2,435 research outputs found

    The Stellar Population of Lyman-alpha Emitting Galaxies at z ~ 5.7

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    We present a study of three Lyman-alpha emitting galaxies (LAEs), selected via a narrow-band survey in the GOODS northern field, and spectroscopically confirmed to have redshifts of z ~ 5.65. Using HST ACS and Spitzer IRAC data, we constrain the rest-frame UV-to-optical spectral energy distributions (SEDs) of the galaxies. Fitting stellar population synthesis models to the observed SEDs, we find best-fit stellar populations with masses between ~ 10^9 - 10^10 M_sun and ages between ~ 5 - 100 Myr, assuming a simple starburst star formation history. However, stellar populations as old as 700 Myr are admissible if a constant star formation rate model is considered. Very deep near-IR observations may help to narrow the range of allowed models by providing extra constraints on the rest-frame UV spectral slope. Our narrow-band selected objects and other IRAC-detected z ~ 6 i'-dropout galaxies have similar 3.6 um magnitudes and z' - [3.6] colors, suggesting that they posses stellar populations of similar masses and ages. This similarity may be the result of a selection bias, since the IRAC-detected LAEs and i'-dropouts probably only sample the bright end of the luminosity function. On the other hand, our LAEs have blue i' - z' colors compared to the i'-dropouts, and would have been missed by the i'-dropout selection criterion. A better understanding of the overlap between the LAE and the i'-dropout populations is necessary in order to constrain the properties of the overall high-redshift galaxy population, such as the total stellar mass density at z ~ 6.Comment: 10 pages, 8 figures. Accepted for publication in Ap

    System Design and Implementation of Smart Dashboard for Electric Vehicles

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    Recently, the development of automobile focuses on the chassis structure and motion control. However, due to the concept of smart and safe vehicle, the integrated dashboard becomes a necessary issue. The proposed system can not only represent the conventional dashboard in a digital form but also endow the system with an intelligent guidance. The statuses such as speed, battery SOC, braking, mileage, and the activation of TCS and ABS can be seen and monitored in all driving scenarios. For example, the current modern electric vehicles face the danger of self-ignition problem when the over load problem is consisted. Basically, these severe conditions can be eliminated by a guard of smart interface. Consequently, under a proper design, the presented system can assist the driver to maintain the energy efficiency, steering stability, and so on. Then the operation procedure can be simplified and hence driver can concentrate more on steering

    The heme-p53 interaction: Linking iron metabolism to p53 signaling and tumorigenesis

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    Recently, we reported that heme binds to tumor suppressor p53 protein (TP53, best known as p53) and promotes its nuclear export and cytosolic degradation, whereas iron chelation stabilizes p53 protein and suppresses tumors in a p53-dependent manner. This not only provides mechanistic insights into tumorigenesis associated with iron excess, but also helps guide the administration of chemotherapy based on iron deprivation in the clinic

    Quasispecies distribution of Eigen model

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    We study sharp peak landscapes (SPL) of Eigen model from a new perspective about how the quasispecies distribute in the sequence space. To analyze the distribution more carefully, we bring forth two tools. One tool is the variance of Hamming distance of the sequences at a given generation. It not only offers us a different avenue for accurately locating the error threshold and illustrates how the configuration of the distribution varies with copying fidelity qq in the sequence space, but also divides the copying fidelity into three distinct regimes. The other tool is the similarity network of a certain Hamming distance d0d_{0}, by which we can get a visual and in-depth result about how the sequences distribute. We find that there are several local optima around the center (global optimum) in the distribution of the sequences reproduced near the threshold. Furthermore, it is interesting that the distribution of clustering coefficient C(k)C(k) follows lognormal distribution and the curve of clustering coefficient CC of the network versus d0d_{0} appears as linear behavior near the threshold.Comment: 13 pages, 6 figure

    Enteral supplementation of alanyl–glutamine attenuates the up-regulation of beta-defensin-2 protein in lung injury induced by intestinal ischemia reperfusion in rats

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    AbstractBackground: Beta-defensin-2 (BD-2), an endogenous antimicrobial peptide, plays a key role in immune response against microbial invasion. This study aimed to observe the effect of Alanyl–Glutamine (Ala–Gln) on BD-2 protein expression in pulmonary tissues after intestinal ischemia reperfusion (IIR) in rats and to investigate its correlations to pulmonary inflammatory and oxidative injury. Methods: Rats in IIR and the two treatment groups were subjected to intestine ischemia for 60 min and those in the treatment groups were administered orally with Ala–Gln or alanine (Ala) respectively. Lung tissues were harvested to detect the BD-2 protein expression. Concentrations of Tumor necrosis factor (TNF)-α and malondialdehyde (MDA) as well as superoxide dismutase (SOD) activity in lung tissues were determined simultaneously. Results: Ala–Gln attenuated the up-regulation of BD-2 expression (p < 0.05) and TNF-α (p < 0.05), MDA (p < 0.05) levels, as well as the reduction of SOD activity (p < 0.05) in lung tissues after IIR. But Ala did not exert significant effects. BD-2 protein in lung tissues was positively correlated to local TNF-α level (p < 0.01) and MDA concentration (p < 0.01) with statistical significance. Conclusion: Ala–Gln can relieve the IIR-induced up-regulation of BD-2 protein expression in the lung of rats, which involves anti-inflammation and anti-oxidation mechanisms

    Fucoxanthin-Rich Brown Algae Extract Decreases Inflammation and Attenuates Colitis-associated Colon Cancer in Mice

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    Abstract Fucoxanthin is a natural carotenoid that is isolated from seaweed. We evaluated the effects of fucoxanthin-rich brown algae extract (FX-BAE) on the development of dextran sulfate sodium (DSS)-induced colitis, and colitis-associated colon cancer (CACC) in BALB/c mice. Colitis mice were given drinking water containing 3% DSS for 14 days, and fed with or without FX-BAE (1, 2.5, or 5 g/kg bodyweight/day) from day 8 to day 14. Another way, CACC mice were treated with azoxymethane (AOM) and 2% DSS, and fed with or without FX-BAE at 0.5, 1, or 2.5 g/kg every 2 days. Results revealed the disease activity index (DAI), nitric oxide (NO), malondialdehyde (MDA), tumor necrosis factor-alpha (TNF-α), and interleukin-6 (IL-6) were all significantly less in FX-BAE treated mice. Additionally, FX-BAE not only decreased the incidence of colonic neoplasm, but also increased superoxide dismutase (SOD) production, lymphocyte proliferation and survival rate in CACC mice

    A hybrid microfluidic-vacuum device for direct interfacing with conventional cell culture methods

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    <p>Abstract</p> <p>Background</p> <p>Microfluidics is an enabling technology with a number of advantages over traditional tissue culture methods when precise control of cellular microenvironment is required. However, there are a number of practical and technical limitations that impede wider implementation in routine biomedical research. Specialized equipment and protocols required for fabrication and setting up microfluidic experiments present hurdles for routine use by most biology laboratories.</p> <p>Results</p> <p>We have developed and validated a novel microfluidic device that can directly interface with conventional tissue culture methods to generate and maintain controlled soluble environments in a Petri dish. It incorporates separate sets of fluidic channels and vacuum networks on a single device that allows reversible application of microfluidic gradients onto wet cell culture surfaces. Stable, precise concentration gradients of soluble factors were generated using simple microfluidic channels that were attached to a perfusion system. We successfully demonstrated real-time optical live/dead cell imaging of neural stem cells exposed to a hydrogen peroxide gradient and chemotaxis of metastatic breast cancer cells in a growth factor gradient.</p> <p>Conclusion</p> <p>This paper describes the design and application of a versatile microfluidic device that can directly interface with conventional cell culture methods. This platform provides a simple yet versatile tool for incorporating the advantages of a microfluidic approach to biological assays without changing established tissue culture protocols.</p

    Coupled CRLH transmission lines for compact and high selectivity bandpass filters

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    A compact size and high selective bandpass filter is presented in this paper. The filter is designed to serve at 3.5 GHz with two transmission zeros at 3.35 GHz and 3.85 GHz. The filter is designed as two gap capacitor coupled to two coupled composite right–left handed transmission lines. The coupled lines were designed to demonstrate a zeroth order phase at 3.5 GHz. Also, the transmission zeros were achieved as a consequence of the electrical/magnetic couplings between the two coupled transmission lines. The employed cell, filter design equations are emphasized. The filter S-parameters were extracted based on the circuit model, full wave simulation, and experimental measurements. A good agreement between modeled, simulated, and measured results is achieved. The measured center frequency of the bandpass filter is 3.55 GHz and 100 MHz bandwidth which is suitable for WiMAX applications. Also, the filter has low measured insertion loss which does not exceed 1 dB within passband. Finally, the filter has advantages of compactness (size is 20 3 18 mm2) which is only 50% compared to conventional non-selective one-stage coupled line filter
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