bluuebunny/crossref_metadata_2025 huggingface dataset:
A combat aircraft mission readiness model
Authors: Burleigh C. D. , Fielding J. P.
Published: March 2023

It has always been important for military commanders to be able to rely on their equipment being available to them during a conflict. Some recent published figures, however, showed that two modern fighter aircraft were only available for missions for 47% or 56% of the time.

A simple operation simulation model was derived to show an aircraft's sensitivity to the main availability parameters. This model can be applied to any aircraft type provided that the necessary inputs can be calculated. The simulated operations were as realistic as possible, although many assumptions had to be made.

For reasons of national security it was not possible to relate this study directly to any current service aircraft, so a design project study has been used as the baseline aircraft in the simulation model. This aircraft was the 1980 Mini-CAS, developed at Cranfield Institute of Technology. This was used because all the necessary data were available or could be estimated with reasonable confidence and also the operating conditions are comparable to a number of current service types employed in the Close-Air-Support role. Thus the simulation was kept realistic and the results and conclusions are directly applicable to real and projected designs. Subsequent work checked the validity of the model by simulating an A-10 exercise and Sea Harrier operations in the Falklands conflict.

The Operations Simulation Model proved to be a satisfactory means of assessing the effectiveness of a force of aircraft under war-time conditions. It was far more flexible than the Availability and Mission Readiness equations commonly used to compare the in-service performance of aircraft and highlighted areas where resources could best be concentrated to improve availability. Further improvements are necessary however, to take account of spares shortages and the effect of adverse weather.
The flow development in a shielding jet
Authors: Baker J. N.
Published: March 2023

The flow from a high aspect ratio rectangular nozzle has been studied, so as to provide data to aid prediction of the effectiveness of this type of jet flow for acoustic shielding. Flow parameters investigated in both stationary and parallel, coflowing, airstreams, include axial centre-line velocity decay, jet width growth and velocity profile similarity. The existence of significant velocity peaks towards the edge of the jet in the plane of the major axis was observed, together with an unexpected interaction on this jet flow by an adjacent circular and subsonic jet.
The next European engine for combat aircraft
Authors: Lewis G. M.
Published: March 2023

European Aero Engine Companies assisted by National Research Establishments have a long and successful record in the design, development and manufacture of engines for high performance military fighter aircraft.

Because the cost of developing and producing a new aero engine is now so great, it has become increasingly impracticable for individual European nations to embark on such projects alone. This has resulted in recent years in a number of collaborative European engine programmes. As Fig. 1 shows, the range of European military turbofan engines now in service is largely the result of such collaboration amongst various European countries, and compares with the much more limited US involvement in design collaboration. Figure 1 also shows that the thrust range covered by European military turbofans is very comparable to that of engines of US manufacture.
The von Karman Institute for Fluid Dynamics — Teaching and Research
Authors: Ginoux Jean J.
Published: March 2023

As a member of the International group who set up the von Karman Institute for Fluid Dynamic (known at that time as the Training Centre for Experimental Aerodynamics — TCEA) Professor A. D. Young participated actively in the Institute's programme. After the death of Dr von Karman in 1963, he was nominated Chairman of the VKI Board of Directors, and still holds this position.

It is clear that the goals of the Institute, as envisaged by Dr von Karman, have been successfully met. After the first few challenging years under his leadership, it was essential to ensure that the scientific reputation of the Institute continued to be strengthened. The VKI is now recognised as a major establishment in its own right with a very high scientific reputation.
World Civil Aviation in Chaos
Authors: Taneja Nawal K.
Published: March 2023

This short note is intended as a measure of thanks to Alec Young for his encouragement and supervision of the author's PhD studies.

International air transport is a vital industry, integral to world trade, commerce and tourism. This industry has contributed substantially not only to worldwide economic growth, but also to political and sociological progress. However, in recent years the industry has fallen into chaos, to the point that many airlines find themselves either subject to unstable situations, or threatened by bankruptcies, or, in the case of state-owned airlines, in need of financial support from their governments. Competitive behaviour sometimes occurs on an under-the-table basis, interline co-operation has been deteriorating, and a clear international policy whose guidelines are accepted by everyone in the industry is absent. If the international airline industry is to continue to play a vital and dynamic role in contributing to the progress and prosperity of so many nations, then it is essential to adopt and implement policies aimed at eliminating the chaos in the industry, facilitating its healthy growth and stability, and developing international collaboration for the common good.
Design parameters and performance of two-dimensional, asymmetric, ‘sliding block’, variable Mach number, supersonic nozzles
Authors: Winarto H. , Stalker R. J.
Published: March 2023

The ‘sliding block’ asymmetric nozzle, which is mechanically simple and robust, is ideal for a small, variable Mach number supersonic wind tunnel installation, due the fact that it is affordable and relatively easy to manufacture. Until now there has been no rational procedure for selecting the correct nozzle profiles to satisfy certain predetermined nozzle performance criteria, ie, a range of operating Mach numbers and an acceptable test section flow non-uniformity over the given range. The present paper considers the minimum requirements which are sufficient and necessary to design an asymmetric nozzle and shows that these can be met by nozzles defined in terms of a shape parameter, an angular parameter and a length parameter. The lower end of the range of operating Mach numbers is determined by the choice of the overall flow turning angle. For a family of nozzles defined by a particular shape parameter, an heuristic analysis indicates how the test section flow non-uniformity must vary as a function of a variable which is a particular grouping of the angular and length parameters, and the range of operating Mach numbers. The dependence of the nozzle performance on the parameters is investigated numerically, assuming inviscid flow and utilising the method of characteristics. The result shows that the best nozzle shape is where the flow is expanded very rapidly immediately downstream of the throat. For a particular family of nozzles, the numerical analysis shows the complex relationship between nozzle performance and the angular and length parameters, which is best described in a graphical representation. As a result, the task of selecting correct profiles for sliding block nozzles is reduced to simply selecting the appropriate values of nozzle parameters from the curves supplied.
On the design of three-dimensional wind tunnel contractions
Authors: Downie J. H. , Jordinson R. , Barnes F. H.
Published: March 2023

A method is given for the calculation of incompressible inviscid flow through non-axisymmetric contracting ducts with rectangular cross-sections. The method is based on a finite difference approximation to Laplace's equation and solved by the method of successive over relaxation. In an attempt to provide practical criteria for the design of such contractions, the flows through a series of contraction shapes were calculated, each shape being based on a pair of matched elliptic arcs. This permitted choice of such parameters as length, local (ie two-dimensional) contraction ratio, position and magnitude of the maximum slope. It was found that reducing the length of the contraction also reduced its effective length, although increasing the effects of overshoot and undershoot. This could be compensated for by designing a contraction with a steep maximum slope which with associated low curvatures at entrance and exit reduced the values of overshoot and undershoot. The axial positions of maximum slope on wall and roof should be the same.

The predictions of the numerical method were tested against experiment and, in general, satisfactory comparisons were obtained.
Some effects of sweep direction and strakes for wings with sharp leading edges
Authors: Poll D. I. A. , Qiu Cheng-Hao
Published: March 2023

An experimental investigation has been carried out to compare the effects of sweep direction upon the aerodynamic characteristics of three wing planforms. The wings have biconvex aerofoil sections which allow them to be tested in both the forward-swept and backward-swept configurations without changing the section profile. Measurements of lift, drag and pitching moment have been made for angles of incidence in the range —5° to +50° at a mean chord Reynolds number of approximately 1·5 × 105 and a Mach number of 0·1. To complement the force and moment data a comprehensive series of oil-flow visualisations are also presented. In addition the aerodynamic characteristics of simple strakes (wing root fillets) have been studied for both the swept-forward and swept-back configurations.
Wing tip sails which give lower drag at all normal flight speeds
Authors: Spillman J. J. , McVitie A. M.
Published: March 2023

Wing tip sails are small lifting surfaces fitted to the wings in such a way that they use the local air flows about the wing tips, induced by the generation of lift on the wing, to produce a thrust. They act in a manner similar to that of the sail of a yacht when it is sailing close to the wind, hence their name.

Previous work, described in references 1, 2 and 3, has investigated the effects of adding sails to existing wings, extending their span and wetted area. It has long been realised that the correct use of sails is to replace part of the outer wing area with them, in other words to include them in the initial design of the wing. This note describes wind tunnel tests on a simple untapered, unswept wing to examine the benefits from such a design approach and subsequent flight tests on a Cessna Centurion to confirm them.
Mini-RPV research
Authors: Coleman R. , Robins A. J. , Frary D. J. , Stephenson R.
Published: March 2023

Early work on mini-RPVs in the former British Aircraft Corporation, Guided Weapons Division was described in a paper presented at the symposium on ‘RPVs — Roles and Technology’ held at the Royal Aeronautical Society, London in January 1976. Since then research and development work has expanded in several areas.

Significantly, the Stabileye research RPV which in prototype form had made some limited flights at that time has been developed into a payload carrying RPV system for research and development work within the UK UMA Systems Research programme.
Experimental investigations of the base pressures found on a bluff body in ground effect
Authors: Frost R. L. L.
Published: March 2023

A practical application of two-dimensional subsonic bluff body flow research can be seen in the design, construction and positioning of tall slender buildings. Similarly, from a three-dimensional viewpoint, drag reduction and vortex control is an important factor in the latest road vehicle designs. From just these two examples it can be seen that the problem of flow about a bluff body is one of major practical importance, while at the same time being of great theoretical interest. However, despite many years of extensive testing, there has been little progress made on the theoretical investigation of turbulent base flows since the foundations laid down by Kirchhoff and von Karman. The non-steady processes in the wake, in particular the complex dynamics of vortex formation, have proved to be problems of formidable size.
Helium and its relevance to the airship industry
Authors: Lloyd C. R.
Published: March 2023

Hydrogen is the medium of the past and helium is the hope of the future. I do not intend, in this paper to go into the relevant merits of helium over hydrogen and vice versa for its uses in the airship industry, for the obvious reason that most of you here today will be more knowledgeable on this particular aspect than I. What I will try and do in this paper is to give a brief background on the interesting aspects of helium and its unique characteristics.
The airship in the modern air traffic control environment
Authors: Gill G. G.
Published: March 2023

In considering the subject of this Symposium I was somewhat encouraged by a reminder of my company's first memorandum of association, written back in 1946. It is: to send and receive signals, messages and communications to and from aircraft, dirigibles and all other vehicles propelled in the air. How far-sighted those solicitors and recently demobilised airmen must have been! For although it has been the brief privilege of but very few of my air traffic control colleagues to have worked a non-dirigible a few years ago, I cannot honestly feel certain that they seriously believed that the age of the airship would dawn again. (Or did they?)
The evolution of British civil aviation since Edwards
Authors: Colegate R.
Published: March 2023

A little time ago Peter Martin suggested that it would be of some interest to airlines and others if someone from the CAA were to come along tonight and talk about the Civil Aviation Authority's future policy. We had to reply that this was something we could not usefully do at a time when we would be in the middle of our consultations with the industry about what that future policy should be. There the matter rested until July when I was discussing another matter with Peter Martin. I happened to say, in response to an observation of his, that I had in my mind a clear picture of where the industry had been, where it stands now and — perhaps rather less clearly — what the options were for its future development. Mr Martin seized upon this, believing that it would not only be interesting but even helpful to the industry and others if I were to share this personal vision with you. He may be right.

In any event that is how I come to be standing here before you tonight, in essence to talk about my own view of the industry as it was and as it is, together perhaps with a few glimpses of the way things might develop in future.
The application of dynamic soaring to man powered flight
Authors: Sherwin Keith
Published: March 2023

With the achievement of a man powered flight across the English Channel by Bryan Allen flying the ‘Gossamer Albatross’ aircraft in 1979, attention is now centred on new performance objectives for man powered aircraft.

In the long term it is widely recognised that man powered flight must develop as a sport and this requires an improvement in the design and construction of the necessary aircraft. It is anticipated that this trend will be stimulated in the short term by speed competitions which will encourage the design and construction of compact man powered aircraft.

With such compact machines the prospect of sporting flights for duration no longer relies on the reduction of the pilot's continuous power input, but on the utilisation of help from the atmosphere, in particular, by using dynamic soaring techniques.
Attitude estimation and control of a flexible spacecraft using inertial and optical measurements
Authors: Horton D. , Fenton J. , Gill K. F.
Published: March 2023

It is envisaged that future earth resources satellites will be required to perform frequent attitude manoeuvres and also to maintain a given orientation to within a few seconds of arc. These requirements place a severe demand on the attitude measurement and control systems used, and this, demand is increased when the satellite needs to carry large flexible solar arrays.

By combining inertial and optical measurements using an optimal filter, an attitude estimate can be obtained for which the error components are minimised over a wide frequency band. Jude, used intermittent star sensor readings to update the attitude and gyroscope drift estimates from an optimal filter and he noted that it would be useful to study the effect of mismatch between actual sensor models and those assumed in the computation of the optimal filter. Jude's recommendation is investigated in this paper.
Optimal low-level pursuit and evasion
Authors: Large E.
Published: March 2023

It is possible, and even probable, that the next generation of defensive missiles will use modern methods of optimal control of the interception trajectory. Miniaturised computing is becoming so readily available that it becomes feasible to compute the optimal trajectory to the interception point.

Consider a ground site, defended by a surface-to-air missile, which is being attacked by a low-level intruder aircraft. As soon as the intruder is attacked, by launching the defensive missile, the intruder attempts to avoid interception by using evasive tactics; the intruder becomes the evader and the defensive missile the pursuer. When both the pursuer and evader use optimal tactics, the one to achieve interception and the other to avoid it, the result becomes the outcome of a game of pursuit and evasion, as described by Isaacs in Reference 1.
Spin: angles and inertial moments
Authors: Yangos Patroclos J. , Yangos John P.
Published: March 2023

‘Young lady, a spin is like a love affair;

you don't notice how you get into it

and it is very hard to get out of!’

Theodore von Karman to Amy Johnson*

The serious mathematical complications of the kinetics of the aeroplane spin have given birth to methods of explanation based on assumptions and simplifications, the application of which, not unfrequently, has led to confusion and misunderstanding on the part of the student, let alone error on the part of the initiator of the method.

One of the problems, is the selection of the geometric parameters that have to be introduced as opposed to those which may be left out of the picture. Obviously, in such complex movement as the spin, the most obscure parameters are the angles of the motion. Unfortunately, there is a minimum number of such angles which is necessary and if one, hopefully, begins with a lesser number, one soon finds that the rest have to be put in place, even tardily, if the puzzle is to be completed.
Helicopter engine technology — with particular reference to the Rolls-Royce Gem engine
Authors: lewis Dennis
Published: March 2023

Any aero engine designer works against a background of a list of general desirable features for all engines of:

Low acquisition costs

Low operating costs

High reliability

Good performance and fuel efficiency

Ease of maintenance

In the helicopter business however, the engine designer is faced with a real dilemma. On the one hand there is the desire to produce an engine which has as wide an application as possible, (i.e. turboshaft, turboprop, turbofan, APU, industrial power generator, marine traction etc) and this produces a basically low cost, high volume, production flow provided that the required changes in the engine configuration are kept to a minimum.
Some possibilities for composite light aircraft construction
Authors: Webb J. H.
Published: March 2023

The College of Aeronautics has a considerable interest in composite materials, and in their application in particular to aerospace vehicles, over a number of years, and during this time we have conducted several research programmes on these types of materials.

During recent years, an area of research which has attracted our interest is in the application of composite materials to light aircraft, forming part of a more general study of light aircraft which has resulted in our constructing and testing aircraft in this category on two occasions in recent years.

Some of the work on these programmes has been conducted by students at Cranfield studying for higher degrees, and I acknowledge my indebtedness to them for some of the results presented in this paper.
Barnes Wallis — Designer (1887-1979)
Authors: Boorer N.W.
Published: March 2023

The Royal Aeronautical Society and the Weybridge Branch have given me a great honour in inviting me to deliver this unique lecture in memory of one of its distinguished Honorary Fellows.

The life and achievements of Sir Barnes Wallis (Fig. 1) have been well chronicled and broadcast. It is with some trepidation, therefore that I make this contribution, but as one of many at Weybridge who worked directly under his authority, I would like in paying this tribute to feel that I am representing all of them. In a lecture of about 75 minutes it is not possible to give proper justice to the work of a man who devoted something like 70 years to engineering design. He was already 16 years old and in his last year at school when the Wright Brothers were the first to fly, in 1903; he was still in full-time employment when Concorde flew in 1969. Although not involved in either of these epics, his own career was studded with many achievements, and even after his retirement he continued to work on visionary projects.
Shock wave reflection from supersonic sea-skimming — a first look
Authors: Moss G. M.
Published: March 2023

There is currently some interest in supersonic sea-skimming as a possible terminal phase for anti-ship guided weapons. The flight of a supersonic vehicle, close to a density interface, will produce an additional series of shock waves from the reflection of the shock waves generated by the vehicle from the interface. The angle of reflection of these shock waves will depend, interalia,on the slope of the surface upon which they are incident. Given a surface with a periodic positional displacement, such as would be produced by a train of surface waves, the variation in position of the reflected shocks, in relation to the generating vehicle, will also be periodic in nature. This coherent motion could produce periodically fluctuating forces and moments on the vehicle generating the incident shocks and these, in turn, could cause stability or control problems for the missile autopilot.
Aircraft that fly backwards? The application of forward swept wings
Authors: Howe Dennis
Published: March 2023

It was recognised over 40 years ago that sweeping the wing of an aircraft could be used to offset the effects of compressibility. However, by no means all of the earlier swept-back wing aircraft used sweep for performance reasons. Some, such as the Horten tailless gliders built in Germany, had swept back wings to ensure necessary longitudinal stability. Likewise the Messerschmitt Me163 rocket interceptor employed a swept back wing as an essential feature of its layout but it operated at a sufficiently high Mach number for the beneficial aerodynamic effects of sweep to be of value. From the compressibility point of view, the wing may be either swept back or swept forward, and the idea of forward sweep was incorporated in the Junkers Ju287 jet propelled bomber (Fig. 1). The 18 degrees forward sweep enabled the wing-fuselage intersection to be positioned behind the deep bomb-bay and thus avoided a difficult structural cut-out problem. A more elegant solution to the same difficulty was the ‘crescent’ swept-back wing layout for the Handley-Page Victor bomber.
Chronotype is differentially associated with lifetime mood and panic-agoraphobic spectrum symptoms in patients with bipolar disorder and healthy controls
Authors: Cruz-Sanabria Francy , Violi Miriam , Bazzani Andrea , Bruno Simone , Massoni Leonardo , Bertelloni Carlo Antonio , Dell’Oste Valerio , Frumento Paolo , Faraguna Ugo , Dell’Osso Liliana , Carmassi Claudia
Published: March 2023

Objective

Although the association between chronotype and mood disorders has been consistently reported, conversely, attempts to measure the association between chronotype and anxiety symptoms have generated inconsistent results. We aimed at evaluating whether chronotype (assessed through subjective and objective measures) is associated with lifetime mood and panic-agoraphobic spectrum symptoms in healthy controls (HCs) and in patients with bipolar disorder (BD).

Methods

Overall, 173 subjects, patients with BD in euthymic phase (n = 76) and HC (n = 97), were evaluated through the reduced Morningness–Eveningness Questionnaire (rMEQ), actigraphy monitoring and mood and panic-agoraphobic spectrum self-report (MOODS-SR and PAS-SR). The discrepancy between objective (actigraphic-based) versus subjective (rMEQ-based) circadian typology was estimated through the Circadian Classification Discrepancy Index (CCDI).

Results

rMEQ-based evening chronotype (ET) was associated with higher scores in MOODS-SR depressive and rhythmicity and vegetative functions domains in HC and BD.Both ET and morning chronotypes (MT) were associated with higher PAS-SR scores in BD only. Actigraphic-based MT was associated with higher MOODS-SR depressive scores in HC. Likewise, the discrepancy between actigraphic-based and rMEQ-based circadian typology was associated with depressive symptoms in HC only.

Conclusion

Self-reported ET was consistently associated with mood symptoms, while associations with panic-agoraphobic symptoms only emerged in BD and involved both extreme chronotypes. The discrepancy between the preferred circadian typology (rMEQ-based) and the actual one (actigraphic-based) could contribute to depressive symptoms in HC. These results pave the way for interventional studies targeting circadian typology in an attempt to prevent or treat mental health disorders.
A Markov Chain Model for the Evolution of Sex Ratio
Authors: Stark Alan E. , Seneta Eugene
Published: March 2023

A model in the form of a Markov chain is constructed to mimic variations in the human sex ratio. It is illustrated by simulation. The equilibrium distribution is shown to be a simple modification of the binomial distribution. This enables an easy calculation of the variation in sex ratio which could be expected in small populations.
Forecast Skill of the Arctic Sea Ice Outlook 2008–2022
Authors: Blanchard‐Wrigglesworth Edward , Bushuk Mitchell , Massonnet François , Hamilton Lawrence C. , Bitz Cecilia M. , Meier Walter N. , Bhatt Uma S.
Published: March 2023

We assess the skill of forecasts of Arctic September sea ice in the Sea Ice Outlook over 2008–2022. The multi‐model median June initialized forecast of September sea ice extent (SIE) is slightly more skilled (RMSE = 0.48 million km2) than a damped anomaly forecast, but July and August initialized forecasts (RMSE = 0.52 and 0.36 million km2 respectively) do not beat this benchmark. The skill of individual dynamical and statistical SIE forecasts is lower than the multi‐model median forecast skill. Overall skill is lower than expected from retrospective forecasts. Several forecasts initialized in early September 2021 and 2022 imply physically improbable values. Spatial forecasts of sea ice concentration show multi‐model forecast skill and an improvement in individual forecast skill in recent years. Initial conditions show large spread in sea ice volume and a positive correlation between initialized sea ice volume and September SIE forecast. Summer weather has an impact on forecast error.
Analytical Model for Graded Sediment Transport in Velocity‐ and Acceleration‐Skewed Oscillatory Sheet Flow
Authors: Hu Xinyu , Chen Xin
Published: March 2023

An analytical model is proposed for graded sediment transport in velocity‐ and acceleration‐skewed oscillatory sheet flow. The model consists of periodic velocity and sediment concentration formulae over a mobile sediment bed. An active layer is set below the mobile sediment bed level to handle erosion differences among size fractions. The model accounts for velocity phase lead, sediment phase lag, velocity and acceleration asymmetries, and gradation effects. The model is validated using datasets of velocity, concentration, sediment flux, and transport rate. Better performance is obtained by the model when compared to previous formulae. Discussion is conducted for net boundary layer flow, total, and fractional sediment fluxes under both velocity‐ and acceleration‐skewed oscillatory flows, and the result shows the existence of inhibited or promoted transport for different size fractions. The model is applied to describe the sediment size grading curve at different levels. The composition of transported sediment is different from the initial bed composition. The fining of sediment above the initial bed and the coarse below the initial bed are reproduced by the model, which reveals the vertical sorting processes at different locations. Meanwhile, interactions between fractions are substantial in the sheet flow layer but are insignificant in the suspension layer. The model is suitable for non‐cohesive sediment mixtures consisting of fine, medium, and coarse proportions and has implications for predicting nearshore‐graded sediment transport and sorting processes.
Cocaine induces locomotor sensitization through a dopamine-dependent VTA-mPFC-FrA cortico-cortical pathway in male mice
Authors: Wang Lun , Gao Min , Wang Qinglong , Sun Liyuan , Younus Muhammad , Ma Sixing , Liu Can , Shi Li , Lu Yang , Zhou Bo , Sun Suhua , Chen Guoqing , Li Jie , Zhang Quanfeng , Zhu Feipeng , Wang Changhe , Zhou Zhuan
Published: March 2023

As a central part of the mammalian brain, the prefrontal cortex (PFC) has been implicated in regulating cocaine-induced behaviors including compulsive seeking and reinstatement. Although dysfunction of the PFC has been reported in animal and human users with chronic cocaine abuse, less is known about how the PFC is involved in cocaine-induced behaviors. By using two-photon Ca2+ imaging to simultaneously record tens of intact individual networking neurons in the frontal association cortex (FrA) in awake male mice, here we report that a systematic acute cocaine exposure decreased the FrA neural activity in mice, while the chemogenetic intervention blocked the cocaine-induced locomotor sensitization. The hypoactivity of FrA neurons was critically dependent on both dopamine transporters and dopamine transmission in the ventromedial PFC (vmPFC). Both dopamine D1R and D2R neurons in the vmPFC projected to and innervated FrA neurons, the manipulation of which changed the cocaine-induced hypoactivity of the FrA and locomotor sensitization. Together, this work demonstrates acute cocaine-induced hypoactivity of FrA neurons in awake mice, which defines a cortico-cortical projection bridging dopamine transmission and cocaine sensitization.
Accelerating network layouts using graph neural networks
Authors: Both Csaba , Dehmamy Nima , Yu Rose , Barabási Albert-László
Published: March 2023

Graph layout algorithms used in network visualization represent the first and the most widely used tool to unveil the inner structure and the behavior of complex networks. Current network visualization software relies on the force-directed layout (FDL) algorithm, whose high computational complexity makes the visualization of large real networks computationally prohibitive and traps large graphs into high energy configurations, resulting in hard-to-interpret “hairball” layouts. Here we use Graph Neural Networks (GNN) to accelerate FDL, showing that deep learning can address both limitations of FDL: it offers a 10 to 100 fold improvement in speed while also yielding layouts which are more informative. We analytically derive the speedup offered by GNN, relating it to the number of outliers in the eigenspectrum of the adjacency matrix, predicting that GNNs are particularly effective for networks with communities and local regularities. Finally, we use GNN to generate a three-dimensional layout of the Internet, and introduce additional measures to assess the layout quality and its interpretability, exploring the algorithm’s ability to separate communities and the link-length distribution. The novel use of deep neural networks can help accelerate other network-based optimization problems as well, with applications from reaction-diffusion systems to epidemics.
Shape control in 2D molecular nanosheets by tuning anisotropic intermolecular interactions and assembly kinetics
Authors: Dreher Maximilian , Dombrowski Pierre Martin , Tripp Matthias Wolfgang , Münster Niels , Koert Ulrich , Witte Gregor
Published: March 2023

Since molecular materials often decompose upon exposure to radiation, lithographic patterning techniques established for inorganic materials are usually not applicable for the fabrication of organic nanostructures. Instead, molecular self-organisation must be utilised to achieve bottom-up growth of desired structures. Here, we demonstrate control over the mesoscopic shape of 2D molecular nanosheets without affecting their nanoscopic molecular packing motif, using molecules that do not form lateral covalent bonds. We show that anisotropic attractive Coulomb forces between partially fluorinated pentacenes lead to the growth of distinctly elongated nanosheets and that the direction of elongation differs between nanosheets that were grown and ones that were fabricated by partial desorption of a complete molecular monolayer. Using kinetic Monte Carlo simulations, we show that lateral intermolecular interactions alone are sufficient to rationalise the different kinetics of structure formation during nanosheet growth and desorption, without inclusion of interactions between the molecules and the supporting MoS2substrate. By comparison of the behaviour of differently fluorinated molecules, experimentally and computationally, we can identify properties of molecules with regard to interactions and molecular packing motifs that are required for an effective utilisation of the observed effect.
Robust automated backbone triple resonance NMR assignments of proteins using Bayesian-based simulated annealing
Authors: Bishop Anthony C. , Torres-Montalvo Glorisé , Kotaru Sravya , Mimun Kyle , Wand A. Joshua
Published: March 2023

Assignment of resonances of nuclear magnetic resonance (NMR) spectra to specific atoms within a protein remains a labor-intensive and challenging task. Automation of the assignment process often remains a bottleneck in the exploitation of solution NMR spectroscopy for the study of protein structure-dynamics-function relationships. We present an approach to the assignment of backbone triple resonance spectra of proteins. A Bayesian statistical analysis of predicted and observed chemical shifts is used in conjunction with inter-spin connectivities provided by triple resonance spectroscopy to calculate a pseudo-energy potential that drives a simulated annealing search for the most optimal set of resonance assignments. Termed Bayesian Assisted Assignments by Simulated Annealing (BARASA), a C++ program implementation is tested against systems ranging in size to over 450 amino acids including examples of intrinsically disordered proteins. BARASA is fast, robust, accommodates incomplete and incorrect information, and outperforms current algorithms – especially in cases of sparse data and is sufficiently fast to allow for real-time evaluation during data acquisition.
Integrating terrestrial and aquatic ecosystems to constrain estimates of land-atmosphere carbon exchange
Authors: Casas-Ruiz Joan P. , Bodmer Pascal , Bona Kelly Ann , Butman David , Couturier Mathilde , Emilson Erik J. S. , Finlay Kerri , Genet Hélène , Hayes Daniel , Karlsson Jan , Paré David , Peng Changhui , Striegl Rob , Webb Jackie , Wei Xinyuan , Ziegler Susan E. , del Giorgio Paul A.
Published: March 2023

In this Perspective, we put forward an integrative framework to improve estimates of land-atmosphere carbon exchange based on the accumulation of carbon in the landscape as constrained by its lateral export through rivers. The framework uses the watershed as the fundamental spatial unit and integrates all terrestrial and aquatic ecosystems as well as their hydrologic carbon exchanges. Application of the framework should help bridge the existing gap between land and atmosphere-based approaches and offers a platform to increase communication and synergy among the terrestrial, aquatic, and atmospheric research communities that is paramount to advance landscape carbon budget assessments.
Safeguarding pollinators requires specific habitat prescriptions and substantially more land area than suggested by current policy
Authors: Pindar Alana , Raine Nigel E.
Published: March 2023

Habitat loss and fragmentation are major drivers of global pollinator declines, yet even after recent unprecedented periods of anthropogenic land-use intensification the amount of habitat needed to support insect pollinators remains unknown. Here we use comprehensive pan trap bee survey datasets from Ontario, Canada, to determine which habitat types are needed and at what spatial scales to support wild bee communities. Safeguarding wild bee communities in a Canadian landscape requires 11.6–16.7% land-cover from a diverse range of habitats (~ 2.6–3.7 times current policy guidelines) to provide targeted habitat prescriptions for different functional guilds over a variety of spatial scales, irrespective of whether conservation aims are enhancing bee species richness or abundance. Sensitive and declining habitats, like tallgrass woodlands and wetlands, were important predictors of bee biodiversity. Conservation strategies that under-estimate the extent of habitat, spatial scale and specific habitat needs of functional guilds are unlikely to protect bee communities and the essential pollination services they provide to both crops and wild plants.
Investigations on the morpho-anatomy and histochemistry of the European mistletoe: Viscum album L. subsp. album
Authors: de Almeida Valter Paes , Monchak Irailson Thierry , da Costa Batista João Vitor , Grazi Mirio , Ramm Hartmut , Raman Vijayasankar , Baumgartner Stephan , Holandino Carla , Manfron Jane
Published: March 2023

Viscum albumL. (Santalaceae) is an important medicinal plant traditionally used to treat several diseases, including cancer therapy. This paper provides detailed morpho-anatomical characteristics of the leaves, stems and berries ofViscum albumsubsp.albumgrowing as hemi-parasite on the branches ofMalus domestica(Suckow) Borkh. (Rosaceae) to aid species identification and botanical characterization. Additionally, for the first time, microchemical analyses of all tissues and Energy Dispersive X-Ray Spectroscopy analyses of the calcium oxalate crystals are provided for the first time. The plant features leathery presents green leaves with parallel veins, small yellow unisexual flowers in 3-flowered cymes, and the dioecious inflorescences usually consist of three flowers, with female flowers generating white fleshy berries, in which a seed is embedded in the mucilaginous mesocarp, normally containing two embryos. Anatomically, the analyzed leaves were isobilateral and amphistomatic, and showed straight anticlinal epidermal cell walls, thick cuticles with epicuticular wax crystalloids, and paracytic stomata. The midrib is flat on both sides and has a single vascular bundle, whereas the strongly shortened petiole is concave-convex in shape and contains five bundles. The stems show a primary structure with a ring of nine vascular bundles enclosing the pith. Calcium oxalate druses and cubic and quadrangular prisms were observed in different plant parts. The results of this study provide new microscopy information that can help in the authentication of mistletoe raw materials.
Elucidating the molecular mechanisms of essential oils' insecticidal action using a novel cheminformatics protocol
Authors: Corrêa Eduardo José Azevedo , Carvalho Frederico Chaves , de Castro Oliveira Júlia Assunção , Bertolucci Suzan Kelly Vilela , Scotti Marcus Tullius , Silveira Carlos Henrique , Guedes Fabiana Costa , Melo Júlio Onésio Ferreira , de Melo-Minardi Raquel Cardoso , de Lima Leonardo Henrique França
Published: March 2023

Essential oils (EOs) are a promising source for novel environmentally safe insecticides. However, the structural diversity of their compounds poses challenges to accurately elucidate their biological mechanisms of action. We present a new chemoinformatics methodology aimed at predicting the impact of essential oil (EO) compounds on the molecular targets of commercial insecticides. Our approach merges virtual screening, chemoinformatics, and machine learning to identify custom signatures and reference molecule clusters. By assigning a molecule to a cluster, we can determine its most likely interaction targets. Our findings reveal that the main targets of EOs are juvenile hormone-specific proteins (JHBP and MET) and octopamine receptor agonists (OctpRago). Three of the twenty clusters show strong similarities to the juvenile hormone, steroids, and biogenic amines. For instance, the methodology successfully identified E-Nerolidol, for which literature points indications of disrupting insect metamorphosis and neurochemistry, as a potential insecticide in these pathways. We validated the predictions through experimental bioassays, observing symptoms in blowflies that were consistent with the computational results. This new approach sheds a higher light on the ways of action of EO compounds in nature and biotechnology. It also opens new possibilities for understanding how molecules can interfere with biological systems and has broad implications for areas such as drug design.
The secure judgment of graphic similarity against malicious adversaries and its applications
Authors: Liu Xin , Xu Yang , Luo Dan , Xu Gang , Xiong Neal , Chen Xiu-Bo
Published: March 2023

With the advent of the era of big data, privacy computing analyzes and calculates data on the premise of protecting data privacy, to achieve data ‘available and invisible’. As an important branch of secure multi-party computation, the geometric problem can solve practical problems in the military, national defense, finance, life, and other fields, and has important research significance. In this paper, we study the similarity problem of geometric graphics. First, this paper proposes the adjacency matrix vector coding method of isomorphic graphics, and use the Paillier variant encryption cryptography to solve the problem of isomorphic graphics confidentiality under the semi-honest model. Using cryptography tools such as elliptic curve cryptosystem, zero-knowledge proof, and cut-choose method, this paper designs a graphic similarity security decision protocol that can resist malicious adversary attacks. The analysis shows that the protocol has high computational efficiency and has wide application value in terrain matching, mechanical parts, biomolecules, face recognition, and other fields.
Dose optimization in surgical prophylaxis: sub-inhibitory dosing of vancomycin increases rates of biofilm formation and the rates of surgical site infection
Authors: Brothers Kimberly M. , Parker Dana M. , Taguchi Masashi , Ma Dongzhu , Mandell Jonathan B. , Thurlow Lance L. , Byrapogu Venkata C. , Urish Kenneth L.
Published: March 2023

Antibiotic stewardship is viewed as having great public health benefit with limited direct benefit to the patient at the time of administration. The objective of our study was to determine if inappropriate administration of antibiotics could create conditions that would increase the rates of surgical infection. We hypothesized that sub-MIC levels of vancomycin would increase Staphylococcus aureus growth, biofilm formation, and rates of infection. S. aureus MRSA and MSSA strains were used for all experiments. Bacteria were grown planktonically and monitored using spectrophotometry. Quantitative agar culture was used to measure planktonic and biofilm bacterial burden. A mouse abscess model was used to confirm phenotypes in vivo. In the planktonic growth assay, increases in bacterial burden at ¼ MIC vancomycin were observed in USA300 JE2 by 72 h. Similar findings were observed with ½ MIC in Newman and SH1000. For biofilm formation, USA300 JE2 at ¼ and ½ MIC vancomycin increased biofilm formation by approximately 1.3- and 2.3-fold respectively at 72 h as compared to untreated controls. Similar findings were observed with Newman and SH1000 with a 2.4-fold increase in biofilm formation at ½ MIC vancomycin. In a mouse abscess model, there was a 1.2-fold increase with sub-MIC vancomycin at 3 days post infection. Our study showed that Sub-optimal vancomycin dosing promoted S. aureus planktonic growth and biofilm formation, phenotypic measures of bacterial virulence. This phenotype induced by sub-MIC levels of vancomycin was also observed to increase rates of infection and pathogenesis in our mouse model. Risks of exposure to sub-MIC concentrations with vancomycin in surgical procedures are greater as there is decreased bioavailability in tissue in comparison to other antibiotics. This highlights the importance of proper antibiotic selection, stewardship, and dosing for both surgical prophylaxis and treatment of infection.
Revealing the dynamics of ultrarelativistic non-equilibrium many-electron systems with phase space tomography
Authors: Funkner Stefan , Niehues Gudrun , Nasse Michael J. , Bründermann Erik , Caselle Michele , Kehrer Benjamin , Rota Lorenzo , Schönfeldt Patrik , Schuh Marcel , Steffen Bernd , Steinmann Johannes L. , Weber Marc , Müller Anke-Susanne
Published: March 2023

The description of physical processes with many-particle systems is a key approach to the modeling of numerous physical systems. For example in storage rings, where ultrarelativistic particles are agglomerated in dense bunches, the modeling and measurement of their phase-space distribution is of paramount importance: at any time the phase-space distribution not only determines the complete space-time evolution but also provides fundamental performance characteristics for storage ring operation. Here, we demonstrate a non-destructive tomographic imaging technique for the 2D longitudinal phase-space distribution of ultrarelativistic electron bunches. For this purpose, we utilize a unique setup, which streams turn-by-turn near-field measurements of bunch profiles at MHz repetition rates. To demonstrate the feasibility of our method, we induce a non-equilibrium state and show that the phase-space distribution microstructuring as well as the phase-space distribution dynamics can be observed in great detail. Our approach offers a pathway to control ultrashort bunches and supports, as one example, the development of compact accelerators with low energy footprints.