Nonlinear excitations in CsNiF3 in magnetic fields perpendicular to the easy plane

Experimental and numerical studies of the magnetic field dependence of the specific heat and magnetization of single crystals of CsNiF3 have been performed at 2.4 K, 2.9 K, and 4.2 K in magnetic fields up to 9 T oriented perpendicular to the easy plane. The experimental results confirm the presence of the theoretically predicted double peak structure in the specific heat arising from the formation of nonlinear spin modes. The demagnetizing effects are found to be negligible, and the overall agreement between the data and numerical predictions is better than reported for the case when the magnetic field was oriented in the easy plane. Demagnetizing effects might play a role in generating the difference observed between theory and experiment in previous work analyzing the excess specific heat using the sine-Gordon model.Comment: 6 pages, 5 figures, submitted to Phys. Rev.

Geographical and temporal distribution of SARS-CoV-2 clades in the WHO European Region, January to June 2020

We show the distribution of SARS-CoV-2 genetic clades over time and between countries and outline potential genomic surveillance objectives. We applied three available genomic nomenclature systems for SARS-CoV-2 to all sequence data from the WHO European Region available during the COVID-19 pandemic until 10 July 2020. We highlight the importance of real-time sequencing and data dissemination in a pandemic situation. We provide a comparison of the nomenclatures and lay a foundation for future European genomic surveillance of SARS-CoV-2.Peer reviewe

The Cholecystectomy As A Day Case (CAAD) Score: A Validated Score of Preoperative Predictors of Successful Day-Case Cholecystectomy Using the CholeS Data Set

Background Day-case surgery is associated with significant patient and cost benefits. However, only 43% of cholecystectomy patients are discharged home the same day. One hypothesis is day-case cholecystectomy rates, defined as patients discharged the same day as their operation, may be improved by better assessment of patients using standard preoperative variables. Methods Data were extracted from a prospectively collected data set of cholecystectomy patients from 166 UK and Irish hospitals (CholeS). Cholecystectomies performed as elective procedures were divided into main (75%) and validation (25%) data sets. Preoperative predictors were identified, and a risk score of failed day case was devised using multivariate logistic regression. Receiver operating curve analysis was used to validate the score in the validation data set. Results Of the 7426 elective cholecystectomies performed, 49% of these were discharged home the same day. Same-day discharge following cholecystectomy was less likely with older patients (OR 0.18, 95% CI 0.15–0.23), higher ASA scores (OR 0.19, 95% CI 0.15–0.23), complicated cholelithiasis (OR 0.38, 95% CI 0.31 to 0.48), male gender (OR 0.66, 95% CI 0.58–0.74), previous acute gallstone-related admissions (OR 0.54, 95% CI 0.48–0.60) and preoperative endoscopic intervention (OR 0.40, 95% CI 0.34–0.47). The CAAD score was developed using these variables. When applied to the validation subgroup, a CAAD score of ≤5 was associated with 80.8% successful day-case cholecystectomy compared with 19.2% associated with a CAAD score >5 (p < 0.001). Conclusions The CAAD score which utilises data readily available from clinic letters and electronic sources can predict same-day discharges following cholecystectomy

The evolving SARS-CoV-2 epidemic in Africa: Insights from rapidly expanding genomic surveillance

INTRODUCTION Investment in Africa over the past year with regard to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sequencing has led to a massive increase in the number of sequences, which, to date, exceeds 100,000 sequences generated to track the pandemic on the continent. These sequences have profoundly affected how public health officials in Africa have navigated the COVID-19 pandemic. RATIONALE We demonstrate how the first 100,000 SARS-CoV-2 sequences from Africa have helped monitor the epidemic on the continent, how genomic surveillance expanded over the course of the pandemic, and how we adapted our sequencing methods to deal with an evolving virus. Finally, we also examine how viral lineages have spread across the continent in a phylogeographic framework to gain insights into the underlying temporal and spatial transmission dynamics for several variants of concern (VOCs). RESULTS Our results indicate that the number of countries in Africa that can sequence the virus within their own borders is growing and that this is coupled with a shorter turnaround time from the time of sampling to sequence submission. Ongoing evolution necessitated the continual updating of primer sets, and, as a result, eight primer sets were designed in tandem with viral evolution and used to ensure effective sequencing of the virus. The pandemic unfolded through multiple waves of infection that were each driven by distinct genetic lineages, with B.1-like ancestral strains associated with the first pandemic wave of infections in 2020. Successive waves on the continent were fueled by different VOCs, with Alpha and Beta cocirculating in distinct spatial patterns during the second wave and Delta and Omicron affecting the whole continent during the third and fourth waves, respectively. Phylogeographic reconstruction points toward distinct differences in viral importation and exportation patterns associated with the Alpha, Beta, Delta, and Omicron variants and subvariants, when considering both Africa versus the rest of the world and viral dissemination within the continent. Our epidemiological and phylogenetic inferences therefore underscore the heterogeneous nature of the pandemic on the continent and highlight key insights and challenges, for instance, recognizing the limitations of low testing proportions. We also highlight the early warning capacity that genomic surveillance in Africa has had for the rest of the world with the detection of new lineages and variants, the most recent being the characterization of various Omicron subvariants. CONCLUSION Sustained investment for diagnostics and genomic surveillance in Africa is needed as the virus continues to evolve. This is important not only to help combat SARS-CoV-2 on the continent but also because it can be used as a platform to help address the many emerging and reemerging infectious disease threats in Africa. In particular, capacity building for local sequencing within countries or within the continent should be prioritized because this is generally associated with shorter turnaround times, providing the most benefit to local public health authorities tasked with pandemic response and mitigation and allowing for the fastest reaction to localized outbreaks. These investments are crucial for pandemic preparedness and response and will serve the health of the continent well into the 21st century

Characterising activities of free-ranging Merino ewes before, during and after lambing from GNSS data

Tracking the movement of grazing Merino ewes using Global Navigational Satellite Systems (GNSS) provided data which could be used to determine the behavioural characteristics exhibited during different physiological states and times-within-day. GNSS location and the resulting movement calculations from five foraging Merino ewes of known lambing date were partitioned into four different 24 h physiological states (PS): (1) seven days before lambing (L − 7), (2) day of lambing (L), (3) three days after lambing (L + 3) and (4) seven days after lambing (L + 7). Within each of these four PS the data were further partitioned into three time-within-day (TWD) intervals based on behavioural patterns: (1) 0500 to 1159 h morning foraging; (2) 1200 to 1859 h afternoon foraging and (3) 1900 to 0459 h night camping. Ewe locations were recorded at 10 min intervals over a 43 day period. Distances moved (m) and rates of travel (m/s) were analysed to characterise free-ranging ewe spatio-temporal activities within the four PS and three TWD periods. Physiological state and TWD had significant (P < 0.001) effects on mean distance moved by ewes but there was no two-way interaction (P > 0.05). Ewe rate of travel was significantly (P < 0.001) affected by PS and TWD and there was a significant (P < 0.01) two-way interaction. Ewes at L spent 13.2% less time foraging than ewes in other PS (mean 53.2%), while time spent in stationary behaviour accounted for 59.5% and ewes in other PS spent a mean of 45.2% of their time stationary. Distance moved and rate of travel during foraging were significantly (P < 0.001) affected by PS and TWD. GNSS collars were satisfactory to characterise behaviour of foraging Merino ewes at different PS and TWD. However, using ewe behaviour alone to identify when lambing occurs may not be a satisfactory husbandry option

GPS tracking of sheep to investigate shelter and shade use in relation to weather conditions

In Australia inclement weather contributes to losses of new-born lambs and recently-shorn sheep. Provision of forced shelter has been observed to reduce lamb losses by up to 10 percent and when given a choice, ewes preferentially seek shelter on offer for a period of approximately two weeks post shearing (Alexander et al. 1980). Given significant sheep losses can occur during adverse weather conditions a better understanding of sheep use of shelter and/or alternative ways of attracting sheep to shelter are needed. \ud \ud This paper reports on the results of deploying GPS collars on sheep on a commercial property in the Northern Tablelands region of NSW Australia, (latitude: 30.99°S, longitude: 151.59°E, elevation: 1060-1151 m MSL) with the aim of understanding the relationship between local climate and topography and sheep preference for shelter during pregnancy. In this work, two 20+ ha field designs were evaluated. Field A comprised of perimeter shelter belts (3-4 rows of native trees) and individual, free-standing trees (lone trees) within the field. Three classes of shelter; "Lone Trees", "Exterior Shelter" and "Remainder of Paddock" were ascribed to this field. Field B comprised of perimeter shelter belts, a single, internal shelter belt ("boomerang" shape) and a number of free-standing trees. Four shelter classes; "Lone Trees", "Interior Shelter", "Exterior Shelter" and "Remainder of Paddock" were ascribed to this field. Over two shearing and lambing seasons a random sample of 5 ewes from each of the two flocks of 200-300 ewes (ranging from 2 to 5 years of age) were fitted with GPS collars providing continuous (43-51 days) observations of the ewes‟ movement and proximity to shelter in spring (September and October). GPS collars recorded individual animal location every 10 minutes. Weather stations and temperature loggers were strategically located throughout the fields to provide localized hourly measures of temperature, wind speed and precipitation during the two observation periods. Daily minimum and maximum temperature ranged between -6 and 27°C respectively. Nights were generally still and frost was common, days were often sunny and windy; hourly wind speed reached a mean maximum of 49.6 km per hour. Strong westerly winds prevailed; northerly and southerly winds were unusual. The mean annual rainfall for the two years was 724.8 to 795.4 mm, mostly falling in the summer and winter months. The region experiences warm summers; rain and sleet are not uncommon in early spring, and winters occasionally have light snow and are cool enough to inhibit plant growth markedly for about 4 months. \ud \ud As field utilisation was similar each year, the decision was made to combine the data from both years for analysis. GPS records were converted into the spatially-based livestock residency index (LRI) (Trotter et al. 2010) and the proportion of residency times within a radius of 25 m of each shelter class was determined during 1900-0400h night camping; 0500-1100h morning grazing and 1200-1800h afternoon grazing time intervals (Figure 1). \ud \ud During night camping and where the choice of an internal shelter belt was provided (Field B), sheep were observed to spend more time in the vicinity (0-25m) of interior shelter belts (56%) than free-standing trees (12%). In Field A where only internal trees (43%) or perimeter shelter belts (40%) were available, a slight preference for the free-standing trees was observed. During daytime, shade-seeking behaviour indicated an increase in preference for individual, internal trees in both fields compared to night-time camping. Night camping also used interior shelter or free-standing trees which could be associated with predation prevention; however, the tree canopies would also reduce heat loss form radiation which may be of more importance to the sheep than wind protection provided by the exterior shelter belts. These results suggest sheep prefer to manoeuvre in and around shelter and freestanding trees provided within a field rather than huddle against exterior shelter belts provided along fence lines. The effects of local climatic temperature "extremes", wind direction, altitude and diurnal movements on daytime and night time preferences are also expected to play a role in the observed shelter-seeking behaviour and these data are currently being analysed

What can sheep teach us about shelter use?

Over many years there has been limited success in encouraging sheep to use shelter and a poor understanding of why they choose to use shelter the way they do. Have we misunderstood sheep use of shelter and if so are sheep sensible in their use of existing shelter based on climate and topography? The information gathered in this research should address this question and more. Over three lambing seasons a random sample of 5 ewes from each of the two flocks of 200-300 ewes were fitted with GPS collars. The GPS collars provided continuous (51 days) observation of the ewes movements and use of shelter in two paddocks with varying shelter designs on a commercial property on the Northern Tablelands, NSW. Weather stations and temperature loggers were strategically located throughout the paddock to provide localized measures of temperature, wind speed and precipitation that will be correlated to paddock and shelter use by the flocks. These data will give insight into sheep choice of shade and shelter use within a paddock relative to climatic conditions post shearing and during lambing. If sheep are reluctant to use perimeter shelter currently provided by producers, can they be encouraged or attracted to shelter during inclement weather? \ud \ud To determine if sheep could be trained to a visual and/or auditory stimulus that would attract them to shelter, forty-four fine wool Merino ewes were obtained at eight months of age, gentled, introduced to lupin grain and randomly dividing them into four groups (n=11): auditory, visual, visual+auditory and control (not trained). The ewes were trained in a 23.9 x 21.5 m outdoor arena to approach either the auditory, visual or visual+auditory stimulus for a food reward. After eight days of individual training the ewes were tested in a 'T' shaped maze without a food reward. The proportion of correct T-maze choices for each group was: auditory 36% (± SEM 0.08), visual 41% (± SEM 0.04) and visual+auditory 58% (± SEM 0.04). The ewes learned to approach the stimulus within 5-6 trials and demonstrated long-term memory retention for over 110 days without reinforcement. Training significantly improved the animal's ability to choose the stimulus. The controls received no training and made no choice during the 60 second T-maze test. The time taken by the trained animals to make a choice decreased as their proportion of correct choices increased (p<0.01, R2=0.75) suggesting memory assurance in making the choice. This study indicates sheep can be trained to approach a visual/auditory stimulus that could potentially be used to attract them to shelter. \ud \ud The next phase of our research will examine whether Merino synchronized following behaviour can improve the trained sheep's ability to lead a group of naive sheep to the stimulus. No published study has examined a means of attracting sheep to shelter as an alternative to forced shelter provision; or studied shelter use with GPS to understand their shelter selection criteria

GPS tracking: use of shelter and shade by Merino ewes

Information on the spatial distribution of ewes was obtained by deploying GPS collars on sheep on a commercial property on the Northern Tablelands of New South Wales. The aim of this study was to quantify the relationship between local weather, topography and use of shade and shelter by sheep in 2 paddocks of 20 ha. Paddock A was characterised by 3 distinct areas: "exterior shelter" consisting of perimeter shelter belts (3–4 rows of native trees), "lone trees" consisting of individual free-standing trees within the paddock, and "remainder of paddock". Paddock B contained areas that were categorised as for paddock A, plus an "interior shelter", a single, internal boomerang-shaped shelter belt. Over 2 lambing seasons (spring 2008 and 2009, 43–51 days), a random sample of 5 ewes from each of the 2 flocks of 200–300 ewes (2–5 years old and shorn 2 weeks prior to commencement of the experiment) were fitted with GPS collars set to log position every 10 min. Four weather stations and 55 temperature loggers were strategically located throughout the paddocks to provide localized hourly measurements of temperature, wind speed and precipitation over the observation periods. Daily temperatures ranged between –6 °C and 27 °C; nights were generally still and frost was common; days were often sunny and windy. Wind speed reached a mean maximum of 49.6 km/h. Strong westerly winds prevailed; northerly and southerly winds were unusual. The average rainfall during the observation period was 760 mm. \ud \ud As the number of times that sheep were detected in the various paddock categories was similar in each year, data for the 2 years were combined. The percentage of observations in which sheep were within 25 m of each shelter class was determined during 3 key phases of the diurnal behavioural cycle: 19:00–04:00 (night camping); 05:00–11:00 (morning grazing) and 12:00–18:00 (afternoon grazing). During night camping and when an internal shelter belt was provided (Paddock B), sheep spent more time in the vicinity (0–25 m) of the interior shelter belt (56%) than free-standing trees (12%). In Paddock A, which contained only free-standing trees (43%) or perimeter shelter belts (40%), the difference between the times spent in these areas was not significant. During daylight, shade-seeking behaviour indicated an increase in the use of free-standing trees in both paddocks. Interior shelter or free-standing trees were utilised during night camping, which may have occurred because tree canopies reduce heat loss via radiation. During the day, shade reduces radiation load, which may be of more importance to sheep than the wind protection provided by the exterior shelter belts. \ud \ud These results suggest that sheep prefer to manoeuvre in and around shelter and free-standing trees within a paddock rather than exterior shelter belts along fence lines. The effects of local weather temperature extremes, wind direction, altitude and diurnal movements on daytime and night-time preferences are currently being analysed