruderman Alex , Choi Seung-Kyum , Patel Jiten , Kumar Abhishek , Allen Janet K.
Published: October 2010

The current research proposes an integrated framework for product design that incorporates simulation-based tools into the early design stage to achieve optimum multiscale systems. The method to determine the appropriate cellular material-property relations for the internal material structures of the system is through a topology optimization technique and a multiscale design process. Specifically, the reliability-based topology optimization (RBTO) and a multi-attribute decision design method are integrated into the inductive design exploration method (IDEM). The RBTO method is introduced to determine optimal topologies at the mesoscale. The multi-attribute decision design method is used for decision support in the design process of the macroscale systems. IDEM offers the capability for concurrent design on multiple scales providing an approach for the integration of the other two methods. An example of the developed multiscale design framework is presented in terms of a hydrogen storage tank used in a hydrogen fuel cell for automotive applications. The multiscale tank design will feature a high strength cellular structured wall, resulting in a large weight reduction.
Impact of a Fixed-Length Rigid Cylinder on an Elastic-Plastic Homogeneous Body
Authors: Katta Raja R. , Polycarpou Andreas A.
Published: October 2010

A contact mechanics (CM) based model of a fixed-length rigid cylinder impacting a homogeneous elastic-plastic homogeneous body was developed and includes an improved method of estimating the residual depth after impact. The nonlinear elastic behavior during unloading was accounted for to develop an improved coefficient of restitution model. The impact model was applied to study a practical case of a cylindrical feature on the slider of a magnetic storage hard disk drive impacting the disk to predict various critical impact contact parameters. The CM model was validated using a plane strain finite element model and it was found that a cylindrical feature with a longer length results in a substantial alleviation of impact damage.
Structural Design and Analysis of the Toroidal Heliostat
Authors: Zang Chuncheng , Wang Zhifeng , Liang Wenfeng , Wang Xiaoyu
Published: October 2010

Heliostat is an important component in the solar power tower station because its cost, optical performance, and mechanical performance have great influence on the overall property evaluation of the station. The T-shape heliostat tracking the sun in the azimuth-elevation mode has been commonly developed and successfully applied in many stations. In recent years, some researchers have developed spinning-elevation heliostats and have analyzed their optical performance. In this paper, the structure of a 16 m2 toroidal heliostat tracking the sun in the spinning-elevation mode is designed, and the mechanical performance of the structure under wind load is analyzed by means of the finite element method. The trends of force, moments, and vibration modes with the change in elevation have been presented, and the classic status is analyzed in detail when their maximum values occur. Furthermore, the advantages and disadvantages of a toroidal heliostat in reducing the cost are discussed compared with those of a traditional T-shape heliostat.
Numerical Continuation in a Physical Experiment: Investigation of a Nonlinear Energy Harvester
Authors: Barton David A. W. , Burrow Stephen G.
Published: October 2010

In this paper, we demonstrate the use of control-based continuation within a physical experiment: a nonlinear energy harvester, which is used to convert vibrational energy into usable electrical energy. By employing the methodology of Sieber et al. (2008, “Experimental Continuation of Periodic Orbits Through a Fold,” Phys. Rev. Lett., 100(24), p. 244101), a branch of periodic orbits is continued through a saddle-node bifurcation and along the associated branch of unstable periodic orbits using a modified time-delay controller. At each step in the continuation, the pseudo-arclength equation is appended to a set of equations that ensure that the controller is noninvasive. The resulting nonlinear system is solved using a quasi-Newton iteration, where each evaluation of the nonlinear system requires changing the excitation parameters of the experiment and measuring the response. We present the continuation results for the energy harvester in a number of different configurations.
Wave Propagation in Periodic Composites: Higher-Order Asymptotic Analysis Versus Plane-Wave Expansions Method
Authors: Andrianov I. V. , Awrejcewicz J. , Danishevs’kyy V. V. , Weichert D.
Published: October 2010

This work is devoted to a comparison of different methods determining stop-bands in 1D and 2D periodic heterogeneous media. For a 1D case, the well-known dispersion equation is studied via asymptotic approach. In particular, we show how homogenized solutions can be obtained by elementary series used up to any higher-order. We illustrate and discuss a possible application of asymptotic series regarding parameters other than wavelength and frequency. In addition, we study antiplane elastic shear waves propagating in the plane through a spatially infinite periodic composite material consisting of an infinite matrix and a square lattice of circular inclusions. In order to solve the problem, a homogenization method matched with asymptotic solution on the cell with inclusion of the large volume fracture is proposed and successfully applied. First and second approximation terms of the averaging method provide the estimation of the first stop-band. For validity and comparison with other approaches, we have also applied the Fourier method. The Fourier method is shown to work well for relatively small inclusions, i.e., when the inclusion-associated parameters and matrices slightly differ from each other. However, for evidently contrasting structures and for large inclusions, a higher-order homogenization method is advantageous. Therefore, a higher-order homogenization method and the Fourier analysis can be treated as mutually complementary.
Experimental Studies Using Response Surface Methodology for Condition Monitoring of Ball Bearings
Authors: Patil M. S. , Mathew Jose , Rajendrakumar P. K. , Karade Sumit
Published: October 2010

The presence of defect in the bearing (outer race, inner race, or ball) results in increased vibrations. Time domain indices such as rms, crest factor, and kurtosis are some of the important parameters used to monitor the condition of the bearing. Radial load and operating speed also have an important role in bearing vibrations. The interaction between the defect size, load, and speed helps to study their effect on vibrations more effectively. Response surface methodology (RSM) is a combination of statistical and mathematical techniques to represent the relationship between the inputs and the outputs of a physical system. But so far, the literature related to its application in bearing damage identification is scarce. The proposed study uses RSM to study the influence of defect size, load, and speed on the bearing vibrations. Kurtosis is used as response factor. Experiments are planned using Box Behnken design procedure. Experiments are performed using 6305 ball bearings and the results have been presented. MINITAB statistical software is used for analysis. It is seen from the analysis of the experimental results that the defect size, interaction effect of defect size and load, and interaction effect of defect size and speed are significant. Response surface method using Box Behnken design and analysis of variance has proved to be a successful technique to assess the significant factors related to bearing vibrations.
A Microstructurally Driven Model for Pulmonary Artery Tissue
Authors: Kao Philip H. , Lammers Steven R. , Tian Lian , Hunter Kendall , Stenmark Kurt R. , Shandas Robin , Qi H. Jerry
Published: October 2010

A new constitutive model for elastic, proximal pulmonary artery tissue is presented here, called the total crimped fiber model. This model is based on the material and microstructural properties of the two main, passive, load-bearing components of the artery wall, elastin, and collagen. Elastin matrix proteins are modeled with an orthotropic neo-Hookean material. High stretch behavior is governed by an orthotropic crimped fiber material modeled as a planar sinusoidal linear elastic beam, which represents collagen fiber deformations. Collagen-dependent artery orthotropy is defined by a structure tensor representing the effective orientation distribution of collagen fiber bundles. Therefore, every parameter of the total crimped fiber model is correlated with either a physiologic structure or geometry or is a mechanically measured material property of the composite tissue. Further, by incorporating elastin orthotropy, this model better represents the mechanics of arterial tissue deformation. These advancements result in a microstructural total crimped fiber model of pulmonary artery tissue mechanics, which demonstrates good quality of fit and flexibility for modeling varied mechanical behaviors encountered in disease states.
Characterizing the Interaction Among Bullet, Body Armor, and Human and Surrogate Targets
Authors: Shen Weixin , Niu Yuqing , Bykanova Lucy , Laurence Peter , Link Norman
Published: October 2010

This study used a combined experimental and modeling approach to characterize and quantify the interaction among bullet, body armor, and human surrogate targets during the 10–1000 μs range that is crucial to evaluating the protective effectiveness of body armor against blunt injuries. Ballistic tests incorporating high-speed flash X-ray measurements were performed to acquire the deformations of bullets and body armor samples placed against ballistic clay and gelatin targets with images taken between 10 μs and 1 ms of the initial impact. Finite element models (FEMs) of bullet, armor, and gelatin and clay targets were developed with material parameters selected to best fit model calculations to the test measurements. FEMs of bullet and armor interactions were then assembled with a FEM of a human torso and FEMs of clay and gelatin blocks in the shape of a human torso to examine the effects of target material and geometry on the interaction. Test and simulation results revealed three distinct loading phases during the interaction. In the first phase, the bullet was significantly slowed in about 60 μs as it transferred a major portion of its energy into the body armor. In the second phase, fibers inside the armor were pulled toward the point of impact and kept on absorbing energy until about 100 μs after the initial impact when energy absorption reached its peak. In the third phase, the deformation on the armor’s back face continued to grow and energies inside both armor and targets redistributed through wave propagation. The results indicated that armor deformation and energy absorption in the second and third phases were significantly affected by the material properties (density and stiffness) and geometrical characteristics (curvature and gap at the armor-target interface) of the targets. Valid surrogate targets for testing the ballistic resistance of the armor need to account for these factors and produce the same armor deformation and energy absorption as on a human torso until at least about 100 μs (maximum armor energy absorption) or more preferably 300 μs (maximum armor deformation).
Geometric Characterization of Cell Membrane of Mouse Oocytes for ICSI
Authors: Diaz Jhon F. , Karzar-Jeddi Mehdi , Olgac Nejat , Fan Tai-Hsi , Ergenc Ali Fuat
Published: October 2010

Intracytoplasmic sperm injection (ICSI) is a broadly utilized assisted reproductive technology. A number of technologies for this procedure have evolved lately, such as the most commonly utilized piezo-assisted ICSI technique (P-ICSI). An important problem with this technique, however, is that it requires a small amount of mercury to stabilize the tip of the penetration micropipette. A completely different and mercury-free injection technology, called the rotationally oscillating drill (Ros-Drill©) (RD-ICSI), was recently developed. It uses microprocessor-controlled rotational oscillations of a spiked micropipette after the pipette deforms the membrane to a certain tension level. Inappropriate selection of this initiation instant typically results in cell damage, which ultimately leads to unsuccessful ICSI. During earlier manual clinical tests of Ros-Drill, the technicians’ expertise determined this instant in an ad hoc fashion. In this paper, we introduce a computer-vision-based tool to mechanize this process with the objective of maintaining the repeatability and introducing potential automation. Computer images are used for monitoring the membrane deformations and curvature variations as the basis for decision making. The main contribution of this paper is in the specifics of the computer logic to perform the monitoring. These new tools are expected to provide a practicable means for automating the Ros-Drill-assisted ICSI operation.
Complex dielectric function and refractive index spectra of epitaxial CdO thin film grown on r-plane sapphire from 0.74 to 6.45 eV
Authors: Choi S. G. , Zúñiga-Pérez J. , Muñoz-Sanjosé V. , Norman A. G. , Perkins C. L. , Levi D. H.
Published: October 2010

The authors report ellipsometrically determined optical properties of epitaxial cadmium oxide thin film grown by metal-organic vapor phase epitaxy on r-plane sapphire substrate. The ellipsometric data were collected from 0.74 to 6.45 eV with the sample at room temperature. Artifacts from the surface overlayers were reduced as far as possible by the premeasurement surface treatment procedures. Complex dielectric function ε=ε1+iε2 and refractive index N=n+ik spectra were extracted from multilayer modeling of the data with the B-spline functions.
Atmospheric CO
2
: Principal Control Knob Governing Earth’s Temperature
Authors: Lacis Andrew A. , Schmidt Gavin A. , Rind David , Ruedy Reto A.
Published: October 2010

Turning Up the Heat

The physical effect of atmospheric carbon dioxide on Earth's energy budget—that is, its “greenhouse effect”—has been understood for more than 100 years, but its role in climate warming is still not universally accepted.

Lacis
et al.

(p.
356
) conducted a set of idealized climate model experiments in which various greenhouse gases were added to or subtracted from the atmosphere in order to illustrate their roles in controlling the temperature of the air. The findings clearly show that carbon dioxide exerts the most control on Earth's climate, and that its abundance determines how much water vapor the atmosphere contains, even though the radiative effect of the water vapor is greater than that of carbon dioxide itself.
Our Evolving View of Childhood
The Evolution of Childhood
Relationships, Emotion, Mind

by Melvin Konner

Harvard University Press, Cambridge, MA, 2010. 959 pp. $39.95, £29.95, €36. ISBN 9780674045668.
Authors: Gopnik Alison
Published: October 2010

Combining findings on evolution, maturation, socialization, and culture, Konner offers a broad-based explanation of how biology underlies "normally developing social behavior."
Filling the Light Pipe
Authors: Richardson David J.
Published: October 2010

As data transmission rates continue to increase, optoelectronic engineers are developing techniques to deal with the approaching “capacity crunch.”
Dom34:Hbs1 Promotes Subunit Dissociation and Peptidyl-tRNA Drop-Off to Initiate No-Go Decay
Authors: Shoemaker Christopher J. , Eyler Daniel E. , Green Rachel
Published: October 2010

Stop, No-Go

The decoding of messenger RNA (mRNA) into protein by eukaryotic ribosomes is constantly monitored to prevent errors. As well as mechanisms that detect and degrade messages with premature stop codons, no-go decay (NGD) results in the degradation of mRNA with inhibitory secondary structure or chemical damage.

Shoemaker
et al.

(p.
369
) show that in
Saccharomyces cerevisiae
the protein complex formed between Dom34 and Hbs1 is involved in NGD. The complex acts as a translational “reset button,” recognizing failed translation events and initiating an abortive program that results in the destruction of the stalled mRNA.
Comment on “Narrow Primary Feather Rachises in
Confuciusornis
and
Archaeopteryx
Suggest Poor Flight Ability”
Authors: Paul Gregory S.
Published: October 2010

Nudds and Dyke (Reports, 14 May 2010, p. 887) reported that the primary features of the early birds
Archaeopteryx
and
Confuciusornis
were too weak to power flight. This conclusion is not supported because the authors overestimated the mass of the subjects and understated the strength of the primary shafts in at least one example. The total biology of the birds indicates that they could achieve flapping flight.
Comment on “Narrow Primary Feather Rachises in
Confuciusornis
and
Archaeopteryx
Suggest Poor Flight Ability”
Authors: Zheng Xiaoting , Xu Xing , Zhou Zhonghe , Miao Desui , Zhang Fucheng
Published: October 2010

Nudds and Dyke (Reports, 14 May 2010, p. 887) compared the rachis diameters of the primary feathers of
Archaeopteryx
and
Confuciusornis
to those of modern birds and found that the primary feathers of these two basal birds were too weak to support sustained flight. Our measurements of
Confuciusornis
specimens suggest that their conclusions need to be further evaluated.
Selection at Linked Sites Shapes Heritable Phenotypic Variation in
C. elegans
Authors: Rockman Matthew V. , Skrovanek Sonja S. , Kruglyak Leonid
Published: October 2010

Selection and Variation

In order to understand adaptation and evolution, it is necessary to understand the relationship between natural phenotypic variation and population genetics.

Rockman
et al.

(p.
372
; see the Perspective by

Charlesworth

) examined the level of genetic variance affecting gene expression through the comparison of two strains of the nematode
Caenorhabditis elegans
. Surprisingly, the variation observed in each trait was better explained by the genomic pattern of background selection than by selection on the traits themselves. Thus, the removal of deleterious mutations from the population by selection reduces phenotypic variability caused by genetic variation at closely linked neutral or nearly neutral sites, and quantitative variability in gene expression shows a similar pattern to sequence diversity and is affected by local rates of genetic recombination and the effective population size.
The Structure of Iron in Earth’s Inner Core
Authors: Tateno Shigehiko , Hirose Kei , Ohishi Yasuo , Tatsumi Yoshiyuki
Published: October 2010

Packing the Core

The packing and arrangement of atoms in Earth's solid inner core can dictate processes such as core growth and rotation. Seismology and modeling suggest the inner core is composed primarily of iron, but the structure is less clear due to anisotropic splitting of seismic waves.

Tateno
et al.

(p.
359
) performed static compression experiments on pure iron at the extremely high pressures and temperatures found in the inner core and saw that iron prefers a hexagonal close-packed structure, as opposed to cubic structures. The results help to explain the observed seismic anisotropy, and also suggest that individual iron crystals in the core may prefer orienting themselves with their long crystallographic axes parallel to Earth's rotation axis.
Room-Temperature Detection of a Single Molecule’s Absorption by Photothermal Contrast
Authors: Gaiduk A. , Yorulmaz M. , Ruijgrok P. V. , Orrit M.
Published: October 2010

Hot Enough to See

Over the last decade, detection of fluorescence from individual molecules has allowed for increasingly detailed probing of biochemical reaction mechanisms. The key advantage of fluorescence detection is the absence of background; the signal appears as a glowing point in a void. However, not all molecules fluoresce, and so alternative detection methods are needed.

Gaiduk
et al.

(p.
353
) now show that a photothermal detection scheme can resolve absorption events by individual molecular dyes that exhibit poor fluorescence efficiency. The technique relies on each molecule's release of heat to the surrounding solvent after light absorption, an energy dissipation mechanism that is enhanced as fluorescence efficiency declines. The solvent heating alters the local refractive index just enough to scatter a portion of a probe beam backwards, revealing the absorption.
Intravascular Danger Signals Guide Neutrophils to Sites of Sterile Inflammation
Authors: McDonald Braedon , Pittman Keir , Menezes Gustavo B. , Hirota Simon A. , Slaba Ingrid , Waterhouse Christopher C. M. , Beck Paul L. , Muruve Daniel A. , Kubes Paul
Published: October 2010

Inflammation Response in Living Color

Besides responding to microbial infection, our immune system also plays an important role in responding to sterile injury, for example, during trauma or organ necrosis. In a mouse model of sterile liver inflammation,

McDonald
et al.

(p.
362
) used dynamic in vivo imaging to visualize the innate immune response, which is dominated by neutrophils. Neutrophils were rapidly recruited to the site of inflammation through intravascular channels. Adenosine triphosphate generated from necrotic cells at the injury site and the Nlrp3 inflammasome were required for neutrophils to exit the circulation into the vascular endothelium, where they used integrins to adhere. A luminal chemokine gradient guided integrin-dependent, intravascular migration toward the site of injury. Finally, formyl peptides provided a signal to override the chemokine gradient and draw neutrophils into the site of injury.
Recasting Metal Alloy Phases with Block Copolymers
Authors: Peterca Mihai , Percec Virgil
Published: October 2010

Highly complex metal alloy phases have been replicated at a larger scale with spherical aggregates formed from polymers.
Stopping the Stones
Authors: Coe Fredric L. , Asplin John R.
Published: October 2010

Compounds that prevent the crystallization of an amino acid may represent a new class of therapeutic agent for kidney stones.
Variation Catches a Ride
Authors: Charlesworth Brian
Published: October 2010

Genetic hitchhiking appears to shape variability in quantitative traits
Descended from Refuse
Espèces en voie d'apparition [Species About to Evolve]
OEuvres de François Riou, Muséum d'Histoire Naturelle Neuchâtel, Neuchâtel, Switzerland. Through 9 January 2011. www.museum-neuchatel.ch/new/navigation.php?cat=5
Authors: Junier Thomas , Junier Pilar
Published: October 2010

Rious has assembled a diverse fauna from scraps of everyday human implements.
Three Laureates Explained Why Unemployment Is Inevitable
Authors: Cho Adrian
Published: October 2010

Peter Diamond, Dale Mortensen, and Christopher Pissarides won this year's Sveriges Riksbank Prize in Economic Sciences in Memory of Alfred Nobel for laying out the theory that explains why full employment is impossible.
Climate Talks Still at Impasse, China Buffs Its Green Reputation
Authors: Stone Richard
Published: October 2010

Amid the pessimism and recriminations at a United Nations meeting in Tianjin, China, last week, one nation won praise from observers for its efforts to boost energy efficiency and invest in green technologies: the host, China.
Better Intro Courses Seen as Key to Reducing Attrition of STEM Majors
Authors: Mervis Jeffrey
Published: October 2010

A new report from the National Academies says that improving introductory courses is one of many steps needed to increase the number of students obtaining degrees in the fields of science, technology, engineering, and mathematics and, in particular, the percentage of minorities in the scientific and engineering workforce.
PTEN Deficiency in Endometrioid Endometrial Adenocarcinomas Predicts Sensitivity to PARP Inhibitors
Authors: Dedes Konstantin J. , Wetterskog Daniel , Mendes-Pereira Ana M. , Natrajan Rachael , Lambros Maryou B. , Geyer Felipe C. , Vatcheva Radost , Savage Kay , Mackay Alan , Lord Christopher J. , Ashworth Alan , Reis-Filho Jorge S.
Published: October 2010

Endometrioid endometrial cancer cell lines harboring PTEN loss of function have impaired homologous recombination response to DNA double-strand breaks and show an exquisite sensitivity to PARP inhibition.
Detection of Saxitoxin-Producing Cyanobacteria and
Anabaena circinalis
in Environmental Water Blooms by Quantitative PCR
Authors: Al-Tebrineh Jamal , Mihali Troco Kaan , Pomati Francesco , Neilan Brett A.
Published: October 2010

Saxitoxins (STXs) are carbamate alkaloid neurotoxins produced by marine “red tide” dinoflagellates and several species of freshwater filamentous cyanobacteria, including
Anabaena circinalis
,
Aphanizomenon
spp.,
Lyngbya wollei
, and
Cylindrospermopsis raciborskii
. A specific quantitative PCR (qPCR) method based on SYBR green chemistry was developed to quantify saxitoxin-producing
Anabaena circinalis
cyanobacteria, which are major bloom-forming freshwater cyanobacteria. The aim of this study was to infer the potential toxigenicity of samples by determining the copy number of a unique and unusual polyketide synthase (PKS) sequence (
sxtA
) in the STX biosynthesis gene cluster identified in cyanobacteria. Our qPCR approach was applied to water samples collected from different Australian lakes, dams, and rivers. The STX concentration and cyanobacterial cell density of these blooms were also determined by high-pressure liquid chromatography (HPLC) and microscopic cell counting, respectively. STX concentrations correlated positively with STX gene copy numbers, indicating that the latter can be used as a measure of potential toxigenicity in
Anabaena circinalis
and possibly other cyanobacterial blooms. The qPCR method targeting STX genes can also be employed for both monitoring and ecophysiological studies of toxic
Anabaena circinalis
blooms and potentially several other STX-producing cyanobacteria.
Repression of Antibiotic Production and Sporulation inStreptomyces coelicolorby Overexpression of a TetR Family Transcriptional Regulator
Authors: Xu Delin , Seghezzi Nicolas , Esnault Catherine , Virolle Marie-Joelle
Published: October 2010

The overexpression of a regulatory gene of the TetR family (SCO3201) originating either fromStreptomyces lividansor fromStreptomyces coelicolorwas shown to strongly repress antibiotic production (calcium-dependent antibiotic [CDA], undecylprodigiosin [RED], and actinorhodin [ACT]) ofS. coelicolorand of theppkmutant strain ofS. lividans. Curiously, the overexpression of this gene also had a strong inhibitory effect on the sporulation process ofS. coelicolorbut not on that ofS. lividans. SCO3201 was shown to negatively regulate its own transcription, and its DNA binding motif was found to overlap its −35 promoter sequence. The interruption of this gene inS. lividansorS. coelicolordid not lead to any obvious phenotypes, indicating that when overexpressed SCO3201 likely controls the expression of target genes of other TetR regulators involved in the regulation of the metabolic and morphological differentiation process inS. coelicolor. The direct and functional interaction of SCO3201 with the promoter region ofscbA, a gene under the positive control of the TetR-like regulator, ScbR, was indeed demonstrated byin vitroas well asin vivoapproaches.
Chimeric Lactase Capable of Spontaneous and Strong Immobilization on Cellulose and Development of a Continuous-Flow System for Lactose Hydrolysis at High Temperatures
Authors: Velikodvorskaya G. A. , Tikhonova T. V. , Gurvits I. D. , Karyagina A. S. , Lavrova N. V. , Sergienko O. V. , Tashlitskii V. N. , Lunina N. A. , Lunin V. G.
Published: October 2010

Recombinant plasmids containing fusion proteins composed of two different modules were constructed and expressed in
Escherichia coli
. The modules encoded the lactase LacA (LacZ) from the thermophilic bacterium
Thermoanaerobacter ethanolicus
and the cellulase CelD, a cellulose-binding module (CBM) from
Anaerocellum thermophilum
. The CelD CBM provides a spontaneous and strong sorption of the fusion proteins onto a cellulose carrier. The enzymatic activities of both the free LacA protein and LacA-CelD CBM fusion proteins immobilized onto the cellulose carrier were assessed. The LacA activity of the fusion protein was dependent upon its position with respect to the CBM. The highest level of lactase activity and stability was observed when the lactase domain was localized at its N terminus. A continuous-flow column reactor of lactase immobilized on a cellulose carrier was constructed, and its activity was assessed. The lactose hydrolysis rate for a 150 mM (5%) solution at a flow rate of 1 reactor volume per min was 75%, which is a value optimal for further whey transformation into glucose/galactose syrup.