Ice Crust Research Articles

Method for detecting and quantitating capture of organic molecules in hypervelocity impacts

Enceladus is a prime candidate in the solar system for in-depth astrobiological studies searching for habitability and life because it has a liquid water ocean with significant organic content and ongoing cryovolcanic activity. The presence of ice plumes that jet up through fissures in the ice crust covering the sub-surface ocean, enables remote sampling and in-situ analysis via a fly-by mission. However, capture and transport of organic materials to organic analyzers presents distinctive challenges as it is unknown whether, and to what extent, organic molecules imbedded in ice particles can be captured and survive hypervelocity impacts. This manuscript provides a fluorescence microscopic method to parametrically determine the amount of an organic fluorescent tracer dye, Pacific Blue™ (PB) deposited on a metallic surface. This method can be used to measure the capture and survival outcomes of terrestrial hypervelocity impact experiments where an ice projectile labeled with Pacific Blue impacts a soft metal surface. This work is an important step in the advancement of instruments like the Enceladus Organic Analyzer for detecting biosignatures in an Enceladus plume fly-by mission.An apparatus consisting of a substrate humidification shroud coupled with an epifluorescence microscope with CCD detector is developed to measure the intensity of quantitatively deposited Pacific Blue droplets under controlled humidity.Calibration curves are produced that relate the integrated fluorescence intensity of humidified PB droplets on metal foils to the number of PB molecules deposited.To demonstrate the utility of this method, our calibrations are used to analyze and quantitate organic capture and survival (up to 11% capture efficiency) following ice particle impacts at a velocity of 1.7 km/s on an aluminum substrate.

Пропиточный состав для цементно-бетонного покрытия дорог для улучшения ледофобных свойств

The article proposes an impregnation composition for cement concrete roads used to improve the ice-phobic properties of the pavement. The composition is based on the keratin production technology. The distinctive component of the composition is the addition of water-soluble polymers. One of the study criteria was to evaluate the performance of the impregnation composition, its adhesion resistance to mechanical impact. Tests were conducted for large samples (surface area 1925 cm2) in laboratory conditions with the application of vibration and shock loads. The test results showed the effectiveness of the ice-resistant coating, as in all experiments the uncoated specimens showed greater resistance of the ice crust to mechanical stress.

ОБГРУНТУВАННЯ ШЛЯХІВ ПОДОЛАННЯ ЕВТРОФІКАЦІЇ ВОДОЙМ

Introduction. Increasingly, due to excessive growth of nutrients and decomposition of plants and animals in the reservoir, low turbulence, increased temperature, and due to this decrease in the solubility of oxygen in water, leads to eutrophication and as a consequence – “blooming” of the reservoir. It is the signal of trouble in a hydrosphere that needs immediate permission. Problem Statement. For today processes and conformities to law of growing speed of distribution of eutrophication of reservoirs, is studied not enough and there is not the only setting, the structural parameters of that will be able to provide optimal terms that will assist breeding of industrial fish, both in summer and in a winter period of year, and thus it is the issue of the day of present time. Purpose. Exposure on the basis of analysis of existing for today methods and facilities of prevention of excessive increase of reservoirs by cyanobacterias, to execute the review of methods airing of reservoir, that answer the requirements of seasonal temperature condition, the capable normalized necessary concentration of oxygen, as in a summer period of year so in winter. Id est creation of such terms an eutrophication will not develop at that. Materials and methods. Methods of analysis of literature sources, laboratory studies of the effect of nutrient concentration in water on the development of algae, microscopic control of the number of cyanobacteria in experimental vessels, chemical analysis of the presence of dissolved oxygen in water were used. Water samples from the Pokrovsk pond were selected as research material. Results. Excessive growth of cyanobacteria is observed at a water temperature of 15 ° C. And when exposed to elements such as nitrogen and phosphorus, the growth rate increases several times, as evidenced by a number of laboratory experiments. The results of the experiment showed that even a small concentration of fertilizers in the pond can lead to rapid flowering of algae, to a critical decrease in oxygen concentration, which in turn will lead to the death of fish and other aquatic organisms. The general analysis of modern methods and methods of combating eutrophication allowed us to identify their main advantages and defects. Different methods of preventing and combating eutrophication have their advantages, but they mainly have a unidirectional effect, low efficiency, some use toxic reagents that are unacceptable in fisheries. Conclusions. A review of recent studies on the occurrence of eutrophication of water bodies and as a result – harmful algal blooms, investigated the main environmental factors that mediate the expansion of cyanobacterial blooms. At present, there is no single way or means to combat eutrophication processes that can completely clean the reservoir, but their use in the complex can be effective. Of particular interest is the deep aeration, which can be used both in the warm season and in winter. Eutrophication today is mainly a consequence of human activity, and which requires mainly a comprehensive solution. It includes both preventive and regulatory methods. Promising is the use of aeration, the result of which is achieved in the fight against “blooming” of the reservoir by cyanobacteria, including those that produce toxins, both in the warm season and cold, preventing the formation of ice crusts. Keywords: cyanobacteria, algae, eutrophication, aeration, oxygen saturation, conditioning.

ЭКСПАНСИЯ АРКТОГЕННОГО ЭЛЕМЕНТА ФЛОРЫ В БОРЕАЛЬНУЮ ОБЛАСТЬ (НА ПРИМЕРЕ ОХОТИИ)

On the example of arctic and arctoalpine species of the sedge family (Cyperaceae Juss.), willow family (Salicaea Mirb.), saxifrage family (Saxifragaceae Juss.), buttercup family (Ranunculaceae Juss.) and rose family (Rosaceae Juss.) new points of their settlement in the subarctic mountain structures of Priokhotye are shown. The ecological adaptations of arctogenic element species to existence in mountainous conditions of low temperatures and high water content of habitats (nival lawns, the outskirts of ice crust fields, key bogs, etc.) are considered. This made it possible to clarify the main ways of arctic and arctic-alpine species dispersal in the subarctic mountain systems of the Boreal region.

СТРОЕНИЕ СНЕЖНОГО ПОКРОВА НА СЕВЕРО-ВОСТОКЕ МОСКОВСКОЙ ОБЛАСТИ

Snow stratigraphy can be considered as an integral characteristic of weather conditions of the corresponding winter season. The stratigraphic approach is convenient for a comparative analysis of the snow stratigraphy at different spatial-temporal scales, including the variability of the snow cover due to climate change. The snow stratigraphy can be sufficiently modeled on the basis of three meteorological characteristics: air temperature, wind speed and precipitation. Consequently, significant differences in the winter meteorological conditions should produce different stratigraphy.In the Moscow region winter temperatures are almost three degrees higher in the 21‑st century compared to the middle of the 20th century, though precipitation and wind speed are similar. Thus, changes in the snow stratigraphy can be expected. Comparative analysis of the results of stratigraphic studies carried out in the mid‑1950s to 1960s and 2010s indicates a slight decrease in the proportion of faceted crystal and depth hoar layers and increase in melt-freeze layers during the last decade, while the proportion of settled layers composed by rounded grains remains relatively invariable. However, the interannual variability of the winter weather produces higher variability in the snow structure compared to the expected effect of the long-term climate trends. The spatial distribution of the melt-freeze layers in the 2014–2019 was different compared to 1957/58 and 1961/62 due to the increase in the number and intensity of thaws in the winter seasons. In the 2010s, the number and thickness of ice crusts and melt-freeze layers increased in the middle part of the strata, which usually forms in January–February. Such layers composed 5 to 31% (17% in average) in 2014–2019 winters, while in 1957/58 and 1961/62 it was 7 and 10% respectively. A further increase in winter temperatures can enhance changes in snow stratigraphy and properties. It may result in thicker melt-freeze layers, weaker kinetic growth and shorter winter seasons.

АДАПТИВНІ ВЛАСТИВОСТІ СОРТУ ЯК ФАКТОР ПІДВИЩЕННЯ ВАЛОВОГО ЗБОРУ ЗЕРНА ПШЕНИЦІ ОЗИМОЇ

It is proved that one of the main reasons for the winter wheat yield decrease is damage of plants in the autumn-winter season by low temperatures in the absence of snow cover and the harmful effects of ground ice crust, which is formed due an alternation between long-term thaws and frosts. It was found that according to adaptability indicators the best for cultivation in the Steppe zone are Smuglianka, Lymarivna, Oriika, Mudrist odeska, Askaniiska varieties of winter wheat. All of them are char-acterized by the sufficient winter hardiness, frost and drought resistance. Over the years of research, the av-erage yield of these varieties was: Smuglianka – 5.31 t/ha, Lymarivna – 6.04 t/ha, Oriika – 6.08 t/ha, Mudrist odeska – 5.84 t/ha, Askaniiska – 6.90 t/ha. Studies was established that for cultivation in arid conditions of the Steppe zone considering the adap-tive and plastic properties of winter wheat, the best varieties were such as: Bohynia, Oleksiivka, Donetska 48, Smuglianka, Epokha Odeska, Kiriia, Zolotokolosa, Blahodarka Odeska, Boghdana, List 25, Rozkishna. It is determined that an important element of agricultural technology improvement for winter wheat cultivation in the eastern part of the Northern Steppe of Ukraine is the genetic potential consideration of modern varieties, namely adaptive properties to increasing of yield by 11–50 % and raise of gross grain har-vest. In particular, plastic varieties of winter wheat are characterized by the formation of consistently high yields in different weather conditions. It is established that the winter wheat varieties of Ukrainian selection and including of different groups of maturity are advisably to grow in a Steppe zone. The share of cultivation areas under early and medium-late varieties should be 10–15 %, and medium-early and medium-ripe – 30–45 %. Key words: variety, yield, weather conditions, productivity, winter hardiness, varietal characteristic.

Study of hydrological changes in the middle section of the Bazavluk river under the influence of natural and anthropogenic factors

This article is devoted to the study of one of the most significant problems of hydro-ecology, pollution of rivers and other water bodies through natural and anthropogenic factors. Without solving this problem, it will be extremely difficult to provide the population with safe drinking water, to allow the normal development and habitation of fish and other aquatic organisms in water bodies, and to protect the environment and its integrity. During our study of the Bazavluk River, a hydrological study was carried out, physical and geographical indicators were measured and studied, conclusions were drawn, and methodological recommendations were developed for the preservation and restoration of the Bazavluk River, which is necessary for economic water supply, fisheries, and irrigation. The reservoir has a length of 157 kilometers, and the area of ​​the basin is 4,200 km2. The river valley has a trapezoidal shape up to 2 kilometers wide. The river is winding; the lower part the left bank is sloping in contrast to the right, which is steep along the entire length of the reservoir. The width ranges from 8 to 10 meters, and the average depth is 1.5 meters. The slope of the river is 1.3 m/km. The Bazavluk River originates southeast of the village of Kozoduba, and flows from north to south (partly to the southwest) and flows into the Dnieper (Kakhovka Reservoir) 199 kilometers east of the village of Hrushivka. This reservoir has 6 main tributaries, the largest of which are: Rekalova (right, 14 km), Balka Koshovata (left, 16 km), Vodyana (right, 15 km), Bazavluchok (right, 24 km), Solona (left, 56 km), Kamyanka (right, 88 km). The ice crust usually appears in December and disappears in late February-early March. It mostly flows through the plain steppe, but sometimes there are places with high rocky shores. In dry years, shallow areas can dry out and freeze. Some water resources are used by local residents who have settled nearby to irrigate agricultural land.

Yield Stability in a Wide Range of Environments as a Primary Parameter in Winter Wheat Breeding

The breeding of winter wheat was carried out using conventional technology in the Rostov Federal Agrarian Research Center in 2014–2019. It took place in the chernozem (black earth) steppe under the conditions of a severely continental climate with insufficient and unstable humidity. It is demonstrated that yield stability in a wide range of environments becomes possible due to creating the environmental plasticity margin against the basic stress factors when trait values approach a limit in the region (76–88% of plants must survive with a temperature of –18°С at the tillering node, 75–82% after ice crust, 76–78% after May frosts, etc.). The selection markers under droughts, including grain weight per plant, harvest index, aboveground mass, and function of leaves in photosynthesis, have been identified. They enable one to clearly focus on populations and to reveal the required recombinants. Methods have been established to create selectable genetic variation in all breeding directions, which allows the approved program to be implemented. The breeding technology for the purpose of achieving trait transgressions has been proven. Based on the obtained results, the next-generation varieties, such as Bylina Dona, Akapella, Pafos, and Pal’mira 18, have been developed. The degree of their environmental plasticity has been determined.

Improvement of traction capacity of industrial railway transport in the Arctic and on the continental shelf

The Russian Arctic is extremely rich in minerals (hydrocarbons, various minerals, precious metals, etc.). In modern conditions, it is of particular importance to develop vast territories located beyond the Arctic Circle, due to their special socio-economic, geopolitical and defense significance. The rapid development of the Yamal field needs a reliable and modern trunk railway. The project called the Northern Latitudinal Railway has been included in the Strategy for the Development of Railway Transport until 2030. At the temperatures below minus 20 °C, the use of ordinary sand to improve adhesion usually has low effect due to a significant increase in the hardness of ice and ice crust. It should be noted that given sand is present at the contact of ice-glazed rails and wheels, their metal–metal interaction is interrupted by of this sandwiched sand interlayer, which leads to a decrease in the traction characteristics of locomotives. To increase the adhesion coefficient in winter, the author has proposed an engineering solution protected by patent No. 2504492, which consists in the feed of pre-heated, for example, using an induction heater, dry quartz sand to the rail–wheel contact zone. This invention allows increasing the coefficient of adhesion and, consequently, the traction force of locomotives on average up to 10%. Currently, we are carrying out studies to solve the problem of removing ice deposits from the working surface of rails using innovative “sandless” methods that eliminate the need of using ordinary sand. The solution to the problem of removing ice from rails will contribute to the creation of a terrestrial year-round communication between Chukotka and the Barents Sea, which duplicates the Northern Sea Route.

Interfacial Stress and Container Failure During Freezing of Bulk Protein Solutions Can Be Prevented by Local Heating.

Bottles and carboys are used for frozen storage and transport of biopharmaceutical formulations under a wide range of conditions. The quality of freezing and thawing in these systems has been questioned due to the formation of heterogeneous ice structures and deformation of containers. This work shows that during freezing of bulk protein solutions, the liquid at the air-liquid interface freezes first, forming an ice crust and enclosing the liquid phase. As the enclosed liquid freezes, internal pressure rises, pushing the liquid phase through the porous ice crust towards the air interface, leading to interfacial stress and protein aggregation. The aggregation of bovine serum albumin was more intense in the foam-like ice mound that was formed at the top, where bubbles were entrapped. This was characterized experimentally with the assistance of magnetic resonance imaging (MRI). An isothermal cover is proposed to prevent the early freezing of the liquid at the air interface, attenuating substantially interfacial stress to proteins and releasing hydrostatic pressure, preserving the shape and integrity of the containers.

Matching of Models of the Internal Structure and Thermal Regime of Partially Differentiated Titan with Gravity Field

The problem of matching models of the internal structure of partially differentiated Titan with experimentally measured values of Love number k2 (Iess et al., 2012; Durante et al., 2019) according to results of studying the gravity field of Titan based on flights of the Cassini spacecraft is discussed. The values of k2 obtained presumably point to the presence of large masses of liquid (ocean) in the interior of Titan. However, there are no reliable data about the thickness of the outer ice crust and internal (underice) ocean. In this work, constraints on the heat flow, structure of the water-ice shell, and composition of the Titan ocean which are necessary for matching the calculated (model) and experimental Love numbers are considered. The energy release due to ice crystallization in the ocean is estimated. Estimates for the model Love numbers and maximal surface heat flows for the L/LL chondritic composition of the rock–iron component of Titan are obtained with allowance for the radiogenic energy, as well as for the energy of ice crystallization in the ocean due to the satellite cooling: F ~ 5.8 mW/m2, k2 = 0.53, the thickness of the ice Ih shell $${{H}_{{{{{\text{I}}}_{h}}}}}$$ ~ 100 km, and the ocean depth HW ~ 280 km. Model Love numbers k2 agree with experimental ones (Iess et al., 2012) in the presence of the ocean. To match the model (k2 ≥ 0.55) and recently refined values of Love numbers (k2)D = 0.616 ± 0.067 (Durante et al., 2019), it is necessary to satisfy the constraints on the magnitude of the surface heat flow F ≥ 6.3 mW/m2, which corresponds to a water ocean thickness HW ≥ 310 km under the ice Ih shell with a thickness $${{H}_{{{{{\text{I}}}_{h}}}}}$$ ≤ 90 km. The effect of heat flow variations, ice crust thickness, and water–ammonia ocean density on model values of Love numbers is analyzed and the negligible influence of the NH3 admixture in the ocean on the k2 value is demonstrated. The moment of inertia for models of partially differentiated Titan has constraints: I* ≤ 0.342 at k2 ≥ 0.56.

Morphologic Evidence for Volcanic Craters Near Titan's North Polar Region

AbstractCassini Radar observations of Titan have revealed diverse landforms resulting from a variety of geologic processes. Many landforms can be unambiguously interpreted as resulting from atmospheric processes (dunes, rivers, and lakes) or impact cratering. Here we argue from morphological evidence such as nested collapses, elevated ramparts, halos, and islands or floor mountains that some of the abundant small depressions in the north polar region of Titan are volcanic collapse craters. A few similar depressions occur near the south pole; the restriction of this volcanism to polar regions is possibly related to predicted warmer and thinner‐than‐normal ice crust at the low‐elevation poles. The close association of the proposed volcanic craters with polar lakes is consistent with a volcanic origin through explosive eruptions, as either maars or calderas. The apparent freshness of some craters may mean that volcanism has been relatively recently active on Titan or even continues today.

Non-Isothermal Kinetic Model of the Methane Hydrate Dissociation Process at Temperatures Below Ice Melting Point

The paper proposes a new model of gas hydrate particles dissociation at high heat fluxes. In this model, the process of hydrate decomposition occurs under the conditions of competition between heterogeneous kinetics and gas filtration. An analysis of the experimental data gives new values ​​of the kinetic coefficients for the hydrate dissociation at low temperatures. The calculation results make it possible to reproduce experimental data on the dynamics of methane hydrate powder dissociation (including dissociation under the conditions of gas burning above the surface) and to describe the phenomenon of self-conservation in terms of changes in the pore structure of the ice crust. The submodel of dissociation of a single particle is embedded in the mathematical model of transport processes in the powder layer, which allows analyzing the heterogeneity of heating and the collective effects of dissociation.

Internally Heated Porous Convection: An Idealized Model for Enceladus' Hydrothermal Activity

AbstractRecent planetary data and geophysical modeling suggest that hydrothermal activity is ongoing under the ice crust of Enceladus, one of Saturn's moons. According to these models, hydrothermal flow in the porous, rocky core of the satellite is driven by tidal deformation that induces dissipation and volumetric internal heating. Despite the effort in the modeling of Enceladus' interior, systematic understanding—and even basic scaling laws—of internally heated porous convection and hydrothermal activity are still lacking. In this article, using an idealized model of an internally heated porous medium, we explore numerically and theoretically the flows that develop close to and far from the onset of convection. In particular, we quantify heat‐transport efficiency by convective flows as well as the typical extent and intensity of heat flux anomalies created at the top of the porous layer. With our idealized model, we derive simple and general laws governing the temperature and hydrothermal velocity that can be driven in the oceans of icy moons. In the future, these laws could help better constraining models of the interior of Enceladus and other icy satellites.

Schumann resonance on Titan: A critical Re-assessment

Extremely Low Frequency (ELF) electric field signals recorded by the Huygens probe have previously been interpreted as indicating a Schumann Resonance (SR) in the ionosphere-ocean cavity. This interpretation required accommodation of a number of anomalous features with respect to the terrestrial SR, namely a lack of observed lightning discharges with instead an appeal to excitation by interaction with the Saturnian magnetosphere, a horizontal field orientation, and the presence of only a single spectral peak speculated to be the second eigenmode. We suggest here that the data are dominated by artifacts due to mechanical oscillations of the booms or other elements of the probe. Although such an explanation was previously dismissed, we show in new analyses that the ELF time series correlates closely with the history of other mechanical vibration on the probe. In particular, the growth of the ‘ELF’ signals after the release of the main parachute, when the most extensive probe motions also began, and the disappearance of the signals within a few seconds after probe impact, point to a mechanical origin. We additionally review the capability of possible future SR measurements to constrain the thickness of an ice crust on Titan. Even if the magnetospheric excitation does not happen (it may or may not have occurred during the Huygens descent, we only argue that it is not required to explain the data), sporadic lightning during methane rainstorms could yet occur and excite occasional SR activity. However, the interpretation of the SR to retrieve ice thickness is challenged by ambiguities without simultaneous knowledge of the lower ionospheric structure.

Resource-saving thermodynamic cycles in liquid hydrocarbon fuel storage technology

Resource-saving thermodynamic cycles for material and energy flows in the technology of storing liquid hydrocarbon fuel in tanks using a vapor compression heat pump are proposed, which reduce the loss of fuel resulting from evaporation. The heat pump is equipped with a two-section evaporator, the working and reserve sections of which alternately operate in condensation and regeneration modes, respectively. Vapors of hydrocarbon fuel from the tank are discharged to the evaporator section operating in condensation mode. The water contained in the fuel vapor condenses on the heat ex-change surface in the form of an ice crust, and the condensed fuel separated from the water is discharged into an interme-diate tank and returned to the storage tank. The condensation heat of the refrigerant in the condenser is used to heat the intermediate coolant, which is sent to defrost the section of the evaporator operating in the regeneration mode. After this section, the spent intermediate coolant is returned to the condenser in the closed thermodynamic cycle mode. The water formed during defrosting is sent to the biological treatment stage. Thus, real conditions are created for increasing the ener-gy efficiency and environmental safety of the technology for storing liquid hydrocarbon fuel in tanks with maximum con-densation of the vapors resulting from evaporation.

Downhill sledding at 40 AU: Mobilizing Pluto's chaotic mountain blocks

We present a force-balance analysis of the mobilization and emplacement of the large mountain block chains observed on the western rim of Pluto's Sputnik Planitia basin. These mountain blocks are likely disrupted pieces of Pluto's water ice crust that are grounded in the nitrogen ice that fills the basin. After fracturing from the basin rim, they could have slid downslope into the basin under their own weight on timescales as short as hundreds to thousands of years, collecting into the observed ranges where the basin slope shallows below a critical value. This movement would require a lubricating fluid, most likely nitrogen, to be present at the base of the blocks.Traction from flowing nitrogen glaciers could have initiated or aided transport for blocks that are small enough to be at least halfway immersed by the nitrogen. Lateral convective forces within the nitrogen ice sheet did not play a significant role in the mobilization of all but the smallest of the observed blocks that likely float buoyantly in the nitrogen ice.If the blocks did emplace by basal sliding, the requirement that liquid nitrogen be present to provide lubrication provides a key to Pluto's past climate history. This work adds to the body of evidence that erosional features and other surface modification could have been driven by the surface or near-surface flow of liquid nitrogen resulting from global climate change on Pluto.

Ammonia-water freezing as a mechanism for recent cryovolcanism on Pluto

NASA's New Horizons flyby of the Pluto-Charon system in 2015 exposed a multitude of geologically active terrains on the surface of Pluto. Possible evidence of cryovolcanism has been reported in association with crustal scale extensional tectonic structures at Virgil Fossae and at two large circular mountains, informally referred to as Wright Mons and Piccard Mons. Our detailed geologic mapping of Wright Mons and the surrounding region reveals additional circular mounds overlying the main edifice and narrow ravines emanating from the summit, possibly produced by liquid flow. We model the overpressure generated during the freezing of a mixed ammonia-water liquid inside an enclosed chamber in Pluto's ice crust and in a global subsurface ocean. We consider scenarios spanning the possible range of Pluto's ammonia abundance and conclude that stresses generated due to freezing-induced pressurization can exceed the tensile strength of ice and create fractures for the liquid to escape. Our results suggest that freezing in a crustal chamber and the subsurface ocean are both viable mechanisms for cryovolcanism on Pluto and may explain the morphological variety of cryovolcanic formations observed by New Horizons.

Impact of ultrasonic exposure and external pressure in a closed volume on the temperature of the evaporated liquid

The influence of ultrasonic exposure (UE) and external pressure on the process of heat and mass transfer during liquid evaporation is studied, which is an urgent task, since UE is widely used in various technological processes, and the parameters of UE and external pressure determine their effectiveness. Experimental studies of the effect of UE and pressure in a vacuum chamber on the temperature of the evaporated liquid at a constant ultrasonic frequency of 25 kHz and an amplitude of ultrasonic vibrations of 2 μm were carried out. The dependences of the change in the relative load on the amplitude of the oscillations of the bottom of the bath with a change in pressure in a closed volume are obtained, and coefficients are determined that refine the thermal physico-mathematical model of the wave processes in a liquid with ultrasound and a change in external pressure in a closed volume. The liquid temperature from the initial moment of time sharply increases from 27.7 ° C to 32.8 ° C, and then, when the pressure in the vacuum chamber reaches 45 kPa, it gradually decreases until an ice crust forms on the liquid surface. A comparative analysis of the results of mathematical modeling, taking into account the use of refinement coefficients and the results of experimental studies showing that the discrepancy between the temperature of the evaporated liquid, from the initial moment of time to the moment of formation of cavitation bubbles on the surface of the liquid, is 8%. The discrepancy between the temperature of the evaporated liquid from the moment of formation of cavitation bubbles to the freezing point of the liquid is up to 50%, which is explained by the error in measuring the temperature of the liquid with thermocouples during the formation of cavitation bubbles.

Habitat, Climate, and Fisher and Marten Distributions

ABSTRACTSince the mid‐twentieth century, fisher populations (Pekania pennanti) increased in several eastern jurisdictions of North America, particularly in the northern part of the species’ range. Changes in fisher distribution have led to increased overlap with the southern portion of the range of American marten (Martes americana), whose populations may be locally declining. This overlap occurs particularly in habitats undergoing natural and anthropogenic modification. The objective of our study was to determine the respective effects of habitat changes and climatic conditions on fisher and marten populations in Quebec, Canada, based on trapper knowledge. We analyzed annual fisher and marten harvest (number of pelts sold/100 km2) between the 1984–1985 and 2014–2015 trapping seasons using linear mixed models. Fisher harvest increased with the increased abundance of mixed forests >12 m tall, resulting from decades of forest harvesting. Fisher harvest decreased with increasing spring rains, which can affect survival when rearing young. Marten harvest decreased with increasing winter rains, which lower thermoregulation capacity and hamper movements by creating an ice crust on the snowpack, reducing access to subnivean areas. Decline in marten harvest during the 30‐year study period coincided with an increase in fisher harvest, suggesting possible interspecific competition. Results highlight that managers should strive to maintain mixedwood stands taller than 12 m to maintain high quality habitat for fishers. Our study confirms the importance of working with trappers to assess furbearing population trends in response to habitat changes and climatic conditions. © 2019 The Wildlife Society.