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1.
Artif Organs ; 45(11): 1348-1359, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34181759

RESUMO

Facile methods for accurate fluid-mechanical characterization of haemofilters (HF) are indispensable for haemofiltration process improvements, equipment design/optimization, and reliable module specifications. Currently employed methods, implemented through specific experimental in vitro protocols, are assessed herein in detail, considering the conditions prevailing during haemofiltration. Minimum number of key parameters required to fully describe the common countercurrent flow field, in the HF active section, include membrane permeance K and friction coefficients in lumen and shell side (ff and fs ). It is shown that the countercurrent flow mode itself is incapable of yielding these parameters, based on externally measured flow rates and pressures. Similarly, the relevant ISO protocol is deficient as it can only provide rough underpredictions of permeance K. The causes of such inherent deficiencies of current standards and practices are analyzed. In contrast, a recently developed methodology, accounting for the (heretofore ignored) pressure drop in module headers and combining a mechanistic theoretical model with experimental data from 2 special haemofilter operating modes, yields an accurate determination of the key parameters (K, ff , fs ). Additionally, it permits a full description of flow field for Newtonian liquids, for both constant and axially varying viscosity in fiber-lumen due to the transmembrane flux. Development of new reliable standards is suggested, facilitated by the insights gained in this work.


Assuntos
Hemofiltração/instrumentação , Hidrodinâmica , Desenho de Equipamento , Hemofiltração/normas , Membranas Artificiais , Modelos Teóricos
2.
Sensors (Basel) ; 20(14)2020 Jul 08.
Artigo em Inglês | MEDLINE | ID: mdl-32650597

RESUMO

Application Layer Distributed Denial of Service (DDoS) attacks are very challenging to detect. The shortfall at the application layer allows formation of HTTP DDoS as the request headers are not compulsory to be attached in an HTTP request. Furthermore, the header is editable, thus providing an attacker with the advantage to execute HTTP DDoS as it contains almost similar request header that can emulate a genuine client request. To the best of the authors' knowledge, there are no recent studies that provide forged request headers pattern with the execution of the current HTTP DDoS attack scripts. Besides that, the current dataset for HTTP DDoS is not publicly available which leads to complexity for researchers to disclose false headers, causing them to rely on old dataset rather than more current attack patterns. Hence, this study conducted an analysis to disclose forged request headers patterns created by HTTP DDoS. The results of this study successfully disclose eight forged request headers patterns constituted by HTTP DDoS. The analysis was executed by using actual machines and eight real attack scripts which are capable of overwhelming a web server in a minimal duration. The request headers patterns were explained supported by a critical analysis to provide the outcome of this paper.

3.
Sci Med Footb ; : 1-10, 2023 Sep 27.
Artigo em Inglês | MEDLINE | ID: mdl-37753837

RESUMO

There is concern that exposure to soccer headers may be associated with neurological sequelae. Training proper heading technique represents a coachable intervention that may reduce head acceleration exposure. The objective was to assess relationships between heading technique and head kinematics in female youth soccer players. Fourteen players (mean age = 14.4 years) wore instrumented mouthpieces during practices and games. Headers were reviewed by three raters to assign a technique score. Mixed models and LASSO regression evaluated associations of technique with peak linear acceleration (PLA), rotational acceleration (PRA), rotational velocity (PRV), and head impact power ratio (HIP Ratio) while adjusting for session type and ball delivery. Two hundred eighty-nine headers (n = 212 standing, n = 77 jumping) were analyzed. Technique score (p = 0.043) and the technique score - session type interaction (p = 0.004) were associated with PRA of standing headers, whereby each 10-unit increase in technique score was associated with an 8.6% decrease in PRA during games but a 5.1% increase in PRA during practices. Technique was not significantly associated with any other kinematic metrics; however, peak kinematics tended to decrease as technique score increased. LASSO regression identified back extension and shoulder/hip alignment as important predictors of peak kinematics. Additional research on heading technique and head acceleration is recommended.

4.
J Biomech ; 126: 110619, 2021 09 20.
Artigo em Inglês | MEDLINE | ID: mdl-34325122

RESUMO

Although most head impacts in soccer are headers, limited knowledge exists about how header magnitude varies by on-field scenario. This study aimed to compare head kinematics during on-field headers by play state (i.e., corner kick, goal kick, free kick, throw-in, drill, or live ball), intent (i.e., pass, shot, or clearance), and outcome (i.e., successful or unsuccessful). Fifteen female collegiate soccer players were instrumented with mouthpiece-based head impact sensors during 72 practices and 24 games. A total of 336 headers were verified and contextualized via film review. Play state was associated with peak linear acceleration, rotational acceleration, and rotational velocity (all p < .001) while outcome was associated with peak linear acceleration (p < .010). Header intent was not significantly associated with any kinematic metric. Headers during corner kicks (22.9 g, 2189.3 rad/s2, 9.87 rad/s), goal kicks (24.3 g, 2658.9 rad/s2, 10.1 rad/s), free kicks (18.0 g, 1843.3 rad/s2, 8.43 rad/s), and live balls (18.8 g, 1769.7 rad/s2, 8.09 rad/s) each had significantly greater mean peak linear acceleration (all p < .050), rotational acceleration (all p < .001), and rotational velocity (all p < .001) than headers during drills (13.0 g, 982.4 rad/s2, 5.28 rad/s). Headers during goal kicks also had a significantly greater mean rotational acceleration compared to headers during live ball scenarios (p < .050). Successful headers (18.3 g) had a greater mean peak linear acceleration compared to unsuccessful headers (13.8 g; p < .010). Results may help inform efforts to reduce head impact exposure in soccer.


Assuntos
Futebol , Aceleração , Fenômenos Biomecânicos , Feminino , Humanos , Intenção , Universidades
5.
Rev. Inst. Adolfo Lutz ; 33(1-2): e37050, dez.28,1973. ilus
Artigo em Português | LILACS, Coleciona SUS (Brasil), SES-SP, CONASS, SES SP - Instituto Adolfo Lutz, SES-SP, SESSP-IALACERVO | ID: biblio-1066541

RESUMO

A Biblioteca do Instituto Adolfo Lutz iniciou uma remodelação em seus catálogos (AU).


Assuntos
Descritores , Livros , Indexação e Redação de Resumos
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