1,486 research outputs found
Geomagnetically Conjugate Relationship of Polar Geomagnetic Disturbances -Particularly the Distinct Geomagnetic Conjugacy between Syowa Station in Antarctica and Reykjavik in Iceland
In Chapter I, the average pattern of the ionospheric current system of polar geomagnetic storms for the northern and southern polar regions is constructed by analyzing exactly simultaneous events during the IGY period. Those events are classified into two groups; i.e., severe storms where K_P=7.4 and moderate storms where K_p=4.3. In both cases, the average D_p fields for northern and southern polar regions are almost exactly symmetric with each other with respect to the geomagnetic coordinates, suggesting that the geomagnetic linkage holds well between the two polar regions. Several remarks are made on the mechanism of causation of the D_p field. It is emphasized that the D_p field may comprise two components, namely, SP-component which is characterized by enhancement of the S_q^p field by the stronger solar wind in storm time, and defined AEJ-component which has been known as the auroral electrojet concentrating along the narrow region of the auroral zone. In Chapter II, similarity and simultaneity of geomagnetic bay type variations in geomagnetically conjugate areas in the northern and southern polar regions are discussed, based upon simultaneous data of individual bays. From the observed facts, it has been concluded that charged particles of nearly the same flux are precipitating simultaneously in the northern and southern polar ionospheres over the conjugate areas. Besides, it seems likely that nearly the same intensity of electric field is transferred to the both polar regions simultaneously from the magnetosphere. The conjugacy always holds well between the conjugate stations located in the auroral zone and the polar cap at the best-developed stage of geomagnetic bays. Some theoretical discussions are attempted on the structure of instantaneous and individual D_p field of geomagnetic bays. In Chapter III, the conjugacy of storm sudden commencement (SSC) between conjugate points in the auroral zone is described based upon the simultaneous data observed at Syowa Station and Reykjavik. Similarity and simultaneity are good at the conjugate points for SSCs. Observed SSCs are elliptically polarized and the sense of rotation of polarization is counterclockwise and clockwise on the morning and afternoon sides respectively as viewed along the magnetic lines of force in both conjugate points. Comparing the characteristics of polarization and other morphological facts revealed by the present analysis with those of the S_q^p field, it is concluded that the polar part of SSC is attributable to the transfer of excess electric charge to the polar ionosphere from the outer magnetosphere, which is caused by fluctuation and enhancement of the S_q^p field of a pre-SSC stage by the impact of storm time solar wind to the magnetosphere. The propagation of SSC seems to take the form of hydromagnetic wave propagation. In Chapter IV, the conjugacy of sudden impulses (SI) between the conjugate stations in the auroral zone is described, using the simultaneous data obtained at Syowa Station and Reykjavik. Comparison of morphological characteristics of sudden impulse with those of storm sudden commencement indicates that SI and SSC are quite similar and sudden impulse may be caused by the same mechanism as that for SSC. In Chapter V, the conjugacy of geomagnetic pulsations of several minutes in period (pc-5) between conjugate points in the auroral zone is discussed. Pc-5 pulsations have extremely good conjugate relations in regard to their time of occurrence and their wave forms. The polarization of the observed pc-5 is elliptic and the plane of polarization is approximately perpendicular to the geomagnetic lines of force. The sense of rotation of polarization vector is counterclockwise in the morning and clockwise in the afternoon as viewed along the magnetic lines of force. Therefore, pc-5 pulsation may be attributable to low frequency hydromagnetic wave generated in the outer magnetosphere and transmitted along the lines of force to both polar
IMMUNOLOGIC PROPERTIES OF MOUSE THYMUS CELLS : IDENTIFICATION OF T CELL FUNCTIONS WITHIN A MINOR, LOW-DENSITY SUBPOPULATION
The functional attributes of minor subpopulations of mouse thymus cells derived by bovine serum albumin density gradient centrifugation, cortisone treatment, or selective depletion by anti-TL or anti-θ treatment have been examined. A subpopulation derived in each fashion contains the cells required to evoke graft-versus-host reactions in neonatal F1 hybrid recipients and to be stimulated by alloantigens in vitro in one-way mixed lymphocyte cultures and by phytohemagglutinin. The functions of this subpopulation are abrogated by treatment with anti-H-2 plus complement and by high concentrations of anti-θ. A tentative ordering of the various thymus cell subpopulations, on the basis of these and other data, is described
Design of Energy-Efficient Artificial Noise for Physical Layer Security in Visible Light Communications
This paper studies the design of energy-efficient artificial noise (AN)
schemes in the context of physical layer security in visible light
communications (VLC). Two different transmission schemes termed
and
are examined and
compared in terms of secrecy energy efficiency (SEE). In the former, the
closest LED luminaire to the legitimate user (Bob) is the information-bearing
signal's transmitter. At the same time, the rest of the luminaries act as
jammers transmitting AN to degrade the channels of eavesdroppers (Eves). In the
latter, the information-bearing signal and AN are combined and transmitted by
all luminaries. When Eves' CSI is unknown, an indirect design to improve the
SEE is formulated by maximizing Bob's channel's energy efficiency. A
low-complexity design based on the zero-forcing criterion is also proposed. In
the case of known Eves' CSI, we study the design that maximizes the minimum SEE
among those corresponding to all eavesdroppers. At their respective optimal
SEEs, simulation results reveal that when Eves' CSI is unknown, the selective
AN-aided SISO transmission can archive twice better SEE as the AN-aided MISO
does. In contrast, when Eves' CSI is known, the AN-aided MISO outperforms by
30%
Space-local Navier--Stokes turbulence
We investigate the physical-space locality of interactions in
three-dimensional incompressible turbulent flow. To that, we modify the
nonlinear terms of the vorticity equation such that the vorticity field is
advected and stretched by the locally induced velocity. This space-local
velocity field is defined by the truncated Biot--Savart law, where only the
neighboring vorticity field in a sphere of radius is integrated. We conduct
direct numerical simulations of the space-local system to investigate its
statistics in the inertial range. We observe a standard
scaling of the energy spectrum associated with an energy cascade for scales
smaller than the space-local domain size . This result is
consistent with the assumption Kolmogorov's 1941 paper made for the
space-locality of the nonlinear interactions. The enstrophy production is
suppressed for larger scales , and for these scales, the system
exhibits a scaling consistent with a conservative enstrophy cascade.Comment: 22 pages, 8 figure
Minimal modeling of the intrinsic cycle of turbulence driven by steady forcing
Quasi-Cyclic Behavior (QCB) is a common feature of various laminar and
turbulent flows. We conduct Direct Numerical Simulations (DNS) of
three-dimensional flow driven by the steady Taylor--Green forcing to find a
silent similarity between a stable periodic flow at a small Reynolds number
() and turbulent QCB at higher . These two temporal
dynamics are continuously connected by varying . A close
examination of the periodic flow allows the formulation of a simple
three-equation model, representing the evolution of Fourier modes in three
distinct scales. The model reproduces the continuously connected periodic
solution and QCB when is varied. We find that non-local triad
interactions are necessary to maintain the periodic solution and QCB.
Bifurcation analyses illustrate that the model can also reproduce several
critical features of turbulence, such as sudden relaminarization of transient
chaos. These findings suggest that the model is not specific to the studied
flow in a periodic domain but is of more general importance in investigating
turbulence in different flow configurations
Disability Prevention Programs for Older People: Factors Associated with Medical and Nursing Care Costs
This study aimed to clarify factors associated with medical and nursing care costs for older people living in community and to suggest an effective disability prevention programs. Total of participants in this study was 83 individuals (29 men and 54 women; mean age 81.2 ± 6.3 years old) on November 1st – December 28th, 2014. This study compared the average medical and nursing care costs per month with national average for those aged ≥ 65 years old. Logistic regression test was conducted to examine its association with medical and nursing care costs. Those who had outing activities ≥ 3 times a week were approximately three times less likely to reduce medical and nursing care costs than those who had outing activities < 3 times a week despite three controlled covariates (OR = 3.23 and 95% CI = 1.03 – 10.42). Disability prevention programs that improve frequency of outing at least three times in a week may become a valid economic approach to older people who do not live in nursing home
Early Ontogeny of the Japanese Common Squid Todarodes pacificus (Cephalopoda, Ommastrephidae) with Special Reference to its Characteristic Morphology and Ecological Significance
Early ontogeny of the Japanese Common Squid Todarodes pacificus was described for artificially inseminated and collected specimens to present new criteria for developmental stages in relation to its ecological adaptation. For the purpose, details for formation of the following organs and tissues were observed with special attention: cilia on the integument, mouth part, shell sac and stellate ganglia, visceral mass, funnel-collar complex, statocysts, eye parts, and ventral photosensitive vesicles. At the embryonic stage (i.e., pre-hatching), various types of epidermal cilia that seem to work as the embryonic rotation were detected. At the early postembryonic stage (i.e., post-hatching), the epidermal lines were characteristically arranged at the scattered condition on arms, tentacles, head, and funnel. Novel strong muscle fibers were distinct in the base of tentacles and funnel retractor muscles at the early postembryonic stage, which is clearly related to the head withdrawal behavior of the paralarvae. The lip cilia and toothed beak developed at the early postembryonic stage, but disappeared later; these apparatus were considered to be related with a change of unique feeding mode in the paralarval life. Based on such morphological features, four distinct stages, namely, paralarval stage 1, 2, 3, and juvenile stage are proposed. The present observations are discussed in relation to survival strategy at early life of T. pacificus and they are compared with those in other cephalopods
Dyson processes on the octonion algebra
We consider Brownian motion on symmetric matrices of octonions, and study the
law of the spectrum. Due to the fact that the octonion algebra is
nonassociative, the dimension of the matrices plays a special role. We provide
two specific models on octonions, which give some indication of the relation
between the multiplicity of eigenvalues and the exponent in the law of the
spectrum
Indoor particle counts during Asian dust events under everyday conditions at an apartment in Japan.
[Objective]Asian dust storms originating from arid regions of Mongolia and China are a well-known springtime phenomenon throughout East Asia. Evidence is increasing for the adverse health effects caused by airborne desert dust inhalation. Given that people spend approximately 90 % of their time indoors, indoor air quality is a significant concern. The present study aimed to examine the influence of outdoor particulate matter (PM) levels on indoor PM levels during Asian dust events under everyday conditions. [Methods]We simultaneously monitored counts of particles larger than 0.3, 0.5, 1, 2, and 5 μm using two direct-reading instruments (KC-01D1 airborne particle counter; Rion), one placed in an apartment room and another on the veranda, under everyday conditions before and during an Asian dust event. We also examined how indoor particle counts were affected by opening a window, crawling, and air purifier use. [Results]An Asian dust event on 24 April 2012 caused 50- and 20-fold increases in PM counts in outdoor and indoor air, respectively. A window open for 10 min resulted in a rapid increase of indoor PM counts up to 70 % of outside levels that did not return to baseline levels after 3 h. An air purifier rapidly reduced PM counts for all particle sizes measured. [Conclusions]It is important to account for occupant behavior, such as window-opening and air purifier use, when estimating residential exposure to particulate matter
A rotating cavity for high-field angle-dependent microwave spectroscopy of low-dimensional conductors and magnets
The cavity perturbation technique is an extremely powerful method for
measuring the electrodynamic response of a material in the millimeter- and
sub-millimeter spectral range (10 GHz to 1 THz), particularly in the case of
high-field/frequency magnetic resonance spectroscopy. However, the application
of such techniques within the limited space of a high-field magnet presents
significant technical challenges. We describe a 7.62 mm x 7.62 mm (diameter x
length) rotating cylindrical cavity which overcomes these problems.Comment: 11 pages including 8 figure
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