The upgraded Polaris powder diffractometer at the ISIS neutron source.

This paper describes the design and operation of the Polaris time-of-flight powder neutron diffractometer at the ISIS pulsed spallation neutron source, Rutherford Appleton Laboratory, UK. Following a major upgrade to the diffractometer in 2010-2011, its detector provision now comprises five large ZnS scintillator-based banks, covering an angular range of 6° ≤ 2θ ≤ 168°, with only minimal gaps between each bank. These detectors have a substantially increased solid angle coverage (Ω âˆ¼ 5.67 sr) compared to the previous instrument (Ω âˆ¼ 0.82 sr), resulting in increases in count rate of between 2× and 10×, depending on 2θ angle. The benefits arising from the high count rates achieved are illustrated using selected examples of experiments studying small sample volumes and performing rapid, time-resolved investigations. In addition, the enhanced capabilities of the diffractometer in the areas of in situ studies (which are facilitated by the installation of a novel design of radial collimator around the sample position and by a complementary programme of advanced sample environment developments) and in total scattering studies (to probe the nature of short-range atomic correlations within disordered crystalline solids) are demonstrated.

HLA class I variation in Iranian Lur and Kurd populations: high haplotype and allotype diversity with an abundance of KIR ligands.

HLA-A, -B and -C alleles of 285 individuals, representing three Iranian Lur populations and one Iranian Kurd population were sequenced completely, yielding human leukocyte antigen (HLA) class I genotypes at high resolution and filling four fields of the official HLA nomenclature. Each population has 87-99 alleles, evenly distributed between the three HLA class I genes, 145 alleles being identified in total. These alleles were already known, named and deposited in the HLA database. The alleles form 316 different HLA A-B-C haplotypes, with each population having between 80 and 112 haplotypes. The four Iranian populations form a related group that is distinguished from other populations, including other Iranians. All four KIR ligands - the A3/11, Bw4, C1 and C2 epitopes - are well represented, particularly Bw4, which is carried by three high-frequency allotypes: HLA-A*24:02, HLA-A*32:01 and HLA-B*51:01. In the Lur and Kurd populations, between 82% and 94% of individuals have the Bw4 epitope, the ligand for KIR3DL1. HLA-B*51:01 is likely of Neandertal origin and associated with Behcet's disease, also known as the Silk Road disease. The Lordegan Lur have the highest frequency of HLA-B*51:01 in the world. This allele is present on 46 Lur and Kurd haplotypes. Present at lower frequency is HLA-B*51:08, which is also associated with Behcet's disease. In the four Iranian populations, 31 haplotypes encode both Bw4(+) HLA-A and Bw4(+) HLA-B, a dual combination of Bw4 epitopes that is relatively rare in other populations, worldwide. This study both demonstrates and emphasizes the value of studying HLA class I polymorphism at highest resolution in anthropologically well-defined populations.

Neutron powder diffraction and molecular dynamics study of superionic SrBr2.

The nature of the dynamic ionic disorder within the high-temperature superionic phase of strontium bromide, ß-SrBr2, has been investigated using reverse Monte Carlo (RMC) modelling of neutron powder diffraction data and complementary ab initio molecular dynamics (MD) simulations. The RMC and MD results are in good agreement and indicate the presence of extensive dynamic disorder within the Br(-) sublattice of the cubic fluorite structure. Rapid anion diffusion predominantly occurs as hops between nearest neighbour sites in the 〈100〉 directions, though the trajectories are markedly curved and pass through the peripheries of the octahedral voids in the cation sublattice. In addition, there are extensive correlations between the motions of individual Br(-), often leading to the formation of a short-lived square antiprism co-ordination environment around the Sr(2+). Such polyhedra are observed within the (ambient temperature) ordered tetragonal crystal structure of α-SrBr2. The nature of the ionic disorder in SrBr2 is of particular interest because it is the only known example of a Br(-)-ion superionic. Owing to the large size of this anion, a comparison with the behaviour of other superionic phases gives an insight into the role of ionic size on the conducting properties within these materials.

Total scattering analysis of cation coordination and vacancy pair distribution in Yb substituted δ-Bi2O3.

Reverse Monte Carlo (RMC) modelling of neutron total scattering data, combined with conventional Rietveld analysis of x-ray and neutron data, has been used to describe the cation coordination environments and vacancy pair distribution in the oxide ion conducting electrolyte Bi3YbO6. The thermal variation of the cubic fluorite unit cell volume, monitored by variable temperature x-ray and neutron experiments, reveals significant curvature, which is explained by changes in the oxide ion distribution. There is a significant increase in tetrahedral oxide ion vacancy concentration relative to δ-Bi2O3, due to the creation of Frenkel defects associated with the Yb(3+) cation. The tetrahedral oxide ion vacancy concentration increases from room temperature to 800 °C, but little change is observed in the vacancy pair distribution with temperature. The vacancy pair distributions at both temperatures are consistent with a favouring of [100] vacancy pairs.

Serum chemistry values of free-ranging, lactating northern fur seals (Callorhinus ursinus).

Reference range clinical serum chemistry values were established for free-ranging lactating northern fur seals (Callorhinus ursinus). Fur seals sampled for this study were part of a healthy and growing population in the Kuril Islands of far-east Russia. Blood was collected from 45 females between June and August 2005 to 2007. Fresh serum was assayed for 16 components. Packed-cell volume was determined from fresh whole blood. Results are made available for future comparisons with the declining population of northern fur seals on the Pribilof Islands and are compared with published values for other otariid species.

Poststreptococcal dystonia with bilateral striatal enlargement: MR imaging and spectroscopic findings.

Isolated bilateral striatal necrosis is an abnormality of the basal ganglia associated with acute dystonia in children. This report describes the development of dystonic movements in a 7-year-old male patient 2 weeks after streptococcal pharyngitis.

Utilization of energy and amino acids of spray-dried egg, plasma protein, and soybean meal by ducks.

A study was conducted to determine AMEn, TMEn, apparent amino acid digestibility (AAAD), and true amino acid digestibility (TAAD) of spray-dried egg (SDE), plasma protein (PP), and soybean meal (SBM). AMEn and TMEn values for ducks fed SDE were higher (P < or = 0.001) than for ducks fed PP, which were higher than SBM. The AMEn values were 5.048, 3.230, and 2.605 kcal/g for SDE, PP, and SBM, respectively, with TMEn values of 5.373, 3.555, and 2.930 kcal/g, respectively. Spray-dried egg, PP, and SBM were similar in apparent digestibility of the indispensable amino acids except for methionine, histidine, and valine. Apparent methionine digestibility in SDE (95.5%) was higher (P < or = 0.01) than PP (88.3%) or SBM (91.3%). Apparent digestibilities of dispensable amino acids were similar for SDE, PP, and SBM except proline and alanine. Apparent alanine digestibility in SDE (89.9%) was higher (P < or = 0.05) than in SBM (85.7%). True digestibilities of indispensable amino acids were similar in SDE, PP, and SBM except for methionine, histidine, and valine. True methionine digestibility was higher (P < or = 0.05) for SDE (97.0%) than for PP (89.8%) or SBM (92.7%), with PP and SBM being similar. True histidine and valine digestibilities were significantly lower for SDE (P < or = 0.05) than for PP or SBM. True digestibilities of the dispensable amino acids were also similar in SDE, PP, and SBM except for proline and alanine. This study demonstrates that the energy value of SDE is greater than that of PP or SBM.

KSbO(Ge0.32Si0.68)O4, a KTP isomorph.

A structural model of potassium antimony germanate/silicate (0.32/0.68), KSbO(Ge(0.32)Si(0.68))O(4), has been determined at room temperature. KSbO(Ge(0.32)Si(0.68))O(4) belongs to the KTiOPO(4) (KTP) isomorphic family and is composed of SbO(6) octahedra (site symmetry -1 and 2) arranged in helical chains bridged by (Ge/Si)O(4) tetrahedra. Germanium and silicon have a similar distribution in the crystallographically independent tetrahedra (site symmetry 2). The structure contains large cavities occupied by the K atom. Two partially occupied potassium positions have been identified 1.273 (8) A apart, with an indication of a third potassium position between them. At room temperature, KSbO(Ge(0.32)Si(0.68))O(4) crystallizes in the paraelectric phase of space group Pnan. This phase is found at elevated temperatures for almost all KTiOPO(4) isomorphic compounds and KSbO(Ge(0.32)Si(0.68))O(4) is the second isomorph that is paraelectric at room temperature.

Extramedullary fixation of 569 unstable intertrochanteric fractures: a randomized multicenter trial of the Medoff sliding plate versus three other screw-plate systems.

We compared the efficacy of the Medoff sliding plate (MSP) with 3 other screw-plate systems for fixation of unstable intertrochanteric fractures in a randomized multicenter trial of 569 elderly patients. The MSP has biaxial dynamic capacity along both the neck and the shaft of the femur unlike the other systems, which lack dynamic capacity along the shaft. 268 fractures were operated on with the MSP, and 301 with the dynamic hip screw (DHS), with or without a trochanteric stabilizing plate (DHS/TSP) or with the dynamic condylar screw (DCS). The MSP had recently been shown to the surgeons. The patients in the groups were similar as regards age, domestic situation, preinjury walking ability and type of fracture. We followed the patients clinically and radiographically for at least 1 year. There was no significant difference in walking ability at follow-up or rate of return to home. Fixation failure occurred in 18/268 fractures operated on with the MSP, in 8/238 with the DHS, in 3/49 with the DHS/TSP and in 1/14 with the DCS. The difference in the rate of fixation failure was not statistically significant when the MSP group was compared to the 3 other groups. In 14 of the 18 fixation failures in the MSP group, the biaxial dynamic capacity of the MSP had not been used due to technical errors by surgeons, unfamiliar with the new method. No selection bias was found regarding fracture types in the 2 subgroups of patients with correct or inadequate biaxial dynamization. Extramedullary fixation of unstable intertrochanteric fractures with these implants showed a low failure rate. When using the MSP, biaxial dynamization must be correctly performed.

A TiP(2)O(7) superstructure.

A room-temperature structural model of titanium pyrophosphate, TiP(2)O(7), has been determined from synchrotron X-ray data. The structure consists of TiO(6) octahedra and PO(4) tetrahedra sharing corners in a three-dimensional network. The PO(4) tetrahedra form P(2)O(7) groups connecting the TiO(6) octahedra. The 3 x 3 x 3 superstructure differs substantially from the parent AB(2)O(7) structure. The P--O--P bonding angles of the pyrophosphate group are between 141.21 (12) and 144.51 (13) degrees for those groups not located on the threefold axis. The individual TiO(6) octahedra and PO(4) tetrahedra are somewhat distorted.

Crucial influence of solvent and chirality-the formation of helices and three-dimensional nets by hydrogen-bonded biimidazolate complexes.

Deprotonation and recrystallisation of racemic [Co(2,2'-biimidazole)3][NO3]3 by ammonia in water/dimethylformamide solutions gave crystals of [Co(Hbiim)3] x 0.8H2O x 0.5DMF (2: Hbiim = monoanion of 2,2'-biimidazole, DMF = dimethylformamide), a porous material that contains fourfold interpenetrating (10.3) three-dimensional nets formed by neutral, hydrogen-bonded [Co(Hbiim)3] units, with DMF molecules in the narrow channels. Recrystallisation of [delta-Co(2,2'-biimidazolate)3] gave helices instead of the expected (10,3)-a net. These results are discussed in the light of additional density functional theory and molecular mechanics calculations and the X-ray structure of [Co(H2biim)3][NO3]3.

Extramedullary fixation of 107 subtrochanteric fractures: a randomized multicenter trial of the Medoff sliding plate versus 3 other screw-plate systems.

We compared the efficacy of a load-sharing device, the Medoff sliding plate (MSP), with that of 3 other load-bearing screw-plate devices for the fixation of subtrochanteric fractures in a randomized multicenter trial of 107 elderly patients. 55 fractures were operated on with the MSP, and 52 with the dynamic hip screw (DHS) with or without a trochanteric stabilizing plate (TSP) or with the dynamic condylar screw (DCS). The patient material in the groups was similar regarding age, domestic situation, preinjury walking ability and fracture types. We followed the patients clinically and radiographically for a minimum of 1 year. There was no significant difference in walking ability or return rate to the home at follow-up. Fixation failure occurred in 1/55 fractures operated on with the MSP, in 3/32 with the DHS, in 3/12 with the DCS and in 2/8 with the DHS/TSR The difference in the rate of fixation failure was statistically significant, when the MSP group was compared to the 3 load-bearing devices in the other group (1 vs 8). On the basis of this experience, we think that the load-sharing principle of the MSP, which seems to facilitate fracture impaction and stability, appears to be a good alternative in extramedullary fixation of subtrochanteric fractures.

Intrauterine growth restriction is associated with a reduced activity of placental taurine transporters.

Taurine is an essential amino acid during fetal life and appears to be vital for the growth of the fetus and for the development of the CNS. In intrauterine growth restriction (IUGR), fetal plasma concentrations of taurine are reduced, and we tested the hypothesis that this is caused by altered placental transport of taurine. Syncytiotrophoblast microvillous membrane (MVM) and basal membrane (BM) vesicles were isolated from control (fetal weight, 3068+/-191 g; gestational age, 37.0+/-0.7 wk; n=13) and IUGR pregnancies (fetal weight, 1724+/-118 g; gestational age, 35.8+/-0.7 wk; n=11). Uptake of [3H]taurine (0.5 microM) was studied at 22 degrees C using rapid filtration techniques. Sodium stimulated taurine uptake 35-fold in MVM, confirming Na+-dependent transport in this membrane. A Na+-dependent taurine transport could also be demonstrated in BM; however, the activity was only 6% of that in MVM. Na+-independent transport activities were similar in MVM and BM. In IUGR, MVM Na+-dependent taurine transport was reduced by 34% (p < 0.05), whereas Na+-independent uptake was unaltered. In contrast to MVM, Na+-dependent taurine uptake in BM was unaffected by IUGR, whereas Na+-independent transport was decreased by 33% (p < 0.05). The highly polarized distribution of the Na+/taurine cotransporter to the MVM in conjunction with similar Na+-independent transport rates for taurine in MVM and BM provides the basis for net taurine flux from the mother to the fetus. These data suggest that the low plasma concentrations of taurine in IUGR fetuses are caused by a reduced activity of placental taurine transporters.

Air pollution involving nitrogen dioxide exposure and wheezing bronchitis in children.

BACKGROUND: A population-based case-control study was performed in Stockholm to assess the influence of air pollution on the occurrence of severe wheezing bronchitis in children. METHODS: The study included 197 children aged 4 months to 4 years, who were hospitalized because of breathing difficulties with wheezing, and 350 population controls. Information on potential risk factors for childhood wheezing and a residential history was obtained at home interview with parents. Outdoor nitrogen dioxide (NO2) concentrations at home addresses and day care centres from birth on were estimated from validated models, mainly using data on traffic intensity from municipal registers. RESULTS: The risk of wheezing bronchitis was related to time-weighted mean outdoor NO2 exposure in girls (P = 0.02), but not in boys. A gas stove in the home appeared to be a risk factor primarily for girls. All analyses controlled for parental asthma and maternal smoking, which were independent risk factors for wheezing bronchitis. CONCLUSIONS: The results suggest that exposure to combustion products containing NO2 may be of particular importance for the development of wheezing bronchitis in girls.

The stories of physicians, registered nurses and enrolled nurses about ethically difficult care episodes in surgical care.

Twenty physicians, 19 registered nurses (RN), and 20 enrolled nurses (EN) working in surgical care in Sweden narrated their experiences of being in ethically difficult care situations. All three professional groups disclosed a strong wish to help patients. The narrations of the physicians and the ENs indicated that they were very much involved in their patients, while most of the RNs' stories were narrated from a distanced onlooker's perspective and disclosed a lot of moral outrage, mainly directed towards physicians. The physicians were the only group that emphasized the importance of acting in accordance with science and proven experience. Like RNs they emphasized the importance and difficulty of telling the truth to the patients and their families and being open to one's own and others' harsh experiences. RNs and ENs emphasized the patient's right to a death with dignity and the difficulties connected with being with dying patients, and they also described feelings of powerlessness and neglect of patients related to a heavy work load. ENs narrated difficulties related to providing patients with individualized but fair care.