Computer simulation of the aluminium extrusion process

The purpose of the work is computer simulation of the aluminium extrusion process using the Finite elements method (FEM). The impact of the speed of a punch falling on the material in the aluminium extrusion process was investigated. It was found that high stresses are created, leading to material destruction, if the punch is falling too fast. The design cycle is significantly reduced in multiple industrial applications if the FEM is applied, which enhances productivity and profits

The harmonic power spectrum of the soft X-ray background I. The data analysis

Fluctuations of the soft X-ray background are investigated using harmonic analysis. A section of the ROSAT All-Sky Survey around the north galactic pole is used. The flux distribution is expanded into a set of harmonic functions and the power spectrum is determined. Several subsamples of the RASS have been used and the spectra for different regions and energies are presented. The effects of the data binning in pixels are assessed and taken into account. The spectra of the analyzed samples reflect both small scale effects generated by strong discrete sources and the large scale gradients of the XRB distribution. Our results show that the power spectrum technique can be effectively used to investigate anisotropy of the XRB at various scales. This statistics will become a useful tool in the investigation of various XRB components.Comment: 12 pages, A&A accepte

Quantum transport and mobility spectrum of topological carriers in (001) SnTe/PbTe heterojunctions

Measurements of magnetotransport in SnTe/PbTe heterojunctions grown by the MBE technique on (001) undoped CdTe substrates were performed. At low magnetic fields, quantum corrections to conductivity were observed that may be attributed to the presence of topological states at the junction interface. For a sample with 5 nm thick SnTe layer, the data analysis suggests that midgap states are actually gapped. However, the phase coherence effects in 10 nm and 20 nm SnTe/PbTe samples are fully explained assuming existence of gapless Dirac cones. Magnetotransport at higher magnetic fields is described in the framework of mobility spectrum analysis (MSA). We demonstrate that the electron- and hole-like peaks observed simultaneously for all SnTe/PbTe heterojunctions may originate from the concave and convex parts of the energy isosurface for topological states -- and not from the existence of quasiparticles both carrying negative and positive charges. This interpretation is supported by numerical calculations of conductivity tensor components for gapless (100) Dirac cones, performed within a classical model and based on the solutions of Boltzmann transport equation. Our approach shows the feasibility of MSA in application to magnetotransport measurements on topological matter

Samorząd terytorialny w oczach socjologów – dyskusja

The last elections in Poland have substantially changed the political discourse. The new government has started to implement numerous reforms. Many of them aroused great controversy, including the one introducing changes in the local government system. This discussion can be considered as an invitation to broader considerations on the future of local government in Poland. It contains statements of six sociologists who are professionally interested in local government issues. They were inspired by three questions (asked by the editors of the text) about: (i) the possible outcome of the reform of the territorial self-government (ii) the functioning of the territorial self-government (iii) the evaluation of the discussion on the announced changes. The answers to these questions were based on the research knowledge and research experiences of the respondents and are therefore more science-based that general opinions typical for a public discussion which often manifest the worldview (or political attitudes) of the debating parties.Ostatnie wybory w Polsce mocno zmieniły sytuację polityczną. Nowe władze przystąpiły do realizacji licznych reform. Wiele z nich wzbudziło duże kontrowersje. Dotyczy to także zapowiedzi związanych ze zmianami w systemie samorządu terytorialnego. Artykuł można potraktować jako zaproszenie do dyskusji na temat przyszłości samorządności terytorialnej w Polsce. Zawiera wypowiedzi sześciu socjologów zajmujących się problematyką samorządową. Były one inspirowane trzema pytaniami, które dotyczyły: (1) bilansu polskiej reformy samorządowej, (2) problemów funkcjonowania samorządów, (3) oceny przebiegu dyskusji poświęconej zapowiedzianym zmianom. Wypowiedzi (odpowiedzi na pytania) opierają się na kompetencjach badaczy i ich doświadczeniu badawczym, są zatem w większym stopniu odwzorowaniem wiedzy naukowej i doświadczeń badawczych niż opinii, czy światopoglądu, które właściwe są dyskursowi publicznemu

The uniform bounded deciding property and the separable quotient problem

[EN] Saxon-Wilansky's paper "The equivalence of some Banach space problems" contains six properties equivalent to the existence of an infinite dimensional separable quotient in a Banach space with nice simplified proofs. In the frame of uniform bounded deciding property, we prove that for an infinite dimensional Banach space E the following properties are equivalents: 1) The unit sphere of E contains a dense and non uniform bounded deciding subset. 2) The unit sphere S of E contains a dense and non strong norming subset. 3) E admits an infinite dimensional separable quotient.López Alfonso, S.; Moll López, SE. (2019). The uniform bounded deciding property and the separable quotient problem. Revista de la Real Academia de Ciencias Exactas Físicas y Naturales Serie A Matemáticas. 113(2):1223-1230. https://doi.org/10.1007/s13398-018-0543-7S122312301132Argyros, S.A., Dodos, P., Kanellopoulos, V.: Unconditional families in Banach spaces. Math. Ann. 341, 15–38 (2008)Fernández, J., Hui, S., Shapiro, H.: Unimodular functions and uniform boundedness. Publ. Mat. 33, 139–146 (1989)Font, V.P.: On exposed and smooth points of convex bodies in Banach spaces. Bull. London Math. Soc. 28, 51–58 (1996)Ka̧kol, J., López-Pellicer, M.: On Valdivia strong version of Nikodym boundedness property. J. Math. Anal. Appl. 446, 1–17 (2017)López-Alfonso, S., Mas, J., Moll, S.: Nikodym boundedness property and webs in $$\sigma$$ σ -algebras. RACSAM Rev. R. Acad. Cienc. Exactas Fís. Nat. Ser. A Math. 110, 711–722 (2016)López-Alfonso, S.: On Schachermayer and Valdivia results in algebras of Jordan measurable sets. RACSAM Rev. R. Acad. Cienc. Exactas Fís. Nat. Ser. A Math. 110, 799–808 (2016)Nygaard, O.: A strong uniform boundedness principle in Banach spaces. Proc. Am. Math. Soc. 129, 861–863 (2001)Schachermayer, W.: On some classical measure-theoretic theorems for non-sigma-complete Boolean algebras. Dissertationes Math. (Rozprawy Mat.) 214, 33 (1982)Śliwa, W.: The separable quotient problem and the strongly normal sequences. J. Math. Soc. Jpn. 64, 387–397 (2012)Saxon, S.A., Wilansky, A.: The equivalence of some Banach space problems. Colloq. Math. 37, 217–226 (1977)Valdivia, M.: On certain barrelled normed spaces. Ann. Inst. Fourier 29, 39–56 (1979)Valdivia, M.: On Nikodym boundedness property. RACSAM Rev. R. Acad. Cienc. Exactas Fís. Nat. Ser. A Mat. 107, 355–372 (2013

Heralded generation of entangled photon pairs

Entangled photons are a crucial resource for quantum communication and linear optical quantum computation. Unfortunately, the applicability of many photon-based schemes is limited due to the stochastic character of the photon sources. Therefore, a worldwide effort has focused in overcoming the limitation of probabilistic emission by generating two-photon entangled states conditioned on the detection of auxiliary photons. Here we present the first heralded generation of photon states that are maximally entangled in polarization with linear optics and standard photon detection from spontaneous parametric down-conversion. We utilize the down-conversion state corresponding to the generation of three photon pairs, where the coincident detection of four auxiliary photons unambiguously heralds the successful preparation of the entangled state. This controlled generation of entangled photon states is a significant step towards the applicability of a linear optics quantum network, in particular for entanglement swapping, quantum teleportation, quantum cryptography and scalable approaches towards photonics-based quantum computing

Distinct Modulation of Spontaneous and GABA-Evoked Gating by Flurazepam Shapes Cross-Talk Between Agonist-Free and Liganded GABAA Receptor Activity

GABAA receptors (GABAARs) play a crucial inhibitory role in the CNS. Benzodiazepines (BDZs) are positive modulators of specific subtypes of GABAARs, but the underlying mechanism remains obscure. Early studies demonstrated the major impact of BDZs on binding and more recent investigations indicated gating, but it is unclear which transitions are affected. Moreover, the upregulation of GABAAR spontaneous activity by BDZs indicates their impact on receptor gating but the underlying mechanisms remain unknown. Herein, we investigated the effect of a BDZ (flurazepam) on the spontaneous and GABA-induced activity for wild-type (WT, α1β2γ2) and mutated (at the orthosteric binding site α1F64) GABAARs. Surprisingly, in spite of the localization at the binding site, these mutations increased the spontaneous activity. Flurazepam (FLU) upregulated this activity for mutants and WT receptors to a similar extent by affecting opening/closing transitions. Spontaneous activity affected GABA-evoked currents and is manifested as an overshoot after agonist removal that depended on the modulation by BDZs. We explain the mechanism of this phenomenon as a cross-desensitization of ligand-activated and spontaneously active receptors. Moreover, due to spontaneous activity, FLU-pretreatment and co-application (agonist + FLU) protocols yielded distinct results. We provide also the first evidence that GABAAR may enter the desensitized state in the absence of GABA in a FLU-dependent manner. Based on our data and model simulations, we propose that FLU affects agonist-induced gating by modifying primarily preactivation and desensitization. We conclude that the mechanisms of modulation of spontaneous and ligand-activated GABAAR activity concerns gating but distinct transitions are affected in spontaneous and agonist-evoked activity