Author Correction: Lithospheric mantle buoyancy: the role of tectonic convergence and mantle composition.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Lithospheric mantle buoyancy: the role of tectonic convergence and mantle composition.

Plate subduction and delamination, two key processes driving plate tectonics, are thought to be controlled by the buoyancy of the lithospheric mantle relative to the underlying asthenosphere. Most mantle delamination models consider a lithospheric density higher than the asthenosphere to ensure negative buoyancy (slab pull). However, mineral physics show that the continental lithospheric mantle density is lighter than the asthenosphere, and that only its pressure-temperature-composition dependence makes it become denser and unstable when sinking adiabatically. Here, we explore the controls on buoyancy using a 2D thermal-diffusive model of plate convergence, considering five chemical compositions and tectonothermal ages, namely Archon (>2.5 Ga), Proton (2.5-1.0 Ga), Tecton (<1.0 Ga), and two oceanic lithospheric plates of 30 Ma and 120 Ma. While the advection of colder rock in oceanic-like plates always results in negative buoyancy, Protons and Tectons exhibit an ability to slowly flip from negative to positive buoyancy at low convergence rates: they first favour the sinking due to advection and then become more buoyant because they are thinner and heat up faster during subduction. In contrast, the lighter density of cratons overprints this effect and hinders delamination or subduction, regardless of the convergence rate. This may explain why Archons are more stable during the Wilson cycle.

Deep Seated Density Anomalies Across the Iberia-Africa Plate Boundary and Its Topographic Response.

The modes in which the lithosphere deforms during continental collision and the mechanisms involved are not well understood. While continental subduction and mantle delamination are often invoked in tectonophysical studies, these processes are difficult to be confirmed in more complex tectonic regions such as the Gibraltar Arc. We study the present-day density and compositional structure of the lithosphere along a transect running from South Iberia to North Africa crossing the western Gibraltar Arc. This region is located in the westernmost continental segment of the African-Eurasian plates, characterized by a diffuse transpressive plate boundary. An integrated and self-consistent geophysical-petrological methodology is used to model the lithosphere structure variations and the thermophysical properties of the upper mantle. The crustal structure is mainly constrained by seismic experiments and geological data, whereas the composition of the lithospheric mantle is constrained by xenolith data. The results show large lateral variations in the topography of the lithosphere-asthenosphere boundary. We distinguish different chemical lithospheric mantle domains that reproduce the main trends of the geophysical observables and the modeled P and S wave seismic velocities. A sublithospheric body colder than the surrounding mantle is needed beneath the Betics-Rif to adjust the measured potential fields. We link this body to the Iberian slab localized just to the east of the profile and having some effect on the geoid and Bouguer anomalies. Local isostasy allows explaining most of the topography, but an elastic thickness higher than 10 km is needed to explain local misfits between the Atlas and the Rif Mountains.

Avalanche Behavior in Creep Failure of Disordered Materials.

We present a mesoscale elastoplastic model of creep in disordered materials, which considers temperature-dependent stochastic activation of localized deformation events that are coupled by internal stresses, leading to collective avalanche dynamics. We generalize this stochastic plasticity model by introducing damage in terms of a local strength that decreases, on statistical average, with increasing local plastic strain. The model captures failure in terms of strain localization in a catastrophic shear band concomitant with a finite-time singularity of the creep rate. The statistics of avalanches in the run-up to failure is characterized by a decreasing avalanche exponent τ that, at failure, approaches the value τ=1.5 typical of a critical branching process. The average avalanche rate exhibits an inverse Omori law as a function of time to failure. The distribution of interavalanche times turns out to be consistent with the epidemic-type aftershock sequences (ETAS) model of earthquake statistics.

Identifying factors associated with fast food consumption among adolescents in Beijing China using a theory-based approach.

OBJECTIVES: China is in the midst of the nutrition transition with increasing rates of obesity and dietary changes. One contributor is the increase in fast food chains within the country. The purpose of this study was to develop a theory-based instrument that explores influencing factors of fast food consumption in adolescents residing in Beijing, China. DESIGN: Cross-sectional study. METHODS: Value expectancy and theory of planned behaviour were utilised to explore influencing factors of fast food consumption in the target population. There were 201 Chinese adolescents between the ages of 12 and 18. Cronbach's alpha correlation coefficients were used to examine internal reliability of the theory-based questionnaire. Bivariate correlations and a MANOVA were utilised to determine the relationship between theory-based constructs, body mass index (BMI)-for-age and fast food intake frequency as well as to determine differences in theory-based scores among fast food consumption frequency groupings. RESULTS: The theory-based questionnaire showed good reliability. Furthermore, there was a significant difference in the theory-based subcategory scores between fast food frequency groups. A significant positive correlation was observed between times per week fast food was consumed and each theory-based subscale score. Using BMI-for-age of 176 participants, 81% were normal weight and 19% were considered overweight or obese. Results showed consumption of fast food to be on average 1.50 ± 1.33 per week. The relationship between BMI-for-age and times per week fast food was consumed was not significant. CONCLUSIONS: As the nutrition transition continues and fast food chains expand, it is important to explore factors effecting fast food consumption in China. Interventions targeting influencing factors can be developed to encourage healthy dietary choice in the midst of this transition.

Biological markers of cisplatin resistance in advanced testicular germ cell tumours

INTRODUCTION: Germ cell tumours (GCTs) of the testis show exquisite sensitivity to treatment with cisplatin. Despite the high cure rates provided by platinum-based chemotherapy, 10-20% of patients die from progressive disease. Although various cellular pathways may influence cisplatin efficacy, their actual impact has not been comprehensively investigated in advanced GCTs. The objective of the present study was to clarify the role of the expression status of proteins involved in the Rb and p53 tumour suppressor pathways in sensitivity and resistance of GCTs to cisplatin-based chemotherapy. MATERIALS AND METHODS: Paraffin-embedded tumour tissues from 84 patients with advanced GCT treated with cisplatin-based chemotherapy were analysed. Immunohistochemical expression of proteins p53 and mdm2, and the G1-phase cyclins D1 and D2 (CD1 and CD2) was assessed and correlated with the clinical course. RESULTS: The percentages of positive expression of p53, mdm2, CD1 and CD2 were 56, 57, 37.5 and 55%, respectively. From univariate analysis, there was no significant association between p53, mdm2 or CD1 expression and outcome. Instead, positive CD2 expression was found to be marginally associated with shorter median duration of progression-free survival (PFS) (p=0.06). In multivariate analysis, none of the molecular markers retained statistical significance with treatment response or survival. CONCLUSIONS: Tissular expression of p53, mdm2 and CD1 is not associated with prognosis or treatment response in patients with advanced GCT. Aberrant CD2 expression appears to further determine a shorter PFS. Larger and further studies are required to validate CD2 as a marker of cisplatin resistance (AU)

Messinian salinity crisis regulated by competing tectonics and erosion at the Gibraltar arc.

The Messinian salinity crisis (5.96 to 5.33 million years ago) was caused by reduced water inflow from the Atlantic Ocean to the Mediterranean Sea resulting in widespread salt precipitation and a decrease in Mediterranean sea level of about 1.5 kilometres due to evaporation. The reduced connectivity between the Atlantic and the Mediterranean at the time of the salinity crisis is thought to have resulted from tectonic uplift of the Gibraltar arc seaway and global sea-level changes, both of which control the inflow of water required to compensate for the hydrological deficit of the Mediterranean. However, the different timescales on which tectonic uplift and changes in sea level occur are difficult to reconcile with the long duration of the shallow connection between the Mediterranean and the Atlantic needed to explain the large amount of salt precipitated. Here we use numerical modelling to show that seaway erosion caused by the Atlantic inflow could sustain such a shallow connection between the Atlantic and the Mediterranean by counteracting tectonic uplift. The erosion and uplift rates required are consistent with previous mountain erosion studies, with the present altitude of marine sediments in the Gibraltar arc and with geodynamic models suggesting a lithospheric slab tear underneath the region. The moderate Mediterranean sea-level drawdown during the early stages of the Messinian salinity crisis can be explained by an uplift of a few millimetres per year counteracted by similar rates of erosion due to Atlantic inflow. Our findings suggest that the competition between uplift and erosion can result in harmonic coupling between erosion and the Mediterranean sea level, providing an alternative mechanism for the cyclicity observed in early salt precipitation deposits and calling into question previous ideas regarding the timing of the events that occurred during the Messinian salinity crisis.

Catastrophic flood of the Mediterranean after the Messinian salinity crisis.

The Mediterranean Sea became disconnected from the world's oceans and mostly desiccated by evaporation about 5.6 million years ago during the Messinian salinity crisis. The Atlantic waters found a way through the present Gibraltar Strait and rapidly refilled the Mediterranean 5.33 million years ago in an event known as the Zanclean flood. The nature, abruptness and evolution of this flood remain poorly constrained. Borehole and seismic data show incisions over 250 m deep on both sides of the Gibraltar Strait that have previously been attributed to fluvial erosion during the desiccation. Here we show the continuity of this 200-km-long channel across the strait and explain its morphology as the result of erosion by the flooding waters, adopting an incision model validated in mountain rivers. This model in turn allows us to estimate the duration of the flood. Although the available data are limited, our findings suggest that the feedback between water flow and incision in the early stages of flooding imply discharges of about 10(8) m(3) s(-1) (three orders of magnitude larger than the present Amazon River) and incision rates above 0.4 m per day. Although the flood started at low water discharges that may have lasted for up to several thousand years, our results suggest that 90 per cent of the water was transferred in a short period ranging from a few months to two years. This extremely abrupt flood may have involved peak rates of sea level rise in the Mediterranean of more than ten metres per day.

Sexual risk behaviour, viral load, and perceptions of HIV transmission among homosexually active Latino men: an exploratory study.

The objective of the paper was to describe awareness of HIV medications and HIV viral load, and to assess the impact of HIV medications (including highly active antiretroviral therapy) and notions of viral load on sexual risk practices. This was an exploratory cross-sectional study of a non-random sample of 395 homosexually active Latino men in New York City. An anonymous self-administered questionnaire was used focusing on perceptions about HIV/AIDS, HIV treatment medications and viral load, risk perceptions, HIV status, and sexual partners and practices in the past 6 months. HIV-positive participants taking HIV medications, those who knew their viral loads, and those who had undetectable viral loads did not report significantly different frequencies of high-risk (receptive or insertive) unprotected anal intercourse (UAI) in comparison to other HIV-positive individuals in the sample. Perceptions about HIV status (assuming same status) and viral load (penetrating partner or letting partner penetrate one) were related to significantly higher high-risk UAI in the past 6 months. HIV prevention strategies for homosexually active Latino men should not only address the basic issue of assuming similar HIV status but also need to examine misconstructions of the transmissibility of HIV as a result of undetectable viral load.

Epidermal growth factor receptor activating mutations in Spanish gefitinib-treated non-small-cell lung cancer patients.

BACKGROUND: North American and Japanese non-small-cell lung cancer (NSCLC) patients with epidermal growth factor receptor (EGFR) activation via tyrosine kinase (TK) mutations respond dramatically to gefitinib treatment. To date, however, the frequency and effect of EGFR TK mutations have not been examined in European patients. PATIENTS AND METHODS: Eighty-three Spanish advanced NSCLC patients who had progressed after chemotherapy, were treated with compassionate use of gefitinib. Patients were selected on the basis of available tumor tissue. Tumor genomic DNA was retrieved from paraffin-embedded tissue obtained by laser capture microdissection. EGFR mutations in exons 19 and 21 were examined by direct sequencing. RESULTS: EGFR mutations were found in 10 of 83 (12%) of patients. All mutations were found in adenocarcinomas, more frequently in females (P=0.007) and non-smokers (P=0.01). Response was observed in 60% of patients with mutations and 8.8% of patients with wild-type EGFR (P=0.001). Time to progression for patients with mutations was 12.3 months, compared with 3.6 months for patients with wild-type EGFR (P=0.002). Median survival was 13 months for patients with mutations and 4.9 months for those with wild-type EGFR (P=0.02). CONCLUSIONS: EGFR TK mutational analysis is a novel predictive test for selecting lung adenocarcinoma patients for targeted therapy with EGFR TK inhibitors.

CNS voltage-dependent Na(+) channel expression and distribution in an undifferentiated and differentiated CNS cell line.

Upon serum removal, CAD-R1 cells undergo neurite outgrowth and an increase in voltage-dependent Na(+) current (VDNaC) density without changing their activation and inactivation properties. Insulin and endothelial cell growth supplement inhibited the increase in VDNaC density but not the neurite outgrowth. RI, RII, RIII Na(+) channel proteins were expressed in CAD-R1 cells. These proteins exhibited both similar and different distribution and clustering patterns which suggested the channel's structural differences play a role in channel distribution.

Anxiety disorders in children and adolescents.

BACKGROUND: Children and adolescents frequently have symptoms of anxiety. In addition, anxiety disorders are some of the most frequent psychiatric disorders in this age group. METHODS: We used computerized literature searches (MEDLINE and PSYCHLIT) to identify clinical, research, and review articles on this subject. Various journals and textbooks from the psychiatric, medical, and psychology literature were accessed. RESULTS: This review includes findings on the epidemiology, developmentally normal anxiety, clinical presentations, course and outcome, and treatment interventions. CONCLUSIONS: Pediatricians and family practitioners should be familiar with the spectrum of anxiety in children and adolescents. Guidelines for referral to a mental health practitioner are reviewed.

Coherent optical array receivers for the mitigation of atmospheric turbulence and speckle effects.

A description is given of the design, operation, and test over a 2-km path (roundtrip) of a continuous wave, coherent laser array receiver that uses two independent aperture-receivers whose intermediate frequencies are electro-optically co-phased in real time and then added as a proposed way to overcome effective aperture limitations imposed by atmospheric turbulence and to mitigate signal fading associated with atmospheric turbulence and speckle effects. The experiment resulted in a mean carrier-to-noise ratio increase of 1.8, which is within 1% of the theoretical predictions, when the two signals were phase locked, versus no increase without phase locking. Further, the carrier fading strength, or normalized carrier-to-noise ratio variance, was reduced by a factor of 0.53, which is within 2% of the theoretical prediction. The bandwidth of the electro-optic phase-locked loop was measured to be of the order of 600 Hz, which is adequate to compensate for atmospheric refractive turbulence fluctuations.

Role of cholecystokinin in the anorexia produced by duodenal delivery of oleic acid in rats.

To assess the importance of triglyceride digestion products in producing satiety, we determined the effects of duodenal infusions of triolein, oleic acid, and oleic acid plus monoolein on meal patterns in ad libitum-feeding rats. Oleic acid and oleic acid plus monoolein inhibited feeding similarly; triolein's effect was delayed and fourfold less potent. We then used the type A cholecystokinin (CCK-A)-receptor antagonist devazepide to assess the importance of CCK in mediating the anorexia produced by oleic acid. Oleic acid (at 320, 440, and 640 mumol/h) inhibited 3-h intake dose dependently by 32, 56, and 75%, respectively. Devazepide (1 or 2 mg/kg) blocked the responses to the 320 mumol/h dose, but had little if any effect on responses to the larger doses. Devazepide (1 mg/kg) did block anorexic responses to 3-h cholecystokinin octapeptide infusions (3 and 10 nmol.kg-1.h-1 iv) that inhibited 3-h intake by 25 and 65%, respectively. Our results suggest that the satiety response to triolein is produced by the products of triolein digestion and that CCK plays a significant, indispensable role in mediating the satiety response to duodenal delivery of small but not large loads of oleic acid.

[Elastic band ligation: preliminary experience in esophagogastric varices]. / Ligadura con bandas elásticas: experiencia preliminar en varices esofagogástricas.

Endoscopic ligation is a new technique that shows an efficacy for acute hemorrhage and prevention similar to sclerotherapy. Its principal advantage is the smaller number of complications (2%), which seem to be related to the presence of post-treatment ulcers which are indeed more extensive but more superficial. In our preliminary study on 8 patients, eradication of varices in 62.5% was obtained. The mean number of bands placed at each ligation session was of 2.4 +/- 0.96 and the mean number of treatment sessions to achieve the eradication was 3.4 +/- 1.5. The complications that appear during the positioning of bands, a minimum bleeding was observed during the polyp formation, and in one occasion, the partial detachment of an eschar followed the bleeding was also observed. Rebleeding occurred in two patients (25%), and in other patient, spontaneous bacterial peritonitis was observed. The two patients who presented recurrent variceal bleeding, received a transjugular intrahepatic portosystemic shunt to control their hemorrhage.

[Tracheoesophageal fistula secondary to endoscopic sclerotherapy of esophageal varices]. / Fístula traqueoesofágica secundaria a escleroterapia endoscópica de varices esofágicas.

Over the past 15 years, endoscopic variceal sclerotherapy (EVS) has become the main therapy for patients with bleeding esophageal varices. EVS has the advantage of a low associated mortality and morbidity, but may lead to serious complications. We report a case of esophagotracheal fistula complicating sclerotherapy that resolved with nonsurgical management.

[Hypertensive colopathy: its endoscopic evaluation and evolution following a liver transplant]. / Colopatía hipertensiva: valoraciíon endoscópica y evolución tras trasplante hepático.

In the last decade the association between intestinal vasculopathy and Portal Hypertension (PH) has been established on the basis of endoscopic, histological and histomorphometric examinations. We report the case of a patient with cirrhosis secondary to hepatitis C virus, in whom colonoscopy demonstrated the presence of colonic vascular lesions with cherry spots appearance in the rectum and left colon that vanished two weeks after liver transplantation. The disappearance of mucosal lesions after liver grafting suggest a relation ship among them and portal hypertension.

La red geodésica del volcán Popocatépetl para el monitoreo de la actividad volcánica

Uno de los métodos más utilizados para la detección temprana de cambios en el estado de actividad de un volcán, que pudieran a llegar a traducirse en un proceso eruptivo de carácter destructivo, es el método geódesicopara la medición de deformaciones de los edificios volcánicos. Aquí se describen la metodología y los resultados de las observaciones geodésicas realizadas en el volcán Popocatépetl desde principios de 1992 utilizando métodos de triangulalateración e inclinometría, y se evalúan los resultados en términos del riesgo volcánico (AU)