Photon scattering by an electric field in noncommutative spacetime

Abstract As is known, the existence of a small noncommutativity between coordinates would generate nonlocal self-interactions in the electromagnetic theory. To explore some consequences of this effect on the propagation of photons we consider Moyal space half-filled with a static and homogeneous electric field and analyze electromagnetic fluctuations on top of this step-like background. Both the localization of photons and the possibility of photon production by strong electric fields are addressed. Several aspects of the Klein paradox in this setup are discussed as well

Assessment of right ventricular function by three-dimensional echocardiography and myocardial strain imaging in adult atrial septal defect before and after percutaneous closure

Real-time three-dimensional (3D) echocardiography allows us to measure right ventricular (RV) end-diastolic volume irrespective of its shape. Tissue Doppler imaging (TDI) and speckle tracking imaging (STI) are new tools to assess myocardial function. We sought to evaluate RV function by 3D echocardiography and myocardial strain imaging in adult patients with atrial septal defect (ASD) before and 6 months after transcatheter closure in order to assess the utility of these new indexes in comparison with standard two-dimensional (2D) and Doppler parameters. Thirty-nine ASD patients and 39 healthy age- and sex-matched controls were studied using a commercially available cardiovascular ultrasound system. 2D-Doppler parameters of RV function (fractional area change, tricuspid annular plane systolic excursion, myocardial performance index) were calculated. 3D RV volumes were also obtained. RV peak-systolic velocities, peak-systolic strain, and peak systolic and diastolic strain-rate were measured in the basal, mid and apical segments of lateral and septal walls in apical 4-chamber view by TDI and STI. In open ASD, RV ejection fraction (3D-RVEF) and global and regional RV longitudinal strain were significantly higher than control group and decreased significantly after closure. By multivariate analysis 3D-RVEF, apical strain and strain rate were independent predictors of functional class. ROC analysis showed 3D-RVEF and apical strain to be more sensitive predictors of unfavorable outcome after defect closure compared to 2D-Doppler indexes. 3D echocardiography and myocardial strain imaging give useful insights in the quantitative assessment of RV function in ASD patients before and after closure

Internet and social media use among patients with colorectal diseases (ISMAEL): a nationwide survey

Aim: Social media are used daily by both healthcare workers and patients. Online platforms have the potential to provide patients with useful information, increase their engagement and potentially revolutionize the patient-physician relationship. This survey aimed to evaluate the impact of the Internet and social media (I&SM) on patients affected by colorectal and proctological diseases to define a pathway to develop an evidence-based communications strategy. Method: A 31-item anonymous electronic questionnaire was designed. It consisted of different sections concerning demographics and education, reason for the visit, knowledge of the diseases, frequency of I&SM use and patients' opinions about physicians' websites. Results: Over a 5-month period, 37 centres and 105 surgeons took part in the survey, and a total of 5800 patients enrolled. Approximately half of them reported using the Internet daily, and 74.6% of the study population used it at least once per week. There was a correlation (P < 0.001) between those who used the Internet for work and those who had knowledge of both symptoms and the likely diagnosis before consultation. Patients who used the Internet daily were more likely to request a consultation within 6 months of symptom onset (P < 0.0001). Patients with anorectal diseases were more likely to know about their disease and symptoms before the visit (P < 0.001). Conclusion: Colorectal patients use I&SM to look for health-related information mainly after their medical visit. Surgeons and hospital networks should plan a tailored strategy to increase patient engagement, delivering appropriate information on social medi