Miracle-dz/UniFAR-FTUs huggingface dataset:
A variational principle for Kaluza-Klein type theories

For any positive integer n and any Lie group G, given a definite symmetric bilinear form on R n and an Ad-invariant scalar product on the Lie algebra of G, we construct a variational problem on fields defined on an arbitrary (n + dimG)-dimensional manifold Y. We show that, if G is compact and simply connected, any global solution of the Euler-Lagrange equations leads to identify Y with the total space of a principal bundle over an n-dimensional manifold X. Moreover X is automatically endowed with a (pseudo-)Riemannian metric and a connection which are solutions of the Einstein-Yang-Mills system equation with a cosmological constant.
Optical identification of X-ray source 1RXS J180431.1-273932 as a magnetic cataclysmic variable

The X-ray source 1RXS J180431.1−273932 has been proposed as a new member of the symbiotic X-ray binary (SyXB) class of systems, which are composed of a late-type giant that loses matter to an extremely compact object, most likely a neutron star. In this paper, we present an optical campaign of imaging plus spectroscopy on selected candidate counterparts of this object. We also reanalyzed the available archival X-ray data collected with XMM-Newton. We find that the brightest optical source inside the 90% X-ray positional error circle is spectroscopically identified as a magnetic cataclysmic variable (CV), most likely of intermediate polar type, through the detection of prominent Balmer, Hei ,H eii, and Bowen blend emissions. On either spectroscopic or statistical grounds, we discard as counterparts of the X-ray source the other optical objects in the XMM-Newton error circle. A red giant star of spectral type M5 III is found lying just outside the X-ray position: we consider this latter object as a fore-/background one and likewise rule it out as a counterpart of 1RXS J180431.1−273932. The description of the X-ray spectrum of the source using a bremsstrahlung plus black-body model gives temperatures of kTbr ∼ 40 keV and kTbb ∼ 0.1 keV for these two components. We estimate a distance of d ∼ 450 pc and a 0.2−10 keV X-ray luminosity of LX ∼ 1.7 × 10 32 erg s −1 for this system and, using the information obtained from the X
Design, synthesis and anti-diabetic activity of piperazine sulphonamide derivatives as dipeptidyl peptidase-4 inhibitors

Type II diabetes (T2DM) is considered one of the most prevalent metabolic disorders in the world. It is known as insulin resistance and persistent hyperglycemia. Over the past decade, inhibition of the enzymatic dipeptidyl peptidase-4 (DPP-4) has indeed been demonstrated to be an efficient and safe intervention for type 2 diabetes. In order to develop innovative DPP-4 inhibitors, several in silico techniques including 3D-QSAR, molecular docking, in-silico toxicity has been performed to confirm a total of 18 novel piper-azine and pyridine derivatives to be synthesized from many designed molecules. These molecules have indeed been docked onto the protein surface of the DPP-4 enzyme, and ADMET characteristics have also been generated in silico . The compounds were then developed and analysed using FT-IR. Then, these compounds were investigated for DPP-4 inhibition in vitro . The most promising compound 8h showed 27.32% inhibition at 10μmol L -1 concentration over DPP-4 so selected for further in-vivo anti-diabetic evaluation. Compound 8h decreased blood glucose excursion in a dose-dependent manner during the OGTT and STZ-induced glucose models in normal Albino Wistar rats. Low-dose streptozotocin-induced type 2 diabetes in Albino Wistar rats treated chronically for 21 days with compound 8h resulted in a reduction in serum glucose levels. This highlighted that 8h is a moderately strong and specific block-buster molecule that can be structurally modified to boost its effectiveness and overall pharmacological profile as a DPP-4 inhibitor.
Interpretation of the cosmological metric

The cosmological Robertson–Walker metric of general relativity is often said to have the consequences that (1) the recessional velocity v of a galaxy at proper distance l obeys the Hubble law v=Hl, and therefore galaxies at sufficiently great distance l are receding faster than the speed of light c; (2) faster than light recession does not violate special relativity theory because the latter is not applicable to the cosmological problem, and because “space itself is receding” faster than c at great distance, and it is velocity relative to local space that is limited by c, not the velocity of distant objects relative to nearby ones; (3) we can see galaxies receding faster than the speed of light; and (4) the cosmological redshift is not a Doppler shift, but is due to a stretching of photon wavelength during propagation in an expanding universe. We present a particular Robertson–Walker metric (an empty universe metric) for which a coordinate transformation shows that none of these interpretation necessarily.
Narrowband Passive RF Tags for Frequency-Selective Harmonic Doppler Radar Tracking

A design for frequency-selective radio frequency (RF) harmonic tags for harmonic Doppler radar tracking is presented. Harmonic RF tags receive an incident microwave signal and generate a retransmitted signal at a harmonic of the incident frequency, typically the second harmonic. Since environmental backscatter occurs at the fundamental frequency, the second harmonic can be easier to detect. Typical harmonic tags operate over a reasonably wide fractional bandwidth, and thus to detect multiple tags within the same field of view, additional circuitry must generally be added to the tag to differentiate the responses. We propose a different approach based on frequency selectivity implemented by the tag antenna. Based on narrowband split-ring printed antennas, the tags accept incident signals over a specified narrow fractional bandwidth, after which the second harmonic is generated by a diode and retransmitted with a standard dipole antenna. The narrowband filtering occurs at the fundamental frequency antenna, and thus with tags designed at adjacent narrowband frequency channels, no additional circuitry is necessary to differentiate multiple tags. Fabricated tags achieved fractional bandwidths below 0.5% at carrier frequencies below 2.5 GHz while maintaining gains above 2 dBi. The construction of the tag is simple and low-cost, requiring only a single component (a diode) on a printed antenna structure. We demonstrate the feasibility of simultaneously measuring the time-varying harmonic Doppler signature of multiple tags in the field of view by experimentally verifying the frequency selectivity of tags in motion using a 2.4/4.8 GHz harmonic Doppler radar.
VARIABILITY IN PROTO-PLANETARY NEBULAE. IV. LIGHT CURVE ANALYSIS OF FOUR OXYGEN-RICH, F SPECTRAL TYPE OBJECTS

We present new light curves covering 14–19 years of observations of four bright proto-planetary nebulae (PPNs), all oxygen-rich and of F spectral type. They each display cyclical light curves with significant variations in amplitude. All four were previously known to vary in light. Our data were combined with published data and searched for periodicity. The results are as follows: IRAS 19475+3119 (HD 331319; 41.0 days), 17436+5003 (HD 161796; 45.2 days), 19386+0155 (101.8 days), and 18095+2704 (113.3 days). The two longer periods are in agreement with previous studies while the two shorter periods each reveal for the first time a dominant period over these long observing intervals. Multiple periods were also found for each object. The secondary periods were all close to the dominant periods, with P2/P1 ranging from 0.86 to 1.06. The variations in color reveal maximum variations in Teff of 400–770 K. These variations are due to pulsations in these post-asymptotic giant branch objects. Maximum seasonal light variations are all less than 0.23 mag (V), consistent for their temperatures and periods with the results of Hrivnak et al. for 12 C-rich PPNs. For all of these PPNs, there is an inverse relationship between period and temperature; however, there is a suggestion that the period–temperature relationship may be somewhat steeper for the O-rich than for the C-rich PPNs.
Dark Forces and Light Dark Matter

We consider a simple class of models in which the dark matter, X, is coupled to a new gauge boson, phi, with a relatively low mass (m_phi \sim 100 MeV-3 GeV). Neither the dark matter nor the new gauge boson have tree-level couplings to the Standard Model. The dark matter in this model annihilates to phi pairs, and for a coupling of g_X \sim 0.06 (m_X/10 GeV)^1/2 yields a thermal relic abundance consistent with the cosmological density of dark matter. The phi's produced in such annihilations decay through a small degree of kinetic mixing with the photon to combinations of Standard Model leptons and mesons. For dark matter with a mass of \sim10 GeV, the shape of the resulting gamma-ray spectrum provides a good fit to that observed from the Galactic Center, and can also provide the very hard electron spectrum required to account for the observed synchrotron emission from the Milky Way's radio filaments. For kinetic mixing near the level naively expected from loop-suppressed operators (epsilon \sim 10^{-4}), the dark matter is predicted to scatter elastically with protons with a cross section consistent with that required to accommodate the signals reported by DAMA/LIBRA, CoGeNT and CRESST-II.
Predicting galaxy star formation rates via the co-evolution of galaxies and haloes

In this paper, we test the age matching hypothesis that the star formation rate (SFR) of a galaxy is determined by its dark matter halo formation history, and as such, that more quiescent galaxies reside in older halos. This simple model has been remarkably successful at predicting color-based galaxy statistics at low redshift as measured in the Sloan Digital Sky Survey (SDSS). To further test this method with observations, we present new SDSS measurements of the galaxy two-point correlation function and galaxy-galaxy lensing as a function of stellar mass and SFR, separated into quenched and star forming galaxy samples. We find that our age matching model is in excellent agreement with these new measurements. We also employ a galaxy group finder and show that our model is able to predict: (1) the relative SFRs of central and satellite galaxies, (2) the SFR-dependence of the radial distribution of satellite galaxy populations within galaxy groups, rich groups, and clusters and their surrounding larger scale environments, and (3) the interesting feature that the satellite quenched fraction as a function of projected radial distance from the central galaxy exhibits an approx r-. 15 slope, independent of environment. The accurate prediction for the spatial distribution ofmore » satellites is intriguing given the fact that we do not explicitly model satellite-specific processes after infall, and that in our model the virial radius does not mark a special transition region in the evolution of a satellite, contrary to most galaxy evolution models. The success of the model suggests that present-day galaxy SFR is strongly correlated with halo mass assembly history. « less
Precision cosmology with Padé rational approximations: Theoretical predictions versus observational limits

We propose a novel approach for parameterizing the luminosity distance, based on the use of rational "Pad\'e" approximations. This new technique extends standard Taylor treatments, overcoming possible convergence issues at high redshifts plaguing standard cosmography. Indeed, we show that Pad\'e expansions enable us to confidently use data over a larger interval with respect to the usual Taylor series. To show this property in detail, we propose several Pad\'e expansions and we compare these approximations with cosmic data, thus obtaining cosmographic bounds from the observable universe for all cases. In particular, we fit Pad\'e luminosity distances with observational data from different uncorrelated surveys. We employ union 2.1 supernova data, baryonic acoustic oscillation, Hubble space telescope measurements and differential age data. In so doing, we also demonstrate that the use of Pad\'e approximants can improve the analyses carried out by introducing cosmographic auxiliary variables, i.e. a standard technique usually employed in cosmography in order to overcome the divergence problem. Moreover, for any drawback related to standard cosmography, we emphasize possible resolutions in the framework of Pad\'e approximants. In particular, we investigate how to reduce systematics, how to overcome the degeneracy between cosmological coefficients, how to treat divergences and so forth. As a result, we show that cosmic bounds are actually refined through the use of Pad\'e treatments and the thus derived best values of the cosmographic parameters show slight departures from the standard cosmological paradigm. Although all our results are perfectly consistent with the $\Lambda$CDM model, evolving dark energy components different from a pure cosmological constant are not definitively ruled out.
Pure quantum dephasing of a solid-state electron spin qubit in a large nuclear spin bath coupled by long-range hyperfine-mediated interactions

We investigate decoherence due to pure dephasing of a localized spin qubit interacting with a nuclear spin bath. Although in the limit of a very large magnetic field the only decoherence mechanism is spectral diffusion due to dipolar flip-flops of nuclear spins, with decreasing field the hyperfine-mediated interactions between the nuclear spins become important. We take advantage of their long-range nature and resum the leading terms in an $1/N$ expansion of the decoherence time-evolution function ($N$, being the number of nuclear spins interacting appreciably with the electron spin, is large). For the case of the thermal uncorrelated bath we show that our theory is applicable down to low magnetic fields ($\ensuremath{\sim}10\text{ }\text{mT}$ for a large dot with $N={10}^{6}$) allowing for comparison with recent experiments in GaAs quantum dot spin qubits. Within this approach we calculate the free induction decay and spin echo decoherence in GaAs and InGaAs as a function of the number of the nuclei in the bath (i.e., the quantum dot size) and the magnetic field. Our theory for free induction decay in a narrowed nuclear bath is shown to agree with the exact solution for decoherence due to hyperfine-mediated interaction which can be obtained when all the nuclei-electron coupling constants are identical. For the spin echo evolution we show that the dominant decoherence process at low fields is due to interactions between nuclei having significantly different Zeeman energies (i.e., nuclei of As and two isotopes of Ga in GaAs), and we compare our results with recent measurements of spin echo signal of a single spin confined in a GaAs quantum dot. For the same set of parameters we perform calculations of decoherence under various dynamical decoupling pulse sequences and predict the effect of these sequences in low-$B$ regime in GaAs.
Managing ideational complexity in public policies: the case of public research funding

Abstract This article examines how ideational complexity, i.e. the lasting presence of alternative policy frames in a policy domain, can be managed without leading to overt conflicts. By leveraging insights from the organisational literature, we suggest that, in most cases, alternative frames are kept apart within distinct policy instruments, while hybrid instruments are established only when required by the nature of the problem. We provide illustrative examples of how these strategies are employed in the case of public grant schemes for research funding. Our findings suggest that a) composite instrument mixes are an important resource to deal with ideational complexity, and b) the design of the instruments’ delivery package, and specifically its procedural and organisational dimensions, plays a central role in avoiding conflicts between policy frames. Accordingly, our analysis advances the unexplored issue of how the coexistence of alternative policy frames impacts policy implementation.
VARIABILITAS KONSENTRASI KLOROFIL-a DI PERAIRAN KALIMANTAN BARAT MENGGUNAKAN DATA MODIS AQUA

Chlorophyll-a is one of the important parameters in determining the amount of primary productivity in a waters. The purpose of this study was to examine the variability of chlorophyll-a in the waters of West Kalimantan. The data used is monthly and annual level 3 data for 5 years from 2016 – 2020 taken from the Aqua MODIS (Moderate-Resolution Imaging Spectroradiometer) satellite. The distribution of chlorophyll-a in the waters of West Kalimantan shows that the highest concentration value is found in coastal areas and the lowest in offshore waters. Meanwhile, the monthly distribution of chlorophyll-a showed that the highest concentration of chlorophyll-a was in August at 28.93 mg/m3 and the lowest was in December at 19.42 mg/m3.
The K-theory of the compact quantum group SUq(2) for q = -1

We determine the K-theory of the C*-algebra C(SU-1(2)), describe its spectrum, and compute its Haar state. As an application, we use Blanchard's technique in order to prove the existence of a continuous C*-bundle over [-1, 0) whose fiber at q is isomorphic to C(SUq(2)).
Singularity structure of the pi N scattering amplitude in a meson-exchange model up to energies W < 2.0 GeV

Within the previously developed Dubna-Mainz-Taipei meson-exchange model, the singularity structure of the {pi}N scattering amplitudes has been investigated. For all partial waves up to F waves and c.m. energies up to W{approx}2 GeV, the T-matrix poles have been calculated by three different techniques: analytic continuation into the complex energy plane and speed-plot and regularization method. For all four-star resonances except the S{sub 11}(1535), we find very good agreement between the analytic continuation and the regularization method. We also find resonance poles for resonances that are not so well established, but in these cases the pole positions and residues obtained by analytic continuation can substantially differ from the results predicted by the speed-plot and regularization methods.
Perspective: Ultrafast magnetism and THz spintronics

This year the discovery of femtosecond demagnetization by laser pulses is 20 years old. For the first time this milestone work by Bigot and coworkers gave insight in a very direct way into the time scales of microscopic interactions that connect the spin and electron system. While intense discussions in the field were fueled by the complexity of the processes in the past, it now became evident that it is a puzzle of many different parts. Rather than giving an overview that has been presented in previous reviews on ultrafast processes in ferromagnets, this perspective will show that with our current depth of knowledge the first real applications are on their way: THz spintronics and all-optical spin manipulation are becoming more and more feasible. The aim of this perspective is to point out where we can connect the different puzzle pieces of understanding gathered over 20 years to develop novel applications. based on many observations in a large number of experiments. Differences in the theoretical models arise from the localized and delocalized nature of ferromagnetism. Transport effects are intrinsically non-local in spintronic devices and at interfaces. We review the need for multiscale modeling to address processes starting from electronic excitation of the spin system on the picometer length scale and sub-femtosecond time scale, to spin wave generation, and towards the modeling of ultrafast phase transitions that altogether determine the response time of the ferromagnetic system. Today, our current understanding gives rise to the first real applications of ultrafast spin physics for ultrafast magnetism control: THz spintronic devices. This makes the field of ultrafast spin-dynamics an emerging topic open for many researchers right now.
Unitary evolution, canonical variables and vacuum choice for general quadratic Hamiltonians in spatially homogeneous and isotropic space-times

Quantization of arbitrary free scalar fields in spatially homogeneous and isotropic space-times is considered. The quantum representation allowing a unitary evolution for the fields is taken as a requirement for the theory. Studying the group of linear canonical transformations, we show the relations between unitary evolution and choice of canonical variables. From these relations we obtain the conditions on the Hamiltonian such that there are canonical variables for which the field has unitary evolution. We then compute the linear transformation leading to these variables, also proving that they are unique. We obtain these results by developing the asymptotic analysis of the fields using the action angle variables, which proves to be a generalization of the usual Wentzel-Kramers-Brillouin approximation. These tools allow us to re-frame the adiabatic vacuum condition in a extensible format by using the action angle variables to relate these vacuum choices to those where the particle number density does not depend on angle (fast) variables. Finally, we develop a larger set of canonical variables relating the adiabatic vacuum conditions with the smearing of the quantum fields. This set of canonical variables also connects the adiabatic vacuum conditions with the instantaneous Hamiltonian diagonalization vacuum choice.
Enhancement of coherent dipole coupling between two atoms via squeezing a cavity mode

We propose a theoretical method to enhance the coherent dipole coupling between two atoms in an optical cavity via parametrically squeezing the cavity mode. In the present scheme, conditions for coherent coupling are derived in detail and diverse dynamics of the system can be obtained by regulating system parameters. In the presence of environmental noise, an auxiliary squeezed field is employed to suppress, and even completely eliminate the additional noise induced by squeezing. In addition, we demonstrate that our scheme enables the effective suppression of atomic spontaneous emission. The results in our investigation could be used for diverse applications in quantum technologies.
Wavelet based Faraday Rotation Measure Synthesis

The Faraday rotation measure synthesis, as a method for analysing multichannel observations of polarized radio emission to investigate galactic magnetic field structures requires the definition of complex polarized intensity in the wavelength range −∞ <λ 2 < ∞. The problem is that the measurements at negative λ 2 are not possible. We introduce a simple method for continuation of the observed complex polarized intensity P (λ 2 ) into the domain λ 2 < 0u sing symmetry arguments. The method is suggested in context of magnetic field recognition in galactic discs where the magnetic field is supposed to have a maximum in the equatorial plane. The method is quite simple when applied to a single Faraday rotating structure on the line of sight. Recognition of several structures on the same line of sight requires a more sophisticated technique. We also introduce a wavelet-based algorithm which allows us to consider a set of isolated structures in the (φ, λ 2 ) plane (where φ is the Faraday depth). The method essentially improves the possibilities for reconstruction of complicated Faraday structures using the capabilities of modern radio telescopes.