4,584 research outputs found
Modeling the Light Curves of the Luminous Type Ic Supernova 2007D
SN~2007D is a nearby (redshift ), luminous Type Ic supernova
(SN) having a narrow light curve (LC) and high peak luminosity. Previous
research based on the assumption that it was powered by the Ni cascade
decay suggested that the inferred Ni mass and the ejecta mass are M and M, respectively. In this paper, we
employ some multiband LC models to model the -band LC and the color ()
evolution of SN~2007D to investigate the possible energy sources powering them.
We find that the pure Ni model is disfavored; the multiband LCs of
SN~2007D can be reproduced by a magnetar whose initial rotational period
and magnetic field strength are (or
) ms and (or
) G, respectively. By comparing the
spectrum of SN~2007D with that of some superluminous SNe (SLSNe), we find that
it might be a luminous SN like several luminous ``gap-filler" optical
transients that bridge ordinary and SLSNe, rather than a genuine SLSN.Comment: 11 pages, 5 figures, 1 table, accepted for publication in Ap
Modeling the Light Curves of the Luminous Type Ic Supernova 2007D
SN 2007D is a nearby (redshift z = 0.023146), luminous Type Ic supernova (SN) having a narrow light curve (LC) and high peak luminosity. Previous research based on the assumption that it was powered by the 56Ni cascade decay suggested that the inferred 56Ni mass and the ejecta mass are ~1.5 M ⊙ and ~3.5 M ⊙, respectively. In this paper, we employ some multiband LC models to model the R-band LC and the color (V − R) evolution of SN 2007D to investigate the possible energy sources powering them. We find that the pure 56Ni model is disfavored; the multiband LCs of SN 2007D can be reproduced by a magnetar whose initial rotational period P 0 and magnetic field strength B p are (or ) ms and (or ) G, respectively. By comparing the spectrum of SN 2007D with that of some superluminous SNe (SLSNe), we find that it might be a luminous SN like several luminous gap-filler optical transients that bridge ordinary and SLSNe, rather than a genuine SLSN
Triply charmed baryons mass decomposition from lattice QCD
We present the first lattice QCD calculation about the mass decomposition of
triply charmed baryons with as and .
The quark mass term contributes about 66\% to the mass
of state, which is slightly lower than that of the meson system
with the same valence charm quark. Furthermore, based on our results, the total
contribution of sea quarks, the gluons and the QCD anomaly accounts for about a
quarter of the mass of these two triply charmed baryons. The mass difference of
and states is mainly from the quark energy
of the QCD energy-momentum tensor. For comparison, the
mass splitting is also calculated under the framework of the constituent quark
model.Comment: 7 page, 14 figure
Experimental Research on Foamed Mixture Lightweight Soil Mixed with Fly-Ash and Quicklime as Backfill Material behind Abutments of Expressway Bridge
To promote the utilization of fly-ash, based on the orthogonal experiment method, wet density and unconfined compressive strength of Foamed Mixture Lightweight Soil mixed with fly-ash and quicklime (FMLSF) are studied. It is shown that the wet density and unconfined compressive strength of FMLSF increase with the increase of cement content, while decreasing with the increase of foam content. With the mixing content of fly-ash increase, the wet density and unconfined compressive strength of FMLSF increase firstly and then decrease. Scanning Electron Microscope (SEM) tests show that ball effect or microaggregate effect of fly-ash improves the wet density and unconfined compressive strength of FMLSF. With the mixing content of quicklime increase, the wet density and unconfined compressive strength of FMLSF increase firstly within a narrow range and then decrease. In addition, the primary and secondary influence order on wet density and 28-day compressive strength of FMLSF are obtained, as well as the optimal mixture combination. Finally, based on two abutments in China, behind which they are filled with FMLSF and Foamed Mixture Lightweight Soil (FMLS), the construction techniques and key points of quality control behind abutment are compared and discussed in detail, and the feasibility of utilization fly-ash as FMLSF is verified by the experimental results
The diagnostic value of elastography and ultrasound contrast in papillary thyroid microcarcinoma
目的 评估弹性成像与超声造影(CEUS)两种检查技术对鉴别诊断甲状腺微小乳头状癌(TMC)的价值。方法 对常规超声检测出且定性困难的73例80个甲状腺微小结节进行弹性成像及CEUS检查,所有结节均经手术病理证实。比较两种检查方法的准确性。结果 80个结节中CEUS诊断正确率为85.0%(68/80),其中6例TMC误诊为良性病变,6例良性结节误诊为TMC;弹性成像5分法诊断正确率为92.5%(74/80),其中3例TMC误诊为良性结节,3例良性结节误诊为TMC。性成像诊断甲状腺微小癌的敏感性94.0%,特异性90.0%,准确性92.5%;CEUS诊断甲状腺微小癌的敏感性88.0%,特异性80.0%,准确性85.0%。结论 CEUS和弹性成像对于诊断TMC方面均有价值,但弹性评分≥3作为诊断TMC的敏感性、特异性及准确性均高于CEUS。Objective: To assess the value of elastic imaging and CEUS two inspection techniques for differential diagnosis of thyroid papillary carcinoma (TMC). Method: To do elastic imaging and CEUS checks to 73 cases of 80 thyroid nodules which was tested by conventional ultrasonic and difficult to quantify. All nodules were confirmed by surgery and pathologic examination. Comparing the accuracy of both detection methods. Result: Of the 80 nodules, the accuracy of CEUS diagnosis was 85.0%(68/80), of which 6 cases were misdiagnosed as benign lesions, and 6cases of benign nodules were misdiagnosed as TMC: the accuracy of 5-point scale criteria of elastography was 92.5%(74/80), of which 3 TMC were misdiagnosed as benign nodules: and 3 benign nodules were misdiagnosed as TMC. The application of elastography in the diagnosis of thyroid microcarcinoma displayed a sensitivity of 94.0%, a specificity of 90.0% and an accuracy of 92.5%. Elastography detection was more advantagerous than CEUS in the diagnosis of thyroid microcarcinoma, and compared to CEUS , the differences were statistically significant(P <0.05).Conclusion: Elastography and Ultrasound Contrast have highly practical value to diagnosis of TMC. The sensitivity specificity and accuracy of using elastic score ≥3 as criteria of diagnosis of TMC was higher than that of CEUS
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