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2011

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Articles 7291 - 7320 of 7768

Full-Text Articles in Physical Sciences and Mathematics

Tcp Congestion Avoidance Algorithm Identification, Peng Yang, Wen Luo, Lisong Xu, Jitender S. Deogun, Ying Lu Jan 2011

Tcp Congestion Avoidance Algorithm Identification, Peng Yang, Wen Luo, Lisong Xu, Jitender S. Deogun, Ying Lu

School of Computing: Conference and Workshop Papers

The Internet has recently been evolving from homogeneous congestion control to heterogeneous congestion control. Several years ago, Internet traffic was mainly controlled by the traditional AIMD algorithm, whereas Internet traffic is now controlled by many different TCP algorithms, such as AIMD, BIC, CUBIC, and CTCP. However, there is very little work on the performance and stability study of the Internet with heterogeneous congestion control. One fundamental reason is the lack of the deployment information of different TCP algorithms. In this paper, we first propose a tool called TCP Congestion Avoidance Algorithm Identification (CAAI) for actively identifying the TCP algorithm of …

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Using Property-Based Oracles When Testing Embedded System Applications, Tingting Yu, Ahyoung Sung, Witawas Srisaan, Gregg Rothermel Jan 2011

Using Property-Based Oracles When Testing Embedded System Applications, Tingting Yu, Ahyoung Sung, Witawas Srisaan, Gregg Rothermel

School of Computing: Conference and Workshop Papers

Embedded systems are becoming increasingly ubiquitous, controlling a wide variety of popular and safety critical devices. Effective testing techniques could improve the dependability of these systems. In prior work we presented an approach for testing embedded systems, focusing on embedded system applications and the tasks that comprise them. In this work we focus on a second but equally important aspect of testing embedded systems; namely, the need to provide observability of system behavior sufficient to allow engineers to detect failures. We present several property-based oracles that can be instantiated in embedded systems through program analysis and instrumentation, and can detect …

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Automatic Generation Of Load Tests, Pingyu Zhang, Sebastian Elbaum, Matthew Dwyer Jan 2011

Automatic Generation Of Load Tests, Pingyu Zhang, Sebastian Elbaum, Matthew Dwyer

School of Computing: Conference and Workshop Papers

Load tests aim to validate whether system performance is acceptable under peak conditions. Existing test generation techniques induce load by increasing the size or rate of the input. Ignoring the particular input values, however, may lead to test suites that grossly mischaracterize a system’s performance. To address this limitation we introduce a mixed symbolic execution based approach that is unique in how it 1) favors program paths associated with a performance measure of interest, 2) operates in an iterative-deepening beam-search fashion to discard paths that are unlikely to lead to high-load tests, and 3) generates a test suite of a …

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Response Time Analysis Of Hierarchical Scheduling: The Synchronized Deferrable Servers Approach, Haitao Zhu, Steve Goddard, M. Dwyer Jan 2011

Response Time Analysis Of Hierarchical Scheduling: The Synchronized Deferrable Servers Approach, Haitao Zhu, Steve Goddard, M. Dwyer

School of Computing: Conference and Workshop Papers

Hierarchical scheduling allows reservation of processor bandwidth and the use of different schedulers for different applications on a single platform. We propose a hierarchical scheduling interface called synchronized deferrable servers that can reserve different processor bandwidth on each core, and can combine global and partitioned scheduling on a multicore platform. Significant challenges will arise in the response time analysis of a task set if the tasks are globally scheduled on a multiprocessor platform and the processor bandwidth reserved for the tasks on each processor is different; as a result, existing works on response time analysis for dedicated scheduling on identical …

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Experiences With Dynamic Circuit Creation In A Regional Network Testbed, Pragatheeswaran Angu, Byrav Ramamurthy Jan 2011

Experiences With Dynamic Circuit Creation In A Regional Network Testbed, Pragatheeswaran Angu, Byrav Ramamurthy

School of Computing: Conference and Workshop Papers

In this paper we share our experiences of enabling dynamic circuit creation in the GpENI network. GpENI is a network research testbed in the mid-west USA involving several educational institutions. University of Nebraska-Lincoln is involved in provisioning dynamic circuits across the GpENI network among its participating universities. We discuss several options investigated for deploying dynamic circuits over the GpENI network as well as our demonstration experiments at the GENI engineering conferences. UNL has also collaborated with ProtoGENI project of University of Utah and Mid-Atlantic Crossroads (MAX) facility of Washington DC to create interdomain dynamic circuits.

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End-User Programmers And Their Communities: An Artifact-Based Analysis, Kathryn T. Stolee, Sebastian Elbaum, Anita Sarma Jan 2011

End-User Programmers And Their Communities: An Artifact-Based Analysis, Kathryn T. Stolee, Sebastian Elbaum, Anita Sarma

School of Computing: Conference and Workshop Papers

End-user programmers outnumber professionals programmers, write software that matters to an increasingly large number of users, and face software engineering challenges that are similar to their professionals counterparts. Yet, we know little about how these end-user programmers create and share artifacts as part of a community. To gain a better understanding of these issues, we perform an artifact-based community analysis of 32,000 mashups from the Yahoo! Pipes repository. We observed that, like with other online communities, there is great deal of attrition but authors that persevere tend to improve over time, creating pipes that are more configurable, diverse, complex, and …

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Annual Outflow Of Water From Nebraska, 1950 - 2010, S. Olafsen-Lackey Jan 2011

Annual Outflow Of Water From Nebraska, 1950 - 2010, S. Olafsen-Lackey

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.

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Transition From One-Dimensional Water To Ferroelectric Ice Within A Supramolecular Architecture, Hai-Xia Zhao, Xiang-Jian Kong, Hui Li, Yi-Chang Jin, La-Sheng Long, Xiao Cheng Zeng, Rong-Bin Huang, Lan-Sun Zheng Jan 2011

Transition From One-Dimensional Water To Ferroelectric Ice Within A Supramolecular Architecture, Hai-Xia Zhao, Xiang-Jian Kong, Hui Li, Yi-Chang Jin, La-Sheng Long, Xiao Cheng Zeng, Rong-Bin Huang, Lan-Sun Zheng

Xiao Cheng Zeng Publications

Ferroelectric materials are characterized by spontaneous electric polarization that can be reversed by inverting an external electric field. Owing to their unique properties, ferroelectric materials have found broad applications in microelectronics, computers, and transducers. Water molecules are dipolar and thus ferroelectric alignment of water molecules is conceivable when water freezes into special forms of ice. Although the ferroelectric ice XI has been proposed to exist on Uranus, Neptune, or Pluto, evidence of a fully protonordered ferroelectric ice is still elusive. To date, existence of ferroelectric ice with partial ferroelectric alignment has been demonstrated only in thin films of ice grown …

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Structure Evolution Of Gold Cluster Anions Between The Planar And Cage Structures By Isoelectronic Substitution: AuN− (N = 13–15) And MauN− (N = 12–14; M = Ag, Cu), Rhitankar Pal, Lei-Ming Wang, Wei Huang, Lai-Sheng Wang, Xiao Cheng Zeng Jan 2011

Structure Evolution Of Gold Cluster Anions Between The Planar And Cage Structures By Isoelectronic Substitution: AuN− (N = 13–15) And MauN− (N = 12–14; M = Ag, Cu), Rhitankar Pal, Lei-Ming Wang, Wei Huang, Lai-Sheng Wang, Xiao Cheng Zeng

Xiao Cheng Zeng Publications

The structural and electronic effects of isoelectronic substitution by Ag and Cu atoms on gold cluster anions in the size range between 13 and 15 atoms are studied using a combination of photoelectron spectroscopy and first-principles density functional calculations. The most stable structures of the doped clusters are compared with those of the undoped Au clusters in the same size range. The joint experimental and theoretical study reveals a new C3v symmetric isomer for Au13 −, which is present in the experiment, but has hitherto not been recognized. The global minima of Au14 − and Au …

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Diagnosis Of Multiple Scan-Chain Faults In The Presence Of System Logic Defects, Zhen Chen, Sharad C. Seth, Dong Xiang, Bhargab B. Bhattacharya Jan 2011

Diagnosis Of Multiple Scan-Chain Faults In The Presence Of System Logic Defects, Zhen Chen, Sharad C. Seth, Dong Xiang, Bhargab B. Bhattacharya

School of Computing: Conference and Workshop Papers

We present a combined hardware-software based approach to scan-chain diagnosis, when the outcome of a test may be affected by system faults occurring in the logic outside of the scan chain. For the hardware component we adopt the double-tree scan (DTS) chain architecture, which has previously been shown to be effective in reducing power, volume, and application time of tests for stuck-at and delay faults. We develop a version of flush test which can resolve a multiple fault in a DTS chain to a small number of suspect candidates. Further resolution to a unique multiple fault is enabled by the …

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Reference List For Describing Cuttings And Cores Of Sediments And Sedimentary Rocks In Nebraska, J. T. Korus, Robert Matthew Joeckel, P. R. Hanson, J. W. Goeke, S. O. Lackey, M. B. Burbach Jan 2011

Reference List For Describing Cuttings And Cores Of Sediments And Sedimentary Rocks In Nebraska, J. T. Korus, Robert Matthew Joeckel, P. R. Hanson, J. W. Goeke, S. O. Lackey, M. B. Burbach

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.

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Estimating Hydraulic Conductivity For The Martian Subsurface Based On Drainage Patterns — A Case Study In The Mare Tyrrhenum Quadrangle, Wei Luo, Bartosz Grudzinski, Darryll T. Pederson Jan 2011

Estimating Hydraulic Conductivity For The Martian Subsurface Based On Drainage Patterns — A Case Study In The Mare Tyrrhenum Quadrangle, Wei Luo, Bartosz Grudzinski, Darryll T. Pederson

Department of Earth and Atmospheric Sciences: Faculty Publications

Hydraulic conductivity K, as the coefficient of proportionality in Darcy’s Law, is critical in understanding the past Martian hydrologic cycle, climate, and landform evolution. However, K and its spatial variability on Mars are thus far poorly constrained due to lack of accessibility. Using an innovative method based on surface drainage dissection patterns, which has been successfully tested in the Oregon Cascades on Earth, we estimated K in the Mare Tyrrhenum Quadrangle on Mars. The basic assumption is that under long-term dynamic equilibrium conditions, the overall dissection pattern in a watershed as reflected in drainage density is controlled by the …

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Late Pleistocene Dune Activity In The Central Great Plains, Usa, Joseph A. Mason, James B. Swinehart, Paul R. Hanson, David Loope, Ronald J. Goble, Xiaodong Miao, Rebecca L Schmeisser Jan 2011

Late Pleistocene Dune Activity In The Central Great Plains, Usa, Joseph A. Mason, James B. Swinehart, Paul R. Hanson, David Loope, Ronald J. Goble, Xiaodong Miao, Rebecca L Schmeisser

Department of Earth and Atmospheric Sciences: Faculty Publications

Stabilized dunes of the central Great Plains, especially the megabarchans and large barchanoid ridges of the Nebraska Sand Hills, provide dramatic evidence of late Quaternary environmental change. Episodic Holocene dune activity in this region is now well-documented, but Late Pleistocene dune mobility has remained poorly documented, despite early interpretations of the Sand Hills dunes as Pleistocene relicts. New optically stimulated luminescence (OSL) ages from drill cores and outcrops provide evidence of Late Pleistocene dune activity at sites distributed across the central Great Plains. In addition, Late Pleistocene eolian sands deposited at 20–25 ka are interbedded with loess south of the …

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Using Observations Of Distant Quasars To Constrain Quantum Gravity, Eric S. Perlman, Yeejack Ng, David J.E. Floyd, Wayne A. Christiansen Jan 2011

Using Observations Of Distant Quasars To Constrain Quantum Gravity, Eric S. Perlman, Yeejack Ng, David J.E. Floyd, Wayne A. Christiansen

Aerospace, Physics, and Space Science Faculty Publications

Aims. The small-scale nature of spacetime can be tested with observations of distant quasars. We comment on a recent paper by Tamburini et al. (2011, A&A, 533, A71) which claims that Hubble Space Telescope (HST) observations of the most distant quasars place severe constraints on models of foamy spacetime. Methods. If space is foamy on the Planck scale, photons emitted from distant objects will accumulate uncertainties in distance and propagation directions thus affecting the expected angular size of a compact object as a function of redshift. We discuss the geometry of foamy spacetime, and the appropriate distance measure for calculating …

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The Period And Amplitude Changes In The Coolest Gw Virginis Variable Star (Pg 1159-Type) Pg 0122+200, Gérard P. Vauclair, Jianning Fu, Jan Erik Solheim, Seunglee Kim, Noël Dolez, M Chevreton, Li Chen, Matt A. Wood, Isaac M. Silver, Zs Bognár, Margit Paparó, Alejandro H. Córsico Jan 2011

The Period And Amplitude Changes In The Coolest Gw Virginis Variable Star (Pg 1159-Type) Pg 0122+200, Gérard P. Vauclair, Jianning Fu, Jan Erik Solheim, Seunglee Kim, Noël Dolez, M Chevreton, Li Chen, Matt A. Wood, Isaac M. Silver, Zs Bognár, Margit Paparó, Alejandro H. Córsico

Aerospace, Physics, and Space Science Faculty Publications

Context: The PG 1159 pre-white dwarf stars experiment a rapidly cooling phase with a time scale of a few 106 years. Theoretical models predict that the neutrinos produced in their core should play a dominant role in the cooling, mainly at the cool end of the PG 1159 sequence. Measuring the evolutionary time scale of the coolest PG 1159 stars could offer a unique opportunity to empirically constrain the neutrino emission rate. Aims. A subgroup of the PG 1159 stars are nonradial pulsators, the GW Vir type of variable stars. They exhibit g-mode pulsations with periods of a few hundred …

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The Increasing Rotation Period Of Comet 10p/Tempel 2, Matthew M. Knight, Tony L. Farnham, David G. Schleicher, Edward W. Schwieterman Jan 2011

The Increasing Rotation Period Of Comet 10p/Tempel 2, Matthew M. Knight, Tony L. Farnham, David G. Schleicher, Edward W. Schwieterman

Aerospace, Physics, and Space Science Faculty Publications

We imaged comet 10P/Tempel 2 on 32 nights from 1999 April through 2000 March. R-band light curves were obtained on 11 of these nights from 1999 April through 1999 June, prior to both the onset of significant coma activity and perihelion. Phasing of the data yields a double-peaked light curve and indicates a nucleus rotational period of 8.941 ± 0.002 hr with a peak-to-peak amplitude of ∼0.75 mag. Our data are sufficient to rule out all other possible double-peaked solutions as well as the single- and triple-peaked solutions. This rotation period agrees with one of five possible solutions found in …

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Suppression Of Away-Side Jet Fragments With Respect To The Reaction Plane In Au + Au Collisions At √Snn=200 Gev, Andrew Marshall Adare, Gyöngyi Baksay, László A. Baksay, Szabolcs Rembeczki, Marcus Hohlmann Jan 2011

Suppression Of Away-Side Jet Fragments With Respect To The Reaction Plane In Au + Au Collisions At √Snn=200 Gev, Andrew Marshall Adare, Gyöngyi Baksay, László A. Baksay, Szabolcs Rembeczki, Marcus Hohlmann

Aerospace, Physics, and Space Science Faculty Publications

Pair correlations between large transverse momentum neutral pion triggers (pT=4 - 7 GeV/c) and charged hadron partners (pT=3 - 7 GeV/c) in central (0%-20%) and midcentral (20%-60%) Au+Au collisions at √sNN=200 GeV are presented as a function of trigger orientation with respect to the reaction plane. The particles are at larger momentum than where jet shape modifications have been observed, and the correlations are sensitive to the energy loss of partons traveling through hot dense matter. An out-of-plane trigger particle produces only 26±20% of the away-side pairs that are observed opposite of an in-plane trigger particle for midcentral (20%-60%) collisions. …

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Suppression Of Away-Side Jet Fragments With Respect To The Reaction Plane In Au + Au Collisions At √Snn=200 Gev, Andrew Marshall Adare, Gyöngyi Baksay, László A. Baksay, Szabolcs Rembeczki, Marcus Hohlmann, Phenix Collaboration Jan 2011

Suppression Of Away-Side Jet Fragments With Respect To The Reaction Plane In Au + Au Collisions At √Snn=200 Gev, Andrew Marshall Adare, Gyöngyi Baksay, László A. Baksay, Szabolcs Rembeczki, Marcus Hohlmann, Phenix Collaboration

Aerospace, Physics, and Space Science Faculty Publications

Pair correlations between large transverse momentum neutral pion triggers (pT=4 - 7 GeV/c) and charged hadron partners (pT=3 - 7 GeV/c) in central (0%-20%) and midcentral (20%-60%) Au+Au collisions at √sNN=200 GeV are presented as a function of trigger orientation with respect to the reaction plane. The particles are at larger momentum than where jet shape modifications have been observed, and the correlations are sensitive to the energy loss of partons traveling through hot dense matter. An out-of-plane trigger particle produces only 26±20% of the away-side pairs that are observed opposite of an in-plane trigger particle for midcentral (20%-60%) collisions. …

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Melting Kinetics In Microgravity, Martin E. Glicksman Jan 2011

Melting Kinetics In Microgravity, Martin E. Glicksman

Aerospace, Physics, and Space Science Faculty Publications

We analyzed the large data archive obtained from microgravity experiments called the Isothermal Dendritic Growth Experiment (IDGE). The final orbital mission of the IDGE allowed streaming of real-time video of crystal growth and melting in low-Earth orbit of high-purity pivalic acid anhydride (PVA). Melting kinetics was observed in detail for the first time under microgravity conditions. Normally, terrestrial gravity precludes observation and analysis of conduction-limited melting by stimulating buoyancy flows and inducing collapse of the solid-liquid structure. The initial dendritic mushy zone melts under steady heating into isolated crystallite clusters that remain stationary within the melt, and eventually shrink toward …

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The Lightning-Tgf Relationship On Microsecond Ttimescales, Steven A. Cummer, Gaopeng Lu, Michael S. Briggs, Valerie Connaughton, Shaolin Xiong, Gerald Jerry Fishman, Joseph R. Dwyer Jan 2011

The Lightning-Tgf Relationship On Microsecond Ttimescales, Steven A. Cummer, Gaopeng Lu, Michael S. Briggs, Valerie Connaughton, Shaolin Xiong, Gerald Jerry Fishman, Joseph R. Dwyer

Aerospace, Physics, and Space Science Faculty Publications

We analyze the count rates of two terrestrial gamma-ray flashes (TGFs) detected by the Fermi Gamma-ray Burst Monitor (GBM) with the broadband magnetic fields (1 to 300 kHz) produced by the simultaneous lightning processes. The microsecond-scale absolute time accuracy for these data, combined with independent geolocations of the source lightning, enable this analysis with higher accuracy than previously possible. In both events, fast discharge-like processes occur within several tens of microseconds of the gamma-ray generation, although not with a consistent relationship. The magnetic field data also show a slower signal component produced by a source current that in both events …

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Electron-Positron Beams From Terrestrial Lightning Observed With Fermi Gbm, Michael S. Briggs, Joseph R. Dwyer Jan 2011

Electron-Positron Beams From Terrestrial Lightning Observed With Fermi Gbm, Michael S. Briggs, Joseph R. Dwyer

Aerospace, Physics, and Space Science Faculty Publications

Terrestrial Gamma-ray Flashes (TGFs) are brief pulses of energetic radiation observed in low-earth orbit. They are associated with thunderstorms and lightning and have been observed both as gamma-ray and electron flashes depending on the position of the spacecraft with respect to the source. While gamma-ray TGFs are detected as short pulses lasting less than 1 ms, most TGFs seen by the Fermi Gamma-ray Burst Monitor (GBM) with durations greater than 1 ms are, instead, the result of electrons traveling from the sources along geomagnetic field lines. We perform spectral analysis of the three brightest electron TGFs detected by GBM and …

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The Rarity Of Terrestrial Gamma-Ray Flashes, D. M. Smith, Michael E. Splitt, Steven M. Lazarus, W. Ulrich, Jospeh R. Dwyer Jan 2011

The Rarity Of Terrestrial Gamma-Ray Flashes, D. M. Smith, Michael E. Splitt, Steven M. Lazarus, W. Ulrich, Jospeh R. Dwyer

Aerospace, Physics, and Space Science Faculty Publications

We report on the first search for Terrestrial Gamma-ray Flashes (TGFs) from altitudes where they are thought to be produced. The Airborne Detector for Energetic Lightning Emissions (ADELE), an array of gamma-ray detectors, was flown near the tops of Florida thunderstorms in August/September 2009. The plane passed within 10 km horizontal distance of 1213 lightning discharges and only once detected a TGF. If these discharges had produced TGFs of the same intensity as those seen from space, every one should have been seen by ADELE. Separate and significant nondetections are established for intracloud lightning, negative cloud-to-ground lightning, and narrow bipolar …

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Low-Energy Electron Production By Relativistic Runaway Electron Avalanches In Air, Joseph R. Dwyer, Leonid P. Babich Jan 2011

Low-Energy Electron Production By Relativistic Runaway Electron Avalanches In Air, Joseph R. Dwyer, Leonid P. Babich

Aerospace, Physics, and Space Science Faculty Publications

This paper investigates the production of low-energy (few eV) electrons by relativistic runaway electron avalanches. This work is motivated by a growing body of literature that claims that runaway electron avalanches produce an anomalous growth of low-energy electrons and hence an anomalously large electrical conductivity, a factor of 50 larger than expected from standard calculations. Such large enhancements would have a substantial impact on properties of runaway electron avalanches and their observable effects. Indeed, these purportedly large conductivities have been used to argue that runaway electron avalanches result in a novel form of electrical breakdown called "runaway breakdown." In this …

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High-Speed X-Ray Images Of Triggered Lightning Dart Leaders, Joseph R. Dwyer, M. M. Schaal, Hamid K. Rassoul, Martin A. Uman, Douglas M. Jordan, Dustin Hill Jan 2011

High-Speed X-Ray Images Of Triggered Lightning Dart Leaders, Joseph R. Dwyer, M. M. Schaal, Hamid K. Rassoul, Martin A. Uman, Douglas M. Jordan, Dustin Hill

Aerospace, Physics, and Space Science Faculty Publications

We present the first high-time resolution two-dimensional images of X-ray emissions from lightning. The images were recorded at a rate of 10 million per second using a new pinhole-type camera, located 44 m from rocket-and-wire- triggered lightning. We report observations of two dart leaders, one in each of two lightning flashes triggered during the summer of 2010 in north-central Florida. In both events, as the dart leader approached the ground, the X-ray source was also seen to descend along the previous lightning channel. For the second event, the X-ray source exhibited a downward speed of 4.5 × 10 7 m/s, …

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Charged Particle Transverse Momentum Spectra In Pp Collisions At √S = 0:9 And 7 Tev, S. Chatrchyan, Marc M. Baarmand, B. Dorney, Samir Guragain, Marcus Hohlmann, Himali Kalakhety, Robert M. Ralich, Igor Vodopiyanov, The Cms Collaboration Jan 2011

Charged Particle Transverse Momentum Spectra In Pp Collisions At √S = 0:9 And 7 Tev, S. Chatrchyan, Marc M. Baarmand, B. Dorney, Samir Guragain, Marcus Hohlmann, Himali Kalakhety, Robert M. Ralich, Igor Vodopiyanov, The Cms Collaboration

Aerospace, Physics, and Space Science Faculty Publications

The charged particle transverse momentum (pT) spectra are presented for pp collisions at √s = 0.9 and 7 TeV. The data samples were collected with the CMS detector at the LHC and correspond to integrated luminosities of 231 μb−1 and 2.96 pb−1, respectively. Calorimeter-based high-transverse-energy triggers are employed to enhance the statistical reach of the high-pT measurements. The results are compared with leading and next-to-leading order QCD and with an empirical scaling of measurements at different collision energies using the scaling variable xT ≡ 2pT / √s over the pT range up to 200 GeV / c. Using a combination …

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Reaction Of Cycloheptatriene Derivatives With 1,3-Diketones In The Presence Of Mn(Oac)_3, Mahi̇r Burak Südemen, Mustafa Zengi̇n, Hayri̇ye Genç, Meti̇n Balci Jan 2011

Reaction Of Cycloheptatriene Derivatives With 1,3-Diketones In The Presence Of Mn(Oac)_3, Mahi̇r Burak Südemen, Mustafa Zengi̇n, Hayri̇ye Genç, Meti̇n Balci

Turkish Journal of Chemistry

The reactions of some 1,3-dicarbonyl compounds with cycloheptatriene derivatives in the presence of Mn(OAc)_3 were examined. Cycloheptatriene forms mainly [2+3] and [6+3] dihydrofuran addition products derived from cycloheptatriene. However, the reaction of acetylacetone with cycloheptatriene substituted with an electron withdrawing group exclusively gave products derived from the norcaradiene structure. The formation mechanism of the products as well as the role of the substituent attached to cycloheptatriene is discussed.

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Synthesis Of Some 2,3,6,8-Tetraarylimidazo[1,2-A]Pyrazine Derivatives By Using Either Reflux Or Microwave Irradiation Method, And Investigation Their Anticancer Activities, İsmai̇l Kayaği̇l, Şeref Demi̇rayak Jan 2011

Synthesis Of Some 2,3,6,8-Tetraarylimidazo[1,2-A]Pyrazine Derivatives By Using Either Reflux Or Microwave Irradiation Method, And Investigation Their Anticancer Activities, İsmai̇l Kayaği̇l, Şeref Demi̇rayak

Turkish Journal of Chemistry

In this study, some 2,3,6,8-tetraarylimidazo[1,2-a]pyrazine derivatives were synthesized by reacting 1-(2-aryl-2-oxoethyl)-2-aryloyl-4,5-diarylimidazoles from 2-aryloyl-4,5-diarylimidazole and 2-bromoacetophenone derivatives with ammonium acetate in acetic acid by using the method that was previously developed and repeatedly tested in our studies. Structural elucidation of the compounds was performed by IR, ^1H-NMR, and MASS spectroscopic data and elemental analysis results. Anticancer activities of selected compounds were evaluated and the noticeable activity values were reported.

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Structural Studies Of Complex Compounds Of 6,6'-Diacetyl-2,2'-Bipyridine Dioxime With Copper(I/Ii), Platinum(Ii), And Palladium(Ii) Metal Ions, Abdurrahman Şengül, Hakan Ağaç, Burak Çoban, Erol Eroğlu Jan 2011

Structural Studies Of Complex Compounds Of 6,6'-Diacetyl-2,2'-Bipyridine Dioxime With Copper(I/Ii), Platinum(Ii), And Palladium(Ii) Metal Ions, Abdurrahman Şengül, Hakan Ağaç, Burak Çoban, Erol Eroğlu

Turkish Journal of Chemistry

The tetradentate ligand 6,6'-diacetyl-2,2'-bipyridine dioxime (L) was obtained in high yield by the condensation reaction of 6,6'-diacetyl-2,2'-bipyridine with hydroxyl amine in alkaline solution. Density functional calculations and 3D modeling of the structure at the B3LYP/6-31G(d) level of theory for L revealed that the energy difference between the global trans conformer (trans-L), which possesses the C_{2h} point group, and the distorted cis conformer (cis-L) was 5.214 kcal/mol. Synthesis and characterization of the metal complexes with Cu(I), Cu(II), Pt(II), and Pd(II) metal ions were reported. L acted as a N_4-donor ligand to coordinate to the metal centers via N atoms of the …

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Effect Of Cmc And Hpc Mixture On The Photocatalytic Activity Of Nd-Tio_2/Sio_2 Film Under Visible Light Irradiation, Parviz Aberoomand, Shahram Moradi, Susan Samadi, Mohammad Saber Tehrani, Mohammad Hadi Givianrad Jan 2011

Effect Of Cmc And Hpc Mixture On The Photocatalytic Activity Of Nd-Tio_2/Sio_2 Film Under Visible Light Irradiation, Parviz Aberoomand, Shahram Moradi, Susan Samadi, Mohammad Saber Tehrani, Mohammad Hadi Givianrad

Turkish Journal of Chemistry

Neodymium-titania/silica films were prepared by the sol-gel method with the addition of various amounts of hydroxy propyl cellulose (HPC) and 5.09 \times 10^{-5} g g^{-1}_{solution} of carboxy methyl cellulose (CMC) in saturated conditions. The porous Nd-TiO_2/SiO_2 was obtained after heat treatment for 2 h at 500 °C, with the surface area up to 276 m^2 g^{-1}, which was measured using the Brunauer, Emmett, and Teller (BET) method. Scanning electron microscopy (SEM) showed that the particle size of Nd-TiO_2/SiO_2 decreased and the microstructure of the film became loose in suitable conditions with the addition of CMC to HPC. Subsequently, the photocatalytic …

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Synthesis And Characterisation Of Tris(2,4-Dinitrophenoxo)Monooxovanadium(V) And Its Complex Salts, Neeraj Sharma, Reena Sharma, Meena Kumari, Subhash Chaudhry Jan 2011

Synthesis And Characterisation Of Tris(2,4-Dinitrophenoxo)Monooxovanadium(V) And Its Complex Salts, Neeraj Sharma, Reena Sharma, Meena Kumari, Subhash Chaudhry

Turkish Journal of Chemistry

The monooxovanadium(V) complex of composition [VO(OC_6H_3(NO_2)_2-2,4)_3] (I) was synthesized by the reaction of VOCl_3 with Me_3SiOC_6H_3(NO_2)_2-2,4 in toluene and characterised by elemental analyses, molar conductance, and IR, ^1H- and ^{13}C-NMR, and mass spectral studies. The reactions of (I) with alkali metal 2,4-dinitrophenoxides [MOC_6H_3(NO_2)_2-2,4] (M = Li, Na, K) yield complex salts of composition M[VO(OC_6H_3(NO_2)_2-2,4]_4 authenticated by physicochemical and IR spectral studies. Thermal behaviour of complexes was studied by TG and DTA techniques. The molecular modelling calculations of the parent complex and its complex salts were performed to visualise the probable geometry around vanadium metal, which, coupled with spectroscopic evidence, suggests …

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