3,556 research outputs found
Alcohol-dysregulated microRNAs in hepatitis B virus-related hepatocellular carcinoma.
No full textAlcohol consumption and chronic hepatitis B virus (HBV) infection are two well-established risk factors for Hepatocellular carcinoma (HCC); however, there remains a limited understanding of the molecular pathway behind the pathogenesis and progression behind HCC, and how alcohol promotes carcinogenesis in the context of HBV+ HCC. Using next-generation sequencing data from 130 HCC patients and 50 normal liver tissues, we identified a panel of microRNAs that are significantly dysregulated by alcohol consumption in HBV+ patients. In particular, two microRNAs, miR-944 and miR-223-3p, showed remarkable correlation with clinical indication and genomic alterations. We confirmed the dysregulation of these two microRNAs in liver cell lines treated by alcohol and acetaldehyde, and showed that manipulation of miR-223-3p and miR-944 expression induces significant changes in cellular proliferation, sensitivity to doxorubicin, and the expression of both direct-binding and downstream mRNA targets. Together, the results of this study suggest that alcohol consumption in HBV+ HCCs regulates microRNAs that likely play previously uncharacterized roles in the alcohol-associated carcinogenesis of HCC, and future studies of these microRNAs may be valuable for furthering the understanding and treatment of alcohol and HBV-associated HCC
Hubungan Antara Ukuran Partikel Pada Pembuatan Bonded Permanen Magnet Nd-Fe-B Terhadap Struktur Mikro dan Sifat Magnet
No full textA study concerning the manufacture of bonded NdFeB magnet type MQP-B + by
looking at the relationship between particle size on the microstructure and
magnetic properties. The process of making permanent magnets bonded Nd-Fe-B
with a matrix of polyvinyl chloride type KH-10 made by mixing powder
Neodymium Iron Boron (Nd-Fe-B) type commercial MQP-B + which has been
sieved using a mesh fluorsifiyer. Each is Original Powder particle size and
particle size sieve 50, 100, 200, and 325 mesh. Polyvinyl chloride composition of
2% by weight of the total sample mass of 3 grams. The mixture is then molded by
compression molding method of cleaning with pressure 40 MPa and the samples
were dried at 150 ºC for 30 minutes in argon environment. Microstructure
characterization using Scanning Electron Microscopy (SEM) and X-Ray
Diffraction (XRD). Magnetic properties were characterized using Gaussmeter
and Permagraph to determine the field strength and hysteresis curves. The results
showed that the smaller particle size, the increasing value of the density but does
not affect the value of the magnetic field strength. The best magnetic properties on
particle size of 100 mesh sieve, produces the bulk value of 6,47 g/cm3
and denstity
value = 2332 gauss field strength, Br = 6,12 kG, Hcj = 8,450 kOe, BHmax = 7,43
MGOe.72 HalamanSkripsi Sarjan
Abstract 66: c-Fos: A new player in promotion of cancer stem-like cell properties in head and neck squamous cell carcinoma
No full textAbstract
Head and neck squamous cell carcinoma (HNSCC) is the sixth most common cancer worldwide. We have shown that c-Fos was highly up-regulated in the HNSCC sphere forming cells. However, upregulation of c-Fos for the biology of HNSCC-CSCs remains unknown. In this study, we investigated the role of c-Fos in renewal of stemness of HNSCC and tumor growth.
We demonstrated that c-Fos overexpression enhanced the epithelial-mesenchymal transition (EMT) state and expression of CSC markers (Nanog, c-Myc, Sox2 and Notch1). Ectopic expression of c-Fos in HNSCC cells also display increased number of sphere formation. We further observed that overexpression of c-Fos increased the expression of pERK and cyclin D1 in HNSCC cells. Knockdown of c-Fos in Cal27 cells impaired sphere formation. Next we examine the effect of c-Fos expression in vivo. For this, we established stable HNSCC cell line (MDA1386Tu cells) where c-Fos gene is ectopically expressed. Our results demonstrated that exogenous expression of c-Fos in non-tumorigenic MDA1386Tu cells makes these cells tumorigenic in nude mice. Further, subcutaneous transplantation of c-Fos overexpressing Cal27 cells (tumorigenic) into immunocompromised mice enhanced tumor growth as compared to parental cells. Taken together, our results strongly demonstrated a novel role of c-Fos as a regulator of EMT and cancer stem cell reprogramming in HNSCC cells.
Collectively, our results offer that c-Fos may be a new target for developing therapeutic strategies against HNSCC.
Citation Format: Ratna B. Ray. c-Fos: A new player in promotion of cancer stem-like cell properties in head and neck squamous cell carcinoma [abstract]. In: Proceedings of the AACR-AHNS Head and Neck Cancer Conference: Optimizing Survival and Quality of Life through Basic, Clinical, and Translational Research; April 23-25, 2017; San Diego, CA. Philadelphia (PA): AACR; Clin Cancer Res 2017;23(23_Suppl):Abstract nr 66.</jats:p
New insights on accretion in supergiant fast X-ray transients from XMM-Newton and INTEGRAL observations of IGR J17544-2619
No full textXMM–Newton observations of the supergiant fast X-ray transient IGR J17544?2619 are reported and placed in the context of an analysis of archival INTEGRAL/IBIS data that provide a refined estimate of the orbital period at 4.9272?±?0.0004?d. A complete outburst history across the INTEGRAL mission is reported. Although the new XMM–Newton observations (each lasting ?15 ks) targeted the peak flux in the phase-folded hard X-ray light curve of IGR J17544?2619, no bright outbursts were observed, the source spending the majority of the exposure at intermediate luminosities of the order of several 1033?erg?s?1 (0.5–10 keV) and displaying only low level flickering activity. For the final portion of the exposure, the luminosity of IGR J17544?2619 dropped to ?4?×?1032?erg?s?1 (0.5–10 keV), comparable with the lowest luminosities ever detected from this source, despite the observations being taken near to periastron. We consider the possible orbital geometry of IGR J17544?2619 and the implications for the nature of the mass transfer and accretion mechanisms for both IGR J17544?2619 and the supergiant fast X-ray transients (SFXTs) population. We conclude that accretion under the ‘quasi-spherical accretion’ model provides a good description of the behaviour of IGR J17544?2619 and suggests an additional mechanism for generating outbursts based upon the mass accumulation rate in the hot shell (atmosphere) that forms around the neutron star under the quasi-spherical formulation. Hence, we hope to aid in explaining the varied outburst behaviours observed across the SFXT population with a consistent underlying physical model
A 2 h periodic variation in the low-mass X-ray binary Ser X-1
No full textSpectroscopy of the low-mass X-ray binary Ser X-1 using the Gran Telescopio Canarias have revealed a ?2 h periodic variability that is present in the three strongest emission lines. We tentatively interpret this variability as due to orbital motion, making it the first indication of the orbital period of Ser X-1. Together with the fact that the emission lines are remarkably narrow, but still resolved, we show that a main-sequence K dwarf together with a canonical 1.4 M? neutron star gives a good description of the system. In this scenario, the most likely place for the emission lines to arise is the accretion disc, instead of a localized region in the binary (such as the irradiated surface or the stream-impact point), and their narrowness is due instead to the low inclination (?10°) of Ser X-1
Active X-ray optics for the next generation of X-ray space telescopes
No full textDescribed within is the design, manufacture, metrology and X-ray testing of an active X-ray
prototype intended for the next generation of X-ray telescopes. One of the challenges faced by
the X-ray telescope community is how to combine high resolution and high sensitivity into one
system, as weight limitations place constraints on the optics that can be launched. Therefore the
mandate of the active X-ray prototype is to provide high sensitivity through the ability of the optics
to be nested and to deliver high angular resolution through the active control of the optic’s form.
Piezoelectric unimorph actuators provide the active component: it is intended that they will correct
for figure errors within the optic and therefore increase the angular resolution capability.
The prototype’s design is based upon an ellipsoidal segment which provides point-to-point
focussing of an X-ray source. The prototype itself is composed of an electroformed nickel optic
where the non-reflective surface is populated with 30 piezoelectric actuators and it is the production
of the prototype that is the core of the presented research. Metrology of the actuators’ influence
functions is presented and highlight the prototype’s ability to deform its optic surface by microns.
In addition, the measured influence functions are compared against finite element models and a
distinct similarity between the functions is observed.
The prototype was tested at an X-ray beamline facility in November 2008 and the results
showed the prototype’s ability to correct the optic to achieve an improved angular resolution: from
0.786 arc-minutes to 0.686 arc-minutes in terms of full width half maximum. Finally, difficulties
in the manufacture of the prototype and X-ray testing shall be presented alongside future work in
conclusion to this thesis
Correlated X-ray/ultraviolet/optical variability in the very low mass AGN NGC 4395
No full textWe report the results of a 1-yr Swift X-ray/ultraviolet (UV)/optical programme monitoring the dwarf Seyfert nucleus in NGC4395 in 2008-2009. The UV/optical flux from the nucleus was found to vary dramatically over the monitoring period, with a similar pattern of variation in each of the observed UV/optical bands (spanning 1900-5500 Å). In particular, the luminosity of NGC4395 in the 1900 Å band changed by more than a factor of 8 over the monitoring period. The fractional variability was smaller in the UV/optical bands than that seen in the X-rays, with the X-ray/optical ratio increasing with increasing flux. Pseudo-instantaneous flux measurements in the X-ray and each UV/optical band were well correlated, with cross-correlation coefficients of ≥0.7, significant at 99.9per cent confidence. Archival Swift observations from 2006 sample the intra-day X-ray/optical variability on NGC4395. These archival data show a very strong correlation between the X-ray and b bands, with a cross-correlation coefficient of 0.84 (significant at >99per cent confidence). The peak in the cross-correlation function is marginally resolved and asymmetric, suggesting that X-rays lead the b band, but by ≤1h. In response to recent (2011 August) very high X-ray flux levels from NGC4395 we triggered Swift target of opportunity observations, which sample the intra-hour X-ray/UV variability. These observations indicate, albeit with large uncertainties, a lag of the 1900 Å band behind the X-ray flux of ∼400s. The tight correlation between the X-ray and UV/optical lightcurves, together with the constraints we place on the lag time-scale, is consistent with the UV/optical variability of NGC4395 being primarily due to reprocessing of X-ray photons by the accretion disc
What went missing: a case study of faculty and organizational elements necessary to sustain university-based service learning programs
No full textPurpose Service learning, an innovative program that combines community service with academic course content, has achieved a new vibrancy under President Obama. Over 1,100 colleges and universities are now involved in some form of community service, an increase of over 50% in the last 10 years. Despite the reported positive impact of such programs by faculty and students, little research is available on how to create and sustain a service learning program. This qualitative case study sought to understand some of these implementation issues through an examination of a failed service learning program at a regional university in the Northeast. Research Questions 1. How do faculty members describe their participation in the service learning program at Korbet University? 2. How do faculty members describe the organizational context for service learning at Korbet University? iii 3. From the faculty descriptions, what contributed to the failure of the service learning program at Korbet University? Methodology This case study utilized interviews with a purposeful sample of 15 faculty and reviewed documents to build an understanding of why the service learning program failed. To analyze the data record, a number of phases were utilized, including coding and subcoding, looking for evidence and relationships across the codes to develop categories that reflected the literature and research questions, and finally, “selecting data excerpts” (Hatch, 2002, p. 159) to illuminate the final themes. Findings The failure of service learning in this site was attributed to several interrelated factors. These factors were changing leadership, the undermining of organizational structures, and declining resources to support the implementation of service learning. As the organizational context became less supportive of service learning, faculty participation decreased until service learning was a program in name only. The findings corroborate those of organizational change experts that suggest it is the phase of implementing or continuing a new program rather than the innovative stage that typically leads to its demise. Significance Although this study is limited by the case of one service learning program, it is significant, in part, because it is based on issues surrounding programmatic decline and failure rather than success. It is noteworthy because it tried to understand from those involved in the program what went wrong. The study is also significant in that it examined organizational change and how innovations impact participants and organizational context.Ed.D.Includes bibliographical referencesby Ray B. For
X-ray polarization in relativistic jets
No full textWe investigate the polarization properties of Comptonized X-rays from relativistic jets in active galactic nuclei (AGN) using Monte Carlo simulations. We consider three scenarios commonly proposed for the observed X-ray emission in AGN: Compton scattering of blackbody photons emitted from an accretion disc; scattering of cosmic microwave background (CMB) photons and self-Comptonization of intrinsically polarized synchrotron photons emitted by jet electrons. Our simulations show that for Comptonization of disc and CMB photons, the degree of polarization of the scattered photons increases with the viewing inclination angle with respect to the jet axis. In both cases, the maximum linear polarization is ≈20 per cent. In the case of synchrotron self-Comptonization (SSC), we find that the resulting X-ray polarization depends strongly on the seed synchrotron photon injection site, with typical fractional polarizations P≈ 10–20 per cent when synchrotron emission is localized near the jet base, while P≈ 20–70 per cent for the case of uniform emission throughout the jet. These results indicate that X-ray polarimetry may be capable of providing unique clues to identify the location of particle acceleration sites in relativistic jets. In particular, if synchrotron photons are emitted quasi-uniformly throughout a jet, then the observed degree of X-ray polarization may be sufficiently different for each of the competing X-ray emission mechanisms (synchrotron, SSC or external Comptonization) to determine which is the dominant process. However, X-ray polarimetry alone is unlikely to be able to distinguish between disc and CMB Comptonization
The nature of the X-ray transient MAXI J0556−332
No full textPhase-resolved spectroscopy of the newly discovered X-ray transient MAXIJ0556-332 has revealed the presence of narrow emission lines in the Bowen region that most likely arise on the surface of the mass donor star in this low-mass X-ray binary. A period search of the radial velocities of these lines provides two candidate orbital periods (16.43 ± 0.12 and 9.754 ± 0.048h), which differ from any potential X-ray periods reported. Assuming that MAXIJ0556-332 is a relatively high-inclination system that harbours a precessing accretion disc in order to explain its X-ray properties, it is only possible to obtain a consistent set of system parameters for the longer period. These assumptions imply a mass ratio of q≃ 0.45, a radial velocity semi-amplitude of the secondary of K 2≃ 190kms -1 and a compact object mass of the order of the canonical neutron star mass, making a black hole nature for MAXIJ0556-332 unlikely. We also report the presence of strong Niii emission lines in the spectrum, thereby inferring a high N/O abundance. Finally, we note that the strength of all emission lines shows a continuing decay over the ≃1 month of our observations
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