30,351 research outputs found
Simulations of an energy dechirper based on dielectric lined waveguides
Terahertz frequency wakefields can be excited by ultra-short relativistic
electron bunches travelling through dielectric lined waveguide (DLW)
structures. These wakefields can either accelerate a witness bunch with high
gradient, or modulate the energy of the driving bunch. In this paper, we study
a passive dechirper based on the DLW to compensate the correlated energy spread
of the bunches accelerated by the laser plasma wakefield accelerator (LWFA). A
rectangular waveguide structure was employed taking advantage of its
continuously tunable gap during operation. The assumed 200 MeV driving bunch
had a Gaussian distribution with a bunch length of 3.0 {\mu}m, a relative
correlated energy spread of 1%, and a total charge of 10 pC. Both of the CST
Wakefield Solver and PIC Solver were used to simulate and optimize such a
dechirper. Effect of the time-dependent self-wake on the driving bunch was
analyzed in terms of the energy modulation and the transverse phase space
Spectroscopy of reflection-asymmetric nuclei with relativistic energy density functionals
Quadrupole and octupole deformation energy surfaces, low-energy excitation
spectra and transition rates in fourteen isotopic chains: Xe, Ba, Ce, Nd, Sm,
Gd, Rn, Ra, Th, U, Pu, Cm, Cf, and Fm, are systematically analyzed using a
theoretical framework based on a quadrupole-octupole collective Hamiltonian
(QOCH), with parameters determined by constrained reflection-asymmetric and
axially-symmetric relativistic mean-field calculations. The microscopic QOCH
model based on the PC-PK1 energy density functional and -interaction
pairing is shown to accurately describe the empirical trend of low-energy
quadrupole and octupole collective states, and predicted spectroscopic
properties are consistent with recent microscopic calculations based on both
relativistic and non-relativistic energy density functionals. Low-energy
negative-parity bands, average octupole deformations, and transition rates show
evidence for octupole collectivity in both mass regions, for which a
microscopic mechanism is discussed in terms of evolution of single-nucleon
orbitals with deformation.Comment: 36 pages, 21 figures, Accepted for Publication in Physical Review
Analytic Spectra of CMB Anisotropies and Polarization Generated by Relic Gravitational Waves with Modification due to Neutrino Free-Streaming
We present an analytical calculation of the spectra of CMB anisotropies and
polarizations generated by relic gravitational waves (RGWs). As a substantial
extension to the previous studies, three new ingredients are included in this
work. Firstly, the analytic and are given; especially the
latter can be useful to extract signal of RGWs from the observed data in the
zero multipole method. Secondly, a fitting formula of the decaying factor on
small scales is given, coming from the visibility function around the photon
decoupling. Thirdly, the impacts by the neutrino free-streaming (NFS) is
examined, a process that occurred in the early universe and leaves observable
imprints on CMB via RGWs.
It is found that the analytic and have profiles
agreeing with the numeric ones, except that in a range
and the trough of around have some deviations.
With the new damping factor, the analytic and match with
the numeric ones with the maximum errors only up to the first three
peaks for , improving the previous studies substantially. The
correspondence of the positions of peaks of and those of RGWs are
also demonstrated explicitly. We also find that NFS reduces the amplitudes of
by for and shifts slightly
their peaks to smaller angles. Detailed analyses show that the zero multipoles
, where crosses 0, are shifted to larger values by NFS. This
shifting effect is as important as those causedby different inflation models
and different baryon fractions.Comment: 17 pages, 7 figures. accepted by PR
Phylogeny-structured carbohydrate metabolism across microbiomes collected from different units in wastewater treatment process
With respect to global priority for bioenergy production from plant biomass, understanding the fundamental genetic associations underlying carbohydrate metabolisms is crucial for the development of effective biorefinery process. Compared with gut microbiome of ruminal animals and wood-feed insects, knowledge on carbohydrate metabolisms of engineered biosystems is limited.published_or_final_versio
Automatic detection of malignant prostatic gland units in cross-sectional microscopic images
Prostate cancer is the second most frequent cause of cancer deaths among men in the US. In the most reliable screening method, histological images from a biopsy are examined under a microscope by pathologists. In an early stage of prostate cancer, only relatively few gland units in a large region become malignant. Discovering such sparse malignant gland units using a microscope is a labor-intensive and error-prone task for pathologists. In this paper, we develop effective image segmentation and classification methods for automatic detection of malignant gland units in microscopic images. Both segmentation and classification methods are based on carefully designed feature descriptors, including color histograms and texton co-occurrence tables. © 2010 IEEE.published_or_final_versionThe 17th IEEE International Conference on Image Processing (ICIP 2010), Hong Kong, China, 26-29 September 2010. In Proceedings of the 17th ICIP, 2010, p. 1057-106
High resolution, low temperature photoabsorption cross-section of C2H2 with application to Saturn's atmosphere
New laboratory observations of the VUV absorption cross-section of C2H2, obtained under physical conditions approximating stratospheres of the giant planets, were combined with IUE observations of the albedo of Saturn, for which improved data reduction techniques have been used, to produce new models for that atmosphere. When the effects of C2H2 absorption are accounted for, additional absorption by other molecules is required. The best-fitting model also includes absorption by PH3, H2O, C2H6 and CH4. A small residual disagreement near 1600 A suggests that an additional trace species may be required to complete the model
Cellular adhesiveness and cellulolytic capacity in Anaerolineae revealed by omics-based genome interpretation
The Anaerolineae lineage of Chloroflexi had been identified as one of the core microbial populations in anaerobic digesters; however, the ecological role of the Anaerolineae remains uncertain due to the scarcity of isolates and annotated genome sequences. Our previous metatranscriptional analysis revealed this prevalent population that showed minimum involvement in the main pathways of cellulose hydrolysis and subsequent methanogenesis in the thermophilic cellulose fermentative consortium (TCF).published_or_final_versio
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