Momentum-resolved evolution of the Kondo lattice into "hidden order" in URu2Si2.

We study, using high-resolution angle-resolved photoemission spectroscopy, the evolution of the electronic structure in URu2Si2 at the Γ, Z, and X high-symmetry points from the high-temperature Kondo-screened regime to the low-temperature hidden-order (HO) state. At all temperatures and symmetry points, we find structures resulting from the interaction between heavy and light bands related to the Kondo-lattice formation. At the X point, we directly measure a hybridization gap of 11 meV already open at temperatures above the ordered phase. Strikingly, we find that while the HO induces pronounced changes at Γ and Z, the hybridization gap at X does not change, indicating that the hidden-order parameter is anisotropic. Furthermore, at the Γ and Z points, we observe the opening of a gap in momentum in the HO state, and show that the associated electronic structure results from the hybridization of a light electron band with the Kondo-lattice bands characterizing the paramagnetic state.

Coherent heavy quasiparticles in a CePt5 surface alloy.

We report on the results of a high-resolution angle-resolved photoemission study on the ordered surface alloy CePt(5). The temperature dependence of the spectra show the formation of the coherent low-energy heavy-fermion band near the Fermi level. These experimental data are supported by a multiband model calculation in the framework of the dynamical mean-field theory.

High-temperature signatures of quantum criticality in heavy-fermion systems.

We propose a new criterion for distinguishing the Hertz-Millis (HM) and the local quantum critical (LQC) mechanism in heavy-fermion systems with a magnetic quantum phase transition (QPT). The criterion is based on our finding that the complete spin screening of Kondo ions can be suppressed by the Ruderman-Kittel-Kasuya-Yosida (RKKY) coupling to the surrounding magnetic ions even without magnetic ordering and that, consequently, the signature of this suppression can be observed in spectroscopic measurements above the magnetic ordering temperature. We apply the criterion to high-resolution photoemission measurements on CeCu(6 - x)Au(x) and conclude that the QPT in this system is dominated by the LQC scenario.

Signature of quantum criticality in photoemission spectroscopy.

A quantum phase transition in a heavy-fermion compound may destroy the Fermi-liquid ground state. However, the conditions for this breakdown have remained obscure. We report the first direct investigation of heavy quasiparticle formation and breakdown in the canonical system CeCu(6-x)Au(x) by ultraviolet photoemission spectroscopy at elevated temperatures without the complications of lattice coherence. Surprisingly, the single-ion Kondo energy scale T(K) exhibits an abrupt step near the quantum critical Au concentration of x(c) = 0.1. We show theoretically that this step is expected from a highly nonlinear renormalization of the local spin coupling at each Ce site, induced by spin fluctuations on neighboring sites. It provides a general high-temperature indicator for heavy-fermion quasiparticle breakdown at a quantum phase transition.

Prevalence of diabetic peripheral neuropathy and its relation to glycaemic control and potential risk factors: the EURODIAB IDDM Complications Study.

The EURODIAB IDDM Complications Study involved the examination of 3250 randomly selected insulin-dependent diabetic patients, from 31 centres in 16 European countries. Part of the examination included an assessment of neurological function including neuropathic symptoms and physical signs, vibration perception threshold, tests of autonomic function and the prevalence of impotence. The prevalence of diabetic neuropathy across Europe was 28% with no significant geographical differences. Significant correlations were observed between the presence of diabetic peripheral neuropathy with age (p < 0.05), duration of diabetes (p < 0.001), quality of metabolic control (p < 0.001), height (p < 0.01), the presence of background or proliferative diabetic retinopathy (p < 0.01), cigarette smoking (p < 0.001), high-density lipoprotein cholesterol (p < 0.001) and the presence of cardiovascular disease (p < 0.05), thus confirming previous associations. New associations have been identified from this study - namely with elevated diastolic blood pressure (p < 0.05), the presence of severe ketoacidosis (p < 0.001), an increase in the levels of fasting triglyceride (p < 0.001), and the presence of microalbuminuria (p < 0.01). All the data were adjusted for age, duration of diabetes and HbA1c. Although alcohol intake correlated with absence of leg reflexes and autonomic dysfunction, there was no overall association of alcohol consumption and neuropathy. The reported problems of impotence were extremely variable between centres, suggesting many cultural and attitudinal differences in the collection of such information in different European countries. In conclusion, this study has identified previously known and new potential risk factors for the development of diabetic peripheral neuropathy.

[Pulmonary arterial hypertension and primary biliary cirrhosis]. / Hypertension artérielle pulmonaire et cirrhose biliaire primitive.

The authors report a case of the association of primary biliary cirrhosis and pulmonary hypertension presenting with syncopal complete atrioventricular block. The clinical, aetiopathological and therapeutic aspects of this pathology are reviewed with special emphasis on the value of early diagnosis of the pulmonary hypertension in cases of unusual dyspnoea in patients with primary biliary cirrhosis especially those of an age when they could benefit from liver-heart-lung transplantation.

No association of antibodies to glutamic acid decarboxylase and diabetic complications in patients with IDDM.

OBJECTIVE: To evaluate the association of antibodies to glutamic acid decarboxylase (GAD-ab) and diabetic complications (neuropathy, retinopathy, and nephropathy) in patients with insulin-dependent diabetes mellitus (IDDM). RESEARCH DESIGN AND METHODS: We examined the prevalence of GAD-ab (immunoprecipitation assay) and islet cell antibodies (ICAs) (indirect immunofluorescence) in a representative sample of IDDM patients (n = 146) with different disease duration (2-52 years, median 13.2 years). Of all patients characterized for the existence of diabetic complications, 56 of 146 had peripheral neuropathy, 24 of 142 had autonomic neuropathy, 67 of 141 had retinopathy, and 39 of 146 had nephropathy. RESULTS: GAD-ab (> 2 SD) were detected more frequently than ICA (> 5 Juvenile Diabetes Foundation units) in IDDM patients of different disease duration (GAD-ab+ 37% [54 of 146] vs. ICA+ 22% [32 of 146], P = 0.011; diabetes duration less than median: GAD-ab+ 47% vs. ICA+ 23%, P = 0.0046; diabetes duration greater than median: GAD-ab+ 27% vs. ICA+ 22%, P > 0.05). For GAD-ab and for ICA, respectively, no difference was observed in frequency of positivity or titers between patients with or without diabetic complications. CONCLUSIONS: Both GAD-ab and, to a lesser extent, ICA persist for a long time in several individuals. This persistence is not related to diabetic neuropathy or any other diabetic complication.

Metabolic effects of ramipril treatment in hypertensive subjects with non-insulin-dependent diabetes mellitus.

The antihypertensive and metabolic effects of the new long-acting angiotensin converting enzyme (ACE) inhibitor, ramipril (Hoe 498), were assessed in 21 patients with non-insulin-dependent diabetes mellitus (NIDDM) over a 12-week treatment period. In an average dose of 5 mg given once daily, ramipril effectively reduced the elevated blood pressure. In 74% of the cases systolic and diastolic blood pressure was normalised during monotherapy. Mean blood glucose and glycosylated hemoglobin (HbAI) values showed a slight but significant (p less than 0.05) decrease at the end of the ramipril treatment period (glucose: 8.5 +/- 1.4 mmol/l vs 8.0 +/- 0.9 mmol/l; HbAI: 10.0 +/- 1.3% vs 9.7 +/- 1.1%). C-peptide levels did not change. Since there was also a small reduction of body weight during treatment, the observed hypoglycemic response could not be fully ascribed to ramipril. Also, a reduction in total cholesterol and an increase of HDL cholesterol could be documented during treatment with ramipril. The reduction in body weight could also be made partly responsible for this positive effect on lipid metabolism. No serious side effects were reported during the entire study period. Due to these beneficial effects, ramipril can be recommended as first-line drug in the management of hypertensive subjects with NIDDM.