bluuebunny/crossref_metadata_2025_split huggingface dataset:
On the equations of motion for an aircraft with an internal moving load which is then dropped
Authors: Bernstein L. 
Published: February 2023

AbstractEquations of motion have been developed for the situation in which a substantial load, carried internally by an aircraft, is drawn along a ramp by an extraction parachute and is then dropped. The motion of the load is assumed to remain in the plane of symmetry. The perturbations to the aircraft motion are assumed to be small so that the equations can be linearised following the representation of the aerodynamic out-of-balance forces using conventional aerodynamic derivatives. The resulting system of six ordinary differential equations consists of the four normally associated with the longitudinally-perturbed motion of the aircraft (slightly modified by the reaction forces due to the load), together with two describing the motion of the load.Numerical solutions are presented for a generic aircraft, the investigation examining the effects of a number of different parameters such as the ratio of the mass of the load to that of the aircraft, the length and angle of the ramp, the friction between the load and the ramp and the direction of the parachute extraction force. In addition the effects of employing various control strategies to limit the disturbed motion have also been computed.It was found that the acceleration of the load, relative to the aircraft, was sensibly constant. In the absence of any resetting of the controls (elevators and throttle), the disturbances computed exceeded those for which the linearisation is justified. When the controls were reset, either as the load began to move or as it was jettisoned, to the trim values appropriate to the unloaded aircraft flying at the same speed, the disturbances were reduced, but remained large, the phugoid mode being dominant. The incorporation of various kinds of feedback from the disturbance variables to the elevator was also investigated and a successful control strategy was identified, that limited the perturbations and minimised the steady-state errors in airspeed and angle of climb.
Combined effect of wall suction and riblets on a low Rθ turbulent boundary layer
Authors: Djenidi L. , Antonia R. A. , Hundseid J. , Krogstad P. A. 
Published: February 2023

AbstractA low Reynolds number turbulent boundary layer is subjected to a relatively strong rate of suction, which is applied through a short porous strip. Downstream of the strip, the effectiveness of a riblet surface is assessed by comparison,to that of a smooth wall. Measured mean velocity and longitudinal turbulence intensity profiles indicate that the riblets do not hinder the action the suction can have on the flow.
A note on the Prandtl number effect on laminar heat transfer and recovery
Authors: van Oudheusden B. W. 
Published: February 2023

AbstractA critical revision is made of the classic power-law expressions that describe the effect of the Prandtl number on laminar heat transfer and temperature recovery for Pr near one, by applying a perturbation analysis to the energy equation for constant-property flow. In this way, the Pr dependence is obtained as a systematic asymptotic expansion up to any desired order, which provides a more accurate and convenient procedure than classic curve-fitting methods. The effect of pressure gradient and flow sweep are examined for self-similar yawed wedge flows.
Homogeneous wall boundary condition for oscillatory flow in slotted tunnels
Authors: Mabey D.G. 
Published: February 2023

Abstract
The aerodynamic interference between oscillating models and the walls of slotted windtunnels is controlled by the homogeneous wall boundary condition, which has hitherto been uncertain. In this report a new homogeneous boundary condition for slotted tunnels is suggested which incorporates the important effects of plenum chamber depth and slot parameter.In particular, this new boundary condition controls the transverse resonance frequencies of the tunnel, which represent a severe form of wall interference. Hence a comparison of measured resonance frequencies with predictions based on such a boundary condition provides a good test of its correctness.The new homogeneous boundary condition complements that obtained previously for a perforated tunnel and is essentially similar in character. The boundary condition is applicable to oscillatory flows at frequencies ranging from quasi-steady values to multiples of the first resonance frequency.
Measurements of velocities in the near field of a lobed forced mixer trailing edge
Authors: Yu S. C. M. , Yip T. H. 
Published: February 2023

Abstract
Previous experimental studies have shown that the development of flow behind the trailing edge of a lobed forced mixer is greatly influenced by the formation of large-scale streamwise vortices. The main objective of the present study is to establish quantitatively the presence and role of the streamwise vortices in the mixing layer in the near field of a lobed forced mixer trailing edge. The near field was defined as the region within five wavelengths (of the trailing edge profile) from the trailing edge. A two-stream mixing layer with a velocity ratio of 0.6 was generated with initially turbulent boundary layers and nominally two-dimensional flow. Mean flow and turbulence measurements were made on fine cross-plane grids across the wake region and at several streamwise locations using a two-component laser-doppler anemometer. Production of turbulent kinetic energy existed in most parts of the near field enhancing the overall mixing process. The streamwise vortex development underwent a three-step process by which it was formed, intensified and quickly dissipated towards the end of the near field. The distance between two rows of streamwise vortices of alternate signs within a lobe reduced with downstream distance causing the amalgamation and annihilation of the vortices. Analysing this movement of vortices, based on inviscid vortex dynamics, suggested that the normal vortices shed at the trailing edge had actually provided a squeezing (pinched off) effect to two adjacent rows of streamwise vortices within a lobe, forcing them to interact with each other.
Two-dimensional implicit flux split steady and unsteady Euler calculations using unstructured moving grids
Authors: Sinhamahapatra K. P. , Singh N. 
Published: February 2023

AbstractTwo-dimensional Euler equations are solved on unstructured triangular meshes using commonly available minicomputers. The driving algorithm is an upwind biased implicit cell-centred finite volume scheme. The spatial discretisation involves a naturally dissipative flux-split approach that sharply captures Shockwaves. The grid generation method uses a type of advancing front technique which triangulates a given set of points. To demonstrate the application, the steady flow results are presented for single and two component aerofoils. The unsteady results are obtained using a dynamic mesh algorithm for an aerofoil pitching harmonically about the quarter chord. The paper presents a description of the grid generation and movement algorithm and of the Euler solver, along with results and comparison that assess their capabilities.
Seeking Protection and Reconciliation: A Pashtun Legal Custom in Recorded Tribal Histories
Authors: Pelevin Mikhail 
Published: February 2023

AbstractAvailable essays on Pashtunwali describe this system of customary laws and ethics for the most part as a static model of ideal conduct, without a diachronic perspective. Offering a historical approach to Pashtunwali, this article introduces and analyzes fragmentary data on the nənawāte custom from early modern Pashto sources—historiographical narratives of the Khatak chieftains in the Tarikh-i Murassaʿ (finished 1724) and the romantic poem Adam Khan aw Durkhaney (1706/7). Recorded cases of resorting to nənawāte, considered among the main pillars of Pashtunwali but still variously interpreted, prove that this is a complex legal custom based on the right to appeal for protection, mediation, and reconciliation. As a common means of dispute settlement, nənawāte originates with a binding request for help and favor in a conflict situation. The discussion of nənawāte is preceded by a brief overview of the existing scholarly definitions of Pashtunwali, underscoring its emic perception as an ethnic identity marker.
One for All? State Violence and Insurgent Cohesion
Authors: Schubiger Livia Isabella 
Published: February 2023

AbstractWhat effect does state violence have on the cohesiveness and fragmentation of insurgent organizations? This article develops a theory of how state violence against civilians affects insurgent cohesion and fragmentation in civil war. It argues that the state-led collective targeting of an armed group's alleged civilian constituency increases the probability of insurgent fragmentation, defined as the process through which insurgent organizations split into distinct entities, each with its own social composition, goals, and leadership. This effect is driven by the interaction of several mechanisms at the individual, group, and organizational levels: state-led collective targeting enlarges the supply of fresh recruits, strengthens the bonds between immediate group members (interpersonal cohesion), and disrupts intra-organizational coordination, strategic unity, and institutional arrangements that underpin the commitment of individual fighters to the organization as a whole (ideological cohesion). The implications of this argument are empirically tested in an analysis of armed groups fighting against their governments between 1946 and 2008. The results suggest that campaigns of massive state violence directed against the civilian constituency of rebel groups increase the overall risk of insurgent fragmentation, a finding that has important implications for the duration and escalation of civil wars.
Patent Trolls and the Market for Acquisitions
Authors: Dayani Arash 
Published: February 2023

AbstractI study the effect of patent-infringement claims by patent trolls on acquisitions of small firms. Exploiting staggered adoption of state anti-patent troll laws, I find that the laws have two effects. First, the number of acquisitions of small firms declines after these laws are adopted. Second, the anti-troll laws increase the acquisition price for acquirers. The market reflects the increased cost of acquisition as measured by lower acquisition announcement returns. Large firms increase R&D after the adoption of state laws, replacing external innovation. Using a sample of acquisitions that are plausibly unaffected by the laws, I disentangle alternative explanations.
Relative Richardson varieties
Authors: CHAN MELODY , PFLUEGER NATHAN 
Published: February 2023

AbstractA Richardson variety in a flag variety is an intersection of two Schubert varieties defined by transverse flags. We define and study relative Richardson varieties, which are defined over a base scheme with a vector bundle and two flags. To do so, we generalise transversality of flags to a relative notion, versality, that allows the flags to be non-transverse over some fibers. Relative Richardson varieties share many of the geometric properties of Richardson varieties. We generalise several geometric and cohomological facts about Richardson varieties to relative Richardson varieties. We also prove that the local geometry of a relative Richardson variety is governed, in a precise sense, by the two intersecting Schubert varieties, giving a generalisation, in the flag variety case, of a theorem of Knutson–Woo–Yong; we also generalise this result to intersections of arbitrarily many relative Schubert varieties. We give an application to Brill–Noether varieties on elliptic curves, and a conjectural generalisation to higher genus curves.
Random feedback shift registers and the limit distribution for largest cycle lengths
Authors: Arratia Richard A. , Canfield E. Rodney , Hales Alfred W. 
Published: February 2023

AbstractFor a random binary noncoalescing feedback shift register of width$n$, with all$2^{2^{n-1}}$possible feedback functions$f$equally likely, the process of long cycle lengths, scaled by dividing by$N=2^n$, converges in distribution to the same Poisson–Dirichlet limit as holds for random permutations in$\mathcal{S}_N$, with all$N!$possible permutations equally likely. Such behaviour was conjectured by Golomb, Welch and Goldstein in 1959.
Energy and international business cycles
Authors: Kim Myunghyun 
Published: February 2023

AbstractUS output is more strongly correlated with the output of energy-exporting countries than with that of energy-importing countries. I first document this empirical finding, then construct a three-country model in which countries’ different energy production and trade structures are considered. The three countries are the USA (an energy importer), a non-US energy importer, and an energy exporter. Consistent with the empirical findings, the model produces a higher output correlation between the USA and the energy exporter than between the USA and the energy importer. A positive productivity shock in the USA, raising its output, leads to increases in energy prices and its import demand for energy. The increased energy prices adversely influence output in the energy importer, whereas the rise in US energy imports has positive effects on output in the energy exporter, enabling the correlation of US output with the exporter’s output to be higher.
Systematic and Temporal Geochemical Changes in the Upper Deccan Lavas: Implications for the Magma Plumbing System of Flood Basalt Provinces
Authors: Hoyer P. A. , Haase K. M. , Regelous M. , Fluteau F. 
Published: February 2023

AbstractLarge Igneous Provinces (LIPs) are unusual volcanic events in which massive amounts of melt (∼106 km3) erupt in relatively short time periods (<106 years). Most LIP magmas have undergone extensive fractional crystallization and crustal contamination, but the crustal magmatic plumbing systems and the processes triggering eruptions are poorly understood. We present new major and trace element and radiogenic isotope data for 43 individual lava flows from a continuous 1,200 m thick stratigraphic profile through the upper, most voluminous part of the Deccan LIP (Bushe to Mahabaleshwar Formations). Eruption rates for this section are constrained by published paleomagnetic directions and absolute U‐Pb ages for zircons from weathered flow tops exposed in the profile. We find four magmatic sequences each lasting ∼104–∼105 years during which major and trace element compositions change systematically, followed by an abrupt change in geochemistry at the start of a new sequence. Within each sequence, the MgO content and proportion of crustal contamination decrease progressively, indicating a continuous replenishment of the associated magma reservoirs with less contaminated but more evolved melts. These geochemical signatures are best explained by repeated episodes of melt recharge, mixing, and eruption of variably evolved magmas originating from relatively small magma reservoir located in different crustal levels.
Long‐Term Prediction of Sudden Stratospheric Warmings With Geomagnetic and Solar Activity
Authors: Vokhmyanin Mikhail , Asikainen Timo , Salminen Antti , Mursula Kalevi 
Published: February 2023

AbstractThe polar vortex is a strong jet of westerly wind which forms each winter around the polar stratosphere. Sometimes, roughly every other winter, the polar vortex in the Northern Hemisphere experiences a dramatic breakdown and associated warming of the polar stratosphere. Such events are called sudden stratospheric warmings (SSWs) and they are known to have a significant influence on ground weather in Northern Eurasia and large parts of North America. Typically, these events are thought to occur due to planetary waves propagating to the stratosphere where they may disrupt the vortex. Here, we show that the SSW probability depends significantly on a favorable combination of geomagnetic and solar activity and the phase of the Quasi‐Biennial Oscillation (QBO). Using logistic regression models, we find that more SSWs occur when early‐winter geomagnetic activity (aa index) is low and QBO winds are easterly and when solar activity (F10.7 index) is high and QBO winds are westerly. We then examine the possibility of using these results to predict the occurrence probability of SSWs with several months lead time and evaluate the optimal lead times for all variables using cross‐validation methods. As a result, we find that the SSW probability can be predicted rather well and we can issue a probabilistic SSW prediction for the coming winter season with a success ratio of about 86% already in the preceding August. The results presented here are an important step toward improving the seasonal predictability of wintertime weather using information about solar and geomagnetic activity.
Carbon Dioxide Retrievals From NOMAD‐SO on ESA's ExoMars Trace Gas Orbiter and Temperature Profile Retrievals With the Hydrostatic Equilibrium Equation: 2. Temperature Variabilities in the Mesosphere at Mars Terminator
Authors: Trompet L. , Vandaele A. C. , Thomas I. , Aoki S. , Daerden F. , Erwin J. , Flimon Z. , Mahieux A. , Neary L. , Robert S. , Villanueva G. , Liuzzi G. , López‐Valverde M. A. , Brines A. , Bellucci G. , Lopez‐Moreno J. J. , Patel M. R. 
Published: February 2023

AbstractThe Solar Occultation (SO) channel of the Nadir and Occultation for Mars Discovery (NOMAD) instrument scans the Martian atmosphere since 21 April 2018. In this work, we present a subset of the NOMAD SO data measured at the mesosphere. We focused on a spectral range that started to be recorded in Martian year (MY) 35. A total of 968 vertical profiles of carbon dioxide density and temperature covering MY 35 and the beginning of MY 36 were investigated until 135° of solar longitude. We compared 47 profiles with co‐located profiles of the Mars Climate Sounder onboard the Mars Reconnaissance Orbiter. Most profiles show a good agreement as SO temperatures are only 1.8 K higher, but some biases lead to an average absolute difference of 7.4°K. The SO data set is also compared with simulations from the Global Environmental Multiscale‐Mars general circulation model. Both data sets are in good agreement except for the presence of a cold layer in the winter hemisphere and a warm layer at dawn in the Northern hemisphere for solar longitudes between 240° and 360°. Five profiles contain temperatures lower than the limit for CO2 condensation. Strong warm layers were found in 13.5% of the profiles. They are present mainly at dawn and in the winter hemisphere, while the Northern dusks appear featureless. The data set mainly covers high latitudes around 60° and we derived some non‐migrating tides. In the Southern winter hemisphere, we derived apparent zonal wavenumber‐1 (WN‐1) and WN‐3 tidal components with a maximum amplitude of 10% and 5% at 63 km, respectively.
Tandem Observations of Nighttime Mid‐Latitude Topside Ionospheric Perturbations
Authors: Song Hosub , Park Jaeheung , Jin Yaqi , Otsuka Yuichi , Buchert Stephan , Lee Jaejin , Yi Yu 
Published: February 2023

AbstractNighttime medium‐scale traveling ionospheric disturbances (MSTIDs) have been generally observed by ground‐based instruments. However, they provide 2‐dimensional images over only a limited field of view and are not distributed globally. The ground‐based observations reported that MSTID wavefronts exhibit backward‐C shapes virtually straddling the dip equator. In situ plasma density measurements onboard individual satellites could overcome the limited coverage of ground‐based MSTID observations. But, most of those spacecrafts could obtain only 1‐dimensional profiles of plasma density, which leaves uncertain whether the observed perturbations generally have the characteristic directivity of MSTIDs. This paper addresses this knowledge gap by statistically investigating nighttime perturbations in the mid‐latitude topside ionosphere observed by tandem satellites, Swarm A and C. We cross‐correlate the plasma density profiles observed by Swarm A and C. The correlation coefficient tends to increase as the two spacecraft move closer, allowing us to derive the disturbances' directivity whenever the Swarm A and C observations are correlated significantly. The directivity statistics agree well with the backward‐C shape. Furthermore, the wavefront directions have clear dependence on magnetic latitudes while they are not as well aligned with local time, which is also consistent with previous reports on nighttime MSTIDs using ground‐based observations and computer simulations. Additionally, we demonstrate that the nighttime MSTIDs can increase the topside Rate Of Total electron content Index above Swarm. All the above‐mentioned results support that the nighttime mid‐latitude perturbations observed by Swarm can be identified as MSTIDs on the whole, which is the most important finding of this paper.
MYT1L haploinsufficiency in human neurons and mice causes autism-associated phenotypes that can be reversed by genetic and pharmacologic intervention
Authors: Weigel Bettina , Tegethoff Jana F. , Grieder Sarah D. , Lim Bryce , Nagarajan Bhuvaneswari , Liu Yu-Chao , Truberg Jule , Papageorgiou Dimitris , Adrian-Segarra Juan M. , Schmidt Laura K. , Kaspar Janina , Poisel Eric , Heinzelmann Elisa , Saraswat Manu , Christ Marleen , Arnold Christian , Ibarra Ignacio L. , Campos Joaquin , Krijgsveld Jeroen , Monyer Hannah , Zaugg Judith B. , Acuna Claudio , Mall Moritz 
Published: February 2023

AbstractMYT1L is an autism spectrum disorder (ASD)-associated transcription factor that is expressed in virtually all neurons throughout life. How MYT1L mutations cause neurological phenotypes and whether they can be targeted remains enigmatic. Here, we examine the effects of MYT1L deficiency in human neurons and mice. Mutant mice exhibit neurodevelopmental delays with thinner cortices, behavioural phenotypes, and gene expression changes that resemble those of ASD patients. MYT1L target genes, including WNT and NOTCH, are activated upon MYT1L depletion and their chemical inhibition can rescue delayed neurogenesis in vitro. MYT1L deficiency also causes upregulation of the main cardiac sodium channel, SCN5A, and neuronal hyperactivity, which could be restored by shRNA-mediated knockdown of SCN5A or MYT1L overexpression in postmitotic neurons. Acute application of the sodium channel blocker, lamotrigine, also rescued electrophysiological defects in vitro and behaviour phenotypes in vivo. Hence, MYT1L mutation causes both developmental and postmitotic neurological defects. However, acute intervention can normalise resulting electrophysiological and behavioural phenotypes in adulthood.