737 research outputs found
Compactness and existence results in weighted Sobolev spaces of radial functions. Part II: Existence
We prove existence and multiplicity results for finite energy solutions to
the nonlinear elliptic equation where is a radial domain (bounded or
unbounded) and satisfies on if and as
if is unbounded. The potential may be vanishing or unbounded at
zero or at infinity and the nonlinearity may be superlinear or sublinear.
If is sublinear, the case with is also considered.Comment: 29 pages, 8 figure
Gravitational dipole radiations from binary systems
We investigate the possibility of generating sizeable dipole radiations in
relativistic theories of gravity. Optimal parameters to observe their effects
through the orbital period decay of binary star systems are discussed.
Constraints on gravitational couplings beyond general relativity are derived.Comment: One comment added, accepted for publication in Phys. Rev.
Regulating C<sub>2</sub>H<sub>2</sub>/CO<sub>2</sub> adsorption selectivity by electronic-state manipulation of iron in metal-organic frameworks
The separation of C2H2 from C2H2/CO2 mixture is of great importance, yet highly challenging in the petrochemical industry due to their similar physicochemical properties. While open-metal sites (OMSs) in metal-organic frameworks (MOFs) are known to possess high affinity toward C2H2, its selective adsorption performance regulated by the electronic state of the same OMSs remains unexplored. Here, we report a metal electronic-state manipulation approach to construct a pair of isostructural Fe-MOFs, namely LIFM-26(Fe[II]/Fe[III]) and LIFM-27(Fe[III]) with different Fe[II] or Fe[III] oxidation states on the Fe centers, which display mixed-valent Fe[II]/Fe[III] centers in the former and sole Fe[III] centers in the latter. Remarkably, LIFM-26(Fe[II]/Fe[III]) shows significantly enhanced C2H2 uptake capacity than LIFM-27(Fe[III]), attested by adsorption isotherms and IAST calculations, as well as simulated and experimental breakthrough experiments. Furthermore, in situ infrared (IR) and molecular calculations unveil that the presence of Fe[II] in LIFM-26(Fe[II]/Fe[III]) results in stronger Fe[II]âC2H2 interactions than Fe[III]âC2H2, which plays a key role in the C2H2/CO2 separation
Iron pnictides: Single crystal growth and effect of doping on structural, transport and magnetic properties
We demonstrate the preparation of large, free standing iron pnictide single
crystals with a size up to 20 x 10 x 1 mm3 using solvents in zirconia crucibles
under argon atmosphere. Transport and magnetic properties are investigated to
study the effect of potassium doping on the structural and superconducting
property of the compounds. The spin density wave (SDW) anomaly at Ts ~138 K in
BaFe2As2 single crystals from self-flux shifts to Ts ~85 K due to Sn solvent
growth. We show direct evidence for an incorporation of Sn on the Fe site. The
electrical resistivity data show a sharp superconducting transition temperature
Tc~38.5 K for the single crystal of Ba0.68K0.32Fe2As2. A nearly 100% shielding
fraction and bulk nature of the superconductivity for the single crystal were
confirmed by magnetic susceptibility data. A sharp transition Tc~25 K occurred
for the single crystal of Sr0.85K0.15Fe2As2. There is direct evidence for a
coexistence of the SDW and superconductivity in the low doping regime of
Sr1-xKxFe2As2 single crystals. Structural implications of the doping effects as
well as the coexistence of the two order parameters are discussed.Comment: 22 pages, 9 figure
On the structure and evolution of a polar crown prominence/filament system
Polar crown prominences are made of chromospheric plasma partially circling
the Suns poles between 60 and 70 degree latitude. We aim to diagnose the 3D
dynamics of a polar crown prominence using high cadence EUV images from the
Solar Dynamics Observatory (SDO)/AIA at 304 and 171A and the Ahead spacecraft
of the Solar Terrestrial Relations Observatory (STEREO-A)/EUVI at 195A. Using
time series across specific structures we compare flows across the disk in 195A
with the prominence dynamics seen on the limb. The densest prominence material
forms vertical columns which are separated by many tens of Mm and connected by
dynamic bridges of plasma that are clearly visible in 304/171A two-color
images. We also observe intermittent but repetitious flows with velocity 15
km/s in the prominence that appear to be associated with EUV bright points on
the solar disk. The boundary between the prominence and the overlying cavity
appears as a sharp edge. We discuss the structure of the coronal cavity seen
both above and around the prominence. SDO/HMI and GONG magnetograms are used to
infer the underlying magnetic topology. The evolution and structure of the
prominence with respect to the magnetic field seems to agree with the filament
linkage model.Comment: 24 pages, 14 figures, Accepted for publication in Solar Physics
Journal, Movies can be found at http://www2.mps.mpg.de/data/outgoing/panesar
Measurement of the Charged Multiplicities in b, c and Light Quark Events from Z0 Decays
Average charged multiplicities have been measured separately in , and
light quark () events from decays measured in the SLD experiment.
Impact parameters of charged tracks were used to select enriched samples of
and light quark events, and reconstructed charmed mesons were used to select
quark events. We measured the charged multiplicities:
,
, from
which we derived the differences between the total average charged
multiplicities of or quark events and light quark events: and . We compared
these measurements with those at lower center-of-mass energies and with
perturbative QCD predictions. These combined results are in agreement with the
QCD expectations and disfavor the hypothesis of flavor-independent
fragmentation.Comment: 19 pages LaTex, 4 EPS figures, to appear in Physics Letters
Physics of Solar Prominences: II - Magnetic Structure and Dynamics
Observations and models of solar prominences are reviewed. We focus on
non-eruptive prominences, and describe recent progress in four areas of
prominence research: (1) magnetic structure deduced from observations and
models, (2) the dynamics of prominence plasmas (formation and flows), (3)
Magneto-hydrodynamic (MHD) waves in prominences and (4) the formation and
large-scale patterns of the filament channels in which prominences are located.
Finally, several outstanding issues in prominence research are discussed, along
with observations and models required to resolve them.Comment: 75 pages, 31 pictures, review pape
Performance and operational effectiveness of evacuated flat plate solar collectors compared with conventional thermal, PVT and PV panels
The concept of an evacuated flat plate (EFP) collector was proposed over 40 years ago but, despite its professed advantages, very few manufacturers have developed commercial versions. This situation suggests both technical difficulties in manufacturing a competitively-priced sealed for life panel and a lack of awareness of the bene fits of such panels. This paper demonstrates an evacuated flat plate simulation that closely models experimental efficiency measurements. Having established the validity of the model, it compares published data for a commercial EFP collector with predictions for an optimal design to investigate whether any further efficiency improvement might be possible. The optimised design is then evaluated against alternative solar energy devices by modelling a number of possible applications. These comparisons should inform choices about solar options for delivering heat: EFP collectors are well-suited to some of these applications. Evacuated flat plate collectors are a possible alternative to concentrating collectors for Organic Rankine Cycle power generation. The annual output for all the modelled collectors was found to be a quadratic function of delivery temperature: this enabled a novel optimisation of ORC source temperature. Predictions for concentrating and non-concentrating ORC plant are compared with a PV/thermal alternative. The ORC output is significantly less than a PV panel would achieve; applications needing both heat and power are better served by PVT panels. This is an original and novel result
Time-integrated luminosity recorded by the BABAR detector at the PEP-II e+e- collider
This article is the Preprint version of the final published artcile which can be accessed at the link below.We describe a measurement of the time-integrated luminosity of the data collected by the BABAR experiment at the PEP-II asymmetric-energy e+e- collider at the Ď(4S), Ď(3S), and Ď(2S) resonances and in a continuum region below each resonance. We measure the time-integrated luminosity by counting e+e-âe+e- and (for the Ď(4S) only) e+e-âÎź+Îź- candidate events, allowing additional photons in the final state. We use data-corrected simulation to determine the cross-sections and reconstruction efficiencies for these processes, as well as the major backgrounds. Due to the large cross-sections of e+e-âe+e- and e+e-âÎź+Îź-, the statistical uncertainties of the measurement are substantially smaller than the systematic uncertainties. The dominant systematic uncertainties are due to observed differences between data and simulation, as well as uncertainties on the cross-sections. For data collected on the Ď(3S) and Ď(2S) resonances, an additional uncertainty arises due to Ďâe+e-X background. For data collected off the Ď resonances, we estimate an additional uncertainty due to time dependent efficiency variations, which can affect the short off-resonance runs. The relative uncertainties on the luminosities of the on-resonance (off-resonance) samples are 0.43% (0.43%) for the Ď(4S), 0.58% (0.72%) for the Ď(3S), and 0.68% (0.88%) for the Ď(2S).This work is supported by the US Department of Energy and National Science Foundation, the Natural Sciences and Engineering Research Council (Canada), the Commissariat Ă lâEnergie Atomique and Institut National de Physique NuclĂŠaire et de Physiquedes Particules (France), the Bundesministerium fĂźr Bildung und Forschung and Deutsche Forschungsgemeinschaft (Germany), the Istituto Nazionale di Fisica Nucleare (Italy), the Foundation for Fundamental Research on Matter (The Netherlands), the Research Council of Norway, the Ministry of Education and Science of the Russian Federation, Ministerio de Ciencia e InnovaciĂłn (Spain), and the Science and Technology Facilities Council (United Kingdom). Individuals have received support from the Marie-Curie IEF program (European Union) and the A.P. Sloan Foundation (USA)
Search for direct production of charginos and neutralinos in events with three leptons and missing transverse momentum in âs = 7 TeV pp collisions with the ATLAS detector
A search for the direct production of charginos and neutralinos in final states with three electrons or muons and missing transverse momentum is presented. The analysis is based on 4.7 fbâ1 of protonâproton collision data delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with Standard Model expectations in three signal regions that are either depleted or enriched in Z-boson decays. Upper limits at 95% confidence level are set in R-parity conserving phenomenological minimal supersymmetric models and in simplified models, significantly extending previous results
- âŚ