Balancing exposed and hidden nodes in linear wireless networks

Wireless networks equipped with the CSMA protocol are subject to collisions due to interference. For a given interference range, we investigate the tradeoff between collisions (hidden nodes) and unused capacity (exposed nodes). We show that the sensing range that maximizes throughput critically depends on the activation rate of nodes. For infinite line networks, we prove the existence of a threshold: When the activation rate is below this threshold, the optimal sensing range is small (to maximize spatial reuse). When the activation rate is above the threshold, the optimal sensing range is just large enough to preclude all collisions. Simulations suggest that this threshold policy extends to more complex linear and nonlinear topologies. Keywords: Carrier-sensing range; Markov processes; collisions; exposed nodes; hidden nodes; random-access; throughput; wireless network

Conceptualizing autonomy in the context of chronic physical illness: relating philosophical theories to social scientific perspectives

The aim of this article is to conceptualize autonomy in the context of chronic physical illness. To this end, we compare and contrast a selection of contemporary philosophical theories of autonomy with social scientific perspectives on chronic illness, particularly models of disability and symbolic interactionism. The philosophical theories mainly depart from a positive conceptualization of autonomy, which involves actively shaping one's life and identifying with fundamental values. This conceptualization is preferred over a negative conceptualization, which defines autonomy as non-interference, for its compatibility with social models of disability and with the assumption that people are interdependent. Interference may disable, but also enable people with a chronic illness to shape their lives. What matters is that people can realize what they want to realize. We suggest that, in the context of chronic physical illness, autonomy might be conceptualized as correspondence between what people want their lives to be like and what their lives are actually like. Disturbed autonomy might be restored either by expanding opportunities to arrange life or by adjusting how one wants life to be arranged. The grounds for the latter approach might be questioned, first, if people have not adjusted what they want carefully, and second, if reorganization of the material and social environment would have made it unnecessary to adjust one's arrangement of life

Ghrelin drives GH secretion during fasting in man

OBJECTIVES: In humans, fasting leads to elevated serum GH concentrations. Traditionally, changes in hypothalamic GH-releasing hormone and somatostatin release are considered as the main mechanisms that induce this elevated GH secretion during fasting. Ghrelin is an endogenous ligand of the GH secretagogue receptor and is synthesized in the stomach. As ghrelin administration in man stimulates GH release, while serum ghrelin concentrations are elevated during fasting in man, this increase in ghrelin levels might be another mechanism whereby fasting results in stimulation of GH release. DESIGN AND SUBJECTS: In ten healthy non-obese males we performed a double-blind placebo-controlled crossover study comparing fasting with and fasting without GH receptor blockade. GH, ghrelin, insulin, glucose and free fatty acids were assessed. RESULTS: While ghrelin levels do not vary considerably in the fed state, fasting rapidly induced a diurnal rhythm in ghrelin concentrations. These changes in serum ghrelin concentrations during fasting were followed by similar, profound changes in serum GH levels. The rapid development of a diurnal ghrelin rhythm could not be explained by changes in insulin, glucos

Effects of Somatostatin Analogs and Dopamine Agonists on Insulin-Like Growth Factor 2-Induced Insulin Receptor Isoform-A Activation by Gastroenteropancreatic Neuroendocrine Tumor Cells

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Retrospective evaluation of the Dutch pre-newborn screening cohort for propionic acidemia and isolated methylmalonic acidemia: What to aim, expect, and evaluate from newborn screening?

Evidence for effectiveness of newborn screening (NBS) for propionic acidemia (PA) and isolated methylmalonic acidemia (MMA) is scarce. Prior to implementation in the Netherlands, we aim to estimate the expected health gain of NBS for PA and MMA. In this national retrospective cohort study, the clinical course of 76/83 Dutch PA and MMA patients, diagnosed between January 1979 and July 2019, was evaluated. Five clinical outcome parameters were defined: adverse outcome of the first symptomatic phase, frequency of acute metabolic decompensations (AMD), cognitive function, mitochondrial complications, and treatment-related complications. Outcomes of patients identified by family testing were compared with the outcomes of their index siblings. An adverse outcome due to the first symptomatic phase was recorded in 46% of the clinically diagnosed patients. Outcome of the first symptomatic phase was similar in 5/9 sibling pairs and better in 4/9 pairs. Based on the day of diagnosis of the clinically diagnosed patients and sibling pair analysis, a preliminary estimated reduction of adverse outcome due to the first symptomatic phase from 46% to 36%-38% was calculated. Among the sibling pairs, AMD frequency, cognitive function, mitochondrial, and treatment-related complications were comparable. These results suggest that the health gain of NBS for PA and MMA in overall outcome may be limited, as only a modest decrease of adverse outcomes due to the first symptomatic phase is expected. With current clinical practice, no reduced AMD frequency, improved cognitive function, or reduced frequency of mitochondrial or treatment-related complications can be expected

A Test and Refinement of the Demand-Control-Support Model in the Construction Industry

This study aims at a test and further refinement of the Demand-Control-Support (DCS) model among construction workers (N = 210). On the basis of theory and empirical evidence, we hypothesized that mental or physical job demands, low job control, and lack of social support at work have direct and synergistic effects on burnout. The model was expanded by hypothesizing that burnout mediates the relationships between these potentially demanding working conditions on the one hand, and health complaints on the other. Results of a series of structural equation analyses partly supported these hypotheses. The proposed model fitted adequately to the data, although some variables in the DCS model did not make a unique contribution to explaining variance in burnout and (indirectly) health complaints. Interestingly, lack of social support was the most important determinant of burnout and health complaints among construction workers. In addition, a significant three-way interaction effect partly confirmed the synergism hypothesis: Physical demands were only related to burnout if participants had poor job control and reported high social support. The implications of these findings for research and practice are discussed