Impact scores of invasive plants are biased by disregard of environmental co-variation and non-linearity

Prioritisation of high-impact species is becoming increasingly important for management of introduced species (‘neobiota’) because of their growing number of which, however, only a small fraction has substantial impacts. Impact scores for prioritising species may be affected by the type of effect model used. Recent studies have shown that environmental co-variation and non-linearity may be significant for effect models of biological invasions. Here, we test for differences in impact scores between simple and complex effect models of three invasive plant species (Heracleum mantegazzianum, Lupinus polyphyllus, Rosa rugosa). We investigated the effects of cover percentages of the invasive plants on species richness of invaded communities using both simple linear effect models (‘basic models’) and more complex linear or nonlinear models including environmental co-factors (‘full models’). Then, we calculated impact scores for each invasive species as the average reduction of species richness predicted by basic and full effect models. All three non-native species had negative effects on species richness, but the full effect models also indicated significant influence of habitat types. Heracleum mantegazzianum had uniform linear effects in all habitats, while effects of L. polyphyllus interacted strongly with habitat type, and R. rugosa showed a marked non-linear relationship. Impact scores were overestimated by basic effect models for H. mantegazzianum and R. rugosa due to disregard of habitat effects and non-linearity, respectively. In contrast, impact of L. polyphyllus was underestimated by the basic model that did not account for the strong interaction of invader cover and habitat type. We conclude that simple linear models will often yield inaccurate impact scores of non-native species. Hence, effect models should consider environmental co-variation and, if necessary, non-linearity of the effects of biological invasions on native ecosystems

Modelling and control of a high redundancy actuator

The high redundancy actuation concept is a completely new approach to fault tolerance, and it is important to appreciate that it provides a transformation of the characteristics of actuators so that the actuation performance (capability) degrades slowly rather than suddenly failing, even though individual elements themselves fail. This paper aims to demonstrate the viability of the concept by showing that a highly redundant actuator, comprising a relatively large number of actuation elements, can be controlled in such a way that faults in individual elements are inherently accommodated, although some degradation in overall performance will inevitably be found. The paper introduces the notion of fault-tolerant systems and the highly redundant actuator concept. Then a model for a two by two configuration with electro-mechanical actuation elements is derived. Two classical control approaches are then considered based on frequency domain techniques. Finally simulation results under a number of faults show the viability of the approach for fault accommodation without re-configuratio

Towards distributed diagnosis of the Tennessee Eastman process benchmark

A distributed hybrid strategy is outlined for the isolation of faults and disturbances in the Tennessee Eastman process, which would build on existing structures for distributed control systems, so should be easy to implement, be cheap and be widely applicable. The main emphasis in the paper is on one component of the strategy, a steady-state-based approach. Results obtained by applying this approach are presented and knowledge limitations are discussed. In particular a way in which a knowledge-base might evolve to improve isolation capabilities is suggested and the role of the operator is briefly discussed

spl(2,1) dynamical supersymmetry and suppression of ferromagnetism in flat band double-exchange models

The low energy spectrum of the ferromagnetic Kondo lattice model on a N-site complete graph extended with on-site repulsion is obtained from the underlying spl(2,1) algebra properties in the strong coupling limit. The ferromagnetic ground state is realized for 1 and N+1 electrons only. We identify the large density of states to be responsible for the suppression of the ferromagnetic state and argue that a similar situation is encountered in the Kagome, pyrochlore, and other lattices with flat bands in their one-particle density of states.Comment: 7 pages, 1 figur

Colour-Kinematics Duality for One-Loop Rational Amplitudes

Colour-kinematics duality is the conjecture of a group theory-like structure for the kinematic dependence of scattering amplitudes in gauge theory and gravity. This structure has been verified at tree level in various ways, but similar progress has been lacking at loop level, where the power of the duality would be most significant. Here we explore colour-kinematics duality at one loop using the self-dual sector as a starting point. The duality is shown to exist in pure Yang-Mills theory for two infinite classes of amplitudes: amplitudes with any number of particles either all of the same helicity or with one particle helicity opposite the rest. We provide a simple Lagrangian-based argument in favour of the double copy relation between gauge theory and gravity amplitudes in these classes, and provide some explicit examples. We further discuss aspects of the duality which persist after integration, leading to relations among partial amplitudes. Finally, we describe form factors in the self-dual theory at tree level which also satisfy the duality.Comment: 36 pages, 5 figures; v2: published versio

Black Hole Formation and Classicalization in Ultra-Planckian 2 -> N Scattering

We establish a connection between the ultra-Planckian scattering amplitudes in field and string theory and unitarization by black hole formation in these scattering processes. Using as a guideline an explicit microscopic theory in which the black hole represents a bound-state of many soft gravitons at the quantum critical point, we were able to identify and compute a set of perturbative amplitudes relevant for black hole formation. These are the tree-level N-graviton scattering S-matrix elements in a kinematical regime (called classicalization limit) where the two incoming ultra-Planckian gravitons produce a large number N of soft gravitons. We compute these amplitudes by using the Kawai-Lewellen-Tye relations, as well as scattering equations and string theory techniques. We discover that this limit reveals the key features of the microscopic corpuscular black hole N-portrait. In particular, the perturbative suppression factor of a N-graviton final state, derived from the amplitude, matches the non-perturbative black hole entropy when N reaches the quantum criticality value, whereas final states with different value of N are either suppressed or excluded by non-perturbative corpuscular physics. Thus we identify the microscopic reason behind the black hole dominance over other final states including non-black hole classical object. In the parameterization of the classicalization limit the scattering equations can be solved exactly allowing us to obtain closed expressions for the high-energy limit of the open and closed superstring tree-level scattering amplitudes for a generic number N of external legs. We demonstrate matching and complementarity between the string theory and field theory in different large-s and large-N regimes.Comment: 55 pages, 7 figures, LaTeX; v2: typos removed; final version to appear in Nucl. Phys.

New relations for scattering amplitudes in Yang-Mills theory at loop level

The calculation of scattering amplitudes in Yang-Mills theory at loop level is important for the analysis of background processes at particle colliders as well as our understanding of perturbation theory at the quantum level. We present tools to derive relations for especially one loop amplitudes, as well as several explicit examples for gauge theory coupled to a wide variety of matter. These tools originate in certain scaling behavior of permutation and cyclic sums of Yang-Mills tree amplitudes and loop integrands. In the latter case evidence exists for relations at all loop orders.Comment: 12 pages, 4 figures. v3: typos corrected, figures and clarifications adde

Elucidating the role of histone variant H2A.J following ionizing radiation

Senescence is a stress-induced state in which cells cease proliferation whilst remaining metabolically active. While it is a noteworthy tumour suppressor mechanism, accumulation of senescent cells in aged or DNA-damaged tissue through toxins such as ionizing radiation (IR), has been implicated as a one of the nine hallmark ageing mechanisms as well as inducing premature ageing and promoting neoplastic growth. The limited study of novel histone variant H2A.J, has uncovered targeted accumulation of H2A.J in etoposide (ETO)-induced and oncogene-induced senescence (OIS). Additionally, it plays a functional role in induction of the inflammatory senescence-associated secretory phenotype, a major effector of ageing and cancer. Whilst the DNA-damaging properties of radiotherapy aid in tumour growth control, healthy tissue is inevitably exposed to low doses of irradiation with side-effects including inflammation and radiation–induced senescence. This study therefore seeks to elucidate a possible role of H2A.J association with irradiation-induced senescence, DNA-damage repair and senescence-associated secretory phenotype. H2A.J knock-down WI-38 lung fibroblasts and No-Target WI-38 lung fibroblasts containing unaltered H2A.J expression were irradiated and compared. Immunofluorescence microscopy (IFM) examinations were applied to determine normal H2A.J accumulation in response to IR, DNA-damage repair efficiency, senescence induction, proliferative arrest, senescence-associated heterochromatin foci (SAHF) formation and DNA-segments with chromatin alterations reinforcing senescence (DNA-SCARS) formation. Transmission electron microscopy (TEM) was applied to gain further insight into senescence-associated chromatin changes and H2A.J localisation in respect to SAHF and DNA-SCARS. Furthermore, ultrastructure of DNA-SCARS was examined at the nanoscale using TEM. The senescence-associated secretory phenotype (SASP) following irradiation was investigated using enzyme-linked immunosorbent assay (ELISA) performed on conditioned medium and quantitative reverse transcription polymerase chain reaction (RT-qPCR) on isolated RNA. Additionally, aged- and ex-vivo irradiated human epidermis was evaluated for DNA-damage foci and H2A.J accumulation using IFM. In vivo immunofluorescence microscopy examinations of 20x 0.1Gy irradiated murine epidermis was also completed to gain insight into the long term accumulation of H2A.J following low-dose fractionated irradiation. In vitro studies revealed H2A.J accumulates in a dose-dependent manner with lower doses resulting in transient accumulation and higher doses inducing senescence leading to long-term H2A.J positivity. H2A.J did not influence repair capacity following IR. Knock-down of H2A.J did not affect senescence induction, proliferative arrest, and SAHF formation. It did however, effect ultrastructure of DNA-SCARS thus potentially explaining the altered SASP revealed by ELISA and RT-qPCR. Human epidermal biopsy examinations revealed increased H2A.J in aged epidermis together with increasing presence of DNA-damage foci. In vivo murine epidermis showed increased H2A.J accumulation up to 6 months post-IR at a level similar to 18 month old aged mice. This work provides a baseline insight into H2A.J accumulation following IR revealing potential insight into its influence on IR-induced SASP regulation. Additionally, indications arose for the application of H2A.J as a potential biomarker of senescent cells in culture, as well as, in human epidermal biopsies.Die Bedeutung der Histonvariants H2A.J nach ionisierender Strahlung Seneszenz beschreibt einen durch Stress induzierten zellulären Zustand, indem keine Proliferation stattfindet, die Zelle aber trotz allem metabolisch aktiv bleibt. Während Seneszenz damit in erster Linie einen effizienten Tumorsuppressions-Mechanismus darstellt, unterstützt die Akkumulation seneszenter Zellen in gealtertem oder bestrahltem Gewebe frühzeitige Alterung und das Tumorwachstum. Eine aktuelle Studie der Histonvariante H2A.J zeigt die Akkumulation von H2A.J im Rahmen einer Etoposid- und Onkogen-induzierten Seneszenz. Weiterhin bestätigte sich ein Zusammenhang zwischen H2A.J und der Induktion des Seneszenz-assoziiertem sekretorischem Phänotyps (SASP), einem Haupteffektor von Alterung und Krebs. In der Radiotherapie macht man sich die DNA-schädigenden Eigenschaften von ionisierender Strahlung zur gezielten Kontrolle des Tumorwachstums zu Nutze, wobei auch gesundes Gewebe in Tumornähe mit niedrigen Strahlendosen belastet wird. Dies kann möglicherweise Nebenwirkungen, wie Inflammation und strahlen induzierte Seneszenz, zur Folge haben. Im Rahmen dieser Dissertation sollen mögliche Zusammenhänge zwischen H2A.J und strahlen induzierter Seneszenz, der DNA-Schadensantwort sowie dem SASP untersucht werden. Mithilfe von WI-38 Lungenfibroblasten, die zum einen eine unveränderte Expression von H2A.J durch Einbringung einer „No-Target“-Leerkassette und zum anderen einen H2A.J Knock-down aufweisen, wurden Unterschiede nach Bestrahlung eruiert. Unter Anwendung immunfluoreszenzmikroskopischer Analysen wurde die Akkumulation von H2A.J, die Effizienz der DNA-Reparatur, die Proliferation, die Seneszenz-assoziierten heterochromatischen Foci (SAHF) und die Entstehung von DNA- Segments with chromatin alterations reinforcing senescence (DNA-SCARS) untersucht. Anhand des Transmissionselektronenmikroskops (TEM) wurden zudem weitere Einblicke in die Lokalisation von H2A.J im Kontext von SAHF und DNA-SCARS gewährt. Zusätzlich wurde mittels TEM die Ultrastruktur und Entstehung von DNA-SCARS bestimmt. Der strahleninduzierte SASP wurde mithilfe eines ELISA im Zellüberstand gemessen und die Expression, der involvierten Gene, an Hand von RT-qPCR analysiert. Weiterhin wurden durch IFM-Analysen DNA-Reparaturfoci und die H2A.J Akkumulation in gealterter und ex-vivo bestrahlter humaner Epidermis bestimmt. Abschließend wurde die Langzeit-Akkumulation von H2A.J in niedrig-dosis-exponierter muriner Epidermis untersucht. In vitro Untersuchungen ergaben eine dosisabhängige Akkumulation von H2A.J nach Bestrahlung mit einer vorübergehenden H2A.J-Zunahme nach niedrigen Dosen und einer induzierten Seneszenz mit bleibender H2A.J-Expression nach hohen Dosen. Es zeigte sich zudem, dass die Effizienz der DNA-Schadensreparatur nach Bestrahlung nicht durch H2A.J beeinflusst wurde und dass der Knock-down von H2A.J keine Auswirkung auf die Seneszenzinduktion, den Proliferationsarrest und die SAHF Entwicklung hat. Im Gegensatz dazu beeinflusste der H2A.J knock-down die Ultrastruktur der DNA-SCARS; was eine potentielle Erklärung für den verminderten SASP darstellen könnte, der mithilfe von ELISA und RT-qPCR nachgewiesen wurde. Untersuchungen an humaner Epidermis zeigten zudem eine Zunahme von H2A.J analog zu einem erhöhten Aufkommen an DNA-Reparaturfoci mit zunehmendem Alter und nach Bestrahlung. Die Analyse niedrig-dosis-exponierter muriner Epidermis wies selbst 6 Monate nach Ende der Bestrahlung eine zunehmende Akkumulation von H2A.J auf, die dem Level einer 18 Monate alten Maus entsprachen. Diese Untersuchungen dienen als Grundlage um Zusammenhänge zwischen der Akkumulation von H2A.J und Bestrahlung zu erforschen und zeigen eine H2A.J-abhängige Induktion des SASP nach Bestrahlung. Schließlich zeigte sich, dass H2A.J als Biomarker für seneszente Zellen in der humanen Epidermis potentiell genutzt werden kann

Harpsichord Chamber Music at the University of Dayton

News release announces Julane Rodgers and other faculty members will give a program of Baroque and contemporary chamber music