339 research outputs found
The Structure of Martian Magnetosphere at the Dayside Terminator Region as Observed on MAVEN Spacecraft
We analyzed 44 passes of the MAVEN spacecraft through the magnetosphere,
arranged by the angle between electric field vector and the projection of
spacecraft position radius vector in the YZ plane in MSE coordinate system
( E ). All passes were divided into 3 angular sectors near 0{\deg},
90{\deg} and 180{\deg} E angles in order to estimate the role of IMF
direction in plasma and magnetic properties of dayside Martian magnetosphere.
The time interval chosen was from January 17 through February 4, 2016 when
MAVEN was crossing the dayside magnetosphere at SZA ~ 70{\deg}. Magnetosphere
as the region with prevailing energetic planetary ions is always found between
the magnetosheath and the ionosphere. 3 angular sectors of dayside interaction
region in MSE coordinate system with different orientation of the solar wind
electric field vector E = -1/c V x B showed that for each sector one can find
specific profiles of the magnetosheath, the magnetic barrier and the
magnetosphere. Plume ions originate in the northern MSE sector where motion
electric field is directed from the planet. This electric field ejects
magnetospheric ions leading to dilution of magnetospheric heavy ions
population, and this effect is seen in some magnetospheric profiles. Magnetic
barrier forms in front of the magnetosphere, and relative magnetic field
magnitudes in these two domains vary. The average height of the boundary with
ionosphere is ~530 km and the average height of the magnetopause is ~730 km. We
discuss the implications of the observed magnetosphere structure to the
planetary ions loss mechanism.Comment: 24 pages, 13 figure
Observation of a Chiral State in a Microwave Cavity
A microwave experiment has been realized to measure the phase difference of
the oscillating electric field at two points inside the cavity. The technique
has been applied to a dissipative resonator which exhibits a singularity --
called exceptional point -- in its eigenvalue and eigenvector spectrum. At the
singularity, two modes coalesce with a phase difference of We
conclude that the state excited at the singularity has a definitiv chirality.Comment: RevTex 4, 5 figure
Is it possible to estimate the Higgs Mass from the CMB Power Spectrum?
General Relativity and Standard Model are considered as a theory of dynamical
scale symmetry with definite initial data compatible with the accepted Higgs
mechanism. In this theory the Early Universe behaves like a factory of
electroweak bosons and Higgs scalars, and it gives a possibility to identify
three peaks in the Cosmic Microwave Background power spectrum with the
contributions of photonic decays and annihilation processes of primordial
Higgs, W, and Z bosons in agreement with the QED coupling constant, Weinberg's
angle, and Higgs' particle mass of about 118 GeV.Comment: version to appear in Yadernaya Fizik
Enabling magnetic resonance imaging of hollow-core microstructured optical fibers via nanocomposite coating
Optical fibers are widely used in bioimaging systems as flexible endoscopes
capable of low-invasive penetration inside hollow tissue cavities. Here, we
report on the technique which allows magnetic resonance imaging (MRI) of
hollow-core microstructured fibers (HC-MFs), paving the way for combing MRI and
optical bioimaging. Our approach is based on Layer-by-Layer assembly of
oppositely charged polyelectrolytes and magnetite nanoparticles on the inner
core surface of HC-MFs. Incorporation of magnetite nanoparticles into
polyelectrolyte layers renders HC-MFs visible for MRI and induces the red-shift
in their transmission spectra. Specifically, the transmission shifts up to 60
nm have been revealed for the several-layers composite coating along with the
high-quality contrast of HC-MFs in MRI scans. Our results shed light on
marrying fiber-based endoscopy with MRI that opens novel possibilities for
minimally invasive clinical diagnostics and surgical procedures in vivo.Comment: 11 pages, 6 figure
アルメニアおよびグルジアにおける果樹遺伝資源の探索収集
Caucasia is considered to be a gene center for cultivated fruit trees (Vavilov, 1980) and many kind of fruit tree genetic resources are reported to grow in North Caucasia of Russia (Sanada, 1996). To investigate genetic diversity of fruit trees and collect useful breeding materials, a collaborative exploration mission for fruit tree genetic resources was undertaken in Armenia and Georgia from July 12 to August 17 in 1998. The fruit collecting mission was organized by the N. I. Vavilov All-Russia Institute of Plant Industry (VIR), Research Institute of Viticulture, Wine-making and Horticulture of Armenia and Skra Experiment Station, Gori region. The schedule, route and equipment for this exploration were arranged mainly by VIR. The team traveled on roads around the Aragats mountains from Jul. 15 to Jul. 18. We could collect fruit genetic resources such as Malus, Pyrus and Prunus species in mountainous areas of Hrazdan and Achundov near the road. Then the team traveled in the south-east region of Armenia from Jul. 19 to Jul. 25. The south region of Yerevan was very hot and dry, we could not find any fruit tree genetic resources except for wild Prunus amygdalus on mountain slopes. In Goris, wild species of Malus, Pyrus, and Prunus amygdalus were found on mountain slopes. The VIR researchers traveled to Karabakh region which was surrounded by the regions of Azerbaydzhan. They collected many kinds of wild fruit tree genetic resources such as Malus, Pyrus, Prunus, Mespilus, Corylus and Cornus. These collected materials were provided to the Japanese side. After the collection in Armenia, the team transferred to Tbilisi in Georgia. The team traveled in western regions of Georgia along the road from Jul. 27 to Aug. 2. Wild species of Malus, Pyrus and Prunus avium were observed in mountainous areas and forested plains. We visited Skra Experiment Station, Gori region in this duration, and local cultivars of Prunus aviuum, P. cerasus and wild Prunus species were provided by this Experiment Station. From Aug. 2 the team traveled to the eastern region of Georgia. The team climbed up the slopes of Pankisi valley in Achmeta, where we could find many fruit tree genetic resources of Prunus avium, P. cerasifera, Pyrus sp., Crataegus sp., Mespilus germanica, Corylus sp. and Castanea sp. In the diverse fruit tree species observed, Mespilus germanica and Prumus cerasifera were predominant. During this exploration 86 samples belonging to 7 genera were collected
Dependence of Quadrupole Strength in the Transition
Models of baryon structure predict a small quadrupole deformation of the
nucleon due to residual tensor forces between quarks or distortions from the
pion cloud. Sensitivity to quark versus pion degrees of freedom occurs through
the dependence of the magnetic (), electric (), and
scalar () multipoles in the
transition. We report new experimental values for the ratios
and over the range = 0.4-1.8 GeV, extracted from
precision data using a truncated multipole expansion.
Results are best described by recent unitary models in which the pion cloud
plays a dominant role.Comment: 5 pages, 5 figures, 1 table. To be published in Phys. Rev. Lett.
(References, figures and table updated, minor changes.
Measurement of Inclusive Spin Structure Functions of the Deuteron
We report the results of a new measurement of spin structure functions of the
deuteron in the region of moderate momentum transfer ( = 0.27 -- 1.3
(GeV/c)) and final hadronic state mass in the nucleon resonance region (
= 1.08 -- 2.0 GeV). We scattered a 2.5 GeV polarized continuous electron beam
at Jefferson Lab off a dynamically polarized cryogenic solid state target
(ND) and detected the scattered electrons with the CEBAF Large
Acceptance Spectrometer (CLAS). From our data, we extract the longitudinal
double spin asymmetry and the spin structure function . Our
data are generally in reasonable agreement with existing data from SLAC where
they overlap, and they represent a substantial improvement in statistical
precision. We compare our results with expectations for resonance asymmetries
and extrapolated deep inelastic scaling results. Finally, we evaluate the first
moment of the structure function and study its approach to both the
deep inelastic limit at large and to the Gerasimov-Drell-Hearn sum rule
at the real photon limit (). We find that the first moment varies
rapidly in the range of our experiment and crosses zero at between
0.5 and 0.8 (GeV/c), indicating the importance of the resonance at
these momentum transfers.Comment: 13 pages, 8 figures, ReVTeX 4, final version as accepted by Phys.
Rev.
A tetragonal-to-monoclinic phase transition in a ferroelectric perovskite: the structure of PbZr(0.52)Ti(0.48)O3
The perovskite-like ferroelectric system PbZr(1-x)Ti(x)O3 (PZT) has a nearly
vertical morphotropic phase boundary (MPB) around x=0.45-0.50. Recent
synchrotron x-ray powder diffraction measurements by Noheda et al. [Appl. Phys.
Lett. 74, 2059 (1999)] have revealed a new monoclinic phase between the
previously-established tetragonal and rhombohedral regions. In the present work
we describe a Rietveld analysis of the detailed structure of the tetragonal and
monoclinic PZT phases on a sample with x= 0.48 for which the lattice parameters
are respectively: at= 4.044 A, ct= 4.138 A, at 325 K, and am= 5.721 A, bm=
5.708 A, cm= 4.138 A, beta= 90.496 deg., at 20K. In the tetragonal phase the
shifts of the atoms along the polar [001] direction are similar to those in
PbTiO3 but the refinement indicates that there are, in addition, local
disordered shifts of the Pb atoms of ~0.2 A perpendicular to the polar axis..
The monoclinic structure can be viewed as a condensation along one of the
directions of the local displacements present in the tetragonal phase. It
equally well corresponds to a freezing-out of the local displacements along one
of the directions recently reported by Corker et al.[J. Phys. Condens.
Matter 10, 6251 (1998)] for rhombohedral PZT. The monoclinic structure
therefore provides a microscopic picture of the MPB region in which one of the
"locally" monoclinic phases in the "average" rhombohedral or tetragonal
structures freezes out, and thus represents a bridge between these two phases.Comment: REVTeX, 7 figures. Modifications after referee's suggestion: new
figure (figure 5), comments in 2nd para. (Sect.III) and in 2nd & 3rd para.
(Sect. IV-a), in the abstract: "...of ~0.2 A perpendicular to the polar
axis.
The e p -> e' p eta reaction at and above the S11(1535) baryon resonance
New cross sections for the reaction e p -> ep eta are reported for total
center of mass energy W = 1.5--1.86 GeV and invariant momentum transfer Q^2 =
0.25--1.5 GeV^2. This large kinematic range allows extraction of important new
information about response functions, photocouplings, and eta N coupling
strengths of baryon resonances. Expanded W coverage shows sharp structure at W
\~ 1.7 GeV; this is shown to come from interference between S and P waves and
can be interpreted in terms of known resonances. Improved values are derived
for the photon coupling amplitude for the S11(1535) resonance.Comment: 11 pages, RevTeX, 5 figures, submitted to Phys. Rev. Let
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