2,708 research outputs found
Maternal Diet, Breast Feeding and Infants' Growth: A fieldstudy in the Ivory Coast (West Africa)
Four mothers and their infants living in a rural village of the Ivory Coast were studied for maternal diet, breast milk composition and volume and infants' growth over an 18 months' period. Two of the mothers were young, had a low calorie intake and gave little supplementary nourishment to their infants; these infants had an unsatisfactory growth pattern. Two mothers were middle-aged, had a satisfactory calorie intake and their infants thrived well on breast milk alone for the first 6 months. Supplements were introduced by those mothers after their infant was 6 months old which provided adequate energy and protein intake and had a beneficial effect on the growth of the infants. Detailed biochemical analyses of diets and breast milk have been performed and dietary allowances are discussed in the light of the present results. Despite important differences in dietary intake the milks produced by the four mothers showed no significant differences in biochemical composition. The mothers with low calorie and low protein intake produced however smaller quantities of breast milk when the infants were 4 to 7 months old. Since breast milk provides a substantial amount of protein and calories for the infants even in late lactation, the implication with regard to adequate growth of the infants is to provide adequate dietar
NASA aviation safety reporting system
The origins and development of the NASA Aviation Safety Reporting System (ASRS) are briefly reviewed. The results of the first quarter's activity are summarized and discussed. Examples are given of bulletins describing potential air safety hazards, and the disposition of these bulletins. During the first quarter of operation, the ASRS received 1464 reports; 1407 provided data relevant to air safety. All reports are being processed for entry into the ASRS data base. During the reporting period, 130 alert bulletins describing possible problems in the aviation system were generated and disseminated. Responses were received from FAA and others regarding 108 of the alert bulletins. Action was being taken with respect to 70 of the 108 responses received. Further studies are planned of a number of areas, including human factors problems related to automation of the ground and airborne portions of the national aviation system
Retrospective studies of operating problems in air transport
An epidemiological model for the study of human errors in aviation is presented. In this approach, retrospective data are used as the basis for formulation of hypotheses as to system factors which may have contributed to such errors. Prospective experimental studies of aviation operations are also required in order to prove or disprove the hypotheses, and to evaluate the effectiveness of intervention techniques designed to solve operational problems in the aviation system
Simulation studies of air transport operational problems
An experimental evaluation of the monitored approach procedure for conducting low visibility instrument approaches is described. Four airline crews each flew 16 approaches using the monitored procedure and 16 using a modified standard procedure in a DC-10 simulator under various conditions of visibility, wind shear and turbulence, and radar vectoring scenarios. In terms of system measures of aircrew performance, no major differences were found. Pilot opinion data indicate that there are some desirable characteristics of the monitored procedure, particularly with reference to the increased role of the flight engineer in conducting low visibility approaches. Rationale for developing approach procedures is discussed
The joint US/UK 1990 epoch world magnetic model
A detailed summary of the data used, analyses performed, modeling techniques employed, and results obtained in the course of the 1990 Epoch World Magnetic Modeling effort are given. Also, use and limitations of the GEOMAG algorithm are presented. Charts and tables related to the 1990 World Magnetic Model (WMM-90) for the Earth's main field and secular variation in Mercator and polar stereographic projections are presented along with useful tables of several magnetic field components and their secular variation on a 5-degree worldwide grid
Veteran Participation in Operation Song: Exploring Resiliency in a Songwriting Experience
This study takes a phenomenological approach to explore the experience of Operation Song, a United States nonprofit organization’s songwriting program for military veterans with posttraumatic stress disorder (PTSD). Six participants completed semi-structured interviews to identify the structural, textural, and composite descriptions of the Operation Song experience. Findings were analyzed through an interpretive phenomenological analysis, which led to themes describing the essence as a “catalyst to invoke personal change.” When restructured for this article, original key themes describing the overall experience were reestablished as a setting that promoted authenticity, trusted social support, uniquely skilled songwriters, songwriting, and listening to the songs. Through a review of the biopsychosocial impacts of trauma and resiliency factors, this study offers a unique outlook supporting social and creative experiences as complementary mechanisms to enhance treatment outcomes for military veterans with PTSD
Control in the technical societies: a brief history
By the time control engineering emerged as a coherent body of knowledge and practice (during and just after WW2) professional engineering societies had existed for many decades. Since control engineering is an interdisciplinary branch of the profession, new sections devoted to control were quickly established within the various existing technical societies. In addition, some new bodies devoted specifically or primarily to control were established. This article, a revised version of a paper presented at the IEEE 2009 Conference on the History of Technical Societies, describes how control engineering as a distinct branch of engineering became represented in technical societies in a number of countries
Cooperative Scattering by Cold Atoms
We have studied the interplay between disorder and cooperative scattering for
single scattering limit in the presence of a driving laser. Analytical results
have been derived and we have observed cooperative scattering effects in a
variety of experiments, ranging from thermal atoms in an optical dipole trap,
atoms released from a dark MOT and atoms in a BEC, consistent with our
theoretical predictions.Comment: submitted for special issue of PQE 201
Constructal alkaline membrane fuel cell (AMFC) design
This paper introduces a structured procedure to optimize the internal structure (relative sizes, spacing) and external shape (aspect ratios) of a single alkaline membrane fuel cell so that net power is maximized. The optimization of flow geometry is conducted for the smallest (elemental) level of a fuel cell stack, i.e., the single alkaline membrane fuel cell, which is modeled as a unidirectional flow system. The polarization curve, total and net power, and efficiency are obtained as functions of temperature, pressure, electrolyte solution concentration (KOH), geometry and operating parameters. The optimization is subjected to fixed total volume. There are two levels of optimization: (i) the internal structure, which basically accounts for the relative thicknesses of two reaction and diffusion layers and the membrane space, and (ii) the external shape, which accounts for the external aspect ratios of a square section plate that contains all single alkaline membrane fuel cell components. The available volume is distributed optimally through the system so that the net power is maximized. Temperature and pressure gradients play important roles, especially as the fuel and oxidant flow paths increase. The optimized internal structure and external shape are a result of an optimal balance between electrical power output and pumping power required to supply fuel and oxidant to the fuel cell through the gas channels. In the process, a third level of optimization was found with respect to the KOH concentration in the electrolyte solution that leads to a 3-way maximized net power output. The numerical results show that the maxima found are sharp, since a variation of up to 600% in net power was observed within the tested range of AMFC external aspect ratios, what emphasizes the importance of finding the optimal AMFC parameters, no matter how complex the actual design might be. It is also shown that the three times maximized net power increases monotonically with total volume raised to the power 0.7 (~3/4), similarly to metabolic rate and mass in animal design. Due to the fact that precision and low computational time are combined, it is expected that the model could be used as an important tool for AMFC design, control and optimization at the fuel cell stack level
- …