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Tytuł:
Wreath Product in Factorization of Holosymmetric Group
Autorzy:
Florek, W.
Lulek, T.
Powiązania:
https://bibliotekanauki.pl/articles/1887747.pdf
Data publikacji:
1991-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.50.Em
02.20.+b
Opis:
The holosymmetric group Q of an n-dimensional crystal lattice determined by a given lattice basis B is considered. This group is contained in the n-dimensional orthogonal group O(n) so its elements preserve the orthogonality of basis vectors and their lengths. These conditions yield the decomposition of lattice basis into orthogonal sublattices and next the factorization of the holosymmetric group, which can be written as a direct product of complete monomial groups of k-dimensional (k ≤ n) holosymmetric groups. Simple, decomposable and primitive holosymmetric groups are discussed. The results for n ≤ 4 are presented.
Źródło:
Acta Physica Polonica A; 1991, 79, 6; 843-852
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Uniwersytet Ekonomiczny w Poznaniu
Evaluation of the economy for macroeconomic policy purposes
Autorzy:
Tomidajewicz, Janusz J.
Błaszczyk, Paweł
Powiązania:
https://bibliotekanauki.pl/articles/693462.pdf
Data publikacji:
2013
Wydawca:
Uniwersytet im. Adama Mickiewicza w Poznaniu
Tematy:
JEL
B22
B41
E20
E30
E61
goals of an economic policy
assessment of the economy
economic policy
cele polityki gospodarczej
ocena gospodarki
polityka ekonomiczna
Opis:
The main aim of this paper is to present a combination of measures that are useful for economic policy activities in the assessment of a given economic condition from two points of view, in the shortand long-term perspective. At the same time, it should be noted that, in relation to the former, the authors’ comments are rather of an ordering character, while their own proposals have been formulated mainly with regard to the latter interpretation. The paper consists of two basic parts. One is predominantly theoretical in character and concerns the macroeconomic basics of economy evaluation and its use by economic decision makers and as well entities of the private sector (parts II and III). The other presents partial indicators of the contemporary macroeconomic policy. It includes among others: the GDP and the general price level dynamics, the rate of unemployment and the public sector balance. Additionally, a multi-indicator, a macroeconomic measure of the economy is presented (parts IV and V).
Głównym celem niniejszego opracowania jest przedstawienie zastawu mierników wykorzystywanych w polityce gospodarczej do oceny sytuacji gospodarczej z dwóch punktów widzenia – zarówno w krótko-, jak i długookresowej perspektywie. Należy przy tym zaznaczyć, że w odniesieniu do mierników w pierwszym ujęciu przedstawione tu uwagi mają raczej charakter porządkujący, własne propozycje autorów zaś sformułowane zostały głównie w odniesieniu do drugiego ujęcia. W konsekwencji artykuł składa się z dwóch głównych części. Pierwsza ma przede wszystkim charakter teoretyczny i dotyczy makroekonomicznych podstaw oceny gospodarki i jej wykorzystania zarówno przez decydentów gospodarczych, jak i podmioty sektora prywatnego (punkty II i III). W drugiej części prezentowane są cząstkowe wyznaczniki bieżącej makroekonomicznej polityki gospodarczej. Można do nich zaliczyć m.in.: dynamikę PKB i ogólnego poziomu cen, stopę bezrobocia i bilans sektora finansów publicznych. Dodatkowo przedstawiona została również metodyka WMMOG (punkty IV i V).
Źródło:
Ruch Prawniczy, Ekonomiczny i Socjologiczny; 2013, 75, 3; 123-137
0035-9629
2543-9170
Pojawia się w:
Ruch Prawniczy, Ekonomiczny i Socjologiczny
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Tunneling of Interacting Fermions in 1D Systems
Autorzy:
Gendiar, A.
Moško, M.
Vagner, P.
Németh, R.
Powiązania:
https://bibliotekanauki.pl/articles/2043712.pdf
Data publikacji:
2005-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.23.-b
73.61.Ey
Opis:
Using the self-consistent Hartree-Fock approximation for spinless electrons at zero temperature, we study tunneling of the interacting electron gas through a single δ barrier in a finite one-dimensional wire connected to contacts. Our results exhibit features known from correlated many-body models. In particular, the conductance decays with the wire length as ∝ L$\text{}^{-2α}$, where the powerα is universal. We also show that a similar result for a wire conductance can be extracted from the persistent current (I) through theδ barrier in a one-dimensional ring, where it is known that I∝ L$\text{}^{-1-α}$.
Źródło:
Acta Physica Polonica A; 2005, 108, 4; 661-667
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Topographic and Energetic Heterogeneity Studies of Oxidized Graphite Surface by Scanning Tunneling Microscopy/Spectroscopy and Photoelectron Spectroscopy
Autorzy:
Klusek, Z.
Powiązania:
https://bibliotekanauki.pl/articles/1963284.pdf
Data publikacji:
1997-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.16.Ch
71.20.-b
Opis:
Scanning tunneling microscopy and spectroscopy and X-ray photoelectron spectroscopy are used to study oxidation effects of nitric acid on a highly-oriented pyrolytic graphite surface. Various etching times at constant temperature are applied in order to create local binding sites on the surface without creating deep defects. A single and paired chains structure, different from pure graphite at atomic scale, is shown by scanning tunneling microscopy. This can be explained by the presence of oxygenate groups on the surface, revealed by X-ray photoelectron spectroscopy. Both scanning tunneling spectroscopy and X-ray photoelectron spectroscopy demonstrate the vanishing of π bands characteristic of sp$\text{}^{2}$ graphite hybridization. This, in turn, can be explained by dehybridization related to new bondings of the graphite carbons in the oxygenate groups. An important result of area averaging spectroscopy is the observed energetic heterogeneity considered in terms of the changes of local electronic density of states of the oxidized surface.
Źródło:
Acta Physica Polonica A; 1997, 91, 3; 569-582
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Thermodynamic and Electronic Properties of $OsB_2$ from First-Principles Calculations
Autorzy:
Cheng, Y.
Yang, J.
Wang, Y.
Ji, G.
Chen, X.
Powiązania:
https://bibliotekanauki.pl/articles/1365243.pdf
Data publikacji:
2014-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.15.Mb
61.50.Ks
67.25.de
71.20.-b
Opis:
The pressure induced phase transitions of $OsB_2$ from the orthorhombic structure (Orth) to the hexagonal structure (Hex) is investigated by using ab initio plane-wave pseudopotential density functional theory, together with quasi-harmonic Debye model. We find that the pressure-induced phase transition occurs at 2.8 GPa and 12.5 GPa by local density approximation and general gradient approximation, respectively. It is predicted that $OsB_2$ has no phase transition temperature from the Orth structure to the Hex structure. Moreover, the dependences of the relative volume V/$V_0$ on the pressure, thermal expansion coefficient α on the pressure and temperature are also successfully obtained. The electronic properties including energy band, total and partial density of states and electron density difference for two structures are also analyzed. The Mulliken charges and Bond populations for both Orth and Hex structures are also obtained.
Źródło:
Acta Physica Polonica A; 2014, 125, 5; 1186-1190
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Puzzle of the 0.7 Anomaly in Conductance of Quantum Point Contact Reexamined
Autorzy:
Figielski, T.
Powiązania:
https://bibliotekanauki.pl/articles/1399104.pdf
Data publikacji:
2013-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.23.Ad
73.61.Ey
72.25.-b
03.65.Ge
Opis:
A novel approach to the solution of the long-standing problem, called 0.7 anomaly in quantum point contact, is proposed. It is based on fundamental principles of quantum mechanics and can explain all main properties of the anomaly.
Źródło:
Acta Physica Polonica A; 2013, 124, 5; 841-842
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The optoelectronic properties of Sb doped BBi compounds
Autorzy:
Ustundag, M.
Yalcin, B.
Aslan, M.
Bagcı, S.
Powiązania:
https://bibliotekanauki.pl/articles/1065716.pdf
Data publikacji:
2016-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.15.Mb
78.20.Ci
71.20.-b
61.72.Vv
Opis:
We have determined structural, electronic and optical properties of BBi_{1-x}Sb_x alloy by using density functional theory based on the full potential linearized augmented plane wave method. For the exchange correlation potential, the generalized gradient approximation of Perdew, Burke, and Ernzerhof has been performed. The structural properties, including lattice constants and bulk modulus have been calculated by changing x concentration. We have investigated the effect of composition on lattice constant, bulk modulus and band gap. Properly, direct/indirect band character of BBi_{1-x}Sb_x has been investigated depending on the x concentration. Then we have determined some basic linear optical properties BBi_{1-x}Sb_x alloy in direct band gap region. The obtained results have been compared with available studies. All the calculations have been performed after geometry optimization. As far as we know, no experimental or theoretical data are presently available for the studied ternary alloy BBi_{1-x}Sb_x (0 < x < 1).
Źródło:
Acta Physica Polonica A; 2016, 130, 1; 98-100
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
TEM Study of the Structural Properties of Nanowires Based on Cd, Zn, Te grown by MBE on Silicon Substrates
Autorzy:
Kaleta, A.
Kret, S.
Sanchez, A.
Bilska, M.
Kurowska, B.
Szczepańska, A.
Płachta, J.
Wojnar, P.
Wojciechowski, T.
Powiązania:
https://bibliotekanauki.pl/articles/1032910.pdf
Data publikacji:
2017-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.05.Dz
81.07.-b
61.46.-w
62.23.Hj
81.07.Gf
61.46.Km
78.67.Uh
07.10.Pz
68.35.Gy
68.37.Lp
68.37.Og
68.37.Ma
Opis:
In this work we report on the atomic structures, elemental distribution, defects and dislocations of three types of semiconductor nanowires: ZnTe, CdTe, and complex ZnTe/(Cd,Zn)Te core/shell hetero-nanowires grown by a molecular beam epitaxy on (111) Si substrate using a vapor-liquid-solid mechanism. The structural properties and the chemical gradients were measured by transmission electron microscopy methods. The nanowires reveal mainly sphalerite structure, however wurtzite nanowires were also observed.
Źródło:
Acta Physica Polonica A; 2017, 131, 5; 1399-1405
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Synthesis of $Fe_4[Fe(CN)_6]_3$·$14H_2O$ Nanopowder by Co-Precipitation Technique and Effect of Heat Treatment
Autorzy:
Rohilla, S.
Lal, B.
Sunder, S.
Aghamkar, P.
Kumar, S.
Aggarwal, A.
Powiązania:
https://bibliotekanauki.pl/articles/1535871.pdf
Data publikacji:
2010-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.07.-b
64.70.Nd
61.82.Rx
Opis:
Nanopowder of iron cyanide hydrate (member of Prussian blue family) was obtained using ferric chloride and potassium cyanide in their dilute solution through co-precipitation method. The effect of thermal annealing on iron cyanide hydrate nanocrystallites have been studied in detail. The formation of $Fe_4[Fe(CN)_6]_3$·$14H_2O$ and iron oxides was revealed by the Fourier transform infrared spectroscopy. The crystal structure, morphology and size of nanocrystallites were investigated by X-ray diffraction and transmission electron microscope. Results suggest that using co-precipitation technique, nanopowder of iron cyanide hydrate, in typically spherical shape, can be obtained and their thermal treatment also yield iron oxide nanocrystallites of spherical with good homogeneity. The size of the prepared nanocrystallites was found in the range 20-36 nm. It was observed that thermal treatment, typically at 800°C (4 h), iron cyanide hydrate ($Fe_4[Fe(CN)_6]_3$·$14H_2O$) nanocrystallites transformed into iron oxide ($α-Fe_2O_{3,}$ hematite) nanocrystallites.
Źródło:
Acta Physica Polonica A; 2010, 118, 4; 696-700
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Synthesis and Characterization of ZnO Doped with $Fe_{2}O_{3}$ - Hydrothermal Synthesis and Calcination Process
Autorzy:
Sibera, D.
Jędrzejewski, R.
Mizeracki, J.
Presz, A.
Narkiewicz, U.
Łojkowski, W.
Powiązania:
https://bibliotekanauki.pl/articles/1807546.pdf
Data publikacji:
2009-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.46.-w
68.37.Hk
81.07.-b
81.16.Be
Opis:
The aim of the present work is to compare two methods of synthesis of nanocrystallline zinc oxide doped with iron oxide. The synthesis was carried out using microwave asssisted hydrothermal synthesis and traditional wet chemistry method followed by calcination. The phase composition of the samples was determined using X-ray diffraction measurements. Depending on the chemical composition of the samples, hexagonal ZnO, and/or cubic $ZnFe_{2}O_{4}$ were identified. The morphology of the received materials was characterized using scanning electron microscopy. Two different structures of agglomerates were observed: a hexagonal structure (corresponding to zinc oxide) and spherical (corresponding to spinel phase). The effect of the iron oxide concentration on specific surface area and density of the samples was determined.
Źródło:
Acta Physica Polonica A; 2009, 116, S; S-133-S-135
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Surface Modification of Metallic Targets with Ultrashort Laser Pulses
Autorzy:
Gakovic, B.
Stasic, J.
Petrovic, S.
Radak, B.
Krmpot, A.
Jelenkovic, B.
Trtica, M.
Powiązania:
https://bibliotekanauki.pl/articles/1795615.pdf
Data publikacji:
2009-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
42.62.-b
61.80.Ba
61.82.Bg
79.20.Eb
Opis:
Interaction of pulsed femtosecond Ti:sapphire laser (160 fs), operating at high repetition rate (75 MHz) at 800 nm, with nickel-based superalloy Inconel 600 and tungsten-titanium (WTi) target was studied. The WTi target was in form of thin film deposited on silicon substrate. Low laser fluence of maximum 50 mJ/cm^{2} had modified the target surface during irradiation/exposure time of seconds or minutes. The radiation absorbed from the laser beam generates at the surface a series of effects, such as direct material vaporization, formation of clusters, etc. Morphological features of the targets can be summarized as: (a) intensive removal of material and crater appearance; (b) creation of nanostructures; (c) microcracking, etc. Ablation of Inconel 600 surface is effective, resulting in formation of holes with small diameter ( ≤ 10 μm) and relatively large depth ( ≤ 50 μm). In case of WTi target/thin film, the surrounding rim is not so expressed, and crater depths are lower. It can be concluded that the average laser power of the order of watts, pulse energies of the order of nanojoules and high repetition rates (MHz range) can successfully modify metallic materials.
Źródło:
Acta Physica Polonica A; 2009, 116, 4; 611-613
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Superconductivity Study of GaN Highly Doped by Transition Metals
Autorzy:
Gosk, J.
Boćkowski, M.
Tokarczyk, M.
Kowalski, G.
Twardowski, A.
Powiązania:
https://bibliotekanauki.pl/articles/1399142.pdf
Data publikacji:
2013-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.25.Ha
74.70.-b
74.25.Dw
75.50.-y
61.72.Dd
81.10.Dn
Opis:
GaN:Cr and GaN:Fe single crystals as well as GaN:Mn micropowders highly doped by transition metals were grown to investigate low temperature superconductivity. Magnetic measurements revealed type I superconductivity with $T_{C} ≈ 6 K$ and $H_{C} ≈ 600 Oe$, identical for all compounds and also identical to that observed before in GaP:Cr and GaAs:Cr. The presence of amorphous inclusions of gallium may explain existing superconductivity as a result of a phase transition leading to β-Ga during cooling down of the sample. Since the observed parameters are close to those characteristic for superconducting Ga(II) this possibility could not be ruled out.
Źródło:
Acta Physica Polonica A; 2013, 124, 5; 877-880
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Study on the Breakdown Mechanism of Fabrication of Micro Channels in Fused Silica Substrates with ps Laser Pulses
Autorzy:
Li, S.
Bai, Z.
Qin, S.
Powiązania:
https://bibliotekanauki.pl/articles/1400288.pdf
Data publikacji:
2013-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
52.50.Jm
52.40.Hf
61.80.-x
42.62.-b
Opis:
A new microchannel fabrication technology for fused silica substrate is presented. A mode-locked laser was used to fabricate straight microchannels in a fused silica substrate by laser plasma-induced plasma. The depth of the channels is up to 5 mm and there are no thermal cracks around the channel. We studied the ionization mechanism of optical breakdown formed by laser pulses and discussed the optical breakdown threshold. A mechanism is proposed to explain the formation of the microchannels and the characteristics of the microchannels are analyzed through the laser pulse characteristics.
Źródło:
Acta Physica Polonica A; 2013, 123, 1; 67-72
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Structural and Optical Properties of Nanostructured Fe-Doped SnO₂
Autorzy:
Saleh, S.
Ibrahim, A.
Mohamed, S.
Powiązania:
https://bibliotekanauki.pl/articles/1398977.pdf
Data publikacji:
2016-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.07.-b
61.05.C-
78.20.-e
Opis:
Nanocrystalline $Sn_{1-x}Fe_xO_2$ (where x = 0, 0.01, 0.02, 0.03 and 0.04) powders have been successfully synthesized by the hydrothermal method followed by sintering at 1000°C for 3 h. The morphology and structure of the samples have been analyzed by field emission scanning electron microscope and X-ray diffraction, respectively. X-ray diffraction results revealed that all diffraction peaks positions agree well with the reflection of a tetragonal rutile structure of SnO₂ phase without extra peaks. The formation of a tetragonal rutile structure of SnO₂ nanostructures was further supported by the Raman spectra. The band gap of Fe-doped SnO₂ nanoparticles was estimated from the diffuse reflectance spectra using the Kubelka-Munk function and it was decreasing slightly with the increase of Fe ion concentration from 3.59 to 3.52 eV. The variation in band gap is attributed predominantly to the lattice strain and particle size. The presence of chemical bonding was confirmed by the Fourier transform infrared spectra.
Źródło:
Acta Physica Polonica A; 2016, 129, 6; 1220-1225
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
STM Study on the (100) Surface of the Ag-In-Yb 1/1 Cubic Approximant
Autorzy:
Cui, C.
Sharma, H.
Nugent, P.
Shimoda, M.
Pang Tsai, An
Powiązania:
https://bibliotekanauki.pl/articles/1373497.pdf
Data publikacji:
2014-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.44.Br
68.35.B-
68.37.Ef
Opis:
Scanning tunneling microscopy studies have revealed a periodic step-terrace structure in the (100) surface of the Ag-In-Yb 1/1 cubic approximant. The step height between the large terraces is about 0.73 nm, approximately one-half of the lattice constant, which is consistent with the bcc-like crystalline structure of this crystal. Two small terraces are observed between the adjacent large terraces. High-resolution STM images of the large terrace exhibit a square lattice of protrusions with a lattice constant of about 1.55 nm, which is consistent with the bulk lattice constant. The scanning tunneling microscopy results suggest that the large terraces are associated with the planes that intersect the centers of rhombic triacontrahedral clusters (the building unit of the crystal) and show the highest atomic density along the [100] axis. It is highly likely that the small terraces are related to moderate atomic density planes and are less stable than the large terraces.
Źródło:
Acta Physica Polonica A; 2014, 126, 2; 577-580
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł

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