6,801 research outputs found
Evolving small-world networks with geographical attachment preference
We introduce a minimal extended evolving model for small-world networks which
is controlled by a parameter. In this model the network growth is determined by
the attachment of new nodes to already existing nodes that are geographically
close. We analyze several topological properties for our model both
analytically and by numerical simulations. The resulting network shows some
important characteristics of real-life networks such as the small-world effect
and a high clustering.Comment: 11 pages, 4 figure
High Dimensional Apollonian Networks
We propose a simple algorithm which produces high dimensional Apollonian
networks with both small-world and scale-free characteristics. We derive
analytical expressions for the degree distribution, the clustering coefficient
and the diameter of the networks, which are determined by their dimension
Magnetic configurations of the tilted current sheets in magnetotail
In this research, the geometrical structures of tilted current sheet and tail flapping waves have been analysed based on multiple spacecraft measurements and some features of the tilted current sheets have been made clear for the first time. The geometrical features of the tilted current sheet revealed in this investigation are as follows: (1) The magnetic field lines (MFLs) in the tilted current sheet are generally plane curves and the osculating planes in which the MFLs lie are about vertical to the equatorial plane, while the normal of the tilted current sheet leans severely to the dawn or dusk side. (2) The tilted current sheet may become very thin, the half thickness of its neutral sheet is generally much less than the minimum radius of the curvature of the MFLs. (3) In the neutral sheet, the field-aligned current density becomes very large and has a maximum value at the center of the current sheet. (4) In some cases, the current density is a bifurcated one, and the two humps of the current density often superpose two peaks in the gradient of magnetic strength, indicating that the magnetic gradient drift current is possibly responsible for the formation of the two humps of the current density in some tilted current sheets. Tilted current sheets often appear along with tail current sheet flapping waves. It is found that, in the tail flapping current sheets, the minimum curvature radius of the MFLs in the current sheet is rather large with values around 1 <I>R<sub>E</sub></I>, while the neutral sheet may be very thin, with its half thickness being several tenths of <I>R<sub>E</sub></I>. During the flapping waves, the current sheet is tilted substantially, and the maximum tilt angle is generally larger than 45&deg;. The phase velocities of these flapping waves are several tens km/s, while their periods and wavelengths are several tens of minutes, and several earth radii, respectively. These tail flapping events generally last several hours and occur during quiet periods or periods of weak magnetospheric activity
Transceiver Optimization for Wireless Powered Time-Division Duplex MU-MIMO Systems: Non-Robust and Robust Designs
Wireless powered communication (WPC) has been considered as one of the key technologies in the Internet of Things (IoT) applications. In this paper, we study a wireless powered time-division duplex (TDD) multiuser multiple-input multiple-output (MU-MIMO) system, where the base station (BS) has its own power supply and all users can harvest radio frequency (RF) energy from the BS. We aim to maximize the users' information rates by jointly optimizing the duration of users' time slots and the signal covariance matrices of the BS and users. Different to the commonly used sum rate and max-min rate criteria, the proportional fairness of users' rates is considered in the objective function. We first study the ideal case with the perfect channel state information (CSI), and show that the non-convex proportionally fair rate optimization problem can be transformed into an equivalent convex optimization problem. Then we consider practical systems with imperfect CSI, where the CSI mismatch follows a Gaussian distribution. A chance-constrained robust system design is proposed for this scenario, where the Bernstein inequality is applied to convert the chance constraints into the convex constraints. Finally, we consider a more general case where only partial knowledge of the CSI mismatch is available. In this case, the conditional value-at-risk (CVaR) method is applied to solve the distributionally robust system rate optimization problem. Simulation results are presented to show the effectiveness of the proposed algorithms
Scaling of Horizontal and Vertical Fixational Eye Movements
Eye movements during fixation of a stationary target prevent the adaptation
of the photoreceptors to continuous illumination and inhibit fading of the
image. These random, involuntary, small, movements are restricted at long time
scales so as to keep the target at the center of the field of view. Here we use
the Detrended Fluctuation Analysis (DFA) in order to study the properties of
fixational eye movements at different time scales. Results show different
scaling behavior between horizontal and vertical movements. When the small
ballistics movements, i.e. micro-saccades, are removed, the scaling exponents
in both directions become similar. Our findings suggest that micro-saccades
enhance the persistence at short time scales mostly in the horizontal component
and much less in the vertical component. This difference may be due to the need
of continuously moving the eyes in the horizontal plane, in order to match the
stereoscopic image for different viewing distance.Comment: 5 pages, 4 figure
FLEET: Butterfly Estimation from a Bipartite Graph Stream
We consider space-efficient single-pass estimation of the number of
butterflies, a fundamental bipartite graph motif, from a massive bipartite
graph stream where each edge represents a connection between entities in two
different partitions. We present a space lower bound for any streaming
algorithm that can estimate the number of butterflies accurately, as well as
FLEET, a suite of algorithms for accurately estimating the number of
butterflies in the graph stream. Estimates returned by the algorithms come with
provable guarantees on the approximation error, and experiments show good
tradeoffs between the space used and the accuracy of approximation. We also
present space-efficient algorithms for estimating the number of butterflies
within a sliding window of the most recent elements in the stream. While there
is a significant body of work on counting subgraphs such as triangles in a
unipartite graph stream, our work seems to be one of the few to tackle the case
of bipartite graph streams.Comment: This is the author's version of the work. It is posted here by
permission of ACM for your personal use. Not for redistribution. The
definitive version was published in Seyed-Vahid Sanei-Mehri, Yu Zhang, Ahmet
Erdem Sariyuce and Srikanta Tirthapura. "FLEET: Butterfly Estimation from a
Bipartite Graph Stream". The 28th ACM International Conference on Information
and Knowledge Managemen
Fano Effect through Parallel-coupled Double Coulomb Islands
By means of the non-equilibrium Green function and equation of motion method,
the electronic transport is theoretically studied through a parallel-coupled
double quantum dots(DQD) in the presence of the on-dot Coulomb correlation,
with an emphasis put on the quantum interference. It has been found that in the
Coulomb blockage regime, the quantum interference between the bonding and
antiboding DQD states or that between their Coulomb blockade counterparts may
result in the Fano resonance in the conductance spectra, and the Fano peak
doublet may be observed under certain non-equilibrium condition. The
possibility of manipulating the Fano lineshape is predicted by tuning the
dot-lead coupling and magnetic flux threading the ring connecting the dots and
leads. Similar to the case without Coulomb interaction, the direction of the
asymmetric tail of Fano lineshape can be flipped by the external field. Most
importantly, by tuning the magnetic flux, the function of four relevant states
can be interchanged, giving rise to the swap effect, which might play a key
role as a qubit in the quantum computation.Comment: 7 pages, 5 figure
Survivin expression in ovarian cancer
Aim: To examine the expression of survivin in benign ovarian tumors, ovarian carcinomas of different stages. Methods: We screened the expression of survivin mRNA by reverse transcription polymerase chain reaction in 114 ovarian tissue samples. Quantitative real-time PCR was used to estimate survivin mRNA levels in the samples with positive survivin expression. Results: No survivin mRNA was expressed in all normal ovarian specimens, while it appeared in 73% of ovarian carcinomas, 47% of borderline ovarian carcinomas and 19% of benign ovarian tumors. The survivin mRNA expression rate was positively associated with clinical stage (P = 0.026) and differentiation grade (P = 0.049). There was notably statistically significant difference in the survivin mRNA expression rate dependent on different histological types (serous, mucinous, endometrioid, P = 0.008), but not β dependent on lymph node metastasis (P = 0.921) and ascites (P = 0.87). In tissues with positive expression of survivin, we also found that mean survivin mRNA expression levels were higher in ovarian carcinomas than that in benign ovarian tumors and borderline ovarian carcinoma tissues (P < 0.001). Among ovarian carcinomas, the high survivin mRNA expression levels correlated with the clinical stages, differentiation grade, lymph node metastasis, but not β with ascites and histological type. Conclusion: Our study suggest that survivin is associated with progression of ovarian carcinoma.Π¦Π΅Π»Ρ: ΠΈΡΡΠ»Π΅Π΄ΠΎΠ²Π°ΡΡ ΡΠΊΡΠΏΡΠ΅ΡΡΠΈΡ ΡΡΡΠ²ΠΈΠ²ΠΈΠ½Π° Π² Π΄ΠΎΠ±ΡΠΎΠΊΠ°ΡΠ΅ΡΡΠ²Π΅Π½Π½ΡΡ
ΠΈ Π·Π»ΠΎΠΊΠ°ΡΠ΅ΡΡΠ²Π΅Π½Π½ΡΡ
Π½ΠΎΠ²ΠΎΠΎΠ±ΡΠ°Π·ΠΎΠ²Π°Π½ΠΈΡΡ
ΡΠΈΡΠ½ΠΈΠΊΠ°. ΠΠ΅ΡΠΎΠ΄Ρ: ΡΠΊΡΠΏΡΠ΅ΡΡΠΈΡ
ΠΌΠ ΠΠ ΡΡΡΠ²ΠΈΠ²ΠΈΠ½Π° ΠΈΡΡΠ»Π΅Π΄ΠΎΠ²Π°Π½Π° ΠΌΠ΅ΡΠΎΠ΄ΠΎΠΌ RT-PCR Π² 114 ΠΎΠ±ΡΠ°Π·Π°Ρ
ΡΠΊΠ°Π½ΠΈ ΡΠΈΡΠ½ΠΈΠΊΠ° ΡΠ΅Π»ΠΎΠ²Π΅ΠΊΠ°. ΠΠ»Ρ ΡΡΡΠ°Π½ΠΎΠ²Π»Π΅Π½ΠΈΡ ΡΡΠΎΠ²Π½Ρ ΡΠΊΡΠΏΡΠ΅ΡΠΈΠΈ
ΠΌΠ ΠΠ ΡΡΡΠ²ΠΈΠ²ΠΈΠ½Π° ΠΏΡΠΈΠΌΠ΅Π½ΡΠ»ΠΈ ΠΊΠΎΠ»ΠΈΡΠ΅ΡΡΠ²Π΅Π½Π½ΡΠΉ PCR Π² ΡΠ΅ΠΆΠΈΠΌΠ΅ ΡΠ΅Π°Π»ΡΠ½ΠΎΠ³ΠΎ Π²ΡΠ΅ΠΌΠ΅Π½ΠΈ. Π Π΅Π·ΡΠ»ΡΡΠ°ΡΡ: ΡΠΊΡΠΏΡΠ΅ΡΡΠΈΡ ΠΌΠ ΠΠ ΡΡΡΠ²ΠΈΠ²ΠΈΠ½Π°
Π½Π΅ Π²ΡΡΠ²Π»Π΅Π½Π° Π² ΠΎΠ±ΡΠ°Π·ΡΠ°Ρ
Π½ΠΎΡΠΌΠ°Π»ΡΠ½ΠΎΠΉ ΡΠΊΠ°Π½ΠΈ ΡΠΈΡΠ½ΠΈΠΊΠ°, Π½ΠΎ Π·Π°ΡΠ΅Π³ΠΈΡΡΡΠΈΡΠΎΠ²Π°Π½Π° Π² 73% ΡΠ»ΡΡΠ°Π΅Π² ΡΠ°ΠΊΠ° ΡΠΈΡΠ½ΠΈΠΊΠ°, 47% ΡΠ»ΡΡΠ°Π΅Π² ΡΠ΅ΡΠΎΠ·Π½ΡΡ
ΠΎΠΏΡΡ
ΠΎΠ»Π΅ΠΉ ΡΠΈΡΠ½ΠΈΠΊΠ° ΡΠ΅ΡΠΎΠ·Π½ΠΎΠ³ΠΎ ΡΠΈΠΏΠ° ΠΈ 19% ΠΎΠ±ΡΠ°Π·ΡΠΎΠ² Π΄ΠΎΠ±ΡΠΎΠΊΠ°ΡΠ΅ΡΡΠ²Π΅Π½Π½ΡΡ
ΠΎΠΏΡΡ
ΠΎΠ»Π΅ΠΉ. Π£ΡΡΠ°Π½ΠΎΠ²Π»Π΅Π½Π° ΠΏΠΎΠ»ΠΎΠΆΠΈΡΠ΅Π»ΡΠ½Π°Ρ Π·Π°Π²ΠΈΡΠΈΠΌΠΎΡΡΡ ΠΌΠ΅ΠΆΠ΄Ρ
ΡΡΠΎΠ²Π½Π΅ΠΌ ΡΠΊΡΠΏΡΠ΅ΡΡΠΈΠΈ ΠΌΠ ΠΠ ΡΡΡΠ²ΠΈΠ²ΠΈΠ½Π° ΠΈ ΠΊΠ»ΠΈΠ½ΠΈΡΠ΅ΡΠΊΠΎΠΉ ΡΡΠ°Π΄ΠΈΠ΅ΠΉ Π·Π°Π±ΠΎΠ»Π΅Π²Π°Π½ΠΈΡ (P = 0,026), ΠΈ ΡΡΠ΅ΠΏΠ΅Π½ΡΡ Π΄ΠΈΡΡΠ΅ΡΠ΅Π½ΡΠΈΡΠΎΠ²ΠΊΠΈ ΠΎΠΏΡΡ
ΠΎΠ»ΠΈ
(P = 0,049). ΠΡΡΠ²Π»Π΅Π½Π° ΡΡΠ°ΡΠΈΡΡΠΈΡΠ΅ΡΠΊΠΈ Π·Π½Π°ΡΠΈΠΌΠ°Ρ Π·Π°Π²ΠΈΡΠΈΠΌΠΎΡΡΡ ΡΡΠΎΠ²Π½Ρ ΡΠΊΡΠΏΡΠ΅ΡΡΠΈΠΈ ΠΌΠ ΠΠ ΡΡΡΠ²ΠΈΠ²ΠΈΠ½Π° ΠΎΡ Π³ΠΈΡΡΠΎΠ»ΠΎΠ³ΠΈΡΠ΅ΡΠΊΠΎΠ³ΠΎ ΡΠΈΠΏΠ°
ΠΎΠΏΡΡ
ΠΎΠ»ΠΈ (ΡΠ΅ΡΠΎΠ·Π½ΠΎΠ³ΠΎ, ΠΌΡΠΊΠΎΠ·Π½ΠΎΠ³ΠΎ, ΡΠ½Π΄ΠΎΠΌΠ΅ΡΡΠΈΠΎΠΈΠ΄Π½ΠΎΠ³ΠΎ, P = 0,008) ΠΈ ΠΎΡΡΡΡΡΡΠ²ΠΈΠ΅ ΡΠ°ΠΊΠΎΠ²ΠΎΠΉ ΠΎΡ Π½Π°Π»ΠΈΡΠΈΡ ΠΌΠ΅ΡΠ°ΡΡΠ°Π·ΠΎΠ² Π² Π»ΠΈΠΌΡΠ°ΡΠΈΡΠ΅ΡΠΊΠΈΡ
ΡΠ·Π»Π°Ρ
(P = 0.921) ΠΈΠ»ΠΈ Π°ΡΡΠΈΡΠ° (P = 0.87). Π’Π°ΠΊΠΆΠ΅ ΡΡΡΠ°Π½ΠΎΠ²Π»Π΅Π½ΠΎ, ΡΡΠΎ ΡΡΠ΅Π΄Π½ΠΈΠ΅ ΡΡΠΎΠ²Π½ΠΈ ΡΠΊΡΠΏΡΠ΅ΡΡΠΈΠΈ ΠΌΠ ΠΠ ΡΡΡΠ²ΠΈΠ²ΠΈΠ½Π° Π²ΡΡΠ΅ ΠΏΡΠΈ ΡΠ°ΠΊΠ΅
ΡΠΈΡΠ½ΠΈΠΊΠ°, ΡΠ΅ΠΌ Π² ΡΠΊΠ°Π½ΠΈ Π΄ΠΎΠ±ΡΠΎΠΊΠ°ΡΠ΅ΡΡΠ²Π΅Π½Π½ΡΡ
Π½ΠΎΠ²ΠΎΠ±ΡΠ°Π·ΠΎΠ²Π°Π½ΠΈΠΉ ΠΈΠ»ΠΈ ΡΠ΅ΡΠΎΠ·Π½ΡΡ
ΠΎΠΏΡΡ
ΠΎΠ»Π΅ΠΉ ΡΠΈΡΠ½ΠΈΠΊΠ° ΠΏΠΎΠ³ΡΠ°Π½ΠΈΡΠ½ΠΎΠ³ΠΎ ΡΠΈΠΏΠ° (P < 0,001).
ΠΡΠΈ ΡΠ°ΠΊΠ΅ ΡΠΈΡΠ½ΠΈΠΊΠ° Π²ΡΡΠΎΠΊΠΈΠΉ ΡΡΠΎΠ²Π΅Π½Ρ ΡΠΊΡΠΏΡΠ΅ΡΡΠΈΠΈ ΠΌΠ ΠΠ ΡΡΡΠ²ΠΈΠ²ΠΈΠ½Π° ΠΊΠΎΡΡΠ΅Π»ΠΈΡΠΎΠ²Π°Π» Ρ ΠΊΠ»ΠΈΠ½ΠΈΡΠ΅ΡΠΊΠΎΠΉ ΡΡΠ°Π΄ΠΈΠ΅ΠΉ Π·Π°Π±ΠΎΠ»Π΅Π²Π°Π½ΠΈΡ, ΡΡΠ΅ΠΏΠ΅Π½ΡΡ
Π΄ΠΈΡΡΠ΅ΡΠ΅Π½ΡΠΈΡΠΎΠ²ΠΊΠΈ ΠΎΠΏΡΡ
ΠΎΠ»Π΅Π²ΡΡ
ΠΊΠ»Π΅ΡΠΎΠΊ, Π½ΠΎ Π½Π΅ ΠΊΠΎΡΡΠ΅Π»ΠΈΡΠΎΠ²Π°Π» Ρ Π³ΠΈΡΡΠΎΠ»ΠΎΠ³ΠΈΡΠ΅ΡΠΊΠΈΠΌ ΡΠΈΠΏΠΎΠΌ Π½ΠΎΠ²ΠΎΠΎΠ±ΡΠ°Π·ΠΎΠ²Π°Π½ΠΈΡ. ΠΡΠ²ΠΎΠ΄Ρ: ΡΠ΅Π·ΡΠ»ΡΡΠ°ΡΡ
ΡΠ²ΠΈΠ΄Π΅ΡΠ΅Π»ΡΡΡΠ²ΡΡΡ ΠΎ ΡΠΎΠΌ, ΡΡΠΎ ΡΠΊΡΠΏΡΠ΅ΡΡΠΈΡ ΡΡΡΠ²ΠΈΠ²ΠΈΠ½Π° Π°ΡΡΠΎΡΠΈΠΈΡΠΎΠ²Π°Π½Π° Ρ ΠΏΡΠΎΠ³ΡΠ΅ΡΡΠΈΠ΅ΠΉ ΡΠ°ΠΊΠ° ΡΠΈΡΠ½ΠΈΠΊΠ°.
ΠΠ»ΡΡΠ΅Π²ΡΠ΅ ΡΠ»ΠΎΠ²Π°: ΡΡΡΠ²ΠΈΠ²ΠΈΠ½, ΡΠ°ΠΊ ΡΠΈΡΠ½ΠΈΠΊΠ°, ΠΎΠΏΡΡ
ΠΎΠ»Π΅Π²Π°Ρ ΠΏΡΠΎΠ³ΡΠ΅ΡΡΠΈΡ
Aqueous Reactive Species Induced by a Surface Air Discharge: Heterogenous Mass Transfer and Liquid Chemistry Pathways
Plasma-liquid interaction is a critical area of plasma science and a knowledge bottleneck for many promising applications. In this paper, the interaction between a surface air discharge and its downstream sample of deionized water is studied with a system-level computational model, which has previously reached good agreement with experimental results. Our computational results reveal that the plasma-induced aqueous species are mainly H+, nitrate, nitrite, H2O2 and O-3. In addition, various short-lived aqueous species are also induced, regardless whether they are generated in the gas phase first. The production/loss pathways for aqueous species are quantified for an air gap width ranging from 0.1 to 2 cm, of which heterogeneous mass transfer and liquid chemistry are found to play a dominant role. The short-lived reactive oxygen species (ROS) and reactive nitrogen species (RNS) are strongly coupled in liquid-phase reactions: NO3 is an important precursor for short-lived ROS, and in turn OH, O-2(-) and HO2 play a crucial role for the production of short-lived RNS. Also, heterogeneous mass transfer depends strongly on the air gap width, resulting in two distinct scenarios separated by a critical air gap of 0.5 cm. The liquid chemistry is significantly different in these two scenarios
First- and Second-Order Phase Transitions, Fulde-Ferrel Inhomogeneous State and Quantum Criticality in Ferromagnet/Superconductor Double Tunnel Junctions
First- and second-order phase transitions, Fulde-Ferrel (FF) inhomogeneous
superconducting (SC) state and quantum criticality in
ferromagnet/superconductor/ferromagnet double tunnel junctions are
investigated. For the antiparallel alignment of magnetizations, it is shown
that a first-order phase transition from the homogeneous BCS state to the
inhomogeneous FF state occurs at a certain bias voltage ; while the
transitions from the BCS state and the FF state to the normal state at are of the second-order. A phase diagram for the central superconductor
is presented. In addition, a quantum critical point (QCP), , is
identified. It is uncovered that near the QCP, the SC gap, the chemical
potential shift induced by the spin accumulation, and the difference of free
energies between the SC and normal states vanish as with
the quantum critical exponents , 1 and 2, respectively. The tunnel
conductance and magnetoresistance are also discussed.Comment: 5 pages, 4 figures, Phys. Rev. B 71, 144514 (2005
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