Differences In Temperature Changes Research Articles

How reversible is sea ice loss?

Abstract. It is well accepted that increasing atmospheric CO2 results in global warming, leading to a decline in polar sea ice area. Here, the specific question of whether there is a tipping point in the sea ice cover is investigated. The global climate model HadCM3 is used to map the trajectory of sea ice area under idealised scenarios. The atmospheric CO2 is first ramped up to four times pre-industrial levels (4 × CO2), then ramped down to pre-industrial levels. We also examine the impact of stabilising climate at 4 × CO2 prior to ramping CO2 down to pre-industrial levels. Against global mean temperature, Arctic sea ice area is reversible, while the Antarctic sea ice shows some asymmetric behaviour – its rate of change slower, with falling temperatures, than its rate of change with rising temperatures. However, we show that the asymmetric behaviour is driven by hemispherical differences in temperature change between transient and stabilisation periods. We find no irreversible behaviour in the sea ice cover.

Efficacy of cervical fixed-point traction manipulation for cervical spondylotic radiculopathy: a randomizedcontrolled trial

Cervical spondylotic radiculopathy is a commonly encountered and frequently occurring disease. Traditional Chinese osteopathic manipulations may have better therapeutic efficacy than that of other methods in treating patients with cervical spondylotic radiculopathy. To evaluate the clinical therapeutic effects of cervical fixed-point traction manipulation in treating patients with cervical spondylotic radiculopathy. A prospective, randomized controlled trial was adopted. Eighty-four patients with cervical spondylotic radiculopathy were randomly divided into treatment group (n=42) and control group (n=42). All patients were enrolled from the outpatient service of Department of Rehabilitation of Chinese PLA General Hospital of China. Patients received oral and written information about clinical procedures before giving their written informed consent. The patients were treated with cervical fixed-point traction manipulation (treatment group) or cervical computer traction (control group). Cervical fixed-point traction was performed once every other day for a total of seven treatment periods and cervical computer traction was performed 30 min, once per day for 14 d. Before and after treatment, visual analogue scale (VAS) score and temperature of upper limb skin (normal limb and abnormal limb) detected by infrared thermal imaging system were contrastively analyzed. Five patients were lost to follow-up, one patient in the treatment group and four patients in the control group. There were significant differences in VAS score and temperature difference between the normal and abnormal upper limbs of infrared thermal imaging in the treatment group (t=28.652, P<0.01; t=64.214, P<0.01) or in the control group (t=14.484, P<0.05; t=84.425, P<0.05) compared between before and after treatment. After treatment, the changes in VAS score and temperature difference of normal and abnormal upper limbs in the treatment group were more obvious compared with the control group (t=7.494, P<0.01; t=5.321, P<0.01). Cervical fixed-point traction manipulation has better efficacy than cervical computer traction in treating patients with cervical spondylotic radiculopathy.

Stratospheric heating by potential geoengineering aerosols

[1] A fixed dynamical heating model is used to investigate the pattern of zonal-mean stratospheric temperature change resulting from geoengineering with aerosols composed of sulfate, titania, limestone and soot. Aerosol always heats the tropical lower stratosphere, but at the poles the response can be either heating, cooling, or neutral. The sign of the change in stratospheric Pole-Equator temperature difference depends on aerosol type, size and season. This has implications for modeling geoengineering impacts and the response of the stratospheric circulation.

Effect Analysis of Temperature in the Large Continuous Rigid Frame Bridge

Thermal stress is a factor of the large bridge structure cracks which can not be ignored. As a continuous rigid frame bridge in a certain period of Guangzhou ring express way the background, using the general finite element program MIDAS/Civil, only considering the load of temperature effect established the original bridge model, reference the China road and bridge design for temperature effect on the bridge numerical analysis. By section temperature difference and system temperature change getting the stress distribution and the stress distribution of section temperature difference and the system of heating section, cooling section and the system temperature gradient linear combinations ,the stress we got will get a large section of the stress to the actual distribution of bridge crack detection have a good agreement . Cooling load combination get the Maximum tensile stress at the bridge span beam bottom and the result exceeds the tensile strength of concrete, it gets most impact to the end of the beam cracks. On the bridge design to consider the temperature effect the conclusion has some certain reference value.

Study on the Realization of Zinc Point and the Zinc-Point Cell Comparison

Continuing our study on aluminum, tin, and silver points, a study on the realization of the zinc point was conducted. Zinc-point cells were newly fabricated using 6N-nominal grade zinc samples, impurity elements of which were analyzed extensively based on glow-discharge mass spectrometry (GDMS). The present paper reports the temperature measurements done using the newly fabricated cells during the zinc freezing process, under which the zinc fixed point is defined, and the analysis of the freezing curve obtained. Comparisons of zinc-point temperatures realized by the newly fabricated cells (cell-to-cell comparisons) were also conducted. Zinc-point depression due to impurity elements was calculated based on the sum of individual estimates and the impurity element analysis. One of the cells evaluated was drawn out from its crucible and analyzed by GDMS at four points, namely, at around the center of the top, of the middle, of the bottom, and around the outer part of the middle area. The purpose of this cell disassembly is to see whether or not there has been some difference before and after cell fabrication, as well as difference in impurity element distribution within the ingot. From the aforementioned studies, some findings were obtained. First finding is that the homogeneity of the zinc ingot was within 30%, except for Pb, which was more concentrated in the center part. Second finding is that the cell-to-cell temperature difference changes along with the progressing solidification process. As a consequence, for an accurate cell-to-cell comparison, the locus in the freezing plateau where the comparison is done should be determined. Third finding is that the slope analysis estimates accurately the cell-to-cell comparison, and is consistent with the impurity analysis. This shows that the slope analysis gives extensive information about the effect of impurity to the zinc-point realization, especially after the cell fabrication.

Mass Flux Through a Cell Filled with Solid 4He Induced by the Thermo-Mechanical Effect

We have induced a mass flow through a sample cell filled with hcp solid 4He by the imposition of a temperature difference between two reservoirs filled with superfluid liquid helium connected to each other by porous Vycor glass rods in series with the bulk solid 4He. The Vycor rods allow us to perform this experiment at pressures greater than the bulk melting pressure. The imposition of a change in the temperature difference between the reservoirs results in a rate-limited flux that creates a change in the pressure difference. The equilibrium pressure and temperature differences are in accord with predictions based on the fountain effect.

Phonon Hall effect in four-terminal nano-junctions

Using an exact nonequilibrium Green's function formulation, the phonon Hall effect (PHE) for paramagnetic dielectrics is studied in a nanoscale four-terminal device setting. The temperature difference in the transverse direction of the heat current is calculated for two-dimensional models with the magnetic field perpendicular to the plane. We find that there is a PHE in nanoscale paramagnetic dielectrics, the magnitude of which is comparable to millimeter scale experiments. If the dynamic matrix of the system satisfies mirror reflection symmetry, the PHE disappears. The Hall temperature difference changes sign if the magnetic field is sufficiently large or if the size increases.

마이크로파를 이용한 고 효율 해동 시스템 개발

본 연구에서 개발된 해동 시스템은 에너지 절감 및 친환경 측면에서 위해 요소 중점 관리기준(HACCP)에 대응하기 위한 필수적인 기술이다. 개발된 해동 시스템으로 냉동 돈육과 연육을 실험하였다. 실험 결과 냉동 연육보다 냉동돈육이 해동되지 않는 부위가 많이 발생하였다. 이와 같은 현상은 냉동 연육의 경우 갈아 있어서 부피와 밀도가 균일하게 형성 되었지만, 돈육은 밀도가 조밀하여 온도 차이 변화가 큰 것으로 사료되었다. 또한 해동 후 측정 위치 중심부에서 온도가 대체적으로 낮은 것으로 나타났다. 이것은 냉동 부위의 중심부분이 임피던스 변화가 적어 나타난 현상으로 사료되었다. 향후에는 임피던스 변화를 위해 해동 시스템의 구조를 변경할 필요가 있는 것으로 판단되었다.

Annual temperature history in Southwest Tibet during the last 400 years recorded by tree rings

AbstractWe present a tree ring‐width record from the southern Tibetan Plateau (TP) which spans from 1612–1998 AD (387 years). The series was developed from Tibetan juniper (Juniperus tibetica Kom) growing at sites near the western distribution limit of the species. Two versions of the chronology, a traditionally standardized chronology (TSC) and a regional curve standardization (RCS)chronology were developed. Linear regression models between ring width and mean annual temperature account for 41% (TSC) and 43% (RCS) of the annual (July–June) temperature variance for the period 1957–1998. According to the TSC reconstruction, warm periods occurred during the 1620s, 1650–1675, 1720s, 1740–1790, 1810s, 1850s–1890s, 1935–1950, and 1957–1964 and since 1980. Cold conditions prevailed during the 1630s–1640s, 1680s–1710s, 1730s, 1820–1840s, 1900s–1920s and the 1970s. Within the last 400 years, the late‐20th century warming is distinctive but still within the range of natural climatic variability of this region. Comparison of our TSC reconstruction with proxy temperature records from other parts of the TP shows that the cold conditions during the 1730s, 1900s–1920s, and 1970s, and the warm periods during the 1770–1800, 1850s–1890s, 1935–1950, and 1957–1964 and since 1980 were synchronously occurring broad‐scale climate anomalies on the whole TP. Differences between the reconstructions are found during the 17th century and around 1760, which were probably caused by local differences in temperature change and different sensitivity in seasonality. The RCS series portrays low‐frequency variations such as warm periods during 1620–1640, 1650–1690, 1715–1790, and 1845–1875, and cold conditions during 1640–1650, 1690–1715, and 1875–1995. These long‐term trends need to be verified by developing other proxy records that target to capture low‐frequency signals in the future. Copyright © 2009 Royal Meteorological Society

C14 熱音響現象に関する数値解析(パルス管冷凍機,熱音響機器及び関連要素と応用システム(2))

Numerical simulation of heat and fluid flow has been performed to investigate the difference in temperature change by the difference in thermal condition of the regenerator of a thermoacoustic oscillator. Transient one-dimensional equations of continuity, momentum and energy were solved utilizing the TVD scheme. A simple physical model was used for the numerical simulation. In this study, the effect of thermal condition of the regenerator on gas temperature was made clear.

C07 振動流中の熱伝達率に関する数値解析(パルス管冷凍機,熱音響機器及び関連要素と応用システム(3))

Numerical simulation of heat and fluid flow has been performed to clarify the effect of heat transfer coefficient on temperature change in oscillatory flows. Transient one-dimensional equations of continuity, momentum and energy are solved utilizing a TVD scheme. A basic pulse tube refrigerator is selected as the physical model. In this paper, we investigate the behavior of temperature changes during a cycle under various conditions of heat transfer coefficient. As a result, it was found that there are differences in temperature change among various conditions.

Essential Features of a Handheld Infrared Thermometer Used to Guide the Treatment of Neuropathic Feet

A study was conducted to compare the accuracy, reliability, and essential features of nine commercially available handheld infrared thermometers used to manage the neuropathic foot. The thermometers were compared using two temperature-control sources simulating physiologic conditions found in a foot-care clinic. With each control source independently set, temperature difference ranges of 0 degrees, 2 degrees, 4 degrees, and 6 degrees C were randomly sampled and analyzed for each thermometer by two testers. The order of testing was randomly assigned for testers and instruments. There were differences in mean temperature change among thermometers (P<.001) and between testers (P=.0247). Differences in mean temperature change among instruments (<0.5 degrees C), although small, could affect interpretation of skin temperature if temperature comparisons are made using two different instruments. The difference in temperature change between testers (0.06 degrees C) was not large enough to affect decisions in clinical practice. Instrument response time, distance-to-spot ratio, sensor diameter, display resolution, emissivity, and cost were compared. The low-cost, general-use infrared thermometers used in this study showed good accuracy, reliability, and performance and are appropriate for use in a foot-care clinic.

Enamel surface evaluation after removal of orthodontic composite remnants by intraoral sandblasting: A 3-dimensional surface profilometry study

The purpose of this study was to determine the utility of sandblasting to remove composite remnants after orthodontic bracket debonding. The sample consisted of 20 human premolars extracted for orthodontic purposes. The buccal surface of each premolar was divided into 3 parts: the upper half (control surface group, CS), the lower half left (LS group), and the lower half right (SS group). A composite resin paste (volume, 5 x 3 x 1 mm3) was bonded onto the LS and SS surfaces. Then it was removed by using 1 of 2 methods: low-speed handpiece with tungsten carbide bur in the LS group and sandblasting in the SS group. Temperature change and removal time were recorded, and surface profiles were examined with 3-dimensional profilometry. An independent t test showed a statistically significant difference in temperature change between the LS and SS groups (P <.01). ANOVA showed no significant difference in surface profile between the LS and SS groups (P >.5). The results suggest that intraoral sandblasting might be an alternative to rotatory instruments for resin remnant removal after orthodontic bracket debonding.

Oscillatory thermocapillary flow in liquid bridges of high Prandtl number fluid with free surface heat gain

Oscillatory thermocapillary flow in liquid bridges of high Prandtl number fluid is studied. The effect of free surface heat transfer, especially heat gain, on the oscillation phenomenon is investigated experimentally and numerically. It is shown that the critical temperature difference (Δ T cr) changes substantially when the free surface heat transfer changes from loss to gain in the case of nearly straight liquid bridges. In contrast, Δ T cr is not affected by the free surface heat transfer with concave liquid bridges. The free surface heat transfer rate is computed numerically by simulating the interaction of the liquid and the surrounding air. The oscillatory flow is also investigated numerically by analyzing the liquid flow in three-dimensions for straight bridges. The computed results agree well with the experimental data. The simulation shows that the free surface heat gain enhances the surface flow and that the oscillatory flow is a result of interactions between the convection effect and buoyancy. The flow does not become oscillatory if there is no net heat gain at the free surface in the range of Marangoni number of the present work (⩽1.8 × 10 4), so the present cause of oscillations is different from that in the free surface heat loss case we investigated in the past.

An in vitro uterine perfusion model for investigating endometrial cryoablation

Study Objectives To build a simple in vitro uterine perfusion model for investigating the clinical effectiveness of endometrial ablation. Design Comparative laboratory and in vivo study (Canadian Task Force classification II-2). Setting University teaching hospital. Patients Women undergoing hysterectomy for menorrhagia with uteri of normal shape and size. Interventions A single 5-minute freeze, followed by an active thaw was applied to the endometrial cavity of uteri in vivo and in the in vitro perfusion model. Measurements and Main Results Endometrial/myometrial temperature change was measured continuously during the cryosurgical procedure. Depth of cell death was measured using nicotinamide adenine dinucleotide diaphorase enzyme assay. There was no significant difference in temperature change and depth of cell death in endometrial/myometrial tissue between in vivo and in vitro perfusion experiments. Conclusions The in vitro perfusion model described is a useful tool for investigating endometrial cryoablation and has potential for investigating and developing other intrauterine surgical modalities.

Correlates of thenar near-infrared spectroscopy-derived tissue O2 saturation after cardiac surgery

We studied the significance of near-infrared spectroscopy (NIRS), for measuring tissue oxygenation (S(t)O(2)) and perfusion adequacy, and thus for haemodynamic monitoring of patients after cardiac surgery. We compared NIRS-derived S(t)O(2) of the thenar muscle to haemodynamic variables, oxygenation indices, temperature, lactate levels and urinary output, in 23 patients in the course of time after cardiac surgery and admission into the intensive care unit. Clinical variables, global haemodynamics and NIRS% total haemoglobin (%HT) and S(t)O(2) in the thenar for up to 18-22 h after admission were measured. The S(t)O(2) declined concomitantly with a rise in the body-finger temperature difference. Cardiac output did not change but mean arterial pressure rose, concomitantly with tapering doses of nitroglycerine, indicative of an increase in vascular tone during recovery from surgery. From all variables, changes in body-finger temperature difference best correlated to changes in S(t)O(2) (r(s)=-0.48, P<0.001). As judged from clinical and haemodynamic correlates, thenar NIRS S(t)O(2) is a non-invasive measure of peripheral rather than global perfusion adequacy, after cardiac surgery. This may help to define the role of thenar NIRS monitoring after cardiac surgery in future studies.

Susceptibility of uterine myomas and endometrium to cryosurgery using a carbon dioxide cryosurgical probe in vitro

Study objective To determine the effect of a 9-mm diameter carbon dioxide cryoprobe, the Endocryo, on myomas and endometrial/myometrial tissue in vitro. Design Comparative laboratory study (Canadian Task Force classification II-2). Setting University laboratory. Patients Women with and without myomas, undergoing hysterectomy. Intervention A single 5-minute freeze followed by an active thaw was applied to uterine myomas and endometrial/myometrial tissue in vitro. Measurements and main results Endometrial/myometrial and uterine myoma temperature change was measured continuously during the cryosurgical procedure. Depth of cell death was measured using nicotinamide adenine dinucleotide diaphorase enzyme assay. There was no significant difference in temperature change and depth of cell death between myomas and endometrial/myometrial tissue in vitro. Conclusions The Endocryo produces the same cryosurgical effect on both uterine myomas and endometrial/myometrial tissue in vitro, an important principal for future development of a clinically effective cryosurgical device for the treatment of menorrhagia in the presence of submucous myomas.

Experimental Study of Effect of Rare Gas Admixture on Temperatures of Microwave-Excited Oxygen Discharge Plasma

We examined the effect of a rare gas admixture with oxygen discharge on the vibrational and rotational temperatures of the OH radical by optical emission spectroscopy (OES). We chose helium, neon, argon, krypton and xenon as admixture components with oxygen. We generated a microwave discharge oxygen plasma in a cylindrical quartz tube (26 mm i.d.) with a discharge pressure of about 1.0 Torr. The microwave frequency was 2.45 GHz and the output power was set at 600 W. To obtain the rotational temperature, we measured the band spectrum of the radiative transition A2Σ+→X2Πi of an OH radical. We compared the experimentally measured and calculated spectra to determine the actual vibrational and rotational temperatures of the generated plasma. When the mixture ratio was larger than about 80%, the vibrational and rotational temperatures markedly changed, with depended on the mixed rare gas species. The difference in temperature change is discussed from several physical viewpoints.

δ 18O record and temperature change over the past 100 years in ice cores on the Tibetan Plateau

The 213 m ice core from the Puruogangri Ice Field on the Tibetan Plateau facilitates the study of the regional temperature changes with its δ 18O record of the past 100 years. Here we combine information from this core with that from the Dasuopu ice core (from the southern Tibetan Plateau), the Guliya ice core (from the northwestern Plateau) and the Dunde ice core (from the north-eastern Plateau) to learn about the regional differences in temperature change across the Tibetan Plateau. The δ 18O changes vary with region on the Plateau, the variations being especially large between South and North and between East and West. Moreover, these four ice cores present increasing δ 18O trends, indicating warming on the Tibetan Plateau over the past 100 years. A comparative study of Northern Hemisphere (NH) temperature changes, the δ 18O-reflected temperature changes on the Plateau, and available meteorological records show consistent trends in overall warming during the past 100 years.

Stomatal conductance in a tropical xerophilous shrubland at a lava substratum.

Diurnal variation in leaf stomatal conductance (gs) of three xerophilous species (Buddleia cordata, Senecio praecox and Dodonaea viscosa) was measured over a 10-month period during the dry and wet seasons in a shrubland that is developing in a lava substratum in Mexico. Averaged stomatal conductances were 147 and 60.2 (B. cordata), 145 and 24.8 (D. viscosa) and 142.8 and 14.1 mmol m(-2) s(-1) (S. praecox) during the wet and dry season respectively. Leaf water potential (Psi) varied in a range of -0.6 to -1.2 (S. praecox), -0.6 to -1.8 (B. cordata) and -0.9 to -3.4 MPa (D. viscosa) during the same measurement periods. Stomata were more sensitive to changes in irradiance, air temperature and leaf-air vapour pressure difference in the rainy season than the dry season. Although stomatal responses to Psi were difficult to distinguish in any season (dry or rainy), data for the entire period of measurement showed a positive correlation, stomata tending to open as Psi increased, but there is strong evidence of isohydric behaviour in S. praecox and B. cordata. A multiplicative model relating gs to environmental variables and to Psi accounted for 79%-83% of the variation of gs in three sites (pooled data); however, the performance of the model was poorer (60%-76%) for individual species from other sites not included in the pooled data.