8,017 research outputs found
On the SL(2) period integral
Let E/F be a quadratic extension of number fields. For a cuspidal
representation of SL(2,A_E), we study the non-vanishing of the period
integral on SL(2,F)\SL(2,A_F). We characterise the non-vanishing of the period
integral of in terms of being generic with respect to characters of
E\A_E which are trivial on A_F. We show that the period integral in general is
not a product of local invariant functionals, and find a necessary and
sufficient condition when it is. We exhibit cuspidal representations of
SL(2,A_E) whose period integral vanishes identically while each local
constituent admits an SL(2)-invariant linear functional. Finally, we construct
an automorphic representation on SL(2,A_E) which is abstractly SL(2,A_F)
distinguished but none of the elements in the global L-packet determined by
is distinguished by SL(2,A_F)
A local global question in automorphic forms
In this paper, we consider the \SL(2) analogue of two well-known theorems
about period integrals of automorphic forms on \GL(2): one due to
Harder-Langlands-Rapoport, and the other due to Waldspurger.Comment: 28 page
Valence Fluctuation in CeMo2Si2C
We report on the valence fluctuation of Ce in CeMoSiC as studied
by means of magnetic susceptibility , specific heat , electrical
resistivity and x-ray absorption spectroscopy. Powder x-ray
diffraction revealed that CeMoSiC crystallizes in
CeCrSiC-type layered tetragonal crystal structure (space group
\textit{P4/mmm}). The unit cell volume of CeMoSiC deviates from the
expected lanthanide contraction, indicating non-trivalent state of Ce ions in
this compound. The observed weak temperature dependence of the magnetic
susceptibility and its low value indicate that Ce ions are in valence
fluctuating state. The formal Ce valence in CeMoSiC
= 3.11 as determined from x-ray absorption spectroscopy
measurement is well bellow the value 3.4 in
tetravalent Ce compound CeO. The temperature dependence of specific heat
does not show any anomaly down to 1.8 K which rules out any magnetic ordering
in the system. The Sommerfeld coefficient obtained from the specific heat data
is = 23.4 mJ/mol\,K. The electrical resistivity follows the
behavior in the low temperature range below 35 K confirming a Fermi
liquid behavior. Accordingly both the Kadowaki Wood ratio and
the Sommerfeld Wilson ratio are in the range expected for
Fermi-liquid systems. In order to get some information on the electronic
states, we calculated the band structure within the density functional theory,
eventhough this approach is not able to treat 4f electrons accurately. The
non- electron states crossing the Fermi level have mostly Mo 4d character.
They provide the states with which the 4f sates are strongly hybridized,
leading to the intermediate valent state.Comment: 18 pages, 10 figures Submitted to Journal of Alloys and Compound
PARS: Programs for Analysis and Resizing of Structures, user manual
PARS processors and their use, flutter analysis, sensitivity analysis for stresses, and resizing are presented. Design variable definition and interface with finite element model, static constraints and their derivatives, flutter derivatives, and optimization are discussed
Itinerant and local-moment magnetism in EuCr2As2 single crystals
We report on the crystal structure, physical properties, and electronic
structure calculations for the ternary pnictide compound EuCr2As2. X-ray
diffraction studies confirmed that EuCr2As2 crystalizes in the ThCr2Si2-type
tetragonal structure (space group I4/mmm). The Eu ions are in a stable divalent
state in this compound. Eu moments in EuCr2As2 order magnetically below Tm = 21
K. A sharp increase in the magnetic susceptibility below Tm and the positive
value of the paramagnetic Curie temperature obtained from the Curie-Weiss fit
suggest dominant ferromagnetic interactions. The heat capacity exhibits a sharp
{\lambda}-shape anomaly at Tm, confirming the bulk nature of the magnetic
transition. The extracted magnetic entropy at the magnetic transition
temperature is consistent with the theoretical value Rln(2S+1) for S = 7/2 of
the Eu2+ ion. The temperature dependence of the electrical resistivity
\r{ho}(T) shows metallic behavior along with an anomaly at 21 K. In addition,
we observe a reasonably large negative magneto-resistance (~ -24%) at lower
temperature. Electronic structure calculations for EuCr2As2 reveal a moderately
high density of states of Cr-3d orbitals at the Fermi energy, indicating that
the nonmagnetic state of Cr is unstable against magnetic order. Our density
functional calculations for EuCr2As2 predict a G-type AFM order in the Cr
sublattice. The electronic structure calculations suggest a weak interlayer
coupling of the Eu moments.Comment: 9 pages, 7 figure
The use of remote sensing data for drought assessment and monitoring in southwest Asia
Drought / Monitoring / Indicators / Assessment / Remote sensing / Asia
Distinguished representations for SL(2)
Let E/F be a quadratic extension of p-adic fields. We compute the multiplicity of the space of SL2(F)-invariant linear forms on a representation of SL2(E). This multiplicity varies inside an L-packet similar in spirit to the multiplicity formula for automorphic representations due to Labesse and Langlands
Valence fuctuation and magnetic ordering in EuNi2(P1-xGex)2 single crystals
Unusual phases and phase transitions are seen at the magnetic-nonmagnetic
boundary in Ce, Eu and Yb-based compounds. EuNiP is a very unusual
valence fluctuating Eu system, because at low temperatures the Eu valence stays
close to 2.5 instead of approaching an integer value. Eu valence and thus the
magnetic property in this system can be tuned by Ge substitution in P site as
EuNiGe is known to exhibit antiferromagnetc (AFM) ordering of
divalent Eu moments with = 30 K. We have grown
EuNi(PGe) (0.0 0.5) single crystals and
studied their magnetic, thermodynamic and transport properties. Increasing Ge
doping to 0.4 results in a well-defined AFM ordered state with = 12
K for = 0.5. Moreover, the reduced value of magnetic entropy for = 0.5
at suggests the presence of valance fluctuation/ Kondo effect in this
compound. Interestingly, the specific heat exhibits an enhanced Sommerfeld
coefficient upon Ge doping. Subsequently, electronic structure calculations
lead to a non-integral valence in EuNiP but a stable divalent Eu
state in EuNiGe which is in good agreement with experimental results.Comment: 7 pages, 8 figure
Droplet size distribution in homogeneous isotropic turbulence
We study the physics of droplet breakup in a statistically stationary
homogeneous and isotropic turbulent flow by means of high resolution numerical
investigations based on the multicomponent lattice Boltzmann method. We
verified the validity of the criterion proposed by Hinze (1955) for droplet
breakup and we measured the full probability distribution function (pdf) of
droplets radii at different Reynolds numbers and for different volume fraction.
By means of a Lagrangian tracking we could follow individual droplets along
their trajectories, define a local Weber number based on the velocity gradients
and study its cross-correlation with droplet deformation.Comment: 10 pages, 6 figure
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