The Off-Shell Nucleon-Nucleon Amplitude: Why it is Unmeasurable in Nucleon-Nucleon Bremsstrahlung

Nucleon-nucleon bremsstrahlung has long been considered a way of getting information about the off-shell nucleon-nucleon amplitude which would allow one to distinguish among nucleon-nucleon potentials based on their off-shell properties. There have been many calculations and many experiments devoted to this aim. We show here, in contrast to this standard view, that such off-shell amplitudes are not measurable as a matter of principle. This follows formally from the invariance of the S-matrix under transformations of the fields. This result is discussed here and illustrated via two simple models, one applying to spin zero, and one to spin one half, processes. The latter model is very closely related to phenomenological models which have been used to study off-shell effects at electromagnetic vertices.Comment: 6 pages, Latex, uses FBSsuppl.cls - Invited plenary talk at the Asia Pacific Conference on Few Body Problems in Physics, Noda/Kashiwa, Japan, August, 1999 - To be published in Few Body Systems Supp

COUROUPITA GUIANENSIS LEAF CALLUS EXTRACT MEDIATED SYNTHESIS AND ANTIBACTERIAL ACTIVITY OF SILVER NANOPARTICLES.

Objective: Synthesis of varied sized and morphologically distinct silver nanoparticles (AgNPs) using callus/callus extract, and their promising antibacterial and cytotoxicity was reported from very few plant systems. Here, we investigated silver nanoparticle synthetic potential of Couroupita guianensis leaf callus extract and their antibacterial activity.Methods: synthesis of callus mediated silver nanoparticles and characterisation of physical, chemical, and antibacterial activity of AgNPs.Results: Callus extract rapidly reduced silver ions and stabilized nanoparticles have displayed characteristic maximum UV absorbance at 410 nm. SEM and AFM images revealed their spherical morphology and size variation, which is ranged from 30.38 nm to 88.32 nm and were in small aggregates. Capping of AgNPs by the phenolic compounds and proteins revealed from FTIR spectral peaks. Silver nanoparticles displayed significantly high antimicrobial activity against both Gram positive and negative bacterial strains compared to silver ions and gentamicin. This enhanced antimicrobial activity of AgNPs may due their small size leading to efficient molecular contact with cell surface, and uptake and interaction with vital biomolecules.Conclusions: Stable AgNPs were synthesized through reduction and capping of silver ions by polyphenols and proteins present in callus extract. Theenhanced antimicrobial activity of AgNPs may due to their small size leading to efficient molecular contact with the cell surface, penetration, andinteraction, and inactivation of vital biomolecules.Â

Bacteria classification using Cyranose 320 electronic nose

Background An electronic nose (e-nose), the Cyrano Sciences' Cyranose 320, comprising an array of thirty-two polymer carbon black composite sensors has been used to identify six species of bacteria responsible for eye infections when present at a range of concentrations in saline solutions. Readings were taken from the headspace of the samples by manually introducing the portable e-nose system into a sterile glass containing a fixed volume of bacteria in suspension. Gathered data were a very complex mixture of different chemical compounds. Method Linear Principal Component Analysis (PCA) method was able to classify four classes of bacteria out of six classes though in reality other two classes were not better evident from PCA analysis and we got 74% classification accuracy from PCA. An innovative data clustering approach was investigated for these bacteria data by combining the 3-dimensional scatter plot, Fuzzy C Means (FCM) and Self Organizing Map (SOM) network. Using these three data clustering algorithms simultaneously better 'classification' of six eye bacteria classes were represented. Then three supervised classifiers, namely Multi Layer Perceptron (MLP), Probabilistic Neural network (PNN) and Radial basis function network (RBF), were used to classify the six bacteria classes. Results A [6 × 1] SOM network gave 96% accuracy for bacteria classification which was best accuracy. A comparative evaluation of the classifiers was conducted for this application. The best results suggest that we are able to predict six classes of bacteria with up to 98% accuracy with the application of the RBF network. Conclusion This type of bacteria data analysis and feature extraction is very difficult. But we can conclude that this combined use of three nonlinear methods can solve the feature extraction problem with very complex data and enhance the performance of Cyranose 320

Exercise cardiac MRI unmasks right ventricular dysfunction in acute hypoxia and chronic pulmonary arterial hypertension

Background - Coupling of right ventricular (RV) contractility to afterload is maintained at rest in the early stages of pulmonary arterial hypertension (PAH), but exercise may unmask depleted contractile reserves. We assessed whether elevated afterload reduces RV contractile reserve despite compensated resting function using non-invasive exercise imaging. Methods and Results - Fourteen patients with PAH (mean age 39.1 years, 10 females) and 34 healthy control subjects (mean age 35.6 years, 17 females) completed real-time cardiac magnetic resonance imaging during sub-maximal exercise breathing room-air. Controls were then also exercised during acute normobaric hypoxia (FiO2 12%). RV contractile reserve was assessed by the effect of exercise on ejection fraction (RVEF). In control subjects the increase in RVEF on exercise was less during hypoxia (P=0.017), but the response of left ventricular ejection fraction to exercise did not change. Patients with PAH had impaired RV reserve with half demonstrating a fall in RVEF on exercise despite comparable resting function to controls (PAH: rest 53.6{plus minus}4.3% vs exercise 51.4{plus minus}10.7%; controls: rest 57.1{plus minus}5.2% vs exercise 69.6{plus minus}6.1%, P<0.0001). In control subjects the increase in stroke volume index (SVi) on exercise was driven by reduced RV end-systolic volume, whereas PAH patients did not augment SVi, with increases in both end-diastolic and end-systolic volumes. From baseline hemodynamic and exercise capacity variables only VE/VCO2 was an independent predictor of RV functional reserve (P=0.021). Conclusions - Non-invasive cardiac imaging during exercise unmasks depleted RV contractile reserves in healthy adults under hypoxic conditions and PAH patients under normoxic conditions despite preserved ejection fraction

Pulmonary Hypertension in Patients with Chronic Fibrosing Idiopathic Interstitial Pneumonias

Background Pulmonary hypertension (PH) is a common finding in patients with chronic fibrosing idiopathic interstitial pneumonias (IIP). Little is known about the response to pulmonary vasodilator therapy in this patient population. COMPERA is an international registry that prospectively captures data from patients with various forms of PH receiving pulmonary vasodilator therapies. Methods We retrieved data from COMPERA to compare patient characteristics, treatment patterns, response to therapy and survival in newly diagnosed patients with idiopathic pulmonary arterial hypertension (IPAH) and PH associated with IIP (PH-IIP). Results Compared to patients with IPAH (n = 798), patients with PH-IIP (n = 151) were older and predominantly males. Patients with PH-IIP were treated predominantly with phosphodiesterase-5 inhibitors (88% at entry, 87% after 1 year). From baseline to the first follow-up visit, the median improvement in 6MWD was 30 m in patients with IPAH and 24.5 m in patients with PH-IIP (p = 0.457 for the difference between both groups). Improvements in NYHA functional class were observed in 22.4% and 29.5% of these patients, respectively (p = 0.179 for the difference between both groups). Survival rates were significantly worse in PH-IIP than in IPAH (3-year survival 34.0 versus 68.6%; p<0.001). Total lung capacity, NYHA class IV, and mixed-venous oxygen saturation were independent predictors of survival in patients with PH-IIP. Conclusions Patients with PH-IIP have a dismal prognosis. Our results suggest that pulmonary vasodilator therapy may be associated with short-term functional improvement in some of these patients but it is unclear whether this treatment affects survival

Implementation of Clinical Assisted Reproduction Technologies for the Improvement of in vitro Production of Porcine Embryos: From IVF Clinic to Pig Farm

The world population is predicted to rise from 7 to 9 billion in the next 30 years, and per capita, meat consumption is predicted to increase by 20% at this time. This places a demand on current food producers globally (particularly pork producers as 40% of global meat consumption is pig meat) that is not sustainable unless sufficient innovations are implemented. Livestock production also contributes 18% of the earth's global warming, and this is also set to increase. Solving these problems necessitates producing increased amounts of meat from fewer animals in a shorter amount of time. UK companies lead the world in developing livestock with superior genetic traits that drive increased productivity through greater feed conversion efficiencies, improved disease resistance, and higher fertility. Disseminating and applying these advances into herds around the world, however, presents unique problems. That is, for female line genetics, (male line genetics can be disseminated via sperm samples) producers are left with no other choice but to transport live animals for establishing nucleus farms overseas (e.g. In East and Southeast Asia). This can be expensive; energy is consuming, environmentally unfriendly, and carries important animal welfare and disease transmission concerns. One possible solution is to preserve and transports superior genetics in the form of preimplantation embryos (preferably pre-genotyped for sex and desirable production trait). To date, however, pig IVF and production (henceforth termed "IVP") has not been successfully implemented. The purpose of this thesis was to contribute to an ongoing effort to improve pig IVP through fundamental studies of porcine reproduction. Specifically, the work focussed on boar sperm production and on the human system (IVF clinic data) to provide clues as to the likely effects of embryo biopsy - an essential precursor to genotyping a preimplantation embryo as follows: The first aim was to produce a working classification system for boar sperm morphology and test the hypothesis that there are differences between high quality and poor quality boars. Some hitherto unreported features of sperm morphology were established as significantly different in the poor-quality boar seen group. The second was to assess the effects of stimulants (e.g. caffeine and adenosine) on capacitation and fertilization rates and ask whether there was a correlation between capacitation and fertilization. Here, the utility of caffeine was established, and correlations were observed between sperm morphology and capacitation rates. The third aim involved establishing whether novel markers of correct sperm chromatin packaging (CMA3 stain, nuclear organization, sperm aneuploidy) were indicative of reduced fertility in boars. Here a significant association between the poor-quality boars and level of CMA3 staining was observed indicating that this test may be implemented in the future as a means of identifying poor quality boars. No significant association with nuclear organization nor sperm aneuploidy was observed, however. Finally, attention turned to human IVF data to test the hypothesis that embryo biopsy adversely affected subsequent embryo development. Using state of the art time lapse imaging no evidence was found to indicate that biopsy had an adverse effect in humans suggesting that, if performed correctly, this may also be the case in pigs. Taken together, the results provide evidence for the potential of significant advances in pig IVP by adapting protocols already commonplace in humans. Indeed, during the project, and in part because of it, IVP success rates in the laboratory increased dramatically

COVID-19 Vaccine Acceptance and Hesitancy among Ethnic Minorities in Hong Kong

Ethnic minorities account for 8% of the Hong Kong population, most are Filipino and Indonesian domestic helpers taking care of children and the elderly. To understand the COVID-19 vaccination rates and factors associated with vaccine acceptance of ethnic minorities, we performed a cross-sectional questionnaire study recruiting Hong Kong ethnic minorities aged ≥18 years between 1 July and 18 July 2021 in public areas. Demographics, knowledge about COVID-19, vaccination status, intention and reasons to receive the vaccine, and planning to be re-vaccinated were analyzed. Continuous and categorical variables were compared using unpaired t-test and Chi-square test, respectively. Potential confounders were adjusted using multiple logistic regression. 2,012 ethnic minorities participated, with a mean age of 39 years, of which 97.6% were female, 79.5% were Filipino, and 17.5% were Indonesian. 80.6% of participants were categorized as vaccine acceptance, and 69.2% were willing to be re-vaccinated. There were significantly more Filipinos than Indonesians in the vaccine acceptance group (p < .001). Subjects in the vaccine acceptance group were more likely to have higher education (p < .001), a higher COVID-19 knowledge score (p < .001), received information from the Government website (p = .003) and not from their friends or family members (p = .02), and were more confident in judging the accuracy of the information (p < .001). Logistic regression showed the mean knowledge score (β = 3.07, p < .001) and receiving information from official Government websites (adjusted OR = 1.37, p = .03) were significant factors that positively influenced vaccine acceptance. The Hong Kong Government should improve COVID-19 vaccination acceptance among ethnic minorities through public education using official channels