Biomedical subjects

A Sperduti

Publications and source records attributed to A Sperduti.

4 recordsLinked to original sources

PubMed2000

Discriminant pattern recognition using transformation-invariant neurons.

To overcome the problem of invariant pattern recognition, Simard, LeCun, and Denker (1993) proposed a successful nearest-neighbor approach based on tangent distance, attaining state-of-the-art accuracy. Since this approach needs great computational and memory effort, Hastie, Simard, and Säckinger (1995) proposed an algorithm (HSS) based on singular value decomposition (SVD), for the generation of nondiscriminant tangent models. In this article we propose a different approach, based on a gradient-descent constructive algorithm, called TD-Neuron, that develops discriminant models. We present as well comparative results of our constructive algorithm versus HSS and learning vector quantization (LVQ) algorithms. Specifically, we tested the HSS algorithm using both the original version based on the two-sided tangent distance and a new version based on the one-sided tangent distance. Empirical results over the NIST-3 database show that the TD-Neuron is superior to both SVD- and LVQ-based algorithms, since it reaches a better trade-off between error and rejection.

Algorithms↗

PubMed1994

Intra- and interobserver concordance in scoring Harris lines: a test on bone sections and radiographs.

Little attention has been devoted to assessing the reproducibility of (paleo) pathological observations. Harris lines (HL) are among the markers most used to determine chronology of stresses suffered during growth. Nevertheless, their scoring entails remarkable methodological difficulty. Bone sections (S) and radiographs (R) of 29 adult tibiae of archeological provenance (medieval) were scored for HL by five observers. At regular intervals of time, each observer gave two independent counts on both series. Results show a) a substantial interobserver disagreement of HL estimates for both sectional and radiographic records, and b) a high level of intraobserver error.

Adult↗

PubMed1991

Behavior-induced auditory exostoses in imperial Roman society: evidence from coeval urban and rural communities near Rome.

Presence and features of auditory exostoses were investigated in two cranial samples of Roman imperial age (1st-3rd century A.D.). The skeletal material comes from the necropolises of Portus (Isola Sacra) and Lucus Feroniae (Via Capenate), two towns along the Tevere River, in close relation with the social and economic life of Rome. Deep-rooted differences between the human communities represented by the skeletal samples (83 and 71 individuals, respectively, in this study) are documented both historically and archaeologically. The results show lack of exostoses in the female sex, a negligible incidence among the males of Lucus Feroniae, but a high frequency in the male sample from Isola Sacra (31.3%). Auditory exostoses are commonly recognised as localized hyperplastic growths of predominantly acquired origin. Features of the exostoses found in the male crania from Isola Sacra (particularly in relation to the age at death of the affected individuals) support this view. Furthermore, several clinical and anthropological studies have pointed out close links between the occurrence of auditory exostoses and prolonged cold water exposure, generally due to the practice of aquatic sports, or to working activities involving water contact or diving. In this perspective, the differences observed between the two Roman populations and between the sexes (in Isola Sacra) appear to result from different social habits: the middle class population of Portus habitually used thermal baths, whereas it is probable that thermae were seldom frequented (if at all) by the Lucus Feroniae population represented in the necropolis (mostly composed by slaves or freedmen farm laborers).(ABSTRACT TRUNCATED AT 250 WORDS)

Baths↗

PubMedDate not supplied

Analysis of the internal representations developed by neural networks for structures applied to quantitative structure--activity relationship studies of benzodiazepines.

An application of recursive cascade correlation (CC) neural networks to quantitative structure-activity relationship (QSAR) studies is presented, with emphasis on the study of the internal representations developed by the neural networks. Recursive CC is a neural network model recently proposed for the processing of structured data. It allows the direct handling of chemical compounds as labeled ordered directed graphs, and constitutes a novel approach to QSAR. The adopted representation of molecular structure captures, in a quite general and flexible way, significant topological aspects and chemical functionalities for each specific class of molecules showing a particular chemical reactivity or biological activity. A class of 1,4-benzodiazepin-2-ones is analyzed by the proposed approach. It compares favorably versus the traditional QSAR treatment based on equations. To show the ability of the model in capturing most of the structural features that account for the biological activity, the internal representations developed by the networks are analyzed by principal component analysis. This analysis shows that the networks are able to discover relevant structural features just on the basis of the association between the molecular morphology and the target property (affinity).

Benzodiazepines↗