On amplitude zeros at threshold

The occurrence of zeros of 2 to n amplitudes at threshold in scalar theories is studied. We find a differential equation for the scalar potential, which incorporates all known cases where the 2 to n amplitudes at threshold vanish for all sufficiently large $n$, in all space-time dimensions, $d\ge 1$. This equation is related to the reflectionless potentials of Quantum Mechanics and to integrable theories in 1+1 dimensions. As an application, we find that the sine-Gordon potential and its hyperbolic version, the sinh-Gordon potential, also have amplitude zeros at threshold, ${\cal A}(2\to n)=0$, for $n\ge 4$ and $d\ge 2$, independently of the mass and the coupling constant.Comment: 6 pages, Latex, CERN-TH.6762/9

Multiscalar production amplitudes beyond threshold

We present exact tree-order amplitudes for $H^* \to n~H$, for final states containing one or two particles with non-zero three-momentum, for various interaction potentials. We show that there are potentials leading to tree amplitudes that satisfy unitarity, not only at threshold but also in the above kinematical configurations and probably beyond. As a by-product, we also calculate $2\to n$ tree amplitudes at threshold and show that for the unbroken $\phi^4$ theory they vanish for $n>4~$, for the Standard Model Higgs they vanish for $n\ge 3~$ and for a model potential, respecting tree-order unitarity, for $n$ even and $n>4~$. Finally, we calculate the imaginary part of the one-loop $1\to n$ amplitude in both symmetric and spontaneously broken $\phi^4$ theory.Comment: 11 pages, Latex, 3 figures (available on request

A qualitative exploration of care homes workers' views and training needs in relation to the use of socially assistive humanoid robots in their workplace

Aim: The study aimed to explore the views and attitudes of care home workers about the socially assistive robot that was trialled in their workplace, in order to identify training needs in relation to the hypothetical future use of these robots in their workplace. Background: Care home workers face challenging workload conditions which may require the exploration of new solutions such as the use of socially assistive robots (SARs). Methods: This is a qualitative descriptive study which used semi-structured interviews. Care home workers (n = 23) in the UK participated in the study, and data collection took place between October 2019 and January 2020. NVivo software was used for data management, and a thematic inductive analysis was conducted. Results: Findings indicated that many participants were open to the use of robots and valued the potential usefulness of SARs in the care setting. However, some participants showed resistance to the use of robots and did not feel comfortable with the idea of working alongside them. Participants wished to receive technical training that would enable them to be competent in using SARs. Participants took seriously their duty of care to the older people and thus wanted to ensure that the use of the SAR would not negatively impact on the care being provided. Robots were viewed as having potential to be supplementary to human carers, such as sharing the workload and improving upon the care already being provided. Conclusions: Care home workers express both positive and negative views in relation to the hypothetical future deployment of socially assistive humanoid robots in their workplace. Implications for practice: The findings highlighted the importance of values around person-centred care which should be taken into account when planning for the implementation of robots in social care settings and training care home workers in how to work with robots

Advances in Wood Composites

Wood composites have shown very good performance, and substantial service lives when correctly specified for the exposure risks present. Selection of an appropriate product for the job should be accompanied by decisions about the appropriate protection, whether this is by design, by preservative treatment or by wood modification techniques. This Special Issue, Advances in Wood Composites presents recent progress in enhancing and refining the performance and properties of wood composites by chemical and thermal modification and the application of smart nanomaterials, which have made them a particular area of interest for researchers. In addition, it reviews some important aspects in the field of wood composites, with particular focus on their materials, applications, and engineering and scientific advances, including solutions inspired biomimetrically by the structure of wood and wood composites. This Special Issue, with a collection of 13 original contributions, provides selected examples of recent Advances in Wood Composite

Increasing the imaging capabilities of multimode fibers by exploiting the properties of highly scattering media

We present a novel design that exploits the focusing properties of scattering media to increase the resolution and the working distance of multimode fiber based imaging devices. Placing a highly scattering medium in front of the distal tip of the multimode fiber enables the formation of smaller sized foci at increased working distances away from the fiber tip. We perform a parametric study of the effect of the working distance and the separation between the fiber and the scattering medium on the focus size. We experimentally demonstrate submicron focused spots as far away as 800{\mu}m with 532nm light.Comment: 4 pages, 3 figure

The safety of therapeutic monoclonal antibodies: Implications for cardiovascular disease and targeting the PCSK9 pathway

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Heat and mass transfer effects in the nozzle of a fuel injector from the start of needle lift to after the end of injection in the presence of fuel dribble and air entrainment

The design of fuel injectors is key to achieving high-efficiency engine combustion with low tailpipe emissions. The small dimensions of injector nozzle holes make the manufacturing of real-size optical injectors aimed at fundamental understanding of in-nozzle processes at design stage very challenging, especially for operation under realistic in-cylinder thermodynamic conditions. Therefore, faithful numerical predictions based on complete multiphase flow simulations upstream and downstream of the nozzle exit of a real injector geometry are highly sought after. In this paper, numerical studies of a Diesel injector nozzle with moving needle were performed using transient Reynolds Averaged Navier-Stokes (RANS) modelling with compressibility of all phases accounted for. A Volume of Fluid (VOF) method was employed, coupled to cavitation and evaporation submodels, along with a complete set of pressure and temperature dependent thermophysical fuel properties. The aim was to understand the flow inside the nozzle both during injection and after the end of injection, including fuel dribble and air backfilling effects. A range of fuel injection and air chamber pressures and temperatures were simulated, namely 400 and 900 bar upstream and 1, 35 and 60 bar downstream. Fuel, air and wall temperatures were varied in the range 300 K to 550 K. The results showed that the flow during injection carried hysteresis effects. After the end of injection, the state of the nozzle varied from being filled with a large amount of liquid to being filled mostly with air. Some form of immediate fuel dribble existed in all test cases, whilst late liquid fuel mass expulsion was also predicted under certain conditions. The latter prediction highlighted sensitivity to the models enabled. The use of a transient pressure outlet based on an engine's expansion stroke pressure trace affected the process of late fuel expulsion by pulling fuel out of the nozzle in multiphase form faster. These processes are of particular importance as they can contribute directly to unburned hydrocarbon emissions and/or the formation of deposits inside the holes. Starting a second injection from the resulting state of the nozzle at the end of the original injection resulted in a deformed liquid jet tip without the classic mushroom shape and a temporarily lower liquid jet penetration