Pathway to health: Cluster-randomized trail to increase fruit and vegetable consumption among smokers in public housing.

Objectives: Examine the effectiveness of an intervention to increase fruits and vegetables (FV) consumption among smokers. Design: Cluster-randomized trial of 20 public housing developments; 10 randomly assigned to an FV intervention and 10 to a smoking cessation intervention. Main outcome measures: Usual (past 7 days) and past 30 days change in daily FV intake at 8 weeks and 6 months postbaseline. Results: Greater increases were seen in the FV group. At Week 8 and Month 6, the FV group had consumed 1.58 (p = .001) and 0.78 (p = .04), respectively, more daily FV servings in the past 7 days than the cessation group. At the same time points, the FV group had consumed 3.61 (p = .01) and 3.93 (p = .01), respectively, more FV servings in the past 30 days than the cessation group. Completing more motivational interviewing sessions (p = .02) and trying more recipes (p = .02) led to significantly greater increases at Month 6 among FV participants. Conclusions: Motivational interviewing counseling and lifestyle modification through trying out healthy recipes may be effective in helping a high-risk population increase their FV intake. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Cyclic variation of the power of ultrasonic Doppler signalsbackscattered by polystyrene microspheres and porcine erythrocytesuspensions

Factors affecting the power of the ultrasonic Doppler signal within the flow cycle have been evaluated experimentally using a pulsatile flow loop model. Polystyrene microspheres and porcine red cells suspended in saline solution for hematocrits between 2 and 40% were used as scattering fluid in the flow model. Experiments were performed at mean flow velocities of 11, 64, and 76 cm/s. In laminar flow experiments performed at a mean velocity of 11 cm/s, no variation of the Doppler power was found for both polystyrene microspheres and red cell suspensions (40% hematocrit). When turbulence was induced in the flow model, the power increasing during systole, a maximum was observed early after peak systole, and a decrease was obtained in diastole during deceleration of flow     

Effect of various parameters on the level of mixing in continuous flow systems

Variations of the level of mixing in a flow system have been investigated as a function of the following parameters: diameter, shape and speed of the agitator, feed rate and position of the feed inlet. At agitator speeds inferior to a critical value, a minimum level of mixing is observed which depends on the position of the feed inlet. At speeds superior to the critical value, the level of mixing increases linearly with agitator speed, at a given feed rate, until conditions of perfect mixing are reached. The critical agitator speed and the position of each straight line depend on the agitator size. A modified Reynolds number makes possible a more general correlation. At a given agitator speed, superior to the critical value, the level of mixing decreases as the feed rate increases, due to the smaller amount of energy imparted by the agitator per unit mass of feed. The effect of agitator shape on the level of mixing is rather pronounced as it affects the flow patterns inside the reservoir.     

Hysteresis‐Free 1D Network Mixed Halide‐Perovskite Semitransparent Solar Cells

The morphology of hybrid organic–inorganic perovskite films is known to strongly affect the performance of perovskite‐based solar cells. CH₃NH₃PbI_3‐xCl_x (MAPbI_3‐xCl_x) films have been previously fabricated with 100% surface coverage in glove boxes. In ambient air, fabrication generally relies on solvent engineering to obtain compact films. In contrast, this work explores the potential of altering the perovskites microstructure for solar cell engineering. This work starts with CH₃NH₃PbI_3‐xCl_x, films with grain morphology carefully controlled by varying the deposition speed during the spin‐coating process to fabricate efficient and partially transparent solar cells. Devices produced with a CH₃NH₃PbI_3‐xCl_x film and a compact thick top gold electrode reach a maximum efficiency of 10.2% but display a large photocurrent hysteresis. As it is demonstrated, the introduction of different concentrations of bromide in the precursor solution addresses the hysteresis issues and turns the film morphology into a partially transparent interconnected network of 1D microstructures. This approach leads to semitransparent solar cells with negligible hysteresis and efficiencies up to 7.2%, while allowing average transmission of 17% across the visible spectrum. This work demonstrates that the optimization of the perovskites composition can mitigate the hysteresis effects commonly attributed to the charge trapping within the perovskite film.     

Experimental evaluation of intrinsic and nonstationary ultrasonic Doppler spectral broadening in steady and pulsatile flow loop models

Intrinsic and nonstationary Doppler spectral broadening, and the skewness of the spectral representation, were evaluated experimentally using porcine red cell suspensions as ultrasonic scatterers. Theoretically, the relative Doppler bandwidth, defined as the intrinsic bandwidth divided by the mean Doppler frequency shift, should be velocity independent. The relative Doppler bandwidth invariance theorem was experimentally verified with an in vitro steady laminar blood flow model. It is shown that the relative bandwidth is both independent of the flow velocity and blood hematocrit. Using a pulsatile laminar flow model, the authors demonstrated that the relative Doppler bandwidth invariance theorem did not hold during flow acceleration and deceleration. In addition, a positive skewness of the Doppler spectra was observed during acceleration while a negative skewness was measured during the deceleration of blood. The effect of the window duration used in the Fourier spectral computation, on nonstationary broadening, is characterized.     

Nonlinear inverse optimization approach for determining the weights of objective function in standing reach tasks

This paper presents a nonlinear inverse optimization approach to determine the weights for the joint displacement function in standing reach tasks. This inverse optimization problem can be formulated as a bi-level highly nonlinear optimization problem. The design variables are the weights of a cost function. The cost function is the weighted summation of the differences between two sets of joint angles (predicted posture and the actual standing reach posture). Constraints include the normalized weights within limits and an inner optimization problem to solve for joint angles (predicted standing reach posture). The weight linear equality constraints, obtained through observations, are also implemented in the formulation to test the method. A 52 degree-of-freedom (DOF) human whole body model is used to study the formulation and visualize the prediction. An in-house motion capture system is used to obtain the actual standing reach posture. A total of 12 subjects (three subjects for each percentile in stature of 5th percentile female, 50th percentile female, 50th percentile male and 95th percentile male) are selected to run the experiment for 30 tasks. Among these subjects one is Turkish, two are Chinese, and the rest subjects are Americans. Three sets of weights for the general standing reach tasks are obtained for the three zones by averaging all weights in each zone for all subjects and all tasks. Based on the obtained sets of weights, the predicted standing reach postures found using the direct optimization-based approach have good correlation with the experimental results. Sensitivity of the formulation has also been investigated in this study. The presented formulation can be used to determine the weights of cost function within any multi-objective optimization (MOO) problems such as any types of posture prediction and motion prediction.     

How drivers decide whether to get a fuel cell vehicle: An ethnographic decision model

This article develops and tests an ethnographic decision model (EDM) of hydrogen fuel cell vehicle (FCV) adoption using interviews with California residents that either actually adopted an FCV or “seriously considered” doing so before deciding against it. We developed an initial model from 25 semi-structured interviews in which respondents self-described their decision-making processes. We iteratively tested and refined the model in a second round of 53 structured interviews. The final model consists of a first stage that assesses FCV adoption feasibility and a second stage that compares FCVs to other vehicle types. The model ultimately correctly predicts 86.8% of cases in the sample. In the first stage, respondents preferred to satisfy their need for a primary refueling station near home but a substantial number were willing to rely on a station near or on the way to work or other destination. Most drivers required a convenient backup station and a means of managing long-distance trips. Vehicle size options eliminated a few respondents. None rejected FCV adoption due to insufficient driving range. In the second stage, nearly all drivers engaged in some kind of cost comparison, though the factors considered varied greatly. Most opted for what they viewed as the less costly option, although a few FCV adopters and non-adopters were willing to pay more for their more preferred option. EDM is a promising qualitative research method for generating insights into how people navigate the decision whether or not to get an alternative-fuel vehicle.     

Use of Sb spray for improved performance of InAs/GaAs quantum dots for novel photovoltaic structures

Photoluminescence output from InAs/GaAs quantum dots has been improved by a Sb treatment immediately prior to capping with GaAs. Spectra taken at 300 and 80 K show a significant increase in output intensity when the quantum dots are exposed for 15 s under a Sb flux of approximately 0.1 monolayers per second, but this improvement is lost when the Sb exposure is extended to 30 s. There is no significant shift in the emission energies between samples indicating strain relief due to the cap layer is not responsible for the improvement. Analysis of temperature dependent photoluminescence taken between 80 and 300 K show increased activation energies at lower temperatures when an Sb spray is used, suggesting passivation of deep defect levels. For the higher temperature activation energy, corresponding to carrier escape from the QD to the barrier, whilst a 15 s Sb spray gives a substantial increase, the longer 30 s Sb spray sees the activation energy decrease, a result deduced to be due to Sb segregation providing shallow defect levels. A band structure including a very thin GaAsSb layer adjacent to the quantum dots is used to explain these results, with the 30 s Sb spray leading to shallow Sb segregation related defects and a lower activation energy. Depth dependent X-ray photoelectron spectroscopy data support the band structure proposed to explain the photoluminescence results and also reveals the highest concentration of Sb at the sample surface suggesting a ‘floating layer’ of Sb during growth of the GaAs cap. Some of the implications of these results, for growth of quantum dot samples and for two novel solar cell proposals, the intermediate band and hot carrier solar cells, are discussed.