bluuebunny/crossref_metadata_2025 huggingface dataset:
Metamorphic Rock‐hosted Disseminated Gold Deposits—A Case Study of the Xiaotongjiapuzi Gold Deposit of Eastern Liaoning
Authors: Guoping LIU , Yongfu AI , Kezhu FENG , Zhimin ZHANG
Published: November 2010

Abstract The Xiaotongjiapuzi gold deposit occurs in a Palaeoproterozoic rift accretionary terrane in eastern Liaoning and is hosted by a carbonate formation of the Dashiqiao Formation, Liaohe Group. The metamorphic grade of the host rock is low amphibolite‐high greenschist facies. Gold, which is mainly invisible, is distributed in pyrite and arsenopyrite. The grains of Au‐bearing sulphide minerals are fine, ranging from 0.0 n to 1 mm. The wall‐rock alterations are characterized by low‐temperature silification, hydro‐sericitization, sericitization and carbonatization. The homogenization temperatures of the fluid inclusions in quartz closely associated with gold mineralization range from 140 to 240°C. The metallogenic age represented by the Ar‐Ar isotopic age of sericite is 167 Ma. Comparisons and studies show that the Xiaotongjiapuzi gold deposit can be classified as the submicron‐sized disseminated deposit (analogous to the Carlin‐type) hosted in metamorphic rocks.
Fractal and Multifractal Properties of the Spatial Distribution of Natural Fractures—Analyses and Applications
Authors: Jiandong XU , Guosheng QU , JACOBI Robert D.
Published: November 2010

Abstract The Cantor's dust theory is applied to investigate the scaling properites of the spatial distribution of natural fractures obtained from detailed scanline surveys of 27 field sites in the Appalachian Plateau of western New York, USA. The results obtained in this study indicate: 1) fracture spacing is characterized by fractal and multifractal properties. On small scales analyses yield an average fractal dimension of 0.15, which suggests a very high degree of clustering. In contrast, on large scales, fractures tend to be more regular and evenly distributed with an average fracture dimension of 0.52; 2) fractal dimension varies with different sets in different orientations, which can be attributed to interactions between pre‐existing fractures and younger ones, as well as variations of the intensity of the stresses under which the fractures were formed; 3) a time sequence of fracture set formation can be proposed based on fractal and multifractal analyses, which consists of (from old to young): N‐S, NW, ENE, and NE‐striking sets. This time sequence is confirmed by the study of the abutting relationships of different fracture sets observed in the field.
A New Protoceratopsid (Dinosauria: Neoceratopsia) from the Late Cretaceous of Inner Mongolia, China
Authors: Hailu YOU , Zhiming DONG
Published: November 2010

Abstract  An almost complete skull, which was collected from the Upper Cretaceous of the Bayan Mandahu area in Inner Mongolia, China by the Sino‐Canadian Dinosaur Project, is described and assigned to a new genus of protoceratopsid dinosaur, Magnirostris dodsoni gen. et sp. nov. This new taxon is distinguished from other protoceratopsids by the robust rostral bone and the existence of incipient orbital horn cores. The existence of an additional antorbital fenestra indicates a close relationship between Magnirostris and Bagaceratops.
An X‐Ray Diffraction Study of an Inclusion in Diamond from the Luobusha Chromite Deposit in Tibet, China
Authors: Nicheng SHI , Wenji BAI , Zhesheng MA , Qingsong FANG , Ming XIONG , Binggang YAN , Mingquan DAI , Jingsui YANG
Published: November 2010

Abstract  Diamond was found in podiform chromitites of ophiolite and harzburgite from Luobusha, Tibet. There are silicate inclusions in some diamond grains from this area. In the present work, the CCD (charge coupled detector) technology of X‐ray powder diffraction was applied to the study of the inclusion in diamond from the ophiolite of Tibet. Diffraction patterns are obtained even though the inclusion is only 20 μm in crystal size. The results show that the inclusion in diamond consists of talc and clinochrysotile. Therefore, it is clear that the diamond from the ophiolite of Luobusha, Tibet, is natural diamond rather than a synthetic one.
Geochronology and Geochemical Characteristics of the Early Mesozoic Tangquan Pluton in Southwestern Fujian and Its Tectonic Implications
Authors: Jianren MAO , Qing HU , Naizheng XU , Fanggui XIE , Kuiyuan TAO
Published: November 2010

Abstract  The Tangquan granodioritic pluton in Datian County, southwestern Fujian, China, which extends in a NE direction with an exposed area of about 130 km2, used to be considered a product of Early Cretaceous magmatism. The present study suggests for the first time that the pluton was formed in the Early Jurassic by using multiple methods for isotopic dating, which give zircon U‐Pb ages of 186.8 Ma and 179.0 Ma, Rb‐Sr isochron age of 162.02±4.5 Ma, and biotite 40Ar/39Ar plateau age of 158.1±0.7 Ma. The cooling rate for the pluton was relatively low (4.76°C/Ma) during the early stage (183–162 Ma) because of the compressional environment. It was emplaced in a higher cooling rate (50°C/Ma) in an extensional environment during the later stage (162–158 Ma). The granodiorites are metaluminous‐peraluminous, relatively enriched in Na2O and depleted in K2O, and characteristic of I‐type granites of crust‐mantle mixed sources. They are moderately enriched in Rb, Th, Hf and LREE, and depleted in Ti, Nb, Ta and Sr, and have geochemical features of cal‐alkaline rocks of an island arc or active continental margin. Their (87Sr/86Sr)i ratio varies from 0.70769 to 0.70822, εNd(t) from −9.68 to −10.07 and TDM from 1.52 to 1.55 Ga. They were formed by mixing of mantle‐derived mafic magma with the granitic magma resulting from partial melting of crust‐derived materials in an upwelling of the asthenospheric mantle in South China during the Early Mesozoic.
The Vanishing Shoulder: Rapidly Progressive Destructive Shoulder Chondrolysis
Authors: Ben-Galim Peleg , Rosenblatt Yishai , Haim Amir , Maman Eran , Mozes Martha , Mozes Gavriel
Published: November 2010

Idiopathic chondrolysis of the shoulder is an extremely rare condition. We report a unique case of glenohumeral joint chondrolysis which progressed rapidly, causing severe joint destruction. This catastrophic destructive process occurred within less than 1 month and resulted not only in the disappearance of the cartilage lining of the joint, but also in the destruction and deformation of the humeral head and some destruction of the glenoid. Clinical findings, radiographs, magnetic resonance imaging and nuclear scans are presented along with the histological findings, and a literature review.
Glenoid and Coracoid Morphology are Ideally Matched for the Congruent-Arc Latarjet
Authors: Gooding Benjamin W. T. , Cresswell Timothy R. , Sloan Roger , Du Toit Don F. , De Beer Joe
Published: November 2010

Background

The Congruent-Arc Latarjet is modification of the Latarjet open bony stabilisation for shoulder instability. It involves rotation of the coracoid so the curved under-surface lies congruent with the glenoid. The aim of this study was to define the relationship between the concave under surface of the coracoid and the glenoid.

Methods

An initial study of 210 cadaveric scapulae was performed followed by a study measuring the same curves using 3D CT reconstruction on 20 scapulae from living patients.

Results

Cadveric measurement revealed the glenoid's surface had a median radius of curvature of 30 mm and the coracoid had a median radius of curvature of 25 mm. The CT measurements revealed similar radii of curvature with the glenoid measuring 23.9 mm and the coracoid measuring 25.4 mm (p = 0.2488).

Conclusion

The curvature of the glenoid in the cadaveric specimens was slightly larger than the corresponding coracoid curvature. In life this difference may be minimised by articular cartilage, labrum and the attachment of capsule. The CT study revealed similar curves, although in contrast to the cadaveric specimens the coracoid curvature was slightly larger. Overall the curvature of the under surface of the coracoid is similar to the glenoid, which supports this modification of the Latarjet procedure.
Human control of an inverted pendulum: Is continuous control necessary? Is intermittent control effective? Is intermittent control physiological?
Authors: Loram Ian D. , Gollee Henrik , Lakie Martin , Gawthrop Peter J.
Published: November 2010

Non‐technical summary

Homeostasis, the physiological control of variables such as body position, is founded on negative feedback mechanisms. The default understanding, consistent with a wealth of knowledge related to peripheral reflexes, is that feedback mechanisms controlling body position act continuously. For more than fifty years, it has been assumed that sustained control of position is best interpreted using continuous paradigms from engineering control theory such as those which regulate speed in a vehicle ‘cruise control’ system. Using a joystick to control an unstable load that falls over like a person fainting, we show that control using intermittent gentle taps is natural, more effective and robust to unexpected changes than continuous hand contact, works best with two taps per second, and can explain the upper frequency limit of control by both methods. Serial ballistic control, limited to an optimum rate, provides a new physiological paradigm for interpreting sustained control of posture and movement.
Formation of the non‐functional and functional pools of granule cells in the dentate gyrus: role of neurogenesis, LTP and LTD
Authors: Lisman John
Published: November 2010

Some aspects of the function of the dentate gyrus (DG) and CA3 regions of the hippocampus are beginning to be understood, notably the way that grid cell inputs from the medial entorhinal cortex (MEC) are processed to form place cells in the dentate/CA3. However, one aspect of DG function remains very puzzling: more than 95% of the cells do not fire in any environment. Here, I propose a possible explanation for these non‐functional cells. Because of the competition mediated by feedback inhibition, only the most excited DG cells fire. Cells that do not spike nevertheless receive excitatory input from the grid cells of the MEC (these cells fire nearly continuously because they represent a property (space) that is always being processed). Experiments suggest that synapses on such cells will undergo long‐term depression (LTD). Cells that have their synapses weakened in this way are less likely to be winners in subsequent competitions. There may thus be a downward spiral in which losers eventually have no chance of winning and thus become non‐functional. On the other hand, cells that fire get stronger synapses, making them more likely to be subsequent winners. Because the long‐term potentiation (LTP) in these cells balances ongoing LTD, these cells will be relatively stable members of the functional pool. Although these pools are relatively stable, there will nevertheless be some chance that LTD converts a functional cell to a non‐functional one; in contrast, the probability of a reverse transition is near zero. Thus, without additional processes, there would be a slow reduction in the size of the functional pool. I suggest that the ongoing generation of new cells by neurogenesis may be a solution to this problem. These cells are highly excitable and may thus win the competition to fire. In this way, the functional pool will be replenished. To test this and other theories about the DG requires an understanding of the role of the DG in memory. Recent experimental and theoretical work is providing a better understanding of the unique memory functions of the DG/CA3 unit. This will provide a behavioural framework for testing the ideas proposed here.
Methodology and Tools to Support Knowledge Management in Topology Optimization
Authors: Muzzupappa Maurizio , Barbieri Loris , Bruno Fabio , Cugini Umberto
Published: November 2010

Topological optimization (TO) tools are today widely employed in several engineering fields (e.g., construction, aeronautics, aerospace, and automotive). The diffusion of these tools is due to their capacity to improve mechanical properties of products through a global optimization of the product in terms of weight, stiffness, strength, and cost. On the other hand, the adoption of TO tools still requires a sizeable organizational effort because, at present, these tools are mostly stand-alone and are not well integrated into the product development process (PDP). This paper presents an innovative methodology that supports designers and analysts in formalizing and transmitting design choices taken during project activities and in making the integration of TO tools in the PDP more efficient. The methodology clearly defines the roles, the activities, the data to exchange, and the software tools to be used in the process. Some custom computer-aided design automation tools have been implemented to improve the efficiency of the methodology. Moreover, this paper defines an original procedure to support the interpretation of the TO results.
Primary Surface Recuperator Alloy Oxidation: A Comparison of Accelerated Engine Testing to Field Operation
Authors: Matthews Wendy J. , More Karren L. , Walker Larry R.
Published: November 2010

The Capstone C65 Microturbine primary surface recuperator (PSR) core has been manufactured from Haynes alloy HR-120 since 2005 (Microturbine is a registered trademark of Capstone Turbine Corporation; Haynes and HR-120 are trademarks of Haynes International, Inc.). When exposed to the harsh operating environment of the microturbine PSR, HR-120 forms a protective oxide scale that is resistant to the effects of the water vapor present in the exhaust gas. Long-term accelerated microturbine testing with samples in a modified PSR with a removable aft dome is ongoing at an elevated turbine exit temperature (TET) ∼100°F higher than normal operation. The elevated TET test engine is operated at steady-state conditions, and the engine is shut down at predetermined intervals for sample removal. Material characterization of the elevated TET samples has been carried out by Capstone Turbine Corporation in collaboration with Oak Ridge National Laboratory. The surface oxide scale formation and associated alloy compositional changes have been evaluated for elevated TET samples with operating lives ranging from ∼1800 h to ∼26,500 h. In addition, field-operated HR-120 recuperators have been sectioned and samples have been evaluated for operating lives ranging from ∼5500 h to ∼18,000 h. Results from the microstructural and compositional analyses of both the long-term steady-state elevated TET HR-120 samples and the field-operated HR-120 recuperator samples will be presented and compared.
Influence of Transversal Acoustic Excitation of the Burner Approach Flow on the Flame Structure
Authors: Hauser Martin , Lorenz Manuel , Sattelmayer Thomas
Published: November 2010

Modern large gas turbines for power generation have multiple burners, which are distributed around the circumference of the engine and which generate flames in combustors of either annular or can-annular geometry. In both cases, considering only the axial modes has proven to be insufficient for the assessment of the thermoacoustic stability. An adequate analysis requires consideration of the circumferential acoustic coupling generated by the acoustic field in the upstream and downstream annuli and the open passages between the cans, respectively. As in annular combustors, the particularly critical eigenmodes with low frequencies are predominantly of circumferential nature; the stability of annular combustors is often governed by the onset of circumferential acoustic oscillations. To determine the influence of these circumferential acoustic modes on the dynamic flame behavior, a new single burner test rig was developed. The unique acoustic properties of the test rig allow the exposure of a single swirl burner to a two-dimensional acoustic field that resembles the circumferential mode in an annular combustor. Measurements were performed for axial as well as transversal excitation of the burner and the combination of both. To investigate the dynamic flame structure, phase-resolved flame images have been evaluated in terms of amplitude and phase distribution. Under transversal excitation, the flame structure becomes highly asymmetrical. A region of higher OH∗ intensity is generated in the combustion chamber, which rotates with the excitation frequency. From phase-resolved particle image velocimetry (PIV) measurements of the isothermal flow, it is concluded that the transversal excitation modulates the swirl generation leading to an asymmetrical velocity distribution in the burner nozzle and the combustion chamber.
An Experimental System for Assessing Combustor Durability
Authors: Rudrapatna Nagaraja S. , Peterson Benjamin H. , Greving Daniel
Published: November 2010

Modern gas turbine combustors are made of high temperature alloys, employ effusion cooling, and are protected by a thermal barrier coating (TBC). Gas turbine combustor failure modes, such as TBC spallation, cracking, and distortion resulting from oxidation, creep, and thermal fatigue, are driven by hot spot peak temperature and the associated thermal gradient. Standard material characterization tests, such as creep, oxidation, and low cycle fatigue are indicators of a material’s potential performance but they neither fully represent the combustor geometric/material system nor fully represent the thermal fatigue conditions a combustor is subjected to during engine operation. Combustor rig tests and/or engine cyclic endurance tests to determine the suitability of new material systems for combustors are time-consuming and costly. Therefore, a simple yet efficient test method for screening material systems under representative combustor conditions is needed. An experimental system has been developed to fill this gap. This paper discusses the configured specimen geometry, test methodology, observed test results, and a comparison with typical failure modes observed in combustors.
An Intrinsic Geometric Framework for the Building Block Synthesis of Single Point Compliant Mechanisms
Authors: Krishnan Girish , Kim Charles , Kota Sridhar
Published: November 2010

In this paper, we implement a characterization based on eigentwists and eigenwrenches for the synthesis of a compliant mechanism at a given point. For 2D mechanisms, this involves characterizing the compliance matrix at a unique point called the center of elasticity, where translational and rotational compliances are decoupled. Furthermore, the translational compliance may be represented graphically as an ellipse and the coupling between the translational and rotational components as vectors. These representations facilitate geometric insight into the operations of serial and parallel concatenations. Parametric trends are ascertained for the compliant dyad building block and are utilized in example problems involving serial concatenation of building blocks. The synthesis technique is also extended to combination of series and parallel concatenation to achieve any compliance requirements.
Investigation of Reverse Thermosyphoning in an Indirect SDHW System
Authors: Cruickshank Cynthia A. , Harrison Stephen J.
Published: November 2010

Thermal energy storages with thermosyphon natural convection heat exchangers have been used in solar water heating systems as a means of increasing tank stratification and eliminating the need for a second circulation pump. However, if the storage system is not carefully designed, under adverse pressure conditions, reverse thermosyphoning can result in increased thermal losses from the storage and reduced thermal performance of the system. To investigate this phenomenon, tests were conducted on single tank and multitank thermal storages under controlled laboratory conditions. Energy storage rates and temperature profiles were experimentally measured during charge periods, and the effects of reverse thermosyphoning were quantified. Further objectives of this study were to empirically derive performance characteristics, to develop numerical models to predict the performance of the heat exchanger during reverse thermosyphon operation, and to quantify the relative magnitude of these effects on the energy stored during typical daylong charge periods. Results of this study show that the magnitude of the reverse flow rate depends on the pressure drop characteristics of the heat exchange loop, the system temperatures, and the geometry of the heat exchanger and storage tank. In addition, the results show that in the case of a multitank thermal storage, the carryover of energy to the downstream thermal energy storages depends on the effectiveness of the exchangers used in the system.
Type Synthesis of Parallel Mechanisms Having the Second Class GF Sets and Two Dimensional Rotations
Authors: Gao Feng , Yang Jialun , Ge Qiaode Jeffrey
Published: November 2010

With the introduction of generalized function sets (GF set) to represent the characteristics of the end-effectors of parallel mechanisms, two classes of GF sets are proposed. The type synthesis of parallel mechanisms having the second class GF sets and two dimensional rotations, including 2-, 3-, and 4DOF parallel mechanisms, is investigated. First, the intersection algorithms for the GF sets are established via the axiom of two dimensional rotations. Second, the kinematic limbs with specific characteristics are designed according to the axis movement theorem. Finally, several parallel mechanisms having the second class GF sets and two dimensional rotations have been illustrated to show the effectiveness of the proposed methodology.
A Study on μ-Synthesis Control for Four-Wheel Steering System to Enhance Vehicle Lateral Stability
Authors: Yin Guo-Dong , Chen Nan , Wang Jin-Xiang , Wu Ling-Yao
Published: November 2010

This paper presents the design of μ-synthesis control for four-wheel steering (4WS) vehicle and an experimental study using a hardware-in-the-loop (Hil) setup. First, the robust controller is designed and the selection of weighting functions is discussed in the framework of μ-synthesis control scheme, considering the varying parameters induced by running vehicle condition. Second, in order to investigate the feasibility of the four-wheel steering control system, the 4WS vehicle control system is built using dSPACE DS1005 platform. The experimental tests are performed using the Hil setup which has been constructed using the devised rear steering actuating system. The dynamics performance is evaluated by experiment using the Hil setup under the condition of parameter variations. Finally, experimental results show that the μ-synthesis controller can enhance good vehicle lateral maneuverability.
Temperature of a Quartz/Sapphire Window in a Solar Cavity-Receiver
Authors: Maag G. , Falter C. , Steinfeld A.
Published: November 2010

Radiation heat transfer within a high-temperature solar cavity-receiver containing a windowed aperture exposed to concentrated solar radiation is solved using the gray-band approximated radiosity method for semitransparent enclosures. Spectrally selective quartz and sapphire are examined for window materials. Window and cavity temperatures are calculated as a function of the incoming radiative flux and solar energy absorption efficiency. For validation and comparability, a windowless cavity is analyzed. Due to its relatively high reflectance in the visible spectrum, the sapphire window requires higher inlet solar radiative flux than the quartz window to obtain the same reactor temperature and energy absorption efficiency.
Numerical Investigation of a Silicon Six-Wafer Microcombustor Under the Effect of Heat Loss Through the Outer Walls
Authors: Zhu Lin , Jen Tien-Chien , Kong Xiao-Ling
Published: November 2010

In this paper, the influences of low heat transfer condition at the outer walls on the microcombustor are investigated due to the fact that a sufficiently small heat transfer coefficient at the outer wall incurs the upstream burning in the recirculation jacket, results in the high wall temperature, and hence possibly damages the microcombustor. Numerical simulation approaches focused on the microcombustor with the flame burning in the recirculation jacket. Combustion characteristics of the combustor were first analyzed based on 2D computational fluid dynamics (CFD), and then the most dangerous locations on the combustor were predicted by means of the 3D finite element analysis method. The study demonstrates the effectiveness of CFD and stress modeling for the design and improvement of the microcombustors.
The Effect of Kinematic and Kinetic Changes on Meniscal Strains During Gait
Authors: Netravali Nathan A. , Koo Seungbum , Giori Nicholas J. , Andriacchi Thomas P.
Published: November 2010

The menisci play an important role in load distribution, load bearing, joint stability, lubrication, and proprioception. Partial meniscectomy has been shown to result in changes in the kinematics and kinetics at the knee during gait that can lead to progressive meniscal degeneration. This study examined changes in the strains within the menisci associated with kinematic and kinetic changes during the gait cycle. The gait changes considered were a 5 deg shift toward external rotation of the tibia with respect to the femur and an increased medial-lateral load ratio representing an increased adduction moment. A finite element model of the knee was developed and tested using a cadaveric specimen. The cadaver was placed in positions representing heel-strike and midstance of the normal gait, and magnetic resonance images were taken. Comparisons of the model predictions to boundaries digitized from images acquired in the loaded states were within the errors produced by a 1 pixel shift of either meniscus. The finite element model predicted that an increased adduction moment caused increased strains of both the anterior and posterior horns of the medial meniscus. The lateral meniscus exhibited much lower strains and had minimal changes under the various loading conditions. The external tibial rotational change resulted in a 20% decrease in the strains in the posterior medial horn and increased strains in the anterior medial horn. The results of this study suggest that the shift toward external tibial rotation seen clinically after partial medial meniscectomy is not likely to cause subsequent degenerative medial meniscal damage, but the consequence of this kinematic shift on the pathogenesis of osteoarthritis following meniscectomy requires further consideration.
Physical Review Letters in the Classroom
Authors: Angiolillo Paul J. , Lynch Jonathan
Published: November 2010

Ask any physicist what the preeminent journal in the field is, and I think the almost unanimous answer will be Physical Review Letters (PRL). This weekly journal of the American Physical Society publishes high-impact research from all the major subdisciplines of physics. This journal is not the one you would think is the first place a high school physics teacher or college professor teaching introductory physics would look to find material for his or her class. But to the contrary, what better way to excite young minds to the wonders of physics than to introduce them to the primary source material? Often times, the articles in PRL address what to the casual observer would be considered rather simple phenomena. However, as we in the discipline know, it is these simple phenomena that are difficult to understand and explain. In this paper, we have surveyed a five-year period of PRL and have chosen two papers from which to conduct further experimentation, experimentation that is designed to be simple, make use of common materials and inexpensive apparatuses, and consequently be accessible to most high school settings or adopted for individual student projects.
An Inexpensive Cosmic Ray Detector for the Classroom
Authors: Goldader Jeffrey D. , Choi Seulah
Published: November 2010

Finding ways to demonstrate—in a high school classroom—that subatomic particles from space produce other particles capable of reaching the Earth's surface is not a trivial task. In this paper, we describe a Geiger-Muller tube-based cosmic ray coincidence detector we produced at a total cost of less than $200, using two tubes purchased used online; if the tubes were purchased new, the total cost would be about $325. Our detector is able to produce unambiguous CR detections in just 1000 total seconds of data collection. Furthermore, it is small and easily manipulated, allowing us to easily demonstrate the relationship between cosmic ray flux and the zenith angle.
The Twin Twin Paradox: Exploring Student Approaches to Understanding Relativistic Concepts
Authors: Cormier Sébastien , Steinberg Richard
Published: November 2010

A great deal has long been known about student difficulties connecting real-world experiences with what they are learning in their physics classes, making learning basic ideas of classical physics challenging.1 Understanding these difficulties has led to the development of many instructional approaches that have been shown to help students make connections to the real world, think constructively, and learn the material successfully.2 However, what happens when making connections to the real world is more complicated. It is one thing to try to figure out how pushing a block with a constant force leads to constant speed, but it is very different to try to build toward an understanding of time dilation. Do the same instructional approaches work here? Also, is it possible that improved instructional approaches lead to improved student approaches when trying to make sense of difficult and very unfamiliar material? In this paper we describe a unique opportunity to perform a controlled experiment by interviewing identical twin brothers working together to resolve the twin paradox. These were intelligent and articulate science students with similar backgrounds but with diverging undergraduate experiences. One happened to take traditional physics classes and the other happened to take classes designed through Physics Education Research.
Cylindrometer
Authors: Khan Sameen Ahmed
Published: November 2010

Spherometers are instruments designed to measure the radius of curvature of spherical surfaces.1,2 They are particularly useful in situations where only a portion of the spherical surface is available, for example, for measuring the radii of curvature of spherical lenses.3 A spherometer can be easily modified so that it can also be used to measure the radius of curvature of a right circular cylinder. The resulting device is called a cylindrometer (also known as the cylindrospherometer). The idea is quite old4 but is seldom mentioned in introductory laboratory courses. This paper describes the device and its operation.
Characterization of a Piezoelectric Buzzer Using a Michelson Interferometer
Authors: Lloyd S. , Paetkau M.
Published: November 2010

A piezoelectric material generates an electric potential across its surface when subjected to mechanical stress;1 conversely, the inverse piezoelectric effect describes the expansion or contraction of the material when subjected to some applied voltage. Piezoelectric materials are used in devices such as doorbell buzzers, barbeque igniters, and also as the scanning and approach mechanisms in scanning probing microscopy. The assembly of a scanning tunnelling microscope (STM)2 at Thompson Rivers University has motivated a characterization of the sensitivity and hysteresis3 of piezoelectric discs using a Michelson interferometer. The investigation uses an interferometer4 and a simple photodiode circuit to track the fringes. As a possible undergraduate lab, the measurement provides an introduction to piezoelectric materials (including hysteresis), the Michelson interferometer, and data acquisition techniques.
Graphical Method for Determining Projectile Trajectory
Authors: Moore J. C. , Baker J. C. , Franzel L. , McMahon D. , Songer D.
Published: November 2010

We present a nontrigonometric graphical method for predicting the trajectory of a projectile when the angle and initial velocity are known. Students enrolled in a general education conceptual physics course typically have weak backgrounds in trigonometry, making inaccessible the standard analytical calculation of projectile range. Furthermore, research shows that standard instructional techniques fail to confront student misconceptions about motion in a gravitational field.1–4 We have designed a guided inquiry-based lesson that specifically addresses these misconceptions with minimal mathematics.
UPBEAT Growth
Authors: Wong Wei
Published: November 2010

Gradients of reactive oxygen species determine whether cells proliferate or differentiate in
Arabidopsis
roots.
Tweaking Dopamine Reception
Authors: Vinson Valda
Published: November 2010

Discovery of a binding site in the extracellular domain of a dopamine receptor offers hope for more selective therapeutics.
Wiping Out Memories
Authors: Stern Peter R.
Published: November 2010

The subunit composition of AMPA receptors at lateral amygdala synapses changes after the acquisition of associative fear.
Science Signaling
Podcast: 23 November 2010
Authors: Reed Elaine F. , VanHook Annalisa M.
Published: November 2010

Targeting interactions between HLA-I and the integrin β
4
subunit is a potential strategy for preventing transplant rejection.
Cyclic-di-GMP Reaches Out into the Bacterial RNA World
Authors: Hengge Regine
Published: November 2010

A bacterial second messenger regulates mRNA translation by altering the cleavage of a self-splicing intron.
Single-Dose Pharmacokinetics, Safety, and Tolerability of Albinterferon Alfa-2b in Subjects with End-Stage Renal Disease on Hemodialysis Compared to Those in Matched Healthy Volunteers
Authors: Serra Denise B. , Sun Haiying , Karwowska Sylwia , Praestgaard Jens , Halabi Atef , Stein Daniel S.
Published: November 2010

Albinterferon alfa-2b (albIFN) is being developed, in combination with ribavirin, for the treatment of hepatitis C virus infection. This study was designed to evaluate the pharmacokinetics, safety, and tolerability of a 900-μg dose of albIFN administered as a single subcutaneous injection in end-stage renal disease (ESRD) patients on hemodialysis and matched healthy volunteers (by age [±5 years], weight [±5 kg], and gender). The maximum concentration in plasma (
C
max
) and the area under the concentration-time curve from time zero to infinity (AUC
0-∞
) were 42.8 ± 14.0 ng/ml and 16,414 ± 4,203 ng·h/ml, respectively, for healthy volunteers, while the
C
max
and AUC
0-∞
were 49.9 ± 20.9 ng/ml and 18,919 ± 8,008 ng·h/ml, respectively, for ESRD patients. The geometric least-squares mean ratios were 1.15 (90% confidence interval [CI], 0.78, 1.68) for
C
max
and 1.11 (90% CI, 0.83, 1.48) for AUC
0-∞
. Adverse events were as expected for an interferon (e.g., flu-like symptoms), with the main laboratory adverse event being a decline in total white blood cell count, which was specifically related to a decline in the neutrophil count. This effect was somewhat greater in the ESRD patients, with the maximal decreases in neutrophil counts from those at the baseline being (−2.6 ± 0.32) × 10
9
and (−2.19 ± 0.58) × 10
9
cells/liter for the ESRD patients and the healthy volunteers, respectively. This study indicates no significant effect of renal failure on the pharmacokinetics of albIFN. Safety and tolerability were as expected for an interferon.
Vancomycin Bonded to Bone Grafts Prevents Bacterial Colonization
Authors: Ketonis Constantinos , Barr Stephanie , Adams Christopher S. , Shapiro Irving M. , Parvizi Javad , Hickok Noreen J.
Published: November 2010

Infection is an important medical problem associated with the use of bone allografts. To retard bacterial colonization, we have recently reported on the modification of bone allografts with the antibiotic vancomycin (VAN). In this report, we examine the ability of this antibiotic-modified allograft to resist bacterial colonization and biofilm formation. When antibiotic was coupled to the allograft, a uniform distribution of the antibiotic was apparent. Following challenges withStaphylococcus aureusfor 6 h, the covalently bonded VAN decreased colonization as a function of inoculum, ranging from 0.8 to 2.0 log10CFU. Furthermore, the VAN-modified surface resisted biofilm formation, even in topographical niches that provide a protected environment for bacterial adhesion. Attachment of the antibiotic to the allograft surface was robust, and the bonded VAN was stable whether incubated in aqueous media or in air, maintaining levels of 75 to 100% of initial levels over 60 days. While the VAN-modified allograft inhibited the Gram-positiveS. aureuscolonization, in keeping with VAN′s spectrum of activity, the VAN-modified allograft was readily colonized by the Gram-negativeEscherichia coli. Finally, initial toxicity measures indicated that the VAN-modified allograft did not influence osteoblast colonization or viability. Since the covalently tethered antibiotic is stable, is active, retains its specificity, and does not exhibit toxicity, it is concluded that this modified allograft holds great promise for decreasing bone graft-associated infections.
A Rapid, High-Throughput Viability Assay forBlastocystisspp. Reveals Metronidazole Resistance and Extensive Subtype-Dependent Variations in Drug Susceptibilities
Authors: Mirza Haris , Teo Joshua D. W. , Upcroft Jacqui , Tan Kevin S. W.
Published: November 2010

Blastocystisis an emerging protistan parasite of controversial pathogenesis. Although metronidazole (Mz) is standard therapy forBlastocystisinfections, there have been accumulating reports of treatment failure, suggesting the existence of drug-resistant isolates. Furthermore, very little is known aboutBlastocystissusceptibility to standard antimicrobials. In the present study, we established resazurin and XTT viability microassays forBlastocystisspp. belonging to subtypes 4 and 7, both of which have been suggested to represent pathogenic zoonotic subtypes. The optimized resazurin assay was used to screen a total of 19 compounds against both subtypes. Interestingly, subtype 7 parasites were resistant to Mz, a 1-position-substituted 5-nitroimidazole (5-NI), while subtype 4 parasites were sensitive. Some cross-resistance was observed to tinidazole, another 1-position 5-NI. Conversely, subtype 4 parasites were resistant to emetine, while subtype 7 parasites were sensitive. Position 2 5-NIs were effective against both subtypes, as were ornidazole, nitazoxanide, furazolidone, mefloquine, quinicrine, quinine, cotrimoxazole (trimethoprim-sulfamethoxazole), and iodoacetamide. Both subtypes were resistant to chloroquine, doxycycline, paromomycin, ampicillin, and pyrimethamine. This is the first study to report extensive variations in drug sensitivities among two clinically important subtypes. Our study highlights the need to reevaluate established treatment regimens forBlastocystisinfections and offers clear new treatment options for Mz treatment failures.
The
In Vitro
Contribution of Autolysins to Bacterial Killing Elicited by Amoxicillin Increases with Inoculum Size in
Enterococcus faecalis
Authors: Dubée Vincent , Chau Françoise , Arthur Michel , Garry Louis , Benadda Samira , Mesnage Stéphane , Lefort Agnès , Fantin Bruno
Published: November 2010

The mechanisms of antibiotic-induced cell death are poorly understood despite the critical role of the bactericidal activities of antibiotics for successful treatment of severe infections. These mechanisms include irreversible damaging of macromolecules by reactive oxygen species and bacteriolysis mediated by peptidoglycan hydrolases (autolysins). We have assessed the contribution of the second mechanism by using an autolysin-deficient mutant of
Enterococcus faecalis
and shown that it contributes to amoxicillin-induced cell lysis only at a high bacterial density.
Inhibition of human purine nucleoside phosphorylase by tenofovir phosphate congeners
Authors: Votruba Ivan , Trýznová Jana , Břehová Petra , Tloušťová Eva , Horská Květoslava , Fanfrlík Jindřich , Přenosil Ondřej , Holý Antonín
Published: November 2010

The structure-activity study on the phosphates of phosphonomethoxypropyl derivatives of purine bases interacting with human purine nucleoside phosphorylase has shown that the most efficient inhibitors of the enzyme are (R)- and (S)-PMPGp with Ki ~ 1.9 × 10–8 and/or 2.2 × 10–8 mol/l. The kinetic experiments have proven, with the exception of both enantiomers of PMP-8-BrDAPp, strictly competitive character of inhibition for all ANP monophosphates tested. Bromine derivatives exhibited uncompetitive and mixed type of inhibition as well. These results were confirmed by docking studies. The substitution of purine moiety with the bromine at the position 8 lead to an allosteric binding of these compounds toward the enzyme.
Barriers to, and facilitators of, the prevention of unintentional injury in children in the home: a systematic review and synthesis of qualitative research
Authors: Smithson Janet , Garside Ruth , Pearson Mark
Published: November 2010

Background

This review considers barriers to, and facilitators of, success for interventions to reduce unintentional injury to children in the home through supply and/or installation of home safety equipment, and looks at risk assessments.

Methods

A systematic review of qualitative research. Bibliographic databases were searched for studies on interventions to reduce unintentional child injury in the home, or on related attitudes and behaviours. Studies were quality appraised, findings extracted, and a conceptual framework was developed to assess factors affecting the success of interventions.

Results

Nine peer-reviewed journal articles were included. Barriers and facilitators were highlighted at organisational, environmental and personal levels. Effective provision of safety equipment involves ongoing support with installation and maintenance. Take up and success of interventions depends on adjusting interventions according to practical limitations and parents' cultural expectations. A particular barrier was parents' inability to modify rented or shared accommodation.

Conclusions

The review highlights ways in which health inequalities affect the take up and success of home safety interventions, and how health workers can use this knowledge to facilitate future interventions.
Scientific evidence and best patient care practices should guide the ethics of Lyme disease activism: Table 1
Authors: Auwaerter Paul G , Bakken Johan S , Dattwyler Raymond J , Dumler J Stephen , Halperin John J , McSweegan Edward , Nadelman Robert B , O'Connell Susan , Sood Sunil K , Weinstein Arthur , Wormser Gary P
Published: November 2010

Johnson and Stricker published an opinion piece in theJournal of Medical Ethicspresenting their perspective on the 2008 agreement between the Infectious Diseases Society of America (IDSA) and the Connecticut Attorney General with regard to the 2006 IDSA treatment guideline for Lyme disease. Their writings indicate that these authors hold unconventional views of a relatively common tick-transmitted bacterial infection caused by the spirocheteBorrelia burgdorferi. Therefore, it should come as no surprise that their opinions would clash with the IDSA's evidence-based guidelines for the diagnosis and treatment of Lyme disease. Their allegations of conflict of interest against the IDSA resemble those made against the National Institutes of Health, the Food and Drug Administration and the Centers for Disease Control and Prevention in 2000, which were found to be baseless. It is the responsibility of all physicians and medical scientists to stand up to antiscientific, baseless and unethical attacks on those who support an evidence-based approach to caring for patients.
Respecting frailty: Table 1
Authors: Mallery Laurie H , Moorhouse Paige
Published: November 2010

While the medical treatment of older individuals often results in desirable outcomes, indiscriminate use of aggressive treatment at the end-of-life can cause paradoxical harm and suffering. Comprehensive assessment and communication can help foster decisions that consider the effect of frailty on health outcomes.
ALMOST ADDITIVE THERMODYNAMIC FORMALISM: SOME RECENT DEVELOPMENTS
Authors: BARREIRA LUIS
Published: November 2010

This is a survey on recent developments concerning a thermodynamic formalism for almost additive sequences of functions. While the nonadditive thermodynamic formalism applies to much more general sequences, at the present stage of the theory there are no general results concerning, for example, a variational principle for the topological pressure or the existence of equilibrium or Gibbs measures (at least without further restrictive assumptions). On the other hand, in the case of almost additive sequences, it is possible to establish a variational principle and to discuss the existence and uniqueness of equilibrium and Gibbs measures, among several other results. After presenting in a self-contained manner the foundations of the theory, the survey includes the description of three applications of the almost additive thermodynamic formalism: a multifractal analysis of Lyapunov exponents for a class of nonconformal repellers; a conditional variational principle for limits of almost additive sequences; and the study of dimension spectra that consider simultaneously limits into the future and into the past.
THE l1 PENALTY FUNCTION METHOD FOR NONCONVEX DIFFERENTIABLE OPTIMIZATION PROBLEMS WITH INEQUALITY CONSTRAINTS
Authors: ANTCZAK TADEUSZ
Published: November 2010

In this paper, some new results on the l1 exact penalty function method are presented. A simple optimality characterization is given for the nonconvex differentiable optimization problems with inequality constraints via the l1 exact penalty function method. The equivalence between sets of optimal solutions in the original mathematical programming problem and its associated exact penalized optimization problem is established under suitable r-invexity assumption. The penalty parameter is given, above which this equivalence holds. Furthermore, the equivalence between a saddle point in the considered nonconvex mathematical programming problem with inequality constraints and a minimizer in its penalized optimization problem with the l1 exact penalty function is also established.
SOME IMPROVED ALGORITHMS ON THE SINGLE MACHINE HIERARCHICAL SCHEDULING WITH TOTAL TARDINESS AS THE PRIMARY CRITERION
Authors: HE CHENG , LIN YIXUN , YUAN JINJIANG
Published: November 2010

It is well-known that a single machine scheduling problem of minimizing the total tardiness is NP-hard. Recently, Liu, Ng and Cheng solved some special hierarchical minimization problems with total tardiness as the primary criterion by the Algorithm TAP (Two Assignment Problems) in O(n3) time. And in this paper we present some algorithms for these problems with running time O(n log n).
STOCHASTIC MARKET-CLEARING OF JOINT ENERGY AND RESERVES AUCTIONS
Authors: AGHAEI J. , SHAYANFAR H. A. , AMJADY N.
Published: November 2010

An important issue in deregulated power systems is a provision of ancillary services. This paper presents a Mixed Integer Non-Linear Programming (MINLP) formulation for the provision of ancillary services (Automatic Generation Control or AGC, Spinning, Non-spinning and operational reserves) as well as the energy in simultaneous auctions by pool-based aggregated market scheme. The uncertainty of the market clearing procedure is represented by a stochastic model. Thus, the market clearing process is expressed as a stochastic optimization problem in which the expected objective function is minimized, while meeting AC power flow constraints, system reserve requirements and Lost Opportunity Cost (LOC). The model is applied to the IEEE 24-bus Reliability Test System (IEEE 24-bus RTS), and simulation studies carried out to examine the effectiveness of the proposed method.