225 research outputs found

    Factors influencing engineering students for choosing techno-entrepreneurship as a career: An implication for better learning

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    Techno-entrepreneurship is critical to the growth of society as a useful technique for overcoming youth unemployment. However, the growth of techno-entrepreneurship has been limited with the end outcome being less than satisfying. Hence, the purpose of this study was to determine the factors that influence the possibility of choosing techno-entrepreneurship as a profession among engineering students in the Philippines. There were 200 engineering students selected by stratified random sampling and the significance of the factors was then determined using Pearson correlation analysis. Based on the findings, students’ likelihood of choosing techno-entrepreneurship as a career was not influenced by their equipment availability but by their e-commerce experience, geographical location, and internet ability. This implies the need for academic personnel and instructors teaching techno-entrepreneurship courses to guarantee students have relevant technopreneur knowledge, skills, and competencies that value students’ creativity and innovation to encourage techno-entrepreneurship as a profession

    A New Spectroscopic and Photometric Analysis of the Transiting Planet Systems TrES-3 and TrES-4

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    We report new spectroscopic and photometric observations of the parent stars of the recently discovered transiting planets TrES-3 and TrES-4. A detailed abundance analysis based on high-resolution spectra yields [Fe/H] = –0.19 ± 0.08, T_(eff) = 5650 ± 75 K, and log g = 4.4 ± 0.1 for TrES-3, and [Fe/H] = +0.14 ± 0.09, T_(eff) = 6200 ± 75 K, and log g = 4.0 ± 0.1 for TrES-4. The accuracy of the effective temperatures is supported by a number of independent consistency checks. The spectroscopic orbital solution for TrES-3 is improved with our new radial velocity measurements of that system, as are the light-curve parameters for both systems based on newly acquired photometry for TrES-3 and a reanalysis of existing photometry for TrES-4. We have redetermined the stellar parameters taking advantage of the strong constraint provided by the light curves in the form of the normalized separation a/R_* (related to the stellar density) in conjunction with our new temperatures and metallicities. The masses and radii we derive are M_* = 0.928^(+0.028)_(–0.048) M_⊙, R_* = 0.829^(+0.015)_(–0.022) R_⊙, and M_* = 1.404^(+0.066)_(–0.134) M_⊙, R_* = 1.846^(+0.096)_(–0.087) R_⊙ for TrES-3 and TrES-4, respectively. With these revised stellar parameters, we obtain improved values for the planetary masses and radii. We find M_p = 1.910^(+0.075)_(–0.080) M_(Jup), R_p = 1.336^(+0.031)_(–0.036) R_(Jup) for TrES-3, and M_p = 0.925 ± 0.082 M_(Jup), R_p = 1.783^(+0.093)_(–0.086) R_(Jup) for TrES-4. We confirm TrES-4 as the planet with the largest radius among the currently known transiting hot Jupiters

    TrES-2: The First Transiting Planet in the Kepler Field

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    We announce the discovery of the second transiting hot Jupiter discovered by the Trans-atlantic Exoplanet Survey. The planet, which we dub TrES-2, orbits the nearby star GSC 03549-02811 every 2.47063 days. From high-resolution spectra, we determine that the star has T_eff = 5960 +/- 100 K and log(g) = 4.4 +/- 0.2, implying a spectral type of G0V and a mass of 1.08 +0.11/-0.05 M_sun. High-precision radial-velocity measurements confirm a sinusoidal variation with the period and phase predicted by the photometry, and rule out the presence of line-bisector variations that would indicate that the spectroscopic orbit is spurious. We estimate a planetary mass of 1.28 +0.09/-0.04 M_Jup. We model B, r, R, and I photometric timeseries of the 1.4%-deep transits and find a planetary radius of 1.24 +0.09/-0.06 R_Jup. This planet lies within the field of view of the NASA Kepler mission, ensuring that hundreds of upcoming transits will be monitored with exquisite precision and permitting a host of unprecedented investigations.Comment: Accepted for publication in ApJL. 15 pages, 2 figure

    Short climatic changes in the Central Pyrenees at the end of the Upper Pleistocene and Holocene from stalagmite records in the Seso Cave (Huesca, Spain)

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    Las estalagmitas de la cueva de Seso (Boltaña, provincia de Huesca) registran cambios climĂĄticos cortos durante el final del Pliestoceno superior y el Holoceno los Pirineos centrales. Mediante U/Th se diferencian seis fases de crecimiento estalagmĂ­tico (12.9-11.5 ka, 9.1-8.3 ka, 6.3-6.2 ka, 3.0-2.5 ka, 1.8-1.4 ka y 0.6-0.2 ka) que se correlacionan con etapas frĂ­as y/o hĂșmedas a escala regional. Los datos isotĂłpicos (ÎŽ18O y ÎŽ13C) indican que durante el Younger Dryas las condiciones fueron mĂĄs frĂ­as y ĂĄridas que durante el HolocenoThe Seso Cave (Boltaña, Huesca province) in the Pyrenees houses stalagmites recording climate variability during the end of Upper Pleistocene and Holocene times. Six growing periods have been deduced by U/Th dating at 12.9-11.5 ka, 9.1-8.3 ka, 6.3-6.2 ka, 3.0-2.5 ka, 1.8-1.4 ka and 0.6-0.2 ka, respectively. These intervals correspond to cold and/or wet short climate changes identified at a regional scale. Isotopic data (ÎŽ18O and ÎŽ13C) indicate that environmental conditions during the Younger Dryas were cooler and drier than in the Holocen

    The origin of slow electron recombination processes in dye-sensitized solar cells with alumina barrier coatings

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    We investigate the effect of a thin alumina coating of nanocrystalline TiO2 films on recombination dynamics of dye-sensitized solar cells. Both coated and uncoated cells were measured by a combination of techniques: transient absorption spectroscopy, electrochemical impedance spectroscopy, and open-circuit voltage decay. It is found that the alumina barrier reduces the recombination of photoinjected electrons to both dye cations and the oxidized redox couple. It is proposed that this observed retardation can be attributed primarily to two effects: almost complete passivation of surface trap states in TiO2 that are able to inject electrons to acceptor species, and slowing down by a factor of 3–4 the rate of interfacial charge transfer from conduction-band [email protected]

    Efficient generation of A9 midbrain dopaminergic neurons by lentiviral delivery of LMX1A in human embryonic stem cells and Induced Pluripotent Stem Cells

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    Human embryonic stem cells (hESC) and induced pluripotent stem cells (iPSC) offer great hope for in vitro modeling of Parkinson's disease (PD), as well as for designing cell-replacement therapies. To realize these opportunities, there is an urgent need to develop efficient protocols for the directed differentiation of hESC/iPSC into dopamine (DA) neurons with the specific characteristics of the cell population lost to PD, i.e., A9-subtype ventral midbrain DA neurons. Here we use lentiviral vectors to drive the expression of LMX1A, which encodes a transcription factor critical for ventral midbrain identity, specifically in neural progenitor cells. We show that clonal lines of hESC engineered to contain one or two copies of this lentiviral vector retain long-term self-renewing ability and pluripotent differentiation capacity. Greater than 60% of all neurons generated from LMX1A-engineered hESC were ventral midbrain DA neurons of the A9 subtype, compared with ∌10% in green fluorescent protein engineered controls, as judged by specific marker expression and functional analyses. Moreover, DA neuron precursors differentiated from LMX1A-engineered hESC were able to survive and differentiate when grafted into the brain of adult mice. Finally, we provide evidence that LMX1A overexpression similarly increases the yield of DA neuron differentiation from human iPSC. Taken together, our data show that stable genetic engineering of hESC/iPSC with lentiviral vectors driving controlled expression of LMX1A is an efficient way to generate enriched populations of human A9-subtype ventral midbrain DA neurons, which should prove useful for modeling PD and may be helpful for designing future cell-replacement strategies

    Histone Acetylation-Mediated Regulation of the Hippo Pathway

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    The Hippo pathway is a signaling cascade recently found to play a key role in tumorigenesis therefore understanding the mechanisms that regulate it should open new opportunities for cancer treatment. Available data indicate that this pathway is controlled by signals from cell-cell junctions however the potential role of nuclear regulation has not yet been described. Here we set out to verify this possibility and define putative mechanism(s) by which it might occur. By using a luciferase reporter of the Hippo pathway, we measured the effects of different nuclear targeting drugs and found that chromatin-modifying agents, and to a lesser extent certain DNA damaging drugs, strongly induced activity of the reporter. This effect was not mediated by upstream core components (i.e. Mst, Lats) of the Hippo pathway, but through enhanced levels of the Hippo transducer TAZ. Investigation of the underlying mechanism led to the finding that cancer cell exposure to histone deacetylase inhibitors induced secretion of growth factors and cytokines, which in turn activate Akt and inhibit the GSK3 beta associated protein degradation complex in drug-affected as well as in their neighboring cells. Consequently, expression of EMT genes, cell migration and resistance to therapy were induced. These processes were suppressed by using pyrvinium, a recently described small molecule activator of the GSK 3 beta associated degradation complex. Overall, these findings shed light on a previously unrecognized phenomenon by which certain anti-cancer agents may paradoxically promote tumor progression by facilitating stabilization of the Hippo transducer TAZ and inducing cancer cell migration and resistance to therapy. Pharmacological targeting of the GSK3 beta associated degradation complex may thus represent a unique approach to treat cancer. © 2013 Basu et al
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