3,117 research outputs found

    Exact solutions and conservation lawsof a one-dimensional PDE model for a blood vessel

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    Two aspects of a widely used 1D model of blood flow in a single blood vessel are studied by symmetry analysis, where the variables in the model are the blood pressure and the cross-section area of the blood vessel. As one main result, all travelling wave solutions are found by explicit quadrature of the model. The features, behaviour, and boundary conditions for these solutions are discussed. Solutions of interest include shock waves and sharp wave-front pulses for the pressure and the blood flow. Another main result is that three new conservation laws are derived for inviscid flows. Compared to the well-known conservation laws in 1D compressible fluid flow, they describe generalized momentum and generalized axial and volumetric energies. For viscous flows, these conservation laws get replaced by conservation balance equations which contain a dissipative term proportional to the friction coefficient in the model.Comment: 23 pages; 9 figure

    Symmetry analysis and hidden variational structure of Westervelt's equation in nonlinear acoustics

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    Westervelt's equation is a nonlinear wave equation that is widely used to model the propagation of sound waves in a compressible medium, with one important application being ultra-sound in human tissue. Two fundamental aspects of this equation -- symmetries and conservation laws -- are studied in the present work by modern methods. Numerous results are obtained: new conserved integrals; potential systems yielding hidden symmetries and nonlocal conservation laws; mapping of Westervelt's equation in the undamped case into a linear wave equation; exact solutions arising from the mapping; hidden variational structures, including a Lagrangian and a Hamiltonian; a recursion operator and a Noether operator; contact symmetries; higher-order symmetries and conservation laws.Comment: 23 pages; published versio

    Association between Family Dysfunction and Post-Traumatic Stress Disorder in School Students during the Second COVID-19 Epidemic Wave in Peru

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    "Although the effect of the COVID-19 pandemic on children and adolescents’ mental health has been studied, there is still scarce evidence of the influence of nuclear family on the development of post-traumatic stress disorder (PTSD). This study aimed to determine the association between family dysfunction and PTSD in Peruvian high-school students during the COVID-19 pandemic. A cross-sectional study was conducted using a virtual survey administered to 562 high-school students in three schools in Chiclayo, Peru. The dependent variable was PTSD, which was measured with the Child PTSD Symptom Scale. Family dysfunction was the main independent variable, measured with the Family APGAR Questionnaire. Prevalence ratios (PR) and 95% confidence intervals (95% CI) were estimated with generalized linear models. Most of the students were female (88.3%) and the average age was 14.4 years. We found that 21.4% showed severe family dysfunction and 60.3% had PTSD. Students with mild and moderate family dysfunction had 37% (PR: 1.37; 95% CI: 1.14–1.65) and 26% (PR: 1.26; 95% CI: 1.04–1.54) higher PTSD prevalence, respectively. In conclusion, family dysfunction may influence the development of PTSD in adolescents. This study suggests the importance to develop a healthy family environment to help adolescents face critical situations experienced during the pandemic.

    Support of advanced technologies in supply chain processes and sustainability impact

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    This paper aims to present a study of the type of advanced technologies used across manufacturing supply chains in supporting the main processes of the supply chain operations reference model (SCOR). It also intends to identify a set of sustainable performance indicators (environmental, economic, and social) suitable to evaluate a supply chain 4.0 (SC4.0). To attain this objective, based on the literature review, a conceptual model is proposed. The multiple case study is used with a cross-case comparison to identify the type of advanced technologies more commonly used in SC4.0, and the performance indicators more suitable for assessing a SC4.0 sustainability performance. A sample of ten case studies was considered with companies belonging to different manufacturing SCs, from different countries, and belonging to different echelons. Main findings revealed that the level of adoption of advanced technologies in the Supply Chain SCOR processes varies amongst the case studies. Some technologies are quite commonly used among the several SCOR processes and companies while others are seldom applied. Some indicators were also identified that are regarded as very or extremely suitable to evaluate the sustainability performance of a SC4.0. The main contribution of this research to the body of knowledge is the empirical insights on the SC4.0 field and on Supply Chain Sustainability performance measurement. The results provide guidelines for the selection of advanced technologies to support SC processes and for the design of sustainable SC4.0 performance measurement systems.This work has been funded by national funds through FCT—Fundação para a Ciência e a Tecnologia, I.P., Projects UIDB/05037/2020, UIDB/04058/2020 and UIDB/00319/2020

    Integrating in situ and ocean color data to evaluate ecological quality under the water framework directive

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    TheWater Framework Directive (WFD) aims at evaluating the ecological status of European coastal water bodies (CWBs). This is a rather complex task and first requires the use of long-term databases to assess the e ect of anthropogenic pressure on biological communities. An in situ dataset was assembled using concomitant biological, i.e., chlorophyll a (Chl a) and environmental data, covering the years from 1995 to 2014, to enable a comprehensive assessment of eutrophication in the Western Iberia Coast (WIC). Given the temporal gaps in the dataset, especially in terms of Chl a, satellite observations were used to complement it. Positive relationships between Chl a 90th percentile and nitrogen concentrations were obtained. The Land-Uses Simplified Index (LUSI), as a pressure indicator, showed no relationship with Chl a, except in Galicia, but it highlighted a higher continental pressure in the Portuguese CWBs in comparison with Galician waters. In general terms, the trophic index (TRIX) showed that none of the CWBs were in degraded conditions. Nevertheless, the relatively high TRIX and LUSI values obtained for the water body in front of Tagus estuary suggest that this area should be subject to continued monitoring. Results highlighted the usefulness of satellite data in water quality assessments and set the background levels for the implementation of operational monitoring based on satellite Chl a. In the future, low uncertainty and harmonized satellite products across countries should be provided. Moreover, the assessment of satellite-based eutrophication indicators should also include metrics on phytoplankton phenology and community structure.CEECIND/00095/2017/ UIDB/04326/2020/ UID/MAR/04292/2020info:eu-repo/semantics/publishedVersio

    Gluteus maximus transfer for hip abductor deficiency

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    Hip abductor deficiency resulting from gluteus medius and minimus pathology is increasingly recognized as a generator of lateral-sided hip pain. In the setting of a failed gluteus medius repair or in patients with irreparable tears, transfer of the anterior portion of the gluteus maximus muscle can be performed to treat gluteal abductor deficiency. The classic description of the gluteus maximus transfer technique relies solely on bone tunnel fixation. This article describes a reproducible technique that incorporates the addition of a distal row to the tendon transfer, which may improve fixation by both compressing the tendon transfer to the greater trochanter and providing improved biomechanical strength to the transfer

    Inhibition of bladder tumor growth by chitooligosaccharides in an experimental carcinogenesis model

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    Urinary bladder cancer is one of the most common cancers worldwide, with the highest incidence in industrialized countries. Patients with cancer commonly use unconventional and complementary therapy including nutraceuticals. In this study we evaluated the efficacy of chitooligosaccharides (in orange juice) in rat bladder cancer chemoprevention and as therapeutic agent, on a rat model of urinary bladder carcinogenesis induced with N-butyl-N-(4-hydroxybutyl) nitrosamine. Results indicate that chitooligosaccharides may have a preventive effect on bladder cancer development and a curative effect upon established bladder tumors, dependent on the concentration ingested 500 mg/kg b.w., every three days, showed capacity to inhibit and prevent the proliferation of bladder cancer; however, this was associated with secondary effects such as hypercholesterolemia and hypertriglyceridemia. The use of lower doses (50 and 250 mg/kg b.w.) showed only therapeutic effects. It is further suggested that this antitumor effect might be due to its expected anti-inflammatory action, as well as by mechanisms not directly dependent of COX-2 inhibition, such as cellular proliferation control and improvement in antioxidant profile.info:eu-repo/semantics/publishedVersio

    Association between childhood trauma and mental health disorders in adolescents during the second pandemic wave of COVID-19, Chiclayo-Peru

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    "Introduction: The COVID-19 pandemic has significantly affected mental health, with children and adolescents being particularly vulnerable. Evidence on the association between childhood trauma and mental health outcomes in schoolchildren during the pandemic is limited. This study aimed to evaluate this relationship in Chiclayo city, northern Peru, during the second wave of COVID-19. Methods: A cross-sectional secondary data study was conducted, measuring childhood trauma using the Marshall’s Trauma Scale, depressive symptomatology (PHQ-9), and anxiety symptomatology (GAD-7). Additional variables assessed were alcohol use (AUDIT), resilience (abbreviated CD-RISC), and socio-educational data. Prevalence ratios were estimated using generalized linear models. Results: Among 456 participants, 88.2% were female, with a mean age of 14.5 years (SD: 1.33). Depressive symptomatology prevalence was 76.3% (95%CI: 72.14– 80.15) and increased by 23% in schoolchildren with childhood trauma (PR: 1.23; 95%CI: 1.10–1.37). Factors positively associated with depressive symptomatology included increasing age, seeking mental health help during the pandemic, and severe family dysfunction. Anxiety symptomatology prevalence was 62.3% (95%CI: 57.65–66.75) and increased by 55% in schoolchildren with childhood trauma (PR: 1.55; 95%CI: 1.31–1.85). Anxiety symptomatology was positively associated with mild, moderate, and severe family dysfunction. Conclusion: Schoolchildren exposed to childhood trauma are at increased risk for depressive and anxiety symptoms. Monitoring the impact of the COVID-19 pandemic on adolescent mental health is vital. These findings can assist schools in establishing effective measures to prevent mental health outcomes

    Population Pharmacokinetic Analysis of Lanreotide Autogel® in Healthy Subjects: evidence for injection interval of up to 2 months

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    BACKGROUND AND OBJECTIVE: Lanreotide is a somatostatin analogue used for the treatment of acromegaly and neuroendocrine tumours. The objective of this study was to develop a pharmacokinetic model for the sustained-release formulation lanreotide Autogel after deep subcutaneous administration in healthy subjects, and to explore the potential effect of covariates, especially sex and dose. SUBJECTS AND METHODS: This was an open-label, single-centre, randomized, dose-ranging, parallel-group study, with a follow-up period of 4-7 months following drug administration in healthy subjects. Healthy Caucasian subjects aged 18-45 years were included. Subjects received a rapid intravenous bolus of 7 microg/kg of an immediate-release formulation of lanreotide (lanreotide IRF). After a 3-day washout period, participants were randomized to receive a single deep subcutaneous injection of lanreotide Autogel at a dose of 60, 90 or 120 mg. PHARMACOKINETIC AND STATISTICAL ANALYSIS: Blood samples for lanreotide determination were obtained during the first 12 hours after the intravenous bolus injection and during the 4- to 7-month follow-up period after deep subcutaneous administration of lanreotide Autogel. Data after intravenous and subcutaneous administration were fitted simultaneously using the population approach in NONMEM((R)) version VI software. The model was validated externally using data from patients with acromegaly. RESULTS: In total, 50 healthy subjects (24 women and 26 men) received a single intravenous dose of lanreotide IRF. Of these, 38 subjects (18 women and 20 men) received a single subcutaneous dose of lanreotide Autogel 3 days after intravenous lanreotide IRF. The disposition of lanreotide was described by a three-compartment open model. The estimates of the total volume of distribution and serum clearance were 15.1 L and 23.1 L/h, respectively. The estimates of interindividual variability were 0.05). CONCLUSIONS: Population analysis allows a full description of the disposition of lanreotide after rapid intravenous bolus administration of lanreotide IRF (7 microg/kg) and the pharmacokinetics of lanreotide Autogel after a single deep subcutaneous injection (60, 90 or 120 mg) in healthy subjects. The model-based simulations provide support for the feasibility of extending the dosing interval for lanreotide Autogel to 56 days when given at 120 mg. The absorption profile of lanreotide Autogel was independent of the dose and was not affected by sex
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