The Effects of Maternal Employment on Childhood Obesity in the United States

Childhood obesity is a growing problem in the United States. The Center for Disease Control (CDC), based on data from the National Health and Nutrition Examination Survey (NHANES), reports that from 1971 to 2004, obesity rates have increased from 5% to 13.9% among two- to five-year-olds, from 4% to 18.8% among six- to eleven-year-olds, and from 6.1% to 17.4% among twelve- to nineteen-year-olds (CDC, 2007). Increases in childhood obesity have been especially pronounced among low-income children from racial and ethnic minority groups. This vast increase in the number of obese children is a major cause for alarm because of the many health problems associated with being overweight.

Transient behavior of wind towers grounding systems under lightning strikes

Wind turbines, because of their height and localization, are frequently subject to direct lightning strikes. Thus, the investigation on the performance of their grounding system is of paramount interest for the prediction of the potential threats either for people working in (or animals passing through) the wind farm area and for the power and control units installed in close proximity of the turbine towers. In this paper,we perform a comprensive study of the transient behavior of the earthing systems of wind turbines. The analysis is conducted in the frequency domain and an hybrid approach, based on circuit theory and Method of Moments, is adopted to fully account for resistive, inductive and capacitive couplings between elements of the ground system. The actual transient behavior is obtained by means of an Inverse Fourier Transform. The results, computed considering a typical wind turbine grounding system configuration, provide more insight on the nature of the early-time transient response of grounding systems and allow to draw up useful design guidelines

Ground Transient Resistance of Underground Cables

During transients involving multiconductor lines, the importance of the ground finite conductivity is well known and various techniques and expressions have been presented in literature for the inclusion of its contribution into the per unit length parameters. The direct time domain approach based on the introduction of the transient parameters and on the numerical solution of the telegrapher's equations demonstrated to be accurate and efficient for the analysis of typical transients. In this letter, the expressions for the ground transient resistance for underground cables, based on the closed-form inverse Laplace transform of the classical Pollaczek expressions (valid for the low-frequency-range), are presented and discussed

Eco-sustainable routing of power lines for the connection of renewable energy plants to the Italian high-voltage grid

Routing of high-voltage electric transmission lines for the connection of renewable energy-distributed generation plants is a critical issue from an environmental point of view. A standard methodology that accounts for multiple perspectives, influence factors and is able to mediate between weighted constraints can be a useful tool for the regulating bodies that are involved in approval processes. The methodology can be an effective support to increase reliability, save consumers' money and mitigate the unavoidable impacts of the lines on the population living nearby. In this paper we investigate the suitability of a procedure employed by Terna, the Italian high-voltage transmission system operator, to identify the corridors where to route new overhead transmission lines with the lowest environmental impact. The methodology is based on the subdivision of all the relevant constraints dictated by environmental issues and territory legislations in four main classes. A real case study concerning the design and connection of a wind farm placed near Collarmele, in the center of Italy, shows the effectiveness of the proposed methodology

Prediction in Photovoltaic Power by Neural Networks

The ability to forecast the power produced by renewable energy plants in the short and middle term is a key issue to allow a high-level penetration of the distributed generation into the grid infrastructure. Forecasting energy production is mandatory for dispatching and distribution issues, at the transmission system operator level, as well as the electrical distributor and power system operator levels. In this paper, we present three techniques based on neural and fuzzy neural networks, namely the radial basis function, the adaptive neuro-fuzzy inference system and the higher-order neuro-fuzzy inference system, which are well suited to predict data sequences stemming from real-world applications. The preliminary results concerning the prediction of the power generated by a large-scale photovoltaic plant in Italy confirm the reliability and accuracy of the proposed approaches

Propagation characteristics of differential lines: the odd-mode impedance

New analytical expressions are proposed for the prediction of the frequency dependence of the characteristic oddmode impedance of differential interconnects. The classical microwave definition is reviewed as well as analytical formulations available in literature. A two dimensional Finite Difference Frequency Domain method is applied to compare the results and check the accuracy of the proposed expressions

Droplet separators for evaporative towers: efficiency estimation by PDA

Abstract A Phase Doppler Anemometry system has been set up to characterize the behaviour of different arrangements of static impactors that are used as drift eliminators to intercept and remove residual water droplets entrained in the hot air flow released by an evaporative tower. The investigated evaporative tower has a square section of 60x60 cm, that is the standard size for modular separation elements; it was tested while working with or without the droplet separators; for each test condition, the residual water droplets entrained by the air flow and expulsed by the tower are detected few centimetres above the tower exhaust and are characterized by the PDA system that can measure the velocity and diameter of each droplet. Many parameters describing the droplet population over the whole exit section, (number, mean velocity and diameter) can be obtained. The distribution of the droplets is calculated as a function of their diameter, and represented as a percentage of their total number and of their total volume. The velocity-diameter plot of the same droplets shows other aspect of the population. Droplets with same diameter show a spread velocity distribution due to the high turbulence of the exhaust air flow. Droplets with larger diameters have smaller mean velocity, since the gravitational downward force is not negligible compared to the aerodynamic upward drag from the air flow. Few very large droplets have even negative velocity: they are interpreted as droplets that, after the expulsion, are falling back downward. The use of an LDV-PDA system allows to detect such droplets and to discard them from the separation efficiency calculations. The efficiency can be calculated by direct comparison of the number of water droplets that are detected in the exhaust air flow, both globally or for any specific class of droplet size. Global results can be calculated on the basis of the number or of the volume of the droplets. The accuracy of the efficiency estimation is also studied. Two main aspects are considered. The first is that the PDA measurement volume dimension variation with the detected droplet size: it has negligible effect on the result per classes of diameters, but the effect on the global efficiency is present and will be discussed. The second aspect is the presence of droplets that are falling downward in the upward air flow: their presence should be considered and corrected for. The results of this paper are useful when comparing them to other measurements obtained with techniques that are not able to detect the droplet velocity

Simplified conservative testing method of touch and step voltages by multiple auxiliary electrodes at reduced distance

Grounding systems (GSs) must be tested periodically in order to maintain the touch voltage (TV) and step voltage (SV) below a safe value in all of the zones of the installation. Measurements of the ground resistance and of the TV and SV are typically done by the fall-of-potential (FoP) method, locating the auxiliary current electrode at remote distance to test the effective behavior of the GS. In urban areas, it could be very complicated or impossible to install the auxiliary current electrode as required, not having area around with sufficient accessibility. At this aim, this paper describes a methodology of using multiple current electrodes at short distances, modifying the classic FoP practice, so that the measurements of TV and SV are always conservative. The adequacy of a GS is verified if the values of the TV and SV, tested inside and in the vicinity of the GS, are below the permissible limits, regardless if they are true or conservatively increased. Thus, the measured TV and SV by the suggested method, always conservative, allow verifying the adequacy of GSs, in the cases where it is impossible to locate the remote auxiliary electrode

Nervous Salomes: New York Salomania and the Neurological Condition of Modernité

In January 1907, New York City had its first major encounter with the figure of Salome. Appearing on three large stages in the city simultaneously, the archetype of the dancing girl quickly became an object of controversy. Her appearance at the Metropolitan Opera House in its staging of Strauss’s Salome resulted in public debate and the ultimate closure of the performance by the Met’s Board of Directors. The event brought attention to the Salome archetype’s already contested character. Salome arrived in the United States from Europe where she had been the subject of a quarter century of debates about how aesthetic representations of the dancing girl were indulging the decadent and neurologically degenerate nature of modernist culture. Within the context of New York, Salome quickly became a vehicle by which U.S. culture could negotiate its own relationship to the modern experience. In the three years following the Met’s closure of its production of Strauss’s opera, the figure of Salome would appear on variety stages around the city in increasing numbers. These performances, using many of the European representations of the dancing girl as their model, embodied, I argue, a significant number of the neuropathological traits that were proving so threatening to western culture. This dissertation examines this explosion of Salome performances in New York from 1907 to 1909. It looks to how in their performative celebration of the archetype of the dancing girl they engaged new medical models of neurological impairment circulating at the time. The chapters in this dissertation illuminate what I see as the process by which the archetype of Salome became increasingly neuropathologized. In chapter one, I position the dancing girl inside a modernist landscape where neurological concepts were freely circulating. I do so by examining how changes to individual experiences with the physical and social environments of modern life coincided with the rise of neurology as a medical sub-discipline. In chapter two, I provide a preliminary discussion of the Salome phenomenon in New York, what has come to be known as the city’s period of Salomania. This is followed by an explication of how the modernist archetype that became so popular in the city gained its neuropathological character. To do so, I look to the archetype’s fin de siècle past in Europe. The final chapter examines more closely the dynamics of New York’s Salomania. It considers how the popular performances embodied the neurological nature of modernist culture through their representation of neuropathological conditions. The chapter concludes with two case studies. I first examine the performance style of Gertrude Hoffmann, a successful vaudeville performer who was one of the first to present a Salome act at a major variety venue. I study her work for how it embodies traits associated with the neurological condition of generalized hysteria. Next I examine the contortionist/dancer La Sylphe for how her iteration of Salome corresponded with behaviors and gestures associated with the neurological condition of epilepsy

Comparison of gasolines with different distillation curves: effect of the temperature on a GDI spray opening angle

A GDI multihole injector was used to investigate the effect of the fuel composition and temperature on the spray angle. Three pure mono-component fuels, and six different kinds of gasoline were tested in a quiescent bomb. The injector and the fuel were heated-up at at different temperatures ranging from 20 to 120 °C. Back light photography was used to capture still images of the spray from which geometrical parameter of the spray image could be extracted. The spray spreading, its initial and far field angles could be compared to infer information on the effect of the fuel composition on the spray macroscopic parameters