4,751 research outputs found
Universality of Zipf's Law
We introduce a simple and generic model that reproduces Zipf's law. By
regarding the time evolution of the model as a random walk in the logarithmic
scale, we explain theoretically why this model reproduces Zipf's law. The
explanation shows that the behavior of the model is very robust and universal.Comment: 5 eps files included. To be published in J. Phys. Soc. Jp
All-optical transport and compression of ytterbium atoms into the surface of a solid immersion lens
We present an all-optical method to load 174Yb atoms into a single layer of
an optical trap near the surface of a solid immersion lens which improves the
numerical aperture of a microscope system. Atoms are transported to a region 20
um below the surface using a system comprised by three optical dipole traps.
The "optical accordion" technique is used to create a condensate and compress
the atoms to a width of 120 nm and a distance of 1.8 um away from the surface.
Moreover, we are able to verify that after compression the condensate behaves
as a two-dimensional quantum gas.Comment: 5 pages, 5 figure
Anomalous behavior of the energy gap in the one-dimensional quantum XY model
We re-examine the well-studied one dimensional spin-1/2 model to reveal
its nontrivial energy spectrum, in particular the energy gap between the ground
state and the first excited state. In the case of the isotropic model --
the model -- the gap behaves very irregularly as a function of the system
size at a second order transition point. This is in stark contrast to the usual
power-law decay of the gap and is reminiscent of the similar behavior at the
first order phase transition in the infinite-range quantum model. The gap
also shows nontrivial oscillatory behavior for the phase transitions in the
anisotropic model in the incommensurate phase. We observe a close relation
between this anomalous behavior of the gap and the correlation functions. These
results, those for the isotropic case in particular, are important from the
viewpoint of quantum annealing where the efficiency of computation is strongly
affected by the size dependence of the energy gap.Comment: 25 pages, 8 figures. arXiv admin note: substantial text overlap with
arXiv:1501.0292
Complete mitochondrial DNA sequence of the parasitic honey bee mite Varroa destructor (Mesostigmata : Varroidae)
Varroa destructor is a parasite mite of the eastern honey bee Apis cerana, which is native to Asia. The European honey bee Apis mellifera was imported to Asia from Europe and the USA for apiculture in the 19th century. In a short period of time, V. destructor parasitized the artificially introduced honey bees. Varroa destructor was estimated to have spread around the world with A. mellifera when it was exported from Asia to locations worldwide about 50 years ago. The mitochondrial DNA of the parasitic honey bee mite V. destructor was analyzed using next-generation sequencing. The complete mitochondrial genome of V. destructor was identified as a 16,476-bp circular molecule containing 13 protein-coding genes (PCGs), 22 tRNA genes, two rRNA genes, and one AT-rich control region. The heavy strand was predicted to have nine PCGs and 13 tRNA genes, whereas the light strand was predicted to contain four PCGs, nine tRNA genes, and two rRNA genes. All PCGs began with ATA as the start codon, except COIII and CytB, which had ATG as the start codon. Stop codons were of two types: TAA for eight genes and TAG for five genes. Molecular phylogenetic analysis revealed that V. destructor from Japan was genetically distant from that of France. A high base substitution rate of 2.82% was also confirmed between the complete mitochondrial DNA sequences of V. destructor from Japan and the USA, suggesting that one Varroa mite strain found in the USA is not from Japan
B field and squeezed states in Vacuum String Field Theory
We show that squeezed state solutions for solitonic lumps in Vacuum String
Field Theory still exist in the presence of a constant B field. We show in
particular that, just as in the B=0 case, we can write down a compact explicit
form for such solutions.Comment: 15 pages, Latex, typos corrected, final versio
't Hooft Expansion of 1/2 BPS Wilson Loop
We revisit the 't Hooft expansion of 1/2 BPS circular Wilson loop in N=4 SYM
studied by Drukker and Gross in hep-th/0010274. We find an interesting
recursion relation which relates different number of holes on the worldsheet.
We also argue that we can turn on the string coupling by applying a certain
integral transformation to the planar result.Comment: 21 pages; v2: minor correction
Zeeman Spectroscopy of the Star Algebra
We solve the problem of finding all eigenvalues and eigenvectors of the
Neumann matrix of the matter sector of open bosonic string field theory,
including the zero modes, and switching on a background B-field. We give the
discrete eigenvalues as roots of transcendental equations, and we give
analytical expressions for all the eigenvectors.Comment: (1, 25) pages, 2 Figure
Luminescent Polymer Electrolyte Composites Using Silica Coated-Y2O3:Eu as Fillers
Luminescent polymer electrolyte composites composed of silica coated Y2O3:Eu in polyethylene glycol (PEG) matrix has been produced by initially synthesizing silica coated Y2O3:Eu and mixing with polyethylene glycol in a lithium salt solution. High luminescence intensity at round 600 nm contributed by electron transitions in Eu3+ (5D0 → 7F0, 5D0 → 7F1, and 5D0 → 7F3 transitions) were observed. The measured electrical conductivity was comparable to that reported for polymer electrolyte composites prepared using passive fillers (non luminescent). This approach is therefore promising for production of high intensity luminescent polymer electrolyte composites for use in development of hybrid battery/display
Zinc Oxide Nanoparticles Prepared by a Simple Heating: Effect of Polymer Addition and Polymer Absence on the Morphology
Zinc oxide (ZnO) nanoparticles were prepared by a simple heating of precursors in a furnace at temperatures of below 1000°C in an air environment. If zinc nitrate was used as precursor, polymer (e.g., polyethylene glycol (PEG)) must be added into the precursor to produce ZnO in nanometer size. The absence of polymer led to the presence of several micrometer-sized flakes. In addition, the heating temperatures must be higher than 500°C to completely decompose the organic material in final product. However, if zinc acetate was used as precursor, nanometer-sized ZnO having a high crystallinity can be obtained even when the polymer was absent. Interestingly, we also found that heating at low temperatures (e.g. 400°C) resulted in ZnO nanorods with an elongation ratio of around 5. This method is rapid, economically efficient, and readily scalable for industrial applications
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