1,706 research outputs found
Power Consumption Model of NDN-Based Multicore Software Router Based on Detailed Protocol Analysis
Named data networking (NDN) has received considerable attention recently, mainly due to its built-in caching, which is expected to enable widespread and transparent operator-controlled caching. One of the important research challenges is to reduce the amount of power consumed by NDN networks as it has been shown that NDN's name prefix matching and caching are power-hungry. As a first step to achieving power-efficient NDN networks, in this paper, we develop a power consumption model of a multicore software NDN router. By applying this model to analyze how caching reduces power, we report that caching can reduce power consumption of an NDN network if the power consumption of routers is in proportion to their load and the computation of caching is as light as that of forwarding
Evidence for Strong-coupling S-wave Superconductivity in MgB2 :11B NMR Study
We have investigated a gap structure in a newly-discovered superconductor,
MgB2 through the measurement of 11B nuclear spin-lattice relaxation rate,
^{11}(1/T_1). ^{11}(1/T_1) is proportional to the temperature (T) in the normal
state, and decreases exponentially in the superconducting (SC) state, revealing
a tiny coherence peak just below T_c. The T dependence of 1/T_1 in the SC state
can be accounted for by an s-wave SC model with a large gap size of 2\Delta
/k_BT_c \sim 5 which suggests to be in a strong-coupling regime.Comment: 2 pages with 1 figur
Increased production of viral proteins by a 3'-LTR-deleted infectious clone of human T-cell leukemia virus type 1
We previously reported that a full-length provirus of HTLV-1 was directly constructed from the HTLV-1-transformed cell line MT-2 using overlapping polymerase chain reaction (PCR) and cloned into a plasmid vector (pFL-MT2). 293T cells transfected with pFL-MT2 alone did not produce virus particles because there was no expression of the viral transactivator protein Tax, whereas cells transfected with pFL-MT2 plus a Tax expression vector produced virus-like particles. In the process of constructing the HTLV-1 provirus by overlapping PCR, we also constructed an incomplete molecular clone, in which the 3' long terminal repeat (LTR) was replaced with the endogenous human gene, which resulted in the expression of a tax gene shorter by 43 bp. This incomplete molecular clone alone expressed Tax and produced the viral protein in transfected cells. Various clones were then constructed with different lengths of the 3' LTR and lacking the reverse-direction TATA box. The clones contained over 113 bp of the 3' LTR, with no reverse-direction TATA box, which might express the full-length tax gene, and did not produce the viral antigen. These results suggest that Tax in which the C-terminal portion is deleted is more strongly expressed than the wild-type protein and has transcriptional activity
Antiferromagnetic phase transition in four-layered high-T_c superconductors Ba_2Ca_3Cu_4O_8(F_yO_{1-y})_2 with T_c=55-102 K: Cu- and F-NMR studies
We report on magnetic characteristics in four-layered high-T_c
superconductors Ba_2Ca_3Cu_4O_8(F_yO_{1-y})_2 with apical fluorine through Cu-
and F-NMR measurements. The substitution of oxygen for fluorine at the apical
site increases the carrier density (N_h) and T_c from 55 K up to 102 K. The NMR
measurements reveal that antiferromagnetic order, which can uniformly coexist
with superconductivity, exists up to N_h = 0.15, which is somewhat smaller than
N_h = 0.17 being the quantum critical point (QCP) for five-layered compounds.
The fact that the QCP for the four-layered compounds moves to a region of lower
carrier density than for five-layered ones ensures that the decrease in the
number of CuO_2 layers makes an interlayer magnetic coupling weaker.Comment: 7 pages, 6 gigures, Submitted to J. Phys. Soc. Jp
Nuclear spin-spin coupling in La_{2-x}Sr_{x}CuO_{4} studied by stimulated echo decay
We have performed copper NQR experiments in high temperature superconductors
YBa_{2}Cu_{4}O_{8}, YBa_{2}Cu_{3}O_{7}, and La_{2-x}Sr_{x}CuO_{4} (x=0.12 and
0.15), using the stimulated echo technique. The stimulated echo intensity is
analyzed by a model that includes the spin-lattice relaxation process (T_ {1
}-process) and the fluctuating local field due to nuclear spin-spin coupling.
The model gives quantitative account of the experimental results in Y-based
compounds using the known values of 1/T_{1} and 1/T_{2G}, the gaussian decay
rate of the spin echo intensity. The same model applied to LSCO enables us to
extract the value of T_{2G}. Our results indicate that T_{1}T/T_{2G} is
independent of temperature, implying that the dynamic exponent is one in
La_{2-x}Sr_{x}CuO_{4}.Comment: 14 pages, 11 fugures, The bibliography field is correcte
Infrared/optical - X-ray simultaneous observations of X-ray flares in GRB 071112C and GRB 080506
We investigate the origin of short X-ray flares which are occasionally
observed in early stages of afterglows of gamma-ray bursts (GRBs). We observed
two events, GRB 071112C and GRB 080506, before the start of X-ray flares in the
optical and near-infrared (NIR) bands with the 1.5-m Kanata telescope. In
conjunction with published X-ray and optical data, we analyzed densely sampled
light curves of the early afterglows and spectral energy distributions (SEDs)
in the NIR-X-ray ranges. We found that the SEDs had a break between the optical
and X-ray bands in the normal decay phases of both GRBs regardless of the model
for the correction of the interstellar extinction in host galaxies of GRBs. In
the X-ray flares, X-ray flux increased by 3 and 15 times in the case of GRB
071112C and 080506, respectively, and the X-ray spectra became harder than
those in the normal decay phases. No significant variation in the optical-NIR
range was detected together with the X-ray flares. These results suggest that
the X-ray flares were associated with either late internal shocks or external
shocks from two-component jets.Comment: 10 pages, 5 figures, accepted to Astronomy and Astrophysic
Unique Spin Dynamics and Unconventional Superconductivity in the Layered Heavy Fermion Compound CeIrIn_5:NQR Evidence
We report measurements of the ^{115}In nuclear spin-lattice relaxation rate
(1/T_1) between T=0.09 K and 100 K in the new heavy fermion (HF) compound
CeIrIn_5. At 0.4 K < T < 100 K, 1/T_1 is strongly T-dependent, which indicates
that CeIrIn_5 is much more itinerant than known Ce-based HFs. We find that
1/T_1T, subtracting that for LaIrIn_5, follows a 1/(T+\theta)^{3/4} variation
with \theta=8 K. We argue that this novel feature points to anisotropic, due to
a layered crystal structure, spin fluctuations near a magnetic ordering. The
bulk superconductivity sets in at 0.40 K below which the coherence peak is
absent and 1/T_1 follows a T^3 variation, which suggests unconventional
superconductivity with line-node gap.Comment: minor changes, appeared in PRL (4 pages, 4 figures
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