Deriving Large Coronal Magnetic Loop Parameters Using LOFAR J Burst Observations

Large coronal loops around one solar radius in altitude are an important connection between the solar wind and the low solar corona. However, their plasma properties are ill-defined, as standard X-ray and UV techniques are not suited to these low-density environments. Diagnostics from type J solar radio bursts at frequencies above 10 MHz are ideally suited to understand these coronal loops. Despite this, J-bursts are less frequently studied than their type III cousins, in part because the curvature of the coronal loop makes them unsuited for using standard coronal density models. We used LOw-Frequency-ARray (LOFAR) and Parker Solar Probe (PSP) solar radio dynamic spectrum to identify 27 type III bursts and 27 J-bursts during a solar radio noise storm observed on 10 April 2019. We found that their exciter velocities were similar, implying a common acceleration region that injects electrons along open and closed magnetic structures. We describe a novel technique to estimate the density model in coronal loops from J-burst dynamic spectra, finding typical loop apex altitudes around 1.3 solar radius. At this altitude, the average scale heights were 0.36 solar radius, the average temperature was around 1 MK, the average pressure was 0.7mdyncm−2, and the average minimum magnetic field strength was 0.13 G. We discuss how these parameters compare with much smaller coronal loops

Use of video laryngoscopes by inexperienced personnel in difficult intubations

The current gold standard in securing airway patency remains to be endotracheal intubation. It is the only method, which allows for nearly 100% protection of the bronchial tree from aspiration of gastric contents as well as providing the most ideal circumstances for control of ventilation parameters. Endotracheal intu- bation, although in many aspects superior to other methods of securing airways, can only be performed by skilled and experienced personnel in ideal conditions. An example of such conditions are in an operating room in the preoperative period when an anesthesiologist is able to proficiently perform the task with all of the tools and equipment needed at hand. However, in many situations, especially in emergencies, such ideal conditions are difficult or impossible to achieve. One of the many reasons behind this is often the lack of experienced personnel at the scene of an emergency. Another significant difficulty arises from trauma patients who must maintain an immobilized cervical spine, as well as those patients who are undergoing active cardiopulmonary resuscitation when providing high quality chest compressions is the highest priority. Therefore, it seems reasonable to look for the methods which on one hand will secure an airway with a tube inserted directly into the larynx, and on the other hand will make the procedure more accessible to less expe- rienced personnel by maintaining the proper patient safety throughout the whole procedure. A noteworthy method, which achieves this goal, is the use of the video laryngoscopes for endotracheal intubation. The participation in a short introductory training, regarding the use of the device itself, is sufficient to allow for the efficient intubation. The parameters which can be used to compare these different intubation methods include the ease of use, the rate of effectiveness of the first intubation trial as well as the total time needed for the procedure. The authors of this article attempt to compare classic laryngoscopes to video-assisted laryngoscopes. 

AUTOMATIC PROXY GENERATION AND LOAD-BALANCING-BASED DYNAMIC CHOICE OF SERVICES

The paper addresses the issues of invoking services from within workflows which are becoming an increasingly popular paradigm of distributed programming. The main idea of our research is to develop a facility which enables load balancing between the available services and their instances. The system consists of three main modules: a proxy generator for a specific service according to its interface type, a proxy that redirects requests to a concrete instance of the service and load-balancer (LB) to choose the least loaded virtual machine (VM) which hosts a single service instance. The proxy generator was implemented as a bean (in compliance to EJB standard) which generates proxy according to the WSDL service interface description using XSLT engine and then deploys it on a GlassFish application server using GlassFish API, the proxy is a BPEL module and load-balancer is a stateful Web Service

Interpretation of Radio Wave Scintillation Observed through LOFAR Radio Telescopes

Radio waves propagating through a medium containing irregularities in the spatial distribution of the electron density develop fluctuations in their intensities and phases. In the case of radio waves emitted from astronomical objects, they propagate through electron density irregularities in the interstellar medium, the interplanetary medium, and Earth’s ionosphere. The LOFAR radio telescope, with stations across Europe, can measure intensity across the VHF radio band and thus intensity scintillation on the signals received from compact astronomical objects. Modeling intensity scintillation allows the estimate of various parameters of the propagation medium, for example, its drift velocity and its turbulent power spectrum. However, these estimates are based on the assumptions of ergodicity of the observed intensity fluctuations and, typically, of weak scattering. A case study of single-station LOFAR observations of the strong astronomical source Cassiopeia A in the VHF range is utilized to illustrate deviations from ergodicity, as well as the presence of both weak and strong scattering. Here it is demonstrated how these aspects can lead to misleading estimates of the propagation medium properties, for example, in the solar wind. This analysis provides a method to model errors in these estimates, which can be used in the characterization of both the interplanetary medium and Earth’s ionosphere. Although the discussion is limited to the case of the interplanetary medium and Earth’s ionosphere, its ideas are also applicable to the case of the interstellar medium

TACTICAL MEDICINE INSPIRING CIVILIAN RESCUE MEDICINE IN THE MANAGEMENT OF HAEMORRHAGE

   Accidents remain to be the most common cause of death amongst men of ages 10–39 and women of ages 5–24. The sudden occurrence of simultaneous multiple events or a mass casualty event with many patients suffering severe injuries, including severe haemorrhage, requires emergency medical personnel to modify the algorithms, which dictate their actions. The military war mission in Iraq and Afghanistan brought many experiences, which were used and applied to guidelines, which are now used for the management of patients experiencing trauma in the civilian sector. The current trauma ITLS (International Trauma Life Support) guidelines suggest to use compression bands or haemostatic dressings in order to control bleeding in case of massive haemorrhage. An example of this recommendation being used can be seen in the regional par­amedic station in Poznan, Poland, where each ambulance is outfitted with “rescue packages” to be used in the event of massive haemorrhage. This practice can also be seen in Great Britain as well as Germany, where local protocols recommend the use of medical equipment taken from tactical medicine. The use of such tools allows for achieving a greater chance of rapid and effective haemostatic control in the event of massive haemorrhaging. These tools allow for more efficient use of time at the scene of the event, reducing the time a patient spends at the scene, allowing more rapid transport to hospital and more specialised surgical support. Reducing the time spent at the scene of an event while carrying out important procedures such as stabilising the patient’s airway, stopping haemorrhage and immobilising the patient, markedly improves the survival of trauma patients

Interferometric imaging with LOFAR remote baselines of the fine structures of a solar type-IIIb radio burst

Context. Solar radio bursts originate mainly from high energy electrons accelerated in solar eruptions like solar flares, jets, and coronal mass ejections. A sub-category of solar radio bursts with short time duration may be used as a proxy to understand wave generation and propagation within the corona.Aims. Complete case studies of the source size, position, and kinematics of short term bursts are very rare due to instrumental limitations. A comprehensive multi-frequency spectroscopic and imaging study was carried out of a clear example of a solar type IIIb-III pair.Methods. In this work, the source of the radio burst was imaged with the interferometric mode, using the remote baselines of the LOw Frequency ARray (LOFAR). A detailed analysis of the fine structures in the spectrum and of the radio source motion with imaging was conducted.Results. The study shows how the fundamental and harmonic components have a significantly different source motion. The apparent source of the fundamental emission at 26.56 MHz displaces away from the solar disk center at about four times the speed of light, while the apparent source of the harmonic emission at the same frequency shows a speed of <0.02 c. The source size of the harmonic emission observed in this case is smaller than that in previous studies, indicating the importance of the use of remote baselines.Peer reviewe

Lensing from small-scale travelling ionospheric disturbances observed using LOFAR

Observations made using the LOw-Frequency ARray (LOFAR) between 10:15 and 11:48 UT on the 15th of September 2018 over a bandwidth of approximately 25-65 MHz contain discrete pseudo-periodic features of ionospheric origin. These features occur within a period of approximately 10 min and collectively last roughly an hour. They are strongly frequency dependent, broadening significantly in time towards the lower frequencies, and show an overlaid pattern of diffraction fringes. By modelling the ionosphere as a thin phase screen containing a wave-like disturbance, we are able to replicate the observations, suggesting that they are associated with small-scale travelling ionospheric disturbances (TIDs). This modelling indicates that the features observed here require a compact radio source at a low elevation and that the TID or TIDs in question have a wavelength <~30 km. Several features suggest the presence of deviations from an idealised sinusoidal wave form. These results demonstrate LOFAR-s capability to identify and characterise small-scale ionospheric structures

Exploring the Circular Polarisation of Low-Frequency Solar Radio Bursts with LOFAR

The Sun is an active star that often produces numerous bursts of electromagnetic radiation at radio wavelengths. Low frequency radio bursts have recently been brought back to light with the advancement of novel radio interferometers. However, their polarisation properties have not yet been explored in detail, especially with the Low Frequency Array (LOFAR), due to difficulties in calibrating the data and accounting for instrumental leakage. Here, using a unique method to correct the polarisation observations, we explore the circular polarisation of different sub-types of solar type III radio bursts and a type I noise storm observed with LOFAR, which occurred during March-April 2019. We analysed six individual radio bursts from two different dates. We present the first Stokes V low frequency images of the Sun with LOFAR in tied-array mode observations. We find that the degree of circular polarisation for each of the selected bursts increases with frequency for fundamental emission, while this trend is either not clear or absent for harmonic emission. The type III bursts studied, that are part of a long-lasting type III storm, can have different senses of circular polarisation, occur at different locations and have different propagation directions. This indicates that the type III bursts forming a classical type III storm do not necessarily have a common origin, but instead they indicate the existence of multiple, possibly unrelated acceleration processes originating from solar minimum active regions.Peer reviewe