Shape2SAS -- a web application to simulate small-angle scattering data and pair distance distributions from user-defined shapes

Shape2SAS is a web application that allows researchers and students to build intuition and understanding of small-angle scattering. It is available at https://somo.chem.utk.edu/shape2sas. The user defines a model of arbitrary shape by combining geometrical subunits, and Shape2SAS then calculates and displays the scattering intensity, the pair distance distribution as well as a visualization of the user-defined shape. Simulated data with realistic noise are also generated. We demonstrate how Shape2SAS can calculate and display the different scattering patterns for various geometrical shapes, such as spheres and cylinders. We also demonstrate how the effect of structure factors can be visualized. Finally, we show how multi-contrast particles can readily be generated, and how the calculated scattering may be used to validate and visualize analytical models generated in analysis software for fitting small-angle scattering data

Ising magnetism and ferroelectricity in Ca3_3CoMnO6_6

The origin of both the Ising chain magnetism and ferroelectricity in Ca$_3$CoMnO$_6$ is studied by $ab$ $initio$ electronic structure calculations and x-ray absorption spectroscopy. We find that Ca$_3$CoMnO$_6$ has the alternate trigonal prismatic Co$^{2+}$ and octahedral Mn$^{4+}$ sites in the spin chain. Both the Co$^{2+}$ and Mn$^{4+}$ are in the high spin state. In addition, the Co$^{2+}$ has a huge orbital moment of 1.7 $\mu_B$ which is responsible for the significant Ising magnetism. The centrosymmetric crystal structure known so far is calculated to be unstable with respect to exchange striction in the experimentally observed $\uparrow\uparrow\downarrow\downarrow$ antiferromagnetic structure for the Ising chain. The calculated inequivalence of the Co-Mn distances accounts for the ferroelectricity.Comment: 4 pages, 3 figures, PRL in press (changes made upon referees comments

Morphometric analysis of the canal system of cortical bone: an experimental study in the rabbit femur carried out with standard histology and micro-CT

The osteonal pattern of cortical bone is gradually built around the intracortical vessels by the progression of the cutting cones (secondary remodelling); therefore, the central canal size can be used as index of the remodelling activity. An experimental model in the rabbit femur was used to investigate, through central canal morphometry and frequency distribution analysis, the remodelling activity, comparing the middle of the diaphysis (mid-shaft) with the extremity (distal-shaft) and at the same level sectors and layers of the cortex in transversal sections. The study documented a higher density of canals in the mid-shaft than in the distal-shaft and a higher remodelling in the distal-shaft. There were no significant differences between dorsal, ventral, medial and lateral sectors at both midshaft and distal-shaft levels, while the number of canals was higher in the sub-periosteal layers than in the sub-endosteal. A lower threshold of 40 lm2 was observed in the central canal area. Sealed osteons in the midshaft were 22.43% of the total number of osteons of the central canal area between 40 and 200 lm2 and 0.44% of those of the distal-shaft. Micro-CT allowed a 3D reconstruction of the vascular canal system, which confirmed the branched network pattern rather than the trim architecture of the traditional representation. Some aspects like the lower threshold of the central canal size and the sealed osteons documented the plasticity of the system and its capacity for adaptation to changes in the haemodynamic conditions

Admission to hospital following head injury in England: Incidence and socio-economic associations

BACKGROUND: Head injury in England is common. Evidence suggests that socio-economic factors may cause variation in incidence, and this variation may affect planning for services to meet the needs of those who have sustained a head injury. METHODS: Socio-economic data were obtained from the UK Office for National Statistics and merged with Hospital Episodes Statistics obtained from the Department of Health. All patients admitted for head injury with ICD-10 codes S00.0–S09.9 during 2001–2 and 2002–3 were included and collated at the level of the extant Health Authorities (HA) for 2002, and Primary Care Trust (PCT) for 2003. Incidence was determined, and cluster analysis and multiple regression analysis were used to look at patterns and associations. Results: 112,718 patients were admitted during 2001–2 giving a hospitalised incidence rate for England of 229 per 100,000. This rate varied across the English HA's ranging from 91–419 per 100,000. The rate remained unchanged for 2002–3 with a similar magnitude of variation across PCT's. Three clusters of HA's were identified from the 2001–2 data; those typical of London, those of the Shire counties, and those of Other Urban authorities. Socio-economic factors were found to account for a high proportion of the variance in incidence for 2001–2. The same pattern emerged for 2002–3 at the PCT level. The use of public transport for travel to work is associated with a decreased incidence and lifestyle indicators, such as the numbers of young unemployed, increase the incidence. CONCLUSION: Head injury incidence in England varies by a factor of 4.6 across HA's and PCT's. Planning head injury related services at the local level thus needs to be based on local incidence figures rather than regional or national estimates. Socio-economic factors are shown to be associated with admission, including travel to work patterns and lifestyle indicators, which suggests that incidence is amenable to policy initiatives at the macro level as well as preventive programmes targeted at key groups

The presence of protease activity in the rectal fluid of attine ants

The rectal fluid of twenty-two species of ants, including seven species of Attini, seven species of non-attine Myrmicinae, and eight species of Formicinae was assayed for proteolytic enzyme activity. Significant activity was present in the rectal fluid of all of the attines and only in the attines. Some implications of these results are discussed.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/32816/1/0000190.pd

Impact of a drought on nutrient concentrations in the Lower Lakes (Murray Darling Basin, Australia)

Nutrient concentrations increased in 2 lakes (Lake Alexandrina and Lake Albert) located at the downstream end of the Murray Darling Basin, Australia, as a result of water level drawdown and salinisation associated with a severe drought. Between January 2007 and March 2008 the salinity difference between the inlet and outlets (5 barrages) increased from 0.9 to 21.0 g L-1, resulting primarily from seawater leakage through the barrages. Subsequently, in relatively sheltered areas upstream of the barrages, permanent salinity-derived density stratification developed, leading to the development of an anoxic hypolimnion. This seemingly favoured the regeneration of dissolved nutrients from the sediments, with standing stocks of ammonium and filterable reactive phosphorus increasing by 250 and 142%, respectively. However, the source of leakage water through the barrages also contributed to the increase. While dissolved organic carbon concentrations also increased, this was a result of evapoconcentration because calculated standing stocks changed little during the study period. In the open water areas, vertical density stratification was not evident, but sediment resuspension seemed to increase during the drawdown. Total organic nitrogen and total phosphorus concentrations were closely related to light attenuation, suggesting increased resuspension of particulate nutrients during the water level drawdown or increased assimilation of dissolved nutrients by phytoplankton. Overall, sediment resuspension seemed to have had a greater impact on nutrient concentrations in open water areas of Lake Alexandrina and Lake Albert, while saline intrusions were more significant in relatively sheltered areas located close to the lake outlets