From steady state to climate-driven denudation across the Central Andes in SE Peru

To better constrain the orogenic growth of the Andean chain, we investigated the time-Temperature paths of bedrocks from the two morpho-structural highs of the Central Andes that are separated by the vanishing Altiplano, i.e. the Eastern and Western Cordilleras of SE Peru. The Western Cordillera is a volcanic to volcano detrital chain that developed ~40-35 Ma ago and is characterized by a 4000m high mean altitude whose origin is poorly constrained. Fission-Track data on apatite and zircon crystals extracted from an Eocene pluton yield ages comprised between 24 and 14 Ma, and 38 and 30 Ma respectively. One of the noteworthy aspects of the data is that analyses reveal a steady-state phase of exhumation from the late Eocene to at least the middle Miocene (38-14 Ma) with no disruption of the exhumation path since 38 Ma either by sedimentary burial and/or rapid exhumation. The uplift of the Western Cordillera was thus probably steady since, avoiding the deposition of foreland basin sequences as in the Altiplano region. Further east, Apatite Fission-Track ages are much younger and range between 7.6 and 2.5 Ma for the Eastern Cordillera and between 11.2 and 1.5 Ma for the Sub Andean Zone. Age-altitude relationshipssuggest that denudation increased from a more quiescent Late Miocene period to a high rate of 0.9 km/my for the Pliocene. Such abrupt change is supported by a net in sediment accumulation rates in the Andean Amazon Basin but as far as offshore the Amazon fan. A global climate change is usually invoked for high Pliocene rates; however it post-dated a documented period of surface uplift in the Eastern Andes

Illite crystallinity patterns in the Anti-Atlas of Morocco

The low-grade metamorphism of the sedimentary cover of the Moroccan Anti-Atlas is investigated using Illite crystallinity (IC) method. More than 200 samples from three key areas (southwestern, central and eastern Anti-Atlas) have been taken from a maximum of different stratigraphic levels and have been analysed. The metamorphism is of low to very low degree throughout the southern flank of the Anti-Atlas. It increases from northeast to southwest. Whereas in the eastern Anti-Atlas diagenetic and anchizonal IC-values are predominant, in the western and central Anti-Atlas also epizonal IC-values are found. In every respective area the IC improves with stratigraphic age. At the scale of the entire Palaeozoic Anti-Atlas basin the IC correlates best with estimated paleo-overburden. However, burial metamorphism cannot be the cause even though considering missing sedimentary pile of Late Carboniferous age. The ‘abnormal' paleo-geothermal gradient of 43-35 °C/km we evidenced for the Carboniferous is a true one, and has to be related to a basement sequence enriched in heat producing elements such as series of the West African Crato

Landscape evolution of the Apurimac river drainage basin, southern Peru

The northernmost part of the Altiplano in Southern Peru is drained by the river Apurimac and its tributaries. The Altiplano is a region that covers most of the eastern part of the Cordillera Occidental and is bounded in the East by the Cordillera Oriental. The Apurirnac River Drainage Basin (ARDB) extends roughly between 13 °S and l5°S over 50000 km 2. It mainly occupies the northeastern flank of the Cordillera Occidental and a negligible part of the southwestern flank of the Cordillera Oriental. At the latitude of the Abancay deflection, i.e. 13.5 S; 72.7 W, the Apurirnac River abandons the Cordillera Occidental. On its way to the Amazon Basin in the North the Apurimac River drains the Cordillera Oriental and the Sub-Andean Zone (SAZ). The incision by the rivers of the ARDB has created differences in relief of more than 2000 m that contributed to the denudation and exhumation, hence the evolution ofthe landscape. The Altiplano sedimentary basin contains an 8 kilometers thick succession of Cenozoic sediments, which it received from the surrounding highs in the West and the Easl Its structural framework has been formed by the various tectonic events that struck the Andes and the various pulses of magmatic activity that took place during the Cenozoic. In the western part of the Altiplano Miocene volcanics domínate, whereas in the northeastern part, in the Cusco region, clastic deposits do so. In the region of Abancay, a batholite got emplaced during the mid Tertiary, that extends over few 1000 km2

Decision Tree Classifiers for Star/Galaxy Separation

We study the star/galaxy classification efficiency of 13 different decision tree algorithms applied to photometric objects in the Sloan Digital Sky Survey Data Release Seven (SDSS DR7). Each algorithm is defined by a set of parameters which, when varied, produce different final classification trees. We extensively explore the parameter space of each algorithm, using the set of $884,126$ SDSS objects with spectroscopic data as the training set. The efficiency of star-galaxy separation is measured using the completeness function. We find that the Functional Tree algorithm (FT) yields the best results as measured by the mean completeness in two magnitude intervals: $14\le r\le21$ ($85.2$) and $r\ge19$ ($82.1$). We compare the performance of the tree generated with the optimal FT configuration to the classifications provided by the SDSS parametric classifier, 2DPHOT and Ball et al. (2006). We find that our FT classifier is comparable or better in completeness over the full magnitude range $15\le r\le21$, with much lower contamination than all but the Ball et al. classifier. At the faintest magnitudes ($r>19$), our classifier is the only one able to maintain high completeness ($>$80%) while still achieving low contamination ($\sim2.5$). Finally, we apply our FT classifier to separate stars from galaxies in the full set of $69,545,326$ SDSS photometric objects in the magnitude range $14\le r\le21$.Comment: Submitted to A

Morphology of Isotactic Polypropylene–Polyethylene Block Copolymers Driven by Controlled Crystallization

A study of the morphology of diblock copolymers composed of two crystalline blocks of isotactic polypropylene (iPP) and polyethylene (PE) is shown. The samples form phase-separated structures in the melt because of the incompatibility between iPP and PE blocks. Cylindrical PE microdomains are visible at room temperature in the sample with a PE volume fraction of 26%, rapidly quenched from the melt in liquid nitrogen. In the quenched sample, PE crystallizes inside the PE cylindrical microdomains, whereas crystals of iPP are not visible in the iPP domains because the quenching prevents crystallization of the lamellar α form. Less rapid cooling of the melt produces, instead, breakout crystallization, where the phase-separated structure of the melt is destroyed by the slow crystallization of the α form of iPP and of PE. The succession of crystallization of iPP and PE and the resulting final morphology have been analyzed by inducing selective and different orientations of iPP and PE crystals through epitaxial crystallization onto the benzoic acid (BA) crystal substrate. Epitaxy produces oriented crystallization of iPP and PE, with a unique alignment of PE lamellar crystals and a double orientation of iPP crystals on to the (001) exposed face of BA. Epitaxy destroys the phase-separated structure of the melt and induces the formation of ordered lamellar nanostructures with alternated layers of iPP and PE, whose orientation is defined by the alignment of PE or iPP crystals, which, in turn, is determined by epitaxy. The results indicate that crystalline block copolymers offer the opportunity to create nanoscale patterns on thin films and improve the possibility of controlling the microstructure of block copolymers and the alignment of microdomains by controlling the crystallization process

Chronic administration of atypical antipsychotics improves behavioral and synaptic defects of STOP null mice.

International audienceINTRODUCTION: Recent studies have suggested that schizophrenia is associated with alterations in the synaptic connectivity involving cytoskeletal proteins. The microtubule-associated protein stable tubule only polypeptide (STOP) plays a key role in neuronal architecture and synaptic plasticity, and it has been demonstrated that STOP gene deletion in mice leads to a phenotype mimicking aspects of positive and negative symptoms and cognitive deficits classically observed in schizophrenic patients. In STOP null mice, behavioral defects are associated with synaptic plasticity abnormalities including defects in long-term potentiation. In these mice, long-term administration of typical antipsychotics has been shown to partially alleviate behavioral defects but, as in humans, such a treatment was poorly active on deficits related to negative symptoms and cognitive impairments. Here, we assessed the effects of risperidone and clozapine, two atypical antipsychotics, on STOP null mice behavior and synaptic plasticity. RESULTS: Long-term administration of either drug results in alleviation of behavioral alterations mimicking some negative symptoms and partial amelioration of some cognitive defects in STOP null mice. Interestingly, clozapine treatment also improves synaptic plasticity of the STOP null animals by restoring long-term potentiation in the hippocampus. DISCUSSION: All together, the pharmacological reactivity of STOP null mice to antipsychotics evokes the pharmacological response of humans to such drugs. Totally, our study suggests that STOP null mice may provide a useful preclinical model to evaluate pharmacological properties of antipsychotic drugs

Time-resolving small angle X-Ray scattering analysis of melt crystallization of mixtures of regular and irregular isotactic polypropylene samples

The melting/crystallization properties of blends obtained by mixing two isotactic polypropylene (iPP) samples synthesized using single-site metallocene catalyst systems and containing a high and low concentration of rr triads as stereo-defects, are studied. The changes occurring at lamellar length scale during a heating/cooling cycle at constant scanning rate are followed in situ by performing time-resolved small angle X-ray scattering (SAXS) measurements. Data analysis demonstrates that the evolution of the SAXS intensity with increase/decrease of the temperature is controlled by the separate melting/crystallization of the two components, the differences in the thermal expansion (contraction) coefficient of the amorphous and crystalline phases and the role of thermal fluctuations in electron density. The two components give rise to different populations of intermixed lamellar stacks in the blends which originate from the good miscibility of the low and high stereoregular samples in the melt.info:eu-repo/semantics/publishedVersio

Overprinting orogenic events, ductile extrusion and strain partitioning during Caledonian transpression, NW Mainland Shetland

A 3.6 km thick stack of mid-crustal deformed Precambrian rocks is associated with the North Roe Nappe (NRN) and Walls Boundary Fault in the northernmost Scottish Caledonides on NW Mainland Shetland. The greenschist- to amphibolite-facies rocks display unusually complex and heterogeneous combinations of coaxial and non-coaxial transpressional deformation. Previously published isotopic dating, together with new detailed field mapping and microstructural characterisation show that the NRN preserves a record of Neoarchaean, Neoproterozoic (Knoydartian) and Ordovician-Silurian (Caledonian) overprinting deformation and metamorphism. Neoarchaean events in the Uyea Gneiss Complex located in its footwall are reworked by younger events in the overlying nappe pile. The main ductile fabrics were formed during Caledonian top-to-the W/NW thrusting and top-to-the N sinistral shearing, with subordinate regions of top- to-the E extensional and NNE-SSW dextral shearing. In lower parts of the NRN, these different kinematic domains are texturally indistinguishable and overprinting relationships are absent. At higher levels, top-to-the-W/NW thrust-related fabrics are consistently overprinted by top-to-the-N/NE sinistral shearing. The highly partitioned transpressional deformation shows similarities with equivalent rocks of the Moine Nappe in NW Scotland

ICF-Based Disability Survey in a Rural Population of Adults and Older Adults Living in Cinco Villas, Northeastern Spain: Design, Methods and Population Characteristics

Background: This article describes the methods of a door-to-door screening survey exploring the distribution of disability and its major determinants in northeastern Spain. This study will set the basis for the development of disability-related services for the rural elderly in northeastern Spain. Methods: The probabilistic sample was composed of 1,354 de facto residents from a population of 12,784 Social Security card holders (age: 6 50 years). Cognitive and disability screenings were conducted (period: June 2008-June 2009). Screening instruments were the MMSE and the World Health Organization Disability Assessment Schedule. Participants screened positive for disability underwent an assessment protocol focusing on primary care diagnoses, disability, lifestyle, and social and health service usage. Participants screened positive for cognitive functioning went through in-depth neurological evaluation. Results: The study sample is described. Usable data were available for 1,216 participants. A total of 625 individuals (51.4%) scored within the positive range in the disability screening, while 135 (11.1%) scored within the positive range of the cognitive screening. The proportion of positively screened individuals was higher for women and increased with age. Conclusions: Screening surveys represent a feasible design for examining the distribution of disability and its determinants among the elderly. Data quality may benefit from methodological developments tailored to rural populations with a low education level. Copyright (C) 2010 S. Karger AG, Base