Bubble growth analysis during subcooled boiling experiments on-board the international space station: Benchmark image analysis.

This work compares four different image processing algorithms for the analysis of image data obtained during the Multiscale Boiling Experiment of ESA, executed on-board the International Space Station. Two separate experimental campaigns have been performed in 2019 and 2020, aiming to investigate boiling phenomena in microgravity, with and without the presence of shear flow and electric field. A heated substrate, at the bottom of the test cell, creates a temperature profile across the liquid bulk above it. A laser beam hits a designated microcavity at the middle of the substrate, to initiate nucleation of a single, isolated bubble. In the presence of shear flow or electric field forces, the bubble slides or detaches respectively, leaving the cavity free for the nucleation and growth of a new bubble. The growth of such a bubble within the prescribed temperature profile is studied for varying experimental conditions (i.e. pressure, heat flux, subcooling temperature) by capturing high speed, black and white video images. The presence of light reflections at random locations around the bubble contour vary with bubble size and population. This, combined with the refraction induced optical distortion of vertical image dimension close to the heater, make the accurate detection of bubbles contour a real challenge. Four research teams, namely the University of Pisa (UNIPI), the Institute of Fluid Mechanics of Toulouse (IMFT), the joint group of Aix Marseille University (AMU) and Kutateladze Institute of Thermophysics (IT), and the joined group of Aristotle University of Thessaloniki (AUTH), Technical University of Darmstadt (TUD) and Foundation of Research and Technology in Crete (FORTH), developed separate specialized algorithms to: a) detect bubble edges and b) use these edges to calculate basic bubble geometrical features, such as contact line diameter, bubble diameter and contact angles. These four different approaches diverge in complexity and concept. In the absence of reference measurements at microgravity conditions, measurements efficiency is evaluated based on the comparison of the estimated bubble geometrical features along with pertinent physical arguments. Results show that the efficiency of each approach varies with the nature of measurement. The studied benchmark dataset is published allowing other research groups to test further their own image processing algorithms.

Surveillance of CKD epidemiology in the US - a joint analysis of NHANES and KEEP.

Chronic Kidney Disease (CKD), is highly prevalent in the United States. Epidemiological systems for surveillance of CKD rely on data that are based solely on the NHANES survey, which does not include many patients with the most severe and less frequent forms of CKD. We investigated the feasibility of estimating CKD prevalence from the large-scale community disease detection Kidney Early Evaluation and Program (KEEP, n = 127,149). We adopted methodologies from the field of web surveys to address the self-selection bias inherent in KEEP. Primary outcomes studied were CKD Stage 3-5 (estimated glomerular filtration rate [eGFR] <60 mL/min/1.73 m2, and CKD Stage 4-5 (eGFR <30 mL/min/1.73 m2). The unweighted prevalence of Stage 4-5 CKD was higher in KEEP (1.00%, 95%CI: 0.94-1.05%) than in NHANES (0.51%, 95% CI: 0.43-0.59%). Application of a selection model that used  variables related to demographics, recruitment and socio-economic factors resulted in estimates similar to NHANES (0.55%, 95% CI: 0.50-0.60%). Weighted prevalence of Stages 3-5 CKD in KEEP was 6.45% (95% CI: 5.70-7.28%) compared to 6.73% (95% CI: 6.30-7.19%) for NHANES. Application of methodologies that address the self-selection bias in the KEEP program may allow the use of this large, geographically diverse dataset for CKD surveillance.

In Situ Electron Microscopy of Plasmon-Mediated Nanocrystal Synthesis.

Chemical processes driven by nonthermal energy (e.g., visible light) are attractive for future approaches to energy conversion, synthesis, photocatalysis, and so forth. The growth of anisotropic metal nanostructures mediated by excitation of a localized surface plasmon resonance (LSPR) is a prototype example of such a reaction. Important aspects, notably the growth mechanism and a possible role of plasmonic "hot spots" within the metal nanostructures, remain poorly understood. Here, we use in situ electron microscopy to stimulate and image the plasmon-mediated growth of triangular Ag nanoprisms in solution. The quantification of the time-dependent evolution of the lateral size and thickness of the nanoprisms, enabled by nanometer-scale real-time microscopy in solution, shows a transition from an early stage of uniform Ag0 incorporation exclusively in the prism side facets to a size regime with accelerated growth in thickness. Differences in attachment rate at this advanced stage correlate with local plasmonic field enhancements, which allows determining the range over which charge carriers transferred from plasmonic hot spots can drive chemistry. Such data support the development of nonthermal chemical processes that depend on plasmonic light harvesting and the transfer of nonequilibrium charge carriers.

Temporal soliton excitation in an ε-near-zero plasmonic metamaterial.

The excitation of temporal solitons in a metamaterial formed by an array of ε-near-zero (ENZ) plasmonic channels loaded with a material possessing a cubic (χ(3)) nonlinearity are theoretically explored. The unique interplay between the peculiar dispersion properties of ENZ channels and their enhanced effective nonlinearity conspires to yield low threshold intensities for the formation of slow group velocity solitons.

Layered plasmonic cloaks to tailor the optical scattering at the nanoscale.

We discuss the rich scattering features offered by thin and thick plasmonic layers covering dielectric nanoparticles and their potential optical applications. The frequency position of scattering dips and peaks may be controlled to a large degree using plasmonic layers, which may dramatically vary the total scattering signature in the frequency range of interest. We show that complex and exotic spectra may be obtained using a single composite nanosphere, including dipole-dipole Fano resonances and electromagnetic induced transparency effects. The described phenomena are observable at any angle of observation, in the total scattering cross section and for realistic plasmonic materials, since they are based on purely dipolar fields. Enhanced field amplitudes are associated with these anomalous scattering features, which may be used to efficiently boost weak optical nonlinear effects. Exciting applications of these nanostructures are envisioned, such as efficient and tunable sensors, all-optical switches and memories, optical tagging and biomolecular imaging.

Thermal emission from a metamaterial wire medium slab.

We investigate thermal emission from a metamaterial wire medium embedded in a dielectric host and highlight two different regimes for efficient emission, respectively characterized by broadband emission near the effective plasma frequency of the metamaterial, and by narrow-band resonant emission at the band-edge in the Bragg scattering regime. We discuss how to control the spectral position and relative strength of these two emission mechanisms by varying the geometrical parameters of the proposed metamaterial and its temperature.

Operational criteria for selecting a cDNA microarray data normalization algorithm.

Microarray technology allows gene expression profiling at a global level. Many algorithms for the normalization of raw microarray data have been proposed, but no attempt has yet been made to propose operationally verifiable criteria for their comparative evaluation, which is necessary for the selection of the most appropriate method for a given dataset. This study develops a set of operational criteria for assessing the impact of various normalization algorithms in terms of accuracy (bias), precision (variance) and over-fitting (information reduction). The use of these criteria is illustrated by applying the three most widely used algorithms (global median normalization, spiked-in based normalization and lowess) on a specifically designed, multiply-controlled dataset.

Mining microarray data to identify transcription factors expressed in naïve resting but not activated T lymphocytes.

Transcriptional repressors controlling the expression of cytokine genes have been implicated in a variety of physiological and pathological phenomena. An unknown repressor that binds to the distal NFAT element of the interleukin-2 (IL-2) gene promoter in naive T-helper lymphocytes has been implicated in autoimmune phenomena and has emerged as a potentially important factor controlling the latency of HIV-1. The aim of this paper was the identification of this repressor. We resorted to public microarray databases looking for DNA-binding proteins that are present in naïve resting T cells but are downregulated when the cells are activated. A Bayesian data mining statistical analysis uncovered 25 candidate factors. Of the 25, NFAT4 and the oncogene ets-2 bind to the common motif AAGGAG found in the HIV-1 LTR and IL-2 probes. Ets-2 binding site contains the three G's that have been shown to be important for binding of the unknown factor; hence, we considered it the likeliest candidate. Electrophoretic mobility shift assays confirmed cross-reactivity between the unknown repressor and anti-ets-2 antibodies, and cotransfection experiments demonstrated the direct involvement of Ets-2 in silencing the IL-2 promoter. Designing experiments for transcription factor analysis using microarrays and Bayesian statistical methodologies provides a novel way toward elucidation of gene control networks.

Individualization of theophylline infusion rate on the basis of a nonlinear compartmental pharmacokinetic model.

In the present paper, a nonlinear compartmental model for theophylline pharmacokinetics is developed. The analytical solution of the model, in parametric form, is derived under plateau conditions for plasma metabolite concentration. The parameters are obtained from plasma and urine data using best fitting techniques and their values are used in order to calculate maintenance intravenous infusion. Numerical simulation is then performed in order to compare the drug concentration obtained by our approach with that of alternative intravenous regimens. The differences argue for individualized dosage regimens, since theophylline is a drug with a narrow therapeutic window and its concentration at the active sites strongly depends on characteristic parameters of the patient's response. Our results show that it is possible to estimate the patients' parameters during the first 8 h after intravenous administration of the drug and these parameters can be used to design an individualized dosage regimen in patients receiving theophylline intravenously.

Preliminary evaluation of 15 chemotherapeutic agents applied topically in the treatment of mycosis fungoides.

This is an interim report of a double-blind multi-institutional study to examine the effect of chemotherapeutic agents applied topically to patients with mycosis fungoides. To date, 41 patch tests have been completed using 15 drugs. Five of the drugs produced some improvement, four were highly irritating, and six had no effect. This patch-testing study is a prelude to more extensive therapy trials.

Mycosis fungoides: epidemiologic observations.

An analysis of cases from a multi-hospital, pathologically verified clinical series and of deaths from US mortality statistics available at the county level for 1950--1975 (excluding 1972) was made in order to obtain information on the etiology of mycosis fungoides (MF). Despite the absence of an appropriate comparison group, the cases seemed to have a high frequency of antecedent allergies, fungal and viral skin infections, sun sensitivity, familial aggregation of lymphoma and leukemia, and employment in a manufacturing occupation (especially petrochemical, textile, metal, and machinery industries). The mortality survey revealed a predominance among males, nonwhites, and residents of the northeastern US, the latter due partly to an association between MF mortality and population size. The influence of occupational exposures was suggested by the excessive MF mortality rates in counties where petroleum, rubber, primary and fabricated metal, machinery, and printing industries were located.

F- and M-wave conduction velocity in amyotrophic lateral sclerosis.

The F-wave was used to estimate motor nerve conduction velocity (MNCV) along the proximal segment of the fastest axons of the deep peroneal nerve (anterior-horn cells to knee) in 13 patients with amyotrophic lateral sclerosis (ALS) and in 21 age- and sex-matched control subjects. Measurements were based on the shortest latency of 100 F-waves obtained after supramaximal stimulation at the ankle and knee. The MNCV was estimated with the F-wave and conventional M-response methods in the distal segment (knee to ankle) of the nerve. Our results showed that proximal-nerve conduction is faster than distal conduction both in control subjects and in ALS patients. In ALS, there was a moderate reduction of MNCV, which was of equal degree in both the proximal and distal segments of the deep peroneal nerve. In control subjects and in ALS patients, no statistically significant difference was found between the MNCV estimated for the knee-to-ankle segment by conventional means and that obtained by the F-wave method. This indicates that the F-wave of shortest latency is conducted by the fastest surviving motor fibers, as in the initial components of the M-response--demonstrating that it is legitimate to make direct comparison of F- and M-latencies in estimating the proximal MNCV.