Energy scales in 4f1 delafossite magnets: crystal-field splittings larger than the strength of spin-orbit coupling in KCeO2

Ytterbium-based delafossites with effective S=1/2 moments are investigated intensively as candidates for quantum spin-liquid ground states. While the synthesis of related cerium compounds has also been reported,many important details concerning their crystal, electronic, and magnetic structures are unclear. Here we analyze the S=1/2 system KCeO2, combining complementary theoretical methods. The lattice geometry was optimized and the band structure investigated using density functional theory extended to the level of a GGA+U calculation in order to reproduce the correct insulating behavior. The Ce 4f1 states were then analyzed in more detail with the help of ab initio wave-function-based computations. Unusually large effective crystal-field splittings of up to 320 meV are predicted, which puts KCeO2 in the strong field coupling regime. Our results reveal a subtle interplay between ligand-cage electrostatics and the trigonal field generated by the extended crystalline surroundings, relevant in the context of recent studies on tuning the nature of the ground-state wave function in 4f triangular-lattice and pyrochlore compounds. It also makes KCeO2 an interesting model system in relation to the effect of large crystal-field splittings on the anisotropy of intersite exchange in spin-orbit coupled quantum magnets.Comment: 6 pages, 2 figures, and 3 table

Hypertension as the trigger for posterior reversible encephalopathy syndrome in paediatric renal patients: An important diagnosis that should not be missed

Background. Posterior reversible encephalopathy syndrome (PRES) is a reversible neurological condition presenting with seizures and visual disturbances and diagnosed on magnetic resonance imaging (MRI). Little is understood about its pathogenesis, particularly in children, but it is thought to be related to hypertension.Objectives. To review the presentation, diagnosis and outcome of PRES in paediatric renal patients at Chris Hani Baragwanath Academic Hospital, Johannesburg, South Africa, between 1 January 2000 and 31 January 2017 and compare these with published case reports to date.Methods. This was a retrospective analysis of five new cases and a review of the existing literature.Results. The five reported patients were all hypertensive at the time of diagnosis and presented with seizures. Most (91%) of the 64 reviewed patients were also hypertensive at initial presentation. All five of the reported and 91% of the reviewed patients presented with seizures. The most common pattern of change on MRI occurred in the parietal and occipital regions. Complete neurological recovery occurred in four of the five reported and 87.5% of the reviewed patients.Conclusion. All patients presented clinically with hypertensive crises and radiological evidence of PRES. Seizures were the most common presenting symptom. The prognosis for paediatric patients with PRES is favourable, so it is important to confirm the diagnosis in low-resource settings where intensive care is limited.

Posterior urethral valves in South African boys: Outcomes and challenges

Background. Posterior urethral valves (PUV) are a common cause of congenital obstructive nephropathy. The outcome of patients with PUV at Chris Hani Baragwanath Academic Hospital in Johannesburg, South Africa, has not been documented previously.Objectives. To describe the outcome of patients diagnosed with PUV over a 29-year period from January 1985 to December 2013, and to analyse risk factors for chronic kidney disease.Methods. This was a retrospective record review of boys aged <14 years diagnosed with PUV at Chris Hani Baragwanath Academic Hospital. PUV was diagnosed by a voiding cystourethrogram (VCUG) and/or at cystoscopy. Valves were resected primarily or after vesicostomy. The glomerular filtration rate was calculated using the Schwartz formula, and stratified as normal or decreased for age at presentation and at the final visit.Results. Records of 181 patients were analysed. The diagnosis was made during the first year of life in 139 patients (76.8%). Clinical presentation included urinary tract infection (UTI) in 109 patients (60.2%), palpable bladder in 98 (54.1%), palpable kidney in 85 (46.9%), and poor urinary stream in 78 (43.1%). An ultrasound scan was reported normal in 10.9%. Vesicostomy was performed in 80 patients (44.2%) and primary valve ablation in 101 (55.8%), with vesicostomy being more prevalent in the pre-2000 era. The median duration of follow-up was 21 months (interquartile range 5 - 79) and renal outcome at last visit was normal in 117 patients (64.6%). The presence of bladder diverticula was associated with a favourable renal outcome. Thirteen patients (7.2%) died, and 102 (56.3%) defaulted from follow-up.Conclusions. PUV frequently presents with UTI and palpable bladder and/or kidneys. Findings on ultrasound were normal in 10.9% of our patients with PUV. A VCUG is indicated in the presence of palpable kidneys or bladder even if the ultrasound scan is normal. Bladder diverticula as a pressure-release mechanism are renoprotective. Vesicostomy or primary valve ablation did not affect final renal outcome. Chronic kidney disease occurred in 34.8% of patients after surgical correction. Adherence to scheduled appointments is problematic in this population. Long-term follow-up is mandatory.

The thrombomodulin analog Solulin promotes reperfusion and reduces infarct volume in a thrombotic stroke model

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/86888/1/j.1538-7836.2011.04269.x.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/86888/2/JTH_4269_sm_Data-S1.pd

The Pondicherry interpretation of quantum mechanics: An overview

An overview of the Pondicherry interpretation of quantum mechanics is presented. This interpretation proceeds from the recognition that the fundamental theoretical framework of physics is a probability algorithm, which serves to describe an objective fuzziness (the literal meaning of Heisenberg's term "Unschaerfe," usually mistranslated as "uncertainty") by assigning objective probabilities to the possible outcomes of unperformed measurements. Although it rejects attempts to construe quantum states as evolving ontological states, it arrives at an objective description of the quantum world that owes nothing to observers or the goings-on in physics laboratories. In fact, unless such attempts are rejected, quantum theory's true ontological implications cannot be seen. Among these are the radically relational nature of space, the numerical identity of the corresponding relata, the incomplete spatiotemporal differentiation of the physical world, and the consequent top-down structure of reality, which defies attempts to model it from the bottom up, whether on the basis of an intrinsically differentiated spacetime manifold or out of a multitude of individual building blocks.Comment: 18 pages, 1 eps figure, v3: with corrections made in proo

Task Control Signals in Pediatric Tourette Syndrome Show Evidence of Immature and Anomalous Functional Activity

Tourette Syndrome (TS) is a pediatric movement disorder that may affect control signaling in the brain. Previous work has proposed a dual-networks architecture of control processing involving a task-maintenance network and an adaptive control network (Dosenbach et al., 2008). A prior resting-state functional connectivity MRI (rs-fcMRI) analysis in TS has revealed functional immaturity in both putative control networks, with “anomalous” correlations (i.e., correlations outside the typical developmental range) limited to the adaptive control network (Church et al., 2009). The present study used functional MRI (fMRI) to study brain activity related to adaptive control (by studying start-cues signals), and to task-maintenance (by studying signals sustained across a task set). Two hypotheses from the previous rs-fcMRI results were tested. First, adaptive control (i.e., start-cue) activity will be altered in TS, including activity inconsistent with typical development (“anomalous”). Second, group differences found in task-maintenance (i.e., sustained) activity will be consistent with functional immaturity in TS. We examined regions found through a direct comparison of adolescents with and without TS, as well as regions derived from a previous investigation that showed differences between unaffected children and adults. The TS group showed decreased start-cue signal magnitude in regions where start-cue activity is unchanged over typical development, consistent with anomalous adaptive control. The TS group also had higher magnitude sustained signals in frontal cortex regions that overlapped with regions showing differences over typical development, consistent with immature task-maintenance in TS. The results demonstrate task-related fMRI signal differences anticipated by the atypical functional connectivity found previously in adolescents with TS, strengthening the evidence for functional immaturity and anomalous signaling in control networks in adolescents with TS

Moduli-Space Dynamics of Noncommutative Abelian Sigma-Model Solitons

In the noncommutative (Moyal) plane, we relate exact U(1) sigma-model solitons to generic scalar-field solitons for an infinitely stiff potential. The static k-lump moduli space C^k/S_k features a natural K"ahler metric induced from an embedding Grassmannian. The moduli-space dynamics is blind against adding a WZW-like term to the sigma-model action and thus also applies to the integrable U(1) Ward model. For the latter's two-soliton motion we compare the exact field configurations with their supposed moduli-space approximations. Surprisingly, the two do not match, which questions the adiabatic method for noncommutative solitons.Comment: 1+15 pages, 2 figures; v2: reference added, to appear in JHE

Influence of a magnetic field on the antiferromagnetic order in UPt_3

A neutron diffraction experiment was performed to investigate the effect of a magnetic field on the antiferromagnetic order in the heavy fermion superconductor UPt_3. Our results show that a field in the basal plane of up to 3.2 Tesla, higher than H_c2(0), has no effect: it can neither select a domain nor rotate the moment. This has a direct impact on current theories for the superconducting phase diagram based on a coupling to the magnetic order.Comment: 7 pages, RevTeX, 3 postscript figures, submitted to Phys. Rev.

Radiosensitization of HNSCC cells by EGFR inhibition depends on the induction of cell cycle arrests

The increase in cellular radiosensitivity by EGF receptor (EGFR) inhibition has been shown to be attributable to the induction of a G1-arrest in p53-proficient cells. Because EGFR targeting in combination with radiotherapy is used to treat head and neck squamous cell carcinomas (HNSCC) which are predominantly p53 mutated, we tested the effects of EGFR targeting on cellular radiosensitivity, proliferation, apoptosis, DNA repair and cell cycle control using a large panel of HNSCC cell lines. In these experiments EGFR targeting inhibited signal transduction, blocked proliferation and induced radiosensitization but only in some cell lines and only under normal (pre-plating) conditions. This sensitization was not associated with impaired DNA repair (53BP1 foci) or induction of apoptosis. However, it was associated with the induction of a lasting G2-arrest. Both, the radiosensitization and the G2-arrest were abrogated if the cells were re-stimulated (delayed plating) with actually no radiosensitization being detectable in any of the 14 tested cell lines. Therefore we conclude that EGFR targeting can induce a reversible G2 arrest in p53 deficient HNSCC cells, which does not consequently result in a robust cellular radiosensitization. Together with recent animal and clinical studies our data indicate that EGFR inhibition is no effective strategy to increase the radiosensitivity of HNSCC cells.</p