Polar Plateau Research Articles

Electrochemical properties of plasticized PVA-based electrolyte inserted with alumina nanoparticles for EDLC application with enhanced dielectric constant

In the current study, the role of alumina nanoparticles was examined in the electrochemical and device performance of PVA-based electrolytes. The NaSCN was used as a cation provider for the host electrolyte, and the glycerol plasticizers were used to enhance conductivity and flexibility. The ratio of salt and plasticizer was fixed, while nanoparticles were varied. The results of impedance AC conductivity confirm that 3 wt% of alumina insertion results in high DC conductivity, which is sufficient for electrochemical device application. Electrode polarization region and plateau area are clearly distinguished in AC spectra. The study of the Dielectric constant reveals that charge storage is maximum at 3 wt% of alumina. The dielectric constant values are about twice the dielectric loss value, which is the topic of immense scientific discussion. The contribution of ion fraction was found to be 0.94, which is excellent compared to the negligible contribution of electrons, which is about 0.05. Electrochemical stability is an additional crucial factor and was found to be 2.47 V. To identify any Redox or non-Redox phenomena occurring in the electrical double-layer capacitor (EDLC) cyclic voltammetry (CV) as the simplest analysis method has been carried out on the sample having the highest DC value. A leaf-like form of the CV plot was noticed at high scan rates, while a rectangular shape was identified at low scan rates. The charge-discharge shape is almost close to the ideal triangular pattern. The discharge part was used to calculate critical EDLC device parameters such as ESR, efficiency, specific capacitance power density, and energy density over 2000 cycles. Low ESR (below 60 Ω) and stable efficiency (almost 100 %) of the device results in high capacitance (≈87 F/g), power density (2978 Wh/kg), and energy density (12.86 W kg−1). The results established that nan-fillers alongside plasticizer is crucial to deliver EDLC devices with improved performances.

Analysis of hysteresis loops and dielectric performance in the ovalene-like system: Monte Carlo study

This Monte Carlo study offers a comprehensive analysis of the ovalene-like system, emphasizing its dielectric behavior, thermal performance and hysteresis loops. The investigation reveals intricate dynamics influenced by diverse parameters, contributing to a nuanced understanding of the system’s response. Additionally, the study scrutinizes the impact of various physical parameters on the thermal behavior of polarizations and susceptibilities. The examination thoroughly explores the influence of these parameters on loop characteristics, coercive field, and saturation behavior, unveiling the formation of multiple loops and polarization plateaus on the electric hysteresis. In summary, this study advances our understanding of the ovalene-like system’s dielectric response, thermal characteristics and hysteresis dynamics, providing valuable insights for future research and applications, particularly in advanced electronic devices.

Dielectric behavior of graphene-type nanolattice: Monte Carlo simulations

In this study, we used Monte Carlo simulations to explore the dielectric properties of a graphene-type nanolattice, revealing significant effects on blocking temperature. The ferroelectric interaction and external electric field parameters greatly influence the nanolattice's dielectric and thermal properties. We observed a polarization plateau and multiple hysteresis loops, indicating stability and various polarization states. Unexpected ferroelectric behavior in graphene-based systems was confirmed experimentally in moiré heterostructures, validating theoretical predictions. This aligns with models like the Ising model and enhances material stability and response, offering insights for precise control over dielectric properties in nanotechnology.

Electric hysteresis cycles and polarization plateaus in MXene-like lattices: Monte Carlo simulations

This scientific paper presents a comprehensive investigation into the behavior of electric hysteresis cycles and polarization plateaus in the MXene-like system. Utilizing Monte Carlo simulations (MCs), the study explores the effects of ferrielectric and crystal field parameters on these phenomena. The coercive electric field and the surface characteristics of the loops in the electric hysteresis cycles are analyzed, along with the critical and saturation electric fields in the polarization plateaus. The research findings provide insights into the control of the MXene-like system, offering opportunities to optimize MXene materials for diverse applications. The study can contribute to the advancement of MXene research and lays the foundation for future developments in the field.

Emergence of Multiple Hysteresis Cycles and Polarization Plateaus: A Monte Carlo Investigation of Fullerene-Like System

This study uses Monte Carlo simulations to study the emergence of polarization plateaus and hysteresis cycles within fullerene-like systems. To explore the dielectric properties of the system, we also applied the Blume-Capel Ising model, which considered critical, coercive and saturation fields. Temperature, ferrielectric parameter, and crystal field all influenced the system’s behavior. Multi-state memory devices, spintronics, and materials characterization can benefit from the discovery of multiple loops and polarization plateaus.

Seasonality Is the Main Determinant of Microbial Diversity Associated to Snow/Ice around Concordia Station on the Antarctic Polar Plateau.

The French-Italian Concordia Research Station, situated on the Antarctic Polar Plateau at an elevation of 3233 m above sea level, offers a unique opportunity to study the presence and variation of microbes introduced by abiotic or biotic vectors and, consequently, appraise the amplitude of human impact in such a pristine environment. This research built upon a previous work, which explored microbial diversity in the surface snow surrounding the Concordia Research Station. While that study successfully characterized the bacterial assemblage, detecting fungal diversity was hampered by the low DNA content. To address this knowledge gap, in the present study, we optimized the sampling by increasing ice/snow collected to leverage the final DNA yield. The V4 variable region of the 16S rDNA and Internal Transcribed Spacer (ITS1) rDNA was used to evaluate bacterial and fungal diversity. From the sequencing, we obtained 3,352,661 and 4,433,595 reads clustered in 930 and 3182 amplicon sequence variants (ASVs) for fungi and bacteria, respectively. Amplicon sequencing revealed a predominance of Basidiomycota (49%) and Ascomycota (42%) in the fungal component; Bacteroidota (65.8%) is the main representative among the bacterial phyla. Basidiomycetes are almost exclusively represented by yeast-like fungi. Our findings provide the first comprehensive overview of both fungal and bacterial diversity in the Antarctic Polar Plateau's surface snow/ice near Concordia Station and to identify seasonality as the main driver of microbial diversity; we also detected the most sensitive microorganisms to these factors, which could serve as indicators of human impact in this pristine environment and aid in planetary protection for future exploration missions.

A topographic hinge-zone divides coastal and inland ice dynamic regimes in East Antarctica

The impact of late Cenozoic climate on the East Antarctic Ice Sheet is uncertain. Poorly constrained patterns of relative ice thinning and thickening impair the reconstruction of past ice-sheet dynamics and global sea-level budgets. Here we quantify long-term ice cover of mountains protruding the ice-sheet surface in western Dronning Maud Land, using cosmogenic Chlorine-36, Aluminium-26, Beryllium-10, and Neon-21 from bedrock in an inverse modeling approach. We find that near-coastal sites experienced ice burial up to 75–97% of time since 1 Ma, while interior sites only experienced brief periods of ice burial, generally <20% of time since 1 Ma. Based on these results, we suggest that the escarpment in Dronning Maud Land acts as a hinge-zone, where ice-dynamic changes driven by grounding-line migration are attenuated inland from the coastal portions of the East Antarctic Ice Sheet, and where precipitation-controlled ice-thickness variations on the polar plateau taper off towards the coast.

Paleoglaciology of the central East Antarctic Ice Sheet as revealed by blue-ice sediment

We present ∼100 cosmogenic surface exposure ages, including 75 new analyses, for a blue-ice moraine complex at Mt. Achernar, head of Law Glacier, in the central Transantarctic Mountains. The 10Be–3He–26Al ages along with previously-published boron concentrations chronicle past behavior of the East Antarctic Ice Sheet (EAIS) along the edge of the polar plateau since the sediments started to accumulate, around 0.5–1 Ma. Samples analyzed for 10Be from the Law Glacier surface record <100 years of exposure, indicating they likely have negligible inheritance when first exposed. The Law Glacier surface experienced relatively minor fluctuations in surface elevation throughout MIS 6 and 5, and likely during prior periods, as geomorphic features are intact and exposure ages are coherent on the moraine, ranging from ∼210 to ∼86 ka; respective means for MIS 5 till in two different areas are 106 ± 9.1 ka [n = 4 ages] and 106 ± 5.1 ka [n = 6]. Although we infer the Law Glacier has been relatively close to its current configuration generally since 0.5–1 Ma, disturbances to Achernar blue-ice moraine architecture seem apparent at times especially prior to the last two glacial cycles. The largest observed disturbance occurred when the nearby Lewis Cliffs Ice Tongue expanded either close to, or earlier than, 500-400 ka. A minimum ice thickness increase of 30 m is associated with the ∼20 ka blue-ice ridges, and a lateral moraine indicates the Law Glacier surface was ∼40–50 m higher at ∼9.2 ± 0.5 ka. Our findings support that lateral accretion over time formed the Mt. Achernar blue-ice moraine sequence, and by implication, other analogue Antarctic deposits. We interpret blue-ice moraines as representing, at times, relatively constant outlet glacier conditions and concur with prior studies that they reflect near-equilibrium forms. Blue-ice sediments are an underutilized and dateable paleoglaciologic and paleoclimate archive in Antarctica, including for former ice surface dynamics and possibly as a repository of old ice during periods such as MIS 5 and prior.

Organic matter distribution in the icy environments of Taylor Valley, Antarctica

Glaciers can accumulate and release organic matter affecting the structure and function of associated terrestrial and aquatic ecosystems. We analyzed 18 ice cores collected from six locations in Taylor Valley (McMurdo Dry Valleys), Antarctica to determine the spatial abundance and quality of organic matter, and the spatial distribution of bacterial density and community structure from the terminus of the Taylor Glacier to the coast (McMurdo Sound). Our results showed that dissolved and particulate organic carbon (DOC and POC) concentrations in the ice core samples increased from the Taylor Glacier to McMurdo Sound, a pattern also shown by bacterial cell density. Fluorescence Excitation Emission Matrices Spectroscopy (EEMs) and multivariate parallel factor (PARAFAC) modeling identified one humic-like (C1) and one protein-like (C2) component in ice cores whose fluorescent intensities all increased from the Polar Plateau to the coast. The fluorescence index showed that the bioavailability of dissolved organic matter (DOM) also decreased from the Polar Plateau to the coast. Partial least squares path modeling analysis revealed that bacterial abundance was the main positive biotic factor influencing both the quantity and quality of organic matter. Marine aerosol influenced the spatial distribution of DOC more than katabatic winds in the ice cores. Certain bacterial taxa showed significant correlations with DOC and POC concentrations. Collectively, our results show the tight connectivity among organic matter spatial distribution, bacterial abundance and meteorology in the McMurdo Dry Valley ecosystem.

Roald Amundsen’s route across the polar plateau in 1911–1912

Abstract Roald Amundsen’s exact route from the top of the Axel Heiberg glacier to the South Pole and back in 1911–1912 has always been somewhat unclear because he never observed his longitude during his southern journey. His approach was simply to steer approximately in a true southerly direction by magnetic compass as long as obstacles did not force him to deviate. The fact that he only knew approximately where he was most of the time on the polar plateau never caused any severe problems for him, but it complicated the search for a depot during the return journey. Based on Amundsen’s bearings of some peaks in the Transantarctic Mountains, in combination with his compass courses adjusted with accurate values for the magnetic declination at the time, this paper elucidates Amundsen’s actual route across the polar plateau in 1911–1912. The main result is that Amundsen must have taken a more easterly route than what previously has been assumed.

Polarization Plateaus and Hysteresis Behaviors of a Stanene-like Nanostructure: Monte Carlo Simulations

The dielectric properties and the hysteresis electric cycles of a monolayer stanene-like nanostructure are studied using Monte Carlo simulations. The considered system consists of mixed spins S= ±1 and σ= ±7/2 with an ferrielectric intermediate exchange coupling. We start by analyzing the ground state phase diagrams for (T = 0). In this case, only 18 configurations are stable among 8 × 3 = 24 possible ones. Besides, for T > 0, we investigate the behavior of the blocking temperature for different electric parameters. We discuss the polarization plateaus of the hysteresis electric cycles of this nanostructure by exploring the critical (EC), the coercive (ECoer), and the saturation (ES) electric fields.

North polar trough formation due to in-situ erosion as a source of young ice in mid-latitudinal mantles on Mars

The clockwise spiral of troughs marking the Martian north polar plateau forms one of the planet’s youngest megastructures. One popular hypothesis posits that the spiral pattern resulted as troughs underwent poleward migration. Here, we show that the troughs are extensively segmented into enclosed depressions (or cells). Many cell interiors display concentric layers that connect pole- and equator-facing slopes, demonstrating in-situ trough erosion. The segmentation patterns indicate a history of gradual trough growth transversely to katabatic wind directions, whereby increases in trough intersections generated their spiral arrangement. The erosional event recorded in the truncated strata and trough segmentation may have supplied up to ~25% of the volume of the mid-latitude icy mantles. Topographically subtle undulations transition into troughs and have distributions that mimic and extend the troughs’ spiraling pattern, indicating that they probably represent buried trough sections. The retention of the spiral pattern in surface and subsurface troughs is consistent with the megastructure’s stabilization before its partial burial. A previously suggested warm paleoclimatic spike indicates that the erosion could have occurred as recently as ~50 Ka. Hence, if the removed ice was redeposited to form the mid-latitude mantles, they could provide a valuable source of near-surface, clean ice for future human exploration.

Social dynamics in an isolated, confined, and extreme workplace.

There can be few indoor workplaces that are more subject to the meteorological and atmospheric conditions of their locations than permanent stations on the high, inland polar plateau of Antarctica. The US Amundsen-Scott South Pole Station is such a workplace, totally isolated during the 8-9months of the austral winter, more than 800miles (1287km) from the nearest other human habitation. The wintering party at the South Pole must deal with all the demands and stressors of an isolated, confined, and extreme environment without the prospect of relief from the outside world. In 1975, the seventeen men chosen to winter at the South Pole had an additional challenge. In February, as the austral winter was about to begin, a new geodesic-domed research station had just been completed. The station was the first of its kind, and the vagaries of its design and construction would be significant factors in the health and well-being of station residents as winter progressed. Potential physical and psychological problems from isolation literature are commented upon, and some significant events from this noteworthy winter are described. In addition, supporting quantitative data from current research at South Pole are used to better understand these events.

Ice surface changes during recent glacial cycles along the Jutulstraumen and Penck Trough ice streams in western Dronning Maud Land, East Antarctica

Reconstructing past ice-sheet surface changes is key to testing and improving ice-sheet models. Data constraining the past behaviour of the East Antarctic Ice Sheet are sparse, limiting our understanding of its response to past, present and future climate change. Here, we report the first cosmogenic multi-nuclide (10Be, 26Al, 36Cl) data from bedrock and erratics on nunataks along the Jutulstraumen and Penck Trough ice streams in western Dronning Maud Land, East Antarctica. Spanning elevations between 741 and 2394 m above sea level, the samples have apparent exposure ages between 2 ka and 5 Ma. The highest-elevation bedrock sample indicates (near-) continuous minimum exposure since the Pliocene, with a low apparent erosion rate of 0.15 ± 0.03 m Ma−1, which is similar to results from eastern Dronning Maud Land. In contrast to studies in eastern Dronning Maud Land, however, our data show clear indications of a thicker-than-present ice sheet within the last glacial cycle, with a thinning of ∼35–120 m during the Holocene (∼2–11 ka). Difficulties in separating suitable amounts of quartz from the often quartz-poor rock-types in the area, and cosmogenic nuclides inherited from exposure prior to the last deglaciation, prevented robust thinning estimates from elevational profiles. Nevertheless, the results clearly demonstrate ice-surface fluctuations of several hundred meters between the current grounding line and the edge of the polar plateau for the last glacial cycle, a constraint that should be considered in future ice-sheet model simulations.

River temperature and the thermal-dynamic transport of sediment

Spatial and temporal variability of river temperature, and its impact on sediment transport, is explored. Global river temperatures, computed daily using 1980–2010 climate, reflect latitudinal and seasonal variations in solar radiation, wind patterns, humidity, and water sources, and can be cooler or warmer than air temperatures. Subpolar, Polar and High Plateau rivers are cold (TMEAN: <8 °C), and of intermediate variability (Tσ: 6° to 10 °C), are highly sensitive to temperature variations, which together favor a river's ability to transport sediment. Temperate, Subtropical and Alpine rivers are of intermediate temperatures (TMEAN: 5° to 26 °C) with a maximum in variability (Tσ: >8°); their transport responsiveness is dependent on their minimum temperature. Tropical rivers are warm (TMEAN: >25 °C), less sensitive to temperature swings, and possess a reduced sediment transport capacity; their narrow temperature variability (Tσ: 1° to 4 °C) favors finer-grained sediment transport. Fluid density of river water ranges by 3.5%, and more rarely increases by 170% and thereby increases sediment transport 2.8-fold. Kinematic viscosity has a global range of 72.5%, and works to reduce sediment transport as the river warms. A 25 °C increase in water temperature, due to some combination of river elevation descent, or flow to warmer latitudes, or seasonal increases, can increase grain settling velocities by 7.3%, 42%, 85%, 90% for a 1000-μm, 250-μm, 62.5-μm, or a 10-μm grain respectively, and reduce sediment transport by 90% for a grain size population centered at 62.5 μm, or 300% if centered at 10 μm. The common practice of using fluid density and temperature constants (ρf = 1000 kg/m3, T = 20 °C) in transport models, can greatly under-predict subpolar and alpine river transport and over-predict sediment transport in a tropical river. Temperature variations impact rivers that transport a preponderance of fine sediment, a characteristic of most large rivers. These trends in river temperature and sediment transport have important ecological and anthropogenic implications. The effects on sediment transport will be especially important to quantify under a warming climate and where human influences, such as urbanization, may change the riverine thermal regime.

Regionalization of the Atmospheric Dust Cycle on the Periphery of the East Antarctic Ice Sheet Since the Last Glacial Maximum

AbstractIce cores from inner East Antarctica provided some of the longest and most detailed climatic reconstructions and allowed understanding the relationships between atmospheric mineral dust and climate. In this work we present synchrotron radiation X‐ray Fluorescence geochemical data of dust from the TALDICE ice core drilled at Talos Dome, a peripheral ice dome of East Antarctica (Western Ross Sea). Results highlight a dominant southern South American origin for dust at TALDICE during the Last Glacial Maximum, similarly to other sites located further inland onto the polar plateau. On the contrary, a different scenario concerns Talos Dome during the Holocene if it is compared to more inner sites. The tight connection between high southern latitudes and Antarctica that characterizes cold climate stages becomes weaker since the onset of the last climatic transition and throughout the Holocene. The net effect of this process at Talos Dome is a modification of the atmospheric and environmental settings, owing to local Antarctic sources of Victoria Land to gain importance and become the dominant ones. At the same time in inner East Antarctica the provenance of dust remains remote also during Holocene, revealing an evolution of the homogeneous scenario observed in glacial periods. The enhanced sensitivity of peripheral ice sheet sites to local dust sources makes Talos Dome an ideal site to assess the climatic and atmospheric changes of the peripheral sectors of East Antarctica during the current interglacial period.

MARSIS Radar Data Interpretation to Characterize the Deeper Layers in the North Polar Cap on Mars

We performed a study using radar data from the Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) on board ESA’s Mars Express spacecraft [23]. MARSIS collects data by transmitting a low-frequency radar pulse, between 1.3 and 5.5 MHz with a 1 MHz bandwidth, which is capable of penetrating below the surface and is reflected by any dielectric discontinuity present in the sub-surface, reaching a depth of analysis of 3.7 km in icy deposits [25]. We analyzed radargrams crossing Planum Boreum, the 1000 km diameter north polar plateau located in the center of Borealis Basin, to study the deeper layered deposits identified in the north polar cap’s stratigraphy (mapped by, e.g., [34]). The main objective of our study was to obtain a stratigraphic geological profile to identify the deep trend of the Cavi unit, one of the main geological units which characterize Planum Boreum. This unit, deposited on a surface of unconformity, indicates the period of compositional variation of the placement materials at the bottom of the north polar plateau, in which the lithic percentage decreased exponentially to the advantage of an almost pure ice composition [34]. The Cavi unit represents an important element for the understanding of the north polar cap evolution, the past climate cycles on Mars, and the changes in the orbital parameters of the planet [27]. The geological profile was obtained through the use of a Geographical Information System, which allowed us to correlate the USGS cartography with MOLA topography, and the MARSIS radargrams. The outline trace covers about 1500 km, passing through the Planum Boreum and the surrounding areas. The final obtained stratigraphic profile allowed us to have a global vision of the stratigraphic relationships of the various units, to show the trend of the Cavi unit, to identify some covered structures, and also to formulate a plausible hypothesis about the evolution of the Planum Boreum. Using this method of radargram interpretation, we showed how to improve geological analysis of planetary sub-surfaces.

The multiple effects of potassium doping on LiVPO4F/C composite cathode material for lithium ion batteries

The intermediate product VPO4/C is synthesized via sol-gel method, then it is mixed with other raw materials and calcined to prepare Li1-xKxVPO4F/C (x = 0, 0.005, 0.01, 0.02). Potassium with large ionic radius partially substitutes the lithium site and slightly increases the unit cell volume. The potassium dopant suppresses the formation of Li3V2(PO4)3 and reduces the particle agglomeration. The doped samples possess lower polarization and higher discharge plateau than the pristine LiVPO4F/C, and Li0.99K0.01VPO4F/C exhibits the best electrochemical performance. With 2.9 wt% amorphous carbon uniformly wrapping the surface, Li0.99K0.01VPO4F/C delivers a reversible capacity of 140.9 mA h g-1 at 0.12 C and maintains 98.3 mA h g-1 at the charge/discharge rate of 10 C. Its specific discharge capacity with a retention of 96.13% decreases from 131.9 to 126.8 mA h g-1 after 125 cycles at the charge/discharge rate of 1 C. The improvement of rate and cycling performance is ascribed to the decrease of charge transfer resistance (88.47 Ω) and the increase of Li+ diffusion coefficient (6.75 × 10−13 cm2 s−1), indicating that potassium doping facilitates the migration and diffusion of Li+ due to the expansion of Li+ pathway.

Warm-based basal sediment entrainment and far-field Pleistocene origin evidenced in central Transantarctic blue ice through stable isotopes and internal structures

ABSTRACTStable isotopes of water (δ18O and δ2H) were measured in the debris-laden ice underlying an Antarctic blue ice moraine, and in adjoining Law Glacier in the central Transantarctic Mountains. Air bubble content and morphology were assessed in shallow ice core samples. Stable isotope measurements plot either on the meteoric waterline or are enriched from it. The data cluster in two groups: the ice underlying the moraine has a δ2H:δ18O slope of 5.35 ± 0.92; ice from adjoining portions of Law Glacier has a slope of 6.69 ± 1.39. This enrichment pattern suggests the moraine's underlying blue ice entrained sediment through refreezing processes acting in an open system. Glaciological conditions favorable to warm-based sediment entrainment occur 30–50 km upstream. Basal melting and refreezing are further evidenced by abundant vapor figures formed from internal melting of the ice crystals. Both the moraine ice and Law Glacier are sufficiently depleted of heavy isotopes that their ice cannot be sourced locally, but instead must be derived from far-field interior regions of the higher polar plateau. Modeled ice flow speeds suggest the ice must be at least 80 ka old, with Law Glacier's ice possibly dating to OIS 5 and moraine ice older still.

In Shackleton's trails: Central and local thermoadaptive modifications to cold and hypoxia after a man-hauling expedition on the Antarctic Plateau

Cold and hypoxia constitute the main environmental stressors encountered on the Antarctic Plateau. Hence, we examined whether central and/or peripheral acclimatisation to the combined stressors of cold and hypoxia would be developed in four men following an 11-day man-hauling expedition on this polar region. Before and after the journey, participants performed a static whole-body immersion in 21 °C water, during which they were breathing a hypoxic gas (partial pressure of inspired O2: ~97 mmHg). To evaluate their local responses to cold, participants also immersed the hand into 8 °C water for 30 min, while they were whole-body immersed and mildly hypothermic [i.e. 0.5 °C fall in rectal temperature (Trec) from individual pre-immersion values]. Trec and skin temperature (Tsk), skin blood flux, and oxygen uptake (reflecting shivering thermogenesis) were monitored throughout. The polar expedition accelerated by ~14 min the drop in Trec [final mean (95% confidence interval) changes in Trec: Before = −0.94 (0.15) °C, After: − 1.17 (0.23) °C]. The shivering onset threshold [Before: 19 (22) min, After: 25 (19) min] and gain [Before: − 4.19 (3.95) mL min−1 kg−1, After: − 1.70 (1.21) mL min−1 kg−1] were suppressed by the expedition. Tsk did not differ between trials. The development of a greater post-expedition hypothermic state did not compromise finger circulation during the hand-cooling phase. Present findings indicate therefore that a hypothermic pattern of cold acclimatisation, as investigated in hypoxia, was developed following a short-term expedition on the South Polar Plateau; an adaptive response that is characterised mainly by suppressed shivering thermogenesis, and partly by blunted cutaneous vasoconstriction.