• Building a consistent parton shower

      Forshaw, Jeffrey R.; Holguin, Jack; orcid: 0000-0001-5183-2673; email: jack.holguin@manchester.ac.uk; Plätzer, Simon (Springer Berlin Heidelberg, 2020-09-01)
      Abstract: Modern parton showers are built using one of two models: dipole showers or angular ordered showers. Both have distinct strengths and weaknesses. Dipole showers correctly account for wide-angle, soft gluon emissions and track the leading flows in QCD colour charge but they are known to mishandle partonic recoil. Angular ordered showers keep better track of partonic recoil and correctly include large amounts of wide-angle, soft physics but azimuthal averaging means they are known to mishandle some correlations. In this paper, we derive both approaches from the same starting point; linking our under- standing of the two showers. This insight allows us to construct a new dipole shower that has all the strengths of a standard dipole shower together with the collinear evolution of an angular-ordered shower. We show that this new approach corrects the next-to-leading- log errors previously observed in parton showers and improves their sub-leading-colour accuracy.
    • Characterisation of road-dust sediment in urban systems: a review of a global challenge

      Haynes, Haydn M.; Taylor, Kevin G.; email: kevin.taylor@manchester.ac.uk; Rothwell, James; Byrne, Patrick (Springer Berlin Heidelberg, 2020-10-21)
      Abstract: Purpose: The proportion of people living in urbanised areas is predicted to rise to > 65% by 2050, and therefore, more humans than ever will be exposed to urban environmental pollution. Accumulation of organic and inorganic substances on street and road surfaces is a major global challenge requiring scientifically robust methods of establishing risk that inform management strategies. This aim of this contribution is to critically review the global literature on urban road–deposited sediment contamination with a specific focus on variability in sampling and analytical methods. Materials and methods: In order to assess the concentration of contaminants in global road-deposited sediment (RDS), a comprehensive search of published RDS studies was completed. We review methodological approaches used in RDS studies to highlight the variability in datasets as a result of sampling technique, grain size fractionation, geochemical and mineralogical characterisation methods and establishing the influence of local geology on contaminant concentrations. We also consider emerging contaminants in RDS, and we provide a workflow diagram which promotes a standardised sampling and analysis regime that we believe can reduce data variability and promote collaboration when it comes to tackling the important issue of RDS contamination. Results and discussion: Across the literature, Asia (except China) and Africa are underrepresented in RDS studies despite these continents having the largest and fastest growing populations, respectively. The removal of tetraethyl lead from gasoline produced a noticeable decrease in lead concentrations in global RDS, and platinum group element (PGE) concentrations in RDS were consistent with catalytic converter usage. Research into the impact of electric vehicles on non-exhaust emissions suggests other contaminants such as zinc may become more prominent in the future. Most RDS studies consider grain size fractions larger than > 20 μm due to sampling constraints despite RDS < 20 μm being most relevant to human health. The use of chemical extraction methods to establish contaminant geochemistry is popular; however, most extraction procedures are not relevant or specific to minerals identified in RDS through microscopic and spectroscopic investigations. Conclusions: This review highlights considerable variability in sampling and analytical approach which makes it difficult to identify broad global patterns in RDS contamination. To remove this variability from future RDS research, this review suggests a workflow plan which attempts to improve the comparability between RDS studies. Such comparability is crucial in identifying more discrete RDS trends and informing future emission policy.
    • Combining single and double parton scatterings in a parton shower

      Cabouat, Baptiste; email: baptiste.cabouat@manchester.ac.uk; Gaunt, Jonathan R. (Springer Berlin Heidelberg, 2020-10-01)
      Abstract: Double parton scattering (DPS) processes in which there is a perturbative “1 → 2” splitting in both protons overlap with loop corrections to single parton scattering (SPS). Any fundamental theoretical treatment of DPS needs to address this double-counting issue. In this paper, we augment our Monte-Carlo simulation of DPS, dShower, to be able to generate kinematic distributions corresponding to the combination SPS+DPS without double counting. To achieve this, we formulate a fully-differential version of the subtraction scheme introduced in Diehl et al. (JHEP 06 (2017) 083). A shower is attached to the subtraction term, and this is combined with the dShower DPS shower along with the usual SPS shower. We perform a proof-of-concept study of this new algorithm in the context of Z0Z0 production. Once the subtraction term is included, we verify that the results do not depend strongly on the artificial “DPS-SPS demarcation” scale ν. As part of the development of the new algorithm, we improve the kinematics of the 1 → 2 splitting in the DPS shower (and subtraction term), allowing the daughter partons to have a relative transverse momentum. Several reasonable choices for the transverse profile in the 1 → 2 splitting are studied. We find that many kinematic distributions are not strongly affected by the choice, although we do observe some differences in the region where the transverse momenta of both bosons are small.
    • Does posture explain the kinematic differences in a grounded running gait between male and female Svalbard rock ptarmigan ( Lagopus muta hyperborea ) moving on snow?

      Marmol-Guijarro, Andres; orcid: 0000-0001-9316-540X; Nudds, Robert; orcid: 0000-0002-7627-6324; Folkow, Lars; orcid: 0000-0002-6580-9156; Lees, John; orcid: 0000-0002-9627-1790; Codd, Jonathan; orcid: 0000-0003-0211-1786; email: jonathan.codd@manchester.ac.uk (Springer Berlin Heidelberg, 2021-05-05)
      Abstract: The majority of locomotor research is conducted on treadmills and few studies attempt to understand the differences between this and animals moving in the wild. For example, animals may adjust their gait kinematics or limb posture, to a more compliant limb, to increase stability of locomotion to prevent limb failure or falling on different substrates. Here, using video recordings, we compared locomotor parameters (speed range, stride length, stride frequency, stance duration, swing duration and duty factor) of female Svalbard rock ptarmigan (Lagopus muta hyperborea) moving in the wild over snow to previous treadmill-based research. We also compared the absolute and body size (body mass and limb length)-corrected values of kinematic parameters to published data from males to look for any sex differences across walking and grounded running gaits. Our findings indicate that the kinematics of locomotion are largely conserved between the field and laboratory in that none of the female gaits were drastically affected by moving over snow, except for a prolonged swing phase at very slow walking speeds, likely due to toe dragging. Comparisons between the sexes indicate that the differences observed during a walking gait are likely due to body size. However, sexual dimorphism in body size could not explain the disparate grounded running kinematics of the female and male ptarmigan, which might be linked to a more crouched posture in females. Our findings provide insight into how males and females moving in situ may use different strategies to alleviate the effects of a variable substrate.
    • Effects of a disposable home electro-stimulation device (Pelviva) for the treatment of female urinary incontinence: a randomised controlled trial

      Oldham, Jackie; orcid: 0000-0001-5857-9551; email: jackie.oldham@manchester.ac.uk; Herbert, Julia; Garnett, Jane; Roberts, Stephen A. (Springer Berlin Heidelberg, 2021-08-20)
      Abstract: Aims: To compare current General Medical Practitioner treatment as usual (TAU) for the treatment of female urinary incontinence with a novel disposable home electro-stimulation device (Pelviva). Methods: Open label, Primary Care post-market evaluation. 86 women with urinary incontinence were randomly assigned to one of two 12-week treatments: TAU or Pelviva for 30 min every other day plus TAU. Outcome measures included ICIQ-UI (primary), PISQ-IR, PGI-S / PGI-I and FSFI (secondary) at recruitment and immediately after intervention, 1-h pad test at recruitment and usage diaries throughout. Results: Pelviva plus TAU produced significantly better outcome than TAU alone: 3 versus 1 point for ICIQ-UI (Difference − 1.8 95% CI: − 3.5 to − 0.1, P = 0.033). Significant differences were also observed for PGI-I at both 6 weeks (P = 0.001) and 12 weeks (P < 0.001). In the Pelviva group, 17% of women described themselves as feeling very much better and 54% a little or much better compared to 0% and 15% in the TAU. Overall PISQ-IR score reached statistical significance (P = 0.032) seemingly related to impact (P = 0.027). No other outcome measures reached statistical significance. Premature termination due to COVID-19 meant only 86 women were recruited from a sample size of 264. TAU did not reflect NICE guidelines. Conclusions: This study suggests Pelviva is more successful than TAU in treating urinary incontinence in Primary Care. The study had reduced power due to early termination due to COVID-19 and suggests TAU does not follow NICE guidelines.
    • EFT for soft drop double differential cross section

      Pathak, Aditya; orcid: 0000-0001-8149-2817; email: aditya.pathak@manchester.ac.uk; Stewart, Iain W.; Vaidya, Varun; Zoppi, Lorenzo; orcid: 0000-0002-9157-6907 (Springer Berlin Heidelberg, 2021-04-06)
      Abstract: We develop a factorization framework to compute the double differential cross section in soft drop groomed jet mass and groomed jet radius. We describe the effective theories in the large, intermediate, and small groomed jet radius regions defined by the interplay of the jet mass and the groomed jet radius measurement. As an application we present the NLL′ results for the perturbative moments that are related to the coefficients C1 and C2 that specify the leading hadronization corrections up to three universal parameters. We compare our results with Monte Carlo simulations and a calculation using the coherent branching method.
    • Frame covariant formalism for fermionic theories

      Finn, Kieran; orcid: 0000-0002-9840-2264; email: kieran.finn@manchester.ac.uk; Karamitsos, Sotirios; Pilaftsis, Apostolos (Springer Berlin Heidelberg, 2021-07-02)
      Abstract: We present a frame- and reparametrisation-invariant formalism for quantum field theories that include fermionic degrees of freedom. We achieve this using methods of field-space covariance and the Vilkovisky–DeWitt (VDW) effective action. We explicitly construct a field-space supermanifold on which the quantum fields act as coordinates. We show how to define field-space tensors on this supermanifold from the classical action that are covariant under field reparametrisations. We then employ these tensors to equip the field-space supermanifold with a metric, thus solving a long-standing problem concerning the proper definition of a metric for fermionic theories. With the metric thus defined, we use well-established field-space techniques to extend the VDW effective action and express any fermionic theory in a frame- and field-reparametrisation-invariant manner.
    • Frame covariant formalism for fermionic theories

      Finn, Kieran; orcid: 0000-0002-9840-2264; email: kieran.finn@manchester.ac.uk; Karamitsos, Sotirios; Pilaftsis, Apostolos (Springer Berlin Heidelberg, 2021-07-02)
      Abstract: We present a frame- and reparametrisation-invariant formalism for quantum field theories that include fermionic degrees of freedom. We achieve this using methods of field-space covariance and the Vilkovisky–DeWitt (VDW) effective action. We explicitly construct a field-space supermanifold on which the quantum fields act as coordinates. We show how to define field-space tensors on this supermanifold from the classical action that are covariant under field reparametrisations. We then employ these tensors to equip the field-space supermanifold with a metric, thus solving a long-standing problem concerning the proper definition of a metric for fermionic theories. With the metric thus defined, we use well-established field-space techniques to extend the VDW effective action and express any fermionic theory in a frame- and field-reparametrisation-invariant manner.
    • From parametric trace slicing to rule systems

      Reger, Giles; email: giles.reger@manchester.ac.uk; Rydeheard, David (Springer Berlin Heidelberg, 2021-02-27)
      Abstract: Parametric runtime verification is the process of verifying properties of execution traces of (data carrying) events produced by a running system. This paper continues our work exploring the relationship between specification techniques for parametric runtime verification. Here we consider the correspondence between trace-slicing automata-based approaches and rule systems. The main contribution is a translation from quantified automata to rule systems, which has been implemented in Scala. This then allows us to highlight the key differences in how the two formalisms handle data, an important step in our wider effort to understand the correspondence between different specification languages for parametric runtime verification. This paper extends a previous conference version of this paper with further examples, a proof of correctness, and an optimisation based on a notion of redundancy observed during the development of the translation.
    • Improvements on dipole shower colour

      Holguin, Jack; orcid: 0000-0001-5183-2673; email: jack.holguin@manchester.ac.uk; Forshaw, Jeffrey R.; Plätzer, Simom (Springer Berlin Heidelberg, 2021-04-27)
      Abstract: The dipole formalism provides a powerful framework from which parton showers can be constructed. In a recent paper (Forshaw et al. 2020), we proposed a dipole shower with improved colour accuracy and in this paper we show how it can be further improved. After an explicit check at O(αs2) we confirm that our original shower performs as it was designed to, i.e. inheriting its handling of angular-ordered radiation from a coherent branching algorithm. We also show how other dipole shower algorithms fail to achieve this. Nevertheless, there is an O(αs2) topology where it differs at sub-leading Nc from a coherent branching algorithm. This erroneous topology can contribute a leading logarithm to some observables and corresponds to emissions that are ordered in kt but not angle. We propose a simple, computationally efficient way to correct this and assign colour factors in accordance with the coherence properties of QCD to all orders in αs.
    • Intersecting Lorenz curves and aversion to inverse downside inequality

      Chiu, W. Henry; orcid: 0000-0003-3000-9519; email: henry.chiu@manchester.ac.uk (Springer Berlin Heidelberg, 2020-10-02)
      Abstract: This paper defines and characterizes the concept of an increase in inverse downside inequality and show that, when the Lorenz curves of two income distributions intersect, how the change from one distribution to the other is judged by an inequality index exhibiting inverse downside inequality aversion often depends on the relative strengths of its aversion to inverse downside inequality and inequality aversion. For the class of linear inequality indices, of which the Gini coefficient is a member, a measure characterizing the strength of an index’s aversion to inverse downside inequality against its own inequality aversion is shown to determine the ranking by the index of two distributions whose Lorenz curves cross once. The precise condition under which the same result generalizes to the case of multiple-crossing Lorenz curves is also identified.
    • Investigating the importance of B cells and antibodies during Trichuris muris infection using the IgMi mouse

      Sahputra, Rinal; orcid: 0000-0001-6612-0417; email: rinal.sahputra@manchester.ac.uk; Murphy, Emma A; Forman, Ruth; Mair, Iris; Fadlullah, Muhammad Z. H.; Waisman, Ari; Muller, Werner; Else, Kathryn J.; email: kathryn.j.else@manchester.ac.uk (Springer Berlin Heidelberg, 2020-08-10)
      Abstract: The IgMi mouse has normal B cell development; its B cells express an IgM B cell receptor but cannot class switch or secrete antibody. Thus, the IgMi mouse offers a model system by which to dissect out antibody-dependent and antibody-independent B cell function. Here, we provide the first detailed characterisation of the IgMi mouse post-Trichuris muris (T. muris) infection, describing expulsion phenotype, cytokine production, gut pathology and changes in T regulatory cells, T follicular helper cells and germinal centre B cells, in addition to RNA sequencing (RNA seq) analyses of wild-type littermates (WT) and mutant B cells prior to and post infection. IgMi mice were susceptible to a high-dose infection, with reduced Th2 cytokines and elevated B cell-derived IL-10 in mesenteric lymph nodes (MLN) compared to controls. A low-dose infection regime revealed IgMi mice to have significantly more apoptotic cells in the gut compared to WT mice, but no change in intestinal inflammation. IL-10 levels were again elevated. Collectively, this study showcases the potential of the IgMi mouse as a tool for understanding B cell biology and suggests that the B cell plays both antibody-dependent and antibody-independent roles post high- and low-dose T. muris infection. Key messages: During a high-dose T. muris infection, B cells are important in maintaining the Th1/Th2 balance in the MLN through an antibody-independent mechanism. High levels of IL-10 in the MLN early post-infection, and the presence of IL-10-producing B cells, correlates with susceptibility to T. muris infection. B cells maintain gut homeostasis during chronic T. muris infection via an antibody-dependent mechanism.
    • Investigating top tagging with Y m -Splitter and N-subjettiness

      Dasgupta, Mrinal; Helliwell, Jack; orcid: 0000-0002-8725-7794; email: jack.helliwell@manchester.ac.uk (Springer Berlin Heidelberg, 2021-10-12)
      Abstract: We study top-tagging from an analytical QCD perspective focussing on the role of two key steps therein: a step to find three-pronged substructure and a step that places constraints on radiation. For the former we use a recently introduced modification of Y-Splitter, known as Ym-Splitter, and for the latter we use the well-known N-subjettiness variable. We derive resummed results for this combination of variables for both signal jets and background jets, also including pre-grooming of the jet. Our results give new insight into the performance of top tagging tools in particular with regard to the role of the distinct steps involved.
    • Mirror self-recognition in gorillas ( Gorilla gorilla gorilla ): a review and evaluation of mark test replications and variants

      Murray, Lindsay E.; orcid: 0000-0002-7810-9546; email: l.murray@chester.ac.uk; Anderson, James R.; Gallup, Gordon G., Jr (Springer Berlin Heidelberg, 2022-01-07)
      Abstract: Mirror self-recognition (MSR), widely regarded as an indicator of self-awareness, has not been demonstrated consistently in gorillas. We aimed to examine this issue by setting out a method to evaluate gorilla self-recognition studies that is objective, quantifiable, and easy to replicate. Using Suarez and Gallup’s (J Hum Evol 10:175–183, 1981) study as a reference point, we drew up a list of 15 methodological criteria and assigned scores to all published studies of gorilla MSR for both methodology and outcomes. Key features of studies finding both mark-directed and spontaneous self-directed responses included visually inaccessible marks, controls for tactile and olfactory cues, subjects who were at least 5 years old, and clearly distinguishing between responses in front of versus away from the mirror. Additional important criteria include videotaping the tests, having more than one subject, subjects with adequate social rearing, reporting post-marking observations with mirror absent, and giving mirror exposure in a social versus individual setting. Our prediction that MSR studies would obtain progressively higher scores as procedures and behavioural coding practices improved over time was supported for methods, but not for outcomes. These findings illustrate that methodological rigour does not guarantee stronger evidence of self-recognition in gorillas; methodological differences alone do not explain the inconsistent evidence for MSR in gorillas. By implication, it might be suggested that, in general, gorillas do not show compelling evidence of MSR. We advocate that future MSR studies incorporate the same criteria to optimize the quality of attempts to clarify the self-recognition abilities of gorillas as well as other species.
    • Predictive approaches to guide the expression of recombinant vaccine targets in Escherichia coli: a case study presentation utilising Absynth Biologics Ltd. proprietary Clostridium difficile vaccine antigens

      Hussain, Hirra; McKenzie, Edward A; Robinson, Andrew M; Gingles, Neill A; Marston, Fiona; Warwicker, Jim; Dickson, Alan J; orcid: 0000-0001-9490-645X; email: alan.dickson@manchester.ac.uk (Springer Berlin Heidelberg, 2021-06-28)
      Abstract: Bacterial expression systems remain a widely used host for recombinant protein production. However, overexpression of recombinant target proteins in bacterial systems such as Escherichia coli can result in poor solubility and the formation of insoluble aggregates. As a consequence, numerous strategies or alternative engineering approaches have been employed to increase recombinant protein production. In this case study, we present the strategies used to increase the recombinant production and solubility of ‘difficult-to-express’ bacterial antigens, termed Ant2 and Ant3, from Absynth Biologics Ltd.’s Clostridium difficile vaccine programme. Single recombinant antigens (Ant2 and Ant3) and fusion proteins (Ant2-3 and Ant3-2) formed insoluble aggregates (inclusion bodies) when overexpressed in bacterial cells. Further, proteolytic cleavage of Ant2-3 was observed. Optimisation of culture conditions and changes to the construct design to include N-terminal solubility tags did not improve antigen solubility. However, screening of different buffer/additives showed that the addition of 1–15 mM dithiothreitol alone decreased the formation of insoluble aggregates and improved the stability of both Ant2 and Ant3. Structural models were generated for Ant2 and Ant3, and solubility-based prediction tools were employed to determine the role of hydrophobicity and charge on protein production. The results showed that a large non-polar region (containing hydrophobic amino acids) was detected on the surface of Ant2 structures, whereas positively charged regions (containing lysine and arginine amino acids) were observed for Ant3, both of which were associated with poor protein solubility. We present a guide of strategies and predictive approaches that aim to guide the construct design, prior to expression studies, to define and engineer sequences/structures that could lead to increased expression and stability of single and potentially multi-domain (or fusion) antigens in bacterial expression systems.
    • Probing the ∆ U = 0 rule in three body charm decays

      Dery, Avital; Grossman, Yuval; Schacht, Stefan; email: stefan.schacht@manchester.ac.uk; Soffer, Abner (Springer Berlin Heidelberg, 2021-05-20)
      Abstract: CP violation in charm decay was observed in the decays D0→ P±P∓ of a D0 meson to two pseudoscalars. When interpreted within the SM, the results imply that the ratio of the relevant rescattering amplitudes has a magnitude and phase that are both of O(1). We discuss ways to probe similar ratios in D0→ V±P∓ decays, where V is a vector that decays to two pseudoscalars, from the Dalitz-plot analysis of time-integrated three-body decays. Compared to two-body decays, three-body decays have the advantage that the complete system can be solved without the need for time-dependent CP violation measurements or use of correlated D0−D¯0 production. We discuss the decays D0→ π+π−π0 and D0→ K+K−π0 as examples by considering a toy model of only two overlapping charged resonances, treating the underlying pseudo two-body decays in full generality.
    • Probing the ∆ U = 0 rule in three body charm decays

      Dery, Avital; Grossman, Yuval; Schacht, Stefan; email: stefan.schacht@manchester.ac.uk; Soffer, Abner (Springer Berlin Heidelberg, 2021-05-20)
      Abstract: CP violation in charm decay was observed in the decays D0→ P±P∓ of a D0 meson to two pseudoscalars. When interpreted within the SM, the results imply that the ratio of the relevant rescattering amplitudes has a magnitude and phase that are both of O(1). We discuss ways to probe similar ratios in D0→ V±P∓ decays, where V is a vector that decays to two pseudoscalars, from the Dalitz-plot analysis of time-integrated three-body decays. Compared to two-body decays, three-body decays have the advantage that the complete system can be solved without the need for time-dependent CP violation measurements or use of correlated D0−D¯0 production. We discuss the decays D0→ π+π−π0 and D0→ K+K−π0 as examples by considering a toy model of only two overlapping charged resonances, treating the underlying pseudo two-body decays in full generality.
    • The potential of coffee stems gasification to provide bioenergy for coffee farms: a case study in the Colombian coffee sector

      Garcia-Freites, Samira; orcid: 0000-0002-4136-2724; email: samira.garciafreites@manchester.ac.uk; Welfle, Andrew; Lea-Langton, Amanda; Gilbert, Paul; Thornley, Patricia (Springer Berlin Heidelberg, 2019-08-03)
      Abstract: The coffee industry constitutes an important part of the global economy. Developing countries produce over 90% of world coffee production, generating incomes for around 25 million smallholder farmers. The scale of this industry poses a challenge with the generation of residues along with the coffee cultivation and processing chain. Coffee stems, obtained after pruning of coffee trees, are one of those abundant and untapped resources in the coffee supply chain. Their high lignocellulosic content, the low calorific value ranging between 17.5 and 18 MJ kg−1 and the low ash content make them a suitable solid fuel for thermochemical conversion, such as gasification. This research evaluates the feasibility of using these residues in small-scale downdraft gasifiers coupled to internal combustion engines for power and low-grade heat generation, using process modelling and the Colombian coffee sector as a case study. The producer gas properties (5.6 MJ Nm−3) and the gasifier’s performance characteristics suggest that this gas could be utilized for power generation. A cogeneration system efficiency of 45.6% could be attainable when the system’s low-grade heat is recovered for external applications, like in the coffee drying stage. An analysis of the energy demand and coffee stems availability within the Colombian coffee sector shows that the biomass production level in medium- to large-scale coffee farms is well matched to their energy demands, offering particularly attractive opportunities to deploy this bioenergy system. This work assesses the feasibility of providing coffee stem–sourced low-carbon energy for global coffee production at relevant operating scales in rural areas.