The use of three-dimensional conjugate CFD to enhance understanding of, and to verify, multi-modal heat transfer in dynamic laboratory test walls

This work describes the use of conjugate computational fluid dynamics (C-CFD) to simulate controlled laboratory based dynamic heat transfer tests on building components. This study proposes that conjugate CFD simulation can be used to evaluate the influence of combined convective and conductive heat transfer in multi-state building components. To this end, a solid wall and cavity wall were tested with a Calibrated Hotbox and subject to variable temperature conditions leading to combined convective and conductive heat transfer. The varying temperature of the heat source was monitored and used as the input boundary condition in the simulation model, which included a computational domain which encompassed the hot-side air chamber and the wall, including cavity when applicable. It was found acceptable accuracy could be realized with a simplified constant surface heat transfer coefficient with fixed air temperature on the cold air side, which greatly reduced computational effort. The experimental results revealed that the cavity wall experienced a phase lag, peak displacement of 2.9 times higher and decrement factor 1.6 times lower compared with that of the solid wall

Effects of Multiple Bouts of Long-duration Hindlimb Unloading and Recovery on Rat Plantaris Muscle

Exposure to microgravity results in a rapid reduction of muscle mass. However, few studies exist designed to examine the effects of multiple long-term exposures to microgravity with alternating recovery periods on skeletal muscle. To determine what happens to the recovery of skeletal muscle when faced with subsequent unloading and recovery periods. Male Sprague-Dawley (6 mo) were assigned to the following groups as shown in figure 1 below: 28d hindlimb unloading (1HU), 28d HU session followed by a 56d recovery bout of normal cage ambulation at 1g (1HU+REC), 2 cycles of 28d HU with a 56d recovery period between unloadings (2HU), 2 cycles of 28d HU as in the 2HU group, but followed by an additional 56d recovery at 1g (2HU+REC), and an age- and housing-matched control group (CON). On the final day of the experimental period, plantaris muscles were excised and weighed. The 1HU+REC (0.548 ± 0.012), 2HU+REC (0.562 ± 0.015), and CON (0.550 ± 0.013) showed no statistical difference (p\u3e0.05) between each other. The 1 HU (0.442 ± 0.020) and 2 HU (0.431 ± 0.011) groups were significantly less (p\u3c0.001) than recovery and aged control animals but were not significantly different from each other. The results show that the plantaris muscle presented reduction of muscle mass with initial and subsequent exposures to microgravity. However, with the recovery period, animals were able to regain lost muscle mass, similar to age-matched controls. These findings would be relevant for astronauts participating in multiple long-duration missions throughout their career

Seeking the Ultraviolet Ionizing Background at z~3 with the Keck Telescope

We describe the initial results of a deep long-slit emission line search for redshifted (2.7<z<4.1) Lyman-alpha. These observations are used to constrain the fluorescent Ly-alpha emission from the population of clouds whose absorption produces the higher-column-density component of the Ly-alpha forest in quasar spectra. We use the results to set an upper limit on the ultraviolet ionizing background. Our spectroscopic data obtained with the Keck II telescope at lambda/(Delta lambda FWHM)~2000 reveals no candidate Ly-alpha emission over the wavelength range of 4500-6200 Ang along a 3 arcmin slit in a 5400 s integration. Our 3 sigma upper bound on the mean intensity of the ionizing background at the Lyman limit is J(nu 0) < 2E-21 erg/s/cm**2/Hz/sr for 2.7<z<3.1 (where we are most sensitive), assuming Lyman limit systems have typical radii of 70 kpc (q_0=0.5, H_0=50 km/s/Mpc). This constraint is more than an order of magnitude more stringent than any previously published direct limit. However, it is still a factor of three above the ultraviolet background level expected due to the integrated light of known quasars at z~3. This pilot study confirms the conclusion of Gould \& Weinberg (1996) that integrations of several hours on a 10-m class telescope should be capable of measuring J(nu 0) at high redshift.Comment: 22 pages, 2 postscipt figures. Latex requires aaspp4.sty and epsf.sty (included). Accepted for publication in the Astronomical Journal (Nov 1998

Effects of Voluntary Resistance Exercise Training During Recovery From Hindlimb Unloading on Rat Gastrocnemius Muscle

As research continues to examine the deleterious impact of long-duration spaceflight on human muscle mass and function, there remain gaps in our knowledge of muscle physiology, especially in examining how muscle’s ability to recover or rehabilitate from unloading may alter the results of multiple exposures to microgravity followed by 1g recovery. The purpose of this study was to analyze the effects of resistance exercise training of gastrocnemius muscle mass and anabolism during the initial recovery period immediately following a bout of unloading, as well as to examine the role that exercise may have on a subsequent period of weightlessness. This was achieved in rodent models of simulated spaceflight (0g), recovery (1g), and resistance training (\u3e1g) using male Sprague-Dawley (6 mo) rats randomly assigned to the following groups: 28d hindlimb unloading (HU), 28d HU followed by a 56d recovery period of normal cage ambulation at 1g (1HU+REC), 2 cycles of 28d HU with a 56d recovery period between unloading (2HU), 2HU followed by an additional 56d recovery at 1g (2HU+REC), or an age- and housing-matched control group (CON). In addition, following the initial 28d HU period, two groups of animals were given 7d recovery at 1g followed by a 7wk (3 sessions/wk) moderate-intensity, moderate-volume voluntary resistance exercise program (EX) in which the animals were trained to perform a squat-like motion with full extension of the lower limb and resistance was applied incrementally by weighted pouches over the scapula to ~65% bodyweight. At the conclusion of the experiments, gastrocnemius muscles were carefully excised, weighed, and evaluated for cumulative (24h) rates of protein synthesis (FSR). Values of both muscle mass and FSR were lower than control during periods of unloading (p\u3c0.05), but with recovery, control values were reached for mass and surpassed for FSR. Interestingly, there was no significant difference between the mass of 2HU and 2HU+EX (p\u3e0.05), and both were diminished in comparison to control animals, suggesting that benefits of exercise during periods of ambulatory reloading after disuse/microgravity may not be additive. In conclusion, our data suggest that given adequate recovery, microgravity-induced losses of muscle mass can be fully restored to control values, and this adaptational response persists even with multiple exposures. These findings may have important implications not only for career astronauts, but also for individuals who have been subjected to casting of a limb or a period of bed rest following severe injury or illness

Chemiluminescence from reactions with bis-cyclometalated iridium complexes in acidic aqueous solution

Chemical reactions between certain bis-cyclometalated iridium complexes, cerium(IV) and organic reducing agents in aqueous solution produce an emission of light which in some cases is more intense than that from analogous reactions with conventional ruthenium-based reagents, thus providing a new avenue for chemically-initiated luminescence detection.<br /

Vortex Shedding in a Tandem Circular Cylinder System With a Yawed Downstream Cylinder,”

This investigation examines the flow produced by a tandem cylinder system with the downstream cylinder yawed to the mean flow direction. The yaw angle was varied from a ¼ 90 deg (two parallel tandem cylinders) to a ¼ 60 deg; this has the effect of varying the local spacing ratio between the cylinders. Fluctuating pressure and hot-wire measurements were used to determine the vortex-shedding frequencies and flow regimes produced by this previously uninvestigated flow. The results showed that the frequency and magnitude of the vortex shedding varies along the cylinder span depending on the local spacing ratio between the cylinders. In all cases the vortex-shedding frequency observed on the front cylinder had the same shedding frequency as the rear cylinder. In general, at small local spacing ratios the cylinders behaved as a single large body with the shear layers separating from the upstream cylinder and attaching on the downstream cylinder, this caused a correspondingly large, low frequency wake. At other positions where the local span of the tandem cylinder system was larger, small-scale vortices began to form in the gap between the cylinders, which in turn increased the vortex-shedding frequency. At the largest spacings, classical vortex shedding persisted in the gap formed between the cylinders, and both cylinders shed vortices as separate bodies with shedding frequencies typical of single cylinders. At certain local spacing ratios two distinct vortex-shedding frequencies occurred indicating that there was some overlap in these flow regimes

DEPTOR Expression Correlates with Muscle Protein Synthesis

Mammalian target of rapamycin (mTOR) has long been declared a focal point of muscle protein synthesis. mTORC1 (an mTOR complex consisting of mTOR, raptor, PRAS40, and mLST8) has been associated with regulation of protein translation in muscle, altering expression and activity levels of key downstream targets S6K1 and eIF-4E-BP1. mTORC1 has been shown to be affected by various stimuli, including nutritional status, growth factors, and mechanical loading. But in past incidents we have found disconnects in muscle protein synthesis and mTOR signaling, stimulating discussions that mTOR content and activation alone may not be able to fully account for muscle protein synthesis. Gaining popularity as a target for anti-cancer therapies, we became interested in DEPTOR, an endogenous inhibitor of mTORC1. Pharmacological inhibition of DEPTOR in cell culture and mouse studies has displayed increases of anabolic signaling in response to atrophic circumstances. We present two unique catabolic conditions in which we explore DEPTOR expression and muscle protein synthesis and demonstrate the first known data proposing that DEPTOR expression is not only influenced by physiological stimuli, including mechanical loading and insulin sensitivity, but that DEPTOR expression strongly correlates with 24-hr cumulative muscle protein synthesis rates. In one study, male Sprague Dawley rats were subjected to various conditions of musculoskeletal unloading, reloading, and overload, in which hindlimb unloading (HU) was utilized to mimic chronic disuse atrophy (28-d), followed by ambulatory reloading (56-d post HU) with and without the addition of resistance exercise prescribed to assist in recovery (3 sessions/wk for 7-wks; progressive increases in added resistance up to ~60% BW). DEPTOR expression was assessed via Immunoblotting. 24-hr cumulative muscle protein synthesis (FSR) was measured via stable isotope labeling and quantified by gas chromatogram/mass spectrometry. DEPTOR demonstrated a strong negative correlation with FSR in the gastrocnemius (r = - 0.93261; p \u3c0.01). In our second study, male obese Zucker rats were divided into their lean and obese phenotypes, as well as placed into sedentary and resistance exercised groups. DEPTOR and FSR were assessed as described above following operant conditioning and four progressive exercise sessions over 9-d. Gastrocnemius DEPTOR/FSR was again significant (r = - 0.75723; p\u3c0.01). Collectively, these results are the first to associate physiologic changes in DEPTOR expression with alterations of FSR, which may have important implications towards the design of therapeutic targets for the control of muscle mass or in evaluating muscle anabolism

The significance of motivation in student-centred learning : a reflective case study

The theoretical underpinnings of student-centred learning suggest motivation to be an integral component. However, lack of clarification of what is involved in motivation in education often results in unchallenged assumptions that fail to recognise that what motivates some students may alienate others. This case study, using socio-cognitive motivational theory to analyse previously collected data, derives three fuzzy propositions which, collectively, suggest that motivation interacts with the whole cycle of episodes in the teachinglearning process. It argues that the development of the higherlevel cognitive competencies that are implied by the term, student-centred learning, must integrate motivational constructs such as goal orientation, volition, interest and attributions into pedagogical practices

Foundations of character: methodological aspects of a study of character development in three- to six-year-old children with a focus on sharing behaviours

This article focuses on methodological issues arising in a study of character development, using illustrations of ‘sharing behaviours.’ Based primarily in six early years settings in southeast England the research records naturalistic observations of peer interactions for 55 children aged three to six years. Applying grounded theory to the processes of observing, analysing and interpreting evidence required a cautious and collectively reflective approach. The methodology sought to moderate the influence of the researchers' prior knowledge of ‘grand theories’ of moral development and assumptions about relevance to the observation records. The study's originality lay in the exploration of moral development without reference to any particular grand theory as an explanatory framework; and in the reluctance to be drawn to potentially simplistic rationalisations of the children's intentions on the basis of their observed behaviours. Exploring young children's subjective experiences, this research provides insights into the intricacy of this process, steering away from ‘neat’ findings and attempting to reflect the sophistication of the children's skilful and sometimes surprising negotiations of moral dilemmas. Implications for practice relate to the complexities involved in attempts to unravel the developing moral characters of young children and the practice through which this may be nurtured