7,238 research outputs found
Electrical Investigation of the Oblique Hanle Effect in Ferromagnet/Oxide/Semiconductor Contacts
We have investigated the electrical Hanle effect with magnetic fields applied
at an oblique angle ({\theta}) to the spin direction (the oblique Hanle effect,
OHE) in CoFe/MgO/semiconductor (SC) contacts by employing a three-terminal
measurement scheme. The electrical oblique Hanle signals obtained in
CoFe/MgO/Si and CoFe/MgO/Ge contacts show clearly different line shapes
depending on the spin lifetime of the host SC. Notably, at moderate magnetic
fields, the asymptotic values of the oblique Hanle signals (in both contacts)
are consistently reduced by a factor of cos^2({\theta}) irrespective of the
bias current and temperature. These results are in good agreement with
predictions of the spin precession and relaxation model for the electrical
oblique Hanle effect. At high magnetic fields where the magnetization of CoFe
is significantly tilted from the film plane to the magnetic field direction, we
find that the observed angular dependence of voltage signals in the CoFe/MgO/Si
and CoFe/MgO/Ge contacts are well explained by the OHE, considering the
misalignment angle between the external magnetic field and the magnetization of
CoFe.Comment: 19 pages, 8 figure
The Light and Period Variations of the Eclipsing Binary BX Draconis
New CCD photometric observations of BX Dra were obtained for 26 nights from
2009 April to 2010 June. The long-term photometric behaviors of the system are
presented from detailed studies of the period and light variations, based on
the historical data and our new observations. All available light curves
display total eclipses at secondary minima and inverse O'Connell effects with
Max I fainter than Max II, which are satisfactorily modeled by adding the
slightly time-varying hot spot on the primary star. A total of 87 times of
minimum light spanning over about 74 yrs, including our 22 timing measurements,
were used for ephemeris computations. Detailed analysis of the O-C diagram
showed that the orbital period has changed in combinations with an upward
parabola and a sinusoidal variation. The continuous period increase with a rate
of +5.65 \times 10^-7 d yr^-1 is consistent with that calculated from the
Wilson-Devinney synthesis code. It can be interpreted as a mass transfer from
the secondary to the primary star at a rate of 2.74 \times 10^-7 M\odot yr^-1,
which is one of the largest rates for contact systems. The most likely
explanation of the sinusoidal variation with a period of 30.2 yrs and a
semi-amplitude of 0.0062 d is a light-traveltime effect due to the existence of
a circumbinary object. We suggest that BX Dra is probably a triple system,
consisting of a primary star with a spectral type of F0, its secondary
component of spectral type F1-2, and an unseen circumbinary object with a
minimum mass of M3 = 0.23 M\odot.Comment: 24 pages, including 5 figures and 9 tables, accepted for publication
in PAS
Complete BFT Embedding of Massive Theory with One- and Two-form Gauge Fields
We study the constraint structure of the topologically massive theory with
one- and two-form fields in the framework of Batalin-Fradkin-Tyutin embedding
procedure. Through this analysis we obtain a new type of Wess-Jumino action
with novel symmetry, which is originated from the topological coupling term, as
well as the St\"uckelberg action related to the explicit gauge breaking mass
terms from the original theory.Comment: 22 pages, no figures, references adde
Block Design-Based Local Differential Privacy Mechanisms
In this paper, we propose a new class of local differential privacy (LDP)
schemes based on combinatorial block designs for a discrete distribution
estimation. This class not only recovers many known LDP schemes in a unified
framework of combinatorial block design, but also suggests a novel way of
finding new schemes achieving the optimal (or near-optimal) privacy-utility
trade-off with lower communication costs. Indeed, we find many new LDP schemes
that achieve both the optimal privacy-utility trade-off and the minimum
communication cost among all the unbiased schemes for a certain set of input
data size and LDP constraint. Furthermore, to partially solve the sparse
existence issue of block design schemes, we consider a broader class of LDP
schemes based on regular and pairwise-balanced designs, called RPBD schemes,
which relax one of the symmetry requirements on block designs. By considering
this broader class of RPBD schemes, we can find LDP schemes achieving
near-optimal privacy-utility trade-off with reasonably low communication costs
for a much larger set of input data size and LDP constraint.Comment: 18 pages, 3 figures, and 1 table. This manuscript was submitted to
IEEE Transactions on Information Theory and a short version of this
manuscript will be presented at 2023 IEEE International Symposium on
Information Theor
Clock Light Design Based on Sunrise and Sunset Time
We intend to develop a clock with a natural human perception of time,
instead of a numerical one. Our representation of time was inspired by the
difference in light during sunrise and sunset depending on the season or place
and its annual recurrence. The events of sunrise, midday, and sunset, which
consist our time series, was appointed a specific color based on the theory
associated with color temperature, and connected with gradation. To be able
to show the time information with light, we created a physical form. This
clock light functions as an indirect light source and gives emotional value to
time
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