269 research outputs found

    Poblamiento, movilidad y territorios entre las sociedades cazadoras-recolectoras de Patagonia

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    La transición Pleistoceno/Holoceno fue un tiempo crítico ambiental en el cual se produjo la dispersión humana del último continente en ser poblado, América del Sur. Los primeros colonos, que buscaban lugares para establecerse, fueron desafiados en América por la enorme variabilidad ambiental y los profundos y repentinos cambios climáticos de los momentos de la transición. Este artículo trata de ese proceso de poblamiento en la Patagonia, donde las ocupaciones humanas más antiguas están datadas entre 13.5 y 10.5 ka AP en tres diferentes focos geográficos: (a) las cuencas andinas de la vertiente Pacífica; (b) la cuenca del Macizo del Deseado; y (c) la cuenca magallánico-fueguina. Siguiendo los datos arqueológicos y paleoambientales (polen, faunas, sedimentos) y los fechados radiocarbónicos se proponen hipótesis sobre las formas de la colonización y la movilidad humana durante el final de la última gran glaciación y el Holoceno medio. El ingreso de los primeros grupos de cazadores-recolectores podría haber ocurrido por dos rutas diferentes, el borde Pacífico y la vertiente Atlántica. Desde ambos litorales y remontando los ríos hacia el interior del territorio los grupos habrían alcanzado en forma diferida ambos flancos cordilleranos. La alta movilidad de los primeros grupos humanos habría sido la clave para enfrentar el desafío de la colonización en esas altas latitudes.La transición Pleistoceno/Holoceno fue un tiempo crítico ambiental en el cual se produjo la dispersión humana del último continente en ser poblado, América del Sur. Los primeros colonos, que buscaban lugares para establecerse, fueron desafiados en América por la enorme variabilidad ambiental y los profundos y repentinos cambios climáticos de los momentos de la transición. Este artículo trata de ese proceso de poblamiento en la Patagonia, donde las ocupaciones humanas más antiguas están datadas entre 13.5 y 10.5 ka AP en tres diferentes focos geográficos: (a) las cuencas andinas de la vertiente Pacífica; (b) la cuenca del Macizo del Deseado; y (c) la cuenca magallánico-fueguina. Siguiendo los datos arqueológicos y paleoambientales (polen, faunas, sedimentos) y los fechados radiocarbónicos se proponen hipótesis sobre las formas de la colonización y la movilidad humana durante el final de la última gran glaciación y el Holoceno medio. El ingreso de los primeros grupos de cazadores-recolectores podría haber ocurrido por dos rutas diferentes, el borde Pacífico y la vertiente Atlántica. Desde ambos litorales y remontando los ríos hacia el interior del territorio los grupos habrían alcanzado en forma diferida ambos flancos cordilleranos. La alta movilidad de los primeros grupos humanos habría sido la clave para enfrentar el desafío de la colonización en esas altas latitudes

    Temperature profile in a reverse flow reactor for catalytic partial oxidation of methane by fast IR imaging

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    Catalytic partial oxidation of methane with air was investigated in a reverse flow reactor with commercial Rh/A1(2)O(3) catalyst in pellets. Temperature profile of the catalyst bed was measured by fast IR thermography and product composition was measured with a continuous gas analyzer. The effect of internal heat recovery on reactor performance and catalyst thermal stress is presented and compared with steady state operation. Feed direction switching time, total flow rate, and methane to oxygen ratio were investigated as process operating parameters. Data of catalyst bed temperature evolution during the flow cycle are presented and discussed. Comparison of dynamic heat integration with external feed preheating in terms of product composition and catalyst temperature profile is also presented. (C) 2008 American Institute of Chemical Engineers

    First beam test of Laser Engineered Surface Structures (LESS) at cryogenic temperature in CERN SPS accelerator

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    Electron cloud mitigation is an essential requirement for accelerators of positive particles with high intensity beams to guarantee beam stability and limited heat load in cryogenic systems. Laser Engineered Surface Structures (LESS) are being considered, within the High Luminosity upgrade of the LHC collider at CERN (HL-LHC), as an option to reduce the Secondary Electron Yield (SEY) of the surfaces facing the beam, thus suppressing the elec-tron cloud phenomenon. As part of this study, a 2.2 m long Beam Screen (BS) with LESS has been tested at cryogenic temperature in the COLD bore EXperiment (COLDEX) facility in the SPS accelerator at CERN. In this paper, we describe the manufacturing procedure of the beam screen, the employed laser treatment technique and discuss our first observations in COLDEX confirming electron cloud suppression.Electron cloud mitigation is an essential requirement for accelerators of positive particles with high intensity beams to guarantee beam stability and limited heat load in cryogenic systems. Laser Engineered Surface Structures (LESS) are being considered, within the High Luminosity upgrade of the LHC collider at CERN (HL-LHC), as an option to reduce the Secondary Electron Yield (SEY) of the surfaces facing the beam, thus suppressing the electron cloud phenomenon. As part of this study, a 2.2 m long Beam Screen (BS) with LESS has been tested at cryogenic temperature in the COLD bore EXperiment (COLDEX) facility in the SPS accelerator at CERN. In this paper, we describe the manufacturing procedure of the beam screen, the employed laser treatment technique and discuss our first observations in COLDEX confirming electron cloud suppression

    Structures performance, benefit, cost-study

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    New technology concepts and structural analysis development needs which could lead to improved life cycle cost for future high-bypass turbofans were studied. The NASA-GE energy efficient engine technology is used as a base to assess the concept benefits. Recommended programs are identified for attaining these generic structural and other beneficial technologies

    The identification of tyrosine as a common key residue in unrelated H-2Kd restricted antigenic peptides

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    we have compared the activity of several Kd-or Ld-restricted antigenic peptides as competitors in a functional competition assay using cytolytic T lymphocyte (CTL) clones. All of four unrelated Kd-restricted peptides tested could compete with each other but not with the Ld-restricted peptide P91A-.12-24 (P91A). Moreover, the P91A peptide falled to compete with the four Kd-restricted peptides. In contrast, another Ld-restricted peptide[mouse cytomegalovirus (MCMV) pp89 167-176] could clearly compete with both Kd- and Ld-restricted peptides. The comparison of a series of modified MCMV pp89 peptides suggested that distinct structural features allow the Interaction of the peptide with the two different MHC class I molecules. We showed previously that the competitor activity of two different Kd-restricted antigenic peptides was reduced substantially upon Ala substitution of the single Tyr residues present in these peptides. We now show a similar effect for two additional Kd-restricted peptides. Our results thus suggest that Tyr may function as an ‘anchor' residue for many antigentic peptides that bind to the Kdmolecule. Molecular modeling of the presumed antigen-binding site of the Kdmolecule revealed the presence of two deep cavities that may be involved in binding peptide amino acid side chains. A model Illustrating one possible interaction of a Tyr-containing peptide with the Kdmolecule is presente

    Impact resistant boron/aluminum composites for large fan blades

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    Blade-like specimens were subjected to static ballistic impact testing to determine their relative FOD impact resistance levels. It was determined that a plus or minus 15 deg layup exhibited good impact resistance. The design of a large solid boron/aluminum fan blade was conducted based on the FOD test results. The CF6 fan blade was used as a baseline for these design studies. The solid boron/aluminum fan blade design was used to fabricate two blades. This effort enabled the assessment of the scale up of existing blade manufacturing details for the fabrication of a large B/Al fan blade. Existing CF6 fan blade tooling was modified for use in fabricating these blades

    Stress induced cardiomyopathy presenting as acute coronary syndrome: Tako-Tsubo in Mercogliano, Southern Italy

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    <p>Abstract</p> <p>Background</p> <p>Tako-tsubo syndrome (TTS) in its typical (apical) and atypical (non-apical) forms is being increasingly recognized in the West owing to early systematic coronary angiography in acute coronary syndromes (ACS).</p> <p>Aim of the study</p> <p>To assess the incidence, the clinical characteristics and the outcome of TTS in a single high volume cath lab in Southern Italy over the last 6 years.</p> <p>Methods</p> <p>Among 1674 consecutive patients (pts) referred to our coronary care units in the last 6 years (2001–2006) for ACS we selected 6 (0.5%) pts (6 women; age 57 ± 6 years) who fulfilled the following 4 criteria: 1) transient left ventricular wall motion abnormalities resulting in ballooning at contrast ventricolographic or echocardiographic evaluation; 2) normal coronary artery on coronary angiography performed 5 ± 9 hours from hospitalization; 3) new electrocardiographic ischemic-like abnormalities (either ST-segment elevation or T-wave inversion) and 4) emotional or physical trigger event.</p> <p>Results</p> <p>At admission all pts had presumptive diagnosis of ACS and ECG revealed ST elevation in 3 (50%) and T wave inversion with QT elongation in 3 (50%). In the acute phase cardiogenic shock occurred in 2 (33%) and heart failure in 1(16%). Presenting symptoms were chest pain in 6 (100%), dyspnoea in 2 (33%) and lipotimia in 1 (16%). At echocardiographic-ventricolographic assessment, the mechanical dysfunction (ballooning) was apical in all 6 pts ("classic" TTS). In all patients wall motion abnormalities completely reversed within 4.5 ± 1.5 days. The region of initial recovery was the anterior and lateral wall in 4 cases and the lateral wall in 2 cases. Ejection fraction was 35 ± 8% in the acute phase and increased progressively at discharge (55 ± 6%) and at 41 ± 20 months follow-up (60 ± 4%, p < 0.001 vs. baseline). All patients remained asymptomatic with minimal (aspirin, beta blockers, antihypertensive and antidislipidemic therapy) treatment.</p> <p>Conclusion</p> <p>Classic TTS is a frequent serendipitous diagnosis after coronary angiography showed "surprisingly" normal findings in a clinical setting mimicking an ACS. Despite its long-term good prognosis life threatening complications in the acute phase can occur.</p

    Anosognosia in Early- and Late-Onset Dementia and Its Association With Neuropsychiatric Symptoms

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    Background: The symptom anosognosia or unawareness of disease in dementia has mainly been studied in patients with late-onset dementia (LOD, ≥65 years), whereas little is known on whether it is also present in patients with early-onset dementia (EOD, &lt;65 years). We aimed at investigating differences in anosognosia between LOD and EOD, by also studying its association with different clinical variants of EOD and the presence of neuropsychiatric symptoms. Methods: A total of 148 patients, 91 EOD and 57 LOD, were recruited and underwent extended clinical assessment and caregiver interview that included questionnaires aimed at measuring anosognosia and neuropsychiatric symptoms. Differences in anosognosia between EOD and LOD and between subgroups with different clinical variants were investigated, as well as correlation between anosognosia and neuropsychiatric symptoms. A regression analysis was applied to explore the association between anosognosia and development of neuropsychiatric symptoms during disease progression. Results: Median levels of anosognosia were not significantly different between EOD and LOD. Anosognosia increased overtime with disease progression and was higher in frontotemporal dementia patients or, more precisely, in frontotemporal dementia and Alzheimer's disease variants associated with involvement of the frontal lobes. Higher levels of early anosognosia were associated with higher frequency and severity of subsequent neuropsychiatric symptoms, in particular apathy, later in the course of the disease. Conclusion: Anosognosia is a frequent symptom of EOD, occurring in 94.5% of all-cause EOD, and it is associated with higher risk of developing neuropsychiatric symptoms during disease progression. Recognising anosognosia may be helpful for clinicians and families to reduce diagnostic delay and improve disease managment

    Drug-eluting balloons for the treatment of the superficial femoral artery in-stent restenosis: 2-year follow-up.

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    OBJECTIVES: The aim of this prospective registry was to evaluate the safety and efficacy at 2-year follow-up of the use of drug-eluting balloons (DEBs) for the treatment of superficial femoral artery (SFA) in-stent restenosis (ISR). BACKGROUND: The use of DEBs for the treatment of SFA ISR is associated with a satisfactory primary patency rate at 1 year, but no data are available for longer follow-up. Unfortunately, when DEBs were used to treat SFA de novo lesions, the occurrence of restenosis increased by 50% between the first and the second years of follow-up. METHODS: From December 2009 to December 2010, 39 consecutive patients underwent percutaneous transluminal angioplasty of SFA ISR at our institution (Clinica Montevergine, Mercogliano, Italy). All patients underwent conventional SFA percutaneous transluminal angioplasty and final post-dilation with paclitaxel-eluting balloons (IN.PACT, Medtronic Inc., Minneapolis, Minnesota). Patients were evaluated for up to 24 months. RESULTS: During follow-up, 1 patient died of heart failure and another of sudden death, for a 2-years rate of cardiovascular mortality rate of 5.12 %. The primary patency rate at 2 years was 70.3% (11 of 37 patients experienced restenosis recurrence at 2-year follow-up). The treatment of complex ISR lesions (classes II and III) was associated with an increased rate of recurrent restenosis compared with class I (33.3 % and 36.3 % vs. 12.5%; p = 0.05). CONCLUSIONS: The data suggest that adjunctive use of DEBs for the treatment of SFA ISR is a safe and effective therapeutic strategy up to 2 years of follow-up

    Predictors of carotid occlusion intolerance?during proximal protected?carotid artery?stenting.

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    OBJECTIVES: The aim of this study was to identify predictors of occlusion intolerance (OI) developing during proximal protected carotid artery stenting (CAS). BACKGROUND: The use of proximal embolic protection devices, such as endovascular occlusion, during CAS has been demonstrated to be particularly safe and effective. However, endovascular occlusion can expose the ipsilateral hemisphere to hypoperfusion and produce transient neurological symptoms (OI). METHODS: From March 2010 to March 2012, 605 consecutive patients underwent proximal protected CAS at our institution. To identify independent predictors of OI, a multivariate logistic regression model was developed that included all patients' clinical/angiographic and procedural characteristics. RESULTS: OI developed in a total of 184 patients (30.4%). Compared with patients in whom OI did not develop, those who experienced OI had lower occlusion pressure (OP) (42.3 ± 12.7 mm Hg vs. 61.9 ± 15.4 mm Hg, p < 0.001). Receiver-operating characteristic curve analysis demonstrated that OP was the most consistent predictor of OI with a C-statistic of 0.85 (95% confidence interval [CI]: 0.82 to 0.88) with best cutoff being ≤40 mm Hg (sensitivity, 68.5%; specificity, 93.3%). By logistic regression analysis, the most powerful independent predictor of OI developing was an OP ≤40 mm Hg (odds ratio: 33.2, 95% CI: 19.1 to 57.7) and the most powerful clinical predictor of such OP was the presence of contralateral internal carotid artery occlusion (odds ratio: 3.1, 95% CI: 1.5 to 6.2). CONCLUSIONS: OI may occur in as many as one-third of the patients undergoing proximal protected CAS. This event is more common in those patients with an OP ≤40 mm Hg. Patients presenting with concomitant occlusion of the contralateral internal carotid artery more frequently have an OP ≤40 mm Hg
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