The NICHD Fetal 3D Study: A Pregnancy Cohort Study of Fetal Body Composition and Volumes.

There's a paucity of robust normal fractional limb and organ volume standards from a large and diverse ethnic population. The Fetal 3D Study was designed to develop research and clinical applications for fetal soft tissue and organ volume assessment. The NICHD Fetal Growth Studies (2009-2013) collected 2D and 3D fetal volumes. In the Fetal 3D Study (2015-2019), sonographers performed longitudinal 2D and 3D measurements for specific fetal anatomical structures in research ultrasounds of singletons and dichorionic twins. The primary aim was to establish standards for fetal body composition and organ volumes, overall and by maternal race/ethnicity, and determine whether these standards vary for twins versus singletons. We describe the study design, methods, and details about reviewer training. Basic characteristics of this cohort, with their corresponding distributions of fetal 3D measurements by anatomical structure, are summarized. This investigation is responsive to critical data gaps in understanding serial changes in fetal subcutaneous fat, lean body mass, and organ volume in association with pregnancy complications. In the future, this cohort can answer critical questions regarding the potential influence of maternal characteristics, lifestyle factors, nutrition, and biomarker and chemical data on longitudinal measures of fetal subcutaneous fat, lean body mass, and organ volumes.

Multiethnic growth standards for fetal body composition and organ volumes derived from 3D ultrasonography.

BACKGROUND: A major goal of contemporary obstetrical practice is to optimize fetal growth and development throughout pregnancy. To date, fetal growth during prenatal care is assessed by performing ultrasonographic measurement of 2-dimensional fetal biometry to calculate an estimated fetal weight. Our group previously established 2-dimensional fetal growth standards using sonographic data from a large cohort with multiple sonograms. A separate objective of that investigation involved the collection of fetal volumes from the same cohort. OBJECTIVE: The Fetal 3D Study was designed to establish standards for fetal soft tissue and organ volume measurements by 3-dimensional ultrasonography and compare growth trajectories with conventional 2-dimensional measures where applicable. STUDY DESIGN: The National Institute of Child Health and Human Development Fetal 3D Study included research-quality images of singletons collected in a prospective, racially and ethnically diverse, low-risk cohort of pregnant individuals at 12 U.S. sites, with up to 5 scans per fetus (N=1730 fetuses). Abdominal subcutaneous tissue thickness was measured from 2-dimensional images and fetal limb soft tissue parameters extracted from 3-dimensional multiplanar views. Cerebellar, lung, liver, and kidney volumes were measured using virtual organ computer aided analysis. Fractional arm and thigh total volumes, and fractional lean limb volumes were measured, with fractional limb fat volume calculated by subtracting lean from total. For each measure, weighted curves (fifth, 50th, 95th percentiles) were derived from 15 to 41 weeks' using linear mixed models for repeated measures with cubic splines. RESULTS: Subcutaneous thickness of the abdomen, arm, and thigh increased linearly, with slight acceleration around 27 to 29 weeks. Fractional volumes of the arm, thigh, and lean limb volumes increased along a quadratic curvature, with acceleration around 29 to 30 weeks. In contrast, growth patterns for 2-dimensional humerus and femur lengths demonstrated a logarithmic shape, with fastest growth in the second trimester. The mid-arm area curve was similar in shape to fractional arm volume, with an acceleration around 30 weeks, whereas the curve for the lean arm area was more gradual. The abdominal area curve was similar to the mid-arm area curve with an acceleration around 29 weeks. The mid-thigh and lean area curves differed from the arm areas by exhibiting a deceleration at 39 weeks. The growth curves for the mid-arm and thigh circumferences were more linear. Cerebellar 2-dimensional diameter increased linearly, whereas cerebellar 3-dimensional volume growth gradually accelerated until 32 weeks followed by a more linear growth. Lung, kidney, and liver volumes all demonstrated gradual early growth followed by a linear acceleration beginning at 25 weeks for lungs, 26 to 27 weeks for kidneys, and 29 weeks for liver. CONCLUSION: Growth patterns and timing of maximal growth for 3-dimensional lean and fat measures, limb and organ volumes differed from patterns revealed by traditional 2-dimensional growth measures, suggesting these parameters reflect unique facets of fetal growth. Growth in these three-dimensional measures may be altered by genetic, nutritional, metabolic, or environmental influences and pregnancy complications, in ways not identifiable using corresponding 2-dimensional measures. Further investigation into the relationships of these 3-dimensional standards to abnormal fetal growth, adverse perinatal outcomes, and health status in postnatal life is warranted.

Biliary Disorders, Anomalies, and Malignancies in Children.

Biliary abnormalities in children are uncommon, and the spectrum of biliary disorders is broader than in adult patients. Unlike in adults, biliary disorders in children are rarely neoplastic and are more commonly rhabdomyosarcoma rather than cholangiocarcinoma. Pediatric biliary disorders may be embryologic or congenital, such as anatomic gallbladder anomalies, anomalous pancreaticobiliary tracts, various cholestatic processes, congenital cystic lesions, or genetic conditions. They may also be benign, such as biliary filling anomalies, biliary motility disorders, and biliary inflammatory and infectious disorders. Distinguishing these entities with a single imaging modality is challenging. US is the primary imaging modality for initial evaluation of biliary abnormalities in children, due to its wide availability, lack of ionizing radiation, and low cost and because it requires no sedation. Other examinations such as MRI, CT, and nuclear medicine examinations may provide anatomic and functional information to narrow the diagnosis further. Hepatobiliary-specific contrast material with MRI can provide better assessment of biliary anatomy on delayed images than can traditional MRI contrast material. MR cholangiopancreatography (MRCP) allows visualization of the intra- and extrahepatic biliary ducts, which may not be possible with endoscopic retrograde cholangiopancreatography (ERCP). Suspected biliary atresia requires multiple modalities for diagnosis and timely treatment. Determining the type of choledochal cyst calls for a combination of initial US and MRCP. Many benign and malignant biliary masses require biopsy for definitive diagnosis. Knowledge of the imaging appearances of different pediatric biliary abnormalities is necessary for appropriate imaging workup, providing a diagnosis or differential diagnosis, and guiding appropriate management. ©RSNA, 2024 Test Your Knowledge questions for this article are available in the supplemental material.

Diagnostic challenges of renal medullary carcinoma and the role for cytologic assessment: Case report and literature review.

BACKGROUND: Renal medullary carcinoma (RMC) is a diagnostically challenging, aggressive primary renal malignancy associated with abysmal survival. Delays in diagnosis contribute to most patients having diffusely metastatic disease at the time of initial presentation. METHODS: We present the case of a 13-year-old African American male with sickle cell trait who presented with a renal mass and hematuria. Evaluation included imaging, fluid cultures, and cytologic assessment. RESULTS: Patient was diagnosed with RMC based on cytologic assessment of sub-centimeter fluid collections aspirated from the left kidney at the time of cortical biopsy for suspected renal mass. The additional fluid aspiration in conjunction with renal biopsy was an atypical but crucial step in early diagnosis. CONCLUSION: Cytomorphologic evaluation of fluid biospecimens is not currently part of the standard work-up for patients with renal masses but, when available, can provide crucial information that reduces time to diagnosis. Prompt symptom recognition and treatment initiation may improve patient outcomes.

Prenatal diagnosis of Poland-Möbius syndrome by multimodality fetal imaging.

We describe prenatal diagnosis of Poland-Möbius syndrome using a combination of ultrasound and MRI. Poland syndrome was diagnosed based on absence of the pectoralis muscles associated with dextroposition of the fetal heart and elevation of the left diaphragm. Associated brain anomalies that led to the diagnosis of Poland-Möbius syndrome, included ventriculomegaly, hypoplastic cerebellum, tectal beaking, and a peculiar flattening of the posterior aspect of the pons and medulla oblongata, which has been reported by postnatal diffusion tensor imaging studies as a reliable neuroimaging marker for Möbius syndrome. Since abnormalities of cranial nerves VI and VII may be difficult to detect prenatally, careful attention to the appearance of the brain stem as illustrated in the current report may aid in the prenatal diagnosis of Möbius syndrome.

Four-dimensional fetal cardiac imaging in a cohort of fetuses with suspected congenital heart disease.

BACKGROUND: Fetal cardiac magnetic resonance imaging (MRI) requires high spatial and temporal resolution and robustness to random fetal motion to capture the dynamics of the beating fetal heart. Slice-to-volume reconstruction techniques can produce high-resolution isotropic images while compensating for random fetal motion. OBJECTIVE: The objective of this study was to evaluate image quality for slice-to-volume reconstruction of four-dimensional balanced steady-state free precession (bSSFP) imaging of the fetal heart. MATERIALS AND METHODS: A cohort of 13 women carrying fetuses with congenital heart disease were imaged with real-time bSSFP sequences. Real-time bSSFP sequences were post-processed using a slice-to-volume reconstruction algorithm to produce retrospectively gated 4-D sequences with isotropic spatial resolution. Two radiologists evaluated slice-to-volume reconstruction image quality on a scale from 0 to 4 using 11 categories based on a segmental approach to defining cardiac anatomy and pathology. A score of 0 corresponded to cardiac structures not visualized at all and four corresponded to high quality and distinct appearance of structures. RESULTS: In 11 out of 13 cases, the average radiologist score of image quality across all categories was 3.0 or greater. In the remaining two cases, slice-to-volume reconstruction was not possible due to insufficient image quality in the acquisition. CONCLUSION: Slice-to-volume reconstruction has the potential to produce isotropic images with high spatial and temporal resolution that can display the anatomy of the fetal heart in arbitrary imaging planes retrospectively. More rapid, motion-robust acquisitions may be necessary to successfully reconstruct the fetal heart in all patients.

Marine Sensors: Recent Advances and Challenges.

The ocean has a huge impact on our way of life; therefore, there is a need to monitor and protect its biodiversity [...].

Design and In Situ Validation of Low-Cost and Easy to Apply Anti-Biofouling Techniques for Oceanographic Continuous Monitoring with Optical Instruments.

Biofouling is the major factor that limits long-term monitoring studies with automated optical instruments. Protection of the sensing areas, surfaces, and structural housing of the sensors must be considered to deliver reliable data without the need for cleaning or maintenance. In this work, we present the design and field validation of different techniques for biofouling protection based on different housing materials, biocides, and transparent coatings. Six optical turbidity probes were built using polylactic acid (PLA), acrylonitrile butadiene styrene (ABS), PLA with copper filament, ABS coated with PDMS, ABS coated with epoxy and ABS assembled with a system for in situ chlorine production. The probes were deployed in the sea for 48 days and their anti-biofouling efficiency was evaluated using the results of the field experiment, visual inspections, and calibration signal loss after the tests. The PLA and ABS were used as samplers without fouling protection. The probe with chlorine production outperformed the other techniques, providing reliable data during the in situ experiment. The copper probe had lower performance but still retarded the biological growth. The techniques based on transparent coatings, epoxy, and PDMS did not prevent biofilm formation and suffered mostly from micro-biofouling.

Biomaterials and Bioactive Natural Products from Marine Invertebrates: From Basic Research to Innovative Applications.

Aquatic invertebrates are a major source of biomaterials and bioactive natural products that can find applications as pharmaceutics, nutraceutics, cosmetics, antibiotics, antifouling products and biomaterials. Symbiotic microorganisms are often the real producers of many secondary metabolites initially isolated from marine invertebrates; however, a certain number of them are actually synthesized by the macro-organisms. In this review, we analysed the literature of the years 2010-2019 on natural products (bioactive molecules and biomaterials) from the main phyla of marine invertebrates explored so far, including sponges, cnidarians, molluscs, echinoderms and ascidians, and present relevant examples of natural products of interest to public and private stakeholders. We also describe omics tools that have been more relevant in identifying and understanding mechanisms and processes underlying the biosynthesis of secondary metabolites in marine invertebrates. Since there is increasing attention on finding new solutions for a sustainable large-scale supply of bioactive compounds, we propose that a possible improvement in the biodiscovery pipeline might also come from the study and utilization of aquatic invertebrate stem cells.

Ultrasound for malrotation and volvulus - point.

Upper gastrointestinal series is considered the gold standard imaging test to evaluate for malrotation and midgut volvulus. US has been explored for this purpose in recent years and has been shown to be a good alternative because of its relatively good accuracy, fast learning curve for sonographers and radiologists, as well as convenience for children, clinical staff and radiologists in the neonatal intensive care unit. In this article we describe our experience and review the evidence supporting the use of emergency US primarily to diagnose midgut volvulus as well as its use as a problem-solving tool for the diagnosis of malrotation. The examination technique, normal and abnormal findings are described, with emphasis on the whirlpool and superior mesenteric artery cutoff signs to diagnose midgut volvulus.

Contribution of fetal magnetic resonance imaging in fetuses with congenital heart disease.

BACKGROUND: Increasing evidence supports an association among congenital heart disease (CHD), structural brain lesions on neuroimaging, and increased risk of neurodevelopmental delay and other structural anomalies. Fetal MRI has been found to be effective in demonstrating fetal structural and developmental abnormalities. OBJECTIVE: To determine the contribution of fetal MRI to identifying cardiovascular and non-cardiovascular anomalies in fetuses with CHD compared to prenatal US and fetal echocardiography. MATERIALS AND METHODS: We performed a retrospective study of fetuses with CHD identified by fetal echocardiography. Exams were performed on 1.5-tesla (T) or 3-T magnets using a balanced turbo field echo sequence triggered by an external electrocardiogram simulator with a fixed heart rate of 140 beats per minute (bpm). Fetal echocardiography was performed by pediatric cardiologists and detailed obstetrical US by maternal-fetal medicine specialists prior to referral to MRI. We compared the sensitivity of fetal MRI and fetal echocardiography for the diagnosis of cardiovascular anomalies, as well as the sensitivity of fetal MRI and referral US for the diagnosis of non-cardiac anomalies. We performed statistical analysis using the McNemar test. RESULTS: We identified 121 anomalies in 31 fetuses. Of these, 73 (60.3%) were cardiovascular and 48 (39.7%) involved other organ systems. Fetal echocardiography was more sensitive for diagnosing cardiovascular anomalies compared to fetal MRI, but the difference was not statistically significant (85.9%, 95% confidence interval [CI] 77.8-94.0% vs. 77.5%, 95% CI 67.7-87.2%, respectively; McNemar test 2.29; P=0.13). The sensitivity of fetal MRI was higher for diagnosing extracardiac anomalies when compared to referral US (84.1%, 95% CI 73.3-94.9% vs. 31.8%, 95% CI 18.1-45.6%, respectively; McNemar test 12.9; P<0.001). The additional information provided by fetal MRI changed prognosis, counseling or management for 10/31 fetuses (32.2%), all in the group of 19 fetuses with anomalies in other organs and systems besides CHD. CONCLUSION: Fetal MRI performed in a population of fetuses with CHD provided additional information that altered prognosis, counseling or management in approximately one-third of the fetuses, mainly by identifying previously unknown anomalies in other organs and systems.

Underwater Energy Harvesting to Extend Operation Time of Submersible Sensors.

A linear electromagnetic energy harvesting device for underwater applications, fabricated with a simple manufacturing process, was developed to operate with movement frequencies from 0.1 to 0.4 Hz. The generator has two coils, and the effect of the combination of the two coils was investigated. The experimental study has shown that the energy capture system was able to supply energy to several ocean sensors, producing 7.77 mJ per second with wave movements at 0.4 Hz. This study shows that this energy is enough to restore the energy used by the battery or the capacitor and continue supplying energy to the sensors used in the experimental work. For an ocean wave frequency of 0.4 Hz, the generator can supply power to 8 sensors or 48 sensors, depending on the energy consumed and its optimization.

Mass Spectrometry-Based Proteomic and Metabolomic Profiling of Serum Samples for Discovery and Validation of Tuberculosis Diagnostic Biomarker Signature.

Tuberculosis (TB) is a transmissible disease listed as one of the 10 leading causes of death worldwide (10 million infected in 2019). A swift and precise diagnosis is essential to forestall its transmission, for which the discovery of effective diagnostic biomarkers is crucial. In this study, we aimed to discover molecular biomarkers for the early diagnosis of tuberculosis. Two independent cohorts comprising 29 and 34 subjects were assayed by proteomics, and 49 were included for metabolomic analysis. All subjects were arranged into three experimental groups­healthy controls (controls), latent TB infection (LTBI), and TB patients. LC-MS/MS blood serum protein and metabolite levels were submitted to univariate, multivariate, and ROC analysis. From the 149 proteins quantified in the discovery set, 25 were found to be differentially abundant between controls and TB patients. The AUC, specificity, and sensitivity, determined by ROC statistical analysis of the model composed of four of these proteins considering both proteomic sets, were 0.96, 93%, and 91%, respectively. The five metabolites (9-methyluric acid, indole-3-lactic acid, trans-3-indoleacrylic acid, hexanoylglycine, and N-acetyl-L-leucine) that better discriminate the control and TB patient groups (VIP > 1.75) from a total of 92 metabolites quantified in both ionization modes were submitted to ROC analysis. An AUC = 1 was determined, with all samples being correctly assigned to the respective experimental group. An integrated ROC analysis enrolling one protein and four metabolites was also performed for the common control and TB patients in the proteomic and metabolomic groups. This combined signature correctly assigned the 12 controls and 12 patients used only for prediction (AUC = 1, specificity = 100%, and sensitivity = 100%). This multiomics approach revealed a biomarker signature for tuberculosis diagnosis that could be potentially used for developing a point-of-care diagnosis clinical test.

Employing molecularly imprinted polymers in the development of electroanalytical methodologies for antibiotic determination.

Antibiotics, although being amazing compounds, need to be monitored in the environment and foodstuff. This is primarily to prevent the development of antibiotic resistance that may make them ineffective. Unsurprisingly, advances in analyticalsciences that can improve their determination are appreciated. Electrochemical techniques are known for their simplicity, sensitivity, portability and low-cost; however, they are often not selective enough without recurring to a discriminating element like an antibody. Molecular imprinting technology aims to create artificial tissues mimicking antibodies named molecularly imprinted polymers (MIPs), these retain the advantages of selectivity but without the typical disadvantages of biological material, like limited shelf-life and high cost. This manuscript aims to review all analytical methodologies for antibiotics, using MIPs, where the detection technique is electrochemical, like differential pulse voltammetry (DPV), square-wave voltammetry (SWV) or electrochemical impedance spectroscopy (EIS). MIPs developed by electropolymerization (e-MIPs) were applied in about 60 publications and patents found in the bibliographic search, while MIPs developed by other polymerization techniques, like temperature assisted ("bulk") or photopolymerization, were limited to around 40. Published works covered the electroanalysis of a wide range of different antibiotics (ß-lactams, tetracyclines, quinolones, macrolides, aminoglycosides, among other), in a wide range of matrices (food, environmental and biological).

Data Quality Assessment for Super-Resolution Fetal Brain MR Imaging: A Retrospective 1.5 T Study.

BACKGROUND: Super-resolution is a promising technique to create isotropic image volumes from stacks of two-dimensional (2D) motion-corrupted images in fetal magnetic resonance imaging (MRI). PURPOSE: To determine an acquisition quality metric and correlate that metric with radiologist perception of three-dimensional (3D) image quality. STUDY TYPE: Retrospective. SUBJECTS: Eighty-seven patients, mean gestational age 29 ± 6 weeks. FIELD STRENGTH/SEQUENCE: 1.5 T/2D fast spin-echo. ASSESSMENT: Four radiologists (L.G., D.M.E.B., P.C., and J.V.; 31, 21, 7, and 7 years' experience, respectively) graded reconstructions on a 0 to 4 scale for overall appearance and visibility of specific anatomy. During reconstruction, slices were labeled as inliers based on correlation between a simulated vs. actual acquisition. The fraction of brain voxels in inlier slicers vs. total brain voxels was measured for each acquisition. STATISTICAL TESTS: Paired sample t test, Pearson's correlation, intra-class correlation. RESULTS: The average brain mask inlier fraction for all acquisitions was 0.8. There was a statistically significant correlation (0.71) between overall reconstruction appearance and number of acquisitions with inlier fraction above 0.73. There was low correlation (0.21, P = 0.05) between the number of acquisitions used in the reconstruction and overall score when no data quality measure was considered. Similar results were found for ratings of specific anatomy. Statistically significant differences in overall perception of image quality were found when using three vs. four, four vs. five, and three vs. five high-quality acquisitions in the reconstruction. Five high-quality acquisitions were sufficient to yield an average radiologist rating of 3.59 out of 4.0 for overall image quality. DATA CONCLUSION: Reconstruction quality can be reliably predicted using the brain mask inlier fraction. Real-time super-resolution protocols could exploit this to terminate acquisition when enough high-quality acquisitions have been collected. To achieve consistent 3D image quality it may be necessary to acquire more than five scans to compensate for severely motion-corrupted acquisitions. LEVEL OF EVIDENCE: 3 TECHNICAL EFFICACY: 1.

Electroanalytical profiling of cocaine samples by means of an electropolymerized molecularly imprinted polymer using benzocaine as the template molecule.

The analysis of 'cutting' or additive agents in cocaine, like benzocaine (BZC), allows police analysts to identify each component of the sample, thus obtaining information like the drugs' provenience. This kind of drug profiling is of great value in tackling drug trafficking. Electropolymerized molecularly imprinted polymers (e-MIPs) on portable screen-printed carbon electrodes (SPCEs) were developed in this study for BZC determination. The MIPs' electropolymerization was performed on a carbon surface using the anaesthetic BZC as the template molecule and 3-amino-4-hydroxybenzoic acid (3,4-AHBA) as the functional monomer. The build-up of this biomimetic sensor was carefully characterized by cyclic voltammetry (CV) and optimized. Cyclic voltammetric investigation demonstrated that BZC oxidation had a complex and pH-dependent mechanism, but at pH 7.4 a single, well-defined oxidation feature was observed. The BZC-MIP interactions were studied by computer-aided theoretical modeling by means of density functional theory (DFT) calculations. The electroanalytical methodology was effectively applied to artificial urine samples; BZC molecular recognition was achieved with a low limit of detection (LOD) of 2.9 nmol L-1 employing square-wave voltammetry (SWV). The e-MIPs were then used to 'fingerprint' genuine cocaine samples, assisted by principal component analysis (PCA), at the central forensic laboratory of the Brazilian Federal Police (BFP) with a portable potentiostat. This electroanalysis provided proof-of-concept that the drugs could be voltammetrically 'fingerprinted' using e-MIPs supported by chemometric analysis.

NS1 glycoprotein detection in serum and urine as an electrochemical screening immunosensor for dengue and Zika virus.

The incidence of infection by the dengue virus (DENV) has grown dramatically, reaching 128 countries in tropical and subtropical regions worldwide, with a pattern of hyper-endemicity. DENV is a mosquito-borne disease having four serotypes, one or two circulating in epidemic outbreaks. The diagnosis of DENV is challenging mainly due to the circulation of new viruses with remarkable similarities, such as Zika (ZIKV) that may cause fetal microcephaly. DENV affects 390 million people per year, but these numbers may be higher due to the underreported and misclassified cases. Recently, the NS1 nonstructural protein has been described in serum and urine of DENV and ZIKV patients, suggesting its use as a biomarker for screening since a negative NS1 sample confirms the absence of these infections. Herein, a label-free immunosensor comprising an assembled nanostructured thin film of carbon nanotube-ethylenediamine is described. The advantage of in situ electrosynthesis of polymer film is to allow major control of thickness and conductivity, in addition to designing the reactive groups for functionalization. A quartz crystal microbalance system was used to estimate the thickness of the polymeric film obtained. The anti-NS1 monoclonal antibodies were immobilized to carbon nanotubes by covalent linkage, permitting a high stability during measurements. Analytical responses to NS1 were obtained by differential pulse voltammetry (DPV), showing a linear range from 20 to 800 ng mL-1 and reproducibility of 3.0%, with a limit of detection (LOD) of 6.8 ng mL- 1. This immunosensor was capable of detecting ZIKV and DENV NS1 in spiked urine and real serum in a clinical range.Graphical abstract.

Fetal brain small vessel disease 1 caused by a novel mutation in the COL4A1 gene.

A singleton fetus was referred to fetal magnetic resonance imaging (MRI) at 25 weeks due to mild ventriculomegaly and an abnormal fetal echocardiogram showing cardiomegaly, right ventricular hypertrophy and tricuspid insufficiency. Patchy areas of ischemic infarction, extensive subacute and chronic hemorrhage not respecting vascular territories, encephaloclastic cysts and closed lip schizencephaly were identified. Cataract was detected postnatally. The anomalies were caused by a pathogenic mutation (c.353 G>A; p.G118D) in the COL4A1 gene. The phenotype seen in this case, i.e. small vessel cerebral disease with or without ocular anomalies caused by COL4A1 mutations, is likely an underrecognized cause of perinatal stroke. The pattern of abnormalities reported herein should prompt strong consideration for diagnosis and molecular testing.

Meteorological conditions and thermal comfort during the athletic events of the olympic games in Rio de Janeiro in 2016.

This work is taken up to evaluate the relationship between the thermal comfort of spectators and athletes and the prevailing meteorological conditions during Rio 2016 Olympic Games. Empirical and physiological thermal comfort indices are calculated from data collected from an automatic weather station installed near the Olympic Stadium and interviews with the spectators. The study period was marked by a gradual rise in air temperature and by the occurrence of two significant weather events associated with wind gusts, which caused disturbances in some areas of the competitions. ET and NET were below the air temperature, indicating that both humidity and wind contributed to the reduction of the human-biometeorological indices. Majority of the interviewed persons reported comfortable sensation and weather conditions. These perceptions corroborate results of the thermal comfort indices calculated for these resting spectators. The comfort indices calculated for the athletes with high level of physical activity showed that PET estimated hotter thermal sensation those for the individuals at rest, indicating that the physical type of a person may strongly influence the thermal sensation and comfort during intense physical activity. Increasing trend observed in all the indices of human thermal comfort during the period of study shows consistency among them.

A Dynamic Threshold Cancellation Technique for a High-Power Conversion Efficiency CMOS Rectifier.

Power conversion efficiency (PCE) has been one of the key concerns for power management circuits (PMC) due to the low output power of the vibrational energy harvesters. This work reports a dynamic threshold cancellation technique for a high-power conversion efficiency CMOS rectifier. The proposed rectifier consists of two stages, one passive stage with a negative voltage converter, and another stage with an active diode controlled by a threshold cancellation circuit. The former stage conducts the signal full-wave rectification with a voltage drop of 1 mV, whereas the latter reduces the reverse leakage current, consequently enhancing the output power delivered to the ohmic load. As a result, the rectifier can achieve a voltage and power conversion efficiency of over 99% and 90%, respectively, for an input voltage of 0.45 V and for low ohmic loads. The proposed circuit is designed in a standard 130 nm CMOS process and works for an operating frequency range from 800 Hz to 51.2 kHz, which is promising for practical applications.