819 research outputs found

    Ecological aspect in combined sewer overflows chamber design

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    In 2005 one of major Czech manufacturers of glass reinforced plastic pipes asked the Department of Sanitary and Ecological Engineering to develop a new type of combined sewer overflows (CSO) chamber that could become a part of their manufacturing programme. The main requirements were economy of production, easy and fast installation on the field and increased protection of receiving waters. A simple object consisting of a pipe placed above another one was designed. The object begins with a stilling chamber formed by a conical expansion of the inlet pipe. It is separated from the overflow object itself by a downflow baffle designed to trap floating objects. The CSO chamber is equipped by a flow regulation device (e.g. vortex valve or throttle pipe) at the end. Excess water flows through a slit in the top of the bottom pipe into the upper pipe and from there to the receiving water. More than 15 prototypes were already installed in the Czech and Slovak Republics and more than 20 are planned to be built in Europe. We hope this type of CSO CHAMBER will help to decrease the cost of construction of new sewers and reconstruction of old ones. Its higher efficiency of separation of suspended particles might also contribute to the improvement of the quality of receiving water bodies according to Water Framework Directive 2000/60/EC

    Long-Term Focus of Attentional Biases

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    Prior research regarding attentional biases, or patterns of visual attention, have focused on attention over the initial second when exposed to pictoral food stimuli. This manuscript reviews the literature regarding attentional biases in overweight/obese individuals over this timeframe for the two previously defined components of attentional bias (attentional orientation and attentional maintenance). A new component is proposed, called “attentional re-engagement,” defined as the pattern of attentional shifts towards target stimulus types over longer periods of time. Overweight/Obese and Normal-weighted participants were recruited and engaged in an Extended Dot Probe task, wherein attentional orientation, maintenance, and re-engagement were assessed using the traditional dot-probe method, while long-term attentional re-engagement measures were also assessed via participant responses during long duration trials (15000ms). Participants also engaged in an eating task. The weight groups did not differ on attentional orientation, attentional maintenance, or any eating measure. Most participants experienced several attentional shifts in the long duration trials, but a small subset experienced very few attentional shifts. Within the majority of participants whose attention did shift in long duration trials, weight groups differed on the amount of attention directed to food images. This long-term attention to food images was also predictive of eating outcome in these individuals, suggesting that attentional re-engagement may be an unexplored component of attentional bias

    The Role of Attention in Ego-Depletion

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    The resource model of ego-depletion is unable to account for the results of several ego-depletion studies, whereas a recent mechanistic revision by Inzlicht and Schmeichel (2012) has focused on the role of attention and motivation in an effort to explain the phenomenon. Assessment of attention\u27s role in restrained and unrestrained eaters may provide evidence that motivation and attention work in tandem to affect one\u27s ability to exert self-control. In this experiment, college-aged females participated in two studies to examine the role of attention in ego-depletion effects. Study 1 evaluated the effect of ego depletion on attention via a dot probe task, while Study 2 assessed the effect of attentional bias on self-regulatory ability during an eating task. No ego-depletion effect was observed to affect attention toward reward cues or away from self-control cues in the first study, with ancillary evidence suggesting that the ego-depletion induction task was unable to induce a depletive effect which may have driven the observed results. The results of the second study indicate that orienting individuals toward reward cues impacted only the restrained eaters, thus implicating both attention and motivation in guiding eating behavior which is consistent with the components of the mechanistic revision of ego-depletion

    Synthesis, Characterization and Magnetic Susceptibility of the Heavy Fermion Transition Metal Oxide LiV_{2}O_{4}

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    The preparative method, characterization and magnetic susceptibility \chi measurements versus temperature T of the heavy fermion transition metal oxide LiV_{2}O_{4} are reported in detail. The intrinsic \chi(T) shows a nearly T-independent behavior below ~ 30 K with a shallow broad maximum at about 16 K, whereas Curie-Weiss-like behavior is observed above 50-100 K. Field-cooled and zero-field-cooled magnetization M measurements in applied magnetic fields H = 10 to 100 G from 1.8 to 50 K showed no evidence for spin-glass ordering. Crystalline electric field theory for an assumed cubic V point group symmetry is found insufficient to describe the observed temperature variation of the effective magnetic moment. The Kondo and Coqblin-Schrieffer models do not describe the magnitude and T dependence of \chi with realistic parameters. In the high T range, fits of \chi(T) by the predictions of high temperature series expansion calculations provide estimates of the V-V antiferromagnetic exchange coupling constant J/k_{B} ~ 20 K, g-factor g ~ 2 and the T-independent susceptibility. Other possible models to describe the \chi(T) are discussed. The paramagnetic impurities in the samples were characterized using isothermal M(H) measurements with 0 < H <= 5.5 Tesla at 2 to 6 K. These impurities are inferred to have spin S_{imp} ~ 3/2 to 4, g_{imp} ~ 2 and molar concentrations of 0.01 to 0.8 %, depending on the sample.Comment: 19 typeset RevTeX pages, 16 eps figures included, uses epsf; to be published in Phys. Rev.

    A Resonant X-ray Scattering Study of Octahedral Tilt Ordering in LaMnO3_3 and Pr1x_{1-x}Cax_xMnO3_3

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    We report an x-ray scattering study of octahedral tilt ordering in the manganite series Pr1x_{1-x}Cax_xMnO3_3 with x=0.4 and 0.25 and in LaMnO3_3. The sensitivity to tilt ordering is achieved by tuning the incident x-ray energy to the LI_I, LII_{II} and LIII_{III} absorption edges of Pr and La, respectively. The resulting energy-dependent profiles are characterized by a dipole-resonant peak and higher energy fine structure. The polarization dependence is predominantly σ\sigma-to-π\pi and the azimuthal dependence follows a sin-squared behavior. These results are similar to those obtained in recent x-ray scattering studies of orbital ordering carried out in these same materials at the Mn K edge. They lead to a description of the cross-section in terms of Templeton scattering in which the tilt ordering breaks the symmetry at the rare earth site. The most interesting result of the present work is our observation that octahedral tilt ordering persists above the orbital ordering transition temperatures in all three samples. Indeed, we identify separate structural transitions which may be associated with the onset of orbital and tilt ordering, respectively, and characterize the loss of tilt ordering versus temperature in LaMnO3_3.Comment: 24 pages, 8 figure

    Evidence for charge localization in the ferromagnetic phase of La_(1-x)Ca_(x)MnO_3 from High real-space-resolution x-ray diffraction

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    High real-space-resolution atomic pair distribution functions of La_(1-x)Ca_(x)MnO_3 (x=0.12, 0.25 and 0.33) have been measured using high-energy x-ray powder diffraction to study the size and shape of the MnO_6 octahedron as a function of temperature and doping. In the paramagnetic insulating phase we find evidence for three distinct bond-lengths (~ 1.88, 1.95 and 2.15A) which we ascribe to Mn^{4+}-O, Mn^{3+}-O short and Mn^{3+}-O long bonds respectively. In the ferromagnetic metallic (FM) phase, for x=0.33 and T=20K, we find a single Mn-O bond-length; however, as the metal-insulator transition is approached either by increasing T or decreasing x, intensity progressively appears around r=2.15 and in the region 1.8 - 1.9A suggesting the appearance of Mn^{3+}-O long bonds and short Mn^{4+}-O bonds. This is strong evidence that charge localized and delocalized phases coexist close to the metal-insulator transition in the FM phase.Comment: 8 pages, 8 postscript figures, submitted to Phys. Rev.

    OPTIMIZING EFFICIENCY OF THE COMBINED SEWER OVERFLOW CHAMBER HOBAS

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    The paper deals with the design of swinging self-clean screen bars and the assessment of pressure losses in the combined sewer overflow chamber (HOBAS CSO Chamber), sold by the company HOBAS. The HOBAS CSO Chamber ensures a safe transfer of rainwater during a major rain event. The main goal of the research was to determine the pressure losses of the overflow chamber under various conditions - without self-clean screen bars; with screen bars without impurities and with screen bars partially or fully clogged with various impurities. The measurements were performed on a 1 : 5 scale physical model of CSO using 4 probes for measuring level heights. From the measured values, the coefficients of local losses were calculated, which were then entered into the currently used design table of flow capacities of the CSO HOBAC Chamber. At the same time, the optimal shape of individual rods of swinging self-clean bars was investigated, so that the oscillation of the free ends of the rods supports the separation and self-cleaning function during their operation. The research was conducted on a 1 : 1 scale model, so that impurities present in the CSO during the overflow (i.e. textile, cosmetic handkerchiefs, feminine hygiene products, condoms and others) could be used directly in the measurement. At the end of the experiments, the variants of the rods of screen bars that were the most effective in the separation and self-cleaning function were selected. The self-cleaning effect, which occurs at the end of the rain event and ensures that the CSOis free of impurities and ready for further use, was subsequently tested with the selected variant of the rods

    Phase Separation and the Low-Field Bulk Magnetic Properties of Pr0.7Ca0.3MnO3

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    We present a detailed magnetic study of the perovskite manganite Pr0.7Ca0.3MnO3 at low temperatures including magnetization and a.c. susceptibility measurements. The data appear to exclude a conventional spin glass phase at low fields, suggesting instead the presence of correlated ferromagnetic clusters embedded in a charge-ordered matrix. We examine the growth of the ferromagnetic clusters with increasing magnetic field as they expand to occupy almost the entire sample at H ~ 0.5 T. Since this is well below the field required to induce a metallic state, our results point to the existence of a field-induced ferromagnetic insulating state in this material.Comment: 15 pages with figures, submitted to Physical Review
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