Selected Topics in High Energy Semi-Exclusive Electro-Nuclear Reactions

We review the present status of the theory of high energy reactions with semi-exclusive nucleon electro-production from nuclear targets. We demonstrate how the increase of transferred energies in these reactions opens a complete new window in studying the microscopic nuclear structure at small distances. The simplifications in theoretical descriptions associated with the increase of the energies are discussed. The theoretical framework for calculation of high energy nuclear reactions based on the effective Feynman diagram rules is described in details. The result of this approach is the generalized eikonal approximation (GEA), which is reduced to Glauber approximation when nucleon recoil is neglected. The method of GEA is demonstrated in the calculation of high energy electro-disintegration of the deuteron and A=3 targets. Subsequently we generalize the obtained formulae for A>3 nuclei. The relation of GEA to the Glauber theory is analyzed. Then based on the GEA framework we discuss some of the phenomena which can be studied in exclusive reactions, these are: nuclear transparency and short-range correlations in nuclei. We illustrate how light-cone dynamics of high-energy scattering emerge naturally in high energy electro-nuclear reactions.Comment: LaTex file with 51 pages and 23 eps figure

An enigmatic hypoplastic defect of the maxillary lateral incisor in recent and fossil orangutans from Sumatra (Pongo abelii) and Borneo (Pongo pygmaeus)

Developmental dental pathologies provide insight into health of primates during ontogeny, and are particularly useful for elucidating the environment in which extant and extinct primates matured. Our aim is to evaluate whether the prevalence of an unusual dental defect on the mesiolabial enamel of the upper lateral incisor, thought to reflect dental crowding during maturation, is lesser in female orangutans, with their smaller teeth, than in males; and in Sumatran orangutans, from more optimal developmental habitats, than in those from Borneo. Our sample includes 49 Pongo pygmaeus (87 teeth), 21 P. abelii (38 teeth), Late Pleistocene paleo-orangutans from Sumatra and Vietnam (67 teeth), Late Miocene catarrhines Lufengpithecus lufengensis (2 teeth), and Anapithecus hernyaki (7 teeth). Methods include micro-CT scans, radiography, and dental metrics of anterior teeth. We observed fenestration between incisor crypts and marked crowding of unerupted crowns, which could allow tooth-to-tooth contact. Tooth size does not differ significantly in animals with or without the defect, implicating undergrowth of the jaw as the proximate cause of dental crowding and defect presence. Male orangutans from both islands show more defects than do females. The defect is significantly more common in Bornean orangutans (71 %) compared to Sumatran (29 %). Prevalence among fossil forms falls between these extremes, except that all five individual Anapithecus show one or both incisors with the defect. We conclude that maxillary lateral incisor defect is a common developmental pathology of apes that is minimized in optimal habitats and that such evidence can be used to infer habitat quality in extant and fossil apes

Avaliação comparativa do espaçamento anterior em nipo-brasileiros e leucodermas, na dentição decídua Comparative assessment of anterior spacing in Japanese-Brazilian and white children in the primary dentition

OBJETIVO: avaliar comparativamente a prevalência das características de espaçamento anterior em nipo-brasileiros e leucodermas, na dentição decídua. MÉTODOS: duas amostras de crianças com 2 a 6 anos de idade foram selecionadas: 405 nipo-brasileiros de 36 escolas do estado de São Paulo e 510 leucodermas de 11 instituições públicas da cidade de São Paulo. As variantes oclusais foram classificadas em quatro categorias, nas arcadas superior e inferior: espaçamento generalizado; somente espaços primatas; ausência de espaços; e apinhamento. Foi aplicada regressão logística para análise do efeito dos fatores idade, sexo e grupo étnico sobre a prevalência das características oclusais (&#945; = 0,05). RESULTADOS: em nipo-brasileiros, o espaçamento generalizado foi a característica mais prevalente nas arcadas superior (46,2%) e inferior (53,3%). A frequência dos espaços primatas foi maior na arcada superior (28,2% versus 15,3%). Para a ausência de espaços (21,7-26,4%) e o apinhamento (4,0-4,9%), a variação entre as arcadas foi relativamente pequena. Em leucodermas, a ausência de espaços e a presença exclusiva dos primatas evidenciaram distribuição similar à observada nos nipo-brasileiros. O espaçamento generalizado foi diagnosticado em aproximadamente 50% das arcadas. A prevalência de apinhamento foi maior na arcada inferior (12,8% versus 3,9%). O único modelo de regressão logística que apresentou algum fator significativo foi o ajustado para a prevalência de apinhamento. Apenas o fator racial foi significativo (p < 0,001). CONCLUSÃO: sugere-se que as características de espaçamento anterior, na dentição decídua, não estariam condicionadas à idade ou ao sexo. Contudo, leucodermas teriam chances 2,8 vezes maiores de apresentar apinhamento na arcada inferior, em comparação aos nipo-brasileiros.<br>OBJECTIVE: To carry out a comparative evaluation of the prevalence of anterior spacing characteristics in Japanese-Brazilian and white children in primary dentition. METHODS: Two selected samples of children aged 2-6 years were: 405 Japanese-Brazilians from 36 schools in the State of São Paulo and 510 white children from 11 public institutions in São Paulo city. The spacing features in the maxillary and mandibular arches were assigned to four categories: generalized spacing; only primate spaces; no spacing; and crowding. Logistic regression was used to analyze the effect of age, gender and ethnic group on the prevalence of the occlusal characteristics (&#945;=0.05). RESULTS: In Japanese-Brazilians, generalized spacing was the most prevalent trait in the maxillary (46.2%) and mandibular (53.3%) arches. The frequency of primate spaces was higher in the maxillary arch (28.2% versus 15.3%). Concerning no spacing (21.7-26.4%) and crowding (4.0-4.9%), the variation between arches was relatively small. In white children, no spacing and exclusive presence of primate spaces showed distributions similar to that observed in Japanese-Brazilians. Generalized spacing was diagnosed in approximately 50% of the arches. Crowding prevalence was higher in the mandibular arch (12.8% versus 3.9%). The regression model adjusted for crowding prevalence was the only significant one. Only racial factor was significant (p<0.001). CONCLUSION: It may be suggested that anterior spacing features in primary dentition would not be influenced by age or gender. Nevertheless, white children would have 2.8 times more chances of presenting crowding in the mandibular arch, in comparison with Japanese-Brazilians