Detection of Earth-mass and super-Earth Trojan planets using transit timing variation method

Haghighipour, Nader,Capen, Stephanie,Hinse, Tobias C. Springer-Verlag 2013 Celestial mechanics and dynamical astronomy Vol.117 No.1

Implementation of Uniform Deformation Theory in semi-active control of structures using fuzzy controller

Reza Karami Mohammadi,Fariba Haghighipour 국제구조공학회 2017 Smart Structures and Systems, An International Jou Vol.19 No.4

Protection of structures against natural hazards such as earthquakes has always been a major concern. Semi-active control combines the reliability of passive control and versatility and adaptability of active control. So it has recently become a preferred control method. This paper proposes an algorithm based on Uniform Deformation Theory to mitigate vulnerable buildings using magneto-rheological (MR) damper. Due to the successful performance of fuzzy logic in control of systems and its simplicity and intrinsically robustness, it is used here to regulate MR dampers. The particle swarm optimization (PSO) algorithm is also used as an adaptive method to develop a fuzzy control algorithm that is able to create uniform inter-story drifts. Results show that the proposed algorithm exhibited a desirable performance in reducing both linear and nonlinear seismic responses of structures. Performance of the presented method is indicated in compare with passive-on and passive-off control algorithms.

OBSERVATIONAL AND DYNAMICAL CHARACTERIZATION OF MAIN-BELT COMET P/2010 R2 (La Sagra)

Hsieh, Henry H.,Yang, Bin,Haghighipour, Nader,Novaković,, Bojan,Jedicke, Robert,Wainscoat, Richard J.,Denneau, Larry,Abe, Shinsuke,Chen, Wen-Ping,Fitzsimmons, Alan,Granvik, Mikael,Grav, Tommy,Ip, American Institute of Physics 2012 The Astronomical journal Vol.143 No.5

<P>We present observations of the recently discovered comet-like main-belt object P/2010 R2 (La Sagra) obtained by Pan-STARRS1 and the Faulkes Telescope-North on Haleakala in Hawaii, the University of Hawaii 2.2 m, Gemini-North, and Keck I telescopes on Mauna Kea, the Danish 1.54 m telescope (operated by the MiNDSTEp consortium) at La Silla, and the Isaac Newton Telescope on La Palma. An antisolar dust tail is observed to be present from 2010 August through 2011 February, while a dust trail aligned with the object's orbit plane is also observed from 2010 December through 2011 August. Assuming typical phase darkening behavior, P/La Sagra is seen to increase in brightness by >1 mag between 2010 August and December, suggesting that dust production is ongoing over this period. These results strongly suggest that the observed activity is cometary in nature (i.e., driven by the sublimation of volatile material), and that P/La Sagra is therefore the most recent main-belt comet to be discovered. We find an approximate absolute magnitude for the nucleus of H<SUB>R</SUB> = 17.9 ± 0.2 mag, corresponding to a nucleus radius of ~0.7 km, assuming an albedo of p = 0.05. Comparing the observed scattering surface areas of the dust coma to that of the nucleus when P/La Sagra was active, we find dust-to-nucleus area ratios of A<SUB>d</SUB>/A<SUB>N</SUB> = 30-60, comparable to those computed for fellow main-belt comets 238P/Read and P/2008 R1 (Garradd), and one to two orders of magnitude larger than for two other main-belt comets (133P/Elst-Pizarro and 176P/LINEAR). Using optical spectroscopy to search for CN emission, we do not detect any conclusive evidence of sublimation products (i.e., gas emission), finding an upper limit CN production rate of Q<SUB>CN</SUB> < 6 × 10<SUP>23</SUP> mol s<SUP>–1</SUP>, from which we infer an H<SUB>2</SUB>O production rate of <img SRC='http://ej.iop.org/images/1538-3881/143/5/104/aj423523ieqn1.gif' ALIGN='MIDDLE' ALT='$Q_{\rm H_2O}\,{<}\,10^{26}$'/> mol s<SUP>–1</SUP>. Numerical simulations indicate that P/La Sagra is dynamically stable for >100 Myr, suggesting that it is likely native to its current location and that its composition is likely representative of other objects in the same region of the main belt, though the relatively close proximity of the 13:6 mean-motion resonance with Jupiter and the (3,–2,–1) three-body mean-motion resonance with Jupiter and Saturn mean that dynamical instability on larger timescales cannot be ruled out.</P>

The Role of Low-Frequency Electromagnetic Fields on Mesenchymal Stem Cells Differentiation: A Systematic Review

Safavi Atiyeh Sadat,Sendera Anna,Haghighipour Nooshin,Banas-Zabczyk Agnieszka 한국조직공학과 재생의학회 2022 조직공학과 재생의학 Vol.19 No.6

BACKGROUND Low-frequency electromagnetic fields (EMFs) influence biological processes. This present study was aimed at the scientific literature on the use of EMFs in the mesenchymal stem cell differentiation process. MATERIALS AND METHODS The electronic search was carried out in PubMed and Web of Science, a database with a combination of the sinusoidal and pulsed low- and extremely low-frequency electromagnetic fields stimulation and mesenchymal stem cells differentiation, considering the period of publication until December 2021. The literature search identified 118 references in PubMed and Web of Science of which 46 articles were selected, respectively, according to the eligibility requirements. CONCLUSION The analysis of research indicated that EMFs are an easy-to-apply and practical way in cell therapy and tissue engineering when regulation of stem cells is required. Studies have shown that EMFs have positive effects on stem cell differentiation, accelerating its process regardless of the parameters and type of stem cells. However, the exact amplitude, frequency, duration of the electrical field, and application method remain elusive and need more study in future work.

New light‐travel time models and orbital stability study of the proposed planetary system HU Aquarii

Hinse, T. C.,Lee, J. W.,Goź,dziewski, K.,Haghighipour, N.,Lee, C.‐,U.,Scullion, E. M. Blackwell Publishing Ltd 2012 Monthly notices of the Royal Astronomical Society Vol.420 No.4

<P><B>ABSTRACT</B></P><P>In this work we propose a new orbital architecture for the two proposed circumbinary planets around the polar eclipsing binary HU Aquarii. We base the new two‐planet, light‐travel time model on the result of a Monte Carlo simulation driving a least‐squares Levenberg–Marquardt minimization algorithm on the observed eclipse egress times. Our best‐fitting model with <IMG src='/wiley-blackwell_img/equation/MNR_20283_mu1.gif' alt ='inline image'/> resulted in high final eccentricities for the two companions leading to an unstable orbital configuration. From a large ensemble of initial guesses, we examined the distribution of final eccentricities and semimajor axes for different <IMG src='/wiley-blackwell_img/equation/MNR_20283_mu2.gif' alt ='inline image'/> parameter intervals and encountered qualitatively a second population of best‐fitting parameters. The main characteristic of this population is described by low‐eccentric orbits favouring long‐term orbital stability of the system. We present our best‐fitting model candidate for the proposed two‐planet system and demonstrate orbital stability over one million years using numerical integrations.</P>

THE PROPOSED QUADRUPLE SYSTEM SZ HERCULIS: REVISED LITE MODEL AND ORBITAL STABILITY STUDY

Hinse, Tobias Cornelius,Goź,dziewski, Krzysztof,Lee, Jae Woo,Haghighipour, Nader,Lee, Chung-Uk American Institute of Physics 2012 The Astronomical journal Vol.144 No.2

<P>In a recent study, Lee et al. presented new photometric follow-up timing observations of the semidetached binary system SZ Herculis and proposed the existence of two hierarchical cirumbinary companions. Based on the light-travel time effect, the two low-mass M-dwarf companions are found to orbit the binary pair on moderate to high eccentric orbits. The derived periods of these two companions are close to a 2:1 mean-motion orbital resonance. We have studied the stability of the system using the osculating orbital elements as presented by Lee et al. Results indicate an orbit-crossing architecture exhibiting short-term dynamical instabilities leading to the escape of one of the proposed companions. We have examined the system's underlying model parameter space by following a Monte Carlo approach and found an improved fit to the timing data. A study of the stability of our best-fitting orbits also indicates that the proposed system is generally unstable. If the observed anomalous timing variations of the binary period is due to additional circumbinary companions, then the resulting system should exhibit a long-term stable orbital configuration much different from the orbits suggested by Lee et al. We, therefore, suggest that based on Newtonian-dynamical considerations, the proposed quadruple system cannot exist. To uncover the true nature of the observed period variations of this system, we recommend future photometric follow-up observations that could further constrain eclipse-timing variations and/or refine light-travel time models.</P>

The effect of collagen/polycaprolactone fibrous scaffold decorated with graphene nanoplatelet and low-frequency electromagnetic field on neuronal gene expression by stem cells

Moraveji, Marzie,Keshvari, Hamid,Karkhaneh, Akbar,Bonakdar, Shahin,Hadi, Amin,Haghighipour, Nooshin Techno-Press 2021 Advances in nano research Vol.10 No.6

This study aimed to develop a collagen/polycaprolactone (CP) fibrous scaffold decorated with Graphene (Gr) nanoplatelets (Gr-CP). In previous studies, accessibility of cells to the surface of Gr nanoplatelet was missed. Nanofibers were prepared by electrospinning which sprayed Gr nanoplatelets (1 wt.%) to synthesize the Gr-CP scaffold. Fourier transform infrared spectroscopy (FTIR) was utilized for investigation of chemical structure. Tensile tests were performed to study the influence of Gr on the mechanical properties of scaffolds. Cell differentiation was analyzed based on MAP2 and TUJ1 expression levels using real-time PCR technique in 6 groups. The variables examined in this experiment was the neural differentiating chemical medium, low-frequency electromagnetic field (LFEMF; 50Hz, 1mT) and Gr. Based on the results, Young's modulus, tensile strength and work of fracture ratio of the Gr-CP were 1.68, 2.41 and 1.42 times higher than those of the CP scaffold, respectively. MTT assay outcomes were indicative of scaffold cytocompatibility. The group treated with all three factors exhibited the highest MAP2 expression level compared to other groups. Based on the obtained results, exposing stem cells to the combined treatment of Gr and LFEMF can be used as a promising method to induce neuronal differentiation.

Induction of Chondrogenic Differentiation in Human Mesenchymal Stem Cells Cultured on Human Demineralized Bone Matrix Scaffold under Hydrostatic Pressure

Saeid Reza Shahmoradi,Maryam Kabir Salmani,Hamid Reza Soleimanpour,Amir Hossein Tavakoli,Kazem Hosaini,Nooshin Haghighipour,Shahin Bonakdar 한국조직공학과 재생의학회 2019 조직공학과 재생의학 Vol.16 No.1

BACKGROUND: Articular cartilage damage is still a troublesome problem. Hence, several researches have been performed for cartilage repair. The aim of this study was to evaluate the chondrogenicity of demineralized bone matrix (DBM) scaffolds under cyclic hydrostatic pressure (CHP) in vitro. METHODS: In this study, CHP was applied to human bone marrow mesenchymal stem cells (hBMSCs) seeded on DBM scaffolds at a pressure of 5 MPa with a frequency of 0.5 Hz and 4 h per day for 1 week. Changes in chondrogenic and osteogenic gene expressions were analyzed by quantifying mRNA signal level of Sox9, collagen type I, collagen type II, aggrecan (ACAN), Osteocalcin, and Runx2. Histological analysis was carried out by hematoxylin and eosin, and Alcian blue staining. Moreover, DMMB and immunofluorescence staining were used for glycosaminoglycan (GAG) and collagen type II detection, respectively. RESULTS: Real-time PCR demonstrated that applying CHP to hBMSCs in DBM scaffolds increased mRNA levels by 1.3-fold, 1.2-fold, and 1.7-fold (p\0.005) for Sox9, Col2, and ACAN, respectively by day 21, whereas it decreased mRNA levels by 0.7-fold and 0.8-fold (p\0.05) for Runx2 and osteocalcin, respectively. Additionally, in the presence of TGF-b1 growth factor (10 ng/ml), CHP further increased mRNA levels for the mentioned genes (Sox9, Col2, and ACAN) by 1.4-fold, 1.3-fold and 2.5-fold (p\0.005), respectively. Furthermore, in histological assessment, it was observed that the extracellular matrix contained GAG and type II collagen in scaffolds under CHP and CHP with TGF-b1, respectively. CONCLUSION: The osteo-inductive DBM scaffolds showed chondrogenic characteristics under hydrostatic pressure. Our study can be a fundamental study for the use of DBM in articular cartilage defects in vivo and lead to production of novel scaffolds with two different characteristics to regenerate both bone and cartilage simultaneously.

KEPLER-1647B: THE LARGEST AND LONGEST-PERIOD<i>KEPLER</i>TRANSITING CIRCUMBINARY PLANET

Kostov, Veselin B.,Orosz, Jerome A.,Welsh, William F.,Doyle, Laurance R.,Fabrycky, Daniel C.,Haghighipour, Nader,Quarles, Billy,Short, Donald R.,Cochran, William D.,Endl, Michael,Ford, Eric B.,Gregori American Astronomical Society 2016 The Astrophysical journal Vol.827 No.1

<P>We report the discovery of a new Kepler transiting circumbinary planet (CBP). This latest addition to the stillsmall family of CBPs defies the current trend of known short-period planets orbiting near the stability limit of binary stars. Unlike the previous discoveries, the planet revolving around the eclipsing binary system Kepler-1647 has a very long orbital period (similar to 1100 days) and was at conjunction only twice during the Kepler mission lifetime. Due to the singular configuration of the system, Kepler-1647b is not only the longest-period transiting CBP at the time of writing, but also one of the longest-period transiting planets. With a radius of 1.06 +/- 0.01 RJup, it is also the largest CBP to date. The planet produced three transits in the light curve of Kepler-1647 (one of them during an eclipse, creating a syzygy) and measurably perturbed the times of the stellar eclipses, allowing us to measure its mass, 1.52 +/- 0.65M(Jup). The planet revolves around an 11-day period eclipsing binary consisting of two solar-mass stars on a slightly inclined, mildly eccentric (e(bin) = 0.16), spin-synchronized orbit. Despite having an orbital period three times longer than Earth's, Kepler-1647b is in the conservative habitable zone of the binary star throughout its orbit.</P>