6,280 research outputs found
Snoozing through the storm: torpor use during a natural disaster
Although storms provide an extreme environmental challenge to organisms and are predicted to increase in frequency and intensity due to climate change, there are no quantitative observations on the behaviour and physiology of animals during natural disasters. We provide the first data on activity and thermal biology of a free-ranging, arboreal mammal during a storm with heavy rain and category 1 cyclone wind speeds. We studied a population of sugar gliders (Petaurus breviceps), a species vulnerable to bad weather due to their small body size and mode of locomotion, in a subtropical habitat during spring when storms are common. Although torpor is generally rare in this species, sugar gliders remained inactive or reduced foraging times during the storm and further minimized energy demands by entering deep torpor. All animals survived the storm and reverted to normal foraging activity during the following night(s). It thus appears that heterothermic mammals have a crucial adaptive advantage over homeothermic species as they can outlast challenging weather events, such as storms and floods, by reducing metabolism and thus energetic needs
Seismic modeling using the frozen Gaussian approximation
We adopt the frozen Gaussian approximation (FGA) for modeling seismic waves.
The method belongs to the category of ray-based beam methods. It decomposes
seismic wavefield into a set of Gaussian functions and propagates these
Gaussian functions along appropriate ray paths. As opposed to the classic
Gaussian-beam method, FGA keeps the Gaussians frozen (at a fixed width) during
the propagation process and adjusts their amplitudes to produce an accurate
approximation after summation. We perform the initial decomposition of seismic
data using a fast version of the Fourier-Bros-Iagolnitzer (FBI) transform and
propagate the frozen Gaussian beams numerically using ray tracing. A test using
a smoothed Marmousi model confirms the validity of FGA for accurate modeling of
seismic wavefields.Comment: 5 pages, 8 figure
A new cue for torpor induction: charcoal, ash and smoke
Recent work has shown that the use of torpor for energy conservation increases after forest fires in heterothermic mammals, probably in response to the reduction of food. However, the specific environmental cues for this increased torpor expression remain unknown. It is possible that smoke and the novel substrate of charcoal and ash act as signals for an impending period of starvation requiring torpor. We therefore tested the hypothesis that the combined cues of smoke, a charcoal/ash substrate and food shortage will enhance torpor expression in a small forest-dwelling marsupial, the yellowfooted antechinus (Antechinus flavipes), because like other animals that live in fire-prone habitats they must effectively respond to fires to ensure survival. Activity and body temperature patterns of individuals in outdoor aviaries were measured under natural environmental conditions. All individuals were strictly nocturnal, but diurnal activity was observed shortly after smoke exposure. Overall, torpor in females was longer and deeper than that in males. Interestingly, while both males and females increased daily torpor duration during food restriction by >2-fold as anticipated, a combination of food restriction and smoke exposure on a charcoal/ash substrate further increased daily torpor duration by βΌ2-fold in both sexes. These data show that this combination of cues for torpor induction is stronger than food shortage on its own. Our study provides significant new information on how a small forest-dwelling mammal responds to fire cues during and immediately after a fire and identifies a new, not previously recognised, regulatory mechanism for thermal biology in mammals
Physiological and behavioral responses of an arboreal mammal to smoke and charcoal-ash substrate.
The recent observation that torpor plays a key role in post-fire survival has been mainly attributed to the reduced food resources after fires. However, some of these adjustments can be facilitated or amplified by environmental changes associated with fires, such as the presence of a charcoal-ash substrate. In a previous experiment on a small terrestrial mammal the presence of charcoal and ash linked to food restriction intensified torpor use. However, whether fire cues also act as a trigger of torpor use when food is available and whether they affect other species including arboreal mammals remains elusive. To evaluate whether smoke, charcoal and ash can act as proximate triggers for an impending period of food shortage requiring torpor for mammals, we conducted an experiment on captive sugar gliders (Petaurus breviceps), a small, arboreal marsupial, housed in outside aviaries under different food regimes and natural ambient conditions. When food was available, fire simulation via exposure to smoke and charcoal-ash substrate caused a significant earlier start of activity and a significant decrease in resting body temperature. In contrast, only when food was withheld, did smoke and charcoal-ash exposure significantly enhance torpor depth and duration. Thus, our study not only provides evidence that fire simulation does affect arboreal and terrestrial species similarly, but also suggests that smoke and ash were presumably selected as cues for torpor induction because they indicate an impending lack of food
ΠΠΎΠ½ΡΡΠΎΠ»Ρ ΠΏΠ°ΡΠ°ΠΌΠ΅ΡΡΠΎΠ² Π²ΠΎΠ·Π΄ΡΡΠ½ΠΎΠΉ ΡΡΠ΅Π΄Ρ Π΄Π»Ρ ΠΏΠΎΡΡΡΠΎΠ΅Π½ΠΈΡ ΡΠΈΡΡΠ΅ΠΌ ΠΎΠ±Π½Π°ΡΡΠΆΠ΅Π½ΠΈΡ ΠΏΠΎΠΆΠ°ΡΠΎΠΎΠΏΠ°ΡΠ½ΠΎΠ³ΠΎ ΡΠΎΡΡΠΎΡΠ½ΠΈΡ
Π Π΄Π°Π½Π½ΠΎΠΉ ΡΡΠ°ΡΡΠ΅ Π΄Π°Π½ Π°Π½Π°Π»ΠΈΠ· ΠΏΡΠΎΡΠ΅ΡΡΠ° ΡΠ°Π·Π²ΠΈΡΠΈΡ ΠΏΠΎΠΆΠ°ΡΠ°, ΠΏΠΎΠΊΠ°Π·Π°Π²ΡΠΈΠΉ, ΡΡΠΎ ΠΏΠΎΠΆΠ°Ρ ΡΠ°Π·Π²ΠΈΠ²Π°Π΅ΡΡΡ Π² ΡΠ΅ΡΠ΅Π½ΠΈΠ΅ ΡΠ΅ΠΌΠΈ ΡΡΠ°Π΄ΠΈΠΉ, ΠΊΠ°ΠΆΠ΄ΠΎΠΉ ΠΈΠ· ΠΊΠΎΡΠΎΡΡΡ
ΡΠΎΠΎΡΠ²Π΅ΡΡΡΠ²ΡΠ΅Ρ ΡΠΎΠ²ΠΎΠΊΡΠΏΠ½ΠΎΡΡΡ ΡΠ²Π»Π΅Π½ΠΈΠΉ (ΡΠ°ΠΊΡΠΎΡΠΎΠ², ΠΏΡΠΈΠ·Π½Π°ΠΊΠΎΠ²) ΠΏΠΎΠΆΠ°ΡΠΎΠΎΠΏΠ°ΡΠ½ΠΎΠ³ΠΎ ΡΠΎΡΡΠΎΡΠ½ΠΈΡ, Ρ
Π°ΡΠ°ΠΊΡΠ΅ΡΠΈΠ·ΡΠ΅ΠΌΠ°Ρ Π½Π°Π±ΠΎΡΠΎΠΌ ΠΎΠΏΡΠ΅Π΄Π΅Π»Π΅Π½Π½ΡΡ
ΠΏΠ°ΡΠ°ΠΌΠ΅ΡΡΠΎΠ². ΠΠΎΠΊΠ°Π·Π°Π½ΠΎ, ΡΡΠΎ ΠΏΠΎΠ½ΠΈΠΆΠ΅Π½ΠΈΠ΅ ΡΡΠ°Π΄ΠΈΠΉΠ½ΠΎΡΡΠΈ ΡΠ΅Π³ΠΈΡΡΡΠΈΡΡΠ΅ΠΌΠΎΠ³ΠΎ ΡΠ°ΠΊΡΠΎΡΠ° ΠΏΡΠΈΠ²ΠΎΠ΄ΠΈΡ ΠΊ ΠΏΠΎΡΡΡΠΎΠ΅Π½ΠΈΡ ΠΏΡΠΎΡΠΈΠ²ΠΎΠΏΠΎΠΆΠ°ΡΠ½ΡΡ
ΠΏΡΠΎΡΠΈΠ»Π°ΠΊΡΠΈΠΊΠΎ-Π΄ΠΈΠ°Π³Π½ΠΎΡΡΠΈΡΠ΅ΡΠΊΠΈΡ
ΡΠΈΡΡΠ΅ΠΌ, ΠΏΠΎΡΠΊΠΎΠ»ΡΠΊΡ ΡΠ΅ΠΌ Π½ΠΈΠΆΠ΅ ΡΠ΅Π³ΠΈΡΡΡΠΈΡΡΠ΅ΠΌΠ°Ρ ΡΡΠ°Π΄ΠΈΡ, ΡΠ΅ΠΌ Π½Π΅ΠΎΠΏΡΠ΅Π΄Π΅Π»Π΅Π½Π½Π΅Π΅ ΡΠ²ΡΠ·Ρ ΡΠ°ΠΊΡΠ° Π΅Π΅ ΠΎΠ±Π½Π°ΡΡΠΆΠ΅Π½ΠΈΡ Ρ ΠΏΠΎΠΆΠ°ΡΠΎΠΌ. Π£ΠΊΠ°Π·Π°Π½ΠΎ, ΡΡΠΎ Ρ ΡΠ°Π·Π²ΠΈΡΠΈΠ΅ΠΌ ΡΠ»Π΅ΠΊΡΡΠΎΠ½Π½ΠΎΠΉ ΡΠ΅Ρ
Π½ΠΈΠΊΠΈ ΡΡΠ°Π΄ΠΈΠΉΠ½ΠΎΡΡΡ ΠΈΡΠΏΠΎΠ»ΡΠ·ΡΠ΅ΠΌΡΡ
Π΄Π»Ρ ΠΎΠ±Π½Π°ΡΡΠΆΠ΅Π½ΠΈΡ ΡΠ°ΠΊΡΠΎΡΠΎΠ² ΠΏΠΎΠΆΠ°ΡΠ½ΡΡ
ΡΠΈΡΡΠ°ΡΠΈΠΉ, Π² ΡΠ΅Π»ΠΎΠΌ, ΠΏΠΎΠ½ΠΈΠΆΠ°Π΅ΡΡΡ, Π° ΡΠ°ΠΊΠΆΠ΅ ΠΎΡΠΌΠ΅ΡΠ΅Π½ΠΎ, ΡΡΠΎ Π΄Π»Ρ ΠΊΠ°ΠΆΠ΄ΠΎΠ³ΠΎ ΠΎΠ±ΡΠ΅ΠΊΡΠ° ΠΊΠΎΠ½ΡΡΠΎΠ»Ρ Π½Π΅ΠΎΠ±Ρ
ΠΎΠ΄ΠΈΠΌ Π²ΡΠ±ΠΎΡ (Π²ΡΡΠ²Π»Π΅Π½ΠΈΠ΅) ΠΎΠΏΡΠΈΠΌΠ°Π»ΡΠ½ΠΎΠ³ΠΎ ΡΠ°ΠΊΡΠΎΡΠ°, Π² ΡΠ°ΡΡΠ½ΠΎΡΡΠΈ, ΠΏΠΎ ΠΌΠ½ΠΎΠ³ΠΈΠΌ Ρ
Π°ΡΠ°ΠΊΡΠ΅ΡΠΈΡΡΠΈΠΊΠ°ΠΌ ΠΎΠΏΡΠΈΠΌΠ°Π»ΡΠ½ΡΠΌ ΡΠ°ΠΊΡΠΎΡΠΎΠΌ Π΄Π»Ρ Π»Π΅ΡΠ°ΡΠ΅Π»ΡΠ½ΡΡ
Π°ΠΏΠΏΠ°ΡΠ°ΡΠΎΠ² ΡΠ²Π»ΡΡΡΡΡ Π΄ΡΠΌΡ, ΠΈΡ
Π’Π-ΠΈΠ·ΠΎΠ±ΡΠ°ΠΆΠ΅Π½ΠΈΡ. This article analyzes the development process of the fire, which showed that a fire develops over seven stages, each of which corresponds to a set of phenomena (factors, signs) fire risk condition characterized by a set of defined parameters. It was shown that the decrease of the registered staging factor leads to the construction of fire preventive and diagnostic systems as recorded by the lower stage, the more uncertain the fact of its connection with the detection of a fire. It is indicated that the development of electronic equipment staging used for the detection of the factors fire situations, in general, is reduced, and also noted that for each control object is necessary to choose (identify) the optimal factor, in particular, in many ways the best factor for aircraft are smoke their TV picture
An unsupervised learning approach to identifying blocking events: the case of European summer
Atmospheric blocking events are mid-latitude weather patterns, which obstruct the usual path of the polar jet streams. They are often associated with heat waves in summer and cold snaps in winter. Despite being central features of mid-latitude synoptic-scale weather, there is no well-defined historical dataset of blocking events. Various blocking indices (BIs) have thus been suggested for automatically identifying blocking events in observational and in climate model data. However, BIs show significant regional and seasonal differences so that several indices are typically applied in combination to ensure scientific robustness. Here, we introduce a new BI using self-organizing maps (SOMs), an unsupervised machine learning approach, and compare its detection skill to some of the most widely applied BIs. To enable this intercomparison, we first create a new ground truth time series classification of European blocking based on expert judgement. We then demonstrate that our method (SOM-BI) has several key advantages over previous BIs because it exploits all of the spatial information provided in the input data and reduces the dependence on arbitrary thresholds. Using ERA5 reanalysis data (1979β2019), we find that the SOM-BI identifies blocking events with a higher precision and recall than other BIs. In particular, SOM-BI already performs well using only around 20 years of training data so that observational records are long enough to train our new method. We present case studies of the 2003 and 2019 European heat waves and highlight that well-defined groups of SOM nodes can be an effective tool to diagnose such weather events, although the domain-based approach can still lead to errors in the identification of certain events in a fashion similar to the other BIs. We further test the red blocking detection skill of SOM-BI depending on the meteorological variable used to study blocking, including geopotential height, sea level pressure and four variables related to potential vorticity, and the 500βhPa geopotential height anomaly field provides the best results with our new approach. We also demonstrate how SOM-BI can be used to identify different types of blocking events and their associated trends. Finally, we evaluate the SOM-BI performance on around 100 years of climate model data from a pre-industrial simulation with the new UK Earth System Model (UKESM1-0-LL). For the model data, all blocking detection methods have lower skill than for the ERA5 reanalysis, but SOM-BI performs noticeably better than the conventional indices. Overall, our results demonstrate the significant potential for unsupervised learning to complement the study of blocking events in both reanalysis and climate modelling contexts
Hibernation in pygmy lorises (Nycticebus pygmaeus)βwhat does it mean?
Torpor use in primates appeared to be restricted to African species and was only recently discovered in a species from Asia, the pygmy loris (Nycticebus pygmaeus). This finding has considerable implications for our perception of torpor in this mammal group and demonstrates that torpor is probably more widespread in mammals than commonly thought. This article summarizes the current knowledge on the use of torpor in the pygmy loris and places it into the context of ongoing research on this topic
Silver speciation and release in commercial antimicrobial textiles as influenced by washing
The use of nanoscale Ag in textiles is one the most often mentioned uses of nano-Ag. It has previously been shown that significant amounts of the Ag in the textiles are released upon washing. However, the form of Ag present in the textiles remains largely unknown as product labelling is insufficient. The aim of this study was therefore to investigate the solid phase speciation of Ag in original and washed silver textiles using XANES. The original Ag speciation in the textiles was found to vary greatly between different materials with Ag(0), AgCl, Ag2S, Agβphosphate, ionic Ag and other species identified. Furthermore, within the same textile a number of different species were found to coexist. This is likely due to a combination of factors such as the synthesis processes at industrial scale and the possible reaction of Ag with atmospheric gases. Washing with two different detergents resulted in marked changes in Ag-speciation. For some textiles the two detergents induced similar transformation, in other textiles they resulted in very different Ag species. This study demonstrates that in functional Ag textiles a variety of different Ag species coexist before and after washing. These results have important implications for the risk assessment of Ag textiles because they show that the metallic Ag is only one of the many silver species that need to be considered
Detection of Orbital Fluctuations Above the Structural Transition Temperature in the Iron-Pnictides and Chalcogenides
We use point contact spectroscopy to probe () and . For we detect orbital
fluctuations above while for AE=Ca these fluctuations start below .
Co doping preserves the orbital fluctuations while K doping suppresses it. The
fluctuations are only seen at those dopings and temperatures where an in-plane
resistive anisotropy is known to exist. We predict an in-plane resistive
anisotropy of above . Our data are examined in light of
the recent work by W.-C. Lee and P. Phillips (arXiv:1110.5917v2). We also study
how joule heating in the PCS junctions impacts the spectra. Spectroscopic
information is only obtained from those PCS junctions that are free of heating
effects while those PCS junctions that are in the thermal regime display bulk
resistivity phenomenon.Comment: Accepted for publication in Physical Review
Point-contact spectroscopy on URuSi
Tunnel and point contact experiments have been made in a URuSi single
crystal along the c-axis. The experiments were performed changing temperature
and contact size in a low temperature scanning tunneling microscope. A
resonance develops at the Fermi level at K. This resonance splits
and becomes asymmetric when the 17.5 K phase transition is crossed. These
results are consistent with the existence of Kondo like bound states of the
U ionic configurations and the conduction electrons. Below the
transition, these configurations are split by the development of quadrupolar
ordering. The peak separation can be interpreted as a direct measurement of the
order parameter. Measurements on a policrystalline UAu_2Si_2$ sample are also
reported, with a comparative study of the behavior of both materials.Comment: 4 pages (Latex) + 2 postscript figure
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