221 research outputs found
Doping Dependence of Polaron Hopping Energies in La(1-x)Ca(x)MnO(3) (0<= x<= 0.15)
Measurements of the low-frequency (f<= 100 kHz) permittivity at T<= 160 K and
dc resistivity (T<= 430 K) are reported for La(1-x)Ca(x)MnO(3) (0<= x<= 0.15).
Static dielectric constants are determined from the low-T limiting behavior of
the permittivity. The estimated polarizability for bound holes ~ 10^{-22}
cm^{-3} implies a radius comparable to the interatomic spacing, consistent with
the small polaron picture established from prior transport studies near room
temperature and above on nearby compositions. Relaxation peaks in the
dielectric loss associated with charge-carrier hopping yield activation
energies in good agreement with low-T hopping energies determined from
variable-range hopping fits of the dc resistivity. The doping dependence of
these energies suggests that the orthorhombic, canted antiferromagnetic ground
state tends toward an insulator-metal transition that is not realized due to
the formation of the ferromagnetic insulating state near Mn(4+) concentration ~
0.13.Comment: PRB in press, 5 pages, 6 figure
Π‘ΠΈΠ½ΠΊΡΠ΅ΡΠΈΠ·ΠΌ ΠΊΠ²Π°Π½ΡΠΈΡΠ°ΡΠΈΠ²Π½ΠΈΡ ΠΊΠΎΠ½ΡΡΡΡΡΠ²Π°Π½Ρ (Π½Π° ΠΌΠ°ΡΠ΅ΡΡΠ°Π»Ρ ΡΠΈΡΠ»ΡΠ²Π½ΠΈΠΊΡΠ² Π°Π½Π³Π»ΡΠΉΡΡΠΊΠΎΡ ΠΌΠΎΠ²ΠΈ)
Π£ ΡΡΠ°ΡΡΡ ΠΎΡΠΌΠΈΡΠ»ΡΡΡΡΡΡ ΡΠ²ΠΈΡΠ΅ ΡΠΈΠ½ΠΊΡΠ΅ΡΠΈΠ·ΠΌΡ Π½Π° ΠΌΠ°ΡΠ΅ΡΡΠ°Π»Ρ Π°Π½Π³Π»ΡΠΉΡΡΠΊΠΈΡ
ΠΊΠ²Π°Π½ΡΠΈΡΠ°ΡΠΈΠ²Π½ΠΈΡ
ΡΠ»ΡΠ², Π½ΡΠΌΠ΅ΡΠ°Π»ΡΠ½ΠΈΡ
Ρ Π΄Π΅Π½ΡΠΌΠ΅ΡΠ°Π»ΡΠ½ΠΈΡ
ΡΠ»ΠΎΠ²ΠΎΡΠΏΠΎΠ»ΡΡΠ΅Π½Ρ. ΠΠ°ΡΡΡ ΠΌΡΡΡΠ΅ ΠΏΠΎΡΡΠ²Π½ΡΠ½Π½Ρ Π· Π΄ΠΈΠΌΠ΅Π½Π·ΡΠΎΠ½Π°Π»ΡΠ½ΠΎΡ Π»Π΅ΠΊΡΠΈΠΊΠΎ. Π‘ΠΈΠ½ΠΊΡΠ΅ΡΠΈ ΡΠΎΠ·Π³Π»ΡΠ΄Π°ΡΡΡΡΡ Π½Π° ΠΌΠ°ΡΠ΅ΡΡΠ°Π»Ρ ΡΠΈΠ½ΠΊΡΠ΅ΡΡΠ΅ΠΌΡΡ. ΠΠΊΡΡΠ°Π»ΡΠ½ΡΡΡΡ ΡΠ΅ΠΌΠΈ ΠΌΠΎΡΠΈΠ²ΡΡΡΡΡΡ Π·ΡΠΎΡΡΠ°ΡΡΠΈΠΌ ΡΠ½ΡΠ΅ΡΠ΅ΡΠΎΠΌ ΡΡΠ΅Π½ΠΈΡ
Π΄ΠΎ Π½ΠΎΠ²ΠΎΡ Π½Π°ΡΠΊΠΎΠ²ΠΎΡ ΠΏΠ°ΡΠ°Π΄ΠΈΠ³ΠΌΠΈ β ΡΠΈΠ½Π΅ΡΠ³Π΅ΡΠΈΠΊΠΈ.ΠΠ±ΡΠ΅ΠΊΡΠΎΠΌ ΠΈΡΡΠ»Π΅Π΄ΠΎΠ²Π°Π½ΠΈΡ ΡΠ²Π»ΡΠ΅ΡΡΡ ΡΠ΅Π½ΠΎΠΌΠ΅Π½ ΡΠΈΠ½ΠΊΡΠ΅ΡΠΈΠ·ΠΌΠ° Π½Π° ΠΌΠ°ΡΠ΅ΡΠΈΠ°Π»Π΅ ΠΊΠ²Π°Π½ΡΠΈΡΠ°ΡΠΈΠ²Π½ΡΡ
Π΅Π΄ΠΈΠ½ΠΈΡ Π² ΠΌΠΎΠ΄ΡΡΠ°Ρ
ΡΠ·ΡΠΊΠ°, ΡΠ΅ΡΠΈ ΠΈ ΡΠ΅ΡΠ΅Π²ΠΎΠ³ΠΎ ΠΏΠΎΠ²Π΅Π΄Π΅Π½ΠΈΡ (ΠΏΡΠ΅Π΄ΠΌΠ΅Ρ ΠΈΡΡΠ»Π΅Π΄ΠΎΠ²Π°Π½ΠΈΡ). Π¦Π΅Π»Ρ ΠΈΡΡΠ»Π΅Π΄ΠΎΠ²Π°Π½ΠΈΡ ΡΠΎΡΡΠΎΠΈΡ Π² ΠΎΡΠΌΡΡΠ»Π΅Π½ΠΈΠΈ ΡΠΏΠΎΠΌΡΠ½ΡΡΠΎΠΉ ΠΏΠ°ΡΠ°Π΄ΠΈΠ³ΠΌΡ, Π΅Π΅ ΠΈΠ΄Π΅ΠΉ, ΠΏΡΠΎΡΠ΅ΡΡΠΎΠ² ΡΠ°ΠΌΠΎΠΎΡΠ³Π°Π½ΠΈΠ·Π°ΡΠΈΠΈ ΠΈ ΡΠ°ΠΌΠΎΡΠ°Π·Π²ΠΈΡΠΈΡ. Π ΡΠ°Π±ΠΎΡΠ΅ Π²Π΅ΡΠΈΡΠΈΡΠΈΡΡΡΡΡΡ Π³ΠΈΠΏΠΎΡΠ΅Π·Ρ:
- Π½ΠΎΠΌΠΈΠ½Π°ΡΠΈΠ²Π½ΡΠ΅ Π΅Π΄ΠΈΠ½ΠΈΡΡ ΡΠ²Π»ΡΡΡΡΡ Π±ΠΈΠ»Π°ΡΠ΅ΡΠ°Π»ΡΠ½ΡΠΌΠΈ ΠΈ ΡΠΈΠ½ΠΊΡΠ΅ΡΠΈΡΠ½ΡΠΌΠΈ;
- ΠΈΡ
ΡΠΈΡΡΠ΅ΠΌΠ½Π°Ρ ΠΎΡΠ³Π°Π½ΠΈΠ·Π°ΡΠΈΡ ΠΈ ΡΠ²ΠΎΠ»ΡΡΠΈΡ ΠΈΠ½ΡΠ΅Π³ΡΠΈΡΡΠ΅ΡΡΡ ΡΡΠΈΠ°Π΄ΠΎΠΉ ΠΌΠ°ΡΠ΅ΡΠΈΠ°Π»Π°, ΡΠ½Π΅ΡΠ³ΠΈΠΈ, ΠΈΠ½ΡΠΎΡΠΌΠ°ΡΠΈΠΈ;
- ΠΎΡΠ½ΠΎΠ²Π½ΡΠΌ ΠΌΠ΅ΡΠΎΠ΄ΠΎΠ»ΠΎΠ³ΠΈΡΠ΅ΡΠΊΠΈΠΌ ΠΌΠ΅Ρ
Π°Π½ΠΈΠ·ΠΌΠΎΠΌ ΡΠ²Π»ΡΠ΅ΡΡΡ ΠΎΠ½ΡΠΎΠ³Π½ΠΎΡΠΈΠΎΠ»ΠΎΠ³ΠΈΡΠ΅ΡΠΊΠΈΠΉ ΠΏΠΎΠ΄Ρ
ΠΎΠ΄ ΠΊ ΠΈΡΡΠ»Π΅Π΄ΡΠ΅ΠΌΡΠΌ ΡΠ΅ΡΠ΅ΡΠ΅Π½ΡΠ°ΠΌ.
Π¦Π΅Π½Π½ΡΠΌ Π²ΠΊΠ»Π°Π΄ΠΎΠΌ Π² ΡΠΈΠ½Π΅ΡΠ³Π΅ΡΠΈΠΊΡ ΠΏΡΠ΅Π΄ΡΡΠ°Π²Π»ΡΠ΅ΡΡΡ Π΄Π°Π»ΡΠ½Π΅ΠΉΡΠ°Ρ ΡΠ°Π·ΡΠ°Π±ΠΎΡΠΊΠ° ΠΎΡΠ½ΠΎΠ²Π½ΡΡ
ΠΏΠΎΠ»ΠΎΠΆΠ΅Π½ΠΈΠΉ ΠΈ ΠΏΠΎΠ½ΡΡΠΈΠΉ Π½ΠΎΠ²ΠΎΠΉ Π½Π°ΡΡΠ½ΠΎΠΉ ΠΏΠ°ΡΠ°Π΄ΠΈΠ³ΠΌΡ β Π»ΠΈΠ½Π³Π²ΠΎΡΠΈΠ½Π΅ΡΠ³Π΅ΡΠΈΠΊΠΈ.The article in question deals with the English quantitative units, i.e. numerals, numeric words, on the one hand, and dimension units β words of weight and measure, on the other hand. This object is dealt with in the endozones of language, speech and speech behaviour. The aim of investigation consists in identification of the markers of systematic arrangement of the paradigm β its selforganization and evolution:
- verification of hypotheses that:
- bilateral and syncretic;
- aspects of words go together;
- incorporated subject mater, energy and information of syncretas make the triad go;
- ontognosiological method is at work.
Topicality of the theme is objectivized by the growing interest to the problem by scientists of this country and abroad. This is a new scientific paradigm (synergetics), let alone many a lacunar items within its domain. Valour scenes remain undiscovered yet and await their solution in terms of mayor ideas and categories.
Lacunarity is indebted to the process of cognition, cognized and non-cognized phenomenas. The choise of complex ontognosiological approach is determined by the nature of referents. Missing items come into being due to the problem of nothingness. The syncretas come archaic due to losses in the vocabulary or fall out of concepts. Some words are prohibited by taboo. Some syncretas work in the speech behaviour (silence, hesitation, pauses)
Whatβs so bad about scientism?
In their attempt to defend philosophy from accusations of uselessness made by prominent scientists, such as Stephen Hawking, some philosophers respond with the charge of βscientism.β This charge makes endorsing a scientistic stance, a mistake by definition. For this reason, it begs the question against these critics of philosophy, or anyone who is inclined to endorse a scientistic stance, and turns the scientism debate into a verbal dispute. In this paper, I propose a different definition of scientism, and thus a new way of looking at the scientism debate. Those philosophers who seek to defend philosophy against accusations of uselessness would do philosophy a much better service, I submit, if they were to engage with the definition of scientism put forth in this paper, rather than simply make it analytic that scientism is a mistake
High Temperature Thermopower in La_{2/3}Ca_{1/3}MnO_3 Films: Evidence for Polaronic Transport
Thermoelectric power, electrical resistivity and magnetization experiments,
performed in the paramagnetic phase of La_{2/3}Ca_{1/3}MnO_3, provide evidence
for polaron-dominated conduction in CMR materials. At high temperatures, a
large, nearly field-independent difference between the activation energies for
resistivity (rho) and thermopower (S), a characteristic of Holstein Polarons,
is observed, and ln(rho) ceases to scale with the magnetization. On approaching
T_c, both energies become field-dependent, indicating that the polarons are
magnetically polarized. Below T_c, the thermopower follows a law S(H) prop.
1/rho (H) as in non saturated ferromagnetic metals.Comment: 10 pages, 5 .gif figures. Phys. Rev B (in press
Actin-binding rho activating protein (Abra) is essential for fluid shear stress-induced arteriogenesis
OBJECTIVE: Arteriogenesis, the development of a collateral circulation, is important for tissue survival but remains functionally defective because of early normalization of fluid shear stress (FSS). Using a surgical model of chronically elevated FSS we showed that rabbits exhibited normal blood flow reserve after femoral artery ligature (FAL). Inhibition of the Rho pathway by Fasudil completely blocked the beneficial effect of FSS. In a genome-wide gene profiling we identified actin-binding Rho activating protein (Abra), which was highly upregulated in growing collaterals. METHODS AND RESULTS: qRT-PCR and Western blot confirmed highly increased FSS-dependent expression of Abra in growing collaterals. NO blockage by L-NAME abolished FSS-generated Abra expression as well as the whole arteriogenic process. Cell culture studies demonstrated an Abra-triggered proliferation of smooth muscle cells through a mechanism that requires Rho signaling. Local intracollateral adenoviral overexpression of Abra improved collateral conductance by 60% in rabbits compared to the natural response after FAL. In contrast, targeted deletion of Abra in CL57BL/6 mice led to impaired arteriogenesis. CONCLUSIONS: FSS-induced Abra expression during arteriogenesis is triggered by NO and leads to stimulation of collateral growth by smooth muscle cell proliferation
Low-temperature electrical transport and double exchange in La(Pb,Ca)MnO
The resistivity in the ferromagnetic state of flux-grown
La_{2/3}(Pb,Ca)_{1/3}MnO_3 single crystals, measured in magnetic fields up to 7
T, reveals a strong quadratic temperature dependence at and above 50 K. At
lower temperatures, this contribution drops precipitously leaving the
resistivity essentially temperature independent below 20 K. The Seebeck
coefficient also reflects a change of regime at the same temperature. We
attribute this behavior to a cut-off of single magnon scattering processes at
long wavelengths due to the polarized bands of a double-exchange ferromagnet.Comment: 10 pages, TeX, 4 figures. Revised version. Submitte
Specific heat and heat conductivity of the BaTiO3 polycrystalline films with the thickness in the range 20 - 1100 nm
Thermal properties - specific heat and heat conductivity coefficient - of
polycrystalline BaTiO3 films on massive substrates were studied as a function
of the temperature and the film thickness by ac-hot probe method. The anomalies
of specific heat with decreasing of the film thickness from 1100 to 20 nm
revealed the reducing of critical temperature (Tc) and excess entropy of the
ferroelectric phase transition, which becomes diffused. The critical thickness
of the film at which Tc = 0 estimated as 2.5 nm.Comment: 12 pages, 7 figures, 2 tables, 450kb; submitted to J.Phys.:Cond.Mat
Effect of plant sterols on the lipid profile of patients with hypercholesterolaemia. Randomised, experimental study
Extrinsic Magnetotransport Phenomena in Ferromagnetic Oxides
This review is focused on extrinsic magnetotransport effects in ferromagnetic
oxides. It consists of two parts; the second part is devoted to an overview of
experimental data and theoretical models for extrinsic magnetotransport
phenomena. Here a critical discussion of domain-wall scattering is given.
Results on surfacial and interfacial magnetism in oxides are presented.
Spin-polarized tunnelling in ferromagnetic junctions is reviewed and
grain-boundary magnetoresistance is interpreted within a model of
spin-polarized tunnelling through natural oxide barriers. The situation in
ferromagnetic oxides is compared with data and models for conventional
ferromagnets. The first part of the review summarizes basic material
properties, especially data on the spin-polarization and evidence for
half-metallicity. Furthermore, intrinsic conduction mechanisms are discussed.
An outlook on the further development of oxide spin-electronics concludes this
review.Comment: 133 pages, 47 figures, submitted to Rep. Prog. Phy
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