Direct Numerical Simulation of decaying two-dimensional turbulence in a no-slip square box using Smoothed Particle Hydrodynamics

This paper explores the application of SPH to a Direct Numerical Simulation (DNS) of decaying turbulence in a two-dimensional no-slip wall-bounded domain. In this bounded domain, the inverse energy cascade, and a net torque exerted by the boundary, result in a spontaneous spin up of the fluid, leading to a typical end state of a large monopole vortex that fills the domain. The SPH simulations were compared against published results using a high accuracy pseudo-spectral code. Ensemble averages of the kinetic energy, enstrophy and average vortex wavenumber compared well against the pseudo-spectral results, as did the evolution of the total angular momentum of the fluid. However, while the pseudo-spectral results emphasised the importance of the no-slip boundaries as generators of long lived coherent vortices in the flow, no such generation was seen in the SPH results. Vorticity filaments produced at the boundary were always dissipated by the flow shortly after separating from the boundary layer. The kinetic energy spectrum of the SPH results was calculated using a SPH Fourier transform that operates directly on the disordered particles. The ensemble kinetic energy spectrum showed the expected k-3 scaling over most of the inertial range. However, the spectrum flattened at smaller length scales (initially less than 7.5 particle spacings and growing in size over time), indicating an excess of small-scale kinetic energy

Long-term Recovery from Acute Cold Shock in Caenorhabditis Elegans

Background Animals are exposed to a wide range of environmental stresses that can cause potentially fatal cellular damage. The ability to survive the period of stress as well as to repair any damage incurred is essential for fitness. Exposure to 2 °C for 24 h or longer is rapidly fatal to the nematode Caenorhabditis elegans, but the process of recovery from a shorter, initially non-lethal, cold shock is poorly understood. Results We report that cold shock of less than 12-hour duration does not initially kill C. elegans, but these worms experience a progression of devastating phenotypes over the next 96 h that correlate with their eventual fate: successful recovery from the cold shock and survival, or failure to recover and death. Cold-shocked worms experience a marked loss of pigmentation, decrease in the size of their intestine and gonads, and disruption to the vulva. Those worms who will successfully recover from the cold shock regain their pigmentation and much of the integrity of their intestine and gonads. Those who will die do so with a distinct phenotype from worms dying during or immediately following cold shock, suggesting independent mechanisms. Worms lacking the G-protein coupled receptor FSHR-1 are resistant to acute death from longer cold shocks, and are more successful in their recovery from shorter sub-lethal cold shocks. Conclusions We have defined two distinct phases of death associated with cold shock and described a progression of phenotypes that accompanies the course of recovery from that cold shock. The G-protein coupled receptor FSHR-1 antagonizes these novel processes of damage and recovery

Notes on plague, its epidemicity and prophylaxis

#1. The wide dissemination of Plague in India is attributable to the great facilities for and popularity of Railway travel. #2. A local outbreak is almost invariably traceable t. an imported case, and it is always preceded by an epizootic (among rats and chipmunks). #3. The interval between the discovery of the epigootic (i.e. the finding of dead rats) is regularly from 10 to 14 days. c.f. The Etiology and Epidemiology of Plague, 1908, p.21 1. #4. There is a general recognition by the mass of the people, even villagers, of the close connection between rat mortality and human plague. There is increasing willingness to evacuate houses earlier. #5. The effective management of plague epidemics, owi to the lethargy and prejudices of t.he people, is possible only in small communities. #6. The mode of building and the close proximity to each other of Indian houses favour the maintenance: of a large rat population, which is usually well fed owing to the very careless storage and handling of food stuffs, and the accumulation of rubbish in the houses. #7. Plague rarely attacks the young and old, while it incidence among the strong and healthy adult, male and female, is proverbial. #8. The infection is usually and markedly most virulent at the beginning of an outbreak, and there is a low case mortality at the end. #9. The infection of plague is frequently spread when people flee from an infected locality taking the bedding with them. #10. It is most conspicuous how seldom those in attendance on cases of plague (out of the surroundings in which the disease was contracted) themselves contract the disease. #11. The epidemicity of plague seems to be favoured by prevalence of conditions of scarcity or famine. #12. The breeding of rats is specially related to the hot season, when scarcity usually prevails, and there is always a relatively greater number of young and highly susceptible rats after a famine or scarcity. #13. A marked tendency of plague to recur in the same localities in successive outbreaks has been noticed. #14. Anti- plague inoculation with Haffkine's prophylacsic confers a very high degree of protection and immunity upon inoculated persons. The writer has net known of the occurrence in the same epidemic season of a single case of plague among over 1,000 'cases personally inoculated. The statistics of the outbreak in the 99th Native Infantry at Sehore show how high a degree of safety of life, i.e. hot great a reduction of mortality there is among those contracting plague even six months after being inoculated. Probably six months should be considered the outside period of the protectio resulting from inoculation. #15. Only cases of Bubonic Plague have been met with i the epidemics occurring under the writer's observation in the Districts, in Central India, and th Central Provinces, referred to. The occurrence of carbuncles has never been observed in these areas. #16. The symptoms of the earlier cases have been marked and classical, but cases near the cessation of the outbreak may be so mild as to go undetected - hen e possible inaccuracy of mortality statistics. #17. With the exception of the incision of bubos that have progressed to suppuration, and the application of Ac. Carbolic Pur. and Sp. Vin. Rect. tc them when evacuated, the treatment has been symptomatic, and chiefly directed to the avoidanc of heart failure. #18. Immediate evacuation of dwellings'', and, after sterilisation of bedding, etc., the resort to camps can be relied upon to reduce an outbreak to trivial proportions. This, however, is seldom attainable, and there is commonly a severe exacerbation through People returning too soon to their homes. On the outbreak of an epizootic and the finding dead rats, etc. #19. Anti- plague inoculation is not only a great individual safeguard, but it can be relied upon greatly to minimise the ravages of an incipient epidemic, if a sufficiently large proportion of the population, say not less than 500 and better 60 or upwards, is inoculated. #20. The destruction of rats on such a scale as to modify the epidemicity of plague,is not attainable in India because of the indifference of the people at non-epidemic seasons, when alone it is of value, and because of the Hindus religious objection to the taking of animal life. #21. Small and comparatively isolated communities can be guarded against outbreaks of plague by prompt and thorough measures in dealing with imported cases - i.e. by the effective inspection and taking the temperature for ten days of visitors and returning inhabitants from infected places, and the rigorous isolation in a segregation camp for ten days of suspects and contacts, and the treatment in a plague camp or Hospital of all cases. #22. Too great stress cannot be laid upon the value of popularising anti-plague inoculation, a practice attended with no ascertained injury to health,and the one effective personal or individual and communal safeguard. The methods assailable and effective for propaganda are: - (a) Civil surgeons and Medical Missionaries coming into personal contact with the common people and explaining the objects and results of inoculation (b) The granting of certificates of inoculation which lighten the restrictions upon residence and tray of people belonging to infected localities. (c) Legitimate pressure upon Government servants and employees to induce them to submit to inoculation - preferably in public. (d) Monetary rewards to those who are inoculated. (e) Widespread circulation of explanatory literature (e.g. specimens sent) giving details of the method and results, both in English and the vernaculars, to induce the educated classes to adopt and recommend thát safeguard, and to remove the prejudice of the masses. (f) The writer thinks that a properly trained staff of Subordinate European Inonulators, who would travel among the villages in the cool season, might do much to recommend and increase the adoption of the safeguard by the common people

Agricultural Aerosols: The Impact of Farming Activity on Ice Nucleating Particles

Farming activities cause particles such as soil dust and plant material to be emitted into the air. Some of these aerosols can become ice nucleating particles (INPs), serving as seeds for ice and mixed-phase clouds. While there have been ground-based studies of these particles in the western Great Plains and a single air-based study in Indiana, there is a distinct lack of ground-based studies in the Midwest. In Indiana, over two-thirds of the state is farmland, with over 75% of land in Tippecanoe County used for agriculture. Despite farming being such an essential part of life in Indiana, the connection between agricultural activities and INP concentrations in the area has not been explored. Using field observations taken at the Purdue Agronomy Center for Research and Education (ACRE), we hope to study the impact of harvesting on INP concentrations in the midwestern United States. The field experiment took place from May to December 2021 at the ACRE site, but this study focuses on three days during the harvesting period. Data was collected via two instruments: the SPectrometer for Ice Nuclei (SPIN) and the Cloud Condensation Nuclei Counter (CCNC). It appears there is an increase in INP concentrations on days when harvesting occurs, most likely due to an increase in organic and biological particles. It is hoped that the data from this project will provide further insight into the composition and number concentrations of INPs from harvesting through ground-based field observations, as well as insight into INP concentration in the rural Midwest and its climatic impacts