23 research outputs found
Color Superconducting Phases of Cold Dense Quark Matter
We investigate color superconducting phases of cold quark matter at densities
relevant for the interiors of compact stars. At these densities, electrically
neutral and weak-equilibrated quark matter can have unequal numbers of up,
down, and strange quarks. The QCD interaction favors Cooper pairs that are
antisymmetric in color and in flavor, and a crystalline color superconducting
phase can occur which accommodates pairing between flavors with unequal number
densities. In the crystalline color superconductor, quarks of different flavor
form Cooper pairs with nonzero total momentum, yielding a condensate that
varies in space like a sum of plane waves. Rotational and translational
symmetry are spontaneously broken. We use a Ginzburg-Landau method to evaluate
candidate crystal structures and predict that the favored structure is
face-centered-cubic. We predict a robust crystalline phase with gaps comparable
in magnitude to those of the color-flavor-locked phase that occurs when the
flavor number densities are equal. Crystalline color superconductivity will be
a generic feature of the QCD phase diagram, occurring wherever quark matter
that is not color-flavor locked is to be found. If a very large flavor
asymmetry forbids even the crystalline state, single-flavor pairing will occur;
we investigate this and other spin-one color superconductors in a survey of
generic color, flavor, and spin pairing channels. Our predictions for the
crystalline phase may be tested in an ultracold gas of fermionic atoms, where a
similar crystalline superfluid state can occur. If a layer of crystalline quark
matter occurs inside of a compact star, it could pin rotational vortices,
leading to observable pulsar glitches.Comment: Ph.D. thesis, submitted to the MIT Department of Physics, May 2003.
Five chapters and two appendices (180 pages, 30 figures). Chapters 1 and 5
are new: chapter 1 is a detailed review of previous work, and chapter 5
discusses applications of the crystalline phase for the physics of pulsar
spin glitches and cold trapped atom
Impacts of cross-phase modulation on modulation instability of Airy pulses
<p>The modulation instability (MI) of Airy pulses with the influence of cross-phase modulation is studied based on the coupled nonlinear Schrödinger equations in nonlinear media. The main lobe of Airy pulses can be manifested as breakup of MI under interaction with higher power pumped solitons, although the power of Airy pulses is small. By comparing the main lobe’s gain spectrum of MI, the gain spectrum has gradually improved with the increase of power of pumped solitons. The gain spectrum of MI of the main lobe is inversely proportional to the truncation coefficient, and then it gradually approaches to that of Gauss pulses with the truncation coefficient increasing to 1. For the side lobes of Airy pulses, there are similar MI but smaller gain spectrum than the main lobe when the pumped solitons is overlapping with corresponding ones of Airy pulses.</p
Binary detection in ghost imaging with preserved grayscale
Traditional imaging of grayscale object generally demands multiple bits detection, in this paper, ghost imaging for grayscale object based on binary detection is investigated, and our results demonstrate that binary ghost imaging is enough to reconstruct the grayscale objects. With only binary signals, a little difference between binary and ordinary ghost imaging can be found when reconstructing the object with lower grayscale value, however, for the grayscale object with higher value, binary ghost imaging almostly achieves the same results to ordinary ghost imaging. Under extreme cases, the image of a grayscale object can be obtained by using the binary detector according to the characteristics of ghost imaging
Phylogenetic Analysis of ALV-J Associated with Immune Responses in Yellow Chicken Flocks in South China
The aim of this study was to better understand the sequence characteristics and immune responses in avian leukosis virus subgroup J (ALV-J) infected yellow chicken flocks in South China. We isolated four strains of ALV-J virus from these flocks, which were then identified by several methods, including subtype-specific polymerase chain reaction (PCR), enzyme-linked immunosorbent assay (ELISA), and immunofluorescence assay (IFA). All four viruses were sequenced for their complete genomes and named GD19GZ01, GD19GZ02, GD19GZ03, and GD19GZ04. In comparison with the reference sequence, the homology analysis showed that the gag and pol genes were relatively conserved, whereas env contained much variation. Both GD19GZ01 and GD19GZ02 almost entirely lacked the rTM region and E element, while the latter was retained in GD19GZ03 and GD19GZ04. Moreover, the virus replication levels in GD19GZ03 and GD19GZ04were much higher than those in GD19GZ01 and GD19GZ02. And three virus recombination events in GD19GZ01 and GD19GZ02 were revealed by the results of PDR5 and SimPlot software analysis. Additionally, we found that some interferon-stimulating genes (CH25H, MX, PKR, OAS, and ZAP) and inflammatory mediators (IL-4, IL-6, IL-10, IL-12, 1L-18, and TNF-α) were significantly upregulated in the immune system organs of clinical chickens. Taken together, these findings clarify and reveal the sequence characteristics and trends in the variation of ALV-J infection in yellow chicken flocks of South China
Research on Multipath Correlated Imaging with the Grayscale Target in Endoscopic Applications
The application of correlated imaging in endoscope, one of the research hotspots, may lead to multipath effect in the closed endoscopic environment. The model of multipath correlated imaging with a grayscale object is given, where the mismatch ratio and the reflection ratio are two key factors affecting imaging quality. The theoretical and experimental results show that multipath effect has an influence on the grayscale distribution and imaging quality of the reconstructed image, and the effect of the mismatch ratio is stronger than that of the reflection ratio. The conditions that the disturbance from multipath effect can be ignored in endoscopic applications are given
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Vertical Structures of Typical Meiyu Precipitation Events Retrieved From GPM‐DPR
This work for the first time analyzed the vertical structures of the different stages of Meiyu precipitation systems over the Yangtze-Huai River Valley in central China using measurements and retrievals from the Global Precipitation Measurement Mission Dual-Frequency Precipitation Radar (GPM-DPR) and Feng Yun satellites. GPM-DPR-retrieved near-surface rain and drop size distributions were first validated against the surface disdrometer measurements and showed good agreement. Then we analyzed three cases from the Integrative Monsoon Frontal Rainfall Experiment to demonstrate the different characteristics of convective precipitation and stratiform precipitation (SP) in the developing, mature, and dissipating stages of the Meiyu precipitation systems, respectively. For statistical analysis, all Meiyu cases during the period 2016-2018 detected by GPM-DPR were collected and classified into different types and stages. In the stratiform regions of Meiyu precipitation systems, coalescence slightly overwhelms breakup and/or evaporation processes, but it was dominant in the convective regions when raindrops fall. There were large numbers of large ice particles during the developing stage due to strong updrafts and abundant moisture, whereas there were both large ice and liquid particles in the mature stage. The vertical structures of the SP examined in this study were similar to those over the ocean regions due to high relative humidity but different to the mountainous west regions of the USA. The findings of the stage-dependent SP vertical structures provide better understanding of the evolution of monsoon frontal precipitation, as well as the associated microphysical properties, and provide insights to improve microphysical parameterization in future models.6 month embargo; published online: 18 December 2019This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]
Graphene Oxide: A Perfect Material for Spatial Light Modulation Based on Plasma Channels
The graphene oxide (GO) is successfully prepared from a purified natural graphite through a pressurized oxidation method. We experimentally demonstrate that GO as an optical media can be used for spatial light modulation based on plasma channels induced by femtosecond pulses. The modulated beam exhibits good propagation properties in free space. It is easy to realize the spatial modulation on the probe beam at a high concentration of GO dispersion solutions, high power and smaller pulse width of the pump beam. We also find that the spatial modulation on the probe beam can be conveniently adjusted through the power and pulse width of pump lasers, dispersion solution concentration
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Statistical Characteristics of Raindrop Size Distributions and Parameters in Central China During the Meiyu Seasons
The rain parameters derived from the laser OTT second-generation Particle Size Velocity (Parsivel(2)), the two-dimensional video disdrometer (2DVD), and DZZ5 tipping-bucket rain gauge (RG) during the Integrative Monsoon Frontal Rainfall Experiment (IMFRE) in summer 2018 are compared. The total rainfall amounts observed by Parsivel, 2DVD, and RG during IMFRE were 178.07, 176.76, and 182.5 mm, while their total rainy hours were 113, 113, and 90. The meanD(m)(mass-weighted mean diameter) andLWC(liquid water content) values derived from Parsivel and 2DVD were 1.03 and 1.01 mm and 0.247 and 0.223 g m(-3). The rainy samples from six Parsivel sites over the middle reaches of the Yangtze River during the 2016-2018 Meiyu seasons have been collected and analyzed. The occurrence frequencies for rain rates (RR) 10 mm hr(-1)were 83.9% and 7.4%, respectively, but they contributed 30.5% and 52.1% of the total accumulated rainfall. Compared with the results over the lower reaches of the Yangtze River, the total accumulated rainfall percentages forRR RR > 10 mm hr(-1)observed at XN site were higher and lower, respectively. The stratiform rain (SR) raindrop size increases withRRover both the middle and lower reaches, whereas theN(w)values over the middle reaches are much higher. Opposite to the SR results, the convective rain (CR) raindrops from this study are larger, while theirN(w)values are similar to one another. For gamma-type-size distribution, the mu - lambda andZ - Rrelations are strongly dependent on geographical location.National Key Research and Development Program of China6 month embargo; first published online 17 September 2020This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]