On recent SFR calibrations and the constant SFR approximation

Star Formation Rate (SFR) inferences are based in the so-called constant SFR approximation, where synthesis models are require to provide a calibration; we aims to study the key points of such approximation to produce accurate SFR inferences. We use the intrinsic algebra used in synthesis models, and we explore how SFR can be inferred from the integrated light without any assumption about the underling Star Formation history (SFH). We show that the constant SFR approximation is actually a simplified expression of more deeper characteristics of synthesis models: It is a characterization of the evolution of single stellar populations (SSPs), acting the SSPs as sensitivity curve over different measures of the SFH can be obtained. As results, we find that (1) the best age to calibrate SFR indices is the age of the observed system (i.e. about 13Gyr for z=0 systems); (2) constant SFR and steady-state luminosities are not requirements to calibrate the SFR; (3) it is not possible to define a SFR single time scale over which the recent SFH is averaged, and we suggest to use typical SFR indices (ionizing flux, UV fluxes) together with no typical ones (optical/IR fluxes) to correct the SFR from the contribution of the old component of the SFH, we show how to use galaxy colors to quote age ranges where the recent component of the SFH is stronger/softer than the older component. Particular values of SFR calibrations are (almost) not affect by this work, but the meaning of what is obtained by SFR inferences does. In our framework, results as the correlation of SFR time scales with galaxy colors, or the sensitivity of different SFR indices to sort and long scale variations in the SFH, fit naturally. In addition, the present framework provides a theoretical guide-line to optimize the available information from data/numerical experiments to improve the accuracy of SFR inferences.Comment: A&A accepted, 13 pages, 4 Figure

SPATIAL REGRESSION MODELS FOR YIELD MONITOR DATA: A CASE STUDY FROM ARGENTINA

Precision agricultural technology promises to move crop production closer to a manufacturing paradigm, but analysis of yield monitor, sensor and other spatial data has proven difficult because correlation among neighboring observations often violates the assumptions of classical statistical analysis. When spatial structure is ignored variance estimates tend to be inflated and significance levels of test statistics are reduced. The gap between data analysis and site-specific recommendations has been identified as one of the key constraints on widespread adoption of precision agriculture technology. This paper compares four approaches that explicitly incorporate spatial correlation into regression models: (1) a spatial econometric approach; (2) a polynomial trend regression approach; (3) a classical nearest neighbor analysis; and (4) and a geostatistic approach. In the Argentine data studied, the spatial econometric, geostatistical approach and spatial trend analysis offered stronger statistical evidence of spatial heterogeniety of nitrogen response than the ordinary least squares or nearest neighbor analysis. All the spatial models led to the same economic conclusion, which is that variable rate nitrogen is potentially profitable. The spatial econometric analysis can be implemented on relatively small data sets that do not have enough observations for estimation of the semivariogram required by geostatistics. The spatial trend analysis can be implemented with ordinary least squares functions that are already available in some GIS software. In this study, the main benefit of using spatial regression analysis is increased confidence in the corn yield response estimates by management zone, and conclusions about the profitability of precision agriculture technologies.Crop Production/Industries,

Effects of Hypochlorous Acid Solutions on Venous Leg Ulcers (VLU): Experience With 1249 VLUs in 897 Patients

AbstractIn order to assess the impact of comorbidities and identify factors that accelerate the healing rate of venous leg ulcers we performed an extensive, retrospective analysis of our experience in a diverse population. From June, 2006 to June, 2014, 897 patients with 1249 venous leg ulcers were treated at Lake Wound Clinics. Treatment protocols utilized the standard regimen of wound cleaning, debridement and compression bandaging. Wound cleaning, autolytic debridement, packing and dressing of venous leg ulcers utilized aqueous solutions of hypochlorous acid (HCA) rather than the standard normal saline. This protocol caused all ulcers to close completely. Comorbidities that delayed healing included uncontrolled or poorly controlled diabetes mellitus, advanced peripheral artery occlusive disease (PAD), active smoking, use of steroid medications and/or street drugs, large initial ulcer size and significant depth. Other factors, including advanced age, recurrent venous ulceration, stasis dermatitis, lipodermatosclerosis, morbid obesity and infection with one or more multidrug resistant organisms did not delay closure. From this experience we conclude that venous leg ulcer care protocols that clean, debride, pack and dress with hypochlorous acid solutions can reduce the effects of some comorbidities while accelerating healing times. Additional benefits are described

The Value of Cytological Examination in the Diagnosis of Noninvasive Thyroid Neoplasm with Papillary-like Nuclear Features (NIFTP)

Since the introduction of the concept that the noninvasive encapsulated follicular variant of papillary thyroid carcinoma does not warrant a diagnosis of carcinoma and shall be renamed noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP), many questions have arisen among thyroid cytopathologists concerning the implications of this changing paradigm on the cytological classification of thyroid nodules. Specifically, whether it is possible to diagnose NIFTP by fine-needle aspiration, how will the risk of malignancy of the diagnostic categories of thyroid cytopathology be affected, and which changes will be made to the current cytological workup of thyroid nodules. The aim of our work was to review published literature to analyze how cytopathologists are dealing with this changing paradigm in thyroid pathology and how, in turn, it is affecting their current practice

Density waves and star formation in grand design spirals

HII regions in the arms of spiral galaxies are indicators of recent star-forming processes. They may have been caused by the passage of the density wave or simply created by other means near the arms. The study of these regions may give us clues to clarifying the controversy over the existence of a triggering scenario, as proposed in the density wave theory. Using H$\alpha$ direct imaging, we characterize the HII regions from a sample of three grand design galaxies: NGC5457, NGC628 and NGC6946. Broad band images in R and I were used to determine the position of the arms. The HII regions found to be associated with arms were selected for the study. The age and the star formation rate of these HII regions was obtained using measures on the H$\alpha$ line. The distance between the current position of the selected HII regions and the position they would have if they had been created in the centre of the arm is calculated. A parameter, T, which measures whether a region was created in the arm or in the disc, is defined. With the help of the T parameter we determine that the majority of regions were formed some time after the passage of the density wave, with the regions located `behind the arm' (in the direction of the rotation of the galaxy) the zone they should have occupied had they been formed in the centre of the arm. The presence of the large number of regions created after the passage of the arm may be explained by the effect of the density wave, which helps to create the star-forming regions after its passage. There is clear evidence of triggering for NGC5457 and a co-rotation radius is proposed. A more modest triggering seems to exist for NGC628 and non significant evidence of triggering are found for NGC6946.Comment: 10 pages, 20 figures, accepted for publication in A&

The scientific instruments in the museum of the Politecnico di Torino

The paper wants to illustrate scientific instruments in the collections of the Museum of Politecnico di Torino, distributed in various departments in respect of both historical consistency and didactic use.In particular the attention is focused on scientific instruments for electric and electrotechnical measurements

Performance Comparison in the "Follicular Neoplasm" Category Between the American, British, Italian, and Japanese Systems for Reporting Thyroid Cytopathology

It is now almost ten years that the United Stated of America, England, Italy and Japan had their own reporting system to classify thyroid lesions. Important confusion and uncertainties dominated the "follicular-patterned lesions", a category also known as the "gray zone". Every cytopathologist was using a personal terminology to describe and call lesions made up of a variable admixture of macro- and microfollicular structures. These personal views varied considerably between cytopathologists and generated a great deal of confusion among patients (the cytological report being almost incomprehensible to them), clinicians and even within the same cytopathology community. With the advent of national reporting systems, things changed in a better way and standardized reporting systems became the standard of practice in thyroid cytology. The outcome of the widespread use of standardized diagnostic categories was the reduction of descriptive diagnoses and the improved communication between pathologists, clinicians and patients. In this article we review the major reporting systems, analyze their similarities and differences in the "indeterminate" or "follicular-patterned" diagnostic categories, and when possible, try to assess their performance

Study of star-forming galaxies in SDSS up to redshift 0.4: I. Metallicity evolution

The chemical composition of the gas in galaxies versus cosmic time provides a very important tool for understanding galaxy evolution. Although there are many studies at high redshift, they are rather scarce at lower redshifts. However, low redshift studies can provide important clues about the evolution of galaxies, furnishing the required link between local and high redshift universe. In this work we focus on the metallicity of the gas of star-forming galaxies at low redshift, looking for signs of chemical evolution. To analyze the metallicity contents star-forming galaxies of similar luminosities and masses at different redshifts. With this purpose, we present a study of the metallicity of relatively massive (log(M_star/M_sun)>10.5) star forming galaxies from SDSS--DR5 (Sloan Digital Sky Survey--Data Release 5), using different redshift intervals from 0.04 to 0.4. We used data processed with the STARLIGHT spectral synthesis code, correcting the fluxes for dust extinction, estimating metallicities using the R_23 method, and segregating the samples with respect to the value of the [NII]6583/[OII]3727 line ratio in order to break the R_23 degeneracy selecting the upper branch. We analyze the luminosity and mass-metallicity relations, and the effect of the Sloan fiber diameter looking for possible biases. By dividing our redshift samples in intervals of similar magnitude and comparing them, significant signs of metallicity evolution are found. Metallicity correlates inversely with redshift: from redshift 0 to 0.4 a decrement of ~0.1 dex in 12+log(O/H) is found.Comment: 11 pages, 9 figures, Accepted for publication in A&