Mechanisms underlying reductions in stroke volume at rest and during exercise at high altitude

High-altitude exposure challenges the cardiovascular system to maintain oxygen delivery to the mitochondria under conditions of hypoxic stress. Following acclimatisation (3–5 days), stroke volume (SV) falls to below sea-level values but heart rate remains elevated, such that cardiac output is maintained compared to sea level. The decrease in SV has been a topic of research for over 40 years, but the underlying mechanisms are incompletely understood. Impaired systolic contractile function secondary to reduced coronary arterial oxygen tension has been investigated as a potential cause for the decrease in SV. However, despite in vitro evidence of impaired cardiac contractile force in severe hypoxia, the majority of studies to date have reported enhanced in vivo ventricular systolic function at rest and during exercise in humans up to and above 5000?m. However, the elevated function observed at rest has recently been suggested to reduce the functional reserve available during exercise. While in vivo systolic function appears enhanced at high altitude, a decrease in left ventricular end-diastolic volume (EDV) and altered filling patterns of both ventricles has been observed. The reduction in ventricular filling will undoubtedly affect SV, and four potential mechanisms have been proposed to explain the reduction in left ventricular filling. In this article, both historical and recent reports of systolic function at high altitude will be reviewed, and evidence supporting and refuting each of the four mechanisms underpinning reduced left ventricular filling will be discussed.     

Network Organizations: Symmetric Cooperation or Multivalent Negotiation?

The network model of organization plays a central role in recent sociological accounts of the information economy. This model is also often presented in organization and information and communication technologies (ICT) literature with an air of enthusiasm that underscores its advantages—flexibility, cooperative culture, innovativeness, and knowledge and technology intensity. Such themes are usually based on a “networking logic” that assumes the trustful cooperation of large and small production firms in a rapidly changing economic environment. We believe that both the logic and the themes based upon it are too narrow to be able to explain the complex dimensions of interorganizational networking. Using Enron as a case study, our goal in this article is to enrich the logic just described and to develop an extended model of the network enterprise. We argue that this is only possible by extending the unit of analysis beyond the production firm, to include, among others, subsidiaries, banks, investors, auditors, and government agencies. The proposed extended model allows the broadening of many of the aforementioned themes, making it possible to arrive at a realistic picture of the complexities of the network enterprise. The managerial advantages of the model are also discussed.     

Kirkpatrick plus: Evaluation and continuous improvement with a community focus

For almost 40 years, Donald Kirkpatrick's framework for evaluation has been used as a basic model for the identification and targeting of training-specific interventions in business, government, military, and industry alike. By approaching evaluation from four different perspectives—reaction, learning, behavior, and results—the model has provided a solid basis for the examination of training's impact on the organization. Despite the current practice of measuring one's success according to the success of one's clients, proposed changes in the model have not been frequently adopted. It is therefore likely time for professionals to reevaluate the utility and responsiveness of the Kirk-patrick framework to meet the value-added requirements of today's organizations. This article identifies tools and concepts for being responsive to the new organizational realities not originally addressed by the Kirkpatrick model.     

运动中目标设置研究的现状和存在的问题

目标设置研究是运动心理学领域的一个新课题。主要综述了近几年来国外学者对目标设置的维度、促使目标完成的有效性方法以及目标设置研究中存在的问题等方面的文献。     

Child maltreatment among school children in the Kurdistan Province, Iran

OBJECTIVE: This study examines the determinants of three types of child maltreatment: physical maltreatment, mental maltreatment, and child neglect among school children in the Kurdistan Province of Iran. The analysis examines the impact of socioeconomic, familial, demographic, and household dynamic factors on the three child maltreatment outcomes, and compares the differential impact of these factors across the three types of child maltreatment. A greater understanding of the factors associated with child maltreatment has the potential to inform public health interventions aimed at reducing specific forms of maltreatment and at identifying at risk populations. METHODS: Data were collected from 1,370 school students, age 11-18. Separate logistic models are fitted for six binary outcomes examining self-reported experiences of physical maltreatment in the home or school, mental maltreatment in the home or school, and child neglect in the home or school. RESULTS: Male children were more likely to report experiencing any kind of child maltreatment than girls. Residency in a rural area, poor parental relationships and the use of addictive substances by household members were associated with increased odds of reporting child maltreatment. Poor school performance was associated with the reporting of experiencing maltreatment at school. CONCLUSION: Each of the forms of child maltreatment is highly correlated with socioeconomic, demographic, and living condition factors. The results point to the strong influence that familial factors have in shaping a child's likelihood of reporting maltreatment. Characteristics of the mother were associated with maltreatment, but not characteristics of the father. The results highlight a number of mechanisms through which public health interventions may seek to reduce the prevalence of child maltreatment in Kurdistan; different approaches are needed to reduce child maltreatment in the home and school environments.     

Changes in respiratory muscle and lung function following marathon running in man

Respiratory muscle fatigue has been reported following short bouts of high-intensity exercise, and prolonged, moderate-intensity exercise, as evidenced by decrements in inspiratory and expiratory mouth pressures. However, links to functionally relevant outcomes such as breathing effort have been lacking. The present study examined dyspnoea and leg fatigue during a treadmill marathon in nine experienced runners. Maximal inspiratory and expiratory pressure, peak inspiratory and expiratory flow, forced vital capacity, and forced expiratory volume in one second were assessed before, immediately after, and four and 24 hours after a marathon. During the run, leg effort was rated higher than respiratory effort from 18 through 42 km (P < 0.05). Immediately after the marathon, there were significant decreases in maximal inspiratory pressure and peak inspiratory flow (from 118 +/- 20 cm H(2)O and 6.3 +/- 1.4 litres x s(-1) to 100 +/- 22 cm H(2)O and 4.9 +/- 1.5 litres x s(-1) respectively; P < 0.01), while expiratory function remained unchanged. Leg maximum voluntary contraction force was significantly lower post-marathon. Breathing effort correlated significantly with leg fatigue (r = 0.69), but not inspiratory muscle fatigue. Our results confirm that prolonged moderate-intensity exercise induces inspiratory muscle fatigue. Furthermore, they suggest that the relative intensity of inspiratory muscle work during exercise makes some contribution to leg fatigue.     

A Synchronous Online Social Work PhD Program: Educational Design and Student/Faculty Response

ABSTRACT

Faculty and students evaluate the curriculum design and delivery of a synchronous online PhD program in social work that prepares scholar-practitioners in social work research, education, and organizational practice. The designers envision a collaborative community of scholars and leaders nurtured by a cohort-based, sequenced curriculum, and intentional faculty mentoring. This teaching and learning platform provides an opportunity to engage with a globally diverse population of doctoral students while fostering both relationships and quality learning outcomes. Educational design and pedagogical features of the program are described and analyzed through the collaborative thinking and learning platform of the Community of Inquiry (CoI) model’s interdependent elements–teaching, cognitive, and social presence. Eighteen students and ten faculty evaluated the strengths and limitations of the online program across each dimension of the model through student course evaluations, focus-group reflections, and qualitative faculty survey data. Student and faculty respondents specified the benefits of synchronous presence across all three dimensions. They also identified significant barriers, particularly in the areas of teaching and social presence. Implications and recommendations are based on a review of findings that inform pedagogical decisions and design options for online PhD education in social work.