Noncommutative field theory from angular twist

We consider a noncommutative field theory with space-time $\star$-commutators based on an angular noncommutativity, namely a solvable Lie algebra: the Euclidean in two dimension. The $\star$-product can be derived from a twist operator and it is shown to be invariant under twisted Poincar\'e transformations. In momentum space the noncommutativity manifests itself as a noncommutative $\star$-deformed sum for the momenta, which allows for an equivalent definition of the $\star$-product in terms of twisted convolution of plane waves. As an application, we analyze the $\lambda \phi^4$ field theory at one-loop and discuss its UV/IR behaviour. We also analyze the kinematics of particle decay for two different situations: the first one corresponds to a splitting of space-time where only space is deformed, whereas the second one entails a non-trivial $\star$-multiplication for the time variable, while one of the three spatial coordinates stays commutative.Comment: 23 pages 1 figur

Enhanced propagation of motile bacteria on surfaces due to forward scattering

How motile bacteria move near a surface is a problem of fundamental biophysical interest and is key to the emergence of several phenomena of biological, ecological and medical relevance, including biofilm formation. Solid boundaries can strongly influence a cell's propulsion mechanism, thus leading many flagellated bacteria to describe long circular trajectories stably entrapped by the surface. Experimental studies on near-surface bacterial motility have, however, neglected the fact that real environments have typical microstructures varying on the scale of the cells' motion. Here, we show that micro-obstacles influence the propagation of peritrichously flagellated bacteria on a flat surface in a non-monotonic way. Instead of hindering it, an optimal, relatively low obstacle density can significantly enhance cells' propagation on surfaces due to individual forward-scattering events. This finding provides insight on the emerging dynamics of chiral active matter in complex environments and inspires possible routes to control microbial ecology in natural habitats

Combination Therapy With Fingolimod and Neural Stem Cells Promotes Functional Myelination

Myelination, which occurs predominantly postnatally and continues throughout life, is important for proper neurologic function of the mammalian central nervous system (CNS). We have previously demonstrated that the combination therapy of fingolimod (FTY720) and transplanted neural stem cells (NSCs) had a significantly enhanced therapeutic effect on the chronic stage of experimental autoimmune encephalomyelitis, an animal model of CNS autoimmunity, compared to using either one of them alone. However, reduced disease severity may be secondary to the immunomodulatory effects of FTY720 and NSCs, while whether this therapy directly affects myelinogenesis remains unknown. To investigate this important question, we used three myelination models under minimal or non-inflammatory microenvironments. Our results showed that FTY720 drives NSCs to differentiate into oligodendrocytes and promotes myelination in an ex vivo brain slice culture model, and in the developing CNS of healthy postnatal mice in vivo. Elevated levels of neurotrophic factors, e.g., brain-derived neurotrophic factor and glial cell line-derived neurotrophic factor, were observed in the CNS of the treated infant mice. Further, FTY720 and NSCs efficiently prolonged the survival and improved sensorimotor function of shiverer mice. Together, these data demonstrate a direct effect of FTY720, beyond its known immunomodulatory capacity, in NSC differentiation and myelin development as a novel mechanism underlying its therapeutic effect in demyelinating diseases

Report on Scientific advice to TfL on bus driver assault screen modifications due to the Covid-19 pandemic

In April 2020 Transport for London (TfL) commissioned the UCL Department of Civil, Environmental and Geomatic Engineering (CEGE) to explore measures to mitigate the occupational risk posed to London bus drivers from the COVID-19 pandemic, following the tragic deaths of a number of drivers among bus operators within London. A separate study undertaken by UCL’s Institute of Health Equality has examined more comprehensively a number of other risk factors affecting bus drivers, including beyond their occupational risk. Phase one of that study was published on the 27th July 2020 and has determined that “there is evidence that among bus drivers those aged 65 and over, those from BAME backgrounds and those with pre-existing hypertension are at a higher risk of COVID-19 mortality and this should be taken into accounts in efforts by TfL and bus companies to reduce risks”. TfL asked UCL CEGE to explore the nature of this occupational risk in relation to the interaction between passengers and the bus driver, and the effects arising as a result of the design of the bus itself, in particular the assault screen. The assault screen is a pre-existing transparent polycarbonate fixture designed to resist physical attacks, such as stabbings, while allowing the driver to have both a clear view through the screen, access the electronic ticket machine and provide receipts when required, and the ability to be able to hear and speak to passengers as the need arises. It was not originally designed to keep the driver completely isolated from the passengers. A set of detailed models was created of the front part of a typical London bus, including both front and central doors, the driver’s cabin and a detailed dynamic model of the bus driver, and then detailed CFD simulations were carried out. These calculated the motion of aerosols emanating from a passenger who is coughing and breathing in a number of positions relative to the driver’s cabin under a variety of design and operational scenarios in order to identify appropriate interventions. A typical screen and bus design were chosen for the simulations, that addressed all the relevant design issues - gaps, door and window operations - as a representative case for all buses. The original (pre-COVID) designs of polycarbonate dividers or screens were only marginally protective against aerosols and were not sufficient on their own to protect against airborne transmission of SARS-CoV-2. A set of recommendations has been made with the aim of reducing this risk to London drivers in particular as much as is practically possible, further to interventions already initiated by TfL. Buses in large cities are a unique indoor environment that is confined and often crowded at rush hour or in tourist season and, if poorly ventilated there is potential for airborne transmission of infectious diseases which may pose a risk to drivers due to their prolonged exposure times. Further work is required to determine if there may be a risk to passengers too, if they are on board for long journeys. Regardless of any mechanical or physical interventions to reduce risk, it is recommended that in the medium-term, targets for Indoor Air Quality (IAQ) standards on public transport are developed and adopted. This, due to the high number of daily passengers, some of whom have long journey durations (>1hr if commuting from zones 4 and beyond) and the prevalence of infectious diseases such as influenza and the common cold in the population every winter season, which carry large economic costs and also cost lives. The emergence of highly infectious and more dangerous diseases in the UK and around the world in the past two decades, such as SARS-CoV-2, SARS, H1N1 (swine flu) or MERS, all indicate that it is very timely to invest efforts towards maintaining healthy and safe indoor air on public transport

The Tn916/Tn1545 Family of Conjugative Transposon

The conjugative transposon Tn916 was first discovered in the late 1970s and is, together with the related conjugative transposon Tn1545, the paradigm of a large family of related conjugative transposons known as the Tn916/Tn1545 family, which are found in an extremely diverse range of bacteria. With the huge increase in bacterial genomic sequence data available, due to the widespread use of next generation sequencing, more putative conjugative transposons belonging to the Tn916/Tn1545 family are being reported. Many of these are capable of excision, integration and conjugation. Nearly all of the Tn916/Tn1545‑like elements discovered to date encode tetracycline resistance however, increasingly resistance to other antimicrobials is being found. Some of the members of the Tn916/Tn1545 family of elements are composite structures which contain smaller mobile genetic elements which are also capable of transposition. Tn916/Tn1545‑like elements themselves are also found within larger and more complex elements. This review will give an overview of the current knowledge of the Tn916/Tn1545 family of conjugative transposons highlighting recently characterized composite elements carrying additional and novel resistance genes

Nanovesicles loaded with origanum onites and satureja thymbra essential oils and their activity against food-borne pathogens and spoilage microorganisms

Food poisoning is a common cause of illness and death in developing countries. Essential oils (EOs) could be effective and safe natural preservatives to prevent and control bacterial contamination of foods. However, their high sensitivity and strong flavor limit their application and biological effectiveness. The aim of this study was firstly the chemical analysis and the antimicrobial evaluation of the EOs of Origanum onites L. and Satureja thymbra L. obtained from Symi island (Greece), and, secondly, the formulation of propylene glycol-nanovesicles loaded with these EOs to improve their antimicrobial properties. The EOs were analyzed by GC-MS and their chemical contents are presented herein. Different nanovesicles were formulated with small average sizes, high homogeneity, and optimal ζ-potential. Microscopic observation confirmed their small and spherical shape. Antibacterial and antifungal activities of the formulated EOs were evaluated against food-borne pathogens and spoilage microorganisms compared to pure EOs. Propylene glycol-nanovesicles loaded with O. onites EO were found to be the most active formulation against all tested strains. Additionally, in vitro studies on the HaCaT cell line showed that nanovesicles encapsulated with EOs had no toxic effect. The present study revealed that both EOs can be used as alternative sanitizers and preservatives in the food industry, and that their formulation in nanovesicles can provide a suitable approach as food-grade delivery system

Fracture mechanics of laser sintered cracked polyamide for a new method to induce cracks by additive manufacturing

This paper presents an experimental investigation on specimens manufactured by Selective Laser Sintering (SLS), with the purposes of giving designers advice when designing 3D printed parts, and laying the basis for a step forward in the field of fracture mechanics of 3D complex parts. The aim is to investigate the effect of building direction in Polyamide (PA) 3D printed samples and to assess whether a crack can be initiated directly from the sintering process for fracture mechanics study purposes. Six different configurations of Mode I Compact Tension (CT) specimens were manufactured and tested; the experiments were monitored by Digital Image Correlation (DIC) and fractured surfaces were analyzed using microscopy. Results showed that samples with better mechanical performance are those in which all the layers contain a portion of the crack. On the other hand, those with layers parallel to the crack plan offer a preferential pathway for the crack to propagate. DIC and fractography investigations showed that, under certain conditions, small-radius geometries, or too-close surfaces may glue depending on printer resolution. Experiments also showed that SLS is capable of printing specimens with internal cracks that can be used to study fracture mechanics of complex parts or parts with internal cracks

TetAB46, a predicted heterodimeric ABC transporter conferring tetracycline resistance in Streptococcus australis isolated from the oral cavity.

OBJECTIVES: To identify the genes responsible for tetracycline resistance in a strain of Streptococcus australis isolated from pooled saliva from healthy volunteers in France. S. australis is a viridans Streptococcus, originally isolated from the oral cavity of children in Australia, and subsequently reported in the lungs of cystic fibrosis patients and as a cause of invasive disease in an elderly patient. METHODS: Agar containing 2 mg/L tetracycline was used for the isolation of tetracycline-resistant organisms. A genomic library in Escherichia coli was used to isolate the tetracycline resistance determinant. In-frame deletions and chromosomal repair were used to confirm function. Antibiotic susceptibility was determined by agar dilution and disc diffusion assay. RESULTS: The tetracycline resistance determinant from S. australis FRStet12 was isolated from a genomic library in E. coli and DNA sequencing showed two open reading frames predicted to encode proteins with similarity to multidrug resistance-type ABC transporters. Both genes were required for tetracycline resistance (to both the naturally occurring and semi-synthetic tetracyclines) and they were designated tetAB(46). CONCLUSIONS: This is the first report of a predicted ABC transporter conferring tetracycline resistance in a member of the oral microbiota

Guidance Notes for commercial offices: Safe return to work during COVID-19

This report explores multiple strategies and control measures for preventing or limiting the transmission of the SARS-CoV-2 virus in indoor office workplaces. It has been commissioned by Savile Row Projects Ltd to ensure that, in collaboration with its clients and supply chain, its work on the design, installation and operation of office interiors is executed in light of what is known about the disease. The background study on which this report is based focuses on three areas of advice: clinical, behavioural and built environment