利用二次谱盲估计多速率DS/CDMA伪码周期

针对可变扩频长度(VSL)的多速率DS/CDMA信号伪码周期的盲估计问题进行了研究,将一般单速率直扩信号二次功率谱伪码周期估计的方法扩展到多速率DS/CDMA模型。该方法首先将接收的多速率DS/CDMA信号进行采样,并对其求一次功率谱,再将一次谱作为输入信号作傅里叶变换并取模、平方,从而得到信号的二次功率谱。通过推导证明,多速率DS/CDMA信号的二次功率谱在扩频码周期的整数倍处出现尖锐的谱线,且不同速率用户的二次谱线幅度是不同的,利用这些幅度差异区分不同速率并通过估计谱线之间的距离即可获得不同速率信号的伪码周期。仿真表明该算法在低信噪比下适用,在-15 dB能够利用较少数据同时估计多组速率的伪码周期。     

Burden of illness associated with sinusoidal obstruction syndrome/veno-occlusive disease in patients with hematopoietic stem cell transplantation

Aims: Sinusoidal obstruction syndrome (SOS) is a life-threatening complication of hematopoietic stem cell transplantation (HSCT) associated with significant morbidity and mortality. Healthcare utilization, costs, and mortality were assessed in HSCT patients diagnosed with SOS, with and without multi-organ dysfunction (MOD).

Materials and methods: This retrospective observational study identified real-world patients undergoing HSCT between January 1, 2009 and May 31, 2014 using the Premier Healthcare Database. In absence of a formal ICD-9-CM diagnostic code, SOS patients were identified using a pre-specified definition adapted from Baltimore and Seattle criteria and clinical practice. Severe SOS (SOS/MOD) and non-severe SOS (SOS/no-MOD) were classified according to clinical evidence for MOD in the database.

Results: Of the 5,418 patients with a discharge diagnosis of HSCT, 291 had SOS, with 134 categorized as SOS/MOD and 157 as SOS/no-MOD. The remaining 5,127 patients had HSCT without SOS. Overall SOS incidence was 5.4%, with 46% having evidence of MOD. Distribution of age, gender, and race were similar between the SOS cohorts and non-SOS patients. After controlling for hospital profile and admission characteristics, demographics, and clinical characteristics, the adjusted mean LOS was 31.0 days in SOS/MOD compared to 23.9 days in the non-SOS cohort (medians?=?26.9 days vs 20.8 days, p?p?Limitations: Limitations of retrospective observational studies apply, since the study was not randomized. Definition for SOS was based on ICD-9 diagnosis codes from a hospital administrative database and reliant on completeness and accuracy of coding.

Conclusions: Analysis of real-world data shows that SOS/MOD is associated with significant increases in healthcare utilization, costs, and inpatient mortality.     

The Residency Discount for Rents in Germany and the Tenancy Law Reform Act 2001: Evidence from Quantile Regressions

Most countries show a residency discount in rents for sitting tenants. In the wake of strong rent increases and housing shortages, Germany implemented a reform in 2001 to curtail rent increases. Based on linked housing‐tenant data for Germany, this paper estimates panel OLS and quantile regressions of rents within tenancies. The results show that rents deflated by the CPI increase strongly from 1984 until the reform in 2001, and there is a reversal in the trend afterwards. Before the reform, there is a significant residence discount which decreases in absolute value with tenure. The reform reduces rents, in particular for expensive apartments and for new leases. There is no residency discount after the reform.     

基于自适应门限MDL方法的TDMA突发特征码检测

阐述了基于最小描述长度(MDL)方法来进行特征码检测,根据检测量分布的推导结果,提出了检测门限对检测性能、特征码位置不确定性和信噪比变化自适应的MDL特征码检测方法。当基于特征码进行通信信号分选时,新方法具有更好的应用灵活性,且检测性能对频偏具备鲁棒性。     

Do longer constitutions corrupt?

Tsebelis and Nardi (2016) and Tsebelis (2017) report that constitutional length correlates with lower levels of GDP per capita. They argue that this may be the case because longer constitutions lead to greater corruption. However, uncovering a causal relationship between constitutional length and corruption is difficult. On the one hand, political elites may pressure drafters to include specific provisions that facilitate their rent-seeking efforts. On the other hand, constitutional drafters may be responding to corruption by including a large number of specific safeguards. Our aim in this paper is to explore whether there is a causal effect of constitutional length on corruption. We utilize data from the Comparative Constitutions Project (CCP) to identify 5 cases when a country experienced a ≥50% increase in constitutional length. For each of those cases, we compare the subsequent change in corruption to that of a synthetic control. We report evidence of a significant post-treatment increase in corruption for 3 out of 5 cases (Ecuador in both 1997 and 2008; Venezuela in 1999). However, the 2008 Ecuador result is not robust to a placebo test; and in the case of Venezuela it is difficult to distinguish a constitutional length effect from a “Chavez effect” (Grier and Maynard 2016). The evidence that longer constitutions corrupt is weak.     

归零Turbo码参数的盲识别

针对归零Turbo码码率、码组起点、交织起点、交织长度参数识别问题，首先引入矩阵秩量比的概念，推导出适用于归零Turbo码矩阵秩量比下限，提出了基于秩量比判决门限的码长识别算法；其次，遍历一交织帧输出码元，找出最小秩量比对应的位置，实现交织起点和码组起点的识别；然后，依靠完整的交织帧输出数据，利用分析矩阵实现码率与分量编码器中寄存器个数识别；最后，由以上识别的参数计算出交织长度。仿真结果表明：在信噪比为5 dB时，单靠信息序列，各部分的识别概率能达到80%以上；在交织长度为100时，提出的识别算法与传统算法相比，性能相近，识别时间大约缩短为原来的1/3。     

Tracing the regional dual value chains: Measurement on the production position and evidence from China

When there is insufficient internal and external impetus for developing countries’ economy, building a domestic and international dual circulation is conducive to promoting the regional industrial growth. On the basis of regional embedded international input-output tables, this paper extends the measurement framework of production position and proposes the concept of the dual value chain, which measure production position that unifies the national and global value chains from forward and backward industrial linkages. We decompose the national and global value chains into three categories and investigate the production position characteristics of China with a multi-dimensional perspective. Consistent evidence shows that a feasible path of technological progress in optimizing the production in value chains in which technological progress plays a crucial role on the pure national value chain across the high-tech manufacturing sector, the eastern and central regions. Their posterior probabilities are 0.96, 0.21and 0.86, respectively. Moreover, the impact on the dual production is nonnegligible that the posterior probability of technological progress on the eastern and central regions is 0.40 and 0.92. In addition, the impact of the Chinese economic stimulus program and technological progress on the economic crisis has a certain moderating effect. Our proposed evaluation framework sheds new light that national value chain production can boost economic growth，and further promote the coordinated of regional industries for developing countries.     

沉管灌注桩冲击沉管成孔与振动拔管成桩一体化施工技术

在面对大直径、深桩长的沉管灌注桩施工时，现场选择分别使用固定在不同机架上的液压打桩锤沉管、振动锤拔管成桩工艺。使用该工艺进行沉管、拔管施工不连续，工序转换时间过长，现场难以管理。为更好提高沉管灌注桩施工效率，本文介绍了一种“沉管灌注桩冲击沉管成孔与振动拔管成桩一体化施工技术”，通过将液压冲击锤和弹簧振动锤集成在打桩架上进行沉管、拔管一体化施工，节省了工序转换及辅助作业时间和机械使用成本，达到便捷、高效、经济的效果。     

Survival Modelling for Data From Combined Cohorts: Opening the Door to Meta Survival Analyses and Survival Analysis Using Electronic Health Records

Non-parametric estimation of the survival function using observed failure time data depends on the underlying data generating mechanism, including the ways in which the data may be censored and/or truncated. For data arising from a single source or collected from a single cohort, a wide range of estimators have been proposed and compared in the literature. Often, however, it may be possible, and indeed advantageous, to combine and then analyse survival data that have been collected under different study designs. We review non-parametric survival analysis for data obtained by combining the most common types of cohort. We have two main goals: (i) to clarify the differences in the model assumptions and (ii) to provide a single lens through which some of the proposed estimators may be viewed. Our discussion is relevant to the meta-analysis of survival data obtained from different types of study, and to the modern era of electronic health records.     

The association between quarter length,forecast errors,and firms’ voluntary disclosures

Approximately 60 percent of adjacent fiscal quarters contain a different number of calendar days. In preliminary analyses, we find the change in quarter length is significantly associated with the changes in sales and earnings and that analysts condition on the prior quarter's results when making their forecasts. These results indicate that it is important for analysts to adjust for changes in quarter length when making forecasts. However, we find the quarterly change in days is positively associated with analysts’ sales and earnings forecasts errors, where forecast error equals the actual earnings minus the forecasted earnings. These results indicate that analysts systematically underestimate (overestimate) performance when quarter length increases (decreases). We find evidence indicating investors make similar errors as returns around earnings announcements are positively associated with the change in quarter length, but only when changes in firm performance is more sensitive to changes in quarter length. Corroborating these findings, managers are more (less) likely to discuss quarter length during conference calls when quarter length decreases (increases). These results are consistent with managers’ strategic disclosure incentives. In summary, our evidence suggests analysts and investors fail to fully take account of the quasi-mechanical effect that quarter length has on firm performance and managers strategically alter their voluntary disclosures to take advantage of these failures.