ΔT Difference Research Articles

Radiation error of air temperature measurements: Minimization of the error by a new reference system and comparison with conventional measurement systems, diurnal and annual variation of their errors as a function of radiation and wind speed

Abstract The measurement of air temperature is associated with inaccuracies resulting from radiation errors. Liquid thermometers and automatic sensors are therefore housed in screens. Mechanical ventilation also helps to increase the accuracy of readings. Nonetheless, temperature measurements are not completely accurate. This spurred the development of a measuring system that features improved radiation protection and a modified mechanical ventilation system through a new type of screen. Parallel measurements with this new measurement system and two conventional screens of multiple plastic cones were taken at a location in north-east Germany with a temperate climate. Of the two traditional screens, one was ventilated and the other not. Based on previous findings concerning the seasonality of radiation errors, our analysis of their dependency on global radiation and wind speed was focused on the months of May to August, when global radiation is at its strongest. It was found that the not insignificant differences in Δ T \Delta T display a characteristic diurnal variation. With the new measurement system, in comparison with the two conventional measurung systems, the average air temperature of the four surveyed months during daylight hours was 0.43 K and 0.58 K lower. The differences in Δ T \Delta T are greatest not in the middle of the day but when the sun is low in the sky, as radiation is then reflected into the screen. The findings contribute to the understanding of the temporal variability of radiation errors in modern weather stations in dependence on global radiation and wind speed. The technical innovations presented here allow radiation errors to be largely avoided.

Does cerebrospinal fluid pulsation affect diffusion-weighted imaging thermometry? A study in healthy volunteers.

Diffusion-weighted imaging (DWI)-based thermometry offers potential as a noninvasive method for measuring temperatures deep inside the human brain. However, DWI might be influenced by the pulsatile flow of cerebrospinal fluid (CSF). This study aimed to investigate the influence of such pulsations on DWI thermometry in healthy individuals. A total of 104 participants (50 men, 54 women; mean [± standard deviation] age, 44.2 ± 14.3years; range 21-69 years) were investigated. DWI-based brain temperature (TDWI ) was acquired at three speeds (maximum and minimum speeds of ascending flow and random timing at the cerebral aqueduct) of CSF pulsation using a 3-T magnetic resonance imaging scanner. Magnetic resonance spectroscopy (MRS)-based temperature (TMRS ) at the thalamus was also obtained as a reference standard for brain temperature. The three different CSF pulsatile flows were monitored by heart rate during the scan. The difference between reference temperature and brain temperature (ΔT = TDWI - TMRS ) along with the three CSF speeds were statistically compared using Student's matched pair t-test. No significant difference in ΔT was evident among CSF speeds (p>0.05). No significant linear correlation between ΔT and CSF flow speed at the cerebral aqueduct was observed. Using DWI thermometry with clinical acquisition settings, which utilizes mean values within thresholds, no effect of CSF pulsation speed was observed in the estimation of ΔT.

Revisiting the thermoregulation hypothesis of osteoderms: a study of the crocodilianPaleosuchus palpebrosus(Crocodilia: Alligatoridae)

AbstractThe functional significance of osteoderms—ossified bony structures in the dermis—has been a topic of discussion for many years in biological sciences. Although a protective function has received significant attention in the past, evidence is accumulating that osteoderms might play an important role during physiological activities, specifically thermoregulation. Previous studies have shown that, in crocodilians, the temperature of the skin overlying the osteoderms differs from that of the non-ossified skin during basking. The direction of these differences, however, appears to vary among studies, warranting the re-evaluation of a potential thermoregulatory function. In this study, we explored the thermal benefits of osteoderm expression in dwarf caimans (Paleosuchus palpebrosus). We compared the difference in dorsal and lateral skin temperatures (ΔT) between individuals with fully developed osteoderms and those devoid of any osteoderms, under three different temperature gradients. Our results show that although significant differences in ΔT are present between individuals and between temperature gradients, they do not relate to the expression of osteoderms. The findings of the present study question the thermoregulatory role that osteoderms play in P. palpebrosus, and vertebrates in general, and we put forward a series of alternative (physiological) hypotheses explaining their enigmatic nature.

A multicity analysis of daytime Surface Urban Heat Islands in India and the US.

• In the US, urban land surface temperature (LST) was higher compared to rural LST. • Despite urbanization, urban LST in India was lower compared to rural LST. • Non-photosynthetic vegetation (NPV) and barren land types influence the results. • Built-up indices used here do not differentiate sparse vegetation and built-up surfaces. • New methods are needed for quantifying urbanization's impact on LST in India. Daytime surface UHI (SUHI) and the factors influencing it across highly populated cities in India and the United States (US) were evaluated. Urban-rural mean land surface temperature (LST) differences (ΔT S ) were calculated and correlated with vegetation and built-up surface densities, quantified using the Normalized Difference Vegetation Index (NDVI) and Index Based Built-Up Index (IBI) respectively. The results from the US show a conventional SUHI phenomenon, and LST decrease with increasing vegetation and decreasing built-up surfaces. However, in India, despite existing urban densities, urban areas are cooler than the rural surroundings. The average LST was higher and NDVI was lower compared to the US, and NDVI and LST correlations were weak. Furthermore, in India, the average IBI values calculated for built-up areas, cropland, and other sparse vegetation land covers were approximately equal. The prevalence of non-photosynthetic vegetation (NPV) and barren soil in India are impacting spectral indices and the correlations. Differences in ΔT S and spectral indices trends between India and US highlight the shortcomings of the indices used in appropriately identifying Indian LULC types and establish the need for localized SUHI research methods that can specifically analyze the impact of urbanization on SUHI in India.

Stratospheric carbon isotope fractionation and tropospheric histories of CFC-11, CFC-12, and CFC-113 isotopologues

Abstract. We present novel measurements of the carbon isotope composition of CFC-11 (CCl3F), CFC-12 (CCl2F2), and CFC-113 (CF2ClCFCl2), three atmospheric trace gases that are important for both stratospheric ozone depletion and global warming. These measurements were carried out on air samples collected in the stratosphere – the main sink region for these gases – and on air extracted from deep polar firn snow. We quantify, for the first time, the apparent isotopic fractionation, ϵapp(13C), for these gases as they are destroyed in the high- and mid-latitude stratosphere: ϵapp(CFC-12, high-latitude) =(-20.2±4.4) ‰, and ϵapp(CFC-113, high-latitude) =(-9.4±4.4) ‰, ϵapp(CFC-12, mid-latitude) =(-30.3±10.7) ‰, and ϵapp(CFC-113, mid-latitude) =(-34.4±9.8) ‰. Our CFC-11 measurements were not sufficient to calculate ϵapp(CFC-11), so we instead used previously reported photolytic fractionation for CFC-11 and CFC-12 to scale our ϵapp(CFC-12), resulting in ϵapp(CFC-11, high-latitude) =(-7.8±1.7) ‰ and ϵapp(CFC-11, mid-latitude) =(-11.7±4.2) ‰. Measurements of firn air were used to construct histories of the tropospheric isotopic composition, δT(13C), for CFC-11 (1950s to 2009), CFC-12 (1950s to 2009), and CFC-113 (1970s to 2009), with δT(13C) increasing for each gas. We used ϵapp(high-latitude), which was derived from more data, and a constant isotopic composition of emissions, δE(13C), to model δT(13C, CFC-11), δT(13C, CFC-12), and δT(13C, CFC-113). For CFC-11 and CFC-12, modelled δT(13C) was consistent with measured δT(13C) for the entire period covered by the measurements, suggesting that no dramatic change in δE(13C, CFC-11) or δE(13C, CFC-12) has occurred since the 1950s. For CFC-113, our modelled δT(13C, CFC-113) did not agree with our measurements earlier than 1980. This discrepancy may be indicative of a change in δE(13C, CFC-113). However, this conclusion is based largely on a single sample and only just significant outside the 95 % confidence interval. Therefore more work is needed to independently verify this temporal trend in the global tropospheric 13C isotopic composition of CFC-113. Our modelling predicts increasing δT(13C, CFC-11), δT(13C, CFC-12), and δT(13C, CFC-113) into the future. We investigated the effect of recently reported new CFC-11 emissions on background δT(13C, CFC-11) by fixing model emissions after 2012 and comparing δT(13C, CFC-11) in this scenario to the model base case. The difference in δT(13C, CFC-11) between these scenarios was 1.4 ‰ in 2050. This difference is smaller than our model uncertainty envelope and would therefore require improved modelling and measurement precision as well as better quantified isotopic source compositions to detect.

A climatology of surface–air temperature difference over the Tibetan Plateau: Results from multi‐source reanalyses

AbstractThe Tibetan Plateau (TP), known as earth's “Third Pole,” influences regional and even global weather and climate systems through its mechanical and thermal‐dynamical forcing. Near‐surface (2 m) air temperature (Ta) and surface (skin) temperature (Ts) are two crucial parameters of land–atmosphere interactions and climate change. Their difference (ΔT = Ts − Ta) determines the heating source over the TP that drives the Asian summer monsoon. This study focuses on climatology, inter‐annual variability, and long‐term trend of ΔT over the TP in the last four decades (1979–2018), based on four latest reanalysis datasets including ERA‐Interim, ERA5, MERRA2, and JRA55, along with observational data. We show that ΔT‐based different datasets display fairly different climatology in terms of seasonality, spatial distribution, and long‐term trend. ΔT exhibits a clear seasonality with negative value in winter and positive ones in summer despite different strengths and timings presented by the reanalyses. Along with global warming, all reanalyses except JRA55 exhibit obvious downwards trends of ΔT in a spatially non‐uniform way. The median ΔT among the four reanalyses features uniform decreases in all seasons, with the most distinct area on the northern TP, as well as the largest and least decreases in autumn and spring, respectively. Further analysis shows that the differences in ΔT are most likely associated with discrepancies in radiation forcing, snow cover, wind speed, and boundary layer height within the reanalyses. The present findings highlight the difficulty for the state‐of‐the‐art reanalyses to represent the climate change over the TP and point to possible factors behind the deficiencies identified.

Contrasting Temperature and Precipitation Patterns of Trees in Different Seasons and Responses of Infrared Canopy Temperature in Two Asian Subtropical Forests

Canopy temperature (Tc), one of the most important plant ecophysiological parameters, has been known to respond rapidly to environmental change. However, how environmental factors—especially the temperature and precipitation pattern—impact Tc has been less discussed for forest stands. In this study, we investigated seasonal variations and responses of the Tc and canopy-to-air temperature difference (ΔT) associated with environmental conditions in two subtropical forests with contrasting temperature and precipitation patterns—Dinghushan (DHS) (temperature and precipitation synchronous site: hot and wet in the summer) and Qianyanzhou (QYZ) (temperature and precipitation asynchronous site: hot and arid in the summer). The results showed that Tc exhibits clear diurnal and seasonal variations above air temperature throughout the day and year, suggesting that the canopy of both DHS and QYZ is typically warmer than ambient air. However, the canopy-warming effect was substantially intensified in QYZ, and the difference of ΔT between dry and wet seasons was small (−0.07 °C) in DHS, while it was up to 0.9 °C in QYZ. Regression analysis revealed that this resulted from the combined effects of the increased solar radiation and vapor pressure deficit (VPD), but reduced canopy conductance (gc) caused by drought in the summer in QYZ. Sensitivity analysis further indicated that the responses of ΔT to VPD and gc changes were quite divergent, presenting negative responses to the enhanced VPD and gc in QYZ, while there were positive responses in DHS. The high productivity coupled with low transpiration cooling that occurs in a temperature and precipitation synchronous condition mainly contributes to the positive responses of ΔT in DHS. This study reveals the seasonal variations, environmental responses, and underlying causes of Tc under different temperature and precipitation patterns, providing useful information for the regional assessment of plant responses to future climate change.

Basking African striped mice choose warmer locations to heat up: evidence from a field study

AbstractBasking in the sun is an important energy‐saving tactic in ectotherm animals. It has also been recognized to be important in several mammal species, especially in arid environments. In particular, small mammals that have a greater surface‐to‐volume ratio can use basking to reduce metabolic energy expenditure by using external heat to maintain a high body temperature. If basking mainly functions to passively gain heat, animals should choose basking spots that offer a more favorable micro‐climate for warming up. We tested this hypothesis in African striped mice (Rhabdomys pumilio), a diurnal species that is known to bask. Over 19 months, we displaced 138 individuals from their basking spots and immediately thereafter measured the temperature of the surface (Ts) at these spots. We expected that striped mice choose spots for basking that are warmer than random spots, especially in (1) the morning, when Ts is lower compared to afternoon, and (2) the dry season characterized by low food availability in which energy gain due to basking is more beneficial than in the moist season with high food availability. Moreover, we tested whether there are differences in relative safety (measured as available plant cover) at basking spots compared to random spots. Temperature of the surface (Ts) was significantly higher at basking spots than at random spots. However, we did not find any differences in ΔT in relation to season, time of the day or in the safety between basking and random spots. In conclusion, our study indicates that striped mice choose basking spots with a favourable microclimate characterized by higher surface temperature.

Analysis of temperature increase in swine gingiva after exposure to a Polywave® LED light curing unit

ObjectiveThis study evaluated the temperature increase in swine gingival temperature after exposure to light emitted by a Polywave® LED light curing unit (LCU, Bluephase 20i, Ivoclar Vivadent). MethodsAfter local Ethics Committee approval (protocol 711/2015), 40 pigs were subjected to general anesthesia and the LCU tip was placed 5mm from the buccal gingival tissue (GT) close to lower lateral incisors. A thermocouple probe (Thermes WFI, Physitemp) was inserted into the gingival sulcus before and immediately after exposure to light. Real-time temperature (°C) was measured after the following exposure modes were applied: High Power (20s-H, 40s-H, and 60s-H) or Turbo mode (5s-T), either with or without the presence of rubber dam (RD) interposed between the LCU tip and GT (n=10). The presence of gingival lesions after the exposures was also evaluated. Peak temperature (°C) and the temperature increase during exposure over that of the pre-exposure baseline value (ΔT) data were analyzed using 2-way ANOVA followed by Bonferroni’s post-hoc test (α=5%). A binary logistic regression analysis determined the risk of gingival lesion development. ResultsWithout RD, no significant difference in ΔT was observed among 20s-H, 40s-H, and 60s-H groups, which showed the highest temperature values, while the 5s-T exposure showed the lowest ΔT, regardless of RD. RD reduced ΔT only for the 20s-H group (p=0.004). Gingival lesions were predominantly observed using 40s-H, with RD, and 60s-H, with and without RD. SignificanceExposure to a LCU light might be harmful to swine gingiva only when high radiant exposure values are delivered, regardless of the use of RD.

Effect of Thermal Distress on Residual Behavior of CFRP-Strengthened Steel Beams Including Periodic Unbonded Zones

This paper presents the residual behavior of wide-flange steel beams strengthened with high-modulus carbon fiber-reinforced polymer (CFRP) laminates subjected to thermal loading. Because the coefficients of thermal expansion of the steel and the CFRP are different, temperature-induced distress may take place along their interface. Periodic unbonded zones are considered to represent local interfacial damage. Five test categories are designed depending on the size of the unbonded zones from 10 to 50 mm, and corresponding beams are loaded until failure occurs after exposing to a cyclic temperature range of ΔT = 25 °C (−10 to 15 °C) up to 84 days. The composite action between the CFRP and the steel substrate is preserved until yielding of the beams happens, regardless of the thermal cycling and periodic unbonded zones. The initiation and progression of CFRP debonding become apparent as the beams are further loaded, particularly at geometric discontinuities in the vicinity of the unbonded zones along the interface. A simple analytical model is employed to predict the interfacial stress of the strengthened beams. A threshold temperature difference of ΔT = 30 °C is estimated for the initiation and progression of CFRP debonding. Multiple debonding-progression stages in conjunction with the extent of thermal distress appear to exist. It is recommended that high-modulus CFRP be restrictively used for strengthening steel members potentially exposed to a wide temperature variation range.

Do greater rates of body heat storage precede the accelerated reduction of self-paced exercise intensity in the heat?

To reevaluate the previous hypothesis that greater reductions in self-paced exercise intensity in the heat are mediated by early differences in the rate of body heat storage (S). Eight trained volunteers cycled in 19 °C/1.8 kPa (COOL), 25 °C/1.2 kPa (NORM), and 34 °C/1.6 kPa (HOT), while maintaining an RPE of 16. Potential differences in S following the onset of exercise were assessed by comparing rates of esophageal temperature change (ΔT es/Δt); and estimated S values using a traditional two-compartment thermometric model (S therm) of changes in rectal (T re) and skin (T sk) temperature, and partitional calorimetry (S cal). After 15 min of exercise, workload decreased more in HOT vs. COOL (P = 0.03), resulting in a shorter time (HOT: 40.7 ± 14.9 min; COOL: 53.5 ± 18.7 min; P = 0.04) to 70 % of initial workload. However, there were no preceding differences in ΔT es/Δt between conditions (P = 0.18). S therm values were different between HOT and COOL during the first 5 min of exercise (P < 0.05), primarily due to negative S therm values (-32 ± 15 kJ min(-1)) in COOL, which according to partitional calorimetric measurements, required improbably high (~56 kJ min(-1)) rates of evaporation when no sweating on the back and thigh was observed until after 7.6 ± 1.5 min and 4.8 ± 1.7 min of exercise, respectively. S cal values in the first 5 min of exercise confirmed S was actually positive in COOL (+21 ± 8 kJ min(-1)) and not negative. Different S therm values following the onset of exercise at different environmental temperatures are simply due to transient differences in the rate of change in T sk. Reductions in self-paced exercise intensity in the heat are not mediated by early differences in S following the onset of exercise.

Is Thermography Useful for Assessment of Postoperative Inflammation After Surgical Removal of Mandibular Third Molars When Methylprednisolone Is Administered and How Does It Correlate With Patients' Perception of Swelling?

To assess the differences in facial skin temperature after mandibular third molar removal when patients received methylprednisolone and placebo, respectively and to assess the correlation between patient-reported swelling using a visual analog scale (VAS) and facial skin temperature measured using thermography. The study involved patients with 2 mandibular third molars with an indication for removal. The patients received either methylprednisolone or placebo in a randomized, crossover study design. Thermograms and the swelling VAS score were recorded 2 days after surgery. The outcome variable was the temperature difference (Δt) between the operated and control sides. A 2-sample t test analyzed the difference in Δt between the first and second operations. Spearman's rank correlation analysis was used to assess the correlation between the swelling VAS scores and the Δt. A total of 124 patients (67 males, 57 females, mean age 25 years) had both mandibular third molars removed on 2 separate occasions. No difference in Δt was found when methylprednisolone and placebo were given (P = .07). In addition, the correlation between the swelling VAS score and Δt was 0.30 (P = .001) and 0.09 (P = .3) after the first and second operation, respectively. Thermography does not seem sensitive enough to detect differences in the inflammatory response when patients received methylprednisolone or placebo. The correlation between the Δt and patient-reported swelling was low (≤0.3).

Assessment of colorectal hepatic metastases by quantitative T2 relaxation time

To determine the T(2) relaxation time of colorectal hepatic metastases and changes in T(2) relaxation times following chemotherapy. 42 patients with 96 hepatic colorectal metastases underwent baseline MRI. Axial T(1), T(2) and multi-echo GRASE sequences were acquired. ROIs were drawn on T(2) relaxation maps, obtained from GRASE images, encompassing metastasis and normal liver to record T(2) relaxation time values. In 11 patients with 28 metastases, MRI was repeated using same protocol at 6 weeks following chemotherapy. The median pre-treatment T(2) values of metastases and normal liver were compared using the Mann-Whitney test. The pre- and post-treatment median T(2) values of metastases were compared using the Wilcoxon-Rank test for responding (n=16) and non-responding (n=12) lesions defined by RECIST criteria. The change in T(2) values (ΔT(2)) were compared and correlated with percentage change in lesion size. There was no difference in the pre-treatment median T(2) of metastases between responding (67.3±8.6) and non-responding metastases (71.4±16.5). At the end of chemotherapy, there was a decrease in the median T(2) of responding lesions (61.6±12.6) p=0.83, and increase in non-responding lesions (76.2±18.4) p=0.03, but these were not significantly different from the pre-treatment values. There was no significant difference in ΔT(2) of responding and non-responding lesions (p=0.18) and no correlation was seen between size change and ΔT(2) (coefficient=0.3). T(2) relaxation time does not appear to predict response of colorectal liver metastasis to chemotherapy.

Day-of-the-week variations of urban temperature and their long-term trends in Japan

Temperature differences among days of the week and their long-term trends were evaluated using 29 years of hourly data from the Automated Meteorological Data Acquisition System network of Japan. Stations were categorized with respect to the population density around each site, and an urban temperature anomaly (δT*) was defined as a departure from the spatial average of nearby rural stations. On Saturdays and holidays (Sundays and national holidays), δT* was lower than on weekdays by 0.2–0.25°C at Tokyo, by 0.1–0.2°C at Osaka, and by about 0.02°C at stations where the population density was 300 to 1,000 km–2. Moreover, δT* showed a relative decreasing trend over the long term on Mondays and an increasing trend on Fridays, at a rate of about 0.05–0.1°C decade–1 at Tokyo and about 0.02°C decade–1 at stations where the population density was 100 to 1,000 km–2, but no significant difference in δT* trends was observed between weekdays and weekend days.

SKS/SKKS splitting and Taiwan orogeny

We determine 58 sets of splitting parameters, fast direction (φ) and delay time (δt), from broadband SKS/SKKS waves recorded at temporary and permanent stations in Taiwan. These and earlier results, from S and ScS as well as SKS, show an island‐wide pattern of φ alignment with N–NNE structural trends in southern and central Taiwan and then turn smoothly to EW following the structural bight in northern Taiwan. Remarkable differences in δt for eastern and southwestern events are found, resulting probably from a more anisotropic upper mantle in the east, under the Central Range. With δt an average of 1.3 seconds our observations are consistent with the hypothesis that the orogeny involves shear or flow in the upper mantle in central and southern Taiwan. In northern Taiwan, near the ends of the collision and subduction zones, the extrusion and the hydration of olivine may contribute to the orientation of φ.

Some features of climate change on Earth and its possible relation to solar-activity variations

The global warming on Earth during the last century has been discussed in many studies. The most significant factors of climate change are the increase in the atmospheric concentration of greenhouse gases, catastrophic eruptions of volcanoes, and variations in the solar activity. In this paper, we consider the character of climate change and its possible relation to solar-activity variations using the data of the global network of meteorological stations on temperature variations in different regions across the globe from 1880 and information about variations in the relative sunspot number over the last 300 years and temporal variations in the total solar irradiation. We found that the annual mean sunspot number increased on average by about 0.2% per year in both 11-year and secular cycles. The increase in the globally averaged surface air temperature in the period 1880–2004 was Δt = 0.61 ± 0.04 °C. The difference in Δt calculated for periods with different solar-activity levels in 11-year cycles was estimated. This difference was most clearly revealed over land at high latitudes of the northern hemisphere. The medians of the distributions of the annual mean surface air temperature over land, ocean, and over the entire globe in years with high solar activity in the secular cycle are significantly greater than the corresponding values related to the years of low solar activity. Noticeable falls in temperature (by ∼0.1–0.2°C) through ∼1900–1920 and 1945–1980 are likely to be associated with the radiation balance perturbation caused by a large number of catastrophic volcanic eruptions during these periods. A considerable warming during the last three decades is most probably due to the substantial growth in the rate of carbon dioxide input to the atmosphere and the corresponding large increase in its concentration. The importance of this factor of global warming becomes even greater if we bear in mind that the solar activity in the secular cycle declines after 1970.

Correlation Between Morphologic Characteristics and Local Temperature Differences in Culprit Lesions of Patients With Symptomatic Coronary Artery Disease

The purpose of this study was to investigate the possible correlation between morphologic and functional characteristics of culprit lesions (CL) in patients with acute coronary syndromes (ACS) and chronic stable angina (CSA). Intravascular ultrasound (IVUS) provides morphologic assessment and intracoronary thermography (ICT) evaluates the local inflammatory activation of CL. Eighty-one consecutive patients, 48 with ACS and 33 with CSA, were enrolled. Ratio of lesion to reference external elastic membrane area, indicated by IVUS, was defined as positive remodeling index (pRi) (> or =1) or negative remodeling index (nRi) (<1). We also investigated the existence of ruptured plaque (rp) in the CL. By ICT temperature difference (DeltaT) between the CL and the proximal vessel wall was measured. Patients with ACS had greater remodeling index than patients with CSA (1.15 +/- 0.18 vs. 0.90 +/- 0.12; p < 0.01), as well as increased DeltaT (0.08 +/- 0.03 degrees C vs. 0.04 +/- 0.02 degrees C; p < 0.01). Patients with pRi had higher DeltaT than patients with nRi (0.07 +/- 0.03 degrees C vs. 0.04 +/- 0.02 degrees C; p < 0.001). In patients with nRi there was no difference in DeltaT between ACS and CSA (p = 0.22). Patients with rp had increased DeltaT compared with patients without rp (0.09 +/- 0.03 degrees C vs. 0.05 +/- 0.02 degrees C; p < 0.01). Multivariate analysis showed that DeltaT was independently correlated with the presence of rp, pRi, and ACS. The present study showed that culprit lesions with plaque rupture and positive arterial remodeling have increased thermal heterogeneity, although in certain patients a discrepancy between morphogic and functional characteristics was observed. A combination of morphologic and functional examination may offer additional diagnostic and prognostic information.

Determination of Stellar Ellipticities in Future Microlensing Surveys

We propose a method that can determine the ellipticities of source stars of microlensing events produced by binary lenses. The method is based on the fact that the products of the caustic-crossing timescale, Δt, and the cosine of the caustic incidence angle of the source trajectory, κ, of the individual caustic crossings are different for events involving an elliptical source, while the products are the same for events associated with a circular source. The product Δt⊥ = Δt cos κ corresponds to the caustic-crossing timescale when the incidence angle of the source trajectory is κ = 0. For the unique determination of the source ellipticity, resolutions of at least three caustic crossings are required. Although this requirement is difficult to achieve under the current observational setup based on alert/follow-up mode, it will be possible with the advent of future lensing experiments that will survey wide fields continuously at high cadence. For typical Galactic bulge events, the difference in Δt⊥ between caustic crossings is of the order of minutes, depending on the source orientations and ellipticities. Considering the monitoring frequency of the future lensing surveys of ~6 times hr-1 and the improved photometry, especially of the proposed space-based survey, we predict that ellipticity determinations by the proposed method will be possible for a significant fraction of multiple caustic-crossing binary lens events involving source stars having nonnegligible ellipticities.

The combined effects of ambient temperature and enforced sustained swimming activity on body temperatures of arctic charr ( Salvelinus alpinus L.)

1. 1.|The difference between tissue temperatures and ambient water temperatures ( ΔT) of the ectothermic Arctic charr ( Salvelinus alpinus L.) ranged between 0.2 and 0.6°C. 2. 2.|For fish held at 5.7°C there were no significant differences in ΔT of exercising fish and those of controls. 3. 3.|By contrast, for fish held at 1.7°C sustained exercise led to a significant increase in ΔT of all body compartments compared with fish held in standing water (controls). 4. 4.|It is suggested that Arctic charr are capable of a limited control of metabolic heat exchange between body compartments and surrounding water when subjected to sustained exercise and ambient temperatures <2°C.

Helix‐Coil transition in polypeptides: A microscopical approach

AbstractAnalogous with the Potts model that describes the helix‐coil transition in the isolated polypeptide chain (a Hamiltonian model allowing for the energy U of hydrogen bond formation) the number Q of conformational states of a repeating unit of the chain and the topology of Δ = 3 hydrogen bond formation (the hydrogen bond fixing three pairs of φψ chain rotations) has been constructed and the corresponding transfer‐matrix has been obtained. In the thermodynamical limit, the partition function is expressed through the principal root of the cubic equation. The degree of helicity, the transition point and range, the correlation length, the number of junctions between the helical and coiling sections as well as the mean length of helical and coiling sections are calculated. Empirically introduced parameters of the Zimm–Bragg theory, constants of hydrogen bond formation s, and the cooperativity parameter σ as functions of microscopic parameters U, Q, and Δ are obtained by direct calculations. The behavior of this model was investigated at other topologies of the hydrogen‐bond closing Δ = 2 and Δ = 4, and it was suggested that the actual polypeptide chain (Δ = 3) provides the optimum correlation of helical structure of the order of globule dimensions. An expression was obtained for the maximum correlation length of the order ξ ∼ Q(Δ‐1)/2. For a System with solvent competing for the formation of hydrogen bonds with peptide groups a Hamiltonian model was constructed that took account of the energy E of the formation of hydrogen bond with the solvent and the number q of orientations of a solvent molecule about the peptide groups. It is shown that by the redefinition of the temperature parameter, the model with solvent reduces to the model of an isolated chain. Aside from the definition relationship that exists between the parameters of the theory U &lt; 2E &lt; Uq and the ordinary helix‐coil transitions (“melting”), the model also describes the transition from the coiling state to the helical one (“arrangement”) under heating. The change in temperature and transition range with solvent parameters was discussed and it was shown, that despite the difference in ΔT for the given polypeptide chain (Q = constant) with different solvent parameters, at “melting” and “arrangement,” the transition occurred at the same correlation length (the same cooperativity).