An improved approximation algorithm for uncapacitated facility location problem with penalties

In this paper, we consider an interesting variant of the classical facility location problem called uncapacitated facility location problem with penalties (UFLWP for short) in which each client is either assigned to an opened facility or rejected by paying a penalty. The UFLWP problem has been effectively used to model the facility location problem with outliers. Three constant approximation algorithms have been obtained (Charikar et al. in Proceedings of the Symposium on Discrete Algorithms, pp. 642–651, 2001; Jain et al. in J. ACM 50(6):795–824, 2003; Xu and Xu in Inf. Process. Lett. 94(3):119–123, 2005), and the best known performance ratio is 2. The only known hardness result is a 1.463-inapproximability result inherited from the uncapacitated facility location problem (Guha and Khuller in J. Algorithms 31(1):228–248, 1999). In this paper, We present a 1.8526-approximation algorithm for the UFLWP problem. Our algorithm significantly reduces the gap between known performance ratio and the inapproximability result. Our algorithm first enhances the primal-dual method for the UFLWP problem (Charikar et al. in Proceedings of the Symposium on Discrete Algorithms, pp. 642–651, 2001) so that outliers can be recognized more efficiently, and then applies a local search heuristic (Charikar and Guha in Proceedings of the 39th IEEE Symposium on Foundations of Computer Science, pp. 378–388, 1999) to further reduce the cost for serving those non-rejected clients. Our algorithm is simple and can be easily implemented. The research of this work was supported in part by NSF through CAREER award CCF-0546509 and grant IIS-0713489. A preliminary version of this paper appeared in the Proceedings of the 11th Annual International Computing and Combinatorics Conference (COCOON’05).     

The Effect of Graduate School on Identity Issues

Abstract

Objectives: To provide a critical review of the efficacy of brief interventions for alcohol use in college health centers. Methods: Studies were included if (a) they examined brief intervention trials that were conducted in college- or university-based student health centers or emergency departments, and (b) they provided pre–post data to estimate change. Results: Twelve studies suggested that screening and brief interventions in these settings are acceptable, feasible, and promote risk reduction. Conclusions: Findings support continued use of time-limited, single-session interventions with motivational interviewing and feedback components.     

Indoor Tanning and Problem Behavior

Objective: The authors examined factors predicting college students' use of tanning beds. Participants and Methods: Undergraduate students (N = 745) at a large Northeastern university participated in the study by answering a survey measuring tanning behavior and other psychosocial variables, including sensation seeking, self-esteem, tanning image beliefs, and friends' tanning bed use. Results: All 3 systems from problem behavior theory predicted past tanning bed use and intention to use tanning beds. The authors observed a positive association between sensation seeking and intention to use tanning beds. Tanning image beliefs were positively associated with both past tanning behavior and intention to use tanning beds. Conclusions: Interventions focusing on friend and acquaintance social network influences may be more effective than health-risk campaigns in reducing tanning bed use.     

高校党风廉政建设的问题与对策——基于巡视监督的理性思考

加强巡视监督,在改变高校"一把手"弱监状况、改变"高校体制内"监督状况、改变高校"被动型"监督状况、改变高校"滞后性"监督状况、助力高校"自主性"监督状况中具有不可替代性。巡视视角下高校党风廉政建设存在的突出问题表现在四个方面:在基建和采购方面的腐败易高发,在招生用人方面的腐败难规避,在资金运营方面的问题较严重,在各种评比中存在的腐败最痛心。高校巡视工作对于高校党风廉政建设和各项事业的科学发展有积极作用,但高校党风廉政建设还必须倚重于其自廉的意识和能力。     

“农超对接”中的委托代理问题研究——以农产品质量安全为例

基于委托代理理论,针对“农超对接”中超市为确保农户提供高质量安全农产品,对农户实施参与和激励约束的问题,建立模型并利用库恩—塔克条件进行分析。结果表明：以超市为主导的“农超对接”模式中,若要满足农户参与和激励约束,则超市收购高质量安全农产品与其他采购商收购低质量非安全农产品的价格差额,加之超市对农户种植农产品的单位投资补贴之和,应该等于农户种植高低质量两类农产品的单位成本差额;同时若农产品质量检测不合格对农户施加的边际惩罚额应等于超市进行质量安全检测的边际成本。并据此提出建议,为保障我国农产品质量安全,进一步推广和实施“农超对接”提供参考依据。     

论拜占廷帝国科穆宁制度的历史作用

科穆宁制度是1081年阿莱克修斯上台后建立的以皇帝为中心、以皇帝的家族为统治基础的政治制度。这一制度确立了皇帝家族和军事贵族的统治地位,建立起庞大的皇帝家族对非皇帝家族的绝对优势,为科穆宁王朝前三位皇帝提供了坚实的统治支柱,使他们加强了中央集权,恢复并保持了对贵族、官僚政治、军队和君士坦丁堡民众的控制,最终遏制了11世纪以来十分严重的贵族叛乱和阴谋活动,为拜占廷帝国在1081—1180年出现的百年繁荣局面奠定了基础。     

新创小微型企业劳动生产率的增长因素与空间特征--基于“新”新经济地理学视角的研究

空间选择效应是“新”新经济地理学解析区域生产率差异微观机理的基本理论之一。本文研究结果表明：人均物质资本和企业家人力资本水平对新创小微型企业劳动生产率增长具有显著的正向影响;新创小微型企业的区位选择呈现出“核心区-平均劳动生产率高、边缘区-平均劳动生产率低”的空间分布特征,对小微型企业的区域扶持政策应兼顾增长与效率两种目标,应推行对小微型企业固定资产投资补贴政策,重视区域小微型企业公共服务系建设。     

认知视角下英语学习者听力问题研究

听力理解是一个繁杂而积极的过程,在语言学习中听力起着重要的作用.但由于听力自身的特点,听力研究曾一度被忽视,而学生的听力问题更是没有得到重视.本研究运用Anderson的听力过程三阶段模式,从认知视角探索学生在听力过程中所面临的问题与困难.40名来自内蒙古工业大学的大学一年级学生参与本研究.本研究采用学生日记及采访的方式收集数据.研究结果表明:学生在听力过程中存在的主要问题有8类.在听力过程的三个阶段,学生存在的问题较多的是在接收信息阶段.因此教师在听力教学过程中要注重听力信息接收阶段学生存在的问题,采用不同的教学方法更好地帮助学生提高听力理解能力.     

贵州城镇化问题研究

城镇化是指一个国家或地区由传统的农业社会向现代城市社会发展的自然历史过程,农村人口向城镇迁移的过程,是这一过程中经济社会结构发展变革并获得巨大发展的空间表现。贵州城镇化面临城镇化水平低、城镇综合承载力低、城镇化体制矛盾突出等问题。通过加强规划的引领,促进城市群发展,实施“五个100工程”等举措,贵州城镇化建设一定能取得长足的进步。     

嫖宿幼女罪的法理思考

案例分析发现嫖宿幼女罪判处的刑罚一般来说比强奸罪重.因此,反对嫖宿幼女罪的民众认为该罪比强奸罪判处的刑罚更轻的观点是不成立的.嫖宿幼女罪所存在的问题是逻辑上的,该罪无法回答未满14周岁的幼女究竟有没有同意性交的能力.此外,嫖宿幼女罪会遗漏不明知对方未满14周岁的行为人.解决办法是认可14周岁以下的幼女无论在何种情况下,都没有同意性交的能力,行为人与之发生性关系都构成强奸罪.