559 research outputs found

    Review of \u3cem\u3eVision and Aging: Crossroads for Service Delivery.\u3c/em\u3e Albert L. Orr. Reviewed by James A. Leja, Western Michigan University.

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    Orr, Alberta L., Vision and Aging: Crossroads for Service Delivery. New York: American Foundation for the Blind. 1992. $29.95 papercover

    Bound water structure on the surfaces of Usnea antarctica as observed by NMR and sorption isotherm

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    Hydration courses and proton free induction decays are recorded at 30 MHz for Usnea antarctica thalli hydrated from gaseous phase. NMR data combined with gravimetry allow one to distinguish two fractions of tightly bound water, and loosely bound/free water pool. No water fraction "sealed" in thallus structures is present in U. antarctica

    Performance evaluation of commercial sesame (Sesamum indicum L.) cultivars for yield and yield related traits in Wolaita, Southern Ethiopia

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    Sesame (Sesamum indicum L.) is cultivated in Ethiopia as a cash crop, export commodity, and raw material for sesame oil industries. It has surged up as a silver line regarding its contribution to the export earnings for Ethiopians. Sesame cultivation was not widely known in Wolaita area although the area could be a potential cultivation location for wider production of sesame in the country. Therefore, to evaluate performance in terms of yield and yield related traits for selection of the best performing cultivars to enhance productivity and larger production, ten sesame cultivars were laid out in a randomized complete block design with three replications at two districts (Humbo and Kindo-Koysha) for two years (2017-2018). Analysis of variance showed that cultivars Mehado-80 (154 cm), Adi (153 cm), and Tate (149 cm) have grown to significantly higher heights over the rest of the cultivars. Mehado-80 and Tate had a significantly higher number of primary branches (mean values across locations 9.3, 8.7 and 8.6, respectively). The cultivar Tate had the highest number of capsules (97.9) per plant, which had also the highest genotypic variation (428.54). The highest genotypic coefficient of variance (45.58%) was recorded for seed yield. Days to 50% flowering and 90% maturity exhibited the lowest phenotypic coefficient of variation, 7.16%, and 3.69%, respectively. Heritability in a broad sense (h2b) ranged from 13.32% for plant height to 32.43% for thousand seed weight. The interaction effects had showed no significant difference (P>0.05) for most of the studied traits. Cultivars Tate (1200 kg/ha), Serkamo (917 kg/ha) and Kelafo-74 (875 kg/ha) scored significantly higher seed yield at Kindo-Koysha site whereas Tate (1208 kg/ha, S (1042 kg/ha) and Mehado-80 (1021 kg/ha) scored significantly higher seed yield at Humbo site. Hence these cultivars could, respectively, be used as a potential cultivar for Kindo-Koysha and Humbo districts of Wolaita zone, while cultivar Tate exhibited the highest seed yield at both locations and hence recommended for Wolaita zone, southern Ethiopia

    Constraints for the X17 boson from compacts objects observations

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    We investigate the hypothetical X17 boson on neutron stars and Quark Stars (QSs) using various hadronic Equation of States (EoSs) with phenomenological or microscopic origin. Our aim is to set realistic constraints on its coupling constant and the mass scaling, with respect to causality and various possible upper mass limits and the dimensionless tidal deformability Λ1.4\Lambda_{1.4}. In particular, we pay special attention on two main phenomenological parameters of the X17, the one is related to the coupling constant g\mathrm{g} that it has with hadrons or quarks and the other with the in-medium effects through the regulator C\mathrm{C}. Both are very crucial concerning the contribution on the total energy density and pressure. In the case of considering the X17 as a carrier of nuclear force in Relativistic Mean Field (RMF) theory, an admixture into vector boson segment was constrained by 20\% and 30\%. In our investigation, we came to the general conclusion that the effect of the hypothetical X17 both on neutron and QSs constrained mainly by the causality limit, which is a specific property of each EoS. Moreover, it depends on the interplay between the main two parameters that is the interaction coupling g\mathrm{g} and the in-medium effects regulator C\mathrm{C}. These effects are more pronounced in the case of QSs concerning all the bulk properties.Comment: 12 pages, 14 figures, 2 table

    Molecular characterisation and expression analysis of SEREX-defined antigen NUCB2 in gastric epithelium, gastritis and gastric cancer

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    NUCB2 is an EF-hand Ca2+ binding protein that has been implicated in various physiological processes like calcium homeostasis, hypothalamic regulation of feeding and TNF receptor shedding. In our previous study we identified NUCB2 as a potential tumour antigen eliciting autoantibody responses in 5.4% of gastric cancer patients but not in the healthy individuals. The current study aimed to elucidate the molecular mechanism underlying NUCB2 immunogenicity and to gain an insight into the physiological functions of NUCB2 in the stomach. mRNA expression analysis demonstrated that NUCB2 is ubiquitously expressed in normal tissues, including lymphoid tissues, and downregulated in gastric tumours when compared with the adjacent relatively normal stomach tissues. The search for molecular alterations resulted in the identification of novel mRNA variants transcribed from an alternative promoter and expressed predominantly in gastric cancers. Western blot analysis demonstrated that the protein levels correspond to mRNA levels and revealed that NUCB2 is phosphorylated in gastric mucosa. Furthermore, a 55 kDa isoform, generated presumably by yet an unidentified post-translational modification was detected in gastric tumours and AGS gastric cancer cells but was absent in the relatively normal gastric mucosa and thereby might have served as a trigger for the immune response against NUCB2. Staining of stomach tissue microarray with anti-NUCB2 antibody revealed that it is expressed in the secretory granules of chief cells and in the cytoplasm of parietal cells in the functioning gastric glands which are lost in atrophic glands and tumour cells. Hence we propose that NUCB2 may be implicated in gastric secretion by establishing an agonist-releasable Ca2+ store in ER or Golgi apparatus, signalling via heterotrimeric Gα proteins and/or mediating the exocytosis of the secretory granules

    The Electromagnetic Counterpart of the Binary Neutron Star Merger LIGO/VIRGO GW170817. VII. Properties of the Host Galaxy and Constraints on the Merger Timescale

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    We present the properties of NGC 4993, the host galaxy of GW170817, the first gravitational wave (GW) event from the merger of a binary neutron star (BNS) system and the first with an electromagnetic (EM) counterpart. We use both archival photometry and new optical/near-IR imaging and spectroscopy, together with stellar population synthesis models to infer the global properties of the host galaxy. We infer a star formation history peaked at 10\gtrsim 10 Gyr ago, with subsequent exponential decline leading to a low current star formation rate of 0.01 M_{\odot} yr1^{-1}, which we convert into a binary merger timescale probability distribution. We find a median merger timescale of 11.21.4+0.711.2^{+0.7}_{-1.4} Gyr, with a 90% confidence range of 6.813.66.8-13.6 Gyr. This in turn indicates an initial binary separation of 4.5\approx 4.5 R_{\odot}, comparable to the inferred values for Galactic BNS systems. We also use new and archival HubbleHubble SpaceSpace TelescopeTelescope images to measure a projected offset of the optical counterpart of 2.12.1 kpc (0.64rer_{e}) from the center of NGC 4993 and to place a limit of Mr7.2M_{r} \gtrsim -7.2 mag on any pre-existing emission, which rules out the brighter half of the globular cluster luminosity function. Finally, the age and offset of the system indicates it experienced a modest natal kick with an upper limit of 200\sim 200 km s1^{-1}. Future GW-EM observations of BNS mergers will enable measurement of their population delay time distribution, which will directly inform their viability as the dominant source of rr-process enrichment in the Universe.Comment: 9 Pages, 3 Figures, 2 Tables, ApJL, In Press. Keywords: GW170817, LV

    3D-HST+CANDELS : the evolution of the galaxy size-mass distribution since z=3

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    Spectroscopic+photometric redshifts, stellar mass estimates, and rest-frame colors from the 3D-HST survey are combined with structural parameter measurements from CANDELS imaging to determine the galaxy size-mass distribution over the redshift range 0 < z < 3. Separating early- and late-type galaxies on the basis of star-formation activity, we confirm that early-type galaxies are on average smaller than late-type galaxies at all redshifts, and we find a significantly different rate of average size evolution at fixed galaxy mass, with fast evolution for the early-type population, R eff∝(1 + z)–1.48, and moderate evolution for the late-type population, R eff∝(1 + z)-0.75Peer reviewedFinal Accepted Versio

    Signaling via PI3K/FOXO1A pathway modulates formation and survival of human embryonic stem cell-derived endothelial cells

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    Vascular derivatives of human embryonic stem cells (hESC) are being developed as sources of tissue-specific cells for organ regeneration. However, identity of developmental pathways that modulate the specification of endothelial cells is not known yet. We studied phosphatidylinositol 3-kinase (PI3K)-Forkhead box O transcription factor 1A (FOXO1A) pathways during differentiation of hESC toward endothelial lineage and on proliferation, maturation, and cell death of hESC-derived endothelial cells (hESC-EC). During differentiation of hESC, expression of FOXO1A transcription factor was linked to the expression of a cluster of angiogenesis- and vascular remodeling-related genes. PI3K inhibitor LY294002 activated FOXO1A and induced formation of CD31(+) hESC-EC. In contrast, differentiating hESC with silenced FOXO1A by small interfering RNA (siRNA) showed lower mRNA levels of CD31 and angiopoietin2. LY294002 decreased proliferative activity of purified hESC-EC, while FOXO1A siRNA increased their proliferation. LY294002 inhibits migration and tube formation of hESC-EC; in contrast, FOXO1A siRNA increased in vitro tube formation activity of hESC-EC. After in vivo conditioning of cells in athymic nude rats, cells retain their low FOXO1A expression levels. PI3K/FOXO1A pathway is important for function and survival of hESC-EC and in the regulation of endothelial cell fate. Understanding these properties of hESC-EC may help in future applications for treatment of injured organs

    Early JWST imaging reveals strong optical and NIR color gradients in galaxies at z2z\sim2 driven mostly by dust

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    Recent studies have shown that galaxies at cosmic noon are redder in the center and bluer in the outskirts, mirroring results in the local universe. These color gradients could be caused by either gradients in the stellar age or dust opacity; however, distinguishing between these two causes is impossible with rest-frame optical photometry alone. Here we investigate the underlying causes of the gradients from spatially-resolved rest-frame UVU-V vs. VJV-J color-color diagrams, measured from early observations with the James Webb Space Telescope. We use 1μm4μm1\, \mu m - 4\, \mu m NIRCam photometry from the CEERS survey of a sample of 54 galaxies with M/M>10M_* / M_\odot>10 at redshifts 1.7<z<2.31.7<z<2.3 selected from the 3D-HST catalog. We model the light profiles in the F115W, F200W and F356W NIRCam bands using \texttt{imcascade}, a Bayesian implementation of the Multi-Gaussian expansion (MGE) technique which flexibly represents galaxy profiles using a series of Gaussians. We construct resolved rest-frame UVU-V and VJV-J color profiles. The majority of star-forming galaxies have negative gradients (i.e. redder in the center, bluer in the outskirts) in both UVU-V and VJV-J colors consistent with radially decreasing dust attenuation. A smaller population (roughly 15\%) of star-forming galaxies have positive UVU-V but negative VJV-J gradients implying centrally concentrated star-formation. For quiescent galaxies we find a diversity of UVJ color profiles, with roughly one-third showing star-formation in their center. This study showcases the potential of JWST to study the resolved stellar populations of galaxies at cosmic noon.Comment: Updated to match published version, new Figure 5 and some text change
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