Imaging the electronic Wigner crystal in one dimension.

The quantum crystal of electrons, predicted more than 80 years ago by Eugene Wigner, remains one of the most elusive states of matter. In this study, we observed the one-dimensional Wigner crystal directly by imaging its charge density in real space. To image, with minimal invasiveness, the many-body electronic density of a carbon nanotube, we used another nanotube as a scanning-charge perturbation. The images we obtained of a few electrons confined in one dimension match the theoretical predictions for strongly interacting crystals. The quantum nature of the crystal emerges in the observed collective tunneling through a potential barrier. These experiments provide the direct evidence for the formation of small Wigner crystals and open the way for studying other fragile interacting states by imaging their many-body density in real space.

Realization of pristine and locally tunable one-dimensional electron systems in carbon nanotubes.

The ability to tune local parameters of quantum Hamiltonians has been demonstrated in experimental systems including ultracold atoms, trapped ions, superconducting circuits and photonic crystals. Such systems possess negligible disorder, enabling local tunability. Conversely, in condensed-matter systems, electrons are subject to disorder, which often destroys delicate correlated phases and precludes local tunability. The realization of a disorder-free and locally-tunable condensed-matter system thus remains an outstanding challenge. Here, we demonstrate a new technique for deterministic creation of locally-tunable, ultralow-disorder electron systems in carbon nanotubes suspended over complex electronic circuits. Using transport experiments we show that electrons can be localized at any position along the nanotube and that the confinement potential can be smoothly moved from location to location. The high mirror symmetry of transport characteristics about the nanotube centre establishes the negligible effects of electronic disorder, thus allowing experiments in precision-engineered one-dimensional potentials. We further demonstrate the ability to position multiple nanotubes at chosen separations, generalizing these devices to coupled one-dimensional systems. These capabilities could enable many novel experiments on electronics, mechanics and spins in one dimension.

A universal critical density underlying the physics of electrons at the LaAlO3/SrTiO3 interface.

The two-dimensional electron system at the interface between the insulating oxides LaAlO(3) and SrTiO(3) exhibits ferromagnetism, superconductivity and a range of unique magnetotransport properties. An open experimental challenge is to identify, out of the multitudinous energy bands predicted to exist at the interface, the key ingredients underlying its emergent transport phenomena. Here we show, using magnetotransport measurements, that a universal Lifshitz transition between d orbitals of different symmetries lies at the core of the observed phenomena. We find that LaAlO(3)/SrTiO(3) systems generically switch from one- to two-carrier transport at a universal carrier density, which is independent of the LaAlO(3) thickness and electron mobility. Interestingly, the maximum superconducting critical temperature occurs also at the Lifshitz density, indicating a possible connection between the two phenomena. A simple band model, allowing for spin-orbit coupling at the atomic level, connects the observed transition to a variety of previously reported properties. Our results demonstrate that the fascinating behaviour observed so far in these oxides follows from a small but fundamental set of bands.

[Progressive myoclonic encephalopathy in dialysis patients. Clinical, electroencephalographic and neuropathological study. Pathogenetic discussion]. / L'encéphalopathie myoclonique progressive des dialysés (E.M.P.D.). Etude clinique, électroencéphalographique et neuropathologique. Discussion pathogénique.

Clinical and Neuropathological data on sixteen cases of progressive myoclonic encephalopathy are reported. This neurological syndrome appears after an average duration of thirty two months of haemodialysis and leads to death in four and a half months, and is characterized by myoclonus, speech disorder, epileptic seizures, and mental-status changes. At first, clinical signs and symptoms are related to haemodialysis, later they become permanent. An early diagnosis is based on EEG which is the only useful laboratory test, demonstrating bisynchronous slow-wave bursts. The caracteristic histopathologic findings are neuronal depopulation, lipofuscin accumulation, and appearance of Neurofibrillary degeneration, especially in Motor cortex, red nucleus and dentato-olivary systems. It seems to be justified to attribute P.M.D.E. to aluminium chronic poisonning; the source of the aluminium intoxication is not aluminium containing phosphate-binding gels but intravenously administreted tape-water. The intracellular binding of aluminium is shown from a histochemical study employing fluorescent stain Morin.

[Progressive myoclonic encephalopathy in dialysis patients. The role of the water used for haemodialysis (author's transl)]. / Encéphalopathie myoclonique progressive des dialysés. Rôle de l'eau utilisée pour l'hémodialyse.

The observation in 14 dialysis patients of an encephalopathy associating myoclonia, dysarthria, generalised seizures in some cases, worsening over a few months, led to an aetiological inquiry based upon comparative study of patients with or without encephalopathy treated in the same centre or at home, and controls. Higher levels of aluminium were found in the frontal cortex grey matter of encephalopathy patients as compared to the control group. The same applies to manganese in the white matter. Copper, zinc and iron contents were not different. Aluminium levels in blood, dialysis bath and tap water supply were higher in center dialysis than in home dialysis. Blood aluminium levels at the end of hemodialysis were correlated with bath aluminium levels. The ingestion of alumine gels was not greater in the encephalopathy patients than in other hemodialysis patients; its estimation, in each case, was not related to the blood aluminium levels at the begining of hemodialysis. These finding indicate the need of a routine measure of metal content - mainly aluminium and manganese - in tap water used for dialysis, in order to treat this water if necessary.