scholarly journals Experimental Efficacy of the Face Shield and the Mask against Emitted and Potentially Received Particles

2021 ◽  
Vol 18 (4) ◽  
pp. 1942
Author(s):  
Jean-Michel Wendling ◽  
Thibaut Fabacher ◽  
Philippe-Pierre Pébaÿ ◽  
Isabelle Cosperec ◽  
Michaël Rochoy
Keyword(s):  
Community Setting ◽  
Reduction Factor ◽  
Source Control ◽  
Sufficient Evidence ◽  
Type I ◽  
Experimental Conditions ◽  
Particle Counter ◽  
Performance Effect ◽  
Inhaled Particles ◽  
The Face

There is currently not sufficient evidence to support the effectiveness of face shields for source control. In order to evaluate the comparative barrier performance effect of face masks and face shields, we used an aerosol generator and a particle counter to evaluate the performance of the various devices in comparable situations. We tested different configurations in an experimental setup with manikin heads wearing masks (surgical type I), face shields (22.5 cm high with overhang under the chin of 7 cm and circumference of 35 cm) on an emitter or a receiver manikin head, or both. The manikins were face to face, 25 cm apart, with an intense particle emission (52.5 L/min) for 30 s. The particle counter calculated the total cumulative particles aspirated on a volume of 1.416 L In our experimental conditions, when the receiver alone wore a protection, the face shield was more effective (reduction factor = 54.8%), while reduction was lower with a mask (reduction factor = 21.8%) (p = 0.002). The wearing of a protective device by the emitter alone reduced the level of received particles by 96.8% for both the mask and face shield (p = NS). When both the emitter and receiver manikin heads wore a face shield, the protection allowed for better results in our experimental conditions: 98% reduction for the face shields versus 97.3% for the masks (p = 0.01). Face shields offered an even better barrier effect than the mask against small inhaled particles (<0.3 µm–0.3 to 0.5 µm–0.5 to 1 µm) in all configurations. Therefore, it would be interesting to include face shields as used in our experimental study as part of strategies to reduce transmission within the community setting.

scholarly journals Experimental efficacy of the face shield and the mask against emitted and potentially received particles

2020 ◽  
Author(s):  
Michaël Rochoy ◽  
Thibaut Fabacher ◽  
Isabelle Cosperec ◽  
Jean-Michel Wendling
Keyword(s):  
Short Distance ◽  
Community Setting ◽  
Particle Sizes ◽  
Small Particle Size ◽  
Comparative Performance ◽  
Particle Counter ◽  
Aerosol Generator ◽  
Optical Particle Counter ◽  
The Face ◽  
Number Of Particles

AbstractThe aim of this study was to evaluate the comparative performance of masks and face shields in different experimental configurations. An experimental setup with two mannequin heads positioned at 1.70m high and at 25 cm each other was used. A fogger generated a particle’s airflow with a speed of 5m/sec from the emitter to the receiver head mannequin. Our aerosol generator produced 3 000 times more particles than a physiological cough situation. A particle counter allowed us to evaluate the number of particles received on a mannequin head located at a very short distance of 25 cm. The amount of all particles up to the selected particle sizes were counted with an optical particle counter on channels 0.3 µm, 0.5 µm, 1 µm, 2.5 µm, 5 µm and 10 µm. The reduction factors with a protection worn by the receiver alone, by the emitter alone and then the double protection of emitter and receiver were calculated. When the receiver alone wore a face shield, the amount of total particles was reduced (54.8%), while the reduction was less when the receiver alone wore a mask (21.8%) (p = 0.003). Wearing a protection by the emitter alone reduced much more the level of particles received by 96.8% for both mask and face shield. The double protection allowed for even better results, but close to the protection of the emitter alone: 98% reduction for the face shields and 97.3% for the masks (p=0.022). Even with small particle size emission (≤0.3µm), results were of the same order. Considering our results, protection of the emitter alone or double protection is much more effective than protection of the receiver only. Validated face shield should be included as part of strategies to safely and significantly reduce transmission in the community setting, in addition to masks or for people with disabilities or medical intolerance to masks.

scholarly journals Effect of the Process Parameters on the Adhesive Strength of Dissimilar Polymers Obtained by Multicomponent Injection Molding

Polymers ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1039 ◽  
Author(s):  
Luciano Pisanu ◽  
Leonardo Costa Santiago ◽  
Josiane Dantas Viana Barbosa ◽  
Valter Estevão Beal ◽  
Marcio Luis Ferreira Nascimento
Keyword(s):  
Adhesive Strength ◽  
Natural Fiber ◽  
Fiber Composite ◽  
Pure Shear ◽  
Central Area ◽  
Dissimilar Materials ◽  
Type I ◽  
Coconut Fiber ◽  
Adhesive Properties ◽  
Experimental Conditions

The growing demand in the consumer market for products with sustainable technologies has motivated new applications using overmolded natural fiber composites. Therefore, studies have been conducted mainly to understand the adhesive properties of overmolded parts. In the present study, a polypropylene (PP) composite with 30% coconut fibers without additives was developed with the aid of a corotating twin screw extruder. Subsequently, a multicomponent injection mold was developed based on the geometry of the ISO 527 type I specimen, in which samples overmolded with PP and PP–coconut-fiber composite, with the overlap in the central area, were obtained to evaluate the adhesive strength of dissimilar materials. The objective of this study was to evaluate the bond between PP and PP–coconut-fiber composite under different processing conditions using an adhesive strength testing device to perform a pure shear analysis. The experimental conditions followed a statistical design considering four factors in two levels and a significance level of 5%. The results indicated that adhesive strength increased significantly as the overlap area increased. It was observed that temperature and injection flow rate were the factors that most contributed to strengthening the bonds of dissimilar materials.

Treatment of Leg and Face Veins with a Cryogen Spray, Variable Pulse Width 1064 nm Nd:Yag Laser—A Prospective Study of 47 Patients

2002 ◽  
Vol 19 (1) ◽  
pp. 3-8 ◽  
Author(s):  
Cindy Y. Li ◽  
Sorin Eremia
Keyword(s):  
Prospective Study ◽  
Nd:Yag Laser ◽  
Pulse Width ◽  
Skin Type ◽  
Type I ◽  
High Fluences ◽  
Vein Segment ◽  
The Face ◽  
A Prospective Study ◽  
Reticular Veins

Objective: Throughout the 1990s, laser treatment of leg veins was a challenge. Newer, longer wavelength lasers capable of delivering high fluences with larger spot sizes with a variable pulse width have shown promising preliminary results. Experience with these lasers for treatment of facial telangiectasia and periorbital reticular veins is even more scant. To our knowledge this is the first prospective study to evaluate a variable pulse width, cryogen spray—equipped 1064 nm Nd:Yag laser for both the treatment of leg and face veins, including larger periorbital reticular veins. Materials and Methods: Forty-seven volunteers aged 32–67 years (30 with skin type I-V with leg telangiectasia and reticular veins, and 17 with skin type I-IV with face telangiectasia and reticular periorbital veins) were treated with the Nd:Yag laser. For leg vein patients, 2–3 sets of different leg veins were treated with a maximum of 3 treatments. Patients were examined 1 week after each treatment and at 1, 2, and 3 months after the last treatment. All face vein patients received 1 treatment and were examined at 1 month posttreatment. Treatment parameters for both leg and face veins varied with the size of vessels being treated. Pre- and posttreatment 35 mm photos were taken. Improvement was judged by 2 experienced physicians both visually on patients and by comparison of pre- and posttreatment photos. Results were graded as percent resolution in 5 groups: 0%, 0–25%, 25–50%, 50–75%, and 75–100%. Results: Twenty-three of 30 patients completed the leg vein segment of the study. A total of 41 leg vein sites were treated. Greater than 75% improvement was observed at 85% of the treated sites. Greater than 50% improvement was observed at 95% of the treated sites. Less than 25% improvement was observed at 5% of the treated sites. Seventeen of 17 patients completed the face vein segment of the study, and 32 sites were treated (24 cheeks, noses, and chin telangiectasia and 8 periorbital reticular veins). Greater than 75% improvement was observed at 97% of the treated sites. Greater than 50% improvement was observed at 100% of the treated sites. Notably, 100% of the facial reticular veins treated had essentially 100% resolution. Pain during treatment was variably perceived by patients, but was occasionally sufficient for patients to decline further treatment. Transient hemosiderin pigmentation, as seen with sclerotherapy, was common with larger vessels. Conclusion: The cryogen spray-equipped 1064 nm Nd: Yag laser was remarkably effective and safe for skin type I-V patients. Excellent results for leg veins, approaching sclerotherapy outcomes, were obtained for both 0.3–1.5 mm telangiectasia and larger 1.5–3.0 mm reticular veins. Furthermore, this 1064 Nd:Yag laser is also an outstanding tool for treatment of facial telangiectasia with little if any risk of purpura. For the first time we appear to have a safe and effective treatment for 1–2 mm periorbital reticular veins. The use of topical anesthesia may be needed for some patients.

scholarly journals Insights into spray impingement on mask surface: effect of mask properties on penetration and aerosolization of cough droplets

2021 ◽  
Author(s):  
Gautham Vadlamudi ◽  
Thirumalaikumaran S K ◽  
Dipshikha Chakravortty ◽  
Abhishek Saha ◽  
Saptarshi Basu
Keyword(s):  
Size Distribution ◽  
Droplet Size ◽  
Surface Effect ◽  
Real Life ◽  
Droplet Size Distribution ◽  
Source Control ◽  
Fundamental Study ◽  
The Face ◽  
Spray Impingement ◽  
Respiratory Droplets

The emergence of the COVID 19 pandemic has demonstrated the importance of face masks, making them a part of the routine during the pandemic which is still continuing. The face masks act as source control, reducing the transmission of infectious respiratory droplets by acting as a physical barrier blocking the droplets during speaking, breathing, coughing, sneezing, etc. The novelty of current study is to replicate the droplet size distribution and velocity scale similar to an actual cough or a mild sneeze and conduct a fundamental study to investigate the effects of mask properties on model-cough impingement. The spray replicates the presence of both large-sized and small-sized droplets similar to an actual cough, which makes the observations relevant to real-life situations. The spray is impinged on different mask samples with varying properties like porosity, pore size, fabric thickness, and their combinations in multilayer configuration. The effect of mask properties on the droplet penetration volume is studied as it leads to the release of higher pathogen loading into the surroundings. A two step penetration criteria based on viscous dissipation and capillary effects have been applied along with a third criteria based on the porosity of the mask sample that is specifically applicable for the spray impingement. The droplets present in the impinging cough can penetrate through the mask, atomizing into the aerosolization range and thus increasing the infection potential. Hence the effect of mask properties on the droplet size distribution as well as the velocity distribution of the penetrated droplets has been investigated, which will be essential for estimating the range of infection spread. The filtration of virus-emulating nanoparticles as well as the fate of the penetrated respiratory droplets, with a susceptible person in the proximity, has also been investigated.

scholarly journals An Optimal Model of Financial Distress Prediction: A Comparative Study between Neural Networks and Logistic Regression

Risks ◽  
2021 ◽  
Vol 9 (11) ◽  
pp. 200
Author(s):  
Youssef Zizi ◽  
Amine Jamali-Alaoui ◽  
Badreddine El Goumi ◽  
Mohamed Oudgou ◽  
Abdeslam El Moudden
Keyword(s):  
Neural Networks ◽  
Logistic Regression ◽  
Financial Distress ◽  
Prediction Models ◽  
Type I ◽  
Return On Assets ◽  
Logistic Regression Models ◽  
The Face ◽  
One Year ◽  
Type Ii Errors

In the face of rising defaults and limited studies on the prediction of financial distress in Morocco, this article aims to determine the most relevant predictors of financial distress and identify its optimal prediction models in a normal Moroccan economic context over two years. To achieve these objectives, logistic regression and neural networks are used based on financial ratios selected by lasso and stepwise techniques. Our empirical results highlight the significant role of predictors, namely interest to sales and return on assets in predicting financial distress. The results show that logistic regression models obtained by stepwise selection outperform the other models with an overall accuracy of 93.33% two years before financial distress and 95.00% one year prior to financial distress. Results also show that our models classify distressed SMEs better than healthy SMEs with type I errors lower than type II errors.

scholarly journals Another Warning about Median Reaction Time --- Version of 11 Feb 2020

2020 ◽  
Author(s):  
Jeff Miller
Keyword(s):  
Type I Error ◽  
Reaction Times ◽  
Error Rates ◽  
Type I ◽  
Experimental Conditions ◽  
Type I Error Rates ◽  
Correction Technique ◽  
Inflated Type ◽  
The Mean ◽  
Rt Distributions

Contrary to the warning of Miller (1988), Rousselet and Wilcox (2020) argued that it is better to summarize each participant’s single-trial reaction times (RTs) in a given condition with the median than with the mean when comparing the central tendencies of RT distributions across experimental conditions. They acknowledged that median RTs can produce inflated Type I error rates when conditions differ in the number of trials tested, consistent with Miller’s warning, but they showed that the bias responsible for this error rate inflation could be eliminated with a bootstrap bias correction technique. The present simulations extend their analysis by examining the power of bias-corrected medians to detect true experimental effects and by comparing this power with the power of analyses using means and regular medians. Unfortunately, although bias-corrected medians solve the problem of inflated Type I error rates, their power is lower than that of means or regular medians in many realistic situations. In addition, even when conditions do not differ in the number of trials tested, the power of tests (e.g., t-tests) is generally lower using medians rather than means as the summary measures. Thus, the present simulations demonstrate that summary means will often provide the most powerful test for differences between conditions, and they show what aspects of the RT distributions determine the size of the power advantage for means.

scholarly journals FACIAL ARTERY ON FACE - A STUDY ON SOUTH INDIAN CADAVERS AND SPECIMENS

2013 ◽  
Vol 03 (03) ◽  
pp. 072-076
Author(s):  
Lydia S. Quadros ◽  
Arathy Babu ◽  
Antony Sylvan D'souza
Keyword(s):  
Facial Artery ◽  
Type I ◽  
Type Ii ◽  
Type Iii ◽  
Medical College ◽  
South Indian ◽  
Inferior Angle ◽  
The Face ◽  
Formalin Fixed ◽  
Left Hemi

Abstract Context: Facial artery is usually the main artery supplying the face. It gives three named branches on the face, the inferior labial, the superior labial and the lateral nasal and continues as the angular artery. Face is also supplied by the transverse facial artery and the arteries accompanying the cutaneous nerves. Aim: In the present study, variations of facial artery on face were observed. Settings & design: Department of Anatomy, Kasturba Medical College, Manipal. Material & method: The present study was performed on 38 males and 12 females' formalin-fixed hemi-faces. Diameter of facial artery was noted at two specific points using a fine microcaliper. Results: The variations were divided into 3 categories. Out of 38 male hemi-faces, 100% right and 78% left hemi-faces belonged to type I category; 22% left hemi-faces belonged to Type III category. Out of 12 female hemi-faces, 80% right and 80% left hemi-faces belonged to Type I category, 18% left hemi-faces belonged to Type II category and 20% right and 2% left hemi-faces belonged to Type III category. Premasseteric branch was observed in 4 hemi-faces; a duplex with a prominent lateral angular branch was observed in 4 hemi-faces and anenlarged transverse facial artery was seen in 2 hemi-faces. The diameter of facial artery at its origin and at the antero-inferior angle of masseter muscle was larger in males. Conclusion: This study shows that the variations in the branches and the diameter of the facial artery were relatively larger in males when compared to females.

scholarly journals Data Preparation for NA62

2019 ◽  
Vol 214 ◽  
pp. 02017
Author(s):  
Paul Laycock
Keyword(s):  
Data Processing ◽  
Production System ◽  
Reduction Factor ◽  
Basic Unit ◽  
Experimental Conditions ◽  
Finite State ◽  
Reconstruction Software ◽  
Scale Experiment ◽  
Data Quality Metrics ◽  
Processing Solution

In 2017, NA62 recorded over a petabyte of raw data, collecting around a billion events per day of running. Data are collected in bursts of 3-5 seconds, producing output files of a few gigabytes. A typical run, a sequence of bursts with the same detector configuration and similar experimental conditions, contains 1500 bursts and constitutes the basic unit for offline data processing. A sample of 100 random bursts is used to make timing calibrations of all detectors, after which every burst in the run is reconstructed. Finally the reconstructed events are filtered by physics channel with an average reduction factor of 20, and data quality metrics are calculated. Initially a bespoke data processing solution was implemented using a simple finite state machine with limited production system functionality. In 2017, the ATLAS Tier-0 team offered the use of their production system, together with the necessary support. Data processing workflows were rewritten with better error-handling and I/O operations were minimised, the reconstruction software was improved and conditions data handling was changed to follow best practices suggested by the HEP Software Foundation conditions database working group. This contribution describes the experience gained in using these tools and methods for data-processing on a petabyte scale experiment.

scholarly journals Connective tissue regeneration in skeletal muscle after eccentric contraction-induced injury

2017 ◽  
Vol 122 (3) ◽  
pp. 533-540 ◽  
Author(s):  
Abigail L. Mackey ◽  
Michael Kjaer
Keyword(s):  
Skeletal Muscle ◽  
Connective Tissue ◽  
Human Skeletal Muscle ◽  
Matrix Protein ◽  
Eccentric Contraction ◽  
Eccentric Contractions ◽  
Optimal Timing ◽  
Type I ◽  
Strong Response ◽  
Experimental Conditions

Human skeletal muscle has the potential to regenerate completely after injury induced under controlled experimental conditions. The events inside the myofibers as they undergo necrosis, followed closely by satellite cell-mediated myogenesis, have been mapped in detail. Much less is known about the adaptation throughout this process of both the connective tissue structures surrounding the myofibers and the fibroblasts, the cells responsible for synthesizing this connective tissue. However, the few studies investigating muscle connective tissue remodeling demonstrate a strong response that appears to be sustained for a long time after the major myofiber responses have subsided. While the use of electrical stimulation to induce eccentric contractions vs. voluntary eccentric contractions appears to lead to a greater extent of myofiber necrosis and regenerative response, this difference is not apparent when the muscle connective tissue responses are compared, although further work is required to confirm this. Pharmacological agents (growth hormone and angiotensin II type I receptor blockers) are considered in the context of accelerating the muscle connective tissue adaptation to loading. Cautioning against this, however, is the association between muscle matrix protein remodeling and protection against reinjury, which suggests that a (so far undefined) period of vulnerability to reinjury may exist during the remodeling phases. The role of individual muscle matrix components and their spatial interaction during adaptation to eccentric contractions is an unexplored field in human skeletal muscle and may provide insight into the optimal timing of rest vs. return to activity after muscle injury.

scholarly journals PHAGOCYTOSIS OF BACTERIA IN THE ABSENCE OF ANTIBODY AND THE EFFECT OF PHYSICAL SURFACE

1956 ◽  
Vol 104 (2) ◽  
pp. 233-243 ◽  
Author(s):  
Edwin M. Lerner
Keyword(s):  
Filter Paper ◽  
Chemical Effect ◽  
Type I ◽  
Blood Leukocytes ◽  
Experimental Conditions ◽  
Phagocytic Capacity ◽  
E Coli ◽  
Physical Surface ◽  
Type Iv

The present experiments have shown that phagocytosis occurs in the absence of specific antibody and in the absence of a "suitable physical surface", as further that the presence of a rough surface does not increase the in vitro phagocytosis of pneumococci by polymorphonuclear leukocytes. This held true during repetition of Wood's experiments, as well as when more controlled quantitative techniques were employed, when conditions were made optimal for phagocytosis by increasing bacterial concentrations, and when blood leukocytes were substituted for exudate leukocytes. Evidence has been presented previously that the stimulation of phagocytosis of E. coli, B. abortus, and Type IV Pneumococcus, after contact with filter paper or an active compound present in filter paper, is a chemical effect rather than a physical effect. This type of stimulation did not occur with the Type I A5 Pneumococcus. The leukocyte of the circulating blood was found to be definitely superior to the exudate leukocyte in phagocytic capacity, under all the experimental conditions tested.

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