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1.
Entropy (Basel) ; 23(3)2021 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-33804116

RESUMO

The degradation and recovery processes are multi-scale phenomena in many physical, engineering, biological, and social systems, and determine the aging of the entire system. Therefore, understanding the interplay between the two processes at the component level is the key to evaluate the reliability of the system. Based on the principle of maximum entropy, an approach is proposed to model and infer the processes at the component level, and is applied to repairable and non-repairable systems. By incorporating the reliability block diagram, this approach allows for integrating the information of network connectivity and statistical moments to infer the hazard or recovery rates of the degradation or recovery processes. The overall approach is demonstrated with numerical examples.

2.
Phys Rev Lett ; 125(21): 210601, 2020 Nov 20.
Artigo em Inglês | MEDLINE | ID: mdl-33275022

RESUMO

The finite-time dynamics, apart from its fundamental importance in nonequilibrium thermodynamics, is of great significance in designing heat engine cycles. We build an experimental apparatus to test the predicted long-time 1/τ scaling of the irreversible entropy generation in the finite-time (τ) thermodynamic process by compressing dry air in a temperature-controlled water bath. We present the first direct experimental validation of the scaling, utilized in many finite-time thermodynamic models at the long-time regime. The experimental data also demonstrate a clear deviation from the scaling at the short-time regime. We show the optimal control scheme to minimize the irreversible entropy generation in finite-time process. Such optimization shall bring new insight to the practical design of heat engine cycles.

4.
Phys Rev E ; 101(1-1): 012106, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-32069657

RESUMO

The aging process is a common phenomenon in engineering, biological, and physical systems. The hazard rate function, which characterizes the aging process, is a fundamental quantity in the disciplines of reliability, failure, and risk analysis. However, it is difficult to determine the entire hazard function accurately with limited observation data when the degradation mechanism is not fully understood. Inspired by the seminal work pioneered by Jaynes [Phys. Rev. 106, 620 (1956)PHRVAO0031-899X10.1103/PhysRev.106.620], this study develops an approach based on the principle of maximum entropy. In particular, the time-dependent hazard rate function can be established using limited observation data in a rational manner. It is shown that the developed approach is capable of constructing and interpreting many typical hazard rate curves observed in practice, such as the bathtub curve, the upside down bathtub, and so on. The developed approach is applied to model a classical single function system and a numerical example is used to demonstrate the method. In addition its extension to a more general multifunction system is presented. Depending on the interaction between different functions of the system, two cases, namely reducible and irreducible, are discussed in detail. A multifunction electrical system is used for demonstration.

5.
Sci Rep ; 7(1): 12947, 2017 10 11.
Artigo em Inglês | MEDLINE | ID: mdl-29021626

RESUMO

ABSRACT: Symmetry degree is utilized to characterize the asymmetry of a physical system with respect to a symmetry group. The scalar form of symmetry degree (SSD) based on Frobenius-norm has been introduced recently to present a quantitative description of symmetry. Here we present the vector form of the symmetry degree (VSD) which possesses more advantages than the SSD. Mathematically, the dimension of VSD is defined as the conjugacy class number of the symmetry group, the square length of the VSD gives rise to the SSD and the direction of VSD is determined by the orders of the conjugacy classes. The merits of applying VSD both for finite and infinite symmetry groups include the additional information of broken symmetry operators with single symmetry breaking perturbation, and the capability of distinguishing distinct symmetry breaking perturbations which exactly give rise to degenerate SSD. Additionally, the VSD for physical systems under symmetry breaking perturbations can be regarded as a projection of the initial VSD without any symmetry breaking perturbations, which can be described by an evolution equation. There are the same advantages by applying VSD for the accidental degeneracy and spontaneous symmetry breaking.

6.
Sci Rep ; 6: 32010, 2016 08 25.
Artigo em Inglês | MEDLINE | ID: mdl-27558009

RESUMO

We formulate the Frobenius-norm-based measures for quantum coherence and asymmetry respectively. In contrast to the resource theory of coherence and asymmetry, we construct a natural measure of quantum coherence inspired from optical coherence theory while the group theoretical approach is employed to quantify the asymmetry of quantum states. Besides their simple structures and explicit physical meanings, we observe that these quantities are intimately related to the purity (or linear entropy) of the corresponding quantum states. Remarkably, we demonstrate that the proposed coherence quantifier is not only a measure of mixedness, but also an intrinsic (basis-independent) quantification of quantum coherence contained in quantum states, which can also be viewed as a normalized version of Brukner-Zeilinger invariant information. In our context, the asymmetry of N-qubit quantum systems is considered under local independent and collective transformations. In- triguingly, it is illustrated that the collective effect has a significant impact on the asymmetry measure, and quantum correlation between subsystems plays a non-negligible role in this circumstance.

7.
Artigo em Inglês | MEDLINE | ID: mdl-25615062

RESUMO

The canonical statistics describes the statistical properties of an open system by assuming its coupling with the heat bath is infinitesimal in comparison with the total energy in thermodynamic limit. In this paper, we generally derive a noncanonical density matrix for the open system with a finite coupling to the heat bath, which deforms the energy shell to effectively modify the conventional canonical way. The obtained noncanonical distribution reflects the back action of system on the bath and thus depicts the statistical correlations between two subsystems by the mutual information as a result of energy conservation.

8.
Sci Rep ; 3: 3144, 2013 Nov 13.
Artigo em Inglês | MEDLINE | ID: mdl-24220217

RESUMO

The scattering of a single photon with sufficiently high energy can cause a recoil of a motional scatterer. We study its backaction on the photon's coherent transport in one dimension by modeling the motional scatterer as a two-level system, which is trapped in a harmonic potential. While the reflection spectrum is of a single peak in the Lamb-Dicke limit, multi-peaks due to phonon excitations can be observed in the reflection spectrum as the trap becomes looser or the mass of the two-level system becomes smaller.

9.
Phys Rev Lett ; 111(8): 086805, 2013 Aug 23.
Artigo em Inglês | MEDLINE | ID: mdl-24010464

RESUMO

A semiconductor nanowire quantum dot with strong spin-orbit coupling (SOC) can be used to achieve a spin-orbit qubit. In contrast to a spin qubit, the spin-orbit qubit can respond to an external ac electric field, an effect called electric-dipole spin resonance. Here we develop a theory that can apply in the strong SOC regime. We find that there is an optimal SOC strength η(opt)=√2/2, where the Rabi frequency induced by the ac electric field becomes maximal. Also, we show that both the level spacing and the Rabi frequency of the spin-orbit qubit have periodic responses to the direction of the external static magnetic field. These responses can be used to determine the SOC in the nanowire.

10.
Phys Rev Lett ; 110(4): 045301, 2013 Jan 25.
Artigo em Inglês | MEDLINE | ID: mdl-25166174

RESUMO

The superfluid phases in resonant dipolar Fermi gases are investigated by the standard mean-field theory. In contrast to the crossover from Bose-Einstein condensation (BEC) to Bardeen-Cooper-Schrieffer superfluid in Fermi gases with isotropic interactions, resonant dipolar interaction leads to two completely different BEC phases of the tight-binding Fermi molecules on both sides of the resonance, which are characterized by two order parameters with distinct internal symmetries. We point out that, near the resonances, the two competitive phases can coexist, and an emergent relative phase between the two order parameters spontaneously breaks time-reversal symmetry, which could be observed in momentum resolved rf spectroscopy.

11.
Phys Rev Lett ; 111(10): 103604, 2013 Sep 06.
Artigo em Inglês | MEDLINE | ID: mdl-25166667

RESUMO

We propose an experimentally accessible single-photon routing scheme using a △-type three-level atom embedded in quantum multichannels composed of coupled-resonator waveguides. Via the on-demand classical field being applied to the atom, the router can extract a single photon from the incident channel, and then redirect it into another. The efficient function of the perfect reflection of the single-photon signal in the incident channel is rooted in the coherent resonance and the existence of photonic bound states.

12.
Phys Rev Lett ; 108(12): 125301, 2012 Mar 23.
Artigo em Inglês | MEDLINE | ID: mdl-22540595

RESUMO

We propose an experimental scheme to create spin-orbit coupling in spin-3 Cr atoms using Raman processes. By employing the linear Zeeman effect and optical Stark shift, two spin states within the ground electronic manifold are selected, which results in a pseudospin-1/2 model. We further study the ground state structures of a spin-orbit-coupled Cr condensate. We show that, in addition to the stripe structures induced by the spin-orbit coupling, the magnetic dipole-dipole interaction gives rise to the vortex phase, in which a spontaneous spin vortex is formed.

13.
Phys Rev E Stat Nonlin Soft Matter Phys ; 85(3 Pt 1): 031114, 2012 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-22587045

RESUMO

We present a complete-quantum description of a multiparticle Szilard engine that consists of a working substance and a Maxwell's demon. The demon is modeled as a multilevel quantum system with specific quantum control, and the working substance consists of identical particles obeying Bose-Einstein or Fermi-Dirac statistics. In this description, a reversible scheme to erase the demon's memory by a lower-temperature heat bath is used. We demonstrate that (1) the quantum control of the demon can be optimized for a single-particle Szilard engine so that the efficiency of the demon-assisted thermodynamic cycle could reach the Carnot cycle's efficiency and (2) the low-temperature behavior of the working substance is very sensitive to the quantum statistics of the particles and the insertion position of the partition.


Assuntos
Coloides/química , Temperatura Alta , Modelos Químicos , Modelos Moleculares , Teoria Quântica , Simulação por Computador , Transferência de Energia , Termodinâmica
14.
Gene Ther ; 19(1): 25-33, 2012 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-21562593

RESUMO

Chronic hepatitis B virus (HBV) infection is closely related to the development of severe liver complications, including hepatocellular carcinoma. In previous studies, we reported that in vivo long-term HBV suppression in transgenic mice can be achieved without apparent toxicity by short hairpin RNA sequentially delivered using adeno-associated viral (AAV) vectors of different serotypes. Our goal herein was to address the clinical utility of this delivery system and, in particular, to determine whether RNA interference (RNAi) and its ability to induce long-term HBV suppression will modulate the development of HBV-associated liver pathology. As a model system, we used a unique HBV transgenic mouse model, containing a 1.3 times over length of the HBV genome, on the ICR mouse background. These transgenic mice produce high serum HBV titers comparable with human chronic HBV patients, and, importantly, manifest characteristic HBV-associated pathology, including progressive hepatocellular injury and the development of hepatocellular adenoma. Using this system, we injected animals with AAV vectors expressing either HBV-specific or a control luciferase-specific short hairpin RNA and followed animals for a total of 18 months. We report herein that AAV-mediated RNAi therapy profoundly inhibits HBV replication and gene expression, with a significant reduction in hepatic regeneration, liver enzymes and, importantly, the appearance of liver adenomas. Indeed, the therapeutic effect of RNAi correlated with the reduction in HBV titers. Our data demonstrate that appropriately designed RNAi therapy has the potential to prevent formation of HBV-associated hepatocellular adenoma.


Assuntos
Adenoma de Células Hepáticas/terapia , Regulação Viral da Expressão Gênica , Vírus da Hepatite B/patogenicidade , Neoplasias Hepáticas/terapia , Interferência de RNA , RNA Viral/genética , Adenoma de Células Hepáticas/sangue , Adenoma de Células Hepáticas/patologia , Adenoma de Células Hepáticas/virologia , Animais , Northern Blotting , Dependovirus/genética , Dependovirus/metabolismo , Feminino , Técnicas de Transferência de Genes , Antígenos de Superfície da Hepatite B/análise , Antígenos de Superfície da Hepatite B/sangue , Vírus da Hepatite B/genética , Vírus da Hepatite B/fisiologia , Hepatite B Crônica/sangue , Hepatite B Crônica/patologia , Hepatite B Crônica/terapia , Hepatite B Crônica/virologia , Hepatócitos/citologia , Hepatócitos/metabolismo , Hepatócitos/virologia , Humanos , Neoplasias Hepáticas/sangue , Neoplasias Hepáticas/patologia , Neoplasias Hepáticas/virologia , Neoplasias Hepáticas Experimentais , Luciferases/genética , Luciferases/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos ICR , Camundongos Transgênicos , RNA Interferente Pequeno/genética , RNA Interferente Pequeno/metabolismo , RNA Viral/metabolismo , Transgenes , Carga Viral , Replicação Viral
15.
J Endocrinol Invest ; 35(3): 312-6, 2012 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-21646859

RESUMO

Thyroid hormone insufficiency in adulthood causes a wide range of brain impairments, including altered synaptic proteins in the prefrontal cortex (PFC). The present study investigated whether adult-onset hypothyroidism altered the expression of soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) complexes and synaptotagmin-1 (syt-1) in the PFC of rats. Sprague-Dawley rats were randomly divided into 4 groups: control, hypothyroid, and hypothyroid treated with T(4) [5 or 20 µg/100 g body weight (BW)]. Adult-onset hypothyroidism was induced in rats with the antithyroid drug 6-n-propyl-2-thiouracil (ip injection). PFC levels of synaptosomal-associated protein of 25 kDa (SNAP-25), syntaxin-1, vesicle-associated membrane protein 2 (VAMP-2) and syt-1 were determined by immunohistochemistry and western blot analyses. The results showed that syntaxin-1 and syt-1 were expressed at significantly lower levels in hypothyroid rats, VAMP-2 levels were not altered, and SNAP-25 levels were much higher compared to controls. A 2-week treatment with 5 µg T(4)/100 g BW partially normalized levels of SNARE complex and syt-1, and 20 µg T(4)/100 g BW restored these proteins closer to normal levels. Our findings indicate that dysregulation of SNARE complex and syt-1 in PFC of adult-onset hypothyroidism can be restored by T(4) treatment.


Assuntos
Encefalopatias Metabólicas/metabolismo , Hipotireoidismo/metabolismo , Córtex Pré-Frontal/metabolismo , Proteínas SNARE/metabolismo , Sinaptotagmina I/metabolismo , Tiroxina/metabolismo , Animais , Encefalopatias Metabólicas/tratamento farmacológico , Encefalopatias Metabólicas/etiologia , Hipotireoidismo/complicações , Hipotireoidismo/tratamento farmacológico , Masculino , Córtex Pré-Frontal/efeitos dos fármacos , Ratos , Ratos Sprague-Dawley , Proteína 25 Associada a Sinaptossoma/metabolismo , Sintaxina 1/metabolismo , Tiroxina/sangue , Tiroxina/farmacologia , Tri-Iodotironina/sangue , Proteína 2 Associada à Membrana da Vesícula/metabolismo
16.
Phys Rev E Stat Nonlin Soft Matter Phys ; 83(6 Pt 1): 061108, 2011 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-21797303

RESUMO

We study the physical mechanism of Maxwell's demon (MD), which helps do extra work in thermodynamic cycles with the heat engine. This is exemplified with one molecule confined in an infinitely deep square potential with a movable solid wall. The MD is modeled as a two-level system (TLS) for measuring and controlling the motion of the molecule. The processes in the cycle are described in a quantum fashion. It is discovered that a MD with quantum coherence or one at a temperature lower than the molecule's heat bath can enhance the ability of the whole working substance, formed by the heat engine plus the MD, to do work outside. This observation reveals that the essential role of the MD is to drive the whole working substance off equilibrium, or equivalently, to work between two heat baths with different effective temperatures. The elaborate studies with this model explicitly reveal the effect of finite size off the classical limit or thermodynamic limit, which contradicts common sense on a Szilard heat engine (SHE). The quantum SHE's efficiency is evaluated in detail to prove the validity of the second law of thermodynamics.

17.
J Chem Phys ; 132(23): 234501, 2010 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-20572715

RESUMO

We study the role of the dimer structure of light-harvesting complex II (LH2) in excitation transfer from the LH2 [without a reaction center (RC)] to the LH1 (surrounding the RC) or from the LH2 to another LH2. The excited and unexcited states of a bacteriochlorophyll (BChl) are modeled by a quasispin. In the framework of quantum open system theory, we represent the excitation transfer as the total leakage of the LH2 system and then calculate the transfer efficiency and average transfer time. For different initial states with various quantum superposition properties, we study how the dimerization of the B850 BChl ring can enhance the transfer efficiency and shorten the average transfer time.

18.
Poult Sci ; 89(5): 887-94, 2010 May.
Artigo em Inglês | MEDLINE | ID: mdl-20371839

RESUMO

This study determined the caponization effects on the immune responses in male chicks. Different forms of exogenous androgen implantation on male chick immunity were compared. Healthy, uniform male Single Comb White Leghorn chicks were caponized at 3 wk of age. Birds were housed in individual cages (35 x 30 x 40 cm, length x width x height). Each of 27 sham-operated (sham) and caponized (capon) male chickens were used for trial 1. Trial 2 used 60 capons divided into 4 treatments with implants of either 1 mm i.d. x 3 mm o.d. 58 mg of cholesterol, testosterone (TES), 5alpha-dihydrotestosterone (5alpha-DHT), or 19-nortestosterone (19-NorT). The exogenous androgen was implanted immediately after caponization and resupplied every 4 wk for an entire 13-wk feeding trial. The results from trial 1 showed that the relative bursa weight increased compared with the sham treatment (P < 0.05). The 2 wk post-Newcastle disease virus titer and the delayed-type hypersensitivity (DTH) of 48 h post-phytohemagglutinin phosphate (PHA-P) injection were increased compared with the sham treatment (P < 0.05). In trial 2, implanted 5alpha-DHT and 19-NorT could decrease the relative bursa weight in capons (P < 0.05). The 2 wk post-Newcastle disease virus titer in the 5alpha-DHT group was higher than that in the cholesterol group (P < 0.05). The 19-NorT group had the highest (P < 0.05) PHA-P response. Peripheral blood lymphocyte subset population analysis revealed that the percentage of CD4 T cells in the TES group was lower (P < 0.05) compared with that of the 5alpha-DHT group. Differently, the percentage of CD8 T cells in the TES and 19-NorT groups was higher (P < 0.05) than that in the 5alpha-DHT group. Male chicks that were caponized had increased bursa weight and PHA-P response, whereas different forms of exogenous androgen implantation reverted the phenomena in an order of potency of 5alpha-DHT and 19-NorT > TES, and the PHA-P response was TES > 5alpha-DHT >19-NorT.


Assuntos
Androgênios/farmacologia , Galinhas/imunologia , Androgênios/administração & dosagem , Animais , Bolsa de Fabricius/anatomia & histologia , Bolsa de Fabricius/efeitos dos fármacos , Colesterol/administração & dosagem , Colesterol/farmacologia , Crista e Barbelas/anatomia & histologia , Crista e Barbelas/efeitos dos fármacos , Masculino , Nandrolona/administração & dosagem , Nandrolona/farmacologia , Baço/anatomia & histologia , Baço/efeitos dos fármacos , Baço/imunologia , Esterilização Reprodutiva/veterinária , Testosterona/administração & dosagem , Testosterona/farmacologia , Timo/anatomia & histologia , Timo/efeitos dos fármacos , Timo/imunologia
19.
Phys Rev E Stat Nonlin Soft Matter Phys ; 82(4 Pt 1): 041127, 2010 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-21230258

RESUMO

It is typically assumed, without justification, that a weak coupling between a system and a bath is a necessary condition for the equivalence of a canonical ensemble and a microcanonical ensemble. For instance, in a canonical ensemble, temperature emerges if the system and the bath are uncoupled or weakly coupled. We investigate the validity region of this weak-coupling approximation, using a coupled composite-spin system. Our results show that the spin coupling strength can be as large as the level spacing of the system, indicating that the weak-coupling approximation has a much wider region of validity than usually expected.

20.
Phys Rev E Stat Nonlin Soft Matter Phys ; 79(1 Pt 2): 016606, 2009 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-19257159

RESUMO

We study the nonlinear dynamics of collective excitation in an N -site XXZ quantum spin chain, which is manipulated by an oblique magnetic field. We show that, when the tilted field is applied along the magic angle, theta_{0}=+/-arccossqrt[13] , the anisotropic Heisenberg spin chain becomes isotropic and thus an freely propagating spin wave is stimulated. Also, in the regime of tilted angles larger and smaller than the magic angle, two types of nonlinear excitations appear: bright and dark solitons.

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