Identical Sections Research Articles

Broadband three-section symmetrical directional couplers with reduced coupling coefficient requirements

A new class of broadband symmetrical directional couplers has been investigated. The proposed couplers consist of three coupled-line sections with the middle coupled-line section connected between two identical coupled-line sections in such a way that the coupled and transmission ports of the resulting three-section directional coupler are exchanged in comparison to the well-known three-section symmetrical directional coupler. By choosing coupling coefficients and electrical lengths it is possible to achieve an equal-ripple coupling characteristic. Theoretical analysis has been performed and the properties of the proposed directional couplers are compared to the well-known multisection couplers. The presented theoretical analysis has been verified by the design. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:639–645, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27401

Effect of Nose Tip on Wing Rock of Slender Delta Wing

The root cause of wing rock is investigated by examining two slender delta wings (700 and 850 sweep back angle) in wind tunnel using force measurement, pressure measurement and PIV techniques. The results show presence of asymmetric flow at 200 angle of attack and initiation of wing rock at the same point for 850 model while there is neither asymmetric flow nor wing rock for 700 model suggesting close relation of flow asymmetry with wing rock. Investigation with three apparently identical nose sections reveals that the asymmetry comes from the area very close to the wing tip. This asymmetric flow causes the vortices to interact in a complex way resulting in wing rock when the vortices are in close proximity (such as for 850 model), which is not the case when the vortices are ‘comparatively away’ (such as 700 model) from each other.

Dynamic balancing method for the single-threaded, fixed-pitch screw rotor

The screw rotor is the most important component of dry screw vacuum pumps used in various industrial applications. In this paper, a method for determining the dynamic balance of the single-threaded, fixed-pitch screw rotor is proposed based on previous research. A specific structure is designed in order to meet the demand of engineering. In this structure, two cavities with identical sections are preformed on both end faces of the rotor. The two cavities have the same shape, the same symmetric location relative to each other, and the same pitch with the screw rotor. All the structural parameters of the cavities are described, and the dynamic balancing of the screw rotor is feasible by closely following the procedure. Considering the calculation method does not depend on the form of the end-face profile, it can be used with any type of screw rotor end-face profile.

Overall buckling behavior of all-steel buckling restrained braces

One of the key requirements for the desirable mechanical behavior of buckling restrained braces (BRBs) under severe earthquake loading is to prevent global buckling until the brace member reaches sufficient plastic deformation and ductility. This paper presents finite element analysis results of the proposed all-steel buckling restrained braces. The proposed BRBs have identical core sections but different buckling restraining mechanisms (BRMs). The objective of the analysis is to conduct a parametric study of BRBs with different amounts of gap (between the core and the BRM) and initial imperfections to investigate the global buckling behavior of the brace. The results of the analysis showed that BRM flexural stiffness could significantly affect the global buckling behavior of a brace, regardless of the size of the gap. In addition, a minimum ratio of the Euler buckling load of the restraining member to the yield strength of the core, Pe/Py is suggested for design purposes. This ratio is the principal parameter that controls the global buckling of BRBs.

The Impact of Mindful Awareness Practices on College Student Health, Well-Being, and Capacity for Learning: A Pilot Study

This preliminary study examined the feasibility and potential utility of mindful awareness practices (MAPs) in terms of enhancing student learning in the college classroom, as well as improving psychological well-being. One of two identical undergraduate psychology sections included a 10-minute MAP at the beginning of every class (mindfulness group n = 37; control group n = 23). Primary learning and secondary self-report outcomes were obtained. Controlling for significant demographic covariates, students in the mindfulness group demonstrated significant increases in mindful awareness traits and reductions in rumination and state anxiety compared with controls. While mindfulness intervention did not lead to significant improvement in academic performance across the semester, 81% of students self-reported positive effects of MAPs on their learning. It is concluded that it is feasible to incorporate MAPs into a regular college classroom. MAPs may help improve student psychological well-being. Although students perceived themselves to benefit from their mindfulness practice, further research is needed to examine the effects of MAPs on student academic performance.

A Practical Approach to Anesthesia Equipment

A Practical Approach to Anesthesia Equipment

Space matters: The impact of formal learning environments on student learning

AbstractThe objective of this research is to identify the relationship between formal learning spaces and student learning outcomes. Using a quasi‐experimental design, researchers partnered with an instructor who taught identical sections of the same course in two radically different formal learning environments to isolate the impact of the physical environment on student learning. The results of the study reveal that, holding all factors excepting the learning spaces constant, students taking the course in a technologically enhanced environment conducive to active learning techniques outperformed their peers who were taking the same course in a more traditional classroom setting. The evidence suggests strongly that technologically enhanced learning environments, independent of all other factors, have a significant and positive impact on student learning.

Comparison of student performance using web- and paper- based homework in large enrollment introductory physics courses

The effects of web-based homework and paper-and-pencil homework on student achievement were compared by conducting conceptual tests, exams, and homework assignments. The study was performed on two groups (287 students in total) during three semesters at a public university in the middle region of the US. Of the two identical sections of an introductory calculus-based course, students in one section received paper-and-pencil homework, while the students in the other section received web-based homework. When the results obtained from the study were evaluated statistically, it was found that there was not any significant difference in conceptual test and exam scores between the two groups throughout the three semesters. However, the homework performance scores for the web-based homework group were higher than the performance scores of the paper-and-pencil homework group. Key words: Higher education, paper-and-pencil homework, physics education, web-based homework.

Comparison of Experimental Techniques for Evaluating the Correction Factor of a Rectangular Waveguide Microcalorimeter

We evaluated the correction factor of a new WR-15 (50-75 GHz) rectangular waveguide microcalorimeter with four different techniques. The four methods are in agreement. The technique with the lowest uncertainty utilized two identical microcalorimeter core sections whose reference planes were connected to each other. Use of this technique has enabled us to reduce the uncertainty in effective efficiency by a factor of 2.5 relative to an earlier microcalorimeter.

An Offset Compensation Method With Low Residual Drift for Integrated Thermal Flow Sensors

A new offset compensation approach for integrated thermal flow meters is described. The method is based on micromachined differential flow sensing structures with the heater split into two identical and symmetrical sections. The power unbalance between the two heaters is used to compensate the intrinsic sensor offset. The effectiveness of the approach is proven by means of experiments performed on micro flow meters fabricated by postprocessing chips produced with a commercial microelectronic process. The tests were devoted to demonstrate the robustness of the offset compensation with respect to variation of both the gas temperature and type.

Second harmonic generation and multiphoton microscopic detection of collagen without the need for species specific antibodies

High-resolution, high-contrast, three-dimensional images of live cell and tissue architecture can be obtained using second harmonic generation (SHG), which comprises non-absorptive frequency changes in an excitation laser line. SHG does not require any exogenous antibody or fluorophore labeling, and can generate images from unstained sections of several key endogenous biomolecules, in a wide variety of species and from different types of processed tissue. Here, we examined normal control human skin sections and human burn scar tissues using SHG on a multi-photon microscope (MPM). Examination and comparison of normal human skin and burn scar tissue demonstrated a clear arrangement of fibers in the dermis, similar to dermal collagen fiber signals. Fluorescence-staining confirmed the MPM-SHG collagen colocalization with antibody staining for dermal collagen type-I but not fibronectin or elastin. Furthermore, we were able to detect collagen MPM-SHG signal in human frozen sections as well as in unstained paraffin embedded tissue sections that were then compared with hematoxylin and eosin staining in the identical sections. This same approach was also successful in localizing collagen in porcine and ovine skin samples, and may be particularly important when species-specific antibodies may not be available. Collectively, our results demonstrate that MPM SHG-detection is a useful tool for high resolution examination of collagen architecture in both normal and wounded human, porcine and ovine dermal tissue.

Selection of minimal tripping times for distance protection using fault trees with time dependencies

Correct coordination between protection relays is an essential requirement to maintain stability and integrity of electrical power systems. Time settings of protection relays have to be adapted to time characteristics of electrical power systems and time settings of other protections. In the paper, fault trees with time dependencies (FTTD) are used for selecting time delay settings of remote back-up distance protections. In FTTD, events and gates are characterized by time parameters, which are derived from time characteristics of protection devices and the inherent delays of protection equipment. Two case studies are presented. First, the coordination of protections for the simple transmission line composed of two identical sections is studied. Next, the transmission line that contains two sections of different lengths and transformer between them is analyzed. In both cases, formulae for time delays of protections are derived. According to calculations executed for the first case, our method gives time delays that often are significantly smaller than values suggested by generally recommended and accepted rules.

Long-Term Experiments of Composite Steel-Concrete Beams

This paper presents three sets of full-scale experiments aimed at the evaluation of the long-term behaviour of composite steel concrete beams designed with partial shear connection formed by a steel joist and a solid or composite concrete slab. All specimens were designed in accordance with Australian guidelines. In the first set of experiments three full scale simply-supported composite beams with solid concrete slabs having identical spans and cross sections were prepared and tested. The three beams were cast simultaneously in order to enable comparisons with respect to pouring and loading conditions. The second set of experiments was similar to the first one while using a composite slab instead of a solid one. The third set included the long-term testing of a two span continuous composite beam. A web side plate connection was placed at the internal support to reflect typical Australian detailing practice of flooring systems in which such a joint is usually adopted between secondary and primary beams. For this purpose, the supported solid concrete slab was continuous over the connection. The sustained load was applied by means of concrete blocks placed along the whole member length. The long-term response of these composite members was monitored by measuring the changes in deflections, curvature, strain and slip occurring over time. For each set of experiment, standard tests were carried out on concrete, steel and shear connectors to determine their material properties.

Heating a bowl of single-molecule-soup: structure and desorption energetics of water-encapsulated open-cage [60] fullerenoid anions in the gas-phase

The gas-phase unimolecular decay kinetics of an anionic, open-cage [60] fullerene derivative encapsulating one water molecule is studied by means of black-body IR radiation induced dissociation (BIRD) in the temperature programmable ion trap of a Fourier-transform ion cyclotron resonance (FT-ICR) mass spectrometer. The primary reaction channel observed is escape of the water molecule from the fullerenoid bowl. The rate constants for this water loss as a function of temperature are evaluated using the Arrhenius equation to yield an activation energy of 104 ± 4 kJ mol(-1). A complementary ion mobility spectrometry study contrasting the water-encapsulated and the empty fullerene cages finds identical collision cross sections to within experimental error-supporting the structural assignment of this gas-phase anion as an endohedral (i.e. encapsulated) species. Both experiments were compared with quantum-chemical computations which well-describe the transition state for water desorption and the concomitant binding and activation energies.

Immunohistochemical and Immunocytochemical Localization of Amylase in Rat Parotid Glands and von Ebner's Glands by Ion Etching-Immunoscanning Electron Microscopy

The distribution of amylase in rat parotid glands and von Ebner’s glands was examined using ion etching-immunoscanning electron microscopy, which enables both light and electron microscopic observations of identical semi-thin resin sections immunolabeled with anti-α-amylase and immunogold in association with silver enhancement. At the light microscopic level, most acinar secretory granules (SG) and striated duct secretions of parotid glands were strongly stained dark brown. In von Ebner’s glands, acinar SG and duct secretions were weakly to strongly stained light to dark brown. At the electron microscopic level, labeling was observed as bright gold-silver particles. The labeling intensity of acinar SG of parotid glands was higher than that of von Ebner’s glands. In parotid glands, weak labeling of SG in transitional cells between acini and intercalated ducts, very weak labeling of SG in intercalated ducts, and strong labeling of striated duct secretions were observed. In von Ebner’s glands, the secretions and some SG of interlobular ducts were strongly labeled compared to those of intralobular ducts and SG of acini. Less amylase was synthesized in von Ebner’s acini compared to parotid acini, whereas von Ebner’s ducts may secrete significantly more amylase to modify saliva than parotid ducts.

Effect of the manufacturing process on the behaviour of press-braked thin-walled steel columns

The manufacturing process of cold-formed thin-walled steel columns induces cold work in them and significantly affects their behaviour. This effect has traditionally been assessed using idealised residual stress distributions based on limited laboratory measurements in conjunction with the specification of different mechanical properties for the flat portions and the corner regions. This conventional approach is highly empirical and often does not accurately reflect the effect of cold work on column behaviour. This paper presents an advanced numerical approach for modelling the full-range structural behaviour of press-braked thin-walled steel columns, in which the effect of cold work is accurately and explicitly represented. In the proposed approach, the amount of cold work is quantified using residual stresses and the equivalent plastic strains predicted by a closed-form analytical solution for the cold-forming process and these analytical predictions are directly included in a finite element model for nonlinear buckling analysis. Using results obtained from this advanced numerical column model, the effect of cold work on column behaviour is examined for both carbon and stainless steel sections. The numerical results also explain why both the residual stresses and the column behaviour of cold-formed steel sections may differ considerably among nominally identical sections. The proposed method has the potential to replace laboratory tests to a large extent and can thus be deployed in future research to minimise the need for expensive laboratory testing.

Wasted on the Young? Comparing the Performance and Attitudes of Younger and Older US Adults in an Online Class on Geographic Information

This study investigates the counter-intuitive observation that older students tend to thrive better than younger students in online classes. We use a variety of measures to compare performance and attitudes of undergraduates and continuing adult professionals in separate but nearly identical class sections led by the same instructor at a US university during the same nine-month study period. Findings are consistent with theoretical predictions about differences in readiness of younger and older adults for self-directed learning experiences. Results also suggest that online educators should be proactive in stimulating younger students' participation in class discussions, and should find ways to evaluate explicitly the tacit learning that online discussion can foster.

Calculated cross sections for transport coefficients of H 2 dilute in He and HI gas

Relaxation cross sections determining transport coefficients of the binary systems He–H 2 and HI–H 2 have been calculated by using the Waldmann–Snider formalism of the linearized collision operator. After starting with the rotational relaxation times, which are determined by inelastic rotational transitions only, all the following contributions of relaxation cross sections to the binary transport coefficients of the viscosity, heat conductivity, and diffusion have been confined to the valid isotropic approximations, i.e. containing results of elastic collisions, which are only slightly corrected by inelastic effects. Cross sections of the pure gas components have not been done in this paper. The prepared input data have been differential cross sections of a sufficient number of energies and enough initial rotational j states of the molecules to produce converged results at temperatures from 5 K up to 1000 K. Convergence with regard to the contributed j states are shown in figures, the resulting numbers of the cross sections are printed in tables for temperatures up to 600 K. The results show almost identical cross sections for the ortho-H 2 and para-H 2 gas components in relaxation cross sections of purely translational motion, whereas cross sections pertaining purely internal rotational motion are significantly different for para-H 2 and ortho-H 2, and cross sections pertaining coupling of rotational–translational motion could be shown to be negligible as demonstrated in figures.

Mission Possible: National Bioethics Commissions Beyond the Conservative/Liberal Divide

Mission Possible:National Bioethics Commissions Beyond the Conservative/Liberal Divide F. Daniel Davis (bio) What's a National Bioethics Commission to Do? Beyond the Conservative/Liberal Divide In June 2009, President Obama dissolved his predecessor's President's Council on Bioethics (PCBE), announced the formation of a new President's Commission for the Study of Bioethical Issues (PCSBI), and spurred another round in an ongoing debate about the mission or mandate of a national bioethics commission, its methods, and the criteria by which its work should be judged. Given the contemporary climate for political and moral discourse in this country, one should not be too surprised that this once civil debate has become less so, diminished rather than enriched by sound-bite caricatures of the opposing sides and needlessly pitched between polar positions, one staked out and defended by conservatives and the other by liberals. This is an essay, an attempt, to develop a position beyond the conservative/liberal divide. In simplified form, the conservative position is that a commission's mandate is to deliberate about fundamental philosophical questions generated by advances in biotechnology and by evolving practices in health care and biomedical research—questions about the ends of human life, human dignity and human flourishing. Shunning consensus as a goal, a commission should seek instead to elucidate the differing, often conflicting views of these ends and thereby enlighten the public and policymakers. The liberal position is that a commission's mission is to deliberate on bioethical questions with the eminently practical aim of achieving a consensus, thereby modeling the processes by which citizens in a liberal pluralistic democracy can and should deliberate together on these same questions. And, through the attainment of consensus, a commission should provide an ethically secure, politically legitimate basis for public policy. Within the constraints of this either/or of seemingly irreconcilable positions, one is either for or against consensus. One is either for or against deliberation on fundamentally philosophical questions. One is either for or against the claim that a commission should contribute to the practical process of ethically enlightened policy making. In this essay, I attempt to defend a third position, unfettered by these constraints. From the perspective that informs my attempt, the dichotomy of conservative and liberal standpoints on the question of a commission's proper mandate appears false and over-determined—over-determined, that is, by the polarized character of contemporary political discourse and by the often strident controversy that surrounded the PCBE, generating critics and defenders who give no quarter to their opposition. As for the substance of my position, it is informed by scholarly engagement with the theory and history of public bioethics and by personal experience, for I served, from January 2006 to September 2009, as PCBE's executive director. I set out from the basic observation that in the U.S., bioethics commissions have been, and should continue to be responsive to different needs—needs of the public and policymakers and for ethical advice. A commission can provide that advice in different forms, depending upon the specific need. The specific need determines the form of the advice rendered as well as the method and goal of a commission's deliberations. Thus, a commission should not be restricted to a particular process or goal and should, instead, have the flexibility to adapt these to the specific need for the advice it is called upon to give. Despite the rhetoric of today's debate, this sort of flexibility is observable in the actual practices of recent bioethics commissions, including the PCBE. My position, however, imposes three necessary conditions on the rendering of that advice by a bioethics commission. First, in deliberating with the aim of providing the needed advice, even if the need is for "practical policy options," a commission must reckon with philosophical fundamentals, with ends as well as means, with often conflicting visions of what is good, right, and just.1 Second, the advice rendered should be responsive to a need explicitly identified and articulated by the President (or by his surrogates in the executive branch). The executive order that established PCBE and the more recent order creating PCSBI contain nearly identical second sections stating that the...

Phylogenetic relationships of ornamental species in <i>Allium</i> L. subg. <i>Melanocrommyum</i> (Webb et Berthel.) Rouy (Alliaceae)

About 30 ornamental Allium species are affiliated to nine sections of subg. Melanocrommyum. Recent molecular investigations (sequences of the Internal Transcribed Spacer of nuclear DNA and the trnL-trnF region of chloroplast DNA) showed that most sections are either para- or polyphyletic. Therefore, genetic relationship of these ornamental taxa cannot simply be deduced from affiliation to identical sections. After a brief historical outline, the current affiliation is discussed in connection with relevant molecular data. Molecular data confirmed these pairs of very closely related species: A. nigrum / A. atropurpureum; A. orientale / A. cyrilli; A. alexeianum / A. nevskianum; A. stipitatum / A. altissimum; but their next related species are mostly other ones than formerly deduced from morphological similarities. Allium hollandicum is a species-pair only with Iranian accessions of A. stipitatum and might be of Iranian offspring. A remarkable genetic diversity related to geography was found in A. rosenorum / A. jesdianum, and A. stipitatum. Allium akaka in the wide sense consists of several taxa. Among the material of A. darwasicum two genetically different entities were detected. Unexpectedly, A. giganteum, A. macleanii, A. protensum, A. caspium, A. lipskyanum, A. aflatunense, A. backhousianum, A. karataviense, A. cupuliferum, A. cristophii, A. regelii, A. cardiostemon, A. aschersonianum A. schubertii, A. fetisowii, and A. decipiens occupy phylogenetic positions rather isolated from their morphologically most similar species.