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1
MALEKJANI, M., e A. KHODAM-MOHAMMADI. "NEW HOLOGRAPHIC CHAPLYGIN GAS MODEL OF DARK ENERGY". International Journal of Modern Physics D 20, n. 03 (marzo 2011): 281–97. http://dx.doi.org/10.1142/s0218271811018779.
Testo completoAbstract (sommario):
In this work, we investigate the holographic dark energy model with a new infrared cutoff (new HDE model), proposed by Granda and Oliveros. Using this new definition for the infrared cutoff, we establish the correspondence between the new HDE model and the standard Chaplygin gas (SCG), generalized Chaplygin gas (GCG) and modified Chaplygin gas (MCG) scalar field models in a nonflat universe. The potential and dynamics for these scalar field models, which describe the accelerated expansion of the universe, are reconstructed. According to the evolutionary behavior of the new HDE model, we derive the same form of dynamics and potential for the different SCG, GCG and MCG models. We also calculate the squared sound speed of the new HDE model as well as the SCG, GCG and MCG models, and investigate the new HDE Chaplygin gas models from the viewpoint of linear perturbation theory. In addition, all results in the nonflat universe are discussed in the limiting case of the flat universe, i.e. k = 0.
2
Na, Chun-Soo, Sun Young Yoon, Jin Beom Kim, Dae-Seung Na, Mi-Sook Dong, Moo-Yeol Lee e Cheol Yi Hong. "Anti-fatigue Activity of Hovenia dulcis on a Swimming Mouse Model through the Inhibition of Stress Hormone Expression and Antioxidation". American Journal of Chinese Medicine 41, n. 04 (gennaio 2013): 945–55. http://dx.doi.org/10.1142/s0192415x13500638.
Testo completoAbstract (sommario):
Hovenia dulcis (H. dulcis) Thunb., which is distributed in Korea, China, and Japan, has been known to show hepatoprotective and free radical scavenging effects and enhance physical activity. Therefore, the objectives of this present study were to determine the anti-fatigue activity of hot-water extract from H. dulcis peduncle, and to find the reason why H. dulcis extract (HDE)-ingested mice had enhanced physical activity against swimming performance. The mice orally administrated with HDE (HDE-mice) dramatically enhanced their swimming time compared to the control mice. HDE significantly decreased serum levels of stress hormones, such as cortisol and adrenocorticotropic hormone (ACTH) in mice. The levels of thiobarbituric acid reactive substances (TBARS) were dramatically decreased in gastrocnemius muscle from both 100 mg/kg of HDE (LHDE) and 200 mg/kg of HDE (HHDE)-ingested mice compared to the control mice. The liver activities of superoxide dismutase (SOD) were significantly increased in HHDE-mice with increasing tendency in LHDE-mice. In addition, HHDE-mice significantly decreased the levels of blood glucose, total cholesterol (T-Chol), and triglyceride (TG). These results suggest that HDE had a significant anti-fatigue effect via its anti-stress and antioxidant activities, and thereby enhanced physical activity in swimming performance.
3
ZHANG, ZHENHUI, MIAO LI, XIAO-DONG LI, SHUANG WANG e WEN-SHUAI ZHANG. "GENERALIZED HOLOGRAPHIC DARK ENERGY AND ITS OBSERVATIONAL CONSTRAINTS". Modern Physics Letters A 27, n. 20 (28 giugno 2012): 1250115. http://dx.doi.org/10.1142/s0217732312501155.
Testo completoAbstract (sommario):
In the original holographic dark energy (HDE) model, the dark energy density is proposed to be [Formula: see text], with c a dimensionless constant characterizing the properties of the HDE. In this work, we propose the generalized holographic dark energy (GHDE) model by considering the parameter c as a redshift-dependent function c(z). We derive all the physical quantities of the GHDE model analytically, and fit the c(z) by trying four kinds of parametrizations. The cosmological constraints of the c(z) are obtained from the joint analysis of the present SNLS3+BAO+CMB +H0data. We find that, compared with the original HDE model, the GHDE models can provide a better fit to the data. For example, the GHDE model with JBP-type c(z) can reduce the [Formula: see text] of the HDE model by 2.16. We also find that, unlike the original HDE model with a phantom-like behavior in the future, the GHDE models can present many more different possibilities, i.e. it allows the GHDE in the future to be either quintessence-like, cosmological constant-like, or phantom-like, depending on the forms of c(z).
4
Romberger, Debra J., Art J. Heires, Tara M. Nordgren, Chelsea P. Souder, William West, Xiang-de Liu, Jill A. Poole, Myron L. Toews e Todd A. Wyatt. "Proteases in agricultural dust induce lung inflammation through PAR-1 and PAR-2 activation". American Journal of Physiology-Lung Cellular and Molecular Physiology 309, n. 4 (15 agosto 2015): L388—L399. http://dx.doi.org/10.1152/ajplung.00025.2015.
Testo completoAbstract (sommario):
Workers exposed to aerosolized dust present in concentrated animal feeding operations (CAFOs) are susceptible to inflammatory lung diseases, such as chronic obstructive pulmonary disease. Extracts of dust collected from hog CAFOs [hog dust extract (HDE)] are potent stimulators of lung inflammatory responses in several model systems. The observation that HDE contains active proteases prompted the present study, which evaluated the role of CAFO dust proteases in lung inflammatory processes and tested whether protease-activated receptors (PARs) are involved in the signaling pathway for these events. We hypothesized that the damaging proinflammatory effect of HDE is due, in part, to the proteolytic activation of PARs, and inhibiting the proteases in HDE or disrupting PAR activation would attenuate HDE-mediated inflammatory indexes in bronchial epithelial cells (BECs), in mouse lung slices in vitro, and in a murine in vivo exposure model. Human BECs and mouse lung slice cultures stimulated with 5% HDE released significantly more of each of the cytokines measured (IL-6, IL-8, TNF-α, keratinocyte-derived chemokine/CXC chemokine ligand 1, and macrophage inflammatory protein-2/CXC chemokine ligand 2) than controls, and these effects were markedly diminished by protease inhibition. Inhibition of PARs also blunted the HDE-induced cytokine release from BECs. In addition, protease depletion inhibited HDE-induced BEC intracellular PKCα and PKCε activation. C57BL/6J mice administered 12.5% HDE intranasally, either once or daily for 3 wk, exhibited increased total cellular and neutrophil influx, bronchial alveolar fluid inflammatory cytokines, lung histopathology, and inflammatory scores compared with mice receiving protease-depleted HDE. These data suggest that proteases in dust from CAFOs are important mediators of lung inflammation, and these proteases and their receptors may provide novel targets for therapeutic intervention in CAFO dust-induced airways disease.
5
Romberger, Debra J., Art J. Heires, Tara M. Nordgren, Jill A. Poole, Myron L. Toews, William W. West e Todd A. Wyatt. "β2-Adrenergic agonists attenuate organic dust-induced lung inflammation". American Journal of Physiology-Lung Cellular and Molecular Physiology 311, n. 1 (1 luglio 2016): L101—L110. http://dx.doi.org/10.1152/ajplung.00125.2016.
Testo completoAbstract (sommario):
Agricultural dust exposure results in significant lung inflammation, and individuals working in concentrated animal feeding operations (CAFOs) are at risk for chronic airway inflammatory diseases. Exposure of bronchial epithelial cells to aqueous extracts of hog CAFO dusts (HDE) leads to inflammatory cytokine production that is driven by protein kinase C (PKC) activation. cAMP-dependent protein kinase (PKA)-activating agents can inhibit PKC activation in epithelial cells, leading to reduced inflammatory cytokine production following HDE exposure. β2-Adrenergic receptor agonists (β2-agonists) activate PKA, and we hypothesized that β2-agonists would beneficially impact HDE-induced adverse airway inflammatory consequences. Bronchial epithelial cells were cultured with the short-acting β2-agonist salbutamol or the long-acting β2-agonist salmeterol prior to stimulation with HDE. β2-Agonist treatment significantly increased PKA activation and significantly decreased HDE-stimulated IL-6 and IL-8 production in a concentration- and time-dependent manner. Salbutamol treatment significantly reduced HDE-induced intracellular adhesion molecule-1 expression and neutrophil adhesion to epithelial cells. Using an established intranasal inhalation exposure model, we found that salbutamol pretreatment reduced airway neutrophil influx and IL-6, TNF-α, CXCL1, and CXCL2 release in bronchoalveolar lavage fluid following a one-time exposure to HDE. Likewise, when mice were pretreated daily with salbutamol prior to HDE exposure for 3 wk, HDE-induced neutrophil influx and inflammatory mediator production were also reduced. The severity of HDE-induced lung pathology in mice repetitively exposed to HDE for 3 wk was also decreased with daily salbutamol pretreatment. Together, these results support the need for future clinical investigations to evaluate the utility of β2-agonist therapies in the treatment of airway inflammation associated with CAFO dust exposure.
6
Qiang, Zou, Liao Li e Qin Hui. "Flood disaster evaluation based on adaptive fuzzy clustering iterative model and hybrid differential evolution algorithm". Water Supply 19, n. 6 (25 febbraio 2019): 1619–29. http://dx.doi.org/10.2166/ws.2019.034.
Testo completoAbstract (sommario):
Abstract In order to reasonably and rapidly evaluate flood disaster, based on a fuzzy clustering iterative model (FCI) and differential evolution algorithm (DE), an adaptive fuzzy clustering iterative model using a hybrid differential evolution algorithm (AFCI-HDE) is proposed, which has three advantages: firstly, the decision-maker's subjective preference was considered to flexibly modify the objective function; secondly, HDE was introduced to optimize the index weight vector of AFCI; thirdly, the validity of its clustering effect was more credible than that of FCI. Finally, the case study revealed that AFCI-HDE is feasible and effective by comparing the optimal fitness and clustering validity values with other approaches, which could reflect various decision-maker's preferences by simple adaptive adjustments and rapidly obtain reasonable evaluation results, thus providing a new effective approach in flood risk management.
7
Khodam-Mohammadi, A., E. Karimkhani e A. Sheykhi. "Best values of parameters for interacting HDE with GO IR-cutoff in Brans–Dicke cosmology". International Journal of Modern Physics D 23, n. 10 (settembre 2014): 1450081. http://dx.doi.org/10.1142/s0218271814500813.
Testo completoAbstract (sommario):
We investigate the interacting holographic dark energy (HDE) with Granda–Oliveros (GO) infrared (IR)-cutoff in the framework of Brans–Dicke (BD) cosmology. We obtain the equation of state (EoS) parameter of HDE, wD, the effective EoS parameter w eff , the deceleration parameter q and the squared of sound speed [Formula: see text] in a flat Friedmann–Robertson–Walker (FRW) universe. We show that at late-time the cosmic coincidence problem can be alleviated. Also we show that for noninteracting case, HDE can give a unified dark matter–dark energy (DM–DE) profile in BD cosmology, except that it cannot solve the coincidence problem in the future. By studying the EoS parameter, we see that the phantom divide may be crossed. Using the latest observational data, we calculate the best values of the parameters for interacting HDE in BD framework. Computing the deceleration parameter implies that the transition from deceleration to the acceleration phase occurred for redshift z ≥ 0.5. Finally, we investigate the sound stability of the model, and find that HDE with Granda–Oliveros (GO)-cutoff in the framework of BD cosmology can lead to a stable DE-dominated universe favored by observations, provided we take β = 0.44 and b2 < 0.35. This is in contrast to HDE model in Einstein gravity which does not lead to a stable DE-dominated universe.
8
Sheykhi, A., M. H. Dehghani e S. Ghaffari. "New holographic dark energy model inspired by the DGP braneworld". International Journal of Modern Physics D 25, n. 02 (febbraio 2016): 1650018. http://dx.doi.org/10.1142/s0218271816500188.
Testo completoAbstract (sommario):
The energy density of the holographic dark energy (HDE) is based on the area law of entropy, and thus any modification of the area law leads to a modified holographic energy density. Inspired by the entropy expression associated with the apparent horizon of a Friedmann–Robertson–Walker (FRW) universe in DGP braneworld, we propose a new model for the HDE in the framework of DGP brane cosmology. We investigate the cosmological consequences of this new model and calculate the equation of state (EoS) parameter by choosing the Hubble radius, [Formula: see text], as the system’s IR cutoff. Our study show that, due to the effects of the extra dimension (bulk), the identification of IR cutoff with Hubble radius, can reproduce the present acceleration of the universe expansion. This is in contrast to the ordinary HDE in standard cosmology which leads to the zero EoS parameter in the case of choosing the Hubble radius as system’s IR cutoff in the absence of interaction between dark matter (DM) and dark energy (DE).
9
Sheykhi, A., M. Tavayef e H. Moradpour. "Revisiting holographic dark energy in cyclic cosmology". Canadian Journal of Physics 96, n. 9 (settembre 2018): 1034–41. http://dx.doi.org/10.1139/cjp-2017-0434.
Testo completoAbstract (sommario):
Considering the holographic dark energy (HDE) with two different infrared (IR) cutoffs, we study the evolution of a cyclic universe, which avoids the Big-Rip singularity. Our results show that, even in the absence of a mutual interaction between the cosmos sectors, the HDE model with the Hubble radius as IR cutoff can mimic a cosmological constant in the framework of a cyclic cosmology. In addition, we find that both the interacting and non-interacting universes may enter into a cycle of sequential contraction and expansion, if the Granda–Oliveros cutoff is chosen as the IR cutoff in the energy density of the HDE. We also investigate the instability of the model against perturbations and find the ranges of the parameters in which the model is stable.
10
Chakraborty, Gargee, Surajit Chattopadhyay, Ertan Güdekli e Irina Radinschi. "Thermodynamics of Barrow Holographic Dark Energy with Specific Cut-Off". Symmetry 13, n. 4 (29 marzo 2021): 562. http://dx.doi.org/10.3390/sym13040562.
Testo completoAbstract (sommario):
Motivated by the work of Saridakis (Phys. Rev. D102, 123525 (2020)), the present study reports the cosmological consequences of Barrow holographic dark energy (HDE) and its thermodynamics. The literature demonstrates that dark energy (DE) may result from electroweak symmetry breaking that triggers a phase transition from early inflation to late-time acceleration. In the present study, we incorporated viscosity in the Barrow HDE. A reconstruction scheme is presented for the parameters associated with Barrow holographic dark energy under the purview of viscous cosmology. The equation of state (EoS) parameter is reconstructed in this scenario and quintessence behaviour is observed. Considering Barrow HDE as a specific case of Nojiri–Odintsov (NO) HDE, we have observed quintom behaviour of the EoS parameter and for some values of n the EoS has been observed to be very close to −1 for the current universe. The generalised second law of thermodynamics has come out to be valid in all the scenarios under consideration. Physical viability of considering Barrow HDE as a specific case of NO HDE is demonstrated in this study. Finally, it has been observed that the model under consideration is very close to ΛCDM and cannot go beyond it.
11
Nojiri, Shin’ichi, Sergei D. Odintsov e Tanmoy Paul. "Different Faces of Generalized Holographic Dark Energy". Symmetry 13, n. 6 (23 maggio 2021): 928. http://dx.doi.org/10.3390/sym13060928.
Testo completoAbstract (sommario):
In the formalism of generalized holographic dark energy (HDE), the holographic cut-off is generalized to depend upon LIR=LIRLp,L˙p,L¨p,⋯,Lf,L˙f,⋯,a with Lp and Lf being the particle horizon and the future horizon, respectively (moreover, a is the scale factor of the Universe). Based on such formalism, in the present paper, we show that a wide class of dark energy (DE) models can be regarded as different candidates for the generalized HDE family, with respective cut-offs. This can be thought as a symmetry between the generalized HDE and different DE models. In this regard, we considered several entropic dark energy models—such as the Tsallis entropic DE, the Rényi entropic DE, and the Sharma–Mittal entropic DE—and found that they are indeed equivalent with the generalized HDE. Such equivalence between the entropic DE and the generalized HDE is extended to the scenario where the respective exponents of the entropy functions are allowed to vary with the expansion of the Universe. Besides the entropic DE models, the correspondence with the generalized HDE was also established for the quintessence and for the Ricci DE model. In all the above cases, the effective equation of state (EoS) parameter corresponding to the holographic energy density was determined, by which the equivalence of various DE models with the respective generalized HDE models was further confirmed. The equivalent holographic cut-offs were determined by two ways: (1) in terms of the particle horizon and its derivatives, (2) in terms of the future horizon horizon and its derivatives.
12
Sheykhi, Ahmad, e Maral Sahebi Hamedan. "Holographic Dark Energy in Modified Barrow Cosmology". Entropy 25, n. 4 (26 marzo 2023): 569. http://dx.doi.org/10.3390/e25040569.
Testo completoAbstract (sommario):
Thermodynamics–gravity conjecture implies that there is a deep connection between the gravitational field equations and the first law of thermodynamics. Therefore, any modification to the entropy expression directly modifies the field equations. By considering the modified Barrow entropy associated with the apparent horizon, the Friedmann equations are modified as well. In this paper, we reconsider the holographic dark energy (HDE) model when the entropy is in the form of Barrow entropy. This modification to the entropy not only changes the energy density of the HDE but also modifies the Friedmann equations. Therefore, one should take into account the modified HDE in the context of modified Friedmann equations. We study the Hubble horizon and the future event horizon as IR cutoffs and investigate the cosmological consequences of this model. We also extend our study to the case where dark matter (DM) and dark energy (DE) interact with each other. We observe that Barrow exponent δ significantly affects the cosmological behavior of HDE, and in particular, the equation of state (EoS) parameter can cross the phantom line (wde<−1). Additionally, adding δ remarkably affects the deceleration parameter and shifts the time of universe phase transition.
13
Dominguez, Edward C., Rattapol Phandthong, Matthew Nguyen, Arzu Ulu, Stephanie Guardado, Stefanie Sveiven, Prue Talbot e Tara M. Nordgren. "Aspirin-Triggered Resolvin D1 Reduces Chronic Dust-Induced Lung Pathology without Altering Susceptibility to Dust-Enhanced Carcinogenesis". Cancers 14, n. 8 (9 aprile 2022): 1900. http://dx.doi.org/10.3390/cancers14081900.
Testo completoAbstract (sommario):
Lung cancer is the leading cause of cancer-related deaths worldwide, with increased risk being associated with unresolved or chronic inflammation. Agricultural and livestock workers endure significant exposure to agricultural dusts on a routine basis; however, the chronic inflammatory and carcinogenic effects of these dust exposure is unclear. We have developed a chronic dust exposure model of lung carcinogenesis in which mice were intranasally challenged three times a week for 24 weeks, using an aqueous dust extract (HDE) made from dust collected in swine confinement facilities. We also treated mice with the omega-3-fatty acid lipid mediator, aspirin-triggered resolvin D1 (AT-RvD1) to provide a novel therapeutic strategy for mitigating the inflammatory and carcinogenic effects of HDE. Exposure to HDE resulted in significant immune cell influx into the lungs, enhanced lung tumorigenesis, severe tissue pathogenesis, and a pro-inflammatory and carcinogenic gene signature, relative to saline-exposed mice. AT-RvD1 treatment mitigated the dust-induced inflammatory response but did not protect against HDE + NNK-enhanced tumorigenesis. Our data suggest that chronic HDE exposure induces a significant inflammatory and pro-carcinogenic response, whereas treatment with AT-RvD1 dampens the inflammatory responses, providing a strong argument for the therapeutic use of AT-RvD1 to mitigate chronic inflammation.
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Pradhan, Anirudh, Archana Dixit e Vinod Kumar Bhardwaj. "Barrow HDE model for statefinder diagnostic in FLRW universe". International Journal of Modern Physics A 36, n. 04 (10 febbraio 2021): 2150030. http://dx.doi.org/10.1142/s0217751x21500305.
Testo completoAbstract (sommario):
We have analyzed the Barrow holographic dark energy (BHDE) in the framework of flat FLRW universe by considering the various estimations of Barrow exponent △. Here, we define BHDE, by applying the usual holographic principle at a cosmological system, for utilizing the Barrow entropy rather than the standard Bekenstein–Hawking. To understand the recent accelerated expansion of the universe, consider the Hubble horizon as the IR cutoff. The cosmological parameters, especially the density parameter [Formula: see text], the equation of the state parameter [Formula: see text], energy density [Formula: see text] and the deceleration parameter [Formula: see text] are studied in this paper and found the satisfactory behaviors. Moreover we additionally focus on the two geometric diagnostics, the statefinder [Formula: see text] and [Formula: see text] to discriminant BHDE model from the [Formula: see text]CDM model. Here we determined and plotted the trajectories of evolution for statefinder [Formula: see text], [Formula: see text] and [Formula: see text] diagnostic plane to understand the geometrical behavior of the BHDE model by utilizing Planck 2018 observational information. Finally, we have explored the new Barrow exponent △, which strongly affects the dark energy equation of state that can lead it to lie in the quintessence regime, phantom regime and exhibits the phantom-divide line during the cosmological evolution.
15
Moran, Timothy P., Keiko Nakano, Gregory S. Whitehead, Seddon Y. Thomas, Donald N. Cook e Hideki Nakano. "Inhaled house dust programs pulmonary dendritic cells to promote type 2 T-cell responses by an indirect mechanism". American Journal of Physiology-Lung Cellular and Molecular Physiology 309, n. 10 (15 novembre 2015): L1208—L1218. http://dx.doi.org/10.1152/ajplung.00256.2015.
Testo completoAbstract (sommario):
The induction of allergen-specific T helper 2 (Th2) cells by lung dendritic cells (DCs) is a critical step in allergic asthma development. Airway delivery of purified allergens or microbial products can promote Th2 priming by lung DCs, but how environmentally relevant quantities and combinations of these factors affect lung DC function is unclear. Here, we investigated the ability of house dust extract (HDE), which contains a mixture of environmental adjuvants, to prime Th2 responses against an innocuous inhaled antigen. Inhalational exposure to HDE conditioned lung conventional DCs, but not monocyte-derived DCs, to induce antigen-specific Th2 differentiation. Conditioning of DCs by HDE was independent of Toll-like receptor 4 signaling, indicating that environmental endotoxin is dispensable for programming DCs to induce Th2 responses. DCs directly treated with HDE underwent maturation but were poor stimulators of Th2 differentiation. In contrast, DCs treated with bronchoalveolar lavage fluid (BALF) from HDE-exposed mice induced robust Th2 differentiation. DC conditioning by BALF was independent of the proallergic cytokines IL-25, IL-33, and thymic stromal lymphopoietin. BALF treatment of DCs resulted in upregulation of CD80 but low expression of CD40, CD86, and IL-12p40, which was associated with Th2 induction. These findings support a model whereby environmental adjuvants in house dust indirectly program DCs to prime Th2 responses by triggering the release of endogenous soluble factor(s) by airway cells. Identifying these factors could lead to novel therapeutic targets for allergic asthma.
16
Lindsay, CD, e DG Upshall. "The generation of a human dermal equivalent to assess the potential contribution of human dermal fibroblasts to the sulphur mustard-induced vesication response". Human & Experimental Toxicology 14, n. 7 (luglio 1995): 580–86. http://dx.doi.org/10.1177/096032719501400705.
Testo completoAbstract (sommario):
1 A human dermal equivalent (HDE) gel was constructed from rat tail tendon collagen (type 1) and human dermal fibroblasts (HFs). Histological studies revealed that the HFs within the HDE gel matrix assumed the shape of differentiated dermal fibroblasts and were metabolically viable as determined by the MTT assay. 2 The HDE system was developed to determine if viable, differentiated HFs have the potential to contribute to tis sue damage by releasing the proteolytic enzyme elastase following exposure to sulphur mustard (HD). Elastase was measured, using the substrate suc-ala-ala-val-p- nitroanilide (SAAVNA), because of its association with various human pathological bullous skin diseases. An additional elastase substrate (suc-ala-ala-ala-p- nitroanilide ; SAAANA) was also used. A miniaturised assay was employed to measure lactate dehydrogenase (LDH), a cytosolic enzyme released following damage to the cell membrane. 3 Elastase levels (measured with SAAVNA) increased to over 740% of those in control culture medium at 24 h after exposure of the HDE to HD (2 mM) and may there fore be part of the mechanism associated with dermo- epidermal separation and blistering in humans follow ing exposure of skin to HD. LDH was released from the HDE after exposure to HD in a time dependent fashion, suggesting a steady leakage of cytosolic constituents after the initial exposure. 4 The results suggest that differentiated human dermal fibroblasts have the potential to contribute to the devel opment of the vesication response by releasing proteases such as elastase extracellularly after HD exposure. These types of studies cannot be conducted in humans on ethical grounds because of the mutagenic properties of HD. The HDE model therefore has an important advantage in studies on the mechanism of action of HD.
17
Ranjit, Chayan, e Prabir Rudra. "Study of some cosmological parameters for interacting new holographic dark energy model in f(T) gravity". International Journal of Modern Physics D 25, n. 01 (gennaio 2016): 1650008. http://dx.doi.org/10.1142/s0218271816500085.
Testo completoAbstract (sommario):
The present work is based on the idea of an interacting framework of new holographic dark energy (HDE) with cold dark matter in the background of [Formula: see text] gravity. Here, we have considered the flat modified Friedmann universe for [Formula: see text] gravity which is filled with new HDE and dark matter. We have derived some cosmological parameters like deceleration parameter, equation of state (EoS) parameter, state-finder parameters, cosmographic parameters, Om parameter and graphically investigated the nature of these parameters for the above mentioned interacting scenario. The results are found to be consistent with the accelerating universe. Also, we have graphically investigated the trajectories in [Formula: see text] plane for different values of the interacting parameter and explored the freezing region and thawing region in [Formula: see text] plane. Finally, we have analyzed the stability of this model.
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Mishra, Sudip, e Subenoy Chakraborty. "Stability analysis of an interacting holographic dark energy model". Modern Physics Letters A 34, n. 19 (20 giugno 2019): 1950147. http://dx.doi.org/10.1142/s0217732319501475.
Testo completoAbstract (sommario):
This work deals with dynamical system analysis of Holographic Dark Energy (HDE) cosmological model with different infra-red (IR)-cutoff. By suitable transformation of variables, the Einstein field equations are converted to an autonomous system. The critical points are determined and the stability of the equilibrium points are examined by Center Manifold Theory and Lyapunov function method. Possible bifurcation scenarios have also been explained.
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SHARIF, M., e RABIA SALEEM. "DARK ENERGY MODELS AND LAWS OF THERMODYNAMICS IN BIANCHI I MODEL". Modern Physics Letters A 27, n. 33 (24 ottobre 2012): 1250187. http://dx.doi.org/10.1142/s0217732312501878.
Testo completoAbstract (sommario):
This paper is devoted to check validity of the laws of thermodynamics for locally rotationally symmetric (LRS) Bianchi type I (BI) universe model which is filled with combination of dark matter and dark energy (DE). We take two types of DE models, i.e. generalized holographic DE (HDE) and generalized Ricci DE (RDE). It is proved that the first and generalized second law of thermodynamics (GSLT) are valid on the apparent horizon for both the models. Further, we take fixed radius L of the apparent horizon with original holographic or RDE. We conclude that the first and GSLT do not hold on the horizon of fixed radius L for both the models.
20
Zadeh, M. Abdollahi, e A. Sheykhi. "Sign-changeable holographic dark energy in Brans–Dicke theory". Canadian Journal of Physics 97, n. 7 (luglio 2019): 726–34. http://dx.doi.org/10.1139/cjp-2018-0413.
Testo completoAbstract (sommario):
We consider the Brans–Dicke (BD) theory of gravity and explore the cosmological implications of the sign-changeable interacting holographic dark energy (HDE) model in the background of a Friedmann–Robertson–Walker (FRW) universe. As the system’s infrared cutoff, we choose the future event horizon, the Granda–Oliveros (GO), and the Ricci cutoffs. For each cutoff, we obtain the density parameter, the equation of state (EoS), and the deceleration parameter of the system. In case of future event horizon, we find out that the EoS parameter, wD, can cross the phantom line; as a result the transition from the deceleration to the acceleration of the Universe expansion can be achieved provided the model parameters are chosen suitably. We also investigate the instability of the sign-changeable interacting HDE model against perturbations in BD theory. For this purpose, we study the squared sound speed [Formula: see text] whose sign determines the stability of the model. When [Formula: see text] the model is unstable against perturbation. For future event horizon, our Universe can be stable ([Formula: see text]) depending on the model parameters. Then, we focus on GO and Ricci cutoffs and find out that although other features of these two cutoffs are consistent with observations, they cannot lead to stable dominated universe, except in a special case with GO cutoff. Our studies confirm that for the sign-changeable HDE model in the setup of BD cosmology, the event horizon is the most suitable horizon that can pass all conditions and leads to a stable dark-energy-dominated universe.
21
Hillier, D. John, Paul A. Crowther, Francisco Najarro de la Parra e Alexander W. Fullerton. "The extreme P-Cygni star HDE 316285". Symposium - International Astronomical Union 193 (1999): 246–47. http://dx.doi.org/10.1017/s0074180900205421.
Testo completoAbstract (sommario):
New line-blanketed models for the P-Cygni star HDE 316285 have been calculated. Representative model atoms for H, He I, He II, Ca I, Ca II, Mg I, Mg II, Al II, Al III, Fe II, and Fe III are included in the calculations. We confirm the basic parameters derived by Hillier et al. (1998) in an earlier unblanketed study, and also confirm that many of the optical metal lines are produced by continuum fluorescence. The charge exchange reaction Fe2+ + H ⇌ Fe+ + H + modifies the Fe ionization structure and significantly enhances the strength of the optical Fe II emission lines.
22
Qiu, Xing-Wei, Ze-Wei Zhao, Ling-Feng Wang, Jing-Fei Zhang e Xin Zhang. "A forecast of using fast radio burst observations to constrain holographic dark energy". Journal of Cosmology and Astroparticle Physics 2022, n. 02 (1 febbraio 2022): 006. http://dx.doi.org/10.1088/1475-7516/2022/02/006.
Testo completoAbstract (sommario):
Abstract Recently, about five hundred fast radio bursts (FRBs) detected by CHIME/FRB Project have been reported. The vast amounts of data would make FRBs a promising low-redshift cosmological probe in the forthcoming years, and thus the issue of how many FRBs are needed for precise cosmological parameter estimation in different dark energy models should be detailedly investigated. Different from the usually considered w(z)-parameterized models in the literature, in this work we investigate the holographic dark energy (HDE) model and the Ricci dark energy (RDE) model, which originate from the holographic principle of quantum gravity, using the simulated localized FRB data as a cosmological probe for the first time. We show that the Hubble constant H 0 can be constrained to about 2% precision in the HDE model with the Macquart relation of FRB by using 10000 accurately-localized FRBs combined with the current CMB data, which is similar to the precision of the SH0ES value. Using 10000 localized FRBs combined with the CMB data can achieve about 6% constraint on the dark-energy parameter c in the HDE model, which is tighter than the current BAO data combined with CMB. We also study the combination of the FRB data and another low-redshift cosmological probe, i.e. gravitational wave (GW) standard siren data, with the purpose of measuring cosmological parameters independent of CMB. Although the parameter degeneracies inherent in FRB and in GW are rather different, we find that more than 10000 FRBs are demanded to effectively improve the constraints in the holographic dark energy models.
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Kaur, Simran, e C. P. Singh. "Viscous cosmology in holographic dark energy with Granda–Oliveros cut-off". Communications in Theoretical Physics 75, n. 2 (1 febbraio 2023): 025401. http://dx.doi.org/10.1088/1572-9494/aca651.
Testo completoAbstract (sommario):
Abstract We study the effect of bulk viscosity on holographic dark energy (HDE) with Granda–Oliveros infra-red cut-off. We focus on a generalized form of the bulk viscous coefficient which successfully describes the present-day evolution of the Universe. We observe that the model with bulk viscosity provides an elegant description of the early and late-time evolution of the Universe. We constrain the model through the combined observational data of the Strong Lensing System (SLS), measurements of Hubble parameter, Type Ia supernova data of Pantheon sample and local H 0 measured by SH0ES. Using best-fit values obtained from two different combinations of data, we estimate the present value of Hubble’s constant H 0 = 71.567 − 0.848 + 1.448 and H 0 = 69.197 − 1.924 + 1.563 , the deceleration parameter q 0 = − 0.535 − 0.016 + 0.016 and q 0 = − 0.536 − 0.016 + 0.016 , and the equation of state ω 0 = − 0.690 − 0.010 + 0.010 and ω 0 = − 0.691 − 0.011 + 0.011 , respectively. The HDE model with bulk viscosity exhibits the phase transition from decelerated epoch to accelerated epoch. A comparison of the model with the standard ΛCDM model is discussed with the statefinder and cosmographic parameters.
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Ranjit, Chayan, e Ujjal Debnath. "Analysis of interacting entropy-corrected holographic and new agegraphic dark energies". International Journal of Modern Physics D 27, n. 04 (marzo 2018): 1850035. http://dx.doi.org/10.1142/s0218271818500359.
Testo completoAbstract (sommario):
In the present work, we assume the flat FRW model of the universe is filled with dark matter and dark energy where they are interacting. For dark energy model, we consider the entropy-corrected HDE (ECHDE) model and the entropy-corrected NADE (ECNADE). For entropy-corrected models, we assume logarithmic correction and power law correction. For ECHDE model, length scale [Formula: see text] is assumed to be Hubble horizon and future event horizon. The [Formula: see text]-[Formula: see text] analysis for our different horizons are discussed.
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Chiang, Chao Lung. "Hybrid Differential Evolution for Power Economic Dispatch Problems Considering the Incorporated Cost Model". Applied Mechanics and Materials 302 (febbraio 2013): 782–86. http://dx.doi.org/10.4028/www.scientific.net/amm.302.782.
Testo completoAbstract (sommario):
This paper presents an effective algorithm to solve power economic dispatch (PED) problems considering incorporated cost model of valve-point effects and multiple fuels. The proposed algorithm integrates the hybrid differential evolution (HDE) and the multiplier updating (MU). Few PED problems related studies have seldom addressed both valve-point loadings and change fuels. To show the advantages of the proposed algorithm, was employed to test PED problems with one test system considering the incorporated cost model. Additionally, the proposed algorithm was compared with the differential evolution (DE), revealing that the proposed method is more effective and efficient than the DE in application of power system.
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Najarro De La Parra, Francisco, D. John Hillier e Donald F. Figer. "Metal abundances in the Galactic Center". Symposium - International Astronomical Union 193 (1999): 491–92. http://dx.doi.org/10.1017/s007418090020613x.
Testo completoAbstract (sommario):
Recent progress in model atmospheres for hot stars is presented. The impact of nlte wind-blanketed models is shown by comparison with the ‘old’ standard model. In order to confindently use the IR-spectra of objects at the Galactic Center (with high extinction) to derive their physical properties and trace the metal content, the consistency between results from optical and IR analysis is checked in a calibration study using the B1.5Ia+ star HDE 316285. With the above consistency proved, we started a detail investigation of the Pistol Star. Preliminary results are presented.
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Kumar, Praveen, e G. S. Khadekar. "Holographic Dark Energy with Modified Chaplygin Gas and Scalar Field in (2 + 1)−Dimensional Space-time". Journal of the Tensor Society 15, n. 01 (30 giugno 2007): 17–44. http://dx.doi.org/10.56424/jts.v15i01.10615.
Testo completoAbstract (sommario):
In this paper, we generalized the work of Sheykhi (2011) and Ghose (2014) and establish the connection between Holographic Dark energy interacting with modified Chaplygin gas and then obtain the evolution of holographic dark energy with corresponding equation of state. In the first part of the paper, we have generalized the work of Sheykhi (2011) by choosing Hubble radius as the system’s IR cut-off and constructing the analytical form of the potentials as a function of scalar fields, namely V = V (ϕ) as well as this dynamics of the scalar fields as a function of time, namely ϕ = ϕ(t) then we have implemented the connection between Holographic dark energy and scalar fields model including quintessence, tachyon, K−essence and dilaton energy density in a (2+1)−dimensional spacetime FRW universe. In the second part of the paper, we have generalized the work of Ghose (2014) and investigate holographic dark energy (HDE) correspondence of interacting Modified Chaplygin Gas (MCG), and obtained evolution of the HDE with the corresponding equation of state. Considering the present value of the density parameter a stable configuration is found which accommodates Dark Energy (DE). We note a connection between DE and Phantom fields. It reveals that the DE might have evolved from a Phantom state in the past. We also obtained the stability of the model and analyzed the physical and geometrical interpretations of the cosmological model with reference to the (2 + 1)−dimensional spacetime.
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Sharma, Umesh Kumar, e Vipin Chandra Dubey. "Rényi holographic dark energy in the Brans–Dicke cosmology". Modern Physics Letters A 35, n. 34 (16 settembre 2020): 2050281. http://dx.doi.org/10.1142/s0217732320502818.
Testo completoAbstract (sommario):
In this paper, we construct a holographic dark energy (HDE) model considering the IR cut-off as Hubble horizon, holographic hypothesis, and using the generalized Rényi entropy, and investigate its cosmological outcomes in Brans–Dicke gravity without interaction. We observe the suitable behavior for the cosmological parameters, involving the deceleration parameter, the equation of state (EoS) parameter, and the density parameter in both flat and non-flat Universes. It is also concluded by the stability analysis that the Rényi holographic dark energy (RHDE) model is classically stable at present and future for the Rényi parameter [Formula: see text] in both flat and non-flat Universe.
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Sharma, Umesh Kumar, e Anirudh Pradhan. "Diagnosing Tsallis holographic dark energy models with statefinder and ω − ω′ pair". Modern Physics Letters A 34, n. 13 (30 aprile 2019): 1950101. http://dx.doi.org/10.1142/s0217732319501013.
Testo completoAbstract (sommario):
A useful method, known as statefinder diagnostic, which may differentiate one dark energy (DE) model from others is applied in this work to a holographic dark energy (HDE) model from Tsallis entropy, called the Tsallis holographic dark energy (THDE) model. The evolutionary trajectories of this model are plotted in the statefinder parameter — planes and [Formula: see text] plane, and it is observed that the parameter [Formula: see text] of this model plays a magnificent role from the statefinder and [Formula: see text] plane viewpoints. Eventually, the evolutionary trajectories are plotted considering two different values of THDE energy density ([Formula: see text]), [Formula: see text], in the light of Planck 2018 results VI base-LCDM cosmology and [Formula: see text], in the light of SNe + BAO + OHD + CMB observation data.
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Mahata, Nilanjana, e Subenoy Chakraborty. "A dynamical system analysis of holographic dark energy models with different IR cutoff". Modern Physics Letters A 30, n. 27 (13 agosto 2015): 1550134. http://dx.doi.org/10.1142/s0217732315501345.
Testo completoAbstract (sommario):
The paper deals with a dynamical system analysis of the cosmological evolution of an holographic dark energy (HDE) model interacting with dark matter (DM) which is chosen in the form of dust. The infrared cutoff of the holographic model is considered as future event horizon or Ricci length scale. The interaction term between dark energy (DE) and DM is chosen of following three types: (i) proportional to the sum of the energy densities of the two dark components, (ii) proportional to the product of the matter energy densities and (iii) proportional to DE density. The dynamical equations are reduced to an autonomous system for the three cases and corresponding phase space is analyzed.
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Schmutz, W., C. Leitherer, A. V. Torres-Dodgen, M. Vogel, P. S. Conti, W. R. Hamann e U. Wessolowski. "NLTE analysis of R84". International Astronomical Union Colloquium 113 (1989): 289–90. http://dx.doi.org/10.1017/s025292110000467x.
Testo completoAbstract (sommario):
The LMC star R84 (-HDE 269227 -BR 18) belongs to the group of Ofpe/WN stars believed to be closely related to the Luminous Blue Variables. Support for such a relation comes from the spectral resemblance of these stars to AG Car during visual minimum, and from the observed outburst of the Ofpe/WN star R127.The spectral analysis of R84 presented here is based on model calculations with the NLTE comoving-frame code described by Wessolowski et al. (1988) and references therein. The helium model atom was represented by 28 levels and hydrogen by 9 levels. The free model parameters were varied until the observed line profiles and the absolutely calibrated and dereddened continuum flux were reproduced. The comparison of the theoretical continuum flux distribution with the observed one yields a reddening of EB-V=0.1.
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Alam, Mohammad Moksud. "Anisotropic Universe with Manimally Interacting Matter and Holographic Dark Energy". Chittagong University Journal of Science 42, n. 1 (22 giugno 2021): 39–57. http://dx.doi.org/10.3329/cujs.v42i1.54237.
Testo completoAbstract (sommario):
The holographic dark energy (HDE), a form of dark energy, has been a useful tool in explaining the recent phase transition of the universe. In this paper, we study the anisotropic and homogeneous Bianchi type-III model of the universe filled with minimally interacting matter and holographic dark energy under the framework of the Brans-Dicke (BD) scalar tensor theory of gravitation. Considering two physically plausible conditions such as, (i) the special law of variation for Hubble parameter and (ii) the scalar expansion proportional to the shear scalar, we propose two new models namely, exponential expansion model and power law expansion model. We also show the dynamics of these models fit with existing observational data and literature thereof. The transit behavior of the equation of state parameter for dark energy has been analyzed graphically. The jerk parameter is also studied for both of the models describing cosmological evolution. The Chittagong Univ. J. Sci. 42(1): 39-57, 2020
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Ali, Sarfraz, Muhammad Hummad Waheed, Muhammad Imran Asjad, Khuram Ali Khan, Thanin Sitthiwirattham e Chanon Promsakon. "The Sharma–Mittal Model’s Implications on FRW Universe in Chern–Simons Gravity". Universe 7, n. 11 (10 novembre 2021): 428. http://dx.doi.org/10.3390/universe7110428.
Testo completoAbstract (sommario):
The Sharma–Mittal holographic dark energy model is investigated in this paper using the Chern–Simons modified gravity theory. We investigate several cosmic parameters, including the deceleration, equation of state, square of sound speed, and energy density. According to the deceleration parameter, the universe is in an decelerating and expanding phase known as de Sitter expansion. The Sharma–Mittal HDE model supports a deceleration to acceleration transition that is compatible with the observational data. The EoS depicts the universe’s dominance era through a number of components, such as ω=0, 13, 1, which indicate that the universe is influenced by dust, radiation, and stiff fluid, while −1<ω<13, ω=−1, and ω<−1 are conditions for quintessence DE, ΛCDM, and Phantom era dominance. Our findings indicate that the universe is in an accelerated expansion phase, and this is similar to the observational data.
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KHODAM-MOHAMMADI, A. "POWER-LAW ENTROPY CORRECTED NEW HOLOGRAPHIC SCALAR FIELD MODELS OF DARK ENERGY WITH MODIFIED IR-CUTOFF". Modern Physics Letters A 26, n. 33 (30 ottobre 2011): 2487–99. http://dx.doi.org/10.1142/s0217732311036826.
Testo completoAbstract (sommario):
In this work, the PLECHDE model with Granda–Oliveros (G–O) IR-cutoff is studied. The evolution of dark energy density, deceleration and EoS parameters are calculated. I demonstrate that under a condition, our universe can accelerate near the phantom barrier at present time. We calculate these parameters also in PLECHDE at Ricci scale, when α = 2 and β = 1, and a comparison between Ricci scale, G–O cutoff and non-corrected HDE without matter field with G–O cutoff is done. The correspondence between this model and some scalar field of dark energy models is established. By this method, the evolutionary treatment of kinetic energy and potential for quintessence, tachyon, K-essence and dilaton fields, are obtained. I show that the results has a good compatibility with previous work in the limiting case of flat, dark dominated and non-corrected holographic dark energy.
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Srivastava, Milan, e C. P. Singh. "Cosmological evolution of non-interacting and interacting holographic dark energy model in Brans–Dicke theory". International Journal of Geometric Methods in Modern Physics 15, n. 07 (24 maggio 2018): 1850124. http://dx.doi.org/10.1142/s0219887818501244.
Testo completoAbstract (sommario):
The purpose of this paper is to study the dynamics of non-interacting and interacting holographic dark energy (HDE) models in the framework of Brans–Dicke (BD) cosmology. As system’s infrared cutoff, we consider the future event horizon. The scalar function of BD theory is assumed to be a logarithmic form of scale factor, which is claimed to avoid a constant result for deceleration parameter. We investigate the cosmological implications of this model in detail. We obtain the time-dependent equation of state parameter and deceleration parameter which describe the phase transition of the Universe. We observe that the model explains the early time inflation and late time acceleration including matter-dominated phase. It is also observed that the equation of state parameter may cross phantom divide line in late time evolution. The cosmic coincidence problem is also discussed for both the models. We observe that this logarithmic form of Brans–Dicke scalar field is more appropriate to achieve a less acute coincidence problem in non-interacting model whereas a soft coincidence can be achieved if coupling parameter in interacting model has small value.
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Golchin, Hanif, Sara Jamali e Esmaeil Ebrahimi. "Interacting dark energy: Dynamical system analysis". International Journal of Modern Physics D 26, n. 09 (13 marzo 2017): 1750098. http://dx.doi.org/10.1142/s0218271817500985.
Testo completoAbstract (sommario):
We investigate the impacts of interaction between dark matter (DM) and dark energy (DE) in the context of two DE models, holographic (HDE) and ghost dark energy (GDE). In fact, using the dynamical system analysis, we obtain the cosmological consequence of several interactions, considering all relevant component of universe, i.e. matter (dark and luminous), radiation and DE. Studying the phase space for all interactions in detail, we show the existence of unstable matter-dominated and stable DE-dominated phases. We also show that linear interactions suffer from the absence of standard radiation-dominated epoch. Interestingly, this failure resolved by adding the nonlinear interactions to the models. We find an upper bound for the value of the coupling constant of the interaction between DM and DE as [Formula: see text][Formula: see text]in the case of holographic model, and [Formula: see text] in the case of GDE model, to result in a cosmological viable matter-dominated epoch. More specifically, this bound is vital to satisfy instability and deceleration of matter-dominated epoch.
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Gies, D. R., e C. T. Bolton. "The Optical Spectrum of HDE 226868=Cygnus X-1. III. A Focused Stellar Wind Model for He II lambda 4686 Emission". Astrophysical Journal 304 (maggio 1986): 389. http://dx.doi.org/10.1086/164172.
Testo completo
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Chakraborty, Gargee, e Surajit Chattopadhyay. "Cosmology of a generalised version of holographic dark energy in presence of bulk viscosity and its inflationary dynamics through slow roll parameters". International Journal of Modern Physics D 29, n. 03 (febbraio 2020): 2050024. http://dx.doi.org/10.1142/s0218271820500248.
Testo completoAbstract (sommario):
This study reports a reconstruction scheme of a Dark Energy (DE) model with higher-order derivative of Hubble parameter, which is a particular case of Nojiri–Odintsov holographic DE (HDE) [S. Nojiri and S. D. Odintsov, Gen. Relativ. Gravit. 38 (2006) 1285.] that unifies phantom inflation with the acceleration of the universe on late-time. The reconstruction has been carried out in the presence of bulk viscosity, where the bulk-viscous pressure has been taken as a function of Hubble parameter. Ranges of cosmic time [Formula: see text] have been derived for quintessence, cosmological constant and phantom behaviour of the equation-of-state (EoS) parameter. In the viscous scenario, the reconstruction has been carried out in an interacting and noninteracting situations and in both the cases stability against small perturbations has been observed. Finally, the slow roll parameters have been studied and a scope of exit from inflation has been observed. Also, the availability of quasi-exponential expansion has been demonstrated for interacting viscous scenario and a study through tensor-to-scalar ratio has ensured consistency of the model with the observational bound by Planck. Alongwith primordial fluctuations, the interacting scenario has been found to generate strong dissipative regime.
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Kern, Renée, Abderrahim Malki, Jad Abdallah, Jihen Tagourti e Gilbert Richarme. "Escherichia coli HdeB Is an Acid Stress Chaperone". Journal of Bacteriology 189, n. 2 (3 novembre 2006): 603–10. http://dx.doi.org/10.1128/jb.01522-06.
Testo completoAbstract (sommario):
ABSTRACT We cloned, expressed, and purified the hdeB gene product, which belongs to the hdeAB acid stress operon. We extracted HdeB from bacteria by the osmotic-shock procedure and purified it to homogeneity by ion-exchange chromatography and hydroxyapatite chromatography. Its identity was confirmed by mass spectrometry analysis. HdeB has a molecular mass of 10 kDa in sodium dodecyl sulfate-polyacrylamide gel electrophoresis, which matches its expected molecular mass. We purified the acid stress chaperone HdeA in parallel in order to compare the two chaperones. The hdeA and hdeB mutants both display reduced viability upon acid stress, and only the HdeA/HdeB expression plasmid can restore their viability to close to the wild-type level, suggesting that both proteins are required for optimal protection of the bacterial periplasm against acid stress. Periplasmic extracts from both mutants aggregate at acidic pH, suggesting that HdeA and HdeB are required for protein solubilization. At pH 2, the aggregation of periplasmic extracts is prevented by the addition of HdeA, as previously reported, but is only slightly reduced by HdeB. At pH 3, however, HdeB is more efficient than HdeA in preventing periplasmic-protein aggregation. The solubilization of several model substrate proteins at acidic pH supports the hypothesis that, in vitro, HdeA plays a major role in protein solubilization at pH 2 and that both proteins are involved in protein solubilization at pH 3. Like HdeA, HdeB exposes hydrophobic surfaces at acidic pH, in accordance with the appearance of its chaperone properties at acidic pH. HdeB, like HdeA, dissociates from dimers at neutral pH into monomers at acidic pHs, but its dissociation is complete at pH 3 whereas that of HdeA is complete at a more acidic pH. Thus, we can conclude that Escherichia coli possesses two acid stress chaperones that prevent periplasmic-protein aggregation at acidic pH.
40
Feng, Shaozhen, Zhong Zhong, Jinjin Fan, Xiaoyan Li, Dianchun Shi e Lanping Jiang. "Upregulated Expression of Intestinal Antimicrobial Peptide HD5 Associated with Renal Function in IgA Nephropathy". Disease Markers 2020 (5 febbraio 2020): 1–10. http://dx.doi.org/10.1155/2020/2078279.
Testo completoAbstract (sommario):
Purpose. It was reported that gut-kidney axis may play an important role in IgA nephropathy (IgAN). Previous five GWASs of different populations for IgAN have discovered several genes related to intestinal immunity, including DEFA gene. However, the roles of the encoded proteins of DEFA5/6 which were called intestinal antimicrobial peptides HD5 and HD6 were not clear in kidney disease, such as IgAN. The purpose of this study was to clarify the association of HD5 and HD6 with IgAN. Methods. We measured HD5 and HD6 in serum, urine, and kidney of IgAN patients and normal controls by ELISA, Western blot, and immunofluorescence. The association of HD5 or HD6 levels with clinical and pathologic phenotypes was analyzed. Results. Serum levels of HD5 and HD6 were significantly higher in IgAN patients than those in normal controls. Baseline serum HD5 levels were significantly associated with eGFR (P=0.002) and tubular atrophy/interstitial fibrosis (P=0.004) by stepwise multivariate regression analysis. Compared to the patients with serum HD5 below the median level, patients with elevated serum HD5 above the median level had a significantly worse renal outcome (log-rank test, P=0.009) by Kaplan-Meier analysis. A Cox regression model showed that serum HD5 was an independent prognostic factor (HR=1.239, P=0.029) after adjusting for the well-known predictors of outcome in IgAN patients. In renal biopsies of IgAN patients, HD5 was significantly expressed in the damaged proximal tubules, while no immunoreactive HD6 was found. Interestingly, the serum HD6 level of IgAN patients was significantly associated with gender. Conclusions. In IgAN patients, an elevated serum HD5 level at the time of renal biopsy was associated with poor renal outcomes. HD5 rather than HD6 was probably associated with renal function of IgAN patients.
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Li, Feng, Xuehui Du, Liu Zhang e Aodi Liu. "Image Feature Fusion Method Based on Edge Detection". Information Technology and Control 52, n. 1 (28 marzo 2023): 5–24. http://dx.doi.org/10.5755/j01.itc.52.1.31549.
Testo completoAbstract (sommario):
Deep learning-based image processing algorithms have developed rapidly in the past decade and have shown significant improvements to extract image features when both sufficient computing power and big data are accessible. Thus, rapid advances in applications such as facial recognition and autonomous driving have been one of the implementation areas. On the other hand, edges as a low-level prevalence feature in images with independent semantics are practically adapted to attain better outcomes. However, neural network-based image feature extraction focusing on texture rather than shape leads to insufficient accuracy. To address this issue, an edge feature extraction method utilizing both conventional operators such as HDE and Sobel and a deep learning-based method is proposed to classify and retrieve images with better accuracy outcomes. By doing so, a large amount of data needed to conduct deep learning-based methods is decreased, the transferability of the model is achieved, classification and retrieval accuracies are enhanced, and the data is compressed. All these better results are attained with benchmark data sets. As a result, all these are achieved by proposing a novel method.
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Li, Song, e Yun Chen. "Reconstructing Torsion Cosmology from Interacting Holographic Dark Energy Model". Universe 9, n. 2 (16 febbraio 2023): 100. http://dx.doi.org/10.3390/universe9020100.
Testo completoAbstract (sommario):
We consider a cosmological model in the framework of Einstein–Cartan theory with a single scalar torsion ϕ=ϕ(t) and reconstruct the torsion model corresponding to the holographic dark energy (HDE) density. By studying the corresponding relation between the effective energy density of torsion field ρϕ and holographic dark energy density ρHDE, we naturally obtain a kind of torsion field from the interacting holographic dark energy with interaction term Q=−2ϕρm and ρm is the energy density of matter. We analyze the reconstructed torsion model and find that the torsion field behaves like the quintessence (w>−1) or quintom (exhibiting a transition from w>−1 to w<−1) dark energy, depending on the value of the model parameter c. We then perform a stability analysis according to the squared sound speed. It is shown that the model is classically stable in the current epoch for the case of c<1. We also investigate the model from the viewpoint of statefinder parameters and it turns out that the statefinder trajectories in the r−s plane behave differently for the three cases of c and also quite distinct from those of other cosmological models. From the trajectories of the statefinder pair {q,r}, we find that, for all the three cases of c, the universe has a phase transition from deceleration to acceleration, consistently with cosmological observations. In addition, we fit the reconstructed torsion model with the recent Type Ia supernovae (SNe Ia) samples, i.e., the Pantheon sample containing 1048 SNe Ia with the redshift in the range 0.01<z<2.3 and the Pantheon+ sample with 1701 light curves of 1550 distinct SNe Ia in the range 0.001<z<2.26. The analysis results show that the limits on the present fractional energy density of matter Ωm0 are completely compatible with those of the ΛCDM model obtained from the latest Planck mission observations at 68% confidence level. The mean value of c constrained from the Pantheon sample corresponds to the quintom-like scenario (i.e., c<1) and its mean value from the Pantheon+ sample corresponds to the quintessence-like scenario (i.e., c≥1). However, both of the Pantheon and Pantheon+ samples cannot distinguish the quintom-like and quintessence-like scenarios at 68% confidence level.
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Corvec, Stéphane, Ulrika Furustrand Tafin, Bertrand Betrisey, Olivier Borens e Andrej Trampuz. "Activities of Fosfomycin, Tigecycline, Colistin, and Gentamicin against Extended-Spectrum-β-Lactamase-Producing Escherichia coli in a Foreign-Body Infection Model". Antimicrobial Agents and Chemotherapy 57, n. 3 (7 gennaio 2013): 1421–27. http://dx.doi.org/10.1128/aac.01718-12.
Testo completoAbstract (sommario):
ABSTRACTLimited antimicrobial agents are available for the treatment of implant-associated infections caused by fluoroquinolone-resistant Gram-negative bacilli. We compared the activities of fosfomycin, tigecycline, colistin, and gentamicin (alone and in combination) against a CTX-M15-producing strain ofEscherichia coli(Bj HDE-1)in vitroand in a foreign-body infection model. The MIC and the minimal bactericidal concentration in logarithmic phase (MBClog) and stationary phase (MBCstat) were 0.12, 0.12, and 8 μg/ml for fosfomycin, 0.25, 32, and 32 μg/ml for tigecycline, 0.25, 0.5, and 2 μg/ml for colistin, and 2, 8, and 16 μg/ml for gentamicin, respectively. In time-kill studies, colistin showed concentration-dependent activity, but regrowth occurred after 24 h. Fosfomycin demonstrated rapid bactericidal activity at the MIC, and no regrowth occurred. Synergistic activity between fosfomycin and colistinin vitrowas observed, with no detectable bacterial counts after 6 h. In animal studies, fosfomycin reduced planktonic counts by 4 log10CFU/ml, whereas in combination with colistin, tigecycline, or gentamicin, it reduced counts by >6 log10CFU/ml. Fosfomycin was the only single agent which was able to eradicateE. colibiofilms (cure rate, 17% of implanted, infected cages). In combination, colistin plus tigecycline (50%) and fosfomycin plus gentamicin (42%) cured significantly more infected cages than colistin plus gentamicin (33%) or fosfomycin plus tigecycline (25%) (P< 0.05). The combination of fosfomycin plus colistin showed the highest cure rate (67%), which was significantly better than that of fosfomycin alone (P< 0.05). In conclusion, the combination of fosfomycin plus colistin is a promising treatment option for implant-associated infections caused by fluoroquinolone-resistant Gram-negative bacilli.
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Sinha, Swati, Surajit Chattopadhyay e Irina Radinschi. "Cosmology of viscous holographic f(G) gravity and consequences in the framework of quintessence scalar field". International Journal of Geometric Methods in Modern Physics 16, n. 11 (novembre 2019): 1950176. http://dx.doi.org/10.1142/s0219887819501767.
Testo completoAbstract (sommario):
Work reported in this study demonstrates the reconstruction schemes for the [Formula: see text] gravity in the framework of bulk viscosity and holographic background evolution by considering the universe filled by the viscous fluid that is just special class of more general fluids as described in Nojiri and Odintsov [Inhomogeneous equation of state of the universe: Phantom era, future singularity, and crossing the phantom barrier, Phys. Rev. D 72 (2005) 023003]. The bulk viscous pressure has been considered as [Formula: see text], with [Formula: see text]. Considering the scale factor in power law form and taking holographic dark energy (HDE) with density [Formula: see text] and generalized extended holographic dark energy (EGHRDE) with density [Formula: see text], a specific case of Nojiri–Odintsov holographic DE ([Unifying phantom inflation with late-time acceleration: Scalar phantom–non-phantom transition model and generalized holographic dark energy, Gen. Relativ. Gravit. 38 (2006) 1285]) we have derived solutions for [Formula: see text] and the subsequent effective equation of state parameters have been found to behave like quintom irrespective of the choice of [Formula: see text]. Finally, considering [Formula: see text] as quintessence scalar field we have explored the possibility of quasi-exponential expansion and warm inflation.
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Shi, Qingguo, Yihuai Hu e Guohua Yan. "Hierarchical Multiscale Fluctuation Dispersion Entropy for Fuel Injection System Fault Diagnosis". Polish Maritime Research 30, n. 1 (1 marzo 2023): 98–111. http://dx.doi.org/10.2478/pomr-2023-0010.
Testo completoAbstract (sommario):
Abstract Marine electronically controlled (ME) two-stroke diesel engines occupy the highest market share in newly-built ships and its fuel injection system is quite different and important. Fault diagnosis in the fuel injection system is crucial to ensure the power, economy and emission of ME diesel engines, so we introduce hierarchical multiscale fluctuation dispersion entropy (HMFDE) and a support matrix machine (SMM) to realise it. We also discuss the influence of parameter changes on the entropy calculation’s accuracy and efficiency. The system simulation model is established and verified by Amesim software, and then HMFDE is used to extract a matrix from the features of a high pressure signal in a common rail pipe, under four working conditions. Compared with vectorised HMFDE, the accuracy of fault diagnosis using SMM is nearly 3% higher than that using a support vector machine (SVM). Experiments also show that the proposed method is more accurate and stable when compared with hierarchical multiscale dispersion entropy (HMDE), hierarchical dispersion entropy (HDE), multiscale fluctuation dispersion entropy (MFDE), multiscale dispersion entropy (MDE) and multiscale sample entropy (MSE). Therefore, the proposed method is more suitable for the modelling data. This research provides a new direction for matrix learning applications in fault diagnosis in marine two-stroke diesel engines.
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Qi, Jing-Zhao, Shang-Jie Jin, Xi-Long Fan, Jing-Fei Zhang e Xin Zhang. "Using a multi-messenger and multi-wavelength observational strategy to probe the nature of dark energy through direct measurements of cosmic expansion history". Journal of Cosmology and Astroparticle Physics 2021, n. 12 (1 dicembre 2021): 042. http://dx.doi.org/10.1088/1475-7516/2021/12/042.
Testo completoAbstract (sommario):
Abstract In the near future, the redshift drift observations in optical and radio bands will provide precise measurements on H(z) covering the redshift ranges of 2<z<5 and 0<z<0.3. In addition, gravitational wave (GW) standard siren observations could make measurements on the dipole anisotropy of luminosity distance, which will also provide the H(z) measurements in the redshift range of 0<z<3. In this work, we propose a multi-messenger and multi-wavelength observational strategy to measure H(z) based on the three next-generation projects, E-ELT, SKA, and DECIGO, and we wish to see whether the future H(z) measurements could provide tight constraints on dark-energy parameters. The dark energy models we consider include ΛCDM, wCDM, CPL, HDE, and IΛCDM models. It is found that E-ELT, SKA1, and DECIGO are highly complementary in constraining dark energy models. Although any one of these three data sets can only give rather weak constraints on each model we consider, the combination of them could significantly break the parameter degeneracies and give much tighter constraints on almost all the cosmological parameters. Moreover, we find that the combination of E-ELT, SKA1, DECIGO, and CMB could further improve the constraints on dark energy parameters, e.g., σ(w 0)=0.024 and σ(w a)=0.17 in the CPL model, which means that these three promising probes will play a key role in helping reveal the nature of dark energy.
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Hirsch, Maria, Natalie Hell, Victoria Grinberg, Ralf Ballhausen, Michael A. Nowak, Katja Pottschmidt, Norbert S. Schulz et al. "Chandra X-ray spectroscopy of the focused wind in the Cygnus X-1 system". Astronomy & Astrophysics 626 (giugno 2019): A64. http://dx.doi.org/10.1051/0004-6361/201935074.
Testo completoAbstract (sommario):
We present an analysis of three Chandra High Energy Transmission Gratings observations of the black hole binary Cyg X-1/HDE 226868 at different orbital phases. The stellar wind that is powering the accretion in this system is characterized by temperature and density inhomogeneities including structures, or “clumps”, of colder, more dense material embedded in the photoionized gas. As these clumps pass our line of sight, absorption dips appear in the light curve. We characterize the properties of the clumps through spectral changes during various dip stages. Comparing the silicon and sulfur absorption line regions (1.6–2.7 keV ≡ 7.7–4.6 Å) in four levels of varying column depth reveals the presence of lower ionization stages, i.e., colder or denser material, in the deeper dip phases. The Doppler velocities of the lines are roughly consistent within each observation, varying with the respective orbital phase. This is consistent with the picture of a structure that consists of differently ionized material, in which shells of material facing the black hole shield the inner and back shells from the ionizing radiation. The variation of the Doppler velocities compared to a toy model of the stellar wind, however, does not allow us to pin down an exact location of the clump region in the system. This result, as well as the asymmetric shape of the observed lines, point at a picture of a complex wind structure.
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Zadeh, M. Abdollahi, A. Sheykhi e H. Moradpour. "Holographic dark energy with the sign-changeable interaction term". International Journal of Modern Physics D 26, n. 08 (7 febbraio 2017): 1750080. http://dx.doi.org/10.1142/s0218271817500808.
Testo completoAbstract (sommario):
We use three infrared (IR) cutoffs, including the future event horizon, the Hubble and Granda–Oliveros (GO) cutoffs, to construct three holographic models of dark energy (DE). Additionally, we consider a Friedmann–Robertson–Walker (FRW) universe filled by a dark matter (DM) and a DE that interact with each other through a mutual sign-changeable interaction with positive coupling constant. Thereinafter, we address the evolution of the some cosmological parameters, such as the equation of state (EoS) and dimensionless density parameters of DE as well as the deceleration parameter, during the cosmic evolution from the matter-dominated era until the late-time acceleration. We observe that a holographic dark energy (HDE) model with Hubble cutoff interacting with DM cannot be in line with the current universe. Our study shows that models with the future event horizon as the IR cutoff or the GO cutoff are in good agreement with the observational data. In fact, we find out that these two recent models can predict the universe transition from a deceleration phase to the acceleration one in a compatible way with observations. The three obtained models may also allow the EoS parameter to cross the phantom line, a result which depends on the values of the system’s constants such as the value of the interaction coupling constant.
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Duraffour, Sophie, Robert Snoeck, Marcela Krečmerová, Joost van Den Oord, Rita De Vos, Antonín Holý, Jean-Marc Crance, Daniel Garin, Erik De Clercq e Graciela Andrei. "Activities of Several Classes of Acyclic Nucleoside Phosphonates against Camelpox Virus Replication in Different Cell Culture Models". Antimicrobial Agents and Chemotherapy 51, n. 12 (24 settembre 2007): 4410–19. http://dx.doi.org/10.1128/aac.00838-07.
Testo completoAbstract (sommario):
ABSTRACT Camelpox virus (CMLV) is the closest known virus to variola virus. Here we report on the anti-CMLV activities of several acyclic nucleoside phosphonates (ANPs) related to cidofovir [(S)-1-(3-hydroxy-2-phosphonomethoxypropyl)cytosine (HPMPC; Vistide)] against two CMLV strains, CML1 and CML14. Cytopathic effect (CPE) reduction assays performed with human embryonic lung fibroblast monolayers revealed the selectivities of the first two classes of ANPs (cHPMPA, HPMPDAP, and HPMPO-DAPy) and of the hexadecyloxyethyl ester of 1-{[(5S)-2-hydroxy-2-oxido-1,4,2-dioxaphosphinan-5-yl]methyl}-5-azacytosine (HDE-cHPMP-5-azaC), belonging to the newly synthesized ANPs, which are HPMP derivatives containing a 5-azacytosine moiety. The inhibitory activities of ANPs against both strains were also confirmed with primary human keratinocyte (PHK) monolayers, despite the higher toxicity of those molecules on growing PHKs. Virus yield assays confirmed the anti-CML1 and anti-CML14 efficacies of the compounds selected for the highest potencies in CPE reduction experiments. Ex vivo studies were performed with a 3-dimensional model of human skin, i.e., organotypic epithelial raft cultures of PHKs. It was ascertained by histological evaluation, as well as by virus yield assays, that CMLV replicated in the human skin equivalent. HPMPC and the newly synthesized ANPs proved to be effective at protecting the epithelial cells against CMLV-induced CPE. Moreover, in contrast to the toxicity on PHK monolayers, signs of toxicity in the differentiated epithelium were seen only at high ANP concentrations. Our results demonstrate that compounds belonging to the newly synthesized ANPs, in addition to cidofovir, represent promising candidates for the treatment of poxvirus infections.
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Jawad, Abdul, Kazuharu Bamba, Muhammad Younas, Saba Qummer e Shamaila Rani. "Tsallis, Rényi and Sharma-Mittal Holographic Dark Energy Models in Loop Quantum Cosmology". Symmetry 10, n. 11 (13 novembre 2018): 635. http://dx.doi.org/10.3390/sym10110635.
Testo completoAbstract (sommario):
The cosmic expansion phenomenon is being studied through the interaction of newly proposed dark energy models (Tsallis, Rényi and Sharma-Mittal holographic dark energy (HDE) models) with cold dark matter in the framework of loop quantum cosmology. We investigate different cosmic implications such as equation of state parameter, squared sound speed and cosmological plane (ω d - ω d ′ , ω d and ω d ′ represent the equation of state (EoS) parameter and its evolution, respectively). It is found that EoS parameter exhibits quintom like behavior of the universe for all three models of HDE. The squared speed of sound represents the stable behavior of Rényi HDE and Sharma-Mittal HDE at the latter epoch while unstable behavior for Tsallis HDE. Moreover, ω d - ω d ′ plane lies in the thawing region for all three HDE models.