Laser-induced dynamic alignment of the HD molecule without the Born-Oppenheimer approximation.

Laser-induced molecular alignment is well understood within the framework of the Born-Oppenheimer (BO) approximation. Without the BO approximation, however, the concept of molecular structure is lost, making it hard to precisely define alignment. In this work, we demonstrate the emergence of alignment from the first-ever non-BO quantum dynamics simulations, using the HD molecule exposed to ultrashort laser pulses as a few-body test case. We extract the degree of alignment from the non-BO wave function by means of an operator expressed in terms of pseudo-proton coordinates that mimics the BO-based definition of alignment. The only essential approximation, in addition to the semiclassical electric-dipole approximation for the matter-field interaction, is the choice of time-independent explicitly correlated Gaussian basis functions. We use a variational, electric-field-dependent basis-set construction procedure, which allows us to keep the basis-set dimension low while capturing the main effects of electric polarization on the nuclear and electronic degrees of freedom. The basis-set construction procedure is validated by comparing with virtually exact grid-based simulations for two one-dimensional model systems: laser-driven electron dynamics in a soft attractive Coulomb potential and nuclear rovibrational dynamics in a Morse potential.

[Encephalopathy induced by arterial hypertension: clinical, radiological and therapeutical aspects]. / Encéphalopathie induite par l'hypertension artérielle: aspects cliniques, radiologiques et thérapeutiques.

BACKGROUND: Neuroradiological features of hypertensive encephalopathy are not yet well-known. PATIENTS AND METHODS: The clinical manifestations, neuroradiological aspects and treatment of four patients suffering from hypertensive encephalopathy were studied; special attention was paid to manifestations presented by one patient which appeared representative of the usual manifestations of hypertensive encephalopathy. RESULTS: The main clinical features were visual disturbances (n = 4); altered consciousness (n = 2) and seizures (n = 3). Visual disturbances resulted from cortical lesions (n = 4) associated with optic nerve damage and retinopathy (n = 2). Cerebral imaging showed low density images (CT scan) and hypersignal (MRI, T2 sequence) located in parieto-occipital cortical ribbon and adjacent white matter from the first 24 hours following the onset of neurologic symptoms. In the studied patient, the abnormal images resolved within 1 month after the onset of the disease. Unilateral infarction of the anterior visual pathway affected two patients in whom: 1) hypertension remaining undetected for a long time was revealed by neurological signs; 2) visual impairment was preceded by an hypotensive episode induced by antihypertensive therapy. CONCLUSIONS: Neuroradiological features of hypertensive encephalopathy are useful in establishing the diagnosis. A gradual reduction of blood pressure could prevent the risk of visual complications.