Intensity noise in difference frequency generation-based tunable femtosecond MIR sources.

We characterize the intensity noise of two mid-infrared (MIR) ultrafast tunable (3.5-11 µm) sources based on difference frequency generation (DFG). While both sources are pumped by a high repetition rate Yb-doped amplifier delivering 200 µJ 300 fs at a central wavelength of 1030 nm, the first is based on intrapulse DFG (intraDFG), and the second on DFG at the output of an optical parametric amplifier (OPA). The noise properties are assessed through measurement of the relative intensity noise (RIN) power spectral density and pulse-to-pulse stability. The noise transfer mechanisms from the pump to the MIR beam is empirically demonstrated. As an example, improving the pump laser noise performance allows reduction of the integrated RIN (IRIN) of one of the MIR source from 2.7% RMS down to 0.4% RMS. The intensity noise is also measured at various stages and in several wavelength ranges in both laser system architectures, allowing us to identify the physical origin of their variation. This study presents numerical values for the pulse to pulse stability, and analyze the frequency content of the RINs of particular importance for the design of low-noise high repetition rate tunable MIR sources and future high performance time-resolved molecular spectroscopy experiments.

Calcineurin Inhibitors in the Treatment of Adult Autoimmune Hepatitis: A Systematic Review.

Background and Aims: A considerable number of autoimmune hepatitis (AIH) patients completely or partially fail on first-line treatment. Several studies on the use of calcineurin inhibitors (CNIs) in the treatment of AIH have been published without focusing on indication. The aim was to assess the efficacy of CNIs in the treatment of adult AIH patients, specifically focusing on indication: first-line intolerant and with first-line insufficient response (failure to achieve or maintain remission), and with second versus third-line treatment. Methods: A literature search included studies on the use of CNIs in adult AIH. Patients with past or present use of CNIs from the Dutch AIH group cohort were added. The primary endpoint was biochemical remission while using CNIs. Secondary endpoints were biochemical response, treatment failure, and adverse effects. Results: Twenty studies from the literature and nine Dutch patients were included describing the use of cyclosporine in 59 and tacrolimus in 219 adult AIH patients. The CNI remission rate was 53% in patients with insufficient response to first-line treatment and 67% in patients intolerant to first-line treatment. CNIs were used as second-line treatment in 73% with a remission rate of 52% and as third-line treatment in 22% with a remission rate of 26%. Cyclosporine was discontinued in 13% and tacrolimus in 11% of patients because of adverse events. Conclusions: CNIs as rescue treatment in adult AIH patients are reasonably effective and safe both with insufficient response or intolerance to previous treatment. Prospective studies are needed.

Inline amplification of mid-infrared intrapulse difference frequency generation.

We demonstrate an ultrafast mid-infrared source architecture that implements both intrapulse difference frequency generation (iDFG) and further optical parametric amplification (OPA), in an all-inline configuration. The source is driven by a nonlinearly compressed high-energy Yb-doped-fiber amplifier delivering 7.4 fs pulses at a central wavelength of 1030 nm, at a repetition rate of 250 kHz. It delivers 1 µJ, 73 fs pulses at a central wavelength of 8 µm, tunable over more than one octave. By enrolling all the pump photons in the iDFG process and recycling the long wavelength pump photons amplified in the iDFG in the subsequent OPA, we obtain an unprecedented overall optical efficiency of 2%. These performances, combining high energy and repetition rate in a very simple all-inline setup, make this technique ideally suited for a growing number of applications, such as high harmonic generation in solids or two-dimensional infrared spectroscopy experiments.

Enhanced intrapulse difference frequency generation in the mid-infrared by a spectrally dependent polarization state.

We present a technique to optimize the intrapulse difference frequency generation efficiency for mid-infrared generation. The approach employs a multi-order wave plate that is designed to selectively rotate the polarization state of the incoming spectral components on the relevant orthogonal axes for subsequent nonlinear interaction. We demonstrate a significant increase of the mid-infrared average power generated, of a factor ≥2.5 compared with the conventional scheme, owing to an optimally distributed number of photons enrolled in the difference frequency generation process.

Mechanism and dynamics of fatty acid photodecarboxylase.

Fatty acid photodecarboxylase (FAP) is a photoenzyme with potential green chemistry applications. By combining static, time-resolved, and cryotrapping spectroscopy and crystallography as well as computation, we characterized Chlorella variabilis FAP reaction intermediates on time scales from subpicoseconds to milliseconds. High-resolution crystal structures from synchrotron and free electron laser x-ray sources highlighted an unusual bent shape of the oxidized flavin chromophore. We demonstrate that decarboxylation occurs directly upon reduction of the excited flavin by the fatty acid substrate. Along with flavin reoxidation by the alkyl radical intermediate, a major fraction of the cleaved carbon dioxide unexpectedly transformed in 100 nanoseconds, most likely into bicarbonate. This reaction is orders of magnitude faster than in solution. Two strictly conserved residues, R451 and C432, are essential for substrate stabilization and functional charge transfer.

Frequency-domain two-dimensional infrared spectroscopy using an acousto-optic programmable dispersive filter.

We report on multidimensional spectroscopy in the mid-infrared, performed using a calomel-based acousto-optic programmable dispersive filter. Although the associated spectral resolution is currently not as good as what has been previously reported using time-domain interferometers or other pulse-shaping technologies, the extreme compactness of the calomel crystal allows a straightforward implementation in a pre-existing pump-probe setup. Furthermore, the frequency-domain approach allows easy measurement of 2D slices of the multidimensional spectrum associated with a given pump frequency. We demonstrate our method with the measurement of the mid-infrared spectrum of carboxy-hemoglobin in three spectro-temporal dimensions.

La coccidioidomicosis en Argentina, 1892-2009 / Coccidioidomycosis in Argentina, 1892-2009

Los casos clínicos de coccidioidomicosis en Argentina son pocos y han tenido lugar fundamentalmente en la extensa región árida precordillerana. Este trabajo tiene como objetivos realizar una revisión retrospectiva del total de casos de coccidioidomicosis documentados en Argentina desde el año 1892 hasta 2009 y describir una serie de casos ocurridos en los últimos 4 años. En 117 años se documentaron 128 casos. Desde la primera descripción de la enfermedad en 1892 hasta 1939 se registraron 6 casos; desde 1940 hasta 1999, 59 casos (6-14 casos cada 10 años); y los 63 casos restantes (49% del total histórico) se produjeron en el último decenio. La mediana de edad de los 34 pacientes registrados en el período 2006-2009 fue de 31 años (rango: 7-89), la relación hombre:mujer fue 1,3:1; 12 de estos individuos eran inmunocomprometidos. Veintiséis casos se confirmaron por examen microscópico, por cultivo o por ambos procedimientos; los casos restantes se confirmaron por serología. Todos los aislamientos recuperados fueron identificados como Coccidioides posadasii. Treinta pacientes residían en una amplia área geográfica con epicentro en el valle de Catamarca. Entre 2006 y 2009, la tasa de incidencia en la provincia de Catamarca se incrementó desde valores históricos inferiores a 0,5 casos cada 100 000 habitantes hasta 2,0 casos cada 100 000 habitantes. Este aumento sugiere una emergencia de la coccidioidomicosis en el área.

Clinical cases of coccidioidomycosis are rare in Argentina and are generally found in the large arid precordilleran area of the country. This study aims to perform a retrospective review of all coccidioidomycosis cases documented in the country from 1892 to 2009, and to describe those occurring in the last 4 years. One hundred and twenty eight cases were documented in the 117 year-period. Since the original description of the disease in 1892 until 1939, only 6 cases were registered; between 1940 and 1999, 59 (6-14/10 yrs) and the remaining 63 (49% of total cases) occurred in the last decade. The median age of 34 patients registered in 2006-2009 was 31 years (range: 7-89), male/female ratio was 1.3:1 and 12 patients were immunocompromised. Twenty-six cases were confirmed by direct microscopy and/or culture whereas the remaining ones by serology. All isolates were identified as Coccidioides posadasii. Thirty patients lived in a vast geographic region with epicenter in Catamarca Valley. Between 2006 and 2009, annual disease incidence rates in Catamarca Province increased from historical values below 0.5/100,000 to 2/100,000 inhabitants. Such increase suggests an emergency of coccidioidomycosis in that region.

[Coccidioidomycosis in Argentina, 1892-2009]. / La coccidioidomicosis en Argentina, 1892-2009.

Clinical cases of coccidioidomycosis are rare in Argentina and are generally found in the large arid precordilleran area of the country. This study aims to perform a retrospective review of all coccidioidomycosis cases documented in the country from 1892 to 2009, and to describe those occurring in the last 4 years. One hundred and twenty eight cases were documented in the 117 year-period. Since the original description of the disease in 1892 until 1939, only 6 cases were registered; between 1940 and 1999, 59 (6-14/10 yrs) and the remaining 63 (49% of total cases) occurred in the last decade. The median age of 34 patients registered in 2006-2009 was 31 years (range: 7-89), male/female ratio was 1.3:1 and 12 patients were immunocompromised. Twenty-six cases were confirmed by direct microscopy and/or culture whereas the remaining ones by serology. All isolates were identified as Coccidioides posadasii. Thirty patients lived in a vast geographic region with epicenter in Catamarca Valley. Between 2006 and 2009, annual disease incidence rates in Catamarca Province increased from historical values below 0.5/100,000 to 2/100,000 inhabitants. Such increase suggests an emergency of coccidioidomycosis in that region.

[The scientific journey taken by Neiva and Penna: a blueprint for studies of diseases from the Brazilian hinterland]. / A viagem científica de Neiva e Penna: roteiro para os estudos das doenças do sertão.

Analyze the report by Neiva and Penna, focusing on the contribution these authors made to the study of one of the endemic diseases encountered throughout their journey, which had been long known under the popular name of mal de engasgo (choking disease). They recorded their observations and detailed descriptions of the patients' symptoms and the association frequently encountered between mal de engasgo and another endemic disease, known as vexame or vexame do coração, characterized by bouts of palpitations. Neiva and Penna's epidemiological and clinical observations of mal de engasgo were crucial for all the researchers interested in the disease, especially its relationship with Chagas disease.

A viagem científica de Neiva e Penna: roteiro para os estudos das doenças do sertão / The scientific journey taken by Neiva and Penna: a blueprint for studies of diseases from the Brazilian hinterland

Analisa o relatório de Arthur Neiva e Belisario Penna , focalizando a contribuição dos autores ao estudo de uma das doenças endêmicas por eles encontrada ao longo de todo o trajeto percorrido, de longa data conhecida popularmente por 'mal de engasgo'. Observaram e descreveram com minúcia os sintomas apresentados pelos doentes e a associação frequente do mal de engasgo com outro mal endêmico conhecido por 'vexame' ou 'vexame do coração', que consistia em crises de palpitações. Os estudos epidemiológicos e clínicos de Neiva e Penna sobre o mal de engasgo muito contribuíram para o conhecimento dessa afecção e representaram um incentivo para todos os pesquisadores que se dedicaram ao seu estudo, especialmente quanto a sua relação com a doença de Chagas.

Analyze the report by Neiva and Penna, focusing on the contribution these authors made to the study of one of the endemic diseases encountered throughout their journey, which had been long known under the popular name of mal de engasgo (choking disease). They recorded their observations and detailed descriptions of the patients' symptoms and the association frequently encountered between mal de engasgo and another endemic disease, known as vexame or vexame do coração, characterized by bouts of palpitations. Neiva and Penna's epidemiological and clinical observations of mal de engasgo were crucial for all the researchers interested in the disease, especially its relationship with Chagas disease.