Blocking in Rapid Finger Tapping: The Role of Variability in Proximodistal Coordination

In rapid finger tapping, occasional intertap intervals of about twice the normal length or even longer, called blockings, can be observed. Skilled rapid tapping requires that flexor and extensor activity be timed so that they coincide with certain phases of the finger movement. In the present study, the hypothesis examined was that blockings are associated with a deviation from the proper timing relations between the more proximal signals (electromyographic [EMG] bursts) and the more distal signal (position-time curve of the finger). Participants (N = 8) performed up-and-down tapping. Blockings were compared with the preceding normal tapping cycles; a temporal forward shift of the flexor burst in the time interval between two kinematic landmarks—the lifting of the finger and the reversal of the movement—was found consistently in the blockings The phase shift of the flexor burst relative to the kinematic landmarks did not develop gradually in the course of the tapping cycles that preceded the blocking but was an abrupt deviation, which suggests that blockings occur with an increased likelihood as the extremes of the normal variability of the phase relation are approached.     

Rates of Subthreshold PTSD Among U.S. Military Veterans and Service Members: A Literature Review

The current study’s goal was to provide a comprehensive review of current subthreshold posttraumatic stress disorder (PTSD) rates among U.S. military veterans and service members. PubMed, PsycInfo, ProQuest, Web of Knowledge, Google Scholar, and any relevant articles’ reference lists identified studies of subthreshold PTSD in the U.S. military. Search terms included PTSD in combination with partial, subthreshold or sub-threshold, subsyndromal or sub-syndromal, subclinical or sub-clinical, and military or veteran. Sixteen articles met criteria for review. Current subthreshold PTSD rates ranged from 2.3% to 22.3%, with a weighted mean rate of 7.6%. Definitional variation within and across the “below threshold” terms produced some variability in rates reported. Few studies consistently reported on impairment and comorbidity in the subthreshold PTSD population. Variability of current subthreshold PTSD rates may be due to methodological issues such as sampling methods, sample sizes, and how below threshold PTSD was assessed and defined. Based on our findings, we provide a number of recommendations that can be used to inform future research of subthreshold PTSD among U.S. military veterans and service members. These recommendations include having a standardized term and definition, determining how to more properly assess subthreshold PTSD symptomatology, clarifying subthreshold PTSD diagnostic stability, and identifying appropriate sampling methods.     

Modular Organization of Exploratory Force Development Under Isometric Conditions in the Human Arm

Muscle coordination of isometric force production can be explained by a smaller number of modules. Variability in force output, however, is higher during exploratory/transient force development phases than force maintenance phase, and it is not clear whether the same modular structure underlies both phases. In this study, eight neurologically-intact adults isometrically performed target force matches in 54 directions at hands, and electromyographic (EMG) data from eight muscles were parsed into four sequential phases. Despite the varying degree of motor complexity across phases (significant between-phase differences in EMG-force correlation, angular errors, and between-force correlations), the number/composition of motor modules were found equivalent across phases, suggesting that the CNS systematically modulated activation of the same set of motor modules throughout sequential force development.     

The Political Consequences of Combat: Post‐Traumatic Stress and Political Alienation Among Vietnam Veterans

On average, veterans are more civically and politically engaged than civilians. Previous research on the effects of military service, however, did not account for differences in veterans’ combat experiences. Using survey data from a representative sample of Vietnam veterans, this study presents evidence that veterans who were exposed to severe combat trauma and veterans who exhibited attitudes and fears associated with post‐traumatic stress had significantly lower levels of political efficacy and trust. The negative consequences of combat exposure and post‐traumatic stress are not mitigated when veterans have quality social support or when they seek professional counseling. These findings inform political psychology and hold implications for claims regarding the empowering influence of service in the U.S. military, increased political engagement, in particular. Among Vietnam veterans, exposure to severe combat trauma and post‐traumatic stress were both associated with reduced political efficacy and trust.     

The Embodiment Thesis

In this essay I articulate and defend a thesis about the nature of morality called “the embodiment thesis”. The embodiment thesis states that moral values underdetermine the obligations and entitlements of individual persons, and that actual social institutions must embody morality by specifying these moral relations. I begin by presenting two thought experiments that elucidate and motivate the embodiment thesis. I then proceed by distinguishing the embodiment thesis from a Rawlsian doctrine about the nature of justice, from the doctrine of moral relativism, and from solutions to the coordination problem of rational choice theory.     

健全社区卫生服务功能与防控"非典"传播的理性思考

针对我国当访“非典”防治工作的严竣形势,对健全社区卫生服务“六位一体”功能与防控“非典”传播问题进行哲学思考,着重在健全社区卫生服务功能是防控“非典”传播的客观要求;社区卫生服务功能不全将会对防控“非典”工作产生不利影响;构筑防控“非典”传播的有效机制和基础防线,必须健全社区卫生服务功能等方面作了分析论述。     

Mental Health Utilization Among Diverse Parenting Young Couples

Mental health issues often become apparent as adolescents emerge into young adulthood. The use of mental health services is low among adolescents and young adults, and use is particularly low among minorities. In this study, we examine mental health utilization among diverse young parenting couples. The sample consisted of 296 couples. We used the social–personal framework to examine personal, family, partner relationship, and environmental predictors for using mental health services. We used the Actor–Partner Interdependence Model to assess actor and partner effects on mental health utilization. We also examined moderator effects for gender and internalizing and externalizing behaviors. We found that being female, being White, higher income, more conduct problems, and less anxious romantic attachment predicted mental health utilization. Significant moderator effects included depression × gender, depression × medical insurance, and stress × Latino. Implications for community mental health practice include conducting mental health assessments during medical visits and systematic mental health follow‐up for individuals and couples with identified mental health and support needs. Future research should include married couples and the spouse’s influence on mental health use and examine relevant parenting factors that may also predict mental health utilization among couples.     

对“医疗服务商品和市场”存在客观性和必然性的理性思考——兼评《对中国医疗卫生体制改革的评价与建议》

针对国务院发展研究中心课题组发表的《对中国医疗卫生体制改革的评价与建议》提出的卫生改革带来“问题的根源在于商业化、市场化的走向违背了医疗卫生事业发展的基本规律。”提出“医疗服务商品”、“医疗服务市场”的存在是客观的,并通过反驳《评价与建议》提出的四对矛盾,提出“医疗服务商品”、“医疗服务市场”的存在也是必然的,最后分析了所谓“卫生改革失败”的真正原因。     

Multi-dimensional coordination in cross-country skiing analyzed using self-organizing maps

This study sought to ascertain how multi-dimensional coordination patterns changed with five poling speeds for 12 National Standard cross-country skiers during roller skiing on a treadmill. Self-organizing maps (SOMs), a type of artificial neural network, were used to map the multi-dimensional time series data on to a two-dimensional output grid. The trajectories of the best-matching nodes of the output were then used as a collective variable to train a second SOM to produce attractor diagrams and attractor surfaces to study coordination stability. Although four skiers had uni-modal basins of attraction that evolved gradually with changing speed, the other eight had two or three basins of attraction as poling speed changed. Two skiers showed bi-modal basins of attraction at some speeds, an example of degeneracy. What was most clearly evident was that different skiers showed different coordination dynamics for this skill as poling speed changed: inter-skier variability was the rule rather than an exception. The SOM analysis showed that coordination was much more variable in response to changing speeds compared to outcome variables such as poling frequency and cycle length.