bluuebunny/crossref_metadata_2025 huggingface dataset:
Hair diameter in systemic lupus erythematosus
Authors: Seyahi E , Seyahi N , Fresko I , Kuyumcu M , Yazici H
Published: April 2006

It is widely appreciated that patients with systemic lupus erythematosus (SLE) get thinner and shorter hair. However little work has been done to quantitate this. We assessed hair thickness of SLE patients and compared this to that of patients with rheumatoid arthritis (RA) and healthy controls (HC). Fifty-seven female patients with SLE (mean age: 32 ± 8 years) and 77 female patients with RA (mean age: 50 ± 12 years) were studied along with 75 healthy women (mean age: 27 ± 6 years). Five strands of hair were taken from each subset and mounted on glass slides. Two independent observers, blind to the sources of the hair, measured the hair strands under a light microscope, using a micrometer. Finally, the mean hair thickness between each of the three groups was calculated. The hair in both SLE and RA patients was found to be thinner than that of HC by both observers ( P < 0.001). Age adjusted analysis between SLE and HC showed similar results. However, there was no significant difference in hair thickness between SLE and RA. SLE patients have thinner hair compared to HC. More studies are needed to investigate the effect of disease activity, therapy and other factors on hair diameter.
The Teacher Behaviors Checklist: Factor Analysis of Its Utility for Evaluating Teaching
Authors: Keeley Jared , Smith Dale , Buskist William
Published: April 2006

We converted the Teacher Behaviors Checklist (TBC; Buskist, Sikorski, Buckley, & Saville, 2002) to an evaluative instrument to assess teaching by adding specific instructions and a Likert-type scale. Factor analysis of the modified TBC produced 2 subscales: caring and supportive and professional competency and communication skills. Further psychometric analysis suggested the instrument possessed excellent construct validity and reliability, underscoring its potential as a tool for assessing teaching. This instrument clearly identifies specific target teaching behaviors that instructors can alter to attempt to improve their teaching effectiveness.
The Echo Approach in Developing Items for Student Evaluation of Teaching Performance
Authors: Cunningham J. Barton , MacGregor James N.
Published: April 2006

This article illustrates the application of the Echo approach, originally designed to identify values of different cultures and subcultures, to the generation of questionnaire items for students to evaluate faculty teaching performance. Students preferred items generated using the Echo method over faculty-designed items and items developed by students without prompts. The Echo-generated items also exhibited higher test–retest reliability than items generated in other ways.
Using Interactive Computer Technology to Enhance Learning
Authors: Pemberton Joy R. , Borrego Joaquin , Cohen Lee M.
Published: April 2006

We assessed the effects of using LearnStar™, an interactive, computer-based teaching tool, as an in-class exam review method. Students with higher LearnStar review scores had higher grades. Furthermore, students' satisfaction ratings indicated that LearnStar reviews were more enjoyable and conducive to participation than traditional reviews. However, students who reviewed using LearnStar did not have significantly higher exam scores or course grades compared to students who had traditional reviews. Future research directions include measuring different aspects of students' engagement in courses and examining the effects of using tools such as LearnStar for other in-class activities such as brief quizzes or polls.
Emerging Issues in Economic Development Policy and Technology Incubators: The Vermont Center for Emerging Technologies Experience
Authors: Ventriss Curtis , Gurdon Michael A
Published: April 2006

This article explores the recent efforts of the University of Vermont to promote technology transfer activities and a technology incubator as a way to stimulate job creation and increase the flow of new, targeted technologies from the University to the marketplace. Specifically, the article examines the Vermont Center for Emerging Technologies (VCET) at the University of Vermont and its role in trying to play a crucial role in facilitating economic growth. Special attention is given to how technology enterprise development and economic development strategies should be custom designed to be congruent with the unique strengths (and weaknesses) of the regional economy. In addition to a literature review pertinent to these issues, a survey and interview data were collected from the key actors associated with VCET. A discussion of broader policy lessons that can be drawn from this case study is explored.
The Cultural Production of Asian American Young Adults in the Novels of Marie G. Lee, An Na, and Doris Jones Yang
Authors: Chiu Monica
Published: April 2006

This essay explores how the production of social subjectivities in these novels is related to the books' production processes and marketing, both suggesting a capitulation to a dominant order. A concentration on curricular ethnic inclusion or on making profits from an audience desiring stereotypical tales about ethnic difference comes at the expense of more interesting elements in fiction, such as narrative form and complex characterization.
Asian American Autobiography for Children: Critical Paradigms and Creative Practice
Authors: Davis RocÃ­o G
Published: April 2006

This essay explores exercises in life writing for children by reading several Asian American autobiographies, to analyze their authors' purposes and factor them as part of a dynamic network of creative writing. Reading these autobiographies critically unveils the writers' strategies of meaning and their significance in the intersecting contexts of Asian American children's literature and genre studies. The texts offer diverse examples of the lives of young Asian or Asian American subjects whose experiences attest to the diversity of the classification "Asian American." The analysis covers a range of texts: some center on pre-immigration life, others on growing up as a minority person in America, others on war and internment, and some on urban life in the United States. This diversity proposes a range of experiences that allow the child reader, particularly the Asian American child, to learn about the possibilities of ethnic experience.
Writing Chinese America into Words and Images: Storytelling and Retelling of The Song of Mu Lan
Authors: Dong Lan
Published: April 2006

The story of the ancient woman warriorâMulanâhas attracted repeated attention in China and the United States. This paper explores how words and images of the recreated Mulan story work together to construct a Chinese American tale that not only captures the cultural heritage of ancient China, but also conveys possibilities for female empowerment in the context of storytelling for Asian American and Asian diaspora children. The discussion on Jeanne Lee's The Song of Mu Lan (1995) will be contextualized with Maxine Hong Kingston's The Woman Warrior (1976) and Disney's animated film Mulan (1998).
"Feeding the Nation" and "Protecting the Watershed"
Authors: Paulson Susan , DeVore Jonathan
Published: April 2006

Tensions between efforts to preserve threatened ecosystems and efforts to improve the life conditions of people who inhabit such areas are of increasing concern in environmental science, policy, and practice. In our research with farmers in the Atlantic Forest of Brazil, we have identified a range of forces, factors, and ideas that influence how farmers develop production strategies and make choices about resource use that have consequences for local environmental conditions and human well‐being. This article aims to support collaborative work between organizations investing in conservation efforts and local peoples inhabiting sites of conservationist concern by drawing attention to farmers discussions of, and responses to, these factors. The article advances a framework for considering the beliefs, needs, and aspirations of local stakeholders together with diverse contextual factors that influence their decisions and productive activities.
Genomic-Assisted Prediction of Genetic Value With Semiparametric Procedures
Authors: Gianola Daniel , Fernando Rohan L , Stella Alessandra
Published: April 2006

Semiparametric procedures for prediction of total genetic value for quantitative traits, which make use of phenotypic and genomic data simultaneously, are presented. The methods focus on the treatment of massive information provided by, e.g., single-nucleotide polymorphisms. It is argued that standard parametric methods for quantitative genetic analysis cannot handle the multiplicity of potential interactions arising in models with, e.g., hundreds of thousands of markers, and that most of the assumptions required for an orthogonal decomposition of variance are violated in artificial and natural populations. This makes nonparametric procedures attractive. Kernel regression and reproducing kernel Hilbert spaces regression procedures are embedded into standard mixed-effects linear models, retaining additive genetic effects under multivariate normality for operational reasons. Inferential procedures are presented, and some extensions are suggested. An example is presented, illustrating the potential of the methodology. Implementations can be carried out after modification of standard software developed by animal breeders for likelihood-based or Bayesian analysis.
Epidermal Growth Factor Receptor and Transforming Growth Factor-β Signaling Contributes to Variation for Wing Shape inDrosophila melanogaster
Authors: Dworkin Ian , Gibson Greg
Published: April 2006

Wing development in Drosophila is a common model system for the dissection of genetic networks and their roles during development. In particular, the RTK and TGF-β regulatory networks appear to be involved with numerous aspects of wing development, including patterning, cell determination, growth, proliferation, and survival in the developing imaginal wing disc. However, little is known as to how subtle changes in the function of these genes may contribute to quantitative variation for wing shape, per se. In this study 50 insertional mutations, representing 43 loci in the RTK, Hedgehog, TGF-β pathways, and their genetically interacting factors were used to study the role of these networks on wing shape. To concurrently examine how genetic background modulates the effects of the mutation, each insertion was introgressed into two wild-type genetic backgrounds. Using geometric morphometric methods, it is shown that the majority of these mutations have profound effects on shape but not size of the wing when measured as heterozygotes. To examine the relationships between how each mutation affects wing shape hierarchical clustering was used. Unlike previous observations of environmental canalization, these mutations did not generally increase within-line variation relative to their wild-type counterparts. These results provide an entry point into the genetics of wing shape and are discussed within the framework of the dissection of complex phenotypes.
Genetic Map-Based Analysis of Genome Structure in the Homosporous Fern Ceratopteris richardii
Authors: Nakazato Takuya , Jung Min-Kyung , Housworth Elizabeth A , Rieseberg Loren H , Gastony Gerald J
Published: April 2006

Homosporous ferns have extremely high chromosome numbers relative to flowering plants, but the species with the lowest chromosome numbers show gene expression patterns typical of diploid organisms, suggesting that they may be diploidized ancient polyploids. To investigate the role of polyploidy in fern genome evolution, and to provide permanent genetic resources for this neglected group, we constructed a high-resolution genetic linkage map of the homosporous fern model species, Ceratopteris richardii (n = 39). Linkage map construction employed 488 doubled haploid lines (DHLs) that were genotyped for 368 RFLP, 358 AFLP, and 3 isozyme markers. Forty-one linkage groups were recovered, with average spacing between markers of 3.18 cM. Most loci (∼76%) are duplicated and most duplicates occur on different linkage groups, indicating that as in other eukaryotic genomes, gene duplication plays a prominent role in shaping the architecture of fern genomes. Although past polyploidization is a potential mechanism for the observed abundance of gene duplicates, a wide range in the number of gene duplicates as well as the absence of large syntenic regions consisting of duplicated gene copies implies that small-scale duplications may be the primary mode of gene duplication in C. richardii. Alternatively, evidence of past polyploidization(s) may be masked by extensive chromosomal rearrangements as well as smaller-scale duplications and deletions following polyploidization(s).
Metabolic Disruption in Drosophila Bang-Sensitive Seizure Mutants
Authors: Fergestad Tim , Bostwick Bret , Ganetzky Barry
Published: April 2006

We examined a number of Drosophila mutants with increased susceptibility to seizures following mechanical or electrical stimulation to better understand the underlying factors that predispose neurons to aberrant activity. Several mutations in this class have been molecularly identified and suggest metabolic disruption as a possible source for increased seizure susceptibility. We mapped the bang-sensitive seizure mutation knockdown (kdn) to cytological position 5F3 and identified citrate synthase as the affected gene. These results further support a role for mitochondrial metabolism in controlling neuronal activity and seizure susceptibility. Biochemical analysis in bang-sensitive mutants revealed reductions in ATP levels consistent with disruption of mitochondrial energy production in these mutants. Electrophysiological analysis of mutants affecting mitochondrial proteins revealed an increased likelihood for a specific pattern of seizure activity. Our data implicate cellular metabolism in regulating seizure susceptibility and suggest that differential sensitivity of neuronal subtypes to metabolic changes underlies distinct types of seizure activity.
Glial and Neuronal Functions of the Drosophila Homolog of the Human SWI/SNF GeneATR-X(DATR-X) and thejingZinc-Finger Gene Specify the Lateral Positioning of Longitudinal Glia and Axons
Authors: Sun Xuetao , Morozova Tatiana , Sonnenfeld Margaret
Published: April 2006

Neuronal–glial communication is essential for constructing the orthogonal axon scaffold in the developing Drosophila central nervous system (CNS). Longitudinal glia (LG) guide extending commissural and longitudinal axons while pioneer and commissural neurons maintain glial survival and positioning. However, the transcriptional regulatory mechanisms controlling these processes are not known. Previous studies showed that the midline function of the jing C2H2-type zinc-finger transcription factor was only partially required for axon scaffold formation in the Drosophila CNS. We therefore screened for gain-of-function enhancers of jing gain of function in the eye and identified the Drosophila homolog of the disease gene of human α-thalassemia/mental retardation X-linked (ATR-X) as well as other genes with potential roles in gene expression, translation, synaptic transmission, and cell cycle. jing and DATR-X reporter genes are expressed in both CNS neurons and glia, including the LG. Coexpression of jing and DATR-X in embryonic neurons synergistically affects longitudinal connective formation. During embryogenesis, jing and DATR-X have autonomous and nonautonomous roles in the lateral positioning of LG, neurons, and longitudinal axons as shown by cell-specific knockdown of gene expression. jing and DATR-X are also required autonomously for glial survival. jing and DATR-X mutations show synergistic effects during longitudinal axon formation suggesting that they are functionally related. These observations support a model in which downstream gene expression controlled by a potential DATR-X–Jing complex facilitates cellular positioning and axon guidance, ultimately allowing for proper connectivity in the developing Drosophila CNS.
Artistic Styles and Personalities: A Close View and a More Distant View
Authors: Machotka Pavel
Published: April 2006

In the empirical study of the arts, two approaches exist which illustrate different assumptions about what phenomena are most central to our concerns: the study of central tendencies, which seeks general principles, and the study of differences, whose aim is to accept differences as crucial and then explain them. Nowhere is the study of variability more important than in the creation of works of art; and no approach to accounting for the variability is more promising than a detailed study of the personalities of the creators. Research is discussed here in which the creation of images by undergraduate participants was followed closely, and their personalities were studied clinically by means of a psychodynamic interview. The individual dynamics seemed intimately connected with the processes of image making (the close view). A later cluster analysis of image types revealed that the individual dynamics were consistent within clusters and different between clusters (the distant view). Seven approaches to image making could be identified in this study and described in detail.
Careers in the Dramatic Arts: Comparing Genetic and Interactional Perspectives
Authors: Kogan Nathan , Kangas Barbara L.
Published: April 2006

Taking account of both intrinsic and environmental determinants, Kogan (2002a, b) describes possible interactions between them in a developmental model of performing-arts careers. An alternative model of talent development is offered by Simonton (1999, 2001), who has drawn upon the earlier behavior-genetic research of Lykken (1982), particularly the concept of emergenesis. Questionnaire data from a sample of 122 students in the Actors Studio drama school was examined for its consistency with the Lykken-Simonton emergenesis model. Consistent with the model's expectations, parental professional participation in the dramatic arts was very low, age at which students decided to pursue a dramatic-arts career varied widely, and students' prior school and undergraduate college experience exhibited considerable heterogeneity. The relative merits of a model based entirely on genetic trajectories are discussed in comparison with interactive and purely environmental models. Given the limited empirical base, however, it is far from evident which approach offers the greatest potential for predicting who will become the best actors, directors, and playwrights of the future.
The Search for Objective Measures of Aesthetic Judgment: The Case of Memory Traces
Authors: Nadal Marcos , Marty Gisèle , Munar Enric
Published: April 2006

Verbal responses have frequently been used to measure aesthetic experience. They usually take the form of semantic judgments regarding specific aspects or dimensions of certain stimuli. The use of this kind of technique has produced a great amount of knowledge, but its combination with objective procedures can increase the validity and reliability of measurement. In this study, we set out to assess whether memory traces can serve as an objective control element for subjective aesthetic judgments. We analyzed the relation between aesthetic judgment and recognition of High Art and Popular Art visual stimuli by participants with and without formal art education. Results show that participants tended to give higher pleasantness and beauty ratings to those stimuli that have left a strong memory trace. Lower scores were awarded to stimuli they did not recognize well. However, originality and interest ratings did not follow the same trend. This disparity is discussed in relation to the dimensionality of aesthetic experience and the influence of formal art education on subjective measures of aesthetic experience.
Investigation of the Prototypicality of Visual Stimuli in the Drawings of Seven-Year-Old Children
Authors: Limont Wieslawa , Dreszer Joanna
Published: April 2006

The aim of the present study was to determine whether simple visual signs (shapes) located on the plane reveal the effect of prototypicality. The research used seven-year-old children's drawings produced from a set of simple line sign stimuli: semicircle, perpendiculars, a straight line, a diagonal, and a wavy line. The stimulus set was rotated on a form into one of four successive positions to change the location of the stimuli. The drawings composed of stimuli of specific shapes were divided into semantic categories. Analyses revealed that the prototypicality of the stimuli is related to both the shape and location of the stimuli. Additionally, the study identified two stimuli, a semicircle and perpendiculars, whose shapes show the effect of prototypicality irrespective of their stimulus location.
The Pendulum Swings Both Ways: A Response to “Ethics and the Hyperreality of the Archaeological Thought World”
Authors: Moeller Roger
Published: April 2006

Without entering into an overly philosophical discussion of intellectual property, self-perpetuating righteousness, and ethical behavior, I prefer to respond to individual statements, the general tone of the presentation, and comparisons in light of recent political developments. The problem comes not from the issues that he raises, but how far he rides the pendulum. I certainly hope that no one is offended at plain language, because I checked my political correctness at the door.
Ethics and the Hyperreality of the Archaeological Thought World
Authors: Custer Jay F.
Published: April 2006

Archaeologists have created a thought world which serves to support their own power and privilege, harms the interests of American Indian people, and aids the on-going cultural genocide focused on Native Americans. However, this thought world is a form of hyperreality. Its images and ideas interact with and perpetuate one another with no reference to reality or meaning. We archaeologists must reject the hyperreality, come to terms with the unethical aspects of our discipline's past and our current actions, enter into meaningful interactions with American Indian people, and cede most of our power and privilege to Indian people in order to develop a truly useful set of archaeological ethics in a real moral world.
Determination of thyroxine in pharmaceuticals using flow injection with luminol chemiluminescence inhibition detection
Authors: Waseem Amir , Yaqoob Mohammad , Nabi Abdul
Published: April 2006

A simple flow injection method is reported for the determination of thyroxine, based on its inhibition effect on luminol–iron(II) chemiluminescence in alkaline medium in the presence of molecular oxygen. The detection limits (2s) for d‐ and l‐thyroxine are 0.08 and 0.1 mg/L, respectively, with a sample throughput of 100/h. The calibration data for d‐ and l‐thyroxine over the range 0.2−1.0 mg/L gives correlation coefficients (r2) of 0.9915 and 0.984 with relative standard deviations (RSD; n = 4) in the range 1.2−2.8%. The effects of some organic compounds was studied on luminol‐iron(II) CL system for thyroxine determination. The method was applied to pharmaceutical thyroxine tablets and the results obtained (in the range 50.5 ± 2.0−51.6 ± 1.2 µg l‐thyroxine/tablet) were in reasonable agreement with the value quoted. Copyright © 2006 John Wiley & Sons, Ltd.
Chitinase‐Catalyzed Synthesis of a Chitin‐Xylan Hybrid Polymer: A Novel Water‐Soluble β(1 → 4) Polysaccharide Having an N‐Acetylglucosamine‐Xylose Repeating Unit
Authors: Kobayashi Shiro , Makino Akira , Tachibana Naoki , Ohmae Masashi
Published: April 2006

Summary: A chitin‐xylan hybrid polysaccharide having β(1 → 4)‐linked alternating structure of N‐acetyl‐D‐glucosamine and D‐xylose was synthesized via chitinase‐catalyzed polymerization. An oxazoline derivative of D‐xylosyl‐β(1 → 4)‐N‐acetyl‐D‐glucosamine (1) was effectively polymerized by the catalysis of chitinase from Bacillus sp., giving rise to a water‐soluble chitin‐xylan hybrid polysaccharide (2) in good yields. Molecular weights ($\overline M _{\rm n}$) of 2 reached 1 500, which corresponds to 8–10 saccharide units.

A chitin‐xylan hybrid polysaccharide (2) synthesized via chitinase‐catalyzed polymerization.

magnified image

A chitin‐xylan hybrid polysaccharide (2) synthesized via chitinase‐catalyzed polymerization.
Atomic Force Microscopy Applied to the Study of Whatman Paper Surface Deteriorated by a Cellulolytic Filamentous Fungus
Authors: Piantanida G. , Pinzari F. , Montanari M. , Bicchieri M. , Coluzza C.
Published: April 2006

In this study AFM technique has been used to observe the degradation of cellulose fibres in paper samples used as substrata for the growth of a filamentous fungus known to be responsible for damage to art works made from or supported on paper. Images obtained from the analysis of artificially deteriorated samples have been used for comparison with topographies obtained by AFM from naturally affected samples. As “control” images, AFM topographies of samples obtained from the same paper quality utilised as substrata for fungal inoculum were considered. The samples that were artificially deteriorated and those naturally affected by biological agents showed, at the molecular level, distinct surface differences when compared with control images. The biodegradation of cellulose fibres that appeared in AFM images can be attributed to the activity of both cellulolytic enzymes and acidic compounds produced by the fungal cells. Further studies using the AFM technique could reveal interesting aspects of paper biodeterioration caused by different microrganisms and might allow for a better description of the different stages of fungal attacks on cellulose fibres.
Miniaturized microstrip array for the UHF‐band RFID reader
Authors: Wu Ze‐hai , Lai Sheng‐li
Published: April 2006

In this paper, a new array antenna composed of Koch fractal microstrip patches for the UHF‐band RFID reader is proposed. The investigation shows that the coupling factor of two fractal patches in the E‐plane is much larger than that in the H‐plane, and the coefficients are smaller than that of the rectangular patch. The characteristics of the Koch array antenna have been demonstrated by experiment results: when the patch iteration factor is 0.25, the 2 × 2 fractal is 22.77% smaller than the rectangular array, and antenna gain at 915 MHz is 9.9 dB, yielding a 7‐m identification‐read range when incorporated with the RFID modules. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 1299–1301, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21617
Electromagnetic bandgap structures as artificial magnetic conductor surfaces sidewalls in parallel plate slot antennas
Authors: Fernández J. M. , Sierra‐Castañer M.
Published: April 2006

Metamaterial structures have unique properties in controlling the propagation of electromagnetic waves. In this work we analyze the effect of a metamaterial denominated EBG structures acting as if they had artificial magnetic conductor (AMC) properties to enhance the main radiation characteristics of parallel‐plate slot antennas. The results using these structures in comparison with conventional perfect electric conductor (PEC) sidewalls in a planar slot antenna are presented as an example of application. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 1441–1446, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21633
Planar compact elliptic‐function low‐pass filter using high‐permittivity ceramics substrate
Authors: Chen Yuan‐Bin , Huang Cheng‐Liang , Lo Ching‐Wen
Published: April 2006

A component elliptic‐function low‐pass filter using microstrip stepped‐impedance hairpin resonators and their equivalent‐circuit models is developed. The prototype filters are synthesized from the equivalent‐circuit model using available element value tables. To optimize the performance of the filters, electro‐magnetic simulation is used to tune the dimensions of the prototype filters. The filter using multiple cascaded hairpin resonators provides a very sharp cutoff‐frequency response with low insertion loss. The full‐wave simulator IE3D is used to design the elliptic‐function low‐pass filter. The response of the fabricated filter using Al2O3 (εr = 9.7, Q × f = 350,000 GHz) and La(Mg1/2Ti1/2)O3 (εr = 28.6 Q × f = 60,000 GHz). © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 1393–1398, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21637
A dual‐layered wideband microstrip reflectarray antenna with variable polarization
Authors: Wu Zhi‐Hang , Zhang Wen‐Xun , Liu Zhen‐Guo , Shen Wei
Published: April 2006

This paper presents a new kind of microstrip reflectarray antenna those polarization could be reconfigurable among all polarization states instead of some fixed states for dual‐ or multipolarized antenna. The mechanism for polarized variability is so simple that only mechanical rotation is needed. The complete theoretical analysis is given as well as a specific design sample to verify this method. At designed frequency of 10 GHz and in case of circularly polarized (CP) radiation, experimental results in agreement with simulated ones exhibit −26‐dB cross‐polar level (CPL), −13‐dB side‐lobe level, 13.5° half‐power beamwidth, and 17.3‐dBi gain corresponding to about 40% aperture efficiency. It also possesses 8% bandwidth from 9.5 to 10.3 GHz for CPL less than −15 dB. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 1429–1432, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21640
A millimeter‐wave slow‐wave bandpass filter using compact microstrip stepped‐impedance hairpin resonator with inter‐digital capacitor on GaAs substrate
Authors: Cho Ju‐Hyun , Yun Tae‐Soon , Lee Myeong‐Gil , Baek Tae‐Jong , Shin Dong‐Hoon , Lee Jong‐Chul
Published: April 2006

In this paper, a new microstrip stepped‐impedance hairpin resonator with interdigital capacitor (IDC) slow‐wave band‐pass filter (BPF) using dielectric supported air‐gapped microstrip line (DAML) of surface micromachining on GaAs substrate is proposed. Unlike conventional slow‐wave filters, the proposed bandpass filters are designed to produce a narrow passband at the fundamental mode of the resonators with small size and a sharp skirt characteristic. The proposed slow‐wave band‐pass filter with IDC is designed to produce a passband of 7.7% at the fundamental frequency of 56 GHz. It shows insertion loss of 3.37 dB, return loss of better than 15 dB, and a stopband characteristic greater than 31 dB within 37.03–45.51 GHz. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 1244–1247, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21667
Analysis of 1D PBG structure using the wavelet‐Galerkin time‐domain method
Authors: Dai Shao‐yu , Wu Zhen‐sen
Published: April 2006

In this paper, an accelerated wavelet‐Galerkin time‐domain (WGTD) scheme for electromagnetic scattering is presented, and a numerical interface is applied to overcome the complexity of connection and absorption boundaries. The obtained reflection coefficients of photonic bandgap (PBG) show that the WGTD scheme can increase cell size without sacrificing solution accuracy and thus improve efficiency. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 1258–1261, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21670
Acoustic behaviour of a liquid/vapour mixture in a standing-wave tube
Authors: Coste C. , Laroche C.
Published: April 2006

We study the acoustic behaviour of a mixture of diethyl-ether bubbles and liquid, at small volume fraction of vapour, contained in a standing-wave tube. We give experimental evidence of the effect of the liquid/vapour phase transition on the positions and amplitudes of the resonances of the tube. The effective-medium theory, which properly describes the behaviour of liquid/gas mixtures, is shown to be inadequate. We find that theoretical studies which take the effect of the phase transition into account do agree with our experimental data.
Nonlinear effects in the dynamics of shape and volume oscillations for a gas bubble in an external flow
Authors: Yang S. M. , Feng Z. C. , Leal L. G.
Published: April 2006

This paper considers the dynamics of a gas bubble in response to either a pressure pulse or a pressure step at t = 0, both in the presence and absence of a mean flow. Our work utilizes small-deformation, domain perturbation analysis carried to second and higher order in the amplitude of deformation, ε. In the absence of a mean flow, our analysis of the small deformation problem for an initial impulsive perturbation of the bubble volume and shape is closely related to recently published work by Longuet-Higgins on the time-dependent oscillations of an initially deformed bubble in a quiescent fluid. However, in the presence of a mean flow which deforms the bubble, the bubble response to pressure changes is more complex. Specifically, the present analysis identifies a number of different mechanisms for resonant interaction between shape deformation modes and the volume or radial breathing mode of oscillation. This includes not only a fundamental change in the resonant interactions at 0(ε2) - where resonant interaction is also found in the absence of mean flow – but resonant interactions also at the level of 0(ε3/2;) which are not present without the mean flow. On the other hand, the bubble dynamics in response to a step change in the pressure distribution in a quiescent fluid exhibits similar resonant interactions at 0(ε2) to those obtained for a pressure pulse in the presence of mean flow because the bubble oscillates around a non-spherical steady-state shape owing to the non-uniform pressure distribution on the bubble surface in both the cases.
The interaction of deep-water gravity waves and an annular current: linear theory
Authors: Gerber Marius
Published: April 2006

The interaction of linear, steady, axisymmetric deep-water gravity waves with preexisting large-scale annular currents has been investigated. Waves originating inside the annulus as well as waves approaching the annulus from the outside were studied. Exact linear ray solutions were obtained and involve two non-dimensional parameters, a radius-angle parameter and a velocity parameter. For opposing currents the linear solutions also allow the derivation of radii at which the waves are blocked, reflected at a linear caustic or stopped by the current. Various examples of rays interacting with an annular current are presented to illustrate aspects of the solutions obtained. In particular, the behaviour of the ray solutions at blocking, reflection and stopping is investigated. Linear ray theory is shown to fail at caustics and caustic solutions are briefly discussed.
Free-surface Taylor vortices
Authors: Wang F. J. , Domoto G. A.
Published: April 2006

The hydrodynamic instability of a viscous incompressible flow with a free surface is studied both numerically and experimentally. While the free-surface flow is basically two-dimensional at low Reynolds numbers, a three-dimensional secondary flow pattern similar to the Taylor vorticies between two concentric cylinders appears at higher rotational speeds. The secondary flow has periodic velocity components in the axial direction and is characterized by a distinct spatially periodic variation in surface height similar to a standing wave. A numerical method, using boundary-fitted coordinates and multigrid methods to solve the Navier–Stokes equations in primitive variables, is developed to treat two-dimensional free-surface flows. A similar numerical technique is applied to the linearized three-dimensional perturbation equations to treat the onset of secondary flows. Experimental measurements have been obtained using light sheet techniques to visualize the secondary flow near the free surface. Photographs of streak lines were taken and compared to the numerical calculations. It has been shown that the solution of the linearized equations contains most of the important features of the nonlinear secondary flows at Reynolds number higher than the critical value. The experimental results also show that the numerical method predicts well the onset of instability in terms of the critical wavenumber and Reynolds number.
The coupling of wind and internal waves: modulation and friction mechanisms
Authors: Kudryavtsev V. N.
Published: April 2006

The interaction between internal waves (IW) and wind waves (WW) is studied. Three types of interaction are considered: spontaneous IW generation by a random field of WWs, and two feedback mechanisms - modulation and friction.

The latter mechanism has not been studied before. Its influence on the IW-WW coupling is of primary importance. The modulation and friction mechanisms result in exponential attenuation of the IWs. Attenuation of IWs propagating against wind is the strongest. The IW attenuation has a dimensionless decrement of order 10-3, whereas for storm winds it attains the value of 10-2. Joint action of the spontaneous generation of IWs and their attenuation due to feedback mechanisms permits a stationary ‘wind-IW’ spectrum to exist. For strong winds the ‘wind-IW’ energy is of order 105erg cm-2. The effect of IWs on currents in the ocean's upper layer is considered. Momentum and energy lost by IWs due to their interaction with WWs generates inertial oscillations. Under the attenuation of intensive IWs, the amplitude of inertial oscillations may be compared with the background Ekman current.
On vortex air motions above an axisymmetric source of mass, momentum and heat
Authors: Berezin Y. A. , Hutter K.
Published: April 2006

We study axisymmetric plume dispersion from a steady source of mass, momentum and/or heat that is subjected to either a time-dependent large-scale external vortex or small-scale turbulent axisymmetric helicity. On the basis of the turbulent boundary layer and Boussinesq assumptions and by assuming similarity profiles with Gaussian distribution in the radial direction the balance equations of mass, momentum, and energy reduce to a system of nonlinear differential equations for amplitude functions of axial velocity, pressure and density differences as well as azimuthal velocity. The system of equations is closed with Taylor's entrainment assumption.

The plume radius and the typical radius of the large-scale external vortex are also determined. For a simple density structure of the ambient atmosphere (i.e. adiabatic conditions) analytical results can be obtained, but for more complicated cases, i.e. a layered polytropic atmosphere, the governing equations are examined numerically; computations are reasonably simple and efficient.
The motion of a rising disk in a rotating axially bounded fluid for large Taylor number
Authors: Ungarish Marius , Vedensky Dmitry
Published: April 2006

The motion of a disk rising steadily along the axis in a rotating fluid between two infinite plates is considered. In the limit of zero Rossby number and with the disk in the middle position, the boundary value problem based on the linear, viscous equations of motion is reduced to a system of dual-integral equations which renders ‘exact’ solutions for arbitrary values of the Taylor number, Ta, and disk-to-wall distance, H (scaled by the radius of the disk). The investigation is focused on the drag and on the flow field when Ta is large (but finite) for various H. Comparisons with previous asymptotic results for ‘short’ and ‘long’ containers, and with the preceding unbounded-configuration ‘exact’ solution, provide both confirmation and novel insights.

In particular, it is shown that the ‘free’ Taylor column on the particle appears for H > 0.08 Ta and attains its fully developed features when H > 0.25 Ta (approximately). The present drag calculations improve the compatibility of the linear theory with Maxworthy's (1968) experiments in short containers, but for the long container the claimed discrepancy with experiments remains unexplained.
Boundary-layer transition triggered by hairpin eddies at subcritical Reynolds numbers
Authors: Asai Masahito , Nishioka Michio
Published: April 2006

Subcritical transition in a flat-plate boundary layer is examined experimentally through observing its nonlinear response to energetic hairpin eddies acoustically excited at the leading edge of the boundary-layer plate. When disturbed by the hairpin eddies convecting from the leading edge, the near-wall flow develops local three-dimensional wall shear layers with streamwise vortices. Such local wall shear layers also evolve into hairpin eddies in succession to lead to the subcritical transition beyond the x-Reynolds number Rx = 3.9 × 104, where the momentum thickness Reynolds number Rθ is 127 for laminar Blasius flow without excitation, and is about 150 under the excitation of energetic hairpin eddies. It is found that in terms of u- and v-fluctuations, the intensity of the near-wall activity at this critical station is of almost the same order as or slightly less than that of the developed wall turbulence. The development of wall turbulence structure in this transition is also examined.
Mass transport of interfacial waves in a two-layer fluid system
Authors: Wen Jiangang , Liu Philip L.-F.
Published: April 2006

Effects of viscous damping on mass transport velocity in a two-layer fluid system are studied. A temporally decaying small-amplitude interfacial wave is assumed to propagate in the fluids. The establishment and the decay of mean motions are considered as an initial-boundary-value problem. This transient problem is solved by using a Laplace transform with a numerical inversion. It is found that thin ‘second boundary layers’ are formed adjacent to the interfacial Stokes boundary layers. The thickness of these second boundary layers is of O(ε1/2) in the non-dimensional form, where ε is the dimensionless Stokes boundary layer thickness defined as $\epsilon = \hat{k}\hat{\delta}=\hat{k}(2\hat{v}/\hat{\sigma})^{1/2}$ for an interfacial wave with wave amplitude â, wavenumber $\hat{k}$ and frequency $\hat{\sigma}$ in a fluid with viscosity $\hat{v}$. Inside the second boundary layers there exists a strong steady streaming of O(α2ε−1/2), where $\alpha = \hat{k}\hat{a}$ is the surface wave slope. The mass transport velocity near the interface is much larger than that in a single-layer system, which is O(α2) (e.g. Longuet-Higgins 1953; Craik 1982). In the core regions outside the thin second boundary layers, the mass transport velocity is enhanced by the diffusion of the mean interfacial velocity and vorticity. Because of vertical diffusion and viscous damping of the mean interfacial vorticity, the ‘interfacial second boundary layers’ diminish as time increases. The mean motions eventually die out owing to viscous attenuation. The mass transport velocity profiles are very different from those obtained by Dore (1970, 1973) which ignored viscous attenuation. When a temporally decaying small-amplitude surface progressive wave is propagating in the system, the mean motions are found to be much less significant, O(α2).
Internal hydraulic jumps at T-junctions
Authors: Roberts Paul A. , Hibberd Stephen
Published: April 2006

This paper presents a theoretical investigation of the occurrence of hydraulic jumps in two-layer systems induced by extraction of fluid from the upper layer. The physical configuration consists of a horizontal main pipe along which air and water flow, and a vertically upward side arm. An hydraulic model based on the momentum principle assuming that the fluids do not mix is developed that leads to at least two possible conjugate states for any given two-layer flow. A method of determining the amount of gas which must be extracted into the side arm for a jump to occur is developed and predictions shown to be in reasonable agreement with observation. Unusually, it is shown that above this critical gas take-off value two possible states remain energetically feasible.
The lower limit of photon fluence rate for phototrophic growth: the significance of ‘slippage’ reactions
Authors: RAVEN JOHN A. , BEARDALL JOHN
Published: April 2006

Abstract. The role of ‘slippage’ reactions, in the form of passive H+ uniport through CF0‐CF1, ATP synthetase and breakdown of the S2 and S3 intermediates of O2 evolution, is considered in relation to the growth of phototrophic organisms at low photon fluence rates. Analysis of the limited data available suggests that adaptation (phenotypic or genotypic) to low photon fluence rates is accompanied by an increase in the ratio of light‐absorbing pigments to the (potentially slippage‐inducing) photosystem two units and CF0‐CF1 ATP synthetases. Furthermore, organisms which are genotypically adapted to high photon fluence rates do not, when grown at low photon fluence rates, achieve the same low ratio of reaction centres to total light‐harvesting pigments as is found in phototrophs genotypically adapted to low photon fluence rates. The limits to, and energy costs of, such a mechanism of adaptation to low photon fluence rates are also discussed.
Are electrostatic forces involved in pollen transfer?
Authors: CORBET SARAH A. , BEAMENT JAMES , EISIKOWITCH D.
Published: April 2006

Abstract. The measurements of Yes'kov & Sapozhnikov (1976) suggest that electrostatic potentials on foraging honeybees can reach hundreds of volts. Pollen grains of oilseed rape, Brassica napus L., subjected experimentally to potentials of this order, jumped a distance that increased approximately as the square of the voltage, between two pin electrodes on which, in some experiments, were impaled an anther or stigma of oilseed rape or a freshly‐killed honeybee. Most floral surfaces were insulated, but there was a low‐impedance path to earth via the stigma, and the electrostatic field due to an approaching charged bee must therefore concentrate there. Thus, if electrostatic potentials of this magnitude occur in nature they may increase the chance that pollen from bees will reach the stigma rather than other floral surfaces, as well as enabling pollen to jump from anther to bee and from bee to stigma across an air gap of the order of 0.5 mm.
Structure and function of the elongation sink in the stems of higher plants.*
Authors: MIZUNO AKIKO , OKAMOTO HISASHI
Published: April 2006

Abstract. Application of an acid aerosol generated from an aqueous HC1 or HNO3 solution (pH 1‐2) to the hypocotyl segment of Vigna sesquipedalis, excised from the elongation zone and abraded with alumina gel, induced rapid elongation growth comparable with that induced by aerosol generated from neutral 1 mol m−3 1AA aqueous solution. The activity of the first electrogenic ion pump, whose activity is known to be stimulated by IAA aerosol in advance of the increase in growth rate, was little affected by acids. The latent period of the growth response to acids was only 1 min shorter than that to IAA (mean value: 12min), or than the period from the stimulation of the electrogenic ion pump activity by IAA to the beginning of growth acceleration (mean value: 4 min). The growth rate, together with the activities of the first and the second ion pump, was reduced by anoxia in the presence of acid. The acid N2‐sol was ineffective to stimulate the elongation under anoxia. The acid aerosol was ineffective to stimulate the elongation of a non‐abraded segment with intact cuticle layer on its surface.