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Background although new mothers are aware of the benefits of breastfeeding, many of them stop breastfeeding early in the postpartum period. Maternal psychosocial factors have been shown to contribute to early breastfeeding cessation. According to Self-Determination Theory (SDT) maternal self-determination is an indispensable factor in studying motivation to breastfeed. There are no validated instruments to assess maternal breastfeeding motivation and self-determination. Objective our aim was to develop and assess the psychometric properties of the Breastfeeding Self -Regulation Questionnaire (BSRQ) for Chinese pregnant women in Hong Kong. Method we reviewed the literature and devised items for a preliminary version of the questionnaire. Thirty-five context-specific items in English were generated. We translated the items into Chinese and then back translated them into English following established translation procedures. We employed exploratory factor analysis (EFA) and confirmatory factor analysis (CFA) to assess the structure of the questionnaire. Predictive validity was measured by assessing the relationship between the BRSQ score and actual duration of breastfeeding. Findings we recruited 591 participants from three publicly funded antenatal clinics. Of the 35 items in the preliminary BSRQ, 22 were retained by EFA. CFA revealed that there were 5 factors including intrinsic, identified, integrated, introjected and external regulation. The goodness of fit of the CFA model was adequate. The Cronbach's alpha of the BSRQ was 0.86. For every one point increase in the BSRQ score, participants had 15% higher odds of any breastfeeding (OR=1.15, 95%CI 1.07–1.23) and 9% higher odds of exclusive breastfeeding (OR=1.09, 95%CI 1.02–1.17) at 6 weeks postpartum. Conclusion the Chinese version of the BSRQ was a valid and reliable tool to measure maternal self-determination towards breastfeeding.

In this study, a virtual-reality (VR) pedestrian simulation method was used to evaluate the risks to pedestrians crossing streets in a traffic system with driving rules that were unfamiliar to them. Pedestrians from mainland China (which has a right-side driving (RD) system) and Hong Kong (which has a left-side driving (LD) system) were studied. Significant differences were observed between pedestrians from the different locations in terms of the direction in which the pedestrians habitually first looked before crossing. When exposed to an unfamiliar driving rule (i.e., traffic coming from an inconsistent direction in terms of participants’ habitual driving system), the odds of participants from mainland China making an error in their looking behavior were 2.93 times those when exposed to a familiar driving rule. Road markings and traffic sound did not improve these participants’ looking behavior. The results also show a negative correlation between inattentive looking behavior and time to collision (significant at the 1% level), as these errors lead to a shorter time to collision and increased the risk to pedestrians. The results of this study confirmed the risks for pedestrians traveling to places with unfamiliar driving rules and confirmed the existence of habitual looking behavior, and therefore provide evidence of the need for future studies to improve this problem. These may help decision makers take the risks of pedestrians from different driving rules into consideration in future traffic policymaking or traffic-facility improvements. The use of a VR simulation-based approach in this study provided a safe and controllable way to trial interventions and potential improvements without risking injury to participants, and thus may also be used for similar future studies.

With the recent rising popularity of music streaming platforms, consumers are now able to enjoy music as a service, playing music for free without paying to obtain the ownership, the threat to the record labels’ financial prospect is eminent. We propose a novel decision support framework to assist the record label in making better informed decisions in the postrelease management timeframe to maximise the expected profit. By identifying the musical product as a durable goods, we model the consumers’ consumption rule with forward-looking behaviour, viewing music streaming as the consumers’ option of delayed consumption, making purchase only when the expected discounted lifetime utility exceeds the expected utility from streaming. Our proposed decision support framework has the record label use both the price and advertising as instrument of control in achieving maximised expected discounted profit, playing strategically in anticipating to the consumers’ decisions using an interactive Markov chain. We show in our illustrative example the proposed decision support framework is able to make decisions dynamically and performs substantially better than other single control variable decision tools.

The amount of active ingredient in 20 commercially sourced batches of praziquantel (PZQ) tablets was determined using a high-performance liquid chromatography-ultraviolet (HPLC-UV) assay in conjunction with an anthentic, lot of PZQ powder. The general composition of each batch of tablets was also examined by means of (1)H nuclear magnetic resonance (NMR) spectroscopy and the NMR data were subjected to pattern recognition analysis by means of principal component analysis. The HPLC-UV results showed that each batch of PZQ tablets contained approximately the required amount of PZQ (600 mg per tablet). The NMR analysis showed a high degree of compositional variation between manufacturers, which caused by variation in excipients, along with some batch-to-batch variation in the tablets from a single manufacturer. Additionally, the PZQ tablets from one manufacturer were found to have an extra component (methyl-4-hydroxybenzoate) that was not detected in the other preparations.

Balloon mitral valvotomy (BMV) is safe and effective in patients with mitral stenosis (MS) and coexisting mild mitral regurgitation (MR). Influence of preexisting MR on late outcome of BMV is under evaluation. We included 77 patients without MR and 72 with MR in this study, and compared their immediate and late results in a mean follow-up of 33 ± 24 months after BMV. Patients with coexisting MR were older and more frequently had significant valvular calcium and atrial fibrillation than patients without MR. After BMV, mitral valve gradient decreased, and cardiac output and mitral valve area by planimetry increased significantly (all p = 0.0001) in both groups. There was no difference in values of mitral valve gradient and cardiac output after BMV between the groups. Mitral valve area was significantly smaller in patients with preexisting MR. During follow-up, there were 11 patients (14%) in the group without MR and 24 (33%) in the group with MR developed cardiac events (p = 0.006). Cumulative event-free survival was 90% at the second year, 87% at the fourth year, and 69% at the sixth year, respectively, in the group without MR versus 78%, 62%, and 37%, respectively, in the group with MR (p = 0.0014). Cox regression showed that preexisting MR was a significant predictor for late cardiac events with a threefold increased hazard risk (p = 0.0025), but age, valvular calcium, echocardiographic score, and cardiac rhythm also played a culpable role. We conclude that preexisting MR is an important risk factor for poor, late outcome of BMV.

We developed a prognostic scoring system to predict the outcome of follow-up after balloon mitral valvotomy. The system incorporates seven variables before valvotomy: age, New York Heart Association class, fluoroscopic calcification, echocardiographic score, cardiac rhythm, mitral regurgitation, and mitral valve area. Each variable was coded with either 0 or 1 and a total score was between 0 and 7. The study included 150 patients with a mean follow-up of 33 ± 24 months. In patients with scores of 0-1, 2-3, 4-5, and 6-7, the estimated cardiac event-free survival rate was 97%, 94%, 86%, and 68%, respectively, at 1 year; 95%, 88%, 74%, and 47%, respectively, at 3 years; and 92%, 82%, 61%, and 30%, respectively, 5 years after valvotomy ( p = 0.0001). The hazard risk ratio for cardiac events was 1.7 times greater for every step up of the score ( p = 0.0001). Our scoring system provides a simple but effective method to predict late outcome of balloon mitral valvotomy. (Am Heart J 1997;134:772-8.)

The follow-up results between Inoue balloon (n = 43, group 1) and double-balloon (n = 43, group 2) mitral valvotomies were compared in a patient-to-patient matched study. Matching was based on patients' age, mitral valve echo score, fluoroscopic calcification, mitral valve area before valvotomy, and follow-up period. The mean follow-up period was 13 +/- 9 months for both groups. At follow-up, 72% of patients were symptom free in each group; 2 (4.7%) patients in group 1 and 1 (2.3%) patient in group 2 underwent mitral valve replacement surgery. Of these 3 patients, 2 died after surgery, 1 from each group. The mitral valve area by Doppler was 1.8 +/- 0.3 cm2 in group 1 and 1.8 +/- 0.4 cm2 in group 2 (p = 0.7); the area by echo planimetry was 1.7 +/- 0.3 cm2 in group 1 and 1.8 +/- 0.3 cm2 in group 2 (p = 0.3) at follow-up. Restenosis occurred in 5 (12%) patients from each group. The cumulative restenosis-free rate was 96% at 1 years, 78% at 2 years, and 58% at 3 years in group 1 and 98%, 76%, and 51%, respectively, in group 2 (p = 0.8). Balloon selection did not appear to influence the clinical outcome at follow-up. We conclude that both the inoue balloon and the double-balloon valvotomies are effective therapies with comparable follow-up results for patients with mitral stenosis.

This study was conducted to establish the validity of left-sided cardiac output measurement with a Swan-Ganz catheter and assess its accuracy in estimating mitral valve area (MVA) by the Gorlin formula. The use of right-sided cardiac output after balloon mitral valvotomy (BMV) can give inaccurate measurements for Gorlin-derived MVA because of the atrial septal defect (ASD) created during the procedure. The left-sided cardiac output was measured with a Swan-Ganz catheter (proximal port in the left atrium and then in the left ventricle, and distal port in the ascending aorta) in 10 consecutive patients before and after BMV. Gorlin-derived MVA cardiac output by this method was compared with (1) Gorlin-derived MVA by means of right-sided cardiac output with and without balloon occlusion of the ASD and (2) MVA measured by echocardiography. Before BMV, a close agreement with a good correlation between left-sided and right-sided cardiac output was found (r = 0.83, p = 0.006). Furthermore, Gorlin-derived MVA by cardiac output with either method was comparable with valve area by echo. After BMV, left-sided cardiac output correlated well (r = 0.92, p = 0.0002) and was comparable with right-sided cardiac output with occlusion of the ASD (mean difference 0.17 +/- 0.49 L/min, p = 0.3) but was significantly lower than the value obtained with open ASD (mean difference 0.93 +/- 0.77 L/min, p = 0.004). Comparison of the correspondent MVAs yielded similar results. Gorlin-derived MVA with left-sided cardiac output and MVA by echo were also similar.(ABSTRACT TRUNCATED AT 250 WORDS)

The thermodynamic fluctuation near a certain critical temperature of an isolated, radiating Kerr-Newman black hole with charge and angular momentum not both zero is investigated. Divergence is found in the mean square fluctuation of mass and entropy of the black hole as the critical temperature is approached. This gives further support to the existence of a second order phase transition for Kerr-Newman black holes.

The thermodynamic fluctuation of a charged black hole is investigated and anomalous behaviour near a certain critical temperature is found, evidencing the existence of a phase transition. A phenomenological order parameter is then introduced and the fluctuation-dissipation properties of the black hole near the critical temperature are studied. The critical exponents of relevant thermodynamical quantities are also computed.

Percutaneous double balloon valvotomy for severe rheumatic mitral stenosis was successfully performed in 281 of 285 consecutive patients. The changes evoked were a decrease of the mean transvalvular gradient from 16 +/- 7 to 5 +/- 3 mm Hg, an increase in cardiac output from 3.8 +/- 1.0 liters/min to 5.4 +/- 1.5 liters/min and an increase in mitral valve area from 0.86 +/- 0.24 cm2 to 2.41 +/- 0.54 cm2. The mean pulmonary artery pressure decreased from 37 +/- 13 mm Hg to 27 +/- 12 mm Hg and the pulmonary vascular resistance decreased from 307 +/- 181 to 238 +/- 122 dynes/s/cm-5. Symptomatic improvement occurred in 272 of the 285 (95%) patients. There were 3 procedure-related deaths (1%). Postdilatation mitral regurgitation was not significant in most patients. Therefore, this procedure can be performed at a low risk with effective results and a fast recovery.

Previous studies have demonstrated that mitral regurgitation (MR) greatly influenced long-term outcome after surgical mitral commissurotomy in pts with mitral stenosis. However, this issue has not been addressed after balloon mitral valvotomy (BMV). We therefore examined 6 year follow-up (FU) data in 69 pts who presented MR assessed by angiography before BMV (group 1), and compared the results with 75 pts who had no MR (group 2). Mean FU period was 27 ± 20 mo in group 1 and 33 ± 23 mo in group 2 (p = NS). Comparison of pts baseline characteristics, mitral valve area (MVA) before and after BMV and FU results between the groups were: Clinical Profile Group 1 Group 2 p-value Age (yr) 57 ± 13 45 ± 16 0.0001 Sex: M/F 80%/20% 17%/83% NS NYHA-FC: III-IV 90% 81% NS Echo score g8 22% 12% NS Fluoroscopic Ca 2+ 87% 60% 0.001 A.F 56% 19% 0.0001 Pre 2D MVA (cm 2 ) 1.06 ± 0.30 100 ± 027 NS Post 2D MVA (cm 2 ) 1.71 ± 0.35 1.88±0.41 0.01 FU NYHA class I 51% 88% 0.0001 Cardiac events (CE) 28% 9% l 0.01 CE = stroke, repeat BMV, mitral valve replacement (MVR), and death Comparison of 6 year CE-free and MVR-free actuarial survival rates were: Gr 1/Gr 2 1-yr 2-yr 3-yr 4-yr 5-yr 6-yr p-value CE-free (%) 87/94 79/92 73/90 65/90 59/90 49/79 0.002 MVR-free (%) 93/96 89/96 82/96 78/96 78/96 65/84 0.01 Hazard risk ratio by Cox regression analysis was 3.7 (95% CI: 1.5-8.9) times greater for CE (p l 0.01), and 4.0 (1.2–12.7) times greater for MVR (p l 0.05) at FU in group 1 than in group 2. Conclusions (1) MR before BMV increases risk for late CE, particularly requiring MVR in the early FU. (2) Pts with MR appears to be older with calcified valves and AF, and to obtain smaller MVA post BMV, all of which may exacerbate the poor later outcome. (3) Half of such pts may still derive long-term benefits from BMV.

A low incidence rate of thromboembolism has been reported in mitral porcine valve recipients. In contrast, 5 of 22 single mitral porcine valve recipients (23 percent) followed up in our clinic for a mean of 16 months had thromboembolic events. All patients but one were receiving long-term anticoagulant therapy. One thromboembolic event resulted in death, three in permanent neurologic deficits and one in a peripheral arterial occlusion. All five patients with emboli had atrial fibrillation and left atrial enlargement. Three had thromboembolic events before porcine heart valve implantation. In addition, five mitral porcine valve recipients who were not receiving anticoagulant therapy were examined at autopsy. Thrombus was identified in the left atrium in three patients, at the tissue-valve interface (sewing ring) in two, on the porcine valve cusps in one and in the right atrium in one. Factors influencing thrombus formation such as left atrial enlargement, atrial fibrillation and a prosthetic device are present after mitral porcine valve implantation and are indications for long-term anticoagulation therapy.

Summary The clinical diagnostic features of right ventricular myxoma are described in a recent patient and related to the 15 cases previously reported. The presence of a pulmonic systolic ejection murmur with a delayed (120 to 140 msec.) and accentuated pulmonic second sound, or calcification in the region of the right ventricular outflow tract should suggest this lesion. Cardiac catheterization with angiocardiography is diagnostic. 67 Ga scanning may assist in the diagnosis and follow-up after surgical removal of the myxoma. Early surgical removal will avoid the possibility of sudden death.

The step from coronary angiography to surgery is taken primarily on the basis of the ejection fraction (EF) and number of diseased vessels (NV), taken jointly as coronary status (CS). This study reviewed (1) how well EF, NV and CS are estimated from clinical data, (2) how much improvement is gained by adding noninvasive data, (3) how good this model is when applied to a larger cohort and (4) whether the decision to angiography can be made on the basis of CS estimated from clinical data alone. A quantitative definition of CS was established as a principal component of EF and NV. Estimates of EF, NV and CS were made from clinical data of 60 patients. Correlations with the actual values were EF 87%, NV 93% and CS 93%. When noninvasive data were added to this model, the correlations increased to EF 95%, NV 99% and CS 98%. When the clinical data model was applied to 169 patients, the correlations decreased to EF 77%, NV 71 % and CS 74%. CS estimated from clinical data alone was set up as a test for angiography for 169 patients. This test had a sensitivity of 98% and a specificity of 63%, demonstrating the feasibility of using clinical data alone in deciding angiography.

Eighty of 98 patients with acquired complete heart block are presented and discussed with respect to the effect on prognosis of age, etiology, presence of cardiac and extracardiac complications and electrocardiographic data. In this series of 48 control and 32 paced patients, mortality was adversely affected by myocardial infarction, uremia, shock, diabetes, a ventricular rate below 30/min., and Stokes-Adams attacks. Mortality was not affected by changing block, duration of the QRS interval, or the presence of cardiac failure. The prognosis in complete heart block was improved by pacing except in the presence of severe renal or metabolic complications.

Quantitative preoperative evaluation of potential postoperative myocardial performance after resection of an akinetic area has been difficult because the usual indices of myocardial performance provide no directly applicable information or cannot be applied because of disorders of isovolumetric contraction. Critical factors in postoperative performance are residual ventricular size and the capacity to increase fiber shortening. We have assumed that postoperative incremental fiber shortening is determined primarily by reduction in afterload secondary to reduction in ventricular volume. Using this assumption, a preoperative late systolic force-length curve can be extrapolated to form a boundary for postoperative fiber shortening after surgical unloading. Preliminary preoperative studies in human beings have adequately estimated postoperative performance and are compatible with these assumptions. Mathematical considerations developed for these purposes suggest that the relatively simple spherical model is adequate for most ventricles.

A patient with constrictive pericarditis was studied 5 days before and 50 days and 13 months after extensive pericardiectomy. Functional data were derived from measurement of intracardiac pressure and left ventricular volume. Before operation the left ventricle was characterized by both systolic and diastolic unloading due to volume restriction. Complete anterior and lateral decortication was accompanied by minimal early clinical improvement. Catheterization studies reflected persistent severe biventricular restriction. A year after operation, marked clinical improvement was accompanied by studies revealing resolution of the restrictive elements.