Browsing by Subject "temperature"
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Item Open Access Calibrating single-ended fiber-optic Raman spectra distributed temperature sensing data.(Sensors (Basel), 2011) Hausner, Mark B; Suárez, Francisco; Glander, Kenneth E; van de Giesen, Nick; Selker, John S; Tyler, Scott WHydrologic research is a very demanding application of fiber-optic distributed temperature sensing (DTS) in terms of precision, accuracy and calibration. The physics behind the most frequently used DTS instruments are considered as they apply to four calibration methods for single-ended DTS installations. The new methods presented are more accurate than the instrument-calibrated data, achieving accuracies on the order of tenths of a degree root mean square error (RMSE) and mean bias. Effects of localized non-uniformities that violate the assumptions of single-ended calibration data are explored and quantified. Experimental design considerations such as selection of integration times or selection of the length of the reference sections are discussed, and the impacts of these considerations on calibrated temperatures are explored in two case studies.Item Open Access Demonstration and Performance Evaluation of Two Novel Algorithms for Removing Artifacts From Automated Intraoperative Temperature Data Sets: Multicenter, Observational, Retrospective Study.(JMIR perioperative medicine, 2022-10) Bardia, Amit; Deshpande, Ranjit; Michel, George; Yanez, David; Dai, Feng; Pace, Nathan L; Schuster, Kevin; Mathis, Michael R; Kheterpal, Sachin; Schonberger, Robert BBackground
The automated acquisition of intraoperative patient temperature data via temperature probes leads to the possibility of producing a number of artifacts related to probe positioning that may impact these probes' utility for observational research.Objective
We sought to compare the performance of two de novo algorithms for filtering such artifacts.Methods
In this observational retrospective study, the intraoperative temperature data of adults who received general anesthesia for noncardiac surgery were extracted from the Multicenter Perioperative Outcomes Group registry. Two algorithms were developed and then compared to the reference standard-anesthesiologists' manual artifact detection process. Algorithm 1 (a slope-based algorithm) was based on the linear curve fit of 3 adjacent temperature data points. Algorithm 2 (an interval-based algorithm) assessed for time gaps between contiguous temperature recordings. Sensitivity and specificity values for artifact detection were calculated for each algorithm, as were mean temperatures and areas under the curve for hypothermia (temperatures below 36 C) for each patient, after artifact removal via each methodology.Results
A total of 27,683 temperature readings from 200 anesthetic records were analyzed. The overall agreement among the anesthesiologists was 92.1%. Both algorithms had high specificity but moderate sensitivity (specificity: 99.02% for algorithm 1 vs 99.54% for algorithm 2; sensitivity: 49.13% for algorithm 1 vs 37.72% for algorithm 2; F-score: 0.65 for algorithm 1 vs 0.55 for algorithm 2). The areas under the curve for time × hypothermic temperature and the mean temperatures recorded for each case after artifact removal were similar between the algorithms and the anesthesiologists.Conclusions
The tested algorithms provide an automated way to filter intraoperative temperature artifacts that closely approximates manual sorting by anesthesiologists. Our study provides evidence demonstrating the efficacy of highly generalizable artifact reduction algorithms that can be readily used by observational studies that rely on automated intraoperative data acquisition.Item Open Access Finite density phase transition of QCD with N-f=4 and N-f=2 using canonical ensemble method(2010) Li, A; Alexandru, A; Liu, KF; Meng, XIn a progress toward searching for the QCD critical point, we study the finite density phase transition of N-f = 4 and 2 lattice QCD at finite temperature with the canonical ensemble approach. We develop a winding number expansion method to accurately project out the particle number from the fermion determinant which greatly extends the applicable range of baryon number sectors to make the study feasible. Our lattice simulation was carried out with the clover fermions and improved gauge action. For a given temperature, we calculate the baryon-chemical potential from the canonical approach to look for the mixed phase as a signal for the first-order phase transition. In the case of N-f = 4, we observe an "S-shape'' structure in the chemical potential-density plane due to the surface tension of the mixed phase in a finite volume which is a signal for the first-order phase transition. We use the Maxwell construction to determine the phase boundaries for three temperatures below T-c. The intersecting point of the two extrapolated boundaries turns out to be at the expected first-order transition point at T-c with mu = 0. This serves as a check for our method of identifying the critical point. We also studied the N-f = 2 case, but do not see a signal of the mixed phase for temperature as low as 0.83T(c).Item Open Access Resistance of African tropical forests to an extreme climate anomaly.(Proceedings of the National Academy of Sciences of the United States of America, 2021-05) Bennett, Amy C; Dargie, Greta C; Cuni-Sanchez, Aida; Tshibamba Mukendi, John; Hubau, Wannes; Mukinzi, Jacques M; Phillips, Oliver L; Malhi, Yadvinder; Sullivan, Martin JP; Cooper, Declan LM; Adu-Bredu, Stephen; Affum-Baffoe, Kofi; Amani, Christian A; Banin, Lindsay F; Beeckman, Hans; Begne, Serge K; Bocko, Yannick E; Boeckx, Pascal; Bogaert, Jan; Brncic, Terry; Chezeaux, Eric; Clark, Connie J; Daniels, Armandu K; de Haulleville, Thales; Djuikouo Kamdem, Marie-Noël; Doucet, Jean-Louis; Evouna Ondo, Fidèle; Ewango, Corneille EN; Feldpausch, Ted R; Foli, Ernest G; Gonmadje, Christelle; Hall, Jefferson S; Hardy, Olivier J; Harris, David J; Ifo, Suspense A; Jeffery, Kathryn J; Kearsley, Elizabeth; Leal, Miguel; Levesley, Aurora; Makana, Jean-Remy; Mbayu Lukasu, Faustin; Medjibe, Vincent P; Mihindu, Vianet; Moore, Sam; Nssi Begone, Natacha; Pickavance, Georgia C; Poulsen, John R; Reitsma, Jan; Sonké, Bonaventure; Sunderland, Terry CH; Taedoumg, Hermann; Talbot, Joey; Tuagben, Darlington S; Umunay, Peter M; Verbeeck, Hans; Vleminckx, Jason; White, Lee JT; Woell, Hannsjoerg; Woods, John T; Zemagho, Lise; Lewis, Simon LThe responses of tropical forests to environmental change are critical uncertainties in predicting the future impacts of climate change. The positive phase of the 2015-2016 El Niño Southern Oscillation resulted in unprecedented heat and low precipitation in the tropics with substantial impacts on the global carbon cycle. The role of African tropical forests is uncertain as their responses to short-term drought and temperature anomalies have yet to be determined using on-the-ground measurements. African tropical forests may be particularly sensitive because they exist in relatively dry conditions compared with Amazonian or Asian forests, or they may be more resistant because of an abundance of drought-adapted species. Here, we report responses of structurally intact old-growth lowland tropical forests inventoried within the African Tropical Rainforest Observatory Network (AfriTRON). We use 100 long-term inventory plots from six countries each measured at least twice prior to and once following the 2015-2016 El Niño event. These plots experienced the highest temperatures and driest conditions on record. The record temperature did not significantly reduce carbon gains from tree growth or significantly increase carbon losses from tree mortality, but the record drought did significantly decrease net carbon uptake. Overall, the long-term biomass increase of these forests was reduced due to the El Niño event, but these plots remained a live biomass carbon sink (0.51 ± 0.40 Mg C ha-1 y-1) despite extreme environmental conditions. Our analyses, while limited to African tropical forests, suggest they may be more resistant to climatic extremes than Amazonian and Asian forests.Item Open Access Thyroid hormone fluctuations indicate a thermoregulatory function in both a tropical (Alouatta palliata) and seasonally cold-habitat (Macaca fuscata) primate.(Am J Primatol, 2017-11) Thompson, Cynthia L; Powell, Brianna L; Williams, Susan H; Hanya, Goro; Glander, Kenneth E; Vinyard, Christopher JThyroid hormones boost animals' basal metabolic rate and represent an important thermoregulatory pathway for mammals that face cold temperatures. Whereas the cold thermal pressures experienced by primates in seasonal habitats at high latitudes and elevations are often apparent, tropical habitats also display distinct wet and dry seasons with modest changes in thermal environment. We assessed seasonal and temperature-related changes in thyroid hormone levels for two primate species in disparate thermal environments, tropical mantled howlers (Alouatta palliata), and seasonally cold-habitat Japanese macaques (Macaca fuscata). We collected urine and feces from animals and used ELISA to quantify levels of the thyroid hormone triiodothyronine (fT3). For both species, fT3levels were significantly higher during the cooler season (wet/winter), consistent with a thermoregulatory role. Likewise, both species displayed greater temperature deficits (i.e., the degree to which animals warm their body temperature relative to ambient) during the cooler season, indicating greater thermoregulatory pressures during this time. Independently of season, Japanese macaques displayed increasing fT3levels with decreasing recently experienced maximum temperatures, but no relationship between fT3and recently experienced minimum temperatures. Howlers increased fT3levels as recently experienced minimum temperatures decreased, although demonstrated the opposite relationship with maximum temperatures. This may reflect natural thermal variation in howlers' habitat: wet seasons had cooler minimum and mean temperatures than the dry season, but similar maximum temperatures. Overall, our findings support the hypothesis that both tropical howlers and seasonally cold-habitat Japanese macaques utilize thyroid hormones as a mechanism to boost metabolism in response to thermoregulatory pressures. This implies that cool thermal pressures faced by tropical primates are sufficient to invoke an energetically costly and relatively longer-term thermoregulatory pathway. The well-established relationship between thyroid hormones and energetics suggests that the seasonal hormonal changes we observed could influence many commonly studied behaviors including food choice, range use, and activity patterns.