383 research outputs found
Thermodynamics, phase transitions and Ruppeiner geometry for Einstein-dilaton Lifshitz black holes in the presence of Maxwell and Born-Infeld electrodynamics
In this paper, we first obtain the ()-dimensional dilaton-Lifshitz black
hole (BH) solutions in the presence of Born-Infeld (BI) electrodynamics. We
find that there are two different solutions for and cases
( is dynamical critical exponent). We show that the thermodynamics first law
is satisfied for both cases. Then, we turn to study different phase transitions
(PTs) for our BHs. We start with study of Hawking-Page PT for both linearly and
BI charged BHs. After that, we discuss the PTs inside the BHs. We present the
improved Davies quantities and prove that the PT points shown by them coincide
with Ruppeiner ones. We show that the zero temperature PTs are transitions on
radiance properties of BHs by using Landau-Lifshitz theory. Next, we turn to
study Ruppeiner geometry of linearly and BI charged BHs. For linearly charged
case, we show that there are no PT at finite temperature for the case . For , it is found that the number of finite temperature PT points
depends on the value of BH charge and is not more than two. When we have two
finite temperature PT points, there are no thermally stable BH between these
two points and we have discontinues small/large BH PTs. As expected, for small
BHs, we observe finite magnitude for Ruppeiner invariant which shows the finite
correlation between possible BH molecules while for large BHs, the correlation
is very small. Finally, we study the Ruppeiner geometry and thermal stability
of BI charged Lifshtiz BHs for different values of . We observe that small
BHs are thermally unstable in some situations. Also, the behavior of
correlation between possible BH molecules for large BHs is the same as linearly
charged case. In both linearly and BI charged cases, for some choices of
parameters, the BH systems behave like a Van der Waals gas near transition
point.Comment: V2: 23 pages (revtex format), 13 figures (except one, all include
subfigures), some references adde
Black Holes in (Quartic) Quasitopological Gravity
We construct quartic quasitopological gravity, a theory of gravity containing
terms quartic in the curvature that yields second order differential equations
in the spherically symmetric case. Up to a term proportional to the quartic
term in Lovelock gravity we find a unique solution for this quartic case, valid
in any dimensionality larger than 4 except 8. This case is the highest degree
of curvature coupling for which explicit black hole solutions can be
constructed, and we obtain and analyze the various black hole solutions that
emerge from the field equations in dimensions. We discuss the
thermodynamics of these black holes and compute their entropy as a function of
the horizon radius. We then make some general remarks about -th order
quasitopological gravity, and point out that the basic structure of the
solutions will be the same in any dimensionality for general apart from
particular cases.Comment: LaTex, 9 figures, 27 pages. A new section on holographic
hydrodynamics is added. Introduction and concluding remarks have been revise
Rocker outsole shoes and margin of stability during walking: a preliminary study
Rocker outsole shoes are commonly prescribed to diabetic patients to redistribute peak plantar pressures at high risk areas such as forefoot thereby decreasing risks of plantar ulceration. However, there are evidences of postural destabilizing effect of the rocker outsole shoes. Patients with diabetes, particularly those suffering from neuropathy, are at a higher risk of falling. Then, beside primary role of rocker outsole in offloading, it is essential to explore the effect of the rocker outsole on postural stability of these patients. The smaller base of support (BOS) of the rocker outsoles due to their specific geometry has been previously mentioned as a threat to postural stability. Margin of stability (MOS) appeared to be an appropriate method for measuring postural stability during walking by considering the dynamicity of BOS in its equation. MOS is defined as the distance between the velocity adjusted position of the centre of mass (COM) and the boundaries of the BOS which constantly changes during walking. Then, this study proposes how we can use MOS concept to investigate the impact of the rocker outsoles on dynamic stability. In this study the kinematic data from a single subject with diabetic neuropathy was used to explain the efficiency of the methodology. Conclusive results are expected after carrying out systematic tests using a statistically representative sample size.This project is funded by Iran University of Medical Sciences (IR.IUMS.REC. 1395.9211503202).info:eu-repo/semantics/publishedVersio
Two-photon Lithography for 3D Magnetic Nanostructure Fabrication
Ferromagnetic materials have been utilised as recording media within data
storage devices for many decades. Confinement of the material to a two
dimensional plane is a significant bottleneck in achieving ultra-high recording
densities and this has led to the proposition of three dimensional (3D)
racetrack memories that utilise domain wall propagation along nanowires.
However, the fabrication of 3D magnetic nanostructures of complex geometry is
highly challenging and not easily achievable with standard lithography
techniques. Here, by using a combination of two-photon lithography and
electrochemical deposition, we show a new approach to construct 3D magnetic
nanostructures of complex geometry. The magnetic properties are found to be
intimately related to the 3D geometry of the structure and magnetic imaging
experiments provide evidence of domain wall pinning at a 3D nanostructured
junction
carbonation behaviour of concrete with SCM incorporation according to TfNSW QA specification 3211 requirements
The carbonation of concrete in structures causes deterioration and service life reduction. When carbon dioxide (CO2) from the surrounding atmosphere reacts with cement hydration products in concrete and imposes an environmental load, calcium carbonate forms, and the carbonation process begins.
Validating the minimum SL cement content required for the carbonation resistance formulae in the TfNSW 3211 specification is important parts of this study.
In this research, the carbonation behaviour of concrete mixes utilising 250, 300, and 350 kg/m3 binder content, a fixed water-to-binder ratio of 0.45, and cement replacement levels of 40-70% GGBFS and 15-20% fly ash, will be investigated.
Compressive strength, flexural strength, drying shrinkage and accelerated carbonation depth results will be reported. The relationship between carbonation depth and carbonation rate using GGBFS and fly ash will also be evaluated
Fresh, Mechanical, and Durability Properties of Self-Compacting Mortar Incorporating Alumina Nanoparticles and Rice Husk Ash.
This paper presents a comprehensive evaluation on self-compacting (SC) mortars incorporating 0, 1, 3, and 5% alumina nanoparticles (NA) as well as 0% and 30% rice husk ash (RHA) used as Portland cement replacement. To evaluate the workability, mechanical, and durability performance of SC mortars incorporating NA and RHA, the fresh properties (slump flow diameter and V-funnel flow time), hardened properties (compressive strength, flexural strength, and ultrasonic pulse velocity), and durability properties (water absorption, rapid chloride permeability, and electrical resistivity) were determined. The results indicated that the addition of NA and RHA has negligible effect on the workability and water absorption rate of the SC mortars. However, significant compressive and flexural strength development was observed in the SC mortars treated with NA or the combination of NA and RHA. The introduction of RHA and NA also reduced the rapid chloride permeability and enhanced the electrical resistivity of the SC mortars significantly. It is concluded that the coexistence of 30% RHA and 3% NA as cement replacement in SC mortars can provide the best mechanical and durability performance
Dormant Tumor Cell Vaccination: A Mathematical Model of Immunological Dormancy in Triple-Negative Breast Cancer.
Triple-negative breast cancer (TNBC) is a molecular subtype of breast malignancy with a poor clinical prognosis. There is growing evidence that some chemotherapeutic agents induce an adaptive anti-tumor immune response. This reaction has been proposed to maintain the equilibrium phase of the immunoediting process and to control tumor growth by immunological cancer dormancy. We recently reported a model of immunological breast cancer dormancy based on the murine 4T1 TNBC model. Treatment of 4T1 cells in vitro with high-dose chemotherapy activated the type I interferon (type I IFN) signaling pathway, causing a switch from immunosuppressive to cytotoxic T lymphocyte-dependent immune response in vivo, resulting in sustained dormancy. Here, we developed a deterministic mathematical model based on the assumption that two cell subpopulations exist within the treated tumor: one population with high type I IFN signaling and immunogenicity and lower growth rate; the other population with low type I IFN signaling and immunogenicity and higher growth rate. The model reproduced cancer dormancy, elimination, and immune-escape in agreement with our previously reported experimental data. It predicted that the injection of dormant tumor cells with active type I IFN signaling results in complete growth control of the aggressive parental cancer cells injected at a later time point, but also of an already established aggressive tumor. Taken together, our results indicate that a dormant cell population can suppress the growth of an aggressive counterpart by eliciting a cytotoxic T lymphocyte-dependent immune response
Numerical simulation of turbidity current using V2-f turbulence model
The deposition behavior of fine sediment is an important phenomenon, and yet unclear to engineers concerned about
reservoir sedimentation. An elliptic relaxation turbulence model ( 2 n - f model) has been used to simulate the motion of
turbid density currents laden with fine solid particles. During the last few years, the 2 n - f turbulence model has become
increasingly popular due to its ability to account for near-wall damping without use of damping functions. The 2 n - f model
has also proved to be superior to other RANS (Reynolds-Averaged Navier-Stokes) methods in many fluid flows where
complex flow features are present. This current becomes turbulent at low Reynolds number (order 1000). The k -e model,
which was standardized for high Reynolds number and isotropic turbulence flow, cannot simulate the anisotropy and nonhomogenous
behavior near the wall. In this study, the turbidity current with a uniform velocity and concentration enters the
channel via a sluice gate into a lighter ambient fluid and moves forward down-slope. The model has been validated by
available experimental data sets. Moreover, results have been compared with the standard k -e turbulence model. The
deposition of particles and the effects of their fall velocity on concentration distribution, Richardson number, and the
deposition rate are also investigated. The results show that the coarse particles settle rapidly and make the deposition rate
higher
Reduction in ischemic brain injury following the administration of pentoxifylline after transient global ischemia/reperfusion in a rat model
Background: It is well known that the hippocampus, the CA1 Pyramidal cells in particular, is selectively vulnerable during global cerebral ischemia. Recently, it is observed that pentoxifylline has a neuroprotective effect. This study explored the pharmacological relationship between ischemiainduced cell death of the hippocampus and the efficacy of a vasodilator agent (pentoxifylline) in the prevention of delayed neuronal death. Methods: This experimental study was performed on 4 groups: control, ischemia, experimental (200mg/kg pentoxifylline injection one hour prior to and one hour following ischemia) and vehicle (normal saline). Transient global ischemia was induced by bilateral common carotid arteries occlusion. To investigate the apoptotic bodies and caspase-3 activities as a central role in the execution phase of apoptosis, the brains were prepared for the TUNEL technique. Results: Pentoxifylline administration limited apoptosis and caspase-3 activities in rats' hippocampi. Our data showed no significant difference between the number of apoptotic bodies in the CA1 region of the hippocampus in the control and pentoxifylline -treated groups (p= 0.994). The results of one- way ANOVA revealed that that ischemia significantly increased caspase-3 levels in the hippocampus (p< 0.05); however, the level of caspase-3 in pentoxifylline -treated rats was less than the ischemic group. Conclusion: These results suggest that the neuroprotective effect of pentoxifylline (200mg/kg) may be accompanied by a reduction in ischemic damage within the CA1 region of the hippocampus in rats subjected to transient global cerebral ischemia
Apolipoprotein A1 as a novel anti-implantation biomarker in polycystic ovary syndrome: A case-control study
Background: Women with polycystic ovary syndrome have lower pregnancy rates, possibly due to the decreased uterine receptivity. Successful implantation depends on protein networks that are essential for cross-talk between the embryo and endometrium. Apolipoprotein A1 has been proposed as a putative anti-implantation factor. In this study, we evaluated apolipoprotein A1 expression in human endometrial tissues. Materials and Methods: Endometrial apolipoprotein A1 messenger RNA (mRNA) and protein expression were investigated using quantitative real-time polymerase chain reaction (PCR) and Western blot. The distribution of apolipoprotein A1 was also detected by immunostaining. Samples were obtained from 10 patients with polycystic ovary syndrome and 15 healthy fertile women in the proliferative (on day 2 or day 3 before ovulation, n = 7) and secretory (on days 3-5 after ovulation, n = 8) phases. Results: Endometrial apolipoprotein A1 expression was upregulated in patients with polycystic ovary syndrome compared to normal subjects. However, apolipoprotein A1 expression in the proliferative phase was significantly higher than in the luteal phase (P value < 0.05). Conclusion: It seems that differentially expressed apolipoprotein A1 negatively affects endometrial receptivity in patients with polycystic ovary syndrome. The results showed that apolipoprotein A1 level significantly changes in the human endometrium during the menstrual cycle with minimum expression in the secretory phase, coincident with the receptive phase (window of implantation). Further studies are required to clarify the clinical application of this protein. © 2015 Journal of Research in Medical Sciences
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