scholarly journals The impact of 3D volume of interest definition on accuracy and precision of activity estimation in quantitative SPECT and planar processing methods

2010 ◽  
Vol 55 (12) ◽  
pp. 3535-3544 ◽  
Author(s):  
Bin He ◽  
Eric C Frey
Radiocarbon ◽  
2012 ◽  
Vol 54 (3-4) ◽  
pp. 449-474 ◽  
Author(s):  
Sturt W Manning ◽  
Bernd Kromer

The debate over the dating of the Santorini (Thera) volcanic eruption has seen sustained efforts to criticize or challenge the radiocarbon dating of this time horizon. We consider some of the relevant areas of possible movement in the14C dating—and, in particular, any plausible mechanisms to support as late (most recent) a date as possible. First, we report and analyze data investigating the scale of apparent possible14C offsets (growing season related) in the Aegean-Anatolia-east Mediterranean region (excluding the southern Levant and especially pre-modern, pre-dam Egypt, which is a distinct case), and find no evidence for more than very small possible offsets from several cases. This topic is thus not an explanation for current differences in dating in the Aegean and at best provides only a few years of latitude. Second, we consider some aspects of the accuracy and precision of14C dating with respect to the Santorini case. While the existing data appear robust, we nonetheless speculate that examination of the frequency distribution of the14C data on short-lived samples from the volcanic destruction level at Akrotiri on Santorini (Thera) may indicate that the average value of the overall data sets is not necessarily the most appropriate14C age to use for dating this time horizon. We note the recent paper of Soter (2011), which suggests that in such a volcanic context some (small) age increment may be possible from diffuse CO2emissions (the effect is hypothetical at this stage and hasnotbeen observed in the field), and that "if short-lived samples from the same stratigraphic horizon yield a wide range of14C ages, the lower values may be the least altered by old CO2." In this context, it might be argued that a substantive “low” grouping of14C ages observable within the overall14C data sets on short-lived samples from the Thera volcanic destruction level centered about 3326–3328 BP is perhaps more representative of the contemporary atmospheric14C age (without any volcanic CO2contamination). This is a subjective argument (since, in statistical terms, the existing studies using the weighted average remain valid) that looks to support as late a date as reasonable from the14C data. The impact of employing this revised14C age is discussed. In general, a late 17th century BC date range is found (to remain) to be most likelyeven ifsuch a late-dating strategy is followed—a late 17th century BC date range is thus a robust finding from the14C evidence even allowing for various possible variation factors. However, the possibility of a mid-16th century BC date (within ∼1593–1530 cal BC) is increased when compared against previous analyses if the Santorini data are considered in isolation.


TAPPI Journal ◽  
2017 ◽  
Vol 16 (01) ◽  
pp. 9-15
Author(s):  
David Knox ◽  
Peter W. Hart ◽  
Humphrey Moynihan ◽  
Nichole Kilgore

Several articles have been published during the past 30 years on different methods to produce micro- to nanosize cellulose particles from pulp. Unfortunately, a general lack of information exists on the impact of differing manufacturing process methods upon the product properties obtained from these differing methods. Literature data show that wet processing of small-sized cellulosic fibers generates handsheets with approximately equal or higher density and modulus of elasticity than controls for a given amount of added microcellulose. The current work evaluated small particle generation from pulp fibers via dry processing methods and compared the physical properties of dry versus wet processed particles. Dry processing to obtain microcellulose gave considerably lower sheet density and modulus as compared with wet processed microcellulose. The lower modulus can be compensated for by refining base fibers more aggressively to obtain higher density and higher modulus sheets. Dry processing methods for making microcellulose and their impact on final board properties, including modulus and smoothness, will be discussed.


2009 ◽  
Vol 107 (1) ◽  
pp. 302-307 ◽  
Author(s):  
Josef A. Vogt ◽  
Ulrich Wachter ◽  
Jürgen Mehring ◽  
Peter Radermacher ◽  
Michael Georgieff ◽  
...  

Nondispersive infrared spectroscopy (NDIR) allows the continuous analysis of respiratory gases. Due to its high selectivity, simple and robust setup, and small footprint, it is also used to support13CO2breath tests to assess bacterial growth in the stomach, gut, or liver function. CO2NDIR signals, however, are biased by oxygen in the gas matrix. This complicates NDIR-based breath tests, if the inspired oxygen concentration has to be adjusted to the subject's requirements, or hyperoxia-induced effects were studied. To avoid the oxygen-induced bias, a “dilution” approach was developed: expired gas is mixed with N2to lower the oxygen content down to the usual range of 15–20%. Accuracy and precision were tested using synthetic gas mixtures with increasing13CO2-to-12CO2ratios (13CO2/12CO2), either based on synthetic air with ∼20% volume O2or on pure O2. For samples with δ13C values smaller than 300 (or13CO2/12CO2smaller than 0.003), the dilution does not significantly increase the bias in the13CO2/12CO2determination, and the within-run imprecision is smaller than 1 δ13C. The practical use of this approach was validated in a pig study using a sepsis model reflecting a clinical situation that requires an increased oxygen concentration for respiration. The N2dilution eliminated the high bias in NDIR measurement, thus allowing the determination of the impact of oxygenation on glucose oxidation in patients ventilated with increased oxygen.


2020 ◽  
Vol 8 (11) ◽  
pp. 1770
Author(s):  
Marisa B. Hirsh ◽  
Julianne L. Baron ◽  
Sue M. Mietzner ◽  
John D. Rihs ◽  
Mohamed H. Yassin ◽  
...  

Water safety and management programs (WSMP) utilize field measurements to evaluate control limits and monitor water quality parameters including Legionella presence. This monitoring is important to verify that the plan is being implemented properly. However, once it has been determined when and how to sample for Legionella, it is important to choose appropriate collection and processing methods. We sought to compare processing immediate and flushed samples, filtration of different volumes collected, and sample hold times. Hot water samples were collected immediately and after a 2-min flush. These samples were plated directly and after filtration of either 100 mL, 200 mL, or 1 L. Additionally, unflushed samples were collected and processed immediately and after 1, 24, and 48 h of hold time. We found that flushed samples had significant reductions in Legionella counts compared to immediate samples. Processing 100 mL of that immediate sample both directly and after filter concentration yielded the highest concentration and percent sample positivity, respectively. We also show that there was no difference in culture values from time 0 compared to hold times of 1 h and 24 h. At 48 h, there were slightly fewer Legionella recovered than at time 0. However, Legionella counts were so variable based on sampling location and date that this hold time effect was minimal. The interpretation of Legionella culture results depends on the sample collection and processing methods used, as these can have a huge impact on the success of sampling and the validation of control measures.


2018 ◽  
Vol 48 (1) ◽  
pp. 30-44 ◽  
Author(s):  
Savita Rani ◽  
Rakhi Singh ◽  
Rachna Sehrawat ◽  
Barjinder Pal Kaur ◽  
Ashutosh Upadhyay

Purpose Pearl millet (Pennisetum glaucum) is a rich source of nutrients as compared to the major cultivated cereal crops. However, major factors which limit its utilization are the presence of anti-nutritional factors (phytate, tannins and polyphenols) which lower availability of minerals and poor keeping quality because of higher lipase activity. Therefore, this paper aims to focus on the impact of different processing methods on the nutrient composition and anti-nutritional components of pearl millet. Design/methodology/approach This is a literature review study from 1983 to 2017, focusing on studies related to pearl millet processing and their effectiveness in the enrichment of nutritional value through reduction of anti-nutritional compounds. Findings From the literature reviewed, pearl millet processing through various methods including milling, malting, fermentation, blanching and acid as well as heat treatments were found to be effective in achieving the higher mineral digestibility, retardation of off flavor, bitterness as well as rancidity problems found during storage of flour. Originality/value Through this review paper, possible processing methods and their impact on the nutrient and anti-nutrient profile of pearl millet are discussed after detailed studied of literature from journal articles and thesis.


2018 ◽  
Vol 8 (12) ◽  
pp. 2654
Author(s):  
Joaquin Mass-Sanchez ◽  
Erica Ruiz-Ibarra ◽  
Ana Gonzalez-Sanchez ◽  
Adolfo Espinoza-Ruiz ◽  
Joaquin Cortez-Gonzalez

Localization is a fundamental problem in Wireless Sensor Networks, as it provides useful information regarding the detection of an event. There are different localization algorithms applied in single-hop or multi-hop networks; in both cases their performance depends on several factors involved in the evaluation scenario such as node density, the number of reference nodes and the log-normal shadowing propagation model, determined by the path-loss exponent (η) and the noise level (σdB) which impact on the accuracy and precision performance metrics of localization techniques. In this paper, we present a statistical analysis based on the 2k factorial methodology to determine the key factors affecting the performance metrics of localization techniques in a single-hop network to concentrate on such parameters, thus reducing the amount of simulation time required. For this proposal, MATLAB simulations are carried out in different scenarios, i.e., extreme values are used for each of the factors of interest and the impact of the interaction among them in the performance metrics is observed. The simulation results show that the path-loss exponent (η) and noise level (σdB) factors have the greatest impact on the accuracy and precision metrics evaluated in this study. Based on this statistical analysis, we recommend estimating the propagation model as close to reality as possible to consider it in the design of new localization techniques and thus improve their accuracy and precision metrics.


2018 ◽  
Vol 620 ◽  
pp. A203 ◽  
Author(s):  
A. Moya ◽  
S. Barceló Forteza ◽  
A. Bonfanti ◽  
S. J. A. J. Salmon ◽  
V. Van Grootel ◽  
...  

Context. Asteroseismology has been impressively boosted during the last decade mainly thanks to space missions such as Kepler/K2 and CoRoT. This has a large impact, in particular, in exoplanetary sciences since the accurate characterization of the exoplanets is convoluted in most cases with the characterization of their hosting star. In the decade before the expected launch of the ESA mission PLATO 2.0, only two important missions will provide short-cadence high-precision photometric time-series: NASA–TESS and ESA–CHEOPS missions, both having high capabilities for exoplanetary sciences. Aims. In this work we want to explore the asteroseismic potential of CHEOPS time-series. Methods. Following the works estimating the asteroseismic potential of Kepler and TESS, we have analysed the probability of detecting solar-like pulsations using CHEOPS light-curves. Since CHEOPS will collect runs with observational times from hours up to a few days, we have analysed the accuracy and precision we can obtain for the estimation of νmax. This is the only asteroseismic observable we can recover using CHEOPS observations. Finally, we have analysed the impact of knowing νmax in the characterization of exoplanet host stars. Results. Using CHEOPS light-curves with the expected observational times we can determine νmax for massive G and F-type stars from late main sequence (MS) on, and for F, G, and K-type stars from post-main sequence on with an uncertainty lower than a 5%. For magnitudes V <  12 and observational times from eight hours up to two days, the HR zone of potential detectability changes. The determination of νmax leads to an internal age uncertainty reduction in the characterization of exoplanet host stars from 52% to 38%; mass uncertainty reduction from 2.1% to 1.8%; radius uncertainty reduction from 1.8% to 1.6%; density uncertainty reduction from 5.6% to 4.7%, in our best scenarios.


Sign in / Sign up

Export Citation Format

Share Document