Seasonal temperature acclimatization in a semi-fossorial mammal and the role of burrows as thermal refuges.

Small mammals in habitats with strong seasonal variation in the thermal environment often exhibit physiological and behavioral adaptations for coping with thermal extremes and reducing thermoregulatory costs. Burrows are especially important for providing thermal refuge when above-ground temperatures require high regulatory costs (e.g., water or energy) or exceed the physiological tolerances of an organism. Our objective was to explore the role of burrows as thermal refuges for a small endotherm, the pygmy rabbit (Brachylagus idahoensis), during the summer and winter by quantifying energetic costs associated with resting above and below ground. We used indirect calorimetry to determine the relationship between energy expenditure and ambient temperature over a range of temperatures that pygmy rabbits experience in their natural habitat. We also measured the temperature of above- and below-ground rest sites used by pygmy rabbits in eastern Idaho, USA, during summer and winter and estimated the seasonal thermoregulatory costs of resting in the two microsites. Although pygmy rabbits demonstrated seasonal physiological acclimatization, the burrow was an important thermal refuge, especially in winter. Thermoregulatory costs were lower inside the burrow than in above-ground rest sites for more than 50% of the winter season. In contrast, thermal heterogeneity provided by above-ground rest sites during summer reduced the role of burrows as a thermal refuge during all but the hottest periods of the afternoon. Our findings contribute to an understanding of the ecology of small mammals in seasonal environments and demonstrate the importance of burrows as thermal refuge for pygmy rabbits

Techniques to determine the quiet day curve for a long period of subionospheric VLF observations

Very low frequency (VLF) transmissions propagating between the conducting Earth's surface and lower edge of the ionosphere have been used for decades to study the effect of space weather events on the upper atmosphere. The VLF response to these events can only be quantified by comparison of the observed signal to the estimated quiet time or undisturbed signal levels, known as the quiet day curve (QDC). A common QDC calculation approach for periods of investigation of up to several weeks is to use observations made on quiet days close to the days of interest. This approach is invalid when conditions are not quiet around the days of interest. Longer-term QDCs have also been created from specifically identified quiet days within the period and knowledge of propagation characteristics. This approach is time consuming and can be subjective. We present three algorithmic techniques, which are based on either (1) a mean of previous days' observations, (2) principal component analysis, or (3) the fast Fourier transform (FFT), to calculate the QDC for a long-period VLF data set without identification of specific quiet days as a basis. We demonstrate the effectiveness of the techniques at identifying the true QDCs of synthetic data sets created to mimic patterns seen in actual VLF data including responses to space weather events. We find that the most successful technique is to use a smoothing method, developed within the study, on the data set and then use the developed FFT algorithm. This technique is then applied to multiyear data sets of actual VLF observations

Depletion forces near curved surfaces

Based on density functional theory the influence of curvature on the depletion potential of a single big hard sphere immersed in a fluid of small hard spheres with packing fraction \eta_s either inside or outside of a hard spherical cavity of radius R_c is calculated. The relevant features of this potential are analyzed as function of \eta_s and R_c. There is a very slow convergence towards the flat wall limit R_c \to \infty. Our results allow us to discuss the strength of depletion forces acting near membranes both in normal and lateral directions and to make contact with recent experimental results

Performing heritage: the use of live 'actors' in heritage presentations

This paper investigates the phenomenon of 'living history' presentations of heritage, using live 'actors' to portray historical characters. Its aim is to discuss these presentations in the context of what may be understood as 'heritage', and of the nature of 'performance'. Four case studies of heritage sites, each important as a tourist attraction, have been selected for detailed study, together with a number of other examples of heritage performance. It is clear from the empirical work that different performance strategies are employed within the heritage industry and by individual 'actors'. Most of the performers take part as a leisure activity, and many do not consider themselves to be 'performing' at all. The greatest concern of participants lies in the degree of authenticity of the performance. Through 'living history', the 'actors' are drawn into an experience of heritage which has real meaning for them, and which may contribute both to a sense of identity and to an enhanced understanding of society, past and present. The popularity of such presentations with visitors also indicates that similar benefits are perceived by the 'audience'

Effect of EMIC waves on relativistic and ultrarelativistic electron populations: Ground-based and Van Allen Probes observations

Abstract We study the effect of electromagnetic ion cyclotron (EMIC) waves on the loss and pitch angle scattering of relativistic and ultrarelativistic electrons during the recovery phase of a moderate geomagnetic storm on 11 October 2012. The EMIC wave activity was observed in situ on the Van Allen Probes and conjugately on the ground across the Canadian Array for Real-time Investigations of Magnetic Activity throughout an extended 18 h interval. However, neither enhanced precipitation of \u3e0.7 MeV electrons nor reductions in Van Allen Probe 90° pitch angle ultrarelativistic electron flux were observed. Computed radiation belt electron pitch angle diffusion rates demonstrate that rapid pitch angle diffusion is confined to low pitch angles and cannot reach 90°. For the first time, from both observational and modeling perspectives, we show evidence of EMIC waves triggering ultrarelativistic (~2-8 MeV) electron loss but which is confined to pitch angles below around 45° and not affecting the core distribution. Key Points EMIC wave activity is not associated with precipitation of MeV electrons EMIC waves do not deplete the ultra-relativistic belt down to 90° EMIC waves cause loss of low pitch angle electrons with energies ~2-8 MeV

Alopecia areata is characterized by dysregulation in systemic type 17 and type 2 cytokines, which may contribute to disease‐associated psychological morbidity

Background: Alopecia areata (AA) is a common autoimmune disease, causing patchy hair loss that can progress to involve the entire scalp (totalis) or body (universalis). CD8+NKG2D+ T cells dominate hair follicle pathogenesis, but the specific mechanisms driving hair loss are not fully understood. Objectives To provide a detailed insight into the systemic cytokine signature associated with AA, and assess the association between cytokines and depression. Methods: Multiplex analysis of plasma cytokines from AA patients, psoriatic arthritis (PsA) patients and healthy controls. We also assessed incidence of depression and anxiety using the Hospital Anxiety and Depression Scale. Results: Our analysis identified a systemic inflammatory signature associated with AA, characterised by elevated levels of IL-17A, IL-17F, IL-21 and IL-23 indicative of a type 17 immune response. Circulating levels of the type 2 cytokines IL-33, IL-31 and IL-17E/25 are also significantly increased in AA. In comparison to PsA, AA was associated with higher levels of IL-17F, IL-17E and IL-23. We hypothesised that circulating inflammatory cytokines may contribute to wider comorbidities associated with AA. We assessed psychiatric comorbidity in AA using the Hospital Anxiety and Depression Scale and found that 18% and 51% of people with AA experienced symptoms of depression and anxiety, respectively. Using linear regression modelling, we identified that levels of IL-22 and IL-17E are positively and significantly associated with depression. Conclusion: Our data highlight changes in both type 17 and 2 cytokines, suggesting that complex systemic cytokine profiles may contribute both to the pathogenesis of AA and to the associated depression