bluuebunny/crossref_metadata_2025 huggingface dataset:
Isolation of polymorphic microsatellite loci for the marine invader Microcosmus squamiger (Ascidiacea)
Authors: RIUS MARC , TURON XAVIER , PASCUAL MARTA
Published: August 2009

The ascidian Microcosmus squamiger is native to Australia and has recently spread worldwide. It has become a pest in some littoral communities within its introduced range. An enriched genomic library of M. squamiger resulted in a total of eight polymorphic loci that were genotyped in 20 individuals from a population within its introduced range, and 20 individuals more from a native population. The mean number of alleles per locus was 5.33 and mean observed heterozygosity was 0.432. No significant linkage disequilibrium was found among loci pairs. Significant genetic differentiation was observed between populations.
Characterization of 18 new microsatellite loci in Atlantic cod (Gadus morhua L.)
Authors: SKIRNISDOTTIR SIGURLAUG , PAMPOULIE CHRISTOPHE , HAUKSDOTTIR SIGURBJORG , SCHULTE INGA , OLAFSSON KRISTINN , HREGGVIDSSON GUDMUNDUR O. , HJORLEIFSDOTTIR SIGRIDUR
Published: August 2009

Eighteen new microsatellite loci consisting of 10 di‐, 5 tri‐, 2 tetra‐ and 1 heptanucleotide repeats are introduced for the Atlantic cod (Gadus morhua L.). All loci were co‐amplified in two polymerase chain reactions (plus two previously published microsatellites) and all products were typed clearly. The number of alleles per locus ranged from six (PGmo130) to 45 (PGmo76) and the observed heterozygosity ranged from 0.356 (PGmo130) to 0.957 (PGmo95). All loci except one followed Hardy–Weinberg expectations. Genetic linkage disequilibrium analysis between all pairs of loci did not yield any significant values.
Polymorphic microsatellite markers for the tsetse fly Glossina fuscipes fuscipes (Diptera: Glossinidae), a vector of human African trypanosomiasis
Authors: BROWN J. E. , KOMATSU K. J. , ABILA P. P. , ROBINSON A. S. , OKEDI L. M. A. , DYER N. , DONNELLY M. J. , SLOTMAN M. A. , CACCONE A.
Published: August 2009

Our understanding of Glossina fuscipes fuscipes, a major vector of sleeping sickness, has been severely constrained by a lack of genetic markers for mapping and population genetic studies. Here we present 10 newly developed microsatellite loci for this tsetse species. Heterozygosity levels in Moyo, an Ugandan population, averaged 0.57, with only two loci showing very low heterozygosity. Five loci carried more than six alleles. Together with five recently published microsatellite loci, this brings the number of available microsatellite loci for this species to 15. Their availability will greatly facilitate future studies on the genetics of this important human disease vector.
Efficient molecular sexing in dioecious Silene latifolia and S. dioica and paternity analysis in F1 hybrids
Authors: HOBZA R , WIDMER A
Published: August 2009

Two polymerase chain reaction‐based assays have been developed that work in combination with an efficient DNA extraction protocol to rapidly and reliably determine sex in the dioecious plant species Silene latifolia and S. dioica. In addition, one of the assays allows assessing paternity in the F1 generation of intra‐ and interspecific matings involving the two species.
Isolation and characterization of 12 microsatellites from the black surfperch, Embiotoca jacksoni, a reef fish that lacks a pelagic larval phase
Authors: BERNARDI GIACOMO
Published: August 2009

A set of 12 microsatellite markers was developed from Embiotoca jacksoni genomic DNA and tested for polymorphism using 64 individuals from two populations. All loci were polymorphic with a number of alleles ranging from two to 19 with expected heterozygosities ranging from 0.17 to 0.89. There was no evidence of linkage disequilibrium and all loci were in Hardy–Weinberg equilibrium, except for four loci in one population. High numbers of private alleles were consistent with strong population structure, and very limited dispersal. Six microsatellite markers successfully cross amplified and were polymorphic in closely related species, Embiotoca lateralis and Hyspurus caryi.
Polymorphic microsatellite DNA markers for Banksia hookeriana (Proteaceae)
Authors: HE TIANHUA , KRAUSS SIEGFRIED L. , LAMONT BYRON B.
Published: August 2009

We developed 11 polymorphic microsatellite DNA markers for an Australian native shrub Banksia hookeriana (Proteaceae). The number of alleles per locus in 37 individuals varied from three to 17, observed and expected heterozygosities ranged from 0.297 to 0.838 and from 0.279 to 0.900, respectively. Two loci (BH‐B5 and BH‐B107) showed significant deviation from Hardy–Weinberg equilibrium (P < 0.05), and null alleles may be present at these two loci. All loci showed independent inheritance.
Microsatellite primers for relatedness and population structure in great frigatebirds (Pelecaniformes: Fregatidae)
Authors: DEARBORN DONALD C. , HAILER FRANK , FLEISCHER ROBERT C.
Published: August 2009

Eighteen moderately polymorphic microsatellite loci were isolated and characterized for great frigatebirds Fregata minor. Polymorphism for the 12 dinucleotide and six tetranucleotide markers was assessed in 23 birds from a Hawaii population. Allelic diversity ranged from two to 12 (mean 5.9), with observed heterozygosity from 0.304 to 0.956 (mean 0.637). Three loci showed homozygote excess, possibly due to null alleles. One additional pair of loci exhibited strong gametic disequilibrium. Thus, at least 14 loci will be useful for studies of relatedness and population structure.
Isolation and characterization of 10 highly polymorphic di‐ and trinucleotide microsatellite markers in the mayfly Ameletus inopinatus (Ephemeroptera: Siphlonuridae)
Authors: THEISSINGER KATHRIN , FELDHEIM KEVIN A. , TAUBMANN JULIA , SEITZ ALFRED , PAULS STEFFEN U.
Published: August 2009

We describe the isolation of ten polymorphic microsatellite loci from the mayfly Ameletus inopinatus. Loci had di‐ or trinucleotide repeat motifs and were highly variable with three to 17 alleles (mean = 7.15). Observed heterozygosity ranged from 0.143 to 0.905. One locus (Ami_202) showed significant deviation from Hardy–Weinberg equilibrium in one population, but no evidence for null alleles. One locus (Ami_73) was significantly linked with three other loci. The remaining nine loci should prove highly informative for population genetic studies.
Identification of active methylotrophic bacteria inhabiting surface sediment of a marine estuary
Authors: Moussard Hélène , Stralis‐Pavese Nancy , Bodrossy Levente , Neufeld Josh D. , Murrell J. Colin
Published: August 2009

Methylotrophs play an essential role in the global carbon cycle due to their participation in methane oxidation and C1 metabolism. Despite this important biogeochemical role, marine and estuarine microorganisms that consume C1 compounds are poorly characterized. In this study, we investigated the diversity of active methylotrophs and methanotrophs in sediment from the Colne Estuary (Brightlingsea, UK). Aerobic surface sediment samples were examined for the presence of C1‐utilizing communities using DNA stable‐isotope probing (DNA‐SIP) with 13C‐labelled methane, methanol and monomethylamine. Active methylotrophic bacteria were confirmed after DNA‐SIP and denaturing gradient gel electrophoresis analyses. Clone libraries of 16S rRNA gene amplicons revealed the presence of methylotrophic bacteria affiliated with Methylophaga spp. in methanol and monomethylamine incubations. The addition of marine ammonium mineral salts medium to the microcosms increased the rate of substrate metabolism in DNA‐SIP incubations, although nutrient addition did not affect the active populations contributing 13C‐labelled DNA. The 13CH4 SIP incubations indicated the predominant activity of type I methanotrophs and microarray hybridization of amplified particulate methane monooxygenase (pmoA) genes confirmed the role of type Ia methanotrophs in SIP incubations. Type II methanotrophs (i.e. Methylocystis and Methylosinus) were only detected in the original sediment and in the unlabelled DNA fractions, which indicated that type II methanotrophs were not actively involved in C1 compound assimilation in DNA‐SIP incubations with estuarine surface sediment samples.
A general profile for the MerR family of transcriptional regulators constructed using the semi‐automated Provalidator tool
Authors: Molina‐Henares Antonio J. , Godoy Patricia , Duque Estrella , Ramos Juan L.
Published: August 2009

Provalidator is a web‐based tool that facilitates the design and validation of generalized profiles of protein families in prokaryotes. This tool combines the nearly full automation of profile building with a search for family members in all available databases. The tool is useful for assigning a given protein to a specific family, and is also useful for genome mining in annotated prokaryotic genomes. The tool is freely available at http://www.bactregulators.org. As proof of concept we constructed a profile that best defines the MerR family of transcriptional regulators. The profile created includes functional residues that are part of the helix–turn–helix DNA binding domain and accessory elements defined as wings 1 and 2, suggesting that members of the MerR family of regulators may exhibit conserved 3D structure in the region that defines the family profile. The profile defined for MerR was used to search for members of this family in the Swiss‐Prot and TrEMBL databases, and also to identify members of the family in the genome of Pseudomonas putida. One of these identified regulators was found to be involved in zinc tolerance, showing the usefulness of identifying family members and assigning phenotypes.
An evaluation of bovine derived xenograft with and without a bioabsorbable collagen membrane in the treatment of mandibular Class II furcation defects
Authors: Taheri M , Molla R , Radvar M , Sohrabi K , Najafi MH
Published: August 2009

Background:  The aim of this study was to compare the clinical outcomes of applying Bio‐Oss®, an anorganic bovine bone xenograft (control group) to the combined use of Bio‐Oss® and Bio‐Gide® (a bioabsorbable collagen membrane) (test group) in human mandibular Class II furcation defects.

Methods:  A total of 18 furcations (8 tests and 10 controls) in 14 patients suffering from chronic periodontitis were treated in this randomized clinical trial. Open vertical and horizontal furcation depths (OVFD and OHFD), vertical and horizontal clinical attachment levels (VCAL, HCAL), probing depth (PD) and free gingival marginal level (GML) were among the clinical parameters measured prior and six months after treatment, at re‐entry surgery. The data were analysed by statistical tests while a p value less than 0.05 was considered significant.

Results:  At the surgical re‐entry, the mean reduction for OVFD of the control and test groups was 1.9 ± 1.3 and 2.1 ± 1.0, and for OHFD 2.1 ± 0.7 and 2.4 ± 1.3, respectively. The control and test treatments resulted in significant reductions in PD, VCAL and HCAL measurements at re‐entry but there was no statistically significant difference between the two treatments in all soft and hard tissues measurements.

Conclusions:  This clinical trial failed to demonstrate the superiority of the combined use of Bio‐Gide® and Bio‐Oss® to the use of Bio‐Oss® alone, although both therapies resulted in significant gains in attachment level and bone fill.
Static Output Feedback Control for Electrohydraulic Active Suspensions via T–S Fuzzy Model Approach
Authors: Du Haiping , Zhang Nong
Published: August 2009

The paper presents a fuzzy static output feedback controller design approach for vehicle electrohydraulic active suspensions based on Takagi–Sugeno (T–S) fuzzy modeling technique. The T–S fuzzy model is first applied to represent the nonlinear dynamics of an electrohydraulic suspension. Then, the fuzzy static output feedback controller is designed for the obtained T–S fuzzy model to optimize the H∞ performance of ride comfort through the parallel distributed compensation scheme. The sufficient conditions for the existence of such a controller are derived in terms of linear matrix inequalities (LMIs) with an equality constraint. A computational algorithm is presented to convert the equality constraint into a LMI so that the controller gains can be obtained by solving a minimization problem with LMI constraints. To validate the effectiveness of the proposed approach, two kinds of static output feedback controllers, which use suspension deflection and sprung mass velocity, and suspension deflection only, respectively, as feedback signals, are designed. It is confirmed by the simulations that the designed controllers can achieve good suspension performance similar to that of the active suspension with optimal skyhook damper.
Growing Structure Multiple Model Systems for Anomaly Detection and Fault Diagnosis
Authors: Liu Jianbo , Djurdjanovic Dragan , Marko Kenneth , Ni Jun
Published: August 2009

A new anomaly detection scheme based on growing structure multiple model system (GSMMS) is proposed in this paper to detect and quantify the effects of anomalies. The GSMMS algorithm combines the advantages of growing self-organizing networks with efficient local model parameter estimation into an integrated framework for modeling and identification of general nonlinear dynamic systems. The identified model then serves as a foundation for building an effective anomaly detection and fault diagnosis system. By utilizing the information about system operation region provided by the GSMMS, the residual errors can be analyzed locally within each operation region. This local decision making scheme can accommodate for unequally distributed residual errors across different operational regions. The performance of the newly proposed method is evaluated through anomaly detection and quantification in an electronically controlled throttle system, which is simulated using a high-fidelity engine simulation software package provided by a major automotive manufacturer for control system development.
Linear Quadratic Regulator for a Bottoming Solid Oxide Fuel Cell Gas Turbine Hybrid System
Authors: Mueller Fabian , Jabbari Faryar , Brouwer Jacob , Junker S. Tobias , Ghezel-Ayagh Hossein
Published: August 2009

The control system for fuel cell gas turbine hybrid power plants plays an important role in achieving synergistic operation of subsystems, improving reliability of operation, and reducing frequency of maintenance and downtime. In this paper, we discuss development of advanced control algorithms for a system composed of an internally reforming solid oxide fuel cell coupled with an indirectly heated Brayton cycle gas turbine. In high temperature fuel cells it is critical to closely maintain fuel cell temperatures and to provide sufficient electrochemical reacting species to ensure system durability. The control objective explored here is focused on maintaining the system power output, temperature constraints, and target fuel utilization, in the presence of ambient temperature and fuel composition perturbations. The present work details the development of a centralized linear quadratic regulator (LQR) including state estimation via Kalman filtering. The controller is augmented by local turbine speed control and integral system power control. Relative gain array analysis has indicated that independent control loops of the hybrid system are coupled at time scales greater than 1 s. The objective of the paper is to quantify the performance of a centralized LQR in rejecting fuel and ambient temperature disturbances compared with a previously developed decentralized controller. Results indicate that both the LQR and decentralized controller can well maintain the system power to the disturbances. However, the LQR ensures better maintenance of the fuel cell stack voltage and temperature that can improve high temperature fuel cell system durability.
Augmented Controllable Region of Unstable Second Order Systems With Impulsive Actions
Authors: Sung Wookjin , Luo Jiecai , You Kwanho
Published: August 2009

In this paper, we suggest how to enlarge the maximum controllable region for unstable linear systems with mixed control actions. Using the impulsive action as an alternating control input, it is shown how the collaborative control inputs (bang-bang and impulsive action) work to augment the controllable region of unstable second order systems. However, the weakness resides in the sensitivity to model uncertainty and the time-consuming work to construct the switch curves (bang-bang switch curve and impulse firing curve). We suggest an efficient way to approximate the switch curves. It overcomes the shortcomings from the use of original switch curves, which are constructed through time backward computation. Simulation results show how the approximate switch curves can be used to determine the optimal control values for an augmented maximum controllable region.
A Neural Network Implementation of Peak Pressure Position Control by Ionization Current Feedback
Authors: Rivara N. , Dickinson P. B. , Shenton A. T.
Published: August 2009

This paper describes a neural-network (NN)-based scheme for the control of a cylinder peak pressure position (PPP)—also known as the location of peak pressure (LPP)—by spark timing in a gasoline internal combustion engine. The scheme uses the ionization current to act as a virtual sensor, which is subsequently used for PPP control. A NN is trained offline on principal-component analysis data to predict the cylinder peak pressure position under dynamically varying engine load, speed, and spark advance (SA) settings. Experimental results demonstrate that the PPP prediction by the NN correlates well with those measured from in-cylinder pressure sensors across transients of load, SA, and engine speeds. The dynamic training data allow rapid model identification across the identified engine range, as opposed to just fixed operating points. A linear robust constrained-variance controller, which is a robustified form of the minimum variance controller, is used to regulate the PPP by SA control action, using the NN as a PPP sensor. The control scheme is validated by experimental implementation on a port fuel-injected four-cylinder 1.6 l gasoline internal combustion engine.
Experimental Design and Algorithmics for a Multichannel Spectral Data Acquisition System
Authors: Duerr Konrad , Seethaler Rudolf J. , Holzman Jonathan F.
Published: August 2009

An optically-encoded mechanical modulation system and an electrical signal extraction algorithm are introduced. The system employs the beam chopping in a highly parallel scheme to impart multiple modulation channels onto the spectrum of a white-light source. The optically-multiplexed beam is directed through an experimental sample, and the absorption of the sample at each of the individual modulation channel wavelengths is resolved. A MATLAB-based parallel frequency-selection algorithm is ultimately used to resolve the signals. The low-noise benefits of optical lock-in detection and the practicality of parallel encoding/extraction are demonstrated in this design.
Cantilever Beam Design for Projectile Internal Moving Mass Systems
Authors: Rogers Jonathan , Costello Mark
Published: August 2009

Internal masses that undergo controlled translation within a projectile have been shown to be effective control mechanisms for smart weapons. However, internal mass oscillation must occur at the projectile roll frequency to generate sufficient control force. This can lead to high power requirements and place a heavy burden on designers attempting to allocate volume within the projectile for internal mass actuators and power supplies. The work reported here outlines a conceptual design for an internal translating mass system using a cantilever beam and electromagnetic actuators. The cantilever beam acts as the moving mass, vibrating at the projectile roll frequency to generate control force. First, a dynamic model is developed to describe the system. Then the natural frequency, damping ratio, and length of the beam are varied to study their affects on force required and total battery size. Trade studies also examine the effect on force required and total battery size of a roll-rate feedback system that actively changes beam elastic properties. Results show that, with proper sizing and specifications, the cantilever beam control mechanism requires relatively small batteries and low actuator control forces with minimum actuator complexity and space requirements.
Toward Functionally Graded Cellular Microstructures
Authors: Torres-Sanchez Carmen , Corney Jonathan R.
Published: August 2009

The design of multifunctional materials offers great potential for numerous applications in areas ranging from biomaterial science to structural engineering. Functionally graded microstructures (e.g., polymeric foams) are those whose porosity (i.e., ratio of the void to the solid volume of a material) is engineered to meet specific requirements such as a superior mechanical, thermal, and acoustic behavior. The controlled distribution of pores within the matrix, as well as their size, wall thickness, and interconnectivity are directly linked to the porous materials properties. There are emerging design and analysis methods of cellular materials but their physical use is restricted by current manufacturing technologies. Although a huge variety of foams can be manufactured with homogeneous porosity, for heterogeneous foams there are no generic processes for controlling the distribution of porosity throughout the resulting matrix. This paper describes work to develop an innovative and flexible process for manufacturing engineered cellular structures. Ultrasound was applied during specific foaming stages of a polymeric (polyurethane) melt, and this affected both the cellular architecture and distribution of the pore size, resulting in a controlled distribution that can be designed for specific purposes, once the polymeric foam solidified. The experimental results demonstrate that porosity (i.e., volume fraction) varies in direct proportion to the acoustic pressure magnitude of the ultrasonic signal.
Active Vibration Control and Isolation for Micromachined Devices
Authors: Kim Seong Jin , Dean Robert , Flowers George , Chen Chen
Published: August 2009

Some harsh environments contain high frequency, high amplitude mechanical vibrations. Unfortunately some very useful components, such as micro-electro-mechanical systems (MEMS) gyroscopes, can be very sensitive to these high frequency mechanical vibrations. Passive micromachined silicon low-pass filter structures (spring-mass-damper) have been demonstrated in recent years. However, the performance of these filter structures is typically limited by low damping. This is especially true if operated in low pressure environments, which is often the optimal operating environment for the attached device that requires vibration isolation. An active micromachined vibration isolator can be realized by combining a state sensor, and electrostatic actuator and feedback electronics with the passive isolator. Using this approach, a prototype active micromachined vibration isolator is realized and used to decrease the filter Q from approximately 135 to approximately 60, when evaluated in a low pressure environment. The physical size of these active isolators is suitable for use in or as packaging for sensitive electronic and MEMS devices, such as MEMS vibratory gyros.
Development of a Simple Morphing Wing Using Elastomeric Composites as Skins and Actuators
Authors: Peel Larry D. , Mejia James , Narvaez Ben , Thompson Kyle , Lingala Madhuri
Published: August 2009

Morphing wings are desired for their ability to reduce drag, to change flight characteristics, and perhaps to reduce weight by eliminating flap/aileron mechanisms. Development of two generations of a morphing wing project is documented. The work shows how a relatively low cost but realistic morphing wing test-bed can be fabricated. Wing skin, actuator, and actuator attachment development are discussed, as well as possible auxetic skin behavior. Aerodynamic characterization of the wing will be discussed in another paper. A very simple morphing wing was fabricated in generation one. The nose was able to elastically camber down approximately 25 deg and the tail 20 deg. Actuation was provided by three pneumatic “rubber muscle actuators” that produce high contractive/tensile forces. Upper and lower wing skins were fabricated from carbon fiber/polyurethane elastomer laminates. Lower skin buckling, actuator air leaks, and actuator attachment problems were resolved in the second generation. A finite element model of the second wing was developed and is being used to refine the morphing wing test-bed. The second wing fabrication methodology enabled smooth elastic cambering with no buckling or waviness in the skins. The nose cambered down 14 deg and the tail cambered down to 13 deg, and is capable of larger deformations. Improved leak-free biomimetic actuators and attach points now include no metal parts and have higher actuation forces due to new braided sheaths and functionally gradient matrix properties.
Comments on Static vs Kinetic Friction
Authors: Kessler Gabriel
Published: August 2009

I'm writing to comment on the article published in the March edition of The Physics Teacher titled “Choose Wisely: Static or Kinetic Friction—The Power of Dimensionless Plots.” As I was reading the article, something caught my eye that I couldn't reconcile with. It was the phrase on page 160 in the first column near the bottom. The statement was that the experimental value for the coefficient of kinetic friction was “unexpectedly greater than the coefficient of static friction!”
Alternative Presentation
Authors: Mosca Gene
Published: August 2009

I wish to share a few remarks concerning Fig. 1 in the paper “Analog of Optical Elements for Sound Waves in Air,” as well as the wording leading up to Eq. (1). First, the curve in Fig. 1 is supposed to be that of a hyperbola. Second, the distances labeled x and y in Fig. 1 do not appear as the coordinates of a general point on the curve. Instead they are the thickness and half-height of the lens. Defining x and y in this manner makes for a quick “derivation” of Eq. (1), but not a very satisfying one. That the drawing shows the ray from the focal point to point A penetrating the surface of the lens is particularly unsettling. A more satisfying derivation of Eq. (1) follows: (f + x)2 + y2 + n(L − x) = f + nL ⇒ (n2 − 1)x2 + 2f(n − 1) − y2 = 0.
Author's Correction: “Student Difficulties in Analyzing Thin-Film Interference,” Phys. Teach. 47, 227–230 (April 2009)
Authors: Newburgh Ronald
Published: August 2009

I am slightly embarrassed to have found two small errors in my April paper, owing to imperfect proof reading on my part. They do not affect the content in any way. They are in two equations in the last paragraph before the “Conclusion” section: In line 7, 2m + 1/2 should be (2m + 1)/2 or m + i/2.
Kaleidoscopes Made With Big Mirrors
Authors: Greenslade Thomas B.
Published: August 2009

The familiar kaleidoscope toy was developed by the Scottish physicist David Brewster (1781–1868) in 1816, patented by him in 1817, and described in his 1819 book, A Treatise on the Kaleidoscope. Generations of elementary students have made their own kaleidoscopes by assembling three microscope slides inside a tube and looking through it at a series of randomly colored objects drawn on a piece of transparent plastic placed across the far end of the tube.
Einstein Never Approved of Relativistic Mass
Authors: Hecht Eugene
Published: August 2009

During much of the 20th century it was widely believed that one of the significant insights of special relativity was “relativistic mass.” Today there are two schools on that issue: the traditional view that embraces speed-dependent “relativistic mass,” and the more modern position that rejects it, maintaining that there is only one mass and it's speed-independent. This paper explores the history of “relativistic mass,” emphasizing Einstein's public role and private thoughts. We show how the concept of speed-dependent mass mistakenly evolved out of a tangle of ideas despite Einstein's prescient reluctance. Along the way there will be previously unrevealed surprises (e.g., Einstein never derived the expression for “relativistic mass,” and privately disapproved of it).
Theater in Physics Teacher Education
Authors: van den Berg Ed
Published: August 2009

Ten years ago I sat down with the first batch of students in our science/math teacher education program in the Philippines, then third-year students, and asked them what they could do for the opening of the new science building. One of them pulled a stack of papers out of his bag and put it in front of me: a complete script for a science play! This was beyond expectation. The play was practiced several times for groups of high school students visiting the science exhibition that was also organized by the students. During the opening of our building, the play was performed for visiting dignitaries including the Assistant Secretary for Education, Culture, and Sports. It was a great success! The cast got invited to present their production at a number of places and occasions.
The Physics of a Gymnastics Flight Element
Authors: Contakos Jonas , Carlton Les G. , Thompson Bruce , Suddaby Rick
Published: August 2009

From its inception, performance in the sport of gymnastics has relied on the laws of physics to create movement patterns and static postures that appear almost impossible. In general, gymnastics is physics in motion and can provide an ideal framework for studying basic human modeling techniques and physical principles. Using low-end technology and basic principles of physics, we analyzed a high-end gymnastics skill competed in by both men and women. The comprehensive goal of the examination is to scientifically understand how a skill of this magnitude is actually physically possible and what must a gymnast do to successfully complete the skill. The examination is divided into three sections, each of which is comprehensive enough to be a separate assignment or small group project.
Estimating the Wavelength of Sodium Emission in Flame — The Easy Way
Authors: Wahab M. Farooq
Published: August 2009

Simple “box spectroscopes” are not new. Different methods of building them at home using cheap diffraction gratings have been described. However, their use has often been confined to looking at street lights, discharge tubes, and enjoying the beautiful spectra of various lamps. Construction of the box spectroscope usually involves a narrow slit made with metal plates or razor blades at one end and a transmission grating at the other end. The slit is directed toward a light source and the light spectrum is viewed through the grating. In the experiment described in this paper, a simple box spectroscope is used, along with a digital camera, for making quantitative wavelength measurements.
Three-Phase and Six-Phase AC at the Lab Bench
Authors: Caplan George M.
Published: August 2009

Utility companies generate three-phase electric power, which consists of three sinusoidal voltages with phase angles of 0°, 120°, and 240°. The ac generators described in most introductory textbooks are single-phase generators, so physics students are not likely to learn about three-phase power. I have developed a simple way to display the waveforms of the three-phase power supplied to my lab and to demonstrate an interesting feature of three-phase power. The waveform displays require three small transformers, a Vernier Lab Pro® data-collection device, and a computer; but the demonstration requires only the transformers and some miniature light bulbs. I have also developed a way to demonstrate how six-phase ac can be derived from three-phase ac.
A Static Hanging-Weight Demonstration Apparatus
Authors: Forman Miriam A. , Graf Erlend H.
Published: August 2009

In an effort to get away from standard fixed string-and-weight statics problems, one of us (MAF) posed the following problem to our freshman physics class: As shown in Fig. 1, a string of negligible mass and length L has its ends fixed at points A and B, with point B displaced horizontally from A by a distance w < L, and vertically by a distance h < L2 − w2. A mass m, hung from a small frictionless pulley, is allowed to move freely along the string until it comes to equilibrium, the pulley located a horizontal distance x to the right of A and vertical distance y below point A.
Fermi Questions
Authors: Weinstein Larry
Published: August 2009

The Moon has been hit many times by asteroids and comets. How large would the asteroid need to be in order to be able to split the Moon in half (and permanently separate the two halves)? Assume that the asteroid originates in the solar system.
Know it, Lead it, Revise it: The Keys to Success in Physics Education
Authors: Marshall Jeff C.
Published: August 2009

We start in the middle of the story…. Two teachers plan and implement a lesson addressing a major concept in physics. Yet, formative and summative assessments show that one teacher more positively affected student achievement than the other. By positive, we mean that those students demonstrate solid conceptual understanding of the topic and can apply it to novel situations. What could account for the differences? Did one teacher have all the higher achievers, better lab equipment or access to technology, or a higher academic degree? We would argue that the answer resides in the clear intentional decisions made by the teacher before, during, and after the lesson. Random attempts at improving instruction should be replaced with intentional strategies addressing three areas: knowing the big ideas, leading challenging and engaging lessons, and revising instruction based on student performance.
A Para- and Dia-Magnetism Balance
Authors: Daffron John A.
Published: August 2009

Paramagnetic and diamagnetic effects are very weak, compared to ferromagnetic effects, and conditions must be optimized to give a satisfactory demonstration of them. The samples must be pure, the magnetic field strong, and frictional forces must be held to a minimum. The simple design in Fig. 1 fulfills all of these conditions.
Seven Feynman Video Lectures: The Character of Physical Law from Microsoft Research
Authors: MacIsaac Dan
Published: August 2009

Microsoft Research, in collaboration with Microsoft Corp. Chairman Bill Gates, has purchased rights and is freely streaming Feynman's seven Cornell 1964 lectures on The Character of Physical Law. I watched and greatly enjoyed the first introductory lecture on gravitation. The lectures are being used to demonstrate a new Microsoft video annotation format product called Microsoft Silverlight. While the videos and Silverlight are freely available from Microsoft for a limited selection of platforms, operating systems (OSs) and browsers, I was unable to make Silverlight run on my elderly Mac, or to install Silverlight on several PCs in our physics department. I did manage to watch the first video (only) on a colleague's more recent Mac laptop.
The Brainiacs and the Electric Fence from YouTube
Authors: MacIsaac Dan
Published: August 2009

A humorous collection of classic Ben Franklin-era electrostatics experiments demonstrating conduction and insulation effects reenacted with a group of barefooted college-age volunteers in t-shirts known as “braniacs” and a commercial farm-grade electric fence. Quite humorous and compelling, with a noteworthy musical track. Brainiac: Science Abuse is a UK science entertainment show with several episodes on YouTube and a website with some freely available shows at http://sky1.sky.com/show/brainiac. Note that the Skynet site (like Hulu or Showtime or online TV network sites) has other, adult-themed television content not suitable for the classroom. See also the excellent Benjamin Franklin and Electrostatics website at the Wright Center at Tufts University by Dr. Robert Morse: http://tinyurl.com/2szs2c, especially the QuickTime video clip entitled “Drawing the Fire” that you can reenact with your students in the classroom.
Increasing Physics Enrollment in Your School
Authors: Barrett Earl
Published: August 2009

Forty-one years of teaching nearly every science course offered in high school has given me a pretty good perspective on science teaching. All physics teachers who are practicing a teaching style that actively engages students know that they teach a course of great value to young people. Active engagement techniques used in teaching physics allow the student the intellectual freedom to be an integral part of the learning experience—from planning a laboratory experiment to finding answers to questions, to collecting and analyzing the data, to formulating precise written language and mathematical expressions that describe the results. Working in small lab groups allows students to develop team-building and work-related skills. Confronting students with novel situations provides the opportunity to apply the newly learned principle, so depth of understanding can be measured in a meaningful way. Counselors, administrators, and fellow staff should be invited to be project judges whenever possible.
Simplified “on‐couch” daily quality assurance procedure for CT simulators
Authors: Liu Ruijie Rachel , Prado Karl , Gillin Michael
Published: August 2009

For most computed tomography (CT) simulators, radiation therapists must first remove the fat couch top in order to perform daily CT quality assurance (QA), and then use separate tools to perform localization‐laser QA. This process wastes time and effort, and creates the opportunity for accidents to occur. In this study, we tested a simple, yet comprehensive, daily QA program and phantom designed for CT simulators used in radiation oncology that would enable us to use only one tool to perform both laser and imaging QA on a fat couch. To construct a modified QA phantom, we attached three adjustable legs and fastened two metric scales (one vertically and one horizontally) to a commercial CT QA phantom. The adjustable legs helped to position and level the phantom conveniently in the needed position. The two metric scales were used for localization‐laser QA, while the phantom body was used for CT imaging QA. We evaluated five different CT scanners from two manufacturers with their designated couches to evaluate this phantom system. Since the couch is scanned along with the phantom, we evaluated the couch's effect on image quality. We found that the presence of the couch top changed the uniformity of water's CT number slightly, but did not change the visual image resolution. The couch top also produced different, yet reproducible, effects on image quality. The effects were greatest in the section of the phantom closest to the couch top. For a commercial carbon fiber couch top, the variation was within 3 Hounsfield Units (HU). The effect was couch‐ and scanner‐specific, and could be incorporated into the QA acceptability criteria for each CT scanner. By using the proposed QA program and phantom, we have been able to implement more thorough QA while decreasing the amount of effort and time the simulation therapists spend performing laser and imaging QA.

PACS number(s): 87.55.Gh, 87.55.Qr, 87.56.Fc, 87.57.Q‐
Application of holographic display in radiotherapy treatment planning II: a multi‐institutional study
Authors: Chu James C H , Gong Xing , Cai Yang , Kirk Michael C , Zusag Thomas W , Shott Susan , Rivard Mark J , Melhus Christopher S , Cardarelli Gene A , Hurley Amanda , Hepel Jaroslaw T , Napoli Josh , Stutsman Sandy , Abrams Ross A
Published: August 2009

We hypothesized that use of a true 3D display providing easy visualization of patient anatomy and dose distribution would lead to the production of better quality radiation therapy treatment plans. We report on a randomized prospective multi‐institutional study to evaluate a novel 3D display for treatment planning.

The Perspecta® Spatial 3D System produces 360° holograms by projecting cross‐sectional images on a diffuser screen rotating at 900 rpm. Specially‐developed software allows bi‐directional transfer of image and dose data between Perspecta and the Pinnacle planning system.

Thirty‐three patients previously treated at three institutions were included in this IRB‐approved study. Patient data were de‐identified, randomized, and assigned to different planners. A physician at each institution reviewed the cases and established planning objectives. Two treatment plans were then produced for each patient, one based on the Pinnacle system alone and another in conjunction with Perspecta. Plan quality was then evaluated by the same physicians who established the planning objectives. All plans were viewable on both Perspecta and Pinnacle for review. Reviewing physicians were blinded to the planning device used. Data from a 13‐patient pilot study were also included in the analysis.

Perspecta plans were considered better in 28 patients (61%), Pinnacle in 14 patients (30%), and both were equivalent in 4 patients. The use of non‐coplanar beams was more common with Perspecta plans (82% vs. 27%). The mean target dose differed by less than 2% between rival plans. Perspecta plans were somewhat more likely to have the hot spot located inside the target (43% vs. 33%). Conversely, 30% of the Pinnacle plans had the hot spot outside the target compared with 18% for Perspecta plans. About 57% of normal organs received less dose from Perspecta plans. No statistically significant association was found between plan preference and planning institution or planner.

The study found that use of the holographic display leads to radiotherapy plans preferred in a majority of cases over those developed with 2D displays. These data indicate that continued development of this technology for clinical implementation is warranted.

PACS numbers: 87.55.D
Construction of anthropomorphic phantoms for use in dosimetry studies
Authors: Winslow James F. , Hyer Daniel E. , Fisher Ryan F. , Tien Christopher J. , Hintenlang David E.
Published: August 2009

This paper reports on the methodology and materials used to construct anthropomorphic phantoms for use in dosimetry studies, improving on methods and materials previously described by Jones et al. [Med Phys. 2006;33(9):3274–82]. To date, the methodology described has been successfully used to create a series of three different adult phantoms at the University of Florida (UF). All phantoms were constructed in 5 mm transverse slices using materials designed to mimic human tissue at diagnostic photon energies: soft tissue‐equivalent substitute (STES), lung tissue‐equivalent substitute (LTES), and bone tissue‐equivalent substitute (BTES). While the formulation for BTES remains unchanged from the previous epoxy resin compound developed by Jones et al. [Med Phys. 2003;30(8):2072—81], both the STES and LTES were redesigned utilizing a urethane‐based compound which forms a pliable tissue‐equivalent material. These urethane‐based materials were chosen in part for improved phantom durability and easier accommodation of real‐time dosimeters. The production process has also been streamlined with the use of an automated machining system to create molds for the phantom slices from bitmap images based on the original segmented computed tomography (CT) datasets. Information regarding the new tissue‐equivalent materials, as well as images of the construction process and completed phantom, are included.

PACS number: 87.53.Bn
eIMRT: a web platform for the verification and optimization of radiation treatment plans
Authors: Pena Javier , González‐Castaño Diego M , Gómez Faustino , Gago‐Arias Araceli , González‐Castaño Francisco J. , Rodríguez‐Silva Daniel , Gómez Andrés , Mouriño Carlos , Pombar Miguel , Sánchez Manuel
Published: August 2009

The eIMRT platform is a remote distributed computing tool that provides users with Internet access to three different services: Monte Carlo optimization of treatment plans, CRT & IMRT treatment optimization, and a database of relevant radiation treatments/clinical cases. These services are accessible through a user‐friendly and platform independent web page. Its flexible and scalable design focuses on providing the final users with services rather than a collection of software pieces. All input and output data (CT, contours, treatment plans and dose distributions) are handled using the DICOM format.

The design, implementation, and support of the verification and optimization algorithms are hidden to the user. This allows a unified, robust handling of the software and hardware that enables these computation‐intensive services. The eIMRT platform is currently hosted by the Galician Supercomputing Center (CESGA) and may be accessible upon request (there is a demo version at http://eimrt.cesga.es:8080/eIMRT2/demo; request access in http://eimrt.cesga.es/signup.html).

This paper describes all aspects of the eIMRT algorithms in depth its user interface, and its services. Due to the flexible design of the platform, it has numerous applications including the intercenter comparison of treatment planning, the quality assurance of radiation treatments, the design and implementation of new approaches to certain types of treatments, and the sharing of information on radiation treatment techniques.

In addition, the web platform and software tools developed for treatment verification and optimization have a modular design that allows the user to extend them with new algorithms. This software is not a commercial product. It is the result of the collaborative effort of different public research institutions and is planned to be distributed as an open source project. In this way, it will be available to any user; new releases will be generated with the new implemented codes or upgrades.

PACS number: 87.55.kh
Image quality & dosimetric property of an investigational Imaging Beam Line MV‐CBCT
Authors: Beltran Chris , Lukose Renin , Gangadharan Bijumon , Bani‐Hashemi Ali , Faddegon Bruce A.
Published: August 2009

To measure and compare the contrast to noise ratio (CNR) as a function of dose for the CBCTs produced by the mega‐voltage (MV) imaging beam line (IBL) and the treatment beam line (TBL), and to compare the dose to target and various critical structures of pediatric patients for the IBL CBCT versus standard TBL orthogonal port films.

Two Siemens Oncor linear accelerators were modified at our institution such that the MV‐CBCT would operate under an investigational IBL rather than the standard 6MV TBL. Prior to the modification, several CBCTs of an electron density phantom were acquired with the TBL at various dose values. After the modification, another set of CBCTs of the electron density phantom were acquired for various doses using the IBL. The contrast to noise ratio (CNR) for each tissue equivalent insert was calculated. In addition, a dosimetric study of pediatric patients was conducted comparing the 1 cGy IBL CBCT and conventional TBL orthogonal pair port films.

The CNR for eight tissue equivalent inserts at five different dose settings for each type of CBCT was measured. The CNR of the muscle insert was 0.8 for a 5 cGy TBL CBCT, 1.1 for a 1.5 cGy IBL CBCT, and 2.8 for a conventional CT. The CNR of the trabecular bone insert was 2.9 for a 5 cGy TBL CBCT, 5.5 for a 1.5 cGy IBL CBCT, and 14.8 for a conventional CT. The IBL CBCT delivered approximately one‐fourth the dose to the target and critical structures of the patients as compared to the TBL orthogonal pair port films.

The IBL CBCT improves image quality while simultaneously reducing the dose to the patient as compared to the TBL CBCT. A 1 cGy IBL CBCT, which is used for bony anatomy localization, delivers one‐fourth the dose as compared to conventional ortho‐pair films.

PACS number: 87.57.Q, 87.57.cj, 87.53.Jw