Tight Bounds for On-line Tree Embedding

Many tree–structured computations are inherently parallel. As leaf processes are recursively spawned they can be assigned to independent processors in a multicomputer network. To maintain load balance, an on–line mapping algorithm must distribute processes equitably among processors. Additionally, the algorithm itself must be distributed in nature, and process allocation must be completed via message–passing with minimal communication overhead. This paper investigates bounds on the performance of deterministic and randomized algorithms for on–line tree embedding. In particular, we study tradeoffs between performance (load–balance) and communication overhead (message congest ion). We give a simple technique to derive lower bounds on the congestion that any on–line allocation algorithm must incur in order to guarantee load balance. This technique works for both randomized and deterministic algorithms, although we find that the performance of randomized on-line algorithms to be somewhat better than that of deterministic algorithms. Optimal bounds are achieved for several networks including multi–dimensional grids and butterflies

New Spirometry Indices for Detecting Mild Airflow Obstruction.

The diagnosis of chronic obstructive pulmonary disease (COPD) relies on demonstration of airflow obstruction. Traditional spirometric indices miss a number of subjects with respiratory symptoms or structural lung disease on imaging. We hypothesized that utilizing all data points on the expiratory spirometry curves to assess their shape will improve detection of mild airflow obstruction and structural lung disease. We analyzed spirometry data of 8307 participants enrolled in the COPDGene study, and derived metrics of airflow obstruction based on the shape on the volume-time (Parameter D), and flow-volume curves (Transition Point and Transition Distance). We tested associations of these parameters with CT measures of lung disease, respiratory morbidity, and mortality using regression analyses. There were significant correlations between FEV1/FVC with Parameter D (r = -0.83; p < 0.001), Transition Point (r = 0.69; p < 0.001), and Transition Distance (r = 0.50; p < 0.001). All metrics had significant associations with emphysema, small airway disease, dyspnea, and respiratory-quality of life (p < 0.001). The highest quartile for Parameter D was independently associated with all-cause mortality (adjusted HR 3.22,95% CI 2.42-4.27; p < 0.001) but a substantial number of participants in the highest quartile were categorized as GOLD 0 and 1 by traditional criteria (1.8% and 33.7%). Parameter D identified an additional 9.5% of participants with mild or non-recognized disease as abnormal with greater burden of structural lung disease compared with controls. The data points on the flow-volume and volume-time curves can be used to derive indices of airflow obstruction that identify additional subjects with disease who are deemed to be normal by traditional criteria

Terahertz Detectors (THzDs): Bridging the Gap for Energy Harvesting

It is indispensable to integrate electronics with environment for better lives. Huge amount of solar energy, dark energy, and unused microwave energy is untapped till now due to insufficient availability of high frequency THz detectors. The difference between THz wave detection and THz electric field detection must be clear. THz wave detection connects the detection of explosives, drugs, astronomy, metals, and imaging applications, etc. On the other hand, THz electric field detection involves the conversion of electromagnetic (EM) radiations to usable DC power. The optimum choice of detectors for energy harvesting is a highly diverse area. The latter part is concentrated on the nonlinear behavior of the incoming radiations and has been highlighted also. In this chapter, metal‐insulator‐metal (MIM) diode detectors have been explored to become a best choice for high frequency detectors

A 64-Year-Old Man with Low Back Pain Due to Clostridium perfringens Lumbar Discitis

Lumbar discitis caused by Clostridium perfringens is extremely rare. There have only been 7 published cases of confirmed discitis caused by Clostridium perfringens. We write this report to underscore this unusual relationship by discussing an additional case and providing a review of the previously published cases so clinicians can adequately evaluate and treat patients presenting with discitis. CASE REPORT A 64-year-old morbidly obese man presented with an acute onset of worsening back pain and generalized weakness after incurring physical trauma related to falling. Additionally, he also developed fever and chills before the presentation. Based on the clinical presentation and elevated serum levels of inflammatory markers, magnetic resonance imaging was ordered, which showed L5-S1 discitis with extension of infection into the epidural space. Fluoroscopy-guided aspiration of the L5-S1 epidural space facilitated the detection of Clostridium perfringens as the involved pathogen. Based on the antibiotic susceptibility report, the patient was treated with intravenous ampicillin for 8 weeks, after which his symptoms resolved. CONCLUSIONS Diagnosis of discitis can be very challenging due to its ambiguous clinical presentation, especially in the elderly population due to the presence of underlying degenerative changes. Even though Clostridium perfringens remains a rare cause of lumbar discitis, it should be considered as a pathogen capable of causing infection of the vertebrae and intervertebral discs, thus allowing clinicians to make necessary diagnostic evaluations to provide appropriate targeted treatment to patients presenting with discitis

Venous thromboembolism and COVID-19: a case report and review of the literature

Background: Currently, there is minimal data available highlighting the prevalence of venous thromboembolism in patients infected with coronavirus disease 2019 (COVID-19). This case report with a literature review emphasizes a unique presentation of COVID-19 that is highly important for health care providers to consider when treating their patients. Case report: A 65-year-old Caucasian male patient presented to the emergency department with a 2-day history of dyspnea on exertion after his wife’s recent diagnosis of COVID-19. He additionally had experienced a couple of episodes of self-resolving diarrhea a few days before presentation. Based on the patient’s clinical presentation and the laboratory workup identifying an elevated D-dimer, a computed tomography angiogram of the chest was obtained, which was significant for moderately large, bilateral pulmonary emboli with a saddle embolus, and an associated small, left lower lobe, pulmonary infarct. Ultrasound of the lower extremity showed non-occlusive deep vein thrombosis at the distal left femoral vein to the left popliteal vein. The patient was additionally diagnosed with COVID-19 when the results of the COVID-19 polymerase chain reaction test returned as positive. The patient was admitted to the COVID unit, and he was started on an intravenously administered, unfractionated heparin drip for management of his bilateral pulmonary emboli and deep vein thrombosis. The patient’s clinical condition improved significantly with anticoagulation, and he was observed in the hospital for 3 days, after which he was discharged home on the enoxaparin bridge with warfarin. Post-discharge telephone calls at day 10 and week 4 revealed that the patient was appropriately responding to anticoagulation treatment and had no recurrence of his symptoms related to venous thromboembolism and COVID-19. Conclusion: As COVID-19 continues to lead to significant mortality, more data is emerging that is exposing its perplexing pathogenicity. Meanwhile, the presentation of venous thromboembolism in patients with COVID-19 remains an unusual finding. It is imperative for health care providers to be mindful of this unique association to make necessary diagnostic evaluations and provide appropriate treatment for the patients

The ethical dilemma of ventilator sharing during the COVID-19 pandemic

Ventilator sharing, an ethically challenging and difficult decision for the healthcare providers to make, has emerged due to scarce medical supplies during the COVID-19 pandemic. Healthcare professionals find themselves tangled in the ethical complexity of ventilator sharing at every step – selecting patients, maintaining patient privacy, using appropriate ventilator settings, and avoiding complications. It becomes hard to morally answer questions related to ventilator sharing due to a lack of scientific research in this regard

Acute electrocardiographic changes during smoking: An observational study

Objective To study the temporal relationship of smoking with electrophysiological changes. Design Prospective observational study. Setting Tertiary cardiac center. Participants Male smokers with atypical chest pain were screened with a treadmill exercise test (TMT). A total of 31 such patients aged 49.8±10.5 years, in whom TMT was either negative or mildly positive were included. Heart rate variability (HRV) parameters of smokers were compared to those of 15 healthy non-smoking participants. Interventions All patients underwent a 24 h Holter monitoring to assess ECG changes during smoking periods. Results Heart rate increased acutely during smoking. Mean heart rate increased from 83.8±13.7 bpm 10 min before smoking, to 90.5±16.4 bpm during smoking, (p <0.0001) and returned to baseline after 30 min. Smoking was also associated with increased ectopic beats (mean of 5.3/h prior to smoking to 9.8/h during smoking to 11.3/h during the hour after smoking; p <0.001). Three patients (9.7%) had significant ST–T changes after smoking. HRV index significantly decreased in smokers (15.2±5.3) as compared to non-smoking controls participants (19.4±3.6; p=0.02), but the other spectral HRV parameters were comparable. Conclusions Heart rate and ectopic beats increase acutely following smoking. Ischaemic ST–T changes were also detected during smoking. Spectral parameters of HRV analysis of smokers remained in normal limits, but more importantly geometrical parameter—HRV index—showed significant abnormality