300 research outputs found

    High-order harmonic generation driven by chirped laser pulses induced by linear and non linear phenomena

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    We present a theoretical study of high-order harmonic generation (HHG) driven by ultrashort optical pulses with different kind of chirps. The goal of the present work is perform a detailed study to clarify the relevant parameters in the chirped pulses to achieve a noticeable cut-off extensions in HHG. These chirped pulses are generated using both linear and nonlinear dispersive media.The description of the origin of the physical mechanisms responsible of this extension is, however, not usually reported with enough detail in the literature. The study of the behaviour of the harmonic cut-off with these kind of pulses is carried out in the classical context, by the integration of the Newton-Lorentz equation complemented with the quantum approach, based on the integration of the time dependent Schr\"odinger equation in full dimensions (TDSE-3D), we are able to understand the underlying physics.Comment: 13 pages, 8 figure

    The Problem of Prickling on Fabrics of South American Camelids Fibers: Possible Approaches for Mechanical Solutions

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    In this minireview it is to analyze the physical attributes that determine the comfort of fabrics made of South American Camelid fibers (Lama and Alpaca), discuss the effect on their textile value and evaluate an possible approache on their possible mechanical solutions. Taking the distribution of all fibers do not respond to a normal distribution, but the different fiber types identified by the type of medulla, they do respond to a normal distribution. While emphasis has always been on mean fiber diameter, the fiber frequency exceeding 30 microns (objectionable fibres) has a key role in quality. This is essential for light fabrics, where the effect of prickle plays a critical part in consumer´s choice. Dehairing, as a mechanical way, provides an immediate solution, though excessive fiber breakage should be addressed. It is concluded that the textile fiber quality of South American Camelids is promissory if the presence of objectionable fibers is solved, resulting in a tolerable frequency for consumers (<3%). This implies a true paradigm shift with regard to the classic textile processing of Alpaca and Lama fibers (from worsted to woolen system). This would enhance the fiber softness to touch, together with other important features that would render the fiber price more competitive

    Buried waveguides in Nd:YLF crystals obtained by femtosecond laser writing under double line approach

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    In this paper, we present buried waveguides fabricated by fs laser writing in Nd3+ doped YLF crystal under double line approach (Miura et al. in Appl. Phys. Lett. 71:3329–3331, 1997). The waveguides were made by focusing two consecutive optical breakdown tracks (OBT) separated by about 20 μm. To make the optimal OBT, we focused the fs-laser pulses 200 μm below surface at intensities above the OB threshold for the material and controlled the writing speed. The guiding structures were fabricated by using a Chirped Pulse Amplification (CPA) femtosecond (fs) laser system. We chose the optimal writing parameters in order to obtain suitable waveguides, using around 3 μJ energy and writing speed from 15 to 50 μm/s. After optically exploring the waveguides by end-fire coupling, the guiding structures showed good optical performance. Guiding index profiles were retrieved from modal analysis by using BeamProp (RSoft) commercial software. This spatial distribution of the index increment, taking into account a lower refractive barrier on the OBT region plus the compressed region between the tracks, was obtained correctly fitting profiles modes. Finally, optical spectroscopy measurements were also performed in the waveguides. The results showed that the luminescence properties of Nd3+ ions are preserved in the waveguides compared with the values obtained for bulk.This work was partially supported by Agencia Nacional de Promoción Científica y Tecnólogica. (Argentina) under project PICT-2575 and CONICET (Argentina) under project PIP 0394 and by “Ministerio de Educación y Ciencia,” Spain (Grant no FIS2009-09522 and Consolider Program SAUUL CSD2007-00013). D.B. wishes to thank Comisión de Investigaciones Científicas (Bs. As., Argentina) for his student fellowship

    Acute kidney injury contributes to worse physical and quality of life outcomes in survivors of critical illness

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    Objectives: Survivors of critical illness and acute kidney injury (AKI) are at risk of increased morbidity. The purpose of this study was to compare physical, emotional, and cognitive health in survivors of critical illness with and without AKI. Methods: Retrospective cohort study of adult (≥ 18 years old) survivors of critical illness due to sepsis and/or acute respiratory failure who attended follow-up in a specialized ICU Recovery Clinic. Outcomes were evaluated during 3-month visit and comprised validated tests for evaluation of physical function, muscle strength, cognitive and emotional health, and self-reported health-related quality of life (HRQOL). Descriptive statistics and group comparisons were performed. Results: A total of 104 patients with median age of 55 [49-64] years, 54% male, and median SOFA score of 10 [8-12] were analyzed. Incidence of AKI during ICU admission was 61 and 19.2% of patients required renal replacement therapy (RRT). Patients with AKI stage 2 or 3 (vs. those with AKI stage 1 or no AKI) walked less on the 6-min walk test (223 ± 132 vs. 295 ± 153 m, p = 0.059) and achieved lower of the predicted walk distance (38% vs. 58%, p = 0.041). Similar patterns of worse physical function and more significant muscle weakness were observed in multiple tests, with overall worse metrics in patients that required RRT. Patients with AKI stage 2 or 3 also reported lower HRQOL scores when compared to their counterparts, including less ability to return to work or hobby, or reengage in driving. There were no significant differences in cognitive function or emotional health between groups. Conclusions: Survivors of critical illness and AKI stage 2 or 3 have increased physical debility and overall lower quality of life, with more impairment in return to work, hobby, and driving when compared to their counterparts without AKI or AKI stage 1 at 3 months post-discharge

    Safety, Feasibility, and Efficacy of Early Rehabilitation in Patients Requiring Continuous Renal Replacement: A Quality Improvement Study

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    Introduction: Early rehabilitation in critically ill patients is associated with improved outcomes. Recent research demonstrates that patients requiring continuous renal replacement therapy (CRRT) can safely engage in mobility. The purpose of this study was to assess safety and feasibility of early rehabilitation with focus on mobility in patients requiring CRRT. Methods: Study design was a mixed methods analysis of a quality improvement protocol. The setting was an intensive care unit (ICU) at a tertiary medical center. Safety was prospectively recorded by incidence of major adverse events including dislodgement of CRRT catheter, accidental extubation, bleeding, and hemodynamic emergency; and minor adverse events such as transient oxygen desaturation \u3e 10% of resting. Limited efficacy testing was performed to determine if rehabilitation parameters were associated with clinical outcomes. Results: A total of 67 patients (54.0 ± 15.6 years old, 44% women, body mass index 29.2 ± 9.3 kg/m2) received early rehabilitation under this protocol. The median days of CRRT were 6.0 (interquartile range [IQR], 2–11) and 72% of patients were on mechanical ventilation concomitantly with CRRT at the time of rehabilitation. A total of 112 rehabilitation sessions were performed of 152 attempts (74% completion rate). No major adverse events occurred. Patients achieving higher levels of mobility were more likely to be alive at discharge (P = 0.076). Conclusions: The provision of early rehabilitation in critically ill patients requiring CRRT is safe and feasible. Further, these preliminary results suggest that early rehabilitation with focus on mobility may improve patient outcomes in this susceptible population

    Pneumocystis primary infection in non-immunosuppressed infants in Lima, Peru

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    Objectives: To provide original data on Pneumocystis primary infection in non-immunosuppressed infants from Peru. / Methods: A cross sectional study was performed. Infants less than seven months old, without any underlying medical conditions attending the “well baby” outpatient clinic at one hospital in Lima, Peru were prospectively enrolled during a 15-month period from November 2016 to February 2018. All had a nasopharyngeal aspirate (NPA) for detection of P. jirovecii DNA using a PCR assay, regardless of respiratory symptoms. P. jirovecii DNA detection was considered to represent pulmonary colonization contemporaneous with Pneumocystis primary infection. Associations between infants’ clinical and demographic characteristics and results of P. jirovecii DNA detection were analyzed. / Results: P. jirovecii DNA was detected in 45 of 146 infants (30.8%) and detection was not associated with concurrent respiratory symptoms in 40 of 45 infants. Infants with P. jirovecii had a lower mean age when compared to infants not colonized (p <0.05). The highest frequency of P. jirovecii was observed in 2-3-month-old infants (p < 0.01) and in the cooler winter and spring seasons (p <0.01). Multivariable analysis showed that infants living in a home with ≤ 1 bedroom were more likely to be colonized; Odds Ratio =3.03 (95%CI 1.31-7.00; p =0.01). / Conclusion: Pneumocystis primary infection in this single site in Lima, Peru, was most frequently observed in 2-3-month-old infants, in winter and spring seasons, and with higher detection rates being associated with household conditions favoring close inter-individual contacts and potential transmission of P. jirovecii

    Packed Red Blood Cell Transfusion Associates with Acute Kidney Injury After Transcatheter Aortic Valve Replacement

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    Background: Acute kidney injury after cardiac surgery significantly associates with morbidity and mortality. Despite not requiring cardiopulmonary bypass, transcatheter aortic valve replacement patients have an incidence of post-procedural acute kidney injury similar to patients who undergo open surgical aortic valve replacement. Packed red blood cell transfusion has been associated with morbidity and mortality after cardiac surgery. We hypothesized that packed red blood cell transfusion independently associates with acute kidney injury after transcatheter aortic valve replacement, after accounting for other risk factors. Methods: This is a single-center retrospective cohort study of 116 patients undergoing transcatheter aortic valve replacement. Post-transcatheter aortic valve replacement acute kidney injury was defined by Kidney Disease: Improving Global Outcomes serum creatinine-based criteria. Univariate comparisons between patients with and without post-transcatheter aortic valve replacement acute kidney injury were made for clinical characteristics. Multivariable logistic regression was used to assess independent association of packed red blood cell transfusion with post-transcatheter aortic valve replacement acute kidney injury (adjusting for pre-procedural renal function and other important clinical parameters). Results: Acute kidney injury occurred in 20 (17.2%) subjects. Total number of packed red blood cells transfused independently associated with post-procedure acute kidney injury (OR = 1.67 per unit, 95% CI 1.13–2.47, P = 0.01) after adjusting for pre-procedure estimated glomerular filtration rate (OR = 0.97 per ml/min/1.73m2, 95% CI 0.94–1.00, P = 0.05), nadir hemoglobin (OR = 0.88 per g/dL increase, CI 0.61–1.27, P = 0.50), and post-procedure maximum number of concurrent inotropes and vasopressors (OR = 2.09 per inotrope or vasopressor, 95% CI 1.19–3.67, P = 0.01). Conclusion: Packed red blood cell transfusion, along with post-procedure use of inotropes and vasopressors, independently associate with acute kidney injury after transcatheter aortic valve replacement. Further studies are needed to elucidate the pathobiology underlying these associations

    Investigaciones antropobiológicas en el contexto de la Arqueología de Rescate : Tafí del Valle, provincia de Tucumán

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    Introducción: En el marco de los trabajos de Arqueología de Rescate efectuados en Los Cuartos, en el este de Tafí del Valle, provincia de Tucumán se ha descubierto un contexto funerario muy afectado por procesos postdepositacionales. En este trabajo presentamos los estudios antropobiológicos efectuados sobre el material óseo recuperado. Los mismos se han orientado a obtener información sobre las características biológicas, tales como: edad a la muerte, sexo probable, condiciones de vida y otros elementos que aporten a la interpretación del evento funerario en sí mismo. Materiales y métodos: La muestra esqueletaria estudiada comprende un cráneo y algunos elementos postcraneales extraídos en excavación. Se realizó análisis morfoscópico para obtener información que permitiera la estimación de sexo y edad de muerte. Así mismo se procuró establecer posibles traumas y paleopatologías. Resultados: A través de la información obtenida de los elementos óseos se pudo establecer que los mismos corresponden a un individuo adulto de sexo femenino. El mismo no presenta deformación craneal cultural y/o paleopatologías. Conclusión: El esqueleto corresponde a un solo individuo de sexo femenino, el que fue colocado en el piso de un recinto habitacional, cubierto por grandes piedras. Se encuentra asociado con material cerámico asignable a la Cultura Tafí.Asociación de Antropología Biológica de la República Argentin

    Investigaciones antropobiológicas en el contexto de la Arqueología de Rescate : Tafí del Valle, provincia de Tucumán

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    Introducción: En el marco de los trabajos de Arqueología de Rescate efectuados en Los Cuartos, en el este de Tafí del Valle, provincia de Tucumán se ha descubierto un contexto funerario muy afectado por procesos postdepositacionales. En este trabajo presentamos los estudios antropobiológicos efectuados sobre el material óseo recuperado. Los mismos se han orientado a obtener información sobre las características biológicas, tales como: edad a la muerte, sexo probable, condiciones de vida y otros elementos que aporten a la interpretación del evento funerario en sí mismo. Materiales y métodos: La muestra esqueletaria estudiada comprende un cráneo y algunos elementos postcraneales extraídos en excavación. Se realizó análisis morfoscópico para obtener información que permitiera la estimación de sexo y edad de muerte. Así mismo se procuró establecer posibles traumas y paleopatologías. Resultados: A través de la información obtenida de los elementos óseos se pudo establecer que los mismos corresponden a un individuo adulto de sexo femenino. El mismo no presenta deformación craneal cultural y/o paleopatologías. Conclusión: El esqueleto corresponde a un solo individuo de sexo femenino, el que fue colocado en el piso de un recinto habitacional, cubierto por grandes piedras. Se encuentra asociado con material cerámico asignable a la Cultura Tafí.Asociación de Antropología Biológica de la República Argentin
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