Maximum Temperature Reduction Research Articles

Aspirin Compared with Acetaminophen in the Treatment of Feverand OtherSymptoms of Upper Respiratory Tract Infection in Adults: A Multicenter, Randomized, Double-Blind, Double-Dummy, Placebo-Controlled, Parallel-Group, Single-Dose, 6-Hour Dose-Ranging Study

Aspirin (acetylsalicylic acid) and acetaminophen (paracetamol) are frequently used to treat fever and other symptoms of upper respiratory tract infection (URTI). Both are available over the counter for use at the standard recommended doses of 500 and 1000 mg per single use. This study investigated the efficacy, safety profiles, and tolerability of aspirin 500 and 1000 mg and acetaminophen 500 and 1000 mg compared with placebo in adult patients with acute febrile URTI of suspected viral origin. This was a multicenter, randomized, double-blind, double-dummy, placebo-controlled, parallel-group trial conducted in Ukraine and Russia. Patients with URTI and acute fever of > or =38.5 degrees C received a single dose of aspirin 500 or 1000 mg, acetaminophen 500 or 1000 mg, or matching placebo. Oral body temperature was measured in the clinic at specified time points up to 6 hours after dosing. The intensity of other symptoms of URTI was rated by patients at baseline and at 2, 4, and 6 hours after dosing (scale from 0 = none to 10 = severe). The primary efficacy measure was the AUC for the change in orally measured body temperature from the time of treatment (baseline) to 4 hours after dosing. Secondary outcome measures included the change in body temperature from baseline to specified time points between 0.5 and 6 hours after dosing, the difference between baseline and the lowest measured body temperature, the time to the lowest measured body temperature, and the intensity of other symptoms of URTI (ie, headache, sinus sensitivity to percussion, sore throat, achiness, and feverish discomfort). Tolerability was monitored by recording of adverse events. Three hundred ninety-two patients were enrolled (78 in both aspirin groups, 79 in both acetaminophen groups, 78 in the placebo group). Demographic and baseline characteristics were comparable in the 5 groups; 51% of patients were male, with a mean age of 37.4 years and a mean body weight of 74.3 kg. The AUC values for the change in body temperature 0 to 4 hours after dosing were 3.18 (95% CI, 2.78-3.57) for aspirin 500 mg, 4.26 (95% CI, 3.84-4.68) for aspirin 1000 mg, 3.13 (95% CI, 2.77-3.49) for acetaminophen 500 mg, 4.11 (95% CI, 3.73-4.49) for acetaminophen 1000 mg, and 0.76 (95% CI, 0.38-1.13) for placebo. In terms of the primary efficacy variable, all active treatments were significantly superior to placebo (P < 0.001, 1-sided t test), with no significant differences between them. Reductions in body temperature were significantly greater with the 1000-mg doses of both active treatments compared with the 500-mg doses (P< 0.001, 1-sided t test). The mean maximum temperature reductions were 1.32 degrees C, 1.25 degrees C, 1.67 degrees C,1.71 degrees C, and 0.63 degrees C in the respective treatment groups. Significant reductions were seen in the mean intensity of headache, achiness, and feverish discomfort with all active treatments at most time points (P < 0.001), but not in sinus sensitivity to percussion or sore throat. All treatments were equally well tolerated, and no clinically significant adverse events occurred. In this single-dose study, aspirin 500 and 1000 mg and acetaminophen 500 and 1000 mg were more effective against fever and other symptoms of URTI than placebo. Both active treatments showed dose-related efficacy, and there was no significant difference between equal doses of the 2 agents. Safety profiles and tolerability were also comparable between treatments.

Effect of exfoliation on poly(styrene‐co‐acrylonitrile)/montmorillonite nanocomposite flammability

AbstractMontmorillonite clays (MMT) have shown potential as non‐halogenated fire retardants in polymer blends, but the effect of morphology of the resulting nanocomposite is not well understood. In this article MMT blends are studied in a styrene‐acrylonitrile copolymer (SAN) matrix to get structure–property relationships relating to the more complex problem of flame retardancy (FR) of acrylonitrile‐butadiene‐styrene copolymer (ABS) computer housings. The morphology observed in SAN/MMT blends using twin screw extrusion was complex, and was affected by the compatibilizing amine head group substituent size, the amine tail group length, and the amine exchange ratio. However, the morphology did not affect flammability properties significantly. The most important determinant of FR properties was clay loading. Peak heat release rate was reduced up to 49% at a loading of about 12% organoclay, using a 2‐ethylhexyl dimethyl hydrogenated tallow ammonium surfactant. Backside temperatures were measured during FR tests, and significant reductions in maximum heat soak temperature and time to reach heat soak temperature were noted as exfoliation increased, supporting the theory that the clays have an insulative effect. Copyright © 2005 John Wiley &amp; Sons, Ltd.

Comment on “Climate forcing by the volcanic eruption of Mount Pinatubo” by David H. Douglass and Robert S. Knox

Comment on “Climate forcing by the volcanic eruption of Mount Pinatubo” by David H. Douglass and Robert S. Knox

Simulating the Holocene climate evolution at northern high latitudes using a coupled atmosphere-sea ice-ocean-vegetation model

The response of the climate at high northern latitudes to slowly changing external forcings was studied in a 9,000-year long simulation with the coupled atmosphere-sea ice-ocean-vegetation model ECBilt-CLIO-VECODE. Only long-term changes in insolation and atmospheric CO2 and CH4 content were prescribed. The experiment reveals an early optimum (9-8 kyr BP) in most regions, followed by a 1-3degreesC decrease in mean annual temperatures, a reduction in summer precipitation and an expansion of sea-ice cover. These results are in general agreement with proxy data. Over the continents, the timing of the largest temperature response in summer coincides with the maximum insolation difference, while over the oceans, the maximum response is delayed by a few months due to the thermal inertia of the oceans, placing the strongest cooling in the winter half year. Sea ice is involved in two positive feedbacks (ice-albedo and sea-ice insulation) that lead regionally to an amplification of the thermal response in our model (7degreesC cooling in Canadian Arctic). In some areas, the tundra-taiga feedback results in intensified cooling during summer, most notably in northern North America. The simulated sea-ice expansion leads in the Nordic Seas to less deep convection and local weakening of the overturning circulation, producing a maximum winter temperature reduction of 7degreesC. The enhanced interaction between sea ice and deep convection is accompanied by increasing interannual variability, including two marked decadal-scale cooling events. Deep convection intensifies in the Labrador Sea, keeping the overall strength of the thermohaline circulation stable throughout the experiment.

Evaluation of chemical effects of added CO2 according flame location

A numerical study has been conducted to clearly grasp the impact of chemical effects caused by added CO2 and of flame location on flame structure and NO emission behaviour. Flame location affects the major source reaction of CO formation, CO2+H→CO+OH and the H-removal reaction, CH4+H→CH3+H2. It is, as a result, seen that the reduction of maximum flame temperature due to chemical effects for fuel-side dilution is mainly caused by the competition of the principal chain branching reaction with the reaction, CH4+H→CH3+H2, while that for fuel-side dilution is attributed to the competition of the principal chain branching reaction with the reaction, CO2+H→CO+OH. The importance of the NNH mechanism for NO production, where the reaction pathway is NNH→NH→HNO, is recognized. In C-related reactions most of NO is the direct outcome of (R171) and the contribution of (R171) becomes more and more important with increasing amount of added CO2 as much as the reaction step (R171) competes with the key reaction of thermal mechanism, (R237), for N atom. This indicates a possibility that NO emission in hydrogen flames diluted with CO2 shows less dependent behaviour upon flame temperature. Copyright © 2004 John Wiley & Sons, Ltd.

A simplified model for the effect of interfinger metal on maximum temperature rise in a multifinger bipolar transistor

The prediction of a simple lumped representation of heat sharing through emitter interconnect in high-power multiemitter bipolar devices is compared to numerical thermal simulation and found to exhibit nonphysical results. Using numerical simulation, interfinger metal heat flow is characterized qualitatively in three dimensions and the requirements for a more accurate model are determined. A new modeling approach based on these insights, using segmented emitters and a coarse representation of the metal structure, yields results within 2% of those obtained from numerical thermal simulation for a wide variety of device geometries and substrate materials, with a simulation time reduction of more than an order of magnitude. Using the new model, an extensive series of simulations is performed for devices fabricated in Si, GaAs, and InP substrates using Al and Au for metallization. Reduction in maximum temperature due to the presence of emitter interconnect in these structures is found to be in the range of 5%-15%.

Heat Transfer on the Surface on a Spherically Blunted Cone Exposed to a Supersonic Spatial Flow with Injection of a Coolant Gas

The heat‐transfer processes in a supersonic spatial flow around a spherically blunted cone with allowance for heat overflow along the longitudinal and circumferential coordinates and injection of a coolant gas are studied numerically. The prospects of using highly heat‐conducting materials and injection of a coolant gas for reduction of the maximum temperatures at the body surface are demonstrated. The solutions of the direct and inverse problems in one‐, two‐, and three‐dimensional formulations for different shell materials are compared. The error of the thin‐wall method in determining the heat flux on the heat‐loaded boundary of the body is estimated.

Observational Evidence for Reduction of Daily Maximum Temperature by Croplands in the Midwest United States

Climate model simulations have shown that conversion of natural forest vegetation to croplands in the United States cooled climate. The cooling was greater for daily maximum temperature than for daily minimum temperature, resulting in a reduced diurnal temperature range. This paper presents analyses of observed daily maximum and minimum temperatures that are consistent with the climate simulations. Daily maximum temperature in the croplands of the Midwest United States is reduced relative to forested land in the Northeast, resulting in a decreased diurnal temperature range. The cooling is regional rather than local and is likely created by the contrast between extensive cropland in the Midwest and forest in the Northeast. Seasonal patterns of this cooling are correlated with seasonal changes in crop growth. Analyses of historical temperatures since 1900 and reconstructed cropland extent show a temporal correlation between land use and cooling. The cooling created by the forest–cropland contrast is much more prominent now, when much of the Northeast farmland has been abandoned and reforested, than in the early 1900s when farmlands were more extensive in the Northeast. These results show that human uses of land, especially clearing of forest for agriculture and reforestation of abandoned farmland, are an important cause of regional climate change. Analyses of historical temperature records must consider this “land use” forcing.

An Experimental Investigation of the Effect of Groove Location and Supply Pressure on the THD Performance of a Steadily Loaded Journal Bearing

This paper aims to present the results of parametric experiments carried out in order to study the influence of groove location and supply pressure on the performance of a steadily loaded journal bearing with a single-axial groove. Hydrodynamic pressure and temperature distributions on the bush surface, shaft temperature, flow rate and bush torque were measured at variable supply pressure, using bushes with a single groove located at three different positions. A series of tests were carried out for variable applied load and rotational speed. The experimental evidence shows that some bearing characteristics are significantly sensitive to changes in groove location and supply pressure. One groove located at 30 degrees in relation to the load line, in the direction of shaft rotation, can conduct to reductions in maximum temperature, maximum hydrodynamic pressure and bush torque, with a moderate increase in oil flow rate. [S0742-4787(00)02801-0]

Evaluating strategies for overcoming overheating problems during solid-state fermentation in packed bed bioreactors

Normal operation of packed bed bioreactors used for solid-state fermentation involves a static bed aerated from the bottom throughout the fermentation. This leads to axial temperature profiles with the highest temperature, sometimes over 20°C higher than the inlet air temperature, occurring at the top of the bed. An axial heat transfer model was used to explore two strategies designed to prevent the temperature reaching undesirable levels, namely periodic reversal of the direction of airflow, and periodic mixing. Simulations were done for the growth of Aspergillus niger on a starchy substrate. The bed was assumed to be wide enough such that the radial heat transfer could be ignored. With hourly air reversal or mixing events, the maximum temperature predicted during the fermentation is higher than the maximum temperature predicted for normal operation. Increasing the frequency of air reversals leads to temperatures close to the maximum for growth in the middle of the bed. However, for a 0.345 m high bed and a superficial air velocity of 0.0236 m s −1, mixing 10–60 times per hour can lead to lower maximum temperatures in the column compared to normal operation, because the frequent mixing distributes the benefits of the effective cooling at the bottom of the column throughout the bed. The degree of reduction in maximum temperature increases with increasing specific growth rate of the microorganism. Modelling is a useful tool in guiding experimental programs for the design and scale-up of bioreactors for solid-state fermentation, since it can be used to identify promising strategies and eliminate unfruitful strategies.

Conservation of soil moisture by different stone covers on alpine talus slopes (Lassen, California)

This study reports on the influence of stone covers with different clast sizes on the soil moisture of alpine talus slopes in Lassen (California). Fifteen four-plot sets were sampled in the dry season (July 1990) in sandy areas and in talus covered with pebbles, cobbles, or blocks between 2740 and 2775 m. Three depths (0–5, 5–10, 10–15 cm) were sampled. Field moisture content increased gradually with depth in all soil profiles, and also in plots covered by increasingly larger rocks. Surface soils in sand areas were very dry, but under rocks had water contents 6 to 14 times greater. Differences among plots decreased with depth, but subsoil samples in sand were still drier than those beneath any stone cover at similar depths. Blocks were most effective in conserving moisture; water content below them was higher than even in deep (10–15 cm) sand soils. Soil temperatures were recorded in sand and under blocks for an 11-day period. Minima were not significantly different, but average maxima were 5.6°C lower under blocks than in sand, which reached highs ∼4.4°C lower than the air. Differences in soil moisture among talus types are ascribed to lower evaporation losses under stones, due to both disruption of capillarity by the coarse particles, which prevented water flow to the talus surface, and to their efficient reduction of maximum temperatures. An irrigation experiment was conducted at 2110 m on a steep talus on the Chaos Crags from July 18 to Aug. 2, 1993. Four 100×75 cm plots with the same surface types than at Lassen received 22.5 mm water; moisture content was then periodically sampled. Watering produced similar water distributions among soil depths and talus types to those in Lassen. Evaporation occurred quickly in bare soils due to high air and soil temperatures. The sand surface was already dry 2 days after watering, but stone-covered plots remained moist until day 15, when soils under blocks still retained 77–97% of the water content (percent by weight) at the start of the test.

Heat Transfer Enhancement With Porous Inserts in Recirculating Flows

This investigation explores the use of porous inserts for heat transfer enhancement in recirculating flows, specifically flow over a backward-facing step. Numerical computations are performed for laminar flow with high porosity inserts, which are composed of small-diameter (150 μm) silicon carbide fibers aligned transverse to the streamwise flow. The inserts are varied in length and porosity in order to determine the most favorable combinations of maximum temperature reduction and head loss penalty. In general, the porous inserts reduce or eliminate the lower wall recirculation zone; however, in some cases the recirculation zone is lengthened if the inserts are short and extremely porous. Excellent heat transfer characteristics are shown within the inserts themselves due to the high-conductivity fiber material. Non-Darcy effects are shown to be important primarily as the porosity is increased. Deviation from local thermodynamic conditions between the inserts and the fluid is most apparent for the shortest inserts considered.

Aircraft contrails reduce solar irradiance

A topic of considerable interest today is whether condensation trails generated by the growing number of passenger and other jet aircraft (Figure 1) alter Earth's radiation balance enough to influence regional weather and global climate [e.g., Rind et al. , 1996].While any global influences of contrails have yet to be detected, a number of studies show possible regional effects. Changnon [1981], for example, suggested a possible link between contrails from jet aircraft and a reduction in the diurnal maximum and minimum temperature in the midwestern United States. Cirrus evolved from contrails has even been reported to reduce the warming of a solar‐heated house [Robinson, 1996].

THREE-DIMENSIONAL FLUID FLOW AND HEAT TRANSFER ANALYSIS OF GRATE BLOCKS IN A WASTE-TO-ENERGY POWER PLANT

The cause of high operating temperatures experienced by grate blocks in a waste-to-energy power plant is investigated. A three-dimensional numerical analysis is performed to assess convection from the grate to the underfire air supply and conduction within the grate. A number of geometric complexities, including variable solid thickness, extended surfaces, sharp curvatures, and narrow passages, are accounted for via a finite element approach. The grate temperature is found to be very sensitive to the flow characteristics beneath the grates. Analysis of a modified grate structure was performed, showing a 14% reduction in maximum grate temperature.

Forced convection air-cooling of a commercial electronic chassis: an experimental and computational case study

The present study examines the suitability of a combined experimental and computational methodology for system-level electronic packaging thermal design. A 48.3 cm (19 in), twenty-slot, fully populated commercial-off-the-shelf (COTS) electronic equipment chassis was studied experimentally and computationally. The experimental program involved detailed component surface temperature measurements for system power levels of 423 and 846 W (21 and 42 W/module) and for volumetric flow rates between 0.05 and 0.14 m/sup 3//s. The experimental configuration was also computationally simulated and the predicted component temperatures agreed well with the experiments. The effects of various baffle configuration designs within the inlet plenum were then computationally analyzed for improved thermal performance. The best configuration based on the model study was experimentally examined and provided maximum surface temperature reduction of 56%.

Natural convection liquid immersion cooling of a heat source flush mounted on a conducting substrate in a square enclosure

A numerical investigation of natural convection flow and heat transfer due to a rectangular heat source flush mounted on a substrate in a liquid-filled square enclosure was conducted. A finite volume model that accounts for the coupled conduction within the substrate and heat source and the natural convection in the liquid was utilized for a wide range of Rayleigh and Prandtl numbers. Little reduction in maximum temperatures was observed when substrate to fluid and component to fluid thermal conductivity ratios were increased beyond 10 and 25, respectively. Computed temperatures using the present model compared favorably with an existing experimental study.

Hot spot locations and temperature distributions in a forced convection photochemical reactor

We have computed steady axisymmetric temperature distributions in a tubular photoreactor in which fluid in laminar flow absorbs light from an azimuthally uniform, radially incident light source. In addition to the primary on-axis temperature maximum, a second hot spot forms off the centerline as the optical density γ increases. This results from a shift of light absorption toward the wall, which is held at a fixed temperature (e.g. by forced convection cooling on the outside). At still larger γ the centerline hot spot disappears, leading to a decrease in the maximum temperature and accompanied by an increase in the temperature near the wall. There is a critical value of γ, depending on the Peclet number Pe, below which the hot spot is located on the centerline and above which a second hot spot forms and moves off the centerline. The reduction in maximum centerline temperature may be advantageous for product selectivity and yield in the central core of the reactor, but may be disadvantageous with respect to the formation of light-absorbing deposits on the interior of the tube wall. Axial heat conduction has significant effects for Pe < 50, including displacement of the hot spot upstream from the exit plane of the illuminated section, as well as an increase in the maximum temperature.

Low-temperature (&lt;or=550 degrees C) fabrication of poly-Si thin-film transistors

High performance n- and p-channel thin-film transistors (TFTs) have been fabricated in polycrystalline silicon films using a self-aligned-gate process without exceeding 550 degrees C. This process features the use of polycrystalline Si/sub 0.5/Ge/sub 0.5/ for the gate material and high-dose H/sup +/ implantation for grain-boundary passivation so that shorter process times can be used. Low threshold voltages of 2.8 and -0.2 V, and high field-effect mobilities of 35 and 28 cm/sup 2//V-s, where achieved by the NMOS and PMOS devices, respectively. The performance of these devices is comparable to that of previously reported devices fabricated using process temperatures up to 600 degrees C, and is adequate for large-area-display peripheral driver circuits. The significant reduction in maximum process temperature makes this process advantageous for the fabrication of CMOS circuits on large-area glass substrates. >

Corticosteroid therapy in biliary atresia

Sixteen patients with biliary atresia had 44 steroid courses for treatment of cholangitis or diminution of bile flow following Kasai hepatic portoenterostomy operations. A "blast" type (high dose/short duration) steroid administration was employed to potentiate the choleretic and anti-inflammatory effect. There was a significant augmentation of bile flow and a reduction in maximum temperature, serum bilirubin, and alkaline phosphatase.

Effect of the fluctuations on the TLS parameters

The influence of the phonon fluctuations on the equilibrium parameters of the TLS potential curve is investigated. The distribution range of the transparency parameter of the TLS potential barriers is restricted. The effect of the phonon fluctuations results in a strong reduction of the second maximum temperature of the ultrasonic attenuation, which markedly improves the agreement between the theory and experiment.