7,500 research outputs found

    Experimental Testing Program in Elementary Chemistry: A Preliminary Report

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    An experimental testing program is described which utilizes questions that are partly computer composed, in addition to a section composed by the instructor, and a retesting option to the student. Results from a trial of the program for one term indicate that (1) course grades were improved, (2) the student withdrawal failure rate was unaffected, and (3) the employed students took greater advantage of the retest than did the unemployed students

    A new species of Dialeurodes Cockerell (Hemiptera: Aleyrodidae) on Schefflera Forst and Forst in Florida

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    Descriptions of pupal cases of Dialeurodes schefflerae, new species, as well as distribution records are presented. This species is known to occur in Florida, Hawaii and Puerto Rico appearing to feed only on species of Schefflera Forst and Forst. This restriction to plant hosts in the Asian genus Schefflera, along with its affinities with Dialeurodes agalmae Takahashi, Dialeurodes citri (Ashmead) and Dialeurodes kirkaldyi (Kotinsky), suggests it is an invasive species, probably endemic to the Asian region

    Final design and fabrication of an active control system for flutter suppression on a supercritical aeroelastic research wing

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    The final design and hardware fabrication was completed for an active control system capable of the required flutter suppression, compatible with and ready for installation in the NASA aeroelastic research wing number 1 (ARW-1) on Firebee II drone flight test vehicle. The flutter suppression system uses vertical acceleration at win buttock line 1.930 (76), with fuselage vertical and roll accelerations subtracted out, to drive wing outboard aileron control surfaces through appropriate symmetric and antisymmetric shaping filters. The goal of providing an increase of 20 percent above the unaugmented vehicle flutter velocity but below the maximum operating condition at Mach 0.98 is exceeded by the final flutter suppression system. Results indicate that the flutter suppression system mechanical and electronic components are ready for installation on the DAST ARW-1 wing and BQM-34E/F drone fuselage

    Extending Quantum Coherence in Diamond

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    We experimentally demonstrate over two orders of magnitude increase in the coherence time of nitrogen vacancy centres in diamond by implementing decoupling techniques. We show that equal pulse spacing decoupling performs just as well as non-periodic Uhrig decoupling and has the additional benefit that it allows us to take advantage of "revivals" in the echo (due to the coherent nature of the bath) to explore the longest coherence times. At short times, we can extend the coherence of particular quantum states out from T_2*=2.7 us out to an effective T_2 > 340 us. For preserving arbitrary states we show the experimental importance of using pulse sequences, that through judicious choice of the phase of the pulses, compensate the imperfections of individual pulses for all input states. At longer times we use these compensated sequences to enhance the echo revivals and show a coherence time of over 1.6 ms in ultra-pure natural abundance 13C diamond.Comment: 7 pages, 7 figures; minor syntax/typo. changes and updated reference

    Vloga ekonomije v gozdnem načrtovanju in ocena gozdne politike v Sloveniji

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    This paper explores the current status of the forest sectors in Slovenia, identifies potential issues in the management and use of the forests, and discusses a means by which policy makers can identify opportunities to enhance the role played by forests and their related goods and services in Slovenia. Specifically, a framework is proposed to assess the relationships between the economic, social, and ecological aspects of Slovenia%s forestseffects of changes in economic conditions on forest demands and useseconomic impacts of ecological, social, and business conditionseffects of current or proposed policiesand opportunities for the sustainable economic development of wood-based and forest-dependent enterprises. Such a framework is critical for managing Slovenia\u27s forests and forestry sector in such a manner to optimize the ecological and economic potential.Prispevek prikazuje raziskavo stanja gozdarskega sektorja v Sloveniji, pokaže na potencialne težave v upravljanju in rabi gozdov ter odpira razpravo o orodjih, s katerimi bi lahko pripravljavci politik opredelili priložnosti za krepitev vloge gozdov v Sloveniji in z njimi povezanih dobrin in storitev. Podan je predlog okvira za analizo: povezav med ekonomskimi, socialnimi in ekološkimi vidiki gozdov v Slovenijivplivov spremenjenih ekonomskih razmer na povpraševanje in rabo gozdnih virovekonomskih vplivov ekoloških in socialnih razmer ter poslovnega okoljaučinkov veljavnih in predlaganih politikin priložnosti za trajnostni ekonomski razvoj podjetništva v lesno-predelovalni panogi in gozdarskem podjetništvu. Tovrstni okvir je ključen za gospodarjenje z gozdovi Slovenije z vidika optimiziranja ekološkega in ekonomskega potenciala gozdarskega sektorja

    The Legal Experience of Mr. Alfred Packer

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    High Seas and High Risks: Proliferation in a Post-9/11 World

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    One of the biggest threats that the world faces is the proliferation of weapons of mass destruction (“WMD”) and their use by rogue states and terrorist groups. As the September 11, 2001 terrorist attacks proved, within the span of a few hours, thousands of people can be killed and the direction of the world can be radically changed through the use of unconventional weapons and tactics. As terrible as the attacks were, however, the carnage and consequences of that day would have seemed like a mere pittance if certain kinds of WMD were used instead. Ever since chemical weapons were used to devastating effect in World War I, nations began employing different tactics to control WMD, including legal, political, diplomatic, and military strategies. One of the *190 latest efforts is the Proliferation Security Initiative (“PSI”), a multilateral agreement with more than one hundred nations to facilitate interdictions of vessels suspected of carrying WMD (a weapon made of nuclear, chemical, or biological materials). Created by the Bush Administration and continued by President Barack Obama, the PSI is both a part of, and separate from, the existing anti-proliferation framework -a fact that makes it somewhat controversial, especially when its participants assert its most far-reaching powers on the high seas. According to longstanding international maritime law, the seas do not belong to any nation and, absent a claim of universal jurisdiction or some other exception, it is illegal to board another ship. For many years, universal jurisdiction could only be exercised to thwart a limited number of offenses, none of which are closely related to WMD proliferation. In response to September 11, however, some states pushed to broaden international maritime law to allow states to board *191 vessels to stop WMD proliferation. The PSI is at the forefront of this expansionary effort. This Article considers whether the PSI can be used to expand universal jurisdiction to stop WMD proliferation and, if so, whether such an expansion is desirable. Part II provides background information on the PSI and past conventions, treaties, and multilateral efforts to stem proliferation and delineate maritime jurisdiction. Part III analyzes the ways in which the PSI and its supporting texts affect universal jurisdiction. Part IV offers three recommendations. First, Part IV(A) recommends that universal jurisdiction should expand under the aegis of the United Nations. Second, Part IV(B) argues that if it cannot expand under the United Nations, then universal jurisdiction should expand by increasing the number of states that belong to the PSI. Third, Part IV(C) proposes that if it cannot expand under the United Nations or by increasing the amount of PSI members, then universal jurisdiction should expand through unilateral interdictions. Lastly, Part V of this Article advocates that universal jurisdiction on the high seas should be expanded to include WMD interdiction

    Modeling of composite beams and plates for static and dynamic analysis

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    The main purpose of this research was to develop a rigorous theory and corresponding computational algorithms for through-the-thickness analysis of composite plates. This type of analysis is needed in order to find the elastic stiffness constants for a plate and to post-process the resulting plate solution in order to find approximate three-dimensional displacement, strain, and stress distributions throughout the plate. This also requires the development of finite deformation plate equations which are compatible with the through-the-thickness analyses. After about one year's work, we settled on the variational-asymptotical method (VAM) as a suitable framework in which to solve these types of problems. VAM was applied to laminated plates with constant thickness in the work of Atilgan and Hodges. The corresponding geometrically nonlinear global deformation analysis of plates was developed by Hodges, Atilgan, and Danielson. A different application of VAM, along with numerical results, was obtained by Hodges, Lee, and Atilgan. An expanded version of this last paper was submitted for publication in the AIAA Journal
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