Shot noise in the self-dual interacting resonant level model.

By using two independent and complementary approaches, we compute exactly the shot noise in an out-of-equilibrium interacting impurity model, the interacting resonant level model at its self-dual point. An analytical approach based on the thermodynamical Bethe ansatz allows us to obtain the density matrix in the presence of a bias voltage, which in turn allows for the computation of any observable. A time-dependent density matrix renormalization group technique that has proven to yield the correct result for a free model (the resonant level model) is shown to be in perfect agreement with the former method.

Twofold advance in the theoretical understanding of far-from-equilibrium properties of interacting nanostructures.

We calculate the full I-V characteristics at vanishing temperature in the self-dual interacting resonant level model in two ways. The first uses careful time dependent density matrix renormalization group with a large number of states per block and a representation of the reservoirs as leads subjected to a chemical potential. The other is based on integrability in the continuum limit, and generalizes early work by Fendley, Ludwig, and Saleur on the boundary sine-Gordon model. The two approaches are in excellent agreement, and uncover among other things a power law decay of the current at large voltages when U>0.

Confinement and superfluidity in one-dimensional degenerate fermionic cold atoms.

The physical properties of arbitrary half-integer spins F = N - (1/2) fermionic cold atoms trapped in a one-dimensional optical lattice are investigated by means of a low-energy approach. Two different superfluid phases are found for F > or = (3/2) depending on whether a discrete symmetry is spontaneously broken or not: an unconfined BCS pairing phase and a confined molecular-superfluid instability made of 2N fermions. We propose an experimental distinction between these phases for a gas trapped in an annular geometry. The confined-unconfined transition is shown to belong to the Z(N) generalized Ising universality class. We discuss the possible Mott phases at (1/2) filling.

[The jugulotympanic paragangliomas: 41 cases report]. / Les paragangliomes tympano-jugulaires. A propos de 41 cas.

OBJECTIVE: The jugulotympanic paragangliomas (JTP) represents the most frequent tumour of the middle ear but also of the temporal bone, after the acoustic neurinoma. The management of these vascular tumours remains uncleared. The purpose of this study was to report our experience about JTP in the CHU of Grenoble. MATERIALS AND METHODS: Retrospective study of 41 patients, between 1973 and 1996. Six stages A, 8 stages B and 27 stages C are reported in whom 20 cases (49%) presented an intracranial extension (classification of Fisch). There were 2 familial cases with multiple localisations, in particular carotid. All the patients were divided in 3 groups: surgery or radiation therapy in first intention, surgery followed by radiation therapy. RESULTS: A total tumor removal without recurrence was achieved by surgery in more than 95% of the cases with 6 years follow-up but was associated with significant morbidity (major cranial nerve injury). We noticed one death by laryngospasme (C2Di2 tumour operated by infratemporal A approach). A stabilization of the tumour was obtained with radiotherapy in first intention in 75% of the cases (5 years follow-up) but with a risk of radionecrosis. A revision surgery was necessary in 3 cases. CONCLUSION: The comparaison of our different therapeutic management, surgery (23), radiation therapy (16) or combined (2), encourage us to perform a radical surgery whenever possible. Because of the slow rate of growth, the radiotherapy is indicated for older patients, at risk for surgery or extensive tumors. The objectives of the radiation therapy are to obtain a tumoral stabilization with improvement of the symptoms and low morbidity. The management of this rare pathology must be multidisciplinary. The recent discoveries on genes encoding three succinate dehydrogenase subunits (SDHD, SDHB et SDHC) will allow a genetic detection of asymptomatic case and will define the procedures for their management, coordinated by a national network PGL.NET. A retrospective study could also study the real incidence of familial paragangliomas.

[Cavernous angiomas of the brain stem: auditory and vestibular manifestations]. / Angiomes caverneux du tronc cérébral: manifestations auditives et vestibulaires.

AIMS: To establish the correlation between the clinical manifestations of hearing and balance disturbance and the anatomical site within the pons of cavernous angiomas, and to describe their clinical features, and the findings on ABR and MRI. MATERIALS AND METHODS: Two clinical cases of cavernous angioma with cochlear and vestibular manifestations underwent audiometric evaluation, with VNG and ABR as well as CT and MRI scans. CONCLUSION: Cavernous angiomas are rare (less than 2% of intra-cranial space-occupying lesions). Their most common topographical site is midline in the pons, and may give rise to symptoms in attacks (due to episodes of bleeding within the tumour) which may mimic symptoms of peripheral origin (sudden deafness, fluctuating hearing loss, Menière-like vertigo). There may be ectopic remnants of the embryonic blood vascular system. They may be associated with other malformations (intra-cerebral venous angiomas, cavernous angiomas at other sites). Their development is often by sudden progression which may be dramatic, and have accompanying neurological features. For investigating the hearing and balance, ABR is an excellent test, giving a typical picture of a retro-cochlear lesion that necessitates progression to MRI, the investigation of choice. This will demonstrate the typical rosette-like appearance with a heterogeneous T2 image (a less dense peripheral ring, with a denser central signal). There is no specific medical treatment for this condition, and surgery is indicated only exceptionally. There is a contraindication to anticoagulant therapy, to platelet-dispersing medication and to violent sports activities. Two cases of cavernous angioma are reported; one was more anteriorly situated, and had mainly vestibular features, and the other was more posterior near the floor of the IVth ventricule, with mainly auditory features. The correlation of the anatomical and clinical findings with those of the MRI are discussed, especially in relation to our understanding of the auditory and vestibular pathways within the brainstem (the auditory striae, the crossed auditory pathways and the nuclei of the corpus trapezoideum for the auditory effects, and the paramedian reticular nucleus and crossed inter-commissure pathways to the cerebellum and vestibular nuclei, together with the proximity of the direct midline vestibulo-spinal tract, for the vestibular effects).

[Gadolinium and contrast medium MRI of the acoustic nerve in patients with meningeal neuritis and acoustico-facial syndrome]. / Imagerie en résonance magnétique avec Gadolinium et prise de contraste de la VIIIe paire au cours de méningo-névrites avec syndrome acoustico-facial.

Twelve cases of vestibular neuritis were investigated in gradient echo MRI with gadolinium. Only 3 severe cases associated with an acoustico facial syndrome (2 cases of herpes zoster oticus and one case after influenzae) demonstrated focal enhancement within the internal auditory canal on post contrast T1 weighted images. This enhancement involved at least 2 differents nerves. These 3 severe cases associating sensory neural hearing loss and facial palsy revealed a meningeal reaction after cerebrospinal fluid examination. The enhancement lasted a long time (up to 10 months) in one case of RAMSAY HUNT syndrome associated with a chronic lymphocytic leukemia. The MRI was able to confirm the anatomical reality of the vestibular neuritis and more precisely of the meningoneuritis and gave arguments for the theory of the polyneuropathy of Adour. Enhancement at MRI seems correlated with the severity of the affection (permanent vestibular areflexia in 3 cases and permanent hearing loss in 1 case).

[Hemorrhagic complications of lower turbinectomy]. / Complications hémorragiques des turbinectomies inférieures.

Concerning 52 inferior turbinectomies, the authors analyse the haemorrhagic complications of these surgical operations. They deplore 4% of serious haemorrhages. These ones may immediately occur during the surgical operation or in the next 15 days. No technique can prevent an haemorrhage. So that the patient must be notified of the risks he runs and the indications have to be seriously discussed.