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We studied the magnetic excitations in the quasi-one-dimensional (q-1D) ladder subsystem of Sr_(14-x) Ca_x Cu_24 O_41(SCCO) using Cu L_3-edge resonant inelastic X-ray scattering (RIXS). By comparing momentum-resolved RIXS spectra with (x=12.2) and without (x=0) high Ca content, we track the evolution of the magnetic excitations from collective two-triplon (2T) excitations (x=0) to weakly-dispersive gapped modes at an energy of 280 meV (x=12.2). Density matrix renormalization group (DMRG) calculations of the RIXS response in the doped ladders suggest that the flat magnetic dispersion and damped excitation profile observed at x=12.2 originates from enhanced hole localization. This interpretation is supported by polarization-dependent RIXS measurements, where we disentangle the spin-conserving {\Delta}S=0 scattering from the predominant {\Delta}S=1 spin-flip signal in the RIXS spectra. The results show that the low-energy weight in the {\Delta}S=0 channel is depleted when Sr is replaced by Ca, consistent with a reduced carrier mobility. Our results demonstrate that off-ladder impurities can affect both the low-energy magnetic excitations and superconducting correlations in the CuO_4 plaquettes. Finally, our study characterizes the magnetic and charge fluctuations in the phase from which superconductivity emerges in SCCO at elevated pressures.

High-quality single crystals of CoTiO$_3$ are grown and used to elucidate in detail structural and magnetostructural effects by means of high-resolution capacitance dilatometry studies in fields up to 15 T which are complemented by specific heat and magnetization measurements. In addition, we refine the single-crystal structure of the ilmenite ($R\bar{3}$) phase. At the antiferromagnetic ordering temperature $T_\mathrm{N}$, pronounced $��$-shaped anomaly in the thermal expansion coefficients signals shrinking of both the $c$ and $b$ axes, indicating strong magnetoelastic coupling with uniaxial pressure along $c$ yielding six times larger effect on $T_\mathrm{N}$ than the pressure applied in-plane. The hydrostatic pressure dependency derived by means of Gr��neisen analysis amounts to $\partial T_\mathrm{N}/ \partial p\approx 2.7(4)$~K/GPa. The high-field magnetization studies in static and pulsed magnetic fields up to 60~T along with high-field thermal expansion measurements facilitate in constructing the complete anisotropic magnetic phase diagram of CoTiO$_3$. While the results confirm the presence of significant magnetodielectric coupling, our data show that magnetism drives the observed structural, dielectric, and magnetic changes both in the short-range ordered regime well-above $T_\mathrm{N}$ as well as in the long-range magnetically ordered phase., Accepted for publication in PRB

Mycobacterium chlorophenolicum is a nontuberculous mycobacterium that has previously been characterized as nonpathogenic. We describe a 44 year-old patient with a history of deceased donor renal transplant on sirolimus who was found to meet criteria for both sirolimus-associated pneumonitis and secondary infection with Mycobacterium chlorophenolicum. In addition to describing a new infection with a generally nonpathogenic organism, we believe this case could generate new hypotheses regarding nontuberculous mycobacteria and the pathogenesis of sirolimus-associated pneumonitis.

Diffuse intense lung uptake of TI-201 chloride without abnormal Ga-67 citrate in a case of cytomegalovirus pneumonitis in a patient with AIDS is presented. An autopsy performed within 4 days of imaging revealed no pulmonary pathology other than diffuse cytomegalovirus infection with abundant histiocytes and inclusion bodies and pulmonary congestive heart failure. Among the various mechanisms of TI-201 accumulation, active transport through Na-K ATPase appears to be predominant in this case, as suggested by innumerable histiocytes. It is the authors' experience that positive TI-201 uptake without abnormal Ga-67 accumulation is highly specific for pulmonary Kaposi sarcoma. The presence of such discrepancy between TI-201 and Ga-67 uptake in AIDS patients decreases the specificity of a TI-201 positive/Ga-67 negative lesion for pulmonary Kaposi sarcoma, especially with the rising incidence of both cytomegalovirus and Kaposi sarcoma in AIDS patients.

We studied the magnetic excitations in the quasi-one-dimensional (q-1D) ladder subsystem of Sr14-xCaxCu24O41 (SCCO) using Cu L-3-edge resonant inelastic X-ray scattering (RIXS). By comparing momentum-resolved RIXS spectra with high (x = 12.2) and without (x = 0) Ca content, we track the evolution of the magnetic excitations from collective two-triplon (2 T) excitations (x = 0) to weakly-dispersive gapped modes at an energy of 280 meV (x = 12.2). Density matrix renormalization group (DMRG) calculations of the RIXS response in the doped ladders suggest that the flat magnetic dispersion and damped excitation profile observed at x = 12.2 originates from enhanced hole localization. This interpretation is supported by polarization-dependent RIXS measurements, where we disentangle the spin-conserving Delta S = 0 scattering from the predominant Delta S = 1 spin-flip signal in the RIXS spectra. The results show that the low-energy weight in the Delta S = 0 channel is depleted when Sr is replaced by Ca, consistent with a reduced carrier mobility. Our results demonstrate that off-ladder impurities can affect both the low-energy magnetic excitations and superconducting correlations in the CuO4 plaquettes. Finally, our study characterizes the magnetic and charge fluctuations in the phase from which superconductivity emerges in SCCO at elevated pressures.