Miracle-dz/UniFAR-FTUs huggingface dataset:
Machine-learning-based jet momentum reconstruction in heavy-ion collisions

The precise reconstruction of jet transverse momenta in heavy-ion collisions is a challenging task. A major obstacle is the large number of (mainly) low-$p_{\rm T}$ particles overlaying the jets. Strong region-to-region fluctuations of this background complicate the jet measurement and lead to significant uncertainties. In this paper, a novel approach to correct jet momenta (or energies) for the underlying background in heavy-ion collisions is introduced. The proposed method makes use of common Machine Learning techniques to estimate the jet transverse momentum based on several parameters, including properties of the jet constituents. Using a toy model and HIJING simulations, the performance of the new method is shown to be superior to the established standard area-based background estimator. The application of the new method to data promises the measurement of jets down to extremely low transverse momenta, unprecedented thus far in data on heavy-ion collisions.
NV−–N+ pair centre in 1b diamond

With the creation of nitrogen (NV) in 1b diamond it is common to find that the absorption and emission is predominantly of negatively charged NV centres. This occurs because electrons tunnel from the substitutional nitrogen atoms to NV to form NV−–N+ pairs. There can be a small percentage of neutral charge NV0 centres and a linear increase of this percentage can be obtained with optical intensity. Subsequent to excitation it is found that the line width of the NV− zero-phonon has been altered. The alteration arises from a change of the distribution of N+ ions and a modification of the average electric field at the NV− sites. The consequence is a change to the Stark shifts and splittings giving the change of the zero-phonon line (ZPL) width. Exciting the NV− centres enhances the density of close N+ ions and there is a broadening of the ZPL. Alternatively exciting and ionizing N0 in the lattice results in more distant distribution of N+ ions and a narrowing of the ZPL. The competition between NV− and N0 excitation results in a significant dependence on excitation wavelength and there is also a dependence on the concentration of the NV− and N0 in the samples. The present investigation involves extensive use of low temperature optical spectroscopy to monitor changes to the absorption and emission spectra particularly the widths of the ZPL. The studies lead to a good understanding of the properties of the NV−–N+ pairs in diamond. There is a critical dependence on pair separation. When the NV−–N+ pair separation is large the properties are as for single sites and a high degree of optically induced spin polarization is attainable. When the separation decreases the emission is reduced, the lifetime shortened and the spin polarization downgraded. With separations of <12 A0 there is even no emission. The deterioration occurs as a consequence of electron tunneling in the excited state from NV– to N+ and an optical cycle that involves NV0. The number of pairs with the smaller separations and poorer properties will increase with the number of nitrogen impurities and it follows that the degree of spin polarization that can be achieved for an ensemble of NV− in 1b diamond will be determined and limited by the concentration of single substitutional nitrogen. The information will be invaluable for obtaining optimal conditions when ensembles of NV− are required. As well as extensive measurements of the NV− optical ZPL observations of Stark effects associated with the infrared line at 1042 nm and the optically detected magnetic resonance at 2.87 GHz are also reported.
A Cancellation Nanoflare Model for Solar Chromospheric and Coronal Heating. II. 2D Theory and Simulations

Recent observations at high spatial resolution have shown that magnetic flux cancellation occurs on the solar surface much more frequently than previously thought, and so this led Priest et al. (2018) to propose magnetic reconnection driven by photospheric flux cancellation as a mechanism for chromospheric and coronal heating. In particular, they estimated analytically the amount of energy released as heat and the height of the energy release during flux cancellation. In the present work, we take the next step in the theory by setting up a two-dimensional resistive MHD simulation of two canceling polarities in the presence of a horizontal external field and a stratified atmosphere in order to check and improve upon the analytical estimates. Computational evaluation of the energy release during reconnection is found to be in good qualitative agreement with the analytical estimates. In addition, we go further and undertake an initial study of the atmospheric response to reconnection. We find that, during the cancellation, either hot ejections or cool ones or a combination of both hot and cool ejections can be formed, depending on the height of the reconnection location. The hot structures can have the density and temperature of coronal loops, while the cooler structures are suggestive of surges and large spicules.
Similarity between two scattering matrices

The similarity parameter between two scattering matrices, based on a special correlation coefficient, is presented. This parameter is not only independent of the spans of the scattering matrices, but also independent of the target orientation angles. As an application, the parameters of similarities to several typical scattering matrices are derived and used to analyse characteristics of a radar target.
Numerical investigation of transient, low-power metal vapour discharges occurring in near limit ignitions of flammable gas

This article presents an investigation of a transient (30 μs–) electrical discharge in metal vapour with low voltage () and current (), drawn between two separating electrodes. Discharges of this type are rarely studied, but are important in electrical explosion safety, as they can ignite flammable gasses. An empirical model is developed based on transient recordings of discharge voltages and currents and high speed broadband image data. The model is used for predicting the electrical waveforms and spatial power distribution of the discharge. The predicted electrical waveforms show good accuracy under various scenarios. To further investigate the underlying physics, the model is then incorporated into a simplified 3-D gas dynamics simulation of the discharge occurring in a flammable atmosphere. This simulation includes chemical reactions, molecular diffusion, heat transfer and evaporation of metal from the electrode surface. The local thermodynamic equilibrium (LTE) assumption is next used to calculate electrical conductivity from the field outputs of the simulation, which in turn is integrated to produce electrical resistance over time. This resistance is then compared to that implied by the voltage and current waveforms predicted by the empirical model. The two methods produce differing estimates, demonstrating that the studied discharge very likely deviates from LTE. Finally, assuming that electrical conductivity is approximately independent of the heavy particle temperature, the empirical model is used together with the calculated electrical conductivities to estimate the electron temperatures present in the discharge.
Spitzer Observations of Massive, Red Galaxies at High Redshift

We study massive galaxies at z ~ 1-3.5 using HST optical imaging, ground-based near-IR imaging, and Spitzer observations at 3-24 μm. From Ks-selected galaxies in the ≃130 arcmin2 GOODS-S field, we identify 153 distant red galaxies (DRGs) with (J - Ks)Vega ≥ 2.3. This sample is approximately complete in stellar mass for passively evolving galaxies above 1011 M☉ and z ≤ 3. Roughly half of the DRGs are objects whose optical and near-IR rest-frame light is dominated by evolved stars combined with ongoing star formation (at zmed ~ 2.5), and the others are galaxies whose light is dominated by heavily reddened (A1600 ≳ 4-6 mag) starbursts (at zmed ~ 1.7). Very few DRGs (≲10%) have no indication of current star formation. DRGs at z ~ 1.5-3 with stellar masses ≥1011 M☉ have specific star formation rates (SFRs per unit mass) including the reradiated far-IR emission that range from 0.2 to 10 Gyr-1. Based on the X-ray luminosities and rest-frame near-IR colors, roughly one-quarter of the DRGs contain AGNs, implying that the growth of supermassive black holes coincides with the formation of massive galaxies. At 1.5 ≤ z ≤ 3, the DRGs with M ≥ 1011 M☉ have an integrated specific SFR comparable to the global value of all galaxies. In contrast, galaxies at z ~ 0.3-0.75 with M ≥ 1011 M☉ have an integrated specific SFR less than the global value and more than an order of magnitude lower than that for massive DRGs. At z ≲ 1, lower mass galaxies dominate the overall cosmic mass assembly. This suggests that the bulk of star formation in massive galaxies occurs at early cosmic epochs and is largely complete by z ~ 1.5. Further mass assembly in these galaxies takes place with low specific SFRs.
Convection Initiation by Density Currents: Role of Convergence, Shear, and Dynamical Organization

Abstract Steady-state analytic models establish two key points concerning the impact of vertical shear on density currents and the implication for convection initiation. First, shear decreases the horizontal convergence, and therefore the mean ascent, associated with downshear propagating currents. Second, shear has a basic effect on the dynamical organization. If the downshear current travels at the speed of the ambient flow at a critical (steering) level, an overturning circulation provides deep lifting. Although mean ascent is increased by shear in the case of upshear propagating currents, the lifting is comparatively shallow because jumplike ascent occurs rather than deep overturning. The convection initiation mechanism involving the downshear current is therefore very different from the upshear case. These basic principles are borne out in two-dimensional numerical simulations. Density currents generated by a stationary cold source imposed on an initially horizontally homogeneous, sheared, and neutra.
Estimation of scour below spillways using neural networks

Information on the depth of the scour hole formed downstream of a ski-jump bucket type of energy dissipator is necessary in determining the safety of dams and adjoining structures. Traditional formulae available to predict scour depth suffer from many limitations including one arising out of the technique of data analysis commonly employed, namely, statistical regression. This paper presents an alternative to regression in the form of neural networks. A feed forward network is developed to predict the depth of the scour hole below ski-jump spillways from the specified values of head and discharge intensity. Field measurements collected from a variety of published literature are used to train the network. The validation of the developed network using observations that were not involved in the training indicated the usefulness of the neural network approach for the prediction problem under consideration. Network-yielded values are found to be more accurate than those given by the traditional equations.A matrix of weights and bias values for general use in any location is specified
The effects of musical experience on linguistic pitch perception: A comparison of Norwegian professional singers and instrumentalists

Speech prosody and music share tonal attributes well suited for studying cross‐domain transfer effects. The present study investigates whether the specific pitch experience acquired by professional singers and instrumentalists transfers to the perception of corresponding prosodic elements in a native and non‐native language. Norwegian and Mandarin words with tonal distinctions, together with corresponding hummed tones, were presented dichotically in a forced attention listening test to three groups of native Norwegian listeners: professional singers, professional instrumentalists, and nonmusicians. While instrumentalists and singers were both more accurate (higher percent correct for both ears) than nonmusicians for Mandarin linguistic and hummed tones, only instrumentalists showed positive transfer to corresponding native Norwegian stimuli. Results indicate a pattern of perceiving tonal distinctions that mirrors the pitch experience acquired through professional vocal and instrumental training: Instrumen.
On the apparent velocity of integrated sunlight. 2: 1983-1992 and comparisons with magnetograms

We report additional results in our program to monitor the wavelength stability of lines in the 2.3 micrometer spectrum of integrated sunlight. We use the McMath Fourier transform spectrometer (FTS) of the National Solar Observatory to monitor 16 delta V = 2 lines of (12)C(16)O, as well as five atomic lines. Wavenumber calibration is achieved using a low-pressure N2O absorption cell and checked against terrestrial atmospheric lines. Imperfect optical integration of the solar disk remains the principal source of error, but this error has been reduced by improved FTS/telescope collimation and observing procedures. The present results include data from an additional 13 quarterly observing runs since 1985. We continue to find that the apparent velocity of integrated sunlight is variable, in the sense of having a greater reshift at solar maximum. This is supported by the temporal dependence of the integrated light velocity, and by the presence of a correlation between velocity and the disk-averaged magnetic flux derived from Kitt Peak magnetograms. The indicated peak-to-peak apparent velocity amplitude over a solar cycle is approximately the same as the velocity amplitude of the Sun's motion about the solar system barycenter. This represents about half the amplitude which we inferred in Paper I (Deming et al. 1987), but the present result has a much greater statistical significance. Our results have implications for those investigations which search for the Doppler signatures of planetary-mass companions to solar-type stars. We contrast our results to the recent finding by McMillan et al. 1993 that solar absorption lines in the violet spectral region are wavelength-stable over the solar cycle.
Search for New Physics in e mu X Data at D0 Using Sleuth: A Quasi-Model-Independent Search Strategy for New Physics

We present a quasi-model-independent search for the physics responsible for electroweak symmetry breaking. We deﬁne ﬁnal states to be studied, and construct a rule that identiﬁes a set of relevant variables for any particular ﬁnal state. A new algorithm (“Sleuth”) searches for regions of excess in those variables and quantiﬁes the signiﬁcance of any detected excess. After demonstrating the sensitivity of the method, we apply it to the semi-inclusive channel eµX collected in 108 pb − 1 of p ¯ p collisions at √ s = 1 . 8 TeV at the DØ experiment during 1992–1996 at the Fermilab Tevatron. We ﬁnd no evidence of new high p T physics in this sample.
Electron-Spin Resonance of a La_{0.7}Sr_{0.3}MnO_{3} Slab

We have studied electron-spin resonance (ESR) spectra of a La0.7Sr0. 3MnO3 slab. Experimental results reveal that ESR spectra in the ferromagnetic (FM) region are followed with a broadly resonant mode as θ = 90°, but several modes as θ = 0°. Their spectral parameters depend strongly on θ. When keeping θ = 0° and measuring the temperature dependence of ESR spectra, it is found that several resonant modes in the FM region become a single mode in the Dysonian line-shape at temperatures T >; Tmin ≈ 1.1 TC. At Tmin, the spectral linewidth reaches to a minimum value of ΔHmin= 283 Oe. Temperature dependences of the EPR intensity above Tmin obey a function I(T) = Io exp(Ea/ kB T). Having based on the relation of I(T) ∝ χ(T) = 1/(T-Θ) , we obtained the Curie-Weiss temperature Θ to be 376 K. If using a simple relation of g = hν/ μB Hr (Hr is the resonant position, and μB is the Bohr magneton), we have found that the effective Lande factor g increases from 1.91 (around Tmin) to ~ 1.98 (at 473 K) close to the value of g = 2.0 for spin-spin interactions of Mn ions. This could be due to the additional presence of magnetic interactions, besides spin-spin interactions, such as interactions between FM clusters and/or spin-orbital coupling. Interestingly, despite the sample in the PM regime, the spectral parameters depend on the angle θ. This is assigned to an anisotropic field related to Mn 3+-Mn 4 + FM clusters persisting above Tmin. At 470 K, the anisotropy constant obtained is Ku ≈ 57 erg/cm 3, much smaller than that in the FM region.
Delayed or No Feedback? Gas Outflows in Type 2 AGNs. III.

We present gas kinematics based on the [O iii]λ5007 line and their connection to galaxy gravitational potential, active galactic nucleus (AGN) energetics, and star formation, using a large sample of ∼110,000 AGNs and star-forming (SF) galaxies at z < 0.3. Gas and stellar velocity dispersions are comparable to each other in SF galaxies, indicating that the ionized gas kinematics can be accounted by the gravitational potential of host galaxies. In contrast, AGNs clearly show non-gravitational kinematics, which is comparable to or stronger than the virial motion caused by the gravitational potential. The [O iii] velocity–velocity dispersion (VVD) diagram dramatically expands toward high values as a function of AGN luminosity, implying that the outflows are AGN-driven, while SF galaxies do not show such a trend. We find that the fraction of AGNs with a signature of outflow kinematics, steeply increases with AGN luminosity and Eddington ratio. In particular, the majority of luminous AGNs presents strong non-gravitational kinematics in the [O iii] profile. AGNs with strong outflow signatures show on average similar specific star formation rates (sSFRs) to those of star-forming galaxies. In contrast, AGNs with weak or no outflows have an order of magnitude lower sSFRs, suggesting that AGNs with current strong outflows do now show any negative AGN feedback and that it may take dynamical time to impact on star formation over galactic scales.
Long-Term Rossi X-Ray Timing Explorer Monitoring of Anomalous X-Ray Pulsars

We report on long-term monitoring of three anomalous X-ray pulsars (AXPs) using the Rossi X-Ray Timing Explorer (RXTE). We present a phase-coherent timing ephemeris for 4U 0142+61 and show that it has rotated with high stability over 4.4 yr, with rms phase deviations of 7% of the pulse period from a simple fit including only ν and . We report on the continued timing stability of 1E 2259.1+586, for which phase coherence has now been maintained over 4.5 yr, as well as on the detection of a significant in 1.4 yr of monitoring of 1RXS J170849.0-400910, consistent with recovery following a glitch. We note a correlation in which timing stability in AXPs decreases with increasing . The timing stability of soft gamma repeaters in quiescence is consistent with this trend, given their large spin-down rates. This trend is similar to one seen in radio pulsars, suggesting a connection between the three populations. We find no large variability in pulse morphology as a function of time. We present high signal-to-noise ratio average pulse profiles for each AXP and consider them as a function of energy. We find a variety of different behaviors and consider possible trends in the data. We also find no large variations in pulsed flux and set 1 σ upper limits of ~20%-30% of the mean.
Dense Molecular Clouds in the Galactic Center Region. I. HCN (J = 1--0) Data

The Galactic Center regions $-6^\circ \le l \le 6^\circ$ and $-0.8^\circ \le b \le 0.87^\circ$ are surveyed with HCN J=1$-$0 line (88.6 GHz) on a 4$'$ grid with the 14 m telescope at the Taeduk Radio Astronomy Observatory. The data complement the previous $^{13}$CO, CS, and H$_2$CO measurements (Bally \etal 1988, Zylka \etal 1992) but cover a wider area with a better or comparable resolution. The asymmetry in emission found in the $^{13}$CO observations by Bally \etal (1988) is well confirmed in this study. Interestingly, the asymmetry in HCN emission is more pronounced here: more than $80 \%$ of the overall emission is found in the first quadrant ($l>0$) and $V_{LSR}>0$. Also confirmed is the existence of several emission components in the regions forbidden by the Galactic circular rotation. The HCN maps show clear absence of both more outer galactic emissions and the 3 kpc arm component, which are both visible in the $^{13}$CO map. This implies that the HCN emission lines are not contaminated by foreground or background gas components. Therefore HCN data are particularly useful in investigating the structures of molecular clouds in the Galactic Center. The $\Delta V$s (FWHMs) of the most of the detected lines are found to be very large, \ie, about $15\sim $55 km s$^{-1}$ with the mode at $\Delta V \approx25$ km s$^{-1}$. The typical value of $\Delta V\approx 25$ km s$^{-1}$ may imply that clouds with mass of an order of $10^6 \msun$ are common in the GC region. Another trend found is that the maximum ${\Delta}V$ decreases with $l$, which may be partly due to the overlapping effects of clouds.
Solar Filament Longitudinal Oscillations along a Magnetic Field Tube with Two Dips

The large-amplitude longitudinal oscillations of solar filaments have been observed and explored for more than ten years. Previous studies are mainly based on the one-dimensional rigid flux tube model with a single magnetic dip. However, it is noticed that there might be two magnetic dips, and hence two threads, along one magnetic field line. Following the previous work, we intend to investigate the kinematics of the filament longitudinal oscillations when two threads are magnetically connected, which is done by solving one-dimensional radiative hydrodynamic equations with the numerical code MPI-AMRVAC. Two different types of perturbations are considered, and the difference from previous works resulting from the filament thread-thread interaction is investigated. We find that even with the inclusion of the thread-thread interaction, the oscillation period is modified weakly, by at most 20% compared to the traditional pendulum model with one thread. However, the damping timescale is significantly affected by the thread-thread interaction. Hence, we should take it into account when applying the consistent seismology to the filaments where two threads are magnetically connected.
Constraints on the interacting vacuum–geodesic CDM scenario

We investigate an interacting dark sector scenario in which the vacuum energy is free to interact with cold dark matter (CDM), which itself is assumed to cluster under the sole action of gravity, i.e. it is in freefall (geodesic), as in ΛCDM. The interaction is characterized by a dimensionless coupling qV(z), in general a function of redshift. Aiming to reconstruct the evolution of the coupling, we use cosmic microwave background data from Planck 2015, along with baryon acoustic oscillation, redshift space distortion, and Type Ia supernova measurements to constrain various parametrizations of qV(z). We present the full linear perturbation theory of this interacting scenario and use Monte Carlo Markov Chains (MCMC) sampling to study five different cases: two cases in which we have ΛCDM evolution in the distant past, until a set redshift ztrans, below which the interaction switches on and qV is the single-sampled parameter, with ztrans fixed at ztrans = 3000 and 0.9, respectively; a case where we allow this transition redshift to vary along with qV; a case in which the vacuum energy is zero for z > ztrans and then begins to grow once the interaction switches on; and the final case in which we bin qV(z) in four redshift bins to investigate the possibility of a dynamical interaction, reconstructing the redshift evolution of the function using Gaussian processes. We find that, in all cases where the high-redshift evolution is not modified, the results are compatible with a vanishing coupling, thus finding no significant deviation from ΛCDM.