Theory and applications of supercycled symmetry-based recoupling sequences in solid-state NMR

We present the theoretical principles of supercycled symmetry-based recoupling sequences in solid-state magic-angle-spinning NMR. We discuss the construction procedure of the SR26 pulse sequence, which is a particularly robust sequence for double-quantum homonuclear dipole-dipole recoupling. The supercycle removes destructive higher-order average Hamiltonian terms and renders the sequence robust over long time intervals. We demonstrate applications of the SR26 sequence to double-quantum spectroscopy, homonuclear spin counting, and determination of the relative orientations of chemical shift anisotropy tensors

Partial nonlinear reciprocity breaking through ultrafast dynamics in a random photonic medium

We demonstrate that ultrafast nonlinear dynamics gives rise to reciprocity breaking in a random photonic medium. Reciprocity breaking is observed via the suppression of coherent backscattering, a manifestation of weak localization of light. The effect is observed in a pump-probe configuration where the pump induces an ultrafast step-change of the refractive index during the dwell time of the probe light in the material. The dynamical suppression of coherent backscattering is reproduced well by a multiple scattering Monte Carlo simulation. Ultrafast reciprocity breaking provides a distinct mechanism in nonlinear optical media which opens up avenues for the active manipulation of mesoscopic transport, random lasers, and photon localization.Comment: 5 pages, 4 figure

Attenuated cerebrospinal fluid leukocyte count and sepsis in adults with pneumococcal meningitis: a prospective cohort study

BACKGROUND: A low cerebrospinal fluid (CSF) white-blood cell count (WBC) has been identified as an independent risk factor for adverse outcome in adults with bacterial meningitis. Whereas a low CSF WBC indicates the presence of sepsis with early meningitis in patients with meningococcal infections, the relation between CSF WBC and outcome in patients with pneumococcal meningitis is not understood. METHODS: We examined the relation between CSF WBC, bacteraemia and sepsis in a prospective cohort study that included 352 episodes of pneumococcal meningitis, confirmed by CSF culture, occurring in patients aged >16 years. RESULTS: CSF WBC was recorded in 320 of 352 episodes (91%). Median CSF WBC was 2530 per mm(3 )(interquartile range 531–6983 per mm(3)) and 104 patients (33%) had a CSF WBC <1000/mm(3). Patients with a CSF WBC <1000/mm(3 )were more likely to have an unfavourable outcome (defined as a Glasgow Outcome Scale score of 1–4) than those with a higher WBC (74 of 104 [71%] vs. 87 of 216 [43%]; P < 0.001). CSF WBC was significantly associated with blood WBC (Spearman's test 0.29), CSF protein level (0.20), thrombocyte count (0.21), erythrocyte sedimentation rate (-0.15), and C-reactive protein levels (-0.18). Patients with a CSF WBC <1000/mm(3 )more often had a positive blood culture (72 of 84 [86%] vs. 138 of 196 [70%]; P = 0.01) and more often developed systemic complications (cardiorespiratory failure, sepsis) than those with a higher WBC (53 of 104 [51%] vs. 69 of 216 [32%]; P = 0.001). In a multivariate analysis, advanced age (Odds ratio per 10-year increments 1.22, 95%CI 1.02–1.45), a positive blood culture (Odds ratio 2.46, 95%CI 1.17–5.14), and a low thrombocyte count on admission (Odds ratio per 100,000/mm(3 )increments 0.67, 95% CI 0.47–0.97) were associated with a CSF WBC <1000/mm(3). CONCLUSION: A low CSF WBC in adults with pneumococcal meningitis is related to the presence of signs of sepsis and systemic complications. Invasive pneumococcal infections should possibly be regarded as a continuum from meningitis to sepsis

Ferromagnetic Domain Structure of La0.78Ca0.22MnO3 Single Crystals

The magneto-optical technique has been employed to observe spontaneous ferromagnetic domain structures in La0.78Ca0.22MnO3 single crystals. The magnetic domain topology was found to be correlated with the intrinsic twin structure of the investigated crystals. With decreasing temperature the regular network of ferromagnetic domains undergoes significant changes resulting in apparent rotation of the domain walls in the temperature range of 70-150 K. The apparent rotation of the domain walls can be understood in terms of the Jahn-Teller deformation of the orthorhombic unit cell, accompanied by additional twinning.Comment: 7 pages, 5 figures, to be published in PR

Cerebrospinal Fluid Sex Steroid Hormones in Bacterial Meningitis

Unfavorable outcome in bacterial meningitis is related to excessive inflammation and higher inflammatory markers have been reported in female than in male patients. Sex steroid hormones have immunomodulatory properties and can be found in the cerebrospinal fluid (CSF); however, their actions have not been studied in bacterial meningitis. We investigated the association between CSF sex steroid hormone levels and inflammatory parameters, disease severity, and outcome in pneumococcal meningitis. We identified adults with culture-proven pneumococcal meningitis in a prospective cohort study (2006-2014). We measured estradiol and testosterone in CSF using liquid chromatography-tandem mass spectrometry and sex hormone-binding globulin (SHBG) using an enzyme-linked immunoassay. Hormone levels were compared according to outcome, which was graded using the Glasgow Outcome Scale (a score of 5 indicating favorable, 1-4 unfavorable outcome). Correlation analysis was used to measure the association between hormone levels and inflammatory cytokines, chemokines, and complement factors as well as severity of illness, as measured by the Glasgow Coma Scale and the Dutch Meningitis Risk Score. We included 60 patients: 20 men, 20 premenopausal (50 years) women. Twenty-one (35%) patients had an unfavorable outcome and 11 (18%) died. Cases with an unfavorable outcome exhibited higher estradiol (median 14.0 vs 5.0 pmol/L, P = .04) and lower SHBG (0.40 vs 1.0 nmol/L, P = .03) levels compared with those with a favorable outcome. Estradiol was positively correlated with C-reactive protein (R = 0.42, P = .001), CSF protein (R = 0.33, P = .01), and proinflammatory cytokine levels. CSF concentrations of the sex steroid hormone estradiol were associated with outcome and CSF inflammation. Understanding the dose and time-dependent interaction between sex steroid hormones and the inflammatory response in bacterial meningitis represents an important and understudied topic.info:eu-repo/semantics/publishedVersio

Defect-unbinding and the Bose-glass transition in layered superconductors

The low-field Bose-glass transition temperature in heavy-ion irradiated Bi_2Sr_2CaCu_2O_8+d increases progressively with increasing density of irradiation-induced columnar defects, but saturates for densities in excess of 1.5 x10^9 cm^-2. The maximum Bose-glass temperature corresponds to that above which diffusion of two-dimensional pancake vortices between different vortex lines becomes possible, and above which the ``line-like'' character of vortices is lost. We develop a description of the Bose-glass line that is in excellent quantitative agreement with the experimental line obtained for widely different values of track density and material parameters.Comment: 4 pages, 4 figures, submitted to Phys. Rev. Let