Inapproximability and approximability of maximal tree routing and coloring

Let G be a undirected connected graph. Given g groups each being a subset of V(G) and a number of colors, we consider how to find a subgroup of subsets such that there exists a tree interconnecting all vertices in each subset and all trees can be colored properly with given colors (no two trees sharing a common edge receive the same color); the objective is to maximize the number of subsets in the subgroup. This problem arises from the application of multicast communication in all optical networks. In this paper, we first obtain an explicit lower bound on the approximability of this problem and prove Ω(g^1−ε)-inapproximability even when G is a mesh. We then propose a simple greedy algorithm that achieves performance ratio O√|E(G)|, which matches the theoretical bounds. Supported in part by the NSF of China under Grant No. 70221001 and 60373012.     

江苏省基层医务人员工作压力研究

对905名基层医务人员进行问卷调查,了解基层医务人员工作压力情况及其影响因素,为建立适合基层卫生机构的良性人才发展机制提供依据。基层医务人员整体工作压力得分为56.54分;单因素方差分析显示,不同性别、年龄、婚姻状况、学历、职称、机构类型、工作量、工作年数、受患者尊重程度和社会地位的医务人员工作压力得分差异具有统计学意义;多元线性回归分析结果显示,社会地位、工作量、工作年数、受患者尊重程度、最高学历和性别对基层医务人员工作压力的影响具有统计学意义。需要着重关注乡镇卫生院医生的工作压力情况,重点应放在提升基层医务人员社会地位、及时关注中坚力量等方面,从而减轻其工作压力,提高工作积极性。     

南充市城区已婚育龄妇女二孩生育意愿研究

2018年4—5月在四川省南充市城区采用便利抽样,以已婚且未育或已育一个小孩的育龄妇女为研究对象,采用自制匿名问卷,以面对面的形式收集资料,了解实施全面二孩政策后南充市育龄妇女的生育意愿,为南充市的人口研究提供参考依据。在213名调查对象中,56人(26.3%)有二孩生育意愿,140人(65.7%)无二孩生育意愿,17人(8.0%)不确定是否生育二孩。南充市被调查者的理想子女个数均值为1.46,意愿子女个数均值为1.27。不同文化程度(χ2=7.512)、配偶月收入(χ2=12.641)、理想子女数(χ2=66.401)、一孩性别(χ2=5.441)的育龄妇女间二孩生育意愿差异有统计学意义(P<0.05)。Logistic回归分析显示,第一个孩子性别为女孩(OR=2.641,P=0.021)、丈夫月收入越高(OR=1.761,P=0.028)、理想子女数多于1个(OR=29.040,P<0.001)的育龄妇女更有意愿生育二孩。南充市城区二孩生育意愿处于较低水平,经济收入、理想子女数、一孩性别会影响育龄妇女的二孩生育意愿。全面二孩政策对于促进育龄妇女生育二孩的效应有限,应当建立相关的配套政策,以促进全面二孩政策的实施。     

帕金森病患者住院费用相关因素分析

为分析并探讨帕金森病患者住院费用的影响因素,该研究选取2009年1月至2015年12月在南京医科大学第一附属医院帕金森病住院患者320例,其中接受脑深部电刺激器（DBS）置入手术患者37例,非手术患者283例,根据H&Y（Holehn &Yahr）分级、年龄以及合并感染情况等对住院费用及住院时间进行分析比较。结果发现,非手术组帕金森患者年龄、合并感染情况及H&Y分级与总住院费用及住院时间显著相关。接受DBS手术组患者住院费用较晚期非手术患者显著增高（t=7.40,P<0.001）。高龄、合并感染及帕金森病晚期增加非手术帕金森病患者住院费用和住院时间。     

On Combining Wavelets Expansion and Sparse Linear Models for Regression on Metabolomic Data and Biomarker Selection

Wavelet thresholding of spectra has to be handled with care when the spectra are the predictors of a regression problem. Indeed, a blind thresholding of the signal followed by a regression method often leads to deteriorated predictions. The scope of this article is to show that sparse regression methods, applied in the wavelet domain, perform an automatic thresholding: the most relevant wavelet coefficients are selected to optimize the prediction of a given target of interest. This approach can be seen as a joint thresholding designed for a predictive purpose. The method is illustrated on a real world problem where metabolomic data are linked to poison ingestion. This example proves the usefulness of wavelet expansion and the good behavior of sparse and regularized methods. A comparison study is performed between the two-steps approach (wavelet thresholding and regression) and the one-step approach (selection of wavelet coefficients with a sparse regression). The comparison includes two types of wavelet bases, various thresholding methods, and various regression methods and is evaluated by calculating prediction performances. Information about the location of the most important features on the spectra was also obtained and used to identify the most relevant metabolites involved in the mice poisoning.     

A Note on Selection and Gender Unemployment Gaps

Previous research has documented the impact of positive selection into employment on the ranking of countries by gender wage gaps. This note focuses on the impact of selection into labor force on cross-country differences in gender unemployment gaps. We construct the Manski bounds for the selection-free gender unemployment gaps in 26 EU countries and show that - without additional assumptions - the observed gender unemployment gaps carry little information about the selection-free gender differences in unemployment. Contrary to the common assumption of positive selection into labor force (similar to positive selection into employment documented in the gender wage gap research), we also point at an example of negative-selection bias. We show that labor force withdrawal of mothers on job-protected family leaves may lead to an overestimation of the selection-free gender unemployment gaps by as much as 1 p.p.     

Attenuating Initial Beliefs: Increasing the Acceptance of Anthropogenic Climate Change Information by Reflecting on Values

Anthropogenic climate change information tends to be interpreted against the backdrop of initial environmental beliefs, which can lead to some people being resistant toward the information. In this article (N = 88), we examined whether self‐affirmation via reflection on personally important values could attenuate the impact of initial beliefs on the acceptance of anthropogenic climate change evidence. Our findings showed that initial beliefs about the human impact on ecological stability influenced the acceptance of information only among nonaffirmed participants. Self‐affirmed participants who were initially resistant toward the information showed stronger beliefs in the existence of climate change risks and greater acknowledgment that individual efficacy has a role to play in reducing climate change risks than did their nonaffirmed counterparts.