Biomedical subjects

S Chiodo

Publications and source records attributed to S Chiodo.

4 recordsLinked to original sources

PubMed2006

LANL2DZ basis sets recontracted in the framework of density functional theory.

In this paper we report recontracted LANL2DZ basis sets for first-row transition metals. The valence-electron shell basis functions were recontracted using the PWP86 generalized gradient approximation functional and the hybrid B3LYP one. Starting from the original LANL2DZ basis sets a cyclic method was used in order to optimize variationally the contraction coefficients, while the contraction scheme was held fixed at the original one of the LANL2DZ basis functions. The performance of the recontracted basis sets was analyzed by direct comparison between calculated and experimental excitation and ionization energies. Results reported here compared with those obtained using the original basis sets show clearly an improvement in the reproduction of the corresponding experimental gaps.

Journal Article↗

PubMed2005

Newly developed basis sets for density functional calculations.

Optimized contracted Gaussian basis sets of double-zeta valence polarized (DZVP) quality for first-row transition metals are presented. The DZVP functions were optimized using the PWP86 generalized gradient approximation (GGA) functional and the B3LYP hybrid functional. For a careful analysis of the basis sets performance the transition metal atoms and cations excitation energies were calculated and compared with the experimental ones. The calculated values were also compared with those obtained using the previously available DZVP basis sets developed at the local-density functional level. Because the new basis sets work better than the previous ones, possible reasons of this behavior are analyzed. The newly developed basis sets also provide a good estimation of other atomic properties such as ionization energies.

Journal Article↗

PubMed1999

Landau-Kleffner syndrome (LKS): long-term follow-up and links with electrical status epilepticus during sleep (ESES).

We describe 11 patients affected by Landau-Kleffner syndrome (LKS) with a mean follow-up of 9 years and 8 months. EEG recordings during wakefulness, NREM and REM sleep showed a bitemporal electrical status epilepticus during sleep (BTESES) in all cases; four of them presented a shift from a BTESES towards an 'intercalated electrical status epilepticus during sleep' (IESES) accompanied by a global regression of cognitive and behavioural functions in 3/4 of cases. At the last observation, only 18.2% of cases presented a complete language recovery and mental retardation was evident in 63.6%. The prognosis of LKS in our cases may depend on the interaction of different negative factors such as onset of aphasia before 4 years, its duration for longer than 1 year, long-lasting duration and continuity without fluctuations of BTESES/IESES, probably preexisting mild speech delay. It is important for the prognosis to utilize antiepileptic treatment and possibly neurosurgical techniques to eliminate EEG paroxysmal abnormalities. At present, no similar cases with clinical-EEG evolution from LKS to electrical status epilepticus during sleep (ESES) have ever been described. Our observation demonstrates that LKS and ESES classified as different clinical-EEG syndromes represent two aspects of the same brain dysfunction and they may exist separately or pass one into the other with a change in the clinical-EEG picture. The common origin of the two syndromes is confirmed by recent functional brain imaging, neurophysiological and neurosurgical techniques.

Adolescent↗

PubMed1999

Posterior fossa malformations and epilepsy.

The association between posterior fossa malformations and epilepsy is rarely reported in the literature. We describe 54 cases with posterior fossa malformations, according to embryogenesis classification, divided into two groups on the basis of presence or absence of epilepsy. Epilepsy occurred in 22 cases (40.7%) and was not related to the type of posterior fossa malformation or to supratentorial cerebral lesions associated with the malformation. Familial antecedents for epilepsy and/or febrile convulsions influenced the presence of epilepsy in patients with posterior fossa malformations (P < .01). Epilepsy was mainly partial (77.3%); benign partial/generalized epilepsies and febrile convulsions occurred in 27.3% of cases. Seizures disappeared for 2 or more years at the end of follow-up in 36.4% of patients. Good epilepsy prognosis was not related to the age at onset of seizures, familial antecedents for epilepsy and/or febrile convulsions, supratentorial associated lesions, or age of patients at the last observation. Profound mental retardation prevailed in patients with epilepsy (P < .01), as did pathologic electroencephalograms (EEG) (P < .0001), with paroxysmal abnormalities (P < .001) and asymmetry (P < .01). In our 54 cases of posterior fossa malformation, we identified two risk factors for epilepsy: familial antecedents for epilepsy and/or febrile convulsions and the involvement of the cerebellum in the malformation.

Adolescent↗