85 research outputs found
Low-temperature structural investigations of the frustrated quantum antiferromagnets Cs2CuCl(4-x)Br(x)
Powder X-ray diffraction (PXRD) and single-crystal neutron scattering were
used to study in detail the structural properties of the Cs2CuCl(4-x)Br(x)
series, good realizations of layered triangular antiferromagnets. Detailed
temperature-dependent PXRD reveal a pronounced anisotropy of the thermal
expansion for the three different crystal directions of the orthorhombic
structure without any structural phase transition down to 20 K. Remarkably, the
anisotropy of the thermal expansion varies for different , leading to
distinct changes of the geometry of the local Cu environment as a function of
temperature and composition. The refinement of the atomic positions confirms
that for x=1 and 2, the Br atoms occupy distinct halogen sites in the
[CuX4]-tetrahedra (X = Cl, Br). The precise structure data are used to
calculate the magnetic exchange couplings using density functional methods for
x=0. We observe a pronounced temperature dependence of the calculated magnetic
exchange couplings, reflected in the strong sensitivity of the magnetic
exchange couplings on structural details. These calculations are in good
agreement with the experimentally established values for Cs2CuCl4 if one takes
the low-temperature structure data as a starting point
Structural Insights into Recognition of MDC1 by TopBP1 in DNA Replication Checkpoint Control
SummaryActivation of the DNA replication checkpoint by the ATR kinase requires protein interactions mediated by the ATR-activating protein, TopBP1. Accumulation of TopBP1 at stalled replication forks requires the interaction of TopBP1 BRCT5 with the phosphorylated SDT repeats of the adaptor protein MDC1. Here, we present the X-ray crystal structures of the tandem BRCT4/5 domains of TopBP1 free and in complex with a MDC1 consensus pSDpT phosphopeptide. TopBP1 BRCT4/5 adopts a variant BRCT-BRCT packing interface and recognizes its target peptide in a manner distinct from that observed in previous tandem BRCT- peptide structures. The phosphate-binding pocket and positively charged residues in a variant loop in BRCT5 present an extended binding surface for the negatively charged MDC1 phosphopeptide. Mutations in this surface reduce binding affinity and recruitment of TopBP1 to ÎłH2AX foci in cells. These studies reveal a different mode of phosphopeptide binding by BRCT domains in the DNA damage response
Feeding of the probiotic bacterium Enterococcus faecium NCIMB 10415 differentially affects shedding of enteric viruses in pigs
Effects of probiotic bacteria on viral infections have been described
previously. Here, two groups of sows and their piglets were fed with or
without feed supplementation of the probiotic bacterium Enterococcus faecium
NCIMB 10415. Shedding of enteric viruses naturally occurring in these pigs was
analyzed by quantitative real-time RT-PCR. No differences between the groups
were recorded for hepatitis E virus, encephalomyocarditis virus and norovirus.
In contrast, astrovirus was exclusively detected in the non-supplemented
control group. Rotavirus was shedded later and with lower amounts in the
probiotic piglet group (p < 0.05); rotavirus-shedding piglets gained less
weight than non-infected animals (p < 0.05). Serum titres of anti-rotavirus
IgA and IgG antibodies were higher in piglets from the control group, whereas
no difference was detected between sow groups. Phenotype analysis of immune
cell antigens revealed significant differences of the CD4 and CD8β (p < 0.05)
as well as CD8α and CD25 (p < 0.1) T cell populations of the probiotic
supplemented group compared to the non-supplemented control group. In
addition, differences were evident for CD21/MHCII-positive (p < 0.05) and IgM-
positive (p < 0.1) B cell populations. The results indicate that probiotic
bacteria could have effects on virus shedding in naturally infected pigs,
which depend on the virus type. These effects seem to be caused by
immunological changes; however, the distinct mechanism of action remains to be
elucidated
Magic state distillation in all prime dimensions using quantum Reed-Muller codes
We propose families of protocols for magic state distillation -- important
components of fault tolerance schemes --- for systems of odd prime dimension.
Our protocols utilize quantum Reed-Muller codes with transversal non-Clifford
gates. We find that, in higher dimensions, small and effective codes can be
used that have no direct analogue in qubit (two-dimensional) systems. We
present several concrete protocols, including schemes for three-dimensional
(qutrit) and five-dimensional (ququint) systems. The five-dimensional protocol
is, by many measures, the best magic state distillation scheme yet discovered.
It excels both in terms of error threshold with respect to depolarising noise
(36.3%) and the efficiency measure know as "yield", where, for a large region
of parameters, it outperforms its qubit counterpart by many orders of
magnitude.Comment: Updated from V1 to include results on the remarkable d=5 cas
Crystal growth of copper-rich ytterbium compounds: The predicted giant unit cell structures YbCu4.4 and YbCu4.25
Two new phases YbCu4.4 and YbCu4.25 are found as a result of careful phase
diagram investigations. Between the congruent and peritectic formation of
YbCu4.5 and YbCu3.5, respectively, the phases YbCu4.4 and YbCu4.25 are formed
peritectically at 934(2)degC and 931(3)degC. Crystal growth was realised using
a Bridgman technique and single crystalline grains of about 50-100 10^{-6}m
were analyzed by electron diffraction and single crystal X-ray diffraction. Due
to the only slight differences in both compositions and formation temperatures
the growth of larger single crystals of a defined superstructure is
challenging. The compounds YbCu4.4 and YbCu4.25 fit in Cerny`s (J. Solid State
Chem. 174 (2003) 125) building principle {(RECu5)n(RECu2)} where RE = Yb with n
= 4 and 3. YbCu4.4 and YbCu4.25 base on AuBe5/MgCu2-type substructures and
contain approximately 4570 and 2780 atoms per unit cell. The new phases close
the gap in the series of known copper-rich rare earth compounds for n = 1, 2
(DyCu3.5, DyCu4.0) and n = 5 (YbCu4.5, DyCu4.5)
Less loop diuretic use in patients on sacubitril/valsartan undergoing remote pulmonary artery pressure monitoring
Aims
Control of pulmonary pressures monitored remotely reduced heart failure hospitalizations mainly by lowering filling pressures through the use of loop diuretics. Sacubitril/valsartan improves heart failure outcomes and increases the kidney sensitivity for diuretics. We explored whether sacubitril/valsartan is associated with less utilization of loop diuretics in patients guided with haemodynamic monitoring in the CardioMEMS European Monitoring Study for Heart Failure (MEMS-HF).
Methods and results
The MEMS-HF population (n = 239) was separated by the use of sacubitril/valsartan (n = 68) or no use of it (n = 164). Utilization of diuretics and their doses was prespecified in the protocol and was monitored in both groups. Multivariable regression, ANCOVA, and a generalized linear model were used to fit baseline covariates with furosemide equivalents and changes for 12 months. MEMS-HF participants (n = 239) were grouped in sacubitril/valsartan users [n = 68, 64 ± 11 years, left ventricular ejection fraction (LVEF) 25 ± 9%, cardiac index (CI) 1.89 ± 0.4 L/min/m2] vs. non-users (n = 164, 70 ± 10 years, LVEF 36 ± 16%, CI 2.11 ± 0.58 L/min/m2, P = 0.0002, P < 0.0001, and P = 0.0015, respectively). In contrast, mean pulmonary artery pressure (PAP) values were comparable between groups (29 ± 11 vs. 31 ± 11 mmHg, P = 0.127). Utilization of loop diuretics was lower in patients taking sacubitril/valsartan compared with those without (P = 0.01). Significant predictor of loop diuretic use was a history of renal failure (P = 0.005) but not age (P = 0.091). After subjects were stratified by sacubitril/valsartan or other diuretic use, PAP was nominally, but not significantly lower in sacubitril/valsartan-treated patients (baseline: P = 0.52; 6 months: P = 0.07; 12 months: P = 0.53), while there was no difference in outcome or PAP changes. This difference was observed despite lower CI (P = 0.0015). Comparable changes were not observed for other non-loop diuretics (P = 0.21).
Conclusions
In patients whose treatment was guided by remote PAP monitoring, concomitant use of sacubitril/valsartan was associated with reduced utilization of loop diuretics, which could potentially be relevant for outcomes
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