Lifetime measurements of certain excited states of lead isotopes

As described in Chapter IV, the method of lifetime measurement presented in this thesis is applicable to the El transitions of energy % 1 Mev in medium and high Z K-capture nuclei. In such cases, nuclear and atomic level lifetimes are of comparable order and hence the nuclear transitions of this type are expected to be associated with K X -ray satellites. The fact that the nuclear level lifetime can be expressed in terms of atomic level life- times permits an estimation of the former as already dis- cussed. That the satellite emission does occur has been experimentally demonstrated by the observed differences in the intensity reductions R and R' on the one hand, and R2 and R2' on the other, for two different absorbers. The intensity reductions suggest that the K X -ray satellites are certainly very close to the K -edge of the absorbers used in the experiment. The mean energy of the satellite group according to the experimental values of intensity reductions for the iridium absorber is 76.03 keV whereas for osmium it lies in the range 75.8 - 80.05 keV. These values agree well with the Wentzel- Druyvestyn type of estimate for the lead KK satellite energy (N76 keV) calculated by Slater's method(il° The experimental values of Ks = 5.97 gm,/cm.2 and 8.53 gm. /cm. 2 for iridium and osmium absorbers respectively are also within the expected limits 2.2 - 9.4 and 2.3 - 9.8 for the two absorbers. The relatively small intensity reduction observed in the case of osmium is mainly because the Ka, component of the lead K X -rays lies on the higher energy side of the osmium K edge. While calculating the satellite intensity (S) from equation (4.28), it was found that the value of S depended very sensitively on the difference between Rl and Rlt or R2 and R2t. The relatively large error in estimation of S from osmium measurements as compared with that from iridium results is in accordance with this observation.Since the osmium absorbers were made from a powder of ammonium chlorosmanate, any uncertainty in its thickness or uniformity might also have contributed to the results. It was, however, not possible to take into account the effects of these contributions.. For these reasons, more reliance may be reposed on the results of iridium than those of osmium measurements. The osmium results can then be regarded as a corroborative piece of evidence in favour of the iridium results. The general contribution of the X -ray Compton background and of the Compton back- ground in the neighbourhood of the conversion line to the coincidences observed, from which the satellite intensity was estimated has already been discussed. As explained in Section 5,11, the procedure adopted for recording coincidences was meant to eliminate the contributions from such effects. Another possibility of some contribution to the observed satellite intensity arises from the theory of Primakoff and Porter( 110) already referred to in Section 3.5.4. According to these authors, when a nucleus decays by orbital electron capture, there is a definite probability for the simultaneous excitation of a non -captured orbital electron as a consequence of sudden charge alteration. The probability per K capture for the production of a double hole in the K shell by this process is, however, very small (P(KK)~3/16Z(2)). The only nucleus in which such a process has been observed is Ge71 l for which the theory predicts a value of 10 -4 for P. For lead, P(KK) will be ~ 10(-5), and hence even if such an effect exists, its contribution to the satellite in- tensity will be obviously negligible.The mean life of the 1720 keV El transition as obtained in the present experiment from the iridium measurements is 15 x 10 -16 seconds. The single particle estimate for this transition gives Z = .54 x l0 -16 seconds. The observed value, therefore, corresponds to a retardation of about 27. As mentioned in Section 1.5, two values for the lifetime of this transition are already available. Brunner et al. have reported a retardation of about 50, while Wu et al. obtained a retardation of about 600. None of these authors have quoted errors on the results reported. But since both these results were obtained by observations on monoenergetic positrons, they are expected to involve huge uncertainties. It has already been remarked in Section 2.7 that the estimation of lifetime by this method relies on the theoretical value of monoenergetic K- positron emission coefficient (ae+) for which the results of Lombard and Rys(59) differ from those of Sliv by a factor of 2. Besides, the estimation of K- positron intensity in the presence of a large background also introduces a considerable error. The X -ray satellite method, on the other hand, used in the present experiment does not involve such uncertainties. The quantities involved in the calculations are either experimentally known or can be computed with a reasonable degree of accuracy. The value of lifetime obtained by this method is, therefore, expected to be better than that given by the method of monoenergetic positron emission.The results of the present experiment seem to favour the value reported by Brunner et al. rather than the value obtained by Wu et al. In order to see whether the observed retardation of the 1720 keV El transition in Pb206 is reasonable, reference may be made to section 1.5 where the retardation of El transitions has been briefly discussed. The relatively small retardation obtained in the present experiment rules out any possibility of K- forbiddenness as the cause. This statement is supported by Rusinov's empirical rule (eq. (1.30) , Chapter I) , regarding the K -forbiddenness of El transitions in even - even nuclei. Moreover, the nucleus 82(Pb(206)) with only two neutrons short of doubly closed shell is less likely to be described in terms of the Nilsson model. The unusually high first excited state of Pb(208) and the slow electric quadrupole transition rates in other lead isotopes provide strong evidence for the rigidity of the core and a weak surface coupling in these nuclei. The works of Alburger and Pryce( 118) , True and Ford(119) and Kearsley( 120) have shown that a very successful description of the energy levels in Pb206 up to about 3 Mev can be obtained from simple shell model considerations where the interaction between the two neutron holes is taken as a perturbation and the effects of nuclear deformations are ignored. Thus, most of the energy levels shown in the Bi206 decay scheme (Fig. 33) are accounted for in terms of simple two hole neutron configurations. The upper two levels (3403 and 3280 keV), however, have been ascribed by True and Ford to the core excitation formed, possibly by proton configurations (S1 ) 1 h/ and (d3/2) -h 9/2 respectively. Such an assignment involves a change in the orbitals of three nucleons (2 neutrons and 1 proton) which is very unlikely because many particle transitions are generally expected to be slower compared with single - particle transitions by several orders of magnitude. The result of the present experiment seems to strengthen the confidence in the shell model description of the Pb206 nucleus. An application of the method described in this work to the lifetime measurement of the 1863 keV El transition in Bi(205) may further strengthen this contention

A Study On Risk Factors of Relapses of Nephrotic Syndrome Among Pediatric Patients at a Tertiary Care Center of Bihar

Introduction: Nephrotic syndrome (NS) is 15 times more common in children than in adults. NS affects13/100,000 children<16 years of age . Two-thirds of childhood NS present before the age of 6 years. Therefore, we planned this study with an objective to identify the risk factors for FR in childhood steroid sensitive NS (SSNS). Methodology: A prospective study was conducted by the Department of Pediatrics, Nalanda Medical College &Hospital, Bihar, between February 2020 to January 2021. Cases with the first episode of idiopathic SSNS in the age group of 9 months - 12 years, who followed up for at least 12 months were enrolled in the study. NS was diagnosed in accordance with standard criteria. Results: A total of 100 children with NS were included in the current study based on inclusion criteria during the study period. There was a male preponderance among the study participants. Incidence of infection and hypertension was 34% and 37%, respectively. Incidence of FR was high in 1-8 years age group. The incidence of FR was less in males than in females; but it was not significant. Majority of the children with IFR group responded to steroid therapy in <2 weeks, while the most children with FR showed response after 3-4 weeks. Conclusion: Relapse within first 6 months, associated infections and hypertension were the factors significantly associated with FRs in childhood SSNS. These factors should be kept in mind and should be well documented at the time of initial presentation of NS for the long-term management

Choice of antibiotic for empirical therapy of acute cystitis in a setting of high antimicrobial resistance

Background: A high prevalence of antimicrobial resistance among urinary isolates in the Garhwal region of Uttaranchal. Aims: To identify the most appropriate antibiotic for empirical treatment of community-acquired acute cystitis on the basis of local antimicrobial sensitivity profile. Settings and Design: A prospective clinico-microbiological study including all clinically diagnosed patients with community acquired acute cystitis attending a tertiary care teaching hospital over a period of three years. Methods and Material: Clean-catch midstream urine specimens, from 524 non-pregnant women with community-acquired acute cystitis, were subjected to semi-quantitative culture and antibiotic susceptibility by the Kirby- Bauer disc diffusion method. A survey was also conducted on 30 randomly selected local practitioners, to know the prevalent prescribing habits in this condition. Statistical Analysis: The difference between the susceptibility rates of E.coli isolates to Nitrofurantoin and the other commonly prescribed antibiotics was analysed by applying the z test for proportion. Results: 354 (67.5%) specimens yielded significant growth of E.coli > 35% of the urinary E.coli isolates were resistant to the fluoroquinolones, which were found to be the most commonly used empirical antibiotics in acute cystitis. Resistance was minimum against Nitrofurantoin (9.3%, 33) and Amikacin (11.0%,39).> 80% of the fluoroquinolone-resistant strains were found to be sensitive to Nitrofurantoin. Conclusion: The best in vitro susceptibility profile in our study has been shown by Nitrofurantoin and a significantly high proportion of the urinary E.coli isolates have already developed resistance to the currently prescribed empirical antibiotics, viz. the fluoroquinolones. In view of these in vitro susceptibility patterns, a transition in empirical therapy appears imminent

Electrolyte changes in neonates ≥ 35 weeks gestation receiving phototherapy for neonatal jaundice

Introduction: Neonatal hyperbilirubinemia is a common clinical problem encountered during the neonatal period. High serum bilirubin levels can be toxic for central nervous system development and may cause behavioural and neurological impairment (Kernicterus) even in term newborns. Phototherapy is one of the most effective ways available in preventing the neurotoxic complications of indirect hyperbilirubinemia. Methodology: It is a prospective interventional study. Ethical clearance was obtained from institutional ethical committee. Neonates who were born or admitted to a tertiary care centre from September 2020 to August 2021, receiving Light Emitting Diode(LED) phototherapy for unconjugated hyperbilirubinemia after 24 hrs of life without any co-morbidities were involved in the study. Results: A total of 100 neonates were involved of which 55 were males and 45 were females (Figure 1). The mean sodium, potassium and calcium level before therapy were 147.6±5.2, 4.9±0.3, and 9.6±0.6 respectively. After phototherapy the mean sodium, potassium and calcium level were 142.3±5.6, 4.1±0.5 and 8.5±0.7 respectively. There was significant difference in sodium level before and after phototherapy with p-value= 0.02. But, in level of Potassium there But, in level of Potassium there was no significant difference (p=0.31) due to phototherapy before and after. Before phototherapy none of baby had hyponatremia while after phototherapy 8.7% cases had hyponatremia. Similarly, hypocalcaemic was present in 4.2% cases before phototherapy and after phototherapy 28.3% cases had hypocalcaemic which was found significant statistically. Conclusion: Neonatal hyperbilirubinemia can easily pickup on clinical examination however require quick and on the spot treatment. If not treated properly, it leads to many complications. Currently the best treatment option for jaundice is photo therapy

Performance, energy loss, and degradation prediction of roof-integrated crystalline solar PV system installed in Northern India

This article predicts the performance, energy loss, and degradation of a 200 kW roof-integrated crystalline photovoltaic (PV) system installed at IRB Complex-5, Chandigarh in the Northern part of India. PVsyst simulation tool is used for predicting the energy generation, and energy loss. Analysis of the energy generation and various input parameters are carried out for evaluating the capacity factor (CF), performance ratio (PR), and efficiencies. For a detailed analysis of the energy losses, a three-stage approach (sunlight reaching onto the PV array, sunlight into DC electricity conversion, and DC to AC electricity conversion) is used. The light-induced degradation (LID), which is possible in the PV modules in the second stage (sunlight into DC electricity conversion) is predicted using the PVsyst simulation modeling. Apart from this, the possible degradation rate (DR) in the crystalline PV systems is considered based on the All-India survey of PV module reliability reports. The predicted results show that 292954 kWh of energy generation is possible on an annual basis from the planned PV system. The system is estimated to operate with a yearly CF, PR, and energy losses as 16.72%, 77.27%, and −26.5% respectively. The estimated DR of the PV system would lie between −0.6 to −5%/year, and the possible LID is −2.5%/year. Finally, the energy losses due to LID, and DR are predicted as −8109.99 kWh/year, and −1757.724 to −14647.7 kWh/year respectively. Keywords: Crystalline solar, Energy loss, Light-induced degradation (LID), Degradation rate, Roof-integrated PV, Performance prediction, PVsyst, Model solar cit

Prospective observational cohort study on grading the severity of postoperative complications in global surgery research

Background The Clavien–Dindo classification is perhaps the most widely used approach for reporting postoperative complications in clinical trials. This system classifies complication severity by the treatment provided. However, it is unclear whether the Clavien–Dindo system can be used internationally in studies across differing healthcare systems in high- (HICs) and low- and middle-income countries (LMICs). Methods This was a secondary analysis of the International Surgical Outcomes Study (ISOS), a prospective observational cohort study of elective surgery in adults. Data collection occurred over a 7-day period. Severity of complications was graded using Clavien–Dindo and the simpler ISOS grading (mild, moderate or severe, based on guided investigator judgement). Severity grading was compared using the intraclass correlation coefficient (ICC). Data are presented as frequencies and ICC values (with 95 per cent c.i.). The analysis was stratified by income status of the country, comparing HICs with LMICs. Results A total of 44 814 patients were recruited from 474 hospitals in 27 countries (19 HICs and 8 LMICs). Some 7508 patients (16·8 per cent) experienced at least one postoperative complication, equivalent to 11 664 complications in total. Using the ISOS classification, 5504 of 11 664 complications (47·2 per cent) were graded as mild, 4244 (36·4 per cent) as moderate and 1916 (16·4 per cent) as severe. Using Clavien–Dindo, 6781 of 11 664 complications (58·1 per cent) were graded as I or II, 1740 (14·9 per cent) as III, 2408 (20·6 per cent) as IV and 735 (6·3 per cent) as V. Agreement between classification systems was poor overall (ICC 0·41, 95 per cent c.i. 0·20 to 0·55), and in LMICs (ICC 0·23, 0·05 to 0·38) and HICs (ICC 0·46, 0·25 to 0·59). Conclusion Caution is recommended when using a treatment approach to grade complications in global surgery studies, as this may introduce bias unintentionally

The surgical safety checklist and patient outcomes after surgery: a prospective observational cohort study, systematic review and meta-analysis

© 2017 British Journal of Anaesthesia Background: The surgical safety checklist is widely used to improve the quality of perioperative care. However, clinicians continue to debate the clinical effectiveness of this tool. Methods: Prospective analysis of data from the International Surgical Outcomes Study (ISOS), an international observational study of elective in-patient surgery, accompanied by a systematic review and meta-analysis of published literature. The exposure was surgical safety checklist use. The primary outcome was in-hospital mortality and the secondary outcome was postoperative complications. In the ISOS cohort, a multivariable multi-level generalized linear model was used to test associations. To further contextualise these findings, we included the results from the ISOS cohort in a meta-analysis. Results are reported as odds ratios (OR) with 95% confidence intervals. Results: We included 44 814 patients from 497 hospitals in 27 countries in the ISOS analysis. There were 40 245 (89.8%) patients exposed to the checklist, whilst 7508 (16.8%) sustained ≥1 postoperative complications and 207 (0.5%) died before hospital discharge. Checklist exposure was associated with reduced mortality [odds ratio (OR) 0.49 (0.32–0.77); P\u3c0.01], but no difference in complication rates [OR 1.02 (0.88–1.19); P=0.75]. In a systematic review, we screened 3732 records and identified 11 eligible studies of 453 292 patients including the ISOS cohort. Checklist exposure was associated with both reduced postoperative mortality [OR 0.75 (0.62–0.92); P\u3c0.01; I2=87%] and reduced complication rates [OR 0.73 (0.61–0.88); P\u3c0.01; I2=89%). Conclusions: Patients exposed to a surgical safety checklist experience better postoperative outcomes, but this could simply reflect wider quality of care in hospitals where checklist use is routine