A quasi-Newton acceleration for high-dimensional optimization algorithms

In many statistical problems, maximum likelihood estimation by an EM or MM algorithm suffers from excruciatingly slow convergence. This tendency limits the application of these algorithms to modern high-dimensional problems in data mining, genomics, and imaging. Unfortunately, most existing acceleration techniques are ill-suited to complicated models involving large numbers of parameters. The squared iterative methods (SQUAREM) recently proposed by Varadhan and Roland constitute one notable exception. This paper presents a new quasi-Newton acceleration scheme that requires only modest increments in computation per iteration and overall storage and rivals or surpasses the performance of SQUAREM on several representative test problems.     

篇章、语篇、信息——系统功能语言学视角

"篇章"和"语篇"指的是同一种事物,只是看问题的角度不同。语篇分析就是把篇章跟语言的系统联系起来。作者认为,语篇有各种变体,语码变体跟语域、语类无关。文学语言的特殊性源于语法隐喻。从事语篇分析的学者都是从自己特定的角度出发的,如,批评话语分析、积极话语分析。很多意义是不能量化的,我们不仅要重视概念意义,也要重视人际意义。作者还论证了计算机对语篇分析、机器翻译的作用。     

今日美国社会学浅谈

美国的社会学大约自1900年起,方始作为一门独立的学科而存在。然而,它很快发展为一个复杂而又尚未定型的学术领域。美国社会学协会现有会员15,000人,其中4,000多人是学生。绝大部分职业社会学家依靠在美国各大专院校担任教学和从事研究工作为生,目前受聘于学术机关以外的工业、政府部门以及私人研究机构的趋势,正在上升。     

Semiparametric transformation models for multivariate panel count data with dependent observation process

This article discusses regression analysis of multivariate panel count data in which the observation process may contain relevant information about or be related to the underlying recurrent event processes of interest. Such data occur if a recurrent event study involves several related types of recurrent events and the observation scheme or process may be subject-specific. For the problem, a class of semiparametric transformation models is presented, which provides a great flexibility for modelling the effects of covariates on the recurrent event processes. For estimation of regression parameters, an estimating equation-based inference procedure is developed and the asymptotic properties of the resulting estimates are established. Also the proposed approach is evaluated by simulation studies and applied to the data arising from a skin cancer chemoprevention trial.     

Essential components of curricula for preparing therapists to work effectively with lesbian, gay, and bisexual clients: a Delphi study

The purpose of this study was to determine the knowledge, experiences, and values that therapists should possess to provide quality therapy services to lesbian, gay, and bisexual (LGB) persons and their families. Using the Delphi method, consensus from a panel of experts on LGB topics was obtained on the components that training curricula should ideally include to prepare therapists adequately to work with this population. Panelists provide suggestions for important therapist values and qualities, key theoretical orientations, common issues of LGB clients and their support persons, key components of assessment and interventions, ethical and legal issues, and recommended materials. The panelists stress self-of-the-therapist work and development of a systemic perspective as critical aspects of training. The role of sexuality was deemphasized. Recommendations to training programs based on these findings are provided.     

The role of faith in adoption: achieving positive adoption outcomes for African American children

African American children are overrepresented in foster care by more than twice their proportion in the population (U.S. Government Accountability Office [USGAO], 2007). Building upon research relating faith (religiosity) to positive health and mental health, this study utilized cognitive and religious coping theories to examine the influence of faith on choosing to adopt, achieving positive adoption outcomes, and reducing disproportionality. From Louisiana and Texas, 113 families who adopted 226 children, 48% African American, participated in a survey measuring children's behavior and parent distress (PSI-SF Difficult Child and Parent Distress Subscales) and religiosity (Hoge Intrinsic Religiosity Index). Of the respondents, 93% of the respondents belonged to a religious congregation, 86% attended church weekly. Controlling for child's behavior, religiosity predicted lower stress in adoptive parenting; church attendance was related to improvement in parental health since adopting. Faith was rated most frequently as essential in parents' decisions to adopt. The study concludes that faith may be an asset in increasing adoptions and improving adoption outcomes resulting in increased numbers of African American children adopted.     

Data mining in children and family services: the Contra Costa County experience

Despite access to a comprehensive administrative database that would allow for timely data retrieval and utilization, regular use of data to inform service provision remained infrequent at one children and family services agency. To address this issue, a research and evaluation manager was hired to facilitate regular data use and evidence-informed service provision. This led to a shift in agency culture that moved from viewing data collection as a burden and threat, to now valuing data as a powerful tool for improving programs and outcomes for children and families. This case study presents the experiences of this agency, describing the process by which the research and evaluation manager was hired, how data are now used by the agency, significant changes resulting from the agency's new data use practices, and perspectives of the evaluator and staff on data use and changes in agency culture.     

Manipulating motivating operations to facilitate the emergence of mands for a child with autism

Research on the functional independence of verbal operants (Skinner, 1957) has demonstrated inconsistent findings. One explanation may be that these studies have not manipulated the motivating operation (MO) to facilitate the emergence of mands (Hall & Sundberg, 1987; Lamarre & Holland, 1985). In the current study, 1 participant, diagnosed with autism, was taught to tact high-preference and low-preference leisure items, and emergence of mands was tested under varying MO conditions. Results showed the emergence of mands following periods of arranged deprivation, and greater maintenance for a highly preferred relative to a less preferred stimulus. However, mands only emerged when presession tact trials were conducted. These results suggest that in a state of deprivation, transfer of stimulus control from discriminative to motivational conditions may occur without direct training.     

Sexual practices and the duration of last heterosexual encounter: findings from the Australian longitudinal study of health and relationships

This study investigated the association between sexual practices and duration of a sexual encounter. Using data from a population-based computer-assisted telephone survey of 8,656 Australians aged 16 to 64 years, four distinct patterns of sexual practices among respondents were found: "basic sexual encounter" (involving mainly kissing, cuddling, stroking one's partner and being stroked, and vaginal intercourse), "basic sexual encounter plus oral sex," "all assessed sexual practices" (all sexual behaviors included in the survey), and "mainly vaginal intercourse" (characterized by lower levels of kissing, cuddling, and stroking). For both men and women, respondents classified in the basic sexual encounter plus oral sex, and all assessed sexual practices clusters reported significantly longer durations than those in the basic sexual encounter group, whereas respondents in the mainly vaginal intercourse cluster reported shorter durations. These differences were found even after allowing for demographic differences in sexual duration-specifically, age and partner type of the most recent opposite-sex partner. These findings add to the understanding of what typically happens in a sexual encounter. Overall, longer sexual encounters appear to be associated with the inclusion of the least common sexual practices-namely, oral sex and self-stimulation.     

Staff & client perceptions of unit quality: a pilot study

This pilot study compared psychiatric health care team members' perceptions of unit quality with discharged clients' perceptions of quality of care received on the unit. The staff members were from four different service units in one acute care psychiatric facility. The study used the Perceptions of Unit Quality (PUQ) scale, a valid and reliable outcome measurement instrument, developed by Cronenwett. Most quality assurance instruments that exist have focused on individual caregivers' or service-specific views of quality, but the PUQ scale allows quality assurance data that represent team performance to be described through team perceptions of quality. Results of this pilot study suggest that use of the PUQ scale, in conjunction with clients' perceptions of unit quality, may be a legitimate approach in continuous quality improvement efforts in psychiatric-mental health care centers.