Crystalline Electric Field Effects in CeMIn5: Superconductivity and the Influence of Kondo Spin Fluctuations

We have measured the crystalline electric field (CEF) excitations of the CeMIn5 (M = Co, Rh, Ir) series of heavy fermion superconductors by means of inelastic neutron scattering. Fits to a CEF model reproduce the inelastic neutron scattering spectra and the high temperature magnetic susceptibility. The CEF parameters, energy level splittings, and wavefunctions are tabulated for each member of the CeMIn5 series and compared to each other as well as to the results of previous measurements. Our results indicate that the CEF level splitting in all three materials is similar, and can be thought of as being derived from the cubic parent compound CeIn3 in which an excited state quartet at ~12 meV is split into two doublets by the lower symmetry of the tetragonal environment of the CeMIn5 materials. In each case, the CEF excitations are observed as broad lines in the inelastic neutron scattering spectrum. We attribute this broadening to Kondo hybridization of the localized f moments with the conduction electrons. The evolution of the superconducting transition temperatures in the different members of CeMIn5 can then be understood as a direct consequence of the strength of this hybridization. Due to the importance of Kondo spin fluctuations in these materials, we also present calculations within the non-crossing approximation (NCA) to the Anderson impurity model including the effect of CEF level splitting for the inelastic neutron scattering spectra and the magnetic susceptibility.Comment: 30 pages, 6 figures, submitted to Phys. Rev.

Crystalline Electric Field Excitations in the Heavy Fermion Superconductor CeCoIn_5

The crystalline electric field (CEF) energy level scheme of the heavy fermion superconductor CeCoIn_5 has been determined by means of inelastic neutron scattering (INS). Peaks observed in the INS spectra at 8 meV and 27 meV with incident neutron energies between E_i=30-60 meV and at a temperature T = 10 K correspond to transitions from the ground state to the two excited states, respectively. The wavevector and temperature dependence of these peaks are consistent with CEF excitations. Fits of the data to a CEF model yield the CEF parameters B^0_2=-0.80 meV, B^0_4=0.059 meV, and |B^4_4|= 0.137 meV corresponding to an energy level scheme: Gamma_7^(1) (0)[=0.487|+/-5/2> - 0.873|-/+3/2>], Gamma_7^(2) (8.6 meV, 100 K), and Gamma_6 (24.4 meV, 283 K).Comment: uses latex packages revtex4,amsmath,graphicx,natbib, 9th Annual MMM-Intermag Conference, (Accepted for publication in J. Appl. Phys.) 7 pages, 2 figure

Single-cell reconstruction of follicular remodeling in the human adult ovary

The ovary is perhaps the most dynamic organ in the human body, only rivaled by the uterus. The molecular mechanisms that regulate follicular growth and regression, ensuring ovarian tissue homeostasis, remain elusive. We have performed single-cell RNA-sequencing using human adult ovaries to provide a map of the molecular signature of growing and regressing follicular populations. We have identified different types of granulosa and theca cells and detected local production of components of the complement system by (atretic) theca cells and stromal cells. We also have detected a mixture of adaptive and innate immune cells, as well as several types of endothelial and smooth muscle cells to aid the remodeling process. Our results highlight the relevance of mapping whole adult organs at the single-cell level and reflect ongoing efforts to map the human body. The association between complement system and follicular remodeling may provide key insights in reproductive biology and (in) fertility

Non-Equilibrium Creation of Intrinsically Localized Vibrations in Uranium Using X-Ray and Neutron Scattering

In an anharmonic crystal, large-amplitude vibrational fluctuations on the scale of the lattice spacing can develop frequencies that do not resonate with the normal modes, causing energy to become trapped in intrinsically localized modes (ILMs)--also called 'discrete breathers' or 'lattice solitons'. This mechanism has been observed in analogous systems on a larger scale, but unambiguous sightings in atomic lattice vibrations, where quantum mechanics may play a role, have proved difficult. Two challenges have hampered progress: (1) the need to separate ILMs from defect modes, and (2) complications that arise at high temperatures, including feature broadening and multiphonon processes. Here we solve these problems by using x-ray and neutron scattering to induce ILM-forming amplitude fluctuations in uranium at low temperatures, thereby creating nonequilibrium ILMs. Creation of ILMs occurs at a discrete energy, indicating an unexpected quantum character to ILM formation and greatly simplifying detection

Role of Magnetic Exchange Energy on Charge Ordering in RSFO (R=La, Pr, and Nd)

Inelastic neutron scattering is applied to study the role of magnetism in stabilizing the charge ordered state in \emph{R}$_{1/3}$Sr$_{2/3}$FeO$_{3}$ (\emph{R}SFO) (\emph{R} = La, Pr, and Nd). The ratio of the ferromagnetic exchange energy (J$_F$) and antiferromagnetic exchange energy (J$_{AF}$), |J$_F$ /J$_{AF}|, is a key indicator of the stability of the charge ordered and antiferromagnetic ordered state. This ratio is obtained from the spin wave spectrum by inelastic neutron scattering and is sufficiently large to suggest that the magnetic exchange energy alone can stabilize the charge ordered state in La$_{1/3}$Sr$_{2/3}$FeO$_{3}$and Pr$_{1/3}$Sr$_{2/3}$FeO$_{3}$. The exchange ratio decreases from La$_{1/3}$Sr$_{2/3}$FeO$_{3}$to Nd1$_{1/3}$Sr$_{2/3}$FeO$_{3}$ which indicates a gradual destabilization of the magnetic exchange mechanism for charge ordering in correspondence with the observed reduction in the ordering temperature

Presence of anticitrullinated protein antibodies in a large population-based cohort from the Netherlands

Objectives To determine the prevalence of anticitrullinated protein antibodies (ACPAs) and their association with known rheumatoid arthritis (RA) risk factors in the general population. Methods Lifelines is a multidisciplinary prospective population-based cohort study in the Netherlands. Cross-sectional data from 40 136 participants were used. The detection of ACPA was performed by measuring anti-CCP2 on the Phadia-250 analyser with levels >= 6.2 U/mL considered positive. An extensive questionnaire was taken on demographic and clinical information, including smoking, periodontal health and early symptoms of musculoskeletal disorders. RA was defined by a combination of self-reported RA, medication use for the indication of rheumatism and visiting a medical specialist within the last year. Results Of the total 40 136 unselected individuals, 401 (1.0%) had ACPA level >= 6.2 U/mL. ACPA positivity was significantly associated with older age, female gender, smoking, joint complaints, RA and first degree relatives with rheumatism. Of the ACPA-positive participants, 22.4% had RA (15.2% had defined RA according to our criteria and 7.2% self-reported RA only). In participants without RA, 311 (0.8%) were ACPA-positive. In the non-RA group, older age, smoking and joint complaints remained significantly more frequently present in ACPA-positive compared with ACPA-negative participants. Conclusions In this large population-based study, the prevalence of ACPA levels >= 6.2 U/mL was 1.0% for the total group and 0.8% when excluding patients with RA. Older age, smoking and joint complaints were more frequently present in ACPA-positive Lifelines participants. To our knowledge, this study is the largest study to date on ACPA positivity in the general, mostly Caucasian population

Stratégiai szövetségek, a vállalati kapcsolati hálók átalakulása és a versenyképesség

Transplantation and autoimmunit