Spatially resolvable optical emission spectrometer for analyzing density uniformity of semiconductor process plasma

International Nuclear Information System (INIS)

Oh, Changhoon; Ryoo, Hoonchul; Lee, Hyungwoo; Hahn, Jae W.; Kim, Se-Yeon; Yi, Hun-Jung

2010-01-01

We proposed a spatially resolved optical emission spectrometer (SROES) for analyzing the uniformity of plasma density for semiconductor processes. To enhance the spatial resolution of the SROES, we constructed a SROES system using a series of lenses, apertures, and pinholes. We calculated the spatial resolution of the SROES for the variation of pinhole size, and our calculated results were in good agreement with the measured spatial variation of the constructed SROES. The performance of the SROES was also verified by detecting the correlation between the distribution of a fluorine radical in inductively coupled plasma etch process and the etch rate of a SiO 2 film on a silicon wafer.

Spatially resolved spectroscopy on semiconductor nanostructures

Energy Technology Data Exchange (ETDEWEB)

Roessler, Johanna

2009-02-20

Cleared edge overgrowth (CEO) nanostructures are identified and studied by 1D und 2D {mu}PL mapping scans and by time-resolved and power-dependent measurements. Distinct excitonic ground states of 2fold CEO QDs with large localization energies are achieved. The deeper localization reached as compared to the only other report on 2fold CEO QDs in literature is attributed to a new strain-free fabrication process and changed QW thickness in [001] growth. In order to achieve controlled manipulation of 2fold CEO QDs the concept of a CEO structure with three top gates and one back gate is presented. Due to the complexity of this device, a simpler test structure is realized. Measurements on this test structure confirm the necessity to either grow significantly thicker overgrowth layers or to provide separate top gates in all three spatial direction to controllably manipulate 2fold CEO QDs with an external electric field. (orig.)

Ssb1 and Ssb2 cooperate to regulate mouse hematopoietic stem and progenitor cells by resolving replicative stress.

Science.gov (United States)

Shi, Wei; Vu, Therese; Boucher, Didier; Biernacka, Anna; Nde, Jules; Pandita, Raj K; Straube, Jasmin; Boyle, Glen M; Al-Ejeh, Fares; Nag, Purba; Jeffery, Jessie; Harris, Janelle L; Bain, Amanda L; Grzelak, Marta; Skrzypczak, Magdalena; Mitra, Abhishek; Dojer, Norbert; Crosetto, Nicola; Cloonan, Nicole; Becherel, Olivier J; Finnie, John; Skaar, Jeffrey R; Walkley, Carl R; Pandita, Tej K; Rowicka, Maga; Ginalski, Krzysztof; Lane, Steven W; Khanna, Kum Kum

2017-05-04

Hematopoietic stem and progenitor cells (HSPCs) are vulnerable to endogenous damage and defects in DNA repair can limit their function. The 2 single-stranded DNA (ssDNA) binding proteins SSB1 and SSB2 are crucial regulators of the DNA damage response; however, their overlapping roles during normal physiology are incompletely understood. We generated mice in which both Ssb1 and Ssb2 were constitutively or conditionally deleted. Constitutive Ssb1/Ssb2 double knockout (DKO) caused early embryonic lethality, whereas conditional Ssb1/Ssb2 double knockout (cDKO) in adult mice resulted in acute lethality due to bone marrow failure and intestinal atrophy featuring stem and progenitor cell depletion, a phenotype unexpected from the previously reported single knockout models of Ssb1 or Ssb2 Mechanistically, cDKO HSPCs showed altered replication fork dynamics, massive accumulation of DNA damage, genome-wide double-strand breaks enriched at Ssb-binding regions and CpG islands, together with the accumulation of R -loops and cytosolic ssDNA. Transcriptional profiling of cDKO HSPCs revealed the activation of p53 and interferon (IFN) pathways, which enforced cell cycling in quiescent HSPCs, resulting in their apoptotic death. The rapid cell death phenotype was reproducible in in vitro cultured cDKO-hematopoietic stem cells, which were significantly rescued by nucleotide supplementation or after depletion of p53. Collectively, Ssb1 and Ssb2 control crucial aspects of HSPC function, including proliferation and survival in vivo by resolving replicative stress to maintain genomic stability. © 2017 by The American Society of Hematology.

Improved algorithm for estimating optical properties of food and biological materials using spatially-resolved diffuse reflectance

Science.gov (United States)

In this research, the inverse algorithm for estimating optical properties of food and biological materials from spatially-resolved diffuse reflectance was optimized in terms of data smoothing, normalization and spatial region of reflectance profile for curve fitting. Monte Carlo simulation was used ...

THE PROGENITOR OF THE TYPE IIb SN 2008ax REVISITED

International Nuclear Information System (INIS)

Folatelli, Gastón; Bersten, Melina C.; Benvenuto, Omar G.; Kuncarayakti, Hanindyo; Maeda, Keiichi; Nomoto, Ken’ichi

2015-01-01

Hubble Space Telescope observations of the site of the supernova (SN) SN 2008ax obtained in 2011 and 2013 reveal that the possible progenitor object detected in pre-explosion images was in fact multiple. Four point sources are resolved in the new, higher-resolution images. We identify one of the sources with the fading SN. The other three objects are consistent with single supergiant stars. We conclude that their light contaminated the previously identified progenitor candidate. After subtraction of these stars, the progenitor appears to be significantly fainter and bluer than previously measured. Post-explosion photometry at the SN location indicates that the progenitor object has disappeared. If single, the progenitor is compatible with a supergiant star of B to mid-A spectral type, while a Wolf–Rayet (W-R) star would be too luminous in the ultraviolet to account for the observations. Moreover, our hydrodynamical modeling shows that the pre-explosion mass was 4–5 M ⊙ and the radius was 30–50 R ⊙ , which is incompatible with a W-R progenitor. We present a possible interacting binary progenitor computed with our evolutionary models that reproduces all the observational evidence. A companion star as luminous as an O9–B0 main-sequence star may have remained after the explosion

SPATIALLY RESOLVED SPECTROSCOPY OF EUROPA’S LARGE-SCALE COMPOSITIONAL UNITS AT 3–4 μ m WITH KECK NIRSPEC

Energy Technology Data Exchange (ETDEWEB)

Fischer, P. D.; Brown, M. E.; Trumbo, S. K. [Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125 (United States); Hand, K. P., E-mail: pfischer@caltech.edu [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States)

2017-01-01

We present spatially resolved spectroscopic observations of Europa’s surface at 3–4 μ m obtained with the near-infrared spectrograph and adaptive optics system on the Keck II telescope. These are the highest quality spatially resolved reflectance spectra of Europa’s surface at 3–4 μ m. The observations spatially resolve Europa’s large-scale compositional units at a resolution of several hundred kilometers. The spectra show distinct features and geographic variations associated with known compositional units; in particular, large-scale leading hemisphere chaos shows a characteristic longward shift in peak reflectance near 3.7 μ m compared to icy regions. These observations complement previous spectra of large-scale chaos, and can aid efforts to identify the endogenous non-ice species.

THE KINEMATICS OF THE NEBULAR SHELLS AROUND LOW MASS PROGENITORS OF PNe WITH LOW METALLICITY

Energy Technology Data Exchange (ETDEWEB)

Pereyra, Margarita; López, José Alberto; Richer, Michael G., E-mail: mally@astrosen.unam.mx, E-mail: jal@astrosen.unam.mx, E-mail: richer@astrosen.unam.mx [Instituto de Astronomía, Universidad Nacional Autónoma de México, Apartado Postal 106, C.P. 22800 Ensenada, BC, México (Mexico)

2016-03-15

We analyze the internal kinematics of 26 planetary nebulae (PNe) with low metallicity that appear to derive from progenitor stars of the lowest masses, including the halo PN population. Based upon spatially resolved, long-slit, echelle spectroscopy drawn from the San Pedro Mártir Kinematic Catalog of PNe, we characterize the kinematics of these PNe measuring their global expansion velocities based upon the largest sample used to date for this purpose. We find kinematics that follow the trends observed and predicted in other studies, but also find that most of the PNe studied here tend to have expansion velocities less than 20 km s{sup −1} in all of the emission lines considered. The low expansion velocities that we observe in this sample of low metallicity PNe with low mass progenitors are most likely a consequence of a weak central star (CS) wind driving the kinematics of the nebular shell. This study complements previous results that link the expansion velocities of the PN shells with the characteristics of the CS.

PLZF regulates fibroblast growth factor responsiveness and maintenance of neural progenitors.

Science.gov (United States)

Gaber, Zachary B; Butler, Samantha J; Novitch, Bennett G

2013-10-01

Distinct classes of neurons and glial cells in the developing spinal cord arise at specific times and in specific quantities from spatially discrete neural progenitor domains. Thus, adjacent domains can exhibit marked differences in their proliferative potential and timing of differentiation. However, remarkably little is known about the mechanisms that account for this regional control. Here, we show that the transcription factor Promyelocytic Leukemia Zinc Finger (PLZF) plays a critical role shaping patterns of neuronal differentiation by gating the expression of Fibroblast Growth Factor (FGF) Receptor 3 and responsiveness of progenitors to FGFs. PLZF elevation increases FGFR3 expression and STAT3 pathway activity, suppresses neurogenesis, and biases progenitors towards glial cell production. In contrast, PLZF loss reduces FGFR3 levels, leading to premature neuronal differentiation. Together, these findings reveal a novel transcriptional strategy for spatially tuning the responsiveness of distinct neural progenitor groups to broadly distributed mitogenic signals in the embryonic environment.

Near-Infrared Spatially Resolved Spectroscopy for Tablet Quality Determination.

Science.gov (United States)

Igne, Benoît; Talwar, Sameer; Feng, Hanzhou; Drennen, James K; Anderson, Carl A

2015-12-01

Near-infrared (NIR) spectroscopy has become a well-established tool for the characterization of solid oral dosage forms manufacturing processes and finished products. In this work, the utility of a traditional single-point NIR measurement was compared with that of a spatially resolved spectroscopic (SRS) measurement for the determination of tablet assay. Experimental designs were used to create samples that allowed for calibration models to be developed and tested on both instruments. Samples possessing a poor distribution of ingredients (highly heterogeneous) were prepared by under-blending constituents prior to compaction to compare the analytical capabilities of the two NIR methods. The results indicate that SRS can provide spatial information that is usually obtainable only through imaging experiments for the determination of local heterogeneity and detection of abnormal tablets that would not be detected with single-point spectroscopy, thus complementing traditional NIR measurement systems for in-line, and in real-time tablet analysis. © 2015 Wiley Periodicals, Inc. and the American Pharmacists Association.

AgesGalore-A software program for evaluating spatially resolved luminescence data

International Nuclear Information System (INIS)

Greilich, S.; Harney, H.-L.; Woda, C.; Wagner, G.A.

2006-01-01

Low-light luminescence is usually recorded by photomultiplier tubes (PMTs) yielding integrated photon-number data. Highly sensitive CCD (charged coupled device) detectors allow for the spatially resolved recording of luminescence. The resulting two-dimensional images require suitable software for data processing. We present a recently developed software program specially designed for equivalent-dose evaluation in the framework of optically stimulated luminescence (OSL) dating. The software is capable of appropriate CCD data handling, parameter estimation using a Bayesian approach, and the pixel-wise fitting of functions for time and dose dependencies to the luminescence signal. The results of the fitting procedure and the equivalent-dose evaluation can be presented and analyzed both as spatial and as frequency distributions

Red Supergiants as Potential Type IIn Supernova Progenitors: Spatially Resolved 4.6 μm CO Emission Around VY CMa and Betelgeuse

Science.gov (United States)

Smith, Nathan; Hinkle, Kenneth H.; Ryde, Nils

2009-03-01

We present high-resolution 4.6 μm CO spectra of the circumstellar environments of two red supergiants (RSGs) that are potential supernova (SN) progenitors: Betelgeuse and VY Canis Majoris (VY CMa). Around Betelgeuse, 12CO emission within ±3'' (±12 km s-1) follows a mildly clumpy but otherwise spherical shell, smaller than its ~55'' shell in K I λ7699. In stark contrast, 4.6 μm CO emission around VY CMa is coincident with bright K I in its clumpy asymmetric reflection nebula, within ±5'' (±40 km s-1) of the star. Our CO data reveal redshifted features not seen in K I spectra of VY CMa, indicating a more isotropic distribution of gas punctuated by randomly distributed asymmetric clumps. The relative CO and K I distribution in Betelgeuse arises from ionization effects within a steady wind, whereas in VY CMa, K I is emitted from skins of CO cloudlets resulting from episodic mass ejections 500-1000 yr ago. In both cases, CO and K I trace potential pre-SN circumstellar matter: we conclude that an extreme RSG like VY CMa might produce a Type IIn event like SN 1988Z if it were to explode in its current state, but Betelgeuse will not. VY CMa demonstrates that luminous blue variables are not necessarily the only progenitors of SNe IIn, but it underscores the requirement that SNe IIn suffer enhanced episodic mass loss shortly before exploding. Based on observations obtained at the Gemini Observatory.

Spatially resolved x-ray fluorescence spectroscopy of beryllium capsule implosions at the NIF

Science.gov (United States)

MacDonald, M. J.; Bishel, D. T.; Saunders, A. M.; Scott, H. A.; Kyrala, G.; Kline, J.; MacLaren, S.; Thorn, D. B.; Yi, S. A.; Zylstra, A. B.; Falcone, R. W.; Doeppner, T.

2017-10-01

Beryllium ablators used in indirectly driven inertial confinement fusion implosions are doped with copper to prevent preheat of the cryogenic hydrogen fuel. Here, we present analysis of spatially resolved copper K- α fluorescence spectra from the beryllium ablator layer. It has been shown that K- α fluorescence spectroscopy can be used to measure plasma conditions of partially ionized dopants in high energy density systems. In these experiments, K-shell vacancies in the copper dopant are created by the hotspot emission at stagnation, resulting in K-shell fluorescence at bang time. Spatially resolved copper K- α emission spectra are compared to atomic kinetics and radiation code simulations to infer density and temperature profiles. This work was supported by the US DOE under Grant No. DE-NA0001859, under the auspices of the US DOE by Lawrence Livermore National Laboratory under Contract No. DE-AC52-07NA27344, and by Los Alamos National Laboratory under contract DE-AC52-06NA52396.

THE PROGENITOR OF THE TYPE IIb SN 2008ax REVISITED

Energy Technology Data Exchange (ETDEWEB)

Folatelli, Gastón; Bersten, Melina C.; Benvenuto, Omar G. [Instituto de Astrofísica de La Plata (Argentina); Kuncarayakti, Hanindyo [Millennium Institute of Astrophysics (MAS), Casilla 36-D, Santiago (Chile); Maeda, Keiichi; Nomoto, Ken’ichi, E-mail: gaston@fcaglp.unlp.edu.ar [Kavli Institute for the Physics and Mathematics of the Universe (WPI), The University of Tokyo, Kashiwa, Chiba 277-8583 (Japan)

2015-10-01

Hubble Space Telescope observations of the site of the supernova (SN) SN 2008ax obtained in 2011 and 2013 reveal that the possible progenitor object detected in pre-explosion images was in fact multiple. Four point sources are resolved in the new, higher-resolution images. We identify one of the sources with the fading SN. The other three objects are consistent with single supergiant stars. We conclude that their light contaminated the previously identified progenitor candidate. After subtraction of these stars, the progenitor appears to be significantly fainter and bluer than previously measured. Post-explosion photometry at the SN location indicates that the progenitor object has disappeared. If single, the progenitor is compatible with a supergiant star of B to mid-A spectral type, while a Wolf–Rayet (W-R) star would be too luminous in the ultraviolet to account for the observations. Moreover, our hydrodynamical modeling shows that the pre-explosion mass was 4–5 M{sub ⊙} and the radius was 30–50 R{sub ⊙}, which is incompatible with a W-R progenitor. We present a possible interacting binary progenitor computed with our evolutionary models that reproduces all the observational evidence. A companion star as luminous as an O9–B0 main-sequence star may have remained after the explosion.

Spatially resolved sulfur K-edge XANES spectroscopy of wheat leaves infected by Puccinia triticina

International Nuclear Information System (INIS)

Lichtenberg, H; Prange, A; Hormes, J; Steiner, U; Oerke, E-C

2009-01-01

In this study, wheat leaves infected with brown rust, a plant disease of serious economic concern caused by the fungus Puccinia triticina, were investigated using spatially resolved XANES (X-ray Absorption Near Edge Structure) spectroscopy at the sulfur K-absorption edge.

Spatially resolved sulfur K-edge XANES spectroscopy of wheat leaves infected by Puccinia triticina

Energy Technology Data Exchange (ETDEWEB)

Lichtenberg, H; Prange, A; Hormes, J [CAMD, Louisiana State University, 6980 Jefferson Hwy, Baton Rouge, LA 70806 (United States); Steiner, U; Oerke, E-C, E-mail: lichtenberg@lsu.ed [INRES-Phytomedicine, University of Bonn, Nussallee 9, 53115 Bonn (Germany)

2009-11-15

In this study, wheat leaves infected with brown rust, a plant disease of serious economic concern caused by the fungus Puccinia triticina, were investigated using spatially resolved XANES (X-ray Absorption Near Edge Structure) spectroscopy at the sulfur K-absorption edge.

A framework for widespread replication of a highly spatially resolved childhood lead exposure risk model.

Science.gov (United States)

Kim, Dohyeong; Galeano, M Alicia Overstreet; Hull, Andrew; Miranda, Marie Lynn

2008-12-01

Preventive approaches to childhood lead poisoning are critical for addressing this longstanding environmental health concern. Moreover, increasing evidence of cognitive effects of blood lead levels system-based childhood lead exposure risk models, especially if executed at highly resolved spatial scales, can help identify children most at risk of lead exposure, as well as prioritize and direct housing and health-protective intervention programs. However, developing highly resolved spatial data requires labor-and time-intensive geocoding and analytical processes. In this study we evaluated the benefit of increased effort spent geocoding in terms of improved performance of lead exposure risk models. We constructed three childhood lead exposure risk models based on established methods but using different levels of geocoded data from blood lead surveillance, county tax assessors, and the 2000 U.S. Census for 18 counties in North Carolina. We used the results to predict lead exposure risk levels mapped at the individual tax parcel unit. The models performed well enough to identify high-risk areas for targeted intervention, even with a relatively low level of effort on geocoding. This study demonstrates the feasibility of widespread replication of highly spatially resolved childhood lead exposure risk models. The models guide resource-constrained local health and housing departments and community-based organizations on how best to expend their efforts in preventing and mitigating lead exposure risk in their communities.

Noncontact blood species identification method based on spatially resolved near-infrared transmission spectroscopy

Science.gov (United States)

Zhang, Linna; Sun, Meixiu; Wang, Zhennan; Li, Hongxiao; Li, Yingxin; Li, Gang; Lin, Ling

2017-09-01

The inspection and identification of whole blood are crucially significant for import-export ports and inspection and quarantine departments. In our previous research, we proved Near-Infrared diffuse transmitted spectroscopy method was potential for noninvasively identifying three blood species, including macaque, human and mouse, with samples measured in the cuvettes. However, in open sampling cases, inspectors may be endangered by virulence factors in blood samples. In this paper, we explored the noncontact measurement for classification, with blood samples measured in the vacuum blood vessels. Spatially resolved near-infrared spectroscopy was used to improve the prediction accuracy. Results showed that the prediction accuracy of the model built with nine detection points was more than 90% in identification between all five species, including chicken, goat, macaque, pig and rat, far better than the performance of the model built with single-point spectra. The results fully supported the idea that spatially resolved near-infrared spectroscopy method can improve the prediction ability, and demonstrated the feasibility of this method for noncontact blood species identification in practical applications.

Spatially resolved x-ray laser spectra and demonstration of gain in nickel-like systems

Energy Technology Data Exchange (ETDEWEB)

Whelan, D.A.; Keane, C.J.; MacGowan, B.J.; Matthews, D.L.; Trebes, J.E.; Eckart, M.J.

1987-09-25

A recent series of experiments have provided spatially resolved near field images of several candidate x-ray lasing transition in neon-like, nickel-like, and hydrogen-like ions from laser-produced plasmas. From these time-gated, spatially, and spectrally resolved measurements the source size for the J = 0 - 1 and the J = 2 - 1 transitions in Ne-like selenium have been determined. Source regions as small as 50 ..mu..m have been observed on transitions with gain-length products >9. In addition, we have obtained the first experimental evidence for the amplification of spontaneous emission in the nickel-like ions of europium and ytterbium. Gains of order 1 cm/sup -1/ and gain-length products of up to 3.8 are observed on the J = 0 - 1, 4d-4p transitions in Eu + 35 at 65.26 and 71.00 A. Analogous transitions in Yb = +42 have been identified and some evidence for ASE has been observed. 7 refs., 11 figs.

Spatially resolved X-ray laser spectra and demonstration of gain in nickel-like systems

International Nuclear Information System (INIS)

Whelan, D.A.; Keane, C.J.; MacGowan, B.J.; Matthews, D.L.; Trebes, J.E.; Eckart, M.J.

1987-01-01

A recent series of experiments have provided spatially resolved near field images of several candidate x-ray lasing transition in neon-like, nickel-like, and hydrogen-like ions from laser-produced plasmas. From these time-gated, spatially, and spectrally resolved measurements the source size for the J=0-1 and the J=2-1 transitions in Ne-like selenium have been determined. Source regions as small as 50 μm have been observed on transitions with gain-length products >9. In addition, the authors have obtained the first experimental evidence for the amplification of spontaneous emission in the nickel-like ions of europium and ytterbium. Gains of order 1 cm/sup -1/ and gain-length products of up to 3.8 are observed on the J=0-1,4d-4p transitions in Eu/sup +35/ at 65.83 and 71.00A. Analogous transitions in Yb/sup +42/ have been identified and some evidence for ASE has been observed

Panchromatic SED modelling of spatially resolved galaxies

Science.gov (United States)

Smith, Daniel J. B.; Hayward, Christopher C.

2018-05-01

We test the efficacy of the energy-balance spectral energy distribution (SED) fitting code MAGPHYS for recovering the spatially resolved properties of a simulated isolated disc galaxy, for which it was not designed. We perform 226 950 MAGPHYS SED fits to regions between 0.2 and 25 kpc in size across the galaxy's disc, viewed from three different sight-lines, to probe how well MAGPHYS can recover key galaxy properties based on 21 bands of UV-far-infrared model photometry. MAGPHYS yields statistically acceptable fits to >99 per cent of the pixels within the r-band effective radius and between 59 and 77 percent of pixels within 20 kpc of the nucleus. MAGPHYS is able to recover the distribution of stellar mass, star formation rate (SFR), specific SFR, dust luminosity, dust mass, and V-band attenuation reasonably well, especially when the pixel size is ≳ 1 kpc, whereas non-standard outputs (stellar metallicity and mass-weighted age) are recovered less well. Accurate recovery is more challenging in the smallest sub-regions of the disc (pixel scale ≲ 1 kpc), where the energy balance criterion becomes increasingly incorrect. Estimating integrated galaxy properties by summing the recovered pixel values, the true integrated values of all parameters considered except metallicity and age are well recovered at all spatial resolutions, ranging from 0.2 kpc to integrating across the disc, albeit with some evidence for resolution-dependent biases. These results must be considered when attempting to analyse the structure of real galaxies with actual observational data, for which the `ground truth' is unknown.

Spatially Resolving Ocean Color and Sediment Dispersion in River Plumes, Coastal Systems, and Continental Shelf Waters

Science.gov (United States)

Aurin, Dirk Alexander; Mannino, Antonio; Franz, Bryan

2013-01-01

Satellite remote sensing of ocean color in dynamic coastal, inland, and nearshorewaters is impeded by high variability in optical constituents, demands specialized atmospheric correction, and is limited by instrument sensitivity. To accurately detect dispersion of bio-optical properties, remote sensors require ample signal-to-noise ratio (SNR) to sense small variations in ocean color without saturating over bright pixels, an atmospheric correction that can accommodate significantwater-leaving radiance in the near infrared (NIR), and spatial and temporal resolution that coincides with the scales of variability in the environment. Several current and historic space-borne sensors have met these requirements with success in the open ocean, but are not optimized for highly red-reflective and heterogeneous waters such as those found near river outflows or in the presence of sediment resuspension. Here we apply analytical approaches for determining optimal spatial resolution, dominant spatial scales of variability ("patches"), and proportions of patch variability that can be resolved from four river plumes around the world between 2008 and 2011. An offshore region in the Sargasso Sea is analyzed for comparison. A method is presented for processing Moderate Resolution Imaging Spectroradiometer (MODIS) Aqua and Terra imagery including cloud detection, stray lightmasking, faulty detector avoidance, and dynamic aerosol correction using short-wave- and near-infrared wavebands in extremely turbid regions which pose distinct optical and technical challenges. Results showthat a pixel size of approx. 520 mor smaller is generally required to resolve spatial heterogeneity in ocean color and total suspended materials in river plumes. Optimal pixel size increases with distance from shore to approx. 630 m in nearshore regions, approx 750 m on the continental shelf, and approx. 1350 m in the open ocean. Greater than 90% of the optical variability within plume regions is resolvable with

Collimated dual species oven source and its characterisation via spatially resolved fluorescence spectroscopy

Science.gov (United States)

Cooper, N.; Da Ros, E.; Nute, J.; Baldolini, D.; Jouve, P.; Hackermüller, L.; Langer, M.

2018-03-01

We describe the design, construction and characterisation of a collimated, dual-species oven source for generating intense beams of lithium and caesium in UHV environments. Our design produces full beam overlap for the two species. Using an aligned microtube array the FWHM of the output beam is restricted to  ˜75 milliradians, with an estimated axial brightness of 3.6× 1014 atoms s-1 sr-1 for Li and 7.4× 1015 atoms s-1 sr-1 for Cs. We measure the properties of the output beam using a spatially-resolved fluorescence technique, which allows for the extraction of additional information not accessible without spatial resolution.

Spatially resolved acoustic spectroscopy for rapid imaging of material microstructure and grain orientation

International Nuclear Information System (INIS)

Smith, Richard J; Li, Wenqi; Coulson, Jethro; Clark, Matt; Somekh, Michael G; Sharples, Steve D

2014-01-01

Measuring the grain structure of aerospace materials is very important to understand their mechanical properties and in-service performance. Spatially resolved acoustic spectroscopy is an acoustic technique utilizing surface acoustic waves to map the grain structure of a material. When combined with measurements in multiple acoustic propagation directions, the grain orientation can be obtained by fitting the velocity surface to a model. The new instrument presented here can take thousands of acoustic velocity measurements per second. The spatial and velocity resolution can be adjusted by simple modification to the system; this is discussed in detail by comparison of theoretical expectations with experimental data. (paper)

Requirement of mouse BCCIP for neural development and progenitor proliferation.

Directory of Open Access Journals (Sweden)

Yi-Yuan Huang

Full Text Available Multiple DNA repair pathways are involved in the orderly development of neural systems at distinct stages. The homologous recombination (HR pathway is required to resolve stalled replication forks and critical for the proliferation of progenitor cells during neural development. BCCIP is a BRCA2 and CDKN1A interacting protein implicated in HR and inhibition of DNA replication stress. In this study, we determined the role of BCCIP in neural development using a conditional BCCIP knock-down mouse model. BCCIP deficiency impaired embryonic and postnatal neural development, causing severe ataxia, cerebral and cerebellar defects, and microcephaly. These development defects are associated with spontaneous DNA damage and subsequent cell death in the proliferative cell populations of the neural system during embryogenesis. With in vitro neural spheroid cultures, BCCIP deficiency impaired neural progenitor's self-renewal capability, and spontaneously activated p53. These data suggest that BCCIP and its anti-replication stress functions are essential for normal neural development by maintaining an orderly proliferation of neural progenitors.

Microstructural investigation into calcium phosphate biomaterials by spatially resolved cathodoluminescence

Energy Technology Data Exchange (ETDEWEB)

Goetze, J.; Heimann, R.B.; Hildebrandt, H. [Freiberg Univ. of Mining and Technology (Germany). Dept. of Mineralogy; Gburek, U. [Wuerzburg Univ. (Germany). Dept. of Experimental Dentistry

2001-02-01

From cathodoluminescence (CL) investigations of synthetic and natural calcium phosphates it can be concluded that the CL of pure synthetic apatite is mainly characterized by intrinsic luminescence, whereas the luminescence of naturally occurring apatites is frequently activated by trace elements. CL revealed internal structures within plasma-sprayed hydroxyapatite coatings which were not discernible by SEM-BSE imaging. However, cathodoluminescence microscopy alone can presently not be used in every case to characterize synthetic calcium phosphate biomaterials because of the dominant intrinsic blue CL emission. In the future, optimum results will likely be achieved by using a combination of CL microscopy and spectroscopy with other spatially resolved analytical methods such as SEM-BSE, SEM-CL or micro-Raman spectroscopy. In the present study, different types of tetracalcium phosphate dental cements could be distinguished due to varying CL colours and CL spectra that are caused by a different content of impurity Mn. These results emphasize the advantages of spectral CL measurements for spatially resolved detection of trace elements in solids. (orig.) [German] Ergebnisse von Kathodolumineszenz- (KL-) Untersuchungen synthetischer und natuerlicher Apatite zeigen, dass die KL synthetischer Apatite vorrangig durch intrinsische Lumineszenz gekennzeichnet ist, waehrend die KL natuerlicher Apatite meist durch Spurenlemente aktiviert wird. Mittels KL koennen Internstrukturen in plasmagespritzten Hydroxylapatit-Schichten sichtbar gemacht werden, die im REM-BSE nicht nachweisbar sind. Allerdings kann die KL-Mikroskopie aufgrund der dominierenden blauen intrinsischen Lumineszenz gegenwaertig nicht als alleinige Untersuchungsmethode zur Charakterisierung von Calciumphosphat Biomaterialien eingesetzt werden. Optimale Resultate werden zukuenftig durch Kombination von KL-Mikrroskopie und -spektroskopie mit anderen ortsaufgeloesten analytischen Methoden wie REM-BSE, REM-KL oder Mikro

Sensitivity Analysis and Requirements for Temporally and Spatially Resolved Thermometry Using Neutron Resonance Spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Fernandez, Juan Carlos [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Barnes, Cris William [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Mocko, Michael Jeffrey [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Zavorka, Lukas [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2018-01-31

This report is intended to examine the use of neutron resonance spectroscopy (NRS) to make time- dependent and spatially-resolved temperature measurements of materials in extreme conditions. Specifically, the sensitivities of the temperature estimate on neutron-beam and diagnostic parameters is examined. Based on that examination, requirements are set on a pulsed neutron-source and diagnostics to make a meaningful measurement.

Spatially resolved chemical analysis of cicada wings using laser-ablation electrospray ionization (LAESI) imaging mass spectrometry (IMS).

Science.gov (United States)

Román, Jessica K; Walsh, Callee M; Oh, Junho; Dana, Catherine E; Hong, Sungmin; Jo, Kyoo D; Alleyne, Marianne; Miljkovic, Nenad; Cropek, Donald M

2018-03-01

Laser-ablation electrospray ionization (LAESI) imaging mass spectrometry (IMS) is an emerging bioanalytical tool for direct imaging and analysis of biological tissues. Performing ionization in an ambient environment, this technique requires little sample preparation and no additional matrix, and can be performed on natural, uneven surfaces. When combined with optical microscopy, the investigation of biological samples by LAESI allows for spatially resolved compositional analysis. We demonstrate here the applicability of LAESI-IMS for the chemical analysis of thin, desiccated biological samples, specifically Neotibicen pruinosus cicada wings. Positive-ion LAESI-IMS accurate ion-map data was acquired from several wing cells and superimposed onto optical images allowing for compositional comparisons across areas of the wing. Various putative chemical identifications were made indicating the presence of hydrocarbons, lipids/esters, amines/amides, and sulfonated/phosphorylated compounds. With the spatial resolution capability, surprising chemical distribution patterns were observed across the cicada wing, which may assist in correlating trends in surface properties with chemical distribution. Observed ions were either (1) equally dispersed across the wing, (2) more concentrated closer to the body of the insect (proximal end), or (3) more concentrated toward the tip of the wing (distal end). These findings demonstrate LAESI-IMS as a tool for the acquisition of spatially resolved chemical information from fragile, dried insect wings. This LAESI-IMS technique has important implications for the study of functional biomaterials, where understanding the correlation between chemical composition, physical structure, and biological function is critical. Graphical abstract Positive-ion laser-ablation electrospray ionization mass spectrometry coupled with optical imaging provides a powerful tool for the spatially resolved chemical analysis of cicada wings.

Test Sample for the Spatially Resolved Quantification of Illicit Drugs on Fingerprints Using Imaging Mass Spectrometry

NARCIS (Netherlands)

Muramoto, S.; Forbes, T.P.; van Asten, A.C.; Gillen, G.

2015-01-01

A novel test sample for the spatially resolved quantification of illicit drugs on the surface of a fingerprint using time-of-flight secondary ion mass spectrometry (ToF-SIMS) and desorption electrospray ionization mass spectrometry (DESI-MS) was demonstrated. Calibration curves relating the signal

Scanning photoelectron microscope for nanoscale three-dimensional spatial-resolved electron spectroscopy for chemical analysis.

Science.gov (United States)

Horiba, K; Nakamura, Y; Nagamura, N; Toyoda, S; Kumigashira, H; Oshima, M; Amemiya, K; Senba, Y; Ohashi, H

2011-11-01

In order to achieve nondestructive observation of the three-dimensional spatially resolved electronic structure of solids, we have developed a scanning photoelectron microscope system with the capability of depth profiling in electron spectroscopy for chemical analysis (ESCA). We call this system 3D nano-ESCA. For focusing the x-ray, a Fresnel zone plate with a diameter of 200 μm and an outermost zone width of 35 nm is used. In order to obtain the angular dependence of the photoelectron spectra for the depth-profile analysis without rotating the sample, we adopted a modified VG Scienta R3000 analyzer with an acceptance angle of 60° as a high-resolution angle-resolved electron spectrometer. The system has been installed at the University-of-Tokyo Materials Science Outstation beamline, BL07LSU, at SPring-8. From the results of the line-scan profiles of the poly-Si/high-k gate patterns, we achieved a total spatial resolution better than 70 nm. The capability of our system for pinpoint depth-profile analysis and high-resolution chemical state analysis is demonstrated. © 2011 American Institute of Physics

Inter-progenitor pool wiring: An evolutionarily conserved strategy that expands neural circuit diversity.

Science.gov (United States)

Suzuki, Takumi; Sato, Makoto

2017-11-15

Diversification of neuronal types is key to establishing functional variations in neural circuits. The first critical step to generate neuronal diversity is to organize the compartmental domains of developing brains into spatially distinct neural progenitor pools. Neural progenitors in each pool then generate a unique set of diverse neurons through specific spatiotemporal specification processes. In this review article, we focus on an additional mechanism, 'inter-progenitor pool wiring', that further expands the diversity of neural circuits. After diverse types of neurons are generated in one progenitor pool, a fraction of these neurons start migrating toward a remote brain region containing neurons that originate from another progenitor pool. Finally, neurons of different origins are intermingled and eventually form complex but precise neural circuits. The developing cerebral cortex of mammalian brains is one of the best examples of inter-progenitor pool wiring. However, Drosophila visual system development has revealed similar mechanisms in invertebrate brains, suggesting that inter-progenitor pool wiring is an evolutionarily conserved strategy that expands neural circuit diversity. Here, we will discuss how inter-progenitor pool wiring is accomplished in mammalian and fly brain systems. Copyright © 2017 Elsevier Inc. All rights reserved.

Spatially resolved spectroscopy analysis of the XMM-Newton large program on SN1006

Science.gov (United States)

Li, Jiang-Tao; Decourchelle, Anne; Miceli, Marco; Vink, Jacco; Bocchino, Fabrizio

2016-04-01

We perform analysis of the XMM-Newton large program on SN1006 based on our newly developed methods of spatially resolved spectroscopy analysis. We extract spectra from low and high resolution meshes. The former (3596 meshes) is used to roughly decompose the thermal and non-thermal components and characterize the spatial distributions of different parameters, such as temperature, abundances of different elements, ionization age, and electron density of the thermal component, as well as photon index and cutoff frequency of the non-thermal component. On the other hand, the low resolution meshes (583 meshes) focus on the interior region dominated by the thermal emission and have enough counts to well characterize the Si lines. We fit the spectra from the low resolution meshes with different models, in order to decompose the multiple plasma components at different thermal and ionization states and compare their spatial distributions. In this poster, we will present the initial results of this project.

Spatially Resolved Temperature and Water Vapor Concentration Distributions in Supersonic Combustion Facilities by TDLAT

Science.gov (United States)

Busa, K. M.; McDaniel J. C.; Diskin, G. S.; DePiro, M. J.; Capriotti, D. P.; Gaffney, R. L.

2012-01-01

Detailed knowledge of the internal structure of high-enthalpy flows can provide valuable insight to the performance of scramjet combustors. Tunable Diode Laser Absorption Spectroscopy (TDLAS) is often employed to measure temperature and species concentration. However, TDLAS is a path-integrated line-of-sight (LOS) measurement, and thus does not produce spatially resolved distributions. Tunable Diode Laser Absorption Tomography (TDLAT) is a non-intrusive measurement technique for determining two-dimensional spatially resolved distributions of temperature and species concentration in high enthalpy flows. TDLAT combines TDLAS with tomographic image reconstruction. More than 2500 separate line-of-sight TDLAS measurements are analyzed in order to produce highly resolved temperature and species concentration distributions. Measurements have been collected at the University of Virginia's Supersonic Combustion Facility (UVaSCF) as well as at the NASA Langley Direct-Connect Supersonic Combustion Test Facility (DCSCTF). Due to the UVaSCF s unique electrical heating and ability for vitiate addition, measurements collected at the UVaSCF are presented as a calibration of the technique. Measurements collected at the DCSCTF required significant modifications to system hardware and software designs due to its larger measurement area and shorter test duration. Tomographic temperature and water vapor concentration distributions are presented from experimentation on the UVaSCF operating at a high temperature non-reacting case for water vitiation level of 12%. Initial LOS measurements from the NASA Langley DCSCTF operating at an equivalence ratio of 0.5 are also presented. Results show the capability of TDLAT to adapt to several experimental setups and test parameters.

Redox-dependent spatially resolved electrochemistry at graphene and graphite step edges.

Science.gov (United States)

Güell, Aleix G; Cuharuc, Anatolii S; Kim, Yang-Rae; Zhang, Guohui; Tan, Sze-yin; Ebejer, Neil; Unwin, Patrick R

2015-04-28

The electrochemical (EC) behavior of mechanically exfoliated graphene and highly oriented pyrolytic graphite (HOPG) is studied at high spatial resolution in aqueous solutions using Ru(NH3)6(3+/2+) as a redox probe whose standard potential sits close to the intrinsic Fermi level of graphene and graphite. When scanning electrochemical cell microscopy (SECCM) data are coupled with that from complementary techniques (AFM, micro-Raman) applied to the same sample area, different time-dependent EC activity between the basal planes and step edges is revealed. In contrast, other redox couples (ferrocene derivatives) whose potential is further removed from the intrinsic Fermi level of graphene and graphite show uniform and high activity (close to diffusion-control). Macroscopic voltammetric measurements in different environments reveal that the time-dependent behavior after HOPG cleavage, peculiar to Ru(NH3)6(3+/2+), is not associated particularly with any surface contaminants but is reasonably attributed to the spontaneous delamination of the HOPG with time to create partially coupled graphene layers, further supported by conductive AFM measurements. This process has a major impact on the density of states of graphene and graphite edges, particularly at the intrinsic Fermi level to which Ru(NH3)6(3+/2+) is most sensitive. Through the use of an improved voltammetric mode of SECCM, we produce movies of potential-resolved and spatially resolved HOPG activity, revealing how enhanced activity at step edges is a subtle effect for Ru(NH3)6(3+/2+). These latter studies allow us to propose a microscopic model to interpret the EC response of graphene (basal plane and edges) and aged HOPG considering the nontrivial electronic band structure.

Constraints for the progenitor masses of 17 historic core-collapse supernovae

International Nuclear Information System (INIS)

Williams, Benjamin F.; Peterson, Skyler; Gilbert, Karoline; Dalcanton, Julianne J.; Murphy, Jeremiah; Dolphin, Andrew E.; Jennings, Zachary G.

2014-01-01

Using resolved stellar photometry measured from archival Hubble Space Telescope imaging, we generate color-magnitude diagrams of the stars within 50 pc of the locations of historic core-collapse supernovae (SNe) that took place in galaxies within 8 Mpc. We fit these color-magnitude distributions with stellar evolution models to determine the best-fit age distribution of the young population. We then translate these age distributions into probability distributions for the progenitor mass of each SN. The measurements are anchored by the main-sequence stars surrounding the event, making them less sensitive to assumptions about binarity, post-main-sequence evolution, or circumstellar dust. We demonstrate that, in cases where the literature contains masses that have been measured from direct imaging, our measurements are consistent with (but less precise than) these measurements. Using this technique, we constrain the progenitor masses of 17 historic SNe, 11 of which have no previous estimates from direct imaging. Our measurements still allow the possibility that all SN progenitor masses are <20 M ☉ . However, the large uncertainties for the highest-mass progenitors also allow the possibility of no upper-mass cutoff.

Constraints for the progenitor masses of 17 historic core-collapse supernovae

Energy Technology Data Exchange (ETDEWEB)

Williams, Benjamin F.; Peterson, Skyler; Gilbert, Karoline; Dalcanton, Julianne J. [Department of Astronomy, Box 351580, University of Washington, Seattle, WA 98195 (United States); Murphy, Jeremiah [Department of Physics, Florida State University, Tallahassee, FL 32306 (United States); Dolphin, Andrew E. [Raytheon, 1151 E. Hermans Road, Tucson, AZ 85706 (United States); Jennings, Zachary G., E-mail: ben@astro.washington.edu, E-mail: peters8@uw.edu, E-mail: jd@astro.washington.edu, E-mail: jeremiah@physics.fsu.edu, E-mail: kgilbert@stsci.edu, E-mail: dolphin@raytheon.com, E-mail: zgjennin@ucsc.edu [University of California Observatories, Santa Cruz, CA 95064 (United States)

2014-08-20

Using resolved stellar photometry measured from archival Hubble Space Telescope imaging, we generate color-magnitude diagrams of the stars within 50 pc of the locations of historic core-collapse supernovae (SNe) that took place in galaxies within 8 Mpc. We fit these color-magnitude distributions with stellar evolution models to determine the best-fit age distribution of the young population. We then translate these age distributions into probability distributions for the progenitor mass of each SN. The measurements are anchored by the main-sequence stars surrounding the event, making them less sensitive to assumptions about binarity, post-main-sequence evolution, or circumstellar dust. We demonstrate that, in cases where the literature contains masses that have been measured from direct imaging, our measurements are consistent with (but less precise than) these measurements. Using this technique, we constrain the progenitor masses of 17 historic SNe, 11 of which have no previous estimates from direct imaging. Our measurements still allow the possibility that all SN progenitor masses are <20 M {sub ☉}. However, the large uncertainties for the highest-mass progenitors also allow the possibility of no upper-mass cutoff.

Spatially Resolved Imaging and Spectroscopy of Candidate Dual Active Galactic Nuclei

Science.gov (United States)

McGurk, R. C.; Max, C. E.; Medling, A. M.; Shields, G. A.; Comerford, J. M.

2015-09-01

When galaxies merge, both central supermassive black holes are immersed in a dense and chaotic environment. If there is sufficient gas in the nuclear regions, one expects to see close pairs of active galactic nuclei (AGNs), or dual AGNs, in a fraction of galaxy mergers. However, finding them remains a challenge. The presence of double-peaked [O iii] emission lines has been proposed as a technique to select dual AGNs efficiently. We studied a sample of double-peaked narrow [O iii] emitting AGNs from Sloan Digital Sky Survey (SDSS) DR7. By obtaining new and archival high spatial resolution images taken with the Keck II Laser Guide Star Adaptive Optics system and the near-infrared camera NIRC2, we show that 30% of 140 double-peaked [O iii] emission line SDSS AGNs have two spatial components within a 3″ radius. However, spatially resolved spectroscopy or X-ray observations are needed to confirm these galaxy pairs as systems containing two AGNs. We followed up three spatially double candidate dual AGNs with integral field spectroscopy from Keck OSIRIS and 10 candidates with long-slit spectroscopy from the Shane Kast Double Spectrograph at Lick Observatory. We find that the double-peaked emission lines in our sample of 12 candidates are caused by: one dual AGN (SDSS J114642.47+511029.6), one confirmed outflow and four likely outflows, two pairs of star-forming galaxies, one candidate indeterminate due to sky line interference, and three AGNs with spatially coincident double [O iii] peaks, likely due to unresolved complex narrow line kinematics, outflows, binary AGN, or small-scale jets.

SPATIALLY RESOLVED IMAGING AND SPECTROSCOPY OF CANDIDATE DUAL ACTIVE GALACTIC NUCLEI

Energy Technology Data Exchange (ETDEWEB)

McGurk, R. C.; Max, C. E. [Astronomy Department and UCO-Lick Observatory, University of California, Santa Cruz, CA 95064 (United States); Medling, A. M. [Research School of Astronomy and Astrophysics, Australian National University, Mount Stromlo Observatory, Cotter Road, Weston Creek, ACT 2611 (Australia); Shields, G. A. [Laguna Falls Institute for Astrophysics, Austin, TX 78746 (United States); Comerford, J. M., E-mail: rosalie.mcgurk@gmail.com, E-mail: max@ucolick.org, E-mail: anne.medling@anu.edu.au, E-mail: shields@lfastro.org, E-mail: julie.comerford@colorado.edu [Department of Astrophysical and Planetary Sciences, University of Colorado, Boulder, CO 80309 (United States)

2015-09-20

When galaxies merge, both central supermassive black holes are immersed in a dense and chaotic environment. If there is sufficient gas in the nuclear regions, one expects to see close pairs of active galactic nuclei (AGNs), or dual AGNs, in a fraction of galaxy mergers. However, finding them remains a challenge. The presence of double-peaked [O iii] emission lines has been proposed as a technique to select dual AGNs efficiently. We studied a sample of double-peaked narrow [O iii] emitting AGNs from Sloan Digital Sky Survey (SDSS) DR7. By obtaining new and archival high spatial resolution images taken with the Keck II Laser Guide Star Adaptive Optics system and the near-infrared camera NIRC2, we show that 30% of 140 double-peaked [O iii] emission line SDSS AGNs have two spatial components within a 3″ radius. However, spatially resolved spectroscopy or X-ray observations are needed to confirm these galaxy pairs as systems containing two AGNs. We followed up three spatially double candidate dual AGNs with integral field spectroscopy from Keck OSIRIS and 10 candidates with long-slit spectroscopy from the Shane Kast Double Spectrograph at Lick Observatory. We find that the double-peaked emission lines in our sample of 12 candidates are caused by: one dual AGN (SDSS J114642.47+511029.6), one confirmed outflow and four likely outflows, two pairs of star-forming galaxies, one candidate indeterminate due to sky line interference, and three AGNs with spatially coincident double [O iii] peaks, likely due to unresolved complex narrow line kinematics, outflows, binary AGN, or small-scale jets.

SPATIALLY RESOLVED IMAGING AND SPECTROSCOPY OF CANDIDATE DUAL ACTIVE GALACTIC NUCLEI

International Nuclear Information System (INIS)

McGurk, R. C.; Max, C. E.; Medling, A. M.; Shields, G. A.; Comerford, J. M.

2015-01-01

When galaxies merge, both central supermassive black holes are immersed in a dense and chaotic environment. If there is sufficient gas in the nuclear regions, one expects to see close pairs of active galactic nuclei (AGNs), or dual AGNs, in a fraction of galaxy mergers. However, finding them remains a challenge. The presence of double-peaked [O iii] emission lines has been proposed as a technique to select dual AGNs efficiently. We studied a sample of double-peaked narrow [O iii] emitting AGNs from Sloan Digital Sky Survey (SDSS) DR7. By obtaining new and archival high spatial resolution images taken with the Keck II Laser Guide Star Adaptive Optics system and the near-infrared camera NIRC2, we show that 30% of 140 double-peaked [O iii] emission line SDSS AGNs have two spatial components within a 3″ radius. However, spatially resolved spectroscopy or X-ray observations are needed to confirm these galaxy pairs as systems containing two AGNs. We followed up three spatially double candidate dual AGNs with integral field spectroscopy from Keck OSIRIS and 10 candidates with long-slit spectroscopy from the Shane Kast Double Spectrograph at Lick Observatory. We find that the double-peaked emission lines in our sample of 12 candidates are caused by: one dual AGN (SDSS J114642.47+511029.6), one confirmed outflow and four likely outflows, two pairs of star-forming galaxies, one candidate indeterminate due to sky line interference, and three AGNs with spatially coincident double [O iii] peaks, likely due to unresolved complex narrow line kinematics, outflows, binary AGN, or small-scale jets

Spatially resolved NEXAFS spectroscopy of siderophores in biological matrices

International Nuclear Information System (INIS)

Thieme, J; Kilcoyne, D; Tyliszczak, T; Haselwandter, K

2013-01-01

Iron is an essential nutrient for almost all forms of life. In the presence of oxygen iron is present in its ferric form which precipitates under formation of rather insoluble oxide-hydroxide polymers. Hence the bioavailability of iron is extremely low ( −17 M at pH 7 for Fe 3+ ). Under such conditions almost all microorganisms synthesize siderophores as iron chelating agents, thus solubilizing ferric iron from rather insoluble iron sources. Siderophores form soluble complexes with Fe 3+ . The present study aims at developing a methodology that would allow for the specific detection and localization of such iron chelators in their natural environment. The applicability of spatially resolved NEXAFS spectroscopy in the soft X-ray energy (E < 1 keV) range was evaluated for localization of typical fungal hydroxamate siderophores like ferrichrome or coprogen, which can be present in various biological materials. Results obtained with the scanning transmission X-ray microscopes at beamlines 11.0.2 and 5.3.2 of the ALS have shown characteristic signatures for siderophores. Thus NEXAFS spectroscopy at the carbon K-edge, nitrogen K-edge and iron L-edge with high spatial resolution has proven to be extremely useful for their identification in their natural environment. Spectra of different siderophores as well as spectra and images of biological material containing siderophores are presented

Monthly and spatially resolved black carbon emission inventory of India: uncertainty analysis

Directory of Open Access Journals (Sweden)

U. Paliwal

2016-10-01

Full Text Available Black carbon (BC emissions from India for the year 2011 are estimated to be 901.11 ± 151.56 Gg yr−1 based on a new ground-up, GIS-based inventory. The grid-based, spatially resolved emission inventory includes, in addition to conventional sources, emissions from kerosene lamps, forest fires, diesel-powered irrigation pumps and electricity generators at mobile towers. The emissions have been estimated at district level and were spatially distributed onto grids at a resolution of 40 × 40 km2. The uncertainty in emissions has been estimated using a Monte Carlo simulation by considering the variability in activity data and emission factors. Monthly variation of BC emissions has also been estimated to account for the seasonal variability. To the total BC emissions, domestic fuels contributed most significantly (47 %, followed by industry (22 %, transport (17 %, open burning (12 % and others (2 %. The spatial and seasonal resolution of the inventory will be useful for modeling BC transport in the atmosphere for air quality, global warming and other process-level studies that require greater temporal resolution than traditional inventories.

Obtaining absolute spatial flux measurements with a time-resolved pinhole camera

International Nuclear Information System (INIS)

Baker, K.L.; Porter, J.L.; Ruggles, L.E.; Fehl, D.L.; Chandler, G.A.; Vargas, M.; Mix, L.P.; Simpson, W.W.; Deeney, C.; Chrien, R.E.; Idzorek, G.C.

1999-01-01

A technique is described to determine the spatial x-ray flux emitted from a hohlraum wall and subsequently transmitted through a diagnostic hole. This technique uses x-ray diodes, bolometers, and a time-resolved pinhole camera to determine the spatial flux of x rays emitted through a hohlraum close-quote s diagnostic hole. The primary motivation for this analysis was the relatively long duration, nearly 100 ns, of the x-ray drive present in z-pinch driven hohlraums. This radiation causes plasma to ablate from the hohlraum walls surrounding the diagnostic hole and results in a partial obscuration that reduces the effective area over which diagnostics view the radiation. The effective change in area leads to an underestimation of the wall temperature when nonimaging diagnostics such as x-ray diodes and bolometers are used to determine power and later to infer a wall temperature. An analysis similar to the one described below is then necessary to understand the radiation environment present in x-ray driven hohlraums when these diagnostics are used and hole closure is important. copyright 1999 American Institute of Physics

Spatially Resolved Artificial Chemistry

DEFF Research Database (Denmark)

Fellermann, Harold

2009-01-01

Although spatial structures can play a crucial role in chemical systems and can drastically alter the outcome of reactions, the traditional framework of artificial chemistry is a well-stirred tank reactor with no spatial representation in mind. Advanced method development in physical chemistry has...... made a class of models accessible to the realms of artificial chemistry that represent reacting molecules in a coarse-grained fashion in continuous space. This chapter introduces the mathematical models of Brownian dynamics (BD) and dissipative particle dynamics (DPD) for molecular motion and reaction...

Spatially Resolved Artificial Chemistry

DEFF Research Database (Denmark)

Fellermann, Harold

2009-01-01

made a class of models accessible to the realms of artificial chemistry that represent reacting molecules in a coarse-grained fashion in continuous space. This chapter introduces the mathematical models of Brownian dynamics (BD) and dissipative particle dynamics (DPD) for molecular motion and reaction......Although spatial structures can play a crucial role in chemical systems and can drastically alter the outcome of reactions, the traditional framework of artificial chemistry is a well-stirred tank reactor with no spatial representation in mind. Advanced method development in physical chemistry has...

Spatially resolved determination of the short-circuit current density of silicon solar cells via lock-in thermography

International Nuclear Information System (INIS)

Fertig, Fabian; Greulich, Johannes; Rein, Stefan

2014-01-01

We present a spatially resolved method to determine the short-circuit current density of crystalline silicon solar cells by means of lock-in thermography. The method utilizes the property of crystalline silicon solar cells that the short-circuit current does not differ significantly from the illuminated current under moderate reverse bias. Since lock-in thermography images locally dissipated power density, this information is exploited to extract values of spatially resolved current density under short-circuit conditions. In order to obtain an accurate result, one or two illuminated lock-in thermography images and one dark lock-in thermography image need to be recorded. The method can be simplified in a way that only one image is required to generate a meaningful short-circuit current density map. The proposed method is theoretically motivated, and experimentally validated for monochromatic illumination in comparison to the reference method of light-beam induced current.

Dwarf galaxies with ionizing radiation feedback. II. Spatially resolved star formation relation

International Nuclear Information System (INIS)

Kim, Ji-hoon; Krumholz, Mark R.; Goldbaum, Nathan J.; Wise, John H.; Turk, Matthew J.; Abel, Tom

2013-01-01

We investigate the spatially resolved star formation relation using a galactic disk formed in a comprehensive high-resolution (3.8 pc) simulation. Our new implementation of stellar feedback includes ionizing radiation as well as supernova explosions, and we handle ionizing radiation by solving the radiative transfer equation rather than by a subgrid model. Photoheating by stellar radiation stabilizes gas against Jeans fragmentation, reducing the star formation rate (SFR). Because we have self-consistently calculated the location of ionized gas, we are able to make simulated, spatially resolved observations of star formation tracers, such as Hα emission. We can also observe how stellar feedback manifests itself in the correlation between ionized and molecular gas. Applying our techniques to the disk in a galactic halo of 2.3 × 10 11 M ☉ , we find that the correlation between SFR density (estimated from mock Hα emission) and H 2 density shows large scatter, especially at high resolutions of ≲75 pc that are comparable to the size of giant molecular clouds (GMCs). This is because an aperture of GMC size captures only particular stages of GMC evolution and because Hα traces hot gas around star-forming regions and is displaced from the H 2 peaks themselves. By examining the evolving environment around star clusters, we speculate that the breakdown of the traditional star formation laws of the Kennicutt-Schmidt type at small scales is further aided by a combination of stars drifting from their birthplaces and molecular clouds being dispersed via stellar feedback.

Dwarf galaxies with ionizing radiation feedback. II. Spatially resolved star formation relation

Energy Technology Data Exchange (ETDEWEB)

Kim, Ji-hoon; Krumholz, Mark R.; Wise, John H.; Turk, Matthew J.; Goldbaum, Nathan J.; Abel, Tom

2013-11-15

AWe investigate the spatially resolved star formation relation using a galactic disk formed in a comprehensive high-resolution (3.8 pc) simulation. Our new implementation of stellar feedback includes ionizing radiation as well as supernova explosions, and we handle ionizing radiation by solving the radiative transfer equation rather than by a subgrid model. Photoheating by stellar radiation stabilizes gas against Jeans fragmentation, reducing the star formation rate (SFR). Because we have self-consistently calculated the location of ionized gas, we are able to make simulated, spatially resolved observations of star formation tracers, such as Hα emission. We can also observe how stellar feedback manifests itself in the correlation between ionized and molecular gas. Applying our techniques to the disk in a galactic halo of 2.3 × 10¹¹ M _⊙, we find that the correlation between SFR density (estimated from mock Hα emission) and H₂ density shows large scatter, especially at high resolutions of ≲ 75 pc that are comparable to the size of giant molecular clouds (GMCs). This is because an aperture of GMC size captures only particular stages of GMC evolution and because Hα traces hot gas around star-forming regions and is displaced from the H₂ peaks themselves. By examining the evolving environment around star clusters, we speculate that the breakdown of the traditional star formation laws of the Kennicutt-Schmidt type at small scales is further aided by a combination of stars drifting from their birthplaces and molecular clouds being dispersed via stellar feedback.

Spatially-resolved studies of charge-density-wave phase slip and dynamics in NbSe3

International Nuclear Information System (INIS)

Lemay, S.G.; Adelman, T.L.; Zaitsev-Zotov, S.V.; Thorne, R.E.

1999-01-01

We review our spatially and temporally resolved studies of charge-density-wave (CDW) phase slip and dynamics in NbSe 3 . Measurements of the steady-state CDW current, phase slip and strain profiles and their transient evolutions in response to a change in current direction provide a detailed picture of the interplay between elastic deformations and plasticity in this material. (orig.)

Last millennium Northern Hemisphere summer temperatures from tree rings: Part II, spatially resolved reconstructions

Science.gov (United States)

Anchukaitis, Kevin J.; Wilson, Rob; Briffa, Keith R.; Büntgen, Ulf; Cook, Edward R.; D'Arrigo, Rosanne; Davi, Nicole; Esper, Jan; Frank, David; Gunnarson, Björn E.; Hegerl, Gabi; Helama, Samuli; Klesse, Stefan; Krusic, Paul J.; Linderholm, Hans W.; Myglan, Vladimir; Osborn, Timothy J.; Zhang, Peng; Rydval, Milos; Schneider, Lea; Schurer, Andrew; Wiles, Greg; Zorita, Eduardo

2017-05-01

Climate field reconstructions from networks of tree-ring proxy data can be used to characterize regional-scale climate changes, reveal spatial anomaly patterns associated with atmospheric circulation changes, radiative forcing, and large-scale modes of ocean-atmosphere variability, and provide spatiotemporal targets for climate model comparison and evaluation. Here we use a multiproxy network of tree-ring chronologies to reconstruct spatially resolved warm season (May-August) mean temperatures across the extratropical Northern Hemisphere (40-90°N) using Point-by-Point Regression (PPR). The resulting annual maps of temperature anomalies (750-1988 CE) reveal a consistent imprint of volcanism, with 96% of reconstructed grid points experiencing colder conditions following eruptions. Solar influences are detected at the bicentennial (de Vries) frequency, although at other time scales the influence of insolation variability is weak. Approximately 90% of reconstructed grid points show warmer temperatures during the Medieval Climate Anomaly when compared to the Little Ice Age, although the magnitude varies spatially across the hemisphere. Estimates of field reconstruction skill through time and over space can guide future temporal extension and spatial expansion of the proxy network.

Simulations of the temporal and spatial resolution for a compact time-resolved electron diffractometer

Science.gov (United States)

Robinson, Matthew S.; Lane, Paul D.; Wann, Derek A.

2016-02-01

A novel compact electron gun for use in time-resolved gas electron diffraction experiments has recently been designed and commissioned. In this paper we present and discuss the extensive simulations that were performed to underpin the design in terms of the spatial and temporal qualities of the pulsed electron beam created by the ionisation of a gold photocathode using a femtosecond laser. The response of the electron pulses to a solenoid lens used to focus the electron beam has also been studied. The simulated results show that focussing the electron beam affects the overall spatial and temporal resolution of the experiment in a variety of ways, and that factors that improve the resolution of one parameter can often have a negative effect on the other. A balance must, therefore, be achieved between spatial and temporal resolution. The optimal experimental time resolution for the apparatus is predicted to be 416 fs for studies of gas-phase species, while the predicted spatial resolution of better than 2 nm-1 compares well with traditional time-averaged electron diffraction set-ups.

Effects of Electromagnetic Radiation from Smartphones on Learning Ability and Hippocampal Progenitor Cell Proliferation in Mice.

Science.gov (United States)

Choi, Yu-Jin; Choi, Yun-Sik

2016-02-01

Nonionizing radiation is emitted from electronic devices, such as smartphones. In this study, we intended to elucidate the effect of electromagnetic radiation from smartphones on spatial working memory and progenitor cell proliferation in the hippocampus. Both male and female mice were randomly separated into two groups (radiated and control) and the radiated group was exposed to electromagnetic radiation for 9 weeks and 11 weeks for male and female mice, respectively. Spatial working memory was examined with a Y maze, and proliferation of hippocampal progenitor cells were examined by 5-bromo-2'-deoxyuridine administration and immunohistochemical detection. When spatial working memory on a Y maze was examined in the 9(th) week, there was no significant difference in the spontaneous alternation score on the Y maze between the two groups. In addition, there was no significant difference in hippocampal progenitor cell proliferation. However, immunoreactivity to glial fibrillary acidic protein was increased in exposed animals. Next, to test the effect of recovery following chronic radiation exposure, the remaining female mice were further exposed to electromagnetic radiation for 2 more weeks (total 11 weeks), and spontaneous alternation was tested 4 weeks later. In this experiment, although there was no significant difference in the spontaneous alternation scores, the number of arm entry was significantly increased. These data indicate that although chronic electromagnetic radiation does not affect spatial working memory and hippocampal progenitor cell proliferation it can mediate astrocyte activation in the hippocampus and delayed hyperactivity-like behavior.

CO2 laser interferometer for temporally and spatially resolved electron density measurements

Science.gov (United States)

Brannon, P. J.; Gerber, R. A.; Gerardo, J. B.

1982-09-01

A 10.6-μm Mach-Zehnder interferometer has been constructed to make temporally and spatially resolved measurements of electron densities in plasmas. The device uses a pyroelectric vidicon camera and video memory to record and display the two-dimensional fringe pattern and a Pockels cell to limit the pulse width of the 10.6-μm radiation. A temporal resolution of 14 ns has been demonstrated. The relative sensitivity of the device for electron density measurements is 2×1015 cm-2 (the line integral of the line-of-sight length and electron density), which corresponds to 0.1 fringe shift.

CO2 laser interferometer for temporally and spatially resolved electron density measurements

International Nuclear Information System (INIS)

Brannon, P.J.; Gerber, R.A.; Gerardo, J.B.

1982-01-01

A 10.6-μm Mach--Zehnder interferometer has been constructed to make temporally and spatially resolved measurements of electron densities in plasmas. The device uses a pyroelectric vidicon camera and video memory to record and display the two-dimensional fringe pattern and a Pockels cell to limit the pulse width of the 10.6-μm radiation. A temporal resolution of 14 ns has been demonstrated. The relative sensitivity of the device for electron density measurements is 2 x 10 15 cm -2 (the line integral of the line-of-sight length and electron density), which corresponds to 0.1 fringe shift

Spatially resolved single crystal x-ray spectropolarimetry of wire array z-pinch plasmas.

Science.gov (United States)

Wallace, M S; Haque, S; Neill, P; Pereira, N R; Presura, R

2018-01-01

A recently developed single-crystal x-ray spectropolarimeter has been used to record paired sets of polarization-dependent and axially resolved x-ray spectra emitted by wire array z-pinches. In this measurement, two internal planes inside a suitable crystal diffract the x-rays into two perpendicular directions that are normal to each other, thereby separating incident x-rays into their linearly polarized components. This paper gives considerations for fielding the instrument on extended sources. Results from extended sources are difficult to interpret because generally the incident x-rays are not separated properly by the crystal. This difficulty is mitigated by using a series of collimating slits to select incident x-rays that propagate in a plane of symmetry between the polarization-splitting planes. The resulting instrument and some of the spatially resolved polarized x-ray spectra recorded for a 1-MA aluminum wire array z-pinch at the Nevada Terawatt Facility at the University of Nevada, Reno will be presented.

The very young resolved stellar populations around stripped-envelope supernovae

Science.gov (United States)

Maund, Justyn R.

2018-05-01

The massive star origins for Type IIP supernovae (SNe) have been established through direct detection of their red supergiants progenitors in pre-explosion observations; however, there has been limited success in the detection of the progenitors of H-deficient SNe. The final fate of more massive stars, capable of undergoing a Wolf-Rayet phase, and the origins of Type Ibc SNe remain debated, including the relative importance of single massive star progenitors or lower mass stars stripped in binaries. We present an analysis of the ages and spatial distributions of massive stars around the sites of 23 stripped-envelope SNe, as observed with the Hubble Space Telescope, to probe the possible origins of the progenitors of these events. Using a Bayesian stellar populations analysis scheme, we find characteristic ages for the populations observed within 150 pc of the target Type IIb, Ib, and Ic SNe to be log (t) = 7.20, 7.05, and 6.57, respectively. The Type Ic SNe in the sample are nearly all observed within 100 pc of young, dense stellar populations. The environment around SN 2002ap is an important exception both in terms of age and spatial properties. These findings may support the hypothesis that stars with Minit > 30 M⊙ produce a relatively large proportion of Type Ibc SNe, and that these SN subtypes arise from progressively more massive progenitors. Significantly higher extinctions are derived towards the populations hosting these SNe than previously used in analysis of constraints from pre-explosion observations. The large initial masses inferred for the progenitors are in stark contrast with the low ejecta masses estimated from SN light curves.

A spatially resolved radio spectral index study of the dwarf irregular galaxy NGC 1569

Science.gov (United States)

Westcott, Jonathan; Brinks, Elias; Hindson, Luke; Beswick, Robert; Heesen, Volker

2018-04-01

We study the resolved radio continuum spectral energy distribution of the dwarf irregular galaxy, NGC 1569, on a beam-by-beam basis to isolate and study its spatially resolved radio emission characteristics. Utilizing high-quality NRAO Karl G. Jansky Very Large Array observations that densely sample the 1-34 GHz frequency range, we adopt a Bayesian fitting procedure, where we use H α emission that has not been corrected for extinction as a prior, to produce maps of how the separated thermal emission, non-thermal emission, and non-thermal spectral index vary across NGC 1569's main disc. We find a higher thermal fraction at 1 GHz than is found in spiral galaxies (26^{+2}_{-3} {per cent}) and find an average non-thermal spectral index α = -0.53 ± 0.02, suggesting that a young population of cosmic ray electrons is responsible for the observed non-thermal emission. By comparing our recovered map of the thermal radio emission with literature H α maps, we estimate the total reddening along the line of sight to NGC 1569 to be E(B - V) = 0.49 ± 0.05, which is in good agreement with other literature measurements. Spatial variations in the reddening indicate that a significant portion of the total reddening is due to internal extinction within NGC 1569.

Spatially resolved spectra of the 'teacup' active galactic nucleus: tracing the history of a dying quasar

International Nuclear Information System (INIS)

Gagne, J. P.; Crenshaw, D. M.; Fischer, T. C.; Kraemer, S. B.; Schmitt, H. R.; Keel, W. C.; Rafter, S.; Bennert, V. N.; Schawinski, K.

2014-01-01

The Sloan Digital Sky Survey (SDSS) Galaxy Zoo project has revealed a number of spectacular galaxies possessing extended emission-line regions (EELRs), the most famous being Hanny's Voorwerp galaxy. We present another EELR object discovered in the SDSS endeavor: the Teacup active galactic nucleus (AGN). Nicknamed for its EELR, which has a 'handle'-like structure protruding 15 kpc into the northeast quadrant of the galaxy. We analyze the physical conditions of this galaxy with long-slit, ground-based spectroscopy from the Lowell, Lick, and KPNO observatories. With the Lowell 1.8 m Perkin's telescope we took multiple observations at different offset positions, allowing us to recover spatially resolved spectra across the galaxy. Line diagnostics indicate the ionized gas is photoionized primarily by the AGN. Additionally we are able to derive the hydrogen density from the [S II] λ6716/λ6731 ratio. We generated two-component photoionization models for each spatially resolved Lowell spectrum. These models allow us to calculate the AGN bolometric luminosity seen by the gas at different radii from the nuclear center of the Teacup. Our results show a drop in bolometric luminosity by more than two orders of magnitude from the EELR to the nucleus, suggesting that the AGN has decreased in luminosity by this amount in a continuous fashion over 46,000 yr, supporting the case for a dying AGN in this galaxy independent of any IR based evidence. We demonstrate that spatially resolved photoionization modeling could be applied to EELRs to investigate long timescale variability.

Spatially resolved spectra of the 'teacup' active galactic nucleus: tracing the history of a dying quasar

Energy Technology Data Exchange (ETDEWEB)

Gagne, J. P.; Crenshaw, D. M.; Fischer, T. C. [Department of Physics and Astronomy, Georgia State University, Astronomy Offices, 25 Park Place South SE, Suite 600, Atlanta, GA 30303 (United States); Kraemer, S. B. [Department of Physics, Catholic University of America, 620 Michigan Avenue, N.E., Washington, DC 20064 (United States); Schmitt, H. R. [Naval Research Laboratory, Washington, DC 20375 (United States); Keel, W. C. [Department of Physics and Astronomy, University of Alabama, Box 870324, Tuscaloosa, AL 35487 (United States); Rafter, S. [Physics Department, Technion, Haifa 32000 (Israel); Bennert, V. N. [Physics Department, California Polytechnic State University San Luis Obispo, CA 93407 (United States); Schawinski, K., E-mail: gagne@chara.gsu.edu [Institute for Astronomy, Department of Physics, ETH Zurich, Wolfgang-Pauli-Strasse 27, CH-8093 Zurich (Switzerland)

2014-09-01

The Sloan Digital Sky Survey (SDSS) Galaxy Zoo project has revealed a number of spectacular galaxies possessing extended emission-line regions (EELRs), the most famous being Hanny's Voorwerp galaxy. We present another EELR object discovered in the SDSS endeavor: the Teacup active galactic nucleus (AGN). Nicknamed for its EELR, which has a 'handle'-like structure protruding 15 kpc into the northeast quadrant of the galaxy. We analyze the physical conditions of this galaxy with long-slit, ground-based spectroscopy from the Lowell, Lick, and KPNO observatories. With the Lowell 1.8 m Perkin's telescope we took multiple observations at different offset positions, allowing us to recover spatially resolved spectra across the galaxy. Line diagnostics indicate the ionized gas is photoionized primarily by the AGN. Additionally we are able to derive the hydrogen density from the [S II] λ6716/λ6731 ratio. We generated two-component photoionization models for each spatially resolved Lowell spectrum. These models allow us to calculate the AGN bolometric luminosity seen by the gas at different radii from the nuclear center of the Teacup. Our results show a drop in bolometric luminosity by more than two orders of magnitude from the EELR to the nucleus, suggesting that the AGN has decreased in luminosity by this amount in a continuous fashion over 46,000 yr, supporting the case for a dying AGN in this galaxy independent of any IR based evidence. We demonstrate that spatially resolved photoionization modeling could be applied to EELRs to investigate long timescale variability.

Spatially resolved measurements of the magnetocaloric effect and the local magnetic field using thermography

DEFF Research Database (Denmark)

Christensen, Dennis; Bjørk, Rasmus; Nielsen, Kaspar Kirstein

2010-01-01

The magnetocaloric effect causes a magnetic material to change temperature upon application of a magnetic field. Here, spatially resolved measurements of the adiabatic temperature change are performed on a plate of gadolinium using thermography. The adiabatic temperature change is used to extract...... the corresponding change in the local magnetic field strength. The measured temperature change and local magnetic field strength are compared to results obtained with a numerical model, which takes demagnetization into account and employs experimental data....

Spatially resolved density and ionization measurements of shocked foams using x-ray fluorescence

Energy Technology Data Exchange (ETDEWEB)

MacDonald, M. J.; Keiter, P. A.; Montgomery, D. S.; Scott, H. A.; Biener, M. M.; Fein, J. R.; Fournier, K. B.; Gamboa, E. J.; Kemp, G. E.; Klein, S. R.; Kuranz, C. C.; LeFevre, H. J.; Manuel, M. J. -E.; Wan, W. C.; Drake, R. P.

2016-09-28

We present experiments at the Trident laser facility demonstrating the use of x-ray fluorescence (XRF) to simultaneously measure density, ionization state populations, and electron temperature in shocked foams. An imaging x-ray spectrometer obtained spatially resolved measurements of Ti K-α emission. Density profiles were measured from K-α intensity. Ti ionization state distributions and electron temperatures were inferred by fitting K-α spectra to spectra from CRETIN simulations. This work shows that XRF provides a powerful tool to complement other diagnostics to make equation of state measurements of shocked materials containing a suitable tracer element.

Fiber Bragg grating based spatially resolved characterization of flux-pinning induced strain of rectangular-shaped bulk YBCO samples

International Nuclear Information System (INIS)

Latka, Ines; Habisreuther, Tobias; Litzkendorf, Doris

2011-01-01

Highlights: → Fiber Bragg gratings (FBG) act as strain sensors, also at cryogenic temperatures. → FBGs are not sensitive to magnetic fields. → Local, shape dependent magnetostriction was detected on rectangular samples. → Magnetostrictive effects of the top surface and in a gap between two samples are different. - Abstract: We report on measurements of the spatially resolved characterization of flux-pinning induced strain of rectangular-shaped bulk YBCO samples. The spatially resolved strain measurements are accomplished by the use 2 fiber Bragg grating arrays, which are with an included angle of 45 o fixed to the surface. In this paper first attempts to confirm the shape distortions caused by the flux-pinning induced strain as predicted in will be presented. Two sample setups, a single bulk and a 'mirror' arrangement, will be compared. This mirror setup represents a model configuration for a measurement inside the superconductor, where demagnetization effects can be neglected and the magnetic field merely has a z-component.

Imaging buried organic islands by spatially resolved ballistic electron emission spectroscopy

International Nuclear Information System (INIS)

Goh, Kuan Eng J; Bannani, A; Troadec, C

2008-01-01

The well-known Au/n-Si(111) Schottky interface is modified by a discontinuous pentacene film (∼1.5 nm thick) and studied using spatially resolved ballistic electron emission spectroscopy (BEES). The pentacene film introduced subtle changes to the interface which cannot be definitively detected by current-voltage measurements or a standard BEES analysis of the barrier height. In contrast, analyzing the BEES results in a dual-parameter (transmission attenuation and barrier height) space allows the effect of the pentacene film on the Au/n-Si(111) interface to be clearly demonstrated. We found that the pentacene film behaves like a tunneling barrier and increases the distribution of local barrier heights with a tendency toward lower values. Our results highlight the potential of the dual-parameter BEES analysis for understanding local interface modification by molecules.

Two-Photon Irradiation of an Intracellular Singlet Oxygen Photosensitizer: Achieving Localized Sub-Cellular Excitation in Spatially-Resolved Experiments

DEFF Research Database (Denmark)

Pedersen, Brian Wett; Breitenbach, Thomas; Redmond, Robert W.

2010-01-01

The response of a given cell to spatially-resolved sub-cellular irradiation of a singlet oxygen photosensitizer (protoporphyrin IX, PpIX) using a focused laser was assessed. In these experiments, incident light was scattered over a volume greater than that defi ned by the dimensions of the laser...

Spatially resolved charge exchange flux calculations on the Toroidal Pumped Limiter of Tore Supra

International Nuclear Information System (INIS)

Marandet, Y.; Tsitrone, E.; Boerner, P.; Reiter, D.; Beaute, A.; Delchambre, E.; Escarguel, A.; Brezinsek, S.; Genesio, P.; Gunn, J.; Monier-Garbet, P.; Mitteau, R.; Pegourie, B.

2009-01-01

A spatially resolved calculation of the charge exchange particle and energy fluxes on the Toroidal Pumped Limiter (TPL) of Tore Supra is presented, as a first step towards a better understanding and modelling of carbon erosion, migration, as well as deuterium codeposition and bulk diffusion of deuterium in Tore Supra. The results are obtained with the EIRENE code run in a 3D geometry. Physical and chemical erosion maps on the TPL are calculated, and the contribution of neutrals to erosion, especially in the self-shadowed area, is calculated.

Spatially resolved δ13C analysis using laser ablation isotope ratio mass spectrometry

Science.gov (United States)

Moran, J.; Riha, K. M.; Nims, M. K.; Linley, T. J.; Hess, N. J.; Nico, P. S.

2014-12-01

Inherent geochemical, organic matter, and microbial heterogeneity over small spatial scales can complicate studies of carbon dynamics through soils. Stable isotope analysis has a strong history of helping track substrate turnover, delineate rhizosphere activity zones, and identifying transitions in vegetation cover, but most traditional isotope approaches are limited in spatial resolution by a combination of physical separation techniques (manual dissection) and IRMS instrument sensitivity. We coupled laser ablation sampling with isotope measurement via IRMS to enable spatially resolved analysis over solid surfaces. Once a targeted sample region is ablated the resulting particulates are entrained in a helium carrier gas and passed through a combustion reactor where carbon is converted to CO2. Cyrotrapping of the resulting CO2 enables a reduction in carrier gas flow which improves overall measurement sensitivity versus traditional, high flow sample introduction. Currently we are performing sample analysis at 50 μm resolution, require 65 ng C per analysis, and achieve measurement precision consistent with other continuous flow techniques. We will discuss applications of the laser ablation IRMS (LA-IRMS) system to microbial communities and fish ecology studies to demonstrate the merits of this technique and how similar analytical approaches can be transitioned to soil systems. Preliminary efforts at analyzing soil samples will be used to highlight strengths and limitations of the LA-IRMS approach, paying particular attention to sample preparation requirements, spatial resolution, sample analysis time, and the types of questions most conducive to analysis via LA-IRMS.

A split imaging spectrometer for temporally and spatially resolved titanium absorption spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Hager, J. D., E-mail: hager@lanl.gov; Lanier, N. E.; Kline, J. L.; Flippo, K. A. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Bruns, H. C.; Schneider, M.; Saculla, M.; McCarville, T. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)

2014-11-15

We present a temporally and a spatially resolved spectrometer for titanium x-ray absorption spectroscopy along 2 axial symmetric lines-of-sight. Each line-of-sight of the instrument uses an elliptical crystal to acquire both the 2p and 3p Ti absorption lines on a single, time gated channel of the instrument. The 2 axial symmetric lines-of-sight allow the 2p and 3p absorption features to be measured through the same point in space using both channels of the instrument. The spatially dependent material temperature can be inferred by observing the 2p and the 3p Ti absorption features. The data are recorded on a two strip framing camera with each strip collecting data from a single line-of-sight. The design is compatible for use at both the OMEGA laser and the National Ignition Facility. The spectrometer is intended to measure the material temperature behind a Marshak wave in a radiatively driven SiO{sub 2} foam with a Ti foam tracer. In this configuration, a broad band CsI backlighter will be used for a source and the Ti absorption spectrum measured.

Retinal Ganglion Cell Distribution and Spatial Resolving Power in Deep-Sea Lanternfishes (Myctophidae)

KAUST Repository

De Busserolles, Fanny

2014-01-01

Topographic analyses of retinal ganglion cell density are very useful in providing information about the visual ecology of a species by identifying areas of acute vision within the visual field (i.e. areas of high cell density). In this study, we investigated the neural cell distribution in the ganglion cell layer of a range of lanternfish species belonging to 10 genera. Analyses were performed on wholemounted retinas using stereology. Topographic maps were constructed of the distribution of all neurons and both ganglion and amacrine cell populations in 5 different species from Nissl-stained retinas using cytological criteria. Amacrine cell distribution was also examined immunohistochemically in 2 of the 5 species using anti-parvalbumin antibody. The distributions of both the total neuron and the amacrine cell populations were aligned in all of the species examined, showing a general increase in cell density toward the retinal periphery. However, when the ganglion cell population was topographically isolated from the amacrine cell population, which comprised up to 80% of the total neurons within the ganglion cell layer, a different distribution was revealed. Topographic maps of the true ganglion cell distribution in 18 species of lanternfishes revealed well-defined specializations in different regions of the retina. Different species possessed distinct areas of high ganglion cell density with respect to both peak density and the location and/or shape of the specialized acute zone (i.e. elongated areae ventro-temporales, areae temporales and large areae centrales). The spatial resolving power was calculated to be relatively low (varying from 1.6 to 4.4 cycles per degree), indicating that myctophids may constitute one of the less visually acute groups of deep-sea teleosts. The diversity in retinal specializations and spatial resolving power within the family is assessed in terms of possible ecological functions and evolutionary history.

Spatially resolved positron annihilation spectroscopy on friction stir weld induced defects.

Science.gov (United States)

Hain, Karin; Hugenschmidt, Christoph; Pikart, Philip; Böni, Peter

2010-04-01

A friction stir welded (FSW) Al alloy sample was investigated by Doppler broadening spectroscopy (DBS) of the positron annihilation line. The spatially resolved defect distribution showed that the material in the joint zone becomes completely annealed during the welding process at the shoulder of the FSW tool, whereas at the tip, annealing is prevailed by the deterioration of the material due to the tool movement. This might be responsible for the increased probability of cracking in the heat affected zone of friction stir welds. Examination of a material pairing of steel S235 and the Al alloy Silafont36 by coincident Doppler broadening spectroscopy (CDBS) indicates the formation of annealed steel clusters in the Al alloy component of the sample. The clear visibility of Fe in the CDB spectra is explained by the very efficient trapping at the interface between steel cluster and bulk.

Heat treatment of bovine bone preceding spatially resolved texture investigation by neutron diffraction

International Nuclear Information System (INIS)

Benmarouane, Abdelilah; Hansen, Thomas; Lodini, Alain

2004-01-01

Bone is a composite material of collagen and porous hydroxyapatite crystallites, aligned parallel to each other, with the c-axis parallel to the long axis of the fibre. Its texture and crystallinity has been investigated by means of neutron diffraction, using the high intensity 2-axis diffractometer D20 at ILL in particular. We show spatially resolved pole figures on a composite sample of two bone pieces of different preferred orientation. We have selected the (1 1 1) reflection, which is nearly not affected by texture to characterise the crystallinity index, and (0 0 2) to show the texture because the c-axes of hydroxyapatite crystallites is directed along the axis of the bone

Orientation Characterisation of Aerospace Materials by Spatially Resolved Acoustic Spectroscopy

International Nuclear Information System (INIS)

Li, Wenqi; Coulson, Jethro; Smith, Richard J; Clark, Matt; Somekh, Michael G; Sharples, Steve D; Aveson, John W

2014-01-01

Material characteristics in metals such as strength, stiffness and fracture resistance are strongly related to the underlying microstructure. The crystallographic structure and orientation are related to the ultrasonic properties through the stiffness matrix. In individual grains it is possible to analytically determine the ultrasonic velocity from the orientation and stiffness, or determine the stiffness from the known orientation and measured velocity. In this paper we present a technique for imaging the crystallographic orientation of grains in metals using spatially resolved acoustic spectroscopy (SRAS) and a novel inverse solver that can determine the crystallographic orientation from the known stiffness matrix for the material and the SRAS velocity measurement. Previously we have shown the ability of this technique to determine the orientation on single crystal nickel samples; we extended the technique to multigrain industrial metals, such as aluminium, nickel and Inconel. The comparison between SRAS and electron backscatter diffraction (EBSD) on the nickel sample is presented. SRAS is a fast, accurate, quantitative and robust technique for imaging material microstructure and orientation over a wide range of scales and industrial materials

Scanning mass spectrometer setup for spatially resolved reactivity studies on model catalysts

Energy Technology Data Exchange (ETDEWEB)

Roos, Matthias; Schirling, Christian; Kielbassa, Stefan; Bansmann, Joachim; Behm, Juergen [Institut fuer Oberflaechenchemie und Katalyse, Universitaet Ulm, D-89069 Ulm (Germany)

2007-07-01

A scanning mass spectrometer with micrometer-scale resolution was developed for investigations on the catalytic activity of microstructured planar model catalysts. Products of local surface reactions can be detected via a fine capillary orifice in a differentially pumped quadrupole mass spectrometer. The position of the sample with respect to the capillary is controlled by three piezo-driven translators. The surface reactivity of a resistive heated sample can be depicted in a spatially resolved topogram, taking into account the influence of the distance between sample and capillary on the magnitude of the QMS signal and the lateral resolution. Photolithographic structured reactive patterns on top of an inactive substrate enable investigations of mesoscopic transport effects such as coupling between catalytically active areas and of (reverse) spillover phenomena on one sample by varying the size and the distances of the active areas.

Neural Progenitors Adopt Specific Identities by Directly Repressing All Alternative Progenitor Transcriptional Programs.

Science.gov (United States)

Kutejova, Eva; Sasai, Noriaki; Shah, Ankita; Gouti, Mina; Briscoe, James

2016-03-21

In the vertebrate neural tube, a morphogen-induced transcriptional network produces multiple molecularly distinct progenitor domains, each generating different neuronal subtypes. Using an in vitro differentiation system, we defined gene expression signatures of distinct progenitor populations and identified direct gene-regulatory inputs corresponding to locations of specific transcription factor binding. Combined with targeted perturbations of the network, this revealed a mechanism in which a progenitor identity is installed by active repression of the entire transcriptional programs of other neural progenitor fates. In the ventral neural tube, sonic hedgehog (Shh) signaling, together with broadly expressed transcriptional activators, concurrently activates the gene expression programs of several domains. The specific outcome is selected by repressive input provided by Shh-induced transcription factors that act as the key nodes in the network, enabling progenitors to adopt a single definitive identity from several initially permitted options. Together, the data suggest design principles relevant to many developing tissues. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

A spatially and temporally resolved model of the electricity grid – Economic vs environmental dispatch

International Nuclear Information System (INIS)

Razeghi, Ghazal; Brouwer, Jack; Samuelsen, Scott

2016-01-01

Highlights: • A spatially and temporally resolved dispatch model is developed. • MCP and average price of electricity are determined for 2050 base case. • Economic and environmental dispatch strategies are assessed. • Environmental dispatch results in significant NO_x reduction and higher prices. • A combination of economic and environmental strategies is the preferred method. - Abstract: Substantial changes need to occur in the electricity generation sector in order to address greenhouse gas and urban air quality goals. These goals, combined with increasing energy prices, have led to elevated interest in alternative, low to zero carbon and pollutant emission technologies in this sector. The challenge is to assess the impacts of various technologies, policies, and market practices in order to develop a roadmap to meet energy and environmental goals. To this end, a spatially and temporally resolved resource dispatch model is developed that simulates an electricity market while taking into account physical constraints associated with various components of an electricity grid. Multiple technology simulation modules are developed to provide inputs to the model. The model is used to design a market-based grid, and to develop and evaluate different dispatch strategies. To maintain the system cost at acceptable levels and reduce emissions, the results reveal that the best approach is a combination of economic and environmental dispatch strategies. The methodology and the tools developed provide a means to examine various aspects of future scenarios and their impacts on different sectors, and can be used for both decision making and planning.

SDSS-IV MaNGA: Spatially Resolved Star Formation Main Sequence and LI(N)ER Sequence

Science.gov (United States)

Hsieh, B. C.; Lin, Lihwai; Lin, J. H.; Pan, H. A.; Hsu, C. H.; Sánchez, S. F.; Cano-Díaz, M.; Zhang, K.; Yan, R.; Barrera-Ballesteros, J. K.; Boquien, M.; Riffel, R.; Brownstein, J.; Cruz-González, I.; Hagen, A.; Ibarra, H.; Pan, K.; Bizyaev, D.; Oravetz, D.; Simmons, A.

2017-12-01

We present our study on the spatially resolved Hα and M * relation for 536 star-forming and 424 quiescent galaxies taken from the MaNGA survey. We show that the star formation rate surface density ({{{Σ }}}{SFR}), derived based on the Hα emissions, is strongly correlated with the M * surface density ({{{Σ }}}* ) on kiloparsec scales for star-forming galaxies and can be directly connected to the global star-forming sequence. This suggests that the global main sequence may be a consequence of a more fundamental relation on small scales. On the other hand, our result suggests that ∼20% of quiescent galaxies in our sample still have star formation activities in the outer region with lower specific star formation rate (SSFR) than typical star-forming galaxies. Meanwhile, we also find a tight correlation between {{{Σ }}}{{H}α } and {{{Σ }}}* for LI(N)ER regions, named the resolved “LI(N)ER” sequence, in quiescent galaxies, which is consistent with the scenario that LI(N)ER emissions are primarily powered by the hot, evolved stars as suggested in the literature.

Integrated circuit-based electrochemical sensor for spatially resolved detection of redox-active metabolites in biofilms.

Science.gov (United States)

Bellin, Daniel L; Sakhtah, Hassan; Rosenstein, Jacob K; Levine, Peter M; Thimot, Jordan; Emmett, Kevin; Dietrich, Lars E P; Shepard, Kenneth L

2014-01-01

Despite advances in monitoring spatiotemporal expression patterns of genes and proteins with fluorescent probes, direct detection of metabolites and small molecules remains challenging. A technique for spatially resolved detection of small molecules would benefit the study of redox-active metabolites that are produced by microbial biofilms and can affect their development. Here we present an integrated circuit-based electrochemical sensing platform featuring an array of working electrodes and parallel potentiostat channels. 'Images' over a 3.25 × 0.9 mm(2) area can be captured with a diffusion-limited spatial resolution of 750 μm. We demonstrate that square wave voltammetry can be used to detect, identify and quantify (for concentrations as low as 2.6 μM) four distinct redox-active metabolites called phenazines. We characterize phenazine production in both wild-type and mutant Pseudomonas aeruginosa PA14 colony biofilms, and find correlations with fluorescent reporter imaging of phenazine biosynthetic gene expression.

Retinal ganglion cell topography and spatial resolving power in penguins.

Science.gov (United States)

Coimbra, João Paulo; Nolan, Paul M; Collin, Shaun P; Hart, Nathan S

2012-01-01

Penguins are a group of flightless seabirds that exhibit numerous morphological, behavioral and ecological adaptations to their amphibious lifestyle, but little is known about the topographic organization of neurons in their retinas. In this study, we used retinal wholemounts and stereological methods to estimate the total number and topographic distribution of retinal ganglion cells in addition to an anatomical estimate of spatial resolving power in two species of penguins: the little penguin, Eudyptula minor, and the king penguin, Aptenodytes patagonicus. The total number of ganglion cells per retina was approximately 1,200,000 in the little penguin and 1,110,000 in the king penguin. The topographic distribution of retinal ganglion cells in both species revealed the presence of a prominent horizontal visual streak with steeper gradients in the little penguin. The little penguin retinas showed ganglion cell density peaks of 21,867 cells/mm², affording spatial resolution in water of 17.07-17.46 cycles/degree (12.81-13.09 cycles/degree in air). In contrast, the king penguin showed a relatively lower peak density of ganglion cells of 14,222 cells/mm², but--due to its larger eye--slightly higher spatial resolution in water of 20.40 cycles/degree (15.30 cycles/degree in air). In addition, we mapped the distribution of giant ganglion cells in both penguin species using Nissl-stained wholemounts. In both species, topographic mapping of this cell type revealed the presence of an area gigantocellularis with a concentric organization of isodensity contours showing a peak in the far temporal retina of approximately 70 cells/mm² in the little penguin and 39 cells/mm² in the king penguin. Giant ganglion cell densities gradually fall towards the outermost isodensity contours revealing the presence of a vertically organized streak. In the little penguin, we confirmed our cytological characterization of giant ganglion cells using immunohistochemistry for microtubule

Mesenchymal progenitor cells for the osteogenic lineage.

Science.gov (United States)

Ono, Noriaki; Kronenberg, Henry M

2015-09-01

Mesenchymal progenitors of the osteogenic lineage provide the flexibility for bone to grow, maintain its function and homeostasis. Traditionally, colony-forming-unit fibroblasts (CFU-Fs) have been regarded as surrogates for mesenchymal progenitors; however, this definition cannot address the function of these progenitors in their native setting. Transgenic murine models including lineage-tracing technologies based on the cre-lox system have proven to be useful in delineating mesenchymal progenitors in their native environment. Although heterogeneity of cell populations of interest marked by a promoter-based approach complicates overall interpretation, an emerging complexity of mesenchymal progenitors has been revealed. Current literatures suggest two distinct types of bone progenitor cells; growth-associated mesenchymal progenitors contribute to explosive growth of bone in early life, whereas bone marrow mesenchymal progenitors contribute to the much slower remodeling process and response to injury that occurs mainly in adulthood. More detailed relationships of these progenitors need to be studied through further experimentation.

Computation of the optical properties of turbid media from slope and curvature of spatially resolved reflectance curves

International Nuclear Information System (INIS)

Jäger, Marion; Foschum, Florian; Kienle, Alwin

2013-01-01

The optical properties of turbid media were calculated from the curvature at the radial distance ρ O and the slope at the radial distance ρ* of simulated spatially resolved reflectance curves (ρ O (ρ*) denotes a decrease of the spatially resolved reflectance curve of 0.75 (2.4) orders of magnitude relative to the reflectance value at 1.2 mm). We found correlations between the curvature at ρ O and the reduced scattering coefficient as well as the slope at ρ* and the absorption coefficient. For the determination of the optical properties we used these two correlations. The calculation of the reduced scattering coefficient from the curvature at ρ O is practically independent from the absorption coefficient. Knowing the reduced scattering coefficient within a certain accuracy allows the determination of the absorption coefficient from the slope at ρ*. Additionally, we investigated the performance of an artificial neural network for the determination of the optical properties using the above explained correlations. This means we used the derivatives as input data. Our artificial neural network was capable to learn the mapping between the optical properties and the derivatives. In effect, the results for the determined optical properties improved in comparison to the above explained method. Finally, the procedure was compared to an artificial neural network that was trained without using the derivatives. (note)

Spatially resolved Raman spectroscopy study of transformed zones in magnesia-partially-stabilized zirconia

International Nuclear Information System (INIS)

Davskardt, R.H.; Veirs, D.K.; Ritchie, R.O.

1989-01-01

Raman vibrational spectroscopy provides an effective phase characterization technique in materials systems containing particle dispersions of the tetragonal and monoclinic polymorphs of zirconia, each of which yields a unique Raman spectrum. An investigation is reported to assess a novel, spatially resolved Raman spectroscopy system in the study of transformed zones surrounding cracks in partially stabilized MgO-ZrO 2 (PSZ). The experimental arrangement uses an imaging (two-dimensional) photomultiplier tube to produce a one-dimensional Raman profile of phase compositions along a slitlike laser beam without translation of either the sample or the laser beam and without scanning the spectrometer. Results from phase characterization studies of the size, frontal morphology, and extent of transformation of transformation zones surrounding cracks produced under monotonic and cyclic loading conditions are presented

Spatially and time-resolved magnetization dynamics driven by spin-orbit torques

Science.gov (United States)

Baumgartner, Manuel; Garello, Kevin; Mendil, Johannes; Avci, Can Onur; Grimaldi, Eva; Murer, Christoph; Feng, Junxiao; Gabureac, Mihai; Stamm, Christian; Acremann, Yves; Finizio, Simone; Wintz, Sebastian; Raabe, Jörg; Gambardella, Pietro

2017-10-01

Current-induced spin-orbit torques are one of the most effective ways to manipulate the magnetization in spintronic devices, and hold promise for fast switching applications in non-volatile memory and logic units. Here, we report the direct observation of spin-orbit-torque-driven magnetization dynamics in Pt/Co/AlOx dots during current pulse injection. Time-resolved X-ray images with 25 nm spatial and 100 ps temporal resolution reveal that switching is achieved within the duration of a subnanosecond current pulse by the fast nucleation of an inverted domain at the edge of the dot and propagation of a tilted domain wall across the dot. The nucleation point is deterministic and alternates between the four dot quadrants depending on the sign of the magnetization, current and external field. Our measurements reveal how the magnetic symmetry is broken by the concerted action of the damping-like and field-like spin-orbit torques and the Dzyaloshinskii-Moriya interaction, and show that reproducible switching events can be obtained for over 1012 reversal cycles.

In situ distributed diagnostics of flowable electrode systems: resolving spatial and temporal limitations.

Science.gov (United States)

Dennison, C R; Gogotsi, Y; Kumbur, E C

2014-09-14

In this study, we have developed an in situ distributed diagnostics tool to investigate spatial and temporal effects in electrochemical systems based on flowable electrodes. Specifically, an experimental approach was developed that enables spatially-resolved voltage measurements to be obtained in situ, in real-time. To extract additional data from these distributed measurements, an experimentally-parameterized equivalent circuit model with a new 'flow capacitor' circuit element was developed to predict the distributions of various system parameters during operation. As a case study, this approach was applied to investigate the behavior of the suspension electrodes used in an electrochemical flow capacitor under flowing and static conditions. The volumetric capacitance is reduced from 15.6 F ml(-1) to 1.1 F ml(-1) under flowing conditions. Results indicate that the majority of the charging in suspension electrodes occurs within ∼750 μm of the current collectors during flow, which gives rise to significant state-of-charge gradients across the cell, as well as underutilization of the available active material. The underlying cause of this observation is attributed to the relatively high electrical resistance of the slurry coupled with a stratified charging regime and insufficient residence time. The observations highlight the need to develop more conductive slurries and to design cells with reduced charge transport lengths.

WHITE DWARF-RED DWARF SYSTEMS RESOLVED WITH THE HUBBLE SPACE TELESCOPE. II. FULL SNAPSHOT SURVEY RESULTS

International Nuclear Information System (INIS)

Farihi, J.; Hoard, D. W.; Wachter, S.

2010-01-01

Results are presented for a Hubble Space Telescope Advanced Camera for Surveys high-resolution imaging campaign of 90 white dwarfs with known or suspected low-mass stellar and substellar companions. Of the 72 targets that remain candidate and confirmed white dwarfs with near-infrared excess, 43 are spatially resolved into two or more components, and a total of 12 systems are potentially triples. For 68 systems where a comparison is possible, 50% have significant photometric distance mismatches between their white dwarf and M dwarf components, suggesting that white dwarf parameters derived spectroscopically are often biased due to the cool companion. Interestingly, 9 of the 30 binaries known to have emission lines are found to be visual pairs and hence widely separated, indicating an intrinsically active cool star and not irradiation from the white dwarf. There is a possible, slight deficit of earlier spectral types (bluer colors) among the spatially unresolved companions, exactly the opposite of expectations if significant mass is transferred to the companion during the common envelope phase. Using the best available distance estimates, the low-mass companions to white dwarfs exhibit a bimodal distribution in projected separation. This result supports the hypothesis that during the giant phases of the white dwarf progenitor, any unevolved companions either migrate inward to short periods of hours to days, or outward to periods of hundreds to thousands of years. No intermediate projected separations of a few to several AU are found among these pairs. However, a few double M dwarfs (within triples) are spatially resolved in this range, empirically demonstrating that such separations were readily detectable among the binaries with white dwarfs. A straightforward and testable prediction emerges: all spatially unresolved, low-mass stellar and substellar companions to white dwarfs should be in short-period orbits. This result has implications for substellar companion and

SDSS IV MaNGA: Dependence of Global and Spatially Resolved SFR–M ∗ Relations on Galaxy Properties

Science.gov (United States)

Pan, Hsi-An; Lin, Lihwai; Hsieh, Bau-Ching; Sánchez, Sebastián F.; Ibarra-Medel, Héctor; Boquien, Médéric; Lacerna, Ivan; Argudo-Fernández, Maria; Bizyaev, Dmitry; Cano-Díaz, Mariana; Drory, Niv; Gao, Yang; Masters, Karen; Pan, Kaike; Tabor, Martha; Tissera, Patricia; Xiao, Ting

2018-02-01

The galaxy integrated Hα star formation rate–stellar mass relation, or SFR(global)–M *(global) relation, is crucial for understanding star formation history and evolution of galaxies. However, many studies have dealt with SFR using unresolved measurements, which makes it difficult to separate out the contamination from other ionizing sources, such as active galactic nuclei and evolved stars. Using the integral field spectroscopic observations from SDSS-IV MaNGA, we spatially disentangle the contribution from different Hα powering sources for ∼1000 galaxies. We find that, when including regions dominated by all ionizing sources in galaxies, the spatially resolved relation between Hα surface density (ΣHα (all)) and stellar mass surface density (Σ*(all)) progressively turns over at the high Σ*(all) end for increasing M *(global) and/or bulge dominance (bulge-to-total light ratio, B/T). This in turn leads to the flattening of the integrated Hα(global)–M *(global) relation in the literature. By contrast, there is no noticeable flattening in both integrated Hα(H II)–M *(H II) and spatially resolved ΣHα (H II)–Σ*(H II) relations when only regions where star formation dominates the ionization are considered. In other words, the flattening can be attributed to the increasing regions powered by non-star-formation sources, which generally have lower ionizing ability than star formation. An analysis of the fractional contribution of non-star-formation sources to total Hα luminosity of a galaxy suggests a decreasing role of star formation as an ionizing source toward high-mass, high-B/T galaxies and bulge regions. This result indicates that the appearance of the galaxy integrated SFR–M * relation critically depends on their global properties (M *(global) and B/T) and relative abundances of various ionizing sources within the galaxies.

Investigation of microstructure in additive manufactured Inconel 625 by spatially resolved neutron transmission spectroscopy

Science.gov (United States)

Tremsin, Anton S.; Gao, Yan; Dial, Laura C.; Grazzi, Francesco; Shinohara, Takenao

2016-01-01

Non-destructive testing techniques based on neutron imaging and diffraction can provide information on the internal structure of relatively thick metal samples (up to several cm), which are opaque to other conventional non-destructive methods. Spatially resolved neutron transmission spectroscopy is an extension of traditional neutron radiography, where multiple images are acquired simultaneously, each corresponding to a narrow range of energy. The analysis of transmission spectra enables studies of bulk microstructures at the spatial resolution comparable to the detector pixel. In this study we demonstrate the possibility of imaging (with 100 μm resolution) distribution of some microstructure properties, such as residual strain, texture, voids and impurities in Inconel 625 samples manufactured with an additive manufacturing method called direct metal laser melting (DMLM). Although this imaging technique can be implemented only in a few large-scale facilities, it can be a valuable tool for optimization of additive manufacturing techniques and materials and for correlating bulk microstructure properties to manufacturing process parameters. In addition, the experimental strain distribution can help validate finite element models which many industries use to predict the residual stress distributions in additive manufactured components.

Spatially resolved element analysis of historical violin varnishes by use of muPIXE.

Science.gov (United States)

von Bohlen, Alex; Röhrs, Stefan; Salomon, Joseph

2007-02-01

External muPIXE has been used for characterisation of small samples of varnish from historical violins, and pieces of varnished wood from historical and modern stringed instruments. To obtain spatially resolved information about the distribution of elements across the varnish layers single-spot analysis, line-scans, and area-mapping were performed. Local resolution of approximately 20 mum was obtained from the 3 MeV, 1 nA proton micro-probe. Results from simultaneous multi-element determination of Na, Mg, Al, Si, P, S, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Br, Rb, Sr, Ag, Cd, Sn, Ba, and Pb in historical varnishes are presented. Semi-quantitative evaluation of line-scans recorded on diverse historical varnishes is reported. The applied method is discussed in detail and the results obtained are critically reviewed and compared with those in the literature.

Spatially resolved characterization of biogenic manganese oxideproduction within a bacterial biofilm

Energy Technology Data Exchange (ETDEWEB)

Toner, Brandy; Fakra, Sirine; Villalobos, Mario; Warwick, Tony; Sposito, Garrison

2004-10-01

Pseudomonas putida strain MnB1, a biofilm forming bacteria, was used as a model for the study of bacterial Mn oxidation in freshwater and soil environments. The oxidation of Mn{sub (aq)}{sup +2} by P. putida was characterized by spatially and temporally resolving the oxidation state of Mn in the presence of a bacterial biofilm using scanning transmission x-ray microscopy (STXM) combined with near edge x-ray absorption fine structure (NEXAFS) spectroscopy at the Mn-L{sub 2,3} absorption edges. Subsamples were collected from growth flasks containing 0.1 mM and 1 mM total Mn at 16, 24, 36 and 48 hours after inoculation. Immediately after collection, the unprocessed hydrated subsamples were imaged at 40 nm resolution. Manganese NEXAFS spectra were extracted from x-ray energy sequences of STXM images (stacks) and fit with linear combinations of well characterized reference spectra to obtain quantitative relative abundances of Mn(II), Mn(III) and Mn(IV). Careful consideration was given to uncertainty in the normalization of the reference spectra, choice of reference compounds, and chemical changes due to radiation damage. The STXM results confirm that Mn{sub (aq)}{sup +2} was removed from solution by P. putida and was concentrated as Mn(III) and Mn(IV) immediately adjacent to the bacterial cells. The Mn precipitates were completely enveloped by bacterial biofilm material. The distribution of Mn oxidation states was spatially heterogeneous within and between the clusters of bacterial cells. Scanning transmission x-ray microscopy is a promising tool to advance the study of hydrated interfaces between minerals and bacteria, particularly in cases where the structure of bacterial biofilms needs to be maintained.

Investigation of Co nanoparticle formation using time-dependent and spatially-resolved X-ray absorption spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Zinoveva, S

2008-04-15

A crucial step towards controlled synthesis of nanoparticles is the detailed understanding of the various chemical processes that take place during the synthesis. X-ray Absorption Spectroscopy (XAS) is especially suitable for elucidating the type and structure of the intermediate metal species. It is applicable to materials that have no long range order and provides information on both electronic and geometric structures. Here a comparative study is reported of the formation of cobalt nanoparticles via thermolysis of two organometallic precursors dicobalt octacarbonyl (DCO) and alkyne-bridged dicobalt hexacarbonyl (ADH) in the presence of aluminum organics. Using time-dependent XAS a reaction pathway different from both the atom based La Mer model and the Watzky and Finsky autocatalytic surface growth model is observed. Where prior to the nucleation several intermediates are formed and the initial nucleus is composed of Co atoms coordinated with ligands Co{sub n}(CO){sub m} with n=2-3, m=3-5. The formation of Co nanoparticles was also investigated using a reaction different from thermolysis of cobalt carbonyls, namely reduction of Co (II) acetate by sodium borohydrate. Here the combination of microreactor system and spatially resolved XAS allowed ''in situ'' monitoring of the wet chemical synthesis. Several steps of the reaction were spatially resolved in the microreactor. The vertical size of the X-ray beam (50 {mu}m) focused with Kirkpatrick-Baez mirror system, determines the time resolution (better than 2 ms). The results provide direct insight into rapid process of nanoparticles formation and demonstrate the potential of this new technique for the fundamental studies of such type of processes where miniaturization and timeresolution are important. Like in the carbonyls thermolysis no evidence for the reduction of the starting complex to isolated Co{sup 0} atoms followed by nucleation of Co{sup 0} atoms was observed. (orig.)

Investigation of Co nanoparticle formation using time-dependent and spatially-resolved X-ray absorption spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Zinoveva, S.

2008-04-15

A crucial step towards controlled synthesis of nanoparticles is the detailed understanding of the various chemical processes that take place during the synthesis. X-ray Absorption Spectroscopy (XAS) is especially suitable for elucidating the type and structure of the intermediate metal species. It is applicable to materials that have no long range order and provides information on both electronic and geometric structures. Here a comparative study is reported of the formation of cobalt nanoparticles via thermolysis of two organometallic precursors dicobalt octacarbonyl (DCO) and alkyne-bridged dicobalt hexacarbonyl (ADH) in the presence of aluminum organics. Using time-dependent XAS a reaction pathway different from both the atom based La Mer model and the Watzky and Finsky autocatalytic surface growth model is observed. Where prior to the nucleation several intermediates are formed and the initial nucleus is composed of Co atoms coordinated with ligands Co{sub n}(CO){sub m} with n=2-3, m=3-5. The formation of Co nanoparticles was also investigated using a reaction different from thermolysis of cobalt carbonyls, namely reduction of Co (II) acetate by sodium borohydrate. Here the combination of microreactor system and spatially resolved XAS allowed ''in situ'' monitoring of the wet chemical synthesis. Several steps of the reaction were spatially resolved in the microreactor. The vertical size of the X-ray beam (50 {mu}m) focused with Kirkpatrick-Baez mirror system, determines the time resolution (better than 2 ms). The results provide direct insight into rapid process of nanoparticles formation and demonstrate the potential of this new technique for the fundamental studies of such type of processes where miniaturization and timeresolution are important. Like in the carbonyls thermolysis no evidence for the reduction of the starting complex to isolated Co{sup 0} atoms followed by nucleation of Co{sup 0} atoms was observed. (orig.)

Progenitor Epithelium

Science.gov (United States)

Marty-Santos, Leilani

2015-01-01

Insulin-producing β cells within the vertebrate fetal pancreas acquire their fate in a step-wise manner. Whereas the intrinsic factors dictating the transcriptional or epigenetic status of pancreatic lineages have been intensely examined, less is known about cell–cell interactions that might constitute a niche for the developing β cell lineage. It is becoming increasingly clear that understanding and recapitulating these steps may instruct in vitro differentiation of embryonic stem cells and/or therapeutic regeneration. Indeed, directed differentiation techniques have improved since transitioning from 2D to 3D cultures, suggesting that the 3D microenvironment in which β cells are born is critical. However, to date, it remains unknown whether the changing architecture of the pancreatic epithelium impacts the fate of cells therein. An emerging challenge in the field is to elucidate how progenitors are allocated during key events, such as the stratification and subsequent resolution of the pre-pancreatic epithelium, as well as the formation of lumens and branches. Here, we assess the progenitor epithelium and examine how it might influence the emergence of pancreatic multipotent progenitors (MPCs), which give rise to β cells and other pancreatic lineages. PMID:26216134

Progenitor cells in pulmonary vascular remodeling

Science.gov (United States)

Yeager, Michael E.; Frid, Maria G.; Stenmark, Kurt R.

2011-01-01

Pulmonary hypertension is characterized by cellular and structural changes in the walls of pulmonary arteries. Intimal thickening and fibrosis, medial hypertrophy and fibroproliferative changes in the adventitia are commonly observed, as is the extension of smooth muscle into the previously non-muscularized vessels. A majority of these changes are associated with the enhanced presence of α-SM-actin+ cells and inflammatory cells. Atypical abundances of functionally distinct endothelial cells, particularly in the intima (plexiform lesions), and also in the perivascular regions, are also described. At present, neither the origin(s) of these cells nor the molecular mechanisms responsible for their accumulation, in any of the three compartments of the vessel wall, have been fully elucidated. The possibility that they arise from either resident vascular progenitors or bone marrow–derived progenitor cells is now well established. Resident vascular progenitor cells have been demonstrated to exist within the vessel wall, and in response to certain stimuli, to expand and express myofibroblastic, endothelial or even hematopoietic markers. Bone marrow–derived or circulating progenitor cells have also been shown to be recruited to sites of vascular injury and to assume both endothelial and SM-like phenotypes. Here, we review the data supporting the contributory role of vascular progenitors (including endothelial progenitor cells, smooth muscle progenitor cells, pericytes, and fibrocytes) in vascular remodeling. A more complete understanding of the processes by which progenitor cells modulate pulmonary vascular remodeling will undoubtedly herald a renaissance of therapies extending beyond the control of vascular tonicity and reduction of pulmonary artery pressure. PMID:22034593

A SPATIALLY RESOLVED INNER HOLE IN THE DISK AROUND GM AURIGAE

International Nuclear Information System (INIS)

Hughes, A. Meredith; Andrews, Sean M.; Wilner, David J.; Qi Chunhua; Espaillat, Catherine; Calvet, Nuria; D'Alessio, Paola; Williams, Jonathan P.; Hogerheijde, Michiel R.

2009-01-01

We present 0.''3 resolution observations of the disk around GM Aurigae with the Submillimeter Array (SMA) at a wavelength of 860 μm and with the Plateau de Bure Interferometer at a wavelength of 1.3 mm. These observations probe the distribution of disk material on spatial scales commensurate with the size of the inner hole predicted by models of the spectral energy distribution (SED). The data clearly indicate a sharp decrease in millimeter optical depth at the disk center, consistent with a deficit of material at distances less than ∼20 AU from the star. We refine the accretion disk model of Calvet et al. based on the unresolved SED and demonstrate that it reproduces well the spatially resolved millimeter continuum data at both available wavelengths. We also present complementary SMA observations of CO J = 3-2 and J = 2-1 emission from the disk at 2'' resolution. The observed CO morphology is consistent with the continuum model prediction, with two significant deviations: (1) the emission displays a larger CO J = 3-2/J = 2-1 line ratio than predicted, which may indicate additional heating of gas in the upper disk layers; and (2) the position angle of the kinematic rotation pattern differs by 11 deg. ± 2 deg. from that measured at smaller scales from the dust continuum, which may indicate the presence of a warp. We note that photoevaporation, grain growth, and binarity are unlikely mechanisms for inducing the observed sharp decrease in opacity or surface density at the disk center. The inner hole plausibly results from the dynamical influence of a planet on the disk material. Warping induced by a planet could also potentially explain the difference in position angle between the continuum and CO data sets.

SPATIALLY RESOLVED SPECTROSCOPY OF EUROPA: THE DISTINCT SPECTRUM OF LARGE-SCALE CHAOS

International Nuclear Information System (INIS)

Fischer, P. D.; Brown, M. E.; Hand, K. P.

2015-01-01

We present a comprehensive analysis of spatially resolved moderate spectral resolution near-infrared spectra obtained with the adaptive optics system at the Keck Observatory. We identify three compositionally distinct end member regions: the trailing hemisphere bullseye, the leading hemisphere upper latitudes, and a third component associated with leading hemisphere chaos units. We interpret the composition of the three end member regions to be dominated by irradiation products, water ice, and evaporite deposits or salt brines, respectively. The third component is associated with geological features and distinct from the geography of irradiation, suggesting an endogenous identity. Identifying the endogenous composition is of particular interest for revealing the subsurface composition. However, its spectrum is not consistent with linear mixtures of the salt minerals previously considered relevant to Europa. The spectrum of this component is distinguished by distorted hydration features rather than distinct spectral features, indicating hydrated minerals but making unique identification difficult. In particular, it lacks features common to hydrated sulfate minerals, challenging the traditional view of an endogenous salty component dominated by Mg-sulfates. Chloride evaporite deposits are one possible alternative

SPATIALLY RESOLVED SPECTROSCOPY OF EUROPA: THE DISTINCT SPECTRUM OF LARGE-SCALE CHAOS

Energy Technology Data Exchange (ETDEWEB)

Fischer, P. D.; Brown, M. E. [Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125 (United States); Hand, K. P., E-mail: pfischer@caltech.edu [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States)

2015-11-15

We present a comprehensive analysis of spatially resolved moderate spectral resolution near-infrared spectra obtained with the adaptive optics system at the Keck Observatory. We identify three compositionally distinct end member regions: the trailing hemisphere bullseye, the leading hemisphere upper latitudes, and a third component associated with leading hemisphere chaos units. We interpret the composition of the three end member regions to be dominated by irradiation products, water ice, and evaporite deposits or salt brines, respectively. The third component is associated with geological features and distinct from the geography of irradiation, suggesting an endogenous identity. Identifying the endogenous composition is of particular interest for revealing the subsurface composition. However, its spectrum is not consistent with linear mixtures of the salt minerals previously considered relevant to Europa. The spectrum of this component is distinguished by distorted hydration features rather than distinct spectral features, indicating hydrated minerals but making unique identification difficult. In particular, it lacks features common to hydrated sulfate minerals, challenging the traditional view of an endogenous salty component dominated by Mg-sulfates. Chloride evaporite deposits are one possible alternative.

Spatial-Resolved Measurement and Analysis of Extreme-Ultraviolet Emission Spectra from Laser-Produced Al Plasmas

International Nuclear Information System (INIS)

Cao Shi-Quan; Su Mao-Gen; Sun Dui-Xiong; Min Qi; Dong Chen-Zhong

2016-01-01

Extreme ultraviolet emission from laser-produced Al plasma is experimentally and theoretically investigated. Spatial-evolution emission spectra are measured by using the spatio-temporally resolved laser produced plasma technique. Based on the assumptions of a normalized Boltzmann distribution among the excited states and a steady-state collisional-radiative model, we succeed in reproducing the spectra at different detection positions, which are in good agreement with experiments. The decay curves about the electron temperature and electron density, as well as the fractions of individual Al ions and average ionization stage with increasing the detection distance are obtained by comparison with the experimental measurements. These parameters are critical points for deeply understanding the expanding and cooling of laser produced plasmas in vacuum. (paper)

Spatially resolved soft x-ray diagnostics in fusion energy research

International Nuclear Information System (INIS)

Mlynar, J.; Weinzettl, V.; Imrisek, M.; Loeffelmann, V.

2013-01-01

With construction of ITER, the fusion community has progressed into a new stage of research with increased focus on reactor technologies. Corresponding development of diagnostic systems for fusion is required, including research of novel diagnostic methods, validation of radiation hard detectors, and tests of sensors for real-time operation and control, which comprise development of tools for fast data analyses. In parallel, diagnostic systems on running fusion experiments substantially contribute to better understanding of reactor-relevant plasma physics, in particular of energy confinement, plasma stability and transport of impurities. In this respect, spatially resolved Soft X-ray (SXR) diagnostic systems present an interesting case study of development towards reactor-relevant systems. In magnetic confinement fusion research, spatial distribution of SXR radiation with spectral range typically 1 keV - 15 keV is mostly measured by a photosensitive single-row semiconductor elements in a pinhole camera shielded by a beryllium foil. The SXR intensity strongly depends on plasma density, temperature and effective charge, which carry a valuable information on the plasma core physics. Data from SXR diagnostic can be also used for the operation control, among others due to their sensitivity to heavy impurity concentration or to the position of the peak temperature. In order to reconstruct the spatial distribution of SXR plasma emission from the measured line integrated signals, several tomographic methods have been developed and validated. However, the semiconductor elements cannot survive in harsh conditions of future fusion reactors due to radiation damage, which calls for development of radiation hard SXR cameras. In this contribution, role of the SXR diagnostics will be presented in experience and future plans of the Czech tokamak COMPASS (IPP Prague) and the French tokamak TORE SUPRA (CEA Cadarache). In IPP Prague, data from SXR cameras recently contributed to

Fast spatially resolved exhaust gas recirculation (EGR) distribution measurements in an internal combustion engine using absorption spectroscopy.

Science.gov (United States)

Yoo, Jihyung; Prikhodko, Vitaly; Parks, James E; Perfetto, Anthony; Geckler, Sam; Partridge, William P

2015-09-01

Exhaust gas recirculation (EGR) in internal combustion engines is an effective method of reducing NOx emissions while improving efficiency. However, insufficient mixing between fresh air and exhaust gas can lead to cycle-to-cycle and cylinder-to-cylinder non-uniform charge gas mixtures of a multi-cylinder engine, which can in turn reduce engine performance and efficiency. A sensor packaged into a compact probe was designed, built and applied to measure spatiotemporal EGR distributions in the intake manifold of an operating engine. The probe promotes the development of more efficient and higher-performance engines by resolving high-speed in situ CO2 concentration at various locations in the intake manifold. The study employed mid-infrared light sources tuned to an absorption band of CO2 near 4.3 μm, an industry standard species for determining EGR fraction. The calibrated probe was used to map spatial EGR distributions in an intake manifold with high accuracy and monitor cycle-resolved cylinder-specific EGR fluctuations at a rate of up to 1 kHz.

Transplanting oligodendrocyte progenitors into the adult CNS

International Nuclear Information System (INIS)

Franklin, R.J.M.; Blakemore, W.F.; Cambridge Univ.

1997-01-01

This review covers a number of aspects of the behaviour of oligodendrocyte progenitors following transplantation into the adult CNS. First, an account is given of the ability of transplanted oligodendrocyte progenitors, grown in tissue culture in the presence of PDGF and bFGF, to extensively remyelinate focal areas of persistent demyelination. Secondly, we describe how transplanted clonal cell lines of oligodendrocyte progenitors will differentiate in to astrocytes as will oligodendrocytes following transplantation into pathological environments in which both oligodendrocytes and astrocytes are absent, thereby manifesting the bipotentially demonstrable in vitro but not during development. Finally, a series of studies examining the migratory behaviour of transplanted oligodendrocyte progenitors (modelled using the oligodendrocyte progenitor cell line CG4) are described. (author)

Origin of hemopoietic stromal progenitor cells in chimeras

International Nuclear Information System (INIS)

Chertkov, J.L.; Drize, N.J.; Gurevitch, O.A.; Samoylova, R.S.

1985-01-01

Intravenously injected bone marrow cells do not participate in the regeneration of hemopoietic stromal progenitors in irradiated mice, nor in the curetted parts of the recipient's marrow. The hemopoietic stromal progenitors in allogeneic chimeras are of recipient origin. The adherent cell layer (ACL) of long-term cultures of allogeneic chimera bone marrow contains only recipient hemopoietic stromal progenitors. However, in ectopic hemopoietic foci produced by marrow implantation under the renal capsule and repopulated by the recipient hemopoietic cells after irradiation and reconstitution by syngeneic hemopoietic cells, the stromal progenitors were of implant donor origin, as were stromal progenitors of the ACL in long-term cultures of hemopoietic cells from ectopic foci. Our results confirm that the stromal and hemopoietic progenitors differ in origin and that hemopoietic stromal progenitors are not transplantable by the intravenous route in mice

Spatially and spectrally resolved photoluminescence of InGaN MQWs grown on highly Si doped a-plane GaN buffer

Energy Technology Data Exchange (ETDEWEB)

Thunert, Martin; Wieneke, Matthias; Dempewolf, Anja; Bertram, Frank; Dadgar, Armin; Krost, Alois; Christen, Juergen [Institute of Experimental Physics, Otto-von-Guericke-University Magdeburg (Germany)

2011-07-01

A set of InGaN multi quantum well (MQW) samples grown by MOVPE on highly Si doped a-plane GaN on r-plane sapphire templates has been investigated using spatially resolved photoluminescence spectroscopy ({mu}-PL). The Si doping level of nominal about 10{sup 20} cm{sup -3} leads to three dimensionally grown crystallites mostly terminated by m-facets. The MQW thickness has been systematically varied from nominally 2.1 to 4.2 nm, as well as the InGaN growth temperature, which was varied from 760 C to 700 C. The growth of a-plane GaN based devices leads to a non-polar growth direction avoiding the polarization field affected Quantum-Confined-Stark-Effect. Spatially resolved PL studies show for all samples low near band edge (NBE) GaN emission intensity over the whole area under investigation accompanied by highly intense InGaN MQW emission for single crystallites. The MQW luminescence shows a systematic blueshift with increasing InGaN growth temperature due to lower In incorporation as well as a systematic redshift with increasing MQW thickness. Excitation power dependent spectra at 4 K as well as temperature dependent PL spectra will be presented.

Reactor for in situ measurements of spatially resolved kinetic data in heterogeneous catalysis

Science.gov (United States)

Horn, R.; Korup, O.; Geske, M.; Zavyalova, U.; Oprea, I.; Schlögl, R.

2010-06-01

The present work describes a reactor that allows in situ measurements of spatially resolved kinetic data in heterogeneous catalysis. The reactor design allows measurements up to temperatures of 1300 °C and 45 bar pressure, i.e., conditions of industrial relevance. The reactor involves reactants flowing through a solid catalyst bed containing a sampling capillary with a side sampling orifice through which a small fraction of the reacting fluid (gas or liquid) is transferred into an analytical device (e.g., mass spectrometer, gas chromatograph, high pressure liquid chromatograph) for quantitative analysis. The sampling capillary can be moved with μm resolution in or against flow direction to measure species profiles through the catalyst bed. Rotation of the sampling capillary allows averaging over several scan lines. The position of the sampling orifice is such that the capillary channel through the catalyst bed remains always occupied by the capillary preventing flow disturbance and fluid bypassing. The second function of the sampling capillary is to provide a well which can accommodate temperature probes such as a thermocouple or a pyrometer fiber. If a thermocouple is inserted in the sampling capillary and aligned with the sampling orifice fluid temperature profiles can be measured. A pyrometer fiber can be used to measure the temperature profile of the solid catalyst bed. Spatial profile measurements are demonstrated for methane oxidation on Pt and methane oxidative coupling on Li/MgO, both catalysts supported on reticulated α -Al2O3 foam supports.

Spatially resolved characterization in thin-film photovoltaics

CERN Document Server

Bokalic, Matevz

2015-01-01

The book is devoted to the spatial characterization of solar cells and PV modules. It is written both as a monograph as well as a succinct guide for the state-of-the-art spatial characterization techniques and approaches. Amongst the approaches discussed are visual imaging, electro- and photo-luminescence imaging, thermography, and light beam induced mapping techniques. Emphasis is given on the luminescence image acquisition and interpretation due to its great potential. Characterization techniques are accompanied by simulation tools. The contents are aimed at a readership of students and s

Zooming into Molecular Biomarker Distribution through Spatially Resolved Mass Spectrometry on Intact Sediment Sections

Science.gov (United States)

Wörmer, L.; Fuchser, J.; Alfken, S.; Elvert, M.; Schimmelmann, A.; Hinrichs, K. U.

2016-02-01

Marine microorganisms adapt to their habitat by structural modification of their membrane lipids. After sedimentation, and due to their persistence in the sedimentary record, the information archived in them remains available on geological time-scales. Thereby sedimentary lipid biomarkers become important informants of past environments. Conventional biomarker analysis is labor-intensive and requires cm-sized samples, temporal resolution is consequently low. We here present an approach, based on laser desorption ionization (LDI) coupled to ultra high resolution mass spectrometry, that avoids wet-chemical sample preparation and enables analysis directly on sediment sections at sub-mm spatial resolution. Our initial study targeted archaeal glycerol dialkyl glycerol tetraethers (GDGTs). GDGTS are ubiquitous and persistent components in marine sediments, and used in several, widely recognized paleoenvironmental proxies. Applied to an Eastern Mediterranean Sapropel layer, GDGT-profiles with previously unachieved temporal resolution were obtained, and pointed to a strong influence of high frequency cycles on sea-surface temperature and planktonic archaeal ecology. Spatial information furthermore revealed a new view on the fine-scale patchiness of lipid distribution. Following these pioneering studies, major developments are under way. A dedicated facility has been set up at MARUM/University of Bremen, which combines lipid biomarker and elemental analysis at sub-mm resolution (down to 50 µm). We present methods for other comprehensive lipid biomarkers (e.g. alkenones or sterols) that are currently being targeted; and the application of spatially resolved biomarker analysis to recent laminated sediments (Santa Barbara Basin), yielding informative profiles with subannual resolution. We also discuss criteria for analyte and sample selection, as well as the main potentialities and constraints of this new approach.

Radiative and magnetic properties of solar active regions. II. Spatially resolved analysis of O V 62.97 nm transition region emission

Science.gov (United States)

Fludra, A.; Warren, H.

2010-11-01

Context. Global relationships between the photospheric magnetic flux and the extreme ultraviolet emission integrated over active region area have been studied in a previous paper by Fludra & Ireland (2008, A&A, 483, 609). Spatially integrated EUV line intensities are tightly correlated with the total unsigned magnetic flux, and yet these global power laws have been shown to be insufficient for accurately determining the coronal heating mechanism owing to the mathematical ill-conditioning of the inverse problem. Aims: Our aim is to establish a relationship between the EUV line intensities and the photospheric magnetic flux density on small spatial scales in active regions and investigate whether it provides a way of identifying the process that heats the coronal loops. Methods: We compare spatially resolved EUV transition region emission and the photospheric magnetic flux density. This analysis is based on the O V 62.97 nm line recorded by the SOHO Coronal Diagnostic Spectrometer (CDS) and SOHO MDI magnetograms for six solar active regions. The magnetic flux density ϕ is converted to a simulated O V intensity using a model relationship I(ϕ, L) = Cϕδ Lλ, where the loop length L is obtained from potential magnetic field extrapolations. This simulated spatial distribution of O V intensities is convolved with the CDS instrument's point spread function and compared pixel by pixel with the observed O V line intensity. Parameters δ and λ are derived to give the best fit for the observed and simulated intensities. Results: Spatially-resolved analysis of the transition region emission reveals the complex nature of the heating processes in active regions. In some active regions, particularly large, local intensity enhancements up to a factor of five are present. When areas with O V intensities above 3000 erg cm-2 s-1 sr-1 are ignored, a power law has been fitted to the relationship between the local O V line intensity and the photospheric magnetic flux density in each

Tunable Reflective Spatial Heterodyne Spectrometer: A Technique for High Resolving Power, Wide Field Of View Observation Of Diffuse Emission Line Sources

Science.gov (United States)

Hosseini, Seyedeh Sona

The purpose of this dissertation is to discuss the need for new technology in broadband high-resolution spectroscopy based on the emerging technique of Spatial Heterodyne Spectroscopy (SHS) and to propose new solutions that should enhance and generalize this technology to other fields. Spectroscopy is a proven tool for determining compositional and other properties of remote objects. Narrow band imaging and low resolving spectroscopic measurements provide information about composition, photochemical evolution, energy distribution and density. The extension to high resolving power provides further access to temperature, velocity, isotopic ratios, separation of blended sources, and opacity effects. In current high resolving power devices, the drawback of high-resolution spectroscopy is bound to the instrumental limitations of lower throughput, the necessity of small entrance apertures, sensitivity, field of view, and large physical instrumental size. These limitations quickly become handicapping for observation of faint and/or extended targets and for spacecraft encounters. A technique with promise for the study of faint and extended sources at high resolving power is the reflective format of the Spatial Heterodyne Spectrometer (SHS). SHS instruments are compact and naturally tailored for both high etendue (defined in section 2.2.5) and high resolving power. In contrast, to achieve similar spectral grasp, grating spectrometers require large telescopes. For reference, SHS is a cyclical interferometer that produces Fizeau fringe pattern for all other wavelengths except the tuned wavelength. The large etendue obtained by SHS instruments makes them ideal for observations of extended, low surface brightness, isolated emission line sources, while their intrinsically high spectral resolution enables one to study the dynamical and physical properties described above. This document contains four chapters. Chapter 1, introduces a class of scientific targets that formerly have

Spatial photon correlations in multiple scattering media

DEFF Research Database (Denmark)

Smolka, Stephan; Muskens, O.; Lagendijk, A.

2010-01-01

We present the first angle-resolved measurements of spatial photon correlations that are induced by multiple scattering of light. The correlation relates multiple scattered photons at different spatial positions and depends on incident photon fluctuations.......We present the first angle-resolved measurements of spatial photon correlations that are induced by multiple scattering of light. The correlation relates multiple scattered photons at different spatial positions and depends on incident photon fluctuations....

Spatially Resolved Circumnuclear Dust in Centaurus A

OpenAIRE

Karovska, Margarita; Marengo, Massimo; Elvis, Martin; Fazio, Giovanni; Hora, Joseph; Hinz, Philip; Hoffmann, William; Meyer, Michael; Mamajek, Eric

2003-01-01

In this paper we present results from our exploratory mid-IR study of Centaurus A circumnuclear environment using high-angular resolution imaging at the Magellan 6.5m telescope with the MIRAC/BLINC camera. We detected emission from a compact region surrounding the nuclear source, and obtained photometry at 8.8 microns and in the N band. Our analysis suggests that the nuclear region is resolved with a size of approximately 3 pc. The mid-IR emission from this region is likely associated with co...

Pancreatic β-cell regeneration: Facultative or dedicated progenitors?

Science.gov (United States)

Afelik, Solomon; Rovira, Meritxell

2017-04-15

The adult pancreas is only capable of limited regeneration. Unlike highly regenerative tissues such as the skin, intestinal crypts and hematopoietic system, no dedicated adult stem cells or stem cell niche have so far been identified within the adult pancreas. New β cells have been shown to form in the adult pancreas, in response to high physiological demand or experimental β-cell ablation, mostly by replication of existing β cells. The possibility that new β cells are formed from other sources is currently a point of major controversy. Under particular injury conditions, fully differentiated pancreatic duct and acinar cells have been shown to dedifferentiate into a progenitor-like state, however the extent, to which ductal, acinar or other endocrine cells contribute to restoring pancreatic β-cell mass remains to be resolved. In this review we focus on regenerative events in the pancreas with emphasis on the restoration of β-cell mass. We present an overview of regenerative responses noted within the different pancreatic lineages, following injury. We also highlight the intrinsic plasticity of the adult pancreas that allows for inter-conversion of fully differentiated pancreatic lineages through manipulation of few genes or growth factors. Taken together, evidence from a number of studies suggest that differentiated pancreatic lineages could act as facultative progenitor cells, but the extent to which these contribute to β-cell regeneration in vivo is still a matter of contention. Copyright © 2016. Published by Elsevier B.V.

Spatially-resolved EEL studies of plasmons in silver filled carbon nanotubes using a dedicated STEM

International Nuclear Information System (INIS)

Bangert, U; Harvey, A J; Seepujak, A

2008-01-01

Using a dedicated FEG STEM, we present highly spatially-resolved electron energy-loss (EEL) studies of individual multi-walled carbon nanotubes (MWCNTs), each with the inner cavity possessing regions completely filled with silver. The transmission and attenuation of graphite π-collective mode E-fields through the MWCNT walls are established. Noticeable changes in the graphite π-surface mode are witnessed, concomitant with coupling of the silver Mie mode and the graphite π-surface mode. The resulting collective mode is significantly red-shifted to below 5 eV, with considerable intensity in the visible frequency regime. It appears that silver retains its ability to enhance E-fields when surrounded by a MWCNT. Present observations lead to the possibility of collective modes propagating on graphene monolayers being tuned in frequency by the presence of a metal.

Identification of distinct telencephalic progenitor pools for neuronal diversity in the amygdala.

Science.gov (United States)

Hirata, Tsutomu; Li, Peijun; Lanuza, Guillermo M; Cocas, Laura A; Huntsman, Molly M; Corbin, Joshua G

2009-02-01

The development of the amygdala, a central structure of the limbic system, remains poorly understood. We found that two spatially distinct and early-specified telencephalic progenitor pools marked by the homeodomain transcription factor Dbx1 are major sources of neuronal cell diversity in the mature mouse amygdala. We found that Dbx1-positive cells of the ventral pallium generate the excitatory neurons of the basolateral complex and cortical amygdala nuclei. Moreover, Dbx1-derived cells comprise a previously unknown migratory stream that emanates from the preoptic area (POA), a ventral telencephalic domain adjacent to the diencephalic border. The Dbx1-positive, POA-derived population migrated specifically to the amygdala and, as defined by both immunochemical and electrophysiological criteria, generated a unique subclass of inhibitory neurons in the medial amygdala nucleus. Thus, this POA-derived population represents a previously unknown progenitor pool dedicated to the limbic system.

Early Blue Excess from the Type Ia Supernova 2017cbv and Implications for Its Progenitor

Energy Technology Data Exchange (ETDEWEB)

Hosseinzadeh, Griffin; Howell, D. Andrew; McCully, Curtis; Arcavi, Iair [Las Cumbres Observatory, 6740 Cortona Drive, Suite 102, Goleta, CA 93117-5575 (United States); Sand, David J.; Tartaglia, Leonardo [Department of Astronomy/Steward Observatory, 933 North Cherry Avenue, Room N204, Tucson, AZ 85721-0065 (United States); Valenti, Stefano; Bostroem, K. Azalee [Department of Physics, University of California, 1 Shields Avenue, Davis, CA 95616-5270 (United States); Brown, Peter [Mitchell Institute for Fundamental Physics and Astronomy, Texas A and M University, College Station, TX 77843-4242 (United States); Kasen, Daniel [Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720-8169 (United States); Hsiao, Eric Y.; Davis, Scott; Shahbandeh, Melissa [Department of Physics, Florida State University, 77 Chieftain Way, Tallahassee, FL 32306-4350 (United States); Stritzinger, Maximilian D., E-mail: griffin@lco.global [Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, DK-8000 Aarhus C (Denmark)

2017-08-20

We present very early, high-cadence photometric observations of the nearby Type Ia SN 2017cbv. The light curve is unique in that it has a blue bump during the first five days of observations in the U , B , and g bands, which is clearly resolved given our photometric cadence of 5.7 hr during that time span. We model the light curve as the combination of early shocking of the supernova ejecta against a nondegenerate companion star plus a standard SN Ia component. Our best-fit model suggests the presence of a subgiant star 56 R {sub ☉} from the exploding white dwarf, although this number is highly model-dependent. While this model matches the optical light curve well, it overpredicts the observed flux in the ultraviolet bands. This may indicate that the shock is not a blackbody, perhaps because of line blanketing in the UV. Alternatively, it could point to another physical explanation for the optical blue bump, such as interaction with circumstellar material or an unusual nickel distribution. Early optical spectra of SN 2017cbv show strong carbon (C ii λ 6580) absorption up through day −13 with respect to maximum light, suggesting that the progenitor system contains a significant amount of unburned material. These early results on SN 2017cbv illustrate the power of early discovery and intense follow-up of nearby supernovae to resolve standing questions about the progenitor systems and explosion mechanisms of SNe Ia.

Early Blue Excess from the Type Ia Supernova 2017cbv and Implications for Its Progenitor

International Nuclear Information System (INIS)

Hosseinzadeh, Griffin; Howell, D. Andrew; McCully, Curtis; Arcavi, Iair; Sand, David J.; Tartaglia, Leonardo; Valenti, Stefano; Bostroem, K. Azalee; Brown, Peter; Kasen, Daniel; Hsiao, Eric Y.; Davis, Scott; Shahbandeh, Melissa; Stritzinger, Maximilian D.

2017-01-01

We present very early, high-cadence photometric observations of the nearby Type Ia SN 2017cbv. The light curve is unique in that it has a blue bump during the first five days of observations in the U , B , and g bands, which is clearly resolved given our photometric cadence of 5.7 hr during that time span. We model the light curve as the combination of early shocking of the supernova ejecta against a nondegenerate companion star plus a standard SN Ia component. Our best-fit model suggests the presence of a subgiant star 56 R _☉ from the exploding white dwarf, although this number is highly model-dependent. While this model matches the optical light curve well, it overpredicts the observed flux in the ultraviolet bands. This may indicate that the shock is not a blackbody, perhaps because of line blanketing in the UV. Alternatively, it could point to another physical explanation for the optical blue bump, such as interaction with circumstellar material or an unusual nickel distribution. Early optical spectra of SN 2017cbv show strong carbon (C ii λ 6580) absorption up through day −13 with respect to maximum light, suggesting that the progenitor system contains a significant amount of unburned material. These early results on SN 2017cbv illustrate the power of early discovery and intense follow-up of nearby supernovae to resolve standing questions about the progenitor systems and explosion mechanisms of SNe Ia.

Space- and time-resolved raman and breakdown spectroscopy: advanced lidar techniques

Science.gov (United States)

Silviu, Gurlui; Marius Mihai, Cazacu; Adrian, Timofte; Oana, Rusu; Georgiana, Bulai; Dimitriu, Dan

2018-04-01

DARLIOES - the advanced LIDAR is based on space- and time-resolved RAMAN and breakdown spectroscopy, to investigate chemical and toxic compounds, their kinetics and physical properties at high temporal (2 ns) and spatial (1 cm) resolution. The high spatial and temporal resolution are needed to resolve a large variety of chemical troposphere compounds, emissions from aircraft, the self-organization space charges induced light phenomena, temperature and humidity profiles, ice nucleation, etc.

Resolving runaway electron distributions in space, time, and energy

Science.gov (United States)

Paz-Soldan, C.; Cooper, C. M.; Aleynikov, P.; Eidietis, N. W.; Lvovskiy, A.; Pace, D. C.; Brennan, D. P.; Hollmann, E. M.; Liu, C.; Moyer, R. A.; Shiraki, D.

2018-05-01

Areas of agreement and disagreement with present-day models of runaway electron (RE) evolution are revealed by measuring MeV-level bremsstrahlung radiation from runaway electrons (REs) with a pinhole camera. Spatially resolved measurements localize the RE beam, reveal energy-dependent RE transport, and can be used to perform full two-dimensional (energy and pitch-angle) inversions of the RE phase-space distribution. Energy-resolved measurements find qualitative agreement with modeling on the role of collisional and synchrotron damping in modifying the RE distribution shape. Measurements are consistent with predictions of phase-space attractors that accumulate REs, with non-monotonic features observed in the distribution. Temporally resolved measurements find qualitative agreement with modeling on the impact of collisional and synchrotron damping in varying the RE growth and decay rate. Anomalous RE loss is observed and found to be largest at low energy. Possible roles for kinetic instability or spatial transport to resolve these anomalies are discussed.

Spatially Resolved Hard X-ray Emission in the Central 5 kpc of the Galaxy Merger NGC 6240

Science.gov (United States)

Wang, Junfeng; Nardini, E.; Fabbiano, G.; Karovska, M.; Elvis, M.; Pellegrini, S.; Max, C. E.; Risaliti, G.; U, V.; Zezas, A.

2013-04-01

We have obtained a deep, sub-arcsecond resolution X-ray image of the nuclear region of the luminous galaxy merger NGC 6240 with Chandra, which resolves the X-ray emission from the pair of active nuclei and the diffuse hot gas in great detail. We detect extended hard X-ray emission from 70 million K hot gas over a spatial scale of 5 kpc, indicating the presence of fast shocks with velocity of 2200 km/s. For the first time we obtain spatial distribution of this highly ionized gas emitting FeXXV and find that it shows a remarkable correspondence to the large scale morphology of H_2(1-0) S(1) line emission and Hα filaments. Propagation of fast shocks originated in the starburst driven wind into the ambient dense gas can account for this morphological correspondence. Both the energetics and the iron mass in the hot gas are consistent with the expected injection from the supernovae explosion during the starburst that is commensurate with its high star formation rate.

Algorithm of extraction optics properties from the measurement of spatially resolved diffuse reflectance

International Nuclear Information System (INIS)

Cunill Rodriguez, Margarita; Delgado Atencio, Jose Alberto; Castro Ramos, Jorge; Vazquez y Montiel, Sergio

2009-01-01

There are several methods to obtain the optical parameters of biological tissues from the measurement of spatially resolved diffuse reflectance. One of them is well-known as Video Reflectometry in which a camera CCD is used as detection and recording system of the lateral distribution of diffuse reflectance Rd(r) when an infinitely narrow light beam impinges on the tissue. In this paper, we present an algorithm that we have developed for the calibration and application of an experimental set-up of Video Reflectometry destined to extract the optical properties of models of biological tissues with optical properties similar to the human skin. The results of evaluation of the accuracy of the algorithm for optical parameters extraction is shown for a set of proofs reflectance curves with known values of these parameters. In the generation of these curves the simulation of measurement errors was also considered. The results show that it is possible to extract the optical properties with an accuracy error of less than 1% for all the proofs curves. (Author)

The Progenitor Dependence of Core-collapse Supernovae from Three-dimensional Simulations with Progenitor Models of 12–40 M ⊙

Science.gov (United States)

Ott, Christian D.; Roberts, Luke F.; da Silva Schneider, André; Fedrow, Joseph M.; Haas, Roland; Schnetter, Erik

2018-03-01

We present a first study of the progenitor star dependence of the three-dimensional (3D) neutrino mechanism of core-collapse supernovae. We employ full 3D general-relativistic multi-group neutrino radiation-hydrodynamics and simulate the postbounce evolutions of progenitors with zero-age main sequence masses of 12, 15, 20, 27, and 40 M ⊙. All progenitors, with the exception of the 12 M ⊙ star, experience shock runaway by the end of their simulations. In most cases, a strongly asymmetric explosion will result. We find three qualitatively distinct evolutions that suggest a complex dependence of explosion dynamics on progenitor density structure, neutrino heating, and 3D flow. (1) Progenitors with massive cores, shallow density profiles, and high post-core-bounce accretion rates experience very strong neutrino heating and neutrino-driven turbulent convection, leading to early shock runaway. Accretion continues at a high rate, likely leading to black hole formation. (2) Intermediate progenitors experience neutrino-driven, turbulence-aided explosions triggered by the arrival of density discontinuities at the shock. These occur typically at the silicon/silicon–oxygen shell boundary. (3) Progenitors with small cores and density profiles without strong discontinuities experience shock recession and develop the 3D standing-accretion shock instability (SASI). Shock runaway ensues late, once declining accretion rate, SASI, and neutrino-driven convection create favorable conditions. These differences in explosion times and dynamics result in a non-monotonic relationship between progenitor and compact remnant mass.

THE MASSIVE STAR POPULATION IN M101. I. THE IDENTIFICATION AND SPATIAL DISTRIBUTION OF THE VISUALLY LUMINOUS STARS

International Nuclear Information System (INIS)

Grammer, Skyler; Humphreys, Roberta M.

2013-01-01

An increasing number of non-terminal giant eruptions are being observed by modern supernova and transient surveys. But very little is known about the origin of these giant eruptions and their progenitors, many of which are presumably very massive, evolved stars. Motivated by the small number of progenitors positively associated with these giant eruptions, we have begun a survey of the evolved massive star populations in nearby galaxies. The nearby, nearly face-on, giant spiral M101 is an excellent laboratory for studying a large population of very massive stars. In this paper, we present BVI photometry obtained from archival HST/ACS Wide Field Camera images of M101. We have produced a catalog of luminous stars with photometric errors <10% for V < 24.5 and 50% completeness down to V ∼ 26.5 even in regions of high stellar crowding. Using color and luminosity criteria, we have identified candidate luminous OB-type stars and blue supergiants, yellow supergiants, and red supergiants for future observation. We examine their spatial distributions across the face of M101 and find that the ratio of blue to red supergiants decreases by two orders of magnitude over the radial extent of M101 corresponding to 0.5 dex in metallicity. We discuss the resolved stellar content in the giant star-forming complexes NGC 5458, 5453, 5461, 5451, 5462, and 5449 and discuss their color-magnitude diagrams in conjunction with the spatial distribution of the stars to determine their spatio-temporal formation histories

Spatially-resolved star formation histories of CALIFA galaxies. Implications for galaxy formation

Science.gov (United States)

González Delgado, R. M.; Pérez, E.; Cid Fernandes, R.; García-Benito, R.; López Fernández, R.; Vale Asari, N.; Cortijo-Ferrero, C.; de Amorim, A. L.; Lacerda, E. A. D.; Sánchez, S. F.; Lehnert, M. D.; Walcher, C. J.

2017-11-01

This paper presents the spatially resolved star formation history (SFH) of nearby galaxies with the aim of furthering our understanding of the different processes involved in the formation and evolution of galaxies. To this end, we apply the fossil record method of stellar population synthesis to a rich and diverse data set of 436 galaxies observed with integral field spectroscopy in the CALIFA survey. The sample covers a wide range of Hubble types, with stellar masses ranging from M⋆ 109 to 7 × 1011 M⊙. Spectral synthesis techniques are applied to the datacubes to retrieve the spatially resolved time evolution of the star formation rate (SFR), its intensity (ΣSFR), and other descriptors of the 2D SFH in seven bins of galaxy morphology (E, S0, Sa, Sb, Sbc, Sc, and Sd) and five bins of stellar mass. Our main results are that (a) galaxies form very fast independently of their current stellar mass, with the peak of star formation at high redshift (z > 2). Subsequent star formation is driven by M⋆ and morphology, with less massive and later type spirals showing more prolonged periods of star formation. (b) At any epoch in the past, the SFR is proportional to M⋆, with most massive galaxies having the highest absolute (but lowest specific) SFRs. (c) While today, the ΣSFR is similar for all spirals and significantly lower in early-type galaxies (ETG), in the past, the ΣSFR scales well with morphology. The central regions of today's ETGs are where the ΣSFR reached the highest values (> 103 M⊙ Gyr-1 pc-2), similar to those measured in high-redshift star-forming galaxies. (d) The evolution of ΣSFR in Sbc systems matches that of models for Milky Way-like galaxies, suggesting that the formation of a thick disk may be a common phase in spirals at early epochs. (e) The SFR and ΣSFR in outer regions of E and S0 galaxies show that they have undergone an extended phase of growth in mass between z = 2 and 0.4. The mass assembled in this phase is in agreement with

Spatially resolved XRF, XAFS, XRD, STXM and IR investigation of a natural U-rich clay

Science.gov (United States)

Denecke, M. A.; Michel, P.; Schäfer, T.; Huber, F.; Rickers, K.; Rothe, J.; Dardenne, K.; Brendebach, B.; Vitova, T.; Elie, M.

2009-11-01

Combined spatially resolved hard X-ray μ-XRF and μ-XAFS studies using an X-ray beam with micrometer dimensions at the INE-Beamline for actinide research at ANKA and Beamline L at HASYLAB with those from scanning transmission soft X-ray microscopy (STXM) and synchrotron-based Fourier transform infrared microspectroscopy (μ-FTIR) recorded with beam spots in the nanometer range are used to study a U-rich clay originating from Autunian shales in the Permian Lodève Basin (France). This argillaceous formation is a natural U deposit associated with organic matter (bitumen). Results allow us to differentiate between possible mechanisms leading to U enrichment: likely U immobilization via reaction with organic material associated with clay mineral. Such investigations support development of reliable assessment of the long term radiological safety for proposed nuclear waste disposal sites.

THE YELLOW SUPERGIANT PROGENITOR OF THE TYPE II SUPERNOVA 2011dh IN M51

International Nuclear Information System (INIS)

Maund, J. R.; Fraser, M.; Smartt, S. J.; Kotak, R.; Magill, L.; Ergon, M.; Sollerman, J.; Pastorello, A.; Benetti, S.; Botticella, M.-T.; Valenti, S.; Bufano, F.; Danziger, I. J.; Stephens, A. W.

2011-01-01

We present the detection of the putative progenitor of the Type IIb SN 2011dh in archival pre-explosion Hubble Space Telescope images. Using post-explosion Adaptive Optics imaging with Gemini NIRI+ALTAIR, the position of the supernova (SN) in the pre-explosion images was determined to within 23 mas. The progenitor candidate is consistent with an F8 supergiant star (logL/L sun = 4.92 ± 0.20 and T eff = 6000 ± 280 K). Through comparison with stellar evolution tracks, this corresponds to a single star at the end of core C-burning with an initial mass of M ZAMS = 13 ± 3 M sun . The possibility of the progenitor source being a cluster is rejected, on the basis of: (1) the source not being spatially extended, (2) the absence of excess Hα emission, and (3) the poor fit to synthetic cluster spectral energy distributions (SEDs). It is unclear if a binary companion is contributing to the observed SED, although given the excellent correspondence of the observed photometry to a single star SED we suggest that the companion does not contribute significantly. Early photometric and spectroscopic observations show fast evolution similar to the transitional Type IIb SN 2008ax and suggest that a large amount of the progenitor's hydrogen envelope was removed before explosion. Late-time observations will reveal if the yellow supergiant or the putative companion star were responsible for this SN explosion.

Essential Function of Dicer in Resolving DNA Damage in the Rapidly Dividing Cells of the Developing and Malignant Cerebellum

Directory of Open Access Journals (Sweden)

Vijay Swahari

2016-01-01

Full Text Available Maintenance of genomic integrity is critical during neurodevelopment, particularly in rapidly dividing cerebellar granule neuronal precursors that experience constitutive replication-associated DNA damage. As Dicer was recently recognized to have an unexpected function in the DNA damage response, we examined whether Dicer was important for preserving genomic integrity in the developing brain. We report that deletion of Dicer in the developing mouse cerebellum resulted in the accumulation of DNA damage leading to cerebellar progenitor degeneration, which was rescued with p53 deficiency; deletion of DGCR8 also resulted in similar DNA damage and cerebellar degeneration. Dicer deficiency also resulted in DNA damage and death in other rapidly dividing cells including embryonic stem cells and the malignant cerebellar progenitors in a mouse model of medulloblastoma. Together, these results identify an essential function of Dicer in resolving the spontaneous DNA damage that occurs during the rapid proliferation of developmental progenitors and malignant cells.

Spatially resolving the dust properties and submillimetre excess in M 33

Science.gov (United States)

Relaño, M.; De Looze, I.; Kennicutt, R. C.; Lisenfeld, U.; Dariush, A.; Verley, S.; Braine, J.; Tabatabaei, F.; Kramer, C.; Boquien, M.; Xilouris, M.; Gratier, P.

2018-05-01

Context. The relative abundance of the dust grain types in the interstellar medium is directly linked to physical quantities that trace the evolution of galaxies. Because of the poor spatial resolution of the infrared and submillimetre data, we are able to study the dependence of the resolved infrared spectral energy distribution (SED) across regions of the interstellar medium (ISM) with different physical properties in just a few objects. Aims: We aim to study the dust properties of the whole disc of M 33 at spatial scales of 170 pc. This analysis allows us to infer how the relative dust grain abundance changes with the conditions of the ISM, study the existence of a submillimetre excess and look for trends of the gas-to-dust mass ratio (GDR) with other physical properties of the galaxy. Methods: For each pixel in the disc of M 33 we have fitted the infrared SED using a physically motivated dust model that assumes an emissivity index β close to two. We applied a Bayesian statistical method to fit the individual SEDs and derived the best output values from the study of the probability density function of each parameter. We derived the relative amount of the different dust grains in the model, the total dust mass, and the strength of the interstellar radiation field (ISRF) heating the dust at each spatial location. Results: The relative abundance of very small grains tends to increase, and for big grains to decrease, at high values of Hα luminosity. This shows that the dust grains are modified inside the star-forming regions, in agreement with a theoretical framework of dust evolution under different physical conditions. The radial dependence of the GDR is consistent with the shallow metallicity gradient observed in this galaxy. The strength of the ISRF derived in our model correlates with the star formation rate in the galaxy in a pixel by pixel basis. Although this is expected, it is the first time that a correlation between the two quantities has been reported

Impairment of circulating endothelial progenitors in Down syndrome

Directory of Open Access Journals (Sweden)

Costa Valerio

2010-09-01

Full Text Available Abstract Background Pathological angiogenesis represents a critical issue in the progression of many diseases. Down syndrome is postulated to be a systemic anti-angiogenesis disease model, possibly due to increased expression of anti-angiogenic regulators on chromosome 21. The aim of our study was to elucidate some features of circulating endothelial progenitor cells in the context of this syndrome. Methods Circulating endothelial progenitors of Down syndrome affected individuals were isolated, in vitro cultured and analyzed by confocal and transmission electron microscopy. ELISA was performed to measure SDF-1α plasma levels in Down syndrome and euploid individuals. Moreover, qRT-PCR was used to quantify expression levels of CXCL12 gene and of its receptor in progenitor cells. The functional impairment of Down progenitors was evaluated through their susceptibility to hydroperoxide-induced oxidative stress with BODIPY assay and the major vulnerability to the infection with human pathogens. The differential expression of crucial genes in Down progenitor cells was evaluated by microarray analysis. Results We detected a marked decrease of progenitors' number in young Down individuals compared to euploid, cell size increase and some major detrimental morphological changes. Moreover, Down syndrome patients also exhibited decreased SDF-1α plasma levels and their progenitors had a reduced expression of SDF-1α encoding gene and of its membrane receptor. We further demonstrated that their progenitor cells are more susceptible to hydroperoxide-induced oxidative stress and infection with Bartonella henselae. Further, we observed that most of the differentially expressed genes belong to angiogenesis, immune response and inflammation pathways, and that infected progenitors with trisomy 21 have a more pronounced perturbation of immune response genes than infected euploid cells. Conclusions Our data provide evidences for a reduced number and altered

SPATIALLY RESOLVED HCN ABSORPTION FEATURES IN THE CIRCUMNUCLEAR REGION OF NGC 1052

Energy Technology Data Exchange (ETDEWEB)

Sawada-Satoh, Satoko [Mizusawa VLBI Observatory, National Astronomical Observatory of Japan, 2-12 Hoshigaoka-cho, Mizusawa-ku, Oshu, Iwate 023-0861 (Japan); Roh, Duk-Gyoo; Oh, Se-Jin; Lee, Sang-Sung; Byun, Do-Young; Yeom, Jae-Hwan; Jung, Dong-Kyu; Kim, Hyo-Ryoung; Hwang, Ju-Yeon [Korea Astronomy and Space Science Institute, 776 Daedeok-daero, Yuseong, Daejeon 34055 (Korea, Republic of); Kameno, Seiji, E-mail: satoko.ss@nao.ac.jp, E-mail: sss@mx.ibaraki.ac.jp [Joint ALMA Observatory, Alonso de Cordova 3107 Vitacura, Santiago 763 0355 (Chile)

2016-10-10

We present the first VLBI detection of HCN molecular absorption in the nearby active galactic nucleus NGC 1052. Utilizing the 1 mas resolution achieved by the Korean VLBI Network, we have spatially resolved the HCN absorption against a double-sided nuclear jet structure. Two velocity features of HCN absorption are detected significantly at the radial velocity of 1656 and 1719 km s{sup −1}, redshifted by 149 and 212 km s{sup −1} with respect to the systemic velocity of the galaxy. The column density of the HCN molecule is estimated to be 10{sup 15}–10{sup 16} cm{sup −2}, assuming an excitation temperature of 100–230 K. The absorption features show high optical depth localized on the receding jet side, where the free–free absorption occurred due to the circumnuclear torus. The size of the foreground absorbing molecular gas is estimated to be on approximately one-parsec scales, which agrees well with the approximate size of the circumnuclear torus. HCN absorbing gas is likely to be several clumps smaller than 0.1 pc inside the circumnuclear torus. The redshifted velocities of the HCN absorption features imply that HCN absorbing gas traces ongoing infall motion inside the circumnuclear torus onto the central engine.

Cataclysmic Variables as Supernova Ia Progenitors

Directory of Open Access Journals (Sweden)

Stella Kafka

2012-06-01

Full Text Available Although the identification of the progenitors of type Ia supernovae (SNeIa remains controversial, it is generally accepted that they originate from binary star systems in which at least one component is a carbon-oxygen white dwarf (WD; those systems are grouped under the wide umbrella of cataclysmic variables. Current theories for SNeIa progenitors hold that, either via Roche lobe overflow of the companion or via a wind, the WD accumulates hydrogen or helium rich material which is then burned to C and O onto the WD’s surface. However, the specifics of this scenario are far from being understood or defined, allowing for a wealth of theories fighting for attention and a dearth of observations to support them. I discuss the latest attempts to identify and study those controversial SNeIa progenitors. I also introduce the most promising progenitor in hand and I present observational diagnostics that can reveal more members of the category.

Comparison of grain to grain orientation and stiffness mapping by spatially resolved acoustic spectroscopy and EBSD.

Science.gov (United States)

Mark, A F; Li, W; Sharples, S; Withers, P J

2017-07-01

Our aim was to establish the capability of spatially resolved acoustic spectroscopy (SRAS) to map grain orientations and the anisotropy in stiffness at the sub-mm to micron scale by comparing the method with electron backscatter diffraction (EBSD) undertaken within a scanning electron microscope. In the former the grain orientations are deduced by measuring the spatial variation in elastic modulus; conversely, in EBSD the elastic anisotropy is deduced from direct measurements of the crystal orientations. The two test-cases comprise mapping the fusion zones for large TIG and MMA welds in thick power plant austenitic and ferritic steels, respectively; these are technologically important because, among other things, elastic anisotropy can cause ultrasonic weld inspection methods to become inaccurate because it causes bending in the paths of sound waves. The spatial resolution of SRAS is not as good as that for EBSD (∼100 μm vs. ∼a few nm), nor is the angular resolution (∼1.5° vs. ∼0.5°). However the method can be applied to much larger areas (currently on the order of 300 mm square), is much faster (∼5 times), is cheaper and easier to perform, and it could be undertaken on the manufacturing floor. Given these advantages, particularly to industrial users, and the on-going improvements to the method, SRAS has the potential to become a standard method for orientation mapping, particularly in cases where the elastic anisotropy is important over macroscopic/component length scales. © 2017 The Authors Journal of Microscopy © 2017 Royal Microscopical Society.

Exploring the limits to spatially resolved NMR

Energy Technology Data Exchange (ETDEWEB)

Gaedke, Achim; Nestle, Nikolaus [TU Darmstadt, Institute of Condensed Matter Physics (Germany)

2010-07-01

Recent advances in MRI have demonstrated resolutions down to 1 {mu}m. Magnetic resonance force microscopy has the potential to reach sensitivity for single nuclear spins. Given these numbers, in vivo imaging of single cells or even biomacromolecules may seem possible. However, for in vivo applications, there are fundamental differences in the contrast mechanisms compared to MRI at macroscopic scales as the length scale of of molecular self-diffusion exceeds that of the spatial resolution on the NMR time scale. Those effects - which are fundamentally different from the echo attenuation in field gradient NMR - even may lead to general limitations on the spatial resolution achievable in aqueous systems with high water content. In our contribution, we explore those effects on a model system in a high-resolution stray-field imaging setup. In addition to experimental results, simulations based on the Bloch-Torrey equation are presented.

An online, energy-resolving beam profile detector for laser-driven proton beams

Energy Technology Data Exchange (ETDEWEB)

Metzkes, J.; Rehwald, M.; Obst, L.; Schramm, U. [Helmholtz-Zentrum Dresden–Rossendorf (HZDR), Bautzner Landstr. 400, 01328 Dresden (Germany); Technische Universität Dresden, 01062 Dresden (Germany); Zeil, K.; Kraft, S. D.; Sobiella, M.; Schlenvoigt, H.-P. [Helmholtz-Zentrum Dresden–Rossendorf (HZDR), Bautzner Landstr. 400, 01328 Dresden (Germany); Karsch, L. [OncoRay-National Center for Radiation Research in Oncology, Technische Universität Dresden, 01307 Dresden (Germany)

2016-08-15

In this paper, a scintillator-based online beam profile detector for the characterization of laser-driven proton beams is presented. Using a pixelated matrix with varying absorber thicknesses, the proton beam is spatially resolved in two dimensions and simultaneously energy-resolved. A thin plastic scintillator placed behind the absorber and read out by a CCD camera is used as the active detector material. The spatial detector resolution reaches down to ∼4 mm and the detector can resolve proton beam profiles for up to 9 proton threshold energies. With these detector design parameters, the spatial characteristics of the proton distribution and its cut-off energy can be analyzed online and on-shot under vacuum conditions. The paper discusses the detector design, its characterization and calibration at a conventional proton source, as well as the first detector application at a laser-driven proton source.

Voxel-based measurement sensitivity of spatially resolved near-infrared spectroscopy in layered tissues.

Science.gov (United States)

Niwayama, Masatsugu

2018-03-01

We quantitatively investigated the measurement sensitivity of spatially resolved spectroscopy (SRS) across six tissue models: cerebral tissue, a small animal brain, the forehead of a fetus, an adult brain, forearm muscle, and thigh muscle. The optical path length in the voxel of the model was analyzed using Monte Carlo simulations. It was found that the measurement sensitivity can be represented as the product of the change in the absorption coefficient and the difference in optical path length in two states with different source-detector distances. The results clarified the sensitivity ratio between the surface layer and the deep layer at each source-detector distance for each model and identified changes in the deep measurement area when one of the detectors was close to the light source. A comparison was made with the results from continuous-wave spectroscopy. The study also identified measurement challenges that arise when the surface layer is inhomogeneous. Findings on the measurement sensitivity of SRS at each voxel and in each layer can support the correct interpretation of measured values when near-infrared oximetry or functional near-infrared spectroscopy is used to investigate different tissue structures. (2018) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE).

ON THE PROGENITOR AND EARLY EVOLUTION OF THE TYPE II SUPERNOVA 2009kr

International Nuclear Information System (INIS)

Fraser, M.; Takats, K.; Pastorello, A.; Smartt, S. J.; Botticella, M-T.; Valenti, S.; Mattila, S.; Ergon, M.; Sollerman, J.; Arcavi, I.; Gal-Yam, A.; Benetti, S.; Bufano, F.; Crockett, R. M.; Danziger, I. J.; Maund, J. R.; Taubenberger, S.; Turatto, M.

2010-01-01

We identify a source coincident with SN 2009kr in Hubble Space Telescope pre-explosion images. The object appears to be a single point source with an intrinsic color V - I = 1.1 ± 0.25 and M V = -7.6 ± 0.6. If this is a single star, it would be a yellow supergiant of log L/L sun ∼ 5.1 and a mass of 15 +5 -4 M sun . The spatial resolution does not allow us yet to definitively determine if the progenitor object is a single star, a binary system, or a compact cluster. We show that the early light curve is similar to a Type IIL SN, but the prominent Hα P-Cygni profiles and the signature of the end of a recombination phase are reminiscent of a Type IIP. The evolution of the expanding ejecta will play an important role in understanding the progenitor object.

Spatially resolved micro-Raman observation on the phase separation of effloresced sea salt droplets.

Science.gov (United States)

Xiao, Han-Shuang; Dong, Jin-Ling; Wang, Liang-Yu; Zhao, Li-Jun; Wang, Feng; Zhang, Yun-Hong

2008-12-01

We report on the investigation of the phase separation of individual seawater droplets in the efflorescence processes with the spatially resolved Raman system. Upon decreasing the relative humidity (RH), CaSO4.0.5H2O separated out foremost fromthe droplet atan unexpectedly high RH of approcimately 90%. Occasionally, CaSO4.2H2O substituted for CaSO4.O.5H2O crystallizing first at approximately 78% RH. Relatively large NaCI solids followed to crystallize at approximately 55% RH and led to the great loss of the solution. Then, the KMgCl3.6H2O crystallites separated out from the residual solutions, adjacentto NaCl at approximately 44% RH. Moreover, a shell structure of dried sea salt particle was found to form at low RHs, with the NaCl crystals in the core and minor supersaturated solutions covered with MgSO4 gel coating on the surface. Ultimately, the shielded solution partly effloresced into MgSO4 hydrates at very dry state (<5% RH).

Dose calculation for permanent prostate implants incorporating spatially anisotropic linearly time-resolving edema

International Nuclear Information System (INIS)

Monajemi, T. T.; Clements, Charles M.; Sloboda, Ron S.

2011-01-01

Purpose: The objectives of this study were (i) to develop a dose calculation method for permanent prostate implants that incorporates a clinically motivated model for edema and (ii) to illustrate the use of the method by calculating the preimplant dosimetry error for a reference configuration of 125 I, 103 Pd, and 137 Cs seeds subject to edema-induced motions corresponding to a variety of model parameters. Methods: A model for spatially anisotropic edema that resolves linearly with time was developed based on serial magnetic resonance imaging measurements made previously at our center to characterize the edema for a group of n=40 prostate implant patients [R. S. Sloboda et al., ''Time course of prostatic edema post permanent seed implant determined by magnetic resonance imaging,'' Brachytherapy 9, 354-361 (2010)]. Model parameters consisted of edema magnitude, Δ, and period, T. The TG-43 dose calculation formalism for a point source was extended to incorporate the edema model, thus enabling calculation via numerical integration of the cumulative dose around an individual seed in the presence of edema. Using an even power piecewise-continuous polynomial representation for the radial dose function, the cumulative dose was also expressed in closed analytical form. Application of the method was illustrated by calculating the preimplant dosimetry error, RE preplan , in a 5x5x5 cm 3 volume for 125 I (Oncura 6711), 103 Pd (Theragenics 200), and 131 Cs (IsoRay CS-1) seeds arranged in the Radiological Physics Center test case 2 configuration for a range of edema relative magnitudes (Δ=[0.1,0.2,0.4,0.6,1.0]) and periods (T=[28,56,84] d). Results were compared to preimplant dosimetry errors calculated using a variation of the isotropic edema model developed by Chen et al. [''Dosimetric effects of edema in permanent prostate seed implants: A rigorous solution,'' Int. J. Radiat. Oncol., Biol., Phys. 47, 1405-1419 (2000)]. Results: As expected, RE preplan for our edema model

Antiferromagnetism Induced in the Vortex Core of Tl2Ba2CuO6++δ Probed by Spatially-Resolved 205Tl-NMR

International Nuclear Information System (INIS)

Kumagai, K.; Kakuyanagi, K.; Matsuda, Y.; Hasegawa, T.

2003-01-01

Magnetism in the vortex core state has been studied by spatially-resolved NMR. The nuclear spin lattice relaxation rate T 1 -1 of 205 Tl in nearly optimal-doped Tl 2 Ba 2 CuO 6+ δ (T c =85 K) is significantly enhanced in the vortex core region. The NMR results suggest that the suppression of the d-wave superconducting order parameter in the vortex core leads to the nucleation of islands with local antiferromagnetic (AF) order. (author)

Spatially resolved analyses of uranium species using a coupled system made up of confocal laser-scanning microscopy (CLSM) and laser induced fluorescence spectroscopy (LIFS)

International Nuclear Information System (INIS)

Brockmann, S.; Grossmann, K.; Arnold, T.

2014-01-01

The fluorescent properties of uranium when excited by UV light are used increasingly for spectroscope analyses of uranium species within watery samples. Here, alongside the fluorescent properties of the hexavalent oxidation phases, the tetra and pentavalent oxidation phases also play an increasingly important role. The detection of fluorescent emission spectrums on solid and biological samples using (time-resolved) laser induced fluorescence spectroscopy (TRLFS or LIFS respectively) has, however, the disadvantage that no statements regarding the spatial localisation of the uranium can be made. However, particularly in complex, biological samples, such statements on the localisation of the uranium enrichment in the sample are desired, in order to e.g. be able to distinguish between intra and extra-cellular uranium bonds. The fluorescent properties of uranium (VI) compounds and minerals can also be used to detect their localisation within complex samples. So the application of fluorescent microscopic methods represents one possibility to localise and visualise uranium precipitates and enrichments in biological samples, such as biofilms or cells. The confocal laser-scanning microscopy (CLSM) is especially well suited to this purpose. Coupling confocal laser-scanning microscopy (CLSM) with laser induced fluorescence spectroscopy (LIFS) makes it possible to localise and visualise fluorescent signals spatially and three-dimensionally, while at the same time being able to detect spatially resolved, fluorescent-spectroscopic data. This technology is characterised by relatively low detection limits from up to 1.10 -6 M for uranium (VI) compounds within the confocal volume. (orig.)

Decomposition of time-resolved tomographic PIV

NARCIS (Netherlands)

Schmid, P.J.; Violato, D.; Scarano, F.

2012-01-01

An experimental study has been conducted on a transitional water jet at a Reynolds number of Re = 5,000. Flow fields have been obtained by means of time-resolved tomographic particle image velocimetry capturing all relevant spatial and temporal scales. The measured threedimensional flow fields have

DARK MATTER SUBSTRUCTURE DETECTION USING SPATIALLY RESOLVED SPECTROSCOPY OF LENSED DUSTY GALAXIES

International Nuclear Information System (INIS)

Hezaveh, Yashar; Holder, Gilbert; Dalal, Neal; Kuhlen, Michael; Marrone, Daniel; Murray, Norman; Vieira, Joaquin

2013-01-01

We investigate how strong lensing of dusty, star-forming galaxies (DSFGs) by foreground galaxies can be used as a probe of dark matter halo substructure. We find that spatially resolved spectroscopy of lensed sources allows dramatic improvements to measurements of lens parameters. In particular, we find that modeling of the full, three-dimensional (angular position and radial velocity) data can significantly facilitate substructure detection, increasing the sensitivity of observables to lower mass subhalos. We carry out simulations of lensed dusty sources observed by early ALMA (Cycle 1) and use a Fisher matrix analysis to study the parameter degeneracies and mass detection limits of this method. We find that even with conservative assumptions, it is possible to detect galactic dark matter subhalos of ∼10 8 M ☉ with high significance in most lensed DSFGs. Specifically, we find that in typical DSFG lenses, there is a ∼55% probability of detecting a substructure with M > 10 8 M ☉ with more than 5σ detection significance in each lens, if the abundance of substructure is consistent with previous lensing results. The full ALMA array, with its significantly enhanced sensitivity and resolution, should improve these estimates considerably. Given the sample of ∼100 lenses provided by surveys such as the South Pole Telescope, our understanding of dark matter substructure in typical galaxy halos is poised to improve dramatically over the next few years.

Towards real-time non contact spatial resolved oxygenation monitoring using a multi spectral filter array camera in various light conditions

Science.gov (United States)

Bauer, Jacob R.; van Beekum, Karlijn; Klaessens, John; Noordmans, Herke Jan; Boer, Christa; Hardeberg, Jon Y.; Verdaasdonk, Rudolf M.

2018-02-01

Non contact spatial resolved oxygenation measurements remain an open challenge in the biomedical field and non contact patient monitoring. Although point measurements are the clinical standard till this day, regional differences in the oxygenation will improve the quality and safety of care. Recent developments in spectral imaging resulted in spectral filter array cameras (SFA). These provide the means to acquire spatial spectral videos in real-time and allow a spatial approach to spectroscopy. In this study, the performance of a 25 channel near infrared SFA camera was studied to obtain spatial oxygenation maps of hands during an occlusion of the left upper arm in 7 healthy volunteers. For comparison a clinical oxygenation monitoring system, INVOS, was used as a reference. In case of the NIRS SFA camera, oxygenation curves were derived from 2-3 wavelength bands with a custom made fast analysis software using a basic algorithm. Dynamic oxygenation changes were determined with the NIR SFA camera and INVOS system at different regional locations of the occluded versus non-occluded hands and showed to be in good agreement. To increase the signal to noise ratio, algorithm and image acquisition were optimised. The measurement were robust to different illumination conditions with NIR light sources. This study shows that imaging of relative oxygenation changes over larger body areas is potentially possible in real time.

PROGENITOR-EXPLOSION CONNECTION AND REMNANT BIRTH MASSES FOR NEUTRINO-DRIVEN SUPERNOVAE OF IRON-CORE PROGENITORS

Energy Technology Data Exchange (ETDEWEB)

Ugliano, Marcella; Janka, Hans-Thomas; Marek, Andreas [Max-Planck-Institut fuer Astrophysik, Karl-Schwarzschild-Str. 1, D-85748 Garching (Germany); Arcones, Almudena [Institut fuer Kernphysik, Technische Universitaet Darmstadt, Schlossgartenstr. 2, D-64289 Darmstadt (Germany)

2012-09-20

We perform hydrodynamic supernova (SN) simulations in spherical symmetry for over 100 single stars of solar metallicity to explore the progenitor-explosion and progenitor-remnant connections established by the neutrino-driven mechanism. We use an approximative treatment of neutrino transport and replace the high-density interior of the neutron star (NS) by an inner boundary condition based on an analytic proto-NS core-cooling model, whose free parameters are chosen such that explosion energy, nickel production, and energy release by the compact remnant of progenitors around 20 M{sub Sun} are compatible with SN 1987A. Thus, we are able to simulate the accretion phase, initiation of the explosion, subsequent neutrino-driven wind phase for 15-20 s, and the further evolution of the blast wave for hours to days until fallback is completed. Our results challenge long-standing paradigms. We find that remnant mass, launch time, and properties of the explosion depend strongly on the stellar structure and exhibit large variability even in narrow intervals of the progenitors' zero-age main-sequence mass. While all progenitors with masses below {approx}15 M{sub Sun} yield NSs, black hole (BH) as well as NS formation is possible for more massive stars, where partial loss of the hydrogen envelope leads to weak reverse shocks and weak fallback. Our NS baryonic masses of {approx}1.2-2.0 M{sub Sun} and BH masses >6 M{sub Sun} are compatible with a possible lack of low-mass BHs in the empirical distribution. Neutrino heating accounts for SN energies between some 10{sup 50} erg and {approx}2 Multiplication-Sign 10{sup 51} erg but can hardly explain more energetic explosions and nickel masses higher than 0.1-0.2 M{sub Sun }. These seem to require an alternative SN mechanism.

Heterogeneity of limbal basal epithelial progenitor cells.

Science.gov (United States)

Hayashida, Yasutaka; Li, Wei; Chen, Ying-Ting; He, Hua; Chen, Szu-yu; Kheirkah, Ahmad; Zhu, Ying-Tien; Matsumoto, Yukihiro; Tseng, Scheffer C G

2010-11-01

Although corneal epithelial stem cells (SCs) are located at the limbus between the cornea and the conjunctiva, not all limbal basal epithelial cells are SCs. Using 2 dispase digestions to remove different amounts of limbal basal epithelial cells for cross-sections, flat mounts, and cytospin preparations, double immunostaining to pancytokeratins (PCK) and vimentin (Vim) identified 3 p63+ epithelial progenitors such as PCK-/Vim+, PCK/Vim, and PCK-/Vim+ and 1 p63+ mesenchymal cell, PCK-/Vim+. PCK-/Vim- progenitors had the smallest cell size were 10-20 times more enriched on collagen I-coated dishes in the 5-minute rapid adherent fraction that contained the highest percentage of p63+ cells but the lowest percentage of cytokeratin12+ cells, and gave rise to high Ki67 labeling and vivid clonal growth. In contrast, PCK+/Vim+ and PCK+/Vim- progenitors were found more in the slow-adherent fraction and yielded poor clonal growth. PCK/Vim progenitors and clusters of PCK-/Vim+ mesenchymal cells, which were neither melanocytes nor Langerhans cells, were located in the limbal basal region. Therefore, differential expression of PCK and Vim helps identify small PCK-/Vim- cells as the most likely candidate for SCs among a hierarchy of heterogeneous limbal basal progenitors, and their close association with PCK-/Vim+ presumed "niche" cells.

Biology and flow cytometry of proangiogenic hematopoietic progenitors cells.

Science.gov (United States)

Rose, Jonathan A; Erzurum, Serpil; Asosingh, Kewal

2015-01-01

During development, hematopoiesis and neovascularization are closely linked to each other via a common bipotent stem cell called the hemangioblast that gives rise to both hematopoietic cells and endothelial cells. In postnatal life, this functional connection between the vasculature and hematopoiesis is maintained by a subset of hematopoietic progenitor cells endowed with the capacity to differentiate into potent proangiogenic cells. These proangiogenic hematopoietic progenitors comprise a specific subset of bone marrow (BM)-derived cells that homes to sites of neovascularization and possess potent paracrine angiogenic activity. There is emerging evidence that this subpopulation of hematopoietic progenitors plays a critical role in vascular health and disease. Their angiogenic activity is distinct from putative "endothelial progenitor cells" that become structural cells of the endothelium by differentiation into endothelial cells. Proangiogenic hematopoietic progenitor cell research requires multidisciplinary expertise in flow cytometry, hematology, and vascular biology. This review provides a comprehensive overview of proangiogenic hematopoietic progenitor cell biology and flow cytometric methods to detect these cells in the peripheral blood circulation and BM. © 2014 International Society for Advancement of Cytometry.

Single cell cultures of Drosophila neuroectodermal and mesectodermal central nervous system progenitors reveal different degrees of developmental autonomy.

Science.gov (United States)

Lüer, Karin; Technau, Gerhard M

2009-08-03

The Drosophila embryonic central nervous system (CNS) develops from two sets of progenitor cells, neuroblasts and ventral midline progenitors, which behave differently in many respects. Neuroblasts derive from the neurogenic region of the ectoderm and form the lateral parts of the CNS. Ventral midline precursors are formed by two rows of mesectodermal cells and build the CNS midline. There is plenty of evidence that individual identities are conferred to precursor cells by positional information in the ectoderm. It is unclear, however, how far the precursors can maintain their identities and developmental properties in the absence of normal external signals. To separate the respective contributions of autonomous properties versus extrinsic signals during their further development, we isolated individual midline precursors and neuroectodermal precursors at the pre-mitotic gastrula stage, traced their development in vitro, and analyzed the characteristics of their lineages in comparison with those described for the embryo. Although individually cultured mesectodermal cells exhibit basic characteristics of CNS midline progenitors, the clones produced by these progenitors differ from their in situ counterparts with regard to cell numbers, expression of molecular markers, and the separation of neuronal and glial fate. In contrast, clones derived from individually cultured precursors taken from specific dorsoventral zones of the neuroectoderm develop striking similarities to the lineages of neuroblasts that normally delaminate from these zones and develop in situ. This in vitro analysis allows for the first time a comparison of the developmental capacities in situ and in vitro of individual neural precursors of defined spatial and temporal origin. The data reveal that cells isolated at the pre-mitotic and pre-delamination stage express characteristics of the progenitor type appropriate to their site of origin in the embryo. However, presumptive neuroblasts, once

Reporter-Based Isolation of Developmental Myogenic Progenitors

Directory of Open Access Journals (Sweden)

Eyemen Kheir

2018-04-01

Full Text Available The formation and activity of mammalian tissues entail finely regulated processes, involving the concerted organization and interaction of multiple cell types. In recent years the prospective isolation of distinct progenitor and stem cell populations has become a powerful tool in the hands of developmental biologists and has rendered the investigation of their intrinsic properties possible. In this protocol, we describe how to purify progenitors with different lineage history and degree of differentiation from embryonic and fetal skeletal muscle by fluorescence-activated cell sorting (FACS. The approach takes advantage of a panel of murine strains expressing fluorescent reporter genes specifically in the myogenic progenitors. We provide a detailed description of the dissection procedures and of the enzymatic dissociation required to maximize the yield of mononucleated cells for subsequent FACS-based purification. The procedure takes ~6–7 h to complete and allows for the isolation and the subsequent molecular and phenotypic characterization of developmental myogenic progenitors.

SUPERNOVA REMNANT PROGENITOR MASSES IN M31

Energy Technology Data Exchange (ETDEWEB)

Jennings, Zachary G.; Williams, Benjamin F.; Dalcanton, Julianne J.; Gilbert, Karoline M.; Fouesneau, Morgan; Weisz, Daniel R. [Department of Astronomy, University of Washington Seattle, Box 351580, WA 98195 (United States); Murphy, Jeremiah W. [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States); Dolphin, Andrew E., E-mail: zachjenn@uw.edu, E-mail: adolphin@raytheon.com [Raytheon, 1151 East Hermans Road, Tucson, AZ 85706 (United States)

2012-12-10

Using Hubble Space Telescope photometry, we age-date 59 supernova remnants (SNRs) in the spiral galaxy M31 and use these ages to estimate zero-age main-sequence masses (M{sub ZAMS}) for their progenitors. To accomplish this, we create color-magnitude diagrams (CMDs) and employ CMD fitting to measure the recent star formation history of the regions surrounding cataloged SNR sites. We identify any young coeval population that likely produced the progenitor star, then assign an age and uncertainty to that population. Application of stellar evolution models allows us to infer the M{sub ZAMS} from this age. Because our technique is not contingent on identification or precise location of the progenitor star, it can be applied to the location of any known SNRs. We identify significant young star formation around 53 of the 59 SNRs and assign progenitor masses to these, representing a factor of {approx}2 increase over currently measured progenitor masses. We consider the remaining six SNRs as either probable Type Ia candidates or the result of core-collapse progenitors that have escaped their birth sites. In general, the distribution of recovered progenitor masses is bottom-heavy, showing a paucity of the most massive stars. If we assume a single power-law distribution, dN/dM{proportional_to}M{sup {alpha}}, then we find a distribution that is steeper than a Salpeter initial mass function (IMF) ({alpha} = -2.35). In particular, we find values of {alpha} outside the range -2.7 {>=} {alpha} {>=} -4.4 to be inconsistent with our measured distribution at 95% confidence. If instead we assume a distribution that follows a Salpeter IMF up to some maximum mass, then we find that values of M{sub Max} > 26 are inconsistent with the measured distribution at 95% confidence. In either scenario, the data suggest that some fraction of massive stars may not explode. The result is preliminary and requires more SNRs and further analysis. In addition, we use our distribution to estimate a

Complex EUV imaging reflectometry: spatially resolved 3D composition determination and dopant profiling with a tabletop 13nm source

Science.gov (United States)

Porter, Christina L.; Tanksalvala, Michael; Gerrity, Michael; Miley, Galen P.; Esashi, Yuka; Horiguchi, Naoto; Zhang, Xiaoshi; Bevis, Charles S.; Karl, Robert; Johnsen, Peter; Adams, Daniel E.; Kapteyn, Henry C.; Murnane, Margaret M.

2018-03-01

With increasingly 3D devices becoming the norm, there is a growing need in the semiconductor industry and in materials science for high spatial resolution, non-destructive metrology techniques capable of determining depth-dependent composition information on devices. We present a solution to this problem using ptychographic coherent diffractive imaging (CDI) implemented using a commercially available, tabletop 13 nm source. We present the design, simulations, and preliminary results from our new complex EUV imaging reflectometer, which uses coherent 13 nm light produced by tabletop high harmonic generation. This tool is capable of determining spatially-resolved composition vs. depth profiles for samples by recording ptychographic images at multiple incidence angles. By harnessing phase measurements, we can locally and nondestructively determine quantities such as device and thin film layer thicknesses, surface roughness, interface quality, and dopant concentration profiles. Using this advanced imaging reflectometer, we can quantitatively characterize materials-sciencerelevant and industry-relevant nanostructures for a wide variety of applications, spanning from defect and overlay metrology to the development and optimization of nano-enhanced thermoelectric or spintronic devices.

Meso-scale defect evaluation of selective laser melting using spatially resolved acoustic spectroscopy.

Science.gov (United States)

Hirsch, M; Catchpole-Smith, S; Patel, R; Marrow, P; Li, Wenqi; Tuck, C; Sharples, S D; Clare, A T

2017-09-01

Developments in additive manufacturing technology are serving to expand the potential applications. Critical developments are required in the supporting areas of measurement and in process inspection to achieve this. CM247LC is a nickel superalloy that is of interest for use in aerospace and civil power plants. However, it is difficult to process via selective laser melting (SLM) as it suffers from cracking during rapid cooling and solidification. This limits the viability of CM247LC parts created using SLM. To quantify part integrity, spatially resolved acoustic spectroscopy (SRAS) has been identified as a viable non-destructive evaluation technique. In this study, a combination of optical microscopy and SRAS was used to identify and classify the surface defects present in SLM-produced parts. By analysing the datasets and scan trajectories, it is possible to correlate morphological information with process parameters. Image processing was used to quantify porosity and cracking for bulk density measurement. Analysis of surface acoustic wave data showed that an error in manufacture in the form of an overscan occurred. Comparing areas affected by overscan with a bulk material, a change in defect density from 1.17% in the bulk material to 5.32% in the overscan regions was observed, highlighting the need to reduce overscan areas in manufacture.

Meso-scale defect evaluation of selective laser melting using spatially resolved acoustic spectroscopy

Science.gov (United States)

Hirsch, M.; Catchpole-Smith, S.; Patel, R.; Marrow, P.; Li, Wenqi; Tuck, C.; Sharples, S. D.; Clare, A. T.

2017-09-01

Developments in additive manufacturing technology are serving to expand the potential applications. Critical developments are required in the supporting areas of measurement and in process inspection to achieve this. CM247LC is a nickel superalloy that is of interest for use in aerospace and civil power plants. However, it is difficult to process via selective laser melting (SLM) as it suffers from cracking during rapid cooling and solidification. This limits the viability of CM247LC parts created using SLM. To quantify part integrity, spatially resolved acoustic spectroscopy (SRAS) has been identified as a viable non-destructive evaluation technique. In this study, a combination of optical microscopy and SRAS was used to identify and classify the surface defects present in SLM-produced parts. By analysing the datasets and scan trajectories, it is possible to correlate morphological information with process parameters. Image processing was used to quantify porosity and cracking for bulk density measurement. Analysis of surface acoustic wave data showed that an error in manufacture in the form of an overscan occurred. Comparing areas affected by overscan with a bulk material, a change in defect density from 1.17% in the bulk material to 5.32% in the overscan regions was observed, highlighting the need to reduce overscan areas in manufacture.

Omega 3 fatty acids reduce myeloid progenitor cell frequency in the bone marrow of mice and promote progenitor cell differentiation

Directory of Open Access Journals (Sweden)

Sollars Vincent E

2009-03-01

Full Text Available Abstract Background Omega 3 fatty acids have been found to inhibit proliferation, induce apoptosis, and promote differentiation in various cell types. The processes of cell survival, expansion, and differentiation are of key importance in the regulation of hematopoiesis. We investigated the role of omega 3 fatty acids in controlling the frequency of various myeloid progenitor cells in the bone marrow of mice. Increased progenitor cell frequency and blocked differentiation are characteristics of hematopoietic disorders of the myeloid lineage, such as myeloproliferative diseases and myeloid leukemias. Results We found that increasing the proportion of omega 3 fatty acids relative to the proportion of omega 6 fatty acids in the diet caused increased differentiation and reduced the frequency of myeloid progenitor cells in the bone marrow of mice. Furthermore, this had no adverse effect on peripheral white blood cell counts. Conclusion Our results indicate that omega 3 fatty acids impact hematopoietic differentiation by reducing myeloid progenitor cell frequency in the bone marrow and promoting progenitor cell differentiation. Further exploration of this discovery could lead to the use of omega 3 fatty acids as a therapeutic option for patients that have various disorders of hematopoiesis.

Progenitor's Signatures in Type Ia Supernova Remnants

NARCIS (Netherlands)

Chiotellis, A.; Kosenko, D.; Schure, K.M.; Vink, J.

2013-01-01

The remnants of Type Ia supernovae (SNe Ia) can provide important clues about their progenitor histories. We discuss two well-observed supernova remnants (SNRs) that are believed to have resulted from SNe Ia, and use various tools to shed light on the possible progenitor histories. We find that

Spatially resolved vertical vorticity in solar supergranulation using helioseismology and local correlation tracking

Science.gov (United States)

Langfellner, J.; Gizon, L.; Birch, A. C.

2015-09-01

Flow vorticity is a fundamental property of turbulent convection in rotating systems. Solar supergranules exhibit a preferred sense of rotation, which depends on the hemisphere. This is due to the Coriolis force acting on the diverging horizontal flows. We aim to spatially resolve the vertical flow vorticity of the average supergranule at different latitudes, both for outflow and inflow regions. To measure the vertical vorticity, we use two independent techniques: time-distance helioseismology (TD) and local correlation tracking of granules in intensity images (LCT) using data from the Helioseismic and Magnetic Imager (HMI) on board the Solar Dynamics Observatory (SDO). Both maps are corrected for center-to-limb systematic errors. We find that 8 h TD and LCT maps of vertical vorticity are highly correlated at large spatial scales. Associated with the average supergranule outflow, we find tangential (vortical) flows that reach about 10 m s-1 in the clockwise direction at 40° latitude. In average inflow regions, the tangential flow reaches the same magnitude, but in the anticlockwise direction. These tangential velocities are much smaller than the radial (diverging) flow component (300 m s-1 for the average outflow and 200 m s-1 for the average inflow). The results for TD and LCT as measured from HMI are in excellent agreement for latitudes between -60° and 60°. From HMI LCT, we measure the vorticity peak of the average supergranule to have a full width at half maximum of about 13 Mm for outflows and 8 Mm for inflows. This is larger than the spatial resolution of the LCT measurements (about 3 Mm). On the other hand, the vorticity peak in outflows is about half the value measured at inflows (e.g., 4 × 10-6 s-1 clockwise compared to 8 × 10-6 s-1 anticlockwise at 40° latitude). Results from the Michelson Doppler Imager (MDI) on board the Solar and Heliospheric Observatory (SOHO) obtained in 2010 are biased compared to the HMI/SDO results for the same period

Atomic column resolved electron energy-loss spectroscopy

International Nuclear Information System (INIS)

Duscher, G.; Pennycook, S.J.; Browning, N.D.

1998-01-01

Spatially resolved electron energy-loss spectroscopy (EELS) is rapidly developing into a unique and powerful tool to characterize internal interfaces. Because atomic column resolved Z-contrast imaging can be performed simultaneously with EELS in the scanning transmission electron microscope, this combination allows the atomic structure to be correlated with the electronic structure, and thus the local properties of interfaces or defects can be determined directly. However, the ability to characterize interfaces and defects at that level requires not only high spatial resolution but also the exact knowledge of the beam location, from where the spectrum is obtained. Here we discuss several examples progressing from cases where the limitation in spatial resolution is given by the microscopes or the nature of the sample, to one example of impurity atoms at a grain boundary, which show intensity and fine structure changes from atomic column to atomic column. Such data can be interpreted as changes in valence of the impurity, depending on its exact site in the boundary plane. Analysis ofthis nature is a valuable first step in understanding the microscopic structural, optical and electronic properties of materials. (orig.)

Towards a global system of vigilance and surveillance in unrelated donors of haematopoietic progenitor cells for transplantation.

Science.gov (United States)

Shaw, B E; Chapman, J; Fechter, M; Foeken, L; Greinix, H; Hwang, W; Phillips-Johnson, L; Korhonen, M; Lindberg, B; Navarro, W H; Szer, J

2013-11-01

Safety of living donors is critical to the success of blood, tissue and organ transplantation. Structured and robust vigilance and surveillance systems exist as part of some national entities, but historically no global systems are in place to ensure conformity, harmonisation and the recognition of rare adverse events (AEs). The World Health Assembly has recently resolved to require AE/reaction (AE/R) reporting both nationally and globally. The World Marrow Donor Association (WMDA) is an international organisation promoting the safety of unrelated donors and progenitor cell products for use in haematopoietic progenitor cell (HPC) transplantation. To address this issue, we established a system for collecting, collating, analysing, distributing and reacting to serious adverse events and reactions (SAE/R) in unrelated HPC donors. The WMDA successfully instituted this reporting system with 203 SAE/R reported in 2011. The committee generated two rapid reports, reacting to specific SAE/R, resulting in practice changing policies. The system has a robust governance structure, formal feedback to the WMDA membership and transparent information flows to other agencies, specialist physicians and transplant programs and the general public.

Progress of stem/progenitor cell-based therapy for retinal degeneration.

Science.gov (United States)

Tang, Zhimin; Zhang, Yi; Wang, Yuyao; Zhang, Dandan; Shen, Bingqiao; Luo, Min; Gu, Ping

2017-05-10

Retinal degeneration (RD), such as age-related macular degeneration (AMD) and retinitis pigmentosa, is one of the leading causes of blindness. Presently, no satisfactory therapeutic options are available for these diseases principally because the retina and retinal pigmented epithelium (RPE) do not regenerate, although wet AMD can be prevented from further progression by anti-vascular endothelial growth factor therapy. Nevertheless, stem/progenitor cell approaches exhibit enormous potential for RD treatment using strategies mainly aimed at the rescue and replacement of photoreceptors and RPE. The sources of stem/progenitor cells are classified into two broad categories in this review, which are (1) ocular-derived progenitor cells, such as retinal progenitor cells, and (2) non-ocular-derived stem cells, including embryonic stem cells, induced pluripotent stem cells, and mesenchymal stromal cells. Here, we discuss in detail the progress in the study of four predominant stem/progenitor cell types used in animal models of RD. A short overview of clinical trials involving the stem/progenitor cells is also presented. Currently, stem/progenitor cell therapies for RD still have some drawbacks such as inhibited proliferation and/or differentiation in vitro (with the exception of the RPE) and limited long-term survival and function of grafts in vivo. Despite these challenges, stem/progenitor cells represent the most promising strategy for RD treatment in the near future.

Selective uptake of boronophenylalanine by glioma stem/progenitor cells

International Nuclear Information System (INIS)

Sun, Ting; Zhou, Youxin; Xie, Xueshun; Chen, Guilin; Li, Bin; Wei, Yongxin; Chen, Jinming; Huang, Qiang; Du, Ziwei

2012-01-01

The success of boron neutron capture therapy (BNCT) depends on the amount of boron in cells and the tumor/blood and tumor/(normal tissue) boron concentration ratios. For the first time, measurements of boron uptake in both stem/progenitor and differentiated glioma cells were performed along with measurements of boron biodistribution in suitable animal models. In glioma stem/progenitor cells, the selective accumulation of boronophenylalanine (BPA) was lower, and retention of boron after BPA removal was longer than in differentiated glioma cells in vitro. However, boron biodistribution was not statistically significantly different in mice with xenografts. - Highlights: ► Uptake of BPA was analyzed in stem/progenitor and differentiated glioma cells. ► Selective accumulation of BPA was lower in glioma stem/progenitor cells. ► Retention of boron after BPA removal was longer in glioma stem/progenitor cells. ► Boron biodistribution was not statistically different in mice with xenografts.

INTEGRAL FIELD SPECTROSCOPY OF SUPERNOVA EXPLOSION SITES: CONSTRAINING THE MASS AND METALLICITY OF THE PROGENITORS. I. TYPE Ib AND Ic SUPERNOVAE

Energy Technology Data Exchange (ETDEWEB)

Kuncarayakti, Hanindyo; Maeda, Keiichi [Kavli Institute for the Physics and Mathematics of the Universe (WPI), Todai Institutes for Advanced Study, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8583 (Japan); Doi, Mamoru; Morokuma, Tomoki; Hashiba, Yasuhito [Institute of Astronomy, Graduate School of Science, The University of Tokyo, 2-21-1 Osawa, Mitaka, Tokyo 181-0015 (Japan); Aldering, Greg [Physics Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720 (United States); Arimoto, Nobuo [National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-0015 (Japan); Pereira, Rui [CNRS/IN2P3, Institut de Physique Nucleaire de Lyon, 4 Rue Enrico Fermi, F-69622 Villeurbanne Cedex (France); Usuda, Tomonori, E-mail: hanindyo.kuncarayakti@ipmu.jp [Subaru Telescope, National Astronomical Observatory of Japan, 650 North A' ohoku Place, Hilo, HI 96720 (United States)

2013-08-01

Integral field spectroscopy of 11 Type Ib/Ic supernova (SN Ib/Ic) explosion sites in nearby galaxies has been obtained using UH88/SNIFS and Gemini-N/GMOS. The use of integral field spectroscopy enables us to obtain both spatial and spectral information about the explosion site, enabling the identification of the parent stellar population of the SN progenitor star. The spectrum of the parent population provides metallicity determination via strong-line method and age estimation obtained via comparison with simple stellar population models. We adopt this information as the metallicity and age of the SN progenitor, under the assumption that it was coeval with the parent stellar population. The age of the star corresponds to its lifetime, which in turn gives the estimate of its initial mass. With this method we were able to determine both the metallicity and initial (zero-age main sequence) mass of the progenitor stars of SNe Ib and Ic. We found that on average SN Ic explosion sites are more metal-rich and younger than SN Ib sites. The initial mass of the progenitors derived from parent stellar population age suggests that SN Ic has more massive progenitors than SN Ib. In addition, we also found indication that some of our SN progenitors are less massive than {approx}25 M{sub Sun }, indicating that they may have been stars in a close binary system that have lost their outer envelope via binary interactions to produce SNe Ib/Ic, instead of single Wolf-Rayet stars. These findings support the current suggestions that both binary and single progenitor channels are in effect in producing SNe Ib/Ic. This work also demonstrates the power of integral field spectroscopy in investigating SN environments and active star-forming regions.

Spatially resolved synchrotron radiation induced X-ray fluorescence analyses of rare Rembrandt silverpoint drawings

International Nuclear Information System (INIS)

Reiche, I.; Radtke, M.; Berger, A.; Goerner, W.; Merchel, S.; Riesemeier, H.; Bevers, H.

2006-01-01

New analyses of a series of very rare silverpoint drawings that were executed by Rembrandt Harmensz. van Rijn (1606-1669) which are kept today in the Kupferstichkabinett (Museum of Prints and Drawings) of the State Museums of Berlin are reported here. Analysis of these drawings requires particular attention because the study has to be fully non-destructive and extremely sensitive. The metal alloy on the paper does not exceed some hundreds of μg/cm 2 . Therefore, synchrotron radiation induced X-ray fluorescence (SR-XRF) is - together with external micro-proton-induced X-ray emission - the only well-suited method for the analyses of metalpoint drawings. In some primary work, about 25 German and Flemish metalpoint drawings were investigated using spatially resolved SR-XRF analysis at the BAMline at BESSY. This study enlarges the existing French-German database of metalpoint drawings dating from the 15th and 16th centuries, as these Rembrandt drawings originate from the 17th century where this graphical technique was even rarer and already obsolete. It also illustrates how SR-XRF analysis can reinforce art historical assumptions on the dating of drawings and their connection. (orig.)

Identification of Different Classes of Luminal Progenitor Cells within Prostate Tumors

Directory of Open Access Journals (Sweden)

Supreet Agarwal

2015-12-01

Full Text Available Primary prostate cancer almost always has a luminal phenotype. However, little is known about the stem/progenitor properties of transformed cells within tumors. Using the aggressive Pten/Tp53-null mouse model of prostate cancer, we show that two classes of luminal progenitors exist within a tumor. Not only did tumors contain previously described multipotent progenitors, but also a major population of committed luminal progenitors. Luminal cells, sorted directly from tumors or grown as organoids, initiated tumors of adenocarcinoma or multilineage histological phenotypes, which is consistent with luminal and multipotent differentiation potentials, respectively. Moreover, using organoids we show that the ability of luminal-committed progenitors to self-renew is a tumor-specific property, absent in benign luminal cells. Finally, a significant fraction of luminal progenitors survived in vivo castration. In all, these data reveal two luminal tumor populations with different stem/progenitor cell capacities, providing insight into prostate cancer cells that initiate tumors and can influence treatment response.

DARK MATTER SUBSTRUCTURE DETECTION USING SPATIALLY RESOLVED SPECTROSCOPY OF LENSED DUSTY GALAXIES

Energy Technology Data Exchange (ETDEWEB)

Hezaveh, Yashar; Holder, Gilbert [Department of Physics, McGill University, 3600 Rue University, Montreal, Quebec H3A 2T8 (Canada); Dalal, Neal [Astronomy Department, University of Illinois at Urbana-Champaign, 1002 West Green Street, Urbana, IL 61801 (United States); Kuhlen, Michael [Theoretical Astrophysics Center, University of California, Berkeley, CA 94720 (United States); Marrone, Daniel [Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States); Murray, Norman [CITA, University of Toronto, 60 St. George Street, Toronto, ON M5S 3H8 (Canada); Vieira, Joaquin [California Institute of Technology, 1200 East California Blvd, MC 249-17, Pasadena, CA 91125 (United States)

2013-04-10

We investigate how strong lensing of dusty, star-forming galaxies (DSFGs) by foreground galaxies can be used as a probe of dark matter halo substructure. We find that spatially resolved spectroscopy of lensed sources allows dramatic improvements to measurements of lens parameters. In particular, we find that modeling of the full, three-dimensional (angular position and radial velocity) data can significantly facilitate substructure detection, increasing the sensitivity of observables to lower mass subhalos. We carry out simulations of lensed dusty sources observed by early ALMA (Cycle 1) and use a Fisher matrix analysis to study the parameter degeneracies and mass detection limits of this method. We find that even with conservative assumptions, it is possible to detect galactic dark matter subhalos of {approx}10{sup 8} M{sub Sun} with high significance in most lensed DSFGs. Specifically, we find that in typical DSFG lenses, there is a {approx}55% probability of detecting a substructure with M > 10{sup 8} M{sub Sun} with more than 5{sigma} detection significance in each lens, if the abundance of substructure is consistent with previous lensing results. The full ALMA array, with its significantly enhanced sensitivity and resolution, should improve these estimates considerably. Given the sample of {approx}100 lenses provided by surveys such as the South Pole Telescope, our understanding of dark matter substructure in typical galaxy halos is poised to improve dramatically over the next few years.

The PyCASSO database: spatially resolved stellar population properties for CALIFA galaxies

Science.gov (United States)

de Amorim, A. L.; García-Benito, R.; Cid Fernandes, R.; Cortijo-Ferrero, C.; González Delgado, R. M.; Lacerda, E. A. D.; López Fernández, R.; Pérez, E.; Vale Asari, N.

2017-11-01

The Calar Alto Legacy Integral Field Area (CALIFA) survey, a pioneer in integral field spectroscopy legacy projects, has fostered many studies exploring the information encoded on the spatially resolved data on gaseous and stellar features in the optical range of galaxies. We describe a value-added catalogue of stellar population properties for CALIFA galaxies analysed with the spectral synthesis code starlight and processed with the pycasso platform. Our public database (http://pycasso.ufsc.br/, mirror at http://pycasso.iaa.es/) comprises 445 galaxies from the CALIFA Data Release 3 with COMBO data. The catalogue provides maps for the stellar mass surface density, mean stellar ages and metallicities, stellar dust attenuation, star formation rates, and kinematics. Example applications both for individual galaxies and for statistical studies are presented to illustrate the power of this data set. We revisit and update a few of our own results on mass density radial profiles and on the local mass-metallicity relation. We also show how to employ the catalogue for new investigations, and show a pseudo Schmidt-Kennicutt relation entirely made with information extracted from the stellar continuum. Combinations to other databases are also illustrated. Among other results, we find a very good agreement between star formation rate surface densities derived from the stellar continuum and the H α emission. This public catalogue joins the scientific community's effort towards transparency and reproducibility, and will be useful for researchers focusing on (or complementing their studies with) stellar properties of CALIFA galaxies.

Spatially resolved electronic structure inside and outside the vortex cores of a high-temperature superconductor

Science.gov (United States)

Mitrović, V. F.; Sigmund, E. E.; Eschrig, M.; Bachman, H. N.; Halperin, W. P.; Reyes, A. P.; Kuhns, P.; Moulton, W. G.

2001-10-01

Puzzling aspects of high-transition-temperature (high-Tc) superconductors include the prevalence of magnetism in the normal state and the persistence of superconductivity in high magnetic fields. Superconductivity and magnetism generally are thought to be incompatible, based on what is known about conventional superconductors. Recent results, however, indicate that antiferromagnetism can appear in the superconducting state of a high-Tc superconductor in the presence of an applied magnetic field. Magnetic fields penetrate a superconductor in the form of quantized flux lines, each of which represents a vortex of supercurrents. Superconductivity is suppressed in the core of the vortex and it has been suggested that antiferromagnetism might develop there. Here we report the results of a high-field nuclear-magnetic-resonance (NMR) imaging experiment in which we spatially resolve the electronic structure of near-optimally doped YBa2Cu3O7-δ inside and outside vortex cores. Outside the cores, we find strong antiferromagnetic fluctuations, whereas inside we detect electronic states that are rather different from those found in conventional superconductors.

Comparison of two spatially-resolved fossil fuel CO2 emissions inventories at the urban scale in four US cities

Science.gov (United States)

Liang, J.; Gurney, K. R.; O'Keeffe, D.; Patarasuk, R.; Hutchins, M.; Rao, P.

2017-12-01

Spatially-resolved fossil fuel CO2 (FFCO2) emissions are used not only in complex atmospheric modeling systems as prior scenarios to simulate concentrations of CO2 in the atmosphere, but to improve understanding of relationships with socioeconomic factors in support of sustainability policymaking. We present a comparison of ODIAC, a top-down global gridded FFCO2 emissions dataset, and Hesita, a bottom-up FFCO2 emissions dataset, in four US cities, including Los Angles, Indianapolis, Salt Lake City and Baltimore City. ODIAC was developed by downscaling national total emissions to 1km-by-1km grid cells using satellite nightlight imagery as proxy. Hesita was built from the ground up by allocating sector-specific county-level emissions to urban-level spatial surrogates including facility locations, road maps, building footprints/parcels, railroad maps and shipping lanes. The differences in methodology and data sources could lead to large discrepancies in FFCO2 estimates at the urban scale, and these discrepancies need to be taken into account in conducting atmospheric modeling or socioeconomic analysis. This comparison work is aimed at quantifying the statistical and spatial difference between the two FFCO2 inventories. An analysis of the difference in total emissions, spatial distribution and statistical distribution resulted in the following findings: (1) ODIAC agrees well with Hestia in total FFCO2 emissions estimates across the four cities with a difference from 3%-20%; (2) Small-scale areal and linear spatial features such as roads and buildings are either entirely missing or not very well represented in ODIAC, since nightlight imagery might not be able to capture these information. This might further lead to underestimated on-road FFCO2 emissions in ODIAC; (3) The statistical distribution of ODIAC is more concentrated around the mean with much less samples in the lower range. These phenomena could result from the nightlight halo and saturation effects; (4) The

Strategies to reverse endothelial progenitor cell dysfunction in diabetes.

Science.gov (United States)

Petrelli, Alessandra; Di Fenza, Raffaele; Carvello, Michele; Gatti, Francesca; Secchi, Antonio; Fiorina, Paolo

2012-01-01

Bone-marrow-derived cells-mediated postnatal vasculogenesis has been reported as the main responsible for the regulation of vascular homeostasis in adults. Since their discovery, endothelial progenitor cells have been depicted as mediators of postnatal vasculogenesis for their peculiar phenotype (partially staminal and partially endothelial), their ability to differentiate in endothelial cell line and to be incorporated into the vessels wall during ischemia/damage. Diabetes mellitus, a condition characterized by cardiovascular disease, nephropathy, and micro- and macroangiopathy, showed a dysfunction of endothelial progenitor cells. Herein, we review the mechanisms involved in diabetes-related dysfunction of endothelial progenitor cells, highlighting how hyperglycemia affects the different steps of endothelial progenitor cells lifetime (i.e., bone marrow mobilization, trafficking into the bloodstream, differentiation in endothelial cells, and homing in damaged tissues/organs). Finally, we review preclinical and clinical strategies that aim to revert diabetes-induced dysfunction of endothelial progenitor cells as a means of finding new strategies to prevent diabetic complications.

Strategies to Reverse Endothelial Progenitor Cell Dysfunction in Diabetes

Directory of Open Access Journals (Sweden)

Alessandra Petrelli

2012-01-01

Full Text Available Bone-marrow-derived cells-mediated postnatal vasculogenesis has been reported as the main responsible for the regulation of vascular homeostasis in adults. Since their discovery, endothelial progenitor cells have been depicted as mediators of postnatal vasculogenesis for their peculiar phenotype (partially staminal and partially endothelial, their ability to differentiate in endothelial cell line and to be incorporated into the vessels wall during ischemia/damage. Diabetes mellitus, a condition characterized by cardiovascular disease, nephropathy, and micro- and macroangiopathy, showed a dysfunction of endothelial progenitor cells. Herein, we review the mechanisms involved in diabetes-related dysfunction of endothelial progenitor cells, highlighting how hyperglycemia affects the different steps of endothelial progenitor cells lifetime (i.e., bone marrow mobilization, trafficking into the bloodstream, differentiation in endothelial cells, and homing in damaged tissues/organs. Finally, we review preclinical and clinical strategies that aim to revert diabetes-induced dysfunction of endothelial progenitor cells as a means of finding new strategies to prevent diabetic complications.

Femtosecond Time-resolved Optical Polarigraphy (FTOP)

International Nuclear Information System (INIS)

Aoshima, S.; Fujimoto, M.; Hosoda, M.; Tsuchiya, Y.

2000-01-01

A novel time-resolved imaging technique named FTOP (Femtosecond Time-resolved Optical Polarigraphy) for visualizing the ultrafast propagation dynamics of intense light pulses in a medium has been proposed and demonstrated. Femtosecond snapshot images can be created with a high spatial resolution by imaging only the polarization components of the probe pulse; these polarization components change due to the instantaneous birefringence induced by the pump pulse in the medium. Ultrafast temporal changes in the two-dimensional spatial distribution of the optical pulse intensity were clearly visualized in consecutive images by changing the delay between the pump and probe. We observe that several filaments appear and then come together before the vacuum focus due to nonlinear effects in air. We also prove that filamentation dynamics such as the formation position and the propagation behavior are complex and are strongly affected by the pump energy. The results collected clearly show that this method FTOP succeeds for the first time in directly visualizing the ultrafast dynamics of the self-modulated nonlinear propagation of light. (author)

Quantitative, depth-resolved determination of particle motion using multi-exposure, spatial frequency domain laser speckle imaging.

Science.gov (United States)

Rice, Tyler B; Kwan, Elliott; Hayakawa, Carole K; Durkin, Anthony J; Choi, Bernard; Tromberg, Bruce J

2013-01-01

Laser Speckle Imaging (LSI) is a simple, noninvasive technique for rapid imaging of particle motion in scattering media such as biological tissue. LSI is generally used to derive a qualitative index of relative blood flow due to unknown impact from several variables that affect speckle contrast. These variables may include optical absorption and scattering coefficients, multi-layer dynamics including static, non-ergodic regions, and systematic effects such as laser coherence length. In order to account for these effects and move toward quantitative, depth-resolved LSI, we have developed a method that combines Monte Carlo modeling, multi-exposure speckle imaging (MESI), spatial frequency domain imaging (SFDI), and careful instrument calibration. Monte Carlo models were used to generate total and layer-specific fractional momentum transfer distributions. This information was used to predict speckle contrast as a function of exposure time, spatial frequency, layer thickness, and layer dynamics. To verify with experimental data, controlled phantom experiments with characteristic tissue optical properties were performed using a structured light speckle imaging system. Three main geometries were explored: 1) diffusive dynamic layer beneath a static layer, 2) static layer beneath a diffuse dynamic layer, and 3) directed flow (tube) submerged in a dynamic scattering layer. Data fits were performed using the Monte Carlo model, which accurately reconstructed the type of particle flow (diffusive or directed) in each layer, the layer thickness, and absolute flow speeds to within 15% or better.

3D Spatially Resolved Models of the Intracellular Dynamics of the Hepatitis C Genome Replication Cycle

KAUST Repository

Knodel, Markus

2017-10-02

Mathematical models of virus dynamics have not previously acknowledged spatial resolution at the intracellular level despite substantial arguments that favor the consideration of intracellular spatial dependence. The replication of the hepatitis C virus (HCV) viral RNA (vRNA) occurs within special replication complexes formed from membranes derived from endoplasmatic reticulum (ER). These regions, termed membranous webs, are generated primarily through specific interactions between nonstructural virus-encoded proteins (NSPs) and host cellular factors. The NSPs are responsible for the replication of the vRNA and their movement is restricted to the ER surface. Therefore, in this study we developed fully spatio-temporal resolved models of the vRNA replication cycle of HCV. Our simulations are performed upon realistic reconstructed cell structures-namely the ER surface and the membranous webs-based on data derived from immunostained cells replicating HCV vRNA. We visualized 3D simulations that reproduced dynamics resulting from interplay of the different components of our models (vRNA, NSPs, and a host factor), and we present an evaluation of the concentrations for the components within different regions of the cell. Thus far, our model is restricted to an internal portion of a hepatocyte and is qualitative more than quantitative. For a quantitative adaption to complete cells, various additional parameters will have to be determined through further in vitro cell biology experiments, which can be stimulated by the results deccribed in the present study.

Ionizing radiation induces apoptosis in hematopoietic stem and progenitor cells

International Nuclear Information System (INIS)

Meng, A.; Zhou, D.; Geiger, H.; Zant, G.V.

2003-01-01

The aims of this study was to determine if ionizing radiation (IR) induces apoptosis in hematopoietic stem (HSC) and progenitor cells. Lin-cells were isolated from mouse bone marrow (BM) and pretreated with vehicle or 100 μM z-VAD 1 h prior to exposure to 4 Gy IR. The apoptotic and/or necrotic responses of these cells to IR were analyzed by measuring the annexin V and/or 7-AAD staining in HSC and progenitor populations using flow cytometry, and hematopoietic function of these cells was determined by CAFC assay. Exposure of Lin-cells to IR selectively decreased the numbers of HSC and progenitors in association with an increase in apoptosis in a time-dependent manner. Pretreatment of Lin- cells with z-VAD significantly inhibited IR-induced apoptosis and the decrease in the numbers of HSC and progenitors. However, IR alone or in combination with z-VAD did not lead to a significant increase in necrotic cell death in either HSC or progenitors. In addition, pretreatment of BM cells with z-VAD significantly attenuated IR-induced reduction in the frequencies of day-7, -28 and -35 CAFC. Exposure of HSC and progenitors to IR induces apoptosis. The induction of HSC and progenitor apoptosis contributes to IR-induced suppression of their hematopoietic function

Sub-nanosecond time-resolved near-field scanning magneto-optical microscope.

Science.gov (United States)

Rudge, J; Xu, H; Kolthammer, J; Hong, Y K; Choi, B C

2015-02-01

We report on the development of a new magnetic microscope, time-resolved near-field scanning magneto-optical microscope, which combines a near-field scanning optical microscope and magneto-optical contrast. By taking advantage of the high temporal resolution of time-resolved Kerr microscope and the sub-wavelength spatial resolution of a near-field microscope, we achieved a temporal resolution of ∼50 ps and a spatial resolution of microscope, the magnetic field pulse induced gyrotropic vortex dynamics occurring in 1 μm diameter, 20 nm thick CoFeB circular disks has been investigated. The microscope provides sub-wavelength resolution magnetic images of the gyrotropic motion of the vortex core at a resonance frequency of ∼240 MHz.

Retinal progenitor cell xenografts to the pig retina

DEFF Research Database (Denmark)

Warfvinge, Karin; Kiilgaard, Jens Folke; Lavik, Erin B

2005-01-01

To investigate the survival, integration, and differentiation of mouse retinal progenitor cells after transplantation to the subretinal space of adult pigs.......To investigate the survival, integration, and differentiation of mouse retinal progenitor cells after transplantation to the subretinal space of adult pigs....

Spatially-resolved velocities of thermally-produced spray droplets using a velocity-divided Abel inversion of photographed streaks

Science.gov (United States)

Kawaguchi, Y.; Kobayashi, N.; Yamagata, Y.; Miyazaki, F.; Yamasaki, M.; Muraoka, K.

2017-10-01

Droplet velocities of thermal spray are known to have profound effects on important coating qualities, such as adhesive strength, porosity, and hardness, for various applications. For obtaining the droplet velocities, therefore, the TOF (time-of-flight) technique has been widely used, which relies on observations of emitted radiation from the droplets, where all droplets along the line-of-sight contribute to signals. Because droplets at and near the flow axis mostly contribute coating layers, it has been hoped to get spatially resolved velocities. For this purpose, a velocity-divided Abel inversion was devised from CMOS photographic data. From this result, it has turned out that the central velocity is about 25% higher than that obtained from the TOF technique for the case studied (at the position 150 mm downstream of the plasma spray gun, where substrates for spray coatings are usually placed). Further implications of the obtained results are discussed.

Single cell cultures of Drosophila neuroectodermal and mesectodermal central nervous system progenitors reveal different degrees of developmental autonomy

Directory of Open Access Journals (Sweden)

Technau Gerhard M

2009-08-01

Full Text Available Abstract Background The Drosophila embryonic central nervous system (CNS develops from two sets of progenitor cells, neuroblasts and ventral midline progenitors, which behave differently in many respects. Neuroblasts derive from the neurogenic region of the ectoderm and form the lateral parts of the CNS. Ventral midline precursors are formed by two rows of mesectodermal cells and build the CNS midline. There is plenty of evidence that individual identities are conferred to precursor cells by positional information in the ectoderm. It is unclear, however, how far the precursors can maintain their identities and developmental properties in the absence of normal external signals. Results To separate the respective contributions of autonomous properties versus extrinsic signals during their further development, we isolated individual midline precursors and neuroectodermal precursors at the pre-mitotic gastrula stage, traced their development in vitro, and analyzed the characteristics of their lineages in comparison with those described for the embryo. Although individually cultured mesectodermal cells exhibit basic characteristics of CNS midline progenitors, the clones produced by these progenitors differ from their in situ counterparts with regard to cell numbers, expression of molecular markers, and the separation of neuronal and glial fate. In contrast, clones derived from individually cultured precursors taken from specific dorsoventral zones of the neuroectoderm develop striking similarities to the lineages of neuroblasts that normally delaminate from these zones and develop in situ. Conclusion This in vitro analysis allows for the first time a comparison of the developmental capacities in situ and in vitro of individual neural precursors of defined spatial and temporal origin. The data reveal that cells isolated at the pre-mitotic and pre-delamination stage express characteristics of the progenitor type appropriate to their site of origin in

Endothelial progenitor cells in chronic obstructive pulmonary disease and emphysema

Science.gov (United States)

Tracy, Russell P.; Parikh, Megha A.; Hoffman, Eric A.; Shimbo, Daichi; Austin, John H. M.; Smith, Benjamin M.; Hueper, Katja; Vogel-Claussen, Jens; Lima, Joao; Gomes, Antoinette; Watson, Karol; Kawut, Steven; Barr, R. Graham

2017-01-01

Endothelial injury is implicated in the pathogenesis of COPD and emphysema; however the role of endothelial progenitor cells (EPCs), a marker of endothelial cell repair, and circulating endothelial cells (CECs), a marker of endothelial cell injury, in COPD and its subphenotypes is unresolved. We hypothesized that endothelial progenitor cell populations would be decreased in COPD and emphysema and that circulating endothelial cells would be increased. Associations with other subphenotypes were examined. The Multi-Ethnic Study of Atherosclerosis COPD Study recruited smokers with COPD and controls age 50–79 years without clinical cardiovascular disease. Endothelial progenitor cell populations (CD34+KDR+ and CD34+KDR+CD133+ cells) and circulating endothelial cells (CD45dimCD31+CD146+CD133-) were measured by flow cytometry. COPD was defined by standard spirometric criteria. Emphysema was assessed qualitatively and quantitatively on CT. Full pulmonary function testing and expiratory CTs were measured in a subset. Among 257 participants, both endothelial progenitor cell populations, and particularly CD34+KDR+ endothelial progenitor cells, were reduced in COPD. The CD34+KDR+CD133+ endothelial progenitor cells were associated inversely with emphysema extent. Both endothelial progenitor cell populations were associated inversely with extent of panlobular emphysema and positively with diffusing capacity. Circulating endothelial cells were not significantly altered in COPD but were inversely associated with pulmonary microvascular blood flow on MRI. There was no consistent association of endothelial progenitor cells or circulating endothelial cells with measures of gas trapping. These data provide evidence that endothelial repair is impaired in COPD and suggest that this pathological process is specific to emphysema. PMID:28291826

The impact of spatial resolution on resolving spatial precipitation patterns in the Himalayas

NARCIS (Netherlands)

Bonekamp, P.N.J.; Collier, S.E.; Immerzeel, W.W.

2017-01-01

Frequently used gridded meteorological datasets poorly represent precipitation in the Himalaya due to their relatively low spatial resolution and the associated coarse representation of the complex topography. Dynamical downscaling using high-resolution atmospheric models may improve the accuracy

X Inactivation and Progenitor Cancer Cells

Directory of Open Access Journals (Sweden)

Ruben Agrelo

2011-04-01

Full Text Available In mammals, silencing of one of the two X chromosomes is necessary to achieve dosage compensation. The 17 kb non-coding RNA called Xist triggers X inactivation. Gene silencing by Xist can only be achieved in certain contexts such as in cells of the early embryo and in certain hematopoietic progenitors where silencing factors are present. Moreover, these epigenetic contexts are maintained in cancer progenitors in which SATB1 has been identified as a factor related to Xist-mediated chromosome silencing.

LINKING TYPE Ia SUPERNOVA PROGENITORS AND THEIR RESULTING EXPLOSIONS

International Nuclear Information System (INIS)

Foley, Ryan J.; Kirshner, Robert P.; Simon, Joshua D.; Burns, Christopher R.; Gal-Yam, Avishay; Hamuy, Mario; Morrell, Nidia I.; Phillips, Mark M.; Shields, Gregory A.; Sternberg, Assaf

2012-01-01

Comparing the ejecta velocities at maximum brightness and narrow circumstellar/interstellar Na D absorption line profiles of a sample of 23 Type Ia supernovae (SNe Ia), we determine that the properties of SN Ia progenitor systems and explosions are intimately connected. As demonstrated by Sternberg et al., half of all SNe Ia with detectable Na D absorption at the host-galaxy redshift in high-resolution spectroscopy have Na D line profiles with significant blueshifted absorption relative to the strongest absorption component, which indicates that a large fraction of SN Ia progenitor systems have strong outflows. In this study, we find that SNe Ia with blueshifted circumstellar/interstellar absorption systematically have higher ejecta velocities and redder colors at maximum brightness relative to the rest of the SN Ia population. This result is robust at a 98.9%-99.8% confidence level, providing the first link between the progenitor systems and properties of the explosion. This finding is further evidence that the outflow scenario is the correct interpretation of the blueshifted Na D absorption, adding additional confirmation that some SNe Ia are produced from a single-degenerate progenitor channel. An additional implication is that either SN Ia progenitor systems have highly asymmetric outflows that are also aligned with the SN explosion or SNe Ia come from a variety of progenitor systems where SNe Ia from systems with strong outflows tend to have more kinetic energy per unit mass than those from systems with weak or no outflows.

Development of an integrated fission product release and transport code for spatially resolved full-core calculations of V/HTRs

International Nuclear Information System (INIS)

Xhonneux, Andre; Allelein, Hans-Josef

2014-01-01

The computer codes FRESCO-I, FRESCO-II, PANAMA and SPATRA developed at Forschungszentrum Jülich in Germany in the early 1980s are essential tools to predict the fission product release from spherical fuel elements and the TRISO fuel performance, respectively, under given normal or accidental conditions. These codes are able to calculate a conservative estimation of the source term, i.e. quantity and duration of radionuclide release. Recently, these codes have been reversed engineered, modernized (FORTRAN 95/2003) and combined to form a consistent code named STACY (Source Term Analysis Code System). STACY will later become a module of the V/HTR Code Package (HCP). In addition, further improvements have been implemented to enable more detailed calculations. For example the distinct temperature profile along the pebble radius is now taken into account and coated particle failure rates can be calculated under normal operating conditions. In addition, the absolute fission product release of an V/HTR pebble bed core can be calculated by using the newly developed burnup code Topological Nuclide Transformation (TNT) replacing the former rudimentary approach. As a new functionality, spatially resolved fission product release calculations for normal operating conditions as well as accident conditions can be performed. In case of a full-core calculation, a large number of individual pebbles which follow a random path through the reactor core can be simulated. The history of the individual pebble is recorded, too. Main input data such as spatially resolved neutron fluxes and fluid dynamics data are provided by the VSOP code. Capabilities of the FRESCO-I and SPATRA code which allow for the simulation of the redistribution of fission products within the primary circuit and the deposition of fission products on graphitic and metallic surfaces are also available in STACY. In this paper, details of the STACY model and first results for its application to the 200 MW(th) HTR

Spatially Resolved Carbon Isotope and Elemental Analyses of the Root-Rhizosphere-Soil System to Understand Below-ground Nutrient Interactions

Science.gov (United States)

Denis, E. H.; Ilhardt, P.; Tucker, A. E.; Huggett, N. L.; Rosnow, J. J.; Krogstad, E. J.; Moran, J.

2017-12-01

, soil, and specific types of mineral grains within soil. Integrating spatially resolved analysis of photosynthate distribution with local geochemical microenvironments may reveal key properties of nutrient exchange hotspots that help direct overall plant health and productivity.

Energy dissipation mechanism revealed by spatially resolved Raman thermometry of graphene/hexagonal boron nitride heterostructure devices

Science.gov (United States)

Kim, Daehee; Kim, Hanul; Yun, Wan Soo; Watanabe, Kenji; Taniguchi, Takashi; Rho, Heesuk; Bae, Myung-Ho

2018-04-01

Understanding the energy transport by charge carriers and phonons in two-dimensional (2D) van der Waals heterostructures is essential for the development of future energy-efficient 2D nanoelectronics. Here, we performed in situ spatially resolved Raman thermometry on an electrically biased graphene channel and its hBN substrate to study the energy dissipation mechanism in graphene/hBN heterostructures. By comparing the temperature profile along the biased graphene channel with that along the hBN substrate, we found that the thermal boundary resistance between the graphene and hBN was in the range of (1-2) ~ × 10-7 m2 K W-1 from ~100 °C to the onset of graphene break-down at ~600 °C in air. Consideration of an electro-thermal transport model together with the Raman thermometry conducted in air showed that a doping effect occurred under a strong electric field played a crucial role in the energy dissipation of the graphene/hBN device up to T ~ 600 °C.

THREE-DIMENSIONAL CORE-COLLAPSE SUPERNOVA SIMULATED USING A 15 M{sub ⊙} PROGENITOR

Energy Technology Data Exchange (ETDEWEB)

Lentz, Eric J.; Mezzacappa, Anthony; Harris, J. Austin; Yakunin, Konstantin N. [Department of Physics and Astronomy, University of Tennessee, Knoxville, TN 37996-1200 (United States); Bruenn, Stephen W. [Department of Physics, Florida Atlantic University, 777 Glades Road, Boca Raton, FL 33431-0991 (United States); Hix, W. Raphael [Physics Division, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN 37831-6354 (United States); Messer, O. E. Bronson [National Center for Computational Sciences, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN 37831-6164 (United States); Endeve, Eirik [Computer Science and Mathematics Division, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN 37831-6164 (United States); Blondin, John M. [Department of Physics, North Carolina State University, Raleigh, NC 27695-8202 (United States); Marronetti, Pedro, E-mail: elentz@utk.edu [Physics Division, National Science Foundation, Arlington, VA 22207 (United States)

2015-07-10

We have performed ab initio neutrino radiation hydrodynamics simulations in three and two spatial dimensions (3D and 2D) of core-collapse supernovae from the same 15 M{sub ☉} progenitor through 440 ms after core bounce. Both 3D and 2D models achieve explosions; however, the onset of explosion (shock revival) is delayed by ∼100 ms in 3D relative to the 2D counterpart and the growth of the diagnostic explosion energy is slower. This is consistent with previously reported 3D simulations utilizing iron-core progenitors with dense mantles. In the ∼100 ms before the onset of explosion, diagnostics of neutrino heating and turbulent kinetic energy favor earlier explosion in 2D. During the delay, the angular scale of convective plumes reaching the shock surface grows and explosion in 3D is ultimately lead by a single, large-angle plume, giving the expanding shock a directional orientation not dissimilar from those imposed by axial symmetry in 2D simulations. We posit that shock revival and explosion in the 3D simulation may be delayed until sufficiently large plumes form, whereas such plumes form more rapidly in 2D, permitting earlier explosions.

Haemopoietic progenitor cells in human peripheral blood

International Nuclear Information System (INIS)

Zwaan, F.E.

1980-01-01

The purpose of the investigation reported is to purify haemopoietic progenitor cells from human peripheral blood using density gradient centrifugation in order to isolate a progenitor cell fraction without immunocompetent cells. The purification technique of peripheral blood flow colony forming unit culture (CFU-c) by means of density gradient centrifugation and a combined depletion of various rosettes is described. The results of several 'in vitro' characteristics of purified CFU-c suspensions and of the plasma clot diffusion chamber culture technique are presented. Irradiation studies revealed that for both human bone marrow and peripheral blood the CFU-c were less radioresistant than clusters. Elimination of monocytes (and granulocytes) from the test suspensions induced an alteration in radiosensitivity pararmeters. The results obtained with the different techniques are described by analysing peripheral progenitor cell activity in myeloproliferative disorders. (Auth.)

Constraints on the Progenitor System of SN 2016gkg from a Comprehensive Statistical Analysis

Science.gov (United States)

Sravan, Niharika; Marchant, Pablo; Kalogera, Vassiliki; Margutti, Raffaella

2018-01-01

Type IIb supernovae (SNe) present a unique opportunity for understanding the progenitors of stripped-envelope SNe because the stellar progenitor of several SNe IIb have been identified in pre-explosion images. In this paper, we use Bayesian inference and a large grid of non-rotating solar-metallicity single and binary stellar models to derive the associated probability distributions of single and binary progenitors of the SN IIb 2016gkg using existing observational constraints. We find that potential binary star progenitors have smaller pre-SN hydrogen-envelope and helium-core masses than potential single-star progenitors typically by 0.1 M ⊙ and 2 M ⊙, respectively. We find that, a binary companion, if present, is a main-sequence or red-giant star. Apart from this, we do not find strong constraints on the nature of the companion star. We demonstrate that the range of progenitor helium-core mass inferred from observations could help improve constraints on the progenitor. We find that the probability that the progenitor of SN 2016gkg was a binary is 22% when we use constraints only on the progenitor luminosity and effective temperature. Imposing the range of pre-SN progenitor hydrogen-envelope mass and radius inferred from SN light curves, the probability that the progenitor is a binary increases to 44%. However, there is no clear preference for a binary progenitor. This is in contrast to binaries being the currently favored formation channel for SNe IIb. Our analysis demonstrates the importance of statistical inference methods to constrain progenitor channels.

Neuronal Progenitor Maintenance Requires Lactate Metabolism and PEPCK-M-Directed Cataplerosis.

Science.gov (United States)

Álvarez, Zaida; Hyroššová, Petra; Perales, José Carlos; Alcántara, Soledad

2016-03-01

This study investigated the metabolic requirements for neuronal progenitor maintenance in vitro and in vivo by examining the metabolic adaptations that support neuronal progenitors and neural stem cells (NSCs) in their undifferentiated state. We demonstrate that neuronal progenitors are strictly dependent on lactate metabolism, while glucose induces their neuronal differentiation. Lactate signaling is not by itself capable of maintaining the progenitor phenotype. The consequences of lactate metabolism include increased mitochondrial and oxidative metabolism, with a strict reliance on cataplerosis through the mitochondrial phosphoenolpyruvate carboxykinase (PEPCK-M) pathway to support anabolic functions, such as the production of extracellular matrix. In vivo, lactate maintains/induces populations of postnatal neuronal progenitors/NSCs in a PEPCK-M-dependent manner. Taken together, our data demonstrate that, lactate alone or together with other physical/biochemical cues maintain NSCs/progenitors with a metabolic signature that is classically found in tissues with high anabolic capacity. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

SDSS IV MaNGA - spatially resolved diagnostic diagrams: a proof that many galaxies are LIERs

Science.gov (United States)

Belfiore, Francesco; Maiolino, Roberto; Maraston, Claudia; Emsellem, Eric; Bershady, Matthew A.; Masters, Karen L.; Yan, Renbin; Bizyaev, Dmitry; Boquien, Médéric; Brownstein, Joel R.; Bundy, Kevin; Drory, Niv; Heckman, Timothy M.; Law, David R.; Roman-Lopes, Alexandre; Pan, Kaike; Stanghellini, Letizia; Thomas, Daniel; Weijmans, Anne-Marie; Westfall, Kyle B.

2016-09-01

We study the spatially resolved excitation properties of the ionized gas in a sample of 646 galaxies using integral field spectroscopy data from the Sloan Digital Sky Survey IV Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) programme. Making use of Baldwin-Philips-Terlevich diagnostic diagrams we demonstrate the ubiquitous presence of extended (kpc scale) low-ionization emission-line regions (LIERs) in both star-forming and quiescent galaxies. In star-forming galaxies LIER emission can be associated with diffuse ionized gas, most evident as extraplanar emission in edge-on systems. In addition, we identify two main classes of galaxies displaying LIER emission: `central LIER' (cLIER) galaxies, where central LIER emission is spatially extended, but accompanied by star formation at larger galactocentric distances, and `extended LIER' (eLIER) galaxies, where LIER emission is extended throughout the whole galaxy. In eLIER and cLIER galaxies, LIER emission is associated with radially flat, low H α equivalent width of line emission (<3 Å) and stellar population indices demonstrating the lack of young stellar populations, implying that line emission follows tightly the continuum due to the underlying old stellar population. The H α surface brightness radial profiles are always shallower than 1/r2 and the line ratio [O III] λ5007/[O II] λλ3727,29 (a tracer of the ionization parameter of the gas) shows a flat gradient. This combined evidence strongly supports the scenario in which LIER emission is not due to a central point source but to diffuse stellar sources, the most likely candidates being hot, evolved (post-asymptotic giant branch) stars. Shocks are observed to play a significant role in the ionization of the gas only in rare merging and interacting systems.

An approach to estimate spatial distribution of analyte within cells using spectrally-resolved fluorescence microscopy

Science.gov (United States)

Sharma, Dharmendar Kumar; Irfanullah, Mir; Basu, Santanu Kumar; Madhu, Sheri; De, Suman; Jadhav, Sameer; Ravikanth, Mangalampalli; Chowdhury, Arindam

2017-03-01

While fluorescence microscopy has become an essential tool amongst chemists and biologists for the detection of various analyte within cellular environments, non-uniform spatial distribution of sensors within cells often restricts extraction of reliable information on relative abundance of analytes in different subcellular regions. As an alternative to existing sensing methodologies such as ratiometric or FRET imaging, where relative proportion of analyte with respect to the sensor can be obtained within cells, we propose a methodology using spectrally-resolved fluorescence microscopy, via which both the relative abundance of sensor as well as their relative proportion with respect to the analyte can be simultaneously extracted for local subcellular regions. This method is exemplified using a BODIPY sensor, capable of detecting mercury ions within cellular environments, characterized by spectral blue-shift and concurrent enhancement of emission intensity. Spectral emission envelopes collected from sub-microscopic regions allowed us to compare the shift in transition energies as well as integrated emission intensities within various intracellular regions. Construction of a 2D scatter plot using spectral shifts and emission intensities, which depend on the relative amount of analyte with respect to sensor and the approximate local amounts of the probe, respectively, enabled qualitative extraction of relative abundance of analyte in various local regions within a single cell as well as amongst different cells. Although the comparisons remain semi-quantitative, this approach involving analysis of multiple spectral parameters opens up an alternative way to extract spatial distribution of analyte in heterogeneous systems. The proposed method would be especially relevant for fluorescent probes that undergo relatively nominal shift in transition energies compared to their emission bandwidths, which often restricts their usage for quantitative ratiometric imaging in

Time resolved two- and three-dimensional plasma diagnostics

International Nuclear Information System (INIS)

1991-03-01

This collection of papers on diagnostics in fusion plasmas contains work on the data analysis of inverse problems and on the experimental arrangements presently used to obtain spatially and temporally resolved plasma radial profiles, including electron and ion temperature, plasma density and plasma current profiles. Refs, figs and tabs

α-Ketoglutarate Promotes Pancreatic Progenitor-Like Cell Proliferation

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Jing Song

2018-03-01

Full Text Available A major source of β cell generation is pancreatic progenitor-like cell differentiation. Multiple studies have confirmed that stem cell metabolism plays important roles in self-renewal and proliferation. In the absence of glucose, glutamine provides the energy for cell division and growth. Furthermore, α-ketoglutarate (αKG, a precursor for glutamine synthesis, is sufficient for enabling glutamine-independent cell proliferation. We have demonstrated that αKG contributes to the large-scale proliferation of pancreatic progenitor-like cells that can provide an ample amount of clinically relevant β cells. We compared the mRNA expression of a subset of genes, the abundance of ATP, reactive oxide species, mitochondrial number, and the colony-forming frequency between mouse pancreatic CD133+ and CD133− cells. We employed Real-Time PCR, immunostaining and passage assays to investigate self-renewal and proliferation of pancreatic progenitor-like cells in a 3D culture system in the presence and absence of αKG. The energy metabolism of CD133+ cells was more prone to oxidative phosphorylation. However, in the 3D culture system, when αKG was supplemented to the culture medium, the proliferation of the pancreatic progenitor-like cells was significantly elevated. We confirmed that the presence of αKG correlated with the up-regulation of Ten-Eleven Translocation (Tet. αKG can promote the proliferation of pancreatic progenitor-like cells via the up-regulation of Tet.

α-Ketoglutarate Promotes Pancreatic Progenitor-Like Cell Proliferation.

Science.gov (United States)

Song, Jing; Ma, Dongshen; Xing, Yun; Tang, Shanshan; Alahdal, Murad; Guo, Jiamin; Pan, Yi; Zhang, Yanfeng; Shen, Yumeng; Wu, Qiong; Lu, Zhou; Jin, Liang

2018-03-22

A major source of β cell generation is pancreatic progenitor-like cell differentiation. Multiple studies have confirmed that stem cell metabolism plays important roles in self-renewal and proliferation. In the absence of glucose, glutamine provides the energy for cell division and growth. Furthermore, α-ketoglutarate (αKG), a precursor for glutamine synthesis, is sufficient for enabling glutamine-independent cell proliferation. We have demonstrated that αKG contributes to the large-scale proliferation of pancreatic progenitor-like cells that can provide an ample amount of clinically relevant β cells. We compared the mRNA expression of a subset of genes, the abundance of ATP, reactive oxide species, mitochondrial number, and the colony-forming frequency between mouse pancreatic CD133⁺ and CD133 - cells. We employed Real-Time PCR, immunostaining and passage assays to investigate self-renewal and proliferation of pancreatic progenitor-like cells in a 3D culture system in the presence and absence of αKG. The energy metabolism of CD133⁺ cells was more prone to oxidative phosphorylation. However, in the 3D culture system, when αKG was supplemented to the culture medium, the proliferation of the pancreatic progenitor-like cells was significantly elevated. We confirmed that the presence of αKG correlated with the up-regulation of Ten-Eleven Translocation (Tet). αKG can promote the proliferation of pancreatic progenitor-like cells via the up-regulation of Tet.

Development and molecular composition of the hepatic progenitor cell niche.

Science.gov (United States)

Vestentoft, Peter Siig

2013-05-01

End-stage liver diseases represent major health problems that are currently treated by liver transplantation. However, given the world-wide shortage of donor livers novel strategies are needed for therapeutic treatment. Adult stem cells have the ability to self-renew and differentiate into the more specialized cell types of a given organ and are found in tissues throughout the body. These cells, whose progeny are termed progenitor cells in human liver and oval cells in rodents, have the potential to treat patients through the generation of hepatic parenchymal cells, even from the patient's own tissue. Little is known regarding the nature of the hepatic progenitor cells. Though they are suggested to reside in the most distal part of the biliary tree, the canal of Hering, the lack of unique surface markers for these cells has hindered their isolation and characterization. Upon activation, they proliferate and form ductular structures, termed "ductular reactions", which radiate into the hepatic parenchyma. The ductular reactions contain activated progenitor cells that not only acquire a phenotype resembling that observed in developing liver but also display markers of differentiation shared with the cholangiocytic or hepatocytic lineages, the two parenchymal hepatic cell types. Interactions between the putative progenitor cells, the surrounding support cells and the extracellular matrix scaffold, all constituting the progenitor cell niche, are likely to be important for regulating progenitor cell activity and differentiation. Therefore, identifying novel progenitor cell markers and deciphering their microenvironment could facilitate clinical use. The aims of the present PhD thesis were to expand knowledge of the hepatic progenitor cell niche and characterize it both during development and in disease. Several animal models of hepatic injury are known to induce activation of the progenitor cells. In order to identify possible progenitor cell markers and niche components

NFIX Regulates Neural Progenitor Cell Differentiation During Hippocampal Morphogenesis

Science.gov (United States)

Heng, Yee Hsieh Evelyn; McLeay, Robert C.; Harvey, Tracey J.; Smith, Aaron G.; Barry, Guy; Cato, Kathleen; Plachez, Céline; Little, Erica; Mason, Sharon; Dixon, Chantelle; Gronostajski, Richard M.; Bailey, Timothy L.; Richards, Linda J.; Piper, Michael

2014-01-01

Neural progenitor cells have the ability to give rise to neurons and glia in the embryonic, postnatal and adult brain. During development, the program regulating whether these cells divide and self-renew or exit the cell cycle and differentiate is tightly controlled, and imbalances to the normal trajectory of this process can lead to severe functional consequences. However, our understanding of the molecular regulation of these fundamental events remains limited. Moreover, processes underpinning development of the postnatal neurogenic niches within the cortex remain poorly defined. Here, we demonstrate that Nuclear factor one X (NFIX) is expressed by neural progenitor cells within the embryonic hippocampus, and that progenitor cell differentiation is delayed within Nfix−/− mice. Moreover, we reveal that the morphology of the dentate gyrus in postnatal Nfix−/− mice is abnormal, with fewer subgranular zone neural progenitor cells being generated in the absence of this transcription factor. Mechanistically, we demonstrate that the progenitor cell maintenance factor Sry-related HMG box 9 (SOX9) is upregulated in the hippocampus of Nfix−/− mice and demonstrate that NFIX can repress Sox9 promoter-driven transcription. Collectively, our findings demonstrate that NFIX plays a central role in hippocampal morphogenesis, regulating the formation of neuronal and glial populations within this structure. PMID:23042739

DISAPPEARANCE OF THE PROGENITOR OF SUPERNOVA iPTF13bvn

Energy Technology Data Exchange (ETDEWEB)

Folatelli, Gastón; Bersten, Melina C. [Facultad de Ciencias Astronómicas y Geofísicas, Universidad Nacional de La Plata, Instituto de Astrofísica de La Plata (IALP), CONICET, Paseo del Bosque S/N, B1900FWA La Plata (Argentina); Van Dyk, Schuyler D. [IPAC/Caltech, Mailcode 100-22, Pasadena, CA 91125 (United States); Kuncarayakti, Hanindyo; Pignata, Giuliano; Hamuy, Mario [Millennium Institute of Astrophysics (MAS), Santiago (Chile); Maeda, Keiichi; Nomoto, Ken’ichi; Quimby, Robert M. [Kavli Institute for the Physics and Mathematics of the Universe (WPI), The University of Tokyo, Kashiwa, Chiba 277-8583 (Japan); Zheng, WeiKang; Filippenko, Alexei V.; Clubb, Kelsey I. [Department of Astronomy, University of California, Berkeley, CA 94720-3411 (United States); Smith, Nathan [Steward Observatory, University of Arizona, 933 N. Cherry Avenue, Tucson, AZ 85721 (United States); Elias-Rosa, Nancy [INAF-Osservatorio Astronomico di Padova, Vicolo dell’Osservatorio 5, I-35122 Padova (Italy); Foley, Ryan J. [Astronomy Department, University of Illinois at Urbana-Champaign, 1002 W. Green Street, Urbana, IL 61801 (United States); Miller, Adam A., E-mail: gaston.folatelli@ipmu.jp [Jet Propulsion Laboratory, 4800 Oak Grove Drive, MS 169-506, Pasadena, CA 91109 (United States)

2016-07-10

Supernova (SN) iPTF13bvn in NGC 5806 was the first Type Ib SN to have been tentatively associated with a progenitor in pre-explosion images. We performed deep ultraviolet (UV) and optical Hubble Space Telescope observations of the SN site ∼740 days after explosion. We detect an object in the optical bands that is fainter than the pre-explosion object. This dimming is likely not produced by dust absorption in the ejecta; thus, our finding confirms the connection of the progenitor candidate with the SN. The object in our data is likely dominated by the fading SN, implying that the pre-SN flux is mostly due to the progenitor. We compare our revised pre-SN photometry with previously proposed models. Although binary progenitors are favored, models need to be refined. In particular, to comply with our deep UV detection limit, any companion star must be less luminous than a late-O star or substantially obscured by newly formed dust. A definitive progenitor characterization will require further observations to disentangle the contribution of a much fainter SN and its environment.

Characterization of Hemagglutinin Negative Botulinum Progenitor Toxins

Directory of Open Access Journals (Sweden)

Suzanne R. Kalb

2017-06-01

Full Text Available Botulism is a disease involving intoxication with botulinum neurotoxins (BoNTs, toxic proteins produced by Clostridium botulinum and other clostridia. The 150 kDa neurotoxin is produced in conjunction with other proteins to form the botulinum progenitor toxin complex (PTC, alternating in size from 300 kDa to 500 kDa. These progenitor complexes can be classified into hemagglutinin positive or hemagglutinin negative, depending on the ability of some of the neurotoxin-associated proteins (NAPs to cause hemagglutination. The hemagglutinin positive progenitor toxin complex consists of BoNT, nontoxic non-hemagglutinin (NTNH, and three hemagglutinin proteins; HA-70, HA-33, and HA-17. Hemagglutinin negative progenitor toxin complexes contain BoNT and NTNH as the minimally functional PTC (M-PTC, but not the three hemagglutinin proteins. Interestingly, the genome of hemagglutinin negative progenitor toxin complexes comprises open reading frames (orfs which encode for three proteins, but the existence of these proteins has not yet been extensively demonstrated. In this work, we demonstrate that these three proteins exist and form part of the PTC for hemagglutinin negative complexes. Several hemagglutinin negative strains producing BoNT/A, /E, and /F were found to contain the three open reading frame proteins. Additionally, several BoNT/A-containing bivalent strains were examined, and NAPs from both genes, including the open reading frame proteins, were associated with BoNT/A. The open reading frame encoded proteins are more easily removed from the botulinum complex than the hemagglutinin proteins, but are present in several BoNT/A and /F toxin preparations. These are not easily removed from the BoNT/E complex, however, and are present even in commercially-available purified BoNT/E complex.

Characterization of Proliferating Neural Progenitors after Spinal Cord Injury in Adult Zebrafish.

Directory of Open Access Journals (Sweden)

Subhra Prakash Hui

Full Text Available Zebrafish can repair their injured brain and spinal cord after injury unlike adult mammalian central nervous system. Any injury to zebrafish spinal cord would lead to increased proliferation and neurogenesis. There are presences of proliferating progenitors from which both neuronal and glial loss can be reversed by appropriately generating new neurons and glia. We have demonstrated the presence of multiple progenitors, which are different types of proliferating populations like Sox2+ neural progenitor, A2B5+ astrocyte/ glial progenitor, NG2+ oligodendrocyte progenitor, radial glia and Schwann cell like progenitor. We analyzed the expression levels of two common markers of dedifferentiation like msx-b and vimentin during regeneration along with some of the pluripotency associated factors to explore the possible role of these two processes. Among the several key factors related to pluripotency, pou5f1 and sox2 are upregulated during regeneration and associated with activation of neural progenitor cells. Uncovering the molecular mechanism for endogenous regeneration of adult zebrafish spinal cord would give us more clues on important targets for future therapeutic approach in mammalian spinal cord repair and regeneration.

Uncovering the Number and Clonal Dynamics of Mesp1 Progenitors during Heart Morphogenesis

Directory of Open Access Journals (Sweden)

Samira Chabab

2016-01-01

Full Text Available The heart arises from distinct sources of cardiac progenitors that independently express Mesp1 during gastrulation. The precise number of Mesp1 progenitors that are specified during the early stage of gastrulation, and their clonal behavior during heart morphogenesis, is currently unknown. Here, we used clonal and mosaic tracing of Mesp1-expressing cells combined with quantitative biophysical analysis of the clonal data to define the number of cardiac progenitors and their mode of growth during heart development. Our data indicate that the myocardial layer of the heart derive from ∼250 Mesp1-expressing cardiac progenitors born during gastrulation. Despite arising at different time points and contributing to different heart regions, the temporally distinct cardiac progenitors present very similar clonal dynamics. These results provide insights into the number of cardiac progenitors and their mode of growth and open up avenues to decipher the clonal dynamics of progenitors in other organs and tissues.

Prolonged Mitosis of Neural Progenitors Alters Cell Fate in the Developing Brain.

Science.gov (United States)

Pilaz, Louis-Jan; McMahon, John J; Miller, Emily E; Lennox, Ashley L; Suzuki, Aussie; Salmon, Edward; Silver, Debra L

2016-01-06

Embryonic neocortical development depends on balanced production of progenitors and neurons. Genetic mutations disrupting progenitor mitosis frequently impair neurogenesis; however, the link between altered mitosis and cell fate remains poorly understood. Here we demonstrate that prolonged mitosis of radial glial progenitors directly alters neuronal fate specification and progeny viability. Live imaging of progenitors from a neurogenesis mutant, Magoh(+/-), reveals that mitotic delay significantly correlates with preferential production of neurons instead of progenitors, as well as apoptotic progeny. Independently, two pharmacological approaches reveal a causal relationship between mitotic delay and progeny fate. As mitotic duration increases, progenitors produce substantially more apoptotic progeny or neurons. We show that apoptosis, but not differentiation, is p53 dependent, demonstrating that these are distinct outcomes of mitotic delay. Together our findings reveal that prolonged mitosis is sufficient to alter fates of radial glia progeny and define a new paradigm to understand how mitosis perturbations underlie brain size disorders such as microcephaly. Copyright © 2016 Elsevier Inc. All rights reserved.

APC sets the Wnt tone necessary for cerebral cortical progenitor development.

Science.gov (United States)

Nakagawa, Naoki; Li, Jingjun; Yabuno-Nakagawa, Keiko; Eom, Tae-Yeon; Cowles, Martis; Mapp, Tavien; Taylor, Robin; Anton, E S

2017-08-15

Adenomatous polyposis coli (APC) regulates the activity of β-catenin, an integral component of Wnt signaling. However, the selective role of the APC-β-catenin pathway in cerebral cortical development is unknown. Here we genetically dissected the relative contributions of APC-regulated β-catenin signaling in cortical progenitor development, a necessary early step in cerebral cortical formation. Radial progenitor-specific inactivation of the APC-β-catenin pathway indicates that the maintenance of appropriate β-catenin-mediated Wnt tone is necessary for the orderly differentiation of cortical progenitors and the resultant formation of the cerebral cortex. APC deletion deregulates β-catenin, leads to high Wnt tone, and disrupts Notch1 signaling and primary cilium maintenance necessary for radial progenitor functions. β-Catenin deregulation directly disrupts cilium maintenance and signaling via Tulp3, essential for intraflagellar transport of ciliary signaling receptors. Surprisingly, deletion of β-catenin or inhibition of β-catenin activity in APC-null progenitors rescues the APC-null phenotype. These results reveal that APC-regulated β-catenin activity in cortical progenitors sets the appropriate Wnt tone necessary for normal cerebral cortical development. © 2017 Nakagawa et al.; Published by Cold Spring Harbor Laboratory Press.

Hmga2 regulates self-renewal of retinal progenitors.

Science.gov (United States)

Parameswaran, Sowmya; Xia, Xiaohuan; Hegde, Ganapati; Ahmad, Iqbal

2014-11-01

In vertebrate retina, histogenesis occurs over an extended period. To sustain the temporal generation of diverse cell types, retinal progenitor cells (RPCs) must self-renew. However, self-renewal and regulation of RPCs remain poorly understood. Here, we demonstrate that cell-extrinsic factors coordinate with the epigenetic regulator high-mobility group AT-hook 2 (Hmga2) to regulate self-renewal of late retinal progenitor cells (RPCs). We observed that a small subset of RPCs was capable of clonal propagation and retained multipotentiality of parents in the presence of endothelial cells (ECs), known self-renewal regulators in various stem cell niches. The self-renewing effects, also observed in vivo, involve multiple intercellular signaling pathways, engaging Hmga2. As progenitors exhaust during retinal development, expression of Hmga2 progressively decreases. Analyses of Hmga2-expression perturbation, in vitro and in vivo, revealed that Hmga2 functionally helps to mediate cell-extrinsic influences on late-retinal progenitor self-renewal. Our results provide a framework for integrating the diverse intercellular influences elicited by epigenetic regulators for self-renewal in a dynamic stem cell niche: the developing vertebrate retina. © 2014. Published by The Company of Biologists Ltd.

Investigations of lateral and vertical compositional gradients in Cu(In,Ga)Se{sub 2} by highly spatially, spectrally and time resolved cathodoluminescence spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Mueller, Mathias; Ribbe, Stefan; Hempel, Thomas; Bertram, Frank; Christen, Juergen [Institute for Experimental Physics, Otto-von-Guericke-University, Magdeburg (Germany); Witte, Wolfram; Hariskos, Dimitrios [Zentrum fuer Sonnenenergie- und Wasserstoff-Forschung Baden-Wuerttemberg (ZSW), Stuttgart (Germany)

2011-07-01

Luminescence properties of Cu(In,Ga)Se{sub 2} (CIGS) layers with different thicknesses were investigated by means of highly spatially, spectrally and time resolved cathodoluminescence (CL) spectroscopy at low temperature (T=5 K). A polycrystalline CIGS thin film with a thickness of 2.4 {mu}m was grown using an in-line co-evaporation process with a final Cu-poor composition on top of a sputtered Mo layer on a soda lime glass substrate. The layer thickness was then reduced by highly controlled bromine methanol etching. The typical grainy (d{sub average}=3 {mu}m) structure of the untouched sample develops thin longish structures under the influence of the etchant. Integral CL spectra of the samples are dominated by donor-acceptor pair (DAP) luminescence. The peak energies of these spectra are ranging from 1.13 eV to 1.22 eV with decreasing layer thickness. The lateral distribution of the luminescence is inhomogeneous regarding the intensity as well as the peak energy. Time resolved CL shows a strong dependence of the initial lifetime from the emission energy.

Binaries discovered by the SPY project V. GD 687 - a massive double degenerate binary progenitor that will merge within a Hubble time

OpenAIRE

Geier, S.; Heber, U.; Kupfer, T.; Napiwotzki, R.

2010-01-01

Aims. The ESO SN Ia Progenitor Survey (SPY) aims at finding merging double degenerate binaries as candidates for supernova type Ia (SN Ia) explosions. A white dwarf merger has also been suggested to explain the formation of rare types of stars like R CrB, extreme helium or He sdO stars. Here we present the hot subdwarf B binary GD 687, which will merge in less than a Hubble time. Methods. The orbital parameters of the close binary have been determined from time resolved spectroscopy. Since GD...

Imaging retinal progenitor lineages in developing zebrafish embryos.

Science.gov (United States)

Jusuf, Patricia; Harris, William A; Poggi, Lucia

2013-03-01

In this protocol, we describe how to make and analyze four dimensional (4D) movies of retinal lineage in the zebrafish embryo in vivo. 4D consists of three spatial dimensions (3D) reconstructed from stacks of confocal planes plus one time dimension. Our imaging is performed on transgenic cells that express fluorescent proteins under the control of cell-specific promoters or on cells that transiently express such reporters in specific retinal cell progenitors. An important aspect of lineage tracing is the ability to follow individual cells as they undergo multiple cell divisions, final migration, and differentiation. This may mean many hours of 4D imaging, requiring that cells be kept healthy and maintained under conditions suitable for normal development. The longest movies we have made are ∼50 h. By analyzing these movies, we can see when a specific cell was born and who its sister was, allowing us to reconstruct its retinal lineages in vivo.

Spectral and spatial resolving of photoelectric property of femtosecond laser drilled holes of GaSb(1-x)Bi(x).

Science.gov (United States)

Pan, C B; Zha, F X; Song, Y X; Shao, J; Dai, Y; Chen, X R; Ye, J Y; Wang, S M

2015-07-15

Femtosecond laser drilled holes of GaSbBi were characterized by the joint measurements of photoconductivity (PC) spectroscopy and laser-beam-induced current (LBIC) mapping. The excitation light in PC was focused down to 60 μm presenting the spectral information of local electronic property of individual holes. A redshift of energy band edge of about 6-8 meV was observed by the PC measurement when the excitation light irradiated on the laser drilled holes. The spatial resolving of photoelectric property was achieved by the LBIC mapping which shows "pseudo-holes" with much larger dimensions than the geometric sizes of the holes. The reduced LBIC current with the pseudo-holes is associated with the redshift effect indicating that the electronic property of the rim areas of the holes is modified by the femtosecond laser drilling.

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Renal blood flow and oxygenation drive nephron progenitor differentiation.

Science.gov (United States)

Rymer, Christopher; Paredes, Jose; Halt, Kimmo; Schaefer, Caitlin; Wiersch, John; Zhang, Guangfeng; Potoka, Douglas; Vainio, Seppo; Gittes, George K; Bates, Carlton M; Sims-Lucas, Sunder

2014-08-01

During kidney development, the vasculature develops via both angiogenesis (branching from major vessels) and vasculogenesis (de novo vessel formation). The formation and perfusion of renal blood vessels are vastly understudied. In the present study, we investigated the regulatory role of renal blood flow and O2 concentration on nephron progenitor differentiation during ontogeny. To elucidate the presence of blood flow, ultrasound-guided intracardiac microinjection was performed, and FITC-tagged tomato lectin was perfused through the embryo. Kidneys were costained for the vasculature, ureteric epithelium, nephron progenitors, and nephron structures. We also analyzed nephron differentiation in normoxia compared with hypoxia. At embryonic day 13.5 (E13.5), the major vascular branches were perfused; however, smaller-caliber peripheral vessels remained unperfused. By E15.5, peripheral vessels started to be perfused as well as glomeruli. While the interior kidney vessels were perfused, the peripheral vessels (nephrogenic zone) remained unperfused. Directly adjacent and internal to the nephrogenic zone, we found differentiated nephron structures surrounded and infiltrated by perfused vessels. Furthermore, we determined that at low O2 concentration, little nephron progenitor differentiation was observed; at higher O2 concentrations, more differentiation of the nephron progenitors was induced. The formation of the developing renal vessels occurs before the onset of blood flow. Furthermore, renal blood flow and oxygenation are critical for nephron progenitor differentiation. Copyright © 2014 the American Physiological Society.

SDSS-IV MaNGA: The Spatially Resolved Stellar Initial Mass Function in ˜400 Early-Type Galaxies

Science.gov (United States)

Parikh, Taniya; Thomas, Daniel; Maraston, Claudia; Westfall, Kyle B.; Goddard, Daniel; Lian, Jianhui; Meneses-Goytia, Sofia; Jones, Amy; Vaughan, Sam; Andrews, Brett H.; Bershady, Matthew; Bizyaev, Dmitry; Brinkmann, Jonathan; Brownstein, Joel R.; Bundy, Kevin; Drory, Niv; Emsellem, Eric; Law, David R.; Newman, Jeffrey A.; Roman-Lopes, Alexandre; Wake, David; Yan, Renbin; Zheng, Zheng

2018-03-01

MaNGA provides the opportunity to make precise spatially resolved measurements of the IMF slope in galaxies owing to its unique combination of spatial resolution, wavelength coverage and sample size. We derive radial gradients in age, element abundances and IMF slope analysing optical and near-infrared absorption features from stacked spectra out to the half-light radius of 366 early-type galaxies with masses 9.9 - 10.8 log M/M⊙. We find flat gradients in age and [α/Fe] ratio, as well as negative gradients in metallicity, consistent with the literature. We further derive significant negative gradients in the [Na/Fe] ratio with galaxy centres being well enhanced in Na abundance by up to 0.5 dex. Finally, we find a gradient in IMF slope with a bottom-heavy IMF in the centre (typical mass excess factor of 1.5) and a Milky Way-type IMF at the half-light radius. This pattern is mass-dependent with the lowest mass galaxies in our sample featuring only a shallow gradient around a Milky Way IMF. Our results imply the local IMF-σ relation within galaxies to be even steeper than the global relation and hint towards the local metallicity being the dominating factor behind the IMF variations. We also employ different stellar population models in our analysis and show that a radial IMF gradient is found independently of the stellar population model used. A similar analysis of the Wing-Ford band provides inconsistent results and further evidence of the difficulty in measuring and modelling this particular feature.

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Invited review: mesenchymal progenitor cells in intramuscular connective tissue development.

Science.gov (United States)

Miao, Z G; Zhang, L P; Fu, X; Yang, Q Y; Zhu, M J; Dodson, M V; Du, M

2016-01-01

The abundance and cross-linking of intramuscular connective tissue contributes to the background toughness of meat, and is thus undesirable. Connective tissue is mainly synthesized by intramuscular fibroblasts. Myocytes, adipocytes and fibroblasts are derived from a common pool of progenitor cells during the early embryonic development. It appears that multipotent mesenchymal stem cells first diverge into either myogenic or non-myogenic lineages; non-myogenic mesenchymal progenitors then develop into the stromal-vascular fraction of skeletal muscle wherein adipocytes, fibroblasts and derived mesenchymal progenitors reside. Because non-myogenic mesenchymal progenitors mainly undergo adipogenic or fibrogenic differentiation during muscle development, strengthening progenitor proliferation enhances the potential for both intramuscular adipogenesis and fibrogenesis, leading to the elevation of both marbling and connective tissue content in the resulting meat product. Furthermore, given the bipotent developmental potential of progenitor cells, enhancing their conversion to adipogenesis reduces fibrogenesis, which likely results in the overall improvement of marbling (more intramuscular adipocytes) and tenderness (less connective tissue) of meat. Fibrogenesis is mainly regulated by the transforming growth factor (TGF) β signaling pathway and its regulatory cascade. In addition, extracellular matrix, a part of the intramuscular connective tissue, provides a niche environment for regulating myogenic differentiation of satellite cells and muscle growth. Despite rapid progress, many questions remain in the role of extracellular matrix on muscle development, and factors determining the early differentiation of myogenic, adipogenic and fibrogenic cells, which warrant further studies.

DNMT1 maintains progenitor function in self-renewing somatic tissue.

Science.gov (United States)

Sen, George L; Reuter, Jason A; Webster, Daniel E; Zhu, Lilly; Khavari, Paul A

2010-01-28

Progenitor cells maintain self-renewing tissues throughout life by sustaining their capacity for proliferation while suppressing cell cycle exit and terminal differentiation. DNA methylation provides a potential epigenetic mechanism for the cellular memory needed to preserve the somatic progenitor state through repeated cell divisions. DNA methyltransferase 1 (DNMT1) maintains DNA methylation patterns after cellular replication. Although dispensable for embryonic stem cell maintenance, the role for DNMT1 in maintaining the progenitor state in constantly replenished somatic tissues, such as mammalian epidermis, is unclear. Here we show that DNMT1 is essential for epidermal progenitor cell function. DNMT1 protein was found enriched in undifferentiated cells, where it was required to retain proliferative stamina and suppress differentiation. In tissue, DNMT1 depletion led to exit from the progenitor cell compartment, premature differentiation and eventual tissue loss. Genome-wide analysis showed that a significant portion of epidermal differentiation gene promoters were methylated in self-renewing conditions but were subsequently demethylated during differentiation. Furthermore, UHRF1 (refs 9, 10), a component of the DNA methylation machinery that targets DNMT1 to hemi-methylated DNA, is also necessary to suppress premature differentiation and sustain proliferation. In contrast, Gadd45A and B, which promote active DNA demethylation, are required for full epidermal differentiation gene induction. These data demonstrate that proteins involved in the dynamic regulation of DNA methylation patterns are required for progenitor maintenance and self-renewal in mammalian somatic tissue.

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Recombination dynamics in coalesced a-plane GaN ELO structures investigated by high spatially and ps-time-resolved cathodoluminescence microscopy

Energy Technology Data Exchange (ETDEWEB)

Bastek, B.; Bertram, F.; Christen, J. [Institute of Experimental Physics, Otto-von-Guericke-University Magdeburg (Germany); Wernicke, T.; Weyers, M. [Ferdinand-Braun-Institut fuer Hoechstfrequenztechnik, Berlin (Germany); Kneissl, M. [Institute of Solid State Physics, Technical University, Berlin (Germany)

2008-07-01

The characteristic epitaxial lateral overgrowth (ELO) domains of fully coalesced a-plane GaN layers were directly imaged by highly spatially and spectrally resolved cathodoluminescence microscopy (CL) at 5 K. The patterned layers were grown by MOVPE on r-plane sapphire substrate and stripe masks oriented in the [01 anti 10] direction. In the area of coherent growth (I) the broad basal plane stacking fault (BSF) emission centered at 3.41 eV dominates the spectra. Also in the region (II) of coalescence the BSF luminescence dominates, however, the intensity increases by one order of magnitude compared to area (I). In complete contrast, in the stripes associated with the laterally grown domains (III) in [0001] direction, exclusively an intense and sharp (D{sup 0},X) emission at 3.475 eV is observed. ps-time-resolved CL of the free excitons (FX) recorded from this domains (III) decays bi-exponentially. The initial lifetime of 180 ps is primarily given by the capture of FX by impurities to form bound excitons (BE). With rising temperature this capture time constant decreases as T{sup -1/4} and reaches a minimum of 104 ps at T=60 K. Above 60 K, i.e. when FX starts to dominate the BEs, the lifetime increases rapidly to a value of 240 ps for 300 K.

Diffusion and spatially resolved NMR in Berea and Venezuelan oil reservoir rocks.

Science.gov (United States)

Murgich, J; Corti, M; Pavesi, L; Voltini, F

1992-01-01

Conventional and spatially resolved proton NMR and relaxation measurements are used in order to study the molecular motions and the equilibrium and nonequilibrium diffusion of oils in Berea sandstone and Venezuelan reservoir rocks. In the water-saturated Berea a single line with T*2 congruent to 150 microseconds is observed, while the relaxation recovery is multiexponential. In an oil reservoir rock (Ful 13) a single narrow line is present while a distribution of relaxation rates is evidenced from the recovery plots. On the contrary, in the Ful 7 sample (extracted at a deeper depth in a different zone) two NMR components are present, with 3.5 and 30 KHz linewidths, and the recovery plot exhibits biexponential law. No echo signal could be reconstructed in the oil reservoir rocks. These findings can be related to the effects in the micropores, where motions at very low frequency can occur in a thin layer. From a comparison of the diffusion constant in water-saturated Berea, D congruent to 5*10(-6) cm2/sec, with the ones in model systems, the average size of the pores is estimated around 40 A. The density profiles at the equilibrium show uniform distribution of oils or of water, and the relaxation rates appear independent from the selected slice. The nonequilibrium diffusion was studied as a function of time in a Berea cylinder with z axis along H0, starting from a thin layer of oil at the base, and detecting the spin density profiles d(z,t) with slice-selection techniques. Simultaneously, the values of T1's were measured locally, and the distribution of the relaxation rates was observed to be present in any slice.(ABSTRACT TRUNCATED AT 250 WORDS)

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TYPE IIb SUPERNOVAE WITH COMPACT AND EXTENDED PROGENITORS

International Nuclear Information System (INIS)

Chevalier, Roger A.; Soderberg, Alicia M.

2010-01-01

The classic example of a Type IIb supernova is SN 1993J, which had a cool extended progenitor surrounded by a dense wind. There is evidence for another category of Type IIb supernova that has a more compact progenitor with a lower density, probably fast, wind. Distinguishing features of the compact category are weak optical emission from the shock heated envelope at early times, nonexistent or very weak H emission in the late nebular phase, rapidly evolving radio emission, rapid expansion of the radio shell, and expected nonthermal as opposed to thermal X-ray emission. Type IIb supernovae that have one or more of these features include SNe 1996cb, 2001ig, 2003bg, 2008ax, and 2008bo. All of these with sufficient radio data (the last four) show evidence for presupernova wind variability. We estimate a progenitor envelope radius ∼1 x 10 11 cm for SN 2008ax, a value consistent with a compact Wolf-Rayet progenitor. Supernovae in the SN 1993J extended category include SN 2001gd and probably the Cas A supernova. We suggest that the compact Type IIb events be designated Type cIIb and the extended ones Type eIIb. The H envelope mass dividing these categories is ∼0.1 M sun .

Postembryonic Nephrogenesis and Persistence of Six2-Expressing Nephron Progenitor Cells in the Reptilian Kidney.

Directory of Open Access Journals (Sweden)

Troy Camarata

Full Text Available New nephron formation (nephrogenesis ceases in mammals around birth and is completely absent in adults. In contrast, postembryonic nephrogenesis is well documented in the mesonephric kidneys of fishes and amphibians. The transient mesonephros in reptiles (including birds and mammals is replaced by the metanephros during embryogenesis. Thus, one may speculate that postembryonic nephrogenesis is restricted to the mesonephric kidney. Previous reports have suggested the metanephros of non-avian reptiles (hereafter reptiles may continually form nephrons throughout life. We investigated the presence of adult nephrogenesis in reptiles by examining adult kidneys from several species including Trachemys scripta, Chrysemys picta, Boa constrictor, Tupinambis tegu, Anolis carolinensis, and Alligator mississipiensis among others. We found that all major reptilian groups (Testudines, Crocodylia, and Squamates showed the presence of adult nephrogenesis. The total amount of nephrogenesis varied greatly between species with turtles displaying the highest density of nephrogenesis. In contrast, we were unable to detect adult nephrogenesis in monotremes, and in the iguanid A. carolinensis. Nephron progenitor cells express the transcription factor Six2, which in mammals, becomes downregulated as the progenitor cell population is exhausted and nephrogenesis ends. Using the alligator as a model, we were able to detect Six2-positive cap mesenchyme cells in the adult kidney, which spatially correlated with areas of nephrogenesis. These results suggest that the metanephric kidney of reptiles has maintained the ability to continually grow new nephrons during postembryonic life, a process lost early in mammalian evolution, likely due to the persistence of a Six2-expressing progenitor cell population.

Postembryonic Nephrogenesis and Persistence of Six2-Expressing Nephron Progenitor Cells in the Reptilian Kidney.

Science.gov (United States)

Camarata, Troy; Howard, Alexis; Elsey, Ruth M; Raza, Sarah; O'Connor, Alice; Beatty, Brian; Conrad, Jack; Solounias, Nikos; Chow, Priscilla; Mukta, Saima; Vasilyev, Aleksandr

2016-01-01

New nephron formation (nephrogenesis) ceases in mammals around birth and is completely absent in adults. In contrast, postembryonic nephrogenesis is well documented in the mesonephric kidneys of fishes and amphibians. The transient mesonephros in reptiles (including birds) and mammals is replaced by the metanephros during embryogenesis. Thus, one may speculate that postembryonic nephrogenesis is restricted to the mesonephric kidney. Previous reports have suggested the metanephros of non-avian reptiles (hereafter reptiles) may continually form nephrons throughout life. We investigated the presence of adult nephrogenesis in reptiles by examining adult kidneys from several species including Trachemys scripta, Chrysemys picta, Boa constrictor, Tupinambis tegu, Anolis carolinensis, and Alligator mississipiensis among others. We found that all major reptilian groups (Testudines, Crocodylia, and Squamates) showed the presence of adult nephrogenesis. The total amount of nephrogenesis varied greatly between species with turtles displaying the highest density of nephrogenesis. In contrast, we were unable to detect adult nephrogenesis in monotremes, and in the iguanid A. carolinensis. Nephron progenitor cells express the transcription factor Six2, which in mammals, becomes downregulated as the progenitor cell population is exhausted and nephrogenesis ends. Using the alligator as a model, we were able to detect Six2-positive cap mesenchyme cells in the adult kidney, which spatially correlated with areas of nephrogenesis. These results suggest that the metanephric kidney of reptiles has maintained the ability to continually grow new nephrons during postembryonic life, a process lost early in mammalian evolution, likely due to the persistence of a Six2-expressing progenitor cell population.

Postembryonic Nephrogenesis and Persistence of Six2-Expressing Nephron Progenitor Cells in the Reptilian Kidney

Science.gov (United States)

Camarata, Troy; Howard, Alexis; Elsey, Ruth M.; Raza, Sarah; O’Connor, Alice; Beatty, Brian; Conrad, Jack; Solounias, Nikos; Chow, Priscilla; Mukta, Saima; Vasilyev, Aleksandr

2016-01-01

New nephron formation (nephrogenesis) ceases in mammals around birth and is completely absent in adults. In contrast, postembryonic nephrogenesis is well documented in the mesonephric kidneys of fishes and amphibians. The transient mesonephros in reptiles (including birds) and mammals is replaced by the metanephros during embryogenesis. Thus, one may speculate that postembryonic nephrogenesis is restricted to the mesonephric kidney. Previous reports have suggested the metanephros of non-avian reptiles (hereafter reptiles) may continually form nephrons throughout life. We investigated the presence of adult nephrogenesis in reptiles by examining adult kidneys from several species including Trachemys scripta, Chrysemys picta, Boa constrictor, Tupinambis tegu, Anolis carolinensis, and Alligator mississipiensis among others. We found that all major reptilian groups (Testudines, Crocodylia, and Squamates) showed the presence of adult nephrogenesis. The total amount of nephrogenesis varied greatly between species with turtles displaying the highest density of nephrogenesis. In contrast, we were unable to detect adult nephrogenesis in monotremes, and in the iguanid A. carolinensis. Nephron progenitor cells express the transcription factor Six2, which in mammals, becomes downregulated as the progenitor cell population is exhausted and nephrogenesis ends. Using the alligator as a model, we were able to detect Six2-positive cap mesenchyme cells in the adult kidney, which spatially correlated with areas of nephrogenesis. These results suggest that the metanephric kidney of reptiles has maintained the ability to continually grow new nephrons during postembryonic life, a process lost early in mammalian evolution, likely due to the persistence of a Six2-expressing progenitor cell population. PMID:27144443

Spatially Resolved Quantification of the Surface Reactivity of Solid Catalysts.

Science.gov (United States)

Huang, Bing; Xiao, Li; Lu, Juntao; Zhuang, Lin

2016-05-17

A new property is reported that accurately quantifies and spatially describes the chemical reactivity of solid surfaces. The core idea is to create a reactivity weight function peaking at the Fermi level, thereby determining a weighted summation of the density of states of a solid surface. When such a weight function is defined as the derivative of the Fermi-Dirac distribution function at a certain non-zero temperature, the resulting property is the finite-temperature chemical softness, termed Fermi softness (SF ), which turns out to be an accurate descriptor of the surface reactivity. The spatial image of SF maps the reactive domain of a heterogeneous surface and even portrays morphological details of the reactive sites. SF analyses reveal that the reactive zones on a Pt3 Y(111) surface are the platinum sites rather than the seemingly active yttrium sites, and the reactivity of the S-dimer edge of MoS2 is spatially anisotropic. Our finding is of fundamental and technological significance to heterogeneous catalysis and industrial processes demanding rational design of solid catalysts. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Final Technical Report - Consolidating Biomass Pretreatment with Saccharification by Resolving the Spatial Control Mechanisms of Fungi

Energy Technology Data Exchange (ETDEWEB)

Schilling, Jonathan [Univ. of Minnesota, Minneapolis, MN (United States)

2017-07-06

Consolidated bioprocessing (CBP) of lignocellulose combines enzymatic sugar release (saccharification) with fermentation, but pretreatments remain separate and costly. In nature, lignocellulose-degrading brown rot fungi consolidate pretreatment and saccharification, likely using spatial gradients to partition these incompatible reactions. With the field of biocatalysis maturing, reaction partitioning is increasingly reproducible for commercial use. Therefore, my goal was to resolve the reaction partitioning mechanisms of brown rot fungi so that they can be applied to bioconversion of lignocellulosic feedstocks. Brown rot fungi consolidate oxidative pretreatments with saccharification and are a focus for biomass refining because 1) they attain >99% sugar yield without destroying lignin, 2) they use a simplified cellulase suite that lacks exoglucanase, and 3) their non-enzymatic pretreatment is facilitative and may be accelerated. Specifically, I hypothesized that during brown rot, oxidative pretreatments occur ahead of enzymatic saccharification, spatially, and the fungus partitions these reactions using gradients in pH, lignin reactivity, and plant cell wall porosity. In fact, we found three key results during these experiments for this work: 1) Brown rot fungi have an inducible cellulase system, unlike previous descriptions of a constitutive mechanism. 2) The induction of cellulases is delayed until there is repression of oxidatively-linked genes, allowing the brown rot fungi to coordinate two incompatible reactions (oxidative pretreatment with enzymatic saccharification, to release wood sugars) in the same pieces of wood. 3) This transition is mediated by the same wood sugar, cellobiose, released by the oxidative pretreatment step. Collectively, these findings have been published in excellent journal outlets and have been presented at conferences around the United States, and they offer clear targets for gene discovery en route to making biofuels and biochemicals

Selective In Vitro Propagation of Nephron Progenitors Derived from Embryos and Pluripotent Stem Cells

Directory of Open Access Journals (Sweden)

Shunsuke Tanigawa

2016-04-01

Full Text Available Nephron progenitors in the embryonic kidney propagate while generating differentiated nephrons. However, in mice, the progenitors terminally differentiate shortly after birth. Here, we report a method for selectively expanding nephron progenitors in vitro in an undifferentiated state. Combinatorial and concentration-dependent stimulation with LIF, FGF2/9, BMP7, and a WNT agonist is critical for expansion. The purified progenitors proliferated beyond the physiological limits observed in vivo, both for cell numbers and lifespan. Neonatal progenitors were maintained for a week, while progenitors from embryonic day 11.5 expanded 1,800-fold for nearly 20 days and still reconstituted 3D nephrons containing glomeruli and renal tubules. Furthermore, progenitors generated from mouse embryonic stem cells and human induced pluripotent cells could be expanded with retained nephron-forming potential. Thus, we have established in vitro conditions for promoting the propagation of nephron progenitors, which will be essential for dissecting the mechanisms of kidney organogenesis and for regenerative medicine.

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Proof of region-specific multipotent progenitors in human breast epithelia

DEFF Research Database (Denmark)

Fridriksdottir, Agla J; Villadsen, René; Morsing, Mikkel

2017-01-01

in luminal progenitors to interrogate the differentiation repertoire of candidate stem cells in TDLUs. We show that stem-like activity in serial passage culture and in vivo breast morphogenesis relies on the preservation of a myoepithelial phenotype. By enrichment for region-specific progenitors, we identify...

THE TYPE IIb SUPERNOVA 2011dh FROM A SUPERGIANT PROGENITOR

International Nuclear Information System (INIS)

Bersten, Melina C.; Nomoto, Ken'ichi; Folatelli, Gastón; Maeda, Keiichi; Benvenuto, Omar G.; Ergon, Mattias; Sollerman, Jesper; Benetti, Stefano; Ochner, Paolo; Tomasella, Lina; Botticella, Maria Teresa; Fraser, Morgan; Kotak, Rubina

2012-01-01

A set of hydrodynamical models based on stellar evolutionary progenitors is used to study the nature of SN 2011dh. Our modeling suggests that a large progenitor star—with R ∼ 200 R ☉ —is needed to reproduce the early light curve (LC) of SN 2011dh. This is consistent with the suggestion that the yellow super-giant star detected at the location of the supernova (SN) in deep pre-explosion images is the progenitor star. From the main peak of the bolometric LC and expansion velocities, we constrain the mass of the ejecta to be ≈2 M ☉ , the explosion energy to be E = (6-10) × 10 50 erg, and the 56 Ni mass to be approximately 0.06 M ☉ . The progenitor star was composed of a helium core of 3-4 M ☉ and a thin hydrogen-rich envelope of ≈0.1M ☉ with a main-sequence mass estimated to be in the range of 12-15 M ☉ . Our models rule out progenitors with helium-core masses larger than 8 M ☉ , which correspond to M ZAMS ∼> 25M ☉ . This suggests that a single star evolutionary scenario for SN 2011dh is unlikely.

RESOLVED MILLIMETER-WAVELENGTH OBSERVATIONS OF DEBRIS DISKS AROUND SOLAR-TYPE STARS

Energy Technology Data Exchange (ETDEWEB)

Steele, Amy; Hughes, A. Meredith [Department of Astronomy, Van Vleck Observatory, Wesleyan University, 96 Foss Hill Drive, Middletown, CT, 06459 (United States); Carpenter, John [Division of Physics, Mathematics, and Astronomy, MC249-17, California Institute of Technology, Pasadena, CA 91125 (United States); Ricarte, Angelo [J. W. Gibbs Laboratory, Department of Astronomy, Yale University, 260 Whitney Avenue, New Haven, CT 06511 (United States); Andrews, Sean M.; Wilner, David J. [Harvard-Smithsonian Center for Astrophysics, MS-42, 60 Garden Street, Cambridge, MA 02138 (United States); Chiang, Eugene, E-mail: asteele@wesleyan.edu [Department of Astronomy, 501 Campbell Hall, University of California, Berkeley, CA 94720-3411 (United States)

2016-01-01

The presence of debris disks around young main-sequence stars hints at the existence and structure of planetary systems. Millimeter-wavelength observations probe large grains that trace the location of planetesimal belts. The Formation and Evolution of Planetary Systems Spitzer Legacy survey of nearby young solar analogues yielded a sample of five debris disk-hosting stars with millimeter flux suitable for interferometric follow-up. We present observations with the Submillimeter Array (SMA) and the Combined Array for Research in Millimeter-wave Astronomy at ∼2″ resolution that spatially resolve the debris disks around these nearby (d ∼ 50 pc) stars. Two of the five disks (HD 377, HD 8907) are spatially resolved for the first time and one (HD 104860) is resolved at millimeter wavelengths for the first time. We combine our new observations with archival SMA and Atacama Large Millimeter/Submillimeter Array data to enable a uniform analysis of the full five-object sample. We simultaneously model the broadband photometric data and resolved millimeter visibilities to constrain the dust temperatures and disk morphologies, and perform a Markov Chain Monte Carlo analysis to fit for basic structural parameters. We find that the radii and widths of the cold outer belts exhibit properties consistent with scaled-up versions of the Solar System's Kuiper Belt. All the disks exhibit characteristic grain sizes comparable to the blowout size, and all the resolved observations of emission from large dust grains are consistent with an axisymmetric dust distribution to within the uncertainties. These results are consistent with comparable studies carried out at infrared wavelengths.

EVOLUTION OF PROGENITORS FOR ELECTRON CAPTURE SUPERNOVAE

International Nuclear Information System (INIS)

Takahashi, Koh; Umeda, Hideyuki; Yoshida, Takashi

2013-01-01

We provide progenitor models for electron capture supernovae (ECSNe) with detailed evolutionary calculation. We include minor electron capture nuclei using a large nuclear reaction network with updated reaction rates. For electron capture, the Coulomb correction of rates is treated and the contribution from neutron-rich isotopes is taken into account in each nuclear statistical equilibrium (NSE) composition. We calculate the evolution of the most massive super asymptotic giant branch stars and show that these stars undergo off-center carbon burning and form ONe cores at the center. These cores become heavier up to the critical mass of 1.367 M ☉ and keep contracting even after the initiation of O+Ne deflagration. Inclusion of minor electron capture nuclei causes convective URCA cooling during the contraction phase, but the effect on the progenitor evolution is small. On the other hand, electron capture by neutron-rich isotopes in the NSE region has a more significant effect. We discuss the uniqueness of the critical core mass for ECSNe and the effect of wind mass loss on the plausibility of our models for ECSN progenitors.

REMOVING BIASES IN RESOLVED STELLAR MASS MAPS OF GALAXY DISKS THROUGH SUCCESSIVE BAYESIAN MARGINALIZATION

Energy Technology Data Exchange (ETDEWEB)

Martínez-García, Eric E. [Cerrada del Rey 40-A, Chimalcoyoc Tlalpan, Ciudad de México, C.P. 14630, México (Mexico); González-Lópezlira, Rosa A.; Bruzual A, Gustavo [Instituto de Radioastronomía y Astrofísica, UNAM, Campus Morelia, Michoacán, C.P. 58089, México (Mexico); Magris C, Gladis, E-mail: martinezgarciaeric@gmail.com [Centro de Investigaciones de Astronomía, Apartado Postal 264, Mérida 5101-A (Venezuela, Bolivarian Republic of)

2017-01-20

Stellar masses of galaxies are frequently obtained by fitting stellar population synthesis models to galaxy photometry or spectra. The state of the art method resolves spatial structures within a galaxy to assess the total stellar mass content. In comparison to unresolved studies, resolved methods yield, on average, higher fractions of stellar mass for galaxies. In this work we improve the current method in order to mitigate a bias related to the resolved spatial distribution derived for the mass. The bias consists in an apparent filamentary mass distribution and a spatial coincidence between mass structures and dust lanes near spiral arms. The improved method is based on iterative Bayesian marginalization, through a new algorithm we have named Bayesian Successive Priors (BSP). We have applied BSP to M51 and to a pilot sample of 90 spiral galaxies from the Ohio State University Bright Spiral Galaxy Survey. By quantitatively comparing both methods, we find that the average fraction of stellar mass missed by unresolved studies is only half what previously thought. In contrast with the previous method, the output BSP mass maps bear a better resemblance to near-infrared images.

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Drug discovery for Diamond-Blackfan anemia using reprogrammed hematopoietic progenitors

Science.gov (United States)

Doulatov, Sergei; Vo, Linda T.; Macari, Elizabeth R.; Wahlster, Lara; Kinney, Melissa A.; Taylor, Alison M.; Barragan, Jessica; Gupta, Manav; McGrath, Katherine; Lee, Hsiang-Ying; Humphries, Jessica M.; DeVine, Alex; Narla, Anupama; Alter, Blanche P.; Beggs, Alan H.; Agarwal, Suneet; Ebert, Benjamin L.; Gazda, Hanna T.; Lodish, Harvey F.; Sieff, Colin A.; Schlaeger, Thorsten M.; Zon, Leonard I.; Daley, George Q.

2017-01-01

Diamond-Blackfan anemia (DBA) is a congenital disorder characterized by the failure of erythroid progenitor differentiation, severely curtailing red blood cell production. Because many DBA patients fail to respond to corticosteroid therapy, there is considerable need for therapeutics for this disorder. Identifying therapeutics for DBA requires circumventing the paucity of primary patient blood stem and progenitor cells. To this end, we adopted a reprogramming strategy to generate expandable hematopoietic progenitor cells from induced pluripotent stem cells (iPSCs) from DBA patients. Reprogrammed DBA progenitors recapitulate defects in erythroid differentiation, which were rescued by gene complementation. Unbiased chemical screens identified SMER28, a small-molecule inducer of autophagy, which enhanced erythropoiesis in a range of in vitro and in vivo models of DBA. SMER28 acted through autophagy factor ATG5 to stimulate erythropoiesis and up-regulate expression of globin genes. These findings present an unbiased drug screen for hematological disease using iPSCs and identify autophagy as a therapeutic pathway in DBA. PMID:28179501

Luminal progenitors restrict their lineage potential during mammary gland development.

Science.gov (United States)

Rodilla, Veronica; Dasti, Alessandro; Huyghe, Mathilde; Lafkas, Daniel; Laurent, Cécile; Reyal, Fabien; Fre, Silvia

2015-02-01

The hierarchical relationships between stem cells and progenitors that guide mammary gland morphogenesis are still poorly defined. While multipotent basal stem cells have been found within the myoepithelial compartment, the in vivo lineage potential of luminal progenitors is unclear. Here we used the expression of the Notch1 receptor, previously implicated in mammary gland development and tumorigenesis, to elucidate the hierarchical organization of mammary stem/progenitor cells by lineage tracing. We found that Notch1 expression identifies multipotent stem cells in the embryonic mammary bud, which progressively restrict their lineage potential during mammary ductal morphogenesis to exclusively generate an ERαneg luminal lineage postnatally. Importantly, our results show that Notch1-labelled cells represent the alveolar progenitors that expand during pregnancy and survive multiple successive involutions. This study reveals that postnatal luminal epithelial cells derive from distinct self-sustained lineages that may represent the cells of origin of different breast cancer subtypes.

Time-resolved detection of surface plasmon polaritons with a scanning tunneling microscope

DEFF Research Database (Denmark)

Keil, Ulrich Dieter Felix; Ha, T.; Jensen, Jacob Riis

1998-01-01

We present the time-resolved detection of surface plasmon polaritons with an STM. The results indicate that the time resolved signal is due to rectification of coherently superimposed plasmon voltages. The comparison with differential reflectivity measurements shows that the tip itself influences...... the decay of the plasmon-field coherence. Generation of the measured signal at the tunneling junction offers the possibility to observe ultrafast effects with a spatial resolution determined by the tunneling junction...

First Resolved Images of the Mira AB Symbiotic Binary at Centimeter Wavelengths

OpenAIRE

Matthews, Lynn D.; Karovska, Margarita

2005-01-01

We report the first spatially resolved radio continuum measurements of the Mira AB symbiotic binary system, based on observations obtained with the Very Large Array (VLA). This is the first time that a symbiotic binary has been resolved unambiguously at centimeter wavelengths. We describe the results of VLA monitoring of both stars over a ten month period, together with constraints on their individual spectral energy distributions, variability, and radio emission mechanisms. The emission from...

Spatially resolved speckle-correlometry of sol-gel transition

Science.gov (United States)

Isaeva, A. A.; Isaeva, E. A.; Pantyukov, A. V.; Zimnyakov, D. A.

2018-04-01

Sol-gel transition was studied using the speckle correlometry method with a localized light source and spatial filtering of backscattered radiation. Water solutions of technical or food gelatin with added TiO2 nanoparticles were used as studied objects. Structural transformation of "sol-gel" system was studied at various temperatures from 25°C to 50°C using analysis of the correlation and structure functions of speckle intensity fluctuations. The characteristic temperatures of "sol - gel" transition were evaluated for studied systems. Obtained results can be used for various applications in biomedicine and food industry.

Simultaneously time- and space-resolved spectroscopic characterization of laser-produced plasmas

International Nuclear Information System (INIS)

Charatis, G.; Young, B.K.F.; Busch, G.E.

1988-01-01

The CHROMA laser facility at KMS Fusion has been used to irradiate a variety of microdot targets. These include aluminum dots and mixed bromine dots doped with K-shell (magnesium) emitters. Simultaneously time- and space-resolved K-shell and L-shell spectra have been measured and compared to dynamic model predictions. The electron density profiles are measured using holographic interferometry. Temperatures, densities, and ionization distributions are determined using K-shell and L-shell spectral techniques. Time and spatial gradients are resolved simultaneously using three diagnostics: a framing crystal x-ray spectrometer, an x-ray streaked crystal spectrometer with a spatial imaging slit, and a 4-frame holographic interferometer. Significant differences have been found between the interferometric and the model-dependent spectral measurements of plasma density. Predictions by new non-stationary L-shell models currently being developed are also presented. 14 refs., 10 figs

Selective In Vitro Propagation of Nephron Progenitors Derived from Embryos and Pluripotent Stem Cells.

Science.gov (United States)

Tanigawa, Shunsuke; Taguchi, Atsuhiro; Sharma, Nirmala; Perantoni, Alan O; Nishinakamura, Ryuichi

2016-04-26

Nephron progenitors in the embryonic kidney propagate while generating differentiated nephrons. However, in mice, the progenitors terminally differentiate shortly after birth. Here, we report a method for selectively expanding nephron progenitors in vitro in an undifferentiated state. Combinatorial and concentration-dependent stimulation with LIF, FGF2/9, BMP7, and a WNT agonist is critical for expansion. The purified progenitors proliferated beyond the physiological limits observed in vivo, both for cell numbers and lifespan. Neonatal progenitors were maintained for a week, while progenitors from embryonic day 11.5 expanded 1,800-fold for nearly 20 days and still reconstituted 3D nephrons containing glomeruli and renal tubules. Furthermore, progenitors generated from mouse embryonic stem cells and human induced pluripotent cells could be expanded with retained nephron-forming potential. Thus, we have established in vitro conditions for promoting the propagation of nephron progenitors, which will be essential for dissecting the mechanisms of kidney organogenesis and for regenerative medicine. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

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Adaptive remodeling of the biliary tree: the essence of liver progenitor cell expansion.

Science.gov (United States)

Kok, Cindy Yuet-Yin; Miyajima, Atsushi; Itoh, Tohru

2015-07-01

The liver progenitor cell population has long been thought to exist within the liver. However, there are no standardized criteria for defining the liver progenitor cells, and there has been intense debate about the origin of these cells in the adult liver. The characteristics of such cells vary depending on the disease model used and also on the method of analysis. Visualization of three-dimensional biliary structures has revealed that the emergence of liver progenitor cells essentially reflects the adaptive remodeling of the hepatic biliary network in response to liver injury. We propose that the progenitor cell exists as a subpopulation in the biliary tree and show that the appearance of liver progenitor cells in injured parenchyma is reflective of extensive remodeling of the biliary structure. © 2015 Japanese Society of Hepato-Biliary-Pancreatic Surgery.

The Progenitors of Local Ultra-massive Galaxies Across Cosmic Time

DEFF Research Database (Denmark)

Marchesini, Danilo; Muzzin, Adam; Stefanon, Mauro

2014-01-01

in age of $z=0$ UMGs as derived from their fossil records. The progenitors of local UMGs, including the star-forming ones, never lived on the blue cloud since $z=3$. We propose an alternative path for the formation of local UMGs that refines previously proposed pictures and that is fully consistent......-forming galaxies progressively increases, with the progenitors at $2z 1$, whereas the remaining was assembled via merging from $z\\sim 1$ to the present. Most of the quenching of the star-forming progenitors happened between $z=2.75$ and $z=1.25$, in good agreement with the typical formation redshift and scatter...

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SPATIALLY RESOLVING THE HK Tau B EDGE-ON DISK FROM 1.2 TO 4.7 μm: A UNIQUE SCATTERED LIGHT DISK

International Nuclear Information System (INIS)

McCabe, C.; Duchene, G.; Pinte, C.; Menard, F.; Stapelfeldt, K. R.; Ghez, A. M.

2011-01-01

We present spatially resolved scattered light images of the circumstellar disk around HK Tau B at 3.8 and 4.7 μm taken with the Keck Telescope Laser Guide Star Adaptive Optics (AO) system, and 1.6-2.12 μm images taken with the Very Large Telescope/NACO AO system. Combined with previously published optical Hubble Space Telescope data, we investigate the spatially resolved scattered light properties of this edge-on circumstellar disk and probe for the presence of large grains. The 0.6-3.8 μm scattered light observations reveal strong, and in some cases, unusual, wavelength dependencies in the observed disk morphology. The separation between the two scattered light nebulae, which is directly proportional to the disk-mass-opacity product, decreases by 30% between 0.6 and 3.8 μm. Over the same wavelength range, the FWHM of the disk nebulosity declines by a factor of two, while the flux ratio between the two nebulae increases by a factor of ∼8. No other disk known to date shows a flux ratio that increases with wavelength. Both the FWHM and nebula flux ratio are affected by the scattering phase function and the observed behavior can most readily be explained by a phase function that becomes more forward throwing with wavelength. The multi-wavelength scattered light observations also confirm the asymmetric nature of the disk and show that the level of asymmetry is a function of wavelength. We use the MCFOST radiative transfer code to model the disk at four wavelengths, corresponding to the I, H, Ks, and L' bandpasses. A single power-law grain size distribution can recreate the observed disk properties simultaneously at all four wavelengths. Bayesian analysis of the dust parameters finds a 99% probability that the maximum grain size is 5.5 μm or larger. We also find that the grain size distribution is steep, with a 99% probability of a power-law index of 4.2 or larger, suggesting that these large grains are a small fraction of the overall dust population. The best

Bone marrow niche-inspired, multiphase expansion of megakaryocytic progenitors with high polyploidization potential.

Science.gov (United States)

Panuganti, Swapna; Papoutsakis, Eleftherios T; Miller, William M

2010-10-01

Megakaryopoiesis encompasses hematopoietic stem and progenitor cell (HSPC) commitment to the megakaryocytic cell (Mk) lineage, expansion of Mk progenitors and mature Mks, polyploidization and platelet release. pH and pO2 increase from the endosteum to sinuses, and different cytokines are important for various stages of differentiation. We hypothesized that mimicking the changing conditions during Mk differentiation in the bone marrow would facilitate expansion of progenitors that could generate many high-ploidy Mks. CD34+ HSPCs were cultured at pH 7.2 and 5% O2 with stem cell factor (SCF), thrombopoietin (Tpo) and all combinations of Interleukin (IL)-3, IL-6, IL-11 and Flt-3 ligand to promote Mk progenitor expansion. Cells cultured with selected cytokines were shifted to pH 7.4 and 20% O2 to generate mature Mks, and treated with nicotinamide (NIC) to enhance polyploidization. Using Tpo + SCF + IL-3 + IL-11, we obtained 3.5 CD34+ CD41+ Mk progenitors per input HSPC, while increasing purity from 1% to 17%. Cytokine cocktails with IL-3 yielded more progenitors and mature Mks, although the purities were lower. Mk production was much greater at higher pH and pO2. Although fewer progenitors were present, shifting to 20% O2 /pH 7.4 at day 5 (versus days 7 or 9) yielded the greatest mature Mk production, 14 per input HSPC. NIC more than doubled the percentage of high-ploidy Mks to 40%. We obtained extensive Mk progenitor expansion, while ensuring that the progenitors could produce high-ploidy Mks. We anticipate that subsequent optimization of cytokines for mature Mk production and delayed NIC addition will greatly increase high-ploidy Mk production.

Human mammary progenitor cell fate decisions are products of interactions with combinatorial microenvironments

Energy Technology Data Exchange (ETDEWEB)

LaBarge, Mark A; Nelson, Celeste M; Villadsen, Rene; Fridriksdottir, Agla; Ruth, Jason R; Stampfer, Martha R; Petersen, Ole W; Bissell, Mina J

2008-09-19

In adult tissues, multi-potent progenitor cells are some of the most primitive members of the developmental hierarchies that maintain homeostasis. That progenitors and their more mature progeny share identical genomes, suggests that fate decisions are directed by interactions with extrinsic soluble factors, ECM, and other cells, as well as physical properties of the ECM. To understand regulation of fate decisions, therefore, would require a means of understanding carefully choreographed combinatorial interactions. Here we used microenvironment protein microarrays to functionally identify combinations of cell-extrinsic mammary gland proteins and ECM molecules that imposed specific cell fates on bipotent human mammary progenitor cells. Micropatterned cell culture surfaces were fabricated to distinguish between the instructive effects of cell-cell versus cell-ECM interactions, as well as constellations of signaling molecules; and these were used in conjunction with physiologically relevant 3 dimensional human breast cultures. Both immortalized and primary human breast progenitors were analyzed. We report on the functional ability of those proteins of the mammary gland that maintain quiescence, maintain the progenitor state, and guide progenitor differentiation towards myoepithelial and luminal lineages.

Single progenitor model for GW150914 and GW170104

Science.gov (United States)

D'Orazio, Daniel J.; Loeb, Abraham

2018-04-01

The merger of stellar-mass black holes (BHs) is not expected to generate detectable electromagnetic (EM) emission. However, the gravitational wave (GW) events GW150914 and GW170104, detected by the Laser Interferometer Gravitational Wave Observatory to be the result of merging, ˜60 M⊙ binary black holes (BBHs), each have claimed coincident gamma-ray emission. Motivated by the intriguing possibility of an EM counterpart to BBH mergers, we construct a model that can reproduce the observed EM and GW signals for GW150914- and GW170104-like events, from a single-star progenitor. Following Loeb [Astrophys. J. Lett. 819, L21 (2016), 10.3847/2041-8205/819/2/L21], we envision a massive, rapidly rotating star within which a rotating-bar instability fractures the core into two overdensities that fragment into clumps which merge to form BHs in a tight binary with arbitrary spin-orbit alignment. Once formed, the BBH inspirals due to gas and gravitational-wave drag until tidal forces trigger strong feeding of the BHs with the surrounding stellar-density gas about 10 sec before merger. The resulting giga-Eddington accretion peak launches a jet that breaks out of the progenitor star and drives a powerful outflow that clears the gas from the orbit of the binary within 1 sec, preserving the vacuum GW waveform in the Laser Interferometer Gravitational Wave Observatory band. The single-progenitor scenario predicts the existence of variability of the gamma-ray burst, modulated at the ˜0.2 sec chirping period of the BBH due to relativistic Doppler boost. The jet breakout should be accompanied by a low-luminosity supernova. Finally, because the BBHs of the single-progenitor model do not exist at large separations, they will not be detectable in the low-frequency gravitational-wave band of the Laser Interferometer Space Antenna. Hence, the single-progenitor BBHs will be unambiguously discernible from BBHs formed through alternate, double-progenitor evolution scenarios.

PROGENITORS OF RECOMBINING SUPERNOVA REMNANTS

Energy Technology Data Exchange (ETDEWEB)

Moriya, Takashi J., E-mail: takashi.moriya@ipmu.jp [Kavli Institute for the Physics and Mathematics of the Universe, Todai Institutes for Advanced Study, University of Tokyo, Kashiwanoha 5-1-5, Kashiwa, Chiba 277-8583 (Japan)

2012-05-01

Usual supernova remnants have either ionizing plasma or plasma in collisional ionization equilibrium, i.e., the ionization temperature is lower than or equal to the electron temperature. However, the existence of recombining supernova remnants, i.e., supernova remnants with ionization temperature higher than the electron temperature, has been recently confirmed. One suggested way to have recombining plasma in a supernova remnant is to have a dense circumstellar medium at the time of the supernova explosion. If the circumstellar medium is dense enough, collisional ionization equilibrium can be established in the early stage of the evolution of the supernova remnant and subsequent adiabatic cooling, which occurs after the shock wave gets out of the dense circumstellar medium, makes the electron temperature lower than the ionization temperature. We study the circumstellar medium around several supernova progenitors and show which supernova progenitors can have a circumstellar medium dense enough to establish collisional ionization equilibrium soon after the explosion. We find that the circumstellar medium around red supergiants (especially massive ones) and the circumstellar medium dense enough to make Type IIn supernovae can establish collisional ionization equilibrium soon after the explosion and can evolve to become recombining supernova remnants. Wolf-Rayet stars and white dwarfs have the possibility to be recombining supernova remnants but the fraction is expected to be very small. As the occurrence rate of the explosions of red supergiants is much higher than that of Type IIn supernovae, the major progenitors of recombining supernova remnants are likely to be red supergiants.

File list: Oth.Neu.20.AllAg.Fetal_neural_progenitor_cells [Chip-atlas[Archive

Lifescience Database Archive (English)

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File list: Oth.Neu.50.AllAg.Fetal_neural_progenitor_cells [Chip-atlas[Archive

Lifescience Database Archive (English)

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Development and application of methods and models for the calculation of spatially and temporally highly resolved emissions in Europe

International Nuclear Information System (INIS)

Thiruchittampalam, Balendra

2014-01-01

High spatial and temporal resolution models are essential for answering many questions of air quality management and climate modeling. High-resolution emission models are required to determine the concentration of pollutants using chemical transport models, and to quantify the impacts on health and environment and in particular to develop adequate countermeasures. The aim of this work is to develop methods for the calculation of spatially and temporally high-resolved emissions and to apply these exemplarily on a 1 km x 1 km and hourly resolution for the year 2008 in the EU-27 and EFTA countries. The derivation of methods for the spatial and temporal resolution of emissions with corresponding detailed equations is one of the major improvements that have been carried out in the course of this work. The improvement of the spatial distribution of emissions from the point source relevant sectors like energy supply, industry and waste management is achieved by considering sector specific diffuse emission shares. The progress of the spatial distribution of emissions from households is in particular the development of a fuel type weighted distribution over Europe. Another main focus is the development of the spatial distribution of road transport emissions. Due to the restricted access to traffic count data at the European level, methods have been established to provide reliable emissions on grid level for Europe. The progress in the spatial distribution of agricultural emissions is achieved by the consideration of diffuse shares similar to the other point source relevant sectors like energy supply or industry. In addition to the spatial distribution of the emissions the temporal resolution is a main focus of this work, since the state of knowledge of the temporal resolution of emissions in Europe is still rudimentary. Therefore, it was necessary to develop in particular time curves for the hourly resolution of emissions for the main sectors, namely electricity and heat

Spatially Resolved MR-Compatible Doppler Ultrasound: Proof of Concept for Triggering of Diagnostic Quality Cardiovascular MRI for Function and Flow Quantification at 3T.

Science.gov (United States)

Crowe, Lindsey Alexandra; Manasseh, Gibran; Chmielewski, Aneta; Hachulla, Anne-Lise; Speicher, Daniel; Greiser, Andreas; Muller, Hajo; de Perrot, Thomas; Vallee, Jean-Paul; Salomir, Rares

2018-02-01

We demonstrate the use of a magnetic-resonance (MR)-compatible ultrasound (US) imaging probe using spatially resolved Doppler for diagnostic quality cardiovascular MR imaging (MRI) as an initial step toward hybrid US/MR fetal imaging. A newly developed technology for a dedicated MR-compatible phased array ultrasound-imaging probe acquired pulsed color Doppler carotid images, which were converted in near-real time to a trigger signal for cardiac cine and flow quantification MRI. Ultrasound and MR data acquired simultaneously were interference free. Conventional electrocardiogram (ECG) and the proposed spatially resolved Doppler triggering were compared in 10 healthy volunteers. A synthetic "false-triggered" image was retrospectively processed using metric optimized gating (MOG). Images were scored by expert readers, and sharpness, cardiac function and aortic flow were quantified. Four-dimensional (4-D) flow (two volunteers) showed feasibility of Doppler triggering over a long acquisition time. Imaging modalities were compatible. US probe positioning was stable and comfortable. Image quality scores and quantified sharpness were statistically equal for Doppler- and ECG-triggering (p ). ECG-, Doppler-triggered, and MOG ejection fractions were equivalent (p ), with false-triggered values significantly lower (p 0.05). 4-D flow quantification gave consistent results between ECG and Doppler triggering. We report interference-free pulsed color Doppler ultrasound during MR data acquisition. Cardiovascular MRI of diagnostic quality was successfully obtained with pulsed color Doppler triggering. The hardware platform could further enable advanced free-breathing cardiac imaging. Doppler ultrasound triggering is applicable where ECG is compromised due to pathology or interference at higher magnetic fields, and where direct ECG is impossible, i.e., fetal imaging.

An in situ spatially resolved analytical technique to simultaneously probe gas phase reactions and temperature within the packed bed of a plug flow reactor.

Science.gov (United States)

Touitou, Jamal; Burch, Robbie; Hardacre, Christopher; McManus, Colin; Morgan, Kevin; Sá, Jacinto; Goguet, Alexandre

2013-05-21

This paper reports the detailed description and validation of a fully automated, computer controlled analytical method to spatially probe the gas composition and thermal characteristics in packed bed systems. As an exemplar, we have examined a heterogeneously catalysed gas phase reaction within the bed of a powdered oxide supported metal catalyst. The design of the gas sampling and the temperature recording systems are disclosed. A stationary capillary with holes drilled in its wall and a moveable reactor coupled with a mass spectrometer are used to enable sampling and analysis. This method has been designed to limit the invasiveness of the probe on the reactor by using the smallest combination of thermocouple and capillary which can be employed practically. An 80 μm (O.D.) thermocouple has been inserted in a 250 μm (O.D.) capillary. The thermocouple is aligned with the sampling holes to enable both the gas composition and temperature profiles to be simultaneously measured at equivalent spatially resolved positions. This analysis technique has been validated by studying CO oxidation over a 1% Pt/Al2O3 catalyst and the spatial resolution profiles of chemical species concentrations and temperature as a function of the axial position within the catalyst bed are reported.

PRMT5 is essential for the maintenance of chondrogenic progenitor cells in the limb bud.

Science.gov (United States)

Norrie, Jacqueline L; Li, Qiang; Co, Swanie; Huang, Bau-Lin; Ding, Ding; Uy, Jann C; Ji, Zhicheng; Mackem, Susan; Bedford, Mark T; Galli, Antonella; Ji, Hongkai; Vokes, Steven A

2016-12-15

During embryonic development, undifferentiated progenitor cells balance the generation of additional progenitor cells with differentiation. Within the developing limb, cartilage cells differentiate from mesodermal progenitors in an ordered process that results in the specification of the correct number of appropriately sized skeletal elements. The internal pathways by which these cells maintain an undifferentiated state while preserving their capacity to differentiate is unknown. Here, we report that the arginine methyltransferase PRMT5 has a crucial role in maintaining progenitor cells. Mouse embryonic buds lacking PRMT5 have severely truncated bones with wispy digits lacking joints. This novel phenotype is caused by widespread cell death that includes mesodermal progenitor cells that have begun to precociously differentiate into cartilage cells. We propose that PRMT5 maintains progenitor cells through its regulation of Bmp4 Intriguingly, adult and embryonic stem cells also require PRMT5 for maintaining pluripotency, suggesting that similar mechanisms might regulate lineage-restricted progenitor cells during organogenesis. © 2016. Published by The Company of Biologists Ltd.

File list: Oth.Neu.05.AllAg.Fetal_neural_progenitor_cells [Chip-atlas[Archive

Lifescience Database Archive (English)

Full Text Available Oth.Neu.05.AllAg.Fetal_neural_progenitor_cells hg19 TFs and others Neural Fetal neural progeni...tor cells SRX109477 http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/assembled/Oth.Neu.05.AllAg.Fetal_neural_progenitor_cells.bed ...

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Lifescience Database Archive (English)

Full Text Available ALL.Neu.50.AllAg.Fetal_neural_progenitor_cells hg19 All antigens Neural Fetal neural progeni...tor cells SRX109477,SRX109478 http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/assembled/ALL.Neu.50.AllAg.Fetal_neural_progenitor_cells.bed ...

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Lifescience Database Archive (English)

Full Text Available ALL.Neu.10.AllAg.Fetal_neural_progenitor_cells hg19 All antigens Neural Fetal neural progeni...tor cells SRX109477,SRX109478 http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/assembled/ALL.Neu.10.AllAg.Fetal_neural_progenitor_cells.bed ...

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Full Text Available InP.Adp.05.AllAg.Adipose_progenitor_cells mm9 Input control Adipocyte Adipose progeni...tor cells SRX127367,SRX127370 http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/assembled/InP.Adp.05.AllAg.Adipose_progenitor_cells.bed ...

File list: InP.Adp.20.AllAg.Adipose_progenitor_cells [Chip-atlas[Archive

Lifescience Database Archive (English)

Full Text Available InP.Adp.20.AllAg.Adipose_progenitor_cells mm9 Input control Adipocyte Adipose progeni...tor cells SRX127370,SRX127367 http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/assembled/InP.Adp.20.AllAg.Adipose_progenitor_cells.bed ...

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Lifescience Database Archive (English)

Full Text Available InP.Adp.50.AllAg.Adipose_progenitor_cells mm9 Input control Adipocyte Adipose progeni...tor cells SRX127370,SRX127367 http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/assembled/InP.Adp.50.AllAg.Adipose_progenitor_cells.bed ...

File list: ALL.Neu.05.AllAg.Fetal_neural_progenitor_cells [Chip-atlas[Archive

Lifescience Database Archive (English)

Full Text Available ALL.Neu.05.AllAg.Fetal_neural_progenitor_cells hg19 All antigens Neural Fetal neural... progenitor cells SRX109477,SRX109478 http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/assembled/ALL.Neu.05.AllAg.Fetal_neural_progenitor_cells.bed ...

The spatially resolved characterisation of Egyptian blue, Han blue and Han purple by photo-induced luminescence digital imaging.

Science.gov (United States)

Verri, G

2009-06-01

The photo-induced luminescence properties of Egyptian blue, Han blue and Han purple were investigated by means of near-infrared digital imaging. These pigments emit infrared radiation when excited in the visible range. The emission can be recorded by means of a modified commercial digital camera equipped with suitable glass filters. A variety of visible light sources were investigated to test their ability to excite luminescence in the pigments. Light-emitting diodes, which do not emit stray infrared radiation, proved an excellent source for the excitation of luminescence in all three compounds. In general, the use of visible radiation emitters with low emission in the infrared range allowed the presence of the pigments to be determined and their distribution to be spatially resolved. This qualitative imaging technique can be easily applied in situ for a rapid characterisation of materials. The results were compared to those for Egyptian green and for historical and modern blue pigments. Examples of the application of the technique on polychrome works of art are presented.

Time and spatially resolved LIF of OH in a plasma filament in atmospheric pressure He-H2O

International Nuclear Information System (INIS)

Verreycken, T; Van der Horst, R M; Baede, A H F M; Van Veldhuizen, E M; Bruggeman, P J

2012-01-01

The production of OH in a nanosecond pulsed filamentary discharge generated in pin-pin geometry in a He-H 2 O mixture is studied by time and spatially resolved laser-induced fluorescence. Apart from the OH density the gas temperature and the electron density are also measured. Depending on the applied voltage the discharge is in a different mode. The maximum electron densities in the low- (1.3 kV) and high-density (5 kV) modes are 2 × 10 21 m -3 and 7 × 10 22 m -3 , respectively. The gas temperature in both modes does not exceed 600 K. In the low-density mode the maximum OH density is at the centre of the discharge filament, while in the high-density mode the largest OH density is observed on the edge of the discharge. A chemical model is used to obtain an estimate of the absolute OH density. The chemical model also shows that charge exchange and dissociative recombination can explain the production of OH in the case of the high-density mode. (paper)

Intersections of lung progenitor cells, lung disease and lung cancer.

Science.gov (United States)

Kim, Carla F

2017-06-30

The use of stem cell biology approaches to study adult lung progenitor cells and lung cancer has brought a variety of new techniques to the field of lung biology and has elucidated new pathways that may be therapeutic targets in lung cancer. Recent results have begun to identify the ways in which different cell populations interact to regulate progenitor activity, and this has implications for the interventions that are possible in cancer and in a variety of lung diseases. Today's better understanding of the mechanisms that regulate lung progenitor cell self-renewal and differentiation, including understanding how multiple epigenetic factors affect lung injury repair, holds the promise for future better treatments for lung cancer and for optimising the response to therapy in lung cancer. Working between platforms in sophisticated organoid culture techniques, genetically engineered mouse models of injury and cancer, and human cell lines and specimens, lung progenitor cell studies can begin with basic biology, progress to translational research and finally lead to the beginnings of clinical trials. Copyright ©ERS 2017.

Intersections of lung progenitor cells, lung disease and lung cancer

Directory of Open Access Journals (Sweden)

Carla F. Kim

2017-06-01

Full Text Available The use of stem cell biology approaches to study adult lung progenitor cells and lung cancer has brought a variety of new techniques to the field of lung biology and has elucidated new pathways that may be therapeutic targets in lung cancer. Recent results have begun to identify the ways in which different cell populations interact to regulate progenitor activity, and this has implications for the interventions that are possible in cancer and in a variety of lung diseases. Today's better understanding of the mechanisms that regulate lung progenitor cell self-renewal and differentiation, including understanding how multiple epigenetic factors affect lung injury repair, holds the promise for future better treatments for lung cancer and for optimising the response to therapy in lung cancer. Working between platforms in sophisticated organoid culture techniques, genetically engineered mouse models of injury and cancer, and human cell lines and specimens, lung progenitor cell studies can begin with basic biology, progress to translational research and finally lead to the beginnings of clinical trials.

File list: InP.Neu.20.AllAg.Induced_neural_progenitors [Chip-atlas[Archive

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Full Text Available InP.Neu.50.AllAg.Induced_neural_progenitors mm9 Input control Neural Induced neural... progenitors SRX323563,SRX323574,SRX667380,SRX668238 http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/assembled/InP.Neu.50.AllAg.Induced_neural_progenitors.bed ...

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Full Text Available InP.Neu.10.AllAg.Induced_neural_progenitors mm9 Input control Neural Induced neural... progenitors SRX668238,SRX667380,SRX323563,SRX323574 http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/assembled/InP.Neu.10.AllAg.Induced_neural_progenitors.bed ...

File list: InP.Neu.05.AllAg.Induced_neural_progenitors [Chip-atlas[Archive

Lifescience Database Archive (English)

Full Text Available InP.Neu.05.AllAg.Induced_neural_progenitors mm9 Input control Neural Induced neural... progenitors SRX667380,SRX668238,SRX323563,SRX323574 http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/assembled/InP.Neu.05.AllAg.Induced_neural_progenitors.bed ...

A direct electron detector for time-resolved MeV electron microscopy

Energy Technology Data Exchange (ETDEWEB)

Vecchione, T.; Denes, P.; Jobe, R. K.; Johnson, I. J.; Joseph, J. M.; Li, R. K.; Perazzo, A.; Shen, X.; Wang, X. J.; Weathersby, S. P.; Yang, J.; Zhang, D.

2017-03-01

The introduction of direct electron detectors enabled the structural biology revolution of cryogenic electron microscopy. Direct electron detectors are now expected to have a similarly dramatic impact on time-resolved MeV electron microscopy, particularly by enabling both spatial and temporal jitter correction. Here we report on the commissioning of a direct electron detector for time-resolved MeV electron microscopy. The direct electron detector demonstrated MeV single electron sensitivity and is capable of recording megapixel images at 180 Hz. The detector has a 15-bit dynamic range, better than 30-μmμm spatial resolution and less than 20 analogue-to-digital converter count RMS pixel noise. The unique capabilities of the direct electron detector and the data analysis required to take advantage of these capabilities are presented. The technical challenges associated with generating and processing large amounts of data are also discussed.

Influence of hydrostatic pressure on dynamics and spatial distribution of protein partial molar volume: time-resolved surficial Kirkwood-Buff approach.

Science.gov (United States)

Yu, Isseki; Tasaki, Tomohiro; Nakada, Kyoko; Nagaoka, Masataka

2010-09-30

The influence of hydrostatic pressure on the partial molar volume (PMV) of the protein apomyoglobin (AMb) was investigated by all-atom molecular dynamics (MD) simulations. Using the time-resolved Kirkwood-Buff (KB) approach, the dynamic behavior of the PMV was identified. The simulated time average value of the PMV and its reduction by 3000 bar pressurization correlated with experimental data. In addition, with the aid of the surficial KB integral method, we obtained the spatial distributions of the components of PMV to elucidate the detailed mechanism of the PMV reduction. New R-dependent PMV profiles identified the regions that increase or decrease the PMV under the high pressure condition. The results indicate that besides the hydration in the vicinity of the protein surface, the outer space of the first hydration layer also significantly influences the total PMV change. These results provide a direct and detailed picture of pressure induced PMV reduction.

Pulpal progenitors and dentin repair.

Science.gov (United States)

Harichane, Y; Hirata, A; Dimitrova-Nakov, S; Granja, I; Goldberg, A; Kellermann, O; Poliard, A

2011-07-01

Mesenchymal stem cells are present in the dental pulp. They have been shown to contribute to dentin-like tissue formation in vitro and to participate in bone repair after a mandibular lesion. However, their capacity to contribute efficiently to reparative dentin formation after pulp lesion has never been explored. After pulp exposure, we have identified proliferative cells within 3 zones. In the crown, zone I is near the cavity, and zone II corresponds to the isthmus between the mesial and central pulp. In the root, zone III, near the apex, at a distance from the inflammatory site, contains mitotic stromal cells which may represent a source of progenitor cells. Stem-cell-based strategies are promising treatments for tissue injury in dentistry. Our experiments focused on (1) location of stem cells induced to leave their quiescent state early after pulp injury and (2) implantation of pulp progenitors, a substitute for classic endodontic treatments, paving the way for pulp stem-cell-based therapies.

Renal progenitor cells contribute to hyperplastic lesions of podocytopathies and crescentic glomerulonephritis.

Science.gov (United States)

Smeets, Bart; Angelotti, Maria Lucia; Rizzo, Paola; Dijkman, Henry; Lazzeri, Elena; Mooren, Fieke; Ballerini, Lara; Parente, Eliana; Sagrinati, Costanza; Mazzinghi, Benedetta; Ronconi, Elisa; Becherucci, Francesca; Benigni, Ariela; Steenbergen, Eric; Lasagni, Laura; Remuzzi, Giuseppe; Wetzels, Jack; Romagnani, Paola

2009-12-01

Glomerular injury can involve excessive proliferation of glomerular epithelial cells, resulting in crescent formation and obliteration of Bowman's space. The origin of these hyperplastic epithelial cells in different glomerular disorders is controversial. Renal progenitors localized to the inner surface of Bowman's capsule can regenerate podocytes, but whether dysregulated proliferation of these progenitors contributes to crescent formation is unknown. In this study, we used confocal microscopy, laser capture microdissection, and real-time quantitative reverse transcriptase-PCR to demonstrate that hypercellular lesions of different podocytopathies and crescentic glomerulonephritis consist of three distinct populations: CD133(+)CD24(+)podocalyxin (PDX)(-)nestin(-) renal progenitors, CD133(+)CD24(+)PDX(+)nestin(+) transitional cells, and CD133(-)CD24(-)PDX(+)nestin(+) differentiated podocytes. In addition, TGF-beta induced CD133(+)CD24(+) progenitors to produce extracellular matrix, and these were the only cells to express the proliferation marker Ki67. Taken together, these results suggest that glomerular hyperplastic lesions derive from the proliferation of renal progenitors at different stages of their differentiation toward mature podocytes, providing an explanation for the pathogenesis of hyperplastic lesions in podocytopathies and crescentic glomerulonephritis.

Regulated proliferation of primitive hematopoietic progenitor cells in long-term human marrow cultures

International Nuclear Information System (INIS)

Cashman, J.; Eaves, A.C.; Eaves, C.J.

1985-01-01

We have examined the cycling status of various classes of erythroid and granulopoietic progenitor populations maintained for many weeks in standard normal long-term human marrow cultures. These were initiated with a single inoculum of marrow aspirate and were routinely fed by weekly removal of half of the nonadherent cells and replacement of half of the growth medium. Progenitors of large erythroid colonies (more than eight erythroblast clusters) present in the nonadherent fraction and progenitors of small granulocyte/macrophage colonies (fewer than 500 cells) present in both the nonadherent and adherent fractions were found to be actively cycling at all times examined (28% to 63% kill following a 20-minute exposure to 20 microCi/mL of high specific activity 3 H-thymidine). In contrast, progenitors of large granulocyte/macrophage colonies (more than 500 cells) and progenitors of large erythroid colonies (more than eight erythroblast clusters), present in the adherent layer, consistently alternated between a quiescent state at the time of each weekly medium change and a proliferating state two to three days later (0% to 13% kill and 21% to 49% kill, respectively). Additional experiments revealed that the activation of primitive progenitors in the adherent layer was not dependent on the addition of fresh glutamine or hydrocortisone, nor on the physical manipulations involved in changing the growth medium. These studies provide the first direct evidence that normal long-term human marrow cultures support the continued turnover of a variety of early hematopoietic progenitor cell types. Further, they indicate that the proliferative activity of the most primitive of these progenitors is regulated by stage-specific cell-cell interactions that are subject to manipulation

Spatially and temporally resolved EUV emissions from SATURN z-pinches

International Nuclear Information System (INIS)

Nash, T.J.; Breeze, S.; Mock, R.; Jobe, D.

1995-01-01

EUV emissions can be used to measure several z-pinch parameters. The authors have measured implosion velocity from Doppler splitting of lines and estimated electron temperature during run-in from the mean ionization state of line emissions. In an argon pinch they measure an electron temperature of 100 eV before stagnation. To date Doppler split lines have measured implosion velocities less than 40 cm/microsecond. They are presently attempting to measure magnetic field or load current from Zeeman splitting and it may be possible to measure electron density from a Stark-broadened line. Opacity and ion thermal broadening may also contribute to line width information. The spectrometer utilizes a variable line space grating to give a flat focal field. Spectral resolution with a 60 micron detector resolution is up to 3,000 and generally increases with wavelength. This is sufficient to detect several plasma line broadening mechanisms. The spectrometer may detect lines above 100 angstrom and below 1,400 angstrom. Spectral range across a microchannel plate stripline detector decreases with increasing wavelength setting. The authors may gate two striplines with 1 to 12 nsec gates at any time during the pinch discharge. Each stripline spatially images the pinch diameter perpendicular to the direction of dispersion. Spatial resolution in the pinch diameter is 1 mm. Spatial acquisition along the z axis is also 1 mm. Data are presented from argon, krypton, and aluminum z-pinch discharges on the SATURN accelerator

Spatially resolved spectrophotometry of Comet P/Stephan-Oterma

Science.gov (United States)

Cochran, A. L.; Barker, E. S.

1985-01-01

Observations of Comet P/Stephan-Oterma were made with an Intensified Dissector Scanner spectrograph on the McDonald Observatory 2.7-m telescope during the period from July 1980 to February 1981. These spectra cover a range of heliocentric distances from 2.3 AU preperihelion to 1.8 AU postperihelion. A small aperture was used to map the spatial distributions of the gases in the coma. Column densities of the observed cometary emissions (CN, C3, CH, and C2) were calculated, and it is shown that Stephan-Oterma appeared nearly spherically symmetric. These date are used by Cochran (1985) to constrain chemical models of Stephan-Oterma.

Fingerprinting ancient gold by measuring Pt with spatially resolved high energy Sy-XRF

International Nuclear Information System (INIS)

Guerra, M.F.; Calligaro, T.; Radtke, M.; Reiche, I.; Riesemeier, H.

2005-01-01

Trace elements of ancient gold such as Pt, give fundamental information on the circulation of the metal in the past. In the case of objects from the cultural heritage, the determination of trace elements requires non-destructive point analysis in general. These conditions and the need of good detection limits restrain the number of applicable analytical techniques. After the development of a PIXE set-up with a selective Cu or Zn filter of 75 μm and of a PIXE-XRF set-up using a primary target of As, we tested the possibilities of spatially resolved Sy-XRF to determine Pt in gold alloys. With a Zn filter, PIXE showed a detection limit of 1000 ppm in gold while PIXE-XRF lowers this detection limit down to 80 ppm. This last value being constrained by the resonant Raman effect produced on gold. In order to improve the detection limit of Pt keeping the non-destructiveness and access to point analysis, we developed an analytical protocol for XRF with synchrotron radiation at BESSY II, using the BAMline set-up. The L-lines of Pt were excited by a beam of energy above and below 11.564 keV and measured using a Si(Li) detector with a 50 μm Cu filter. A μ-beam of 100-250 μm 2 was used according to the size of the sample. The determination of the Pt content in the samples was carried out by Monte-Carlo simulation and subtraction of Au and Pt spectra obtained on pure standards. The limit of detection for Pt of 20 ppm was determined by using certified standards. The detection limits of a small set of other characteristic elements of gold were also measured using an incident energy of 33 keV

SDSS-IV MaNGA - the spatially resolved transition from star formation to quiescence

Science.gov (United States)

Belfiore, Francesco; Maiolino, Roberto; Maraston, Claudia; Emsellem, Eric; Bershady, Matthew A.; Masters, Karen L.; Bizyaev, Dmitry; Boquien, Médéric; Brownstein, Joel R.; Bundy, Kevin; Diamond-Stanic, Aleksandar M.; Drory, Niv; Heckman, Timothy M.; Law, David R.; Malanushenko, Olena; Oravetz, Audrey; Pan, Kaike; Roman-Lopes, Alexandre; Thomas, Daniel; Weijmans, Anne-Marie; Westfall, Kyle B.; Yan, Renbin

2017-04-01

Using spatially resolved spectroscopy from SDSS-IV MaNGA we have demonstrated that low ionization emission-line regions (LIERs) in local galaxies result from photoionization by hot evolved stars, not active galactic nuclei, hence tracing galactic region hosting old stellar population where, despite the presence of ionized gas, star formation is no longer occurring. LIERs are ubiquitous in both quiescent galaxies and in the central regions of galaxies where star formation takes place at larger radii. We refer to these two classes of galaxies as extended LIER (eLIER) and central LIER (cLIER) galaxies, respectively. cLIERs are late-type galaxies primarily spread across the green valley, in the transition region between the star formation main sequence and quiescent galaxies. These galaxies display regular disc rotation in both stars and gas, although featuring a higher central stellar velocity dispersion than star-forming galaxies of the same mass. cLIERs are consistent with being slowly quenched inside-out; the transformation is associated with massive bulges, pointing towards the importance of bulge growth via secular evolution. eLIERs are morphologically early types and are indistinguishable from passive galaxies devoid of line emission in terms of their stellar populations, morphology and central stellar velocity dispersion. Ionized gas in eLIERs shows both disturbed and disc-like kinematics. When a large-scale flow/rotation is observed in the gas, it is often misaligned relative to the stellar component. These features indicate that eLIERs are passive galaxies harbouring a residual cold gas component, acquired mostly via external accretion. Importantly, quiescent galaxies devoid of line emission reside in denser environments and have significantly higher satellite fraction than eLIERs. Environmental effects thus represent the likely cause for the existence of line-less galaxies on the red sequence.

File list: InP.Neu.20.AllAg.Neural_progenitor_cells [Chip-atlas[Archive

Lifescience Database Archive (English)

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File list: InP.Neu.10.AllAg.Neural_progenitor_cells [Chip-atlas[Archive

Lifescience Database Archive (English)

Full Text Available InP.Neu.10.AllAg.Neural_progenitor_cells mm9 Input control Neural Neural progenitor... cells SRX109476,SRX315272,SRX315273,SRX109475,SRX667382,SRX668239 http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/assembled/InP.Neu.10.AllAg.Neural_progenitor_cells.bed ...

File list: InP.Neu.05.AllAg.Neural_progenitor_cells [Chip-atlas[Archive

Lifescience Database Archive (English)

Full Text Available InP.Neu.05.AllAg.Neural_progenitor_cells mm9 Input control Neural Neural progenitor... cells SRX109476,SRX667382,SRX109475,SRX315272,SRX315273,SRX668239 http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/assembled/InP.Neu.05.AllAg.Neural_progenitor_cells.bed ...

Transplantation of Expanded Fetal Intestinal Progenitors Contributes to Colon Regeneration after Injury

DEFF Research Database (Denmark)

Fordham, Robert P; Yui, Shiro; Hannan, Nicholas R F

2013-01-01

Regeneration and homeostasis in the adult intestinal epithelium is driven by proliferative resident stem cells, whose functional properties during organismal development are largely unknown. Here, we show that human and mouse fetal intestine contains proliferative, immature progenitors, which can...... be expanded in vitro as Fetal Enterospheres (FEnS). A highly similar progenitor population can be established during intestinal differentiation of human induced pluripotent stem cells. Established cultures of mouse fetal intestinal progenitors express lower levels of Lgr5 than mature progenitors and propagate...... in the presence of the Wnt antagonist Dkk1, and new cultures can be induced to form mature intestinal organoids by exposure to Wnt3a. Following transplantation in a colonic injury model, FEnS contribute to regeneration of colonic epithelium by forming epithelial crypt-like structures expressing region...

Effects of hematopoietic growth factors on purified bone marrow progenitor cells

NARCIS (Netherlands)

F.J. Bot (Freek)

1992-01-01

textabstractWe have used highly enriched hematopoietic progenitor cells and in-vitro culture to examine the following questions: 1. The effects of recombinant lL-3 and GM-CSF on proliferation and differentiation of enriched hematopoietic progenitor cells have not been clearly defined: - how do IL~3

Measurement of fluorophore concentrations and fluorescence quantum yield in tissue-simulating phantoms using three diffusion models of steady-state spatially resolved fluorescence

Energy Technology Data Exchange (ETDEWEB)

Diamond, Kevin R; Farrell, Thomas J; Patterson, Michael S [Department of Medical Physics, Juravinski Cancer Centre and McMaster University, 699 Concession Street, Hamilton, Ontario L8V 5C2 (Canada)

2003-12-21

Steady-state diffusion theory models of fluorescence in tissue have been investigated for recovering fluorophore concentrations and fluorescence quantum yield. Spatially resolved fluorescence, excitation and emission reflectance were calculated by diffusion theory and Monte Carlo simulations, and measured using a multi-fibre probe on tissue-simulating phantoms containing either aluminium phthalocyanine tetrasulfonate (AlPcS{sub 4}), Photofrin or meso-tetra-(4-sulfonatophenyl)-porphine dihydrochloride (TPPS{sub 4}). The accuracy of the fluorophore concentration and fluorescence quantum yield recovered by three different models of spatially resolved fluorescence were compared. The models were based on: (a) weighted difference of the excitation and emission reflectance, (b) fluorescence due to a point excitation source or (c) fluorescence due to a pencil beam excitation source. When literature values for the fluorescence quantum yield were used for each of the fluorophores, the fluorophore absorption coefficient (and hence concentration) at the excitation wavelengthwas recovered with a root-mean-square accuracy of 11.4% using the point source model of fluorescence and 8.0% using the more complicated pencil beam excitation model. The accuracy was calculated over a broad range of optical properties and fluorophore concentrations. The weighted difference of reflectance model performed poorly, with a root-mean-square error in concentration of about 50%. Monte Carlo simulations suggest that there are some situations where the weighted difference of reflectance is as accurate as the other two models, although this was not confirmed experimentally. Estimates of the fluorescence quantum yield in multiple scattering media were also made by determining independently from the fitted absorption spectrum and applying the various diffusion theory models. The fluorescence quantum yields for AlPcS{sub 4} and TPPS{sub 4} were calculated to be 0.59 {+-} 0.03 and 0.121 {+-} 0

Measurement of fluorophore concentrations and fluorescence quantum yield in tissue-simulating phantoms using three diffusion models of steady-state spatially resolved fluorescence

International Nuclear Information System (INIS)

Diamond, Kevin R; Farrell, Thomas J; Patterson, Michael S

2003-01-01

Steady-state diffusion theory models of fluorescence in tissue have been investigated for recovering fluorophore concentrations and fluorescence quantum yield. Spatially resolved fluorescence, excitation and emission reflectance were calculated by diffusion theory and Monte Carlo simulations, and measured using a multi-fibre probe on tissue-simulating phantoms containing either aluminium phthalocyanine tetrasulfonate (AlPcS 4 ), Photofrin or meso-tetra-(4-sulfonatophenyl)-porphine dihydrochloride (TPPS 4 ). The accuracy of the fluorophore concentration and fluorescence quantum yield recovered by three different models of spatially resolved fluorescence were compared. The models were based on: (a) weighted difference of the excitation and emission reflectance, (b) fluorescence due to a point excitation source or (c) fluorescence due to a pencil beam excitation source. When literature values for the fluorescence quantum yield were used for each of the fluorophores, the fluorophore absorption coefficient (and hence concentration) at the excitation wavelengthwas recovered with a root-mean-square accuracy of 11.4% using the point source model of fluorescence and 8.0% using the more complicated pencil beam excitation model. The accuracy was calculated over a broad range of optical properties and fluorophore concentrations. The weighted difference of reflectance model performed poorly, with a root-mean-square error in concentration of about 50%. Monte Carlo simulations suggest that there are some situations where the weighted difference of reflectance is as accurate as the other two models, although this was not confirmed experimentally. Estimates of the fluorescence quantum yield in multiple scattering media were also made by determining independently from the fitted absorption spectrum and applying the various diffusion theory models. The fluorescence quantum yields for AlPcS 4 and TPPS 4 were calculated to be 0.59 ± 0.03 and 0.121 ± 0.001 respectively using the point

Can pancreatic duct-derived progenitors be a source of islet regeneration?

International Nuclear Information System (INIS)

Xia, Bing; Zhan, Xiao-Rong; Yi, Ran; Yang, Baofeng

2009-01-01

The regenerative process of the pancreas is of interest because the main pathogenesis of diabetes mellitus is an inadequate number of insulin-producing β-cells. The functional mass of β-cells is decreased in type 1 diabetes, so replacing missing β-cells or triggering their regeneration may allow for improved type 1 diabetes treatment. Therefore, expansion of the β-cell mass from endogenous sources, either in vivo or in vitro, represents an area of increasing interest. The mechanism of islet regeneration remains poorly understood, but the identification of islet progenitor sources is critical for understanding β-cell regeneration. One potential source is the islet proper, via the dedifferentiation, proliferation, and redifferentiation of facultative progenitors residing within the islet. Neogenesis, or that the new pancreatic islets can derive from progenitor cells present within the ducts has been reported, but the existence and identity of the progenitor cells have been debated. In this review, we focus on pancreatic ductal cells, which are islet progenitors capable of differentiating into islet β-cells. Islet neogenesis, seen as budding of hormone-positive cells from the ductal epithelium, is considered to be one mechanism for normal islet growth after birth and in regeneration, and has suggested the presence of pancreatic stem cells. Numerous results support the neogenesis hypothesis, the evidence for the hypothesis in the adult comes primarily from morphological studies that have in common the production of damage to all or part of the pancreas, with consequent inflammation and repair. Although numerous studies support a ductal origin for new islets after birth, lineage-tracing experiments are considered the 'gold standard' of proof. Lineage-tracing experiments show that pancreatic duct cells act as progenitors, giving rise to new islets after birth and after injury. The identification of differentiated pancreatic ductal cells as an in vivo progenitor for

Can pancreatic duct-derived progenitors be a source of islet regeneration?

Energy Technology Data Exchange (ETDEWEB)

Xia, Bing [Department of Endocrinology, First Hospital of Harbin Medical University, Harbin, Hei Long Jiang Province 150001 (China); Zhan, Xiao-Rong, E-mail: xiaorongzhan@sina.com [Department of Endocrinology, First Hospital of Harbin Medical University, Harbin, Hei Long Jiang Province 150001 (China); Yi, Ran [Department of Endocrinology, First Hospital of Harbin Medical University, Harbin, Hei Long Jiang Province 150001 (China); Yang, Baofeng [Department of Pharmacology, State Key Laboratory of Biomedicine and Pharmacology, Harbin Medical University, Harbin, Hei Long Jiang Province 150001 (China)

2009-06-12

The regenerative process of the pancreas is of interest because the main pathogenesis of diabetes mellitus is an inadequate number of insulin-producing {beta}-cells. The functional mass of {beta}-cells is decreased in type 1 diabetes, so replacing missing {beta}-cells or triggering their regeneration may allow for improved type 1 diabetes treatment. Therefore, expansion of the {beta}-cell mass from endogenous sources, either in vivo or in vitro, represents an area of increasing interest. The mechanism of islet regeneration remains poorly understood, but the identification of islet progenitor sources is critical for understanding {beta}-cell regeneration. One potential source is the islet proper, via the dedifferentiation, proliferation, and redifferentiation of facultative progenitors residing within the islet. Neogenesis, or that the new pancreatic islets can derive from progenitor cells present within the ducts has been reported, but the existence and identity of the progenitor cells have been debated. In this review, we focus on pancreatic ductal cells, which are islet progenitors capable of differentiating into islet {beta}-cells. Islet neogenesis, seen as budding of hormone-positive cells from the ductal epithelium, is considered to be one mechanism for normal islet growth after birth and in regeneration, and has suggested the presence of pancreatic stem cells. Numerous results support the neogenesis hypothesis, the evidence for the hypothesis in the adult comes primarily from morphological studies that have in common the production of damage to all or part of the pancreas, with consequent inflammation and repair. Although numerous studies support a ductal origin for new islets after birth, lineage-tracing experiments are considered the 'gold standard' of proof. Lineage-tracing experiments show that pancreatic duct cells act as progenitors, giving rise to new islets after birth and after injury. The identification of differentiated pancreatic ductal

The Type IIb Supernova 2013df and its Cool Supergiant Progenitor

Science.gov (United States)

VanDyk, Schuyler D.; Zeng, Weikang; Fox, Ori D.; Cenko, S. Bradley; Clubb, Kelsey I.; Filippenko, Alexei; Foley, Ryan J.; Miller, Adam A.; Smith, Nathan; Kelly, Patrick L.;

The type IIb supernova 2013df and its cool supergiant progenitor

Energy Technology Data Exchange (ETDEWEB)

Van Dyk, Schuyler D. [Spitzer Science Center/Caltech, Mail Code 220-6, Pasadena, CA 91125 (United States); Zheng, WeiKang; Fox, Ori D.; Clubb, Kelsey I.; Filippenko, Alexei V.; Kelly, Patrick L. [Department of Astronomy, University of California, Berkeley, CA 94720-3411 (United States); Cenko, S. Bradley [Astrophysics Science Division, NASA Goddard Space Flight Center, Mail Code 661, Greenbelt, MD 20771 (United States); Foley, Ryan J. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Miller, Adam A. [Jet Propulsion Laboratory, MS 169-506, Pasadena, CA 91109 (United States); Smith, Nathan [Steward Observatory, University of Arizona, Tucson, AZ 85720 (United States); Lee, William H. [Instituto de Astronomía, Universidad Nacional Autónoma de México, Apdo. Postal 70-264, Cd. Universitaria, México DF 04510 (Mexico); Ben-Ami, Sagi; Gal-Yam, Avishay, E-mail: vandyk@ipac.caltech.edu [Benoziyo Center for Astrophysics, The Weizmann Institute of Science, Rehovot 76100 (Israel)

2014-02-01

We have obtained early-time photometry and spectroscopy of supernova (SN) 2013df in NGC 4414. The SN is clearly of Type IIb, with notable similarities to SN 1993J. From its luminosity at secondary maximum light, it appears that less {sup 56}Ni (≲ 0.06 M {sub ☉}) was synthesized in the SN 2013df explosion than was the case for the SNe IIb 1993J, 2008ax, and 2011dh. Based on a comparison of the light curves, the SN 2013df progenitor must have been more extended in radius prior to explosion than the progenitor of SN 1993J. The total extinction for SN 2013df is estimated to be A{sub V} = 0.30 mag. The metallicity at the SN location is likely to be solar. We have conducted Hubble Space Telescope (HST) Target of Opportunity observations of the SN with the Wide Field Camera 3, and from a precise comparison of these new observations to archival HST observations of the host galaxy obtained 14 yr prior to explosion, we have identified the progenitor of SN 2013df to be a yellow supergiant, somewhat hotter than a red supergiant progenitor for a normal Type II-Plateau SN. From its observed spectral energy distribution, assuming that the light is dominated by one star, the progenitor had effective temperature T {sub eff} = 4250 ± 100 K and a bolometric luminosity L {sub bol} = 10{sup 4.94±0.06} L {sub ☉}. This leads to an effective radius R {sub eff} = 545 ± 65 R {sub ☉}. The star likely had an initial mass in the range of 13-17 M {sub ☉}; however, if it was a member of an interacting binary system, detailed modeling of the system is required to estimate this mass more accurately. The progenitor star of SN 2013df appears to have been relatively similar to the progenitor of SN 1993J.

Observational Investigations of the Progenitors of Supernovae

Science.gov (United States)

Lyman, J. D.

2014-03-01

Supernovae (SNe) are the spectacular deaths of stars and have shaped the universe we see today. Their far-reaching influence affects the chemical and dynamical evolution of galaxies, star formation, neutron star and black hole formation, and they are largely responsible for most of the heavy elements that make up the universe, including around 90 per cent of the reader. They also provide laboratories of nuclear and particle physics far beyond what we can construct on Earth and act as probes of extreme density and energy. This thesis presents new research into understanding the nature of the progenitor systems of various types of SNe, as well as presenting results that will allow their study to be more productive in the future, through use of automated pipelines and methods to increase the science value of discovered SNe. An environmental study of two peculiar types of transients ('Calcium-rich' and '2002cx-like'), which may not be true SNe, reveals extremely different ages of the exploding systems that will constrain the current theoretical effort into discovering the progenitor systems. The GRB-SN 120422A/2012bz is investigated and found to be an extremely luminous and energetic SN, even amongst the infamously bright GRB-SNe. A method is presented that allows an accurate reconstruction of the bolometric light curve of a core-collapse SN, which relies on only two optical filter observations - this will hugely reduce the observational cost of constructing bolometric light curves, a tool of great importance when hoping to constrain the nature of a SN explosion and hence its progenitor. Finally, this method is utilised to construct the largest bolometric CCSN bolometric light curve sample to date, and these are analytically modelled to reveal population statistics of the explosions, thus informing on the nature of the progenitors.

Characterization of stem/progenitor cell cycle using murine circumvallate papilla taste bud organoid.

Science.gov (United States)

Aihara, Eitaro; Mahe, Maxime M; Schumacher, Michael A; Matthis, Andrea L; Feng, Rui; Ren, Wenwen; Noah, Taeko K; Matsu-ura, Toru; Moore, Sean R; Hong, Christian I; Zavros, Yana; Herness, Scott; Shroyer, Noah F; Iwatsuki, Ken; Jiang, Peihua; Helmrath, Michael A; Montrose, Marshall H

2015-11-24

Leucine-rich repeat-containing G-protein coupled receptor 5-expressing (Lgr5(+)) cells have been identified as stem/progenitor cells in the circumvallate papillae, and single cultured Lgr5(+) cells give rise to taste cells. Here we use circumvallate papilla tissue to establish a three-dimensional culture system (taste bud organoids) that develops phenotypic characteristics similar to native tissue, including a multilayered epithelium containing stem/progenitor in the outer layers and taste cells in the inner layers. Furthermore, characterization of the cell cycle of the taste bud progenitor niche reveals striking dynamics of taste bud development and regeneration. Using this taste bud organoid culture system and FUCCI2 transgenic mice, we identify the stem/progenitor cells have at least 5 distinct cell cycle populations by tracking within 24-hour synchronized oscillations of proliferation. Additionally, we demonstrate that stem/progenitor cells have motility to form taste bud organoids. Taste bud organoids provides a system for elucidating mechanisms of taste signaling, disease modeling, and taste tissue regeneration.

Endothelial Progenitor Cells as Shuttle of Anticancer Agents.

Science.gov (United States)

Laurenzana, Anna; Margheri, Francesca; Chillà, Anastasia; Biagioni, Alessio; Margheri, Giancarlo; Calorini, Lido; Fibbi, Gabriella; Del Rosso, Mario

2016-10-01

Cell therapies are treatments in which stem or progenitor cells are stimulated to differentiate into specialized cells able to home to and repair damaged tissues. After their discovery, endothelial progenitor cells (EPCs) stimulated worldwide interest as possible vehicles to perform autologous cell therapy of tumors. Taking into account the tumor-homing properties of EPCs, two different approaches to control cancer progression have been pursued by combining cell-based therapy with gene therapy or with nanomedicine. The first approach is based on the possibility of engineering EPCs to express different transgenes, and the second is based on the capacity of EPCs to take up nanomaterials. Here we review the most important progress covering the following issues: the characterization of bona fide endothelial progenitor cells, their role in tumor vascularization and metastasis, and preclinical data about their use in cell-based tumor therapy, considering antiangiogenic, suicide, immune-stimulating, and oncolytic virus gene therapy. The mixed approach of EPC cell therapy and nanomedicine is discussed in terms of plasmonic-dependent thermoablation and molecular imaging.

Bone marrow niche-inspired, multi-phase expansion of megakaryocytic progenitors with high polyploidization potential

Science.gov (United States)

Panuganti, Swapna; Papoutsakis, Eleftherios T.; Miller, William M.

2010-01-01

Background Megakaryopoiesis encompasses hematopoietic stem and progenitor cell (HSPC) commitment to the megakaryocytic cell (Mk) lineage, expansion of Mk progenitors and mature Mks, polyploidization, and platelet release. pH and pO2 increase from the endosteum to sinuses, and different cytokines are important for various stages of differentiation. We hypothesized that mimicking the changing conditions during Mk differentiation in the bone marrow would facilitate expansion of progenitors that could generate many high-ploidy Mks. Methods CD34+ HSPCs were cultured at pH 7.2 and 5% O2 with stem cell factor (SCF), thrombopoietin (Tpo), and all combinations of Interleukin (IL)-3, IL-6, IL-11, and Flt-3 ligand to promote Mk progenitor expansion. Cells cultured with selected cytokines were shifted to pH 7.4 and 20% O2 to generate mature Mks, and treated with nicotinamide to enhance polyploidization. Results Using Tpo+SCF+IL-3+IL-11, we obtained 3.5 CD34+CD41+ Mk progenitors per input HSPC, while increasing purity from 1% to 17%. Cytokine cocktails with IL-3 yielded more progenitors and mature Mks, although the purities were lower. Mk production was much greater at higher pH and pO2. Although fewer progenitors were present, shifting to 20% O2/pH 7.4 at day 5 (versus days 7 or 9) yielded the greatest mature Mk production, 14 per input HSPC. Nicotinamide more than doubled the percentage of high-ploidy Mks to 40%. Discussion We obtained extensive Mk progenitor expansion, while ensuring that the progenitors could produce high-ploidy Mks. We anticipate that subsequent optimization of cytokines for mature Mk production and delayed nicotinamide addition will greatly increase high-ploidy Mk production. PMID:20482285

Spatially resolved SO2 flux emissions from Mt Etna

Science.gov (United States)

Bitetto, M.; Delle Donne, D.; Tamburello, G.; Battaglia, A.; Coltelli, M.; Patanè, D.; Prestifilippo, M.; Sciotto, M.; Aiuppa, A.

2016-01-01

Abstract We report on a systematic record of SO2 flux emissions from individual vents of Etna volcano (Sicily), which we obtained using a permanent UV camera network. Observations were carried out in summer 2014, a period encompassing two eruptive episodes of the New South East Crater (NSEC) and a fissure‐fed eruption in the upper Valle del Bove. We demonstrate that our vent‐resolved SO2 flux time series allow capturing shifts in activity from one vent to another and contribute to our understanding of Etna's shallow plumbing system structure. We find that the fissure eruption contributed ~50,000 t of SO2 or ~30% of the SO2 emitted by the volcano during the 5 July to 10 August eruptive interval. Activity from this eruptive vent gradually vanished on 10 August, marking a switch of degassing toward the NSEC. Onset of degassing at the NSEC was a precursory to explosive paroxysmal activity on 11–15 August. PMID:27773952

Violencia Filio Parental: Comparando lo que informan los adolescentes y sus progenitores

OpenAIRE

Calvete, Esther; Orue, Izaskun; González-Cabrera, Joaquín

2017-01-01

El objetivo principal del presente estudio fue examinar la consistencia de los informes de progenitores e hijos a la hora de informar sobre la violencia filio-parental en una muestra comunitaria. Como objetivo secundario, se exploraron las propiedades psicométricas de la versión para progenitores del Cuestionario de Violencia Filio-Parental (Calvete, Gámez-Guadix et al., 2013). Participaron en el estudio un total de 880 adolescentes (51.70% chicas, entre 13 y 19 años) y sus progenitores (76....

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Aging-associated inflammation promotes selection for adaptive oncogenic events in B cell progenitors.

Science.gov (United States)

Henry, Curtis J; Casás-Selves, Matias; Kim, Jihye; Zaberezhnyy, Vadym; Aghili, Leila; Daniel, Ashley E; Jimenez, Linda; Azam, Tania; McNamee, Eoin N; Clambey, Eric T; Klawitter, Jelena; Serkova, Natalie J; Tan, Aik Choon; Dinarello, Charles A; DeGregori, James

2015-12-01

The incidence of cancer is higher in the elderly; however, many of the underlying mechanisms for this association remain unexplored. Here, we have shown that B cell progenitors in old mice exhibit marked signaling, gene expression, and metabolic defects. Moreover, B cell progenitors that developed from hematopoietic stem cells (HSCs) transferred from young mice into aged animals exhibited similar fitness defects. We further demonstrated that ectopic expression of the oncogenes BCR-ABL, NRAS(V12), or Myc restored B cell progenitor fitness, leading to selection for oncogenically initiated cells and leukemogenesis specifically in the context of an aged hematopoietic system. Aging was associated with increased inflammation in the BM microenvironment, and induction of inflammation in young mice phenocopied aging-associated B lymphopoiesis. Conversely, a reduction of inflammation in aged mice via transgenic expression of α-1-antitrypsin or IL-37 preserved the function of B cell progenitors and prevented NRAS(V12)-mediated oncogenesis. We conclude that chronic inflammatory microenvironments in old age lead to reductions in the fitness of B cell progenitor populations. This reduced progenitor pool fitness engenders selection for cells harboring oncogenic mutations, in part due to their ability to correct aging-associated functional defects. Thus, modulation of inflammation--a common feature of aging--has the potential to limit aging-associated oncogenesis.

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Characteristics of meniscus progenitor cells migrated from injured meniscus.

Science.gov (United States)

Seol, Dongrim; Zhou, Cheng; Brouillette, Marc J; Song, Ino; Yu, Yin; Choe, Hyeong Hun; Lehman, Abigail D; Jang, Kee W; Fredericks, Douglas C; Laughlin, Barbara J; Martin, James A

2017-09-01

Serious meniscus injuries seldom heal and increase the risk for knee osteoarthritis; thus, there is a need to develop new reparative therapies. In that regard, stimulating tissue regeneration by autologous stem/progenitor cells has emerged as a promising new strategy. We showed previously that migratory chondrogenic progenitor cells (CPCs) were recruited to injured cartilage, where they showed a capability in situ tissue repair. Here, we tested the hypothesis that the meniscus contains a similar population of regenerative cells. Explant studies revealed that migrating cells were mainly confined to the red zone in normal menisci: However, these cells were capable of repopulating defects made in the white zone. In vivo, migrating cell numbers increased dramatically in damaged meniscus. Relative to non-migrating meniscus cells, migrating cells were more clonogenic, overexpressed progenitor cell markers, and included a larger side population. Gene expression profiling showed that the migrating population was more similar to CPCs than other meniscus cells. Finally, migrating cells equaled CPCs in chondrogenic potential, indicating a capacity for repair of the cartilaginous white zone of the meniscus. These findings demonstrate that, much as in articular cartilage, injuries to the meniscus mobilize an intrinsic progenitor cell population with strong reparative potential. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:1966-1972, 2017. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

A radially accessible tubular in situ X-ray cell for spatially resolved operando scattering and spectroscopic studies of electrochemical energy storage devices

Energy Technology Data Exchange (ETDEWEB)

Liu, Hao; Allan, Phoebe K.; Borkiewicz, Olaf J.; Kurtz, Charles; Grey, Clare P.; Chapman, Karena W.; Chupas, Peter J.

2016-09-16

A tubularoperandoelectrochemical cell has been developed to allow spatially resolved X-ray scattering and spectroscopic measurements of individual cell components, or regions thereof, during device operation. These measurements are enabled by the tubular cell geometry, wherein the X-ray-transparent tube walls allow radial access for the incident and scattered/transmitted X-ray beam; by probing different depths within the electrode stack, the transformation of different components or regions can be resolved. The cell is compatible with a variety of synchrotron-based scattering, absorption and imaging methodologies. The reliability of the electrochemical cell and the quality of the resulting X-ray scattering and spectroscopic data are demonstrated for two types of energy storage: the evolution of the distribution of the state of charge of an Li-ion battery electrode during cycling is documented using X-ray powder diffraction, and the redistribution of ions between two porous carbon electrodes in an electrochemical double-layer capacitor is documented using X-ray absorption near-edge spectroscopy.

Progenitors of white dwarfs

International Nuclear Information System (INIS)

Drilling, J.S.; Schoenberner, D.

1985-01-01

Direct observational evidence is presented which indicates that the immediate progenitors of white dwarfs are the central stars of planetary nebulae (approximately 70%), other post-AGB objects (approximately 30%), and post-HB objects not massive enough to climb the AGB (approximately 0.3%). The combined birth rate for these objects is in satisfactory agreement with the death rate of main-sequence stars and the birth rate of white dwarfs

Biochemistry and biology: heart-to-heart to investigate cardiac progenitor cells.

Science.gov (United States)

Chimenti, Isotta; Forte, Elvira; Angelini, Francesco; Messina, Elisa; Giacomello, Alessandro

2013-02-01

Cardiac regenerative medicine is a rapidly evolving field, with promising future developments for effective personalized treatments. Several stem/progenitor cells are candidates for cardiac cell therapy, and emerging evidence suggests how multiple metabolic and biochemical pathways strictly regulate their fate and renewal. In this review, we will explore a selection of areas of common interest for biology and biochemistry concerning stem/progenitor cells, and in particular cardiac progenitor cells. Numerous regulatory mechanisms have been identified that link stem cell signaling and functions to the modulation of metabolic pathways, and vice versa. Pharmacological treatments and culture requirements may be exploited to modulate stem cell pluripotency and self-renewal, possibly boosting their regenerative potential for cell therapy. Mitochondria and their many related metabolites and messengers, such as oxygen, ROS, calcium and glucose, have a crucial role in regulating stem cell fate and the balance of their functions, together with many metabolic enzymes. Furthermore, protein biochemistry and proteomics can provide precious clues on the definition of different progenitor cell populations, their physiology and their autocrine/paracrine regulatory/signaling networks. Interdisciplinary approaches between biology and biochemistry can provide productive insights on stem/progenitor cells, allowing the development of novel strategies and protocols for effective cardiac cell therapy clinical translation. This article is part of a Special Issue entitled Biochemistry of Stem Cells. Copyright © 2012 Elsevier B.V. All rights reserved.

Tunable All Reflective Spatial Heterodyne Spectroscopy, A Technique For High Resolving Power Observation OI Defused Emission Line Sources

Science.gov (United States)

Hosseini, Seyedeh Sona

The solar system presents a challenge to spectroscopic observers, because it is an astrophysically low energy environment populated with often angularly extended targets (e.g, interplanetary medium, comets, planetary upper atmospheres, and planet and satellite near space environments). Spectroscopy is a proven tool for determining compositional and other properties of remote objects. Narrow band imaging and low resolving spectroscopic measurements provide information about composition, photochemical evolution, energy distribution and density. The extension to high resolving power provides further access to temperature, velocity, isotopic ratios, separation of blended sources, and opacity effects. The drawback of high-resolution spectroscopy comes from the instrumental limitations of lower throughput, the necessity of small entrance apertures, sensitivity, field of view, and large physical instrumental size. These limitations quickly become definitive for faint and/or extended targets and for spacecraft encounters. An emerging technique with promise for the study of faint, extended sources at high resolving power is the all-reflective form of the Spatial Heterodyne Spectrometer (SHS). SHS instruments are compact and naturally possess both high etendue and high resolving power. To achieve similar spectral grasp, grating spectrometers require big telescopes. SHS is a common-path beam Fourier transform interferometer that produces Fizeau fringe pattern for all other wavelengths except the tuned wavelength. Compared to similar Fourier transform Spectrometers (FTS), SHS has considerably relaxed optical tolerances that make it easier to use in the visible and UV spectral ranges. The large etendue of SHS instruments makes them ideal for observations of extended, low surface brightness, isolated emission line sources, while their intrinsically high spectral resolution enables the study of the dynamical and spectral characteristics described above. SHS also combines very

Osteogenic differentiation capacity of human skeletal muscle-derived progenitor cells.

Directory of Open Access Journals (Sweden)

Teruyo Oishi

Full Text Available Heterotopic ossification (HO is defined as the formation of ectopic bone in soft tissue outside the skeletal tissue. HO is thought to result from aberrant differentiation of osteogenic progenitors within skeletal muscle. However, the precise origin of HO is still unclear. Skeletal muscle contains two kinds of progenitor cells, myogenic progenitors and mesenchymal progenitors. Myogenic and mesenchymal progenitors in human skeletal muscle can be identified as CD56(+ and PDGFRα(+ cells, respectively. The purpose of this study was to investigate the osteogenic differentiation potential of human skeletal muscle-derived progenitors. Both CD56(+ cells and PDGFRα(+ cells showed comparable osteogenic differentiation potential in vitro. However, in an in vivo ectopic bone formation model, PDGFRα(+ cells formed bone-like tissue and showed successful engraftment, while CD56(+ cells did not form bone-like tissue and did not adapt to an osteogenic environment. Immunohistological analysis of human HO sample revealed that many PDGFRα(+ cells were localized in proximity to ectopic bone formed in skeletal muscle. MicroRNAs (miRNAs are known to regulate many biological processes including osteogenic differentiation. We investigated the participation of miRNAs in the osteogenic differentiation of PDGFRα(+ cells by using microarray. We identified miRNAs that had not been known to be involved in osteogenesis but showed dramatic changes during osteogenic differentiation of PDGFRα(+ cells. Upregulation of miR-146b-5p and -424 and downregulation of miR-7 during osteogenic differentiation of PDGFRα(+ cells were confirmed by quantitative real-time RT-PCR. Inhibition of upregulated miRNAs, miR-146b-5p and -424, resulted in the suppression of osteocyte maturation, suggesting that these two miRNAs have the positive role in the osteogenesis of PDGFRα(+ cells. Our results suggest that PDGFRα(+ cells may be the major source of HO and that the newly identified mi

Markers of Pluripotency in Human Amniotic Epithelial Cells and Their Differentiation to Progenitor of Cortical Neurons

Science.gov (United States)

García-Castro, Irma Lydia; García-López, Guadalupe; Ávila-González, Daniela; Flores-Herrera, Héctor; Molina-Hernández, Anayansi; Portillo, Wendy; Ramón-Gallegos, Eva; Díaz, Néstor Fabián

2015-01-01

Human pluripotent stem cells (hPSC) have promise for regenerative medicine due to their auto-renovation and differentiation capacities. Nevertheless, there are several ethical and methodological issues about these cells that have not been resolved. Human amniotic epithelial cells (hAEC) have been proposed as source of pluripotent stem cells. Several groups have studied hAEC but have reported inconsistencies about their pluripotency properties. The aim of the present study was the in vitro characterization of hAEC collected from a Mexican population in order to identify transcription factors involved in the pluripotency circuitry and to determine their epigenetic state. Finally, we evaluated if these cells differentiate to cortical progenitors. We analyzed qualitatively and quantitatively the expression of the transcription factors of pluripotency (OCT4, SOX2, NANOG, KLF4 and REX1) by RT-PCR and RT-qPCR in hAEC. Also, we determined the presence of OCT4, SOX2, NANOG, SSEA3, SSEA4, TRA-1-60, E-cadherin, KLF4, TFE3 as well as the proliferation and epigenetic state by immunocytochemistry of the cells. Finally, hAEC were differentiated towards cortical progenitors using a protocol of two stages. Here we show that hAEC, obtained from a Mexican population and cultured in vitro (P0-P3), maintained the expression of several markers strongly involved in pluripotency maintenance (OCT4, SOX2, NANOG, TFE3, KLF4, SSEA3, SSEA4, TRA-1-60 and E-cadherin). Finally, when hAEC were treated with growth factors and small molecules, they expressed markers characteristic of cortical progenitors (TBR2, OTX2, NeuN and β-III-tubulin). Our results demonstrated that hAEC express naïve pluripotent markers (KLF4, REX1 and TFE3) as well as the cortical neuron phenotype after differentiation. This highlights the need for further investigation of hAEC as a possible source of hPSC. PMID:26720151

Multiple spatially resolved reflection spectroscopy for in vivo determination of carotenoids in human skin and blood

Science.gov (United States)

Darvin, Maxim E.; Magnussen, Björn; Lademann, Juergen; Köcher, Wolfgang

2016-09-01

Non-invasive measurement of carotenoid antioxidants in human skin is one of the important tasks to investigate the skin physiology in vivo. Resonance Raman spectroscopy and reflection spectroscopy are the most frequently used non-invasive techniques in dermatology and skin physiology. In the present study, an improved method based on multiple spatially resolved reflection spectroscopy (MSRRS) was introduced. The results obtained were compared with those obtained using the ‘gold standard’ resonance Raman spectroscopy method and showed strong correlations for the total carotenoid concentration (R  =  0.83) as well as for lycopene (R  =  0.80). The measurement stability was confirmed to be better than 10% within the total temperature range from 5 °C to  +  30 °C and pressure contact between the skin and the MSRRS sensor from 800 Pa to 18 000 Pa. In addition, blood samples taken from the subjects were analyzed for carotenoid concentrations. The MSRRS sensor was calibrated on the blood carotenoid concentrations resulting in being able to predict with a correlation of R  =  0.79. On the basis of blood carotenoids it could be demonstrated that the MSRRS cutaneous measurements are not influenced by Fitzpatrick skin types I-VI. The MSRRS sensor is commercially available under the brand name biozoom.

Tissue oxygenation and haemodynamics measurement with spatially resolved NIRS

Science.gov (United States)

Zhang, Y.; Scopesi, F.; Serra, G.; Sun, J. W.; Rolfe, P.

2010-08-01

We describe the use of Near Infrared Spectroscopy (NIRS) for the non-invasive investigation of changes in haemodynamics and oxygenation of human peripheral tissues. The goal was to measure spatial variations of tissue NIRS oxygenation variables, namely deoxy-haemoglobin (HHb), oxy-haemoglobin (HbO2), total haemoglobin (HbT), and thereby to evaluate the responses of the peripheral circulation to imposed physiological challenges. We present a skinfat- muscle heterogeneous tissue model with varying fat thickness up to 15mm and a Monte Carlo simulation of photon transport within this model. The mean partial path length and the mean photon visit depth in the muscle layer were derived for different source-detector spacing. We constructed NIRS instrumentation comprising of light-emitting diodes (LED) as light sources at four wavelengths, 735nm, 760nm, 810nm and 850nm and sensitive photodiodes (PD) as the detectors. Source-detector spacing was varied to perform measurements at different depths within forearm tissue. Changes in chromophore concentration in response to venous and arterial occlusion were calculated using the modified Lambert-Beer Law. Studies in fat and thin volunteers indicated greater sensitivity in the thinner subjects for the tissue oxygenation measurement in the muscle layer. These results were consistent with those found using Monte Carlo simulation. Overall, the results of this investigation demonstrate the usefulness of the NIRS instrument for deriving spatial information from biological tissues.

ON THE PROGENITOR OF THE TYPE II-PLATEAU SN 2008cn in NGC 4603

International Nuclear Information System (INIS)

Elias-Rosa, Nancy; Van Dyk, Schuyler D.; Li, Weidong; Filippenko, Alexei V.; Foley, Ryan J.; Smith, Nathan; Morrell, Nidia; Gonzalez, Sergio; Hamuy, Mario; Cuillandre, Jean-Charles

2009-01-01

A trend is emerging regarding the progenitor stars that give rise to the most common core-collapse supernovae (SNe), those of Type II-Plateau (II-P): they generally appear to be red supergiants with a limited range of initial masses, ∼8-16 M sun . Here, we consider another example, SN 2008cn, in the nearly face-on spiral galaxy NGC 4603. Even with limited photometric data, it appears that SN 2008cn is not a normal SN II-P, but is of the high-luminosity subclass. Through comparison of pre- and post-explosion images obtained with the Wide Field and Planetary Camera 2 on board the Hubble Space Telescope, we have isolated a supergiant star prior to explosion at nearly the same position as the SN. We provide evidence that this supergiant may well be the progenitor of the SN, although this identification is not entirely unambiguous. This is exacerbated by the distance to the host galaxy, 33.3 Mpc, making SN 2008cn the most distant SN II-P yet for which an attempt has been made to identify a progenitor star in pre-SN images. The progenitor candidate has a more yellow color ([V - I] 0 = 0.98 mag and T eff = 5200 ± 300 K) than generally would be expected and, if a single star, would require that it exploded during a 'blue loop' evolutionary phase, which is theoretically not expected to occur. Nonetheless, we estimate an initial mass of M ini = 15 ± 2 M sun for this star, which is within the expected mass range for SN II-P progenitors. The yellower color could also arise from the blend of two or more stars, such as a red supergiant and a brighter, blue supergiant. Such a red supergiant hidden in this blend could instead be the progenitor and would also have an initial mass within the expected progenitor mass range. Furthermore, the yellow supergiant could be in a massive, interacting binary system, analogous to the possible yellow supergiant progenitor of the high-luminosity SN II-P 2004et. Finally, if the yellow supergiant is not the progenitor, or is not a stellar

Novel technique for spatially resolved imaging of molecular bond orientations using x-ray birefringence

Energy Technology Data Exchange (ETDEWEB)

Sutter, John P., E-mail: john.sutter@diamond.ac.uk; Dolbnya, Igor P.; Collins, Stephen P. [Diamond Light Source Ltd, Harwell Science and Innovation Campus, Chilton, Didcot, Oxfordshire OX11 0DE (United Kingdom); Harris, Kenneth D. M., E-mail: HarrisKDM@cardiff.ac.uk; Edwards-Gau, Gregory R.; Kariuki, Benson M. [School of Chemistry, Cardiff University, Park Place, Cardiff CF10 3AT (United Kingdom); Palmer, Benjamin A. [Department of Structural Biology, Weizmann Institute of Science, 234 Herzl St., Rehovot 7610001 (Israel)

2016-07-27

Birefringence has been observed in anisotropic materials transmitting linearly polarized X-ray beams tuned close to an absorption edge of a specific element in the material. Synchrotron bending magnets provide X-ray beams of sufficiently high brightness and cross section for spatially resolved measurements of birefringence. The recently developed X-ray Birefringence Imaging (XBI) technique has been successfully applied for the first time using the versatile test beamline B16 at Diamond Light Source. Orientational distributions of the C–Br bonds of brominated “guest” molecules within crystalline “host” tunnel structures (in thiourea or urea inclusion compounds) have been studied using linearly polarized incident X-rays near the Br K-edge. Imaging of domain structures, changes in C–Br bond orientations associated with order-disorder phase transitions, and the effects of dynamic averaging of C–Br bond orientations have been demonstrated. The XBI setup uses a vertically deflecting high-resolution double-crystal monochromator upstream from the sample and a horizontally deflecting single-crystal polarization analyzer downstream, with a Bragg angle as close as possible to 45°. In this way, the ellipticity and rotation angle of the polarization of the beam transmitted through the sample is measured as in polarizing optical microscopy. The theoretical instrumental background calculated from the elliptical polarization of the bending-magnet X-rays, the imperfect polarization discrimination of the analyzer, and the correlation between vertical position and photon energy introduced by the monochromator agrees well with experimental observations. The background is calculated analytically because the region of X-ray phase space selected by this setup is sampled inefficiently by standard methods.

SPATIALLY RESOLVED SPECTROSCOPY OF SUBMILLIMETER GALAXIES AT z ≃ 2

Energy Technology Data Exchange (ETDEWEB)

Olivares, V.; Treister, E.; Privon, G. C.; Nagar, N. [Universidad de Concepción, Departamento de Astronomía, Casilla 160-C, Concepción (Chile); Alaghband-Zadeh, S.; Chapman, S. [Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge, CB3 0HA UK (United Kingdom); Casey, Caitlin M. [Department of Physics and Astronomy, University of California, Irvine, CA 92697 (United States); Schawinski, K. [Institute for Astronomy, Department of Physics, ETH Zurich, Wolfgang-Pauli-Strasse 27, CH-8093 Zurich (Switzerland); Kurczynski, P.; Gawiser, E. [Department of Physics and Astronomy, Rutgers, The State University of New Jersey, 136 Frelinghuysen Road, Piscataway, NJ 08854 (United States); Bauer, F. E. [Instituto de Astrofísica, Facultad de Física, Pontificia Universidad Católica de Chile, Casilla 306, Santiago 22 (Chile); Sanders, D. [Institute for Astronomy, 2680 Woodlawn Drive, University of Hawaii, Honolulu, HI 96822 (United States)

2016-08-10

We present near-infrared integral-field spectroscopic observations targeting H α in eight submillimeter galaxies (SMGs) at z = 1.3–2.5 using the Very Large Telescope/Spectrograph for Integral Field Observations in the Near Infrared, obtaining significant detections for six of them. The star formation rates derived from the H α emission are ∼100 M {sub ⊙} yr{sup −1}, which account for only ∼20%–30% of the infrared-derived values, thus suggesting that these systems are very dusty. Two of these systems present [N ii]/H α ratios indicative of the presence of an active galactic nucleus. We mapped the spatial distribution and kinematics of the star-forming regions in these galaxies on kiloparsec scales. In general, the H α morphologies tend to be highly irregular and/or clumpy, showing spatial extents of ∼3–11 kpc. We find evidence for significant spatial offsets, of ∼0.″1–0.″4 or 1.2–3.4 kpc, between the H α and the continuum emission in three of the sources. Performing a kinemetry analysis, we conclude that the majority of the sample is not consistent with disk-like rotation-dominated kinematics. Instead, they tend to show irregular and/or clumpy and turbulent velocity and velocity dispersion fields. This can be interpreted as evidence for a scenario in which these extreme star formation episodes are triggered by galaxy–galaxy interactions and major mergers. In contrast to recent results for SMGs, these sources appear to follow the same relations between gas and star-forming rate densities as less luminous and/or normal star-forming galaxies.

Sonic hedgehog lineage in the mouse hypothalamus: from progenitor domains to hypothalamic regions

Directory of Open Access Journals (Sweden)

Alvarez-Bolado Gonzalo

2012-01-01

Full Text Available Abstract Background The hypothalamus is a brain region with essential functions for homeostasis and energy metabolism, and alterations of its development can contribute to pathological conditions in the adult, like hypertension, diabetes or obesity. However, due to the anatomical complexity of the hypothalamus, its development is not well understood. Sonic hedgehog (Shh is a key developmental regulator gene expressed in a dynamic pattern in hypothalamic progenitor cells. To obtain insight into hypothalamic organization, we used genetic inducible fate mapping (GIFM to map the lineages derived from Shh-expressing progenitor domains onto the four rostrocaudally arranged hypothalamic regions: preoptic, anterior, tuberal and mammillary. Results Shh-expressing progenitors labeled at an early stage (before embryonic day (E9.5 contribute neurons and astrocytes to a large caudal area including the mammillary and posterior tuberal regions as well as tanycytes (specialized median eminence glia. Progenitors labeled at later stages (after E9.5 give rise to neurons and astrocytes of the entire tuberal region and in particular the ventromedial nucleus, but not to cells in the mammillary region and median eminence. At this stage, an additional Shh-expressing domain appears in the preoptic area and contributes mostly astrocytes to the hypothalamus. Shh-expressing progenitors do not contribute to the anterior region at any stage. Finally, we show a gradual shift from neurogenesis to gliogenesis, so that progenitors expressing Shh after E12.5 generate almost exclusively hypothalamic astrocytes. Conclusions We define a fate map of the hypothalamus, based on the dynamic expression of Shh in the hypothalamic progenitor zones. We provide evidence that the large neurogenic Shh-expressing progenitor domains of the ventral diencephalon are continuous with those of the midbrain. We demonstrate that the four classical transverse zones of the hypothalamus have clearly

Dendritic Cell Lineage Potential in Human Early Hematopoietic Progenitors

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Julie Helft

2017-07-01

Full Text Available Conventional dendritic cells (cDCs are thought to descend from a DC precursor downstream of the common myeloid progenitor (CMP. However, a mouse lymphoid-primed multipotent progenitor has been shown to generate cDCs following a DC-specific developmental pathway independent of monocyte and granulocyte poiesis. Similarly, here we show that, in humans, a large fraction of multipotent lymphoid early progenitors (MLPs gives rise to cDCs, in particular the subset known as cDC1, identified by co-expression of DNGR-1 (CLEC9A and CD141 (BDCA-3. Single-cell analysis indicates that over one-third of MLPs have the potential to efficiently generate cDCs. cDC1s generated from CMPs or MLPs do not exhibit differences in transcriptome or phenotype. These results demonstrate an early imprinting of the cDC lineage in human hematopoiesis and highlight the plasticity of developmental pathways giving rise to human DCs.

Time-resolved measurement of global synchronization in the dust acoustic wave

Science.gov (United States)

Williams, J. D.

2014-10-01

A spatially and temporally resolved measurement of the synchronization of the naturally occurring dust acoustic wave to an external drive and the relaxation from the driven wave mode back to the naturally occuring wave mode is presented. This measurement provides a time-resolved measurement of the synchronization of the self-excited dust acoustic wave with an external drive and the return to the self-excited mode. It is observed that the wave synchronizes to the external drive in a distinct time-dependent fashion, while there is an immediate loss of synchronization when the external modulation is discontinued.

Development of a Schottky CdTe Medipix3RX hybrid photon counting detector with spatial and energy resolving capabilities

Energy Technology Data Exchange (ETDEWEB)

Gimenez, E.N., E-mail: Eva.Gimenez@diamond.ac.uk [Diamond Light Source, Harwell Campus, Oxforshire OX11 0DE (United Kingdom); Astromskas, V. [University of Surrey (United Kingdom); Horswell, I.; Omar, D.; Spiers, J.; Tartoni, N. [Diamond Light Source, Harwell Campus, Oxforshire OX11 0DE (United Kingdom)

2016-07-11

A multichip CdTe-Medipix3RX detector system was developed in order to bring the advantages of photon-counting detectors to applications in the hard X-ray range of energies. The detector head consisted of 2×2 Medipix3RX ASICs bump-bonded to a 28 mm×28 mm e{sup −} collection Schottky contact CdTe sensor. Schottky CdTe sensors undergo performance degrading polarization which increases with temperature, flux and the longer the HV is applied. Keeping the temperature stable and periodically refreshing the high voltage bias supply was used to minimize the polarization and achieve a stable and reproducible detector response. This leads to good quality images and successful results on the energy resolving capabilities of the system. - Highlights: • A high atomic number (CdTe sensor based) photon-counting detector was developed. • Polarization effects affected the image were minimized by regularly refreshing the bias voltage and stabilizing the temperature. • Good spatial resolution and image quality was achieved following this procedure.

Periodontal Bioengineering: A Discourse in Surface Topographies, Progenitor Cells and Molecular Profiles

Science.gov (United States)

Dangaria, Smit J.

2011-12-01

Stem/progenitor cells are a population of cells capable of providing replacement cells for a given differentiated cell type. We have applied progenitor cell-based technologies to generate novel tissue-engineered implants that use biomimetic strategies with the ultimate goal of achieving full regeneration of lost periodontal tissues. Mesenchymal periodontal tissues such as cementum, alveolar bone (AB), and periodontal ligament (PDL) are neural crest-derived entities that emerge from the dental follicle (DF) at the onset of tooth root formation. Using a systems biology approach we have identified key differences between these periodontal progenitors on the basis of global gene expression profiles, gene cohort expression levels, and epigenetic modifications, in addition to differences in cellular morphologies. On an epigenetic level, DF progenitors featured high levels of the euchromatin marker H3K4me3, whereas PDL cells, AB osteoblasts, and cementoblasts contained high levels of the transcriptional repressor H3K9me3. Secondly, we have tested the influence of natural extracellular hydroxyapatite matrices on periodontal progenitor differentiation. Dimension and structure of extracellular matrix surfaces have powerful influences on cell shape, adhesion, and gene expression. Here we show that natural tooth root topographies induce integrin-mediated extracellular matrix signaling cascades in tandem with cell elongation and polarization to generate physiological periodontium-like tissues. In this study we replanted surface topography instructed periodontal ligament progenitors (PDLPs) into rat alveolar bone sockets for 8 and 16 weeks, resulting in complete attachment of tooth roots to the surrounding alveolar bone with a periodontal ligament fiber apparatus closely matching physiological controls along the entire root surface. Displacement studies and biochemical analyses confirmed that progenitor-based engineered periodontal tissues were similar to control teeth and

Fractalkine expression induces endothelial progenitor cell lysis by natural killer cells.

Directory of Open Access Journals (Sweden)

Dilyana Todorova

Full Text Available BACKGROUND: Circulating CD34(+ cells, a population that includes endothelial progenitors, participate in the maintenance of endothelial integrity. Better understanding of the mechanisms that regulate their survival is crucial to improve their regenerative activity in cardiovascular and renal diseases. Chemokine-receptor cross talk is critical in regulating cell homeostasis. We hypothesized that cell surface expression of the chemokine fractalkine (FKN could target progenitor cell injury by Natural Killer (NK cells, thereby limiting their availability for vascular repair. METHODOLOGY/PRINCIPAL FINDINGS: We show that CD34(+-derived Endothelial Colony Forming Cells (ECFC can express FKN in response to TNF-α and IFN-γ inflammatory cytokines and that FKN expression by ECFC stimulates NK cell adhesion, NK cell-mediated ECFC lysis and microparticles release in vitro. The specific involvement of membrane FKN in these processes was demonstrated using FKN-transfected ECFC and anti-FKN blocking antibody. FKN expression was also evidenced on circulating CD34(+ progenitor cells and was detected at higher frequency in kidney transplant recipients, when compared to healthy controls. The proportion of CD34(+ cells expressing FKN was identified as an independent variable inversely correlated to CD34(+ progenitor cell count. We further showed that treatment of CD34(+ circulating cells isolated from adult blood donors with transplant serum or TNF-α/IFN-γ can induce FKN expression. CONCLUSIONS: Our data highlights a novel mechanism by which FKN expression on CD34(+ progenitor cells may target their NK cell mediated killing and participate to their immune depletion in transplant recipients. Considering the numerous diseased contexts shown to promote FKN expression, our data identify FKN as a hallmark of altered progenitor cell homeostasis with potential implications in better evaluation of vascular repair in patients.

Accounting for spatial effects in land use regression for urban air pollution modeling.

Science.gov (United States)

Bertazzon, Stefania; Johnson, Markey; Eccles, Kristin; Kaplan, Gilaad G

2015-01-01

In order to accurately assess air pollution risks, health studies require spatially resolved pollution concentrations. Land-use regression (LUR) models estimate ambient concentrations at a fine spatial scale. However, spatial effects such as spatial non-stationarity and spatial autocorrelation can reduce the accuracy of LUR estimates by increasing regression errors and uncertainty; and statistical methods for resolving these effects--e.g., spatially autoregressive (SAR) and geographically weighted regression (GWR) models--may be difficult to apply simultaneously. We used an alternate approach to address spatial non-stationarity and spatial autocorrelation in LUR models for nitrogen dioxide. Traditional models were re-specified to include a variable capturing wind speed and direction, and re-fit as GWR models. Mean R(2) values for the resulting GWR-wind models (summer: 0.86, winter: 0.73) showed a 10-20% improvement over traditional LUR models. GWR-wind models effectively addressed both spatial effects and produced meaningful predictive models. These results suggest a useful method for improving spatially explicit models. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

Interneuron progenitor transplantation to treat CNS dysfunction

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Muhammad O Chohan

2016-08-01

Full Text Available Due to the inadequacy of endogenous repair mechanisms diseases of the nervous system remain a major challenge to scientists and clinicians. Stem cell based therapy is an exciting and viable strategy that has been shown to ameliorate or even reverse symptoms of CNS dysfunction in preclinical animal models. Of particular importance has been the use of GABAergic interneuron progenitors as a therapeutic strategy. Born in the neurogenic niches of the ventral telencephalon, interneuron progenitors retain their unique capacity to disperse, integrate and induce plasticity in adult host circuitries following transplantation. Here we discuss the potential of interneuron based transplantation strategies as it relates to CNS disease therapeutics. We also discuss mechanisms underlying their therapeutic efficacy and some of the challenges that face the field.

DNMT1 Maintains Progenitor Function in Self-Renewing Somatic Tissue

OpenAIRE

Sen, George L.; Reuter, Jason A.; Webster, Daniel E.; Zhu, Lilly; Khavari, Paul A.

2010-01-01

Progenitor cells maintain self-renewing tissues throughout life by sustaining their capacity for proliferation while suppressing cell cycle exit and terminal differentiation1,2. DNA methylation3,4,5 provides a potential epigenetic mechanism for the cellular memory needed to preserve the somatic progenitor state through repeated cell divisions. DNA methyltransferase 1 (DNMT1)6,7 maintains DNA methylation patterns after cellular replication. Although dispensable for embryonic stem cell maintena...

Effects of Substrate and Co-Culture on Neural Progenitor Cell Differentiation

Energy Technology Data Exchange (ETDEWEB)

Jones, Erin Boote [Iowa State Univ., Ames, IA (United States)

2008-01-01

In recent years the study of stem and progenitor cells has moved to the forefront of research. Since the isolation of human hematopoietic stem cells in 1988 and the subsequent discovery of a self renewing population of multipotent cells in many tissues, many researchers have envisioned a better understanding of development and potential clinical usage in intractable diseases. Both these goals, however, depend on a solid understanding of the intracellular and extracellular forces that cause stem cells to differentiate to a specific cell fate. Many diseases of large scale cell loss have been suggested as candidates for stem cell based treatments. It is proposed that replacing the function of the damaged or defective cells by specific differentiation of stem or progenitor cells could treat the disease. Before cells can be directed to specific lineages, the mechanisms of differentiation must be better understood. Differentiation in vivo is an intensively complex system that is difficult to study. The goal of this research is to develop further understanding of the effects of soluble and extracellular matrix (ECM) cues on the differentiation of neural progenitor cells with the use of a simplified in vitro culture system. Specific research objectives are to study the differentiation of neural progenitor cells in response to astrocyte conditioned medium and protein substrate composition and concentration. In an effort to reveal the mechanism of the conditioned medium interaction, a test for the presence of a feedback loop between progenitor cells and astrocytes is presented along with an examination of conditioned medium storage temperature, which can reveal enzymatic dependencies. An examination of protein substrate composition and concentration will help to reveal the role of any ECM interactions on differentiation. This thesis is organized into a literature review covering recent advances in use of external modulators of differentiation such as surface coatings, co

Resolvent-based modeling of passive scalar dynamics in wall-bounded turbulence

Science.gov (United States)

Dawson, Scott; Saxton-Fox, Theresa; McKeon, Beverley

2017-11-01

The resolvent formulation of the Navier-Stokes equations expresses the system state as the output of a linear (resolvent) operator acting upon a nonlinear forcing. Previous studies have demonstrated that a low-rank approximation of this linear operator predicts many known features of incompressible wall-bounded turbulence. In this work, this resolvent model for wall-bounded turbulence is extended to include a passive scalar field. This formulation allows for a number of additional simplifications that reduce model complexity. Firstly, it is shown that the effect of changing scalar diffusivity can be approximated through a transformation of spatial wavenumbers and temporal frequencies. Secondly, passive scalar dynamics may be studied through the low-rank approximation of a passive scalar resolvent operator, which is decoupled from velocity response modes. Thirdly, this passive scalar resolvent operator is amenable to approximation by semi-analytic methods. We investigate the extent to which this resulting hierarchy of models can describe and predict passive scalar dynamics and statistics in wall-bounded turbulence. The support of AFOSR under Grant Numbers FA9550-16-1-0232 and FA9550-16-1-0361 is gratefully acknowledged.

Progenitors mobilized by gamma-tocotrienol as an effective radiation countermeasure.

Directory of Open Access Journals (Sweden)

Vijay K Singh

Full Text Available The purpose of this study was to elucidate the role of gamma-tocotrienol (GT3-mobilized progenitors in mitigating damage to mice exposed to a supralethal dose of cobalt-60 gamma-radiation. CD2F1 mice were transfused 24 h post-irradiation with whole blood or isolated peripheral blood mononuclear cells (PBMC from donors that had received GT3 72 h prior to blood collection and recipient mice were monitored for 30 days. To understand the role of GT3-induced granulocyte colony-stimulating factor (G-CSF in mobilizing progenitors, donor mice were administered a neutralizing antibody specific to G-CSF or its isotype before blood collection. Bacterial translocation from gut to heart, spleen and liver of irradiated recipient mice was evaluated by bacterial culture on enriched and selective agar media. Endotoxin in serum samples also was measured. We also analyzed the colony-forming units in the spleens of irradiated mice. Our results demonstrate that whole blood or PBMC from GT3-administered mice mitigated radiation injury when administered 24 h post-irradiation. Furthermore, administration of a G-CSF antibody to GT3-injected mice abrogated the efficacy of blood or PBMC obtained from such donors. Additionally, GT3-mobilized PBMC inhibited the translocation of intestinal bacteria to the heart, spleen, and liver, and increased colony forming unit-spleen (CFU-S numbers in irradiated mice. Our data suggests that GT3 induces G-CSF, which mobilizes progenitors and these progenitors mitigate radiation injury in recipient mice. This approach using mobilized progenitor cells from GT3-injected donors could be a potential treatment for humans exposed to high doses of radiation.

Progenitor outgrowth from the niche in Drosophila trachea is guided by FGF from decaying branches.

Science.gov (United States)

Chen, Feng; Krasnow, Mark A

2014-01-10

Although there has been progress identifying adult stem and progenitor cells and the signals that control their proliferation and differentiation, little is known about the substrates and signals that guide them out of their niche. By examining Drosophila tracheal outgrowth during metamorphosis, we show that progenitors follow a stereotyped path out of the niche, tracking along a subset of tracheal branches destined for destruction. The embryonic tracheal inducer branchless FGF (fibroblast growth factor) is expressed dynamically just ahead of progenitor outgrowth in decaying branches. Knockdown of branchless abrogates progenitor outgrowth, whereas misexpression redirects it. Thus, reactivation of an embryonic tracheal inducer in decaying branches directs outgrowth of progenitors that replace them. This explains how the structure of a newly generated tissue is coordinated with that of the old.

Mass ejection in failed supernovae: variation with stellar progenitor

Science.gov (United States)

Fernández, Rodrigo; Quataert, Eliot; Kashiyama, Kazumi; Coughlin, Eric R.

2018-05-01

We study the ejection of mass during stellar core-collapse when the stalled shock does not revive and a black hole forms. Neutrino emission during the protoneutron star phase causes a decrease in the gravitational mass of the core, resulting in an outward going sound pulse that steepens into a shock as it travels out through the star. We explore the properties of this mass ejection mechanism over a range of stellar progenitors using spherically symmetric, time-dependent hydrodynamic simulations that treat neutrino mass-loss parametrically and follow the shock propagation over the entire star. We find that all types of stellar progenitor can eject mass through this mechanism. The ejected mass is a decreasing function of the surface gravity of the star, ranging from several M⊙ for red supergiants to ˜0.1 M⊙ for blue supergiants and ˜10-3 M⊙ for Wolf-Rayet stars. We find that the final shock energy at the surface is a decreasing function of the core-compactness, and is ≲ 1047-1048 erg in all cases. In progenitors with a sufficiently large envelope, high core-compactness, or a combination of both, the sound pulse fails to unbind mass. Successful mass ejection is accompanied by significant fallback accretion that can last from hours to years. We predict the properties of shock breakout and thermal plateau emission produced by the ejection of the outer envelope of blue supergiant and Wolf-Rayet progenitors in otherwise failed supernovae.

Policy applications of a highly resolved spatial and temporal onroad carbon dioxide emissions data product for the U.S.: Analyses and their implications for mitigation

Science.gov (United States)

Mendoza Lebrun, Daniel

Onroad CO2 emissions were analyzed as part of overall GHG emissions, but those studies have suffered from one or more of these five shortcomings: 1) the spatial resolution was coarse, usually encompassing a region, or the entire U.S.; 2) the temporal resolution was coarse (annual or monthly); 3) the study region was limited, usually a metropolitan planning organization (MPO) or state; 4) fuel sales were used as a proxy to quantify fuel consumption instead of focusing on travel; 5) the spatial heterogeneity of fleet and road network composition was not considered and instead national averages are used. Normalized vehicle-type state-level spatial biases range from 2.6% to 8.1%, while the road type classification biases range from -6.3% to 16.8%. These biases are found to cause errors in reduction estimates as large as ±60%, corresponding to ±0.2 MtC, for a national-average emissions mitigation strategy focused on a 10% emissions reduction from a single vehicle class. Temporal analysis shows distinct emissions seasonality that is particularly visible in the northernmost latitudes, demonstrating peak-to-peak deviations from the annual mean of up to 50%. The hourly structure shows peak-to-peak deviation from a weekly average of up to 200% for heavy-duty (HD) vehicles and 140% for light-duty (LD) vehicles. The present study focuses on reduction of travel and fuel economy improvements by putting forth several mitigation scenarios aimed at reducing VMT and increasing vehicle fuel efficiency. It was found that the most effective independent reduction strategies are those that increase fuel efficiency by extending standards proposed by the corporate average fuel economy (CAFE) or reduction of fuel consumption due to price increases. These two strategies show cumulative emissions reductions of approximately 11% and 12%, respectively, from a business as usual (BAU) approach over the 2000-2050 period. The U.S. onroad transportation sector is long overdue a comprehensive study

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Lifescience Database Archive (English)

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Differential requirements of androgen receptor in luminal progenitors during prostate regeneration and tumor initiation

Science.gov (United States)

Chua, Chee Wai; Epsi, Nusrat J; Leung, Eva Y; Xuan, Shouhong; Lei, Ming; Li, Bo I; Bergren, Sarah K; Hibshoosh, Hanina; Mitrofanova, Antonina

2018-01-01

Master regulatory genes of tissue specification play key roles in stem/progenitor cells and are often important in cancer. In the prostate, androgen receptor (AR) is a master regulator essential for development and tumorigenesis, but its specific functions in prostate stem/progenitor cells have not been elucidated. We have investigated AR function in CARNs (CAstration-Resistant Nkx3.1-expressing cells), a luminal stem/progenitor cell that functions in prostate regeneration. Using genetically--engineered mouse models and novel prostate epithelial cell lines, we find that progenitor properties of CARNs are largely unaffected by AR deletion, apart from decreased proliferation in vivo. Furthermore, AR loss suppresses tumor formation after deletion of the Pten tumor suppressor in CARNs; however, combined Pten deletion and activation of oncogenic Kras in AR-deleted CARNs result in tumors with focal neuroendocrine differentiation. Our findings show that AR modulates specific progenitor properties of CARNs, including their ability to serve as a cell of origin for prostate cancer. PMID:29334357

Novel pathways to erythropoiesis induced by dimerization of intracellular C-Mpl in human hematopoietic progenitors.

Science.gov (United States)

Parekh, Chintan; Sahaghian, Arineh; Kim, William; Scholes, Jessica; Ge, Shundi; Zhu, Yuhua; Asgharzadeh, Shahab; Hollis, Roger; Kohn, Donald; Ji, Lingyun; Malvar, Jemily; Wang, Xiaoyan; Crooks, Gay

2012-04-01

The cytokine thrombopoietin (Tpo) plays a critical role in hematopoiesis by binding to the extracellular domain and inducing homodimerization of the intracellular signaling domain of its receptor, c-Mpl. Mpl homodimerization can also be accomplished by binding of a synthetic ligand to a constitutively expressed fusion protein F36VMpl consisting of a ligand binding domain (F36V) and the intracellular signaling domain of Mpl. Unexpectedly, in contrast to Tpo stimulation, robust erythropoiesis is induced after dimerization of F36VMpl in human CD34+ progenitor cells. The goal of this study was to define the hematopoietic progenitor stages at which dimerization of intracellular Mpl induces erythropoiesis and the downstream molecular events that mediate this unanticipated effect. Dimerization (in the absence of erythropoietin and other cytokines) in human common myeloid progenitors and megakaryocytic erythroid progenitors caused a significant increase in CD34+ cells (p Mpl in human myeloerythroid progenitors induces progenitor expansion and erythropoiesis through molecular mechanisms that are not shared by Tpo stimulation of endogenous Mpl. Copyright © 2012 AlphaMed Press.

Timing the formation and assembly of early-type galaxies via spatially resolved stellar populations analysis

Science.gov (United States)

Martín-Navarro, Ignacio; Vazdekis, Alexandre; Falcón-Barroso, Jesús; La Barbera, Francesco; Yıldırım, Akın; van de Ven, Glenn

2018-04-01

To investigate star formation and assembly processes of massive galaxies, we present here a spatially resolved stellar population analysis of a sample of 45 elliptical galaxies (Es) selected from the Calar Alto Legacy Integral Field Area survey. We find rather flat age and [Mg/Fe] radial gradients, weakly dependent on the effective velocity dispersion of the galaxy within half-light radius. However, our analysis shows that metallicity gradients become steeper with increasing galaxy velocity dispersion. In addition, we have homogeneously compared the stellar population gradients of our sample of Es to a sample of nearby relic galaxies, i.e. local remnants of the high-z population of red nuggets. This comparison indicates that, first, the cores of present-day massive galaxies were likely formed in gas-rich, rapid star formation events at high redshift (z ≳ 2). This led to radial metallicity variations steeper than observed in the local Universe, and positive [Mg/Fe] gradients. Secondly, our analysis also suggests that a later sequence of minor dry mergers, populating the outskirts of early-type galaxies (ETGs), flattened the pristine [Mg/Fe] and metallicity gradients. Finally, we find a tight age-[Mg/Fe] relation, supporting that the duration of the star formation is the main driver of the [Mg/Fe] enhancement in massive ETGs. However, the star formation time-scale alone is not able to fully explain our [Mg/Fe] measurements. Interestingly, our results match the expected effect that a variable stellar initial mass function would have on the [Mg/Fe] ratio.

Induced pluripotent stem cell-derived cardiac progenitors differentiate to cardiomyocytes and form biosynthetic tissues.

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Nicolas Christoforou

Full Text Available The mammalian heart has little capacity to regenerate, and following injury the myocardium is replaced by non-contractile scar tissue. Consequently, increased wall stress and workload on the remaining myocardium leads to chamber dilation, dysfunction, and heart failure. Cell-based therapy with an autologous, epigenetically reprogrammed, and cardiac-committed progenitor cell source could potentially reverse this process by replacing the damaged myocardium with functional tissue. However, it is unclear whether cardiac progenitor cell-derived cardiomyocytes are capable of attaining levels of structural and functional maturity comparable to that of terminally-fated cardiomyocytes. Here, we first describe the derivation of mouse induced pluripotent stem (iPS cells, which once differentiated allow for the enrichment of Nkx2-5(+ cardiac progenitors, and the cardiomyocyte-specific expression of the red fluorescent protein. We show that the cardiac progenitors are multipotent and capable of differentiating into endothelial cells, smooth muscle cells and cardiomyocytes. Moreover, cardiac progenitor selection corresponds to cKit(+ cell enrichment, while cardiomyocyte cell-lineage commitment is concomitant with dual expression of either cKit/Flk1 or cKit/Sca-1. We proceed to show that the cardiac progenitor-derived cardiomyocytes are capable of forming electrically and mechanically coupled large-scale 2D cell cultures with mature electrophysiological properties. Finally, we examine the cell progenitors' ability to form electromechanically coherent macroscopic tissues, using a physiologically relevant 3D culture model and demonstrate that following long-term culture the cardiomyocytes align, and form robust electromechanical connections throughout the volume of the biosynthetic tissue construct. We conclude that the iPS cell-derived cardiac progenitors are a robust cell source for tissue engineering applications and a 3D culture platform for pharmacological

Spatially unresolved SED fitting can underestimate galaxy masses: a solution to the missing mass problem

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Sorba, Robert; Sawicki, Marcin

2018-05-01

We perform spatially resolved, pixel-by-pixel Spectral Energy Distribution (SED) fitting on galaxies up to z ˜ 2.5 in the Hubble eXtreme Deep Field (XDF). Comparing stellar mass estimates from spatially resolved and spatially unresolved photometry we find that unresolved masses can be systematically underestimated by factors of up to 5. The ratio of the unresolved to resolved mass measurement depends on the galaxy's specific star formation rate (sSFR): at low sSFRs the bias is small, but above sSFR ˜ 10-9.5 yr-1 the discrepancy increases rapidly such that galaxies with sSFRs ˜ 10-8 yr-1 have unresolved mass estimates of only one-half to one-fifth of the resolved value. This result indicates that stellar masses estimated from spatially unresolved data sets need to be systematically corrected, in some cases by large amounts, and we provide an analytic prescription for applying this correction. We show that correcting stellar mass measurements for this bias changes the normalization and slope of the star-forming main sequence and reduces its intrinsic width; most dramatically, correcting for the mass bias increases the stellar mass density of the Universe at high redshift and can resolve the long-standing discrepancy between the directly measured cosmic SFR density at z ≳ 1 and that inferred from stellar mass densities (`the missing mass problem').

Use of long-term human marrow cultures to demonstrate progenitor cell precursors in marrow treated with 4-hydroperoxycyclophosphamide

International Nuclear Information System (INIS)

Winton, E.F.; Colenda, K.W.

1987-01-01

The continued retrieval of progenitor cells (CFU-GEMM, BFU-E, CFU-E, CFU-GM) from human long-term marrow cultures (LTMC) is not uncommonly used as evidence that proliferation and differentiation are occurring in more primitive hematopoietic stem cells (HSC) in these cultures. Alternatively, the continued presence of progenitors in LTMC could be the result of survival and/or limited self-renewal of progenitor cells present when the culture was initiated, and such progenitors would have little relevance to the parent HSC. The following studies were designed to determine the relative contributions of precursors of progenitor cells to the total progenitor cells present in LTMC using a two-stage regeneration model. The adherent layer in LTMC was established over 3 weeks, irradiated (875 rad) to permanently eliminate resident hematopoietic cells, and recharged with autologous cryo-preserved marrow that was either treated or not treated (control) with 4-hydroperoxycyclophosphamide (4-HC, 100 micrograms/ml for 30 min). The 4-HC-treated marrow contained no progenitor cells, yet based on clinical autologous bone marrow transplant experience, has intact HSC. Within 1-3 weeks, progenitor cells reappeared in the irradiated LTMC recharged with 4-HC-treated marrow, and were preferentially located in the adherent layer. By 2-6 weeks, the number of progenitor cells in the adherent layer of LTMC recharged with 4-HC marrow was equivalent to control LTMC. The progenitors regenerating in the irradiated LTMC recharged with 4-HC-treated marrow appear to originate from precursors of progenitor cells, perhaps HSC. We propose this model may be useful in elucidating cellular and molecular correlates of progenitor cell regeneration from precursors

Depth resolved hyperspectral imaging spectrometer based on structured light illumination and Fourier transform interferometry

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Choi, Heejin; Wadduwage, Dushan; Matsudaira, Paul T.; So, Peter T.C.

2014-01-01

A depth resolved hyperspectral imaging spectrometer can provide depth resolved imaging both in the spatial and the spectral domain. Images acquired through a standard imaging Fourier transform spectrometer do not have the depth-resolution. By post processing the spectral cubes (x, y, λ) obtained through a Sagnac interferometer under uniform illumination and structured illumination, spectrally resolved images with depth resolution can be recovered using structured light illumination algorithms such as the HiLo method. The proposed scheme is validated with in vitro specimens including fluorescent solution and fluorescent beads with known spectra. The system is further demonstrated in quantifying spectra from 3D resolved features in biological specimens. The system has demonstrated depth resolution of 1.8 μm and spectral resolution of 7 nm respectively. PMID:25360367

Canonical Wnt signaling transiently stimulates proliferation and enhances neurogenesis in neonatal neural progenitor cultures

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Hirsch, Cordula; Campano, Louise M.; Woehrle, Simon; Hecht, Andreas

2007-01-01

Canonical Wnt signaling triggers the formation of heterodimeric transcription factor complexes consisting of β-catenin and T cell factors, and thereby controls the execution of specific genetic programs. During the expansion and neurogenic phases of embryonic neural development canonical Wnt signaling initially controls proliferation of neural progenitor cells, and later neuronal differentiation. Whether Wnt growth factors affect neural progenitor cells postnatally is not known. Therefore, we have analyzed the impact of Wnt signaling on neural progenitors isolated from cerebral cortices of newborn mice. Expression profiling of pathway components revealed that these cells are fully equipped to respond to Wnt signals. However, Wnt pathway activation affected only a subset of neonatal progenitors and elicited a limited increase in proliferation and neuronal differentiation in distinct subsets of cells. Moreover, Wnt pathway activation only transiently stimulated S-phase entry but did not support long-term proliferation of progenitor cultures. The dampened nature of the Wnt response correlates with the predominant expression of inhibitory pathway components and the rapid actuation of negative feedback mechanisms. Interestingly, in differentiating cell cultures activation of canonical Wnt signaling reduced Hes1 and Hes5 expression suggesting that during postnatal neural development, Wnt/β-catenin signaling enhances neurogenesis from progenitor cells by interfering with Notch pathway activity

Human Urine-Derived Renal Progenitors for Personalized Modeling of Genetic Kidney Disorders.

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Lazzeri, Elena; Ronconi, Elisa; Angelotti, Maria Lucia; Peired, Anna; Mazzinghi, Benedetta; Becherucci, Francesca; Conti, Sara; Sansavini, Giulia; Sisti, Alessandro; Ravaglia, Fiammetta; Lombardi, Duccio; Provenzano, Aldesia; Manonelles, Anna; Cruzado, Josep M; Giglio, Sabrina; Roperto, Rosa Maria; Materassi, Marco; Lasagni, Laura; Romagnani, Paola

2015-08-01

The critical role of genetic and epigenetic factors in the pathogenesis of kidney disorders is gradually becoming clear, and the need for disease models that recapitulate human kidney disorders in a personalized manner is paramount. In this study, we describe a method to select and amplify renal progenitor cultures from the urine of patients with kidney disorders. Urine-derived human renal progenitors exhibited phenotype and functional properties identical to those purified from kidney tissue, including the capacity to differentiate into tubular cells and podocytes, as demonstrated by confocal microscopy, Western blot analysis of podocyte-specific proteins, and scanning electron microscopy. Lineage tracing studies performed with conditional transgenic mice, in which podocytes are irreversibly tagged upon tamoxifen treatment (NPHS2.iCreER;mT/mG), that were subjected to doxorubicin nephropathy demonstrated that renal progenitors are the only urinary cell population that can be amplified in long-term culture. To validate the use of these cells for personalized modeling of kidney disorders, renal progenitors were obtained from (1) the urine of children with nephrotic syndrome and carrying potentially pathogenic mutations in genes encoding for podocyte proteins and (2) the urine of children without genetic alterations, as validated by next-generation sequencing. Renal progenitors obtained from patients carrying pathogenic mutations generated podocytes that exhibited an abnormal cytoskeleton structure and functional abnormalities compared with those obtained from patients with proteinuria but without genetic mutations. The results of this study demonstrate that urine-derived patient-specific renal progenitor cultures may be an innovative research tool for modeling of genetic kidney disorders. Copyright © 2015 by the American Society of Nephrology.

THE PROGENITOR OF SUPERNOVA 2011dh/PTF11eon IN MESSIER 51

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Van Dyk, Schuyler D. [Spitzer Science Center/Caltech, Pasadena CA 91125 (United States); Li, Weidong; Cenko, S. Bradley; Silverman, Jeffrey M.; Filippenko, Alexei V. [Department of Astronomy, University of California, Berkeley, CA 94720-3411 (United States); Kasliwal, Mansi M.; Horesh, Assaf; Ofek, Eran O.; Quimby, Robert M.; Kulkarni, Shrinivas R. [Astronomy Department, California Institute of Technology, Pasadena, CA 91125 (United States); Kraus, Adam L. [Institute for Astronomy, University of Hawaii, Honolulu, HI 96822 (United States); Arcavi, Iair; Gal-Yam, Avishay; Yaron, Ofer; Polishook, David, E-mail: vandyk@ipac.caltech.edu [Department of Particle Physics and Astrophysics, Weizmann Institute of Science, 76100 Rehovot (Israel)

2011-11-10

We have identified a luminous star at the position of supernova (SN) 2011dh/PTF11eon, in pre-SN archival, multi-band images of the nearby, nearly face-on galaxy Messier 51 (M51) obtained by the Hubble Space Telescope with the Advanced Camera for Surveys. This identification has been confirmed, to the highest available astrometric precision, using a Keck-II adaptive-optics image. The available early-time spectra and photometry indicate that the SN is a stripped-envelope, core-collapse Type IIb, with a more compact progenitor (radius {approx} 10{sup 11} cm) than was the case for the well-studied SN IIb 1993J. We infer that the extinction to SN 2011dh and its progenitor arises from a low Galactic foreground contribution, and that the SN environment is of roughly solar metallicity. The detected object has absolute magnitude M{sup 0}{sub V} Almost-Equal-To -7.7 and effective temperature {approx}6000 K. The star's radius, {approx}10{sup 13} cm, is more extended than what has been inferred for the SN progenitor. We speculate that the detected star is either an unrelated star very near the position of the actual progenitor, or, more likely, the progenitor's companion in a mass-transfer binary system. The position of the detected star in a Hertzsprung-Russell diagram is consistent with an initial mass of 17-19 M{sub Sun }. The light of this star could easily conceal, even in the ultraviolet, the presence of a stripped, compact, very hot ({approx}10{sup 5} K), nitrogen-rich Wolf-Rayet star progenitor.

Characterization of a resident population of adventitial macrophage progenitor cells in postnatal vasculature.

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Psaltis, Peter J; Puranik, Amrutesh S; Spoon, Daniel B; Chue, Colin D; Hoffman, Scott J; Witt, Tyra A; Delacroix, Sinny; Kleppe, Laurel S; Mueske, Cheryl S; Pan, Shuchong; Gulati, Rajiv; Simari, Robert D

2014-07-18

Macrophages regulate blood vessel structure and function in health and disease. The origins of tissue macrophages are diverse, with evidence for local production and circulatory renewal. We identified a vascular adventitial population containing macrophage progenitor cells and investigated their origins and fate. Single-cell disaggregates from adult C57BL/6 mice were prepared from different tissues and tested for their capacity to form hematopoietic colony-forming units. Aorta showed a unique predilection for generating macrophage colony-forming units. Aortic macrophage colony-forming unit progenitors coexpressed stem cell antigen-1 and CD45 and were adventitially located, where they were the predominant source of proliferating cells in the aortic wall. Aortic Sca-1(+)CD45(+) cells were transcriptionally and phenotypically distinct from neighboring cells lacking stem cell antigen-1 or CD45 and contained a proliferative (Ki67(+)) Lin(-)c-Kit(+)CD135(-)CD115(+)CX3CR1(+)Ly6C(+)CD11b(-) subpopulation, consistent with the immunophenotypic profile of macrophage progenitors. Adoptive transfer studies revealed that Sca-1(+)CD45(+) adventitial macrophage progenitor cells were not replenished via the circulation from bone marrow or spleen, nor was their prevalence diminished by depletion of monocytes or macrophages by liposomal clodronate treatment or genetic deficiency of macrophage colony-stimulating factor. Rather adventitial macrophage progenitor cells were upregulated in hyperlipidemic ApoE(-/-) and LDL-R(-/-) mice, with adventitial transfer experiments demonstrating their durable contribution to macrophage progeny particularly in the adventitia, and to a lesser extent the atheroma, of atherosclerotic carotid arteries. The discovery and characterization of resident vascular adventitial macrophage progenitor cells provides new insight into adventitial biology and its participation in atherosclerosis and provokes consideration of the broader existence of local macrophage

Nf2-Yap signaling controls the expansion of DRG progenitors and glia during DRG development.

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Serinagaoglu, Yelda; Paré, Joshua; Giovannini, Marco; Cao, Xinwei

2015-02-01

Molecular mechanisms governing the maintenance and proliferation of dorsal root ganglia (DRG) progenitors are largely unknown. Here we reveal that the Hippo pathway regulates the expansion of DRG progenitors and glia during mammalian DRG development. The key effectors of this pathway, transcriptional coactivators Yap and Taz, are expressed in DRG progenitors and glia during DRG development but are at least partially inhibited from activating transcription. Aberrant YAP activation leads to overexpansion of DRG progenitor and glial populations. We further show that the Neurofibromatosis 2 (Nf2) tumor suppressor inhibits Yap during DRG development. Loss of Nf2 leads to similar phenotypes as does YAP hyperactivation, and deleting Yap suppresses these phenotypes. Our study demonstrates that Nf2-Yap signaling plays important roles in controlling the expansion of DRG progenitors and glia during DRG development. Copyright © 2014 Elsevier Inc. All rights reserved.

Hepatic progenitor cell resistance to TGF-β1's proliferative and apoptotic effects

International Nuclear Information System (INIS)

Clark, J. Brian; Rice, Lisa; Sadiq, Tim; Brittain, Evan; Song, Lujun; Wang Jian; Gerber, David A.

2005-01-01

The success of hepatocellular therapies using stem or progenitor cell populations is dependent upon multiple factors including the donor cell, microenvironment, and etiology of the liver injury. The following experiments investigated the impact of TGF-β1 on a previously described population of hepatic progenitor cells (HPC). The majority of the hepatic progenitor cells were resistant to endogenously produced TGF-β1's proapoptotic and anti-proliferative effects unlike more well-differentiated cellular populations (e.g., mature hepatocytes). Surprisingly, in vitro TGF-β1 supplementation significantly inhibited de novo hepatic progenitor cell colony formation possibly via an indirect mechanism(s). Therefore despite the HPC's direct resistance to supplemental TGF-β1, this cytokine's inhibitory effect on colony formation could have a potential negative impact on the use of these cells as a therapy for patients with liver disease

A High-mass Protobinary System with Spatially Resolved Circumstellar Accretion Disks and Circumbinary Disk

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Kraus, S.; Kluska, J.; Kreplin, A.; Bate, M.; Harries, T. J.; Hone, E.; Anugu, A. [School of Physics, Astrophysics Group, University of Exeter, Stocker Road, Exeter EX4 4QL (United Kingdom); Hofmann, K.-H.; Weigelt, G. [Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn (Germany); Monnier, J. D. [Department of Astronomy, University of Michigan, 311 West Hall, 1085 South University Avenue, Ann Arbor, MI 48109 (United States); De Wit, W. J. [ESO, Alonso de Cordova 3107, Vitacura, Santiago 19 (Chile); Wittkowski, M., E-mail: skraus@astro.ex.ac.uk [ESO, Karl-Schwarzschild-Str. 2, D-85748 Garching bei München (Germany)

2017-01-20

High-mass multiples might form via fragmentation of self-gravitational disks or alternative scenarios such as disk-assisted capture. However, only a few observational constraints exist on the architecture and disk structure of high-mass protobinaries and their accretion properties. Here, we report the discovery of a close (57.9 ± 0.2 mas = 170 au) high-mass protobinary, IRAS17216-3801, where our VLTI/GRAVITY+AMBER near-infrared interferometry allows us to image the circumstellar disks around the individual components with ∼3 mas resolution. We estimate the component masses to ∼20 and ∼18 M {sub ⊙} and find that the radial intensity profiles can be reproduced with an irradiated disk model, where the inner regions are excavated of dust, likely tracing the dust sublimation region in these disks. The circumstellar disks are strongly misaligned with respect to the binary separation vector, which indicates that the tidal forces did not have time to realign the disks, pointing toward a young dynamical age of the system. We constrain the distribution of the Br γ and CO-emitting gas using VLTI/GRAVITY spectro-interferometry and VLT/CRIRES spectro-astrometry and find that the secondary is accreting at a higher rate than the primary. VLT/NACO imaging shows L ′-band emission on (3–4)× larger scales than the binary separation, matching the expected dynamical truncation radius for the circumbinary disk. The IRAS17216-3801 system is ∼3× more massive and ∼5× more compact than other high-mass multiplies imaged at infrared wavelength and the first high-mass protobinary system where circumstellar and circumbinary dust disks could be spatially resolved. This opens exciting new opportunities for studying star–disk interactions and the role of multiplicity in high-mass star formation.

Amplification of neural stem cell proliferation by intermediate progenitor cells in Drosophila brain development

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Bello Bruno C

2008-02-01

Full Text Available Abstract Background In the mammalian brain, neural stem cells divide asymmetrically and often amplify the number of progeny they generate via symmetrically dividing intermediate progenitors. Here we investigate whether specific neural stem cell-like neuroblasts in the brain of Drosophila might also amplify neuronal proliferation by generating symmetrically dividing intermediate progenitors. Results Cell lineage-tracing and genetic marker analysis show that remarkably large neuroblast lineages exist in the dorsomedial larval brain of Drosophila. These lineages are generated by brain neuroblasts that divide asymmetrically to self renew but, unlike other brain neuroblasts, do not segregate the differentiating cell fate determinant Prospero to their smaller daughter cells. These daughter cells continue to express neuroblast-specific molecular markers and divide repeatedly to produce neural progeny, demonstrating that they are proliferating intermediate progenitors. The proliferative divisions of these intermediate progenitors have novel cellular and molecular features; they are morphologically symmetrical, but molecularly asymmetrical in that key differentiating cell fate determinants are segregated into only one of the two daughter cells. Conclusion Our findings provide cellular and molecular evidence for a new mode of neurogenesis in the larval brain of Drosophila that involves the amplification of neuroblast proliferation through intermediate progenitors. This type of neurogenesis bears remarkable similarities to neurogenesis in the mammalian brain, where neural stem cells as primary progenitors amplify the number of progeny they generate through generation of secondary progenitors. This suggests that key aspects of neural stem cell biology might be conserved in brain development of insects and mammals.

Wnt signaling induces differentiation of progenitor cells in organotypic keratinocyte cultures

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Liu Bob Y

2007-02-01

Full Text Available Abstract Background Interfollicular skin develops normally only when the activity of the progenitor cells in the basal layer is counterbalanced by the exit of cells into the suprabasal layers, where they differentiate and cornify to establish barrier function. Distinct stem and progenitor compartments have been demonstrated in hair follicles and sebaceous glands, but there are few data to describe the control of interfollicular progenitor cell activity. Wnt signaling has been shown to be an important growth-inducer of stem cell compartments in skin and many other tissues. Results Here, we test the effect of ectopic Wnt1 expression on the behavior of interfollicular progenitor cells in an organotypic culture model, and find that Wnt1 signaling inhibits their growth and promotes terminal differentiation. Conclusion These results are consistent with the phenotypes reported for transgenic mice engineered to have gain or loss of function of Wnt signaling in skin, which would recommend our culture model as an accurate one for molecular analysis. Since it is known that canonical ligands are expressed in skin, it is likely that this pathway normally regulates the balance of growth and differentiation, and suggests it could be important to pathogenesis.

PTEN Signaling in the Postnatal Perivascular Progenitor Niche Drives Medulloblastoma Formation.

Science.gov (United States)

Zhu, Guo; Rankin, Sherri L; Larson, Jon D; Zhu, Xiaoyan; Chow, Lionel M L; Qu, Chunxu; Zhang, Jinghui; Ellison, David W; Baker, Suzanne J

2017-01-01

Loss of the tumor suppressor gene PTEN exerts diverse outcomes on cancer in different developmental contexts. To gain insight into the effect of its loss on outcomes in the brain, we conditionally inactivated the murine Pten gene in neonatal neural stem/progenitor cells. Pten inactivation created an abnormal perivascular proliferative niche in the cerebellum that persisted in adult animals but did not progress to malignancy. Proliferating cells showed undifferentiated morphology and expressed the progenitor marker Nestin but not Math1, a marker of committed granule neuron progenitors. Codeletion of Pten and Trp53 resulted in fully penetrant medulloblastoma originating from the perivascular niche, which exhibited abnormal blood vessel networks and advanced neuronal differentiation of tumor cells. EdU pulse-chase experiments demonstrated a perivascular cancer stem cell population in Pten/Trp53 double mutant medulloblastomas. Genetic analyses revealed recurrent somatic inactivations of the tumor suppressor gene Ptch1 and a recapitulation of the sonic hedgehog subgroup of human medulloblastomas. Overall, our results showed that PTEN acts to prevent the proliferation of a progenitor niche in postnatal cerebellum predisposed to oncogenic induction of medulloblastoma. Cancer Res; 77(1); 123-33. ©2016 AACR. ©2016 American Association for Cancer Research.

[Stem and progenitor cells in biostructure of blood vessel walls].

Science.gov (United States)

Korta, Krzysztof; Kupczyk, Piotr; Skóra, Jan; Pupka, Artur; Zejler, Paweł; Hołysz, Marcin; Gajda, Mariusz; Nowakowska, Beata; Barć, Piotr; Dorobisz, Andrzej T; Dawiskiba, Tomasz; Szyber, Piotr; Bar, Julia

2013-09-18

Development of vascular and hematopoietic systems during organogenesis occurs at the same time. During vasculogenesis, a small part of cells does not undergo complete differentiation but stays on this level, "anchored" in tissue structures described as stem cell niches. The presence of blood vessels within tissue stem cell niches is typical and led to identification of niches and ensures that they are functioning. The three-layer biostructure of vessel walls for artery and vein, tunica: intima, media and adventitia, for a long time was defined as a mechanical barrier between vessel light and the local tissue environment. Recent findings from vascular biology studies indicate that vessel walls are dynamic biostructures, which are equipped with stem and progenitor cells, described as vascular wall-resident stem cells/progenitor cells (VW-SC/PC). Distinct zones for vessel wall harbor heterogeneous subpopulations of VW-SC/PC, which are described as "subendothelial or vasculogenic zones". Recent evidence from in vitro and in vivo studies show that prenatal activity of stem and progenitor cells is not only limited to organogenesis but also exists in postnatal life, where it is responsible for vessel wall homeostasis, remodeling and regeneration. It is believed that VW-SC/PC could be engaged in progression of vascular disorders and development of neointima. We would like to summarize current knowledge about mesenchymal and progenitor stem cell phenotype with special attention to distribution and biological properties of VW-SC/PC in biostructures of intima, media and adventitia niches. It is postulated that in the near future, niches for VW-SC/PC could be a good source of stem and progenitor cells, especially in the context of vessel tissue bioengineering as a new alternative to traditional revascularization therapies.

Stem and progenitor cells in biostructure of blood vessel walls

Directory of Open Access Journals (Sweden)

Krzysztof Korta

2013-09-01

Full Text Available Development of vascular and hematopoietic systems during organogenesis occurs at the same time. During vasculogenesis, a small part of cells does not undergo complete differentiation but stays on this level, “anchored” in tissue structures described as stem cell niches. The presence of blood vessels within tissue stem cell niches is typical and led to identification of niches and ensures that they are functioning. The three-layer biostructure of vessel walls for artery and vein, tunica: intima, media and adventitia, for a long time was defined as a mechanical barrier between vessel light and the local tissue environment. Recent findings from vascular biology studies indicate that vessel walls are dynamic biostructures, which are equipped with stem and progenitor cells, described as vascular wall-resident stem cells/progenitor cells (VW-SC/PC. Distinct zones for vessel wall harbor heterogeneous subpopulations of VW-SC/PC, which are described as “subendothelial or vasculogenic zones”. Recent evidence from in vitro and in vivo studies show that prenatal activity of stem and progenitor cells is not only limited to organogenesis but also exists in postnatal life, where it is responsible for vessel wall homeostasis, remodeling and regeneration. It is believed that VW-SC/PC could be engaged in progression of vascular disorders and development of neointima. We would like to summarize current knowledge about mesenchymal and progenitor stem cell phenotype with special attention to distribution and biological properties of VW-SC/PC in biostructures of intima, media and adventitia niches. It is postulated that in the near future, niches for VW-SC/PC could be a good source of stem and progenitor cells, especially in the context of vessel tissue bioengineering as a new alternative to traditional revascularization therapies.

Efficacy and Safety of Human Retinal Progenitor Cells

Science.gov (United States)

Semo, Ma'ayan; Haamedi, Nasrin; Stevanato, Lara; Carter, David; Brooke, Gary; Young, Michael; Coffey, Peter; Sinden, John; Patel, Sara; Vugler, Anthony

2016-01-01

Purpose We assessed the long-term efficacy and safety of human retinal progenitor cells (hRPC) using established rodent models. Methods Efficacy of hRPC was tested initially in Royal College of Surgeons (RCS) dystrophic rats immunosuppressed with cyclosporine/dexamethasone. Due to adverse effects of dexamethasone, this drug was omitted from a subsequent dose-ranging study, where different hRPC doses were tested for their ability to preserve visual function (measured by optokinetic head tracking) and retinal structure in RCS rats at 3 to 6 months after grafting. Safety of hRPC was assessed by subretinal transplantation into wild type (WT) rats and NIH-III nude mice, with analysis at 3 to 6 and 9 months after grafting, respectively. Results The optimal dose of hRPC for preserving visual function/retinal structure in dystrophic rats was 50,000 to 100,000 cells. Human retinal progenitor cells integrated/survived in dystrophic and WT rat retina up to 6 months after grafting and expressed nestin, vimentin, GFAP, and βIII tubulin. Vision and retinal structure remained normal in WT rats injected with hRPC and there was no evidence of tumors. A comparison between dexamethasone-treated and untreated dystrophic rats at 3 months after grafting revealed an unexpected reduction in the baseline visual acuity of dexamethasone-treated animals. Conclusions Human retinal progenitor cells appear safe and efficacious in the preclinical models used here. Translational Relevance Human retinal progenitor cells could be deployed during early stages of retinal degeneration or in regions of intact retina, without adverse effects on visual function. The ability of dexamethasone to reduce baseline visual acuity in RCS dystrophic rats has important implications for the interpretation of preclinical and clinical cell transplant studies. PMID:27486556

Postnatal epithelium and mesenchyme stem/progenitor cells in bioengineered amelogenesis and dentinogenesis.

Science.gov (United States)

Jiang, Nan; Zhou, Jian; Chen, Mo; Schiff, Michael D; Lee, Chang H; Kong, Kimi; Embree, Mildred C; Zhou, Yanheng; Mao, Jeremy J

2014-02-01

Rodent incisors provide a classic model for studying epithelial-mesenchymal interactions in development. However, postnatal stem/progenitor cells in rodent incisors have not been exploited for tooth regeneration. Here, we characterized postnatal rat incisor epithelium and mesenchyme stem/progenitor cells and found that they formed enamel- and dentin-like tissues in vivo. Epithelium and mesenchyme cells were harvested separately from the apical region of postnatal 4-5 day rat incisors. Epithelial and mesenchymal phenotypes were confirmed by immunocytochemistry, CFU assay and/or multi-lineage differentiation. CK14+, Sox2+ and Lgr5+ epithelium stem cells from the cervical loop enhanced amelogenin and ameloblastin expression upon BMP4 or FGF3 stimulation, signifying their differentiation towards ameloblast-like cells, whereas mesenchyme stem/progenitor cells upon BMP4, BMP7 and Wnt3a treatment robustly expressed Dspp, a hallmark of odontoblastic differentiation. We then control-released microencapsulated BMP4, BMP7 and Wnt3a in transplants of epithelium and mesenchyme stem/progenitor cells in the renal capsule of athymic mice in vivo. Enamel and dentin-like tissues were generated in two integrated layers with specific expression of amelogenin and ameloblastin in the newly formed, de novo enamel-like tissue, and DSP in dentin-like tissue. These findings suggest that postnatal epithelium and mesenchyme stem/progenitor cells can be primed towards bioengineered tooth regeneration. Copyright © 2013 Elsevier Ltd. All rights reserved.

Probing Minor-merger-driven Star Formation In Early-type Galaxies Using Spatially-resolved Spectro-photometric Studies

Science.gov (United States)

Kaviraj, Sugata; Crockett, M.; Silk, J.; O'Connell, R. W.; Whitmore, B.; Windhorst, R.; Cappellari, M.; Bureau, M.; Davies, R.

2012-01-01

Recent studies that leverage the rest-frame ultraviolet (UV) spectrum have revealed widespread recent star formation in early-type galaxies (ETGs), traditionally considered to be old, passively-evolving systems. This recent star formation builds 20% of the ETG stellar mass after z 1, driven by repeated minor mergers between ETGs and small, gas-rich satellites. We demonstrate how spatially-resolved studies, using a combination of high-resolution UV-optical imaging and integral-field spectroscopy (IFS), is a powerful tool to quantify the assembly history of individual ETGs and elucidate the poorly-understood minor-merger process. Using a combination of WFC3 UV-optical (2500-8200 angstroms) imaging and IFS from the SAURON project of the ETG NGC 4150, we show that this galaxy experienced a merger with mass ratio 1:15 around 0.9 Gyr ago, which formed 3% of its stellar mass and a young kinematically-decoupled core. A UV-optical analysis of its globular cluster system shows that the bulk of the stars locked up in these clusters likely formed 6-7 Gyrs in the past. We introduce a new HST-WFC3 programme, approved in Cycle 19, which will leverage similar UV-optical imaging of a representative sample of nearby ETGs from SAURON to study the recent star formation and its drivers in unprecedented detail and put definitive constraints on minor-merger-driven star formation in massive galaxies at late epochs.

Human Pluripotent Stem Cell Differentiation into Functional Epicardial Progenitor Cells

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Juan Antonio Guadix

2017-12-01

Full Text Available Summary: Human pluripotent stem cells (hPSCs are widely used to study cardiovascular cell differentiation and function. Here, we induced differentiation of hPSCs (both embryonic and induced to proepicardial/epicardial progenitor cells that cover the heart during development. Addition of retinoic acid (RA and bone morphogenetic protein 4 (BMP4 promoted expression of the mesodermal marker PDGFRα, upregulated characteristic (proepicardial progenitor cell genes, and downregulated transcription of myocardial genes. We confirmed the (proepicardial-like properties of these cells using in vitro co-culture assays and in ovo grafting of hPSC-epicardial cells into chick embryos. Our data show that RA + BMP4-treated hPSCs differentiate into (proepicardial-like cells displaying functional properties (adhesion and spreading over the myocardium of their in vivo counterpart. The results extend evidence that hPSCs are an excellent model to study (proepicardial differentiation into cardiovascular cells in human development and evaluate their potential for cardiac regeneration. : The authors have shown that hPSCs can be instructed in vitro to differentiate into a specific cardiac embryonic progenitor cell population called the proepicardium. Proepicardial cells are required for normal formation of the heart during development and might contribute to the development of cell-based therapies for heart repair. Keywords: human pluripotent stem cells, proepicardium, progenitor cells, cardiovascular, differentiation

Spatially-resolved in-situ quantification of biofouling using optical coherence tomography (OCT) and 3D image analysis in a spacer filled channel

KAUST Repository

Fortunato, Luca

2016-11-21

The use of optical coherence tomography (OCT) to investigate biomass in membrane systems has increased with time. OCT is able to characterize the biomass in-situ and non-destructively. In this study, a novel approach to process three-dimensional (3D) OCT scans is proposed. The approach allows obtaining spatially-resolved detailed structural biomass information. The 3D biomass reconstruction enables analysis of the biomass only, obtained by subtracting the time zero scan to all images. A 3D time series analysis of biomass development in a spacer filled channel under representative conditions (cross flow velocity) for a spiral wound membrane element was performed. The flow cell was operated for five days with monitoring of ultrafiltration membrane performance: feed channel pressure drop and permeate flux. The biomass development in the flow cell was detected by OCT before a performance decline was observed. Feed channel pressure drop continuously increased with increasing biomass volume, while flux decline was mainly affected in the initial phase of biomass accumulation. The novel OCT imaging approach enabled the assessment of spatial biomass distribution in the flow cell, discriminating the total biomass volume between the membrane, feed spacer and glass window. Biomass accumulation was stronger on the feed spacer during the early stage of biofouling, impacting the feed channel pressure drop stronger than permeate flux.

The initial masses of the red supergiant progenitors to Type II supernovae

Science.gov (United States)

Davies, Ben; Beasor, Emma R.

2018-02-01

There are a growing number of nearby supernovae (SNe) for which the progenitor star is detected in archival pre-explosion imaging. From these images it is possible to measure the progenitor's brightness a few years before explosion, and ultimately estimate its initial mass. Previous work has shown that II-P and II-L SNe have red supergiant (RSG) progenitors, and that the range of initial masses for these progenitors seems to be limited to ≲ 17 M⊙. This is in contrast with the cut-off of 25-30 M⊙ predicted by evolutionary models, a result that is termed the `red supergiant problem'. Here we investigate one particular source of systematic error present in converting pre-explosion photometry into an initial mass, which of the bolometric correction (BC) used to convert a single-band flux into a bolometric luminosity. We show, using star clusters, that RSGs evolve to later spectral types as they approach SN, which in turn causes the BC to become larger. Failure to account for this results in a systematic underestimate of a star's luminosity, and hence its initial mass. Using our empirically motivated BCs we reappraise the II-P and II-L SNe that have their progenitors detected in pre-explosion imaging. Fitting an initial mass function to these updated masses results in an increased upper mass cut-off of Mhi = 19.0^{+2.5}_{-1.3} M⊙, with a 95 per cent upper confidence limit of <27 M⊙. Accounting for finite sample size effects and systematic uncertainties in the mass-luminosity relationship raises the cut-off to Mhi = 25 M⊙ (<33 M⊙, 95 per cent confidence). We therefore conclude that there is currently no strong evidence for `missing' high-mass progenitors to core-collapse SNe.

Electroacupuncture Promotes Proliferation of Amplifying Neural Progenitors and Preserves Quiescent Neural Progenitors from Apoptosis to Alleviate Depressive-Like and Anxiety-Like Behaviours

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Liu Yang

2014-01-01

Full Text Available The present study was designed to investigate the effects of electroacupuncture (EA on depressive-like and anxiety-like behaviours and neural progenitors in the hippocampal dentate gyrus (DG in a chronic unpredictable stress (CUS rat model of depression. After being exposed to a CUS procedure for 2 weeks, rats were subjected to EA treatment, which was performed on acupoints Du-20 (Bai-Hui and GB-34 (Yang-Ling-Quan, once every other day for 15 consecutive days (including 8 treatments, with each treatment lasting for 30 min. The behavioural tests (i.e., forced swimming test, elevated plus-maze test, and open-field entries test revealed that EA alleviated the depressive-like and anxiety-like behaviours of the stressed rats. Immunohistochemical results showed that proliferative cells (BrdU-positive in the EA group were significantly larger in number compared with the Model group. Further, the results showed that EA significantly promoted the proliferation of amplifying neural progenitors (ANPs and simultaneously inhibited the apoptosis of quiescent neural progenitors (QNPs. In a word, the mechanism underlying the antidepressant-like effects of EA is associated with enhancement of ANPs proliferation and preserving QNPs from apoptosis.

MyT1 Counteracts the Neural Progenitor Program to Promote Vertebrate Neurogenesis

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Francisca F. Vasconcelos

2016-10-01

Full Text Available The generation of neurons from neural stem cells requires large-scale changes in gene expression that are controlled to a large extent by proneural transcription factors, such as Ascl1. While recent studies have characterized the differentiation genes activated by proneural factors, less is known on the mechanisms that suppress progenitor cell identity. Here, we show that Ascl1 induces the transcription factor MyT1 while promoting neuronal differentiation. We combined functional studies of MyT1 during neurogenesis with the characterization of its transcriptional program. MyT1 binding is associated with repression of gene transcription in neural progenitor cells. It promotes neuronal differentiation by counteracting the inhibitory activity of Notch signaling at multiple levels, targeting the Notch1 receptor and many of its downstream targets. These include regulators of the neural progenitor program, such as Hes1, Sox2, Id3, and Olig1. Thus, Ascl1 suppresses Notch signaling cell-autonomously via MyT1, coupling neuronal differentiation with repression of the progenitor fate.

Generation of Induced Progenitor-like Cells from Mature Epithelial Cells Using Interrupted Reprogramming

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Li Guo

2017-12-01

Full Text Available Summary: A suitable source of progenitor cells is required to attenuate disease or affect cure. We present an “interrupted reprogramming” strategy to generate “induced progenitor-like (iPL cells” using carefully timed expression of induced pluripotent stem cell reprogramming factors (Oct4, Sox2, Klf4, and c-Myc; OSKM from non-proliferative Club cells. Interrupted reprogramming allowed controlled expansion yet preservation of lineage commitment. Under clonogenic conditions, iPL cells expanded and functioned as a bronchiolar progenitor-like population to generate mature Club cells, mucin-producing goblet cells, and cystic fibrosis transmembrane conductance regulator (CFTR-expressing ciliated epithelium. In vivo, iPL cells can repopulate CFTR-deficient epithelium. This interrupted reprogramming process could be metronomically applied to achieve controlled progenitor-like proliferation. By carefully controlling the duration of expression of OSKM, iPL cells do not become pluripotent, and they maintain their memory of origin and retain their ability to efficiently return to their original phenotype. A generic technique to produce highly specified populations may have significant implications for regenerative medicine. : In this article Waddell, Nagy, and colleagues present an “interrupted reprogramming” strategy to produce highly specified functional “induced progenitor-like cells” from mature quiescent cells. They propose that careful control of the duration of transient expression of iPSC reprogramming factors (OSKM allows controlled expansion yet preservation of parental lineage without traversing the pluripotent state. Keywords: generation of induced progenitor-like cells

THE AGES OF TYPE Ia SUPERNOVA PROGENITORS

International Nuclear Information System (INIS)

Brandt, Timothy D.; Aubourg, Eric; Strauss, Michael A.; Tojeiro, Rita; Heavens, Alan; Jimenez, Raul

2010-01-01

Using light curves and host galaxy spectra of 101 Type Ia supernovae (SNe Ia) with redshift z ∼ 2.4 Gyr. We find that each channel contributes roughly half of the Type Ia rate in our reference sample. We also construct the average spectra of high-stretch and low-stretch SN Ia host galaxies, and find that the difference of these spectra looks like a main-sequence B star with nebular emission lines indicative of star formation. This supports our finding that there are two populations of SNe Ia, and indicates that the progenitors of high-stretch supernovae are at the least associated with very recent star formation in the last few tens of Myr. Our results provide valuable constraints for models of Type Ia progenitors and may help improve the calibration of SNe Ia as standard candles.

Establishment of bipotent progenitor cell clone from rat skeletal muscle.

Science.gov (United States)

Murakami, Yousuke; Yada, Erica; Nakano, Shin-ichi; Miyagoe-Suzuki, Yuko; Hosoyama, Tohru; Matsuwaki, Takashi; Yamanouchi, Keitaro; Nishihara, Masugi

2011-12-01

The present study describes the isolation, cloning and characterization of adipogenic progenitor cells from rat skeletal muscle. Among the obtained 10 clones, the most highly adipogenic progenitor, 2G11 cells, were further characterized. In addition to their adipogenicity, 2G11 cells retain myogenic potential as revealed by formation of multinucleated myotubes when co-cultured with myoblasts. 2G11 cells were resistant to an inhibitory effect of basic fibroblast growth factor on adipogenesis, while adipogenesis of widely used preadipogenic cell line, 3T3-L1 cells, was suppressed almost completely by the same treatment. In vivo transplantation experiments revealed that 2G11 cells are able to possess both adipogenicity and myogenicity in vivo. These results indicate the presence of bipotent progenitor cells in rat skeletal muscle, and suggest that such cells may contribute to ectopic fat formation in skeletal muscle. © 2011 The Authors. Animal Science Journal © 2011 Japanese Society of Animal Science.

Role of nutrients and mTOR signaling in the regulation of pancreatic progenitors development

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Lynda Elghazi

2017-06-01

Full Text Available Objective: Poor fetal nutrition increases the risk of type 2 diabetes in the offspring at least in part by reduced embryonic β-cell growth and impaired function. However, it is not entirely clear how fetal nutrients and growth factors impact β-cells during development to alter glucose homeostasis and metabolism later in life. The current experiments aimed to test the impact of fetal nutrients and growth factors on endocrine development and how these signals acting on mTOR signaling regulate β-cell mass and glucose homeostasis. Method: Pancreatic rudiments in culture were used to study the role of glucose, growth factors, and amino acids on β-cell development. The number and proliferation of pancreatic and endocrine progenitor were assessed in the presence or absence of rapamycin. The impact of mTOR signaling in vivo on pancreas development and glucose homeostasis was assessed in models deficient for mTOR or Raptor in Pdx1 expressing pancreatic progenitors. Results: We found that amino acid concentrations, and leucine in particular, enhance the number of pancreatic and endocrine progenitors and are essential for growth factor induced proliferation. Rapamycin, an mTORC1 complex inhibitor, reduced the number and proliferation of pancreatic and endocrine progenitors. Mice lacking mTOR in pancreatic progenitors exhibited hyperglycemia in neonates, hypoinsulinemia and pancreatic agenesis/hypoplasia with pancreas rudiments containing ductal structures lacking differentiated acinar and endocrine cells. In addition, loss of mTORC1 by deletion of raptor in pancreatic progenitors reduced pancreas size with reduced number of β-cells. Conclusion: Together, these results suggest that amino acids concentrations and in particular leucine modulates growth responses of pancreatic and endocrine progenitors and that mTOR signaling is critical for these responses. Inactivation of mTOR and raptor in pancreatic progenitors suggested that alterations in some of

The Energy-Water Nexus: Spatially-Resolved Analysis of the Potential for Desalinating Brackish Groundwater by Use of Solar Energy

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Jill B. Kjellsson

2015-06-01

Full Text Available This research looks at coupling desalination with renewable energy sources to create a high-value product (treated water from two low value resources (brackish groundwater and intermittent solar energy. Desalination of brackish groundwater is already being considered as a potential new water supply in Texas. This research uses Texas as a testbed for spatially-resolved analysis techniques while considering depth to brackish groundwater, water quality, and solar radiation across Texas to determine the locations with the best potential for integrating solar energy with brackish groundwater desalination. The framework presented herein can be useful for policymakers, regional planners, and project developers as they consider where to site desalination facilities coupled with solar photovoltaics. Results suggest that the northwestern region of Texas—with abundant sunshine and groundwater at relatively shallow depths and low salinity in areas with freshwater scarcity—has the highest potential for solar powered desalination. The range in capacity for solar photovoltaic powered reverse osmosis desalination was found to be 1.56 × 10—6 to 2.93 × 10—5 cubic meters of water per second per square meter of solar panel (m3/s/m2.

Nephron progenitor cell death elicits a limited compensatory response associated with interstitial expansion in the neonatal kidney

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Sree Deepthi Muthukrishnan

2018-01-01

Full Text Available The final nephron number in an adult kidney is regulated by nephron progenitor cell availability and collecting duct branching in the fetal period. Fetal environmental perturbations that cause reductions in cell numbers in these two compartments result in low nephron endowment. Previous work has shown that maternal dietary factors influence nephron progenitor cell availability, with both caloric restriction and protein deprivation leading to reduced cell numbers through apoptosis. In this study, we evaluate the consequences of inducing nephron progenitor cell death on progenitor niche dynamics and on nephron endowment. Depletion of approximately 40% of nephron progenitor cells by expression of diphtheria toxin A at embryonic day 15 in the mouse results in 10-20% nephron reduction in the neonatal period. Analysis of cell numbers within the progenitor cell pool following induction of apoptosis reveals a compensatory response in which surviving progenitor cells increase their proliferation and replenish the niche. The proliferative response is temporally associated with infiltration of macrophages into the nephrogenic zone. Colony stimulating factor 1 (CSF1 has a mitogenic effect on nephron progenitor cells, providing a potential explanation for the compensatory proliferation. However, CSF1 also promotes interstitial cell proliferation, and the compensatory response is associated with interstitial expansion in recovering kidneys which can be pharmacologically inhibited by treatment with clodronate liposomes. Our findings suggest that the fetal kidney employs a macrophage-dependent compensatory regenerative mechanism to respond to acute injury caused by death of nephron progenitor cells, but that this regenerative response is associated with neonatal interstitial expansion.

Fast time-resolved aerosol collector: proof of concept

Science.gov (United States)

Yu, X.-Y.; Cowin, J. P.; Iedema, M. J.; Ali, H.

2010-10-01

Atmospheric particles can be collected in the field on substrates for subsequent laboratory analysis via chemically sensitive single particle methods such as scanning electron microscopy with energy dispersive x-ray analysis. With moving substrates time resolution of seconds to minutes can be achieved. In this paper, we demonstrate how to increase the time resolution when collecting particles on a substrate to a few milliseconds to provide real-time information. Our fast time-resolved aerosol collector ("Fast-TRAC") microscopically observes the particle collection on a substrate and records an on-line video. Particle arrivals are resolved to within a single frame (4-17 ms in this setup), and the spatial locations are matched to the subsequent single particle analysis. This approach also provides in-situ information on particle size and number concentration. Applications are expected in airborne studies of cloud microstructure, pollution plumes, and surface long-term monitoring.

Continuous-flow liquid microjunction surface sampling probe connected on-line with high-performance liquid chromatography/mass spectrometry for spatially resolved analysis of small molecules and proteins.

Science.gov (United States)

Van Berkel, Gary J; Kertesz, Vilmos

2013-06-30

A continuous-flow liquid microjunction surface sampling probe extracts soluble material from surfaces for direct ionization and detection by mass spectrometry. Demonstrated here is the on-line coupling of such a probe with high-performance liquid chromatography/mass spectrometry (HPLC/MS) enabling extraction, separation and detection of small molecules and proteins from surfaces in a spatially resolved (~0.5 mm diameter spots) manner. A continuous-flow liquid microjunction surface sampling probe was connected to a six-port, two-position valve for extract collection and injection to an HPLC column. A QTRAP® 5500 hybrid triple quadrupole linear ion trap equipped with a Turbo V™ ion source operated in positive electrospray ionization (ESI) mode was used for all experiments. The system operation was tested with the extraction, separation and detection of propranolol and associated metabolites from drug dosed tissues, caffeine from a coffee bean, cocaine from paper currency, and proteins from dried sheep blood spots on paper. Confirmed in the tissue were the parent drug and two different hydroxypropranolol glucuronides. The mass spectrometric response for these compounds from different locations in the liver showed an increase with increasing extraction time (5, 20 and 40 s). For on-line separation and detection/identification of extracted proteins from dried sheep blood spots, two major protein peaks dominated the chromatogram and could be correlated with the expected masses for the hemoglobin α and β chains. Spatially resolved sampling, separation, and detection of small molecules and proteins from surfaces can be accomplished using a continuous-flow liquid microjunction surface sampling probe coupled on-line with HPLC/MS detection. Published in 2013. This article is a U.S. Government work and is in the public domain in the USA.

Regulation of Mammary Progenitor Cells by p53 and Parity

Science.gov (United States)

2011-01-01

quantitative PCR system (Stratagene). To knockdown Notch1 in TM40A cells, siRNA (s70698 and s70700) were purchased from Ambion. s70698 siRNA sense sequence: 5...hours after transfect ion and real-tim e quantitative P CR was used to confirm the knockdown efficiency. Results Label and chase progenitor cells...cells contained 0.8% o f DsRed positiv e (DsR +) progenitor cells (Fig. 1B). The mammosphere-forming capacity of DsR+ cells is 3.8-fold greater

Enhanced generation of retinal progenitor cells from human retinal pigment epithelial cells induced by amniotic fluid.

Science.gov (United States)

Sanie-Jahromi, Fatemeh; Ahmadieh, Hamid; Soheili, Zahra-Soheila; Davari, Maliheh; Ghaderi, Shima; Kanavi, Mozhgan Rezaei; Samiei, Shahram; Deezagi, Abdolkhalegh; Pakravesh, Jalil; Bagheri, Abouzar

2012-04-10

Retinal progenitor cells are a convenient source of cell replacement therapy in retinal degenerative disorders. The purpose of this study was to evaluate the expression patterns of the homeobox genes PAX6 and CHX10 (retinal progenitor markers) during treatment of human retinal pigment epithelium (RPE) cells with amniotic fluid (AF), RPE cells harvested from neonatal cadaver globes were cultured in a mixture of DMEM and Ham's F12 supplemented with 10% FBS. At different passages, cells were trypsinized and co-cultured with 30% AF obtained from normal fetuses of 1416 weeks gestational age. Compared to FBS-treated controls, AF-treated cultures exhibited special morphological changes in culture, including appearance of spheroid colonies, improved initial cell adhesion and ordered cell alignment. Cell proliferation assays indicated a remarkable increase in the proliferation rate of RPE cells cultivated in 30% AF-supplemented medium, compared with those grown in the absence of AF. Immunocytochemical analyses exhibited nuclear localization of retinal progenitor markers at a ratio of 33% and 27% for CHX10 and PAX6, respectively. This indicated a 3-fold increase in retinal progenitor markers in AF-treated cultures compared to FBS-treated controls. Real-time PCR data of retinal progenitor genes (PAX6, CHX10 and VSX-1) confirmed these results and demonstrated AF's capacity for promoting retinal progenitor cell generation. Taken together, the results suggest that AF significantly promotes the rate of retinal progenitor cell generation, indicating that AF can be used as an enriched supplement for serum-free media used for the in vitro propagation of human progenitor cells.

EMMPRIN overexpression in SVZ neural progenitor cells increases their migration towards ischemic cortex.

Science.gov (United States)

Kanemitsu, Michiko; Tsupykov, Oleg; Potter, Gaël; Boitard, Michael; Salmon, Patrick; Zgraggen, Eloisa; Gascon, Eduardo; Skibo, Galina; Dayer, Alexandre G; Kiss, Jozsef Z

2017-11-01

Stimulation of endogenous neurogenesis and recruitment of neural progenitors from the subventricular zone (SVZ) neurogenic site may represent a useful strategy to improve regeneration in the ischemic cortex. Here, we tested whether transgenic overexpression of extracellular matrix metalloproteinase inducer (EMMPRIN), the regulator of matrix metalloproteinases (MMPs) expression, in endogenous neural progenitor cells (NPCs) in the subventricular zone (SVZ) could increase migration towards ischemic injury. For this purpose, we applied a lentivector-mediated gene transfer system. We found that EMMPRIN-transduced progenitors exhibited enhanced MMP-2 activity in vitro and showed improved motility in 3D collagen gel as well as in cortical slices. Using a rat model of neonatal ischemia, we showed that EMMPRIN overexpressing SVZ cells invade the injured cortical tissue more efficiently than controls. Our results suggest that EMMPRIN overexpression could be suitable approach to improve capacities of endogenous or transplanted progenitors to invade the injured cortex. Copyright © 2017 Elsevier Inc. All rights reserved.

Proliferative status of primitive hematopoietic progenitors from patients with acute myelogenous leukemia (AML).

Science.gov (United States)

Guan, Y; Hogge, D E

2000-12-01

One possible explanation for the competitive advantage that malignant cells in patients with acute myelogenous leukemia (AML) appear to have over normal hematopoietic elements is that leukemic progenitors proliferate more rapidly than their normal progenitor cell counterparts. To test this hypothesis, an overnight 3H-thymidine (3H-Tdr) suicide assay was used to analyze the proliferative status of malignant progenitors detected in both colony-forming cell (CFC) and long-term culture initiating cell (LTC-IC) assays from the peripheral blood of nine patients with newly diagnosed AML. Culture of AML cells in serum-free medium with 100 ng/ml Steel factor (SF), 20 ng/ml interleukin 3 (IL-3) and 20 ng/ml granulocyte colony-stimulating factor (G-CSF) for 16-24 h maintained the number of AML-CFC and LTC-IC at near input values (mean % input +/- s.d. for CFC and LTC-IC were 78 +/- 33 and 126 +/- 53, respectively). The addition of 20 muCi/ml high specific activity 3H-Tdr to these cultures reduced the numbers of both progenitor cell types from most of the patient samples substantially: mean % kill +/- s.d. for AML-CFC and LTC-IC were 64 +/- 27 and 82 +/- 16, respectively, indicating that a large proportion of both progenitor populations were actively cycling. FISH analysis of colonies from CFC and LTC-IC assays confirmed that most cytogenetically abnormal CFC and LTC-IC were actively cycling (mean % kill +/- s.d.: 68 +/- 26 and 85 +/- 13, respectively). Interestingly, in six patient samples where a significant number of cytogenetically normal LTC-ICs were detected, the % kill of these cells (74 +/- 20) was similar to that of the abnormal progenitors. These data contrast with the predominantly quiescent cell cycle status of CFC and LTC-IC previously observed in steady-state peripheral blood from normal individuals but also provide evidence that a significant proportion of primitive malignant progenitors from AML patients are quiescent and therefore may be resistant to standard

Beyond Conceptual Knowledge: The Impact of Children’s Theory-of-Mind on Dyadic Spatial Tasks

Science.gov (United States)

Viana, Karine M. P.; Zambrana, Imac M.; Karevold, Evalill B.; Pons, Francisco

2016-01-01

Recent studies show that Theory of Mind (ToM) has implications for children’s social competences and psychological well-being. Nevertheless, although it is well documented that children overall take advantage when they have to resolve cognitive problems together with a partner, whether individual difference in ToM is one of the mechanisms that could explain cognitive performances produced in social interaction has received little attention. This study examines to what extent ToM explains children’s spatial performances in a dyadic situation. The sample includes 66 boys and girls between the ages of 5–9 years, who were tested for their ToM and for their competence to resolve a Spatial task involving mental rotation and spatial perspective taking, first individually and then in a dyadic condition. Results showed, in accordance with previous research, that children performed better on the Spatial task when they resolved it with a partner. Specifically, children’s ToM was a better predictor of their spatial performances in the dyadic condition than their age, gender, and spatial performances in the individual setting. The findings are discussed in terms of the relation between having a conceptual understanding of the mind and the practical implications of this knowledge for cognitive performances in social interaction regarding mental rotation and spatial perspective taking. PMID:27812344

The poster as modernist progenitor

Directory of Open Access Journals (Sweden)

Katherine Hauser

2015-12-01

Full Text Available Ruth E. Iskin’s The Poster: Art, Advertising. Design, and Collecting, 1860s-1900s positions the late-nineteenth-century advertising poster as the progenitor of valued modernist practices typically attached solely to photography and film. Modernist biases separating high art from mass culture account for scholars ignoring posters, however the poster ushered in an innovative reductive graphic style as well as pioneered the notion of multiple originals.

Culture and Characterization of Circulating Endothelial Progenitor Cells in Patients with Renal Cell Carcinoma.

Science.gov (United States)

Gu, Wenyu; Sun, Wei; Guo, Changcheng; Yan, Yang; Liu, Min; Yao, Xudong; Yang, Bin; Zheng, Junhua

2015-07-01

Although emerging evidence demonstrates increased circulating endothelial progenitor cells in patients with solid tumors, to our knowledge it is still unknown whether such cells can be cultured from patients with highly angiogenic renal cell carcinoma. We cultured and characterized circulating endothelial progenitor cells from patients with renal cell carcinoma. The circulating endothelial progenitor cell level (percent of CD45(-)CD34(+) VEGF-R2(+) cells in total peripheral blood mononuclear cells) was quantified in 47 patients with renal cell carcinoma and 40 healthy controls. Peripheral blood mononuclear cells were then isolated from 33 patients with renal cell carcinoma and 30 healthy controls to culture and characterize circulating endothelial progenitor cells. The circulating endothelial progenitor cell level was significantly higher in patients with renal cell carcinoma than in healthy controls (0.276% vs 0.086%, p cells first emerged significantly earlier in patient than in control preparations (6.72 vs 14.67 days, p culture success rate (87.8% vs 40.0% of participants) and the number of colonies (10.06 vs 1.83) were significantly greater for patients than for controls (each p cell level correlated positively with the number of patient colonies (r = 0.762, p Cells cultured from patients and controls showed a similar growth pattern, immunophenotype, ability to uptake Ac-LDL and bind lectin, and form capillary tubes in vitro. However, significantly more VEGF-R2(+) circulating endothelial progenitor cells were found in preparations from patients with renal cell carcinoma than from healthy controls (21.1% vs 13.4%, p cell colonies, a higher cell culture success rate and more colonies were found for patients with renal cell carcinoma than for healthy controls. Results indicate the important significance of VEGF-R2(+) circulating endothelial progenitors in patients with renal cell carcinoma. Copyright © 2015 American Urological Association Education and Research

EVLA OBSERVATIONS CONSTRAIN THE ENVIRONMENT AND PROGENITOR SYSTEM OF Type Ia SUPERNOVA 2011fe

International Nuclear Information System (INIS)

Chomiuk, Laura; Soderberg, Alicia M.; Moe, Maxwell; Margutti, Raffaella; Fong, Wen-fai; Dittmann, Jason A.; Chevalier, Roger A.; Rupen, Michael P.; Badenes, Carles; Fransson, Claes

2012-01-01

We report unique Expanded Very Large Array observations of SN 2011fe representing the most sensitive radio study of a Type Ia supernova to date. Our data place direct constraints on the density of the surrounding medium at radii ∼10 15 -10 16 cm, implying an upper limit on the mass loss rate from the progenitor system of M-dot -10 M ☉ yr -1 (assuming a wind speed of 100 km s –1 ) or expansion into a uniform medium with density n CSM ∼ –3 . Drawing from the observed properties of non-conservative mass transfer among accreting white dwarfs, we use these limits on the density of the immediate environs to exclude a phase space of possible progenitor systems for SN 2011fe. We rule out a symbiotic progenitor system and also a system characterized by high accretion rate onto the white dwarf that is expected to give rise to optically thick accretion winds. Assuming that a small fraction, 1%, of the mass accreted is lost from the progenitor system, we also eliminate much of the potential progenitor parameter space for white dwarfs hosting recurrent novae or undergoing stable nuclear burning. Therefore, we rule out much of the parameter space associated with popular single degenerate progenitor models for SN 2011fe, leaving a limited phase space largely inhabited by some double degenerate systems, as well as exotic single degenerates with a sufficient time delay between mass accretion and SN explosion.

Cardiac Progenitor Cell Extraction from Human Auricles

KAUST Repository

Di Nardo, Paolo; Pagliari, Francesca

2017-01-01

by precursor cells mostly embedded into the heart apex and in the atria. We have shown that an elective region of progenitor cell embedding is represented by the auricles, non-contractile atria appendages that can be easily sampled without harming the patient

An Interferometric Study of the Post-AGB Binary 89 Herculis. 1: Spatially Resolving the Continuum Circumstellar Environment at Optical and Near-IR Wavelengths with the VLTI, NPOI, IOTA, PTI, and the CHARA Array

Science.gov (United States)

2013-01-01

Herculis I. Spatially resolving the continuum circumstellar environment at optical and near-IR wavelengths with the VLTI, NPOI, IOTA , PTI, and the CHARA...public release; distribution unlimited 13. SUPPLEMENTARY NOTES A&A 559, A111 (2013) 14. ABSTRACT 15. SUBJECT TERMS 16. SECURITY CLASSIFICATION...Array ( IOTA ) and the Center for High Angular Resolution Astronomy (CHARA) Array, covering 0.5 to 2.2 μm and with baselines from 15 to 278 m. Here we

In vitro studies on the radiosensitivity of multipotent hemopoietic progenitors in canine bone marrow

International Nuclear Information System (INIS)

Kreja, L.; Weinsheimer, W.; Nothdurft, W.

1991-01-01

The in vitro radiation response to 280-kV x-rays (does rate 72 cGy/min) of multipotent hemopoietic progenitor cells, mixed colony-forming units (CFU-mix), from canine bone marrow was assayed and compared to the radiation response characteristics of early erythroid progenitors, erythroid burst-forming units (BFU-E). To improve the colony-forming efficiency, the effect of various bone marrow cell separation techniques on colony formation of both progenitors was examined. The separation of bone marrow aspirates by discontinuous buoyant gradient centrifugation using the lymphocyte separation medium Lymphoprep with a density of 1.070 g/ml allowed the establishment of reproducible survival curves. The survival curves for both progenitors were strictly exponential, and CFU-mix were found to be more radiosensitive (D0 = 12 ± 2 cGy) than BFU-E (D0 = 16 ± 2 cGy)

RESOLVE: A new algorithm for aperture synthesis imaging of extended emission in radio astronomy

Science.gov (United States)

Junklewitz, H.; Bell, M. R.; Selig, M.; Enßlin, T. A.

2016-02-01

We present resolve, a new algorithm for radio aperture synthesis imaging of extended and diffuse emission in total intensity. The algorithm is derived using Bayesian statistical inference techniques, estimating the surface brightness in the sky assuming a priori log-normal statistics. resolve estimates the measured sky brightness in total intensity, and the spatial correlation structure in the sky, which is used to guide the algorithm to an optimal reconstruction of extended and diffuse sources. During this process, the algorithm succeeds in deconvolving the effects of the radio interferometric point spread function. Additionally, resolve provides a map with an uncertainty estimate of the reconstructed surface brightness. Furthermore, with resolve we introduce a new, optimal visibility weighting scheme that can be viewed as an extension to robust weighting. In tests using simulated observations, the algorithm shows improved performance against two standard imaging approaches for extended sources, Multiscale-CLEAN and the Maximum Entropy Method.

PTF12os and iPTF13bvn: Two stripped-envelope supernovae from low-mass progenitors in NGC 5806

International Nuclear Information System (INIS)

Fremling, C.; Sollerman, J.; Taddia, F.; Ergon, M.; Fraser, M.

2016-01-01

Context. In this paper, we investigate two stripped-envelope supernovae (SNe) discovered in the nearby galaxy NGC 5806 by the (intermediate) Palomar Transient Factory [(i)PTF]. These SNe, designated PTF12os/SN 2012P and iPTF13bvn, exploded within ~520 days of one another at a similar distance from the host-galaxy center. We classify PTF12os as a Type IIb SN based on our spectral sequence; iPTF13bvn has previously been classified as Type Ib having a likely progenitor with zero age main sequence (ZAMS) mass below ~17 M ⊙ . Because of the shared and nearby host, we are presented with a unique opportunity to compare these two SNe. Aims. Our main objective is to constrain the explosion parameters of iPTF12os and iPTF13bvn, and to put constraints on the SN progenitors. We also aim to spatially map the metallicity in the host galaxy, and to investigate the presence of hydrogen in early-time spectra of both SNe. Methods. We present comprehensive datasets collected on PTF12os and iPTF13bvn, and introduce a new automatic reference-subtraction photometry pipeline (FPipe) currently in use by the iPTF. We perform a detailed study of the light curves (LCs) and spectral evolution of the SNe. The bolometric LCs are modeled using the hydrodynamical code hyde. We analyze early spectra of both SNe to investigate the presence of hydrogen; for iPTF13bvn we also investigate the regions of the Paschen lines in infrared spectra. We perform spectral line analysis of helium and iron lines to map the ejecta structure of both SNe. We use nebular models and late-time spectroscopy to constrain the ZAMS mass of the progenitors. We also perform image registration of ground-based images of PTF12os to archival HST images of NGC 5806 to identify a potential progenitor candidate. Results. We find that our nebular spectroscopy of iPTF13bvn remains consistent with a low-mass progenitor, likely having a ZAMS mass of ~12M ⊙ . Our late-time spectroscopy of PTF12os is consistent with a ZAMS mass of ~15

Chlorpyrifos induces oxidative stress in oligodendrocyte progenitor cells

International Nuclear Information System (INIS)

Saulsbury, Marilyn D.; Heyliger, Simone O.; Wang, Kaiyu; Johnson, Deadre J.

2009-01-01

There are increasing concerns regarding the relative safety of chlorpyrifos (CPF) to various facets of the environment. Although published works suggest that CPF is relatively safe in adult animals, recent evidence indicates that juveniles, both animals and humans, may be more sensitive to CPF toxicity than adults. In young animals, CPF is neurotoxic and mechanistically interferes with cellular replication and cellular differentiation, which culminates in the alteration of synaptic neurotransmission in neurons. However, the effects of CPF on glial cells are not fully elucidated. Here we report that chlorpyrifos is toxic to oligodendrocyte progenitors. In addition, CPF produced dose-dependent increases in 2',7'-dichlorodihydrofluorescein diacetate (H 2 DCF-DA) and dihydroethidium (DHE) fluorescence intensities relative to the vehicle control. Moreover, CPF toxicity is associated with nuclear condensation and elevation of caspase 3/7 activity and Heme oxygenase-1 mRNA expression. Pan-caspase inhibitor QVDOPh and cholinergic receptor antagonists' atropine and mecamylamine failed to protect oligodendrocyte progenitors from CPF-induced injury. Finally, glutathione (GSH) depletion enhanced CPF-induced toxicity whereas nitric oxide synthetase inhibitor L-NAME partially protected progenitors and the non-specific antioxidant vitamin E (alpha-tocopherol) completely spared cells from injury. Collectively, this data suggests that CPF induced toxicity is independent of cholinergic stimulation and is most likely caused by the induction of oxidative stress.

Masses of supernova progenitors

International Nuclear Information System (INIS)

Tinsley, B.M.

1977-01-01

The possible nature and masses of supernovae progenitors, and the bearing of empirical results on some unsolved theoretical problems concerning the origin of supernovae, are discussed. The author concentrates on two main questions: what is the lower mass limit for stars to die explosively and what stars initiate type I supernovae. The evidence considered includes local supernova rates, empirical estimates of msub(w) (the upper mass limit for death as a white dwarf), the distributions of supernovae among stellar populations in galaxies and the colors of supernova producing galaxies. (B.D.)

Enhanced generation of retinal progenitor cells from human retinal pigment epithelial cells induced by amniotic fluid

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Sanie-Jahromi Fatemeh

2012-04-01

Full Text Available Abstract Background Retinal progenitor cells are a convenient source of cell replacement therapy in retinal degenerative disorders. The purpose of this study was to evaluate the expression patterns of the homeobox genes PAX6 and CHX10 (retinal progenitor markers during treatment of human retinal pigment epithelium (RPE cells with amniotic fluid (AF, RPE cells harvested from neonatal cadaver globes were cultured in a mixture of DMEM and Ham's F12 supplemented with 10% FBS. At different passages, cells were trypsinized and co-cultured with 30% AF obtained from normal fetuses of 1416 weeks gestational age. Results Compared to FBS-treated controls, AF-treated cultures exhibited special morphological changes in culture, including appearance of spheroid colonies, improved initial cell adhesion and ordered cell alignment. Cell proliferation assays indicated a remarkable increase in the proliferation rate of RPE cells cultivated in 30% AF-supplemented medium, compared with those grown in the absence of AF. Immunocytochemical analyses exhibited nuclear localization of retinal progenitor markers at a ratio of 33% and 27% for CHX10 and PAX6, respectively. This indicated a 3-fold increase in retinal progenitor markers in AF-treated cultures compared to FBS-treated controls. Real-time PCR data of retinal progenitor genes (PAX6, CHX10 and VSX-1 confirmed these results and demonstrated AF's capacity for promoting retinal progenitor cell generation. Conclusion Taken together, the results suggest that AF significantly promotes the rate of retinal progenitor cell generation, indicating that AF can be used as an enriched supplement for serum-free media used for the in vitro propagation of human progenitor cells.

Spatially-resolved isotopic study of carbon trapped in ∼3.43 Ga Strelley Pool Formation stromatolites

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Flannery, David T.; Allwood, Abigail C.; Summons, Roger E.; Williford, Kenneth H.; Abbey, William; Matys, Emily D.; Ferralis, Nicola

2018-02-01

The large isotopic fractionation of carbon associated with enzymatic carbon assimilation allows evidence for life's antiquity, and potentially the early operation of several extant metabolic pathways, to be derived from the stable carbon isotope record of sedimentary rocks. Earth's organic carbon isotope record extends to the Late Eoarchean-Early Paleoarchean: the age of the oldest known sedimentary rocks. However, complementary inorganic carbon reservoirs are poorly represented in the oldest units, and commonly reported bulk organic carbon isotope measurements do not capture the micro-scale isotopic heterogeneities that are increasingly reported from younger rocks. Here, we investigated the isotopic composition of the oldest paired occurrences of sedimentary carbonate and organic matter, which are preserved as dolomite and kerogen within textural biosignatures of the ∼3.43 Ga Strelley Pool Formation. We targeted least-altered carbonate phases in situ using microsampling techniques guided by non-destructive elemental mapping. Organic carbon isotope values were measured by spatially-resolved bulk analyses, and in situ using secondary ion mass spectrometry to target microscale domains of organic material trapped within inorganic carbon matrixes. Total observed fractionation of 13C ranges from -29 to -45‰. Our data are consistent with studies of younger Archean rocks that host biogenic stromatolites and organic-inorganic carbon pairs showing greater fractionation than expected for Rubisco fixation alone. We conclude that organic matter was fixed and/or remobilized by at least one metabolism in addition to the CBB cycle, possibly by the Wood-Ljungdahl pathway or methanogenesis-methanotrophy, in a shallow-water marine environment during the Paleoarchean.

Spatially-Resolved Influence of Temperature and Salinity on Stock and Recruitment Variability of Commercially Important Fishes in the North Sea.

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Anna Akimova

Full Text Available Understanding of the processes affecting recruitment of commercially important fish species is one of the major challenges in fisheries science. Towards this aim, we investigated the relation between North Sea hydrography (temperature and salinity and fish stock variables (recruitment, spawning stock biomass and pre-recruitment survival index for 9 commercially important fishes using spatially-resolved cross-correlation analysis. We used high-resolution (0.2° × 0.2° hydrographic data fields matching the maximal temporal extent of the fish population assessments (1948-2013. Our approach allowed for the identification of regions in the North Sea where environmental variables seem to be more influential on the fish stocks, as well as the regions of a lesser or nil influence. Our results confirmed previously demonstrated negative correlations between temperature and recruitment of cod and plaice and identified regions of the strongest correlations (German Bight for plaice and north-western North Sea for cod. We also revealed a positive correlation between herring spawning stock biomass and temperature in the Orkney-Shetland area, as well as a negative correlation between sole pre-recruitment survival index and temperature in the German Bight. A strong positive correlation between sprat stock variables and salinity in the central North Sea was also found. To our knowledge the results concerning correlations between North Sea hydrography and stocks' dynamics of herring, sole and sprat are novel. The new information about spatial distribution of the correlation provides an additional help to identify mechanisms underlying these correlations. As an illustration of the utility of these results for fishery management, an example is provided that incorporates the identified environmental covariates in stock-recruitment models.

Identification of human embryonic progenitor cell targeting peptides using phage display.

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Paola A Bignone

Full Text Available Human pluripotent stem (hPS cells are capable of differentiation into derivatives of all three primary embryonic germ layers and can self-renew indefinitely. They therefore offer a potentially scalable source of replacement cells to treat a variety of degenerative diseases. The ability to reprogram adult cells to induced pluripotent stem (iPS cells has now enabled the possibility of patient-specific hPS cells as a source of cells for disease modeling, drug discovery, and potentially, cell replacement therapies. While reprogramming technology has dramatically increased the availability of normal and diseased hPS cell lines for basic research, a major bottleneck is the critical unmet need for more efficient methods of deriving well-defined cell populations from hPS cells. Phage display is a powerful method for selecting affinity ligands that could be used for identifying and potentially purifying a variety of cell types derived from hPS cells. However, identification of specific progenitor cell-binding peptides using phage display may be hindered by the large cellular heterogeneity present in differentiating hPS cell populations. We therefore tested the hypothesis that peptides selected for their ability to bind a clonal cell line derived from hPS cells would bind early progenitor cell types emerging from differentiating hPS cells. The human embryonic stem (hES cell-derived embryonic progenitor cell line, W10, was used and cell-targeting peptides were identified. Competition studies demonstrated specificity of peptide binding to the target cell surface. Efficient peptide targeted cell labeling was accomplished using multivalent peptide-quantum dot complexes as detected by fluorescence microscopy and flow cytometry. The cell-binding peptides were selective for differentiated hPS cells, had little or no binding on pluripotent cells, but preferential binding to certain embryonic progenitor cell lines and early endodermal hPS cell derivatives. Taken

Time-Resolved Hard X-Ray Spectrometer

International Nuclear Information System (INIS)

Kenneth Moya; Ian McKennaa; Thomas Keenana; Michael Cuneob

2007-01-01

Wired array studies are being conducted at the SNL Z accelerator to maximize the x-ray generation for inertial confinement fusion targets and high energy density physics experiments. An integral component of these studies is the characterization of the time-resolved spectral content of the x-rays. Due to potential spatial anisotropy in the emitted radiation, it is also critical to diagnose the time-evolved spectral content in a space-resolved manner. To accomplish these two measurement goals, we developed an x-ray spectrometer using a set of high-speed detectors (silicon PIN diodes) with a collimated field-of-view that converged on a 1-cm-diameter spot at the pinch axis. Spectral discrimination is achieved by placing high Z absorbers in front of these detectors. We built two spectrometers to permit simultaneous different angular views of the emitted radiation. Spectral data have been acquired from recent Z shots for the radial and polar views. UNSPEC1 has been adapted to analyze and unfold the measured data to reconstruct the x-ray spectrum. The unfold operator code, UFO2, is being adapted for a more comprehensive spectral unfolding treatment

Notch signaling patterns neurogenic ectoderm and regulates the asymmetric division of neural progenitors in sea urchin embryos.

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Mellott, Dan O; Thisdelle, Jordan; Burke, Robert D

2017-10-01

We have examined regulation of neurogenesis by Delta/Notch signaling in sea urchin embryos. At gastrulation, neural progenitors enter S phase coincident with expression of Sp-SoxC. We used a BAC containing GFP knocked into the Sp-SoxC locus to label neural progenitors. Live imaging and immunolocalizations indicate that Sp-SoxC-expressing cells divide to produce pairs of adjacent cells expressing GFP. Over an interval of about 6 h, one cell fragments, undergoes apoptosis and expresses high levels of activated Caspase3. A Notch reporter indicates that Notch signaling is activated in cells adjacent to cells expressing Sp-SoxC. Inhibition of γ-secretase, injection of Sp-Delta morpholinos or CRISPR/Cas9-induced mutation of Sp-Delta results in supernumerary neural progenitors and neurons. Interfering with Notch signaling increases neural progenitor recruitment and pairs of neural progenitors. Thus, Notch signaling restricts the number of neural progenitors recruited and regulates the fate of progeny of the asymmetric division. We propose a model in which localized signaling converts ectodermal and ciliary band cells to neural progenitors that divide asymmetrically to produce a neural precursor and an apoptotic cell. © 2017. Published by The Company of Biologists Ltd.

Investigations of vertical chemical gradients in Cu(In,Ga)S{sub 2}-thin films prepared by sulfurization of sputtered precursor layers using highly spatially resolved cathodoluminescence microscopy

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Ribbe, Stefan; Mueller, Mathias; Bertram, Frank; Hempel, Thomas; Christen, Juergen [Institute for Experimental Physics, Otto-von-Guericke-University Magdeburg (Germany); Rodriguez-Alvarez, Humberto; Lauche, Jakob; Schock, Hans-Werner [Helmholtz Center Berlin for Materials and Energy (Germany)

2012-07-01

The luminescence properties of Cu(In,Ga)S{sub 2}(CIGS)-absorber layers for thin film solar cells have been studied by highly spatially resolved cathodoluminescence (CL) at low temperature (T=5 K). In/Cu-Ga-precursors were annealed with elementary sulfur pellets in a rapid thermal process at different annealing times to represent different growth steps of the CIGS absorber layer. Spatially integral CL spectra show a dominant peak at 825 nm accompanied by a low-energy shoulder at 890 nm. Only a slight blue shift of the main peak is observed by variation of the excitation density. Investigations of cross-sections show for all samples a similar luminescence distribution. Near the molybdenum back contact distinct areas show luminescence emitting at 680-750 nm. In contrast, in upper regions of the layer a homogeneous low-energy luminescence at around 820 nm is observed which exhibits the most intensive spots on the cross-section. In local spectra we observe a change of the dominant recombination channel at the interface of these two regions.

THE PROGENITORS OF TYPE Ia SUPERNOVAE. I. ARE THEY SUPERSOFT SOURCES?

International Nuclear Information System (INIS)

Di Stefano, R.

2010-01-01

In a canonical model, the progenitors of Type Ia supernovae (SNe Ia) are accreting, nuclear-burning white dwarfs (NBWDs), which explode when the white dwarf reaches the Chandrasekhar mass, M C . Such massive NBWDs are hot (kT ∼ 100 eV), luminous (L ∼ 10 38 erg s -1 ), and are potentially observable as luminous supersoft X-ray sources (SSSs). During the past several years, surveys for soft X-ray sources in external galaxies have been conducted. This paper shows that the results falsify the hypothesis that a large fraction of progenitors are NBWDs which are presently observable as SSSs. The data also place limits on sub-M C models. While SN Ia progenitors may pass through one or more phases of SSS activity, these phases are far shorter than the time needed to accrete most of the matter that brings them close to M C .

Differentiation-Dependent Motility-Responses of Developing Neural Progenitors to Optogenetic Stimulation

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Tímea Köhidi

2017-12-01

Full Text Available During neural tissue genesis, neural stem/progenitor cells are exposed to bioelectric stimuli well before synaptogenesis and neural circuit formation. Fluctuations in the electrochemical potential in the vicinity of developing cells influence the genesis, migration and maturation of neuronal precursors. The complexity of the in vivo environment and the coexistence of various progenitor populations hinder the understanding of the significance of ionic/bioelectric stimuli in the early phases of neuronal differentiation. Using optogenetic stimulation, we investigated the in vitro motility responses of radial glia-like neural stem/progenitor populations to ionic stimuli. Radial glia-like neural stem cells were isolated from CAGloxpStoploxpChR2(H134-eYFP transgenic mouse embryos. After transfection with Cre-recombinase, ChR2(channelrhodopsin-2-expressing and non-expressing cells were separated by eYFP fluorescence. Expression of light-gated ion channels were checked by patch clamp and fluorescence intensity assays. Neurogenesis by ChR2-expressing and non-expressing cells was induced by withdrawal of EGF from the medium. Cells in different (stem cell, migrating progenitor and maturing precursor stages of development were illuminated with laser light (λ = 488 nm; 1.3 mW/mm2; 300 ms in every 5 min for 12 h. The displacement of the cells was analyzed on images taken at the end of each light pulse. Results demonstrated that the migratory activity decreased with the advancement of neuronal differentiation regardless of stimulation. Light-sensitive cells, however, responded on a differentiation-dependent way. In non-differentiated ChR2-expressing stem cell populations, the motility did not change significantly in response to light-stimulation. The displacement activity of migrating progenitors was enhanced, while the motility of differentiating neuronal precursors was markedly reduced by illumination.

The timing of differentiation of adult hippocampal neurons is crucial for spatial memory.

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Stefano Farioli-Vecchioli

2008-10-01

Full Text Available Adult neurogenesis in the dentate gyrus plays a critical role in hippocampus-dependent spatial learning. It remains unknown, however, how new neurons become functionally integrated into spatial circuits and contribute to hippocampus-mediated forms of learning and memory. To investigate these issues, we used a mouse model in which the differentiation of adult-generated dentate gyrus neurons can be anticipated by conditionally expressing the pro-differentiative gene PC3 (Tis21/BTG2 in nestin-positive progenitor cells. In contrast to previous studies that affected the number of newly generated neurons, this strategy selectively changes their timing of differentiation. New, adult-generated dentate gyrus progenitors, in which the PC3 transgene was expressed, showed accelerated differentiation and significantly reduced dendritic arborization and spine density. Functionally, this genetic manipulation specifically affected different hippocampus-dependent learning and memory tasks, including contextual fear conditioning, and selectively reduced synaptic plasticity in the dentate gyrus. Morphological and functional analyses of hippocampal neurons at different stages of differentiation, following transgene activation within defined time-windows, revealed that the new, adult-generated neurons up to 3-4 weeks of age are required not only to acquire new spatial information but also to use previously consolidated memories. Thus, the correct unwinding of these key memory functions, which can be an expression of the ability of adult-generated neurons to link subsequent events in memory circuits, is critically dependent on the correct timing of the initial stages of neuron maturation and connection to existing circuits.

Differentiation of a bipotential glial progenitor cell in a single cell microculture.

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Temple, S; Raff, M C

Although it is known that most cells of the vertebrate central nervous system (CNS) are derived from the neuroepithelial cells of the neural tube, the factors determining whether an individual neuroepithelial cell develops into a particular type of neurone or glial cell remain unknown. A promising model for studying this problem is the bipotential glial progenitor cell in the developing rat optic nerve; this cell differentiates into a particular type of astrocyte (a type-2 astrocyte) if cultured in 10% fetal calf serum (FCS) and into an oligodendrocyte if cultured in serum-free medium. As the oligodendrocyte-type-2 astrocyte (0-2A) progenitor cell can differentiate along either glial pathway in neurone-free cultures, living axons clearly are not required for its differentiation, at least in vitro. However, the studies on 0-2A progenitor cells were carried out in bulk cultures of optic nerve, and so it was possible that other cell-cell interactions were required for differentiation in culture. We show here that 0-2A progenitor cells can differentiate into type-2 astrocytes or oligodendrocytes when grown as isolated cells in microculture, indicating that differentiation along either glial pathway in vitro does not require signals from other CNS cells, apart from the signals provided by components of the culture medium. We also show that single 0-2A progenitor cells can differentiate along either pathway without dividing, supporting our previous studies using 3H-thymidine and suggesting that DNA replication is not required for these cells to choose between the two differentiation programmes.

Effects of topography on the functional development of human neural progenitor cells.

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Wu, Ze-Zhi; Kisaalita, William S; Wang, Lina; Zachman, Angela L; Zhao, Yiping; Hasneen, Kowser; Machacek, Dave; Stice, Steven L

2010-07-01

We have fabricated a topographical substrate with a packed polystyrene bead array for the development of cell-based assay systems targeting voltage-gated calcium channels (VGCCs). Human neural progenitor cells (H945RB.3) cultured on both flat and topographical substrates were analyzed in terms of morphological spreading, neuronal commitment, resting membrane potential (V(m)) establishment and VGCC function development. We found, by SEM imaging, that arrayed substrates, formed with both sub-micrometer (of 0.51 microm in mean diameter) and micrometer (of 1.98 microm in mean diameter) beads, were capable of promoting the spreading of the progenitor cells as compared with the flat polystyrene surfaces. With the micrometer beads, it was found that arrayed substrates facilitated the neural progenitor cells' maintenance of less negative V(m) values upon differentiation with bFGF starvation, which favored predominant neuronal commitment. Almost all the progenitor cells were responsive to 50 mM K(+) depolarization with an increase in [Ca(2+)](i) either before or upon differentiation, suggesting the expression of functional VGCCs. Compared to the flat polystyrene surfaces, microbead arrayed substrates facilitated the development of higher VGCC responsiveness by the progenitor cells upon differentiation. The enhancement of both VGCC responsiveness and cell spreading by arrays of micrometer beads was most significant on day 14 into differentiation, which was the latest time point of measurement in this study. This study thus rationalized the possibility for future substrate topography engineering to manipulate ion channel function and to meet the challenge of low VGCC responsiveness found in early drug discovery.

The emergence of spatial cyberinfrastructure.

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Wright, Dawn J; Wang, Shaowen

2011-04-05

Cyberinfrastructure integrates advanced computer, information, and communication technologies to empower computation-based and data-driven scientific practice and improve the synthesis and analysis of scientific data in a collaborative and shared fashion. As such, it now represents a paradigm shift in scientific research that has facilitated easy access to computational utilities and streamlined collaboration across distance and disciplines, thereby enabling scientific breakthroughs to be reached more quickly and efficiently. Spatial cyberinfrastructure seeks to resolve longstanding complex problems of handling and analyzing massive and heterogeneous spatial datasets as well as the necessity and benefits of sharing spatial data flexibly and securely. This article provides an overview and potential future directions of spatial cyberinfrastructure. The remaining four articles of the special feature are introduced and situated in the context of providing empirical examples of how spatial cyberinfrastructure is extending and enhancing scientific practice for improved synthesis and analysis of both physical and social science data. The primary focus of the articles is spatial analyses using distributed and high-performance computing, sensor networks, and other advanced information technology capabilities to transform massive spatial datasets into insights and knowledge.

Prognostic value of circulating VEGFR2+ bone marrow-derived progenitor cells in patients with advanced cancer.

Science.gov (United States)

Massard, Christophe; Borget, Isabelle; Le Deley, Marie Cécile; Taylor, Melissa; Gomez-Roca, Carlos; Soria, Jean Charles; Farace, Françoise

2012-06-01

We hypothesised that host-related markers, possibly reflecting tumour aggressiveness, such as circulating endothelial cells (CEC) and circulating VEGFR2(+) bone marrow-derived (BMD) progenitor cells, could have prognostic value in patients with advanced cancer enrolled in early anticancer drug development trials. Baseline CECs (CD45(-)CD31(+)CD146(+)7AAD(-) cells) and circulating VEGFR2(+)-BMD progenitor cells (defined as CD45(dim)CD34(+)VEGFR2(+)7AAD(-) cells) were measured by flow-cytometry in 71 and 58 patients included in phase 1 trials testing novel anti-vascular or anti-angiogenic agents. Correlations between levels of CECs, circulating VEGFR2(+)-BMD progenitor cells, clinical and biological prognostic factors (i.e. the Royal Marsden Hospital (RMH) score), and overall survival (OS) were studied. The median value of CECs was 12 CEC/ml (range 0-154/ml). The median level of VEGFR2(+)-BMD progenitor cells was 1.3% (range 0-32.5%) of circulating BMD-CD34(+) progenitors. While OS was not correlated with CEC levels, it was significantly worse in patients with high VEGFR2(+)-BMD progenitor levels (>1%) (median OS 9.0 versus 17.0 months), and with a RMH prognostic score >0 (median OS 9.0 versus 24.2 months). The prognostic value of VEGFR2(+)-BMD progenitor levels remained significant (hazard ratio (HR) = 2.3, 95% confidence interval (CI), 1.1-4.6, p = 0.02) after multivariate analysis. A composite VEGFR2(+)-BMD progenitor level/RHM score ≥ 2 was significantly associated with an increased risk of death compared to scores of 0 or 1 (median OS 9.0 versus 18.4 months, HR = 2.6 (95%CI, 1.2-5.8, p = 0.02)). High circulating VEGFR2(+)-BMD progenitor levels are associated with poor prognostics and when combined to classical clinical and biological parameters could provide a new tool for patient selection in early anticancer drug trials. Copyright © 2012 Elsevier Ltd. All rights reserved.

Bioreactor-induced mesenchymal progenitor cell differentiation and elastic fiber assembly in engineered vascular tissues.

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Lin, Shigang; Mequanint, Kibret

2017-09-01

In vitro maturation of engineered vascular tissues (EVT) requires the appropriate incorporation of smooth muscle cells (SMC) and extracellular matrix (ECM) components similar to native arteries. To this end, the aim of the current study was to fabricate 4mm inner diameter vascular tissues using mesenchymal progenitor cells seeded into tubular scaffolds. A dual-pump bioreactor operating either in perfusion or pulsatile perfusion mode was used to generate physiological-like stimuli to promote progenitor cell differentiation, extracellular elastin production, and tissue maturation. Our data demonstrated that pulsatile forces and perfusion of 3D tubular constructs from both the lumenal and ablumenal sides with culture media significantly improved tissue assembly, effectively inducing mesenchymal progenitor cell differentiation to SMCs with contemporaneous elastin production. With bioreactor cultivation, progenitor cells differentiated toward smooth muscle lineage characterized by the expression of smooth muscle (SM)-specific markers smooth muscle alpha actin (SM-α-actin) and smooth muscle myosin heavy chain (SM-MHC). More importantly, pulsatile perfusion bioreactor cultivation enhanced the synthesis of tropoelastin and its extracellular cross-linking into elastic fiber compared with static culture controls. Taken together, the current study demonstrated progenitor cell differentiation and vascular tissue assembly, and provides insights into elastin synthesis and assembly to fibers. Incorporation of elastin into engineered vascular tissues represents a critical design goal for both mechanical and biological functions. In the present study, we seeded porous tubular scaffolds with multipotent mesenchymal progenitor cells and cultured in dual-pump pulsatile perfusion bioreactor. Physiological-like stimuli generated by bioreactor not only induced mesenchymal progenitor cell differentiation to vascular smooth muscle lineage but also actively promoted elastin synthesis and

Spatially Resolved Patchy Ly α Emission within the Central Kiloparsec of a Strongly Lensed Quasar Host Galaxy at z = 2.8

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Bayliss, Matthew B.; Bordoloi, Rongmon [Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 (United States); Sharon, Keren; Runnoe, Jessie; Johnson, Traci; Paterno-Mahler, Rachel [Department of Astronomy, University of Michigan, 1085 S. University Avenue, Ann Arbor, MI 48109 (United States); Acharyya, Ayan; Bian, Fuyan; Kewley, Lisa [RSAA, Australian National University, Cotter Road, Weston Creek, ACT 2611 (Australia); Gladders, Michael D. [Kavli Institute for Cosmological Physics, University of Chicago, Chicago, IL 60637 (United States); Rigby, Jane R. [Astrophysics Science Division, NASA Goddard Space Flight Center, 8800 Greenbelt Road, Greenbelt, MD 20771 (United States); Dahle, Hakon [Institute of Theoretical Astrophysics, University of Oslo, P.O. Box 1029, Blindern, NO-0315 Oslo (Norway); Florian, Michael, E-mail: mbayliss@mit.edu [Department of Astronomy and Astrophysics, University of Chicago, Chicago, IL 60637 (United States)

2017-08-20

We report the detection of extended Ly α emission from the host galaxy of SDSS J2222+2745, a strongly lensed quasar at z = 2.8. Spectroscopic follow-up clearly reveals extended Ly α in emission between two images of the central active galactic nucleus (AGN). We reconstruct the lensed quasar host galaxy in the source plane by applying a strong lens model to HST imaging and resolve spatial scales as small as ∼200 pc. In the source plane, we recover the host galaxy morphology to within a few hundred parsecs of the central AGN and map the extended Ly α emission to its physical origin on one side of the host galaxy at radii ∼0.5–2 kpc from the central AGN. There are clear morphological differences between the Ly α and rest-frame ultraviolet stellar continuum emission from the quasar host galaxy. Furthermore, the relative velocity profiles of quasar Ly α , host galaxy Ly α , and metal lines in outflowing gas reveal differences in the absorbing material affecting the AGN and host galaxy. These data indicate the presence of patchy local intervening gas in front of the central quasar and its host galaxy. This interpretation is consistent with the central luminous quasar being obscured across a substantial fraction of its surrounding solid angle, resulting in strong anisotropy in the exposure of the host galaxy to ionizing radiation from the AGN. This work demonstrates the power of strong-lensing-assisted studies to probe spatial scales that are currently inaccessible by other means.

Spatially Resolved Patchy Ly α Emission within the Central Kiloparsec of a Strongly Lensed Quasar Host Galaxy at z = 2.8

International Nuclear Information System (INIS)

Bayliss, Matthew B.; Bordoloi, Rongmon; Sharon, Keren; Runnoe, Jessie; Johnson, Traci; Paterno-Mahler, Rachel; Acharyya, Ayan; Bian, Fuyan; Kewley, Lisa; Gladders, Michael D.; Rigby, Jane R.; Dahle, Hakon; Florian, Michael

2017-01-01

We report the detection of extended Ly α emission from the host galaxy of SDSS J2222+2745, a strongly lensed quasar at z = 2.8. Spectroscopic follow-up clearly reveals extended Ly α in emission between two images of the central active galactic nucleus (AGN). We reconstruct the lensed quasar host galaxy in the source plane by applying a strong lens model to HST imaging and resolve spatial scales as small as ∼200 pc. In the source plane, we recover the host galaxy morphology to within a few hundred parsecs of the central AGN and map the extended Ly α emission to its physical origin on one side of the host galaxy at radii ∼0.5–2 kpc from the central AGN. There are clear morphological differences between the Ly α and rest-frame ultraviolet stellar continuum emission from the quasar host galaxy. Furthermore, the relative velocity profiles of quasar Ly α , host galaxy Ly α , and metal lines in outflowing gas reveal differences in the absorbing material affecting the AGN and host galaxy. These data indicate the presence of patchy local intervening gas in front of the central quasar and its host galaxy. This interpretation is consistent with the central luminous quasar being obscured across a substantial fraction of its surrounding solid angle, resulting in strong anisotropy in the exposure of the host galaxy to ionizing radiation from the AGN. This work demonstrates the power of strong-lensing-assisted studies to probe spatial scales that are currently inaccessible by other means.

File list: NoD.Neu.20.AllAg.Neural_progenitor_cells [Chip-atlas[Archive

Lifescience Database Archive (English)

Full Text Available NoD.Neu.20.AllAg.Neural_progenitor_cells mm9 No description Neural Neural progenito...SRX346675,SRX346817 http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/assembled/NoD.Neu.20.AllAg.Neural_progenitor_cells.bed ...

Differentiation of insulin-producing cells from human neural progenitor cells.

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Yuichi Hori

2005-04-01

Full Text Available BACKGROUND: Success in islet-transplantation-based therapies for type 1 diabetes, coupled with a worldwide shortage of transplant-ready islets, has motivated efforts to develop renewable sources of islet-replacement tissue. Islets and neurons share features, including common developmental programs, and in some species brain neurons are the principal source of systemic insulin. METHODS AND FINDINGS: Here we show that brain-derived human neural progenitor cells, exposed to a series of signals that regulate in vivo pancreatic islet development, form clusters of glucose-responsive insulin-producing cells (IPCs. During in vitro differentiation of neural progenitor cells with this novel method, genes encoding essential known in vivo regulators of pancreatic islet development were expressed. Following transplantation into immunocompromised mice, IPCs released insulin C-peptide upon glucose challenge, remained differentiated, and did not form detectable tumors. CONCLUSION: Production of IPCs solely through extracellular factor modulation in the absence of genetic manipulations may promote strategies to derive transplantable islet-replacement tissues from human neural progenitor cells and other types of multipotent human stem cells.

High resolving power spectrometer for beam analysis

International Nuclear Information System (INIS)

Moshammer, H.W.; Spencer, J.E.

1992-03-01

We describe a system designed to analyze the high energy, closely spaced bunches from individual RF pulses. Neither a large solid angle nor momentum range is required so this allows characteristics that appear useful for other applications such as ion beam lithography. The spectrometer is a compact, double-focusing QBQ design whose symmetry allows the Quads to range between F or D with a correspondingly large range of magnifications, dispersion and resolving power. This flexibility insures the possibility of spatially separating all of the bunches along the focal plane with minimal transverse kicks and bending angle for differing input conditions. The symmetry of the system allows a simple geometric interpretationof the resolving power in terms of thin lenses and ray optics. We discuss the optics and the hardware that is proposed to measure emittance, energy, energy spread and bunch length for each bunch in an RF pulse train for small bunch separations. We also discuss how to use such measurements for feedback and feedforward control of these bunch characteristics as well as maintain their stability. 2 refs

A simultaneous multi-slice selective J-resolved experiment for fully resolved scalar coupling information

Science.gov (United States)

Zeng, Qing; Lin, Liangjie; Chen, Jinyong; Lin, Yanqin; Barker, Peter B.; Chen, Zhong

2017-09-01

Proton-proton scalar coupling plays an important role in molecular structure elucidation. Many methods have been proposed for revealing scalar coupling networks involving chosen protons. However, determining all JHH values within a fully coupled network remains as a tedious process. Here, we propose a method termed as simultaneous multi-slice selective J-resolved spectroscopy (SMS-SEJRES) for simultaneously measuring JHH values out of all coupling networks in a sample within one experiment. In this work, gradient-encoded selective refocusing, PSYCHE decoupling and echo planar spectroscopic imaging (EPSI) detection module are adopted, resulting in different selective J-edited spectra extracted from different spatial positions. The proposed pulse sequence can facilitate the analysis of molecular structures. Therefore, it will interest scientists who would like to efficiently address the structural analysis of molecules.

Earmuff restricts progenitor cell potential by attenuating the competence to respond to self-renewal factors.

Science.gov (United States)

Janssens, Derek H; Komori, Hideyuki; Grbac, Daniel; Chen, Keng; Koe, Chwee Tat; Wang, Hongyan; Lee, Cheng-Yu

2014-03-01

Despite expressing stem cell self-renewal factors, intermediate progenitor cells possess restricted developmental potential, which allows them to give rise exclusively to differentiated progeny rather than stem cell progeny. Failure to restrict the developmental potential can allow intermediate progenitor cells to revert into aberrant stem cells that might contribute to tumorigenesis. Insight into stable restriction of the developmental potential in intermediate progenitor cells could improve our understanding of the development and growth of tumors, but the mechanisms involved remain largely unknown. Intermediate neural progenitors (INPs), generated by type II neural stem cells (neuroblasts) in fly larval brains, provide an in vivo model for investigating the mechanisms that stably restrict the developmental potential of intermediate progenitor cells. Here, we report that the transcriptional repressor protein Earmuff (Erm) functions temporally after Brain tumor (Brat) and Numb to restrict the developmental potential of uncommitted (immature) INPs. Consistently, endogenous Erm is detected in immature INPs but undetectable in INPs. Erm-dependent restriction of the developmental potential in immature INPs leads to attenuated competence to respond to all known neuroblast self-renewal factors in INPs. We also identified that the BAP chromatin-remodeling complex probably functions cooperatively with Erm to restrict the developmental potential of immature INPs. Together, these data led us to conclude that the Erm-BAP-dependent mechanism stably restricts the developmental potential of immature INPs by attenuating their genomic responses to stem cell self-renewal factors. We propose that restriction of developmental potential by the Erm-BAP-dependent mechanism functionally distinguishes intermediate progenitor cells from stem cells, ensuring the generation of differentiated cells and preventing the formation of progenitor cell-derived tumor-initiating stem cells.

Circumstellar matter and the nature of the SN1987A progenitor star

International Nuclear Information System (INIS)

Chevalier, R.A.; Fransson, C.

1987-01-01

The radio observations of the supernova SN1987A can be interpreted in terms of its interaction with circumstellar matter. The early turn-on of the radio emission implies a relatively low density circumstellar medium. The optical properties of the supernova imply that the progenitor star had a smaller radius than that of a typical type II supernova progenitor. The mass loss properties are consistent with this hypothesis. The authors predict the thermal X-ray luminosity of the supernova, and note that it is below the current upper limit. A bright infrared dust echo is not expected. Weak ultraviolet emission lines from circumstellar gas may be visible. Although the circumstellar density is low, it is possible that the progenitor star did lose a substantial fraction of its mass prior to the supernova explosion. (author)

Cadmium modulates hematopoietic stem and progenitor cells and skews toward myelopoiesis in mice

International Nuclear Information System (INIS)

Zhang, Yandong; Yu, Xinchun; Sun, Shuhui; Li, Qian; Xie, Yunli; Li, Qiang; Zhao, Yifan; Pei, Jianfeng; Zhang, Wenmin; Xue, Peng; Zhou, Zhijun; Zhang, Yubin

2016-01-01

The heavy metal cadmium (Cd) is known to modulate immunity and cause osteoporosis. However, how Cd influences on hematopoiesis remain largely unknown. Herein, we show that wild-type C57BL/6 (B6) mice exposed to Cd for 3 months had expanded bone marrow (BM) populations of long-term hematopoietic stem cells (LT-HSCs), common myeloid progenitors (CMPs) and granulocyte-macrophage progenitors (GMPs), while having reduced populations of multipotent progenitors (MPPs) and common lymphoid progenitors (CLPs). A competitive mixed BM transplantation assay indicates that BM from Cd-treated mice had impaired LT-HSC ability to differentiate into mature cells. In accordance with increased myeloid progenitors and decreased lymphoid progenitors, the BM and spleens of Cd-treated mice had more monocytes and/or neutrophils and fewer B cells and T cells. Cd impaired the ability of the non-hematopoietic system to support LT-HSCs, in that lethally irradiated Cd-treated recipients transplanted with normal BM cells had reduced LT-HSCs after the hematopoietic system was fully reconstituted. This is consistent with reduced osteoblasts, a known critical component for HSC niche, observed in Cd-treated mice. Conversely, lethally irradiated control recipients transplanted with BM cells from Cd-treated mice had normal LT-HSC reconstitution. Furthermore, both control mice and Cd-treated mice that received Alendronate, a clinical drug used for treating osteoporosis, had BM increases of LT-HSCs. Thus, the results suggest Cd increase of LT-HSCs is due to effects on HSCs and not on osteoblasts, although, Cd causes osteoblast reduction and impaired niche function for maintaining HSCs. Furthermore, Cd skews HSCs toward myelopoiesis. - Highlights: • Cd increases the number of LT-HSCs but impairs their development. • Cd-treated hosts have compromised ability to support LT-HSCs. • Cd promotes myelopoiesis at the expense of lymphopoiesis at the MPP level.

THE ARDUOUS JOURNEY TO BLACK HOLE FORMATION IN POTENTIAL GAMMA-RAY BURST PROGENITORS

International Nuclear Information System (INIS)

Dessart, Luc; O'Connor, Evan; Ott, Christian D.

2012-01-01

We present a quantitative study on the properties at death of fast-rotating massive stars evolved at low-metallicity—objects that are proposed as likely progenitors of long-duration γ-ray bursts (LGRBs). We perform one-dimensional+rotation stellar-collapse simulations on the progenitor models of Woosley and Heger, and critically assess their potential for the formation of a black hole and a Keplerian disk (namely, a collapsar) or a proto-magnetar. We note that theoretical uncertainties in the treatment of magnetic fields and the approximate handling of rotation compromise the accuracy of stellar-evolution models. We find that only the fastest rotating progenitors achieve sufficient compactness for black hole formation while the bulk of models possess a core density structure typical of garden-variety core-collapse supernova (SN) progenitors evolved without rotation and at solar metallicity. Of the models that do have sufficient compactness for black hole formation, most of them also retain a large amount of angular momentum in the core, making them prone to a magneto-rotational explosion, therefore preferentially leaving behind a proto-magnetar. A large progenitor angular-momentum budget is often the sole criterion invoked in the community today to assess the suitability for producing a collapsar. This simplification ignores equally important considerations such as the core compactness, which conditions black hole formation, the core angular momentum, which may foster a magneto-rotational explosion preventing black hole formation, or the metallicity and the residual envelope mass which must be compatible with inferences from observed LGRB/SNe. Our study suggests that black hole formation is non-trivial, that there is room for accommodating both collapsars and proto-magnetars as LGRB progenitors, although proto-magnetars seem much more easily produced by current stellar-evolutionary models.

THE ARDUOUS JOURNEY TO BLACK HOLE FORMATION IN POTENTIAL GAMMA-RAY BURST PROGENITORS

Energy Technology Data Exchange (ETDEWEB)

Dessart, Luc [Laboratoire d' Astrophysique de Marseille, Universite Aix-Marseille and CNRS, UMR7326, 38 rue Frederic Joliot-Curie, 13388 Marseille (France); O' Connor, Evan; Ott, Christian D., E-mail: Luc.Dessart@oamp.fr, E-mail: evanoc@tapir.caltech.edu, E-mail: cott@tapir.caltech.edu [TAPIR, Mailcode 350-17, California Institute of Technology, Pasadena, CA 91125 (United States)

2012-07-20

We present a quantitative study on the properties at death of fast-rotating massive stars evolved at low-metallicity-objects that are proposed as likely progenitors of long-duration {gamma}-ray bursts (LGRBs). We perform one-dimensional+rotation stellar-collapse simulations on the progenitor models of Woosley and Heger, and critically assess their potential for the formation of a black hole and a Keplerian disk (namely, a collapsar) or a proto-magnetar. We note that theoretical uncertainties in the treatment of magnetic fields and the approximate handling of rotation compromise the accuracy of stellar-evolution models. We find that only the fastest rotating progenitors achieve sufficient compactness for black hole formation while the bulk of models possess a core density structure typical of garden-variety core-collapse supernova (SN) progenitors evolved without rotation and at solar metallicity. Of the models that do have sufficient compactness for black hole formation, most of them also retain a large amount of angular momentum in the core, making them prone to a magneto-rotational explosion, therefore preferentially leaving behind a proto-magnetar. A large progenitor angular-momentum budget is often the sole criterion invoked in the community today to assess the suitability for producing a collapsar. This simplification ignores equally important considerations such as the core compactness, which conditions black hole formation, the core angular momentum, which may foster a magneto-rotational explosion preventing black hole formation, or the metallicity and the residual envelope mass which must be compatible with inferences from observed LGRB/SNe. Our study suggests that black hole formation is non-trivial, that there is room for accommodating both collapsars and proto-magnetars as LGRB progenitors, although proto-magnetars seem much more easily produced by current stellar-evolutionary models.

Cadmium modulates hematopoietic stem and progenitor cells and skews toward myelopoiesis in mice

Energy Technology Data Exchange (ETDEWEB)

Zhang, Yandong; Yu, Xinchun [School of Public Health and Key Laboratory of Public Health, MOE, Fudan University, Shanghai 200032 (China); Sun, Shuhui [Key Laboratory of Medical Molecular Virology, School of Basic Medical Sciences, Shanghai Medical College, Fudan University, Shanghai 200032 (China); Li, Qian [School of Public Health and Key Laboratory of Public Health, MOE, Fudan University, Shanghai 200032 (China); Xie, Yunli [Insititute of Brain Sciences, Fudan University, Shanghai 200032 (China); Li, Qiang [Putuo District Center for Disease Control and Prevention, Shanghai 200062 (China); Zhao, Yifan; Pei, Jianfeng; Zhang, Wenmin; Xue, Peng; Zhou, Zhijun [School of Public Health and Key Laboratory of Public Health, MOE, Fudan University, Shanghai 200032 (China); Zhang, Yubin, E-mail: yz001@fudan.edu.cn [School of Public Health and Key Laboratory of Public Health, MOE, Fudan University, Shanghai 200032 (China)

2016-12-15

The heavy metal cadmium (Cd) is known to modulate immunity and cause osteoporosis. However, how Cd influences on hematopoiesis remain largely unknown. Herein, we show that wild-type C57BL/6 (B6) mice exposed to Cd for 3 months had expanded bone marrow (BM) populations of long-term hematopoietic stem cells (LT-HSCs), common myeloid progenitors (CMPs) and granulocyte-macrophage progenitors (GMPs), while having reduced populations of multipotent progenitors (MPPs) and common lymphoid progenitors (CLPs). A competitive mixed BM transplantation assay indicates that BM from Cd-treated mice had impaired LT-HSC ability to differentiate into mature cells. In accordance with increased myeloid progenitors and decreased lymphoid progenitors, the BM and spleens of Cd-treated mice had more monocytes and/or neutrophils and fewer B cells and T cells. Cd impaired the ability of the non-hematopoietic system to support LT-HSCs, in that lethally irradiated Cd-treated recipients transplanted with normal BM cells had reduced LT-HSCs after the hematopoietic system was fully reconstituted. This is consistent with reduced osteoblasts, a known critical component for HSC niche, observed in Cd-treated mice. Conversely, lethally irradiated control recipients transplanted with BM cells from Cd-treated mice had normal LT-HSC reconstitution. Furthermore, both control mice and Cd-treated mice that received Alendronate, a clinical drug used for treating osteoporosis, had BM increases of LT-HSCs. Thus, the results suggest Cd increase of LT-HSCs is due to effects on HSCs and not on osteoblasts, although, Cd causes osteoblast reduction and impaired niche function for maintaining HSCs. Furthermore, Cd skews HSCs toward myelopoiesis. - Highlights: • Cd increases the number of LT-HSCs but impairs their development. • Cd-treated hosts have compromised ability to support LT-HSCs. • Cd promotes myelopoiesis at the expense of lymphopoiesis at the MPP level.

Time-resolved measurements of the focused ion beams on PBFA II

International Nuclear Information System (INIS)

Mix, L.P.; Stygar, W.A.; Leeper, R.J.; Maenchen, J.E.; Wenger, D.F.

1992-01-01

A time-resolved camera has been developed to image the intense ion beam focus on PBFA II. Focused ions from a sector of the ion diode are Rutherford scattered from a thin gold foil on the diode axis and pinhole imaged onto an array of up to 49 PIN detectors to obtain the spatially and temporally resolved images. The signals from these detectors are combined to provide a movie of the beam focus with a time resolution of about 3 ns and a spatial resolution of 2 mm over a 12 mm field of view. Monte Carlo simulations of the camera response are used with the measured ion energy to account for the time-of-flight dispersion of the beam and to convert the recorded signals to an intensity. From measurements on an 81 degree sector of the diode, average intensities on a 6 mm sphere of about 5 TW/cm 2 and energies approaching 80 kJ/cm 2 are calculated for standard proton diodes. Corresponding numbers for a lithium diode are less than those measured with protons. The details of the analysis and image reconstruction will be presented along with scaled images from recent ion focusing experiments

Common-Lymphoid-Progenitor-Independent Pathways of Innate and T Lymphocyte Development

Directory of Open Access Journals (Sweden)

Maryam Ghaedi

2016-04-01

Full Text Available All lymphocytes are thought to develop from common lymphoid progenitors (CLPs. However, lymphoid-primed multipotent progenitors (LMPPs are more efficient than CLPs in differentiating into T cells and group 2 innate lymphoid cells (ILC2s. Here, we have divided LMPPs into CD127− (LMPP−s and CD127+ (LMPP+s subsets and compared them with Ly6D− and Ly6D+ CLPs. Adult LMPP+s differentiated into T cells and ILCs more rapidly and efficiently than other progenitors in transplantation assays. The development of T cells and ILC2s is highly active in the neonatal period. Neonatal CLPs are rare and, unlike prominent neonatal LMPP+s, do not efficiently differentiate into T cells and ILC2s. ILC2s generated in the neonatal period are long lived and persist in adult tissues. These results suggest that some ILCs and T cells may develop from LMPP+s via CLP-independent pathways.

Hedgehog regulates Norrie disease protein to drive neural progenitor self-renewal.

Science.gov (United States)

McNeill, Brian; Mazerolle, Chantal; Bassett, Erin A; Mears, Alan J; Ringuette, Randy; Lagali, Pamela; Picketts, David J; Paes, Kim; Rice, Dennis; Wallace, Valerie A

2013-03-01

Norrie disease (ND) is a congenital disorder characterized by retinal hypovascularization and cognitive delay. ND has been linked to mutations in 'Norrie Disease Protein' (Ndp), which encodes the secreted protein Norrin. Norrin functions as a secreted angiogenic factor, although its role in neural development has not been assessed. Here, we show that Ndp expression is initiated in retinal progenitors in response to Hedgehog (Hh) signaling, which induces Gli2 binding to the Ndp promoter. Using a combination of genetic epistasis and acute RNAi-knockdown approaches, we show that Ndp is required downstream of Hh activation to induce retinal progenitor proliferation in the retina. Strikingly, Ndp regulates the rate of cell-cycle re-entry and not cell-cycle kinetics, thereby uncoupling the self-renewal and cell-cycle progression functions of Hh. Taken together, we have uncovered a cell autonomous function for Ndp in retinal progenitor proliferation that is independent of its function in the retinal vasculature, which could explain the neural defects associated with ND.

An in vitro clonogenic assay to assess radiation damage in rat CNS glial progenitor cells

International Nuclear Information System (INIS)

Maazen, R.W.M. van der; Verhagen, I.; Kogel, A.J. van der

1990-01-01

Normal glial progenitor cells can be isolated from the rat central nervous system (CNS) and cultured in vitro on a monolayer of type-1 astrocytes. These monolayers are able to support and stimulate explanted glial progenitor cells to proliferate. Employing these in vitro interactions of specific glial cell types, an in vivo-in vitro clonogenic assay has been developed. This method offers the possibility to study the intrinsic radiosensitivity, repair and regeneration of glial progenitor cells after in vitro or in vivo irradiation. (author)

Establishment and characterization of a unique 1 microm diameter liver-derived progenitor cell line.

Science.gov (United States)

Aravalli, Rajagopal N; Behnan Sahin, M; Cressman, Erik N K; Steer, Clifford J

2010-01-01

Liver-derived progenitor cells (LDPCs) are recently identified novel stem/progenitor cells from healthy, unmanipulated adult rat livers. They are distinct from other known liver stem/progenitor cells such as the oval cells. In this study, we have generated a LDPC cell line RA1 by overexpressing the simian virus 40 (SV40) large T antigen (TAg) in primary LDPCs. This cell line was propagated continuously for 55 passages in culture, after which it became senescent. Interestingly, following transformation with SV40 TAg, LDPCs decreased in size significantly and the propagating cells measured 1 microm in diameter. RA1 cells proliferated in vitro with a doubling time of 5-7 days, and expressed cell surface markers of LDPCs. In this report, we describe the characterization of this novel progenitor cell line that might serve as a valuable model to study liver cell functions and stem cell origin of liver cancers. Copyright 2009 Elsevier Inc. All rights reserved.

Nutraceutical augmentation of circulating endothelial progenitor cells and hematopoietic stem cells in human subjects.

Science.gov (United States)

Mikirova, Nina A; Jackson, James A; Hunninghake, Ron; Kenyon, Julian; Chan, Kyle W H; Swindlehurst, Cathy A; Minev, Boris; Patel, Amit N; Murphy, Michael P; Smith, Leonard; Ramos, Famela; Ichim, Thomas E; Riordan, Neil H

2010-04-08

The medical significance of circulating endothelial or hematopoietic progenitors is becoming increasing recognized. While therapeutic augmentation of circulating progenitor cells using G-CSF has resulted in promising preclinical and early clinical data for several degenerative conditions, this approach is limited by cost and inability to perform chronic administration. Stem-Kine is a food supplement that was previously reported to augment circulating EPC in a pilot study. Here we report a trial in 18 healthy volunteers administered Stem-Kine twice daily for a 2 week period. Significant increases in circulating CD133 and CD34 cells were observed at days 1, 2, 7, and 14 subsequent to initiation of administration, which correlated with increased hematopoietic progenitors as detected by the HALO assay. Augmentation of EPC numbers in circulation was detected by KDR-1/CD34 staining and colony forming assays. These data suggest Stem-Kine supplementation may be useful as a stimulator of reparative processes associated with mobilization of hematopoietic and endothelial progenitors.

Nutraceutical augmentation of circulating endothelial progenitor cells and hematopoietic stem cells in human subjects

Directory of Open Access Journals (Sweden)

Minev Boris

2010-04-01

Full Text Available Abstract The medical significance of circulating endothelial or hematopoietic progenitors is becoming increasing recognized. While therapeutic augmentation of circulating progenitor cells using G-CSF has resulted in promising preclinical and early clinical data for several degenerative conditions, this approach is limited by cost and inability to perform chronic administration. Stem-Kine is a food supplement that was previously reported to augment circulating EPC in a pilot study. Here we report a trial in 18 healthy volunteers administered Stem-Kine twice daily for a 2 week period. Significant increases in circulating CD133 and CD34 cells were observed at days 1, 2, 7, and 14 subsequent to initiation of administration, which correlated with increased hematopoietic progenitors as detected by the HALO assay. Augmentation of EPC numbers in circulation was detected by KDR-1/CD34 staining and colony forming assays. These data suggest Stem-Kine supplementation may be useful as a stimulator of reparative processes associated with mobilization of hematopoietic and endothelial progenitors.

Spatially resolved ultrasonic attenuation in resistance spot welds: implications for nondestructive testing.

Science.gov (United States)

Mozurkewich, George; Ghaffari, Bita; Potter, Timothy J

2008-09-01

Spatial variation of ultrasonic attenuation and velocity has been measured in plane parallel specimens extracted from resistance spot welds. In a strong weld, attenuation is larger in the nugget than in the parent material, and the region of increased attenuation is surrounded by a ring of decreased attenuation. In the center of a stick weld, attenuation is even larger than in a strong weld, and the low-attenuation ring is absent. These spatial variations are interpreted in terms of differences in grain size and martensite formation. Measured frequency dependences indicate the presence of an additional attenuation mechanism besides grain scattering. The observed attenuations do not vary as commonly presumed with weld quality, suggesting that the common practice of using ultrasonic attenuation to indicate weld quality is not a reliable methodology.

Lucas–Kanade fluid trajectories for time-resolved PIV