Identifying the spatiotemporal organization of high-traffic events in a mobile communication system using event synchronization and complex networks.

In mobile communication systems, congestion is related to high-traffic events (HTEs) that occur in the coverage areas of base stations. Understanding, recognizing, and predicting these HTEs and researching their occurrence rules provides theoretical and decision-making support for preventing system congestion. Communication sectors are regarded as nodes, and if HTEs occur synchronously among sectors, then the corresponding nodes are connected. The total number of synchronous HTEs determines the edge weights. The mobile-communication spatiotemporal data are mapped to a weighted network, with the occurrence locations of HTEs as the basic elements. Network analysis provides a structure for representing the interaction of HTEs. By analyzing the topological features of the event synchronization network, the associations among the occurrence times of HTEs can be mined. We find that the event synchronization network is a small-world network, the cumulative strength distribution is exponential, and the edge weight obeys a power law. Moreover, the node clustering coefficient is negatively correlated with the node degree. A congestion coefficient based on several topological parameters is proposed, and the system congestion is visualized. The congestion coefficient contains information about the synchronous occurrence of HTEs between a sector and its neighbors and information about the synchronous occurrence of HTEs among its neighbors. For the mobile communication system considered in this study, the congestion coefficient of a large number of sectors is small and the risk of system congestion is low.

The prevalence of neovascularity in rotator cuff tendinopathy: comparing conventional Doppler with superb microvascular imaging.

AIMS: To determine the prevalence of neovascularity in the supraspinatus tendon of patients presenting with clinically painful unilateral rotator cuff tendinopathy (RCT) using conventional colour Doppler ultrasound (CDU), power Doppler ultrasound (PDU), and superb microvascular imaging (SMI). The association between Doppler findings and clinical scores was also assessed. METHODS: The bilateral supraspinatus of consecutive patients presented with unilateral RCT clinically were evaluated with grey-scale ultrasound (tendon thickening, heterogeneous echotexture, and hypoechogenicity), CDU, PDU, and SMI. The prevalence of neovascularity and grey-scale changes on duplex imaging techniques were analysed. The relationship between neovascularity on CDU, PDU, SMI, and pain/disability as determined using a visual analogue scale (VAS) and the Oxford Shoulder Score (OSS) were assessed. RESULTS: Fifty-nine patients (mean age 53 years, 39 women) were recruited. Of the symptomatic supraspinatus tendons, 42.4% (25/59) demonstrated neovascularity on SMI, compared to 6.8% (4/59) on PDU and 5.1% (3/59) on CDU. Of the asymptomatic supraspinatus tendons, 5.1% (3/59) depicted neovascularity on SMI but not on conventional Doppler techniques. SMI showed a significant correlation with the VAS (r2 = 0.560, p<0.001) and OSS (r2 = 0.62, p<0.001). PDU weakly correlated with the VAS and OSS (r2 = 0.312, p=0.016; r2 = 0.260, p=0.047, respectively) while CDU did not show a significant relationship. CONCLUSION: SMI is superior in demonstrating neovascularity and shows better correlation with pain and functional deficit compared to conventional Doppler in patients with painful RCT. SMI also showed vascularity to a lesser degree in the asymptomatic tendon. Further large-scale studies are needed to prove the diagnostic value of SMI in the assessment of RCT.

A Case Series of Bosworth Fracture-Dislocations and Review of 129 Reported Cases.

Introduction: Bosworth fracture dislocations of the ankle are rare injuries of the ankle caused by extreme external rotation of the supinated foot where the proximal fibula fracture fragment is posteriorly dislocated and entrapped behind the posterior-lateral ridge of the tibia. This case series aims to document three such cases treated in our institution over a nine year period. We also provide a review of 129 cases in the existing literature. Materials and methods: Medical records and relevant radiographs for each patient were analysed and collected from the time of presentation till the point of latest follow-up. During each clinic visit, all physical exam findings as well as all complications were recorded. The American Foot and Ankle Society (AOFAS) Hindfoot score was also tabulated for each patient at the point of latest review. Results: Closed reduction was unsuccessful in all three patients, and all required open reduction. One patient had an uncomplicated recovery whilst the remaining two suffered significant soft tissue complications. One patient suffered severe soft tissue swelling preventing primary closure at the time of surgery, whilst another suffered post-operative wound dehiscence and infection. Eventually all fractures healed, and all three patients obtained satisfactory AOFAS scores. Conclusion: The diagnosis of Bosworth fracture dislocations of the ankle is often delayed or missed, due to its rare occurrence. Closed reduction is often unsuccessful, and early open reduction is required to avoid poor clinical outcomes due to severe soft tissue damage or even compartment syndrome.

May-Thurner Syndrome Results in Life-Threatening Condition: Phlegmasia Cerulea Dolens and Rhabdomyolysis.

Venography alone may underestimate the extent of common iliac vein compression in May-Thurner syndrome. Peripheral intravascular ultrasound is mandatory to better assess common iliac vein compression.

Urschel's Sign in Paget-Schroetter Syndrome: Multimodality Evaluation by Extravascular and Intravascular Imaging.

Paget-Schroetter Syndrome is potentially life-threatening. In this case, multidisciplinary imaging with extravascular and intravascular evaluation guided the proper diagnosis and treatment planning.

Optical Coherence Tomography Evaluation of Superficial Femoral Artery Directional Atherectomy.

To the best of our knowledge, this is the first report of optical coherence tomography evaluation of superficial femoral artery atherectomy in a patient from the Asia-Pacific region. We demonstrate the feasibility of this technique in Chinese populations.

An unusual case of anomalous origin of the right coronary artery and hepatic focal nodular hyperplasia.

Anomalous origin of the right coronary artery (ARCA) and focal nodular hyperplasia (FNH) are frequently reported in association with congenital heart abnormalities but not with each other. We propose that both conditions may share common origins in a maladative hyperplastic response to differential vascular flow due to developmental arterial malformations or aberrant Notch signalling during simultaneous gut and cardiac vasculorigenesis.

Self-reported symptoms in patients on antiepileptic drugs in monotherapy.

OBJECTIVE: To ascertain the frequency of self-reported symptoms in patients taking antiepileptic drugs (AED). METHODS: We included patients on carbamazepine (CBZ) n = 36, valproate (VPA) n = 21, levetiracetam (LEV) n = 12, phenytoin (PHT) n = 11, lamotrigine (LTG) n = 20, patients not taking anticonvulsive drugs n = 19, and healthy control subjects (CTRL) n = 41 to complete the Liverpool Adverse Event Profile (LAEP). RESULTS: The mean LAEP scores were CBZ/PHT/LEV/VPA/LTG/noAED/CTRL = 44.97/42.00/41.00/40.33/32.42/42.00/30.80. LEV scored overall in the same range as the older AED but had a different adverse effect profile with self-reported anger (33%) and shaky hands (42%) particularly frequent. Patients with depression or uncontrolled epilepsy had significantly higher LAEP scores than patients without depression or uncontrolled epilepsy. CONCLUSION: Our unblinded observational study of self-reported symptoms suggested LTG was overall the drug with the least self-reported symptoms. Larger studies are needed to determine whether this was a truly significant difference. LEV had a different side effect profile to older AED. Confounding factors were depression and uncontrolled epilepsy. This observation should be further tested with randomized studies.

Distally pedicled peroneus brevis muscle flap: a versatile lower leg and foot flap.

INTRODUCTION: The purpose of this study was to evaluate the outcome of our early experience with the distally pedicled peroneus brevis flap in the management of soft tissue defects of the lower leg, ankle and foot. METHODS: This was a non-randomised, retrospective study involving five patients who were treated with the peroneus brevis muscle flap for soft tissue defects over the lower leg. RESULTS: In all five patients, the flaps were viable and successful in providing satisfactory soft tissue coverage for the defects. In one diabetic patient, distal flap necrosis was observed, which was treated successfully with a local rotational skin flap. CONCLUSION: The distally pedicled peroneus brevis muscle flap is an economical, reliable and relatively easy procedure for treating defects of the distal third of the leg, ankle and foot.

A comparison of screen-based simulation and conventional lectures for undergraduate teaching of crisis management.

In our institution, we introduced a screen-based simulator to our undergraduate lectures on medical crisis management. We hypothesised that this novel use of the screen-based simulator would be as effective as our conventional lectures. To test this we randomly divided medical students into two groups. Students in Group A were taught medical crisis management (heart failure and anaphylaxis) using a screen-based simulation program projected onto a shared screen, with a facilitator guiding the students through the scenarios. Simultaneously, students in Group B were lectured the same content without the screen-based simulation. Both groups were allotted exactly one hour Several days later, students were tested on their management of anaphylaxis using the Human Patient Simulator. A blinded marker assessed them on diagnosis, resuscitation, specific treatment, call for help and for reassessment of the patient. Students also answered a questionnaire on their experience. Sixty-four students participated in the study. Both groups had similar overall scores. However students in Group A scored better in the specific treatment category by a factor of 1.7. Students in both groups rated their learning experiences highly. This study showed that screen-based simulation was as effective as conventional lectures and might be even more effective in some areas.

Meta-analysis of magnetic resonance imaging studies of the corpus callosum in schizophrenia.

OBJECTIVES: The corpus callosum plays a pivotal role in inter-hemispheric transfer and integration of information. Magnetic resonance studies have reported callosal abnormalities in schizophrenia but findings have been inconsistent. Uncertainty has persisted despite a meta-analytic evaluation of this structure several years ago. We set out to perform a further meta-analysis with the addition of the numerous reports published on the subject to test the hypothesis that the corpus callosum is abnormal in schizophrenia. METHOD: A systematic search was carried out to identify suitable magnetic resonance studies which reported callosal areas in schizophrenia compared to controls. Results from the retrieved studies were compared in a meta-analysis whilst the influence of biological and clinical variables on effect size was ascertained with meta-regression analysis. RESULTS: Twenty-eight studies were identified. Corpus callosum area was reduced in schizophrenia in comparison to healthy volunteers. This effect was larger in first episode patients. Similarly, heterogeneity detected among the studies was associated with course of illness indicating that chronic subjects with schizophrenia showed larger callosal areas. There was no evidence of publication bias. CONCLUSIONS: This study confirms the presence of reduced callosal areas in schizophrenia. The effect is of a larger magnitude at first presentation and less so in subjects with a chronic course generally medicated with antipsychotics.

In vitro effects of local anaesthetics on the thromboelastographic profile of parturients.

BACKGROUND: Post-dural puncture headache can be an incapacitating complication of obstetric epidural analgesia/anaesthesia and early or prophylactic epidural blood patch (EBP) is one of the treatment options. Although local anaesthetic (LA) agents have been shown to have anticoagulation effects in vitro, peri-partum women are known to be hypercoagulable. We postulated that the presence of residual LA might not result in impaired haemostasis of the EBP in parturients. METHODS: Blood samples from 10 healthy term parturients were subjected to thromboelastography after the addition of four different LA (lidocaine, bupivacaine, levobupivacaine, and ropivacaine) preparations. RESULTS: There was a significant reduction in reaction (R) and coagulation (K) time (P<0.001, P<0.05) and an increase in alpha degrees angle (P<0.01) when comparing undiluted blood with the saline control group. Maximum amplitude (MA) and clot lysis (Ly30) did not change significantly despite the 50% dilution. The thromboelastographic parameters of all four LA-treated groups were no different from their saline controls and from each other. CONCLUSION: At clinical dosages, LA did not cause any hypocoagulable changes on the thromboelastographic profile of healthy parturients.

Bronchial diameters in children--use of the Fogarty catheter for lung isolation in children.

The right and left main bronchial diameters of 250 children were measured using computed tomography of the thorax. In 75% of the cases, the right main bronchial diameter was significantly larger than the left (95% CI 0.7-0.9, P<0.01). Age but not weight of a child is a good predictor of the bronchial diameter (Beta value is 2.81x10(-2) and 2.58x10(-2) for right and left main bronchial diameter respectively). A size 3 Fogarty catheter will provide effective bronchial blocking for children up to 4 years old. A size 5 Fogarty catheter can be used for most children from 5 to 12 years old. Larger Fogarty catheters or double-lumen tubes can be used in older children. Overinflation of the cuff should be avoided by fibreoptic bronchoscopy of the balloon. Our clinical application of the technique is discussed.

Teaching first-year medical students physiology: does the human patient simulator allow for more effective teaching?

BACKGROUND: Although the Human Patient Simulator (HPS) is an effective teaching tool in many medical fields, literature supporting its use in the teaching of physiology to medical students is lacking. This study investigated the effectiveness of HPS-based teaching of cardiovascular physiology to first-year medical students. METHODS: Two hundred and ten first-year medical students were scheduled to our HPS laboratory with the purpose of demonstrating "physiology in action". Students were divided into groups of 19-25 each, and attended a lecture followed by a HPS session. Using a theatre-type simulator complete with mannequin, anaesthesia machine and monitors (METI, Sarasota FL), the scenarios of hypovolaemia, sepsis, and cardiac failure were run to demonstrate the physiological changes that occur with changes in preload, afterload, and cardiac contractility. Each student was given a true/false test before, and again after the HPS session, followed by a survey of their learning experience. RESULTS: There was marked improvement in test scores after the HPS session (82.1% vs. 64.6%, P < 0.001). Most of the students felt that HPS was a better teaching tool (94.5%) and raised more questions (76.5%) than lectures. They wanted more topics to be taught this way (96%), as they could apply and re-enforce textbook knowledge, and visualise real-time changes. However, they felt that their experience could have been enhanced with more time and smaller groups. DISCUSSION: HPS is an excellent teaching tool as it stimulates student curiosity and makes knowledge acquisition and understanding easier. It is highly desirable to be incorporated into the teaching of physiology.

Critical incidents in paediatric anaesthesia: an audit of 10 000 anaesthetics in Singapore.

BACKGROUND: We undertook an audit of paediatric perioperative incidents in the first 10000 anaesthetics administered in KK Women's and Children's Hospital in Singapore between May 1997 and April 1999. The spectrum of surgery performed ranged from simple ambulatory surgery to open heart surgery for complicated congenital heart diseases. METHODS: An audit form is completed for every anaesthetic delivered and critical incidents are reported on the reverse blank page of the audit form. An anaesthetic incident was defined as 'any incident which affected, or could have affected, the safety of the patient under anaesthetic care'. RESULTS: Two hundred and ninety-seven critical incidents were reported. The majority of them happened in healthy patients (80.1% ASA I and II) scheduled for elective surgery (73.3%). Critical incidents in infants less than 1 year of age were four times as common as in older children (8.6% versus 2.1%). Incidents occurred mainly during maintenance (80.6%). There was no anaesthetic mortality. Respiratory events were the most common (77.4%) with laryngospasm accounting for 35.7%. Cardiovascular incidents (10.8%) included hypotension from haemorrhage and sepsis, and dysrhythmias. The incidence of equipment and pharmacologically related problems was low. CONCLUSIONS: Future reviews of a larger patient population may be helpful to determine trends of perioperative events and whether quality assurance programs have made a difference.

Experience with video-assisted thoracoscopic surgery in the management of complicated pneumonia in children.

PURPOSE: The aim of this study was to assess the impact of video assisted thoracoscopic surgery (VATS) in the management of empyema in children. METHODS: This report involves cases of complicated pneumonia in children requiring surgical intervention after failure of medical treatment with antibiotics, with or without drainage from November 1997 to October 1999. The impact of VATS has been studied prospectively from October 1998 when VATS was introduced. The results have been compared with the previous year when similar cases were dealt with open thoracotomy. These 2 groups of patients with VATS (V) or without VATS (O) were studied for their progress in hospital and the final outcome. RESULTS: A total of 39 immunocompetent children with community-acquired pneumonia were studied. There were 17 cases in O and 22 in V. There were 2 conversions to open thoracotomy in V. Both of these cases required resection of the lung parenchyma for severe necrosis and bronchopleural fistula. The mean age in years was 5.3 (O) and 4.9 (V). Parameters that were significantly less in V compared with O include timing of referral (O, 13.6 days; V, 5.3 days), number of lung resections (O, 8; V, 2), blood transfusion (O, 14; V, 2), analgesia requirements (O, 7.8 days; V, 2.9 days), postoperative length of stay in hospital (O, 10.4 days; V, 4.6 days), time to become normothermic (O, 5.6 days; V, 1.7 days); and time to removal of chest drains (O, 6.0 days; V, 2.7 days). Cosmesis is superior in cases of VATS compared with open thoracotomy. All the children recovered well on follow-up with resolution of symptoms and no recurrences. CONCLUSIONS: (1) VATS has ushered in a new era of hope for patients with complicated pneumonia. (2) Thoracotomy, lung resections, and the attending morbidity rate have decreased. (3) Patients are being referred earlier by the physicians because the management protocol is changing.

Anaesthesia for tracheoplasty: case report and review of anaesthesia techniques.

Congenital tracheal stenosis is an uncommon cause of stridor and can be associated with other anomalies. It may present anytime during childhood depending on the severity of the lesion. The anaesthetist may be involved in all stages of management of this problem; from diagnostic investigations to surgical correction. Various methods of tracheoplasty have been described, some requiring cardiopulmonary bypass support and others may be carried out with conventional ventilatory techniques.