Dynamic Range Extension of a SPAD Imager Using Non-Uniformity Correction Techniques

The extraordinary sensitivity of single-photon avalanche diodes (SPADs) makes these devices the ideal option for vision systems aimed at low-light applications. Nevertheless, there exist large dark count rate and photon detection probability non-uniformities, which reduce the dynamic range of the detector. As a result, the capability to create image contrast is severely damaged or even lost. This paper presents the implementation of a correction algorithm to compensate for the mentioned non-uniformities and thus extend the contrast of the generated images. To demonstrate its efficiency, the proposed technique is applied to real images obtained with a fabricated SPAD image sensor. An increase of more than 3 b of contrast is obtained.Peer ReviewedPostprint (author's final draft

Strategies for using GAPDs as tracker detectors in future linear colliders

AbstractThis work presents the development of a Geiger-mode Avalanche PhotoDiode pixel detector in standard CMOS technologies aimed at the vertex and tracker regions of future linear colliders, i.e. the International Linear Collider and the Compact LInear Collider. In spite of all the advantages that characterize this technology, GAPD detectors suffer from noise pulses that cannot be distinguished from real events and low fill-factors that reduce the detection efficiency. To comply with the specifications imposed by the next generation of particle colliders, solutions to minimize the intrinsic noise pulses and increase the fill-factor have been thoroughly investigated

A new 130nm F.E readout chip for microstrip detectors

In the context of the Silicon tracking for a Linear Collider (SiLC) R&D collaboration, a highly compact mixed-signal chip has been designed in 130nm CMOS technology intended to read Silicon strip detectors for the experiments at the future International Linear Collider. The chip includes eighty eight channels of a full analog signal processing chain and analog to digital conversion with the corresponding digital controls and readout channels. The chip is 5x10mm2 where the analog implementation represents 4/5 of the total Silicon area.Comment: 3 pages, 4 figures, LCWS08 worksho

Geiger-Mode Avalanche Photodiodes in Standard CMOS Technologies

Photodiodes are the simplest but most versatile semiconductor optoelectronic devices. They can be used for direct detection of light, of soft X and gamma rays, and of particles such as electrons or neutrons. For many years, the sensors of choice for most research and industrial applications needing photon counting or timing have been vacuum-based devices such as Photo-Multiplier Tubes, PMT, and Micro-Channel Plates, MCP (Renker, 2004). Although these photodetectors provide good sensitivity, noise and timing characteristics, they still suffer from limitations owing to their large power consumption, high operation voltages and sensitivity to magnetic fields, as well as they are still bulky, fragile and expensive. New approaches to high-sensitivity imagers tend to use CCD cameras coupled with either MCP Image Intensifiers, I-CCDs, or Electron Multipliers, EM-CCDs (Dussault & Hoess, 2004), but they still have limited performances in extreme time-resolved measurements. A fully solid-state solution can improve design flexibility, cost, miniaturization, integration density, reliability and signal processing capabilities in photodetectors. In particular, Single- Photon Avalanche Diodes, SPADs, fabricated by conventional planar technology on silicon can be used as particle (Stapels et al., 2007) and photon (Ghioni et al., 2007) detectors with high intrinsic gain and speed. These SPAD are silicon Avalanche PhotoDiodes biased above breakdown. This operation regime, known as Geiger mode, gives excellent single-photon sensitivity thanks to the avalanche caused by impact ionization of the photogenerated carriers (Cova et al., 1996). The number of carriers generated as a result of the absorption of a single photon determines the optical gain of the device, which in the case of SPADs may be virtually infinite. The basic concepts concerning the behaviour of G-APDs and the physical processes taking place during their operation will be reviewed next, as well as the main performance parameters and noise sources

A Portable Fluorescence Lifetime Spectroscopy Detector for Molecular Diagnosis

Fluorescence-based techniques are amongst the most widely used methods in molecular analysis in life science with multiple applications in clinical analysis and biomedical diagnosis. Considerable efforts have been directed toward the miniaturization of the fluorescence-based instruments, in an effort to reduce both cost and form factor for point of care (PoC) applications, but at the expense of increasing the complexity of the system or losing sensitivity. A new technology is being developed to build a PoC device based on fluorescence lifetime detection for molecular diagnosis with a sensitivity comparable to the bulky optical instruments and with a diagnosis time of a few seconds. Our PoC is a low-cost, simple, fast and easy to use general purpose platform, aimed at carrying out a fast diagnostics test through label detection of a variety of biomarkers. The system is designed to eliminate the optical requirements associated with traditional fluorescence lifetime instruments. With an array of ultra-sensitive detectors based on CMOS SAPD (single photo avalanche diode) technology along a custom microfluidic polydimethyl-siloxane (PDMS) cartridge on top of the sensor to insert the sample. The proximity of the sample and the SPAD sensor conjointly with the gate mode operation of the sensors, makes the use of lenses and optical filters unnecessary. The device is operated in Time Correlated Single Photon Counting (TCSPC), measuring the time of arrival of the photons after excitation of the fluorescence with a nanosecond laser diode. The sensor, which is extremely sensitive to light in the rage from 400 to 1000 nm, and of ultra-high speed, works in gated mode, which makes it practically unaffected by the intrinsic noise. The system has been characterized with several concentrations of fluorescent quantum dots (Qdot®605 streptavidin conjugate from Life Technologies) as proof-of-concept for lifetimes of several nanoseconds. The lifetime of the quantum dots is 35 ns, and is measured in only 15 seconds

Maternal serum angiopoietin-like 3 levels in healthy and mild preeclamptic pregnant women

Objective: Angiopoietin-like protein 3(ANGPTL3) is an important regulator of lipoprotein metabolism in the fed state by inhibiting the enzyme lipoprotein lipase in oxidative tissues. However, the possible role of ANGPTL3 throughout gestation and its relationship with hormonal and biochemical variables are still unknown. The aim of this study was to determinate serum ANGPTL3 level in healthy non-pregnant women, during healthy and preeclamptic pregnancy and postpartum. Methods: Serum ANGPTL3 was analyzed by enzyme-linked immunosorbent assay (ELISA), in a prospective cohort of healthy pregnant women (n = 52) and women with mild preeclampsia (n = 21), and women at three months postpartum (n = 20) and healthy non-pregnant women (n = 20). The results obtained were correlated with biochemical, hormonal and anthropometric variables and insulin resistance indices. Results: Levels of ANGPTL3 were not different between the follicular and the luteal phases of the cycle in healthy non-pregnant women. There was a significant reduction in serum ANGPTL3 levels from the first to the third trimester in healthy pregnant women compared with healthy non-pregnant and postpartum women (p 0.05) Conclusions: We describe for the first time the profile of ANGPTL3 throughout pregnancy and postpartum as well as and discussed about explore their potential contribution interactions with lipoprotein metabolism throughout pregnancy and postpartum. Thus, low levels of ANGPTL3 during pregnancy might favor lipid uptake in oxidative tissues as the main maternal energy source, while may helping to preserve glucose for use by the fetus and placenta.Fil: Garces, María Fernanda. Universidad Nacional de Colombia; ColombiaFil: Rodriguez Navarro, Haiver Antonio. Universidad Nacional de Colombia; ColombiaFil: Buell Acosta, Julieth Daniela. Universidad Nacional de Colombia; ColombiaFil: Burgos Cardenas, Alvaro Javier. Universidad Nacional de Colombia; ColombiaFil: Franco Vega, Roberto. Universidad Nacional de Colombia; ColombiaFil: Maldonado Acosta, Luis Miguel. Universidad Nacional de Colombia; ColombiaFil: Eslava Schmalbach, Javier. Universidad Nacional de Colombia; ColombiaFil: Parada Baños, Arturo José. Universidad Nacional de Colombia; ColombiaFil: Castro Pinzon, Andres. Universidad Nacional de Colombia; ColombiaFil: Sanchez, Elizabeth. Universidad Nacional de Colombia; ColombiaFil: Angel Muller, Edith. Universidad Nacional de Colombia; ColombiaFil: Lacunza, Ezequiel. Universidad Nacional de La Plata. Facultad de Ciencias Médicas. Centro de Investigaciones Inmunológicas Básicas y Aplicadas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; ArgentinaFil: Castaño, Justo P.. Universidad de Córdoba; EspañaFil: Dieguez, Carlos. Universidad de Santiago de Compostela; EspañaFil: Nogueiras, Rubén. Universidad de Santiago de Compostela; EspañaFil: Ruiz Parra, Ariel Ivan. Universidad Nacional de Colombia; ColombiaFil: Caminos, Jorge Eduardo. Universidad Nacional de Colombia; Colombi

Status of the BELLE II Pixel Detector

The Belle II experiment at the super KEK B-factory (SuperKEKB) in Tsukuba, Japan, has been collecting $e^+e^−$ collision data since March 2019. Operating at a record-breaking luminosity of up to $4.7×10^{34} cm^{−2}s^{−1}$, data corresponding to $424 fb^{−1}$ has since been recorded. The Belle II VerteX Detector (VXD) is central to the Belle II detector and its physics program and plays a crucial role in reconstructing precise primary and decay vertices. It consists of the outer 4-layer Silicon Vertex Detector (SVD) using double sided silicon strips and the inner two-layer PiXel Detector (PXD) based on the Depleted P-channel Field Effect Transistor (DePFET) technology. The PXD DePFET structure combines signal generation and amplification within pixels with a minimum pitch of $(50×55) μm^2$. A high gain and a high signal-to-noise ratio allow thinning the pixels to $75 μm$ while retaining a high pixel hit efficiency of about $99$. As a consequence, also the material budget of the full detector is kept low at $≈0.21$$\frac{X}{X_0}$ per layer in the acceptance region. This also includes contributions from the control, Analog-to-Digital Converter (ADC), and data processing Application Specific Integrated Circuits (ASICs) as well as from cooling and support structures. This article will present the experience gained from four years of operating PXD; the first full scale detector employing the DePFET technology in High Energy Physics. Overall, the PXD has met the expectations. Operating in the intense SuperKEKB environment poses many challenges that will also be discussed. The current PXD system remains incomplete with only 20 out of 40 modules having been installed. A full replacement has been constructed and is currently in its final testing stage before it will be installed into Belle II during the ongoing long shutdown that will last throughout 2023

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

Effects of hospital facilities on patient outcomes after cancer surgery: an international, prospective, observational study

Background Early death after cancer surgery is higher in low-income and middle-income countries (LMICs) compared with in high-income countries, yet the impact of facility characteristics on early postoperative outcomes is unknown. The aim of this study was to examine the association between hospital infrastructure, resource availability, and processes on early outcomes after cancer surgery worldwide.Methods A multimethods analysis was performed as part of the GlobalSurg 3 study-a multicentre, international, prospective cohort study of patients who had surgery for breast, colorectal, or gastric cancer. The primary outcomes were 30-day mortality and 30-day major complication rates. Potentially beneficial hospital facilities were identified by variable selection to select those associated with 30-day mortality. Adjusted outcomes were determined using generalised estimating equations to account for patient characteristics and country-income group, with population stratification by hospital.Findings Between April 1, 2018, and April 23, 2019, facility-level data were collected for 9685 patients across 238 hospitals in 66 countries (91 hospitals in 20 high-income countries; 57 hospitals in 19 upper-middle-income countries; and 90 hospitals in 27 low-income to lower-middle-income countries). The availability of five hospital facilities was inversely associated with mortality: ultrasound, CT scanner, critical care unit, opioid analgesia, and oncologist. After adjustment for case-mix and country income group, hospitals with three or fewer of these facilities (62 hospitals, 1294 patients) had higher mortality compared with those with four or five (adjusted odds ratio [OR] 3.85 [95% CI 2.58-5.75]; p<0.0001), with excess mortality predominantly explained by a limited capacity to rescue following the development of major complications (63.0% vs 82.7%; OR 0.35 [0.23-0.53]; p<0.0001). Across LMICs, improvements in hospital facilities would prevent one to three deaths for every 100 patients undergoing surgery for cancer.Interpretation Hospitals with higher levels of infrastructure and resources have better outcomes after cancer surgery, independent of country income. Without urgent strengthening of hospital infrastructure and resources, the reductions in cancer-associated mortality associated with improved access will not be realised