OWLS: a ten-year history in optical wireless links for intra-satellite communications

The application of Optical Wireless Links to intra- Spacecraft communications (OWLS) is presented here. This work summarizes ten years of developments, ranging from basic optoelectronic parts and front-end electronics, to different inorbit demonstrations. Several wireless applications were carried out in representative environments at ground level, and on in-flight experiments. A completely wireless satellite will be launched at the beginning of 2010. The benefits of replacing standard data wires and connectors with wireless systems are: mass reduction, flexibility, and simplification of the Assembly, Integration and Tests phases (AIT). However, the Aerospace and Defense fields need high reliability solutions. The use of COTS (Commercial-Off-The- Shelf) parts in these fields require extensive analyses in order to attain full product assurance. The current commercial optical wireless technology needs a deep transformation in order to be fully applicable in the aforementioned fields. Finally, major breakthroughs for the implementation of optical wireless links in Space will not be possible until dedicated circuits such as mixed analog/digital ASICs are developed. Once these products become available, it will also be possible to extend optical wireless links to other applications, such as Unmanned Air and Underwater Vehicles (UAV and UUV). The steps taken by INTA to introduce Optical Wireless Links in the Space environment are presented in this paper.     

Effects of methylphenidate on discounting of delayed rewards in attention deficit/hyperactivity disorder.

Impulsivity is a central component of attention deficit/hyperactivity disorder (ADHD). Delay discounting, or a preference for smaller, immediate rewards over larger, delayed rewards, is considered an important aspect of impulsivity, and delay-related impulsivity has been emphasized in etiological models of ADHD. In this study, we examined whether stimulant medication, an effective treatment for ADHD, reduced discounting of delayed experiential and hypothetical rewards among 49 children (ages 9–12 years) with ADHD. After a practice day, participants completed a 3-day double-blind placebo-controlled acute medication assessment. Active doses were long-acting methylphenidate (Concerta), with the nearest equivalents of 0.3 and 0.6 mg/kg TID immediate-release methylphenidate. On each testing day, participants completed experiential (real-world money in real time) and hypothetical discounting tasks. Relative to placebo, methylphenidate reduced discounting of delayed experiential rewards but not hypothetical rewards. Broadly consistent with etiological models that emphasize delay-related impulsivity among children with ADHD, these findings provide initial evidence that stimulant medication reduces delay discounting among those with the disorder. The results also draw attention to task parameters that may influence the sensitivity of various delay discounting measures to medication effects. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

AGENT-BASED SIMULATION FOR BORDER CROSSING MODELING

The aim of this study is to build a computational model to simulate border crossing. Since the 19th century, many theories have been applied to the study of international migration phenomena. These theories cover sociological, economical, and cultural aspects. All the theories aim at estimating the magnitude of population movements. Multi-Agent Systems (MAS) are presented as a new methodological approach to model and foresee the process of migration. This article discusses how legal aspects can also be treated from a computational point of view. When a migrant reaches the border checkpoint, he/she must deal with the legislation of the destination country, which is applied by the border security police. This interaction at the microlevel between the migrant and the border agent is based on the definition of a behavioral model that includes the migrant's profile, the border officer's profile, and the legislation that rules the border crossing. With this model, the effects at the macrolevel of new policies (which are usually difficult to predict) can be estimated. Changes in legislation or in strictness in applying the existing law at certain borders can influence migration trends; for example, the choice of route. This study presents the main features of the computational model that has been developed to recreate the border-crossing scenario in a Multi-Agent System.     

How do therapists enhance family alliances? Sequential analyses of therapist-client behavior in two contrasting cases.

To identify alliance-related behavior patterns in more and less successful family therapy, the authors intensively analyzed two cases with highly discrepant outcomes. Both families were seen by the same experienced clinician. Results showed that participants' perceptions of the alliance, session impact, and improvement at three points in time were congruent with the families' differential outcomes and with observer-related alliance behavior using the System for Observing Family Therapy Alliances. In this measure, therapist behaviors contribute to the alliance and client behaviors reveal the strength of the alliance on four dimensions: Engagement in the Therapeutic Process, Emotional Connection with the Therapist, Safety within the Therapeutic System, and Shared Sense of Purpose within the Family. In the poor outcome case, observer ratings and self-reported alliance scores revealed a persistently "split" alliance between family members; this family dropped out midtreatment. Only in the good outcome case did the clients follow the therapist's alliance-building interventions with positive alliance behaviors; sequential analyses showed that therapist contributions to Engagement significantly activated client Engagement behavior, and therapist Emotional Connection interventions significantly activated client Emotional Connection. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Crystallization of Rhenium Salts in a Simulated Low‐Activity Waste Borosilicate Glass

This study presents the characterization of salt phases that formed on simulated low‐activity waste glass melts during a rhenium solubility study. This study with rhenium salts is also applicable to real applications involving radioactive technetium salts. In this synthesis method, oxide glass powder is mixed with the volatile species, vacuum‐sealed in a fused quartz ampoule, and then heated in a furnace. This technique restricts the volatile species to the headspace above the melt but still within the sealed ampoule, thus maximizing the concentration of these species that are in contact with the glass. Above the previously determined solubility of Re⁷⁺ in this glass, a molten salt phase segregated to the top of the melt and crystallized into a solid layer. This salt was analyzed with X‐ray diffraction, scanning electron microscopy, energy dispersive spectroscopy, as well as wavelength dispersive spectroscopy and was found to be composed of alkali perrhenates (NaReO₄, KReO₄) and alkali sulfates. Similar crystalline inclusions were found in the bulk of some glasses as well.     

Operator error and system deficiencies: Analysis of 508 mining incidents and accidents from Queensland, Australia using HFACS

Historically, mining has been viewed as an inherently high-risk industry. Nevertheless, the introduction of new technology and a heightened concern for safety has yielded marked reductions in accident and injury rates over the last several decades. In an effort to further reduce these rates, the human factors associated with incidents/accidents needs to be addressed. A modified version of the Human Factors Analysis and Classification System was used to analyze incident and accident cases from across the state of Queensland to identify human factor trends and system deficiencies within mining. An analysis of the data revealed that skill-based errors were the most common unsafe act and showed no significant differences across mine types. However, decision errors did vary across mine types. Findings for unsafe acts were consistent across the time period examined. By illuminating human causal factors in a systematic fashion, this study has provided mine safety professionals the information necessary to reduce mine incidents/accidents further.     

Social Software in Academic Libraries for Internal Communication and Knowledge Management: A Comparison of Two Reference Blog Implementations

This article investigates the adoption of new innovations for internal reference desk communication and knowledge management in academic libraries, specifically the use of social software tools. Actual implementations of the free blog software Wordpress from two university libraries are described including charts detailing advantages and disadvantages of the methods. In the context of the diffusion of innovation and organizational lag theories, the analyzed outcomes confirm that while social software tools are being used, relatively few institutions have exploited them for improving in-house processes. Without clearly articulated long-term gains, adoption of administrative innovations will follow the pattern of organizational lag.     

Characterization of shear stress at the tool‐part interface during autoclave processing of prepreg composites

In this article, shear stress between an aluminum tool and a carbon fiber‐epoxy prepreg is characterized during cure using polymeric release agent and release film at the tool‐part interface. The effects of surface roughness, release materials, pull‐out speed, temperature, and normal force (autoclave pressure) on the shear stress are investigated using a customized friction rig. Results show that the interfacial shear stress decreases as the temperature increases and it increases as the normal force increases when using either the release film or the release agent. Additionally, changes in surface roughness from 1.35 to 0.18 μm decrease the shear stress 10–27% while the use of release agent shows a decrease between 23% and 51% in the shear stress. Furthermore, strong adhesion between the tool and the part is observed when using release agent and pull‐out speeds of 0.05 mm/min (static/dynamic friction ratio of 5.29 ± 0.19). Using the experimental data, a mathematical approach based on the Coulomb's friction model is proposed to predict the friction force at the tool‐part interface. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Application of the social action theory to understand factors associated with risky sexual behavior among individuals in residential substance abuse treatment.

Risky sexual behavior (RSB) is a leading cause of HIV/AIDS, particularly among urban substance users. Using the social action theory, an integrative systems model of sociocognitive, motivational, and environmental influences, as a guiding framework, the current study examined (1) environmental influences, (2) psychopathology and affect, (3) HIV-related attitudes and knowledge, and (4) self-regulatory skills/deficits as factors associated with event-level condom use (CU) among a sample of 156 substance users residing at a residential substance abuse treatment center (M age = 41.85; SD = 8.59; 75% male). RSB was assessed using event-level measurement of CU given its advantages for improved accuracy of recall and ability for an examination of situational variables. A logistic regression predicting event-level CU indicated the significant contribution of partner type (environmental influences), less favorable attitudes towards condoms (HIV-related attitudes and knowledge), and higher levels of risk-taking propensity (self-regulatory skills/deficits) in predicting greater likelihood of not having used a condom at one's most recent sexual encounter. This study contributes to the literature examining HIV risk behaviors among substance users within a theory-driven model of risk. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Relations between heavy drinking, gender, and substance-free reinforcement.

Behavioral economic theory and laboratory research have suggested that substance abuse may be associated with diminished engagement in enjoyable substance-free activities (substance-free reinforcement). However, college students, in particular men, have reported numerous social benefits from drinking that might mitigate the expected inverse relation between drinking and substance-free reinforcement. In this study, we examined the relations between college student heavy drinking, gender, and several categories of substance-free reinforcement (peer, dating, sexual, school, and family activities). Participants were 246 undergraduate students who were classified as a function of their reported frequency of heavy drinking during a typical week in the past month (120 heavy drinkers, 126 light drinkers). Heavy drinking was associated with significantly higher substance-free peer and sexual reinforcement. This association was gender invariant and remained significant in multiple regression models that controlled for gender, ethnicity, and fraternity or sorority membership. Substance-free reinforcement did not predict frequency of heavy drinking in models that included levels of substance-related reinforcement. The results indicate that college student heavy drinking is not associated with global deficits in substance-free reinforcement and is instead associated with increased peer and sexual activity that occurs outside the context of drinking or drug use. Prevention programs should help students to compensate for the potential loss of social reinforcement associated with reductions in drinking. (PsycINFO Database Record (c) 2010 APA, all rights reserved)