Brokerage rents and intermediation networks.

This paper provides experimental evidence on the economic determinants of intermediation networks by considering two pricing rules-respectively, criticality and betweenness-and three group sizes of subjects-10, 50, and 100 subjects. We find that when brokerage benefits accrue only to traders who lie on all paths of intermediation, stable networks involve interconnected cycles, and trading path lengths grow while linking and payoff inequality remain modest as the number of traders grows. By contrast, when brokerage benefits are equally distributed among traders on the shortest paths, stable networks contain a few hubs that provide the vast majority of links, and trading path lengths remain unchanged while linking and payoff inequality explode as the number of traders grows.

Quantitative assessment and mitigation measures of air pollution from crematoria in NCT of Delhi.

The modernization of crematoria and replacement of existing fuel requirements for better air quality is a key challenge in view of the associated religious beliefs in India where conventional open pyre funeral practices are followed. Unlike developed nations, the lack of appropriate site selection criteria, combustion efficient crematorium oven designs, and pollution control devices at these facilities necessitates formulation of appropriate policy measures to reduce emissions. The existing practices do not address such localized sources that affects the micro air pollution patterns owing to their marginal contribution in the total air pollution load of the city. The present study is thus an attempt to estimate emissions from 51 cremation grounds identified in NCT of Delhi. The study considers both particulate and gaseous pollutants which are released due to burning of fuels like wood, CNG, and cow dung. It is estimated that cremation activities contributed 393 tons/year of PM2.5, 142 tons/year of NOx, 29 tons/year of SO2, and 2686 tons/year of CO in year 2019. The maximum load was emitted from Central district as only Nigambodh Ghat crematoria receives on an average 60 bodies per day. Furthermore, air quality impact zone around crematoria has been demarcated using dispersion modelling considering crematorium with minimum and maximum number of bodies burnt in a day. The study also suggests control measures for reduction of pollution from cremation activities and delineates a buffer zone that could aid policymakers in establishing a site selection criterion to prevent the immediate population from likely exposure.

Tale of fat and fib - cardiac lipoma managed with radiofrequency ablation: A case report.

BACKGROUND: Cardiac lipoma and lipomatous hypertrophy of interatrial septum (LHIS) are very rare disorders with distinct pathological features. While cardiac lipoma is a well-circumscribed encapsulated tumor of mature adipocytes, LHIS is due to entrapment of fat cells in the interatrial septum during embryogenesis. Although a biopsy is the definitive diagnostic test, these disorders can be differentiated by a cardiac magnetic resonance imaging (MRI). Treatment of LHIS is not warranted in asymptomatic patients. In symptomatic patients, surgical resection is the only recommended treatment, which has shown to improve good long-term prognosis. CASE SUMMARY: A 63-year-old Caucasian woman with past medical history significant for hypertension, hypothyroidism, right breast ductal cell carcinoma treated with mastectomy and breast implant, platelet granule disorder, asthma requiring chronic intermittent prednisone use, presented to the outpatient cardiology office with recent onset exertional dyspnea, palpitations, weight gain and weakness. Initial workup with electrocardiogram and holter monitor did not reveal significant findings. During the subsequent hospitalization for community acquired pneumonia, the patient developed symptomatic paroxysmal atrial fibrillation. Transthoracic echocardiogram showed a right ventricular mass. A biopsy was not pursued given the high risk of bleeding due to platelet granule disorder. Cardiac MRI showed characteristic features consistent with cardiac lipoma and LHIS. Prednisone was discontinued. Genetic testing for arrhythmogenic right ventricular dysplasia and 24-h urine cortisol test was negative. As multiple attempts at rhythm control failed with sotalol and flecainide, pulmonary vein isolation and right atrial isthmus radiofrequency ablation were done. She is in follow-up with symptomatic relief and no recurrence of atrial fibrillation for 10 mo. CONCLUSION: Benign fatty lesions in heart include solitary lipoma, lipomatous infiltration and lipomatous hypertrophy of interatrial septum. Although transvenous biopsy provides a definitive diagnosis, Cardiac MRI is superior to computed tomography and aids in differentiating benign from malignant lesions. Surgical excision of cardiac lipoma along with capsule and pedicle removal generally prevents recurrence, but with our patient's unusual tumor features and comorbidities proscribed a surgical approach. Symptom management with antiarrhythmics and ablation techniques were successfully utilized.

Effect of network topology and node centrality on trading.

Global supply networks in agriculture, manufacturing, and services are a defining feature of the modern world. The efficiency and the distribution of surpluses across different parts of these networks depend on the choices of intermediaries. This paper conducts price formation experiments with human subjects located in large complex networks to develop a better understanding of the principles governing behavior. Our first experimental finding is that prices are larger and that trade is significantly less efficient in small-world networks as compared to random networks. Our second experimental finding is that location within a network is not an important determinant of pricing. An examination of the price dynamics suggests that traders on cheapest-and hence active-paths raise prices while those off these paths lower them. We construct an agent-based model (ABM) that embodies this rule of thumb. Simulations of this ABM yield macroscopic patterns consistent with the experimental findings. Finally, we extrapolate the ABM on to significantly larger random and small-world networks and find that network topology remains a key determinant of pricing and efficiency.

Assessment of the effectiveness of policy interventions for Air Quality Control Regions in Delhi city.

Government has implemented various scattered and un-quantified control actions in Delhi city to reduce the air pollution levels; however, it still exceeds the National Ambient Air Quality Standards (NAAQS). The present study has been designed to assess the air quality status, identify Air Quality Control Region (AQCR), and evaluate control strategies in the city. Out of eight selected locations, ambient PM10, PM2.5, and NO2 concentrations were found exceeding the daily as well as annual standards at selected AQCR with peak levels during post-monsoon than winter and summer. Anand Vihar was found to be most polluted and thus, selected as an AQCR. AERMOD performed satisfactorily in predicting pollutant concentration during winter and summer having an index of agreement in the range 0.54-0.80. PM10 and PM2.5 can be reduced substantially by increasing frequency of efficient mechanized cleaning of roads and sprinkling of water on the roads. Progressive decrease in NO2 concentrations can be achieved by restricting entry of truck in the study area through alternate path. The cumulative impact of all selected control strategies indicates a substantial decrease in air pollution within AQCR. The study also suggests a policy framework to manage the urban air quality through local scale air quality guidelines.

Mouse heart rate in a human: diagnostic mystery of an extreme tachyarrhythmia.

We report telemetry recording of an extreme non-fatal tachyarrhythmia noted in a hospitalized quadriplegic male with history of atrial fibrillation where the average ventricular conduction rate was found to be about 600 beats per minute and was associated with transient syncope. A medical literature review suggests that the fastest human ventricular conduction rate reported to date in a tachyarrhythmia is 480 beats per minute. We therefore report the fastest human heart rate noted in a tachyarrhythmia and the most probable mechanism of this arrhythmia being a rapid atrial fibrillation with 1:1 conduction in the setting of probable co-existing multiple bypass tracts.

Mutation in the S3 segment of KCNQ1 results in familial lone atrial fibrillation.

BACKGROUND: Mutations in several ion channel genes have been reported to cause rare cases of familial atrial fibrillation (AF). OBJECTIVE: The purpose of this study was to determine the genetic basis for AF in a family with autosomal dominant AF. METHODS: Family members were evaluated by 12-lead ECG, echocardiogram, signal-averaged P-wave analysis, and laboratory studies. Fourteen family members in AF-324 were studied. Six individuals had AF, with a mean age at onset of 32 years (range 16-59 years). RESULTS: Compared with unaffected family members, those with AF had a longer mean QRS duration (100 vs 86 ms, P = .015) but no difference in the corrected QT interval (423 +/- 15 ms vs 421 +/- 21 ms). The known loci for AF and other cardiovascular diseases were evaluated. Evidence of linkage was obtained with marker D11S4088 located within KCNQ1, and a highly conserved serine in the third transmembrane region was found to be mutated to a proline (S209P). Compared to the wild-type channel, the S209P mutant activates more rapidly, deactivates more slowly, and has a hyperpolarizing shift in the voltage activation curve. A fraction of the mutant channels are constitutively open at all voltages, resulting in a net increase in I(Ks) current. CONCLUSION: We identified a family with lone AF due to a mutation in the highly conserved S3 domain of KCNQ1, a region of the channel not previously implicated in the pathogenesis of AF.

Optimization of superior vena cava coil position and usage for transvenous defibrillation.

BACKGROUND: Prior studies of active pectoral implantable defibrillator (ICD) lead systems demonstrated a lowering of defibrillation thresholds (DFTs) with the addition of a superior vena cava (SVC) coil. These studies were done on fixed-tilt waveforms where a large reduction in impedance leads to large phase duration changes. OBJECTIVE: The present study was designed to evaluate the SVC coil benefit and intercoil spacing on DFTs with a "tuned" waveform. METHODS: This prospective, multicenter study included 113 patients randomized at implant to a 17-cm and a 21-cm intercoil spacing ICD lead. DFTs were measured with SVC coil turned ON versus OFF in a random order, using an optimized binary search method. RESULTS: DFT voltage (423 +/- 120 vs. 438 +/- 118 V; P = .042) and stored energy (9.8 +/- 5.6 vs. 10.2 +/- 5.8 J; P = .043) were significantly reduced with the SVC coil ON. However, intercoil distance had no significant effect on DFT voltage (437.3 +/- 115.1 vs. 407.7 +/- 123.8 V; P = .19) or stored energy (10.3 +/- 5.4 vs. 9.2 +/- 5.8 J; P = .31). Subgroup analyses showed that the dual-coil leads were most effective when placed in the high position (innominate vein-SVC junction) or when the single-coil shock impedance was > or =58 Omega, regardless of intercoil spacing. CONCLUSION: With a tuned waveform, the addition of an SVC coil to the shocking pathway reduces DFTs, although this difference was smaller than reported previously. Intercoil distance had no significant effect on the defibrillation parameters.

Cardiac sarcoidosis with primary involvement of the tricuspid valve.

Sarcoid granulomas usually involve the myocardium with rare focal extensions into the pericardium and endocardium with resultant conduction defects, ventricular arrhythmias, and ventricular systolic and diastolic dysfunction. Primary involvement of valvular leaflets resulting in valvular regurgitation or stenosis is not known. We present a case of a wastewater consultant who developed tricuspid regurgitation and symptomatic atrioventricular block secondary to infiltration of tricuspid leaflets and conduction system from sarcoid granulomas. The patient later developed severe dilated cardiomyopathy as a result of extensive cardiac sarcoidosis necessitating cardiac transplantation. Valvular regurgitation should be included as one of the presenting manifestations of cardiac sarcoidosis.

Persistent left superior vena cava-inferior vena caval communication complicating implantation of an implantable cardioverter defibrillator.

A persistent left superior vena cava has been observed in 0.3% of the general population on autopsy. Its presence can complicate left-sided device implantation. Commonly, a LSVC connects to the right atrium via the coronary sinus. A LSVC-accessory hemiazygous-hemiazygous-inferior vena caval communication has not been described previously. The presence of such a congenital venous anomaly will prohibit a left-sided device implant.

Inappropriate ICD therapy due to proarrhythmic ICD shocks and hyperpolarization.

A 50-year-old man with an ischemic cardiomyopathy underwent ICD implantation for inducible ventricular fibrillation (VF). Sixteen months later he experienced inappropriate ICD therapy due to atrial fibrillation with a rapid ventricular response. The initial shock resulted in the initiation of VF (proarrhythmia) and the patient received an additional shock converting his rhythm to an idioventricular rhythm with a cycle length of 490 ms (122 beats/min). Due to lead hyperpolarization, the device oversensed ventricular events and the patient subsequently received additional shocks.