The impact of chronic childhood illness on family stress : a comparison between autism and cystic fibrosis

Compared the different patterns of stress reported by mothers of children (aged 5–12 yrs) with either a chronic physical illness (cystic fibrosis) or a chronic psychological disorder (autism), and children without a physical or psychological disorder. 24 mothers from each of these 3 groups completed a short form of the Questionnaire on Resources and Stress. Each clinical group exhibited different patterns of stressful response consistent with the nature of the disorder and the requirements of care imposed on the families. Autism contributed significantly more to family stress than did cystic fibrosis. The number of children in the family was not a significant variable. Implications for the development of family intervention programs are discussed

High temperatures-related elderly mortality varied greatly from year to year : important information for heat-warning systems

We examined the variation in association between high temperatures and elderly mortality (age ≥ 75 years) from year to year in 83 US cities between 1987 and 2000. We used a Poisson regression model and decomposed the mortality risk for high temperatures into: a “main effect” due to high temperatures using lagged non-linear function, and an “added effect” due to consecutive high temperature days. We pooled yearly effects across both regional and national levels. The high temperature effects (both main and added effects) on elderly mortality varied greatly from year to year. In every city there was at least one year where higher temperatures were associated with lower mortality. Years with relatively high heat-related mortality were often followed by years with relatively low mortality. These year to year changes have important consequences for heat-warning systems and for predictions of heat-related mortality due to climate change.

Oblique-Shock-Wave/Boundary-Layer Interaction Using Near-Wall Reynolds-Stress Models

A synthesis is presented of the predictive capability of a family of near-wall wall-normal free Reynolds stress models (which are completely independent of wall topology, i.e., of the distance fromthe wall and the normal-to-thewall orientation) for oblique-shock-wave/turbulent-boundary-layer interactions. For the purpose of comparison, results are also presented using a standard low turbulence Reynolds number k–ε closure and a Reynolds stress model that uses geometric wall normals and wall distances. Studied shock-wave Mach numbers are in the range MSW = 2.85–2.9 and incoming boundary-layer-thickness Reynolds numbers are in the range Reδ0 = 1–2×106. Computations were carefully checked for grid convergence. Comparison with measurements shows satisfactory agreement, improving on results obtained using a k–ε model, and highlights the relative importance of redistribution and diffusion closures, indicating directions for future modeling work.

Contribution to single-point closure Reynolds-stress modelling of inhomogeneous flow

This paper is concerned with recent advances in the development of near wall-normal-free Reynolds-stress models, whose single point closure formulation, based on the inhomogeneity direction concept, is completely independent of the distance from the wall, and of the normal to the wall direction. In the present approach the direction of the inhomogeneity unit vector is decoupled from the coefficient functions of the inhomogeneous terms. A study of the relative influence of the particular closures used for the rapid redistribution terms and for the turbulent diffusion is undertaken, through comparison with measurements, and with a baseline Reynolds-stress model (RSM) using geometric wall normals. It is shown that wall-normal-free rsms can be reformulated as a projection on a tensorial basis that includes the inhomogeneity direction unit vector, suggesting that the theory of the redistribution tensor closure should be revised by taking into account inhomogeneity effects in the tensorial integrity basis used for its representation.

Analysis of heat transfer and fluid flow in a triangular enclosure in presence of an adiabatic fin

Natural convection thermal boundary layer adjacent to the heated inclined wall of a right angled triangle with an adiabatic fin attached to that surface is investigated by numerical simulations. The finite volume based unsteady numerical model is adopted for the simulation. It is revealed from the numerical results that the development of the boundary layer along the inclined surface is characterized by three distinct stages, i.e. a start-up stage, a transitional stage and a steady stage. These three stages can be clearly identified from the numerical simulations. Moreover, in presence of adiabatic fin, the thermal boundary layer adjacent to the inclined wall breaks initially. However, it is reattached with the downstream boundary layer next to the fin. More attention has been given to the boundary layer development near the fin area.

Natural convection flow in a strong cross magnetic field with radiation

The problem of MHD natural convection boundary layer flow of an electrically conducting and optically dense gray viscous fluid along a heated vertical plate is analyzed in the presence of strong cross magnetic field with radiative heat transfer. In the analysis radiative heat flux is considered by adopting optically thick radiation limit. Attempt is made to obtain the solutions valid for liquid metals by taking Pr≪1. Boundary layer equations are transformed in to a convenient dimensionless form by using stream function formulation (SFF) and primitive variable formulation (PVF). Non-similar equations obtained from SFF are then simulated by implicit finite difference (Keller-box) method whereas parabolic partial differential equations obtained from PVF are integrated numerically by hiring direct finite difference method over the entire range of local Hartmann parameter, $xi$ . Further, asymptotic solutions are also obtained for large and small values of local Hartmann parameter $xi$ . A favorable agreement is found between the results for small, large and all values of $xi$ . Numerical results are also demonstrated graphically by showing the effect of various physical parameters on shear stress, rate of heat transfer, velocity and temperature.

The formation of YBa2Cu3O7-x in melt-texture heat treatments

A study of the bulk formation of YBa2Cu3O7-x from the Y2BaCuO5 plus liquid regime reveals that phase formation occurs at appreciable rates below 950°C in air. This result has been observed for phase-pure YBa2Cu3O7-x starting material given two types of heat treatment: held at 1100°C and slow-cooled from 1030°C at 6°C/h or heat-treated isothermally. Differential thermal analysis, with a cooling rate of 10°C/min indicates that the degree of undercooling for the peritectic formation of YBa2Cu3O7-x is greater than 100°C. © 1994.

Using the Depression Anxiety Stress Scale 21 (DASS-21) across cultures

DASS-21 has been validated in a number of populations such as Hispanic adults, American, British and Australian. The findings show that the DASS-21 is psychometrically sound with good reliability and validity. It is clear from the literature that the DASS-21 is a well established instrument for measuring depression, anxiety and stress in the Western world. Nonetheless, the lack of appropriate validation amongst Asian populations continues to pose concerns over the use of DASS-21 in Asian samples. Cultural variation may influence the individual’s experience and emotional expression. Thus, when researchers and practitioners employ Western-based assessments with Asian populations by directly translating them without an appropriate validation, the process can be challenging. In summary, we have conducted a series of rigorous statistical tests and minimised any potential confounds from the demographic information. The advantages of this revised DASS-18 stress scale are twofold. First, the revised DASS-18 stress scale possessed fewer items, which resulted in a cleaner factorial structure. Second, it also had a smaller inter-factor correlation. With these justifications, the revised DASS-18 stress scale is potentially more suitable for the Asian populations.

The hyperthermic patient

Concepts used in this chapter include: Thermoregulation:- Thermoregulation refers to the body’s sophisticated, multi-system regulation of core body temperature. This hierarchical system extends from highly thermo-sensitive neurons in the preoptic region of the brain proximate to the rostral hypothalamus, down to the brain stem and spinal cord. Coupled with receptors in the skin and spine, both central and peripheral information on body temperature is integrated to inform and activate the homeostatic mechanisms which maintain our core temperature at 37oC1. Hyperthermia:- An imbalance between the metabolic and external heat accumulated in the body and the loss of heat from the body2. Exertional heat stroke:- A disorder of excessive heat production coupled with insufficient heat dissipation which occurs in un-acclimated individuals who are engaging in over-exertion in hot and humid conditions. This phenomenon includes central nervous system dysfunction and critical dysfunction to all organ systems including renal, cardiovascular, musculoskeletal and hepatic functions. Non-exertional heat stroke:- In contrast to exertional heatstroke as a consequence of high heat production during strenuous exercise, non-exertional heatstroke results from prolonged exposure to high ambient temperature. The elderly, those with chronic health conditions and children are particularly susceptible.3 Rhabdomylosis:- An acute, sometimes fatal disease characterised by destruction of skeletal muscle. In exertional heat stroke, rhabdomylosis occurs in the context of strenuous exercise when mechanical and/or metabolic stress damages the skeletal muscle, causing elevated serum creatine kinease. Associated with this is the potential development of hyperkalemia, myoglobinuria and renal failure. Malignant hyperthermia:- Malignant hyperthermia is “an inherited subclinical myopathy characterised by a hypermetabolic reaction during anaesthesia. The reaction is related to skeletal muscle calcium dysregulation triggered by volatile inhaled anaesthetics and/or succinylcholine.”4 Presentation includes skeletal muscle rigidity, mixed metabolic and respiratory acidosis, tachycardia, hyperpyrexia, rhabdomylosis, hyperkalaemia, elevated serum creatine kinease, multi-organ failure, disseminated intravascular coagulation and death.5

The hypothermic patient

Concepts used in this chapter include: Thermoregulation:- Thermoregulation refers to the body’s sophisticated, multi-system regulation of core body temperature. This hierarchical system extends from highly thermo-sensitive neurons in the preoptic region of the brain proximate to the rostral hypothalamus, down to the brain stem and spinal cord. Coupled with receptors in the skin and spine, both central and peripheral information on body temperature is integrated to inform and activate the homeostatic mechanisms which maintain our core temperature at 37oC.1 Body heat is lost through the skin, via respiration and excretions. The skin is perhaps the most important organ in regulating heat loss. Hyporthermia:- Hypothermia is defined as core body temperature less than 350C and is the result of imbalance between the body’s heat production and heat loss mechanisms. Hypothermia may be accidental, or induced for clinical benefit i.e: neurological protection (therapeutic hypothermia). External environmental conditions are the most common cause of accidental hypothermia, but not the only causes of hypothermia in humans. Other causes include metabolic imbalance; trauma; neurological and infectious disease; and exposure to toxins such as organophosphates. Therapeutic Hypothermia:- In some circumstances, hypothermia can be induced to protect neurological functioning as a result of the associated decrease in cerebral metabolism and energy consumption. Reduction in the extent of degenerative processes associated with periods of ischaemia such as excitotoxic cascade; apoptotic and necrotic cell death; microglial activation; oxidative stress and inflammation associated with ischaemia are averted or minimised.2 Mild hypothermia is the only effective treatment confirmed clinically for improving the neurological outcomes of patient’s comatose following cardiac arrest.3

Effect of cold water immersion after exercise in the heat on muscle function, body temperatures, and vessel diameter

Cold water immersion (CWI) is a popular recovery modality, but actual physiological responses to CWI after exercise in the heat have not been well documented. The purpose of this study was to examine effects of 20-min CWI (14 degrees C) on neuromuscular function, rectal (T(re)) and skin temperature (T(sk)), and femoral venous diameter after exercise in the heat. Ten well-trained male cyclists completed two bouts of exercise consisting of 90-min cycling at a constant power output (216+/-12W) followed by a 16.1km time trial (TT) in the heat (32 degrees C). Twenty-five minutes post-TT, participants were assigned to either CWI or control (CON) recovery conditions in a counterbalanced order. T(re) and T(sk) were recorded continuously, and maximal voluntary isometric contraction torque of the knee extensors (MVIC), MVIC with superimposed electrical stimulation (SMVIC), and femoral venous diameters were measured prior to exercise, 0, 45, and 90min post-TT. T(re) was significantly lower in CWI beginning 50min post-TT compared with CON, and T(sk) was significantly lower in CWI beginning 25min post-TT compared with CON. Decreases in MVIC, and SMVIC torque after the TT were significantly greater for CWI compared with CON; differences persisted 90min post-TT. Femoral vein diameter was approximately 9% smaller for CWI compared with CON at 45min post-TT. These results suggest that CWI decreases T(re), but has a negative effect on neuromuscular function.

Cold-water immersion decreases cerebral oxygenation but improves recovery after intermittent-sprint exercise in the heat

This study examined the effects of post-exercise cooling on recovery of neuromuscular, physiological, and cerebral hemodynamic responses after intermittent-sprint exercise in the heat. Nine participants underwent three post-exercise recovery trials, including a control (CONT), mixed-method cooling (MIX), and cold-water immersion (10 °C; CWI). Voluntary force and activation were assessed simultaneously with cerebral oxygenation (near-infrared spectroscopy) pre- and post-exercise, post-intervention, and 1-h and 24-h post-exercise. Measures of heart rate, core temperature, skin temperature, muscle damage, and inflammation were also collected. Both cooling interventions reduced heart rate, core, and skin temperature post-intervention (P < 0.05). CWI hastened the recovery of voluntary force by 12.7 ± 11.7% (mean ± SD) and 16.3 ± 10.5% 1-h post-exercise compared to MIX and CONT, respectively (P < 0.01). Voluntary force remained elevated by 16.1 ± 20.5% 24-h post-exercise after CWI compared to CONT (P < 0.05). Central activation was increased post-intervention and 1-h post-exercise with CWI compared to CONT (P < 0.05), without differences between conditions 24-h post-exercise (P > 0.05). CWI reduced cerebral oxygenation compared to MIX and CONT post-intervention (P < 0.01). Furthermore, cooling interventions reduced cortisol 1-h post-exercise (P < 0.01), although only CWI blunted creatine kinase 24-h post-exercise compared to CONT (P < 0.05). Accordingly, improvements in neuromuscular recovery after post-exercise cooling appear to be disassociated with cerebral oxygenation, rather reflecting reductions in thermoregulatory demands to sustain force production.

Molecular dynamics investigation on edge stress and shape transition in graphene nanoribbons

Graphene nanoribbon (GNR) with free edges demonstrates unique pre-existing edge energy and edge stress, leading to non-flat morphologies. Using molecular dynamics (MD) methods, we evaluated edge energies as well as edge stresses for four different edge types, including regular edges (armchair and zigzag), armchair edge terminated with hydrogen and reconstructed armchair. The results showed that compressive stress exists in the regular and hydrogen-terminated edges along the edge direction. In contrast, the reconstructed armchair edge is generally subject to tension. Furthermore, we also investigated shape transition between flat and rippled configurations of GNRs with different free edges. It was found that the pre-existing stress at free edges can greatly influence the initial energy state and the shape transition.