Effects of child support and welfare policies on nonmarital teenage childbearing and motherhood

This paper is an assessment of the impact of child support enforcement and welfare policies on nonmarital teenage childbearing and motherhood. We derive four hypotheses about the effects of policies on nonmarital teenage childbearing and motherhood. We propose that teenage motherhood and school enrollment are joint decisions for teenage girls. Based on individual trajectories during ages 12–19, our analysis uses an event history model for nonmarital teenage childbearing and a dynamic model of motherhood that is jointly determined with school enrollment. We find some evidence that child support policies indirectly reduce teen motherhood by increasing the probability of school enrollment, which, in turn, reduces the probability of teen motherhood. This finding suggests that welfare offices may wish to place greater weight on outreach programs that inform more teenagers of the existence of strong child support enforcement measures. Such programs might reduce nonmarital teen motherhood further and thus reduce the need for welfare support and child support enforcement in the long run.

标志审美意象中“似与不似”的物态化属性

标志的审美意象是一种审美的体验与意会,它是以物态化的视觉形式形成意象审美的沟通与心领神会。在标志审美意象的物态化中,各类审美形态大都以"似与不似"或"似此似彼"的表现形式体现出独特的、具有创造性的审美特征,因而,"象"的"似与不似"在标志的审美意象中体现的极为明显,成为其特有的属性。以中国古典艺术创作理论中的"形"与"神"的关系、"虚实相生"、"惊奇感"等美学思想,融合西方美学的"距离说"理论,探讨在标志设计中对审美意象创作的形态构建与分寸把握,提出只有摒弃过于"似"与过于"不似",才能做到标志的"形神兼备""形神相合""虚实相生"并进而达到其视觉传达效果的完美体现;对现代标志艺术设计中的审美意象创造作出一定意义上的理论阐释,揭示其"似与不似"这一物态化的基本特征与创作规律。     

我国地方决策-执行体制的法治透视

在目前依法治国的大环境下,我国地方行政体制改革的启动及运行还存在诸多问题。地方决策-执行体制过于行政化,地方决策执行前各方参与度不高,地方对决策-执行体制改革的主动法治观念也不强。基于此,就有必要创建多层次、有区别的＂决策-执行体制＂,力推民主化、科学化的执行前机制,及时以法治原则来规范地方执行体制的改革。     

从符号学视角看博客情境下的符号互动

博客的出现,给人们提供了表达自我的一个虚拟的网络情境。语言文字是人们表达自我的基本工具,也是人们在交流中使用的基本符号。以符号学作为视角来考察博客,这个交流情境其实是"姿态"缺失的符号的集合体。其中,语言文字是最基本的符号,它在博客中的使用有自身的特性。通过语言文字,人们能够实现表达"自我"的目的。博客最显著的特性是互动性。这种互动,是通过语言文字来实现的,同时,语言文字互动也完成了人的"自我"的实现。     

Uniqueness of equilibria in atomic splittable polymatroid congestion games

We study uniqueness of Nash equilibria in atomic splittable congestion games and derive a uniqueness result based on polymatroid theory: when the strategy space of every player is a bidirectional flow polymatroid, then equilibria are unique. Bidirectional flow polymatroids are introduced as a subclass of polymatroids possessing certain exchange properties. We show that important cases such as base orderable matroids can be recovered as a special case of bidirectional flow polymatroids. On the other hand we show that matroidal set systems are in some sense necessary to guarantee uniqueness of equilibria: for every atomic splittable congestion game with at least three players and non-matroidal set systems per player, there is an isomorphic game having multiple equilibria. Our results leave a gap between base orderable matroids and general matroids for which we do not know whether equilibria are unique.     

Optimization problems with color-induced budget constraints

In 1984, Gabow and Tarjan provided a very elegant and fast algorithm for the following problem: given a matroid defined on a red and blue colored ground set, determine a basis of minimum cost among those with k red elements, or decide that no such basis exists. In this paper, we investigate extensions of this problem from ordinary matroids to the more general notion of poset matroids which take precedence constraints on the ground set into account. We show that the problem on general poset matroids becomes -hard, already if the underlying partially ordered set (poset) consists of binary trees of height two. On the positive side, we present two algorithms: a pseudopolynomial one for integer polymatroids, i.e., the case where the poset consists of disjoint chains, and a polynomial algorithm for the problem to determine a minimum cost ideal of size l with k red elements, i.e., the uniform rank-l poset matroid, on series-parallel posets.     

Approximation strategy-proof mechanisms for obnoxious facility location on a line

In the facility location game on a line, there are some agents who have fixed locations on the line where an obnoxious facility will be placed. The objective is to maximize the social welfare, e.g., the sum of distances from the facility to all agents. On collecting location information, agents may misreport the locations so as to stay far away from the obnoxious facility. In this paper, strategy-proof mechanisms are designed and the approximation ratio is used to measure the performances of the strategy-proof mechanisms. Two objective functions, maximizing the sum of squares of distances (maxSOS) and maximizing the sum of distances (maxSum), have been considered. For maxSOS, a randomized 5/3-approximated strategy-proof mechanism is proposed, and the lower bound of the approximation ratio is proved to be at least 1.042. For maxSum, the lower bound of the approximation ratio of the randomized strategy-proof mechanism is proved to be 1.077. Moreover, a general model is considered that each agent may have multiple locations on the line. For the objective functions maxSum and maxSOS, both deterministic and randomized strategy-proof mechanisms are investigated, and the deterministic mechanisms are shown to be best possible.     

Asymptotically optimal policy for stochastic job shop scheduling problem to minimize makespan

This paper studies the large-scale stochastic job shop scheduling problem with general number of similar jobs, where the processing times of the same step are independently drawn from a known probability distribution, and the objective is to minimize the makespan. For the stochastic problem, we introduce the fluid relaxation of its deterministic counterpart, and define a fluid schedule for the fluid relaxation. By tracking the fluid schedule, a policy is proposed for the stochastic job shop scheduling problem. The expected value of the gap between the solution produced by the policy and the optimal solution is proved to be O(1), which indicates the policy is asymptotically optimal in expectation.     

A quadratic time exact algorithm for continuous connected 2-facility location problem in trees

This paper studies the continuous connected 2-facility location problem (CC2FLP) in trees. Let \(T = (V, E, c, d, \ell , \mu )\) be an undirected rooted tree, where each node \(v \in V\) has a weight \(d(v) \ge 0\) denoting the demand amount of v as well as a weight \(\ell (v) \ge 0\) denoting the cost of opening a facility at v, and each edge \(e \in E\) has a weight \(c(e) \ge 0\) denoting the cost on e and is associated with a function \(\mu (e,t) \ge 0\) denoting the cost of opening a facility at a point x(e, t) on e where t is a continuous variable on e. Given a subset \(\mathcal {D} \subseteq V\) of clients, and a subset \(\mathcal {F} \subseteq \mathcal {P}(T)\) of continuum points admitting facilities where \(\mathcal {P}(T)\) is the set of all the points on edges of T, when two facilities are installed at a pair of continuum points \(x_1\) and \(x_2\) in \(\mathcal {F}\), the total cost involved in CC2FLP includes three parts: the cost of opening two facilities at \(x_1\) and \(x_2\), K times the cost of connecting \(x_1\) and \(x_2\), and the cost of all the clients in \(\mathcal {D}\) connecting to some facility. The objective is to open two facilities at a pair of continuum points in \(\mathcal {F}\) to minimize the total cost, for a given input parameter \(K \ge 1\). This paper focuses on the case of \(\mathcal {D} = V\) and \(\mathcal {F} = \mathcal {P}(T)\). We first study the discrete version of CC2FLP, named the discrete connected 2-facility location problem (DC2FLP), where two facilities are restricted to the nodes of T, and devise a quadratic time edge-splitting algorithm for DC2FLP. Furthermore, we prove that CC2FLP is almost equivalent to DC2FLP in trees, and develop a quadratic time exact algorithm based on the edge-splitting algorithm. Finally, we adapt our algorithms to the general case of \(\mathcal {D} \subseteq V\) and \(\mathcal {F} \subseteq \mathcal {P}(T)\).     

Performance management change in archaeological sites: The case of Herculaneum Conservation Project

This study focuses on the issues relating to the implementation of management accounting systems in complex settings such as archeological sites. The aim is to understand the conditions under which the implementation of performance management systems (PMS) may enable cultural organizations to fulfil their multiple objectives and the factors which play a crucial role in such dynamics. Focusing on the Herculaneum Conservation Project (HCP) the study explains how PMS came to be implemented having been made acceptable to all parties involved. The Middle Range Theory as developed by Broadbent and Laughlin (Accounting control and controlling accounting: interdisciplinary and critical perspectives, Bingley, Emerald, 2013) was utilized to explore how the PMS change took place in the HCP, and focus on the factors influencing this process. The findings reveal that the change in the PMS benefited from the involvement of a multidisciplinary Specialist Work Group. This involvement reduced the natural tendency to resist the forces of change and increased the commitment of the various groups of stakeholders to the new culture. The findings reveal how PMS were developed in the context of a multifaceted approach to change, allowing us to draw both theoretical and practical lessons that may be brought to bear in other complex contexts.