770 research outputs found
The research of modern He discharge in volcanic and tectonically active areas of China's continent
The releasing features of modern helium in volcanic and tectonically active areas of China’s continent are here discussed, presenting that the current escaped He in volcanic areas are mainly the mantle-derived He. The 3HeO4He ratios of these He are gradually lowered during the ascent of deep-seated He towards the surface due to the strong diffusion and migmatization of the air. There is little mantle-derived He in the escaped gases from the hot springs distributed along the active tectonic belts, these gases are mostly derived from the crust The 3HeO4He ratios of the crustal gases (including natural gas) in Eastern China are relatively higher than those gases in
Middle-Western China. It is difficult to interpret this
phenomenon by means of the differences of tectonic activity in those areas. We consider that the main reason of this occurrence may be related to the variation of the crustal thickness of China’s continent from East to West
Effect of disorder with long-range correlation on transport in graphene nanoribbon
Transport in disordered armchair graphene nanoribbons (AGR) with long-range
correlation between quantum wire contact is investigated by transfer matrix
combined with Landauer's formula. Metal-insulator transition is induced by
disorder in neutral AGR. Thereinto, the conductance is one conductance quantum
for metallic phase and exponentially decays otherwise when the length of AGR is
infinity and far longer than its width. Similar to the case of long-range
disorder, the conductance of neutral AGR first increases and then decreases
while the conductance of doped AGR monotonically decreases, as the disorder
strength increases. In the presence of strong disorder, the conductivity
depends monotonically and non-monotonically on the aspect ratio for heavily
doped and slightly doped AGR respectively.Comment: 6 pages, 8 figures; J. Phys: Condensed Matter (May 2012
Transport through a quantum wire with a side quantum-dot array
A noninteracting quantum-dot array side-coupled to a quantum wire is studied.
Transport through the quantum wire is investigated by using a noninteracting
Anderson tunneling Hamiltonian. The conductance at zero temperature develops an
oscillating band with resonances and antiresonances due to constructive and
destructive interference in the ballistic channel, respectively. Moreover, we
have found an odd-even parity in the system, whose conductance vanishes for an
odd number of quantum dots while becomes for an even number. We
established an explicit relation between this odd-even parity, and the
positions of the resonances and antiresonances of the conductivity with the
spectrum of the isolated QD arrayComment: 5 pages, 4 figures, submitted to PR
Discovering temporal regularities in retail customers’ shopping behavior
In this paper we investigate the regularities characterizing the temporal purchasing behavior of the customers of a retail market chain. Most of the literature studying purchasing behavior focuses on what customers buy while giving few importance to the temporal dimension. As a consequence, the state of the art does not allow capturing which are the temporal purchasing patterns of each customers. These patterns should describe the customerâ\u80\u99s temporal habits highlighting when she typically makes a purchase in correlation with information about the amount of expenditure, number of purchased items and other similar aggregates. This knowledge could be exploited for different scopes: set temporal discounts for making the purchases of customers more regular with respect the time, set personalized discounts in the day and time window preferred by the customer, provide recommendations for shopping time schedule, etc. To this aim, we introduce a framework for extracting from personal retail data a temporal purchasing profile able to summarize whether and when a customer makes her distinctive purchases. The individual profile describes a set of regular and characterizing shopping behavioral patterns, and the sequences in which these patterns take place. We show how to compare different customers by providing a collective perspective to their individual profiles, and how to group the customers with respect to these comparable profiles. By analyzing real datasets containing millions of shopping sessions we found that there is a limited number of patterns summarizing the temporal purchasing behavior of all the customers, and that they are sequentially followed in a finite number of ways. Moreover, we recognized regular customers characterized by a small number of temporal purchasing behaviors, and changing customers characterized by various types of temporal purchasing behaviors. Finally, we discuss on how the profiles can be exploited both by customers to enable personalized services, and by the retail market chain for providing tailored discounts based on temporal purchasing regularity
Observations of Forbush Decreases of Cosmic-Ray Electrons and Positrons with the Dark Matter Particle Explorer
The Forbush decrease (FD) represents the rapid decrease of the intensities of charged particles accompanied with the coronal mass ejections or high-speed streams from coronal holes. It has been mainly explored with the ground-based neutron monitor network, which indirectly measures the integrated intensities of all species of cosmic rays by counting secondary neutrons produced from interaction between atmospheric atoms and cosmic rays. The space-based experiments can resolve the species of particles but the energy ranges are limited by the relatively small acceptances except for the most abundant particles like protons and helium. Therefore, the FD of cosmic-ray electrons and positrons have just been investigated by the PAMELA experiment in the low-energy range (<5 GeV) with limited statistics. In this paper, we study the FD event that occurred in 2017 September with the electron and positron data recorded by the Dark Matter Particle Explorer. The evolution of the FDs from 2 GeV to 20 GeV with a time resolution of 6 hr are given. We observe two solar energetic particle events in the time profile of the intensity of cosmic rays, the earlier, and weaker, one has not been shown in the neutron monitor data. Furthermore, both the amplitude and recovery time of fluxes of electrons and positrons show clear energy dependence, which is important in probing the disturbances of the interplanetary environment by the coronal mass ejections
Runoff of arid and semi-arid regions simulated and projected by CLM-DTVGM and its multi-scale fluctuations as revealed by EEMD analysis
Production of doubly-charged baryon in annihilation at energies from 2.3094 to 2.6464 GeV
The processes and
are studied for the first
time with of annihilation data collected with
the BESIII detector at center-of-mass energies from GeV to
GeV. No significant signal for the
process is observed and the upper limit of the Born cross section is estimated
at each energy point. For the process , a significant signal is observed at center-of-mass energies
near 2.6454 GeV and the corresponding Born cross section is reported.Comment: 10 pages, 4 figure
Search for an axion-like particle in radiative decays
We search for an axion-like particle (ALP) through the process
, ,
in a data sample with
events collected by the BESIII detector. No significant ALP signal
is observed over the expected background, and the upper limits on the branching
fraction of the decay and the ALP-photon coupling
constant are set at the 95\% confidence level in the mass
range of 0.165\leq m_a\leq2.84\,\mbox{GeV}/c^2. The limits on
range from to
over the search region, and the constraints on the
ALP-photon coupling are the most stringent to date for 0.165\leq
m_a\leq1.468\,\mbox{GeV}/c^2.Comment: 10 pages, 5 figure
- …