high background
Recently Published Documents


TOTAL DOCUMENTS

765
(FIVE YEARS 257)

H-INDEX

45
(FIVE YEARS 6)

2022 ◽  
Vol 242 ◽  
pp. 106793
Author(s):  
Mychelle M.L. Rosa ◽  
Vera A. Maihara ◽  
Maria Helena T. Taddei ◽  
Luan T.V. Cheberle ◽  
Roseane P. Avegliano ◽  
...  

2022 ◽  
Vol 55 (1) ◽  
Author(s):  
Diandra Doppler ◽  
Mohammad T. Rabbani ◽  
Romain Letrun ◽  
Jorvani Cruz Villarreal ◽  
Dai Hyun Kim ◽  
...  

Serial femtosecond crystallography (SFX) is a powerful technique that exploits X-ray free-electron lasers to determine the structure of macromolecules at room temperature. Despite the impressive exposition of structural details with this novel crystallographic approach, the methods currently available to introduce crystals into the path of the X-ray beam sometimes exhibit serious drawbacks. Samples requiring liquid injection of crystal slurries consume large quantities of crystals (at times up to a gram of protein per data set), may not be compatible with vacuum configurations on beamlines or provide a high background due to additional sheathing liquids present during the injection. Proposed and characterized here is the use of an immiscible inert oil phase to supplement the flow of sample in a hybrid microfluidic 3D-printed co-flow device. Co-flow generation is reported with sample and oil phases flowing in parallel, resulting in stable injection conditions for two different resin materials experimentally. A numerical model is presented that adequately predicts these flow-rate conditions. The co-flow generating devices reduce crystal clogging effects, have the potential to conserve protein crystal samples up to 95% and will allow degradation-free light-induced time-resolved SFX.


2022 ◽  
Author(s):  
Gongbo Chen ◽  
Felix Landmeyer ◽  
Christian Wiede ◽  
Rainer Kokozinski

Abstract Time correlated single photon counting (TCSPC) is a statistical method to generate time-correlated histograms (TC-Hists), which are based on the time-of-flight (TOF) information measured by photon detectors such as single-photon avalanche diodes. With restricted measurements per histogram and the presence of high background light, it is challenging to obtain the target distance in a TC-Hist. In order to improve the data processing robustness under these conditions, the concept of machine learning is applied to the TC-Hist. Using the neural network-based multi-peak analysis (NNMPA), introduced by us, including a physics-guided feature extraction, a neural network multi-classifier, and a distance recovery process, the analysis is focused on a small amount of critical features in the TC-Hist. Based on these features, possible target distances with correlated certainty values are inferred. Furthermore, two optimization approaches regarding the learning ability and real-time performance are discussed. In particular, variants of the NNMPA are evaluated on both synthetic and real datasets. The proposed method not only has higher robustness in allocating the coarse position (±5 %) of the target distance in harsh conditions, but also is faster than the classical digital processing with an average-filter. Thus, it can be applied to improve the system robustness, especially in the case of high background light and middle-range detections.


2021 ◽  
Vol 59 (6) ◽  
pp. 676-683
Author(s):  
A. B. Borisova ◽  
T. A. Lisitsyna ◽  
D. Yu. Veltishchev ◽  
E. L. Nasonov

The aim - screening of anxiety, depression and stress in patients with rheumatic and musculoskeletal diseases (RMD) and medical workers at the beginning of the COVID-19.Material and methods. 150 patients (men/women: 39 (26.0%)/111 (74.0%); mean age - 43.2±16.1 years) with RMD, hospitalized at the V.A. Nasonova Research Institute of Rheumatology (Moscow) from July to November 2020, and 32 relatively healthy medical workers (men/women: 3 (9.38%)/29 (90.6%), mean age - 40.7±14.6 years) as a control group was included in the study. The Hospital Anxiety and Depression Scale (HADS) and the Depression Anxiety and Stress Scale - 21 Items (DASS-21) were used for anxiety, depression and stress screening. Results. Frequency of anxiety-depressive spectrum disorders in patients with RMD was 48% (according to DASS-21) and 27.2% (according to HADS), which did not differ significantly from the control group - 46.9% and 18.8% respectively. According to the DASS-21, patients with systemic sclerosis were significantly more likely to have a combination of clinically significant anxiety, depression and stress compared to healthy control (6 (46.2%) vs 4 (12.5%); p=0.02) and patients with spondyloarthritis (6 (46.2% vs 5 (16.1%); p=0.045). The severity of anxiety was significantly higher among patients with RMD - systemic lupus erythematosus, primary Sjogren's syndrome and systemic sclerosis, according to both scales. The severity of depression, anxiety and stress was significantly higher in women with RMD, rural residents and patients taking moderate and high doses of glucocorticoids. The pathological stress level was experienced by younger medical workers (27.5±5.45 vs 45.8±13.8 years; p=0.001). The transferred coronavirus infection did not lead to an increase in the severity of depression, anxiety and stress tension among patients, however, among medical workers, the frequency of clinically significant anxiety (4 (57.1%) vs 6 (24%)) and stress (3 (42.8%) vs 5 (20%)) was 2.2-2.9 times higher in those who have been ill. When compared with the results of the similar screening by HADS in 2012, the proportion of RМD-patients with clinically significant anxiety and depression over the past 8 years and in connection with the pandemic COVID-19 has not significantly changed.Conclusion. A new threat to health, isolation and uncertainty at the beginning of the COVID-19 were an additional stressful factor for patients with RМD, however, given the high background prevalence of low-severity chronic depression with frequent onset before RМD, the factor of the COVID-19 is not a key factor in provoking mental disorders.


Electronics ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 45
Author(s):  
Thanh-Tuan Nguyen ◽  
Ching-Hwa Cheng ◽  
Don-Gey Liu ◽  
Minh-Hai Le

Background light noise is one of the major challenges in the design of Light Detection and Ranging (LiDAR) systems. In this paper, we build a single-beam LiDAR module to investigate the effect of light intensity on the accuracy/precision and success rate of measurements in environments with strong background noises. The proposed LiDAR system includes the laser signal emitter and receiver system, the signal processing embedded platform, and the computer for remote control. In this study, two well-known time-of-flight (ToF) estimation methods, which are peak detection and cross-correlation (CC), were applied and compared. In the meanwhile, we exploited the cross-correlation technique combined with the reduced parabolic interpolation (CCP) algorithm to improve the accuracy and precision of the LiDAR system, with the analog-to-digital converter (ADC) having a limited resolution of 125 mega samples per second (Msps). The results show that the CC and CCP methods achieved a higher success rate than the peak method, which is 12.3% in the case of applying emitted pulses 10 µs/frame and 8.6% with 20 µs/frame. In addition, the CCP method has the highest accuracy/precision in the three methods reaching 7.4 cm/10 cm and has a significant improvement over the ADC’s resolution of 1.2 m. This work shows our contribution in building a LiDAR system with low cost and high performance, accuracy, and precision.


2021 ◽  
Author(s):  
Bea Vuylsteke ◽  
Lize Cuypers ◽  
Guy Baele ◽  
Marianne Stranger ◽  
Sarah Lima Paralovo ◽  
...  

Abstract Objectives: To better understand the conditions which have led to one of the largest COVID-19 outbreaks in Belgian nursing homes in 2020. Setting: A nursing home in Flanders, Belgium, which experienced a massive outbreak of COVID-19 after a cultural event. An external volunteer who dressed as a legendary figure visited consecutively the 4 living units and tested positive for SARS-CoV-2 the next day. Within days, residents started to display symptoms and the outbreak spread rapidly within the nursing home. Methods: We interviewed key informants and collected standardized data from all residents retrospectively. A batch of 115 positive samples with a Ct value of <37 by qRT-PCR were analysed using whole-genome sequencing. Six months after the outbreak, ventilation assessment of gathering rooms in the nursing home was done using a tracer gas test with calibrated CO2 sensors. Results: Timeline of diagnoses and symptom onsets clearly pointed to the cultural event as the start of the outbreak, with the volunteer as index case. The genotyping of positive samples depicted the presence of one large cluster, suggesting a single source outbreak. The global attack rate among residents was 77% with a significant association between infection and presence at the event. Known risk factors such as short distance to or physical contact with the volunteer, and wearing of a mask during the event were not associated with early infection. The ventilation assessment showed a high background average CO2 level in four main rooms varying from 657 ppm to 846 ppm. Conclusions: Our investigation shows a rapid and widespread single source outbreak of SARS-CoV-2 in a nursing home, in which airborne transmission was the most plausible explanation for the massive intra-facility spread. Our results underscore the importance of ventilation and air quality for the prevention of future outbreaks in closed facilities.


2021 ◽  
Author(s):  
Isadonna Tengganu ◽  
Neil Karerakattil ◽  
Swarup Dey ◽  
Devika Kishnan ◽  
Rizal Hariadi

In vitro gliding assay is a well-established assay for determining the activity of protein motors, such as actin-associated myosins and microtubule-associated kinesins and dyneins. In one of the conventional methods, protein motors are immobilized onto a nitrocellulose-coated coverslip and it propels actin filaments in the presence of ATP. Gliding assays also serve as the foundation for protein-motor-based nanotechnological devices such as biosensing and sorting. However, the preparation of nitrocellulose-coated coverslips is time-consuming and produces rough surfaces. Furthermore, the nitrocellulose film exhibits high background autofluorescence, which can be a problem in single-molecule measurements. Here, we investigated the use of hexamethyldisilazane (HMDS) to study actomyosin function and characterized its physical properties on glass coverslips and glass capillary tubes. We showed that the total preparation time to coat a coverslip with HMDS is <30 minutes, which is 1 order of magnitude faster than the >12-hour protocol for coating glass surfaces with nitrocellulose. In contrast to nitrocellulose film, HMDS vapor deposition is effortless and provides an atomically flat surface with low autofluorescence. In addition, HMDS does not interfere with myosin function, which is indicated by the similar actin gliding speed when compared with nitrocellulose. Our results show that HMDS vapor deposition is a more favorable surface treatment to nitrocellulose for in vitro gliding assay.


Author(s):  
V. L. Shannon ◽  
E. I. Vanguelova ◽  
J. I. L. Morison ◽  
L. J. Shaw ◽  
J. M. Clark

AbstractDeadwood forms a significant carbon pool in forest systems and is a potential source of dissolved organic carbon (DOC) input to soil, yet little is known about how deadwood effects forest soil carbon cycling. Deadwood DOC inputs to soil may be retained through sorption or may prime microbial decomposition of existing organic matter to produce additional DOC. To determine impacts of deadwood on soil C cycling, we analysed surface soil from beneath deadwood or leaf litter only, along chronosequences of stands of lowland oak and upland Sitka spruce. The concentration and quality (by optical indices) of water-extracted soil DOC (water-extractable organic carbon; WEOC), in situ decomposition ‘tea bag index’ (TBI) parameters and enzymatic potential assays (β-D-cellubiosidase, β-glucosidase, β-xylosidase, leucine aminopeptidase, phosphatase, phenol oxidase) were determined. Presence of deadwood significantly (p < 0.05) increased WEOC concentration (~ 1.5 to ~ 1.75 times) in the mineral oak soil but had no effect on WEOC in spruce soils, potentially because spruce deadwood DOC inputs were masked by a high background of WEOC (1168 mg kg−1 soil) and/or were not retained through mineral sorption in the highly organic (~ 90% SOM) soil. TBI and enzyme evidence suggested that deadwood-derived DOC did not impact existing forest carbon pools via microbial priming, possibly due to the more humified/aromatic quality of DOC produced (humification index of 0.75 and 0.65 for deadwood and leaf litter WEOC, respectively). Forest carbon budgets, particularly those for mineral soils, may underestimate the quantity of DOC if derived from soil monitoring that does not include a deadwood component.


2021 ◽  
Vol 2021 ◽  
pp. 1-7
Author(s):  
Willis Otieno Gor Odongo ◽  
Margaret Chege ◽  
Nadir Hashim ◽  
Shinji Tokonami ◽  
Kranrod Chutima ◽  
...  

The areas around Homa and Ruri hills in Homa Bay County in Kenya are associated with high background radiation levels. The activity concentration of the natural radionuclides (226Ra, 232Th, and 40K) in earthen building materials used in the areas of Homa and Ruri hills has been measured using a NaI (Tl) detector in this work. The measured values of radioactivity concentrations are used to estimate the associated radiological risk. The earthen building material samples from Ruri registered relatively high 232Th concentration values averaging 1094 ± 55 Bq/kg, nearly three times those of the samples from Homa. 226Ra level was not significantly different in both regions with Homa reporting 129 ± 10 Bq/kg and Ruri 111 ± 6 Bq/kg. 40K was however higher in the samples from Homa by an approximate factor of 2 relative to those from Ruri where the activity concentration was 489 ± 24 Bq/kg. The radium equivalents for 226Ra, 232Th, and 40K in the samples from Ruri were 111 ± 9, 1564 ± 125, and 38 ± 3 Bq/kg, while in Homa, the values were 129 ± 10, 570 ± 46, and 69 ± 5 Bq/kg, respectively. The calculated value of total radium equivalent in Ruri was 1713 ± 137 Bq/kg which was two times higher than that of Homa. 232Th contributed about 74% and 91% to the total radium equivalent in Homa and Ruri, respectively; thus, it was the one with the largest contribution to radiation exposure in both regions. The average indoor annual effective dose rates were 1.74 ± 0.14 and 3.78 ± 0.30 mSv/y in Homa and Ruri, respectively, both of which were above the recommended safety limit of 1 mSv/y.


Sign in / Sign up

Export Citation Format

Share Document