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Articles 751 - 780 of 1383

Full-Text Articles in Physical Sciences and Mathematics

Mapping Of The Quasi-Periodic Oscillations At The Flank Magnetopause Into The Ionosphere, E. R. Dougal, K. Nykyri, T. W. Moore Nov 2013

Mapping Of The Quasi-Periodic Oscillations At The Flank Magnetopause Into The Ionosphere, E. R. Dougal, K. Nykyri, T. W. Moore

Publications

We have estimated the ionospheric location, area, and travel time of quasi-periodic oscillations originating from the magnetospheric flanks. This was accomplished by utilizing global and local MHD models and Tsyganenko semi-empirical magnetic field model on multiple published and four new cases believed to be caused by the Kelvin– Helmholtz Instability. Finally, we used auroral, magnetometer, and radar instruments to observe the ionospheric signatures. The ionospheric magnetic latitude determined using global MHD and Tsyganenko models ranged from 58.3–80.2 degrees in the Northern Hemisphere and −59.6 degrees to −83.4 degrees in the Southern Hemisphere. The ionospheric magnetic local time ranged between 5.0–13.8 …

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Molecular Mechanisms Of Disease-Causing Missense Mutations, Shannon Stefl, Hafumi Nishi, Marharyta Petukh, Anna R. Panchenko, Emil Alexov Nov 2013

Molecular Mechanisms Of Disease-Causing Missense Mutations, Shannon Stefl, Hafumi Nishi, Marharyta Petukh, Anna R. Panchenko, Emil Alexov

Publications

Genetic variations resulting in a change of amino acid sequence can have a dramatic effect on stability, hydrogen bond network, conformational dynamics, activity and many other physiologically important properties of proteins. The substitutions of only one residue in a protein sequence, so-called missense mutations, can be related to many pathological conditions, and may influence susceptibility to disease and drug treatment. The plausible effects of missense mutations range from affecting the macromolecular stability to perturbing macromolecular interactions and cellular localization. Here we review the individual cases and genome-wide studies which illustrate the association between missense mutations and diseases. In addition we …

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Preferential Scattering By Interfacial Charged Defects For Enhanced Thermoelectric Performance In Few-Layered N-Type Bi2te3, Pooja Puneet, Ramakrishna Podila, Mehmet Karakaya, Song Zhu, Jian He, Terry M. Tritt, Mildred S. Dresselhaus, Apparao Rao Nov 2013

Preferential Scattering By Interfacial Charged Defects For Enhanced Thermoelectric Performance In Few-Layered N-Type Bi2te3, Pooja Puneet, Ramakrishna Podila, Mehmet Karakaya, Song Zhu, Jian He, Terry M. Tritt, Mildred S. Dresselhaus, Apparao Rao

Publications

Over the past two decades several nano-structuring methods have helped improve the figure of merit (ZT) in the state-of-the art bulk thermoelectric materials. While these methods could enhance the thermoelectric performance of p-type Bi2Te3, it was frustrating to researchers that they proved ineffective for n-type Bi2Te3 due to the inevitable deterioration of its thermoelectric properties in the basal plane. Here, we describe a novel chemical-exfoliation spark-plasma-sintering (CE-SPS) nano-structuring process, which transforms the microstructure of n-type Bi2Te3 in an extraordinary manner without compromising its basal plane …

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High-Resolution Near-Infrared Spectroscopy Of Hd 100546. Ii. Analysis Of Variable Rovibrational Co Emission Lines, Sean D. Brittain, Joan Najita, John S. Carr, Joseph Liskowsky, Matthew R. Troutman, Greg W. Doppmann Nov 2013

High-Resolution Near-Infrared Spectroscopy Of Hd 100546. Ii. Analysis Of Variable Rovibrational Co Emission Lines, Sean D. Brittain, Joan Najita, John S. Carr, Joseph Liskowsky, Matthew R. Troutman, Greg W. Doppmann

Publications

We present observations of rovibrational CO in HD 100546 from four epochs spanning 2003 January through 2010 December. We show that the equivalent widths of the CO lines vary during this time period with the v = 1–0 CO lines brightening more than the UV fluoresced lines from the higher vibrational states.While the spectroastrometric signal of the hot band lines remains constant during this period, the spectroastrometric signal of the v = 1–0 lines varies substantially. At all epochs, the spectroastrometric signals of the UV fluoresced lines are consistent with the signal one would expect from gas in an axisymmetric …

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High-Resolution Near-Infrared Spectroscopy Of Hd 100546. I. Analysis Of Asymmetric Ro-Vibrational Oh Emission Lines, Joseph Liskowsky, Sean D. Brittain, Joan R. Najita, John S. Carr, Greg W. Doppman, Matthew R. Troutman Nov 2013

High-Resolution Near-Infrared Spectroscopy Of Hd 100546. I. Analysis Of Asymmetric Ro-Vibrational Oh Emission Lines, Joseph Liskowsky, Sean D. Brittain, Joan R. Najita, John S. Carr, Greg W. Doppman, Matthew R. Troutman

Publications

We present observations of ro-vibrational OH and CO emission from the Herbig Be star HD 100546. The emission from both molecules arises from the inner region of the disk extending from approximately 13 AU from the central star. The velocity profiles of the OH lines are narrower than the velocity profile of the [O i] λ6300 line, indicating that the OH in the disk is not cospatial with the Oi. This suggests that the inner optically thin region of the disk is largely devoid of molecular gas. Unlike the ro-vibrational CO emission lines, the OH lines are highly asymmetric. We …

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Observed Versus Gcm-Generated Local Tropical Cyclone Frequency: Comparisons Using A Spatial Lattice, Sarah Strazzo, Daniel J. Halperin, James Elsner, Tim Larow, Ming Zhao Nov 2013

Observed Versus Gcm-Generated Local Tropical Cyclone Frequency: Comparisons Using A Spatial Lattice, Sarah Strazzo, Daniel J. Halperin, James Elsner, Tim Larow, Ming Zhao

Publications

Of broad scientific and public interest is the reliability of global climate models (GCMs) to simulate future regional and local tropical cyclone (TC) occurrences. Atmospheric GCMs are now able to generate vortices resembling actual TCs, but questions remain about their fidelity to observed TCs. Here the authors demonstrate a spatial lattice approach for comparing actual with simulated TC occurrences regionally using observed TCs from the International Best Track Archive for Climate Stewardship (IBTrACS) dataset and GCM-generated TCs from the Geophysical Fluid Dynamics Laboratory (GFDL) High Resolution Atmospheric Model (HiRAM) and Florida State University (FSU) Center for Ocean–Atmospheric Prediction Studies (COAPS) …

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Ionospheric Signatures Of Acoustic Waves Generated By Transient Tropospheric Forcing, M. D. Zettergren, J. B. Snively Oct 2013

Ionospheric Signatures Of Acoustic Waves Generated By Transient Tropospheric Forcing, M. D. Zettergren, J. B. Snively

Publications

Acoustic waves generated by tropospheric sources may attain significant amplitudes in the thermosphere and overlying ionosphere. Although they are weak precursors to gravity waves in the mesosphere below, acoustic waves may achieve temperature and vertical wind perturbations on the order of approximately tens of Kelvin and m/s throughout the E and F regions. Their perturbations to total electron content are predicted to be detectable by groundbased radar and GPS receivers; they also drive field-aligned currents that may be detectable in situ via magnetometers. Although transient and short lived, ionospheric signatures of acoustic waves may provide new and quantitative insight into …

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Broadband Monitoring Tracing The Evolution Of The Jet And Disk In The Black Hole Candidate X-Ray Binary Maxi J1659-152, A. J. Horst, P. A. Curran, J. C. A. Miller-Jones, J. D. Linford, J. Gorosabel, D. M. Russell, A. De Ugarte Postigo, A. A. Lundgren, G. B. Taylor, D Maitra, S Guziy, T M. Belloni, C Kouveliotou, P G. Jonker, A Kamble, Z Paragi, J Homan, E Kuulkers, J Granot, D Altamirano, M M. Buxton, A Castro-Tirado, R P. Fender, M A. Garrett, N Gehrels, Dieter H. Hartmann, J A. Kennea, H A. Krimm, V Mangano, E Ramirez-Ruiz, P Romano, R.A.M.J. Wijers, R Wijnands, Y J. Yang Oct 2013

Broadband Monitoring Tracing The Evolution Of The Jet And Disk In The Black Hole Candidate X-Ray Binary Maxi J1659-152, A. J. Horst, P. A. Curran, J. C. A. Miller-Jones, J. D. Linford, J. Gorosabel, D. M. Russell, A. De Ugarte Postigo, A. A. Lundgren, G. B. Taylor, D Maitra, S Guziy, T M. Belloni, C Kouveliotou, P G. Jonker, A Kamble, Z Paragi, J Homan, E Kuulkers, J Granot, D Altamirano, M M. Buxton, A Castro-Tirado, R P. Fender, M A. Garrett, N Gehrels, Dieter H. Hartmann, J A. Kennea, H A. Krimm, V Mangano, E Ramirez-Ruiz, P Romano, R.A.M.J. Wijers, R Wijnands, Y J. Yang

Publications

MAXI J1659−152 was discovered on 2010 September 25 as a new X-ray transient, initially identified as a gamma-ray burst, but was later shown to be a new X-ray binary with a blackhole as the most likely compact object. Dips in the X-ray light curves have revealed that MAXI J1659−152 is the shortest period black hole candidate identified to date. Here we present the results of a large observing campaign at radio, submillimetre, near-infrared (nIR), optical and ultraviolet (UV) wavelengths. We have combined this very rich data set with the available X-ray observations to compile a broad-band picture of the evolution …

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A Meteorological Analysis Of Important Contributions To The 1999-2005 Canadian Prairie Drought, Lisa M. Hryciw, Eyad H. Atallah, Shawn M. Milrad, John R. Gyakum Oct 2013

A Meteorological Analysis Of Important Contributions To The 1999-2005 Canadian Prairie Drought, Lisa M. Hryciw, Eyad H. Atallah, Shawn M. Milrad, John R. Gyakum

Publications

Drought is a complex natural hazard that is endemic to the Canadian prairies. The 1999–2005 Canadian prairie drought, which had great socioeconomic impacts, was meteorologically unique in that it did not conform to the traditional persistent positive Pacific–North American (PNA) pattern and west coast ridging paradigm normally associated with prairie drought. The purpose of this study is to diagnose the unique synoptic-scale mechanisms responsible for modulating subsidence during this drought. Using 30-day running means of the percent of normal precipitation from station data, key severe dry periods during 1999–2005 are identified. Analysis of the mean fields from reanalysis data shows …

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A Bayesian Approach To Deriving Ages Of Individual Field White Dwarfs, Erin M. O'Malley, Ted Von Hippel, David A. Van Dyk Sep 2013

A Bayesian Approach To Deriving Ages Of Individual Field White Dwarfs, Erin M. O'Malley, Ted Von Hippel, David A. Van Dyk

Publications

We apply a self-consistent and robust Bayesian statistical approach to determine the ages, distances, and zero-age main sequence (ZAMS) masses of 28 field DA white dwarfs (WDs) with ages of approximately 4–8 Gyr. Our technique requires only quality optical and near-infrared photometry to derive ages with <15% uncertainties, generally with little sensitivity to our choice of modern initial–final mass relation. We find that age, distance, and ZAMS mass are correlated in a manner that is too complex to be captured by traditional error propagation techniques. We further find that the posterior distributions of age are often asymmetric, indicating that the …

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Near-Infrared Spectroscopic Study Of V1647 Ori, Sean D. Brittain, T W. Rettig, Theodore Simon, Erika L. Gibb, Joseph Liskowsky Sep 2013

Near-Infrared Spectroscopic Study Of V1647 Ori, Sean D. Brittain, T W. Rettig, Theodore Simon, Erika L. Gibb, Joseph Liskowsky

Publications

We present new high-resolution infrared echelle spectra of V1647 Ori, the young star that illuminates McNeil's nebula. From the start, V1647 Ori has been an enigmatic source that has defied classification, in some ways resembling eruptive stars of the FUor class and in other respects the EXor variables. V1647 Ori underwent an outburst in 2003 before fading back to its pre-outburst brightness in 2006. In 2008, it underwent a new outburst. In this paper we present high-resolution K-band and M-band spectra from the W. M. Keck Observatory that were acquired during the 2008 outburst. We compare the spectra to spectra …

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Numerical And Statistical Evidence For Long-Range Ducted Gravity Wave Propagation Over Halley, Antarctica, J. B. Snively, K. Nielsen, M. P. Hickey, C. J. Heale, M. J. Taylor, T. Moffat-Griffin Sep 2013

Numerical And Statistical Evidence For Long-Range Ducted Gravity Wave Propagation Over Halley, Antarctica, J. B. Snively, K. Nielsen, M. P. Hickey, C. J. Heale, M. J. Taylor, T. Moffat-Griffin

Publications

Abundant short-period, small-scale gravity waves have been identified in the mesosphere and lower thermosphere over Halley, Antarctica, via ground-based airglow image data. Although many are observed as freely propagating at the heights of the airglow layers, new results under modeled conditions reveal that a significant fraction of these waves may be subject to reflections at altitudes above and below.The waves may at times be trapped within broad thermal ducts, spanning from the tropopause or stratopause to the base of the thermosphere (~140 km), which may facilitate long-range propagation (~1000s of km) under favorable wind conditions.

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Mesospheric Hydroxyl Airglow Signatures Of Acoustic And Gravity Waves Generated By Transient Tropospheric Forcing, J. B. Snively Sep 2013

Mesospheric Hydroxyl Airglow Signatures Of Acoustic And Gravity Waves Generated By Transient Tropospheric Forcing, J. B. Snively

Publications

"Numerical model results demonstrate that acoustic waves generated by tropospheric sources may produce cylindrical “concentric ring” signatures in the mesospheric hydroxyl airglow layer. They may arrive as precursors to upward propagating gravity waves, generated simultaneously by the same sources, and produce strong temperature perturbations in the thermosphere above. Transient and short-lived, the acoustic wave airglow intensity and temperature signatures are predicted to be detectable by ground-based airglow imaging systems and may provide new insight into the forcing of the upper atmosphere from below."--From publisher's website.

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Nitrogen Abundances And The Distance Moduli Of The Pleiades And Hyades, Blake Miller, Jeremy R. King, Yu Chen, Ann Merchant Boesgaard Sep 2013

Nitrogen Abundances And The Distance Moduli Of The Pleiades And Hyades, Blake Miller, Jeremy R. King, Yu Chen, Ann Merchant Boesgaard

Publications

Recent reanalyses of HIPPARCOS parallax data confirm a previously noted discrepancy with the Pleiades distance modulus estimated from main-sequence fitting in the color-magnitude diagram. One proposed explanation of this distance modulus discrepancy is a Pleiades He abundance that is significantly larger than the Hyades value. We suggest that, based on our theoretical and observational understanding of Galactic chemical evolution, nitrogen abundances may serve as a proxy for helium abundances of disk stars. Utilizing high-resolution near-UV Keck/HIRES spectroscopy, we determine N abundances in the Pleiades and Hyades dwarfs from NH features in the λ3330 region. While our Hyades N abundances show …

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Synoptic-Scale Precursors, Characteristics And Typing Of Nocturnal Mesoscale Convective Complexes In The Great Plains, Shawn M. Milrad, Cailee M. Kelly Sep 2013

Synoptic-Scale Precursors, Characteristics And Typing Of Nocturnal Mesoscale Convective Complexes In The Great Plains, Shawn M. Milrad, Cailee M. Kelly

Publications

Mesoscale convective complexes (MCCs) occur frequently during the warm season in the central U.S. and can produce flooding rains, hail and tornadoes. Previous work has found that the synoptic-scale environment can greatly affect, and be affected by, the development and maintenance of MCCs. Ninetytwo MCC cases from 2006–2011 are manually identified using infrared satellite imagery and partitioned into three types (upstream trough, zonal and ridge) using a unique manual synoptic typing based on 500- hPa height patterns. Upstream trough cases feature an amplified longwave 500-hPa trough upstream of the MCC genesis region (GR), while the 500-hPa flow is relatively flat …

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Integrable Dissipative Nonlinear Second Order Differential Equations Via Factorizations And Abel Equations, S.C. Mancas, Haret C. Rosu Sep 2013

Integrable Dissipative Nonlinear Second Order Differential Equations Via Factorizations And Abel Equations, S.C. Mancas, Haret C. Rosu

Publications

We emphasize two connections, one well known and another less known, between the dissipative nonlinear second order differential equations and the Abel equations which in its first kind form have only cubic and quadratic terms. Then, employing an old integrability criterion due to Chiellini, we introduce the corresponding integrable dissipative equations. For illustration, we present the cases of some integrable dissipative Fisher, nonlinear pendulum, and Burgers-Huxley type equations which are obtained in this way and can be of interest in applications. We also show how to obtain Abel solutions directly from the factorization of second-order nonlinear equations.

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Gas Lines From The 5-Myr Old Optically Thin Disk Around Hd141569a, W F. Thi, C Pinte, E Pantin, J C. Augereau, G Meeus, F Menard, C Martin-Zaidi, P Woitke, P Riviere-Marichalar, I Kamp, A Carmona, G Sandell, C Eiroa, W Dent, B Montesinos, G Aresu, R Meijerink, M Spaans, G White, D Ardila, J Lebreton, I Mendigutia, Sean D. Brittain Sep 2013

Gas Lines From The 5-Myr Old Optically Thin Disk Around Hd141569a, W F. Thi, C Pinte, E Pantin, J C. Augereau, G Meeus, F Menard, C Martin-Zaidi, P Woitke, P Riviere-Marichalar, I Kamp, A Carmona, G Sandell, C Eiroa, W Dent, B Montesinos, G Aresu, R Meijerink, M Spaans, G White, D Ardila, J Lebreton, I Mendigutia, Sean D. Brittain

Publications

At the distance of 99-116 pc, HD141569A is one of the nearest HerbigAe stars that is surrounded by a tenuous disk, probably in transition between a massive primordial disk and a debris disk. We observed the fine-structure lines of OI at 63 and 145 micron and the CII line at 157 micron with the PACS instrument onboard the Herschel Space Telescope as part of the open-time large programme GASPS. We complemented the atomic line observations with archival Spitzer spectroscopic and photometric continuum data, a ground-based VLT-VISIR image at 8.6 micron, and 12CO fundamental ro-vibrational and pure rotational J=3-2 observations. We …

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Moving Objects In The Hubble Ultra Deep Field, Mukremin Kilic, Alexandros Gianninas, Ted Von Hippel Sep 2013

Moving Objects In The Hubble Ultra Deep Field, Mukremin Kilic, Alexandros Gianninas, Ted Von Hippel

Publications

We identify proper motion objects in the Hubble Ultra Deep Field (UDF) using the optical data from the original UDF program in 2004 and the near-infrared data from the 128 orbit UDF 2012 campaign. There are 12 sources brighter than I = 27 mag that display >3σ significant proper motions. We do not find any proper motion objects fainter than this magnitude limit. Combining optical and near-infrared photometry, we model the spectral energy distribution of each point-source using stellar templates and state-of-the-art white dwarf models. For I ≤ 27 mag, we identify 23 stars with K0-M6 spectral types and two …

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Book Review: Heart Of Darkness: Unraveling The Mysteries Of The Invisible Universe, T. D. Oswalt Sep 2013

Book Review: Heart Of Darkness: Unraveling The Mysteries Of The Invisible Universe, T. D. Oswalt

Publications

This document is Dr. Oswalt’s review of Heart of Darkness : Unraveling the Mysteries of the Invisible Universe by Jeremiah P. Ostriker and Simon Mitton Princeton, 2013 299p, 9780691134307 $27.95, 9781400844647 $27.95

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First Magnetic Seismology Of The Cme Reconnection Outflow Layer In The Low Corona With 2.5-D Mhd Simulations Of The Kelvin-Helmholtz Instability, Katariina Nykyri, Claire Foullon Aug 2013

First Magnetic Seismology Of The Cme Reconnection Outflow Layer In The Low Corona With 2.5-D Mhd Simulations Of The Kelvin-Helmholtz Instability, Katariina Nykyri, Claire Foullon

Publications

For conditions observed in the low corona, we perform 2.5-D magnetohydrodynamic (MHD) simulations of the Kelvin-Helmholtz instability (KHI) at the surface of a coronal mass ejection (CME). We match the observed time development of the KHI with simulated growth from 110 MHD experiments representing a parametric range of realistic magnetic field strengths and orientations and two key values of the velocity shear, ΔV, inferred from observations. The results are field strengths Be≈ 8–9 G and Bs≈ 10–11 G in the CME reconnection outflow layer and the surrounding sheath, respectively, for ΔV≈770kms−1; for nearly perpendicular orientation (1° tilt) of Bs with …

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Impact Of Mhd Shock Physics On Magnetosheath Symmetry And Kelvin-Helmholtz Instability, K. Nykyri Aug 2013

Impact Of Mhd Shock Physics On Magnetosheath Symmetry And Kelvin-Helmholtz Instability, K. Nykyri

Publications

We have performed 13 three-dimensional global magnetohydrodynamic (MHD) simulations of the magnetosheath plasma and magnetic field properties for Parker spiral (PS) and ortho-Parker spiral interplanetary magnetic field (IMF) orientations corresponding to a wide range of solar wind plasma conditions. To study the growth of the Kelvin-Helmholtz instability on the dawn and dusk flank magnetopause, we have performed 26 local two-dimensional MHD simulations, with the initial conditions taken from global simulations on both sides of the velocity shear layer at the dawn-dusk terminator. These simulations indicate that while the MHD physics of the fast shocks does not directly lead to strong …

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Sensitivity Of Limiting Hurricane Intensity To Sst In The Atlantic From Observations And Gcms, James Elsner, Sarah Strazzo, Thomas H. Jagger, Timothy Larow, Ming Zhao Aug 2013

Sensitivity Of Limiting Hurricane Intensity To Sst In The Atlantic From Observations And Gcms, James Elsner, Sarah Strazzo, Thomas H. Jagger, Timothy Larow, Ming Zhao

Publications

No abstract provided.

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Biofuel From Microalgae – A Review On The Current Status And Future Trends, Rajee Olaganathan, May Zaw Htet, Lim Yan Ling, Sek Hui Yun Aug 2013

Biofuel From Microalgae – A Review On The Current Status And Future Trends, Rajee Olaganathan, May Zaw Htet, Lim Yan Ling, Sek Hui Yun

Publications

The constant reliance on fossil fuel energy resources is unsustainable, due to both depleting world reserves and increasing green house gas emissions associated with their use and thus there are dynamic research at the global level envisioned at developing alternative renewable and potentially carbon neutral solid, liquid and gaseous biofuels as alternative energy resources. The contemporary knowledge and technology predictions have proved that among the third generation biofuels especially those derived from microalgae are considered the best reasonable alternative energy resource compared to undeniable drawbacks of first and second generation biofuels. Moreover, its efficiency to sequester carbon from the atmosphere …

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The Statistical Mapping Of Magnetosheath Plasma Properties Based On Themis Measurements In The Magnetosheath Interplanetary Medium Reference Frame, A. P. Dimmock, K. Nykyri Aug 2013

The Statistical Mapping Of Magnetosheath Plasma Properties Based On Themis Measurements In The Magnetosheath Interplanetary Medium Reference Frame, A. P. Dimmock, K. Nykyri

Publications

The magnetosheath operates as a natural filter between the solar wind and the magnetospheric plasma. As a result of this, the magnetosheath plays a crucial role in the plasma momentum and energy transport from the interplanetary medium into the magnetosphere. Statistical studies of the magnetosheath are difficult due to the dynamic nature of the terrestrial bow shock and the magnetopause. As a result of this, the spatial and temporal dependence of magnetosheath plasma properties under varying solar wind conditions is still not completely understood. We present a study of magnetosheath plasma properties using 5 years of THEMIS and OMNI data …

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Frequency, Intensity, And Sensitivity To Sea Surface Temperature Of North Atlantic Tropical Cyclones In Best-Track And Simulated Data, Sarah Strazzo, James B. Elsner, Jill C. Trepanier, Kerry A. Emanuel Aug 2013

Frequency, Intensity, And Sensitivity To Sea Surface Temperature Of North Atlantic Tropical Cyclones In Best-Track And Simulated Data, Sarah Strazzo, James B. Elsner, Jill C. Trepanier, Kerry A. Emanuel

Publications

Synthetic hurricane track data generated from a downscaling approach are compared to best-track (observed) data to analyze differences in regional frequency, intensity, and sensitivity of limiting intensity to sea surface temperature (SST). Overall, the spatial distributions of observed and simulated hurricane counts match well, although there are relatively fewer synthetic storms in the eastern quarter of the basin. Additionally, regions of intense synthetic hurricanes tend to coincide with regions of intense observed hurricanes. The sensitivity of limiting hurricane intensity to SST computed from synthetic data is slightly lower than sensitivity computed from observed data (5.561.31 m s21 (standard error, SE) …

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Accretion Variability Of Herbig Ae/Be Stars Observed By X-Shooter Hd 31648 And Hd 163296, I Mendigutia, Sean D. Brittain, C Eiroa, G Meeus, B Montesinos, A Mora, J Muzerolle, R D. Oudmaijer, E Rigliaco Aug 2013

Accretion Variability Of Herbig Ae/Be Stars Observed By X-Shooter Hd 31648 And Hd 163296, I Mendigutia, Sean D. Brittain, C Eiroa, G Meeus, B Montesinos, A Mora, J Muzerolle, R D. Oudmaijer, E Rigliaco

Publications

This work presents X-Shooter/Very Large Telescope spectra of the prototypical, isolated Herbig Ae stars HD 31648 (MWC 480) and HD 163296 over five epochs separated by timescales ranging from days to months. Each spectrum spans over a wide wavelength range covering from 310 to 2475 nm. We have monitored the continuum excess in the Balmer region of the spectra and the luminosity of 12 ultraviolet, optical, and near-infrared spectral lines that are commonly used as accretion tracers for T Tauri stars. The observed strengths of the Balmer excesses have been reproduced from a magnetospheric accretion shock model, providing a mean …

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Field Localization And Mass Generation In An Alternative 5-Dimensional Brane Model, Preston Jones, Doug Singleton, Gerardo Muñoz, Triyanta Aug 2013

Field Localization And Mass Generation In An Alternative 5-Dimensional Brane Model, Preston Jones, Doug Singleton, Gerardo Muñoz, Triyanta

Publications

This proceedings is from a talk given at the APS DPF 2013 on a 5- dimensional brane world model. This alternative brane world model is formally related but physically distinct from the Randall-Sundrum brane world model. The spin dependent localization of 5D fields for the alternative model are different and in some ways superior to the RandallSundrum. The alternative model also exhibits a cutoff in the localization of massive scalar fields not seen in the Randall-Sundrum model. This revision includes a correction to the integrand for the scalar field action appearing in the principle reference [1].

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Mechanisms Of Field-Aligned Current Formation In Magnetic Reconnection, Xuanye Ma, Antonius Otto Aug 2013

Mechanisms Of Field-Aligned Current Formation In Magnetic Reconnection, Xuanye Ma, Antonius Otto

Publications

Satellite observations provide strong evidence for the generation of significant field-aligned currents (FACs) during magnetic reconnection. Reconnection of antiparallel magnetic field does not generate FACs in magnetohydrodynamics (MHD) due to coplanarity in MHD shocks. However, a guide magnetic field and a sheared velocity component are almost always present at the magnetopause and their absence is a singular case. It is illustrated that the presence of these noncoplanar fields requires FACs. Contrary to intuition, such currents are generated more efficiently for a small guide field and are more likely to be a result of the redistribution of already present FACs for …

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Optical And Thermal Properties Of Spinel With Revised (Increased) Absorption At 4 To 5 Μm Wavelengths And Comparison With Sapphire, Daniel C. Harris, Giorgio Turri Aug 2013

Optical And Thermal Properties Of Spinel With Revised (Increased) Absorption At 4 To 5 Μm Wavelengths And Comparison With Sapphire, Daniel C. Harris, Giorgio Turri

Publications

Infrared absorption of high-quality, commercial, polycrystalline MgAl2O4 spinel is ∼40% greater in the range of 3.8 to 5.0 μm than the value predicted by the computer code OPTIMATR®, which has been used for window and dome design for more than 20 years. As a result, spinel and a-plane sapphire windows designed to support the same external pressure with the same probability of survival have approximately the same infrared absorptance in the range 3.8 to 5.0 μm. c-Plane sapphire has greater absorptance than spinel in the range 3.8 to 5.0 μm. Spinel has two weak absorption bands near 1.8 and 3.0 …

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Weierstrass Traveling Wave Solutions For Dissipative Benjamin, Bona, And Mahoney (Bbm) Equation, S.C. Mancas, Greg Spradlin, Harihar Khanal Aug 2013

Weierstrass Traveling Wave Solutions For Dissipative Benjamin, Bona, And Mahoney (Bbm) Equation, S.C. Mancas, Greg Spradlin, Harihar Khanal

Publications

In this paper the effect of a small dissipation on waves is included to find exact solutions to the modified Benjamin, Bona, and Mahony (BBM) equation by viscosity. Using Lyapunov functions and dynamical systems theory, we prove that when viscosity is added to the BBM equation, in certain regions there still exist bounded traveling wave solutions in the form of solitary waves, periodic, and elliptic functions. By using the canonical form of Abel equation, the polynomial Appell invariant makes the equation integrable in terms of Weierstrass ℘ functions. We will use a general formalism based on Ince's transformation to write …

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