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It is widely reported that the US criminal justice system is systematically biased in regard to criminal adjudication based on race and class. Specifically, there is concern that Black and Latino defendants as well as poorer defendants receive harsher sentences than Whites or Asians or wealthier defendants. We tested this in a meta-analytic review of 51 studies including 120 effect sizes. Several databases in psychology, criminal justice and medicine were searched for relevant articles. Overall results suggested that neither class nor race biases for criminal adjudications for either violent or property crimes could be reliably detected. For all crimes, effect sizes (in terms of r) for Black vs White comparisons were.054, for Latinos vs Whites, 0.057 and for Asians vs Whites −0.028. There was significant heterogeneity between studies, particularly for Asian vs White comparisons. Effect sizes were smaller than our evidentiary threshold, indicating they are indistinguishable from statistical noise. For drug crimes, evidentiary standards were met, although effect sizes were very small. Better quality studies were less likely to produce results supportive of disparities. Studies with citation bias produced higher effect sizes than did studies without citation bias suggesting that researcher expectancy effects may be driving some outcomes in this field, resulting in an overestimation of true effects. Taken together, these results do not support beliefs that the US criminal justice system is systemically biased at current. Negativity bias and the overinterpretation of statistically significant "noise" from large sample studies appear to have allowed the perception or bias to be maintained among scholars, despite a weak evidentiary base. Suggestions for improvement in this field are offered. Narratives of "systemic racism" as relates to the criminal justice system do not appear to be a constructive framework from which to understand this nuanced issue. • It is commonly believed ethnicity predicts criminal justice outcomes in the US. • For most crimes, evidence for racial disparities is weak. • Very small disparities appear to persist for drug crimes only. • Academia has often worryingly overstated the evidence for racial disparities in the US criminal justice system. [ABSTRACT FROM AUTHOR]

Scientific fields often assign fame to certain individuals and studies to delineate a narrative about the field's importance, success, and contribution to knowledge. However, such assignations of fame can result in a situation wherein assumptions of scientific merit may follow from fame, rather than fame following from clear scientific merit. This can result in several problems for the field including conflicts of interest in peer review, resistance to disconfirmatory results, politicization of some research areas, and may contribute to psychology's replication crisis. It is suggested that principles of replicability, transparency and open science can, ultimately, help psychological science identify those empirical results which are most verifiable and, as such, deserving of "fame." [ABSTRACT FROM AUTHOR]

Like many areas of psychology, aggression research has been impacted by psychology's replication crisis. Until recently, aggression was understood largely from the perspective of social cognitive models, wherein aggression was conceptualized as learned scripts. However, more recent rigorous research has suggested that cognitive scripts may play only a small role in aggression. By contrast, genetic and evolutionary inputs are powerful and combine with both developmental and situational life stress to increase the risk for serious aggression. This article examines aggression from the Catalyst Model and how diathesis-stress approaches to understanding aggression can help reduce error in predicting clinically significant aggression. This article also addresses related issues of measurement error and smallest effect size of interest (SESOI) as they relate to aggression research. [ABSTRACT FROM AUTHOR]

For decades politicians, parent groups, researchers, media outlets, professionals in various fields, and laymen have debated the effects playing violent video games have on children and adolescents. In academia, there also exists a divide as to whether violent video games cause children and adolescents to be aggressive, violent, and even engage in criminal behavior. Given inconsistencies in the data, it may be important to understand the ways and the reasons why professional organizations take a stance on the violent video game effects debate which may reflect greater expressed certitude than data can support. This piece focuses on the American Psychological Association's internal communications leading to the creation of their 2005 Resolution on Violence in Video Games and Interactive Media. These communications reveal that in this case, the APA attempted to "sell" itself as a solution to the perceived violent video game problem. The actions leading to the 2005 resolution are then compared to the actions of the APA's 2013-2015 Task Force on Violent Media. The implications and problems associated with the APA's actions regarding violent video games are addressed and discussed below. [ABSTRACT FROM AUTHOR]

The problem of false positives and negatives has received considerable attention in behavioral research in recent years. The current paper uses video game violence research as an example of how such issues may develop in a field. Despite decades of research, evidence on whether violent video games (VVGs) contribute to aggression in players has remained mixed. Concerns have been raised in recent years that experiments regarding VVGs may suffer from both "false positives" and "false negatives." The current paper examines this issue in three sets of video game experiments, two sets of video game experiments on aggression and prosocial behaviors identified in meta-analysis, and a third group of recent null studies. Results indicated that studies of VVGs and aggression appear to be particularly prone to false positive results. Studies of VVGs and prosocial behavior, by contrast are heterogeneous and did not demonstrate any indication of false positive results. However, their heterogeneous nature made it difficult to base solid conclusions on them. By contrast, evidence for false negatives in null studies was limited, and little evidence emerged that null studies lacked power in comparison those highlighted in past meta-analyses as evidence for effects. These results are considered in light of issues related to false positives and negatives in behavioral science more broadly. [ABSTRACT FROM AUTHOR]

Introduced in 2018, the American Psychological Association's (APA) Practice Guidelines for Men and Boys was intended to provide helpful direction for practitioners when seeing male patients. This followed in the tradition of other practice and clinical guidelines for clinical work with specific identity populations. However, the practice guidelines for men and boys quickly became controversial given concerns that the guidelines were disparaging of men and boys, particularly those with traditional values and sought to impose progressive or feminist gender norms and ideologies rather than remaining focused on clinical wellness and empathy. This review finds that, though the guidelines were offered in good faith, many of the critiques are likely valid. Specifically, the guidelines failed to acknowledge significant evidence for biological influences on gender (e.g., hormonal, and hypothalamic influences on gender identity and gendered behavior), were unintentionally disparaging of traditional men and families, and were too closely wedded to specific sociocultural narratives and incurious of data not supporting those narratives. It is concluded that there are reasonable concerns that the current guidelines may do more harm than good by dissuading traditional men and families from seeking counseling. [ABSTRACT FROM AUTHOR]

Many gamers report that playing video games, including those with violent content, helps them to reduce stress. However, few studies have examined competitive and cooperative video game play as they relate to stress reduction. The current study employed a design to acutely stress 100 participants before assigning them randomly to play a mildly violent game either competitively or cooperatively with a female confederate. Results indicated stress levels declined over time at equal levels during both competitive and cooperative game play. Participants in the competitive condition held a slightly less positive impression of the confederate following game play, although players held a generally positive impression of the confederate overall. [ABSTRACT FROM AUTHOR]

Debates regarding purported negative effects of video games have raged among scholars, clinicians and in the public arena. Surveys of both scholars and the general public reveal wide discrepancies in beliefs about the potential harmfulness of video games, and some evidence suggests that a “generational divide” may be at play. The current study examines this in a sample of 109 clinicians and clinical researchers. Beliefs about the potential harmfulness of video games varied widely in the sample, reflecting absence of a consensus. Beliefs about the harmfulness of video games were predicted by respondents’ age, female gender and negative beliefs about youth. Contrary to hypotheses, respondents’ neuroticism, openness, pacifism and previous gaming experience did not predict beliefs about video games. These results suggest that, even among clinicians, debates about video games are influenced by historical patterns of generational conflict with harmful beliefs endorsed mainly by older individuals who are hostile toward younger generations. [ABSTRACT FROM AUTHOR]

Whether video games with sexualized content do or do not relate to mental health and body image problems in players, and/or sexualization and hostility toward women, is an issue of broad public interest. However, evidence from empirical studies has generally been mixed. To examine this issue, we explored the degree to which sexualization in games was related to both well-being/body dissatisfaction and sexism/misogyny among players in two separate meta-analyses. Results revealed that sexualization in games was neither related to well-being/body dissatisfaction (r = 0.082, k = 10, n = 2,010, p =.066) nor sexism/misogyny (r = 0.040, k = 15, n = 15,938, p =.070). Better designed studies, and those that showed less evidence for researcher expectancy effects (for sexism/misogyny outcomes), tended to find less evidence for effects. As appears commonly in other realms of media effects, the evidence is weak that sexualized games influence player attitudes and behavior. • Whether sexualization in video games causes negative outcomes is a matter of concern. • Meta-analysis examined sexualization effects on misogynistic and mental health outcomes. • Exposure to sexualization in games was not found to be associated with negative outcomes. • Better quality studies were less able to find evidence for effects. [ABSTRACT FROM AUTHOR]

The role of violent video games in the development of aggression and mental health issues in youth continues to be controversial in the scholarly community and general public. Compared to college students, few studies have directly examined the potential impact of violent video games on youth and current evidence is mixed. The current article attempts to address this with three studies examining violent game play in youth aged 12–18. In Study 1, youth were randomized to play closely matched action games with either violent or non-violent content. Youth were given the opportunity to act aggressively using an ice water task. Study 2 was a conceptual replication of Study 1, with slower narrative games rather than action games. Study 3 examined the issue in a correlational study of youth, contrasting exposure to violent video games in youth’s personal lives to their exposure to violence in controversial books while controlling for other variables including family, peer and personality variables. None of the studies provided evidence for concerns linking video game violence to aggressive behaviors or reduced empathy in youth. [ABSTRACT FROM AUTHOR]

Highlights: [•] Histrionic personality disorder remains an understudied clinical syndrome. [•] We developed a brief, free screening measure for histrionic symptoms. [•] The screening measure demonstrate good reliability and validity. [•] Further testing will help demonstrate the measure’s clinical validity. [ABSTRACT FROM AUTHOR]

Highlights: [•] Research on video games, aggression and prosocial behavior remains inconclusive. [•] Examined cooperative and solitary play of violent and non-violent games. [•] Violent games had no impact on aggressive or prosocial behavior. [•] Playing cooperatively reduced aggression even in violent games. [Copyright &y& Elsevier]

Objective To assess the influence of media, specifically reality television, on adolescent behavior. Study design A total of 1141 preteen and adolescent girls (age range 11-17) answered questions related to their reality television viewing, personality, self-esteem, relational aggression, appearance focus, and desire for fame. Results Our results indicated that the influence of reality television on adolescent behavior is complex and potentially related to the adolescents' intended uses and gratifications for using reality television. Reality television viewing was positively related to increased self-esteem and expectations of respect in dating relationships. However, watching reality television also was related to an increased focus on appearance and willingness to compromise other values for fame. Reality television viewing did not predict relational aggression. Conclusion The potential influences of reality television use on adolescent girls are both positive and negative, defying easy categorization. [ABSTRACT FROM AUTHOR]

Abstract: Social scientists continue to debate the impact of spanking and corporal punishment (CP) on negative child outcomes including externalizing and internalizing behavior problems and cognitive performance. Previous meta-analytic reviews have mixed long- and short-term studies and relied on bivariate r, which may inflate effect sizes. The current meta-analysis focused on longitudinal studies, and compared effects using bivariate r and better controlled partial r coefficients controlling for time-1 outcome variables. Consistent with previous findings, results based on bivariate r found small but non-trivial long-term relationships between spanking/CP use and negative outcomes. Spanking and CP correlated .14 and .18 respectively with externalizing problems, .12 and .21 with internalizing problems and −.09 and −.18 with cognitive performance. However, when better controlled partial r coefficients (pr) were examined, results were statistically significant but trivial (at or below pr =.10) for externalizing (.07 for spanking, .08 for CP) and internalizing behaviors (.10 for spanking, insufficient studies for CP) and near the threshold of trivial for cognitive performance (−.11 for CP, insufficient studies for spanking). It is concluded that the impact of spanking and CP on the negative outcomes evaluated here (externalizing, internalizing behaviors and low cognitive performance) are minimal. It is advised that psychologists take a more nuanced approach in discussing the effects of spanking/CP with the general public, consistent with the size as well as the significance of their longitudinal associations with adverse outcomes. [Copyright &y& Elsevier]

Abstract: As Kuhn (1970) has noted, most scientific fields go through processes of paradigm change, painful periods in which old theories no longer fit available data and are placed by new theories. Such periods typically create strife and debate as ideological differences emerged between proponents of old and new theoretical approaches. In the current paper, we argue that such a period has been reached within the field of aggression research. Over the past half-century, social cognitive and social learning paradigms of aggression, exemplified in the General Aggression Model (GAM) have retained dominance, particularly in areas such as media violence. We contend that data to support the GAM and social cognitive approaches to aggression have never been conclusive, and newer evidence increasingly suggests that the GAM and social cognitive theories of aggression more generally are not adequate to explain aggressive phenomena. We discuss weaknesses and problematic, sometimes hidden assumptions of the GAM and how these reduce the utility of this paradigm. Current evidence suggests that the GAM and the social cognitive paradigm of aggression should be retired, and approaches which focus on diathesis-stress hold greater promise. [Copyright &y& Elsevier]

Abstract: Media violence continues to be a concern to parents, policy makers and researchers. In spite of confidence expressed by some that exposure to television violence causes serious aggression and violent crime, critics hold that serious flaws in research methodology limits or nullifies conclusions drawn from widely-cited studies. In this paper, we will examine a series of classic studies for lessons learned about conducting media violence research, and assess whether recent publications adhere to those standards. We conclude that empirical reports with serious flaws continue to be published, compromising our ability to understand this phenomenon. [Copyright &y& Elsevier]

Abstract: Research in the domain of video game violence continues to be contentious and debated. Scholars have examined both positive and negative effects of violent games, although results thus far have been inconclusive and systematic internal validity problems have been identified with past research. The current study adds to this growing literature by examining the effects of video game violence exposure and time spent playing on depression, hostility, and visuospatial cognition. This study improves upon previous research by matching game conditions carefully on confounding variables identified as problems by other scholars. In a laboratory setting, 100 participants were randomly assigned into one of six conditions based on two independent variables (time spent playing and type of video game). Results indicated that neither randomized video game play nor time spent playing a video game had any effect on depression, hostility, or, visuospatial cognition. Effect size estimates were below levels for practical significance. These results suggest that both positive and negative influences of violence in video games may be limited in scope. [Copyright &y& Elsevier]

Objective: To evaluate whether advertising for food influences choices made by children, the strength of these influences, and whether they might be easily undone by parental influences. Study design: Children between 3 and 8 years of age (n=75) were randomized to watch a series of programs with embedded commercials. Some children watched a commercial for a relatively healthy food item, the other children watched a commercial for a less healthy item, both from the same fast-food company. Children were also randomized either to receive parental encouragement to choose the healthy item or to choose whichever item they preferred. Results: Results indicated that children were more likely to choose the advertised item, despite parental input. Parental input only slightly moderated this influence. Conclusion: Although advertising impact on children’s food choices is moderate in size, it appears resilient to parental efforts to intervene. Food advertisements directed at children may have a small but meaningful effect on their healthy food choices. [ABSTRACT FROM AUTHOR]

Abstract: Background: In 2011 the field of video game violence experienced serious reversals with repudiations of the current research by the US Supreme Court and the Australian Government as non-compelling and fundamentally flawed. Scholars too have been calling for higher quality research on this issue. The current study seeks to answer this call by providing longitudinal data on youth aggression and dating violence as potential consequences of violent video game exposure using well-validated clinical outcome measures and controlling for other relevant predictors of youth aggression. Method: A sample of 165, mainly Hispanic youth, were tested at 3 intervals, an initial interview, and 1-year and 3-year intervals. Results: Results indicated that exposure to video game violence was not related to any of the negative outcomes. Depression, antisocial personality traits, exposure to family violence and peer influences were the best predictors of aggression-related outcomes. Interpretation: The current study supports a growing body of evidence pointing away from video game violence use as a predictor of youth aggression. Public policy efforts, including funding, would best be served by redirecting them toward other prevention programs for youth violence. [Copyright &y& Elsevier]

Abstract: Background: Mental health professionals, policy makers and the general public continue to debate the issue of pathological video gaming. Scholars disagree on the prevalence and diagnostic criteria for this potential new disorder. The current meta-analysis considers existing scholarship to examine how differing measurement methods influence prevalence rates and associations with other mental health problems. Method: Thirty three published studies and doctoral dissertations were analyzed in meta-analysis. Prevalence rates and comorbidity with other mental health problems were examined according to measurement method. Results: Prevalence estimates and comorbidity with other problems varied widely between studies. Measurement which attempted to replicate “pathological gambling” approaches produced higher prevalence estimates and lower comorbidity estimates than methods which focused on the interfering nature of pathological gaming. The most precise measures produce an overall prevalence rate of 3.1%. Interpretation: Diagnostic analogies with pathological gambling may produce spuriously high prevalence estimates, potentially over identifying non-pathological players as pathological. Diagnostic approaches focused on the interfering nature on other life needs and responsibilities may have greater validity and utility. [Copyright &y& Elsevier]

Abstract: Background: Research on youth mental health has increasingly indicated the importance of multivariate analyses of multiple risk factors for negative outcomes. Television and video game use have often been posited as potential contributors to attention problems, but previous studies have not always been well-controlled or used well-validated outcome measures. The current study examines the multivariate nature of risk factors for attention problems symptomatic of attention deficit hyperactivity disorder and poor school performance. Method: A predominantly Hispanic population of 603 children (ages 10–14) and their parents/guardians responded to multiple behavioral measures. Outcome measures included parent and child reported attention problem behaviors on the Child Behavior Checklist (CBCL) as well as poor school performance as measured by grade point average (GPA). Results: Results found that internal factors such as male gender, antisocial traits, family environment and anxiety best predicted attention problems. School performance was best predicted by family income. Television and video game use, whether total time spent using, or exposure to violent content specifically, did not predict attention problems or GPA. Interpretation: Television and video game use do not appear to be significant predictors of childhood attention problems. Intervention and prevention efforts may be better spent on other risk factors. [Copyright &y& Elsevier]

Abstract: The issue of potential media effects on psychological health of youth and young adults has been debated for decades. Research on media effects has not always been consistent. One issue that has been raised regards whether the relatively modest media effects found in some research might be explained through mediating personality variables. This hypothesis was examined in three samples of young adults: Mexican–Americans (n =232), Croatians (n =455) and English (n =150). Results indicated that trait aggression was a consistent predictor of both violent crimes and depression across samples. General personality variables were less consistent predictors of violence, although neuroticism consistently predicted depression across samples. Media violence exposure did not predict negative outcomes except among Croatians for whom exposure to violent video games predicted fewer violent crimes, and exposure to television violence predicted increased violent crimes. [Copyright &y& Elsevier]

Abstract: The positive and negative influences of violent/action games, henceforth called “action games”, remains controversial in the scholarly literature. Although debate continues whether action games influence aggressive behavior, little research has examined the influence of action games on civic engagement. The current study addresses this gap by examining the correlation between exposure to action games on civic engagement and on-line prosocial behavior in a sample of 873 teenagers. Results indicated that girls as well as teens who had parents who were more technologically savvy tended to engage in more civic behaviors. Exposure to action games predicted more prosocial behavior on-line, but did not predict civic engagement either positively or negatively. However, exposure to action games and parental involvement interacted to promote youth civic engagement. Action-game-playing-youth whose parents were involved in game play and supervision were most civically involved, compared to youth who did not play action games, or whose parents were less involved. These results indicated little support for the belief that exposure to violence in video games decreases prosocial behavior and/or civic engagement. Conversely some support was found for the possibility that playing action games is associated with small increased prosocial behavior and civic engagement in the real world, possibly due to the team-oriented multiplayer options in many of these games. [Copyright &y& Elsevier]

Abstract: The effects of pornography, whether violent or non-violent, on sexual aggression have been debated for decades. The current review examines evidence about the influence of pornography on sexual aggression in correlational and experimental studies and in real world violent crime data. Evidence for a causal relationship between exposure to pornography and sexual aggression is slim and may, at certain times, have been exaggerated by politicians, pressure groups and some social scientists. Some of the debate has focused on violent pornography, but evidence of any negative effects is inconsistent, and violent pornography is comparatively rare in the real world. Victimization rates for rape in the United States demonstrate an inverse relationship between pornography consumption and rape rates. Data from other nations have suggested similar relationships. Although these data cannot be used to determine that pornography has a cathartic effect on rape behavior, combined with the weak evidence in support of negative causal hypotheses from the scientific literature, it is concluded that it is time to discard the hypothesis that pornography contributes to increased sexual assault behavior. [Copyright &y& Elsevier]

Abstract: The current article examines the influence of genetics and evolution on acts of extreme and criminal violence among human primates. Moderate aggression can function to increase an organism''s reproductive success; extreme violence can place the organism at unnecessary risk. Genetic polymorphisms that have been linked to extreme acts of violence are reviewed as is research elucidating how genetic risk and environmental stress may interact to increase risk of extreme violence. Extreme violence is viewed as high-end variance in an evolutionarily adaptive process in which the propensity for aggression and violent behavior, in moderate doses, has been adaptive for individual humans. [Copyright &y& Elsevier]

Objective: To conduct a meta-analytic review of studies that examine the impact of violent media on aggressive behavior and to determine whether this effect could be explained through methodological problems inherent in this research field. Study design: A detailed literature search identified peer-reviewed articles addressing media violence effects. Effect sizes were calculated for all studies. Effect sizes were adjusted for observed publication bias. Results: Publication bias was a problem for studies of aggressive behavior, and methodological problems such as the use of poor aggression measures inflated effect size. Once corrected for publication bias, studies of media violence effects provided little support for the hypothesis that media violence is associated with higher aggression. The corrected overall effect size for all studies was r = .08. Conclusions: Results from the current analysis do not support the conclusion that media violence leads to aggressive behavior. It cannot be concluded at this time that media violence presents a significant public health risk. [Copyright &y& Elsevier]

Abstract: Previous research has indicated that potential jurors are likely to use personal biases, such as those based on gender and ethnicity, in their judgments of culpability of criminal defendants in addition to, or instead of, the facts of the crime. The present paper seeks to extend this literature to the crime of filicide; to examine whether male defendants are judged more harshly than female defendants, as is the case for domestic violence and sexual abuse. 214 participants were provided with a scenario of filicide in which the gender of the perpetrator, the gender of the child, and the family''s social class were randomly assigned. Participants were asked to rate the culpability of the defendant in the case. Results indicated that, unlike for other violent crimes, participants did not use gender or social class biases in their judgments of criminal culpability. [Copyright &y& Elsevier]

Abstract: Violence in video games has come under increasing research attention over the past decade. Researchers in this area have suggested that violent video games may cause aggressive behavior among players. However, the state of the extant literature has not yet been examined for publication bias. The current meta-analysis is designed to correct for this oversight. Results indicated that publication bias does exist for experimental studies of aggressive behavior, as well as for non-experimental studies of aggressive behavior and aggressive thoughts. Research in other areas, including prosocial behavior and experimental studies of aggressive thoughts were less susceptible to publication bias. Moderator effects results also suggested that studies employing less standardized and reliable measures of aggression tended to produce larger effect sizes. Suggestions for future violent video game studies are provided. [Copyright &y& Elsevier]

Various experimental poly(vinyl acetate) (PVAc) latices containing relatively rigid polystyrene (PS) domains were investigated in order to evaluate whether the presence of PS domains improves the performance, especially the creep resistance, of PVAc adhesives. The effects of a range of PS content, PS/PVAc morphologies and core-shell polymerisation approaches were examined by evaluating thin-film mechanical properties and adhesive performance. The results have shown that up to 50% PS (by mass) can be incorporated into a PVAc latex without compromising adhesive strength. Mechanical testing of films indicated the presence of PS maintains film performance at elevated temperature (60°C). Polymers formed using a chain transfer agent during the second stage styrene polymerisation had a concentric core-shell morphology and these performed better than either copolymers having an acorn morphology or a simple blend of PS and PVAc. Incorporation of PS domains into a commercial PVAc adhesive by second-stage polymerisation of styrene did not greatly diminish the performance of the conventional adhesive. While performance advantages acquired by adding PS into PVAc particles were demonstrated during creep testing at high humidity, the presence of PS did not impart any improved resistance to water or to heat, as determined by accelerated exposure water soak testing and shear block testing above 70°C. [Copyright &y& Elsevier]

The last several decades have seen increased research attention to the subject of serial murder. Unfortunately, an empirical understanding of serial homicide continues to be impeded by difficulties in establishing a working definition for serial murder. Current definitions for serial homicide tend to focus on frequency and timing of homicide behaviors, and thus leave some confusion as to which groups of individuals should be included under the heading of serial murders. This article suggests alterations to the definition of serial murder, which focus not only on frequency and timing of homicide behaviors, but also on the motivation and context of those behaviors. [Copyright &y& Elsevier]

A strategy is explored for synthesizing latex particles with polystyrene cores and poly(vinyl acetate) shells. The seed particles are poly(vinyl acetate), which theory indicates should be immune to secondary particle formation when a second-stage seeded emulsion polymerization with styrene is carried out. The objective is to form a single hydrophobic core by inversion of the second and first stages. While this morphology is favoured thermodynamically, conditions need to be optimized so that it is kinetically achievable: many attempts to implement this using straightforward synthetic procedures result in either no core (acorn morphology) or multiple polystyrene cores. A series of experiments enables this goal to be implemented by ensuring sufficiently fast diffusion of the first-stage hydrophilic polymer (using chain-transfer agent to reduce the molecular weight and, more importantly, the degree of branching of the parent poly(vinyl acetate) seed polymer), an initiator which minimized grafting between the first- and second-stage polymers, and modifying the seed poly(vinyl acetate) to increase its hydrophilicity. [Copyright &y& Elsevier]

Strategies for avoiding secondary particle formation in seeded emulsion polymerisation, based on a simple model for particle nucleation [Macromol. Symp. 92 (1995) 13], are discussed and exemplified in the context of growing latex particles with polystyrene cores and poly(vinyl acetate) shells. With a polystyrene seed of unswollen radius 44 nm, core–shell polymerisation was easily achieved. However, when the same recipes were used with a polystyrene seed of unswollen radius 200 nm, excessive new particle formation occurred and no poly(vinyl acetate) shells could be detected. A wide selection of the suggested strategies for overcoming this were implemented, but always either extensive secondary nucleation occurred or the system became colloidally unstable. These results are in full accord with the predictions of the simplified nucleation model. [Copyright &y& Elsevier]

A simple model for particle formation in surfactant[hyphen]free emulsion polymerisation [Macromol. Symp. 92 (1995) 13; Emulsion polymerization: a mechanistic approach, 1995], with extension to allow for induced decomposition of initiator, is explored. The object is to find conditions for secondary particle formation, especially to find conditions under which it would be possible to grow core–shell particles of vinyl acetate in styrene, and vice versa; core–shell particle formation requires that secondary particle formation be avoided. The system is described by homogeneous nucleation: a radical generated in the aqueous phase will either enter a latex particle, undergo termination, or grow in the aqueous phase until it becomes the nucleus of a new particle. The simplified kinetic description contains only easily specified parameter values and requires minimal computational resources. The model implies that secondary particle formation is suppressed by decreasing seed radius, by increasing solids content, and by starved[hyphen]feed conditions; seed radius is by far the most influential, while monomer[hyphen]catalysed initiator decomposition has negligible effect. The model predicts that new particle formation will be rampant when vinyl acetate is polymerised in the presence of large polystyrene particles (implying that large core–shell polystyrene/poly(vinyl acetate) (PS/PVAc) particles cannot be obtained in this way), but that there should be relatively little secondary particle formation when styrene is polymerised in the presence of large PVAc particles (implying that large core–shell PS/PVAc particles can be created by inverse core–shell polymerisation). The model was also used to estimate the particle numbers expected in ab initio, surfactant[hyphen]free styrene and vinyl acetate systems. The model explains why such styrene systems give large, monodisperse particles, whereas such vinyl acetate systems give much smaller particles. Comparison of predictions of the model with those of more sophisticated treatments suggests that model contains the kinetic events which are most essential in determining the rate of particle formation, and thus is sufficient for stating whether or not massive secondary nucleation will occur. [Copyright &y& Elsevier]

Objective: To examine the multivariate nature of risk factors for youth violence including delinquent peer associations, exposure to domestic violence in the home, family conflict, neighborhood stress, antisocial personality traits, depression level, and exposure to television and video game violence. Study design: A population of 603 predominantly Hispanic children (ages 10-14 years) and their parents or guardians responded to multiple behavioral measures. Outcomes included aggression and rule-breaking behavior on the Child Behavior Checklist (CBCL), as well as violent and nonviolent criminal activity and bullying behavior. Results: Delinquent peer influences, antisocial personality traits, depression, and parents/guardians who use psychological abuse in intimate relationships were consistent risk factors for youth violence and aggression. Neighborhood quality, parental use of domestic violence in intimate relationships, and exposure to violent television or video games were not predictive of youth violence and aggression. Conclusion: Childhood depression, delinquent peer association, and parental use of psychological abuse may be particularly fruitful avenues for future prevention or intervention efforts. [Copyright &y& Elsevier]