Damage identification in a concrete beam using curvature difference ratio

Previous studies utilising changes in mode shape or curvature to locate damage rely on the fact that the greatest change occurs around the defect. However, in concrete beams this fact is undermined due to the nature of the defect as distributed multi-site cracks. In addition, differences in mode shape and curvature as ways to locate the damage is unstable because of occurrence of modal nodes and inflection points. In this paper, one interesting solution to this problem is being tested by establishing a new non-dimensional expression designated the 'Curvature Difference Ratio (CDR)'. This parameter exploits the ratio of differences in curvature of a specific mode shape for a damaged stage and another reference stage. The expression CDR is reasonably used to locate the damage and estimate the dynamic bending stiffness in a successively loaded 6m concrete beam. Results obtained by the proposed technique are tested and validated with a case study results done by Ren and De Roeck [1] also by Maeck and De Roeck [2]. Another contribution of this work is that relating changes in vibration properties to the design bending moment at beam sections as defined in Eurocode 2 specifications [3]. Linking between a beam section condition and the change in vibration data will help to give a better comprehension on the beam condition than the applied load

Damage and repair classification in reinforced concrete beams using frequency domain data

This research aims at developing a new vibration-based damage classification technique that can efficiently be applied to a real-time large data. Statistical pattern recognition paradigm is relevant to perform a reliable site-location damage diagnosis system. By adopting such paradigm, the finite element and other inverse models with their intensive computations, corrections and inherent inaccuracies can be avoided. In this research, a two-stage combination between principal component analysis and Karhunen-Loéve transformation (also known as canonical correlation analysis) was proposed as a statistical-based damage classification technique. Vibration measurements from frequency domain were tested as possible damage-sensitive features. The performance of the proposed system was tested and verified on real vibration measurements collected from five laboratory-scale reinforced concrete beams modelled with various ranges of defects. The results of the system helped in distinguishing between normal and damaged patterns in structural vibration data. Most importantly, the system further dissected reasonably each main damage group into subgroups according to their severity of damage. Its efficiency was conclusively proved on data from both frequency response functions and response-only functions. The outcomes of this two-stage system showed a realistic detection and classification and outperform results from the principal component analysis-only. The success of this classification model is substantially tenable because the observed clusters come from well-controlled and known state conditions

Linear and non-linear deformations of a wind turbine blade considering warping and all aeroelastic load couplings

The structural dynamics behavior of the blade of a horizontal axis wind turbine that reacts to the different components of the aerodynamic loading were studied by many researchers using different approaches and assumptions. In the present research, the author considered all the extensional, torsional and flexural loadings acting on the blade with their couplings, variable airfoil cross sections with warping effects, shear deflection, rotary inertia and with or without blade\u27s pretwist for both the linear small deformation case and the nonlinear large deformation case. To the best knowledge of the author the simultaneous inclusion of all these factors has not been done before. The assumed modes method was used, in which displacements are assumed to be an expansion of products of time-step dependent constants and polynomial functions of x (where x is the coordinate along the length of the blade) that satisfy the boundary conditions at the fixed end where x=0 (hub of the blade) and at the free end where x=L (tip of the blade). The mass matrix, linear and nonlinear stiffness matrices and the load vector (function of time step) of the dynamic equations of motion are deduced from the Lagrange equations of motion that were derived step by step. The steps of the linear and nonlinear Newmark implicit iteration schemes used for solving the linear and nonlinear dynamic equations of motion respectively were explained in detail. Numerical implementation examples for both linear and nonlinear cases were demonstrated for a 14m long blade with and without pretwisting that has specific material and geometrical properties and a decreasing NACA4415 airfoil cross section from hub to tip. For both of the linear and nonlinear examples, the aerodynamic loadings (lift, drag and pitch moment) and the nonlinear stiffness matrices were computed at each time step utilizing a time dependent set of parameters such as angle of attack, material and air density, wind and blade speed, flow angle, yaw and pitch angles. Then the unknown displacements u,v and w in the directions of x, y and z axes respectively, the bending rotations Θ 1 and Θ 2 about the y and z axes respectively and the torsional rotation Φ about the x axis, were solved using the linear and nonlinear Newmark implicit iteration schemes. The linear case displacement result plots are shown to agree with the work of Younsi et al. The nonlinear case displacement result plots are shown to agree with the Ls-Dyna code

Calculation of 95% confidence interval of the median lethal dose determined by the up-and-down procedure: a letter to editor

Acute toxicity of chemicals can be determined by the up-and-down procedure (UDP) to measure the median lethal dose (LD50) in laboratory animals. An improved UPD was introduced to calculate the 95% confidence intervals (CI) for LD50 values: 95% confidence interval = LD50 + the standard error (SE) SE = SD x √2/N (SD= standard deviation of all dosages in N trials in animals). However, not all studies using the UDP report the 95% CI. Using the above mentioned equations, it is possible to calculate the 95% CI of LD50 determined by using the table of Dixon for UDP- section of the standard error 0.61. For demonstration, recalculations were done on selected LD50 values with standard deviation, standard error and 95% CI from published literature by using the above mentioned equations. These included the LD50 values of propofol and diazinon in chicks, as well as cadmium and tetramisole in mice.

Blood cholinesterase activities and oxidative stress status among farmworkers using pesticides in Duhok, KRG, Iraq

Background: The use of pesticides by farmworkers poses considerable health risks. This study was undertaken to examine plasma and erythrocyte cholinesterase activities, plasma oxidative biomarkers malondialdehyde (MDA), and total antioxidant status (TAS) among farmworkers using different pesticide products in Duhok, northern of Iraq. Methods: This is a case-control study conducted between November 2021 to July 2022 on 92 male farmworkers who were exposed to pesticides in comparison with 44 non-exposed male subjects (control). The availability and uses of pesticides were obtained from 19 agrochemical shops and the farmworkers exposed to pesticides. Demographic data of pesticide-exposed farmworkers and their practice of pesticide applications were recorded. Plasma and erythrocyte cholinesterase activities and plasma MDA and TAS levels were determined in both groups. Results: The farmworkers had a significant 10.0% increase in plasma MDA level, with no significant changes in blood cholinesterase activities or the TAS level. Odds and risk ratios of reduced plasma cholinesterase activity (20.0%) suggested an association of health risks in pesticide-exposed farmworkers. Most of the pesticide products (278) in use were insecticides (47.0%), which comprised mainly 26.0% pyrethroids and 3.0-7.0% anticholinesterase insecticides, among others. The majority of the farmworkers (51%) were merely aware of the general target use of the pesticide, and 75% had an exposure history of > 5 years. Pesticide application was mostly (50.0%) manual, and 54.0% used insufficient personal protection equipment; 32.0% ate and drank at work, 48.0% practiced disposal of empty pesticide containers by burning and/or burying them, whereas 25.0% dumped the containers indiscriminately, and 25% disposed them at garbage sites openly. Conclusion: The farmworkers, with only a marginal increase in oxidative stress biomarker MDA, did not suffer from significant reductions in blood cholinesterase activities, although odds and risk ratios of reduced plasma cholinesterase activity suggested a health risk. Implementation of a national program is needed to measure pre-exposure blood cholinesterase activities in farmworkers

Utjecaj statina na ponašanje pilića u farmakološkom testu sa ksilazin-ketaminom i karbarilom

Statins are known to affect brain function in a manner not related to their dyslipidemic effects. The purpose of the present study was to assess the behavioral response of a chick model (7-14 days old) after single treatments with the statins atorvastatin, fluvastatin or simvastatin at 100 mg/kg, orally, to a pharmacological challenge with an anesthetic regimen of xylazine (5 mg/kg)-ketamine (20 mg/kg), intramuscularly, and a toxicological challenge with the reversible cholinesterase inhibiting insecticide carbaryl (250 mg/kg, orally). Only simvastatin significantly reduced the duration of xylazine-ketamine anesthesia by 47%. Carbaryl at 250 mg/kg, orally induced signs of cholinergic poisoning (57.1 - 100%) in chicks within 3.14 min, and 57.1% death occurred within 85 min. Toxicological challenge of statin-treated chicks with carbaryl also induced signs of cholinergic poisoning, but with varying percentages of reductions compared to the control (carbaryl) group. The reductions in 4 h carbaryl-induced lethality in chicks pre-treated with atorvastatin, fluvastatin and simvastatin were 43, 57 and 29%, respectively, below that of the control value. Correspondingly, their toxicity scores decreased by 18, 18 and 11%, respectively. These data suggest that statins might modulate the functional status of the brain in a manner that affects the impact of centrally acting drugs or toxicants, and hence the behavioral outcomes in chicks. Further studies are warranted on the behavioral effects of statins after prolonged therapy.Poznato je da statini utječu na moždanu funkciju na način koji nije povezan s dislipidemijskim učincima. Svrha ovog istraživanja bila je procijeniti bihevioralni odgovor pilića (starih 7 - 14 dana) nakon liječenja statinima atorvastatinom, fluvastatinom i simvastatinom u dozi od 100 mg/kg, peroralno. Za procjenu su korištena 2 testa: farmakološki test primijenjen s kombinacijom anestetika ksilazina (5 mg/kg) i ketamina (20 mg/kg), apliciranih intramuskularno, i toksikološki test s reverzibilnim inhibitorom kolinesteraze, insekticidom karbarilom (250 mg/kg, peroralno). Samo je simvastatin znakovito skratio trajanje anestezije inducirane ksilazin-ketaminom za 47 %. Karbaril u dozi od 250 mg/kg, primijenjen peroralno, izazvao je znakove kolinergičkog otrovanja (57,1 – 100%) u pilića unutar 3,14 minuta i smrt u 57,1% pilića unutar 85 minuta. Toksikološki test s karbarilom u pilića liječenih statinima također je izazvao znakove kolinergičkog otrovanja, ali s različitim postocima smanjenja u usporedbi s kontrolnom (karbaril) skupinom. Smanjenje smrtnosti uzrokovane karbarilom unutar četiri sata u odnosu na kontrolnu skupinu iznosilo je 43% u pilića liječenih atorvastatinom, 57% u pilića liječenih fluvastatinom i 29% u pilića liječenih simvastatinom. Sukladno tome, toksičnost je smanjena za 18%, 18% i 11%. Ovi podaci upućuju na to da statini mogu modulirati funkcionalno stanje mozga utječući na učinak lijekova koji djeluju centralno ili toksikanata, te time i na ponašanje pilića. Potrebna su daljnja istraživanja učinaka statina na bihevioralni odgovor pilića nakon produljene terapije

Between life & death: Political economy of breast cancer care for refugee populations in Lebanon

Refugees and displaced groups have been shown to face increased risk of developing advanced cancer stages. This has been shown to be evident in Lebanon, whereby refugees are detected at later stages when compared to the Lebanese population. Lebanon is one of the biggest host (per capita) of refugees worldwide, and suffers from difficult political situation, compounded by an economic crisis, the COVID-19 pandemic and a blast which hit the capital Beirut in 2020. The main determinants of poor health outcomes among migrant populations in Lebanon include a fragmented and inequitable healthcare system and legal constraints to healthcare accessibility. The health care system is largely privatised with multiple health systems operating simultaneously for different nationalities. The current multi-crisis situation has exacerbated the fragility of the health system and its ability to cope with increasing needs. On the other hand, legal constraints for refugees to obtain residency in Lebanon has also contributed to insufficient access to health care and poor health outcomes among this population. Health system reforms, improved emergency preparedness and response measures, and an ease on legal and political restrictions for the refugee populations in Lebanon are considered key policy recommendations to ensure refugees right to health in Lebanon. © 2022 Elsevier Lt

Development and validation of a reversed-phase column liquid chromatographic method for simultaneous determination of two novel gliptins in their binary mixtures with Metformin

A new, simple, accurate, and precise liquid chromatographic method has been developed and validated for the determination of two novel dipeptidylpeptidase-4 (DPP-4) inhibitors; namely vildagliptin (VLG) and saxagliptin HCl (SXG) simultaneously in their binary mixtures with metformin HCl (MET). Chromatographic separation was achieved on an Inertsil® CN-3 column (250 mm x 4.6 mm, 5 µm). Isocratic elution using a mobile phase of potassium dihydrogen phosphate buffer pH (4.6) - acetonitrile (15:85, v:v) at a flow rate of 1 mL/min with UV detection at 208 nm was performed. The liquid chromatographic method was used for the simultaneous determination of either VLG, SXG and MET in the range of 5-200, 0.5-20 and 50-2000 μg/mL, respectively. The methods developed were satisfactorily applied to the analysis of the pharmaceutical formulations and proved to be specific and accurate for the quality control of the cited drugs in pharmaceutical dosage forms

Metoclopramide-induced central nervous system depression in the chicken

BACKGROUND: Metoclopramide is a dopamine D2-receptor antagonist used as an antiemetic and gastroprokinetic agent in man and animals. The drug causes sedation as a side effect in man. Such a sedative action of metoclopramide has not been documented in the chicken as the drug is not used clinically in this species. The present study examines the central nervous system depressant effects of metoclopramide in 7–14 days old broiler chicks. RESULTS: Injection of metoclopramide at 50, 100 and 200 mg/kg, subcutaneously (s.c.) induced sedation in the chicks in a dose dependent manner. The chicks manifested, within 3.6–19 minutes of metoclopramide injection, signs of sedation characterized by drooping of the head and wings, closed eyelids, reduced motility and decreased distress calls. The duration of sedation ranged between 37.2 to 163.4 minutes. Metoclopramide at 100 and 200 mg/kg induced, within 12.2 and 6.2 minutes, sleep (loss of righting reflex) for 43.8 and 158.6 minutes, respectively. The median effective doses of metoclopramide for induction of sedation and sleep in the chicks were 11 and 53 mg/kg, s.c., respectively. Lower doses of metoclopramide (5 and 10 mg/kg, s.c.) significantly decreased the open-field activity of the chicks and increased the durations of their tonic immobility. All treated-chicks recovered from the central nervous system depressant effect of metoclopramide without any observable adverse effects. CONCLUSION: The data suggest that metoclopramide induces central nervous system depression in chicks, and the drug could have potential clinical applications as a sedative-hypnotic agent in avian species not intended for human consumptions