DETC2008-49759 CONSTRAINT REDUNDANCY IN MOBILITY OF PARALLEL MANIPULATORS

Abstract: This paper presents a systematic approach to obtain the degrees of freedom (DOF) of the platforms of parallel manipulators. The paper begins with general Kutzbach criterion for mobility. With simple mathematical transformations this criterion is modified to incorporate number of parallel legs used in the parallel platform-type mechanism and the number of joints in the legs. The theory of screws is used to study the freedom of the joints in the individual legs and the mobility of the platform. It is established that the general Kutzbach mobility criterion does not cater for situations where the freedom screws (or constraint screws) of the joints in a leg become dependent on the freedom screws (or constraint screws) of one or more of the other legs; thus, altering the mobility of the platform. The general modified Kutzbach mobility formula is further modified to resolve the problem of redundant constraints. The paper then provides a systematic approach towards the number synthesis of parallel platform-type mechanims. The paper includes three examples of such mechanisms analyzed by this approach. Results agree with the existing studies carried out on the mechanism used in the examples. A numerical example of a three-degree-of-freedom parallel manipulator with three legs is used to show the enumeration of all possible parallel manipulators. This includes cases with and without redundant constraints

The Evolution of Contractual Terms in Sovereign Bonds

In reaction to defaults on sovereign debt contracts, issuers and creditors have strengthened the terms in sovereign debt contracts that enable creditors to enforce their debts judicially and that enable sovereigns to restructure their debts. These apparently contradictory approaches reflect attempts to solve an incomplete contracting problem in which debtors need to be forced to repay debts in good states of the world; debtors need to be granted partial relief from debt payments in bad states; debtors may attempt to exploit divisions among creditors in order to opportunistically reduce their debt burden; debtors may engage in excessively risky activities using creditors\u27 money; and debtors and creditors may attempt to externalize costs on the taxpayers of other coun­tries. We support this argument with a statistical study of the development of sovereign bond terms from 1960 to the present

Epidemiology of Stroke in the MENA Region: A Systematic Review.

Introduction: Stroke is a major burden on the health system due to high fatality and major disability in survivors. Whilst Stroke incidence has declined in the developed world, it continues to increase in developing nations, including the MENA (Middle East and North Africa) region. This may reflect different risk factors and strategies to treat and manage patients prior to and after Stroke. Methods: We have conducted a systematic review of the prevalence, incidence and mortality of Stroke in the 23 countries of MENA region following the PRISMA guidelines. Results: 8,874 published papers were retrieved through both PubMed and Embase. Of those, 38 studies were found to be eligible for inclusion in this review. Only thirteen countries in the MENA region had data points for the critical stroke parameters. Of these qualified studies, 14 were prospective, population-based studies. In the age-adjusted studies, incidence ranged widely between 16/100,000 in a prospective population-based in Iran to 162/100,000 in Libya. Age-adjusted prevalence was available only from Tunisia at 184/100,000. Mortality for all strokes from the eight countries reporting this measure found the 30 day-case fatality ranged from 9.3% in Qatar to 30% in Pakistan. Most stroke studies in the MENA region were small sized, hospital-based, lacked confidence intervals and did not provide prevalence and mortality figures. Conclusion: National policymakers, public health and medical care stakeholders need more reliable epidemiologic studies on Stroke from the MENA region to plan more effective preventive and therapeutic strategies

Polypyrrole-Fe[sub]2O[sub]3 nanocomposites with high dielectric constant : in situ chemical polymerisation

Novel nanocomposites of polypyrrole (PPy) dispersed with iron oxide (Fe2O3) particles have been synthesised by in-situ chemical oxidative polymerisation of pyrrole in the presence of ammonium persulfate (APS) as an oxidising agent. The concentration of Fe2O3 was varied between 10-50wt% of PPy. The simultaneous polymerisation of pyrrole and oxide addition led to the complete synthesis of nanocomposites. A maximum dielectric constant of ~28500 was observed at 20wt% of Fe2O3. The nanocomposites were characterised by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). XRD analysis confirmed the structure and crystallinity of the nanocomposites, and a strong interaction between PPy and the Fe2O3 nanoparticles was observed by FTIR technique. SEM and TEM images showed that Fe2O3 particles had been coated with PPy by establishing a network during the polymerisation process. The values of dielectric constant were obtained from capacitance measurements. The value of dielectric constant for nanocomposites with 20wt% of Fe2O3 was observed to be almost 12 times that of the pure PPy matrix. The high value of dielectric constant indicated a high packing density of Fe2O3 particles in the PPy matrix. These nanocomposites have potential applications in electronic or biomedical devices

Serology based disease status of Pakistani population infected with Hepatitis B virus

<p>Abstract</p> <p>Background</p> <p>The infection rate of hepatitis B virus is continuously increasing in Pakistan. Therefore, a comprehensive study of epidemiological data is the need of time.</p> <p>Methods</p> <p>A total of 1300 individuals were screened for HBV infection markers including HBsAg, anti-HBsAg, HBeAg and anti-HBcAg. The association of these disease indicators was compared with patients' epidemiological characteristics like age, socio-economic status and residential area to analyze and find out the possible correlation among these variables and the patients disease status.</p> <p>Results</p> <p>52 (4%) individuals were found positive for HBsAg with mean age 23.5 ± 3.7 years. 9.30%, 33.47% and 12% individuals had HBeAg, antibodies for HBsAg, and antibodies for HBcAg respectively. HBsAg seropositivity rate was significantly associated (<it>p </it>= 0.03) with the residing locality indicating high infection in rural areas. Antibodies titer against HBsAg decreased with the increasing age reflecting an inverse correlation.</p> <p>Conclusion</p> <p>Our results indicate high prevalence rate of Hepatitis B virus infection and nationwide vaccination campaigns along with public awareness and educational programs are needed to be practiced urgently.</p

Corneal nerve loss as a surrogate marker for poor pial collaterals in patients with acute ischemic stroke

In patients with acute ischemic stroke, pial collaterals play a key role in limiting neurological disability by maintaining blood flow to ischemic penumbra. We hypothesized that patient with poor pial collaterals will have greater corneal nerve and endothelial cell abnormalities. In a cross-sectional study, 35 patients with acute ischemic stroke secondary to middle cerebral artery (MCA) occlusion with poor (n = 12) and moderate-good (n = 23) pial collaterals and 35 healthy controls underwent corneal confocal microscopy and quantification of corneal nerve and endothelial cell morphology. In patients with MCA stroke, corneal nerve fibre length (CNFL) (P < 0.001), corneal nerve fibre density (CNFD) (P = 0.025) and corneal nerve branch density (CNBD) (P = 0.002) were lower compared to controls. Age, BMI, cholesterol, triglycerides, HDL, LDL, systolic blood pressure, NIHSS and endothelial cell parameters did not differ but mRS was higher (p = 0.023) and CNFL (p = 0.026) and CNBD (p = 0.044) were lower in patients with poor compared to moderate-good collaterals. CNFL and CNBD distinguished subjects with poor from moderate-good pial collaterals with an AUC of 72% (95% CI 53–92%) and 71% (95% CI 53–90%), respectively. Corneal nerve loss is greater in patients with poor compared to moderate-good pial collaterals and may act as a surrogate marker for pial collateral status in patients with ischemic stroke

FOXO3 gene hypermethylation and its marked downregulation in breast cancer cases: A study on female patients

BackgroundFOXO3, a member of the FOX transcription factor family, is frequently described as being deregulated in cancer. Additionally, notable role of FOXO3 can be easily recognized in the process of ageing and survival. Even though various studies have been done to acknowledge the tumour-suppressive or oncogenic role of FOXO3 in cancer, still there exist a lack of understanding in terms of cancer prognosis and treatment. Therefore, to provide better insight, our study aims to evaluate the role and function of FOXO3 in breast cancer in Indian female patients. We examined the FOXO3 expression levels in breast cancer samples by analyzing mRNA and protein expression along with its clinicopathological parameters.ResultsA total of 127 cases of breast cancer with equal normal cases (n=127) were assessed with methylation (MS-PCR), Immunohistochemistry (IHC), mRNA expression using Real-time PCR was analysed and 66.14% cases at mRNA level were found to be downregulated, while 81.10% of cases had little or very little protein expression. Our data state, the promoter hypermethylation of the FOXO3 gene and the downregulated protein expression are significantly correlated (p=0.0004). Additionally, we found a significant correlation between the level of FOXO3 mRNA with ER (p=0.04) and status of lymph node (p=0.01) along with this.ConclusionData suggests the prognostic significance and the tumour-suppressive role of FOXO3 in breast cancer cases studied in India. However, there is a need for the extended research targeting FOXO3 to measure its clinical potential and develop well-defined therapeutic strategies

Utilisation of an operative difficulty grading scale for laparoscopic cholecystectomy

Background A reliable system for grading operative difficulty of laparoscopic cholecystectomy would standardise description of findings and reporting of outcomes. The aim of this study was to validate a difficulty grading system (Nassar scale), testing its applicability and consistency in two large prospective datasets. Methods Patient and disease-related variables and 30-day outcomes were identified in two prospective cholecystectomy databases: the multi-centre prospective cohort of 8820 patients from the recent CholeS Study and the single-surgeon series containing 4089 patients. Operative data and patient outcomes were correlated with Nassar operative difficultly scale, using Kendall’s tau for dichotomous variables, or Jonckheere–Terpstra tests for continuous variables. A ROC curve analysis was performed, to quantify the predictive accuracy of the scale for each outcome, with continuous outcomes dichotomised, prior to analysis. Results A higher operative difficulty grade was consistently associated with worse outcomes for the patients in both the reference and CholeS cohorts. The median length of stay increased from 0 to 4 days, and the 30-day complication rate from 7.6 to 24.4% as the difficulty grade increased from 1 to 4/5 (both p < 0.001). In the CholeS cohort, a higher difficulty grade was found to be most strongly associated with conversion to open and 30-day mortality (AUROC = 0.903, 0.822, respectively). On multivariable analysis, the Nassar operative difficultly scale was found to be a significant independent predictor of operative duration, conversion to open surgery, 30-day complications and 30-day reintervention (all p < 0.001). Conclusion We have shown that an operative difficulty scale can standardise the description of operative findings by multiple grades of surgeons to facilitate audit, training assessment and research. It provides a tool for reporting operative findings, disease severity and technical difficulty and can be utilised in future research to reliably compare outcomes according to case mix and intra-operative difficulty

Need for recovery amongst emergency physicians in the UK and Ireland: A cross-sectional survey

OBJECTIVES: To determine the need for recovery (NFR) among emergency physicians and to identify demographic and occupational characteristics associated with higher NFR scores. DESIGN: Cross-sectional electronic survey. SETTING: Emergency departments (EDs) (n=112) in the UK and Ireland. PARTICIPANTS: Emergency physicians, defined as any registered physician working principally within the ED, responding between June and July 2019. MAIN OUTCOME MEASURE: NFR Scale, an 11-item self-administered questionnaire that assesses how work demands affect intershift recovery. RESULTS: The median NFR Score for all 4247 eligible, consented participants with a valid NFR Score was 70.0 (95% CI: 65.5 to 74.5), with an IQR of 45.5-90.0. A linear regression model indicated statistically significant associations between gender, health conditions, type of ED, clinical grade, access to annual and study leave, and time spent working out-of-hours. Groups including male physicians, consultants, general practitioners (GPs) within the ED, those working in paediatric EDs and those with no long-term health condition or disability had a lower NFR Score. After adjusting for these characteristics, the NFR Score increased by 3.7 (95% CI: 0.3 to 7.1) and 6.43 (95% CI: 2.0 to 10.8) for those with difficulty accessing annual and study leave, respectively. Increased percentage of out-of-hours work increased NFR Score almost linearly: 26%-50% out-of-hours work=5.7 (95% CI: 3.1 to 8.4); 51%-75% out-of-hours work=10.3 (95% CI: 7.6 to 13.0); 76%-100% out-of-hours work=14.5 (95% CI: 11.0 to 17.9). CONCLUSION: Higher NFR scores were observed among emergency physicians than reported in any other profession or population to date. While out-of-hours working is unavoidable, the linear relationship observed suggests that any reduction may result in NFR improvement. Evidence-based strategies to improve well-being such as proportional out-of-hours working and improved access to annual and study leave should be carefully considered and implemented where feasible

Outcomes of obstructed abdominal wall hernia: results from the UK national small bowel obstruction audit

Background: Abdominal wall hernia is a common surgical condition. Patients may present in an emergency with bowel obstruction, incarceration or strangulation. Small bowel obstruction (SBO) is a serious surgical condition associated with significant morbidity. The aim of this study was to describe current management and outcomes of patients with obstructed hernia in the UK as identified in the National Audit of Small Bowel Obstruction (NASBO). Methods: NASBO collated data on adults treated for SBO at 131 UK hospitals between January and March 2017. Those with obstruction due to abdominal wall hernia were included in this study. Demographics, co-morbidity, imaging, operative treatment, and in-hospital outcomes were recorded. Modelling for factors associated with mortality and complications was undertaken using Cox proportional hazards and multivariable regression modelling. Results: NASBO included 2341 patients, of whom 415 (17·7 per cent) had SBO due to hernia. Surgery was performed in 312 (75·2 per cent) of the 415 patients; small bowel resection was required in 198 (63·5 per cent) of these operations. Non-operative management was reported in 35 (54 per cent) of 65 patients with a parastomal hernia and in 34 (32·1 per cent) of 106 patients with an incisional hernia. The in-hospital mortality rate was 9·4 per cent (39 of 415), and was highest in patients with a groin hernia (11·1 per cent, 17 of 153). Complications were common, including lower respiratory tract infection in 16·3 per cent of patients with a groin hernia. Increased age was associated with an increased risk of death (hazard ratio 1·05, 95 per cent c.i. 1·01 to 1·10; P = 0·009) and complications (odds ratio 1·05, 95 per cent c.i. 1·02 to 1·09; P = 0·001). Conclusion: NASBO has highlighted poor outcomes for patients with SBO due to hernia, highlighting the need for quality improvement initiatives in this group