Ascertainment rate of SARS-CoV-2 infections from healthcare and community testing in the UK

The proportion of SARS-CoV-2 infections ascertained through healthcare and community testing is generally unknown and expected to vary depending on natural factors and changes in test-seeking behaviour. Here we use population surveillance data and reported daily case numbers in the United Kingdom to estimate the rate of case ascertainment. We mathematically describe the relationship between the ascertainment rate, the daily number of reported cases, population prevalence, and the sensitivity of PCR and Lateral Flow tests as a function time since exposure. Applying this model to the data, we estimate that 20%–40% of SARS-CoV-2 infections in the UK were ascertained with a positive test with results varying by time and region. Cases of the Alpha variant were ascertained at a higher rate than the wild type variants circulating in the early pandemic, and higher again for the Delta variant and Omicron BA.1 sub-lineage, but lower for the BA.2 sub-lineage. Case ascertainment was higher in adults than in children. We further estimate the daily number of infections and compare this to mortality data to estimate that the infection fatality rate increased by a factor of 3 during the period dominated by the Alpha variant, and declined in line with the distribution of vaccines. This manuscript was submitted as part of a theme issue on “Modelling COVID-19 and Preparedness for Future Pandemics”

A Metapopulation Model for Preventing the Reintroduction of Bovine Viral Diarrhea Virus to Naïve Herds: Scotland Case Study

BackgroundBovine viral diarrhea (BVD) virus is one of the most problematic infectious pathogens for cattle. Since 2013, a mandatory BVD eradication program has successfully reduced the number of infected cattle living on Scottish farms; however, England remains at high prevalence and presents a risk to Scotland through animal movement.MethodsWe analyze cattle movements in the UK from 2008 to 2017 and recorded incidence of BVD in Scotland from 2017 to 2020. To simulate BVD reintroduction into Scotland, we developed an epidemiological model that combines transmission between cattle and animal movements between farms. A total of four control strategies were implemented in the model: no intervention, import restriction, targeted vaccination, and combined strategy.ResultsDuring the course of the eradication scheme, movements into Scotland became increasingly distributed in regions close to the England–Scotland border. The prevalence of BVD in this region decreased at a slower rate than the rest of Scotland during the eradication scheme. Our model showed that the change in the prevalence is expected, given that the change in the patterns of movement and if vaccination is targeted to the border areas that decrease in the prevalence will be seen throughout the whole of Scotland.ConclusionScottish farms are susceptible to BVD virus reintroduction through animal imports from non-BVD-free nations with farms in border areas being the most vulnerable. Protecting the border regions provides direct and indirect protection to the rest of Scottish farms by interrupting chains of transmission

Homography-based ground plane detection using a single on-board camera

This study presents a robust method for ground plane detection in vision-based systems with a non-stationary camera. The proposed method is based on the reliable estimation of the homography between ground planes in successive images. This homography is computed using a feature matching approach, which in contrast to classical approaches to on-board motion estimation does not require explicit ego-motion calculation. As opposed to it, a novel homography calculation method based on a linear estimation framework is presented. This framework provides predictions of the ground plane transformation matrix that are dynamically updated with new measurements. The method is specially suited for challenging environments, in particular traffic scenarios, in which the information is scarce and the homography computed from the images is usually inaccurate or erroneous. The proposed estimation framework is able to remove erroneous measurements and to correct those that are inaccurate, hence producing a reliable homography estimate at each instant. It is based on the evaluation of the difference between the predicted and the observed transformations, measured according to the spectral norm of the associated matrix of differences. Moreover, an example is provided on how to use the information extracted from ground plane estimation to achieve object detection and tracking. The method has been successfully demonstrated for the detection of moving vehicles in traffic environments

Are the renormalized band widths in TTF-TCNQ of structural or electronic origin? - An angular dependent NEXAFS study

We have performed angle-dependent near-edge x-ray absorption fine structure measurements in the Auger electron yield mode on the correlated quasi-one-dimensional organic conductor TTF-TCNQ in order to determine the orientation of the molecules in the topmost surface layer. We find that the tilt angles of the molecules with respect to the one-dimensional axis are essentially the same as in the bulk. Thus we can rule out surface relaxation as the origin of the renormalized band widths which were inferred from the analysis of photoemission data within the one-dimensional Hubbard model. Thereby recent theoretical results are corroborated which invoke long-range Coulomb repulsion as alternative explanation to understand the spectral dispersions of TTF-TCNQ quantitatively within an extended Hubbard model.Comment: 6 pages, 5 figure

Laparoscopy for management of nontraumatic acute abdomen

Secţia Chirurgie, Spitalul Municipal de Urgenţă, Moineşti, România, Al XII-lea Congres al Asociației Chirurgilor „Nicolae Anestiadi” din Republica Moldova cu participare internațională 23-25 septembrie 2015Introducere: Laparoscopia în abdomenul acut are atât rol în stabilirea diagnosticului, confirmându-l în situaţiile echivoce, cât şi în orientarea strategiei terapeutice cu avantajele chirurgiei mini-invazive. Material şi metode: Studiul nostru evaluează 873 de cazuri de abdomen acut nontraumatic (exceptând colecistita acută) abordate laparoscopic în perioada 2010-2014, urmarindu-se concordanţa diagnosticului pre- şi postoperator, stabilirea unui diagnostic intraoperator cert, incidenţa intervenţiilor laparoscopice cât şi complicaţiile acestora. Rezultate: Diagnosticul intraoperator a fost de apendicită acută în 653 (75%) de cazuri, urgenţele ginecologice au fost certificate la 146 (17%) de pacienţi (chist ovarian eclatat, sarcina extrauterină, boala inflamatorie pelvină), 52 (6%) de pacienţi au fost diagnosticaţi cu ulcer perforat, 22 de cazuri fiind înregistrate cu alte patologii (pancreatite acute, perforaţii intestinale cu peritonite, diverticul Meckel perforat, infarcte enteromezenterice, peritonita TBC). Incidente şi accidente au fost întâlnite la 56 (6,5%) de pacienţi, au fost înregistrate 33 (3,7%) de conversii, complicaţii postoperatorii fiind înregistrate în 37 (4,2%) de cazuri. Concluzii: Laparoscopia diagnostică este o modalitate optimă diagnostică în cazurile de abdomen acut non-traumatic, fiind salutară în cazurile de apendicită acută, urgenţe ginecologice şi peritonita de etiologie neprecizată cu posibilitatea rezolvării pe această cale a patologiei identificate, în abdomenul acut laparoscopia fiind ultimul mijloc diagnostic şi primul mijloc terapeutic.Aims: Laparoscopy for acute abdomen is important either for diagnostic, when there is uncertainty in establishing the etiology, and also has a therapeutic role with the well known advantages of mini-invasive surgery. Material and methods: Our study evaluates 873 patients of nontraumatic acute abdomen (excepting acute cholecystitis), approached laparoscopically during 2010-2014. The following factors were pursued: the concordance between pre- and postoperative diagnostic, the establishment of a certain intraoperative diagnostic, incidence of laparoscopic interventions and their complications. Results: There were 653 (75%) cases of acute appendicitis, 146 patients with gynecological (ruptured ovarian cyst, ectopic pregnancy, inflammatory pelvic disease), 52 (6%) patients with perforated ulcer, 22 cases with other pathologies (acute pancreatitis, enteral perforations, perforations of Meckel diverticulum, entero-mesenteric infarction, tuberculous peritonitis), confirmed laparoscopically. Incidents and accidents were encountered in 56 (6.5%) cases, there were 33 (3.7%) conversions to open technique and for 37 (4.2%) patients were recorded postoperative complications. Conclusions: Diagnostic laparoscopy is an optimal method of diagnostic confirmation for cases of non-traumatic acute abdomen especially for acute appendicitis, gynecological emergencies and peritonitis of unknown etiology with the possibility of laparoscopic treatment of these pathologies, being also the last option for diagnostic and the first solution for treatment

Conquering the complexity mountain: Full-stack computer architecture teaching with FPGAs

Modern computer systems are exceedingly complex, and increasingly so. This makes it challenging for students with no background in computer systems to climb the mountain of 40 years of design, particularly within a constrained teaching timetable. Through the medium of FPGAs, we have designed an 8-week course to take students from basic digital electronics through to processor design, modern software tools, applications, system-on-chip integration and electronics manufacturing. We recount our experiences with rapidly bringing students up to speed with the modern world of computing systems, and some of the lessons we, as course designers, were taught by the process

Dispersion force for materials relevant for micro and nanodevices fabrication

The dispersion (van der Waals and Casimir) force between two semi-spaces are calculated using the Lifshitz theory for different materials relevant for micro and nanodevices fabrication, namely, gold, silicon, gallium arsenide, diamond and two types of diamond-like carbon (DLC), silicon carbide, silicon nitride and silicon dioxide. The calculations were performed using recent experimental optical data available in the literature, usually ranging from the far infrared up to the extreme ultraviolet bands of the electromagnetic spectrum. The results are presented in the form of a correction factor to the Casimir force predicted between perfect conductors, for the separation between the semi-spaces varying from 1 nanometre up to 1 micrometre. The relative importance of the contributions to the dispersion force of the optical properties in different spectral ranges is analyzed. The role of the temperature for semiconductors and insulators is also addressed. The results are meant to be useful for the estimation of the impact of the Casimir and van der Waals forces on the operational parameters of micro and nanodevices

Simple proof of gauge invariance for the S-matrix element of strong-field photoionization

The relationship between the length gauge (LG) and the velocity gauge (VG) exact forms of the photoionization probability amplitude is considered. Our motivation for this paper comes from applications of the Keldysh-Faisal-Reiss (KFR) theory, which describes atoms (or ions) in a strong laser field (in the nonrelativistic approach, in the dipole approximation). On the faith of a certain widely-accepted assumption, we present a simple proof that the well-known LG form of the exact photoionization (or photodetachment) probability amplitude is indeed the gauge-invariant result. In contrast, to obtain the VG form of this probability amplitude, one has to either (i) neglect the well-known Goeppert-Mayer exponential factor (which assures gauge invariance) during all the time evolution of the ionized electron or (ii) put some conditions on the vector potential of the laser field.Comment: The paper was initially submitted (in a previous version) on 16 October 2006 to J. Phys. A and rejected. This is the extended version (with 2 figures), which is identical to the paper published online on 12 December 2007 in Physica Script

Fast Road Sign Detection Using Hough Transform for Assisted Driving of Road Vehicles

Abstract. A system for real-time traffic sign detection is described in this paper. The system uses restricted Hough transform for circumferences in order to detect circular signs, and for straight lines for triangular ones. Some results obtained from a set of real road images captured under both normal and adverse weather conditions are presented as well in order to illustrate the robustness of the detection system. The average processing time is 30 ms per frame, what makes the system a good approach to work in real time conditions.