Fiber-connectorized ultrafast-laser-inscribed K-band integrated optics beam combiner for the CHARA telescope array.

A fiber-connectorized K-band integrated-optics two-telescope beam combiner was developed for long-baseline interferometry at the CHARA telescope array utilizing the ultrafast laser inscription (ULI) technique. Single-mode waveguide insertion losses were measured to be ∼1.1d B over the 2-2.3 µm window. The development of asymmetric directional couplers enabled the construction of a beam combiner that includes a 50:50 coupler for interferometric combination and two ∼75:25 couplers for photometric calibration. The visibility of the bare beam combiner was measured at 87% and then at 82% after fiber-connectorization by optimizing the input polarization. These results indicate that ULI technique can fabricate efficient fiber-connectorized K-band beam combiners for astronomical purposes.

Six-telescope integrated optics beam combiner fabricated using ultrafast laser inscription for J- and H-band astronomy.

We have built and characterized, to our knowledge, the first six-telescope discrete beam combiner (DBC) for stellar interferometry in the astronomical J-band. It is the DBC with the largest number of beam combinations and was manufactured using ultrafast laser inscription in borosilicate glass, with a throughput of ≈56%. For calibration of the visibility-to-pixel matrix, we use a two-input Michelson interferometer and extract the complex visibility. A visibility amplitude of 1.05 and relative precision of 2.9% and 3.8% are extracted for 1328 nm and 1380 nm, respectively. Broadband (≤40n m) characterization is affected by dispersion but shows similar performance.

Complicaciones del cateterismo cardiaco en cardiopatías congénitas, 30 años de experiencia. Un nuevo score ajustado al riesgo / Complications of cardiac catheterisation in congenital heart disease, 30 years of experience. A new risk-adjusted score

Resumen Objetivo: Presentar un score ajustado al riesgo de complicaciones durante el cateterismo cardiaco en cardiopatías congénitas. Diseño: Observacional, analítico y ambispectivo de 3,504 casos. Se incluyeron edad, cardiopatía, procedimiento, complicaciones mayores y menores. Métodos: 3,504 procedimientos realizados entre octubre de 1987 y mayo de 2019. Variables independientes: edad, cardiopatía, procedimiento y estadio clínico. Se categorizó como bajo riesgo 5 a 7 puntos, moderado riesgo 8 a 11 puntos y alto riesgo 12 a 22 puntos. El score fue validado mediante la prueba de Hosmer-Lemeshow y la curva ROC (receiver operating characteristic). Resultados: Las complicaciones fueron 177 (5%), 66 mayores (1.9%) y 111 menores (3.1%). Mortalidad de 0.4% (15 pacientes). El grupo de bajo riesgo (n = 825) tuvo 1.5% de complicaciones, el de moderado riesgo (n = 2.221) 4.9% y el de alto riesgo (n = 458) 12% (p < 0.001). El análisis de los datos retrospectivos (n = 2,953) fue validado con los prospectivos (n = 551) mediante la prueba de Hosmer-Lemeshow; dejó en evidencia que los valores predichos son similares a los observados. Conclusiones: Las complicaciones siguen presentándose a pesar de la evolución de la técnica. El score resultó útil para estratificar a los pacientes y conocer la probabilidad de complicaciones antes del procedimiento.

Abstract Objetive: to present a risk-ajusted score of complications during cardias catheterization in congenital heart disease. Design: observational, analitic, ambispective of 3.504 cases. The data analyzed included age, heart disease, type of procedure, major and minor complications. Methods: 3.504 procedures performed between october 1987 and may 2019. The variables were age, heart disease, procedere and clinical stege. Each patients was categorized as low risk 5 to 7 points, moderate risk 8 to 11 points and higt risk 12 to 22 points. The score was validated using the Hosmer-Lemeshow test and the ROC curve (Receiver Operating Characteristic). Results: complications 177 (5%) 66 major (1.9%) and 111 minor (3.1%). Mortality was 0.4% (15 patients). The low-risk group (n = 825) had 1.5% complications; moderate risk (n = 2,221) 4.9%; high risk (n: 458) 12% (p < 0.001). The analysis of the retrospective data (n = 2953) was validated with prospective (n = 551) using the Hosmer-Lemeshow test, showed that the predicted values are similar to those observed. Conclusions: Complications continue to occur despite the evolution of the technique. The score was useful for stratifying patients and knowing the probability of complication before the procedere.

[Complications of cardiac catheterisation in congenital heart disease. 30 years of experience. A new risk-adjusted score]. / Complicaciones del cateterismo cardiaco en cardiopatías congénitas. 30 años de experiencia. Un nuevo score ajustado al riesgo.

Objetive: To present a risk-ajusted score of complications during cardias catheterization in congenital heart disease. Design: observational, analitic, ambispective of 3.504 cases. The data analyzed included age, heart disease, type of procedure, major and minor complications. Methods: 3.504 procedures performed between october 1987 and may 2019. The variables were age, heart disease, procedere and clinical stege. Each patients was categorized as low risk 5 to 7 points, moderate risk 8 to 11 points and higt risk 12 to 22 points. The score was validated using the Hosmer-Lemeshow test and the ROC curve (Receiver Operating Characteristic). Results: complications 177 (5%) 66 major (1.9%) and 111 minor (3.1%). Mortality was 0.4% (15 patients). The low-risk group (n = 825) had 1.5% complications; moderate risk (n = 2,221) 4.9%; high risk (n: 458) 12% (p < 0.001). The analysis of the retrospective data (n = 2953) was validated with prospective (n = 551) using the Hosmer-Lemeshow test, showed that the predicted values are similar to those observed. Conclusions: Complications continue to occur despite the evolution of the technique. The score was useful for stratifying patients and knowing the probability of complication before the procedere.

Objetivo: Presentar un score ajustado al riesgo de complicaciones durante el cateterismo cardiaco en cardiopatías congénitas. Diseño: Observacional, analítico y ambispectivo de 3,504 casos. Se incluyeron edad, cardiopatía, procedimiento, complicaciones mayores y menores. Métodos: 3,504 procedimientos realizados entre octubre de 1987 y mayo de 2019. Variables independientes: edad, cardiopatía, procedimiento y estadio clínico. Se categorizó como bajo riesgo 5 a 7 puntos, moderado riesgo 8 a 11 puntos y alto riesgo 12 a 22 puntos. El score fue validado mediante la prueba de Hosmer-Lemeshow y la curva ROC (receiver operating characteristic). Resultados: Las complicaciones fueron 177 (5%), 66 mayores (1.9%) y 111 menores (3.1%). Mortalidad de 0.4% (15 pacientes). El grupo de bajo riesgo (n = 825) tuvo 1.5% de complicaciones, el de moderado riesgo (n = 2.221) 4.9% y el de alto riesgo (n = 458) 12% (p < 0.001). El análisis de los datos retrospectivos (n = 2,953) fue validado con los prospectivos (n = 551) mediante la prueba de Hosmer-Lemeshow; dejó en evidencia que los valores predichos son similares a los observados. Conclusiones: Las complicaciones siguen presentándose a pesar de la evolución de la técnica. El score resultó útil para estratificar a los pacientes y conocer la probabilidad de complicaciones antes del procedimiento.

Effectiveness of a program for the reduction of central venous catheter-related bacteremias in a Pediatric Cardiovascular Unit / Efectividad de un programa de reducción de bacteriemias relacionadas con catéter venoso central en una unidad cardiovascular pediátrica

INTRODUCTION: Central venous catheter (CVC)- related bacteremias are common in pediatric patients following surgery for complex congenital heart disease admitted to a pediatric cardiac intensive care unit (PCICU) and have a high morbidity and mortality. OBJECTIVE: To analyze the effectiveness of an interdisciplinary program for the prevention of CVC-related bacteremias in the PCICU. MATERIAL AND METHODS: Quasi-experimental, before and after implementation study without a control group. Study period: 01-01-2008 to 12- 31-2018. Population: PCICU staff who care for patients following surgery for complex heart disease at a hospital. Pre-intervention period: 01- 01-2008 to 12-31-2008; intervention period: 01-01- 2009 to 01-01-2018. Intervention: implementation of an ongoing improvement program. The rate of CVC-related bacteremias/1000 days and CVC use/100 days, RACHS score, standardized infection ratio (SIR), relative risk (RR), and 95% confidence interval (CI) were analyzed and a p value < 0.05 was considered statistically significant. The reference rate was estimated as the average for the 2008-2009 period and the annual and reference rates were compared. RESULTS: The bacteremia reference rate for 2008- 2009 was 10.6/1000 days of CVC to analyze the SIR. A RACHS score over 3 was similar across all studied periods. The annual comparison showed a statistically significant reduction (p < 0.05) in the SIR. The comparison between the baseline bacteremia rate/1000 days of CVC (11.9) and the final rate (3.8) showed a significant reduction (RR: 0.16; 95 % CI: 0.07-0.35; p < 0.001). CONCLUSIONS: The program was effective; the rate of CVC-related bacteremias in the PCICU showed a progressive, significant reduction.

Introducción. Las bacteriemias relacionadas con catéteres venosos centrales (CVC) son frecuentes en pacientes pediátricos posquirúrgicos de cardiopatías congénitas complejas internados en la unidad de cuidados intensivos pediátricos cardiovascular (UCIP-CV) y tienen alta morbimortalidad. OBJETIVO: Analizar la efectividad de un programa interdisciplinario para prevención de bacteriemias relacionadas con CVC en la UCIP-CV. Material y métodos. Estudio de implementación, cuasiexperimental, antes-después, sin grupo control. Período de estudio del 1 de enero de 2008 al 31 de diciembre de 2018. Población: equipo de salud de la UCIP-CV que atiende pacientes posquirúrgicos de cardiopatías complejas de un hospital. Período preintervención del 1 de enero de 2008 al 31 de diciembre de 2008; período de intervención del 1 de enero de 2009 al 1 de enero de 2018. Intervención: implementación de un programa de mejora continua. Se analizaron tasas de bacteriemias CVC/1000 días y de uso de CVC/100 días, puntaje de RACHS, razón estandarizada de infecciones (REI), riesgo relativo (RR), intervalo de confianza del 95 % (IC95%), estimando una p < 0,05 como estadísticamente significativa. La tasa de referencia se estimó como el promedio del período 2008/2009 y se comparó la tasa anual con la tasa de referencia. RESULTADOS: La tasa de referencia de bacteriemia 2008/2009 fue 10,6/1000 días CVC para analizar la REI. El puntaje de RACHS mayor a 3 fue similar en todos los períodos analizados. Se observó una reducción de la REI estadísticamente significativa (p < 0,05) en la comparación anual. Al comparar la tasa de bacteriemia/1000 días de CVC inicial de 11,9 vs. final de 3,8, se observó una reducción significativa (RR: 0,16; IC95%: 0,07-0,35; p < 0,001). CONCLUSIONES: El programa fue efectivo; se observó reducción progresiva y significativa de la tasa de bacteriemias relacionadas con CVC en la UCIP-CV.

Efectividad de un programa de reducción de bacteriemias relacionadas con catéter venoso central en una unidad cardiovascular pediátrica / Effectiveness of a program for the reduction of central venous catheter-related bacteremias in a Pediatric Cardiovascular Unit

Introducción. Las bacteriemias relacionadas con catéteres venosos centrales (CVC) son frecuentes en pacientes pediátricos posquirúrgicos de cardiopatías congénitas complejas internados en la unidad de cuidados intensivos pediátricos cardiovascular (UCIP-CV) y tienen alta morbimortalidad. Objetivo. Analizar la efectividad de un programa interdisciplinario para prevención de bacteriemias relacionadas con CVC en la UCIP-CV. Material y métodos. Estudio de implementación, cuasiexperimental, antes-después, sin grupo control. Período de estudio del 1 de enero de 2008 al 31 de diciembre de 2018. Población: equipo de salud de la UCIP-CV que atiende pacientes posquirúrgicos de cardiopatías complejas de un hospital. Período preintervención del 1 de enero de 2008 al 31 de diciembre de 2008; período de intervención del 1 de enero de 2009 al 1 de enero de 2018. Intervención: implementación de un programa de mejora continua. Se analizaron tasas de bacteriemias CVC/1000 días y de uso de CVC/100 días, puntaje de RACHS, razón estandarizada de infecciones (REI), riesgo relativo (RR), intervalo de confianza del 95 % (IC95%), estimando una p < 0,05 como estadísticamente significativa. La tasa de referencia se estimó como el promedio del período 2008/2009 y se comparó la tasa anual con la tasa de referencia. Resultados. La tasa de referencia de bacteriemia 2008/2009 fue 10,6/1000 días CVC para analizar la REI. El puntaje de RACHS mayor a 3 fue similar en todos los períodos analizados. Se observó una reducción de la REI estadísticamente significativa (p < 0,05) en la comparación anual. Al comparar la tasa de bacteriemia/1000 días de CVC inicial de 11,9 vs. final de 3,8, se observó una reducción significativa (RR: 0,16; IC95%: 0,07-0,35; p < 0,001). Conclusiones. El programa fue efectivo; se observó reducción progresiva y significativa de la tasa de bacteriemias relacionadas con CVC en la UCIP-CV.

Introduction. Central venous catheter (CVC)related bacteremias are common in pediatric patients following surgery for complex congenital heart disease admitted to a pediatric cardiac intensive care unit (PCICU) and have a high morbidity and mortality. Objective.To analyze the effectiveness of an interdisciplinary program for the prevention of CVC-related bacteremias in the PCICU. Material and methods. Quasi-experimental,before and after implementation study without a control group. Study period: 01-01-2008 to 1231-2018. Population: PCICU staff who care for patients following surgery for complex heart disease at a hospital. Pre-intervention period: 0101-2008 to 12-31-2008; intervention period: 01-012009 to 01-01-2018. Intervention: implementation of an ongoing improvement program. The rate of CVC-related bacteremias/1000 days and CVC use/100 days, RACHS score, standardized infection ratio (SIR), relative risk (RR), and 95% confidence interval (CI) were analyzed and a p value < 0.05 was considered statistically significant. The reference rate was estimated as the average for the 2008-2009 period and the annual and reference rates were compared. Results. The bacteremia reference rate for 20082009 was 10.6/1000 days of CVC to analyze the SIR. A RACHS score over 3 was similar across all studied periods. The annual comparison showed a statistically significant reduction (p < 0.05) in the SIR. The comparison between the baseline bacteremia rate/1000 days of CVC (11.9) and the final rate (3.8) showed a significant reduction (RR: 0.16; 95 % CI: 0.07­0.35; p < 0.001). Conclusions. The program was effective; the rate of CVC-related bacteremias in the PCICU showed a progressive, significant reduction.

Violent Radicalization and Post-traumatic Dissociation: Clinical Case of a Young Adolescent Girl Radicalized.

Introduction: Since 2014, the profiles of radicalized individuals have changed with the appearance of radical groups composed of a large proportion of adolescents. Various individual, relational, and social vulnerabilities have been identified as being involved in the radicalization process of adolescents. Among these factors, it appears that early and repeated history of personal and/or family psychotraumatism may constitute factors of vulnerability to violent radicalization. Material and Methods: The clinical situation of a 17-year-old woman convicted of "links with a terrorist group (DAECH)" was recruited from the 130 radicalized young people followed by the teams of the Maison des Adolescents and the Child and Adolescent Psychiatry Service of the University Hospitals of Strasbourg since May 2015. Based on the analysis of this clinical case, we present the hypothesis that post-traumatic antecedents can constitute vulnerability factors to violent radicalization, and that post-traumatic symptoms can be "used" by recruiters of radical movements at different moments of the radicalization process by reactivating post-traumatic psychic mechanisms, but also, for a smaller number of subjects, by the induction of the trauma (viewing of propaganda videos). Results: We show a possible link between violent radicalization and complex psycho-traumatism with an impact of the reactivation of post-traumatic mechanisms such as (i) the activation of the autonomic nervous system and emotional dysregulation on violent acts, (ii) the activation of dissociation mechanisms (psychic sideration and post-traumatic amnesia) on indoctrination and violent acts, (iii) the activation of control mechanisms on the search for a strict framework of life and a radical ideology and (iv) relational avoidance on the processes of relational rupture and radical socialization. Thus, we highlight that the radicalization process can respond to the needs and psychic functioning of psycho-traumatized individuals (channeling tensions, being recognized and active in one's life). Discussion: We discuss the central role of propaganda videos in the activation of the ANS and dissociation, and the self-perpetuating process between these two posttraumatic mechanisms. We also discuss clinical and therapeutic perspectives (therapies targeting complex psychotrauma). Conclusion: Psychotrauma can promote radicalization due to vulnerability mechanisms. Treatments targeting psychotrauma may be one of the ways to get these young people out of violent radicalization.

Advantages of optical fibers for facile and enhanced detection in droplet microfluidics.

Droplet microfluidics offers a unique opportunity for ultrahigh-throughput experimentation with minimal sample consumption and thus has obtained increasing attention, particularly for biological applications. Detection and measurements of analytes or biomarkers in tiny droplets are essential for proper analysis of biological and chemical assays like single-cell studies, cytometry, nucleic acid detection, protein quantification, environmental monitoring, drug discovery, and point-of-care diagnostics. Current detection setups widely use microscopes as a central device and other free-space optical components. However, microscopic setups are bulky, complicated, not flexible, and expensive. Furthermore, they require precise optical alignments, specialized optical and technical knowledge, and cumbersome maintenance. The establishment of efficient, simple, and cheap detection methods is one of the bottlenecks for adopting microfluidic strategies for diverse bioanalytical applications and widespread laboratory use. Together with great advances in optofluidic components, the integration of optical fibers as a light guiding medium into microfluidic chips has recently revolutionized analytical possibilities. Optical fibers embedded in a microfluidic platform provide a simpler, more flexible, lower-cost, and sensitive setup for the detection of several parameters from biological and chemical samples and enable widespread, hands-on application much beyond thriving point-of-care developments. In this review, we examine recent developments in droplet microfluidic systems using optical fiber as a light guiding medium, primarily focusing on different optical detection methods such as fluorescence, absorbance, light scattering, and Raman scattering and the potential applications in biochemistry and biotechnology that are and will be arising from this.

Design, simulation and characterization of integrated photonic spectrographs for astronomy II: low-aberration Generation-II AWG devices with three stigmatic points.

In the second part of our series on integrated photonic spectrographs for astronomy, we present theoretical and experimental results on the design, simulation and characterization of custom-manufactured silica-on-silicon arrayed waveguide gratings (AWGs) constructed using the three-stigmatic-point method. We derive several mid-to-high resolution field-flattened AWG designs, targeting resolving powers of 11,000 - 35,000 in the astronomical H-band, by iterative computation of differential coefficients of the optical path function. We use numerical simulations to study the imaging properties of the designs in a wide wavelength range between 1500 nm and 1680 nm. We theoretically discuss the design-specific degradation of spectral resolving power at far-off-centre wavelengths and suggest possible solutions. In the experimental section, we provide characterization results of seven manufactured AWG devices of varying free spectral range and resolution. We obtain estimates on spectral resolving powers of up to 27,600 for polarized input at 1550 nm from measurements of the channel transmission bandwidth. Furthermore, we numerically predict expected resolving powers of up to 36,000 in the polarized mode and up to 24,000 in the unpolarized mode for direct continuous imaging of the spectrum.

Design, simulation and characterization of integrated photonic spectrographs for astronomy: generation-I AWG devices based on canonical layouts.

We present an experimental study on our first generation of custom-developed arrayed waveguide gratings (AWG) on a silica platform for spectroscopic applications in near-infrared astronomy. We provide a comprehensive description of the design, numerical simulation and characterization of several AWG devices aimed at spectral resolving powers of 15,000-60,000 in the astronomical H-band. We evaluate the spectral characteristics of the fabricated devices in terms of insertion loss and estimated spectral resolving power and compare the results with numerical simulations. We estimate resolving powers of up to 18,900 from the output channel 3-dB transmission bandwidth. Based on the first characterization results, we select two candidate AWGs for further processing by removal of the output waveguide array and polishing the output facet to optical quality with the goal of integration as the primary diffractive element in a cross-dispersed spectrograph. We further study the imaging properties of the processed AWGs with regards to spectral resolution in direct imaging mode, geometry-related defocus aberration, and polarization sensitivity of the spectral image. We identify phase error control, birefringence control, and aberration suppression as the three key areas of future research and development in the field of high-resolution AWG-based spectroscopy in astronomy.

Simulations of mode-selective photonic lanterns for efficient coupling of starlight into the single-mode regime.

In ground-based astronomy, starlight distorted by the atmosphere couples poorly into single-mode waveguides, but a correction by adaptive optics, even if only partial, can boost coupling into the few-mode regime, allowing the use of photonic lanterns to convert into multiple single-mode beams. Corrected wavefronts result in focal patterns that couple mostly with circularly symmetric waveguide modes. A mode-selective photonic lantern is hence proposed to convert multimode light into a subset of single-mode waveguides of the standard photonic lantern, thereby reducing the required number of outputs. We ran simulations to show that only two out of the six waveguides of a 1×6 photonic lantern carry >95% of the coupled light to the outputs at D/r0<10 if the wavefront is partially corrected and the photonic lantern is made mode selective.

Seeking celestial positronium with an OH-suppressed diffraction-limited spectrograph.

Celestially, positronium (Ps) has been observed only through gamma-ray emission produced by its annihilation. However, in its triplet state, a Ps atom has a mean lifetime long enough for electronic transitions to occur between quantum states. This produces a recombination spectrum observable in principle at near IR wavelengths, where angular resolution greatly exceeding that of the gamma-ray observations is possible. However, the background in the near IR is dominated by extremely bright atmospheric hydroxyl (OH) emission lines. In this paper, we present the design of a diffraction-limited spectroscopic system using novel photonic components-a photonic lantern, OH fiber Bragg grating filters, and a photonic TIGER 2D pseudo-slit-to observe the Ps Balmer alpha line at 1.3122 µm for the first time, to our knowledge.

First stellar photons for an integrated optics discrete beam combiner at the William Herschel Telescope.

We present the first on-sky results of a four-telescope integrated optics discrete beam combiner (DBC) tested at the 4.2 m William Herschel Telescope. The device consists of a four-input pupil remapper followed by a DBC and a 23-output reformatter. The whole device was written monolithically in a single alumino-borosilicate substrate using ultrafast laser inscription. The device was operated at astronomical H-band (1.6 µm), and a deformable mirror along with a microlens array was used to inject stellar photons into the device. We report the measured visibility amplitudes and closure phases obtained on Vega and Altair that are retrieved using the calibrated transfer matrix of the device. While the coherence function can be reconstructed, the on-sky results show significant dispersion from the expected values. Based on the analysis of comparable simulations, we find that such dispersion is largely caused by the limited signal-to-noise ratio of our observations. This constitutes a first step toward an improved validation of the DBC as a possible beam combination scheme for long-baseline interferometry.

Highly parallelized droplet cultivation and prioritization of antibiotic producers from natural microbial communities.

Antibiotics from few culturable microorganisms have saved millions of lives since the 20th century. But with resistance formation, these compounds become increasingly ineffective, while the majority of microbial and with that chemical compound diversity remains inaccessible for cultivation and exploration. Culturing recalcitrant bacteria is a stochastic process. But conventional methods are limited to low throughput. By increasing (i) throughput and (ii) sensitivity by miniaturization, we innovate microbiological cultivation to comply with biological stochasticity. Here, we introduce a droplet-based microscale cultivation system, which is directly coupled to a high-throughput screening for antimicrobial activity prior to strain isolation. We demonstrate that highly parallelized in-droplet cultivation starting from single cells results in the cultivation of yet uncultured species and a significantly higher bacterial diversity than standard agar plate cultivation. Strains able to inhibit intact reporter strains were isolated from the system. A variety of antimicrobial compounds were detected for a selected potent antibiotic producer.

Antibiotics are chemicals derived from microorganisms that can kill the bacteria that harm human health. In the 20^th and 21^st centuries antibiotics saved millions of lives, but new strains of dangerous bacteria that cannot be killed by antibiotics, known as antibiotic resistant strains, are becoming more frequent. Most antibiotics are produced by only a small group of microorganisms, but many more microorganisms exist in nature. So it is possible that microorganisms outside this small group can produce different antibiotics that are effective against antibiotic resistant strains. Unfortunately, finding the microorganisms that produce these alternative antibiotics is challenging because researchers do not know which bacteria are producing these molecules and how to grow these microorganisms in the laboratory. To solve this problem, Mahler et al. developed a new method for growing a new subset of microorganisms in the laboratory. This would allow researchers to study the new microorganisms under controlled conditions, and determine whether any of the substances they produce have antibiotic properties. Mahler et al. generated tiny droplets that could only contain a single cell of a microorganism, so each microbe could grow alone in its own protected environment. Using this approach, it was possible to grow completely different types of microorganisms than with traditional techniques, and keep them isolated from each other. This allowed each different species of microbe to be screened for antimicrobial activity, allowing the identification of chemicals that could potentially be developed into new antibiotics. This new method is automated and miniaturized, paving the way for growing many more cells in few hours, with very low material and space requirements. These results showcase a way of growing new types of microorganisms in the laboratory, making it easier and faster to study them and determine what chemicals they produce. Understanding a greater variety of microorganisms in detail can help identify new chemicals for industrial applications, including new ways of combating infections.

N-Heterocyclization in Gliotoxin Biosynthesis is Catalyzed by a Distinct Cytochrome P450 Monooxygenase.

Gliotoxin and related epidithiodiketopiperazines (ETP) from diverse fungi feature highly functionalized hydroindole scaffolds with an array of medicinally and ecologically relevant activities. Mutation analysis, heterologous reconstitution, and biotransformation experiments revealed that a cytochrome P450 monooxygenase (GliF) from the human-pathogenic fungus Aspergillus fumigatus plays a key role in the formation of the complex heterocycle. In vitro assays using a biosynthetic precursor from a blocked mutant showed that GliF is specific to ETPs and catalyzes an unprecedented heterocyclization reaction that cannot be emulated with current synthetic methods. In silico analyses indicate that this rare biotransformation takes place in related ETP biosynthetic pathways.

Performance limits of astronomical arrayed waveguide gratings on a silica platform.

We present a numerical and experimental study of the impact of phase errors on the performance of large, high-resolution arrayed waveguide gratings (AWG) for applications in astronomy. We use a scalar diffraction model to study the transmission spectrum of an AWG under random variations of the optical waveguide lengths. We simulate phase error correction by numerically trimming the lengths of the optical waveguides to the nearest integer multiple of the central wavelength. The optical length error distribution of a custom-fabricated silica AWG is measured using frequency-domain interferometry and Monte-Carlo fitting of interferogram intensities. In the end, we give an estimate for the phase-error limited size of a waveguide array manufactured using state-of-the-art technology. We show that post-processing eliminates phase errors as a performance limiting factor for astronomical spectroscopy in the H-band.

Wide Field Spectral Imaging with Shifted Excitation Raman Difference Spectroscopy Using the Nod and Shuffle Technique.

Wide field Raman imaging using the integral field spectroscopy approach was used as a fast, one shot imaging method for the simultaneous collection of all spectra composing a Raman image. For the suppression of autofluorescence and background signals such as room light, shifted excitation Raman difference spectroscopy (SERDS) was applied to remove background artifacts in Raman spectra. To reduce acquisition times in wide field SERDS imaging, we adapted the nod and shuffle technique from astrophysics and implemented it into a wide field SERDS imaging setup. In our adapted version, the nod corresponds to the change in excitation wavelength, whereas the shuffle corresponds to the shifting of charges up and down on a Charge-Coupled Device (CCD) chip synchronous to the change in excitation wavelength. We coupled this improved wide field SERDS imaging setup to diode lasers with 784.4/785.5 and 457.7/458.9 nm excitation and applied it to samples such as paracetamol and aspirin tablets, polystyrene and polymethyl methacrylate beads, as well as pork meat using multiple accumulations with acquisition times in the range of 50 to 200 ms. The results tackle two main challenges of SERDS imaging: gradual photobleaching changes the autofluorescence background, and multiple readouts of CCD detector prolong the acquisition time.

Chromatic response of a four-telescope integrated-optics discrete beam combiner at the astronomical L band.

We show the results of simulation and experimental study of a 4-telescope zig-zag discrete beam combiner (DBC) for long-baseline stellar interferometry working at the astronomical L band (3 - 4 µm) under the influence of a narrow bandwidth light source. Following Saviauk et al. (2013), we used a quasi-monochromatic visibility-to-pixel matrix (V2PM) for retrieving the complex coherence functions from simulated and experimentally measured power at the output of the device. Simulation and coefficient of determination (R2) measurements show that we are able to retrieve the visibility amplitudes with >95 % accuracy of our chromatic model source up to a bandwidth of 100 nm centred at 3.5 µm. We characterized a DBC manufactured by 3D ultra-fast laser inscription (ULI) written on gallium lanthanum sulphate (GLS). Experimental results showed retrieval of visibility amplitude with an accuracy of 80-90 % at 69 nm bandwidth, validating our simulation. The standard deviation of experimental phase residuals are between 0.1-0.4 rad, which shows that the retrieval procedure is sufficient to get good quality images, where phase perturbations of less than 1 rad are expected under good seeing conditions for astronomical applications.

Complex phase masks for OH suppression filters in astronomy: part I: design.

The design of a complex phase mask (CPM) for inscribing multi-notch fiber Bragg grating filters in optical fibers for OH suppression in astronomy is presented. We demonstrate the steps involved in the design of a complex mask with discrete phase steps, following a detailed analysis of fabrication constraints. The phase and amplitude of the complex grating is derived through inverse modelling from the desired aperiodic filter spectrum, following which the phase alone is encoded into the surface relief of a CPM. Compared to a complicated "running-light" Talbot interferometer based inscription setup where the phase of the inscribing beam is controlled by electro- or acousto-optic modulators and synchronized to a moving fiber translation stage, CPM offers the well-known convenience and reproducibility of the standard phase mask inscription technique. We have fabricated a CPM that can suppress 37 sky emission lines between 1508 nm to 1593 nm, with a potential of increasing to 99 channels for suppressing near-infrared (NIR) OH-emission lines generated in the upper atmosphere and improving the performance of ground-based astronomical telescopes.

Quantifying the relationship between surfaces' nano-contact point density and adhesion force of Candida albicans.

It has been recently recognized that controlled surface structuring on the nanometer scale is a successful strategy to endow different materials with antimicrobial properties. Despite many studies on bacterial interactions with nanostructured surfaces, a quantitative link between surface topography and bacterial adhesion is still missing. To quantitatively link cell adhesion data with topographical surface parameters, we performed single-cell spectroscopy on chemically identical surfaces with controlled nano-contact point density achieved by immobilization of gold nanoparticles (AuNP) on gold thin films. Such materials surfaces have previously shown antimicrobial (anti-adhesive) efficacy towards Gram-negative Escherichia coli cells. In the current study, the influence of nano-structured surfaces on the surface coverage and adhesion forces of clinically relevant Candida albicans (C. albicans), the fungus primarily associated with implant infections, was investigated to validate their antimicrobial potency against different microbial cells. The adhesion forces of C. albicans cells to nanostructured surfaces showed a decreasing trend with decreasing contact-point density and correlated well with the results of the respective C. albicans cell counts. The surfaces with the lowest contact-point density, 25 AuNP/µm², resulted in an average adhesion force of 5 nN, which was up to 5 times lower compared to control and 61 AuNP/µm² surfaces. Further, detailed analyses of force-distance curves revealed that the work of adhesion, and thus the energy required to remove the C. albicans cell from the surface is up to 10 times lower on 25 AuNP/µm² surfaces compared to unstructured surfaces. These findings show that a controlled tuning of nanostructured surfaces in terms of accessible nano-contact points is crucial to generate surface structures with enhanced antimicrobial properties. The gained knowledge can be further exploited for the design of biomaterials surfaces to prevent adhesion of some most commonly encountered pathogens.