Fluctuation properties of precipitation. Part IV: Finescale clustering of drops in variable rain

In recent studies it is shown that in variable rain the spatial distribution of drops is not Poissonian. However, these past studies were limited to 1-min drop counts, which likely correspond to spatial scales of a few hundred to several hundreds of meters. In this work results based on 1-s drop counts using a video disdrometer are reported. It is shown that the clustering of raindrops previously found during intervals of 1 min also occurs during 1 s as well in convective rain. These latter temporal scales likely correspond to spatial features having dimensions from only a few to tens of meters. Combined with the authors’ earlier results, these findings suggest that clustering of raindrops and meteorological variability span the range of scales from at least as small as a few meters to several hundreds of meters in convective precipitating systems. Consequently, non-Poissonian clustering reported in previous work (analyzing data accumulated over hours using 1-min drop counts) cannot be dismissed as artifacts in the data or errors in the processing. These studies appear to reflect accurately the true probabilistic character of rainfall. Moreover, it is shown that the clustering is more prevalent and occurs over longer coherence times for larger than for smaller drops. An argument is given suggesting that the clustering of larger drops is likely associated with the larger scales of convection, whereas the clustering of smaller drops is likely more strongly influenced by smaller-scale turbulence. Furthermore, in convective rain it appears that the coherence times of drop size distributions will often be governed by the smaller drops. Using current technology, this will make it very difficult, at times, to adequately sample the larger drops in variable rain without mixing observations from more than one drop size distribution at the smaller sizes. Nevertheless, care must be taken since oversampling destroys information just as effectively as undersampling misses it

Application of Tomography to the Nuclear Industry

While tomographic methods of reconstructing three~dimensional x-ray images are becoming more common in the medical field, their application to industrial problems has only started. Some of the features that differentiate industrial tomography from medical tomography are x-ray energies may vary from\u3c 10 keV to\u3e 22 MeV radiation dose to the object is not a constraint inspection times (within economic constraints) are not as important the anomalies to be detected offer sharp, high contrast boundaries to the inspection system high spatial resolution rather than high contrast sensitivity is the primary design goal, and the number of views may be limited by other (mechanical) constraints. This paper will describe the effort the Los Alamos Scientific Laboratory (LASL) is making to define the design parameters that affect the constraints listed above. A tomographic test bed in which various design features may be evaluated will be described. The computational facilities at LASL, which include a versatile modeling code that can simulate tomographic systems with various types of radiation, geometries, and detector types, will also be discussed

The NASA/GSFC hydrogen maser program: A review of recent data

Data is presented on the phase and frequency stability, over time periods extending to one week, of the new NR field operable hydrogen masers developed by the Applied Physics Laboratory (APL) and the older NX and NP field operable hydrogen masers developed by Goddard Space Flight Center and maintained and upgraded by Bendix Field Engineering Corporation (BFEC). Data is presented on the NR masers in the laboratory showing frequency stabilities well into the 10 to the -15th power range and phase stabilities well into the 100 ps range for periods of up to one day. Data is presented on upgraded NP masers in the laboratory showing that the frequency stability has been improved substantially to virtually the NR level. VLBI data is presented on the phase difference between NX-2 at Owens Valley, California and NR-2 at Fort Davis, Texas for a one week period showing, after removal of a constant frequency drift, a 350 ps RMS phase stability

The Radius of Metric Subregularity

There is a basic paradigm, called here the radius of well-posedness, which quantifies the "distance" from a given well-posed problem to the set of ill-posed problems of the same kind. In variational analysis, well-posedness is often understood as a regularity property, which is usually employed to measure the effect of perturbations and approximations of a problem on its solutions. In this paper we focus on evaluating the radius of the property of metric subregularity which, in contrast to its siblings, metric regularity, strong regularity and strong subregularity, exhibits a more complicated behavior under various perturbations. We consider three kinds of perturbations: by Lipschitz continuous functions, by semismooth functions, and by smooth functions, obtaining different expressions/bounds for the radius of subregularity, which involve generalized derivatives of set-valued mappings. We also obtain different expressions when using either Frobenius or Euclidean norm to measure the radius. As an application, we evaluate the radius of subregularity of a general constraint system. Examples illustrate the theoretical findings.Comment: 20 page

Dynamical density functional theory for the evaporation of droplets of nanoparticle suspension

We develop a lattice gas model for the drying of droplets of a nanoparticle suspension on a planar surface, using dynamical density functional theory (DDFT) to describe the time evolution of the solvent and nanoparticle density profiles. The DDFT assumes a diffusive dynamics but does not include the advective hydrodynamics of the solvent, so the model is relevant to highly viscous or near to equilibrium systems. Nonetheless, we see an equivalent of the coffee-ring stain effect, but in the present model it occurs for thermodynamic rather the fluid-mechanical reasons. The model incorporates the effect of phase separation and vertical density variations within the droplet and the consequence of these on the nanoparticle deposition pattern on the surface. We show how to include the effect of slip or no-slip at the surface and how this is related to the receding contact angle. We also determine how the equilibrium contact angle depends on the microscopic interaction parameters.Comment: 35 pages, 10 figure

Corn Disease Update

Goss\u27s Bacterial Wilt and Blight ... Symptoms ... Management ... 2011 Survey ... Literature Cited Gray Leaf Spot Seedling Diseases and Stalk/Crown Root Diseases More Resource

The impact of COVID-19 on routine patient care from a laboratory perspective

Background. Globally, few studies have examined the effect of the COVID-19 pandemic on routine patient care and follow-up.Objectives. To evaluate the effect of the COVID-19 response on biochemical test requests received from outpatient departments (OPDs) and peripheral clinics serviced by the National Health Laboratory Service Chemical Pathology Laboratory at Tygerberg Hospital, Cape Town, South Africa (SA). Request volumes were used as a measure of the routine care of patients, as clinical information was not readily available.Methods. A retrospective audit was conducted. The numbers of requests received from OPDs and peripheral clinics for creatinine, glycated haemoglobin (HbA1c), lipid profiles, thyroid-stimulating hormone (TSH), free thyroxine, free tri-iodothyronine (fT3), serum and urine protein electrophoresis, serum free light chains and neonatal total serum bilirubin were obtained from 1 March to 30 June for 2017, 2018, 2019 and 2020.Results. The biggest impact was seen on lipids, creatinine, HbA1c, TSH and fT3. The percentage reduction between 1 March and 30 June 2019 and between 1 March and 30 June 2020 was 59% for lipids, 64% for creatinine and HbA1c, 80% for TSH and 81% for fT3. There was a noteworthy decrease in overall analyte testing from March to April 2020, coinciding with initiation of level 5 lockdown. Although an increase in testing was observed during June 2020, the number of requests was still lower than in June 2019.Conclusions. This study, focusing on the short-term consequences of the SA response to the COVID-19 pandemic, found that routine follow-up of patients with communicable and non-communicable diseases was affected. Future studies are necessary to evaluate the long-term consequences of the pandemic for these patient groups.