Discovering classes in microarray data using island counts

We present a new biclustering algorithm to simultaneously discover tissue classes and identify a set of genes that well-characterize these classes from DNA microarray data sets. We employ a combinatorial optimization approach where the object is to simultaneously identify an interesting set of genes and a partition of the array samples that optimizes a certain score based on a novel color island statistic. While this optimization problem is NP-complete in general, we are effectively able to solve problems of interest to optimality using a branch-and-bound algorithm. We have tested the algorithm on a 30 sample Cutaneous T-cell Lymphoma data set; it was able to almost perfectly discriminate short-term survivors from long-term survivors and normal controls. Another useful feature of our method is that can easily handle missing expression data.     

Letters to the editor

Relatively little attention has been paid to the use and importance of labels used by men who have sex with men to describe insertive or receptive sexual behavior during intercourse. This study examines sexual self‐labels, sexual behavior, HIV transmission risk, and psychological functioning among 205 HIV‐seropositive men who have sex with men. The majority of participants (88%) identified as a “top, “ a “bottom, “ or “versatile. “ Tops were more likely to engage in insertive anal intercourse than bottoms, and bottoms were more likely to engage in receptive anal intercourse than tops, with versatiles reporting intermediate rates of both behaviors. Although the results suggest preliminary evidence regarding the predictive utility of self‐labels, sexual behaviors of self‐label groups were greatly overlapping. Differences were found among self‐label groups in gay self‐identification, internalized homophobia, sexual sensation seeking, and anxiety. Results suggest an added value in assessing self‐labels in addition to asking about sexual behavior.     

The duration of unemployment in Russia

This paper uses longitudinal survey data to assess factors affecting the duration of unemployment in Russia. We examine four types of marginalised labour force participants, according to ILO guidelines and survey responses, and we estimate duration models for each type. It turns out that the sets of characteristics with the strongest effects on the duration are remarkably similar across the different unemployment definitions and model specifications. Therefore, despite the formidable practical measurement problems, problematic groups of individuals can actually be identified. Received: 27 January 1999/Accepted: 27 January 2000     

The Devil is in the Detail: Clinicians,Academics and Researchers Resolving the Problems of Clinical Research

The difficulties associated with conducting valid family therapy research within a clinical practice discourage many potential researchers. This article will describe collaboration between a group of academics, researchers and clinicians who decided to explore the process and efficacy of systemic family therapy conducted within a working private practice. The specific questions we are addressing are, whether the requests clients bring to their first session of therapy can be reliably classified by practitioners, whether these requests change over time, and whether the nature of the request is associated with therapist and client ratings of therapeutic outcome. Additional questions about the form and nature of the therapeutic alliance as experienced by both client and practitioner are also being explored. This paper will map the passage of the work from inception to its current state where over 140 clients are active participants. In doing so attention will be paid to the obstacles encountered: practical, financial and ethical, and the solutions devised to address these.     

Going most of the way: “Technical virginity” among American adolescents

Reports from academic and media sources assert that many young people substitute non-vaginal sexual activities for vaginal intercourse in order to maintain what could be called “technical virginity.” Explanations for technical virginity, however, are based on weak empirical evidence and considerable speculation. Using a sample of 15–19-year-olds from Cycle 6 of the National Survey of Family Growth, we examine technical virginity and its motivations. The results suggest that religious adolescents are less likely than less-religious ones to opt for non-vaginal sex over total abstinence. Abstinence pledgers who are virgins are neither more nor less likely than nonpledgers who are virgins to substitute non-vaginal sex for intercourse. Moreover, religion and morality are actually the weakest motivators of sexual substitution among adolescents who have not had vaginal sex. Preserving technical virginity is instead more common among virgins who are driven by a desire to avoid potential life-altering consequences, like pregnancy and sexually transmitted diseases.     

The Economic Partnership Agreements: Rationale,Misperceptions and Non‐trade Aspects

The European Union and the African, Caribbean and Pacific (ACP) countries entered a new era in 2008. The Cotonou trade regime and the WTO waiver legitimising it have expired, and the long anticipated, and much debated, move to Economic Partnership Agreements (EPAs) has begun. This article explains the background and analyses the ‘alternatives’ to EPAs, in order to tackle common misperceptions. Moving on from what has been the focus of debates, namely, the reciprocal liberalisation required under WTO rules, it sheds some light on the non‐goods trade aspects of EPAs which, while integral to economic policy, are inherently hard to quantify and often skimmed over in existing studies or addressed in ideological terms.