nils-herrmann/clean_scirepeval huggingface dataset:
Lift and wakes of flying snakes

Flying snakes use a unique method of aerial locomotion: they jump from tree branches, flatten their bodies, and undulate through the air to produce a glide. The shape of their body cross-section during the glide plays an important role in generating lift. This paper presents a computational investigation of the aerodynamics of the cross-sectional shape. Two-dimensional simulations of incompressible flow past the anatomically correct cross-section of the species Chrysopelea paradisi show that a significant enhancement in lift appears at a 35° angle of attack, above Reynolds numbers 2000. Previous experiments on physical models also obtained an increased lift, at the same angle of attack. The flow is inherently three-dimensional in physical experiments, due to fluid instabilities, and it is thus intriguing that the enhanced lift also appears in the two-dimensional simulations. The simulations point to the lift enhancement arising from the early separation of the boundary layer on the dorsal surface of the snake profile, without stall. The separated shear layer rolls up and interacts with secondary vorticity in the near-wake, inducing the primary vortex to remain closer to the body and thus cause enhanced suction, resulting in higher lift.
These Are Not the K-mers You Are Looking For: Efficient Online K-mer Counting Using a Probabilistic Data Structure

K-mer abundance analysis is widely used for many purposes in nucleotide sequence analysis, including data preprocessing for de novo assembly, repeat detection, and sequencing coverage estimation. We present the khmer software package for fast and memory efficient online counting of k-mers in sequencing data sets. Unlike previous methods based on data structures such as hash tables, suffix arrays, and trie structures, khmer relies entirely on a simple probabilistic data structure, a Count-Min Sketch. The Count-Min Sketch permits online updating and retrieval of k-mer counts in memory which is necessary to support online k-mer analysis algorithms. On sparse data sets this data structure is considerably more memory efficient than any exact data structure. In exchange, the use of a Count-Min Sketch introduces a systematic overcount for k-mers; moreover, only the counts, and not the k-mers, are stored. Here we analyze the speed, the memory usage, and the miscount rate of khmer for generating k-mer frequency distributions and retrieving k-mer counts for individual k-mers. We also compare the performance of khmer to several other k-mer counting packages, including Tallymer, Jellyfish, BFCounter, DSK, KMC, Turtle and KAnalyze. Finally, we examine the effectiveness of profiling sequencing error, k-mer abundance trimming, and digital normalization of reads in the context of high khmer false positive rates. khmer is implemented in C++ wrapped in a Python interface, offers a tested and robust API, and is freely available under the BSD license at github.com/ged-lab/khmer.
On Hedging American Options Under Model Uncertainty

We consider as given a discrete time financial market with a risky asset and options written on that asset and determine both the sub- and super-hedging prices of an American option in the model independent framework of ArXiv:1305.6008. We obtain the duality of results for the sub- and super-hedging prices. For the sub-hedging prices we discuss whether the sup and inf in the dual representation can be exchanged (a counter example shows that this is not true in general). For the super-hedging prices we discuss several alternative definitions and argue why our choice is more reasonable. Then assuming that the path space is compact, we construct a discretization of the path space and demonstrate the convergence of the hedging prices at the optimal rate. The latter result would be useful for numerical computation of the hedging prices. Our results generalize those of ArXiv:1304.3574 to the case when static positions in (finitely many) European options can be used in the hedging portfolio.
How conventional measures overestimate electroweak fine-tuning in supersymmetric theory

The lack of evidence for superparticles at the CERN LHC, along with the rather high value of the Higgs mass, has sharpened the perception that supersymmetric model parameter space is highly electroweak fine-tuned (EWFT). We compare three measures of fine-tuning in SUSY models. 1. \Del_HS measures a terms containing large log contributions to m_Z that are inevitable in models defined at scales much higher than the electroweak scale. 2. \Del_BG measures variation in m_Z against variation of model parameters and allows for correlations among high scale parameters which are not included in \Del_HS. 3. The model-independent \Del_EW measures how naturally a model can generate the measured value of m_Z=91.2 GeV in terms of weak scale parameters alone. We hypothesize an overarching Ultimate Theory (UTH) wherein the high scale soft terms are all correlated. The UTH might be contained within the more general effective SUSY theories popular in the literature. For \Del_HS, EWFT can be overestimated by neglecting additional non-independent terms which lead to large cancellations. For \Del_BG, EWFT can be overestimated by applying the measure to the effective theories instead of to the UTH. The measure \Del_EW allows for the possibility of parameter correlations which should be present in the UTH and, since it is model-independent, provides the same value of EWFT for the effective theories as should occur for the UTH. We find that the well-known mSUGRA/CMSSM model is fine-tuned under all three measures so that it is unlikely to contain the UTH. The non-universal Higgs model NUHM2 appears fine-tuned with \Del_HS,BG > 10^3. But since \Del_EW can be as small as 7 (corresponding to 14% fine-tuning), it may contain the UTH for parameter ranges which allow for low true EWFT.
Dynamical foundations of the brane-induced gravity

We present a comprehensive formalism to derive precise expressions for the induced gravity of the braneworld, assuming the dynamics of the Dirac–Nambu–Goto type. The quantum fluctuations of the brane at short distances give rise to divergences, which should be cut off at the scale of the inverse thickness of the brane. It turns out that the induced-metric formula is converted into an Einstein-like equation via quantum effects. We determine the coefficients of the induced cosmological and gravity terms, as well as those of the terms including the extrinsic curvature and the normal connection gauge field. The latter is the characteristic of the brane-induced gravity theory, distinguished from ordinary non-brane-induced gravity.
A nested factor model for non-linear dependencies in stock returns

The aim of our work is to propose a natural framework to account for all the empirically known properties of the multivariate distribution of stock returns. We define and study a ‘nested factor model’, where the linear factors part is standard, but where the log-volatility of the linear factors and of the residuals are themselves endowed with a factor structure and residuals. We propose a calibration procedure to estimate these log-vol factors and the residuals. We find that whereas the number of relevant linear factors is relatively large (10 or more), only two or three log-vol factors emerge in our analysis of the data. In fact, a minimal model where only one log-vol factor is considered is already very satisfactory, as it accurately reproduces the properties of bivariate copulas, in particular, the dependence of the medial point on the linear correlation coefficient, as reported in Chicheportiche and Bouchaud [ 2012, 15]. We have tested the ability of the model to predict out-of-sample the risk of non-linear portfolios, and found that it performs significantly better than other schemes.
Singularity resolution by lattice shifts in discretized quantum mechanics

We investigate the robustness of singularity avoidance mechanisms in nonrelativistic quantum mechanics on the discretised real line when lattice points are allowed to approach a singularity of the classical potential. We consider the attractive Coulomb potential and the attractive scale invariant potential, on an equispaced parity-noninvariant lattice and on a non-equispaced parity-invariant lattice, and we examine the energy eigenvalues by a combination of analytic and numerical techniques. While the lowest one or two eigenvalues descend to negative infinity in the singular limit, we find that the higher eigenvalues remain finite and form degenerate pairs, close to the eigenvalues of a theory in which a lattice point at the singularity is regularised either by Thiemann's loop quantum gravity singularity avoidance prescription or by a restriction to the odd parity sector. The approach to degeneracy can be reproduced from a nonsingular discretised half-line quantum theory by tuning a boundary condition parameter. The results show that Thiemann's singularity avoidance prescription and the discretised half-line boundary condition reproduce quantitatively correct features of the singular limit spectrum apart from the lowest few eigenvalues.
Momentum broadening of partons on the light cone from the lattice

The jet quenching parameter describes the momentum broadening of a high-energy parton moving through the quark-gluon plasma. Following an approach originally proposed by Caron-Huot, we discuss how one can extract information on the collision kernel associated with the parton momentum broadening, from the analysis of certain gauge-invariant operators in dimensionally reduced effective theories, and present numerical results from a lattice study.
Forward Neutral Pion Cross Section and Spin Asymmetry Measurements at STAR

The STAR endcap electromagnetic calorimeter (EEMC) was designed to allow measurement of cross sections and spin observables in the forward direction, $1 < \eta < 2$ and with the full azimuth. Using the EEMC to measure double longitudinal spin asymmetries in photonic channels---such as inclusive neutral pions, prompt photon, and prompt photon + jet---allows access to $\Delta G$ within a low Bjorken-$x$ region ($0.01 < x < 0.33$ at $\sqrt{s}=200$) where $\Delta G$ is poorly constrained. Additionally, transverse spin asymmetries, shown to be zero at $\eta$ near zero and as large as 10\% at $\eta$ near 4, occupy a previously unmeasured region in the 3D pseudorapidity, transverse momentum, and $x$-Feynman phase space when measured with the EEMC. The neutral pion cross section measurement verifies that the signal of interest can be properly reconstructed and isolated from the background. Pion reconstruction techniques in the STAR EEMC will be discussed and preliminary cross-section and transverse single spin asymmetry measurements presented.
EXCESS OPTICAL ENHANCEMENT OBSERVED WITH ARCONS FOR EARLY CRAB GIANT PULSES

We observe an extraordinary link in the Crab pulsar between the enhancement of an optical pulse and the timing of the corresponding giant radio pulse. At optical through infrared wavelengths, our observations use the high time resolution of ARray Camera for Optical to Near-IR Spectrophotometry, a unique superconducting energy-resolving photon-counting array at the Palomar 200 inch telescope. At radio wavelengths, we observe with the Robert C. Byrd Green Bank Telescope and the Green Bank Ultimate Pulsar Processing Instrument backend. We see an 11.3% ± 2.5% increase in peak optical flux for pulses that have an accompanying giant radio pulse arriving near the peak of the optical main pulse, in contrast to a 3.2% ± 0.5% increase when an accompanying giant radio pulse arrives soon after the optical peak. We also observe that the peak of the optical main pulse is 2.8%  ±  0.8% enhanced when there is a giant radio pulse accompanying the optical interpulse. We observe no statistically significant spectral differences between optical pulses accompanied by and not accompanied by giant radio pulses. Our results extend previous observations of optical–radio correlation to the time and spectral domains. Our refined temporal correlation suggests that optical and radio emission are indeed causally linked, and the lack of spectral differences suggests that the same mechanism is responsible for all optical emission.
VERY WIDE BINARY STARS AS THE PRIMARY SOURCE OF STELLAR COLLISIONS IN THE GALAXY

We present numerical simulations modeling the orbital evolution of very wide binaries, pairs of stars separated by over ∼103 AU. Due to perturbations from other passing stars and the Milky Way's tide, the orbits of very wide binary stars occasionally become extremely eccentric, which forces close encounters between the companion stars. We show that this process causes a stellar collision between very wide binary companion stars once every 1000–7500 yr on average in the Milky Way. One of the main uncertainties in this collision rate is the amount of energy dissipated by dynamic tides during close (but not collisional) periastron passages. This dissipation presents a dynamical barrier to stellar collisions and can instead transform very wide binaries into close or contact binaries. However, for any plausible tidal dissipation model, very wide binary stars are an unrealized, and potentially the dominant, source of stellar collisions in our Galaxy. Such collisions should occur throughout the thin disk of the Milky Way. Stellar collisions within very wide binaries should yield a small population of single, Li-depleted, rapidly rotating massive stars.
Nuclear fission in covariant density functional theory

The current status of the application of covariant density functional theory to microscopic description of nuclear fission with main emphasis on superheavy nuclei (SHN) is reviewed. The softness of SHN in the triaxial plane leads to an emergence of several competing fission pathes in the region of the inner fission barrier in some of these nuclei. The outer fission barriers of SHN are considerably affected both by triaxiality and octupole deformation.
Cosmological perturbation theory at three-loop order

We analyze the dark matter power spectrum at three-loop order in standard perturbation theory of large scale structure. We observe that at late times the loop expansion does not converge even for large scales (small momenta) well within the linear regime, but exhibits properties compatible with an asymptotic series. We propose a technique to restore the convergence in the limit of small momentum, and use it to obtain a perturbative expansion with improved convergence for momenta in the range where baryonic acoustic oscillations are present. Our results are compared with data from N-body simulations at different redshifts, and we find good agreement within this range.
Hadronic resonances in heavy-ion collisions at ALICE

Properties of the hadronic phase of high-energy heavy-ion collisions can be studied by measuring the ratios of hadronic resonance yields to the yields of longer-lived particles. These ratios can be used to study the strength of re-scattering effects, the chemical freeze-out temperature, and the lifetime between chemical and kinetic freeze-out. The restoration of chiral symmetry during the early hadronic phase or near the phase transition may lead to shifts in the masses and increases in the widths of hadronic resonances. The ALICE collaboration has measured the spectra, masses, and widths of the K*(892)0 and ϕ(1020) resonances in Pb-Pb collisions at = 2.76 TeV. These results, including RAA and the ratios of the integrated resonance yields to stable hadron yields, are presented and compared to results from other collision systems and to theoretical predictions.
CosMO - A Cosmic Muon Observer Experiment for Students

What are cosmic particles and where do they come from? These are questions which are not only fascinating for scientists in astrophysics. With the CosMO experiment (Cosmic Muon Observer) students can autonomously study these particles. They can perform their own hands-on experiments to become familiar with modern scientific working methods and to obtain a direct insight into astroparticle physics. In this contribution we present the experimental setup and possible measurements. The detector consists of three scintillator boxes. Events are triggered and read out by a data acquisition board developed for the QuarkNet Project. With a Python program running on a netbook under Linux, the trigger and data taking conditions can be defined. The program displays the particle rates in real-time and stores the data for offline analysis. Possible student experiments are the measurement of cosmic particle rates dependent on the zenith angle, the distribution of geometrical size of particle showers, and the lifetime of muons. Twenty CosMO detectors have been built at DESY. They are used within the German outreach network Netzwerk Teilchenwelt at 15 astroparticle-research institutes and universities for project work with students.
Charmonium Potentials at Non-Zero Temperature

Department of Mathematical Physics, National University of Ireland Maynooth, Maynooth,County Kildare, jonivar@thphys.nuim.ieThe charmonium potential at non-zero temperature has been studied using gauge conﬁgurationswith anisotropic lattices and 2+1 dynamical ﬂavors of light sea quarks. We use the HAL QCDtime-dependent method developed for the study of nucleon-nucleon potentials. To serve as in-put, local-extended charmonium correlators were calculated. The results are consistent with theexpectation that the potential between heavy quarks should become deconﬁning at high tempera-tures.31st International Symposium on Lattice Field Theory LATTICE 2013July 29 - August 3, 2013Mainz, Germany
Portfolio Optimization under Small Transaction Costs: a Convex Duality Approach

We consider an investor with constant absolute risk aversion who trades a risky asset with general Ito dynamics, in the presence of small proportional transaction costs. Kallsen and Muhle-Karbe (2012) formally derived the leading-order optimal trading policy and the associated welfare impact of transaction costs. In the present paper, we carry out a convex duality approach facilitated by the concept of shadow price processes in order to verify the main results of Kallsen and Muhle-Karbe under well-defined regularity conditions.
The Aquarius comoving group is not a disrupted classical globular cluster

We present a detailed analysis of high-resolution, high S/N spectra for 5 Aquarius stream stars observed with the MIKE spectrograph on the Magellan Clay telescope. Our sample represents one third of the 15 known members in the stream. We find the stream is not mono-metallic: the metallicity ranges from [Fe/H] = -0.63 to -1.58. No anti-correlation in Na-O abundances is present, and we find a strong positive Mg-Al relationship, similar to that observed in the thick disk. We find no evidence that the stream is a result of a disrupted classical globular cluster, contrary to a previously published claim. High [(Na, Ni, ] and low [Ba/Y] abundance ratios in the stream suggests it is not a tidal tail from a disrupted dwarf galaxy, either. The stream is chemically indistinguishable from Milky Way field stars with the exception of one candidate, C222531-145437. From its position, velocity, and detailed chemical abundances, C222531-145437 is likely a star that was tidally disrupted from omega-Centauri. We propose the Aquarius stream is Galactic in origin, and could be the result from a disk-satellite perturbation in the Milky Way thick disk on the order of a few Gyr ago: derived orbits, UVW velocities, and angular momenta of the Aquarius members offer qualitative support for our hypothesis. Assuming C222531-145437 is a tidally disrupted member of omega-Centauri, this system is the most likely disk perturber. In the absence of compelling chemical and/or dynamical evidence that the Aquarius stream is the tidal tail of a disrupted satellite, we advocate the "Aquarius group" as a more appropriate description. Like the Canis Major over-density, as well as the Hercules and Monoceros groups, the Aquarius group joins the list of kinematically-identified substructures that are not actually accreted material: they are simply part of the rich complexity of the Milky Way structure.
Reducing financial avalanches by random investments.

Building on similarities between earthquakes and extreme financial events, we use a self-organized criticality-generating model to study herding and avalanche dynamics in financial markets. We consider a community of interacting investors, distributed in a small-world network, who bet on the bullish (increasing) or bearish (decreasing) behavior of the market which has been specified according to the S&P 500 historical time series. Remarkably, we find that the size of herding-related avalanches in the community can be strongly reduced by the presence of a relatively small percentage of traders, randomly distributed inside the network, who adopt a random investment strategy. Our findings suggest a promising strategy to limit the size of financial bubbles and crashes. We also obtain that the resulting wealth distribution of all traders corresponds to the well-known Pareto power law, while that of random traders is exponential. In other words, for technical traders, the risk of losses is much greater than the probability of gains compared to those of random traders.
Possible resonance effect of axionic dark matter in Josephson junctions.

We provide theoretical arguments that dark-matter axions from the galactic halo that pass through Earth may generate a small observable signal in resonant S/N/S Josephson junctions. The corresponding interaction process is based on the uniqueness of the gauge-invariant axion Josephson phase angle modulo 2π and is predicted to produce a small Shapiro steplike feature without externally applied microwave radiation when the Josephson frequency resonates with the axion mass. A resonance signal of so far unknown origin observed by C. Hoffmann et al.  is consistent with our theory and can be interpreted in terms of an axion mass m(a)c2=0.11  meV and a local galactic axionic dark-matter density of 0.05  GeV/cm3. We discuss future experimental checks to confirm the dark-matter nature of the observed signal.
Access patterns for robots and humans in web archives

Although user access patterns on the live web are well-understood, there has been no corresponding study of how users, both humans and robots, access web archives. Based on samples from the Internet Archive's public Wayback Machine, we propose a set of basic usage patterns: Dip (a single access), Slide (the same page at different archive times), Dive (different pages at approximately the same archive time), and Skim (lists of what pages are archived, i.e., TimeMaps). Robots are limited almost exclusively to Dips and Skims, but human accesses are more varied between all four types. Robots outnumber humans 10:1 in terms of sessions, 5:4 in terms of raw HTTP accesses, and 4:1 in terms of megabytes transferred. Robots almost always access TimeMaps (95% of accesses), but humans predominately access the archived web pages themselves (82% of accesses). In terms of unique archived web pages, there is no overall preference for a particular time, but the recent past (within the last year) shows significant repeat accesses.