Miracle-dz/UniFAR-FTUs huggingface dataset:
III-Posed problems early vision: from computational theory to analogue networks

We outline a theoretical framework that leads from the computational nature of early vision to algorithms for solving them and finally to a specific class of analogue and parallel hardware for the efficient solution of these algorithms. The common computational structure of many early vision problems is that they are mathematically ill-posed in the sense of Hadamard. Regularization analysis can be used to solve them in terms of variational principles of a specific type that enforce constraints derived from a physical analysis of the problem. Studies of human perception may reveal whether principles of a similar type are exploited by biological vision. We also show that the corresponding variational principles can be implemented in a natural way by analogue networks. Specific electrical and chemical networks for localizing edges and computing visual motion are derived. We suggest that local circuits of neurons may exploit this unconventional model of computation.
Models for the Type Ic Hypernova SN 2003lw associated with GRB 031203

The gamma-ray burst GRB 031203 at a redshift z = 0.1055 revealed a highly reddened Type Ic supernova, SN 2003lw, in its afterglow light. This is the third well-established case of a link between a long-duration GRB and a Type Ic SN. The SN light curve is obtained by subtracting the galaxy contribution and is modeled together with two spectra at near-maximum epochs. A red VLT grism 150I spectrum of the SN near peak is used to extend the spectral coverage, and in particular to constrain the uncertain reddening, the most likely value for which is EG+H(B - V) ≃ 1.07 ± 0.05. Accounting for reddening, SN 2003lw is ~0.3 mag brighter than the prototypical GRB-SN 1998bw. Light curve models yield a 56Ni mass of ~0.55 M☉. The optimal explosion model is somewhat more massive (Mej ~ 13 M☉) and more energetic (E ~ 6 × 1052 ergs) than the model for SN 1998bw, implying a massive progenitor (40-50 M☉). The mass at high velocity is not very large (1.4 M☉ above 30,000 km s-1, but only 0.1 M☉ above 60,000 km s-1), but it is sufficient to cause the observed broad lines. The similarity of SNe 2003lw and 1998bw and the weakness of their related GRBs, GRB 031203 and GRB 980425, suggest that both GRBs may be normal events viewed slightly off-axis or a weaker but possibly more frequent type of GRB.
Multiple Imputation for Interval Estimation from Simple Random Samples with Ignorable Nonresponse

Abstract Several multiple imputation techniques are described for simple random samples with ignorable nonresponse on a scalar outcome variable. The methods are compared using both analytic and Monte Carlo results concerning coverages of the resulting intervals for the population mean. Using m = 2 imputations per missing value gives accurate coverages in common cases and is clearly superior to single imputation (m = 1) in all cases. The performances of the methods for various m can be predicted well by linear interpolation in 1/(m — 1) between the results for m = 2 and m = ∞. As a rough guide, to assure coverages of interval estimates within 2% of the nominal level when using the preferred methods, the number of imputations per missing value should increase from 2 to 3 as the nonresponse rate increases from 10% to 60%.
Zn migration during spark plasma sintering of thermoelectric Zn4Sb3

The phase homogeneity of spark plasma sintered thermoelectric Zn4Sb3 pellets along the pressing direction has been studied by potential Seebeck microprobe scanning and spatially resolved x-ray diffraction. Significant variations in the Seebeck coefficient reflect presence of different crystalline phases. The emergence of the ZnSb phase at the bottom of the pellet and metallic Zn impurity at the top explains the variation in the Seebeck coefficients. Quantitative phase distributions along the pressing axis were determined from the Rietveld refinements of spatially resolved x-ray diffraction patterns. These reveal a migration of highly mobilized Zn atoms under the direct current applied during spark plasma sintering.
Monogamy inequalities for entanglement using continuous variable measurements

We consider three modes $A$, $B$ and $C$ and derive continuous variable monogamy inequalities that constrain the distribution of bipartite entanglement amongst the three modes. The inequalities hold for all such tripartite states, without the assumption of Gaussian states, and are based on measurements of two conjugate quadrature phase amplitudes $X_{i}$ and $P_{i}$ at each mode $i=A,B$. The first monogamy inequality is $D_{BA}+D_{BC}\geq1$ where $D_{BA}<1$ is the widely used symmetric entanglement criterion, for which $D_{BA}$ is the sum of the variances of $(X_{A}-X_{B})/2$ and $(P_{A}+P_{B})/2$. A second monogamy inequality is $Ent_{BA}Ent_{BC}\geq\frac{1}{\left(1+(g_{BA}^{(sym)})^{2}\right)\left(1+(g_{BC}^{(sym)})^{2}\right)}$ where $Ent_{BA}<1$ is the EPR variance product criterion for entanglement. Here $Ent_{BA}$ is a normalised product of variances of $X_{B}-g_{BA}^{(sym)}X_{A}$ and $P_{B}+g_{BA}^{(sym)}P_{A}$, and $g_{BA}^{(sym)}$ is a parameter that gives a measure of the symmetry between the moments of $A$ and $B$. We also show that the monogamy bounds are increased if a standard steering criterion for the steering of $B$ is not satisfied. We illustrate the monogamy for continuous variable tripartite entangled states including the effects of losses and noise, and identify regimes of saturation of the inequalities. The monogamy relations explain the experimentally observed saturation at $D_{AB}=0.5$ for the entanglement between $A$ and $B$ when both modes have 50\% losses, and may be useful to establish rigorous bounds of correlation for the purpose of quantum key distribution protocols.
Focusing and spectral enhancement of a repetition-rated, laser-driven, divergent multi-MeV proton beam using permanent quadrupole magnets

A pair of conventional permanent magnet quadrupoles is used to focus a 2.4 MeV laser-driven proton beam at a 1 Hz repetition rate. The magnetic field strengths are 55 and 60 T/m for the first and second quadrupoles, respectively. The proton beam is focused to a spot with a size of less than ∼3×8 mm2 at a distance of 650 mm from the source. This result is in good agreement with the Monte Carlo particle trajectory simulation.
Gain in quantum cascade lasers and superlattices: A quantum transport theory

Gain in current-driven semiconductor heterostructure devices is calculated within the theory of nonequilibrium Green functions. In order to treat the nonequilibrium distribution self-consistently the full two-time structure of the theory is employed without relying on any sort of Kadanoff-Baym ansatz. The results are independent of the choice of the electromagnetic field if the variation of the self-energy is taken into account. Excellent quantitative agreement is obtained with the experimental gain spectrum of a quantum cascade laser. Calculations for semiconductor superlattices show that the simple two-time miniband transport model gives reliable results for large miniband widths at room temperature.
A test of galaxy evolutionary models via angular sizes

The relationship between angular size, magnitude, and redshift of faint galaxies is explored as a potential tool to distinguish between galaxy evolutionary models. Different models, based on merging, mild luminosity evolution, and no evolution, lead to different predictions of the angular size distribution, redshift- size relation, and magnitude-size relation. The merging model predicts significantly smaller sizes for faint galaxies than the standard model, because of the requirement for more intrinsically small faint objects at high redshift. A dwarf-rich no-evolution model also predicts small sizes for faint galaxies. The mild luminosity evolution model predicts more luminous galaxies of large angular size at high redshift, as does a standard no-evolution model. Prefurbishment Hubble Space Telescope (HST) Medium Deep Survey observations of magnitudes and sizes of faint galaxies indicate an excess of small versus large faint galaxies, favoring the dwarf rich, no evolution model with respect to the merging model; the other two models are more discrepant with the data. While these results cannot yet rule out with certainty any of the proposed models, they demonstrate the potential of angular size to discriminate between models of galaxy evolution, especially with the high-resolution HST wide field/planetary camera-2 (WFPC2) data.
SOLPS analysis of the MAST-U divertor with the effect of heating power and pumping on the access to detachment in the Super-x configuration

SOLPS simulations of MAST-U have been carried out to identify in more detail the physics and operational properties of novel divertor configurations such as Super-x divertor (SXD), in particular the physics of detachment. A well diagnosed L-mode discharge from MAST has been utilised to determine L-mode transport coefficients representative for MAST-U L-mode plasmas. Simulations show that under the same core plasma conditions, the MAST-U SXD is strongly detached whilst the conventional divertor (CD) is not (1 eV versus 20 eV at the divertor plate). The detachment and higher power losses (1.6×) in the SXD versus the attached CD lead to a factor of 25 reduction in the target power load and are attributed to changes in radial location of the target. An attached regime can be established for the SXD in L-mode for higher pumping speed and/or heating power. In contrast, the simulation predicts that the MAST-U CD requires 3× higher density or 4× reduced power than the SXD to detach. Comparing two versions of the SXD, each with a different amount of poloidal expansion in the region near the divertor plate, we find that the effect of additional poloidal flux expansion of the SXD on an already detached plasma is small for a change in flux expansion in volume by a factor of 2–3 (target temperature 0.7 eV versus 1.1 eV). The poloidal flux expansion re-arranges the radiation pattern with only a small increase in divertor power losses (1.06×) compared to changing from the CD to SXD topology. By artifically increasing the leakage from the divertor chamber, we confirmed that the tight closure of the divertor region leads to strong increases in neutral density with concomitant power losses.
A quasar hiding behind two dusty absorbers

The cosmic chemical enrichment as measured from damped Lyα absorbers (DLAs) will be underestimated if dusty and metal-rich absorbers have evaded identification. Here we report the discovery and present the spectroscopic observations of a quasar, KV-RQ 1500–0031, at z = 2.520 reddened by a likely dusty DLA at z = 2.428 and a strong Mg II absorber at z = 1.603. This quasar was identified as part of the KiDS-VIKING Red Quasar (KV-RQ) survey, specifically aimed at targeting dusty absorbers which may cause the background quasars to escape the optical selection of e.g. the Sloan Digital Sky Survey (SDSS) quasar sample. For the DLA we find an H I column density of logN(H I) = 21.2 ± 0.1 and a metallicity of [X/H] = − 0.90 ± 0.20 derived from an empirical relation based on the equivalent width of Si IIλ 1526. We observe a total visual extinction of AV = 0.16 mag induced by both absorbers. To put this case into context we compile a sample of 17 additional dusty (AV > 0.1 mag) DLAs toward quasars (QSO-DLAs) from the literature for which we characterize the overall properties, specifically in terms of H I column density, metallicity and dust properties. From this sample we also estimate a correction factor to the overall DLA metallicity budget as a function of the fractional contribution of dusty QSO-DLAs to the bulk of the known QSO-DLA population. We demonstrate that the dusty QSO-DLAs have high metal column densities (logN(H I) + [X/H]) and are more similar to gamma-ray burst (GRB)-selected DLAs (GRB-DLAs) than regular QSO-DLAs. We evaluate the effect of dust reddening in DLAs as well as illustrate how the induced color excess of the underlying quasars can be significant (up to ~1 mag in various optical bands), even for low to moderate extinction values (AV ≲ 0.6 mag). Finally we discuss the direct and indirect implications of a significant dust bias in both QSO- and GRB-DLA samples.
Update of membership and mean proper motion of open clusters from UCAC5 catalogue

We present mean proper motions and membership probabilities of individual stars for optically visible open clusters, which have been determined using data from the UCAC5 catalog. This follows our previous studies with the UCAC2 and UCAC4 catalogs, but now using improved proper motions in the GAIA reference frame. In the present study results were obtained for a sample of 1108 open clusters. For five clusters, this is the first determination of mean proper motion, and for the whole sample, we present results with a much larger number of identified astrometric member stars than on previous studies. It is the last update of our Open cluster Catalog based on proper motion data only. Future updates will count on astrometric, photometric and spectroscopic GAIA data as input for analyses.
Issues, concepts, and challenges in spintronics

We review form a theoretical perspective the emerging field of spintronics, where active control of spin transport and dynamics in electronic materials may provide novel device application possibilities. In particular, we discuss the quantum mechanical principles underlying spintronics applications, emphasizing the formidable challenges involving spin decoherence and spin injection facing any eventual device fabrication. We provide a critical assessment of the current status of the field with special attention to possible device applications.
FINITE-RANGE GRAVITY AND ITS ROLE IN GRAVITATIONAL WAVES, BLACK HOLES AND COSMOLOGY

Theoretical considerations of fundamental physics, as well as certain cosmological observations, persistently point out to permissibility, and maybe necessity, of macroscopic modifications of the Einstein general relativity. The field theoretical formulation of general relativity helped us to identify the phenomenological seeds of such modifications. They take place in the form of very specific mass terms, which appear in addition to the field theoretical analog of the usual Hilbert–Einstein Lagrangian. We derive and study exact nonlinear equations of the theory, along with its linear approximation. We interpret the added terms as masses of spin-2 and spin-0 gravitons. The arising finite-range gravity is a fully consistent theory, which smoothly approaches general relativity in the massless limit, that is, when both masses tend to zero and the range of gravity tends to infinity. We show that all local weak-field predictions of the theory are in perfect agreement with the available experimental data. However, some other conclusions of the nonlinear massive theory are in a striking contrast with those of general relativity. We show in detail how the arbitrarily small mass terms eliminate the black hole event horizon and replace a permanent power-law expansion of a homogeneous isotropic universe with an oscillatory behaviour. One variant of the theory allows the cosmological scale factor to exhibit an 'accelerated expansion' instead of slowing down to a regular maximum of expansion. We show in detail why the traditional, Fierz–Pauli, massive gravity is in conflict not only with the static-field experiments, but also with the available indirect gravitational-wave observations. At the same time, we demonstrate the incorrectness of the widely held belief that the non-Fierz–Pauli theories possess "negative energies" and "instabilities. "
Impurity scattering in unconventional density waves: non-crossing approximation for arbitrary scattering rate

We present a detailed theoretical study on the thermodynamic properties of impure quasi-one-dimensional unconventional charge and spin density waves in the framework of mean-field theory. The impurities are of the ordinary non-magnetic type. Making use of the full self-energy that takes into account all ladder- and rainbow-type diagrams, we are able to calculate the relevant low temperature quantities for arbitrary scattering rates. These are the density of states, specific heat and the shift in the chemical potential. Our results therefore cover the whole parameter space: they include both the self-consistent Born and the resonant unitary limits, and most importantly give exact results in between.
From kpcs to the central parsec of NGC 1097: feeding star formation and a black hole at the same time

A panchromatic view of the star forming ring and feeding process in the central kpc of the galaxy NGC 1097 is presented. The assembled IR to UV images at ∼10 pc resolution allow us to characterise the population of circa 250 clusters in the ring and disentangle the network of filaments of dust and gas that enshroud and feed them. The ring is a place of intermittent star bursts over the last 100 Myr. Four major episodes covering a proto-cluster phase of eleven mid-IR sources at the molecular clouds core, and two (three) previous bursts with a time separation of 20-30 Myr are identified. The extinction map of the inner few kpc resolves NGC1097's two major dust lanes in bundles of narrow, <25 pc width, filaments running along the galaxy's bar. As they approach the ring, some circularise along it, others curve to the centre to produce a nuclear spiral. We believe these are kpc-scale dust-gas streamers feeding the ring and the black-hole. The total mass in clusters formed in the ring in the last 100 Myr is < 10 7 M , i.e. < 1% of the 10 9 M of molecular gas in the ring; yet, at its current star formation rate, ∼ 1.8 M yr −1 , an order of magnitude more in stellar mass should have been produced over that period. This means that the availability of gas in the ring is not the sole star formation driver, perhaps the rate at which dense gas accumulates in the ring is key.
Full-Polarization Observations of OH Masers in Massive Star-forming Regions. I. Data

We present full-polarization VLBA maps of the ground-state, main-line, 2Π3/2, J = 3/2 OH masers in 18 Galactic massive star-forming regions. This is the first large polarization survey of interstellar hydroxyl masers at VLBI resolution. A total of 184 Zeeman pairs are identified, and the corresponding magnetic field strengths are indicated. We also present spectra of the NH3 emission or absorption in these star-forming regions. Analysis of these data will be presented in a companion paper.
Electromagnetic lattice gauge invariance in two-dimensional discrete-time quantum walks

Gauge invariance is one of the more important concepts in physics. We discuss this concept in connection with the unitary evolution of discrete-time quantum walks in one and two spatial dimensions, when they include the interaction with synthetic, external electromagnetic fields. One introduces this interaction as additional phases that play the role of gauge fields. Here, we present a way to incorporate those phases, which differs from previous works. Our proposal allows the discrete derivatives, that appear under a gauge transformation, to treat time and space on the same footing, in a way which is similar to standard lattice gauge theories. By considering two steps of the evolution, we define a density current which is gauge invariant and conserved. In the continuum limit, the dynamics of the particle, under a suitable choice of the parameters, becomes the Dirac equation and the conserved current satisfies the corresponding conservation equation.
Spontaneous parity violation

We disprove the Vafa-Witten theorem on the impossibility of spontaneously breaking parity in vectorlike gauge field theories, identifying a mechanism driven by quantum fluctuations. With the introduction of a meromorphic lattice formulation, defined over 5 dimensions, we demonstrate that the minima of the free energy can be distinct from the maxima of the partition function. By identifying and evaluating a suitable contour for the partition function the asymptotic behavior of the complex action is shown to be nonoscillatory.
On the stability of nonisothermal Bonnor-Ebert spheres. III. The role of chemistry in core stabilization

Aims. We investigate the effect of chemistry on the stability of starless cores against gravitational collapse.Methods. We combined chemical and radiative transfer simulations in the context of a modified Bonnor-Ebert sphere to model the effect of chemistry on the gas temperature, and study the effect of temperature changes on core stability.Results. We find that chemistry has in general very little effect on the nondimensional radius ξ out , which parametrizes the core stability. Cores that are initially stable or unstable tend to stay near their initial states, in terms of stability (i.e., ξ out ~ const.), as the chemistry develops. This result is independent of the initial conditions. We can however find solutions where ξ out decreases at late times (t ≳ 106 yr), which correspond to increased stabilization caused by the chemistry. Even though the core stability is unchanged by the chemistry in most of the models considered here, we cannot rule out the possibility that a core can evolve from an unstable to a stable state owing to chemical evolution. The reverse case, where an initially stable core becomes ultimately unstable, seems highly unlikely. Conclusions. Our results indicate that chemistry should be properly accounted for in studies of star-forming regions, and that further investigations of core stability especially with hydrodynamical models are warranted.
Narrowband Survey of the GOODS Fields: Search for Lyα Emitters at z = 5.7

We present results from optical narrowband (λc = 8150 Å and Δλ = 120 Å) observations of the Great Observatories Origins Deep Survey (GOODS) fields, using Suprime-Cam on the Subaru Telescope. Using these narrowband data, we then perform a survey of Lyα emitters (LAEs) at z ~ 5.7. The LAE survey covers an area of ≈320 arcmin2 and a comoving volume of ≃8.0 × 104 Mpc3. We found a total of 10 (GOODS-N) and 4 (GOODS-S) LAE candidates at z ~ 5.7. We perform a study of the spatial distribution, space density, and star formation properties of the LAEs at z ~ 5.7.
Evolving Newton's constant, extended gravity theories, and Snia data analysis

Department of Physics, University of Ioannina, Greece(Dated: February 3, 2008)If Newton’s constant G evolves on cosmological timescales as predicted by extended gravity theo-ries then Type Ia supernovae (SnIa) can not be treated as standard candles. The magnitude-redshiftdatasets however can still be useful. They can be used to simultaneously ﬁt for both H(z) and G(z)(so that local G(z) constraints are also satisﬁed) in the context of appropriate parameterizations.Here we demonstrate how can this analysis be done by applying it to the Gold SnIa dataset. Wecompare the derived eﬀective equation of state parameter w(z) at best ﬁt with the correspondingresult obtained by neglecting the evolution G(z). We show that even though the results clearlydiﬀer from each other, in both cases the best ﬁt w(z) crosses the phantom divide w = −1. We thenattempt to reconstruct a scalar tensor theory that predicts the derived best ﬁt forms of H(z) andG(z). Since the best ﬁt G(z) ﬁxes the scalar tensor potential evolution F(z), there is no ambiguityin the reconstruction and the potential U(z) can be derived uniquely. The particular reconstructedscalar tensor theory however, involves a change of sign of the kinetic term Φ