1,721,143 research outputs found
Shale 3D Flow and Interaction With Basement Faults in the Niger Delta Deep-Water Fold and Thrust Belt
No full textBased on a large 3D seismic data set in the deep-water domain of the Niger Delta, this study challenges previous interpretations involving the occurrence of multiple detachments and extensive thrust flats, illustrating timing and mode of shales flow at the toe of the gravity system. Five units of syn-kinematic sediments, reaching a maximum thickness of similar to 800 m, accumulated in the tectonically subsiding synclines during fold amplification between similar to 9.5 and similar to 1.4 Ma. The volumes of syn-kinematic units roughly balance those of the shales accumulated in the thickened cores of WNW trending anticlines. This feature is consistent with folding resulting from buckling controlled by the competence contrast between isopach Cenozoic units and underlying overpressured shales of the Akata Formation. A dense network of NE-SW striking oblique extensional faults offsets a prominent anticline characterized by a NE-SW trend (which is almost perpendicular to the regional fold trend). These faults form a narrow, continuous deformation zone extending for tens of kilometers along and beyond the length of the anticline. The faults, rooting within the shales of the Akata Formation, formed since similar to 5 Ma and deform the seabed. Displacement distribution suggests mechanical interaction between isolated fault segments within the deformation zone. The latter is interpreted as the shallow expression of a deep-seated fault zone inherited from the segmented passive margin and marked by gravity and magnetic data. Our results, providing a comprehensive picture of active deformation features and their relationships with deep-seated faults, shed new light into the modes of interaction between gravity systems and underlying basement structures.The occurrence of thick successions of weak shales underlying sandy deltaic deposits control gravity-driven deformation in deep-water basins worldwide. In these conditions, large sedimentary bodies such as the Niger Delta of this study are characterized by (a) a spreading inner shallow-water sector, which undergoes collapse due to the fast accumulation of deltaic sediments, and (b) a deep-water domain characterized by shortening. Volume balancing in the latter domain points out that a 3D flow pattern must accommodate thickening of mobile shales into anticlinal cores as a result of flow of material from adjacent synclines. Folding occurred by buckling, a process characterized by mechanically active layering. This process was controlled by the strong viscosity contrast between the thick shales and the overlying sandy units, which tend to maintain a constant thickness in seismic lines. Fold nucleation was locally controlled by the occurrence of basement structures, which is revealed by magnetic and gravimetric data. These folds show "anomalous" trends that do not conform to the regional fold orientation. The interaction between the delta deposits and the underlying basement structures also led to the development of faults that display a clear morphology at the sea bottom and are therefore considered active.Volume balancing indicates that mobile shales accumulated into anticlinal cores as a result of 3D flow from surrounding synclinesThe incompetent Akata shales thickened in the core of the anticlines during buckle folding accompanied by late-stage thrustingThe detachment at the base of the shales interacted with basement structures, localizing deformation in overlying delta sediment
Pliocene to Quaternary tectono-sedimentary evolution of the Crati basin, northern Calabria, Italy
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CT diagnosis of lumbosacral conjoined nerve roots - Findings in 19 cases
No full textThe authors report the observations derived from CT evaluation of 19 cases of lumbosacral conjoined nerve roots; 11 of these have been confirmed by lumbar myelography and/or at surgery. They conclude that CT without intrathecal metrizamide allows the recognition in most cases of the presence of conjoined nerve roots and to differentiate them from a herniated disk fragment; this is especially useful to avoid surgical damage of anomalous roots. © 1987 Springer-Verlag
The role of the pineal body in the endocrine control of puberty
No full textThe pineal gland plays an important role in reproductive endocrinology. The epiphysis regulates seasonal variations in reproductive function of seasonally breeding animals. In humans, even if they are not seasonal breeders, the role of the pineal in reproductive endocrinology seems to be important as well. It appears to be of particular importance the endocrine control of the gland on pubertal sexual maturation. Even if not all researchers agree, several data suggest that elevated melatonin levels-characteristic of prepubertal age-keep the hypothalamic-pituitary-gonadal axis in quiescence: thus, an inhibitory effect on pubertal development is exerted. Subsequently, the decreasing serum melatonin with advancing age would result in activation of the hypothalamic pulsatile secretion of GnRH- and therefore of the reproductive axis-with consequent onset of pubertal phenomena. The production rate of melatonin does not change with age and no growth in pineal size from 1 to 15 years of age has been demonstrated by nuclear magnetic resonance (NMR) studies. Therefore the decrease of serum melatonin concentrations has been proposed to be due to the increase in body mass or, according to another hypothesis, to be also temporally linked to sexual maturation. Furthermore, recently, it has been suggested in rats that the pineal influences not only the pubertal sexual maturation, but even the gonadal and genital development and function of offspring, already during intrauterine life. Investigations are needed to evaluate this hypothesis in humans
Use of the GnRH-agonist (GnRH-A) in gynaecology.
No full textGnRH-agonist therapy is used in the management of many gynaecological pathologies: uterine fibroids, endometriosis, ovarian cystic pathology, breast cancer, dysfunctional uterine bleeding and, in males, prostatic cancer. In the case of uterine fibroids, this therapy can be used as a pre-treatment before conservative or demolitive surgery or as an alternative to hysterectomy. At the Centre for Therapy of Uterine Pathologies (I Institute of Obstetrics and Gynaecology of the University of Rome "La Sapienza") the use of Gn-RH-A therapy in uterine fibroids has been investigated and results consistent with those of many other groups of study have been obtained. The two most important results are: 1. the decrease of both the myoma's size and the uterine volume; 2. the block of menometrorrhagiae symptoms, with improvement of the haematic crasis and possibility to convert a demolitive surgery to a conservative surgery. GnRH-agonists can represent a definitive treatment for patients with symptomatic uterine fibroids and in perimenopausal age
High Motor Cortex Excitability in Highly Hypnotizable Individuals: A Favourable Factor for Neuroplasticity?
No full textHypnotizability is a psychophysiological trait associated with morphofunctional brain peculiarities and with several cognitive, sensorimotor and cardiovascular correlates. Behavioral and EEG studies indicate stronger functional equivalence (FE) between motor imagery and action in the individuals with high hypnotizability scores (Highs). We hypothesized that stronger FE leading to greater proneness to ideomotor behavior could be due to greater cortical excitability of the motor cortex. The aim of the study was to evaluate the motor cortical excitability through measurements of the muscle potentials (MEPs) evoked in the left abductor pollicis brevis by transcranial magnetic stimulation (TMS) of the right motor cortex in 10 Highs, 10 medium (Mediums) and 10 low hypnotizable individuals (Lows) classified according to the Stanford Hypnotic Susceptibility Scale, form A (SHSS). They were studied in basal conditions (B) and during motor imagery (MI). Results showed significant, negative correlations (i) between hypnotizability and MEPs Resting Motor Threshold (RMT) in basal conditions, and (ii) between hypnotizability and both MEPs RMT and suprathreshold (I1mv) stimulation intensities during MI. ANOVA revealed significantly lower stimulation intensities in Highs than in Lows, with Mediums exhibiting intermediate values. Thus, the Highs’ greater cortical excitability could sustain their greater FE and proneness to ideomotor behavior. In cognitive neuroscience these findings are relevant to the physiological interpretation of the response to sensorimotor suggestions by participants in the ordinary state of consciousness. In the clinical field they can predict the efficacy of mental training based on motor imagery and, possibly, the degree of imagery-induced cortical plasticity
The evolution of estroprogestative contraception: Analysis on the reduction or suppression of side-effects
No full textThe advances achieved by scientific research about contraception estroprogestinic contraception have lead to a better knowledgeof the risk factors connected to the use of oral contraceptives (O.C.) and trough the years, the change of their hormonal components dosesand of the type of progestin. These advances, together with the selection and monitoring of the patients who can use the pill have been accompanied by an evolution of its riskk. O.C. risks basically include neoplastic, cardiovascular, metabolic, and reproductive risks. This article presents a review of the most important studies conducted about such possible relations. The Authors conclude that the progress achieved in the hotmonal contraception has allowed to reduce greatly and, in some cases, to annul its risks. therefore, proper information is needed to explain that the pill, administered under medical control, is a safe drug and that many fears for its uses are no more justified
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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