Multi-parameter estimation of high-Q silicon rich nitride resonators using optical frequency domain reflectometry

Many linear and nonlinear optics applications rely on micro-resonators (MRRs) with carefully designed dispersion and coupling rate coefficients. These parameters are however challenging to measure for MRRs based on high-confinement optical waveguides. In this paper, we report on the use of optical frequency domain reflectometry (OFDR) for the measurement of group velocity dispersion (GVD), coupling coefficients and round-Trip loss, in high-Q (Q i ∼ 0.3 7 10 6 ) silicon-rich nitride MRRs. This technique allows for retrieving the GVD coefficients, intrinsic losses and coupling coefficients for each transverse mode in the resonator, thus providing very valuable feed-back information from experiments to the design flow step

Si3N4 photonic integration platform at 1 \ub5m for optical interconnects

Vertical-cavity surface-emitting lasers (VCSELs) are the predominant technology for high-speed short-range interconnects in data centers. Most short-range interconnects rely on GaAs-based multi-mode VCSELs and multi-mode fiber links operating at 850 nm. Recently, GaAs-based high-speed single-mode VCSELs at wavelengths > 1 \ub5m have been demonstrated, which increases the interconnect reach using a single-mode fiber while maintaining low energy dissipation. If a suitable platform for passive wavelength- and space-multiplexing were developed in this wavelength range, this single-mode technology could deliver the multi-Tb/s interconnect capacity that will be required in future data centers. In this work, we show the first passive Si3N4 platform in the 1-\ub5m band (1030-1075 nm) with an equivalent loss < 0.3 dB/cm, which is compatible with the system requirements of high-capacity interconnects. The waveguide structure is optimized to achieve simultaneously single-mode operation and low bending radius, and we demonstrate a wide range of high-performance building blocks, including arrayed waveguide gratings, Mach-Zehnder interferometers, splitters and low-loss fiber interfaces. This technology could be instrumental in scaling up the capacity and reducing the footprint of VCSEL-based optical interconnects and, thanks to the broad transparency in the near-infrared and compatibility with the Yb fiber amplifier window, enabling new applications in other domains as optical microscopy and nonlinear optics

Mortality and pulmonary complications in patients undergoing surgery with perioperative SARS-CoV-2 infection: an international cohort study

Background: The impact of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) on postoperative recovery needs to be understood to inform clinical decision making during and after the COVID-19 pandemic. This study reports 30-day mortality and pulmonary complication rates in patients with perioperative SARS-CoV-2 infection. Methods: This international, multicentre, cohort study at 235 hospitals in 24 countries included all patients undergoing surgery who had SARS-CoV-2 infection confirmed within 7 days before or 30 days after surgery. The primary outcome measure was 30-day postoperative mortality and was assessed in all enrolled patients. The main secondary outcome measure was pulmonary complications, defined as pneumonia, acute respiratory distress syndrome, or unexpected postoperative ventilation. Findings: This analysis includes 1128 patients who had surgery between Jan 1 and March 31, 2020, of whom 835 (74·0%) had emergency surgery and 280 (24·8%) had elective surgery. SARS-CoV-2 infection was confirmed preoperatively in 294 (26·1%) patients. 30-day mortality was 23·8% (268 of 1128). Pulmonary complications occurred in 577 (51·2%) of 1128 patients; 30-day mortality in these patients was 38·0% (219 of 577), accounting for 81·7% (219 of 268) of all deaths. In adjusted analyses, 30-day mortality was associated with male sex (odds ratio 1·75 [95% CI 1·28–2·40], p\textless0·0001), age 70 years or older versus younger than 70 years (2·30 [1·65–3·22], p\textless0·0001), American Society of Anesthesiologists grades 3–5 versus grades 1–2 (2·35 [1·57–3·53], p\textless0·0001), malignant versus benign or obstetric diagnosis (1·55 [1·01–2·39], p=0·046), emergency versus elective surgery (1·67 [1·06–2·63], p=0·026), and major versus minor surgery (1·52 [1·01–2·31], p=0·047). Interpretation: Postoperative pulmonary complications occur in half of patients with perioperative SARS-CoV-2 infection and are associated with high mortality. Thresholds for surgery during the COVID-19 pandemic should be higher than during normal practice, particularly in men aged 70 years and older. Consideration should be given for postponing non-urgent procedures and promoting non-operative treatment to delay or avoid the need for surgery. Funding: National Institute for Health Research (NIHR), Association of Coloproctology of Great Britain and Ireland, Bowel and Cancer Research, Bowel Disease Research Foundation, Association of Upper Gastrointestinal Surgeons, British Association of Surgical Oncology, British Gynaecological Cancer Society, European Society of Coloproctology, NIHR Academy, Sarcoma UK, Vascular Society for Great Britain and Ireland, and Yorkshire Cancer Research

Compact 8-channel Loop-back AWG based Integrated Comb Processor

We present an 8-channel integrated comb source spectral processor based on an arrayed-waveguide grating with unconventional mounting, for improved aberration and sidelobes, in loop-back configuration. The spectral processor is fabricated in a silicon nitride platform and has a 100 GHz channel spacing

Passive Si3N4 photonic integrated platform at 1μm for short-range optical interconnects

With the increasing development of cloud services, a large number of high-speed optical interconnects are needed in large-scale datacenters. Future datacenters will require short-range links with multi-Tb/s interconnect capacity, i.e. more than an order of magnitude higher than what is available today with vertical-cavity surface-emission lasers (VCSELs) or silicon photonics. In addition, large-scale datacenters will require longer (> 1km) transmission links. Single-mode GaAs VCSELs today provide transmission speeds ∼ 100 Gb/s, close to their fundamental limit. The recent development of high-speed GaAs VCSELs at a slightly longer wavelength of opens a path forward for low-energy dissipation, high-speed, long-reach optical interconnects because the chromatic dispersion and attenuation in fibers are significantly reduced compared to shorter wavelengths [1]. In order to meet the future capacity prospects, we envision the use of multi-wavelength GaAs VCSEL arrays at 1 μm with advanced multi-fiber cables. This vision requires the use of a low-cost, low-loss passive integrated photonic platform for laser integration, multiplexing, and fiber interfacing, as sketched in Figure (a). Here, we present a silicon nitride (henceforth SiN) platform that can meet these requirements

Independent validation of the PAM50-based Chemo-Endocrine Score in hormonal receptor positive HER2-positive breast cancer treated with neoadjuvant therapy

BACKGROUND: We do not yet have validated biomarkers to predict response and outcome within hormone receptor-positive/HER2-positive (HR+/HER2+) breast cancer (BC). The PAM50-based chemo-endocrine score (CES) predicts chemo-endocrine sensitivity in HR+/HER2-negative BC. Here, we evaluate the relationship of CES with response and survival in HR+/HER2+ BC.METHODS: Intrinsic subtype and clinicopathological data were obtained from 7 studies in which patients were treated with HER2-targeted therapy either with endocrine therapy (ET) or with chemotherapy (CTX). CES was evaluated as a continuous variable and categorically from low to high scores (CES-C [chemo-sensitive], CES-U [uncertain] and CES-E [endocrine-sensitive]. We first analyzed each dataset individually, and then all combined. Multivariable analyses were used to test CES association with pathologic complete response (pCR) and disease-free survival (DFS).RESULTS: 457 patients were included (112 with ET and 345 with CTX). In the combined cohort, CES-C, CES-U and CES-E were identified in 60%, 23% and 17% of the patients, respectively. High CES (i.e. CES-E) was associated with a lower probability of achieving pCR independently of clinical characteristics, therapy, intrinsic subtype, and study (adjusted odd ratio=0.42; p=0.016). 295 patients were analyzed for DFS with a median follow-up of 66 months. High CES was also associated with better DFS (adjusted hazard ratio=0.174, p=0.003) independently of pCR, clinical characteristics and intrinsic subtype. In patients with residual disease, the adjusted DFS hazard ratio of CES was 0.160 (p=0.012).CONCLUSIONS: In HER2+/HR+ BC, CES is useful for predicting chemo-endocrine sensitivity and provides additional prognostication beyond intrinsic subtype and clinicopathologic characteristics

Cytomegalovirus infection management in solid organ transplant recipients across European centers in the time of molecular diagnostics: An ESGICH survey

Background: Scant information is available about how transplant centers are managing their use of quantitative molecular testing (QNAT) assays for active cytomegalovirus (CMV) infection monitoring in solid organ transplant (SOT) recipients. The current study was aimed at gathering information on current practices in the management of CMV infection across European centers in the era of molecular testing assays. Methods: A questionnaire-based cross-sectional survey study was conducted by the European Study Group of Infections in Immunocompromised Hosts (ESGICH) of the Society of Clinical Microbiology and Infectious Diseases (ESCMID). The invitation and a weekly reminder with a personal link to an Internet service provider (https://es.surveymonkey.com/) was sent to transplant physicians, transplant infectious diseases specialists, and clinical virologists working at 340 European transplant centers. Results: Of the 1181 specialists surveyed, a total of 173 responded (14.8%): 73 transplant physicians, 57 transplant infectious diseases specialists, and 43 virologists from 173 institutions located at 23 different countries. The majority of centers used QNAT assays for active CMV infection monitoring. Most centers preferred commercially available real-time polymerase chain reaction (RT-PCR) assays over laboratory-developed procedures for quantifying CMV DNA load in whole blood or plasma. Use of a wide variety of DNA extraction platforms and RT-PCR assays was reported. All programs used antiviral prophylaxis, preemptive therapy, or both, according to current guidelines. However, the centers used different criteria for starting preemptive antiviral treatment, for monitoring systemic CMV DNA load, and for requesting genotypic assays to detect emerging CMV-resistant variants. Conclusions: Significant variation in CMV infection management in SOT recipients still remains across European centers in the era of molecular testing. International multicenter studies are required to achieve commutability of CMV testing and antiviral management procedures

Risk factors for unfavourable postoperative outcome in patients with Crohn's disease undergoing right hemicolectomy or ileocaecal resection. An international audit by ESCP and S-ECCO

Aim: Patient- and disease-related factors, as well as operation technique, all have the potential to impact on postoperative outcome in Crohn's disease. The available evidence is based on small series and often displays conflicting results. The aim was to investigate the effect of preoperative and intra-operative risk factors on 30-day postoperative outcome in patients undergoing surgery for Crohn's disease. Method: This was an international prospective snapshot audit including consecutive patients undergoing right hemicolectomy or ileocaecal resection. The study analysed a subset of patients who underwent surgery for Crohn's disease. The primary outcome measure was the overall Clavien\u2013Dindo postoperative complication rate. The key secondary outcomes were anastomotic leak, reoperation, surgical site infection and length of stay in hospital. Multivariable binary logistic regression analyses were used to produce odds ratios and 95% confidence intervals. Results: In all, 375 resections in 375 patients were included. The median age was 37 and 57.1% were women. In multivariate analyses, postoperative complications were associated with preoperative parenteral nutrition (OR 2.36, 95% CI 1.10\u20134.97), urgent/expedited surgical intervention (OR 2.00, 95% CI 1.13\u20133.55) and unplanned intra-operative adverse events (OR 2.30, 95% CI 1.20\u20134.45). The postoperative length of stay in hospital was prolonged in patients who received preoperative parenteral nutrition (OR 31, 95% CI 1.08\u20131.61) and those who had urgent/expedited operations (OR 1.21, 95% CI 1.07\u20131.37). Conclusion: Preoperative parenteral nutritional support, urgent/expedited operation and unplanned intra-operative adverse events were associated with unfavourable postoperative outcome. Enhanced preoperative optimization and improved planning of operation pathways and timings may improve outcomes for patients

Evaluating the incidence of pathological complete response in current international rectal cancer practice: the barriers to widespread safe deferral of surgery

This is the peer reviewed version of the following article: , which has been published in final form at https://doi.org/10.1111/codi.14361. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions."Colorectal Disease © 2018 The Association of Coloproctology of Great Britain and Ireland Introduction: The mainstay of management for locally advanced rectal cancer is chemoradiotherapy followed by surgical resection. Following chemoradiotherapy, a complete response may be detected clinically and radiologically (cCR) prior to surgery or pathologically after surgery (pCR). We aim to report the overall complete pathological response (pCR) rate and the reliability of detecting a cCR by conventional pre-operative imaging. Methods: A pre-planned analysis of the European Society of Coloproctology (ESCP) 2017 audit was performed. Patients treated by elective rectal resection were included. A pCR was defined as a ypT0 N0 EMVI negative primary tumour; a partial response represented any regression from baseline staging following chemoradiotherapy. The primary endpoint was the pCR rate. The secondary endpoint was agreement between post-treatment MRI restaging (yMRI) and final pathological staging. Results: Of 2572 patients undergoing rectal cancer surgery in 277 participating centres across 44 countries, 673 (26.2%) underwent chemoradiotherapy and surgery. The pCR rate was 10.3% (67/649), with a partial response in 35.9% (233/649) patients. Comparison of AJCC stage determined by post-treatment yMRI with final pathology showed understaging in 13% (55/429) and overstaging in 34% (148/429). Agreement between yMRI and final pathology for T-stage, N-stage, or AJCC status were each graded as ‘fair’ only (n = 429, Kappa 0.25, 0.26 and 0.35 respectively). Conclusion: The reported pCR rate of 10% highlights the potential for non-operative management in selected cases. The limited strength of agreement between basic conventional post-chemoradiotherapy imaging assessment techniques and pathology suggest alternative markers of response should be considered, in the context of controlled clinical trials