Quantum confinement and electroluminescence in ultrathin silicon nanowires fabricated by a maskless etching technique.

We present a novel approach for the direct synthesis of ultrathin Si nanowires (NWs) exhibiting room temperature light emission. The synthesis is based on a wet etching process assisted by a metal thin film. The thickness-dependent morphology of the metal layer produces uncovered nanometer-size regions which act as precursor sites for NW formation. The process is cheap, fast, maskless and compatible with Si technology. Very dense arrays of long (several micrometers) and small (diameter of 5-9 nm) NWs have been synthesized. An efficient room temperature luminescence, visible with the naked eye, is observed when NWs are optically excited, exhibiting a blue-shift with decreasing NW size in agreement with quantum confinement effects. A prototype device based on Si NWs has been fabricated showing a strong and stable electroluminescence at low voltages. The relevance and the perspectives of the reported results are discussed, opening the route toward novel applications of Si NWs.

A mean field analysis of the O-H stretching Raman spectra in methanol/carbon tetrachloride mixtures.

The O-H stretching region of the Raman spectra obtained from methanol/carbon tetrachloride mixtures of different compositions is analyzed. The various components of the spectra associated with methanol molecules with different H-binding states (i.e., non-H-bonded, chain-end, and doubly bonded) are quantitatively related with the alcohol cluster distribution derived by means of a simple lattice model. This comparison allows for the estimate of the mean overall hydrogen bonding energy by means of a best fitting procedure on the Raman data obtained at low-to-moderate alcohol contents; the solvation energy contribution of carbon tetrachloride is then also included. The result (approximately 3 kcal/mol) is found to be in agreement with the estimates from calorimetric and dielectric measurements.

Arithmetic calculation, short-term memory, and language performance in children with specific language impairment: a 5-year follow-up.

A 5-year follow-up of the arithmetic calculation abilities of low-income children with specific language impairment (SLI) is reported. The performance of fourth- and fifth-grade children with SLI was compared with that of typically developing low-income peers and with younger, typically developing low-income children. Short-term memory, language, and arithmetic calculation abilities were assessed. Compared to their age-matched peers, the SLI group exhibited low scores on a number recall task, a marked difficulty with mathematical calculation under timed conditions, and numerous errors when retrieving rote math facts such as 7 x 6 =. Although children with SLI made more written calculation errors than their age-matched peers, they did not differ in the type of errors made. However, strategies used to solve written calculation differed among the groups. Rather than use automatic math fact retrieval, children with SLI were more likely to use counting strategies to solve calculation problems. These findings offer further evidence that children with SLI have difficulty with rote memory. The findings also document the real-world consequences of slow, inefficient memory retrieval in children with SLI.

The effect of presentation rate on serial memory in young children with specific language impairment.

The study examined the serial memory ability of a group of preschool children with specific language impairment (SLI) who were compared to age and language control groups. The children were asked to recognize serial patterns under short and long presentation durations. The subjects were presented with images of common objects (that appeared to be easily recoded into a phonological form) and iconic images of scribble drawings and unfamiliar faces (that did not appear to invite recoding). Under long presentation conditions, the performance of children with SLI resembled that of their age-matched peers on all 3 types of tasks. However, under short presentation conditions, children with SLI performed worse than their age-matched peers on all 3 tasks (and similarly to their language-matched peers). The performance of the children with SLI declined dramatically in all conditions when the items were presented for a brief period. If the serial memory deficits of young children with SLI were specific to phonological processing, their performance on recognizing the pattern of common objects should have been impaired, but not their performance with other visual tasks that are less likely to be recoded. Instead, serial memory in children with SLI was affected by presentation duration across tasks. The findings suggest that recognizing serial patterns is dependent, in part, on the speed of processing serial information. The findings are discussed in relation to models of limited capacity processing.

Vasculitic neuropathy associated with beta-haemolytic streptococcal infection: a case report.

Vasculitic neuropathy is rarely associated with a definable collagen vascular disease. Peripheral neuropathy may be the sole manifestation of vasculitis, and the aetiology is frequently unknown. We here report the case of a woman presenting mononeuritis multiplex, whose sural nerve biopsy was diagnostic of necrotizing vasculitis. There was serological evidence of preceding beta-haemolytic streptococcal infection. We assume that vasculitic neuropathy can be included among the possible sequelae of streptococcal infections.

Learning a new poem: memory for connected speech and phonological awareness in low-income children with and without specific language impairment.

This research examined rote memory for connected speech in low-income children with and without specific language impairment (SLI). Sixteen children with SLI were matched to 16 typically developing children on nonverbal cognition and 16 younger, typically developing peers on language measures. The children learned a new poem under four presentation conditions: with or without accompanying hand motions related to the poem or with or without a simple melody. Compared with their cognitive and language peers, children with SLI had significantly more difficulty learning the poem under all presentation conditions. Furthermore, when asked to recite the poem after a 2-day delay, the performance of the children with SLI was significantly better in the poem with accompanying hand motions condition. It appears that learning the poem with an additional modality aids recall for children with SLI. Phonological awareness task findings revealed that all the children had difficulty with such tasks. However, compared with the children in the cognitive-matched peer group, the children with SLI and their language-matched peers had significantly more difficulty finding pairs of words that rhymed or words that began with the same initial sound. Intervention issues and the relationship between phonological processing and serial memory in children with SLI are discussed.

Mathematical abilities of children with specific language impairment: a 2-year follow-up.

A 2-year follow-up of the mathematical abilities of young children with specific language impairment (SLI) is reported. To detect the nature of the difficulties children with SLI exhibited in mathematics, the first- and second-grade children's performance was compared to mental age and language age comparison groups of typically developing children on a series of tasks that examined conceptual, procedural, and declarative knowledge of mathematics. Despite displaying knowledge of many conceptual aspects of mathematics such as counting plates of cookies to decide which plate had "more," children with SLI displayed marked difficulty with declarative mathematical knowledge that required an immediate response such as rote counting to fifty, counting by 10's, reciting numerals backwards from 20, and addition facts such as 2 + 2 =?. Moreover, children with SLI performed similarly to their cognitive peers on mathematical tasks that allowed children to use actual objects to count and on math problems that did not require them to exceed the sequence of numbers that they knew well. These findings offer further evidence that storage and/or retrieval of rote sequential material is particularly cumbersome for children with SLI.

Tracking children from poverty at risk for specific language impairment: a 3-year longitudinal study.

A 3-year longitudinal study of the language performance of children from poverty was designed to address the problem of separating children with a specific language impairment (SLI) from low-scoring normal children in the borderline area on the continuum of language performance where normal ends and abnormal begins. Two approaches to definition were compared: an experimental approach (using story-retelling, rote-memory ability, and invented-morpheme learning) and a traditional approach (using standardized-test discrepancy scores). Results indicated that 6 of 34 children tracked from kindergarten through second grade appeared to be SLI at the end of the study. The best kindergarten predictor for the outcome status of these 6 children was a combination of the score on the Oral Vocabulary subtest of the TOLD-2P and the score on a combination of the experimental tasks. The best single kindergarten predictor of the academic status of the 15 children in the study who received academic remediation was story-retelling. Children's scores on the experimental and standardized tests of language performance and nonverbal intelligence were profiled over the 3 years of the study, and patterns of change in many instances reveal the lifting of the early influences of poverty.

The counting abilities of children with specific language impairment: a comparison of oral and gestural tasks.

This study examined the counting abilities of preschool children with specific language impairment compared to language-matched and mental-age-matched peers. In order to determine the nature of the difficulties SLI children exhibited in counting, the subjects participated in a series of oral counting tasks and a series of gestural tasks that used an invented counting system based on pointing to body parts. Despite demonstrating knowledge of many of the rules associated with counting, SLI preschool children displayed marked difficulty in counting objects. On oral counting tasks, they showed difficulty with rote counting, displayed a limited repertoire of number terms, and miscounted sets of objects. However, on gestural counting tasks, SLI children's performance was significantly better. These findings suggest that SLI children have a specific difficulty with the rote sequential aspect of learning number words.

Relation between mental age and vocabulary development among children with mild mental retardation.

An investigation of the relation between lexical knowledge and mental age (MA) in elementary school-age children with mild mental retardation was conducted. Lexical knowledge was assessed using the Peabody Picture Vocabulary Test-Revised (PPVT-R) and the Boehm Test of Basic Concepts. Items on the PPVT-R focus on labels for objects and events; items on the Boehm focus on relational terms. Mental age was measured via the Columbia Mental Maturity Scale. Results indicated that the relation between lexical knowledge and MA depended upon the nature of the vocabulary test: The correlation between the Boehm and MA was significantly higher than that between the PPVT-R and MA, suggesting that for this population, MA is more strongly related to knowledge of abstract relational terms than to knowledge of labels for objects and events. The latter may be more open to the influence of differential language experience.

Benign intracranial hypertension associated with HIV infection.

We report the case of a 24-year-old woman with HIV-seropositivity, who developed a clinical picture of pseudotumor cerebri, an association not previously described. The patient improved with the use of acetazolamide. We suggest the possible existence of this disorder in HIV-infected patients with persistent headaches, visual deficits and/or extraocular muscle palsies.

[Diagnostic potentials and limits of nuclear magnetic resonance (NMR) in cerebral neoplastic pathology]. / Possibilità diagnostiche e limiti della risonanza magnetica nucleare (RMN) nella patologia neoplastica cerebrale.

The current possibilities and limitations of NMR in the diagnosis of brain tumours are described with emphasis on the need to consider intrinsic tumoural variations, peritumoural oedema and the mass effect. It is concluded that MR should currently be considered complementary to the CAT scan.

[Electric stimulation and neuromuscular diseases. Effects on denervated and dystrophic muscle]. / Elettrostimolazione e malattie neuromuscolari. Effetti sul muscolo denervato e sul muscolo distrofico.

The literature on the effects of electrical stimulation on denervated and dystrophic muscles is reviewed. Analysis of the information supplied suggests that denervated muscles of experimental animals may benefit from the treatment that cannot be used on human patients due to technical limitations. However electrical stimulation can be used in the treatment of dystrophic muscles in human.

[Steinert's myotonic dystrophy. Attempts at therapy]. / La distrofia miotonica di Steinert. Tentativi di terapia.

Myotonic dystrophy or Steinert's disease is an autosomal dominant hereditary disease affecting the entire system. Apart from the myotonic phenomenon it involves muscular atrophy, endocrine disorders, baldness, cardiac arrhythmias, hyperglycaemia, cataracts. Over the years a number of drugs have been tried with results on the myotonia that are still debated. They include quinine, corticosteroids, L-DOPA, potassium-binding resins, procainamide, phenytoin, diphenylhydantoin, N-propylajmaline, dantrolene sodium, carbamazepine, imipramine, baclofen, mexiletine. It is emphasised that only the identification of the biochemical defect involved in the disease will permit any efficient treatment of its symptoms or causes.

[Facial paralysis in newborn infants and children. Clinical and therapeutic aspects]. / Le paralisi facciali nel neonato e nel bambino. Aspetti clinici e terapeutici.

Paralysis of the facial nerve in newborns and infants is described with a list of the various types including Bell's idiopathic paralysis, forms caused by congenital malformations and labour traumas, fractures of the temporal bone, tumours, infections and high blood pressure. Current approaches to treatment including physiotherapy, pharmacological and surgical treatment are then described.

[Evaluation of visual evoked potentials in chronic Parkinson disease patients]. / Valutazione dei potenziali evocati visivi in parkinsoniani cronici.

The P-100 latency of the evoked visual potentials in 20 cases of idiopathic Parkinson's disease were examined. As indicated in earlier studies, P-100 latency was significantly higher in Parkinson patients than in healthy controls. The hypotheses about the pathogenesis of such anomalies are then discussed.

Cerebral blood flow in minor cerebral contusion.

Seventeen patients with minor cerebral contusion were selected from a series of patients with head injuries of various severity, who had undergone repeat evaluations of the regional cerebral blood flow. The mean global flow (expressed as mean global initial slope index) on early examination was found to be significantly lower, compared with that recorded in healthy volunteers. A tendency towards the recovery of higher flow values was apparent in repeat evaluations that were performed several weeks after the injury. Interhemispheric asymmetries of flow were a common occurrence, with lower perfusion and reduced attenuation values on computed tomography scans being, however, in good agreement only in approximately half of the cases.

[Exploration of the tubero-hypophyseal dopaminergic system in patients with chronic parkinsonism during chronic treatment with L-DOPA]. / Esplorazione del sistema T.I.D.A. in parkinsoniani cronici in trattamento cronico con L-Dopa.

The changes in prolactin release induced by acute doses of L-Dopa + benserazide (250 mg) were analysed in Parkinson disease patients undergoing various drug treatments. The results obtained indicate a highly significant increase in prolactinaemia after 60 minutes in a patient undergoing chronic L-Dopa + benserazide therapy, compared to both healthy subjects and patients receiving other drugs. A patient receiving L-Dopa with no inhibitor also showed significantly high prolactinaemia levels after 180 mins. This confirms the hypothesis that elderly Parkinson patients suffer from chronic denervation of the hypothalamic receptors even when no Dopa-decarboxylase inhibitor is present.