AVALIAÇÃO DAS ALTERAÇÕES DENTOESQUELÉTICAS DE PACIENTES COM MÁ OCLUSÃO DE CLASSE II DE ANGLE, TRATADOS COM O APARELHO REGULADOR DE FUNÇÃO DE FRÄNKEL (RF-2).

Esta pesquisa objetivou estudar retrospectivamente por meio de radiografias em norma frontal e modelos de gesso as alterações dentoesqueléticas de pacientes com má oclusão de Classe II, 1ª divisão, divididos em dois grupos: Grupo Tratado, constituído de 28 pacientes, sendo 13 pacientes do sexo masculino e 15 do sexo feminino, tratados com aparelho regulador de função de Fränkel - 2 (RF-2), por um período ativo de 1,5 anos; Grupo Controle: constituído de 28 pacientes, sendo 12 do sexo masculino e 16 do sexo feminino, sem nenhum tipo de tratamento durante o acompanhamento longitudinal de 1,5 anos. A amostra deste estudo consistiu de 112 telerradiografias em norma frontal e 112 pares de modelos de gesso, 56 obtidos ao início (T1) e 56 ao final da observação (T2). Após a análise estatística das mensurações obtidas, concluiu- se que houve como resultado alterações estatisticamente significantes em todas as medidas analisadas e o aparelho RF-2 teve atuação direta nas variáveis: distância intermolares superio res e inferiores (radiografias e modelos),profundidade palatina, largura maxilar e altura facial ântero-inferior.

Investigating high-achieving sixth grade students' erroneous answers on the angle concept in Yozgat

The angle concept is a multifaceted concept having static and dynamic definitions. The static definition of the angle refers to “the space between two rays” or “the intersection of two rays at the same end point” (Mitchelmore & White, 1998), whereas the dynamic definition of the angle concept highlights that the size of angle is the amount of rotation in direction (Fyhn, 2006). Since both definitions represent two diverse situations and have unique limitations (Henderson & Taimina, 2005), students may hold misconceptions about the angle concept. In this regard, the aim of this research was to explore high achievers’ knowledge regarding the definition of the angle concept as well as to investigate their erroneous answers on the angle concept.

104 grade 6 students drawn from four well-established elementary schools of Yozgat, Turkey were participated in this research. All participants were selected via a purposive sampling method and their mathematics grades were 4 or 5 out of 5, and. Data were collected through four questions prepared by considering the learning competencies set out in the grade 6 curriculum in Turkey and the findings of previous studies whose purposes were to identify students’ misconceptions of the angle concept. The findings were analyzed by two researchers, and their inter-rater agreement was calculated as 0.91, or almost perfect. Thereafter, coding discrepancies were resolved, and consensus was established.

The angle concept is a multifaceted concept having static and dynamic definitions.The static definition of the angle refers to “the space between two rays” or“the intersection of two rays at the same end point” (Mitchelmore & White, 1998), whereas the dynamicdefinition of the angle concept highlights that the size of angle is the amountof rotation in direction (Fyhn, 2006). Since both definitionsrepresent two diverse situations and have unique limitations (Henderson & Taimina, 2005), students may holdmisconceptions about the angle concept. In this regard, the aim of thisresearch was to explore high achievers’ knowledge regarding the definition ofthe angle concept as well as to investigate their erroneous answers on theangle concept.

class="MsoNormal" style="text-align:justify;text-indent:0cm;line-height:normal">104grade 6 students drawn from four well-established elementary schools of Yozgat,Turkey were participated in this research. All participants were selected via a purposive sampling method and their mathematics grades were 4 or 5 out of 5,and. Data were collected through four questions prepared by considering the learning competencies set out in the grade 6 curriculum in Turkey and the findings of previous studies whose purposes were to identify students’ misconceptions of the angle concept. The findings were analyzed by two researchers, and their inter-rater agreement was calculated as 0.91, or almost perfect. Thereafter, coding discrepancies were resolved, and consensus was established.

class="MsoNormal" style="text-align:justify;text-indent:0cm;line-height:normal">In the first question, students were asked to answer a multiple choice questions consisting of two statics definitions and one dynamic definition of the angle concept. Only 38 of 104 students were able to recognize these three definitions. Likewise, Mitchelmore and White (1998) investigated that less than10% of grade 4 students knew the dynamic definition of the angle concept. Additionally,the purpose of the second question was to figure out how well students could recognize 0-degree angle. We found that 49 of 104 students were unable to recognize MXW as an angle. While 6 students indicated that the size of MXW is0, other 6 students revealed that the size of MXW is 360. Therefore, 12 of 104students correctly answered this questions. On the other hand, 28 of 104students recognized the MXW angle as 180-degree angle. This finding demonstrated that these students have difficulties in naming the angles.Moreover, the third question consisted of three concentric circles with center O and two radiuses of the outer circle, and the intersection of the radiuses with these circles were named. Then, students were asked to compare the size of AOB, GOD and EOF angles. Only 36 of 104 students answered correctly by indicating that all three angles are equal, whereas 68 of 104 students incorrectly responded this question by revealing AOB<GOD< EOF. These students erroneously thought the size of the angle is related to either the size of the arc marking the angle or the area between the arms of the angle and the arc marking angle. These two erroneous strategies for determining the size of angles have been found by a few studies (Clausen-May,2008; Devichi & Munier, 2013; Kim & Lee, 2014; Mithcelmore, 1998;Wilson & Adams, 1992). The last question, whose aim was to determine how well students can adapt theangle concept to real life, consisted of an observer and a barrier, and students were asked to color the hidden area behind the barrier. Only 2 of 104students correctly responded this question, whereas 19 of 104 students drew rays from the observer to both sides of the barrier, and colored the area covered by the rays, the observer and barrier. While 35 of 104 students just colored behind the barrier without using any strategies, 33 of 104 students constructed two perpendicular lines at the both end of the barrier, and colored behind the barrier. Similarly, Munier, Devinci and Merle (2008) found that this incorrect strategy was used by 27% of students.

class="MsoNormal" style="text-align:justify;text-indent:0cm;line-height:normal">Consequently, we found that although the participants in this study were high achievers, they still held several misconceptions on the angle concept and had difficulties in adapting the angle concept to real life.

class="MsoNormal" style="text-align:justify;text-indent:0cm;line-height:normal">Keywords: the angle concept;misconceptions; erroneous answers; high achievers

class="MsoBibliography" style="text-align:justify;line-height:normal">Clausen-May, T. (2008). AnotherAngle on Angles. Australian Primary Mathematics Classroom, 13(1),4–8.

class="MsoBibliography" style="text-align:justify;line-height:normal">Devichi, C., & Munier, V.(2013). About the concept of angle in elementary school: Misconceptions andteaching sequences. The Journal of Mathematical Behavior, 32(1),1–19. http://doi.org/10.1016/j.jmathb.2012.10.001

class="MsoBibliography" style="text-align:justify;line-height:normal">Fyhn, A. B. (2006). A climbinggirl’s reflections about angles. The Journal of Mathematical Behavior, 25(2),91–102. http://doi.org/10.1016/j.jmathb.2006.02.004

class="MsoBibliography" style="text-align:justify;line-height:normal">Henderson, D. W., & Taimina,D. (2005). Experiencing geometry: Euclidean and non-Euclidean with history(3rd ed.). New York, USA: Prentice Hall.

class="MsoBibliography" style="text-align:justify;line-height:normal">Kim, O.-K., & Lee, J. H.(2014). Representations of Angle and Lesson Organization in Korean and AmericanElementary Mathematics Curriculum Programs. KAERA Research Forum, 1(3),28–37.

class="MsoBibliography" style="text-align:justify;line-height:normal">Mitchelmore, M. C., & White,P. (1998). Development of angle concepts: A framework for research. MathematicsEducation Research Journal, 10(3), 4–27.

class="MsoBibliography" style="text-align:justify;line-height:normal">Mithcelmore, M. C. (1998). Youngstudents’ concepts of turning and angle. Cognition and Instruction, 16(3),265–284.

class="MsoBibliography" style="text-align:justify;line-height:normal">Munier, V., Devichi, C., &Merle, H. (2008). A Physical Situation as a Way to Teach Angle. TeachingChildren Mathematics, 14(7), 402–407.

class="MsoBibliography" style="text-align:justify;line-height:normal">Wilson, P. S., & Adams, V.M. (1992). A Dynamic Way to Teach Angle and Angle Measure. ArithmeticTeacher, 39(5), 6–13.

Bottle feeding, increased overjet and Class 2 primary canine relationship: is there any association?

The aim of this study was to investigate the association between bottle feeding and prevalence rates of increased overjet and Class 2 primary canine relationship. The sample consisted of 911 children (461 boys, 450 girls) aged 3 (13.9%), 4 (40.8%), 5 (34%) and 6 (11.3%) years, with complete primary dentition. Information about nutritive and nonnutritive (pacifier and/or digit) sucking habits was collected through questionnaires. Three calibrated dentists (κ: 0.9-1.0 and Rs > 0.90) performed the clinical assessments. The children were divided into four groups: G1 - not bottle-fed; G2 - exclusively bottle-fed; G3 - breast- and bottle-fed, bottle feeding ceased before 3 years of age; and G4 - breast- and bottle-fed, bottle feeding ceased between 3 and 4 years of age. Associations between nutritive and nonnutritive sucking behaviors and the malocclusions studied were analyzed by multiple binary logistic regression (α= 0.05). The frequencies of increased overjet were: 25.3% (G1), 38.8% (G2), 39.2% (G3) and 47.8% (G4). The percentages of Class 2 canine relationship were: 27.9% (G1), 48.8% (G2), 43.4% (G3) and 43% (G4). No significant effect of bottle feeding was found. The chances of diagnosing increased overjet (O.R. = 4.42, p < 0.001) and Class 2 canine relationship (O.R. = 4.02, p < 0.001) were greater for children with pacifier and/or digit-sucking habits, compared to those without a history of nonnutritive sucking behavior. It may be suggested that bottle feeding alone is not directly associated with higher prevalence rates of increased overjet and Class 2 canine relationship in the primary dentition.

Differential expression of 12 histone deacetylase (HDAC) genes in astrocytomas and normal brain tissue: class II and IV are hypoexpressed in glioblastomas

Background: Glioblastoma is the most lethal primary malignant brain tumor. Although considerable progress has been made in the treatment of this aggressive tumor, the clinical outcome for patients remains poor. Histone deacetylases (HDACs) are recognized as promising targets for cancer treatment. In the past several years, HDAC inhibitors (HDACis) have been used as radiosensitizers in glioblastoma treatment. However, no study has demonstrated the status of global HDAC expression in gliomas and its possible correlation to the use of HDACis. The purpose of this study was to evaluate and compare mRNA and protein levels of class I, II and IV of HDACs in low grade and high grade astrocytomas and normal brain tissue and to correlate the findings with the malignancy in astrocytomas. Methods: Forty-three microdissected patient tumor samples were evaluated. The histopathologic diagnoses were 20 low-grade gliomas (13 grade I and 7 grade II) and 23 high-grade gliomas (5 grade III and 18 glioblastomas). Eleven normal cerebral tissue samples were also analyzed (54 total samples analyzed). mRNA expression of class I, II, and IV HDACs was studied by quantitative real-time polymerase chain reaction and normalized to the housekeeping gene beta-glucuronidase. Protein levels were evaluated by western blotting. Results: We found that mRNA levels of class II and IV HDACs were downregulated in glioblastomas compared to low-grade astrocytomas and normal brain tissue (7 in 8 genes, p < 0.05). The protein levels of class II HDAC9 were also lower in high-grade astrocytomas than in low-grade astrocytomas and normal brain tissue. Additionally, we found that histone H3 (but not histone H4) was more acetylated in glioblastomas than normal brain tissue. Conclusion: Our study establishes a negative correlation between HDAC gene expression and the glioma grade suggesting that class II and IV HDACs might play an important role in glioma malignancy. Evaluation of histone acetylation levels showed that histone H3 is more acetylated in glioblastomas than normal brain tissue confirming the downregulation of HDAC mRNA in glioblastomas.

Can metal complexes serve as hypoxia activated prodrugs? Investigations of a Co(III) complex of the MMP inhibitor marimastat

For many years proof that the hypoxic nature of malignant tumours can be used to selectively target anticancer drugs has been sought. Several classes of potential redox activated anticancer drugs have been developed to take advantage of the reducing environment resulting from the hypoxia. Drug complexes with redox active metal centres as carriers have been investigated, but have largely been employed with cytotoxic drugs that require release of the drug intracellularly, complicating the design of such complexes. MMP inhibitors, a new class of anticancer drug, conversely act in the extracellular environment and we have investigated inhibitor complexes with several redox active transition metals. Marimastat is an MMP inhibitor with potent in-vitro antimetastatic activity and was recently in Phase III clinical trials for a variety of cancer types. We have synthesised a Co(II1) complex of marimastat incorporating the tetradentate ligand tpa (tris(2-methylpyridyl)amine) as a carrier ligand. The complex was structurally characterised in the solid state by single crystal X-ray diffraction, the first example of a crystal structure containing marimastat. 2D COSY and NOESY NMR spectra showed that the complex exists in two isomeric forms in solution, corresponding to the cis and trans isomers yet only crystallises in one of these forms. Biological testing of the complex in mice with 4T1.2 tumours showed interesting and unexpected outcomes. Initial results of the tumour growth inhibition study showed that a significant inhibition of growth was exhibited by the complex over the free inhibitor and the control. However, the metastatic potential of both free marimastat and the complex were higher than the control indicating likely problems with the experimental protocol. Further experiments are needed to determine the potential of such complexes as hypoxia activated prodrugs but there appears at least to be some promise.

Metabolic syndrome determinants in an urban population from Brazil: Social class and gender-specific interaction

Introduction: The metabolic syndrome (MS) is characterized by multiple cardiovascular risk factors such as central obesity, arterial hypertension, dislipidemia and hyperinsulinemia and is associated with a higher incidence of cardiovascular events and mortality. The aim of the present work is to describe the prevalence of MS in an urban population from a highly admixed developing country and to characterize the different correlations between this diagnosis, cardiovascular risk factors and demographic variables distributed in this population. Materials and methods: A cross-sectional study of risk factors for cardiovascular diseases was performed in the urban population of Vitoria, Brazil (n= 1507). Major cardiovascular risk factors such as smoking habits, alcohol intake, amount of physical activity, diabetes and hypertension were inquired. Blood biochemical assays were performed by standard techniques in 12 h fasting blood sample and Metabolic Syndrome (MS) was characterizes following the ATP III criteria. Results: The analysis of 1507 individuals showed a 25.43% general prevalence of MS without any significant difference between sexes, but a clear relation of the prevalence with progressing age (p=<0.0001). Even though both sexes showed similar prevalence rates, distribution of risk factors that defined MS was different between men and women, with the prevalence of hypertension, fasting hyperglycemia and hypertriglyceridemia being higher in men. Race was not an important risk factor for MS in this population as opposed to social economic class that was highly associated with the risk of MS in women as their social class was lower, but not in men. Conclusion: This cross-sectional study from a large urban population in Brazil showed a high general prevalence of MS (25.4%), which is increased as the population becomes older (especially in women) and poorer. Although prevalence was very similar in both genders, the frequency of components defining the syndrome varied greatly amongst them. In particular, a significant interaction between gender and social class was observed and may shed light in our understanding of the complex interplay between demographic and biological risk factors for metabolic syndrome. (C) 2007 Elsevier Ireland Ltd. All rights reserved.

Major histocompatibility complex (MHC) class II-positive dendritic cells in the rat iris - In situ development from MHC class II-negative precursors

Purpose. To examine the postnatal development of major histocompatibility complex (MHC) class II-positive dendritic cells (DC) in the iris of the normal rat eye. Methods. Single-and double-color immunomorphologic studies were performed on whole mounts prepared from rat iris taken at selected postnatal ages (2 to 3 days to 78 weeks). Immunopositive cells were enumerated, using a quantitative light microscope, and MHC class II expression on individual cells was assessed by microdensitometric analysis. Results. Major histocompatibility class II-positive DCs in the iris developed in an age-dependent manner and reached adult-equivalent density and structure at approximately 10 weeks of age, considerably later than previously described in other DC populations in the rat. In contrast, the anti-rat DC monoclonal antibody OX62 revealed a population of cells present at adult-equivalent levels as early as 3 weeks after birth. Dual-color immunostaining and microdensitometric analysis demonstrated that during postnatal growth, development of the network of MHC class II-positive DCs was a consequence of the progressive increase in expression of MHC class II antigen by OX62-positive cells. Conclusions. During postnatal growth, the DC population of the iris develops initially as an OX62-positive-MHC class II-negative population, which then develops increasing MHC class II expression in situ and finally resembles classic DC populations in other tissue sites. Maturation of the iris DC population is temporally delayed compared with time to maturation in other tissue sites in the rat.

Otitis media with effusion and dental occlusion: is there any relationship?

Aim Auditory tube dysfunction is one of the aetiological causes of otitis media. Studies suggest a correlation between otitis media with effusion and dental malocclusion. Our goal was to determine any correlation between dental malocclusion and otitis media with effusion in children with chronic upper airway obstruction due to tonsil and adenoid enlargement. Materials and methods This prospective study evaluated 52 children with otitis media with effusion and 48 without, aged 4.2 to 10.8 years. A questionnaire was answered by the parents about breast or bottle-feeding and bad oral habits. Malocclusion was diagnosed according to Angle`s classification for molar relationships in Classes I, II and III, posterior and anterior cross bite, open and deep bite, and overjet. Results and conclusion The results suggested no correlation between dental malocclusion and otitis media with effusion. Other potential confounders, such as breast or bottle-feeding and oral habits were also not correlated.

Influence of cephalometric characteristics on the occlusal success rate of Class II malocclusions treated with 2-and 4-premolar extraction protocols

Introduction: The objectives of this investigation were to compare the initial cephalometric characteristics of complete Class II Division 1 malocclusions treated with 2 or 4 premolar extractions and to verify their influence on the occlusal success rate of these treatment protocols. Methods: A sample of 98 records from patients with complete Class II Division 1 malocclusion was divided into 2 groups with the following characteristics: group 1 consisted of 55 patients treated with 2 maxillary first premolar extractions at an initial mean age of 13.07 years; group 2 included 43 patients treated with 4 premolar extractions, with an initial mean age of 12.92 years. Initial and final occlusal statuses were evaluated on dental casts with Grainger`s treatment priority index (TPI), and the initial cephalometric characteristics were obtained from the pretreatment cephalograms. The initial cephalometric characteristics and the initial and final occlusal statuses of the groups were compared with the t test. A multiple regression analysis was used to evaluate the influence of all variables in the final TPI. Results: The 2-premolar extraction protocol provided a statistically smaller TPI and consequently a better occlusal success rate than the 4-premolar extraction protocol. The 4-premolar extraction group had statistically smaller apical base lengths, more vertical facial growth patterns, and greater hard- and soft-tissue convexities at pretreatment than the 2-premolar extraction group. However, the multiple regression analysis showed that only the extraction protocol was significantly associated with the final occlusal status. Conclusions: The initial cephalometric characteristics of the groups did not influence the occlusal success rate of these 2 treatment protocols.

Unprecedented oxidation of a biologically active aroylhydrazone chelator catalysed by iron(III): serendipitous identification of diacylhydrazine ligands with high iron chelation efficacy

Ligands of the 2-pyridylcarbaldehyde isonicotinoylhydrazone class show high iron (Fe) sequestering efficacy and have potential as agents for the treatment of Fe overload disease. We have investigated the mechanisms responsible for their high activity. X-ray crystallography studies show that the tridentate chelate 2-pyridylcarbaldehyde isonicotinoylhydrazone undergoes an unexpected oxidation to isonicotinoyl(picolinoyl)hydrazine when complexed with Fe-III. In contrast, in the absence of Fel the parent hydrazone is not oxidized in aerobic aqueous solution. To examine whether the diacylhydrazine could be responsible for the biological effects of 2-pyridylcarbaldehyde isonicotinoylhydrazone, their Fe chelation efficacy was compared. In contrast to its parent hydrazone, the diacylhydrazine showed little Fe chelation activity. Potentiometric titrations suggested that this might be because the diacylhydrazine was charged at physiological pH, hindering its access across membranes to intracellular Fe pools. In contrast, the Fe complex of this diacylhydrazine was charge neutral, which may allow facile movement through membranes. These data allow a model of Fe chelation for this compound to be proposed: the parent aroylhydrazone diffuses through cell membranes to bind Fe and is subsequently oxidized to the diacylhydrazine complex which then diffuses from the cell. Other diacylhydrazine analogues that were charge neutral at physiological pH demonstrated high Fe chelation efficacy. Thus, for this class of ligands, the charge of the chelator appears to be an important factor for determining their ability to access intracellular Fe. The results of this study are significant for understanding the biological activity of 2-pyridylcarbaldehyde isonicotinoylhydrazone and for the design of novel diacylhydrazine chelators for clinical use.

Synthesis and Coordination Chemistry of a New N-4-Polydentate Class of Pyridyl-Functionalized Scorpionate Ligands: Complexes of Fe-II, Zn-II, V-IV, Pd-II and Use for Heterobimetallic Systems

The new potentially N-4-multidentate pyridyl-functionalized scorpionates 4-((tris-2,2,2-(pyrazol-1-ypethoxy)methyl)pyridine (TpmPy, (1)) and 4-((tris-2,2,2-(3-phenylpyrazol-1-yl)ethoxy)methyl)pyridine (TpmPy(Ph), (2)) have been synthesized and their coordination behavior toward Fe-II, Ni-II, Zn-II, Cu-II, Pd-II, and V-III centers has been studied. Reaction of (1) with Fe(BF4)(2)center dot 6H(2)O yields [Fe(TpmPy)(2)](BF4)(2) (3), that, in the solid state, shows the sandwich structure with trihapto ligand coordination via the pyrazolyl arms, and is completely low spin (LS) until 400 K. Reactions of 2 equiv of (1) or (2) with Zn-II or Ni-II chlorides give the corresponding metal complexes with general formula [MCl2(TpmPy*)(2)] (M = Zn, Ni; TpmPy* = TpmPy, TpmPy(Ph)) (4-7) where the ligand is able to coordinate through either the pyrazolyl rings (in case of [Ni(TpmPy)(2)Cl-2 (5)) or the pyridyl-side (for [ZnCl2(TpmPy)(2)] (4), [ZnCl2(TpmPy(Ph))(2)] (6) and [NiCl2(TpmPy(Ph))(2)] (7)). The reaction of (1) with VCl3 gives [VOCl2(TpmPy)] (8) that shows the N-3-pyrazolyl coordination-mode. Moreover, (1) and react with cis-[PdCl2(CH3CN)(2)] to give the disubstituted complexes [PdCl2(TprnPy)(2)] (9) and [PdCl2(TpmPy(Ph))(2)] (10), respectively, bearing the scorpionate coordinated via the pyridyl group. Compounds (9) and (10) react with Fe(BF4)(2) to give the heterobimetallic Pd/Fe systems [PdCl2(mu-TpmPy)(2)-Fe](BF4)(2) (11) and [PdCl2(mu-TpmPy(Ph))(2)Fe-2(H2O)(6)]BF4)(4) (13), respectively. Compound (11) can also be formed from reaction of (3) with cis-[PdCl2(CH3CN)(2)], while reaction of (3) with Cu(NO3)(2).2.5H(2)O generates [Fe(mu-TpmPy)(2)-Cu(NO3)(2)](BF4)(2) (12), confirming the multidentate ability of the new chelating ligands. The X-ray diffraction analyses of compounds (1), (3), (4), (5), and (9) are also reported.

Atividades de investigação em Geometria: uma experiência no 2º ano de escolaridade

Dissertação apresentada à Escola Superior de Educação de Lisboa para obtenção de grau de mestre em Ciências da Educação, especialidade Educação Matemática na Educação Pré-Escolar e nos 1.º e 2.º Ciclos do Ensino Básico

Cognitive models for the concept of angle

Tese de doutoramento em Filosofia

Deep crustal structure across a young passive margin from wide-angle and reflection seismic data (The Sardinia Experiment) - I. Gulf of Lion's margin

The conjugate margins system of the Gulf of Lion and West Sardinia (GLWS) represents a unique natural laboratory for addressing fundamental questions about rifting due to its landlocked situation, its youth, its thick sedimentary layers, including prominent palaeo-marker such as the MSC event, and the amount of available data and multidisciplinary studies. The main goals of the SARDINIA experiment, were to (i) investigate the deep structure of the entire system within the two conjugate margins: the Gulf of Lion and West Sardinia, (ii) characterize the nature of the crust, and (iii) define the geometry of the basin and provide important constrains on its genesis. This paper presents the results of P-wave velocity modelling on three coincident near-vertical reflection multi-channel seismic (MCS) and wide-angle seismic profiles acquired in the Gulf of Lion, to a depth of 35 km. A companion paper [part II Afilhado et al., 2015] addresses the results of two other SARDINIA profiles located on the oriental conjugate West Sardinian margin. Forward wide-angle modelling of both data sets confirms that the margin is characterised by three distinct domains following the onshore unthinned, 33 km-thick continental crust domain: Domain I is bounded by two necking zones, where the crust thins respectively from 30 to 20 and from 20 to 7 km over a width of about 170 km; the outermost necking is imprinted by the well-known T-reflector at its crustal base; Domain II is characterised by a 7 km-thick crust with anomalous velocities ranging from 6 to 7.5 km/s; it represents the transition between the thinned continental crust (Domain I) and a very thin (only 4-5 km) "atypical" oceanic crust (Domain III). In Domain II, the hypothesis of the presence of exhumed mantle is falsified by our results: this domain may likely consist of a thin exhumed lower continental crust overlying a heterogeneous, intruded lower layer. Moreover, despite the difference in their magnetic signatures, Domains II and III present the very similar seismic velocities profiles, and we discuss the possibility of a connection between these two different domains.

Deep crustal structure across a young passive margin from wide-angle and reflection seismic data (The Sardinia Experiment) - II. Sardinia's margin

Geophysical data acquired on the conjugate margins system of the Gulf of Lion and West Sardinia (GLWS) is unique in its ability to address fundamental questions about rifting (i.e. crustal thinning, the nature of the continent-ocean transition zone, the style of rifting and subsequent evolution, and the connection between deep and surface processes). While the Gulf of Lion (GoL) was the site of several deep seismic experiments, which occurred before the SARDINIA Experiment (ESP and ECORS Experiments in 1981 and 1988 respectively), the crustal structure of the West Sardinia margin remains unknown. This paper describes the first modeling of wide-angle and near-vertical reflection multi-channel seismic (MCS) profiles crossing the West Sardinia margin, in the Mediterranean Sea. The profiles were acquired, together with the exact conjugate of the profiles crossing the GoL, during the SARDINIA experiment in December 2006 with the French R/V L'Atalante. Forward wide-angle modeling of both data sets (wide-angle and multi-channel seismic) confirms that the margin is characterized by three distinct domains following the onshore unthinned, 26 km-thick continental crust : Domain V, where the crust thins from 26 to 6 km in a width of about 75 km; Domain IV where the basement is characterized by high velocity gradients and lower crustal seismic velocities from 6.8 to 7.25 km/s, which are atypical for either crustal or upper mantle material, and Domain III composed of "atypical" oceanic crust.The structure observed on the West Sardinian margin presents a distribution of seismic velocities that is symmetrical with those observed on the Gulf of Lion's side, except for the dimension of each domain and with respect to the initiation of seafloor spreading. This result does not support the hypothesis of simple shear mechanism operating along a lithospheric detachment during the formation of the Liguro-Provencal basin.