438 research outputs found
Differently Shaped Hard Body Colloids in Confinement: From passive to active particles
We review recent progress in the theoretical description of anisotropic hard
colloidal particles. The shapes considered range from rods and dumbbells to
rounded cubes, polyhedra and to biaxial particles with arbitrary shape. Our
focus is on both static and dynamical density functional theory and on computer
simulations. We describe recent results for the structure, dynamics and phase
behaviour in the bulk and in various confining geometries, e.g. established by
two parallel walls which reduce the dimensionality of the system to two
dimensions. We also include recent theoretical modelling for active particles,
which are autonomously driven by some intrinsic motor, and highlight their
fascinating nonequilibrium dynamics and collective behaviour.Comment: 15 pages, 6 figures, EPJ ST (accepted
Tension and stiffness of the hard sphere crystal-fluid interface
A combination of fundamental measure density functional theory and Monte
Carlo computer simulation is used to determine the orientation-resolved
interfacial tension and stiffness for the equilibrium hard-sphere crystal-fluid
interface. Microscopic density functional theory is in quantitative agreement
with simulations and predicts a tension of 0.66 kT/\sigma^2 with a small
anisotropy of about 0.025 kT and stiffnesses with e.g. 0.53 kT/\sigma^2 for the
(001) orientation and 1.03 kT/\sigma^2 for the (111) orientation. Here kT is
denoting the thermal energy and \sigma the hard sphere diameter. We compare our
results with existing experimental findings
Free energies, vacancy concentrations and density distribution anisotropies in hard--sphere crystals: A combined density functional and simulation study
We perform a comparative study of the free energies and the density
distributions in hard sphere crystals using Monte Carlo simulations and density
functional theory (employing Fundamental Measure functionals). Using a recently
introduced technique (Schilling and Schmid, J. Chem. Phys 131, 231102 (2009))
we obtain crystal free energies to a high precision. The free energies from
Fundamental Measure theory are in good agreement with the simulation results
and demonstrate the applicability of these functionals to the treatment of
other problems involving crystallization. The agreement between FMT and
simulations on the level of the free energies is also reflected in the density
distributions around single lattice sites. Overall, the peak widths and
anisotropy signs for different lattice directions agree, however, it is found
that Fundamental Measure theory gives slightly narrower peaks with more
anisotropy than seen in the simulations. Among the three types of Fundamental
Measure functionals studied, only the White Bear II functional (Hansen-Goos and
Roth, J. Phys.: Condens. Matter 18, 8413 (2006)) exhibits sensible results for
the equilibrium vacancy concentration and a physical behavior of the chemical
potential in crystals constrained by a fixed vacancy concentration.Comment: 17 pages, submitted to Phys. Rev.
Thermodynamics of the frustrated one-dimensional spin-1/2 Heisenberg ferromagnet in a magnetic field
We calculate the low-temperature thermodynamic quantities (magnetization,
correlation functions, transverse and longitudinal correlation lengths, spin
susceptibility, and specific heat) of the frustrated one-dimensional spin-half
J1-J2 Heisenberg ferromagnet, i.e. for J2< 0.25|J1|, in an external magnetic
field using a second-order Green-function formalism and full diagonalization of
finite systems. We determine power-law relations for the field dependence of
the position and the height of the maximum of the uniform susceptibility.
Considering the specific heat at low magnetic fields, two maxima in its
temperature dependence are found.Comment: 9 pages, 9 figures, version as published in PR
Viral and Bacterial Pathogens in Bovine Respiratory Disease in Finland
Pathogens causing bovine respiratory tract disease in Finland were investigated. Eighteen cattle herds with bovine respiratory disease were included. Five diseased calves from each farm were chosen for closer examination and tracheobronchial lavage. Blood samples were taken from the calves at the time of the investigation and from 86 calves 3â4 weeks later. In addition, 6â10 blood samples from animals of different ages were collected from each herd, resulting in 169 samples. Serum samples were tested for antibodies to bovine parainfluenza virus-3 (PIV-3), bovine respiratory syncytial virus (BRSV), bovine coronavirus (BCV), bovine adenovirus-3 (BAV-3) and bovine adenovirus-7 (BAV-7). About one third of the samples were also tested for antibodies to bovine virus diarrhoea virus (BVDV) with negative results. Bacteria were cultured from lavage fluid and in vitro susceptibility to selected antimicrobials was tested. According to serological findings, PIV-3, BAV-7, BAV-3, BCV and BRSV are common pathogens in Finnish cattle with respiratory problems. A titre rise especially for BAV-7 and BAV-3, the dual growth of Mycoplasma dispar and Pasteurella multocida, were typical findings in diseased calves. Pasteurella sp. strains showed no resistance to tested antimicrobials. Mycoplasma bovis and Mannheimia haemolytica were not found
Comparison of Finnish meat inspection records and average daily gain for cattle herds differing in Mycoplasma bovis test-status
Detecting Mycoplasma bovis on cattle farms represents a challenge in the absence of an outbreak or cases of M. bovis mastitis, yet identification of an infection is essential to control the spread of the disease successfully. The objectives of this study were: (1) to determine whether meat inspection records can aid identification of cattle farms supporting M. bovis infection, and (2) to compare the average daily weight gain estimated from carcass weight for cattle originating from farms differing in M. bovis test-status. Meat inspection records were collected from two abattoirs in 2015; 80 677 animals in total. All the dairy and mixed breed cows and bulls used for meat production were categorized according to known M. bovis infection status of the farms from which the cattle were derived; positive, contact or control farms. The associations between animals from different M. bovis categories and lung lesions of bulls and cows (pneumonia and pleuritis), identified during meat inspection, and estimated average daily gain (ADG) of bulls, were investigated. The odds ratios for lung lesions, especially pleuritis, were higher in M. bovis test-positive or contact farms compared with control farms. Additionally, odds ratios for pleuritis were higher among animals from M. bovis test-positive farms and animals from contact slaughtering farms originating from M. bovis-free rearing farms. Bulls originating from M. bovis test-positive farms had higher estimated average daily gain than cattle from control farms. Meat inspection records can be used alongside other methods to detect M. bovis-positive farms where M. bovis causes lung lesions. (C) 2019 The Authors. Published by Elsevier Ltd.Peer reviewe
Developing critical analysis of explanations in physics teachers: Which direction to take?
International audienc
The current state of hospital-based emergency medicine in Germany
Germany has a long tradition of having physicians, often anesthesiologists with additional training in emergency medicine, deliver prehospital emergency care. Hospital-based emergency medicine in Germany also differs significantly from the Anglo-American model, and until recently having separate emergency rooms for different departments was the norm. In the past decade, many hospitals have created âcentralized emergency departmentsâ [Zentrale Notaufnahme (ZNAs)]. There is ongoing debate about the training and certification of physicians working in the ZNAs and whether Germany will adopt a specialty board certification for emergency medicine
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