Prices, Asset Markets and Indeterminacy

Competitive equilibrium allocations are indeterminate when the net trades in commodities are constrained, while the asset market is incomplet

Effect of aerobic capacity on Lower Body Negative Pressure (LBNP) tolerance in females

This investigation determined whether a relationship exists in females between: (1) aerobic capacity and Lower Body Negative Pressure (LBNP); and (2) aerobic capacity and change in LBNP tolerance induced by bed rest. Nine females, age 27-47 (34.6 plus or minus 6.0 (Mean plus or minus SD)), completed a treadmill-graded exercise test to establish aerobic capacity. A presyncopal-limited LBNP test was performed prior to and after 13 days of bed rest at a 6 deg head-down tilt. LBNP tolerance was quantified as: (1) the absolute level of negative pressure (NP) tolerated for greater than or equal to 60 sec; and (2) Luft's Cumulative Stress Index (CSI). Aerobic capacity was 33.3 plus or minus 5.0 mL/kg/min and ranged from 25.7 to 38.7. Bed rest was associated with a decrease in NP tolerance (-9.04 1.6 kPa(-67.8 plus or minus 12.0 mmHg) versus -7.7 1.1 kPa(-57.8 plus or minus 8.33 mmHg); p = 0.028) and in CSI (99.4 27.4 kPa min(745.7 plus or minus 205.4 mmHg min) versus 77.0 16.9 kPa min (577.3 plus or minus mmHg min); p = 0.008). The correlation between aerobic capacity and absolute NP or CSI pre-bed rest did not differ significantly from zero (r = -0.56, p = 0.11 for NP; and r = -0.52, p = 0.16 for CSI). Also, no significant correlation was observed between aerobic and pre- to post-rest change for absolute NP tolerance (r = -0.35, p = 0.35) or CSI (r = -0.32, p = 0.40). Therefore, a significant relationship does not exist between aerobic capacity and orthostatic function or change in orthostatic function induced by bed rest

Prices, Asset Markets and Indeterminacy

Competitive equilibrium allocations are indeterminate when the net trades in commodities are constrained, while the asset market is incomplete.Incomplete asset market, trading constraints, indeterminacy

T-mixer operating with water at different temperatures: Simulation and stability analysis

In this paper we investigate the transition from the vortex to the engulfment regime in a T-mixer when the two entering flows have different viscosity. In particular we consider as working fluid water entering the two inlet channels of the mixer at two different temperatures. Contrary to the isothermal case, at low Reynolds numbers the vortex regime shows only a single reflectional symmetry, due to the nonhomogeneous distribution of the viscosity. Increasing the Reynolds number, a symmetry-breaking bifurcation drives the system to a new steady flow configuration, usually called the engulfment regime, similar to what it is possible to observe in an isothermal case. This flow regime is associated with an increase of the mixing between the two inlet streams. It is shown by direct numerical simulation (DNS) and by stability analysis that the engulfment regime is promoted by the temperature difference. Starting from the DNSs, the resulting flow fields are analyzed in detail considering different temperature jumps between the two inlet boundaries. Furthermore, dedicated linear stability analyses are carried out to investigate the instability mechanism associated with the occurrence of the engulfment regime. In particular, similarly to the case without temperature differences, the onset of engulfment is driven by the momentum equation, and the temperature field does not lead to any additional instability mechanism. However, the existence of a temperature field leads to quantitative changes of the stability characteristics and of the resulting flow fields via a variation of the viscosity coefficient

EXISTING-BIM: INTEGRATED SURVEY PROCEDURES FOR THE MANAGEMENT OF MODERN ARCHITECTURE

Abstract. This paper is aimed at illustrating the operation workflow to create a BIM model of an existing building, by highlighting its process starting from photogrammetric acquisitions and indicating its critical elements as regards data structure and the following modeling. The subject of this study is a reinforced concrete building of the 1960s on six levels. At present, it is undergoing an extensive refurbishment with the purpose of converting its original function, from the US Navy Hospital into offices. Since it was possible to access archive documents concerning the executive design and to carry out even invasive surveys for acquiring specific data about building details, BIM modeling could refer to a significant amount of qualitative and quantitative data. This circumstance characterized the work steps of a BIM modeling which, although referred to an existing building, may also be applied to new constructions. Building technology has implicitly facilitated the identification of the constructive elements and the creation of a list, although the unusual shape of the structure has caused specific problems differently discussed and documented in the text.</p

Boundary layer stabilization using free-stream vortices

In this numerical investigation we explore the possibility of applying free-stream vortices as a passive flow control method for delaying the transition to turbulence. The work is motivated by previous experimental studies demonstrating that stable streamwise boundary layer (BL) streaks can attenuate both two- and three-dimensional disturbances inside the BL, leading to transition delay, with the implication of reducing skin-friction drag. To date, successful control has been obtained using physical BL modulators mounted on the surface in order to generate stable streaks. However, surface mounted BL modulators are doomed to failure when the BL is subject to free-stream turbulence (FST), since a destructive interaction between the two is inevitable. In order to tackle free-stream disturbances, such as FST, a smooth surface is desired, which has motivated us to seek new methods to induce streamwise streaks inside the BL. A first step, in a systematic order, is taken in the present paper to prove the control idea of generating free-stream vortices for the attenuation of ordinary Tollmien–Schlichting waves inside the BL. In this proof-of-concept study we show that, by applying a spanwise array of counter-rotating free-stream vortices, inducing streamwise BL streaks further downstream, it is possible to alter the BL stability characteristics to such a degree that transition delay may be accomplished. For the demonstration we use direct numerical simulations along with stability analysis

Stability analysis of boundary layers controlled by miniature vortex generators

It is currently known that Tollmien–Schlichting (TS) waves can be attenuated by the introduction of spanwise mean velocity gradients in an otherwise two-dimensional boundary layer (BL). The stabilizing effect, associated with an extra turbulence production term, is strong enough to obtain a delay in transition to turbulence induced by TS waves, with the implication of reducing skin-friction drag. Miniature vortex generators (MVGs), mounted in an array, have successfully been used to obtain velocity modulations by the generation of alternating high- and low-speed streaks in the spanwise direction to control the BL. Experimentally, an initial amplification of the TS waves has been reported, which takes place in the near-wake region of the MVG array. The higher the streak amplitude, the stronger the downstream stabilizing effect becomes, but with the drawback of experiencing an even stronger initial amplification. This can lead to a sub-critical transitional Reynolds number, which would not only mean that the control has failed but, even worse, also lead to an advancement of the transition location. Here, direct numerical simulations and a local spatial stability analysis have been performed in order to reach a deeper understanding of this behaviour. The results agree well with experiments and we propose an explanation of the described behavior in terms of stability properties of the controlled BL. This important knowledge can be used in future designs of BL modulators, which can lead to improved stability of the control and to an extended region of laminar flow

Carbon dioxide and water vapor production at rest and during exercise. A report on data collection for the Crew and Thermal Systems Division

The current environmental control device in the shuttle uses lithium hydroxide (LiOH) filter canisters to remove carbon dioxide (CO2) from the cabin air, requiring several bulky filter canisters that can only be used once and must be changed frequently. To alleviate a stowage problem and decrease launch weight, the Crew and Thermal Systems Division (CTSD) at the NASA Johnson Space Center has been researching a system to be used on future shuttle missions. This system uses two beds of solid amine material to absorb CO2 and water, later desorbing them to space vacuum. In this way the air scrubbing medium is regenerable and reusable. To identify the efficacy of this regenerable CO2 removal system (RCRS), CTSD began investigations in the shuttle mockup. The purpose of this investigation was to support the CTSD program by determining mean levels of carbon dioxide and water vapor production in normal, healthy males and females age-matched with the astronaut corps. Subjects' responses were measured at rest and during exercise at intensity levels equivalent to normal shuttle operation activities. The results were used to assess the adjustments made to RCRS and are reported as a reference for future investigations in shuttle environmental control

Urokinase Plasminogen Receptor and the Fibrinolytic Complex Play a Role in Nerve Repair after Nerve Crush in Mice, and in Human Neuropathies

Remodeling of extracellular matrix (ECM) is a critical step in peripheral nerve regeneration. In fact, in human neuropathies, endoneurial ECM enriched in fibrin and vitronectin associates with poor regeneration and worse clinical prognosis. Accordingly in animal models, modification of the fibrinolytic complex activity has profound effects on nerve regeneration: high fibrinolytic activity and low levels of fibrin correlate with better nerve regeneration. The urokinase plasminogen receptor (uPAR) is a major component of the fibrinolytic complex, and binding to urokinase plasminogen activator (uPA) promotes fibrinolysis and cell movement. uPAR is expressed in peripheral nerves, however, little is known on its potential function on nerve development and regeneration. Thus, we investigated uPAR null mice and observed that uPAR is dispensable for nerve development, whereas, loss of uPAR affects nerve regeneration. uPAR null mice showed reduced nerve repair after sciatic nerve crush. This was a consequence of reduced fibrinolytic activity and increased deposition of endoneurial fibrin and vitronectin. Exogenous fibrinolysis in uPAR null mice rescued nerve repair after sciatic nerve crush. Finally, we measured the fibrinolytic activity in sural nerve biopsies from patients with peripheral neuropathies. We showed that neuropathies with defective regeneration had reduced fibrinolytic activity. On the contrary, neuropathies with signs of active regeneration displayed higher fibrinolytic activity. Overall, our results suggest that enforced fibrinolysis may facilitate regeneration and outcome of peripheral neuropathies

The effectiveness of "Exercise on Prescription" in stimulating physical activity among women in ethnic minority groups in the Netherlands: protocol for a randomized controlled trial

<p>Abstract</p> <p>Background</p> <p>Lack of physical activity is an important risk factor for overweight, diabetes, cardiovascular disease and other chronic conditions. In the Netherlands, ethnic minority groups are generally less physically active and rate their own health poorer compared to ethnic Dutch. This applies in particular to women. For this reason women from ethnic minority groups are an important target group for interventions to promote physical activity.</p> <p>In the Netherlands, an exercise referral program ("Exercise on Prescription") seems successful in reaching women from ethnic minority groups, in particular because of referral by the general practitioner and because the program fits well with the needs of these women. However, the effect of the intervention on the level of physical activity and related health outcomes has not been formally evaluated within this population. This paper describes the study design for the evaluation of the effect of "Exercise on Prescription" on level of physical activity and related health outcomes.</p> <p>Methods</p> <p>The randomized controlled trial will include 360 inactive women from ethnic minority groups, with the majority having a non-Western background, aged between 18 and 65 years old, with regular visits to their general practitioner. Participants will be recruited at healthcare centres within a deprived neighbourhood in the city of The Hague, the Netherlands.</p> <p>An intervention group of 180 women will participate in an exercise program with weekly exercise sessions during 20 weeks. The control group (n = 180) will be offered care as usual. Measurements will take place at baseline, and after 6 and 12 months. Main outcome measure is minutes of self reported physical activity per week. Secondary outcomes are the mediating motivational factors regarding physical activity, subjective and objective health outcomes (including wellbeing, perceived health, fitness and body size) and use of (primary) health care. Attendance and attrition during the program will be determined.</p> <p>Conclusion</p> <p>This trial will provide information on the effectiveness of an exercise referral scheme on the short and long term among women from ethnic minority groups, mainly non-Western, in the Netherlands. The results of this study will contribute to the evidence base for interventions in ethnic minority populations.</p> <p>Trial registration</p> <p>Dutch Trial register: NTR1294</p