Empirical Traffic Data and Their Implications for Traffic Modeling

From single vehicle data a number of new empirical results about the temporal evolution, correlation, and density-dependence of macroscopic traffic quantities have been determined. These have relevant implications for traffic modeling and allow to test existing traffic models.Comment: For related work see http://www.theo2.physik.uni-stuttgart.de/helbing.htm

Breast feeding practices and views among diabetic women: a retrospective cohort study

Objective: to explore the pattern and experiences of breast-feeding practices among diabetic women. Design: retrospective cohort study using maternal records and postal questionnaires in a Baby-Friendly hospital. Participants: diabetic mothers including women with gestational diabetes, and type 1 and 2 diabetes mellitus. Findings: from the total group of respondents, 81.9% intended to breast feed. The actual breast feeding rates were 81.9% at birth, 68.1% at 2 weeks and 28.7% at 6 months postpartum. Major themes that were identified from women's experiences included information and advice, support vs. pressure, classification and labelling, and expectations. Conclusions: more than two-thirds of the diabetic women intended to breast feed and actually did breast feed in this study. For both the total study population and the type 1 and 2 diabetics alone, more than half were still breast feeding at 2 weeks postpartum, and approximately one-third were still breast feeding at 6 months postpartum. Implications for practice: structured support, provided for women through Baby-Friendly initiatives, was appreciated by the diabetic women in this study. The extent to which this support influenced the highly successful breast feeding practices in this group of women needs focused investigation. The need for a delicate balancing act between pressure and advice in order to prevent coercion was noted.</p

Fuel optimum stochastic attitude control

Numerical solution of stochastic Hamilton-Jacobi equation for fuel optimal spacecraft attitude control syste

Absolute rate of the reaction of hydrogen atoms with ozone from 219-360 K

Absolute rate constants for the reaction of atomic hydrogen with ozone were obtained over the temperature range 219-360 K by the flash photolysis-resonance fluorescence technique. The results can be expressed in Arrhenius form by K = (1.33 plus or minus 0.32)x10 to the minus 10 power exp (-449 plus or minus 58/T) cu cm/molecule/s (two standard deviations). The present work is compared to two previous determinations and is discussed theoretically

Absolute rate of the reaction of bromine atoms with ozone from 200-360 K

The rate constant for the reaction Br + O3 yields BrO + O2 was measured from 200 to 360 K by the technique of flash photolysis coupled to time resolved detection of bromine atoms by resonance fluorescence (FP-RF). Br atoms were produced by the flash photolysis of CH3Br at lambda 165nm.O3 was monitored continuously under reaction conditions by absorption at 253.7 nm. At each of five temperatures the results were independent of substantial variations in O3, total pressure and limited variations in flash intensity. The measured rate constants obeyed the Arrhenius expression, where the error quoted is two standard deviations. Results are compared with previous determinations which employed the discharge flow-mass spectrometric technique

Frequency doubling in Ga:La:S optical glass with microcrystals

Second harmonic generation in gallium-lanthanum-sulphide (Ga:La:S) and GeS2+Ga:La:S glasses is investigated. It is shown that microcrystals of Ga:La:S and of alpha-phase of gallium-sulphide (alpha-Ga2S3), whose presence in the glass matrix is revealed by x-ray diffraction analysis, are responsible for the frequency doubling process

Resolving depth measurement ambiguity with commercially available range imaging cameras

Time-of-flight range imaging is typically performed with the amplitude modulated continuous wave method. This involves illuminating a scene with amplitude modulated light. Reflected light from the scene is received by the sensor with the range to the scene encoded as a phase delay of the modulation envelope. Due to the cyclic nature of phase, an ambiguity in the measured range occurs every half wavelength in distance, thereby limiting the maximum useable range of the camera. This paper proposes a procedure to resolve depth ambiguity using software post processing. First, the range data is processed to segment the scene into separate objects. The average intensity of each object can then be used to determine which pixels are beyond the non-ambiguous range. The results demonstrate that depth ambiguity can be resolved for various scenes using only the available depth and intensity information. This proposed method reduces the sensitivity to objects with very high and very low reflectance, normally a key problem with basic threshold approaches. This approach is very flexible as it can be used with any range imaging camera. Furthermore, capture time is not extended, keeping the artifacts caused by moving objects at a minimum. This makes it suitable for applications such as robot vision where the camera may be moving during captures. The key limitation of the method is its inability to distinguish between two overlapping objects that are separated by a distance of exactly one non-ambiguous range. Overall the reliability of this method is higher than the basic threshold approach, but not as high as the multiple frequency method of resolving ambiguity

Thermal Diffusivities of Functionalized Pentacene Semiconductors

We have measured the interlayer and in-plane (needle axis) thermal diffusivities of 6,13-bis(triisopropylsilylethynyl) pentacene (TIPS-Pn). The needle axis value is comparable to the phonon thermal conductivities of quasi-one dimensional organic metals with excellent pi-orbital overlap, and its value suggests that a significant fraction of heat is carried by optical phonons. Furthermore, the interlayer (c-axis) thermal diffusivity is at least an order of magnitude larger, and this unusual anisotropy implies very strong dispersion of optical modes in the interlayer direction, presumably due to interactions between the silyl-containing side groups. Similar values for both in-plane and interlayer diffusivities have been observed for several other functionalized pentacene semiconductors with related structures.Comment: 9 pages, including 4 figures; submitted to Applied Physics Letter

Absolute rate of the reaction of C l(2P) with methane from 200-500 K

Rate constants for the reaction of atomic chlorine with methane have been measured from 200-500K using the flash photolysis-resonance fluorescence technique. When the results from fourteen equally spaced experimental determinations are plotted in Arrhenius form a definite curvature is noted. The results are compared to previous work and are theoretically discussed