The thermal impact of tourism on a Svalbard glacier cave (Short Communication)

Glacier cave visits are an important tourism activity on Svalbard with increasing popularity. This study investigates the thermal effect of touristic visits on the air temperature of a glacier cave on Longyearbreen, a small high-Arctic glacier. Short-term temperature perturbations of up to 1.59°C (42% local temperature increase) can be linked to human visitors. It is, however, unlikely that the local heat input from touristic visits is high enough to cause a lasting effect on the thermal regime of glacier caves and the surrounding ice.

Modelling and simulations for signal loss evaluation during sampling phase for thermoluminescence authenticity tests

<p class="Abstract"><span lang="EN-GB">In authenticity tests using the thermoluminescence (TL) method, the sampling phase is fundamental to collecting an appropriate amount of powder for analysis. The powder is usually obtained by drilling in hidden and pertinently selected areas of an artefact. During the drilling, a local temperature increase can occur, and, because thermoluminescence emission is dependent on the heating rate, the authenticity test result could be invalidated due to underestimation of the signal intensity. In this work, the percentage of signal intensity loss is investigated through the combination of a dynamic electro-mechanical model and a typical TL glow curve simulation. After first modelling the drilling procedure to estimate the maximum temperature reached, the optimal parameters that should be used during the sampling phase are checked by simulations together with an evaluation of the correlated signal losses.</span></p>

On the specification of the chronostratigraphic scheme of the Buzko-Rosynskyi block of the Ukrainian Shield

In the current correlation chronostratigraphic scheme of early Precambrian of the Ukrainian Shield, among Neoarchean supra crystalline formations of the Buzko-Rosynskyi block, it is identified the Rosynsko-Tikytska series, which consist of the Myzynivska and Lysianska strata and the independent Volodarsko-Bilotserkivska strata, which are located on the same stratigraphic level in the scheme. According to the results of the mapping of metamorphic formations within this block during the geological survey of scale 1:200 000 (articles “Bila Tserkva”, “Uman”, “Lyubashivka”, “Kotovsk”, “Haisyn”, “Skvyra”) it is established these stratas are located in the section in a following order: the lower one is the Myzynivska, the middle one is the Volodarsko-Bilotserkivska and the upper one is the Lysianska and they form a single Rosynsko-Tikytska series. Also, these works did not confirm the presence in the region of the Bilotserkivska group of magnetic anomalies of two-pyroxene schale among the rocks of the Volodarsko-Bilotserkivska strata. This is a sign of their higher metamorphism degree. The hypersthene is present in the area of the Volodarka then only in high-iron rocks. Its presence is associated with a local temperature increase during metamorphism due to the high oxidative ability of iron. This indicates the possibility of its crystallization under conditions of amphibolite facies. A powerful argument in favor of this is the occurrence of a relatively thin carbonate-ferruginous-siliceous strata among thick amphibolite-gneiss and crystalline-schist-amphibolite strata which metamorphosed under amphibolite facies conditions. It indicates the low probability that the metamorphism of the iron ore could occur locally in other conditions. The obtained new data on the composition of the Rosynsko-Tikytska series and the actual stratigraphic sequence of stratas in it, indicates the necessity of making appropriate changes in the current correlation chronostratigraphic scheme of early Precambrian formations of the Ukrainian Shield.

Self-Heating Effects in SiGe Heterojunction Bipolar Transistor with Different Ge Grading Profile

A comparative account of self heating effect of four SiGe HBTs with different Ge grading profiles, designated as Hybrid Trapezoidal (HT), Symmetrically Triangular (ST), Linear Increasing (LI), and Conventional Trapezoidal (CT) with maximum Ge contents of 20%, is presented. Based on an experimentally validated model of the Silvaco TCAD tool, the properties of the four HBTs are simulated. It is observed that both self heating and local temperature increase due to higher device power dissipation. The effect of energy balance and non iso thermal energy balance effect is observed in SiGe HBT with different Ge base profile have been studied in terms of DC, AC, and RF performances and compared .

Climate model shows large-scale wind and solar farms in the Sahara increase rain and vegetation

Wind and solar farms offer a major pathway to clean, renewable energies. However, these farms would significantly change land surface properties, and, if sufficiently large, the farms may lead to unintended climate consequences. In this study, we used a climate model with dynamic vegetation to show that large-scale installations of wind and solar farms covering the Sahara lead to a local temperature increase and more than a twofold precipitation increase, especially in the Sahel, through increased surface friction and reduced albedo. The resulting increase in vegetation further enhances precipitation, creating a positive albedo–precipitation–vegetation feedback that contributes ~80% of the precipitation increase for wind farms. This local enhancement is scale dependent and is particular to the Sahara, with small impacts in other deserts.

Effect of plasma-β on the onset of plasmoid instability in Sweet–Parker current sheets

A numerical study of magnetic reconnection in two-dimensional resistive magnetohydrodynamics for Sweet–Parker current sheets that are subject to plasmoid instability is carried out. The effect of the initial upstream plasma-β on the critical Lundquist number Sc for the onset of plasmoid instability is studied. Our results indicate a weak dependence, with a value of Sc ≃ 1.5 × 104 in the limit of zero β, and a value of Sc ≃ 1 × 104 in the opposite high β regime (β ≫ 1). A similar dependence was previously obtained (Ni et al. 2012 Phys. Plasm. 19, 072902), but with a somewhat much larger variation, that can be largely attributed to the different configuration setup used in their study, and also to the definition of the Lundquist number. This conclusion does not depend significantly on the equilibrium used, i.e. both initial configurations with either plasma density or temperature spatial variations lead to very similar results. Finally, we show that the inner plasmoid structure appears as an under-dense hotted magnetic island, with a local temperature increase that is noticeably strengthened for low β cases.

Application of Temperature-Dependent Fluorescent Dyes to the Measurement of Millimeter Wave Absorption in Water Applied to Biomedical Experiments

Temperature sensitivity of the fluorescence intensity of the organic dyes solutions was used for noncontact measurement of the electromagnetic millimeter wave absorption in water. By using two different dyes with opposite temperature effects, local temperature increase in the capillary that is placed inside a rectangular waveguide in which millimeter waves propagate was defined. The application of this noncontact temperature sensing is a simple and novel method to detect temperature change in small biological objects.