A Lattice Boltzmann Method for relativistic rarefied flows in (2+1) dimensions

We propose an extension to recently developed Relativistic Lattice Boltzmann solvers (RLBM), which allows the simulation of flows close to the free streaming limit. Following previous works Ambruş and Blaga (2018), we use product quadrature rules and select weights and nodes by separately discretizing the radial and the angular components. This procedure facilitates the development of quadrature-based RLBM with increased isotropy levels, thus improving the accuracy of the method for the simulation of flows beyond the hydrodynamic regime. In order to quantify the improvement of this discretization procedure over existing methods, we perform numerical tests of shock waves in one and two spatial dimensions in various kinetic regimes across the hydrodynamic and the free-streaming limits.</p

Echoes from a long time ago: Chewbacca inflation

The cosmic microwave background (CMB) radiation offers a unique avenue for exploring the early Universe's dynamics and evolution. In this paper, we delve into the fascinating realm of slow-roll inflation, contextualizing the primordial acoustic perturbations as the resonant echoes akin to the iconic sound of Chewbacca from the Star Wars universe. By extrapolating polynomial potentials for these primordial sounds, we illuminate their role in shaping the inflationary landscape. Leveraging this framework, we calculate the scalar spectral index ($n_s$) and tensor-to-scalar ratio ($r$), providing insights into the underlying physics governing the inflationary epoch. Employing a rigorous chi-square ($\chi^2$) analysis, we meticulously scrutinize the Planck data combined with that offered by the BICEP/Keck collaboration to identify the Chewbacca sound profile that best aligns with observational constraints. Our findings not only shed light on the intricate interplay between sound and cosmology but also unveil intriguing parallels between the cosmic symphony of the early universe and beloved cultural icons.Comment: 8 pages + references, 5 figures. Prepared for submission to the Annals of Improbable Research on April 1st 2024. Find "The Sound of the Big Bang" in the audio folder of the source fil

A Lattice Boltzmann Method for relativistic rarefied flows in (2+1) dimensions

We propose an extension to recently developed Relativistic Lattice Boltzmann solvers (RLBM), which allows the simulation of flows close to the free streaming limit. Following previous works Ambruş and Blaga (2018), we use product quadrature rules and select weights and nodes by separately discretizing the radial and the angular components. This procedure facilitates the development of quadrature-based RLBM with increased isotropy levels, thus improving the accuracy of the method for the simulation of flows beyond the hydrodynamic regime. In order to quantify the improvement of this discretization procedure over existing methods, we perform numerical tests of shock waves in one and two spatial dimensions in various kinetic regimes across the hydrodynamic and the free-streaming limits

An efficient synthesis of 4-oxo-2,5-hexadienoates via Δ2-isoxazoline intermediates

An efficient method for the preparation of 4-oxo-2,5-hexadienoates starting from 3,5-disubstituted Δ2-isoxazolines is described. The N-O bond cleavage of the isoxazoline ring, promoted by molybdenum hexacarbonyl, afforded the β-hydroxy ketone intermediates 9a-d which were smoothly dehydrated to the expected 4-oxo-2,5-hexadienoates 10a-d in about 40% yield starting from 6a,b

Fast kinetic simulator for relativistic matter

Relativistic kinetic theory is ubiquitous to several fields of modern physics, finding application at large scales in systems in astrophysical contexts, all of the way down to subnuclear scales and into the realm of quark–gluon plasmas. This motivates the quest for powerful and efficient computational methods that are able to accurately study fluid dynamics in the relativistic regime as well as the transition to beyond hydrodynamics—in principle all of the way down to ballistic regimes. We present a family of relativistic lattice kinetic schemes for the efficient simulation of relativistic flows in both strongly (fluid) and weakly (rarefied gas) interacting regimes. The method can deal with both massless and massive particles, thereby encompassing ultra- and mildly relativistic regimes alike. The computational performance of the method for the simulation of relativistic flows across the aforementioned regimes is discussed in detail, along with prospects of future applications

Synthetic approaches to a mononucleotide prodrug of cytarabine.

Synthetic pathways to a mononucleotide prodrug of cytarabine (Ara-C) bearing S-pivaloyl-2-thioethyl (tBuSATE) groups, as biolabile phosphate protections, are reported. Using a common phosphoramidite approach, two different kinds of nucleoside protecting groups have been investigated. During this study, we obsd. an intermol. migration of the Boc protecting group in the course of the tert-butyldimethylsilyl ether cleavage using tetra-Bu ammonium fluorid

Synthesis and Biological Evaluation of a Series of Substituted Pyrazolo[3,4-d]-1,2,3-triazoles and Pyrazolo[3,4-d]oxazoles

--

Synthesis and antiproliferative activity of 2'-O-allyl-1-beta-D-arabynofuranosyl-uracil, -cytosine and -adenine

Functional modification at position 2' of nucleosides gave potent antiviral and antitumor compound

New isoxazole derivatives of retinoids: Synthesis and activity on growth and differentiation of tumor cells

The effects of several newly synthesized isoxazole analogues of retinoids on differentiation and proliferation of 'in vitro' cultured tumor cell lines are reported. Some of the tested compounds exhibit significative differentiating action, inducing adipogenic conversion of the Chinese hamster FH06T1-1 cell line in a range of 2-10 times the activity of retinoic acid and retinol