7,978 research outputs found
Nuclear symmetry potential in the relativistic impulse approximation
Using the relativistic impulse approximation with the Love-Franey \textsl{NN}
scattering amplitude developed by Murdock and Horowitz, we investigate the
low-energy (100 MeV MeV) behavior of the nucleon
Dirac optical potential, the Schr\"{o}dinger-equivalent potential, and the
nuclear symmetry potential in isospin asymmetric nuclear matter. We find that
the nuclear symmetry potential at fixed baryon density decreases with
increasing nucleon energy. In particular, the nuclear symmetry potential at
saturation density changes from positive to negative values at nucleon kinetic
energy of about 200 MeV. Furthermore,the obtained energy and density dependence
of the nuclear symmetry potential is consistent with those of the isospin- and
momentum-dependent MDI interaction with , which has been found to describe
reasonably both the isospin diffusion data from heavy-ion collisions and the
empirical neutron-skin thickness of Pb.Comment: 8 pages, 5 figures, revised version to appear in PR
ENAT-PT: An Enhanced NAT-PT Model
NAT-PT would allow IPv4 nodes to communicate with IPv6 nodes transparently by translating the IPv6 address into a registered V4 address. However, NAT-PT would fall flat when the pool of V4 addresses is exhausted. NAPT-PT multiplexes the registered address’ ports and will allow for a maximum of 63K outbound TCP and 63K UDP sessions per IPv4 address, but it is unidirectional. We present in this paper a novel solution ENAT-PT(an enhanced NAT-PT),which will allow for a great number of inbound sessions by using a single V4 address. By using ENAT-PT, we can visit V6 networks from a V4 network with a small address pool
Behavior patterns of online users and the effect on information filtering
Understanding the structure and evolution of web-based user-object bipartite
networks is an important task since they play a fundamental role in online
information filtering. In this paper, we focus on investigating the patterns of
online users' behavior and the effect on recommendation process. Empirical
analysis on the e-commercial systems show that users have significant taste
diversity and their interests for niche items highly overlap. Additionally,
recommendation process are investigated on both the real networks and the
reshuffled networks in which real users' behavior patterns can be gradually
destroyed. Our results shows that the performance of personalized
recommendation methods is strongly related to the real network structure.
Detail study on each item shows that recommendation accuracy for hot items is
almost maximum and quite robust to the reshuffling process. However, niche
items cannot be accurately recommended after removing users' behavior patterns.
Our work also is meaningful in practical sense since it reveals an effective
direction to improve the accuracy and the robustness of the existing
recommender systems.Comment: 8 pages, 6 figure
Degree heterogeneity in spatial networks with total cost constraint
Recently, In [Phys. Rev. Lett. 104, 018701 (2010)] the authors studied a
spatial network which is constructed from a regular lattice by adding
long-range edges (shortcuts) with probability ,
where is the Manhattan length of the long-range edges. The total
length of the additional edges is subject to a cost constraint ().
These networks have fixed optimal exponent for transportation
(measured by the average shortest-path length). However, we observe that the
degree in such spatial networks is homogenously distributed, which is far
different from real networks such as airline systems. In this paper, we propose
a method to introduce degree heterogeneity in spatial networks with total cost
constraint. Results show that with degree heterogeneity the optimal exponent
shifts to a smaller value and the average shortest-path length can further
decrease. Moreover, we consider the synchronization on the spatial networks and
related results are discussed. Our new model may better reproduce the features
of many real transportation systems.Comment: 4 pages, 4 figure
Abrupt climatic events recorded by the Ili loess during the last glaciation in Central Asia: Evidence from grain-size and minerals
The loess record of Central Asia provides an important archive of regional climate and environmental changes. In contrast to the widely investigated loess deposits in the Chinese Loess Plateau, Central Asian loess-paleosol sequences remain poorly understood. Here, we present an aeolian loess section in the southern Ili Basin. Based on granularity and mineralogical analyses, we reconstruct climatic changes during the last glaciation. The results indicated that most of the abrupt climatic events (such as Dansgaard-Oeschger events and Heinrich events) were imprinted in this loess section, although their amplitudes and ages showed some differences. Compared with the millennial oscillations recoded in loess and stalagmites in East Asia, the arid Central Asia responded more sensitively to the warming events than to the cooling events. The shifting trajectory of westerlies across Central Asia played an important role in dust deposition during the stadials. The North Atlantic climatic signals may have been transmitted from Central Asia to the East Asian monsoon regions via the westerlies
Dynamics on Spatial Networks and the Effect of Distance Coarse Graining
Very recently, a kind of spatial network constructed with power-law distance
distribution and total energy constriction is proposed. Moreover, it has been
pointed out that such spatial networks have the optimal exponents in
the power-law distance distribution for the average shortest path, traffic
dynamics and navigation. Because the distance is estimated approximately in
real world, we present an distance coarse graining procedure to generate the
binary spatial networks in this paper. We find that the distance coarse
graining procedure will result in the shifting of the optimal exponents
. Interestingly, when the network is large enough, the effect of
distance coarse graining can be ignored eventually. Additionally, we also study
some main dynamic processes including traffic dynamics, navigation,
synchronization and percolation on this spatial networks with coarse grained
distance. The results lead us to the enhancement of spatial networks'
specifical functions.Comment: 6 pages,6 figure
An efficient process for wastewater treatment to mitigate free nitrous acid generation and its inhibition on biological phosphorus removal
Free nitrous acid (FNA), which is the protonated form of nitrite and inevitably produced during biological nitrogen removal, has been demonstrated to strongly inhibit the activity of polyphosphate accumulating organisms (PAOs). Herein we reported an efficient process for wastewater treatment, i.e., the oxic/anoxic/oxic/extended-idle process to mitigate the generation of FNA and its inhibition on PAOs. The results showed that this new process enriched more PAOs which thereby achieved higher phosphorus removal efficiency than the conventional four-step (i.e., anaerobic/oxic/anoxic/oxic) biological nutrient removal process (41 ± 7% versus 30 ± 5% in abundance of PAOs and 97 ± 0.73% versus 82 ± 1.2% in efficiency of phosphorus removal). It was found that this new process increased pH value but decreased nitrite accumulation, resulting in the decreased FNA generation. Further experiments showed that the new process could alleviate the inhibition of FNA on the metabolisms of PAOs even under the same FNA concentration
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