Detailed investigation of a vaporising fuel spray. Part 1: Experimental investigation of time averaged spray

A laser tomographic light scattering technique provides rapid and accurate high resolution measurements of droplet sizes, concentrations, and vaporization. Measurements using a computer interfaced thermocouple are presented and it is found that the potential exists for separating gas and liquid temperature measurements and diagnosing local spray density by in situ analysis of the response characteristics of the thermocouple. The thermocouple technique provides a convenient means for measuring mean gas velocity in both hot and cold two phase flows. The experimental spray is axisymmetric and has carefully controlled initial and boundary conditions. The flow is designed to give relatively insignificant transfer of momentum and mass from spray to air flow. The effects of (1) size-dependent droplet dispersion by the turbulence, (2) the initial spatial segregation of droplet sizes during atomization, and (3) the interaction between droplets and coherent large eddies are diagnosed

A Yule-Simon process with memory

The Yule-Simon model has been used as a tool to describe the growth of diverse systems, acquiring a paradigmatic character in many fields of research. Here we study a modified Yule-Simon model that takes into account the full history of the system by means of an hyperbolic memory kernel. We show how the memory kernel changes the properties of preferential attachment and provide an approximate analytical solution for the frequency distribution density as well as for the frequency-rank distribution.Comment: 7 pages, 5 figures; accepted for publication in Europhysics Letter

Parent and child agreement for acute stress disorder, post-traumatic stress disorder and other psychopathology in a prospective study of children and adolescents exposed to single-event trauma

Examining parent-child agreement for Acute Stress Disorder (ASD) and Post-Traumatic Stress Disorder (PTSD) in children and adolescents is essential for informing the assessment of trauma-exposed children, yet no studies have examined this relationship using appropriate statistical techniques. Parent-child agreement for these disorders was examined by structured interview in a prospective study of assault and motor vehicle accident (MVA) child survivors, assessed at 2-4 weeks and 6 months post-trauma. Children were significantly more likely to meet criteria for ASD, as well as other ASD and PTSD symptom clusters, based on their own report than on their parent's report. Parent-child agreement for ASD was poor (Cohen's κ = -.04), but fair for PTSD (Cohen's κ = .21). Agreement ranged widely for other emotional disorders (Cohen's κ = -.07-.64), with generalised anxiety disorder found to have superior parent-child agreement (when assessed by phi coefficients) relative to ASD and PTSD. The findings support the need to directly interview children and adolescents, particularly for the early screening of posttraumatic stress, and suggest that other anxiety disorders may have a clearer presentation post-trauma

Rank Statistics in Biological Evolution

We present a statistical analysis of biological evolution processes. Specifically, we study the stochastic replication-mutation-death model where the population of a species may grow or shrink by birth or death, respectively, and additionally, mutations lead to the creation of new species. We rank the various species by the chronological order by which they originate. The average population N_k of the kth species decays algebraically with rank, N_k ~ M^{mu} k^{-mu}, where M is the average total population. The characteristic exponent mu=(alpha-gamma)/(alpha+beta-gamma)$ depends on alpha, beta, and gamma, the replication, mutation, and death rates. Furthermore, the average population P_k of all descendants of the kth species has a universal algebraic behavior, P_k ~ M/k.Comment: 4 pages, 3 figure

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Biodex, and this effect was most marked in the strongest participants. Nevertheless, there was a good correlation between the measures (r = 0.91, p ! 0.0001). Classifi cation of individuals into tertiles of muscle strength showed good agreement between the two methods (Kappa = 0.69, p ! 0.0001). Conclusions: Our fi ndings suggest that the HHD using a supine positioning offers a feasible, inexpensive, and portable test of quadriceps muscle strength for use in healthy older people. It underestimates the absolute quadriceps strength compared to the Biodex particularly in stronger people, but is a useful tool for ranking muscle strength of older people in epidemiological studies. It may also be of value for quick and objective assessment of physical function in the clinical setting

Soil management of alfisols for water conservation and utilization

Alfisols are abundarrt soils used for rainfed agrkulfure but have a wide rarrse of problrrtrs due lo lora irrfilfratiorr rates. We studied a ranse of soil and crop managemenl options (fillngc and muklring for anrtunl crops, a~rrl ~wrerrninl crolrs) t:, incrcase infiltration during 1989 and 1990. With annual crops sfraw ~rrul~.ahn d FYM trrulch reducrd runof by 52% ar~d1 7% reslwcfitrly compared to barc freatmenfs but tillage h d small and inconsislent effecfs. Perennial crops produced high rutaolf duritrg the esfahlisl~~rrepnetr iod in 1988 and sukquetrfly a wide range of response depending or1 flu foliage slructure of fire r.roj>. Tall groroirtg pererrnial pigeon pea did not reduce runoff compared lo crops with no surface amendment but llrc derrse, shorf, s~rrtrulitrg stylosarrthes harr~ata reduced runofl more than straw mulch. Reduction in runof will decrease soil erosion and nrny increme draitra~e by up to 200 nrm pcr year. This drainage is a mmsive potential resource for dcrp rooted crups or irrigation fro111 grou~ritiuafer. Sustairrnble agrkultural production a1 a wntershed scale will involve soil manageme71t lo increase irtftltrafion in rairrfed areas and exploitafion of cortscqurnt increases in groundwater resources by irrigation or deep roofed crops