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Search Results: 1 - 10 of 10414 matches for " temperature "
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Active Management of Plant Canopy Temperature as a Tool for Modifying Plant Metabolic Activity  [PDF]
James R. Mahan, John J. Burke
American Journal of Plant Sciences (AJPS) , 2015, DOI: 10.4236/ajps.2015.61028
Abstract: The relationship between a plant and its thermal environment is a major determiner of its growth and development. Since plants grow and develop within continuously variable thermal environments, they are subjected to continuous thermal variation over their life cycle. Transpiration serves to uncouple the temperature of the plant from that of its environment in a manner that reduces the occurrence of high temperature stresses that can limit plant performance. In some agriculturally important plants, there are desirable metabolic outcomes that are associated with specific stress events (e.g. wine grapes). In these plants it is often desirable to induce temperature and water stresses of known magnitude and duration at specific points in the growing season. In this study we used a computer-controlled irrigation system that used cotton canopy temperature to control irrigation in greenhouse-grown plants over a 10-day period. The system was designed to irrigate in a manner that altered the canopy temperature relative to specific temperature thresholds (28°C, 30°C, 32°C and 34°C). The results demonstrate that automated irrigation management based on canopy temperature is capable of altering the temporal pattern of canopy temperature in a desired manner using a feed-back loop. Potential limitations on this action are related to the range of air temperatures, radiation and humidity within the environment.
Predicting Hourly Stream Temperatures Using the Equilibrium Temperature Model  [PDF]
Cindie Hébert, Daniel Caissie, Mysore G. Satish, Nassir El-Jabi
Journal of Water Resource and Protection (JWARP) , 2015, DOI: 10.4236/jwarp.2015.74026
Abstract: Water temperature is a key physical habitat determinant in lotic ecosystems as it influences many physical, chemical and biological properties of rivers. Hence, a good understanding of the thermal regime of rivers is essential for effective management of water and fisheries resources. This study deals with the modeling of hourly stream water temperature using the equilibrium temperature model. This water temperature model was applied on two thermally different watercourses, namely, the Little Southwest Miramichi River (LSWM) and Catamaran Brook (CatBk; New Brunswick). The equilibrium temperature model is a simplified version of a deterministic model. As such, in the equilibrium temperature model the total heat flux at the surface is assumed proportional to the difference between the water temperature and an equilibrium temperature. In the present study, the equilibrium temperature was assumed to vary linearly with hourly air temperature. This study showed that there was a good relationship between the equilibrium and air temperature at the hourly time scale. The root-mean-square error (RMSE) obtained with the hourly equilibrium temperature model was similar to results reported in previous studies with values of 1.05°C (CatBk) and 1.36°C (LSWM). The model’s performance was best in late summer and autumn when water levels were low. In contrast, the presence of snowmelt in the spring resulted in poorer performances. This study also showed good results in estimating the daily mean (Tmean) and maximum (Tmax) water temperatures from the predicted hourly water temperatures, which were often required in fishery management.
Temperature estimation of focused ultrasound exposures for stroke treatment  [PDF]
Venediktos Hadjisavvas, Christakis Damianou
Journal of Biomedical Science and Engineering (JBiSE) , 2011, DOI: 10.4236/jbise.2011.45052
Abstract: Introduction: In this paper a simulation model for predicting the temperature during the application of focused ultrasound (FUS) for stroke treatment using pulsed ultrasound is presented. Materials and methods: A single element spherically focused transducer of 5 cm diameter, focusing at 10 cm and operating at either 0.5MHz or 1MHz was considered. The power field was estimated using the Khokhlov-Zabolot-skaya-Kuznetzov (KZK) model. The temperature was estimated using the bioheat equation. The goal was to extract the acoustic parameters (frequency, power, and duty factor) that maintain a temperature increase of less than 1oC during the application of a pulse ultrasound protocol. Results: It was found that the temperature change increases linearly with duty factor. The higher the power, the lower the duty factor needed to keep the temperature change to the safe limit of 1oC. The higher the frequency the lower the duty factor needed to keep the temperature change to the safe limit of 1oC. Finally, the shallow the target, the lower the duty factor needed to keep the temper-ature change to the safe limit of 1oC. The simulation model was tested in brain tissue during the application of pulse ultrasound and the measured temperature was in close agreement with the simulated tem-perature. Conclusions: This simulation model is con-sidered to be very useful tool for providing acoustic parameters (frequency, power, and duty factor) dur-ing the application of pulsed ultrasound at various depths in tissue so that a safe temperature is main-tained during the treatment. This model will be tested eventually during stroke clinical trials.
Calibration of GaAlAs Semiconductor Diode  [PDF]
S. B. Ota, Smita Ota
Journal of Modern Physics (JMP) , 2012, DOI: 10.4236/jmp.2012.310184
Abstract: The forward voltage of GaAlAs semiconductor diode has been measured in the temperature range 50 K - 300 K and for current values between 10 nA and 450 μA. The forward voltage as a function of temperature is least-squares fitted and the coefficients are given. The 1st and 2nd order least-squares fitting has high temperature root between 400 K and 950 K. The presence of the high temperature root indicates that the fitted polynomials are of similar character. The high temperature root is found to increase for the least squares fitted polynomials corresponding to higher current values.
Maintaining Neonatal Normothermia during WHO Rec-ommended Skin-to-Skin Contact in the Setting of Cesarean Section under Regional Anesthesia  [PDF]
Silvia Stirparo,Alessio Farcomeni,Alessandro Laudani,Giorgio Capogna
Open Journal of Anesthesiology (OJAnes) , 2013, DOI: 10.4236/ojanes.2013.33043
Abstract: This study compared mothers’ and newborns’ temperatures (T) when the WHO recommended skin-to-skin contact (SSC) was practiced during cesarean section under regional anesthesia. 139 neonates were randomized to be left in their mothers’ arms warmed by a forced air warmer (SSC-FAW) or put in an incubator. Maternal and newborn rectal T was recorded immediately after birth, at 5, 10 and 15 minute intervals. Maternal and neonatal T was comparable between the groups. FAW is as effective as an incubator in preventing neonatal hypothermia while the mother is undergoing surgery in the operating room, while favouring SSC.
A Late 20th Century European Climate Shift: Fingerprint of Regional Brightening?  [PDF]
A. T. J. de Laat, M. Crok
Atmospheric and Climate Sciences (ACS) , 2013, DOI: 10.4236/acs.2013.33031
Abstract:

We investigate the spatial extent of a statistically highly significant shift in atmospheric temperatures over Europe around 1987-1988 using a boot-strap change point algorithm. According to this algorithm, this change point (average warming of about one degree Celsius) is statistically highly significant (p > 99.9999%). The change point is consistently present in satellite and surface temperature measurements as well as temperature re-analyses and ocean heat content over most of Western Europe. We also find a connection with parts of the North Atlantic Ocean and eastern Asia. Although the time of change coincides with the North Atlantic Oscillation (NAO) going from negative to positive, the consistent warmer temperatures throughout the decades after 1987-1988 does not coincide with a persistent shift of the NAO, as it returns to a neutral/negative in the 1990’s. Furthermore, the shift does not coincide with any other known mode of multidecadal internal climate variability. We argue that the notion of a shift is “spurious”, i.e. the result of a fast change in Europe from dimming to brightening combined with an accidental sequence of cold (negative NAO) and warm (positive) NAO years during this period. The “shift” could therefore be considered as a fingerprint of European brightening during the last few decades.

Intraoperative Rise of Surface Temperature Monitors Success of Sympathectomy in Palmoaxillary Hyperhidrosis  [PDF]
Sebastian Kr?mer, Axel Skuballa, Uwe Eichfeld
Open Journal of Thoracic Surgery (OJTS) , 2013, DOI: 10.4236/ojts.2013.31003
Abstract:

Objectives: Patients with hyperhidrosis suffer from an extreme perspiration that cannot be aligned with natural or situational standards. Endoscopic sympathectomy is a meaningful option for palmar and axillary hyperhidrosis. A standardized method of monitoring the immediate intraoperative success has not been established yet. The presented investigation shows one proposed sollution by monitoring skin surface temperature. The main aspect is to demonstrate a significant rise in temperature with utility for monitoring the immediate success of surgery. Methods: Twenty patients with primary hyperhidrosis were observed and treated in a standardized setting against a control group (n = 10). We obtained diverse data that permit determination of a point of time of measurement of surface temperature and definition of a degree of temperature variance. Results: After 5 minutes a significant change of 0.5? Celcius was noted on the palms; after 10 minutes on average 1.2? Celcius. Axillary temperature had significantly changed after 10 minutes with a mean temperature variation of 0.8? Celcius on the right side and 0.6? Celcius on the left side. Conclusions: Under consideration of appropriate time intervals of measurement and determined changes in surface temperature an early control of correct clip application in ETS is possible. In the palmar aspect an increase of 0.5? Celcius at an 5 minutes interval, and more than 1

Maintaining Neonatal Normothermia during WHO Rec-ommended Skin-to-Skin Contact in the Setting of Cesarean Section under Regional Anesthesia  [PDF]
Silvia Stirparo, Alessio Farcomeni, Alessandro Laudani, Giorgio Capogna
Open Journal of Anesthesiology (OJAnes) , 2013, DOI: 10.4236/ojanes.2013.33043
Abstract:

This study compared mothers’ and newborns’ temperatures (T) when the WHO recommended skin-to-skin contact (SSC) was practiced during cesarean section under regional anesthesia. 139 neonates were randomized to be left in their mothers’ arms warmed by a forced air warmer (SSC-FAW) or put in an incubator. Maternal and newborn rectal T was recorded immediately after birth, at 5, 10 and 15 minute intervals. Maternal and neonatal T was comparable between the groups. FAW is as effective as an incubator in preventing neonatal hypothermia while the mother is undergoing surgery in the operating room, while favouring SSC.

Air-Ground Temperature Coupling: Analysis by Means of Thermal Orbits  [PDF]
Vladimir Cermak, Louise Bodri
Atmospheric and Climate Sciences (ACS) , 2016, DOI: 10.4236/acs.2016.61009
Abstract: Long-term measurements of air, near-surface (soil) and ground temperatures that were collected between 1994 and 2013 at the drill site of the Geothermal Climate Change Observatory (Prague) were analyzed to understand the relationship between these variables and to reveal the mechanisms of heat transport at the land-atmosphere boundary layer. The 2D Thermal Orbit (TO) method was applied to detect regularities that were hidden in noisy and highly variable temperature time series. The results showed that the temperatures at shallow depths were affected by surface air temperature (SAT) variations on seasonal and annual time scales and could be regarded as an accurate proxy for low frequency temperature variations at the Earth’s surface. Only low-frequency/ high-amplitude surface temperature variations penetrate into the subsurface because of strong damping and the filtering effect of the ground surface. The borehole temperatures have good potential to capture temperature variations (periodicities) over long time scales that cannot be detected in the SAT series themselves because of the interference of higher frequency noise. The TO technique is a useful and powerful tool to quickly obtain diagnostics of the presence of long periodicities in borehole temperature time series.
Effect of Oxalate Precursor Formation Temperature on Magnetic Properties of Nicuzn Ferrites  [PDF]
Neelam S. Shinde, Sujata S. Khot, Bhimrao P. Ladgaonkar, Bharat B. Kale, Sanjay Apte, Prasad M. Tamhankar, Shrikant C. Watawe
Materials Sciences and Applications (MSA) , 2011, DOI: 10.4236/msa.2011.28148
Abstract: Ni-Cu-Zn ferrites with general formula Ni0.5Zn0.5-x/2Cux/2Fe2O4 (with x = 0.3, 0.4, 0.5 and 0.6) have been synthesized using oxalate precursor method with different precursor reaction temperatures in the range 10℃ to 70℃. The Curie temperatures obtained using AC susceptibility measurements are found to be in the range 150℃ to 350℃, the measurements also show single domain structure for all the samples except few compositions obtained at 35℃ precursor reaction temperature, show a multi-domain behaviour. The saturation magnetization is found to be in the range 20 to 51 emu/gm, while the magnetic moment is found to be in the range 0.63 to 1.5 µB. The hysteresis losses were found to be maximum for the samples obtained at precursor reaction temperature of 35℃. The grain size is found to be in the range 0.4 to 2.0 µm.
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