The Relationship Between Sexual Minority Verbal Harassment and Utilization of Health Services: Results from Countywide Risk Assessment Survey (CRAS) 2004

In this article we examine the prevalence of and associations between sexual orientation–based verbal harassment and reported utilization of health services across levels of sexual orientation in a diverse sample of adult recipients of Los Angeles County–funded HIV-related health and social services. Thirty-two percent reported they had experienced verbal harassment, the majority (80.3%) of whom identified as lesbian, gay, or bisexual (LGB). Those who reported being verbally harassed received significantly more services overall than those who were not verbally harassed, and service utilization varied by sexual orientation. These findings inform future efforts to identify and assess social discrimination in health and social service settings.     

Penalized spline joint models for longitudinal and time-to-event data

The joint models for longitudinal data and time-to-event data have recently received numerous attention in clinical and epidemiologic studies. Our interest is in modeling the relationship between event time outcomes and internal time-dependent covariates. In practice, the longitudinal responses often show non linear and fluctuated curves. Therefore, the main aim of this paper is to use penalized splines with a truncated polynomial basis to parameterize the non linear longitudinal process. Then, the linear mixed-effects model is applied to subject-specific curves and to control the smoothing. The association between the dropout process and longitudinal outcomes is modeled through a proportional hazard model. Two types of baseline risk functions are considered, namely a Gompertz distribution and a piecewise constant model. The resulting models are referred to as penalized spline joint models; an extension of the standard joint models. The expectation conditional maximization (ECM) algorithm is applied to estimate the parameters in the proposed models. To validate the proposed algorithm, extensive simulation studies were implemented followed by a case study. In summary, the penalized spline joint models provide a new approach for joint models that have improved the existing standard joint models.     

On Christensen's conjecture

In this paper we give solution to a conjecture appearing in Christensen (1997, p. 360) in relation to the definitions of standardized residuals in loglinear models. Work done when he was visiting as the Distinguished Lukacs Professor on leave from the Complutense University of Madrid. An erratum to this article is available at .     

Making Meanings,Meaning Identity: Hmong Adolescent Perceptions and Use of Language and Style as Identity Symbols

Using qualitative interview data gathered from 28 Hmong adolescents, we examined the meaning ascribed to language and style and how language and style behaviors are used to distinguish identity. We found that the participants used language and style to define their own ethnic group membership and cultural identities. Moreover they inferred meaning from these identity behaviors to discern which peer groups are desirable (those who wear American style clothing and are bilingual) and which are of low social status (“fobby” style clothing and monolingual). The cultural identity symbols used by participants reveal heterogeneity among Hmong adolescent peer groups and evolving definitions of what it means to be Hmong in America.     

Cutting Experimental Designs into Blocks

Most experimental material in agriculture and industry is heterogeneous in nature and therefore its statistical analysis benefits from blocking. Many experiments are restricted in time or space, and again blocking is useful. This paper adopts the idea of orthogonal blocking of Box & Hunter (1957) and applies it to optimal blocking designs. This approach is then compared with the determinant-based approach described in the literature for constructing block designs.     

Staying safe and visible via message sharing in online social networks

As an imperative channel for fast information propagation, online social networks (OSNs) also have their defects. One of them is the information leakage, i.e., information could be spread via OSNs to the users whom we are not willing to share with. Thus the problem of constructing a circle of trust to share information with as many friends as possible without further spreading it to unwanted targets has become a challenging research topic but still remained open. Our work is the first attempt to study the Maximum Circle of Trust problem seeking to share the information with the maximum expected number of poster’s friends such that the information spread to the unwanted targets is brought to its knees. First, we consider a special and more practical case with the two-hop information propagation and a single unwanted target. In this case, we show that this problem is NP-hard, which denies the existence of an exact polynomial-time algorithm. We thus propose a Fully Polynomial-Time Approximation Scheme (FPTAS), which can not only adjust any allowable performance error bound but also run in polynomial time with both the input size and allowed error. FPTAS is the best approximation solution one can ever wish for an NP-hard problem. We next consider the number of unwanted targets is bounded and prove that there does not exist an FPTAS in this case. Instead, we design a Polynomial-Time Approximation Scheme (PTAS) in which the allowable error can also be controlled. When the number of unwanted targets are not bounded, we provide a randomized algorithm, along with the analytical theoretical bound and inapproximaibility result. Finally, we consider a general case with many hops information propagation and further show its #P-hardness and propose an effective Iterative Circle of Trust Detection (ICTD) algorithm based on a novel greedy function. An extensive experiment on various real-world OSNs has validated the effectiveness of our proposed approximation and ICTD algorithms. Such an extensive experiment also highlights several important observations on information leakage which help to sharpen the security of OSNs in the future.     

Traditional vs. Modern Food Systems? Insights from Vegetable Supply Chains to Ho Chi Minh City (Vietnam)

This article describes the development of vegetable marketing in Ho Chi Minh City (Vietnam), where modern distribution outlets are competing fiercely with traditional traders for wholesale and retail customers. Data from interviews with supply chain stakeholders and a survey of vegetable wholesalers have been used to compare the performance of modern and traditional chains, and the findings reveal the chains as segmented in their product focus, the modern sector focusing exclusively on quality. Modern marketing channels are generally more efficient than traditional ones but still account for only around 2% of vegetable distribution. The article argues that policy‐makers should not promote the ‘modernisation’ of food systems at the expense of traditional channels which meet important consumer needs.