ShantanuT01/DACTYL-Pretraining huggingface dataset:
Slip activation, slip band interactions, and GND densities in iron-base, galling resistant alloy Nitronic 60 have been characterised at the grain length scale using small-scale mechanical testing with high resolution digital image correlation and high-angular resolution electron backscatter diffraction. By correlating the two measurement techniques, new insight into slip band interactions, the generation of lattice curvature and the corresponding accumulation of geometrically necessary dislocations (GNDs) is provided. Multiple discrete slip bands are typically active within single grains, resulting in significant slip band interactions. Crossing slip bands were found to generate accumulations of GNDs. Regions where slip bands block other slip bands were associated with the highest GND densities, in excess of three time the densities of crossing slip bands. Representative crystal plasticity modelling investigations have demonstrated that discrete slip blocking events are responsible for locally elevated GND density. This behaviour is rationalised in terms of lattice curvature associated with the differing levels of constraint provided by the crossing or blocking-type behaviours. Ferrite grains are also found to contribute to the generation of GNDs. Together, these two effects provide significant work hardening mechanisms, likely to be key to the development of future iron-base hard facing alloys.
Strong [OIII]$\lambda\lambda$4959,5007+H$\beta$ emission appears to be typical in star-forming galaxies at z > 6.5. As likely contributors to cosmic reionization, these galaxies and the physical conditions within them are of great interest. At z > 6.5, where Ly$\alpha$ is greatly attenuated by the intergalactic medium, rest-UV metal emission lines provide an alternative measure of redshift and also constraints on the physical properties of star-forming regions and massive stars. We present the first statistical sample of rest-UV line measurements in z $\sim$ 2 galaxies selected as analogs of those in the reionization era based on [OIII]$\lambda\lambda$4959,5007 EW or rest-frame U-B color. Our sample is drawn from the 3D-HST Survey and spans the redshift range 1.36 $\leqslant$ z $\leqslant$ 2.49. We find that the median Ly$\alpha$ and CIII]$\lambda\lambda$1907,1909 EWs of our sample are significantly greater than those of z $\sim$ 2 UV-continuum-selected star-forming galaxies. Measurements from both individual and composite spectra indicate a monotonic, positive correlation between CIII] and [OIII], while a lack of trend is observed between Ly$\alpha$ and [OIII] at [OIII] EW < 1000$\unicode{x212B}$. At higher [OIII] EW, extreme Ly$\alpha$ emission starts to emerge. Using stacked spectra, we find that Ly$\alpha$ and CIII] are significantly enhanced in galaxies with lower metallicity. Two objects in our sample appear comparable to z > 6.5 galaxies with exceptionally strong rest-UV metal line emission. These objects have significant CIV$\lambda\lambda$1548,1550, HeII$\lambda$1640, and OIII]$\lambda\lambda$1661,1665 emission in addition to intense Ly$\alpha$ or CIII]. Detailed characterization of these lower-redshift analogs provides unique insights into the physical conditions in z > 6.5 star-forming regions, motivating future observations of reionization-era analogs at lower redshifts.
A program is outlined, and first results described, in which fully three-dimensional, time dependent simulations of hydrodynamic turbulence are used as a basis for theoretical investigation of the physics of turbulence in stars. The inadequacy of the treatment of turbulent convection as a diffusive process is discussed. A generalization to rotation and magnetohydrodynamics is indicated, as are connection to simulations of 3D stellar atmospheres.
Aims. This work investigates the potential of using the wavelength-dependence of galaxy structural parameters (S\'ersic index, n, and effective radius, Re) to separate galaxies into distinct types. Methods. A sample of nearby galaxies with reliable visual morphologies is considered, for which we measure structural parameters by fitting multi-wavelength single-S\'ersic models. Additionally, we use a set of artificially redshifted galaxies to test how these classifiers behave when the signal-to-noise decreases. Results. We show that the wavelength-dependence of n may be employed to separate visually-classified early- and late-type galaxies, in a manner similar to the use of colour and n. Furthermore, we find that the wavelength variation of n can recover galaxies that are misclassified by these other morphological proxies. Roughly half of the spiral galaxies that contaminate an early-type sample selected using (u-r) versus n can be correctly identified as late-types by N, the ratio of n measured in two different bands. Using a set of artificially-redshifted images, we show that this technique remains effective up to z ~ 0.1. N can therefore be used to achieve purer samples of early-types and more complete samples of late-types than using a colour-n cut alone. We also study the suitability of R, the ratio of Re in two different bands, as a morphological classifier, but find that the average sizes of both early- and late-type galaxies do not change substantially over optical wavelengths.
Efficient error-mitigation techniques demanding minimal resources is key to quantum information processing. We propose a generic protocol to mitigate quantum errors using detection-based quantum autoencoders. In our protocol, the quantum data are compressed into a latent subspace while leaving errors outside, the latter of which is then removed by a measurement and post-selection. Compared to previously developed methods, our protocol on the one hand requires no extra qubits, and on the other hand has a near-optimal denoising power, in which under reasonable requirements all errors detected outside of the latent subspace can be removed, while those inside the subspace cannot be removed by any means. Our detection-based quantum autoencoders are therefore particularly useful for near-term quantum devices in which controllable qubits are limited while noise reduction is important.
Our aim in this article is to produce new examples of semistable Lazarsfeld- Mukai bundles on smooth projective surfaces $X$ using the notion of parabolic vector bundles. In particular, we associate natural parabolic structures to any rank two (dual) Lazarsfeld-Mukai bundle and study the parabolic stability of these parabolic bundles. We also show that the orbifold bundles on Kawamata coverings of $X$ corresponding to the above parabolic bundles are themselves certain (dual) Lazarsfeld-Mukai bundles. This gives semistable Lazarsfeld-Mukai bundles on Kawamata covers of the projective plane and of certain K3 surfaces.
This article reviews six historically important papers in the development of the theory of measurement for nonlocal variables in quantum mechanics, with special emphasis the non violation of relativistic causality. Spanning more than seventy years, we chart the major developments in the field from the declaration, by Landau and Peierls in 1931, that measurement of nonlocal variables was impossible in the relativistic regime to the demonstration, by Vaidman in 2003, that all such variables \emph{can} be measured instantaneously without violation of causality through an appropriate act of "measurement", albeit not of a standard projective (Von Neumann) type.
[Background] Proton-induced knockout reactions of the form $(p,pN)$ have experienced a renewed interest in recent years due to the possibility of performing these measurements with rare isotopes, using inverse kinematics. Several theoretical models are being used for the interpretation of these new data, such as the distorted-wave impulse approximation (DWIA), the transition amplitude formulation of the Faddeev equations due to Alt, Grassberger and Sandhas (FAGS) and, more recently, a coupled-channels method here referred to as transfer-to-the-continuum (TC).   [Purpose] Our goal is to compare the momentum distributions calculated with the DWIA and TC models for the same reactions, using whenever possible the same inputs (e.g. distorting potential). A comparison with already published results for the FAGS formalism is performed as well.   [Method] We choose the $^{15}$C($p$,$pn$)$^{14}$C reaction at an incident energy of 420 MeV/u, which has been previously studied with the FAGS formalism. The knocked-out neutron is assumed to be in a $2s$ single-particle orbital. Longitudinal and transverse momentum distributions are calculated for different assumed separation energies.   [Results] For all cases considered, we find a very good agreement between DWIA and TC results. The energy dependence of the distorting optical potentials is found to affect in a modest way the shape and magnitude of the momentum distributions. Moreover, when relativistic kinematics corrections are omitted, our calculations reproduce remarkably well the FAGS result.   [Conclusions] The results found in this work provide confidence on the consistency and accuracy of the DWIA and TC models for analyzing momentum distributions for $(p,pn)$ reactions at intermediate energies.
We present model X-ray spectra of accreting black holes with advection-dominated accretion flows, paying attention to thermal emission lines from the hot plasma. We show that the Advanced X-ray Astrophysical Facility (AXAF) might be able to observe lines from X-ray binaries such as V404 Cyg in quiescence, the Galactic Center black hole Sagittarius A*, and the nuclei of nearby galaxies such as M87. Line intensities can provide new diagnostics to study the accreting plasma in these and related systems.
The Kibble-Zurek (KZ) mechanism has been applied to a variety of systems ranging from low temperature Bose-Einstein condensations to grand unification scales in particle physics and cosmology and from classical phase transitions to quantum phase transitions. Here we show that finite-time scaling (FTS) provides a detailed improved understanding of the mechanism. In particular, the finite time scale, which is introduced by the external driving (or quenching) and results in FTS, is the origin of the division of the adiabatic regimes from the impulse regime in the KZ mechanism. The origin of the KZ scaling for the defect density, generated during the driving through a critical point, is not that the correlation length ceases growing in the nonadiabatic impulse regime, but rather, is that it is taken over by the effective finite length scale corresponding to the finite time scale. We also show that FTS accounts well for and improves the scaling ansatz proposed recently by Liu, Polkovnikov, and Sandvik [Phys. Rev. B {\bf 89}, 054307 (2014)]. Further, we show that their universal power-law scaling form applies only to some observables in cooling but not to heating. Even in cooling, it is invalid either when an appropriate external field is present. However, this finite-time-finite-size scaling calls for caution in application of FTS. Detailed scaling behaviors of the FTS and finite-size scaling, along with their crossover, are explicitly demonstrated, with the dynamic critical exponent $z$ being estimated for two- and three-dimensional Ising models under the usual Metropolis dynamics. These values of $z$ are found to give rise to better data collapses than the extant values do in most cases but take on different values in heating and cooling in both two- and three-dimensional spaces.
In this paper we study the existence of minimizers for a class of constrained minimization problems that are invariant under translations. We call $$I_{\rho^{2}}:=\inf_{B_{\rho}}I(u) \ $$ where $B_{\rho}=\{u\in H^{m}(\R^{N}):\|u\|_{2}=\rho\},$ and $I(u)=1/2\|u\|^{2}_{D^{m,2}}+T(u)$, $T$ fulfilling general assumptions. We show that the regularity of the function $$(0,\infty)\ni s \mapsto I_{s^2}\,$$ and the behaviour of $\frac{I_{s^2}}{s^2}$ in the neighborhood of zero allows to prove the strong subadditivity inequality. As byproduct the strong convergence of the minimizing sequences (up to translations) is proved. We give an application to the energy functional $I$ associated to the Schr\"odinger-Poisson equation in $\R^{3}$ orbitally stable standing waves with arbitray charge for the following Schr\"odinger-Poisson type equation \label{SP} i\psi_{t}+ \Delta \psi - (|x|^{-1}*|\psi|^{2}) \psi+|\psi|^{p-2}\psi=0 \text{in} \R^{3}, \text{with} \ 2<p<3. When $2<p<3$, In particular we prove that $I$ achieves its minimum on the constraint $\{u\in H^{1}(\R^{3}): \|u\|_{2}=\rho\}$ for every $\rho>0$ and, as a consequence, the set of minimizers is orbitally stable. This covers the physically relevant case, $p=8/3$, the so called Schr\"odinger-Poisson-Slater system.
Thermal expansion and forced magnetostriction of MnSi were measured as a function of temperature down to 5 K and magnetic field to 3 T. The small length (volume) discontinuity at the magnetic phase transition in MnSi decreases with application of magnetic field to a value $\Delta L/L \sim 10^{-7}$, and then suddenly the discontinuity seemingly jumps to zero. Thermal expansivity peaks strongly deteriorate with magnetic fields. No specific features identifying a tricritical point were observed. We propose that the Frenkel concept of heterophase fluctuations may be relevant in the current case. Therefore, we suggest that the magnetic phase transition in MnSi always remains first order at any temperature and magnetic field, but the transition is progressively smoothed by heterophase fluctuations. These results question the applicability of a model of a fluctuation-induced first order phase transition for MnSi. Probably a model of coupling of an order parameter with other degrees of freedom is more appropriate.
We consider the issue of an accurate description of the evolution of the non-singlet structure function moments $M_n(Q)$ near heavy quark threshold. To this aim we propose a simple modification of the standard massless \MSbar scheme approach to the next-to-leading QCD analysis of DIS data. We apply it to the processing of the modern CCFR data for $xF_3$ structure function and extract the value of $\alpha_s(M_z) \approx 0.108 \pm 0.004$ We check also the consistency of light gluino hypothesis with CCFR data.
This paper refers to Langlands' big set of notes [L] devoted to the question if the (normalized) local Hecke-Tate root number $\Delta=\Delta(E,\chi)$, where $E$ is a finite separable extension of a fixed non-archimedean local field $F$, and $\chi$ a quasicharacter of $E^\times$, can be appropriately extended to a local $\varepsilon$-factor $\varepsilon_\Delta=\varepsilon_\Delta(E,\rho)$ for all virtual representations $\rho$ of the corresponding Weil group $W_E.$ Whereas Deligne [D] has given a relatively short proof by using the global Artin-Weil L-functions, the proof of Langlands is purely local and splits into two parts: the {\bf algebraic part} to find a minimal set of relations for the functions $\Delta$, such that the existence (and uniqueness) of $\varepsilon_\Delta$ will follow from these relations; and the more extensive {\bf arithmetic part} to give a direct proof that all these relations are actually fulfilled. Our aim is to cover the algebraic part of Langlands' notes which can be done completely in the framework of representations of solvable profinite groups, where two modifications of Brauer's theorem play a prominent role.   Introduction / 1. The notion of extendible functions / 2. The kernel of the Brauer map and its generating relations / 3. A criterion for the extendibility of functions / 4. Recovering Theorem 3.1 for the case of local root numbers / Appendices A1. Proving Brauer 3 and Brauer 4 / A2. On type-III-groups.
Digital signs(such as barcode or QR code) are widely used in our daily life, and for many applications, we need to localize them on images. However, difficult cases such as targets with small scales, half-occlusion, shape deformation and large illumination changes cause challenges for conventional methods. In this paper, we address this problem by producing a large-scale dataset and adopting a deep learning based semantic segmentation approach. Specifically, a synthesizing method was proposed to generate well-annotated images containing barcode and QR code labels, which contributes to largely decrease the annotation time. Through the synthesis strategy, we introduce a dataset that contains 30000 images with Barcode and QR code - Barcode-30k. Moreover, we further propose a dual pyramid structure based segmentation network - BarcodeNet, which is mainly formed with two novel modules, Prior Pyramid Pooling Module(P3M) and Pyramid Refine Module(PRM). We validate the effectiveness of BarcodeNet on the proposed synthetic dataset, and it yields the result of mIoU accuracy 95.36\% on validation set. Additional segmentation results of real images have shown that accurate segmentation performance is achieved.
Let $\cal{P}$ be the family of all 2-connected plane triangulations with vertices of degree three or six. Gr\"{u}nbaum and Motzkin proved (in the dual terms) that every graph $P \in \cal{P}$ is factorable into factors $P_0$, $P_1$, $P_2$ (indexed by elements of the cyclic group $Q = \{0,1,2\}$) such that every factor $P_q$ consists of two induced paths with the same length $M(q)$, and $K(q)-1$ induced cycles with the same length $2M(q)$. For $q \in Q$, we define an integer $S^+(q)$ such that the vector $(K(q), M(q), S^+(q))$ determines the graph $P$ (if $P$ is simple) uniquely up to orientation-preserving isomorphism. We establish arithmetic equations that will allow calculate the vector $(K(q+1), M(q+1), S^+(q+1))$ by the vector $(K(q), M(q), S^+(q))$, $q \in Q$. We present some applications of the equations. The set $\{(K(q), M(q), S^+(q)): q \in Q\}$ is called the orbit of $P$. We characterize one point orbits of graphs in $\cal{P}$. We prove that if $P$ is of order $4n +2$, $n \in\mathbb{N}$, than it has a Hamilton bond such that the end-trees of the bond are equitable 2-colorable and have the same order. We prove that if $M(q)$ is odd and $K(q) \geqslant \frac{M(q)}{3}$, then there are two disjoint induced paths of the same order, which vertices together span all of $P$.
In this work the efficiency of particle acceleration at the forward shock right after the SN outburst for the particular case of the well-known SN 1993J is analyzed. Plasma instabilities driven by the energetic particles accelerated at the shock front grow over intraday timescales and drive a fast amplification of the magnetic field at the shock, that can explain the magnetic field strengths deduced from the radio monitoring of the source. The maximum particle energy is found to reach 1-10 PeV depending on the instability dominating the amplification process. We derive the time dependent particle spectra and the associated hadronic signatures of secondary particles arising from proton proton interactions. We find that the Cherenkov Telescope Array (CTA) should easily detect objects like SN 1993J in particular above 1 TeV, while current generation of Cherenkov telescopes such as H.E.S.S. could only marginally detect such events. The gamma-ray signal is found to be heavily absorbed by pair production process during the first week after the outburst. We predict a low neutrino flux above 10 TeV, implying a detectability horizon with a KM3NeT-type telescope of 1 Mpc only. We finally discuss the essential parameters that control the particle acceleration and gamma-ray emission in other type of SNe.
We propose a new model-independent method to test the cosmic curvature by comparing the proper distance and transverse comoving distance. Using the measurements of Hubble parameter $H(z)$ and angular diameter distance $d_A$, the cosmic curvature parameter $\Omega_K$ is constrained to be $-0.09\pm0.19$, which is consistent with a flat universe. We also use Monte Carlo simulation to test the validity and efficiency, and find that our method can give a reliable and efficient constraint on cosmic curvature. Compared with other model-independent methods testing the cosmic curvature, our method can avoid some drawbacks and give a better constraint.
We analyse deformation mechanism in neutron-rich Cr, Fe and Ti isotopes with N=32-44 by means of a Skyrme-Hartree-Fock-Bogoliubov mean-field code employing a two-dimensional mesh representation in the cylindrical coordinate system. Evaluating systematically the quadrupole deformation energy, we show that the Skyrme parameter set SkM* gives a quadrupole instability around the neutron number N$\sim$38-42 in Cr isotopes, where the deformation energy curve suggests a transitional behavior with a shallow minimum extending to a large prolate deformation. Roles of a deformed N=38 gap and the position of the neutron g9/2 orbit are analysed in detail.
Transition-metal dichalcogenides (WTe$_2$ and MoTe$_2$) have drawn much attention, recently, because of the nonsaturating extremely large magnetoresistance (XMR) observed in these compounds in addition to the predictions of likely type-II Weyl semimetals. Contrary to the topological insulators or Dirac semimetals where XMR is linearly dependent on the field, in WTe$_2$ and MoTe$_2$ the XMR is nonlinearly dependent on the field, suggesting an entirely different mechanism. Electron-hole compensation has been proposed as a mechanism of this nonsaturating XMR in WTe$_2$, while it is yet to be clear in the case of MoTe$_2$ which has an identical crystal structure of WTe$_2$ at low temperatures. In this paper, we report low-energy electronic structure and Fermi surface topology of MoTe$_2$ using angle-resolved photoemission spectrometry (ARPES) technique and first-principle calculations, and compare them with that of WTe$_2$ to understand the mechanism of XMR. Our measurements demonstrate that MoTe$_2$ is an uncompensated semimetal, contrary to WTe$_2$ in which compensated electron-hole pockets have been identified, ruling out the applicability of charge compensation theory for the nonsaturating XMR in MoTe$_2$. In this context, we also discuss the applicability of the existing other conjectures on the XMR of these compounds.
We present simultaneous, multi-wavelength observations of the Small Magellanic Cloud Be/XRB IGR J01217-7257 (=SXP 2.16) during outbursts in 2014, 2015 and 2016. We also present the results of RXTE observations of the Small Magellanic Cloud during which the source was initially discovered with a periodicity of 2.1652$\pm$0.0001 seconds which we associate with the spin period of the neutron star. A systematic temporal analysis of long term Swift/BAT data reveals a periodic signal of 82.5$\pm$0.7 days, in contrast with a similar analysis of long base line OGLE I-band light curves which reveals an 83.67$\pm$0.05 days also found in this work. Interpreting the longer X-ray periodicity as indicative of binary motion of the neutron star, we find that outbursts detected by INTEGRAL and Swift between 2014 and 2016 are consistent with Type I outbursts seen in Be/XRBs, occurring around periastron. Comparing these outbursts with the OGLE data, we see a clear correlation between outburst occurrence and increasing I-band flux. A periodic analysis of subdivisions of OGLE data reveals three epochs during which short periodicities of $\sim$1 day are significantly detected which we suggest are non-radial pulsations (NRPs) of the companion star. These seasons immediately precede those exhibiting clear outburst behaviour, supporting the suggested association between the NRPs, decretion disk growth and the onset of Type I outbursts.
In this paper, we prove the conjecture that if there is an odd perfect number, then there are infinitely many of them.