Examining the Van der Pol Oscillator: Stability and Bifurcation Analysis

In this paper, Van der pol equation has been analyzed for stability and bifurcation phenomena with and without forcing component. Analytical solution of the Van der pol equation using Method of Multiple Scales (MMS) is compared with numerical results obtained using MATLAB ode45 solver. Limit cycle analysis has been performed at increasing order of nonlinear damping term. Different scenarios of bifurcation have been studied with variation in control parameters

Reginol interpretation of river Indus water quality data using regression model

Water samples were collected from river Indus over 591 km2 from Kashmor to Keti Bandar/Shah Bandar in the province of Sindh, Pakistan, during 2008 and 2009 on seasonal bases. These samples were analyzed for 12 water quality variables including physical and chemical parameters. Then correlation study was carried out and correlation co-efficient “r” was determined using correlation matrix to identify the highly correlated and interrelated parameters. Regression model were developed to test the significant ‘r’ and P-value test was carried out to test the significance of the pair of parameters. F-test was also used to examine the joint-effects of several independent variables without taking into account the separate effects of each variable. The comparison of the observed and predicted values of different parameters using regression equation suggested that the regression model provide useful means of rapid and easier monitoring of water quality of a river in a region.Key words: Regression model, correlation coefficient, river indus, monitoring, physico-chemical parameters

The biochemical composition of body fluids, their osmolalities and ultrafiltrates

The serum osmolality has been determined in 101 cases of hypochloraemia. The cause of the chloride depletion was duo to vomiting, less often to continuous gastric suction, and rarely to diarrhoea or fistulae, associated with various clinical disorders. Patients were divided into three groups according to whether the serum osmolality was normal, decreased or increased. The patients in group I succeeded in maintaining the osmotic pressure within normal limits in spite of chloride depletion by the compensatory retention of bicarbonate and urea. This compensatory mechanism failed to operate in the group II patients where the loss of chloride eventually resulted in lowering the osmotic pressure. In group III patients, the serum osmolality was elevated in spite of low chloride, partly due to bicarbonate retention but mainly due to urea retention. There was a relationship between the increased serum osmolslity and urea concentration. Although the chloride ions contribute 35% of the total osmotic pressure, there was no relationship between the serum chloride concentration and the osmotic pressure in any of the three groups. The patients in group III may simply be the extension of group I cases. The transition of one group to the other probably coincides with the onset of renal dysfunction. This kidney involvement is a reversible process and, therefore, must be distinguished from renal disease. The patients in group II were quite distinct from the oases in the other two groups and wore not in the early stages of biochemical upset, end had not passed through the stages corresponding to other groups. Failure to retain urea and to maintain the osmotic pressure of extracellular fluids may be due to a defect in come mechanism presumably related to osmoregulatory centres, abnormal secretion of antidiuretic hormone or to renal tubular damage. PART 2. A new simple ultrafiltration technique has been described and the procedure outlined for ultrafiltration of blood serum. The importance of the method of sample collection, duration of ultrafiltration and pH was investigated. The ultrafiltration results were affected considerably by large changes in pH, while duration of ultrafiltration had no effect. For 20 healthy human subjects, the range for ultrafilterable celcium was found to be 55-61% of the total serum calcium. Ultrafiltration data on sera from patients with hyperparathyroidism before and after removal of parathyroid adenomas, hypoparathyroidism, vitamin D therapy, multiple myeloma, hyperealcaemia due to other causes, and renal disease has been presented. The serum ultrafilterable calcium was raised before operation in ever patient with a functioning parathyroid adenoma even though the serum total calcium was within the normal limits. After removal of the adenema, the serum ultrafilterable celcium always fell below normal. This fall was proportionately greater then the fall in the protein hound fraction. It was inferred that parathyroid hormone reduces the capacity of serum protein to hind calcium. This was supported by the observation of the effect of intravenous calcium on a human subject where the suppression of parathyroid glande resulted in an increase in the binding capacity. The ultrafilterable calcium was reduced in oases of hypercalcaemia due to causes other then hyperparathyroidium. This was also associated with reduced ultrafiltorability of inorgenic phosphate, possibly due to the formation of non-filterable calcium-phosphate-protein complex. Hence difficult cases such as these with functioning parathyroid adenoma associated with normal serum calcium values end cases with hypercalcaemia without parathyroid adenoma, the ultrafiltration results may be of some aid in the differiential diagnosis. The serum ultrafilterable calcium was found to be diminished in hypoparathyroidism, but poor correlation of the extent of tetany with either total serum calcium or the ultrafiltorable calcium was found to exist. Hypoprotenaemia was generally associated with hypocalcaemia, which was accompanied by normal or, more frequently, a high percentage ultrafiltorability of calcium. The hypoosicaemia present was due to the loss in the hound fraction. In renal disease although the total serum calcium was low the percentage of ultrafilterable calcium was almost invariably high, regardless of the concentration of serum proteins. The absence of tetany in those cases was not duo to acidosis alone. Other factors e.g. hypoalbuminaemia and the specific alteration in binding capacity of serum protein by the excess secretion of parathyroid hormone also contribute in maintaining the ultrafilterable calcium. Normal values for both serum and ultrefiltarable magnesium were found in hyperparathyroidism and in hypoparathyroidism. It was concluded that parathyroid glands play no part in magnesium metabolism

Использование терминообразующего потенциала классических языков современными языками (на примере экономической терминологии современного французского языка)

It is imperative to fascinate young children at an early stage in their education for the analytical sciences. The exposure of the public to mass spectrometry presently increases rapidly through the common media. Outreach activities can take advantage of this exposure and employ mass spectrometry as an exquisite example of an analytical science in which children can be fascinated. The presented teaching modules introduce children to mass spectrometry and give them the opportunity to experience a modern research laboratory. The modules are highly adaptable and can be applied to young children from the age of 6 to 14 y. In an interactive tour, the students explore three major scientific concepts related to mass spectrometry; the building blocks of matter, charged particle manipulation by electrostatic fields, and analyte identification by mass analysis. Also, the students carry out a mass spectrometry experiment and learn to interpret the resulting mass spectra. The multistage, inquiry-based tour contains flexible methods, which teach the students current-day research techniques and possible applications to real research topics. Besides the scientific concepts, laboratory safety and hygiene are stressed and the students are enthused for the analytical sciences by participating in “hands-on” work. The presented modules have repeatedly been successfully employed during laboratory open days. They are also found to be extremely suitable for (early) high school science classes during laboratory visit-focused field trips

COVID-19 outbreaks in aged-care facilities in Australia

Background: Aged-care facilities (ACF’s) provide unique challenges when implementing infection control methods for respiratory outbreaks such as COVID-19. Research on this highly vulnerable setting is lacking and there was no national reporting data of COVID-19 cases in ACFs in Australia early in the pandemic. We aimed to estimate the burden of aged-care worker (ACW) infections and outbreaks of COVID-19 in Australian aged-care. Methods: A line list of publicly available aged-care related COVID-19 reported cases from January 25 to June 10, 2020 was created and was enhanced by matching data extracted from media reports of aged-care related COVID-19 relevant outbreaks and reports. Rate ratios (RR) were used to predict risk of infection in ACW and aged-care residents, and were calculated independently, by comparing overall cases to ACW and aged-care residents' cases. Results: A total of 14 ACFs with COVID-19 cases were recorded by June 2020 nationwide, with a high case fatality rate (CFR) of 50% (n = 34) and 100% (n = 3) seen in two ACFs. Analysis on the resident risk found that the COVID-19 risk is 1.27 times higher (unadjusted RR 1.27 95% confidence interval [CI] 1.00 to1.61; P = 0.047) as compared with the risk of infection in the general population. In over 60% of cases identified in ACFs, the source of infection in the index case was unknown. A total of 28 deaths associated within ACFs were reported, accounting for 54.9% of total deaths in New South Wales and 26.9% of total deaths in Australia. Conclusions: This high-risk population requires additional prevention and control measures, such as routine testing of all staff and patients regardless of symptoms. Prompt isolation and quarantine as soon as a case is confirmed within a facility is essential

The association between acute flaccid myelitis (AFM) and enterovirus D68 (EV-D68) – what is the evidence for causation?

© 2018, European Centre for Disease Prevention and Control (ECDC). All rights reserved. Background: Enterovirus D68 (EV-D68) has historically been a sporadic disease, causing occasional small outbreaks of generally mild infection. In recent years, there has been evidence of an increase in EV-D68 infections globally. Large outbreaks of EV-D68, with thousands of cases, occurred in the United States, Canada and Europe in 2014. The outbreaks were associated temporally and geographically with an increase in clusters of acute flaccid myelitis (AFM). Aims: We aimed to evaluate a causal association between EV-D68 and AFM. ?Methods: Using data from the published and grey literature, we applied the Bradford Hill criteria, a set of nine principles applied to examine causality, to evaluate the relationship between EV-D68 and AFM. Based on available evidence, we defined the Bradford Hill Criteria as being not met, or met minimally, partially or fully. Results: Available evidence applied to EV-D68 and AFM showed that six of the Bradford Hill criteria were fully met and two were partially met. The criterion of biological gradient was minimally met. The incidence of EV-D68 infections is increasing worldwide. Phylogenetic epidemiology showed diversification from the original Fermon and Rhyne strains since the year 2000, with evolution of a genetically distinct outbreak strain, clade B1. Clade B1, but not older strains, is associated with AFM and is neuropathic in animal models. Conclusion: While more research is needed on dose–response relationship, application of the Bradford Hill criteria supported a causal relationship between EV-D68 and AFM

Estimated Mask Use and Temporal Relationship to COVID-19 Epidemiology of Black Lives Matter Protests in 12 Cities

Background: There is an increased risk of SARS-CoV-2 transmission during mass gatherings and a risk of asymptomatic infection. We aimed to estimate the use of masks during Black Lives Matter (BLM) protests and whether these protests increased the risk of COVID-19. Two reviewers screened 496 protest images for mask use, with high inter-rater reliability. Protest intensity, use of tear gas, government control measures, and testing rates were estimated in 12 cities. A correlation analysis was conducted to assess the potential effect of mask use and other measures, adjusting for testing rates, on COVID-19 epidemiology 4 weeks (two incubation periods) post-protests. Mask use ranged from 69 to 96% across protests. There was no increase in the incidence of COVID-19 post-protest in 11 cities. After adjusting for testing rates, only Miami, which involved use of tear gas and had high protest intensity, showed a clear increase in COVID-19 after one incubation period post-protest. No significant correlation was found between incidence and protest factors. Our study showed that protests in most cities studied did not increase COVID-19 incidence in 2020, and a high level of mask use was seen. The absence of an epidemic surge within two incubation periods of a protest is indicative that the protests did not have a major influence on epidemic activity, except in Miami. With the globally circulating highly transmissible Alpha, Delta, and Omicron variants, layered interventions such as mandated mask use, physical distancing, testing, and vaccination should be applied for mass gatherings in the future

The REDS score: a new scoring system to risk-stratify emergency department suspected sepsis: a derivation and validation study.

OBJECTIVE: To derive and validate a new clinical prediction rule to risk-stratify emergency department (ED) patients admitted with suspected sepsis. DESIGN: Retrospective prognostic study of prospectively collected data. SETTING: ED. PARTICIPANTS: Patients aged ≥18 years who met two Systemic Inflammatory Response Syndrome criteria or one Red Flag sepsis criteria on arrival, received intravenous antibiotics for a suspected infection and admitted. PRIMARY OUTCOME MEASURE: In-hospital all-cause mortality. METHOD: The data were divided into derivation and validation cohorts. The simplified-Mortality in Severe Sepsis in the ED score and quick-SOFA scores, refractory hypotension and lactate were collectively termed 'component scores' and cumulatively termed the 'Risk-stratification of ED suspected Sepsis (REDS) score'. Each patient in the derivation cohort received a score (0-3) for each component score. The REDS score ranged from 0 to 12. The component scores were subject to univariate and multivariate logistic regression analyses. The receiver operator characteristic (ROC) curves for the REDS and the components scores were constructed and their cut-off points identified. Scores above the cut-off points were deemed high-risk. The area under the ROC (AUROC) curves and sensitivity for mortality of the high-risk category of the REDS score and component scores were compared. The REDS score was internally validated. RESULTS: 2115 patients of whom 282 (13.3%) died in hospital. Derivation cohort: 1078 patients with 140 deaths (13%). The AUROC curve with 95% CI, cut-off point and sensitivity for mortality (95% CI) of the high-risk category of the REDS score were: derivation: 0.78 (0.75 to 0.80); ≥3; 85.0 (78 to 90.5). VALIDATION: 0.74 (0.71 to 0.76); ≥3; 84.5 (77.5 to 90.0). The AUROC curve and the sensitivity for mortality of the REDS score was better than that of the component scores. Specificity and mortality rates for REDS scores of ≥3, ≥5 and ≥7 were 54.8%, 88.8% and 96.9% and 21.8%, 36.0% and 49.1%, respectively. CONCLUSION: The REDS score is a simple and objective score to risk-stratify ED patients with suspected sepsis

Factors Associated with SARS-CoV-2 Attack Rates in Aged Care-A Meta-Analysis

Background: The coronavirus disease 2019 (COVID-19) pandemic has resulted in significant morbidity and mortality in aged-care facilities worldwide. The attention of infection control in aged care needs to shift towards the built environment, especially in relation to using the existing space to allow social distancing and isolation. Physical infrastructure of aged care facilities has been shown to present challenges to the implementation of isolation procedures. To explore the relationship of the physical layout of aged care facilities with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) attack rates among residents, a meta-Analysis was conducted. Methods: Using the Preferred Reporting Items for Systematic Reviews and Meta-Analysis Protocol (PRISMA-P), studies were identified from 5 databases using a registered search strategy with PROSPERO. Meta-Analysis for pooled attack rates of SARS-CoV-2 in residents and staff was conducted, with subgroup analysis for physical layout variables such as total number of beds, single rooms, number of floors, number of buildings in the facility, and staff per 100 beds. Results: We included 41 articles across 11 countries, reporting on 90 657 residents and 6521 staff in 757 facilities. The overall pooled attack rate was 42.0% among residents (95% CI, 38.0%-47.0%) and 21.7% in staff (95% CI, 15.0%-28.4%). Attack rates in residents were significantly higher in single-site facilities with standalone buildings than facilities with smaller, detached buildings. Staff-To-bed ratio significantly explains some of the heterogeneity of the attack rate between studies. Conclusions: The design of aged care facilities should be smaller in size, with adequate space for social distancing

Incidental Prostate Cancer in Transurethral Resection of the Prostate Specimens in the Modern Era

Objectives. To identify rates of incidentally detected prostate cancer in patients undergoing surgical management of benign prostatic hyperplasia (BPH). Materials and Methods. A retrospective review was performed on all transurethral resections of the prostate (TURP) regardless of technique from 2006 to 2011 at a single tertiary care institution. 793 men (ages 45–90) were identified by pathology specimen. Those with a known diagnosis of prostate cancer prior to TURP were excluded (n=22) from the analysis. Results. 760 patients had benign pathology; eleven (1.4%) patients were found to have prostate cancer. Grade of disease ranged from Gleason 3+3=6 to Gleason 3+4=7. Nine patients had cT1a disease and two had cT1b disease. Seven patients were managed by active surveillance with no further events, one patient underwent radiation, and three patients underwent radical prostatectomy. Conclusions. Our series demonstrates that 1.4% of patients were found to have prostate cancer, of these 0.5% required treatment. Given the low incidental prostate cancer detection rate, the value of pathologic review of TURP specimens may be limited depending on the patient population