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关键词： 命名实体识别   网络安全   边界检测   深度学习   自然语言处理  

摘要： 网络安全实体识别作为威胁信息抽取、构建知识图谱的基础，对于发现和应对网络威胁具有至关重要的作用。该文针对当前主流的命名实体识别方法在网络安全领域泛化能力欠佳、难以清晰判断网络安全实体边界的问题，提出一种基于字符表示学习与时序边界扩散的网络安全实体识别方法。该方法首先将命名实体识别任务分解为实体边界检测与实体分类两个子任务，分别进行处理;其次，对于实体边界检测任务，使用基于问答的方法将预定义的问题与数据进行编码，采用膨胀卷积残差字符网络进行数据的字符级特征提取，并使用时序边界扩散网络判断实体边界;然后，对于实体分类任务，同样使用问答方法，并独立训练分类器进行实体类型判断;最后将实体边界检测任务的结果输入实体分类任务判断实体的类型。为验证方法有效性，在网络威胁情报数据集DNRTI上进行测试。实验结果表明，边界检测效率的提升能够有效增强命名实体识别的性能。该方法在网络安全实体识别任务中不仅资源开销较小，且对比近年提出的基线方法性能有所提升，其中较最近两年的方法在F1分数上提升了0.40%～1.65%。

关键词： catalogs   binaries: close   binaries: eclipsing   binaries: spectroscopic   binaries: visual  

摘要： Context. A former analysis of eclipse timing variation (ETV) curves of eclipsing binaries (EBs) observed by the Kepler spacecraft during its similar to 4-year-long prime mission has led to the discovery and characterization of 221 hierarchical triple star system with different confidence levels. Although the prime Kepler mission ended in 2013 (a little more than a decade ago), the TESS space telescope has revisited the original Kepler field on several occasions in between 2019 and 2024, thereby extending the time base of high-precision eclipse timing observations for a substantially longer interval. Aims. In this paper, we re-analyse the extended ETV curves of the formerly identified triple star candidates and many other Kepler EBs. Besides the confirmations of the former findings and/or the improvements of the triple systems' orbital properties, the extended time base allows us to identify several new, longer outer period triple systems, and it also makes a more detailed study of the dynamical perturbations in the tightest triple stars possible. Methods. We extend the ETV curves of the Kepler triples with those mid-eclipse times that can be deduced from the TESS observations and, moreover, from targeted ground-based follow-up observations for a number of the objects. In general, we used the same methods that were applied for the older studies, which are described in the literature. Due to the lower quality of the TESS observations, however, for the fainter systems we averaged light curves of the EBs for 5-20 consecutive cycles, and thereby calculated 'normal' minima from these averaged light curves. Results. In conclusion, we identified 243 hierarchical triple star candidates in the Kepler sample. This sample strongly overlaps our former, nine-year-old sample, confirming the older results, or providing new solutions for 193 systems of the 2016 sample. For the remaining 28 hierarchical triple candidates of that former study, we have been unable to find new solutions

关键词： 乙型肝炎病毒   慢性感染者   肝脏硬度   肝纤维化   队列研究  

摘要： 目的 监测甘肃省武威市慢性乙型肝炎病毒(hepatitis B virus,HBV)感染者肝脏硬度动态变化与临床指标的相关性,为早期发现并有效干预肝纤维化(liver fibrosis,LF)进程提供科学依据.方法 基于武威乙肝专病队列,对3 882例慢性HBV感染者进行每年一次血清学及FibroScan超声检查,经过平均4年随访,监测LF转归情况并通过构建Logistic回归模型分析其影响因素.结果 在完成至少1次随访的2 053例慢性HBV感染者中,基线LF等级F0～F4分别有1 581例(77.0%)、164例(8.0%)、99例(4.8%)、110例(5.4%)和99例(4.8%),五组间年龄、性别、吸烟、抗病毒治疗、肝功指标、控制衰减指数(control attenuation index,CAP)、肝脏硬度值(liver stiffness measurement,LSM)差异有统计学意义(P<0.05).经过平均4年随访,1 686例(17.9/100人年)LF等级无明显改变,260例(2.8/100人年)LF等级降低,107例(1.1/100人年)LF等级升高.按照基线治疗状态分组后,在未采取治疗的慢性HBV感染者中基线谷丙转氨酶(alanine aminotransferase,ALT)(OR=5.50,95%CI:1.79～16.83,P=0.003)和LSM(OR=3.35,95%CI:1.23～9.13,P=0.018)是LF进展的危险因素;而在抗病毒治疗的感染者中LF进展的危险因素则是基线谷草转氨酶(aspartate aminotransferase,AST)(OR=2.23,95%CI:1.41～3.53,P<0.001)和总胆红素(total bilirubin,TBIL)(OR=1.79,95%CI:1.14～2.81,P=0.012)水平.结论 LSM和肝功指标(ALT、AST和TBIL)是肝纤维化进展的重要影响因素,LSM和肝功指标的监测将对于肝硬化预防与早期诊断有重要意义.

关键词： techniques: photometric   planets and satellites: atmospheres   planets and satellites: terrestrial planets  

摘要： Context. M-dwarf systems offer an opportunity to study terrestrial exoplanetary atmospheres due to their small size and cool temperatures. However, the extreme conditions imposed by these host stars raise a question about whether their close-in rocky planets are able to retain any atmosphere at all. Aims. The Hot Rocks Survey aims to answer this question by targeting nine different M-dwarf rocky planets spanning a range of planetary and stellar properties. Of these, LHS 1478 b orbits an M3-type star, has an equilibrium temperature of T-eq = 585 K, and receives 21 times Earth's instellation. Methods. We observed two secondary eclipses of LHS 1478 b using photometric imaging at 15 mu m using the Mid-Infrared Instrument on the James Webb Space Telescope (JWST MIRI) to measure thermal emission from the dayside of the planet. We compared these values to atmospheric models to evaluate potential heat transport and CO2 absorption signatures. Results. We find that a secondary eclipse depth of 138 +/- 53 ppm at the expected time for a circular orbit is preferred over a null model at 2.8 sigma, a moderate detection, though dynamical models do favour a non-eccentric orbit for this planet. The second observation results in a non-detection due to significantly larger unexplained systematics. Based on the first observation alone, we can reject the null hypothesis of the dark (zero Bond albedo) no atmosphere bare rock model with a confidence level of 3.3 sigma, though for A(B) = 0.2 the significance decreases to 2.1 sigma. The tentative secondary eclipse depth is consistent with the majority of the atmospheric scenarios we considered, spanning CO2-rich atmospheres with surface pressures from 0.1 to 10 bar. However, we stress that the two observations from our programme do not yield consistent results, and more observations are needed to verify our findings. The Hot Rocks Survey serves as a relevant primer for future endeavours such as the Director's Discretionary Time (DDT) Rocky W

摘要： 2024年第12期的《算法世界》栏目介绍了选择排序算法,它和下面要介绍的冒泡排序算法原理类似,都是和排序有关的算法.排序是计算机处理工作时经常做的一项工作,据统计,计算机约有25％的工作时间花在排序上.排序如此重要,所以人们发明了各种排序的算法.

摘要： "二次根式"新题总动员 1.D 2.B 3.C 4.C 5.B 6.B 7.B 8.A 9.A 10.x＞1 11.＞12.1 13.√314.-2√3 15.2(或 3)16.1 17.(1)3(2)2 18.2(答案不唯一)19.210(())ab=√5+1/2×√5-1/2=1则a=1/***=n/1+an+ n/1+1/an=n.S1+S2+…+S20=1+2+…+20=210)

关键词： 胎儿心脏定量   超声心动图   胎儿   心脏形态   心脏功能  

摘要： 目的探讨胎儿心脏定量（fetal heart quantification，Fetal HQ）技术评估正常胎儿心脏形态与功能的价值。方法本研究为前瞻性队列研究，纳入2023年1月至2024年10月在湖南省人民医院接受产前超声检查的胎儿正常的健康孕妇。应用GE Voluson E10彩色多普勒超声诊断仪行常规产科超声检查和胎儿超声心动图检查，评估胎儿生长发育情况，排除心内心外畸形；采集四腔心切面（four-chamber view，4CV）清晰显示心内膜的心脏动态图（时间≥3 s），应用Fetal HQ软件进行在机斑点跟踪分析，测量指标包括心脏整体球形指数（global spherical index，GSI）、心脏舒张末期长径（end-diastolic length of the heart，L-ED）与横径（end-diastolic width of the heart，W-ED）以及左心室（left ventricle，LV）、右心室（right ventricle，RV）的整体纵向应变（global longitudinal strain，GLS）、面积变化率（fractional area change，FAC）和24节段球形指数（spherical index，SI）。按产前超声检查孕周分为孕20+0～23周+6、24+0～27周+6、28+0～31周+6、32+0～35周+6和36+0～40周+6组。采用单因素方差分析、两独立样本t检验、单因素线性回归分析和Pearson相关性分析探讨上述指标在不同孕周组之间的差异及其与孕周的相关性。结果共200例孕妇纳入队列，剔除4例（因图像质量欠佳无法准确描迹获得相关指标），余196例（孕20+0～23周+6组40例、24+0～27周+6组34例、28+0～31周+6组41例、32+0～35周+6组48例、36+0～40周+6组33例）的图像纳入分析，图像分析成功率为98.0%（196/200）。（1）4CV L-ED、4CV W-ED、LV-FAC和RV-FAC在孕20+0～23周+6、24+0～27周+6、28+0～31周+6、32+0～35周+6、36+0～40周+6组间差异均有统计学意义［4CV L-ED：28.0±3.0、32.6±4.3、40.9±4.3、46.7±4.8、53.1±5.8，F=3.72；4CV W-ED：21.9±1.8、25.1±4.2、31.7±3.0、37.4±4.0、42.0±4.9，F=2.61；LV-FAC：（51.4±8.0）%、（49.0±10.4）%、（47.3±7.3）%、（43.1±7.5）%、（40.7±8.2）%，F=2.94；RV-FAC：（49.9±10.8）%、（46.2±12.0）%、（46.3±8.3）%、（43.2±8.0）%、（41.9±5.6）%，F=3.09；P值均<0.05］。（2）正常胎儿心脏大小随孕周增加逐渐增大，心脏形态保持相对稳定（4CV L-ED和4CV W-ED与孕周呈正相关，回归系数分别为1.313和1.325，P值均<0.001；LV-FAC和RV-FAC与孕周呈负相关，回归系数分别为－0.783和－0.552，P值均<0.001；GSI、LV-GLS和RV-GLS与孕周无相关性，P值均>0.05）。（3）LV节段1～17的SI均高于RV相应节段的SI，RV节段20～24的SI均高于LV相应节段的SI（P值均<0.001）。结论Fetal HQ在胎儿心脏形态与功能的评估中具有一定价值。