Electric dipole polarizability of low-lying excited states in atomic nuclei

Novel equations for the electric dipole polarizability $\alpha_{_{E1}}$ of low-lying excited states in atomic nuclei -- and the related $(-2)$ moment of the total photo-absorption cross section, $\sigma_{_{-2}}$ -- are inferred in terms of electric dipole and quadrupole matrix elements. These equations are valid for arbitrary angular momenta of the initial/ground and final/excited states and have been exploited in fully converged 1$\hbar\omega$ shell-model calculations of selected {\it p-} and {\it sd-}shell nuclei that consider configuration mixing; advancing previous knowledge from $^{17}$O to $^{36}$Ar, where thousands of electric dipole matrix elements are computed from isovector excitations which include the giant dipole resonance region. Our results are in reasonable agreement with previous shell-model calculations and follow -- except for $^{6,7}$Li and $^{17,18}$O -- Migdal's global trend provided by the combination of the hydrodynamic model and second-order non-degenerate perturbation theory. Discrepancies in $^{6,7}$Li and $^{17}$O arise as a result of the presence of $\alpha$-cluster configurations in odd-mass nuclei, whereas the disagreement in $^{18}$O comes from the mixing of intruder states, which is lacking in the shell-model interactions. More advanced \emph{ab initio} calculations of the dipole polarizability for low-lying excited states covering all the isovector states within the giant dipole resonance region are missing and could be very valuable to benchmark the results presented here and shed further light on how atomic nuclei polarize away from the ground stateComment: 8 pages, 3 figure

Characterization Of Bovine Adipose-Derived Stem Cells

ABSTRACT: Bovine adipose-derived stem cells were obtained from the subcutaneous abdominal adipose tissue. The cells were cultured by the modified tissue-explants method developed in our laboratory, and then analyzed using optical microscopy and flow cytometry. These cells were able to replicate in our cell culture conditions. cell Flow cytometry showed that bovine adipose-derived stem cells expressed mesenchymal stem cell markers (CD73 and CD90). Meanwhile, haematopoietic markers (CD45 and CD34) are absent from bovine adipose-derived stem cells. We also induced their adipogenic differentiation in vitro

Combined analysis of the low-energy enhancement of the gamma-strength function and the giant dipole resonance

The nuclear dipole polarizability is mainly governed by the dynamics of the giant dipole resonance and has been investigated along with the effects of the low-energy enhancement of the photon strength function for nuclides in medium- and heavy-mass nuclei. Cubic-spline interpolations to both data sets show a significant reduction of the nuclear dipole polarizability for semi-magic and doubly magic nuclei, with magic numbers N = 28, 50, 82 and 126, which supports shell effects at high-excitation energies from the quasi-continuum to the giant dipole resonance. This work expands on the data analysis of our recent publication in Ngwetsheni and Orce (Phys. Lett. B 792, 335, 2019), which reveals a new spectroscopic probe to search for “old” and “new” magic numbers at high-excitation energies. New results presented in this work suggest an even higher sensitivity of the nuclear polarizability to shell effects when extrapolating the low-energy enhancement at lower gamma-ray energie

Polarizability effects due to low-energy enhancement of the gamma-strength function

>Magister Scientiae - MScPhysics is the study of natural phenomena. Nuclear physicists have since the discovery of the nucleus been working on understanding its dynamics. The nuclear chart, analogous to the periodic table of elements, is illustrated in Fig. 1.1 and color coded according to decay modes. Several theoretical models, based on various hypothesis, have been developed during the years in order to understand nuclear phenomena such as nucleon-nucleon (n-n) interactions, binding energies, radii, excited states, etc. Unfortunately, no-unique model is actually able to grasp all nuclear phenomena at the desired level of accuracy. Among the di erent models, we notice that two distinct hypotheses can be used to describe nuclear properties. Firstly, the independent particle shell model (IPSM) + the n-n residual interaction, which assumes that a nucleon moves independently in a potential generated by other nucleons. Secondly, the macroscopic models, where a nucleus is considered as a whole, i.e. neutrons and protons behave cooperatively and are mutually coupled to each other; highlighting the short-ranged character of the nuclear force. The liquid-drop model is an example of such macroscopic models. Re nement of these models is dependent on experimental observations that are better detailed for nuclei along the line of - stability, making up a small fraction of the known isotopes, as shown in Fig. 1.1. In practice, various techniques for studying exotic nuclei up to neutron and proton drip-lines have been devised, including the use of radioactive ion beams. However, the main challenges are the synthesization and short lived periods of these exotic nuclei resulting in insu cient data collection from which the characteristics and structural information are extracted. In general, nuclei have unique structures represented by a particular con guration as given by the shell model (SM). These structures impact a number of physical quantities, e.g. transition probabilities, cross sections and photon-strength functions. Experimental methods such as Coulomb excitation or electromagnetic radiation are used to probe these structures without invoking the nuclear force

Glued laminated timber - the durability of bonded joints.

Import 15/01/2013Lepené lamelové dřevo je konstrukčním materiálem na bázi dřeva. Je vytvořeno soustavou lamel vzájemně spojených lepenými spoji řeziva. Lze jej využít na řadu konstrukcí v pozemním i mostním stavitelství a proto musí splňovat požadavky, které se ověřují laboratorními zkouškami. Jedním z těchto požadavků je trvanlivost lepených spojů. Tato trvanlivost lepených spojů může být ovlivněna již výrobou konstrukčních prvků. Výrobní proces proto musí splňovat všechny normové požadavky. V experimentální části mé práce jsem posuzoval vliv prostředí, které bylo simulováno umělým stárnutím, na trvanlivost lepených spojů. Trvanlivost jsem hodnotil na základě zkoušek smykové pevnosti spojů dle norem ČSN EN 392 a ČSN EN 386.Glued laminated timber is construction material on wood basis. It is compounded by system of plates joined together by glued joint of cut timber. It is possible to use it for different types of constructions in civil engineering and bridge constructions and therefore have to meet requirements, which are proved by laboratory tests. One of these requirements is durability of glued joints. Durability of glued joints can be affected already during manufacturing process of construction elements. Manufacturing process must meet all requirements of standards. I viewed the influence of the environment on durability of bonded joints in research part of my thesis, this influence was simulated by accelerated ageing. I evaluated the durability on the basis of shear strength test of joints according to standards ČSN EN 392 and ČSN EN 386.Prezenční223 - Katedra stavebních hmot a hornického stavitelstvívelmi dobř

Proteomika membrane masne globule: kratki pregled biologije epitelnih stanica mliječnih žlijezda

Lipids are released in milk as fat globules, which are droplets of apolar lipids surrounded by a complex membrane deriving from the mammary epithelial cell (MEC) and called the milk fat globule membrane (MFGM). The structure of the MFGM is highly complex and closely related to the mechanisms of milk fat globule secretion in the mammary epithelial cell. Indeed, MFGM is composed of two biological membranes, a phospholipid monolayer, deriving from the endoplasmic reticulum, and a phospholipid bilayer, which originates from the apical plasma membrane of the MEC, with variable amounts of cytoplasm trapped between. Biochemical techniques (i.e. sodium dodecyl sulphate-polyacrylamide gel electrophoresis followed by different staining procedures) have been employed historically to characterize major MFGM proteins, namely MUC-1, fatty acid synthase, xanthine oxidase, butyrophilin, lactadherin, and adipophilin. However, recent advances in the field of proteomics (mostly development of one-dimensional gel electrophoresis approach coupled with tandem mass spectrometry) have led to the identification of hundreds of proteins associated with the MFGM. Surprisingly, newly identified MFGM proteins were not only involved in lipid metabolic or exocytosis-related biological processes, but also in cell signalling, translation, or host defense-related mechanisms. Therefore, the milk fat globule should no longer be viewed as an inert structure only devoted to the delivery of lipids to the newborn, but rather as a dynamic and informative compartment which can contribute to the improvement of our comprehension of the mammary gland biology.Lipidi se oslobađaju u mlijeku kao masne globule, tj. kapljice nepolarnih lipida okružene složenom membranom, koja se sastoji od epitelnih stanica mliječnih žlijezda, a nazivamo ju membrana masne globule. Struktura je te membrane iznimno složena, a utječe na mehanizam izlučivanja globule u epitelnu stanicu mliječne žlijezde. Sastavljena je od dviju bioloških membrana, fosfolipidnog sloja (koji potječe od endoplazmatskog retikuluma) i fosfolipidnog dvosloja (od plazmatske membrane epitelnih stanica vrha mliječne žlijezde), a između ta dva sloja nalazi se citoplazma različite debljine. Biokemijske su tehnike, poput SDS-PAGE s različitim postupcima bojanja, desetljećima primjenjivane za karakterizaciju glavnih proteina membrane masne globule, kao što su: MUC-1, sintaza masnih kiselina, ksantin oksidaza, BTN, MFG-E8 i ADPH. Novija dostignuća na polju protemike (većinom vezana uz razvoj 1D-LC-MS/MS metode) omogućila su identifikaciju stotinu proteina povezanih s membranom masne globule. Ti proteini sudjeluju u metabolizmu lipida i procesima egzocitoze, te u prenošenju signala, translaciji proteina i obrambenim mehanizmima domaćina. Stoga masnu globulu ne možemo više promatrati samo kao inertnu strukturu koja mastima opskrbljuje dojenčad već i kao dinamičan i informativan dio stanice, pomoću kojega se bolje može razumjeti biologija mliječnih žlijezda

Inverse solution to the heat transfer coeffcient for the oxidized ARMCO steel plate cooling by the air nozzle from high temperature

[EN] The inverse solution tests have been performed to the experimental data obtained during the oxidised Armco steel plate cooling by the air nozzle. The three-dimensional numerical model of heat transfer during the plate cooling has been considered. Steel products cooled in the air from high temperatures are covered with the oxide layer having significantly lower conductivity and a different surface structure comparing to the non-oxidised metal surface. The Armco steel has been selected as the experimental material because it oxidised in a similar way to carbon steels but there is no microstructure evolution process in Armco steel below 900oC. It eliminates in the inverse solutions serious problems caused by a latent heat of microstructure evolutions encountered during carbon steel cooling. In the present study the steel plate has been heated to about 900℃ and cooled by the circular air jet. The plate temperature has been measured by 36 thermocouples. The test of the selected inverse solution models involving a different number of degrees of freedom have been performed. The influence of the scale layer on the results of the inverse solution to the heat flux and heat transfer coefficient has been investigated.Scientific study financed from the regular activity of the Faculty of Metals Engineering and Industrial Computer Science of AGH University of Science and Technology.Jasiewicz, K.; Malinowski, Z.; Cebo-Rudnicka, A. (2022). Inverse solution to the heat transfer coeffcient for the oxidized ARMCO steel plate cooling by the air nozzle from high temperature. En Proceedings of the YIC 2021 - VI ECCOMAS Young Investigators Conference. Editorial Universitat Politècnica de València. 233-244. https://doi.org/10.4995/YIC2021.2021.12344OCS23324

Global trends of the electric dipole polarizability from shell-model calculations

Shell-model calculations of the electric dipole (E1) polarizability have been performed for the ground state of selected p- and sd-shell nuclei, substantially advancing previous knowledge. Our results are slightly larger compared with the somewhat more scattered photo-absorption cross-section data, albeit agreeing with ab initio calculations at shell closures and presenting a smooth trend that follows the leptodermus approximation provided by the finite-range droplet model (FRDM). The total E1 strengths also show an increasing trend proportional to the mass number which follows from the classical oscillator strength (TRK) sum rule for the E1 operator. The enhancement of the energy-weighted sum over E1 excitations with respect to the TRK sum rule arises from the use of experimental single-particle energies and the residual particle-hole interaction.Comment: 9 pages, 3 figure