Annotated computed tomography coronary angiogram images and associated data of normal and diseased arteries

Computed Tomography Coronary Angiography (CTCA) is a non-invasive method to evaluate coronary artery anatomy and disease. CTCA is ideal for geometry reconstruction to create virtual models of coronary arteries. To our knowledge there is no public dataset that includes centrelines and segmentation of the full coronary tree. We provide anonymized CTCA images, voxel-wise annotations and associated data in the form of centrelines, calcification scores and meshes of the coronary lumen in 20 normal and 20 diseased cases. Images were obtained along with patient information with informed, written consent as part of the Coronary Atlas. Cases were classified as normal (zero calcium score with no signs of stenosis) or diseased (confirmed coronary artery disease). Manual voxel-wise segmentations by three experts were combined using majority voting to generate the final annotations. Provided data can be used for a variety of research purposes, such as 3D printing patient-specific models, development and validation of segmentation algorithms, education and training of medical personnel and in-silico analyses such as testing of medical devices.

Short-term risk prediction after major lower limb amputation: PERCEIVE study

BACKGROUND

The accuracy with which healthcare professionals (HCPs) and risk prediction tools predict outcomes after major lower limb amputation (MLLA) is uncertain. The aim of this study was to evaluate the accuracy of predicting short-term (30 days after MLLA) mortality, morbidity, and revisional surgery.

METHODS

The PERCEIVE (PrEdiction of Risk and Communication of outcomE following major lower limb amputation: a collaboratIVE) study was launched on 1 October 2020. It was an international multicentre study, including adults undergoing MLLA for complications of peripheral arterial disease and/or diabetes. Preoperative predictions of 30-day mortality, morbidity, and MLLA revision by surgeons and anaesthetists were recorded. Probabilities from relevant risk prediction tools were calculated. Evaluation of accuracy included measures of discrimination, calibration, and overall performance.

RESULTS

Some 537 patients were included. HCPs had acceptable discrimination in predicting mortality (931 predictions; C-statistic 0.758) and MLLA revision (565 predictions; C-statistic 0.756), but were poor at predicting morbidity (980 predictions; C-statistic 0.616). They overpredicted the risk of all outcomes. All except three risk prediction tools had worse discrimination than HCPs for predicting mortality (C-statistics 0.789, 0.774, and 0.773); two of these significantly overestimated the risk compared with HCPs. SORT version 2 (the only tool incorporating HCP predictions) demonstrated better calibration and overall performance (Brier score 0.082) than HCPs. Tools predicting morbidity and MLLA revision had poor discrimination (C-statistics 0.520 and 0.679).

CONCLUSION

Clinicians predicted mortality and MLLA revision well, but predicted morbidity poorly. They overestimated the risk of mortality, morbidity, and MLLA revision. Most short-term risk prediction tools had poorer discrimination or calibration than HCPs. The best method of predicting mortality was a statistical tool that incorporated HCP estimation.

Patterns and predictors of smartphone ownership in a cardiology inpatient population

Introduction

Mobile health (mHealth) interventions have grown in popularity, particularly for chronic disease management. Uptake of these interventions depends on patient smartphone ownership.

Purpose

To examine the smartphone ownership rate among cardiac inpatients and identify the associated demographic factors.

Methods

Between February 2019 and March 2020, 565 patients were screened for potential enrolment in the TeleClinical Care (TCC) pilot study at two hospitals in Australia. All patients had an admission diagnosis of acute coronary syndrome or heart failure. Mobile phone ownership was documented at the time of screening. Retrospectively, each patient's electronic medical record was examined for: age, sex, primary diagnosis, suburb of residence, private health insurance subscription, smoking status and occupation. Continuous variables were analysed using a multinomial logistic regression model. Categorical variables were analysed using a generalised linear model.

Results

Mobile phone ownership was documented for 523 patients (92.6%). 60.6% of all patients owned smartphones, and 14.9% owned basic mobile phones. 24.5% of patients did not own any mobile phone. The average age of participants was 70.8 years. Smartphone ownership rates were high among patients in the 18–49 (96%), 50–59 (89%) and 60–69 (85%) year groups. The differences between these groups were not statistically significant. In the age group 70–79 years, however, smartphone ownership fell to 56.5% (p<0.001, figure 1). The relative risk (RR) of not owning a smartphone increased by 12% for each additional year of age. Overall, smartphone ownership was less more common in women than men [79/179 (44.1%) vs. 238/344 (69.2%), RR 0.78, 95% CI 0.67–0.91, P=0.003, age-adjusted) driven by a difference in patients aged 70 or above [36/131 (27.5%) vs. 82/168 (48.9%), RR 0.66, 95% 0.49–0.90, p<0.001]. After adjustment for age and sex, patients with a primary diagnosis of ACS were more likely to own a smartphone compared to those with HF [227/316 (71.8%) vs. 90/207 (43.5%), RR 1.22, 95% CI 1.04–1.43, P=0.015]. Patients with private health insurance were more likely to own a smartphone than those who were uninsured [68.9% (162/235) v 54.0% (154/285), RR 1.28, 95% CI 1.13–1.43, P<0.001, figure 2). Smartphone ownership was significantly higher in those who were currently working, compared to those who were retired (117/119, 98.3% vs. 56/87, 64.3%, RR 0.76, 95% CI 0.64 – 0.89, P=0.001), even after adjustment for age. Patients living in the region with lowest average household income had the lowest rate of smartphone ownership (52.4%). There was no significant difference in smartphone ownership based on type of occupation.

Conclusion

Smartphone ownership was common in this inpatient population. Patients who are older, female and of lower socioeconomic background are less likely to own smartphones, and future mHealth programs should be cognizant of this.

Funding Acknowledgement

Type of funding sources: Public hospital(s). Main funding source(s): Prince of Wales Hospital, Department of Cardiology Figure 1. Smartphone ownership by ageFigure 2. Insurance status

A randomised control trial of TeleClinical Care – a smartphone-app based model of care for heart failure and acute coronary syndromes

Background

Acute coronary syndrome (ACS) and heart failure (HF) are frequent causes of hospitalisation and readmissions. A novel smartphone app-based model of care (TeleClinical Care – TCC) was developed to support patients after ACS or HF admission.

Purpose

This randomised control trial aimed to characterise both the intervention and clinical outcomes. The primary endpoint was the incidence of 30-day readmissions. Secondary endpoints included six-month cardiac and all-cause readmissions, mortality, major adverse cardiovascular events (MACE), cardiac rehabilitation (CR) completion, medication adherence, serum low-density lipoprotein (LDL-C), quality of life, blood pressure, body mass index, waist circumference and six-minute walk distance. Additionally, cost-effectiveness and user satisfaction were evaluated.

Methods

Patients were randomised 1:1 to either TCC plus usual care or usual care alone and were followed-up at six months. Intervention arm participants received the TCC app and were asked to use Bluetooth-enabled devices for measuring weight, heart rate, blood pressure and physical activity daily. Readings were automatically transmitted to the patient's smartphone and a secure web-server (KIOLA). Customisable thresholds for each parameter were defined at discharge. Abnormal readings were flagged by email to a monitoring team, who discussed management with the patient's usual healthcare providers. The app also provided educational push notifications.

Results

164 patients from two hospitals in Sydney, Australia were enrolled between February 2019 and March 2020 (TCC n=81, control n=83). Recruitment ceased during the COVID-19 pandemic. The mean age was 61.5 years. 79% of patients were male. The per-patient mean percentage of days with data transmission was 64.2±27.5%. 565 alerts were received, 16% of which resulted in additional investigations, healthcare consultation or a change in management. There was no difference in 30-day readmission rate (11 readmissions in each arm). There was a significant difference in six-month readmissions, favouring the intervention (21 vs. 41 readmissions, HR=0.40, 95% CI 0.16–0.95, P=0.03), driven by a reduction in cardiac readmissions (11 vs. 25, HR=0.51, 95% CI 0.27–0.94, P=0.03). Use of TCC was associated with improved CR completion (39% vs. 18%, P=0.025) and medication adherence (75% vs. 50%, P=0.002). There was no significant difference in mortality, MACE, LDL-C, quality of life or any of the physical parameters. The average user rating was 4.56 out of 5. The study cost EUR 4015 per readmission saved. Upon modelling, it was calculated that if the number of enrolled patients exceeds 243, total expenditure will be overcome by cost savings from reducing readmissions.

Conclusion

The TCC model of care was feasible and safe. In this study, clinical benefits were demonstrated including a reduction in six-month readmissions, improved CR completion and improved medication adherence.

Funding Acknowledgement

Type of funding sources: Public hospital(s). Main funding source(s): Department of Cardiology, Prince of Wales HospitalPrince of Wales Hospital Foundation Figure 1. TCC interfaceFigure 2. Cumulative readmissions over the course of the trial

Process evaluation of the TeleClinical Care pilot study

Background

A novel smartphone app-based model of care (TeleClinical Care – TCC) for patients with acute coronary syndrome (ACS) and heart failure (HF) was evaluated in a two-site, pilot randomised control trial of 164 participants in Australia. The trial demonstrated improvements in readmission rates, cardiac rehabilitation completion and medication compliance for participants in the intervention arm.

Purpose

A process evaluation was designed with the aims of identifying contextual factors and mechanisms that influenced the results of the trial, as well as identifying methods of improving site and participant recruitment and the delivery of the intervention, for a planned larger effectiveness trial of over 1000 patients across the state of New South Wales (TCC-Cardiac).

Methods

Multiple data sources were used in this mixed-methods process evaluation including interviews with four TCC team members, three general practitioners and three cardiologists. Cardiac rehabilitation completion (CR) rates, heart failure outreach service (HFOS) referrals and cardiologist follow-up appointments were audited. A patient questionnaire was also analysed for evidence of improved self-care as a mechanism of benefit of the TCC app.

Results

Several factors were identified that influenced the success of the trial. Rates of HFOS referral and cardiologist follow-up were high in both arms, and were not significantly different. Team members were largely positive towards their introduction into the trial, but highlighted several factors that could be optimised for the TCC-Cardiac trial, namely streamlining of the enrolment process and improving the reach of the trial, by maximising the screening of potential participants. In their interviews, the GPs and cardiologists viewed the intervention favourably in regard to potential benefit of closely monitoring, and responding to abnormalities in their patients. Several factors were suggested to be optimised prior to the commencement of TCC-Cardiac, such as additional workload and delineation of which party was responsible for alert management. Several patients commented on improved self-management as a result of TCC participation.

Discussion

The TCC trial was successful with the results likely influenced by high rates of follow-up from HFOS and cardiologists. Improved self-care likely drove several benefits including higher engagement with cardiac rehabilitation. The conduct and delivery TCC-Cardiac will be improved by extending recruitment to patients in non-cardiac wards, ensuring team members have adequate time (>15 hours per week) to optimise recruitment, establishing the responsibilities of GPs and cardiologists as part of the model and provision of summary data to them.

Funding Acknowledgement

Type of funding sources: Public hospital(s). Main funding source(s): Prince of Wales Hospital

Determinants of burnout and other aspects of psychological well-being in healthcare workers during the Covid-19 pandemic: A multinational cross-sectional study

The Covid-19 pandemic has placed unprecedented pressure on healthcare systems and workers around the world. Such pressures may impact on working conditions, psychological wellbeing and perception of safety. In spite of this, no study has assessed the relationship between safety attitudes and psychological outcomes. Moreover, only limited studies have examined the relationship between personal characteristics and psychological outcomes during Covid-19. From 22nd March 2020 to 18th June 2020, healthcare workers from the United Kingdom, Poland, and Singapore were invited to participate using a self-administered questionnaire comprising the Safety Attitudes Questionnaire (SAQ), Oldenburg Burnout Inventory (OLBI) and Hospital Anxiety and Depression Scale (HADS) to evaluate safety culture, burnout and anxiety/depression. Multivariate logistic regression was used to determine predictors of burnout, anxiety and depression. Of 3,537 healthcare workers who participated in the study, 2,364 (67%) screened positive for burnout, 701 (20%) for anxiety, and 389 (11%) for depression. Significant predictors of burnout included patient-facing roles: doctor (OR 2.10; 95% CI 1.49-2.95), nurse (OR 1.38; 95% CI 1.04-1.84), and 'other clinical' (OR 2.02; 95% CI 1.45-2.82); being redeployed (OR 1.27; 95% CI 1.02-1.58), bottom quartile SAQ score (OR 2.43; 95% CI 1.98-2.99), anxiety (OR 4.87; 95% CI 3.92-6.06) and depression (OR 4.06; 95% CI 3.04-5.42). Significant factors inversely correlated with burnout included being tested for SARS-CoV-2 (OR 0.64; 95% CI 0.51-0.82) and top quartile SAQ score (OR 0.30; 95% CI 0.22-0.40). Significant factors associated with anxiety and depression, included burnout, gender, safety attitudes and job role. Our findings demonstrate a significant burden of burnout, anxiety, and depression amongst healthcare workers. A strong association was seen between SARS-CoV-2 testing, safety attitudes, gender, job role, redeployment and psychological state. These findings highlight the importance of targeted support services for at risk groups and proactive SARS-CoV-2 testing of healthcare workers.

mHealth interventions in the management of heart failure, ischaemic heart disease and hypertension: a systematic review and meta-analysis of randomised controlled trials

Introduction

Cardiovascular disease (CVD) remains the leading cause of death in the world. Mobile phones have become ubiquitous in most developed societies. Smartphone applications, telemonitoring and clinician-driven short message service (SMS) allow for novel methods in managing chronic cardiovascular conditions such as ischaemic heart disease, heart failure and hypertension.

Purpose

To evaluate the impact of mobile phone-based interventions (MPIs) on mortality, hospitalisations and blood pressure and body mass index (BMI) in patients diagnosed with either acute coronary syndrome, heart failure or hypertension.

Methods

A systematic review was conducted using seven electronic databases, identifying all randomised control trials (RCTs) featuring an MPI in the management of these conditions. Meta-analysis was performed by using standard analytical techniques. The odds ratio (OR) was used as a summary statistic.

Results

Twenty-six RCTs including 6,713 patients were identified. Of these 26 studies, 13 examined text messaging intereventions, 10 studied telemonitoring interventions and three described smartphone applications with other functions. Twelve studies were included for meta-analysis. In patients with heart failure (n=1683), MPIs were associated with a significantly lower rate of all-cause hospital admissions at six months (31% vs. 36%, OR 0.77, 95% CI 0.62–0.97, p=0.03, I2 = 0). A significant difference was also demonstrated for heart-failure admissions (14.0% vs. 18.5%, OR 0.69, 95% CI 0.48 to 0.98, p=0.04, I2 = 26%). There was no difference in mortality (10.4% vs. 11.6% p=0.45). In patients with hypertension, the difference in systolic BP was 4.3mmHg less in the intervention group (95% CI: −7.8 to −0.78 mmHg, p=0.02). Four studies examined medication compliance as an endpoint in patients with ischaemic heart disease, and all four demonstrated a significant difference favouring the MPI group (see table 1). However, due to variable quantification of compliance, meta-analysis was not possible. There was no significant difference in the change in BMI from four studies after six or more months (mean difference −0.46, 95% CI: −1.44 to 0.52, P=0.36).

Conclusions

The available data suggests MPIs may have a role as valuable adjuncts in the management of chronic CVD.

Figure 1

Funding Acknowledgement

Type of funding source: Public grant(s) – National budget only. Main funding source(s): National Health and Medical Research Council (NHMRC)

Medical education in Singapore

Allopathic medical education in Singapore extends for more than a century from its simple beginnings. In recent times, changes have been rapid, both in undergraduate and postgraduate specialty medical training. Over the last decade, undergraduate medical education has increased from a single to three medical schools and the postgraduate training has expanded further by incorporating the Accreditation Council for Graduate Medical Education International framework. With these changes, the curricula, assessment systems, as well as teaching and learning approaches, with the use of technology-enhanced learning and program evaluation processes have expanded, largely based on best evidence medical education. To support these initiatives and the recent rapid expansion, most training institutions have incorporated faculty development programs, such as the Centre for Medical Education at the National University of Singapore.

Low muscle mass and sarcopenia: common and predictive of osteopenia in inflammatory bowel disease

BACKGROUND

Body composition is poorly studied in inflammatory bowel disease (IBD). Sarcopenia describes a loss of muscle mass and strength.

AIM

To assess the prevalence of low lean mass (LM), sarcopenia and associated morbidity in an adult IBD cohort.

METHODS

Cross-sectional data were gathered on pre-menopausal 18- to 50-year-old patients with IBD. Whole-body dual-energy X-ray absorptiometry, anthropometric assessment and grip strength were performed. Low LM was defined as ≥1 s.d. below the population mean for appendicular skeletal muscle index [ASMI (kg)/height (m)²], and sarcopenia as both ASMI and grip strength ≥1 s.d. below population mean. Multivariate regression analyses were performed.

RESULTS

Of 137 participants (median age 31 years, BMI 24.8 kg/m(2) ), 56% were male and 69% had Crohn's disease (CD). Low LM and sarcopenia were observed in 21% and 12% of patients, respectively, and osteopenia/osteoporosis in 38% of patients (mean lumbar spine t-score -0.3 ± s.d. 1.1). Grip strength predicted low LM and sarcopenia better than did body mass index (BMI) (OR 4.8 vs. OR 0.7 for low-LM, P < 0.05 both). Normal BMI was falsely reassuring in 72% and 76% of patients with low ASMI and sarcopenia, respectively. Low LM and sarcopenia (OR = 3.6, P = 0.03; OR = 6.3, P = 0.02; respectively), but not BMI nor fat mass, predicted osteopenia/osteoporosis.

CONCLUSIONS

Low lean mass and sarcopenia are common in patients with IBD, and important to recognise as they predict osteopenia/osteoporosis. Grip strength testing should be incorporated into routine clinical practice to detect low lean mass deficits, which may go unrecognised using BMI alone.

Oscillatory behavior of vortex-lattice melting transition line in mesoscopic Bi_{2}Sr_{2}CaCu_{2}O_{8+y} superconductors

The vortex-lattice melting transition of a limited number of vortices confined in mesoscopic square superconductors was studied by c-axis resistance measurements using stacks of intrinsic Josephson junctions in Bi_{2}Sr_{2}CaCu_{2}O_{8+y}. In contrast to the melting transition in bulk crystals, we have first found a clear oscillatory behavior in the field dependence of the melting temperature in small samples of 5-10  μm square. The periods of the oscillations roughly obey the regularity of the matching conditions of square vortex lattices surrounded by a square boundary and the melting temperatures are enhanced around the vortex number of i^{2} (where i is an integer). The results suggest that a confinement effect by the square boundary stabilizes square lattice structures which are realized around i^{2} vortex number even in competition with the favorable Abrikosov triangular lattice in the bulk.

Nanostructure characterisation of flow-formed Cr-Mo-V steel using transmission Kikuchi diffraction technique

Nowadays flow-forming has become a desired near net shape manufacturing method as it provides excellent mechanical properties with improved surface finish and significant manufacturing cost reduction. However, the material is subjected to excessive plastic deformation during flow-forming process, generating a very fine and complex microstructure. In addition, the intense dislocation density and residual stress that is generated in the component during processing makes the microstructure characterisation using conventional micro-analytical tools challenging. Thus, the microstructure/property relationship study in such a material is rather difficult. In the present study a flow-formed Cr-Mo-V steel nanostructure and crystallographic texture were characterised by means of Transmission Kikuchi Diffraction (TKD). Here, TKD is shown to be a powerful technique in revealing very fine martensite laths within an austenite matrix. Moreover, fine precipitates in the order of 20-70 nm on the martensite lath boundaries were clearly imaged and characterised. This greatly assisted in understanding the preferable site formation of the carbides in such a complex microstructure. The results showed that the actual TKD spatial resolution was in the range of 5-10 nm using 25 kV for flow-formed Cr-Mo-V steel.

β-Catenin and NF-κB co-activation triggered by TLR3 stimulation facilitates stem cell-like phenotypes in breast cancer

Cancer stem cells (CSCs) are responsible for tumor initiation and progression. Toll-like receptors (TLRs) are highly expressed in cancer cells and associated with poor prognosis. However, a linkage between CSCs and TLRs is unclear, and potential intervention strategies to prevent TLR stimulation-induced CSC formation and underlying mechanisms are lacking. Here, we demonstrate that stimulation of toll-like receptor 3 (TLR3) promotes breast cancer cells toward a CSC phenotype in vitro and in vivo. Importantly, conventional NF-κB signaling pathway is not exclusively responsible for TLR3 activation-enriched CSCs. Intriguingly, simultaneous activation of both β-catenin and NF-κB signaling pathways, but neither alone, is required for the enhanced CSC phenotypes. We have further identified a small molecule cardamonin that can concurrently inhibit β-catenin and NF-κB signals. Cardamonin is capable of effectively abolishing TLR3 activation-enhanced CSC phenotypes in vitro and successfully controlling TLR3 stimulation-induced tumor growth in human breast cancer xenografts. These findings may provide a foundation for developing new strategies to prevent the induction of CSCs during cancer therapies.

Attitudes, Practice and Educational Preferences Towards Evidence-Based Medicine among Physicians in a Large Teaching Hospital

Evidence-based medicine (EBM) is an emerging must-know topic for today's physicians. The present literature is inadequate in identifying the attitudes, practice, and educational needs and preferred interventions of EBM. The objectives of this survey were to identify a) the attitude toward and practice of EBM among physicians, b) perceived benefits of EBM in daily practice, c) barriers to EBM practice, and d) preferred educational interventions.

METHODS

This was a questionnaire-based cross-sectional survey of physicians in a single large teaching hospital.

RESULTS

Overall, 56% of the physician respondents described the attitude towards EBM in their institution as positive. A similar number of physicians also reported the attitude of their colleagues towards EBM as favourable. 67% of the physicians believed EBM was useful in daily management of patients. In contrast, only 45% of the physicians actually practiced EBM in their daily patient management. The factors that discouraged them from actual practice include a lack of time, lack of exposure to EBM during their undergraduate curriculum, lack of endorsement, and fear of criticism by seniors. Physicians preferred less time consuming and less rigorous educational interventions such as clinical practice guidelines, journal club, and case review and discussion for teaching and learning EBM.

INTERPRETATION

There are disconnects between belief and actual practice and between preferred and ideal educational interventions of EBM among physicians surveyed.

Nonlinear nanodevices using magnetic flux quanta

All devices realized so far that control the motion of magnetic flux quanta employ either samples with nanofabricated spatially-asymmetric potentials (which strongly limit controllability), or pristine superconductors rectifying with low-efficiency time-asymmetric oscillations of an external magnetic field. Using layered Bi2Sr2CaCu2O8+delta materials, here we fabricate and simulate two efficient nonlinear superconducting devices with no spatial asymmetry. These devices can rectify with high-efficiency a two-harmonic external current dragging vortices in target directions by changing either the relative phase or the frequency ratio of the two harmonics.

A case of a borderline-broad complex tachycardia

Prompt and correct treatment of broad complex tachycardias in the emergency department can often be life-saving to the patient and satisfying for the emergency physician. They, however, are often a diagnostic challenge. Here, we present a case of posterior fascicular ventricular tachycardia, an idiopathic form of ventricular tachycardia that occurs in patients without coronary artery disease and verapamil sensitive. The differential diagnoses of posterior fascicular ventricular tachycardia and supraventricular tachycardia with aberrancy will also be discussed.

Tilt of pancake vortex stacks in layered superconductors in the crossing lattice regime

We study crossing vortices in strongly anisotropic Bi2Sr2CaCu2O8+delta single crystals. Using scanning Hall probe microscopy and Bitter decoration techniques, we find an asymmetry of magnetic field profiles produced by pancake vortices (PVs), which are interacting with Josephson vortices (JVs), near the surface of the crystal. We attribute the observed asymmetry to a substantial tilt (14-18 degrees) of PV stacks, which is produced by the torque due to the surface currents and JVs. We calculate the tilt angle and obtain agreement with experimental data when the irreversible in-plane magnetization is included. A further refinement to the model is considered which accounts for a reduction in the PV stack line tension near the sample surface.

Periodic oscillations of Josephson-vortex flow resistance in Bi(2)Sr(2)CaCu(2)O(8+y)

To study the Josephson-vortex system, we have measured the vortex-flow resistance as a function of magnetic field parallel to the ab plane in Bi(2)Sr(2)CaCu(2)O(8+y) single crystals. Novel periodic oscillations of the vortex-flow resistance have been observed in a wide range of temperatures and magnetic fields. The period of the oscillations corresponds to the field needed to add "one" vortex quantum per "two" intrinsic Josephson junctions. The flow velocity is related to a matching effect between the lattice spacing of Josephson vortices along the layers and the width of the sample. These results suggest that Josephson vortices form a triangular lattice in the ground state where the oscillations occur.

Visualization of interacting crossing vortex lattices in the presence of quenched disorder

We have imaged interacting crossing pancake vortex (PV) and Josephson vortex (JV) lattices in highly anisotropic Bi2Sr2CaCu2O(8+delta) single crystals under tilted magnetic fields. The dependence of vortex structures on in-plane field is in good quantitative agreement with theoretical predictions, yielding an almost temperature-independent anisotropy parameter of gamma=640+/-25. We directly confirm that the PV/JV attraction arises from small PV displacements in the presence of JV supercurrents and demonstrate how the existence of quenched disorder leads to indirect JV pinning and dynamic vortex fragmentation.

A one-dimensional chain state of vortex matter

Magnetic flux penetrates isotropic type II superconductors in flux-quantized vortices, which arrange themselves into a lattice structure that is independent of the direction of the applied field. In extremely anisotropic high-transition-temperature (high-Tc) superconductors, a lattice of stacks of circular 'pancake' vortices forms when a magnetic field is applied perpendicular to the copper oxide layers, while an orthogonal elongated lattice of elliptical Josephson vortices forms when the applied field is parallel to the layers. Here we report that when a tilted magnetic field is applied to single crystals of Bi2Sr2CaCu2O8+delta, these lattices can interact to form a new state of vortex matter in which all stacks of pancake vortices intersect the Josephson vortices. The sublattice of Josephson vortices can therefore be used to manipulate the sublattice of pancake vortices. This result explains the suppression of irreversible magnetization by in-plane fields as seen in Bi2Sr2CaCu2O8+delta crystals, a hitherto mysterious observation. The ability to manipulate sublattices could be important for flux-logic devices, where a 'bit' might be represented by a pancake vortex stack, and the problem of vortex positioning is overcome through sublattice interactions. This also enables the development of flux transducers and amplifiers, considerably broadening the scope for applications of anisotropic high-Tc superconductors.

Endemic typhus in Singapore--a re-emerging infectious disease?

Singapore is a modern urban city and endemic typhus is thought to be a disease of the past. This may be due to lack of specific serological testing as indirect immunoperoxidase testing using specific rickettsial antigens (U.S. Army Medical Research Unit, Institute of Medical Research, Kuala Lumpur, Malaysia) has only recently become available. In the last fourteen months, twenty-one cases of endemic typhus were diagnosed in patients hospitalised for acute febrile illnesses at the National University Hospital. We conducted a case control study to define the clinical and laboratory features of endemic typhus in Singapore.

METHOD

Demographic, clinical and laboratory data were reviewed for cases and twenty-one age and sex matched controls who had negative serologic tests as part of a work-up for fever of unknown origin.

RESULTS

Apart from a higher initial temperature (39 degrees C vs 37.9 degrees C (p < 0.001)) and ALT(p = 0.002), cases and controls had similar presentations of fever, myalgia, headache, cough, normal WBC and platelet counts. Singapore residents and migrant workers were represented in both groups (p = ns).

CONCLUSION

Endemic typhus remains an important cause of acute febrile illness in Singaporein both the local and migrant worker populations. The presentation is similar to other causes of acute febrile illnesses and the diagnosis will be missed unless it is specifically sought.

New vortex-matter size effect observed in Bi(2)Sr(2)CaCu(2)O(8 + delta)

The vortex-matter 3D to 2D phase transition is studied in micron-sized Bi(2)Sr(2)CaCu(2)O(8 + delta) single crystals using local Hall magnetization measurements. At a given temperature, the second magnetization peak, the signature of a possible 3D--2D vortex phase transition, disappears for samples smaller than a critical length. We suggest that this critical length should be equated with the 2D vortex lattice ab-plane correlation length R(2D)(c). The magnitude and temperature dependence of R(2D)(c) agree well with Larkin-Ovchinnikov collective pinning theory.

Extraosseous epidural IgD myeloma presenting with compression myelopathy

An 85-year-old man presented with acute transverse myelopathy: flaccid paraplegia, superficial and deep sensory disturbance below Th6 and loss of urinary sensation. Spinal magnetic resonance image showed an epidural mass compressing the spinal cord at the level of C7 to Th2. Immunoelectrophoresis revealed the presence of immunoglobulin D (IgD)-lambda M protein. Chemotherapy markedly improved both the haematologic aspect and tumor size, but not the motor deficit. In IgD myeloma, extraosseous spreads occur frequently, but extraosseous epidural tumors causing compression myelopathy are relatively rare. To our knowledge, this is the fourth report of cases.

Applicability of Fractals to the Analysis of the Projection of Small Flocs

The validity of the concept of fractal structure for the analysis of the projection of small flocs was examined using the data obtained from a table-tennis-ball simulation and a coagulation experiment with polystyrene latex particles. Two methods defining a fractal dimension, the box-counting technique and the enumeration of primary particles in an enclosing circle as a function of the radius, were tested for the result of numerical simulations. Comparison of the two results revealed their qualitative tendencies and the limits of their applicability. The projection of flocs was also examined using the relation between the maximum distance in the projected floc, Dm, and the number of primary particles composing the floc, i. The decrease of fractal dimension, D, in the lower limit of i was demonstrated both numerically and experimentally. Copyright 1998 Academic Press.

[An elderly case of pneumothorax treated with omentopexy]

A 74-year-old male was admitted to our hospital because of left pneumothorax with persistent air leakage. He had undergone negative pressure drainage, chemical pleurodesis and transbronchial embolization in another hospital. Chest X-ray and CT scan showed collapse of the left lung and a defect of the pleura in the left lung S9. Patch closure was performed for the round pleurobronchial fistula (35 x 35 mm in size) using polyglycol acid felt and fibrin glue. But as severe air leakage was observed again about 24 hours after surgery, omentopexy was performed. The postoperative course was uneventful, and he was discharged 17 days after the second surgery.