4,638 research outputs found
Correlation-hole induced paired quantum Hall states in lowest Landau level
A theory is developed for the paired even-denominator fractional quantum Hall
states in the lowest Landau level. We show that electrons bind to quantized
vortices to form composite fermions, interacting through an exact instantaneous
interaction that favors chiral p-wave pairing. Two canonically dual pairing gap
functions are related by the bosonic Laughlin wavefunction (Jastraw factor) due
to the correlation holes. We find that the ground state is the Moore-Read
pfaffian in the long wavelength limit for weak Coulomb interactions, a new
pfaffian of an oscillatory pairing function for intermediate interactions, and
a Read-Rezayi composite Fermi liquid beyond a critical interaction strength.
Our findings are consistent with recent experimental observations of the 1/2
and 1/4 fractional quantum Hall effects in asymmetric wide quantum wells.Comment: 4 pages, 2 figures; published versio
Citizen Science for Post-disaster Sustainable Community Development in Ecologically Fragile Regions - A Case from China
The world’s mountains host some of the most complex, dynamic, and diverse ecosystems and are also hotspots for natural disasters, such as earthquake, landslide and flood. One factor that limits the mountain communities to recover from disasters and pursue sustainable development is the lack of locally relevant scientific knowledge, which is hard to gain from global and regional scale observations and models. The rapid advances in ICT, computing, communication technologies and the emergence of citizen science is changing the situation. Here we report a case from Sichuan Giant Panda Sanctuary World Natural Heritage in China on the application of citizen science in a community reconstruction project. Dahe, a mountainous community (ca. 8000 ha in size) is located covering part of the World Heritage’s core and buffer zones, with an elevation range of 1000-3000 meters. The community suffered from two major earthquakes of 7.9 and 6.9 Mw in 2008 and 2013 respectively. Landslides and flooding threat the community and significantly limit their livelihood options. We integrated participatory disaster risk mapping (e.g., community vulnerability and capacity assessment) and mobile assisted natural hazards and natural resources mapping (e.g., using free APP GeoODK) into more conventional community reconstruction and livelihood building activities. We showed that better decisions are made based on results from these activities and local residents have a high level of buy-in in these new knowledge. We suggest that initiatives like this, if successfully scale-up, can also help generate much needed data and knowledge in similar less-developed and data deficient regions of the world
Star Formation Across the Taffy Bridge: UGC 12914/15
We present BIMA two-field mosaic CO(1-0) images of the Taffy galaxies (UGC
12914/15), which show the distinct taffy-like radio continuum emission bridging
the two spiral disks. Large amounts of molecular gas (1.4 x 10^{10} Msun, using
the standard Galactic CO-to-H conversion applicable to Galactic disk giant
molecular clouds [GMCs]) were clearly detected throughout the taffy bridge
between the two galaxies, which, as in the more extreme case of HI, presumably
results from a head-on collision between the two galaxies. The highest CO
concentration between the two galaxies corresponds to the H_alpha source in the
taffy bridge near the intruder galaxy UGC 12915. This HII region is also
associated with the strongest source of radio continuum in the bridge, and
shows both morphological and kinematic connections to UGC 12915. The overall CO
distribution of the entire system agrees well with that of the radio continuum
emission, particularly in the taffy bridge. This argues for the star formation
origin of a significant portion of the radio continuum emission. Compared to
the HI morphology and kinematics, which are strongly distorted owing to the
high-speed collision, CO better defines the orbital geometry and impact
parameter of the interaction, as well as the disk properties (e.g., rotation,
orientation) of the progenitor galaxies. Based on the 20cm-to-CO ratio maps, we
conclude that the starburst sites are primarily located in UGC 12915 and the
H_alpha source in the bridge and show that the molecular gas in the taffy
bridge is forming into stars with star formation efficiency comparable to that
of the target galaxy UGC 12914 and similar to that in the Galactic disk.Comment: Minor typo/style corrections to match with the published version (AJ,
Nov. issue). A single .ps.gz file of the entire paper can be downloaded from
http://spider.ipac.caltech.edu/staff/gao/Taffy/all.ps.g
Influence of Grassland Management on Carbon Allocation in a Semiarid Temperate Steppe
Grazing lands in North China are often excessively grazed and widely degraded, while hay-making lands appear to be in relatively good condition due to grazing exclusion, but they are facing a continuous loss of nutrients in the harvested biomass. In semiarid grasslands, plant productivity and community composition are significantly altered by grazing and haying. Grazing mostly leads to negative effects on aboveground productivity, however root biomass seems to increase with moderate grazing (Gao et al. 2009; Derner et al. 2006), although responses can vary. Aboveground biomass removal can increase C3 grass dominance and productivity (Hofer and Bragg 1981). Grazing exclusion is a valuable mechanism of sequestering soil C (He 2008). However, grazing can change C allocation patterns and affect the amount of C entering the soil. Here we examine the potential effects of common management practices (exclusion with fencing, grazing and hay-making) on semiarid grasslands above- and below-ground C pools. The primary objective of this study was to evaluate the potential of grazing exclusion and annual last-summer haying in previous grazing lands on the storage of C in semiarid grasslands of northern China
Hybrid shrinking projection method for a generalized equilibrium problem, a maximal monotone operator and a countable family of relatively nonexpansive mappings
AbstractThe purpose of this paper is to introduce and consider a hybrid shrinking projection method for finding a common element of the set EP of solutions of a generalized equilibrium problem, the set ⋂n=0∞F(Sn) of common fixed points of a countable family of relatively nonexpansive mappings {Sn}n=0∞ and the set T−10 of zeros of a maximal monotone operator T in a uniformly smooth and uniformly convex Banach space. It is proven that under appropriate conditions, the sequence generated by the hybrid shrinking projection method, converges strongly to some point in EP∩T−10∩(⋂n=0∞F(Sn)). This new result represents the improvement, complement and development of the previously known ones in the literature
Entanglement detection via condition of quantum correlation
We develop a novel necessary condition of quantum correlation. It is utilized
to construct -level bipartite Bell-type inequality which is strongly
resistant to noise and requires only analyses of measurement outcomes
compared to the previous result . Remarkably, a connection between
the arbitrary high-dimensional bipartite Bell-type inequality and entanglement
witnesses is found. Through the necessary condition of quantum correlation, we
propose that the witness operators to detect truly multipartite entanglement
for a generalized Greenberger-Horne-Zeilinger (GHZ) state with two local
measurement settings and a four-qubit singlet state with three settings.
Moreover, we also propose the first robust entanglement witness to detect
four-level tripartite GHZ state with only two local measurement settings
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