The Recurrent Nova Candidate M31N 1966-08a = 1968-10c is a Galactic Flare Star

NASA Astrophysics Data System (ADS)

Shafter, A. W.; Henze, M.; Darnley, M. J.; Ciardullo, R.; Davis, B. D.; Hawley, S. L.

2017-12-01

A spectrum of the quiescent counterpart of the Recurrent Nova candidate M31N 1966-08a (= M31N 1968-10c) obtained with LRS2 on the Hobby-Eberly Telescope reveals the object to be a foreground Galactic dMe flare star, and not a nova in M31.

The 2011 outburst of recurrent nova T PYX: Radio observations reveal the ejecta mass and hint at complex mass loss

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nelson, Thomas; Chomiuk, Laura; Roy, Nirupam

2014-04-10

Despite being the prototype of its class, T Pyx is arguably the most unusual and poorly understood recurrent nova. Here, we use radio observations from the Karl G. Jansky Very Large Array to trace the evolution of the ejecta over the course of the 2011 outburst of T Pyx. The radio emission is broadly consistent with thermal emission from the nova ejecta. However, the radio flux began rising surprisingly late in the outburst, indicating that the bulk of the radio-emitting material was either very cold, or expanding very slowly, for the first ∼50 days of the outburst. Considering a plausiblemore » range of volume filling factors and geometries for the ejecta, we find that the high peak flux densities of the radio emission require a massive ejection of (1-30) × 10{sup –5} M {sub ☉}. This ejecta mass is much higher than the values normally associated with recurrent novae, and is more consistent with a nova on a white dwarf well below the Chandrasekhar limit.« less

No hot and luminous progenitor for Tycho's supernova

NASA Astrophysics Data System (ADS)

Woods, T. E.; Ghavamian, P.; Badenes, C.; Gilfanov, M.

2017-11-01

Type Ia supernovae have proven vital to our understanding of cosmology, both as standard candles and for their role in galactic chemical evolution; however, their origin remains uncertain. The canonical accretion model implies a hot and luminous progenitor that would ionize the surrounding gas out to a radius of 10-100 pc for 100,000 years after the explosion. Here, we report stringent upper limits on the temperature and luminosity of the progenitor of Tycho's supernova (SN 1572), determined using the remnant itself as a probe of its environment. Hot, luminous progenitors that would have produced a greater hydrogen ionization fraction than that measured at the radius of the present remnant ( 3 pc) can thus be excluded. This conclusively rules out steadily nuclear-burning white dwarfs (supersoft X-ray sources), as well as disk emission from a Chandrasekhar-mass white dwarf accreting approximately greater than 10-8 M⊙ yr-1 (recurrent novae; M⊙ is equal to one solar mass). The lack of a surrounding Strömgren sphere is consistent with the merger of a double white dwarf binary, although other more exotic scenarios may be possible.

The Progenitor of Tycho’s Supernova was Not Hot and Luminous

NASA Astrophysics Data System (ADS)

Ghavamian, Parviz; Woods, T. E.; Gilfanov, M.; Badenes, C.; T. E. Woods, C. Badenes, M. Gilfanov

2018-01-01

Canonical accretion models of Type Ia supernovae predict that a hot and luminous progenitor will ionize the surrounding gas out to a radius of ∼10–100 pc for ∼100,000 years after the explosion. Tycho’s supernova of 1572 was a Type Ia explosion which produced a remnant that is currently interacting with neutral gas in the form of Balmer-dominated shocks. From analysis of these shocks and photoionization calculations, we have placed stringent upper limits on the temperature and luminosity of the progenitor of Tycho’s supernova. Hot, luminous progenitors that would have produced a greater hydrogen ionization fraction than that measured at the current SNR radius (∼3 parsecs) can thus be excluded. This rules out steadily nuclear-burning white dwarfs (i..e, supersoft X-ray sources), as well as disk emission from a Chandrasekhar-mass white dwarf accreting 1E-8 solar masses per year (recurrent novae). The lack of a Stromgren sphere around Tycho’s SNR is consistent with a double degenerate explosion, although other more exotic scenarios may be possible.

Breaking the Habit - The peculiar 2016 eruption of the remarkable recurrent nova M31N 2008-12a

NASA Astrophysics Data System (ADS)

Henze, Martin; M31N 2008-12a Monitoring Collaboration

2018-01-01

Since its discovery in 2008, the Andromeda galaxy nova M31N 2008-12a has been observed in eruption every year. This makes it the most extreme member of the new class of Rapidly Recurring Novae (RRN) which show repeated eruptions within a time span of a decade or less. Such frequent outbursts indicate a high mass accretion rate onto a white dwarf that is extremely close to the Chandrasekhar limit, thereby making RRN the most promising observable candidates for the progenitors of type-Ia supernovae currently known.The previous three eruptions of M31N 2008-12a have displayed remarkably homogeneous multi-wavelength properties. From a relatively faint peak brightness the optical light curve declined rapidly by two magnitudes in less than two days. Early spectra showed high velocities that declined significantly within days and displayed clear helium and nitrogen lines throughout. The supersoft X-ray source phase of the nova began extremely early, around day six after eruption, and only lasted for about two weeks.In contrast, the delayed 2016 eruption showed significant deviations from the established pattern. In this talk, I will discuss the observational results and their impact on our understanding of the physics and evolution of this unique nova.

M31N 2008-12a-The Remarkable Recurrent Nova in M31-Panchromatic Observations of the 2015 Eruption

NASA Technical Reports Server (NTRS)

Darnley, M. J.; Henze, M.; Bode, M. F.; Hachisu, I.; Hernanz, M.; Hornoch, K.; Hounsell, R.; Kato, M.; Ness, J.- U.; Osborne, J. P.;

New Nova Candidates from the RSBE M31 Nova Survey

NASA Astrophysics Data System (ADS)

Lauber, Stephanie; Rector, Travis A.; Shafter, Allen W.

2015-01-01

Since 1995 the Kitt Peak National Observatory WIYN 0.9-m telescope has been used to monitor M31 for novae as part of the Research-Based Science Education Project (RBSE). The resulting images, which typically cover approximately the inner 20 arc min of M31, are taken through a broad-band H-alpha filter to isolate the strong H-alpha emission lines characteristic of novae shortly after eruption.We are in the process of reanalyzing the entire RBSE data set covering the period between September 1995 and August 2014 in order to produce an up-to-date list of novae from this survey. Here, we present coordinates and H-alpha magnitudes for 4 new nova discoveries not previous reported. Among the new nova discoveries, one system appears spatially coincident with M31N 1988-09a, and is thus a recurrent nova candidate.

Binary supersoft X-ray sources and the supernova Ia progenitor problem

NASA Astrophysics Data System (ADS)

Nelson, Thomas John

In this thesis I present a study of several binary supersoft X-ray sources in order to assess their properties and to determine whether they may be supernova Ia (SN Ia) progenitors. The first chapter is an introduction to the problem and the sources of interest. In the second and third chapters I present an X-ray spectroscopic study of the recurrent nova RS Ophiuchi (RS Oph) during and after its 2006 outburst, carried out with Chandra and XMM-Newton. I discuss the physical origins of the X-ray emission at each stage of the outburst and place the first direct constraints on the mass of the white dwarf, which is very close to the Chandrasekhar limit. I also show that the surface composition of the white dwarf during the supersoft phase is consistent with nuclear processed material, indicating that RS Oph retains mass after each outburst and is likely growing in mass with time, and is therefore a potential SN Ia progenitor. I discuss the lack of accretion signatures in the quiescent emission from RS Oph, which are at odds with the high frequency of nova outbursts, and explore the possibility that an alternative accretion model may account for the quiescent X-ray properties in the system. Finally, in the fourth chapter, I examine the supersoft X-ray source (SSS) population in the nearby galaxy M31 at X-ray, ultraviolet (UV) and optical wavelengths. I explore the long-term behavior of these objects, and find that a much smaller fraction are persistent or recurrent X-ray sources than in the Magellanic Clouds. I carry out a search for counterparts of the SSS using the Galactic Evolution Explorer (GALEX) satellite and the WIYN 3.5m telescope, and find that the majority of sources do not have any UV counterparts. For those that do, I find that the UV sources have properties consistent with young, massive stars in M31. I find indications that some SSS may be in high mass binaries. If these sources are nuclear burning white dwarfs, then they may be the progenitors of the SNe

HUBBLE SPACE TELESCOPE FAR ULTRAVIOLET SPECTROSCOPY OF THE RECURRENT NOVA T PYXIDIS

PubMed Central

Godon, Patrick; Sion, Edward M.; Starrfield, Sumner; Livio, Mario; Williams, Robert E.; Woodward, Charles E.; Kuin, Paul; Page, Kim L.

2018-01-01

With six recorded nova outbursts, the prototypical recurrent nova T Pyxidis (T Pyx) is the ideal cataclysmic variable system to assess the net change of the white dwarf mass within a nova cycle. Recent estimates of the mass ejected in the 2011 outburst ranged from a few ~10−5 M⊙ to 3.3 × 10−4 M⊙, and assuming a mass accretion rate of 10−8−10−7 M⊙ yr−1 for 44 yr, it has been concluded that the white dwarf in T Pyx is actually losing mass. Using NLTE disk modeling spectra to fit our recently obtained Hubble Space Telescope COS and STIS spectra, we find a mass accretion rate of up to two orders of magnitude larger than previously estimated. Our larger mass accretion rate is due mainly to the newly derived distance of T Pyx (4.8 kpc, larger than the previous 3.5 kpc estimate), our derived reddening of E(B − V) = 0.35 (based on combined IUE and GALEX spectra), and NLTE disk modeling (compared to blackbody and raw flux estimates in earlier works). We find that for most values of the reddening (0.25 ≤ E(B−V) ≤ 0.50) and white dwarf mass (0.70 M⊙ ≤ Mwd ≤ 1.35 M⊙) the accreted mass is larger than the ejected mass. Only for a low reddening (~0.25 and smaller) combined with a large white dwarf mass (0.9 M⊙ and larger) is the ejected mass larger than the accreted one. However, the best results are obtained for a larger value of reddening. PMID:29430290

HUBBLE SPACE TELESCOPE FAR ULTRAVIOLET SPECTROSCOPY OF THE RECURRENT NOVA T PYXIDIS.

PubMed

Godon, Patrick; Sion, Edward M; Starrfield, Sumner; Livio, Mario; Williams, Robert E; Woodward, Charles E; Kuin, Paul; Page, Kim L

2014-04-01

With six recorded nova outbursts, the prototypical recurrent nova T Pyxidis (T Pyx) is the ideal cataclysmic variable system to assess the net change of the white dwarf mass within a nova cycle. Recent estimates of the mass ejected in the 2011 outburst ranged from a few ~10 -5 M ⊙ to 3.3 × 10 -4 M ⊙ , and assuming a mass accretion rate of 10 -8 -10 -7 M ⊙ yr -1 for 44 yr, it has been concluded that the white dwarf in T Pyx is actually losing mass. Using NLTE disk modeling spectra to fit our recently obtained Hubble Space Telescope COS and STIS spectra, we find a mass accretion rate of up to two orders of magnitude larger than previously estimated. Our larger mass accretion rate is due mainly to the newly derived distance of T Pyx (4.8 kpc, larger than the previous 3.5 kpc estimate), our derived reddening of E ( B - V ) = 0.35 (based on combined IUE and GALEX spectra), and NLTE disk modeling (compared to blackbody and raw flux estimates in earlier works). We find that for most values of the reddening (0.25 ≤ E ( B - V ) ≤ 0.50) and white dwarf mass (0.70 M ⊙ ≤ M wd ≤ 1.35 M ⊙ ) the accreted mass is larger than the ejected mass. Only for a low reddening (~0.25 and smaller) combined with a large white dwarf mass (0.9 M ⊙ and larger) is the ejected mass larger than the accreted one. However, the best results are obtained for a larger value of reddening.

The Recurrent Nova T CrB Did Not Erupt In 1842

NASA Astrophysics Data System (ADS)

Schaefer, Bradley E.

2013-01-01

The recurrent nova T CrB was one of the first well observed nova eruptions in 1866, and 80 years later it erupted again in 1946. Just after the 1866 eruption, Sir John Herschel reported to the Monthly Notices that he had seen the same star in his naked-eye charting of the sky on 1842 June 9, implying that there was a prior eruption 24 years earlier, with substantial implications for astrophysics. Unfortunately, the chart in the Monthly Notices was ambiguous and misleading, including whether the recorded position is or is not that of T CrB. So it has long been unclear whether T CrB did indeed have an eruption in 1842. To resolve this, I have made complete searches through the various archives with Herschel material, including the large collections at the Harry Ransom Center in Austin, the Royal Astronomical Society, the complete Herschel correspondence, and the Royal Society; plus three smaller archives as well as consulting with various Herschel experts. In one letter from 1866 to William Huggins, Herschel enclosed his own copy of his original observations, and with this all the ambiguities are resolved. It turns out that Herschel's indicated star was at the same position as a steady background star (BD+25 3020, V=7.06, G8V) and not that of T CrB, and Herschel regularly was seeing stars as faint as V=7.5 mag because he was using an opera glass. With this, there is no evidence for a T CrB eruption in 1842. Supported by the National Science Foundation.

On the Progenitor System of V392 Persei

NASA Astrophysics Data System (ADS)

Darnley, M. J.; Starrfield, S.

2018-05-01

A discussion regarding the progenitor system of the nova and dwarf nova system V392 Persei using archival data from 2MASS and WISE. We find that the system is unlikely to contain a luminous red giant donor (i.e. a symbiotic system), but cannot exclude the presence of a lower luminosity red giant or a sub-giant donor. The similarity of the SED of the quiescent V392 Per to that of GK Persei is noted.

Improved adductor function after canine recurrent laryngeal nerve injury and repair using muscle progenitor cells.

PubMed

Paniello, Randal C; Brookes, Sarah; Bhatt, Neel K; Bijangi-Vishehsaraei, Khadijeh; Zhang, Hongji; Halum, Stacey

2017-12-08

Muscle progenitor cells (MPCs) can be isolated from muscle samples and grown to a critical mass in culture. They have been shown to survive and integrate when implanted into rat laryngeal muscles. In this study, the ability of MPC implants to enhance adductor function of reinnervated thyroarytenoid muscles was tested in a canine model. Animal study. Sternocleidomastoid muscle samples were harvested from three canines. Muscle progenitor cells were isolated and cultured to 10 7 cells over 4 to 5 weeks, then implanted into right thyroarytenoid muscles after ipsilateral recurrent laryngeal nerve transection and repair. The left sides underwent the same nerve injury, but no cells were implanted. Laryngeal adductor force was measured pretreatment and again 6 months later, and the muscles were harvested for histology. Muscle progenitor cells were successfully cultured from all dogs. Laryngeal adductor force measurements averaged 60% of their baseline pretreatment values in nonimplanted controls, 98% after implantation with MPCs, and 128% after implantation with motor endplate-enhanced MPCs. Histology confirmed that the implanted MPCs survived, became integrated into thyroarytenoid muscle fibers, and were in close contact with nerve endings, suggesting functional innervation. Muscle progenitor cells were shown to significantly enhance adductor function in this pilot canine study. Patient-specific MPC implantation could potentially be used to improve laryngeal function in patients with vocal fold paresis/paralysis, atrophy, and other conditions. Further experiments are planned. NA. Laryngoscope, 2017. © 2017 The American Laryngological, Rhinological and Otological Society, Inc.

A Search for Ultrafast Novae in M31

NASA Astrophysics Data System (ADS)

Sola, Nicole; Rector, Travis A.; Shafter, Allen W.; Horst, Chuck; Igarashi, Amy; Henze, Martin; Pilachowski, Catherine A.

2018-06-01

Numerous surveys in search of extragalactic novae have been completed over the last century. From Local Group surveys it has been estimated that the number of novae that occur in M31 is approximately 65 yr-1 (Darnley et al. 2006), with a total of more than 1000 having been discovered over the past century. A fraction of these are recurrent novae that recur on the timescales of years to decades (Shafter et al. 2015).Novae typically fade from view on timescales of weeks to months. However, Shara et al. (2017) present models that predict the existence of "ultrafast" novae that have two-magnitude decay times (t2) of less than a day. The remarkable recurrent nova M31N 2008-12a has a t2 time of ~2 days (e.g., Darnley et al. 2016). None faster than this have been seen in M31; however, most surveys of extragalactic novae use cadences of a day or longer, meaning such novae could be missed.In October 2017 we completed a two-week search for ultrafast novae in M31 with the WIYN 0.9m telescope. The telescope's Half-Degree Imager provided a field of view of a quarter square degree, which covers most of M31's bulge and part of the disk. Weather hampered observations on some nights, but for most nights we were able to obtain multiple observations of M31 on a near hourly basis. We present the results of our search.

Dwarf novae

NASA Technical Reports Server (NTRS)

Ladous, Constanze

1993-01-01

Dwarf novae are defined on grounds of their semi-regular brightness variations of some two to five magnitudes on time scales of typically 10 to 100 days. Historically several different classification schemes have been used. Today, dwarf novae are divided into three sub-classes: the U Geminorum stars, the SU Ursae Majoris stars, and the Z Camelopardalis stars. Outbursts of dwarf novae occur at semi-periodic intervals of time, typically every 10 to 100 days; amplitudes range from typically 2 to 5 mag. Within certain limits values are characteristic for each object. Relations between the outburst amplitude, or the total energy released during outburst, and the recurrence time have been found, as well as relations between the orbital period and the outburst decay time, the absolute magnitude during outburst maximum, and the widths of long and short outbursts, respectively. Some dwarf novae are known to have suspended their normal outburst activity altogether for a while. They later resumed it without having undergone any observable changes. The optical colors of dwarf novae all are quite similar during outburst, considerably bluer than during the quiescent state. During the outburst cycle, characteristic loops in the two color diagram are performed. At a time resolution on the order of minutes, strictly periodic photometric changes due to orbital motion become visible in the light curves of dwarf novae. These are characteristic for each system. Remarkably little is known about orbital variations during the course of an outburst. On time-scales of minutes and seconds, further more or less periodic types of variability are seen in dwarf novae. Appreciable flux is emitted by dwarf novae at all wavelengths from the X-rays to the longest IR wavelengths, and in some cases even in the radio. Most dwarf novae exhibit strong emission line spectra in the optical and UV during quiescence, although some have only very weak emissions in the optical and/or weak absorptions at UV

Fermi Establishes Classical Novae as a Distinct Class of Gamma-ray Sources

NASA Technical Reports Server (NTRS)

Ackermann, M.; Ajello, M.; Albert, A.; Baldini, L.; Ballet, J.; Bastieri, D.; Bellazzini, R.; Bissaldi, E.; Blandford, R. D.; Bloom, E. D.;

Multiwavelength observations of nova SMCN 2016-10a - one of the brightest novae ever observed

NASA Astrophysics Data System (ADS)

Aydi, E.; Page, K. L.; Kuin, N. P. M.; Darnley, M. J.; Walter, F. M.; Mróz, P.; Buckley, D. A. H.; Mohamed, S.; Whitelock, P.; Woudt, P.; Williams, S. C.; Orio, M.; Williams, R. E.; Beardmore, A. P.; Osborne, J. P.; Kniazev, A.; Ribeiro, V. A. R. M.; Udalski, A.; Strader, J.; Chomiuk, L.

2018-02-01

We report on multiwavelength observations of nova Small Magellanic Cloud Nova 2016-10a. The present observational set is one of the most comprehensive for any nova in the Small Magellanic Cloud, including low-, medium-, and high-resolution optical spectroscopy and spectropolarimetry from Southern African Large Telescope, Folded Low-Order Yte-Pupil Double-Dispersed Spectrograph, and Southern Astrophysical Research; long-term Optical Gravitational Lensing Experiment V- and I-bands photometry dating back to 6 yr before eruption; Small and Moderate Aperture Research Telescope System optical and near-IR photometry from ˜11 d until over 280 d post-eruption; Swift satellite X-ray and ultraviolet observations from ˜6 d until 319 d post-eruption. The progenitor system contains a bright disc and a main sequence or a sub-giant secondary. The nova is very fast with t2 ≃ 4.0 ± 1.0 d and t3 ≃ 7.8 ± 2.0 d in the V band. If the nova is in the SMC, at a distance of ˜61 ± 10 kpc, we derive MV, max ≃ -10.5 ± 0.5, making it the brightest nova ever discovered in the SMC and one of the brightest on record. At day 5 post-eruption the spectral lines show a He/N spectroscopic class and an Full Width at Half Maximum of ˜3500 km s-1, indicating moderately high ejection velocities. The nova entered the nebular phase ˜20 d post-eruption, predicting the imminent super-soft source turn-on in the X-rays, which started ˜28 d post-eruption. The super-soft source properties indicate a white dwarf mass between 1.2 and 1.3 M⊙ in good agreement with the optical conclusions.

ToO Galactic Nova -- Michelle ``Quick Response''

NASA Astrophysics Data System (ADS)

Helton, L. Andrew; Woodward, Chick; Evans, Nye; Geballe, Tom; Spitzer Nova Team

2006-08-01

Stars are the engines of energy production and chemical evolution in our Universe, depositing radiative and mechanical energy into their environments and enriching the ambient ISM with elements synthesized in their interiors and dust grains condensed in their atmospheres. Classical novae (CN) contribute to this cycle of chemical enrichment through explosive nucleosynthesis and the violent ejection of material dredged from the white dwarf progenitor and mixed with the accreted surface layers. We propose to obtain mid-IR spectra of a new galactic CN in outburst to investigate aspects of the CN phenomenon including the in situ formation and mineralogy of nova dust and the elemental abundances resulting from thermonuclear runaway. Synoptic, high S/N Michelle spectra permit: 1) determination of the grain size distribution and mineral composition of nova dust; 2) estimation of chemical abundances of nova ejecta from coronal and other emission line spectroscopy; and 3) measurement of the density and masses of the ejecta. This Gemini `Target of Opportunity' initiative (trigger K=5- 8 mag, assuming adequate PWFS guide stars exist) complements our extensive Spitzer, Chandra, Swift, XMM-Newton CN DDT/ToO programs.

Synoptic Mid-IR Spectra ToO Novae

NASA Astrophysics Data System (ADS)

Helton, L. Andrew; Woodward, Chick; Evans, Nye; Geballe, Tom; Spitzer Nova Team

2007-02-01

Stars are the engines of energy production and chemical evolution in our Universe, depositing radiative and mechanical energy into their environments and enriching the ambient ISM with elements synthesized in their interiors and dust grains condensed in their atmospheres. Classical novae (CN) contribute to this cycle of chemical enrichment through explosive nucleosynthesis and the violent ejection of material dredged from the white dwarf progenitor and mixed with the accreted surface layers. We propose to obtain mid-IR spectra of a new galactic CN in outburst to investigate aspects of the CN phenomenon including the in situ formation and mineralogy of nova dust and the elemental abundances resulting from thermonuclear runaway. Synoptic, high S/N Michelle spectra permit: 1) determination of the grain size distribution and mineral composition of nova dust; 2) estimation of chemical abundances of nova ejecta from coronal and other emission line spectroscopy; and 3) measurement of the density and masses of the ejecta. This Gemini `Target of Opportunity' initiative (trigger K=5- 8 mag, assuming adequate PWFS guide stars exist) complements our extensive Spitzer, Chandra, Swift, XMM-Newton CN DDT/ToO programs.

Fermi establishes classical novae as a distinct class of gamma-ray sources

DOE PAGES

Cheung, C. C.

2014-07-31

A classical nova results from runaway thermonuclear explosions on the surface of a white dwarf that accretes matter from a low-mass main-sequence stellar companion. In 2012 and 2013, three novae were detected in γ rays and stood in contrast to the first γ-ray detected nova V407 Cygni 2010, which belongs to a rare class of symbiotic binary systems. Despite likely differences in the compositions and masses of their white dwarf progenitors, the three classical novae are similarly characterized as soft spectrum transient γ-ray sources detected over 2-3 week durations. The γ-ray detections point to unexpected high-energy particle acceleration processes linkedmore » to the mass ejection from thermonuclear explosions in an unanticipated class of Galactic γ-ray sources.« less

Models for various aspects of dwarf novae and nova-like stars

NASA Technical Reports Server (NTRS)

Ladous, Constanze

1993-01-01

The first attempts to explain the nature of dwarf novae were based on the assumption of single-star phenomena, in which emission lines were assumed to be caused by circumstellar gas shells. The outburst behavior was tentatively ascribed to the kind of (also not understood) mechanism leading to nova outbursts. The realization that some, and possibly all, dwarf novae and nova-like stars (and novae) are binaries eventually led to models which bore more and more similarities to the modern interpretation on the basis of the Roche model. Not all cataclysmic variables are known binaries. In fact, with respect to the entire number of known objects, the proven binaries are still the minority, but all the brightest variables are in fact known to binaries. Not a single system is known which exhibits the usual characteristics of a cataclysmic variable and at the same time can be declared with certainty to be a single star. Two systems are known, the dwarf nova EY Cyg and the recurrent nova V1017 Sgr, in which, in spite of intensive search, no radial velocity variations have been found; but they still exhibit composite spectra consisting of a bright continuum, an emission spectrum, and a cool absorption spectrum. If the Roche model is correct, it is to be expected that a small percentage of objects is viewed pole-on, so orbital motions do not make themselves felt as Doppler shifts of spectral lines. So even these two systems support the hypothesis that all cataclysmic variables (with the possible exception of symbiotic stars) are binaries. In cataclysmic variables, it seems that the brightness changes observed in dwarf novae and nova-like stars in the optical and the UV are due directly to changes in the accretion disks. The study and understanding of accretion disks in these systems can bear potentially valuable consequences for many other fields in astronomy. The observed spectra of dwarf novae and nova-like stars comprise a fairly large range: pure emission spectra, pure

SOFIA: A Promising Resource for Future Nova Studies

NASA Astrophysics Data System (ADS)

Helton, L. A.; Sofia Science Team

2014-12-01

The Stratospheric Observatory for Infrared Astronomy (SOFIA) is a 2.5-m telescope carried on board a Boeing 747-SP aircraft. Optimized for observations from infrared through sub-mm wavelengths, SOFIA observes from an altitude of 37,000 - 45,000 feet, above 99% of the atmospheric water vapor. The Observatory's complement of instruments possesses a broad range of capabilities, many of which are especially well suited for observations of classical novae, recurrent novae, and other cataclysmic variables. Here we present a selection of the instruments available on board SOFIA that may prove to be very useful for future novae studies.

Dust, Abundances, and the Evolution of Novae

NASA Astrophysics Data System (ADS)

Woodward, Charles; Bode, Michael; Evans, Anuerin; Geballe, Thomas; Gehrz, Robert; Helton, Andrew; Krautter, Joachim; Lynch, David; Ness, Jan-Uwe; Rudy, Richard; Schwarz, Greg; Shore, Steve; Starrfield, Sumner; Truran, James; Vanlandingham, Karen; Wagner, R. Mark

2008-03-01

Evolved stars are the engines of energy production and chemical evolution in our Universe. They deposit radiative and mechanical energy into their environments. They enrich the ambient ISM with elements synthesized in their interiors and dust grains condensed in their atmospheres. Classical novae (CNe) contribute to this cycle of chemical enrichment through explosive nucleosynthesis and the violent ejection of material dredged from the white dwarf progenitor and mixed with the accreted surface layers. Our capstone study of 10 CNe will provide an ensemble of objects, well-populated in CNe parameter space (fast, slow, 'coronal', dusty) for detailed photoionization modeling and analysis. CNe are laboratories in which several poorly-understood astrophysical processes (e.g., mass transfer, thermonuclear runaway, optically thick winds, common envelope evolution, molecule and grain formation, coronal emission) may be observed. With Spitzer's unique wavelength coverage and point-source sensitivity we can: (i) investigate the in situ formation, astromineralogy, and processing of nova dust, (ii) determine the ejecta elemental abundances resulting from thermonuclear runaway, (iii) constrain the correlation of ejecta mass with progenitor type, (iv) measure the bolometric luminosity of the outburst, and (v) characterize the kinematics and structure of the ejected envelopes. Extensive ground-based and space-based (Chandra, Swift, XMM-Newton) programs led by team CoIs will complement Spitzer CNe observations.

Beryllium detection in the very fast nova ASASSN-16kt (V407 Lupi)

NASA Astrophysics Data System (ADS)

Izzo, L.; Molaro, P.; Bonifacio, P.; Della Valle, M.; Cano, Z.; de Ugarte Postigo, A.; Prieto, J. L.; Thöne, C.; Vanzi, L.; Zapata, A.; Fernandez, D.

2018-02-01

We present high-resolution spectroscopic observations of the fast nova ASASSN-16kt (V407 Lup). A close inspection of spectra obtained at early stages has revealed the presence of low-ionization lines, and among the others we have identified the presence of the ionised 7Be doublet in a region relatively free from possible contaminants. After studying their intensities, we have inferred that ASASSN-16kt has produced (5.9 - 7.7)× 10-9 M⊙ of 7Be. The identification of bright Ne lines may suggest that the nova progenitor is a massive (1.2 M⊙) oxygen-neon white dwarf. The high outburst frequency of oxygen-neon novae implies that they likely produce an amount of Be similar, if not larger, to that produced by carbon-oxygen novae, then confirming that classical novae are among the main factories of lithium in the Galaxy.

Synthesis of C-rich dust in CO nova outbursts

NASA Astrophysics Data System (ADS)

José, Jordi; Halabi, Ghina M.; El Eid, Mounib F.

2016-09-01

Context. Classical novae are thermonuclear explosions that take place in the envelopes of accreting white dwarfs in stellar binary systems. The material transferred onto the white dwarf piles up under degenerate conditions, driving a thermonuclear runaway. In these outbursts, about 10-7-10-3 M⊙, enriched in CNO and sometimes other intermediate-mass elements (e.g., Ne, Na, Mg, or Al for ONe novae) are ejected into the interstellar medium. The large concentrations of metals spectroscopically inferred in the nova ejecta reveal that the solar-like material transferred from the secondary mixes with the outermost layers of the underlying white dwarf. Aims: Most theoretical models of nova outbursts reported to date yield, on average, outflows characterized by O > C, from which, in principle, only oxidized condensates (e.g., O-rich grains) would be expected. Methods: To specifically address whether CO novae can actually produce C-rich dust, six different hydrodynamic nova models have been evolved, from accretion to the expansion and ejection stages, with different choices for the composition of the substrate with which the solar-like accreted material mixes. Updated chemical profiles inside the H-exhausted core have been used, based on stellar evolution calculations for a progenitor of 8 M⊙ through H- and He-burning phases. Results: We show that these profiles lead to C-rich ejecta after the nova outburst. This extends the possible contribution of novae to the inventory of presolar grains identified in meteorites, particularly in a number of carbonaceous phases (I.e., nanodiamonds, silicon carbides, and graphites).

OGLE ATLAS OF CLASSICAL NOVAE. II. MAGELLANIC CLOUDS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mróz, P.; Udalski, A.; Poleski, R.

2016-01-15

The population of classical novae in the Magellanic Clouds was poorly known because of a lack of systematic studies. There were some suggestions that nova rates per unit mass in the Magellanic Clouds were higher than in any other galaxy. Here, we present an analysis of data collected over 16 years by the OGLE survey with the aim of characterizing the nova population in the Clouds. We found 20 eruptions of novae, half of which are new discoveries. We robustly measure nova rates of 2.4 ± 0.8 yr{sup −1} (LMC) and 0.9 ± 0.4 yr{sup −1} (SMC) and confirm that the K-band luminosity-specific novamore » rates in both Clouds are 2–3 times higher than in other galaxies. This can be explained by the star formation history in the Magellanic Clouds, specifically the re-ignition of the star formation rate a few Gyr ago. We also present the discovery of the intriguing system OGLE-MBR133.25.1160, which mimics recurrent nova eruptions.« less

X-ray Novae and Related Systems

NASA Technical Reports Server (NTRS)

Wheeler, J. Craig; Kim, Soonwook; Mineshige, Shin

1992-01-01

Accretion disk thermal instability models have been successful in accounting for the basic observations of dwarf novae and the steady behavior of nova-like systems. Models for the dwarf-nova like variability of the old nova and intermediate polar GK Per give good agreement with the burst amplitude, profile and recurrence time in the optical and UV. A month-long 'precursor plateau' in the UV is predicted for the expected 1992 outburst prior to the rise to maximum in the optical and UV. The models for the time scales of the outbursts and corresponding UV spectra at maximum are consistent with the inner edge of the accretion disk being essentially constant between quiescence and outburst and a factor of four larger than the co-rotation radius. These conclusions represent a challenge to the standard theory of magnetic accretion. Disk instability models have also given a good representation of the soft X-ray and optical outbursts of the X-ray novae A0620-00 and GS2000+25. Formation of coronae above the disk, heated by magneto-acoustic flux from the disk, may account for the temporal and spectral properties of the hard X-ray and gamma ray emission of related sources such as Cyg X-1, GS 2023+33 (V404 Cyg), IE 1740.7-2942 (the 'Galactic Center' Einstein Source), and GS 1124-683 (Nova Muscae).

FROM X-RAY DIPS TO ECLIPSE: WITNESSING DISK REFORMATION IN THE RECURRENT NOVA U Sco

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ness, J.-U.; Talavera, A.; Gonzalez-Riestra, R.

2012-01-20

The tenth recorded outburst of the recurrent eclipsing nova U Sco was observed simultaneously in X-ray, UV, and optical by XMM-Newton on days 22.9 and 34.9 after the outburst. Two full passages of the companion in front of the nova ejecta were observed, as was the reformation of the accretion disk. On day 22.9, we observed smooth eclipses in UV and optical but deep dips in the X-ray light curve that disappeared by day 34.9, yielding clean eclipses in all bands. X-ray dips can be caused by clumpy absorbing material that intersects the line of sight while moving along highlymore » elliptical trajectories. Cold material from the companion could explain the absence of dips in UV and optical light. The disappearance of X-ray dips before day 34.9 implies significant progress in the formation of the disk. The X-ray spectra contain photospheric continuum emission plus strong emission lines, but no clear absorption lines. Both continuum and emission lines in the X-ray spectra indicate a temperature increase from day 22.9 to day 34.9. We find clear evidence in the spectra and light curves for Thompson scattering of the photospheric emission from the white dwarf. Photospheric absorption lines can be smeared out during scattering in a plasma of fast electrons. We also find spectral signatures of resonant line scattering that lead to the observation of the strong emission lines. Their dominance could be a general phenomenon in high-inclination systems such as Cal 87.« less

Novae as a Class of Transient X-ray Sources

NASA Technical Reports Server (NTRS)

Mukai, K.; Orio, M.; Valle, M. Della

2007-01-01

Motivated by the recently discovered class of faint (10(exp 34)-10(exp 35) ergs/s) X-ray transients in the Galactic Center region, we investigate the 2-10 keV properties of classical and recurrent novae. Existing data are consistent with the idea that all classical novae are transient X-ray sources with durations of months to years and peak luminosities in the 10(exp 34)-10(exp 35)ergs/s range. This makes classical novae a viable candidate class for the faint Galactic Center transients. We estimate the rate of classical novae within a 15 arcmin radius region centered on the Galactic Center (roughly the field of view of XMM-Newton observations centered on Sgr A*) to be approx.0.1 per year. Therefore, it is plausible that some of the Galactic Center transients that have been announced to date are unrecognized classical novae. The continuing monitoring of the Galactic Center region carried out by Chandra and XMM-Newton may therefore provide a new method to detect classical novae in this crowded and obscured region, an

Nonradial Pulsations in Post-outburst Novae

NASA Astrophysics Data System (ADS)

Wolf, William M.; Townsend, Richard H. D.; Bildsten, Lars

2018-03-01

After an optical peak, a classical or recurrent nova settles into a brief (days to years) period of quasi-stable thermonuclear burning in a compact configuration nearly at the white dwarf (WD) radius. During this time, the underlying WD becomes visible as a strong emitter of supersoft X-rays. Observations during this phase have revealed oscillations in the X-ray emission with periods on the order of tens of seconds. A proposed explanation for the source of these oscillations is internal gravity waves excited by nuclear reactions at the base of the hydrogen-burning layer. In this work, we present the first models exhibiting unstable surface g-modes with periods similar to oscillation periods found in galactic novae. However, when comparing mode periods of our models to the observed oscillations of several novae, we find that the modes that are excited have periods shorter than that observed.

A Hubble Space Telescope survey for Novae in M87. II. Snuffing out the maximum magnitude–rate of decline relation for novae as a non-standard candle, and a prediction of the existence of ultrafast novae

DOE PAGES

Shara, Michael M.; Doyle, Trisha; Lauer, Tod R.; ...

2017-04-20

The extensive grid of numerical simulations of nova eruptions first predicted that some classical novae might significantly deviate from the Maximum Magnitude–Rate of Decline (MMRD) relation, which purports to characterize novae as standard candles. Kasliwal et al. have announced the observational detection of a new class of faint, fast classical novae in the Andromeda galaxy. These objects deviate strongly from the MMRD relationship, as predicted by Yaron et al. Recently, Shara et al. reported the first detections of faint, fast novae in M87. These previously overlooked objects are as common in the giant elliptical galaxy M87 as they are inmore » the giant spiral M31; they comprise about 40% of all classical nova eruptions and greatly increase the observational scatter in the MMRD relation. We use the extensive grid of the nova simulations of Yaron et al. to identify the underlying causes of the existence of faint, fast novae. These are systems that have accreted, and can thus eject, only very low-mass envelopes, of the order of 10 –7–10 –8 M ⊙, on massive white dwarfs. Such binaries include, but are not limited to, the recurrent novae. As a result, these same models predict the existence of ultrafast novae that display decline times, t 2, to be as short as five hours. We outline a strategy for their future detection.« less

A Hubble Space Telescope survey for Novae in M87. II. Snuffing out the maximum magnitude–rate of decline relation for novae as a non-standard candle, and a prediction of the existence of ultrafast novae

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shara, Michael M.; Doyle, Trisha; Lauer, Tod R.

The extensive grid of numerical simulations of nova eruptions first predicted that some classical novae might significantly deviate from the Maximum Magnitude–Rate of Decline (MMRD) relation, which purports to characterize novae as standard candles. Kasliwal et al. have announced the observational detection of a new class of faint, fast classical novae in the Andromeda galaxy. These objects deviate strongly from the MMRD relationship, as predicted by Yaron et al. Recently, Shara et al. reported the first detections of faint, fast novae in M87. These previously overlooked objects are as common in the giant elliptical galaxy M87 as they are inmore » the giant spiral M31; they comprise about 40% of all classical nova eruptions and greatly increase the observational scatter in the MMRD relation. We use the extensive grid of the nova simulations of Yaron et al. to identify the underlying causes of the existence of faint, fast novae. These are systems that have accreted, and can thus eject, only very low-mass envelopes, of the order of 10 –7–10 –8 M ⊙, on massive white dwarfs. Such binaries include, but are not limited to, the recurrent novae. As a result, these same models predict the existence of ultrafast novae that display decline times, t 2, to be as short as five hours. We outline a strategy for their future detection.« less

A Hubble Space Telescope Survey for Novae in M87. II. Snuffing out the Maximum Magnitude–Rate of Decline Relation for Novae as a Non-standard Candle, and a Prediction of the Existence of Ultrafast Novae

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shara, Michael M.; Doyle, Trisha; Zurek, David

The extensive grid of numerical simulations of nova eruptions from the work of Yaron et al. first predicted that some classical novae might significantly deviate from the Maximum Magnitude–Rate of Decline (MMRD) relation, which purports to characterize novae as standard candles. Kasliwal et al. have announced the observational detection of a new class of faint, fast classical novae in the Andromeda galaxy. These objects deviate strongly from the MMRD relationship, as predicted by Yaron et al. Recently, Shara et al. reported the first detections of faint, fast novae in M87. These previously overlooked objects are as common in the giantmore » elliptical galaxy M87 as they are in the giant spiral M31; they comprise about 40% of all classical nova eruptions and greatly increase the observational scatter in the MMRD relation. We use the extensive grid of the nova simulations of Yaron et al. to identify the underlying causes of the existence of faint, fast novae. These are systems that have accreted, and can thus eject, only very low-mass envelopes, of the order of 10{sup −7}–10{sup −8} M {sub ⊙}, on massive white dwarfs. Such binaries include, but are not limited to, the recurrent novae. These same models predict the existence of ultrafast novae that display decline times, t {sub 2,} to be as short as five hours. We outline a strategy for their future detection.« less

Breaking the Habit: The Peculiar 2016 Eruption of the Unique Recurrent Nova M31N 2008-12a

NASA Astrophysics Data System (ADS)

Henze, M.; Darnley, M. J.; Williams, S. C.; Kato, M.; Hachisu, I.; Anupama, G. C.; Arai, A.; Boyd, D.; Burke, D.; Ciardullo, R.; Chinetti, K.; Cook, L. M.; Cook, M. J.; Erdman, P.; Gao, X.; Harris, B.; Hartmann, D. H.; Hornoch, K.; Horst, J. Chuck; Hounsell, R.; Husar, D.; Itagaki, K.; Kabashima, F.; Kafka, S.; Kaur, A.; Kiyota, S.; Kojiguchi, N.; Kučáková, H.; Kuramoto, K.; Maehara, H.; Mantero, A.; Masci, F. J.; Matsumoto, K.; Naito, H.; Ness, J.-U.; Nishiyama, K.; Oksanen, A.; Osborne, J. P.; Page, K. L.; Paunzen, E.; Pavana, M.; Pickard, R.; Prieto-Arranz, J.; Rodríguez-Gil, P.; Sala, G.; Sano, Y.; Shafter, A. W.; Sugiura, Y.; Tan, H.; Tordai, T.; Vraštil, J.; Wagner, R. M.; Watanabe, F.; Williams, B. F.; Bode, M. F.; Bruno, A.; Buchheim, B.; Crawford, T.; Goff, B.; Hernanz, M.; Igarashi, A. S.; José, J.; Motta, M.; O’Brien, T. J.; Oswalt, T.; Poyner, G.; Ribeiro, V. A. R. M.; Sabo, R.; Shara, M. M.; Shears, J.; Starkey, D.; Starrfield, S.; Woodward, C. E.

2018-04-01

Since its discovery in 2008, the Andromeda galaxy nova M31N 2008-12a has been observed in eruption every single year. This unprecedented frequency indicates an extreme object, with a massive white dwarf and a high accretion rate, which is the most promising candidate for the single-degenerate progenitor of a Type Ia supernova known to date. The previous three eruptions of M31N 2008-12a have displayed remarkably homogeneous multiwavelength properties: (i) from a faint peak, the optical light curve declined rapidly by two magnitudes in less than two days, (ii) early spectra showed initial high velocities that slowed down significantly within days and displayed clear He/N lines throughout, and (iii) the supersoft X-ray source (SSS) phase of the nova began extremely early, six days after eruption, and only lasted for about two weeks. In contrast, the peculiar 2016 eruption was clearly different. Here we report (i) the considerable delay in the 2016 eruption date, (ii) the significantly shorter SSS phase, and (iii) the brighter optical peak magnitude (with a hitherto unobserved cusp shape). Early theoretical models suggest that these three different effects can be consistently understood as caused by a lower quiescence mass accretion rate. The corresponding higher ignition mass caused a brighter peak in the free–free emission model. The less massive accretion disk experienced greater disruption, consequently delaying the re-establishment of effective accretion. Without the early refueling, the SSS phase was shortened. Observing the next few eruptions will determine whether the properties of the 2016 outburst make it a genuine outlier in the evolution of M31N 2008-12a.

The 2011 Outburst of Recurrent Nova T Pyx: X-Ray Observations Expose the White Dwarf Mass and Ejection Dynamics

NASA Technical Reports Server (NTRS)

Chomiuk, Laura; Nelson, Thomas; Mukai, Koji; Solokoski, J. L.; Rupen, Michael P.; Page, Kim L.; Osborne, Julian P.; Kuulkers, Erik; Mioduszewski, Amy J.; Roy, Nirupam;

The 2011 outburst of recurrent nova T Pyx: X-ray observations expose the white dwarf mass and ejection dynamics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chomiuk, Laura; Nelson, Thomas; Mukai, Koji

2014-06-20

The recurrent nova T Pyx underwent its sixth historical outburst in 2011, and became the subject of an intensive multi-wavelength observational campaign. We analyze data from the Swift and Suzaku satellites to produce a detailed X-ray light curve augmented by epochs of spectral information. X-ray observations yield mostly non-detections in the first four months of outburst, but both a super-soft and hard X-ray component rise rapidly after Day 115. The super-soft X-ray component, attributable to the photosphere of the nuclear-burning white dwarf, is relatively cool (∼45 eV) and implies that the white dwarf in T Pyx is significantly below themore » Chandrasekhar mass (∼1 M {sub ☉}). The late turn-on time of the super-soft component yields a large nova ejecta mass (≳ 10{sup –5} M {sub ☉}), consistent with estimates at other wavelengths. The hard X-ray component is well fit by a ∼1 keV thermal plasma, and is attributed to shocks internal to the 2011 nova ejecta. The presence of a strong oxygen line in this thermal plasma on Day 194 requires a significantly super-solar abundance of oxygen and implies that the ejecta are polluted by white dwarf material. The X-ray light curve can be explained by a dual-phase ejection, with a significant delay between the first and second ejection phases, and the second ejection finally released two months after outburst. A delayed ejection is consistent with optical and radio observations of T Pyx, but the physical mechanism producing such a delay remains a mystery.« less

The Accretion Disk and the Boundary Layer of the Symbiotic Recurrent Nova T Corona Borealis

NASA Astrophysics Data System (ADS)

Mukai, Koji; Luna, Gerardo; Nelson, Thomas; Sokoloski, Jennifer L.; Lucy, Adrian; Nuñez, Natalia

2017-08-01

T Corona Borealis is one of four known Galactic recurrent symbiotic novae, red giant-white dwarf binaries from which multiple thermonuclear runaway (TNR) events, or nova eruptions, have been observed. TNR requires high pressure at the base of the accreted envelope, and a recurrence time of less than a century almost certainly requires both high white dwarf mass and high accretion rate. The eruptions of T CrB were observed in 1866 and 1946; if the 80 year interval is typical, the next eruption would be expected within the next decade or two. Optical observations show that T CrB has entered a super-active state starting in 2015, similar to that seen in 1938, 8 years before the last eruption. In quiescence, T CrB is a known, bright hard X-ray source that has been detected in the Swift/BAT all-sky survey. Here we present the result of our NuSTAR observation of T CrB in 2015, when it had started to brighten but had not yet reached the peak of the super-active state. We were able to fit the spectrum with an absorbed cooling flow model with reflection, with a reflection amplitude of 1.0. We also present recent Swift and XMM-Newton observations during the peak of the super-active state, when T CrB had faded dramatically in the BAT band. T CrB is found to be much more luminous in the UV, while the X-ray spectrum became complex including a soft, optically thick component. We present our interpretation of the overall variability as due to instability of a large disk, and of the X-rays as due to emission from the boundary layer. In our view, the NuSTAR observation was performed when the boundary layer was optically thin, and the reflection was only from the white dwarf surface that subtended 2π steradian of the sky as seen from the emission region. With these assumptions, we infer the white dwarf in the T CrB system to have a mass of ~1.2 Msun. During the very active state, the boundary layer had turned partially optically thick and produced the soft X-ray component, while

Exquisite Nova Light Curves from the Solar Mass Ejection Imager (SMEI)

NASA Astrophysics Data System (ADS)

Hounsell, R.; Bode, M. F.; Hick, P. P.; Buffington, A.; Jackson, B. V.; Clover, J. M.; Shafter, A. W.; Darnley, M. J.; Mawson, N. R.; Steele, I. A.; Evans, A.; Eyres, S. P. S.; O'Brien, T. J.

2010-11-01

We present light curves of three classical novae (CNe; KT Eridani, V598 Puppis, V1280 Scorpii) and one recurrent nova (RS Ophiuchi) derived from data obtained by the Solar Mass Ejection Imager (SMEI) on board the Coriolis satellite. SMEI provides near complete skymap coverage with precision visible-light photometry at 102 minute cadence. The light curves derived from these skymaps offer unprecedented temporal resolution around, and especially before, maximum light, a phase of the eruption normally not covered by ground-based observations. They allow us to explore fundamental parameters of individual objects including the epoch of the initial explosion, the reality and duration of any pre-maximum halt (found in all three fast novae in our sample), the presence of secondary maxima, speed of decline of the initial light curve, plus precise timing of the onset of dust formation (in V1280 Sco) leading to estimation of the bolometric luminosity, white dwarf mass, and object distance. For KT Eri, Liverpool Telescope SkyCamT data confirm important features of the SMEI light curve and overall our results add weight to the proposed similarities of this object to recurrent rather than to CNe. In RS Oph, comparison with hard X-ray data from the 2006 outburst implies that the onset of the outburst coincides with extensive high-velocity mass loss. It is also noted that two of the four novae we have detected (V598 Pup and KT Eri) were only discovered by ground-based observers weeks or months after maximum light, yet these novae reached peak magnitudes of 3.46 and 5.42, respectively. This emphasizes the fact that many bright novae per year are still overlooked, particularly those of the very fast speed class. Coupled with its ability to observe novae in detail even when relatively close to the Sun in the sky, we estimate that as many as five novae per year may be detectable by SMEI.

The Radio Light Curve of the Gamma-Ray Nova in V407 CYG: Thermal Emission from the Ionized Symbiotic Envelope, Devoured from Within by the Nova Blast

NASA Technical Reports Server (NTRS)

Chomiuk, Laura; Krauss, Miriam I.; Rupen, Michael P.; Nelson, Thomas; Roy, Nirupam; Sokoloski, Jennifer L.; Mukai, Koji; Munari, Ulisse; Mioduszewski, Amy; Weston, Jeninfer;

Assisted stellar suicide: the wind-driven evolution of the recurrent nova T Pyxidis

NASA Astrophysics Data System (ADS)

Knigge, Ch.; King, A. R.; Patterson, J.

2000-12-01

We show that the extremely high luminosity of the short-period recurrent nova T Pyx in quiescence can be understood if this system is a wind-driven supersoft x-ray source (SSS). In this scenario, a strong, radiation-induced wind is excited from the secondary star and accelerates the binary evolution. The accretion rate is therefore much higher than in an ordinary cataclysmic binary at the same orbital period, as is the luminosity of the white dwarf primary. In the steady state, the enhanced luminosity is just sufficient to maintain the wind from the secondary. The accretion rate and luminosity predicted by the wind-driven model for T Pyx are in good agreement with the observational evidence. X-ray observations with Chandra or XMM may be able to confirm T Pyx's status as a SSS. T Pyx's lifetime in the wind-driven state is on the order of a million years. Its ultimate fate is not certain, but the system may very well end up destroying itself, either via the complete evaporation of the secondary star, or in a Type Ia supernova if the white dwarf reaches the Chandrasekhar limit. Thus either the primary, the secondary, or both may currently be committing assisted stellar suicide.

Overshoot Convective Mixing in Nova Outbursts

NASA Astrophysics Data System (ADS)

Glasner, A. S.; Livne, E.; Truran, J. W.

2014-12-01

We present a 2D study of the overshoot convective mechanism in nova outbursts for a wide range of possible compositions of the layer underlying the accreted envelope. Previous surveys studied this mechanism only for solar composition matter accreted on top of carbon oxygen (CO) white dwarfs. Since, during the runaway, mixing with carbon enhances the hydrogen burning rates dramatically, one should question whether significant enrichment of the ejecta is possible also for other underlying compositions (He, O, Ne, Mg) predicted by stellar evolution models. When needed we upgraded our reaction network and simulated several non-carbon cases. Despite large differences in rates, time scales and energetics, our results show that the convective dredge up mechanism predicts significant enrichment in all cases, including that of helium enrichment in recurrent novae.

A Twenty-Year Survey of Novae in M31

NASA Astrophysics Data System (ADS)

Crayton, Hannah; Rector, Travis A.; Walentosky, Matthew J.; Shafter, Allen W.; Lauber, Stephanie; Pilachowski, Catherine A.; RBSE Nova Search Team

2018-06-01

Numerous surveys of M31 in search of extragalactic novae have been completed over the last century, with a total of more than 1000 having been discovered during this time. From these surveys it has been estimated that the number of novae that occur in M31 is approximately 65 yr-1 (Darnley et al. 2006). A fraction of these are recurrent novae that recur on the timescales of years to decades (Shafter et al. 2015). From 1997 to 2017 we completed observations of M31 with the KPNO/WIYN 0.9-meter telescope, which offers a wide field of view suitable for surveying nearly all of the bulge and much of the disk of M31. Observations were completed in Hα so as to better detect novae in the bulge of the galaxy, where most novae reside. Our survey achieves a limiting absolute magnitude per epoch of MHα ∼ 7.5 mag, which prior M31 nova surveys in Hα (e.g., Ciardullo et al. 1987; Shafter & Irby 2001) have shown to be sufficiently deep to detect a typical nova several months after eruption. By completing nearly all of the observations with the same telescope, cameras, and filters we were able to obtain a remarkably consistent dataset.Our survey offers several benefits as compared to prior surveys. Nearly 200 epochs of observations were completed during the survey period. Observations were typically completed on a monthly basis; although on several occasions we completed weekly and nightly observations to search for novae with faster decay rates. Thus we were sensitive to most of the novae that erupted in M31 during the survey period.Over twenty years we detected 316 novae. Our survey found 85% of the novae in M31 that were reported by other surveys completed during the same time range and in the same survey area as ours (Pietsch et al. 2007). We also discovered 39 novae that were not found by other surveys. We present the complete catalog of novae from our survey, along with example light curves. Among other uses, our catalog will be useful for improving estimates of nova rate

Proper-motion age dating of the progeny of Nova Scorpii AD 1437.

PubMed

Shara, M M; Iłkiewicz, K; Mikołajewska, J; Pagnotta, A; Bode, M F; Crause, L A; Drozd, K; Faherty, J; Fuentes-Morales, I; Grindlay, J E; Moffat, A F J; Pretorius, M L; Schmidtobreick, L; Stephenson, F R; Tappert, C; Zurek, D

2017-08-30

'Cataclysmic variables' are binary star systems in which one star of the pair is a white dwarf, and which often generate bright and energetic stellar outbursts. Classical novae are one type of outburst: when the white dwarf accretes enough matter from its companion, the resulting hydrogen-rich atmospheric envelope can host a runaway thermonuclear reaction that generates a rapid brightening. Achieving peak luminosities of up to one million times that of the Sun, all classical novae are recurrent, on timescales of months to millennia. During the century before and after an eruption, the 'novalike' binary systems that give rise to classical novae exhibit high rates of mass transfer to their white dwarfs. Another type of outburst is the dwarf nova: these occur in binaries that have stellar masses and periods indistinguishable from those of novalikes but much lower mass-transfer rates, when accretion-disk instabilities drop matter onto the white dwarfs. The co-existence at the same orbital period of novalike binaries and dwarf novae-which are identical but for their widely varying accretion rates-has been a longstanding puzzle. Here we report the recovery of the binary star underlying the classical nova eruption of 11 March AD 1437 (refs 12, 13), and independently confirm its age by proper-motion dating. We show that, almost 500 years after a classical-nova event, the system exhibited dwarf-nova eruptions. The three other oldest recovered classical novae display nova shells, but lack firm post-eruption ages, and are also dwarf novae at present. We conclude that many old novae become dwarf novae for part of the millennia between successive nova eruptions.

Swift UVOT observations of the SMC nova MASTER OT J010603.18-744715.8

NASA Astrophysics Data System (ADS)

Kuin, N. P. M.; Page, K. L.; Williams, S. C.; Darnley, M. J.; Shore, S. N.; Walter, F. M.

2016-10-01

Since its discovery at magnitude 10.9 on 2016-10-14.19341 UT (Shumkov et al, ATEL #9621) and spectroscopic confirmation (Williams and Darnley, ATEL #9628) pre-discovery data from the OGLE team (Mroz and Udalski, ATEL #9622, and MASTER (Lipunov et al., ATEL #9631) revealed the progenitor magnitude and pushed back the appearance of the nova to magnitude 8.5 on 2016, Oct 9.808.

Reduced survival in patients with early-stage non-small-cell lung cancer is associated with high pleural endothelial progenitor cell levels.

PubMed

Pirro, Matteo; Cagini, Lucio; Mannarino, Massimo R; Andolfi, Marco; Potenza, Rossella; Paciullo, Francesco; Bianconi, Vanessa; Frangione, Maria Rosaria; Bagaglia, Francesco; Puma, Francesco; Mannarino, Elmo

2016-12-01

Endothelial progenitor cells are capable of contributing to neovascularization in tumours. In patients with either malignant or transudative pleural effusion, we tested the presence of pleural endothelial progenitor cells. We also measured the number of endothelial progenitor cells in post-surgery pleural drainage of either patients with early non-small-cell lung cancer or control patients with benign lung disease undergoing pulmonary resection. The prospective influence of post-surgery pleural-drainage endothelial progenitor cells on cancer recurrence/survival was investigated. Pleural endothelial progenitor cell levels were quantified by fluorescence-activated cell sorting analysis in pleural effusion of 15 patients with late-stage non-small-cell lung cancer with pleural involvement and in 15 control patients with congestive heart failure. Also, pleural-drainage endothelial progenitor cells were measured in pleural-drainage fluid 48 h after surgery in 64 patients with early-stage non-small-cell lung cancer and 20 benign lung disease patients undergoing pulmonary resection. Cancer recurrence and survival was evaluated in patients with high pleural-drainage endothelial progenitor cell levels. The number of pleural endothelial progenitor cells was higher in non-small-cell lung cancer pleural effusion than in transudative pleural effusion. Also, pleural-drainage endothelial progenitor cell levels were higher in patients with non-small-cell lung cancer than in patients with benign lung disease undergoing pulmonary resection (P < 0.05). Non-small-cell lung cancer patients with high pleural-drainage endothelial progenitor cell levels had a significantly 4.9 higher rate of cancer recurrence/death than patients with lower pleural-drainage endothelial progenitor cell levels, irrespective of confounders. Endothelial progenitor cells are present in the pleural effusion and are higher in patients with late-stage non-small-cell lung cancer with pleural involvement than in

The Massive CO White Dwarf in the Symbiotic Recurrent Nova RS Ophiuchi

NASA Astrophysics Data System (ADS)

Mikołajewska, Joanna; Shara, Michael M.

2017-10-01

If accreting white dwarfs (WDs) in binary systems are to produce type Ia supernovae (SNe Ia), they must grow to nearly the Chandrasekhar mass and ignite carbon burning. Proving conclusively that a WD has grown substantially since its birth is a challenging task. Slow accretion of hydrogen inevitably leads to the erosion, rather than the growth of WDs. Rapid hydrogen accretion does lead to growth of a helium layer, due to both decreased degeneracy and the inhibition of mixing of the accreted hydrogen with the underlying WD. However, until recently, simulations of helium-accreting WDs all claimed to show the explosive ejection of a helium envelope once it exceeded ˜ {10}-1 {M}⊙ . Because CO WDs cannot be born with masses in excess of ˜ 1.1 {M}⊙ , any such object in excess of ˜ 1.2 {M}⊙ must have grown substantially. We demonstrate that the WD in the symbiotic nova RS Oph is in the mass range 1.2-1.4 M ⊙. We compare UV spectra of RS Oph with those of novae with ONe WDs and with novae erupting on CO WDs. The RS Oph WD is clearly made of CO, demonstrating that it has grown substantially since birth. It is a prime candidate to eventually produce an SN Ia.

Photometric Investigation of Novae T Pyx, BT Mon and V574 Pup at Quiescence by using the 2.4-m Thai National Telescope

NASA Astrophysics Data System (ADS)

Thipboon, Ritthichai; Kaewrakmuk, Metichai; Surina, Farung; Sanguansak, Nuanwan

2017-09-01

Recurrent novae (RNe) are novae with multiple recorded outbursts powered by a thermonuclear runaway. The outburst occurs on the surface of the white dwarf which accompanies with a late type main-sequence or giant secondary star transferring material onto the white dwarf primary star. They resemble classical novae (CNe) outbursts but only RNe has more than one recorded outbursts. RNe play an important role as one of the suspected progenitor systems of Type Ia supernovae (SNe) which are used as primary distance indicators in cosmology. Thus, it is important to investigate the outburst type of CNe and RNe and finally ascertain the population of objects that might ultimately be candidates for Type Ia SNe explosions. The proposal that RNe occupy a region separated from CNe in an outburst amplitude versus speed class diagram was adopted. Since the low amplitude results from the existence of an evolved secondary and/or high mass transfer rate in the quiescent system, RNe candidates should accordingly have low amplitude. We selected 3 preliminary targets including T Pyx, BT Mon and V574 Pup. Their amplitudes are not that low but the lowest amplitude that can be observed with Thai National Telescope (TNT). We obtained their magnitudes at quiescence using ULTRASPEC camera on the 2.4-m TNT. The positions of three targets on optical and near-infrared color-magnitude diagrams suggest that all three should have main-sequence secondary stars. This is true for T Pyx, whose secondary star has been confirmed its spectroscopy to be a main-sequence star, but not yet confirmed for BT Mon and V574 Pup.

AT Cnc: A SECOND DWARF NOVA WITH A CLASSICAL NOVA SHELL

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shara, Michael M.; Mizusawa, Trisha; Zurek, David

2012-10-20

We are systematically surveying all known and suspected Z Cam-type dwarf novae for classical nova shells. This survey is motivated by the discovery of the largest known classical nova shell, which surrounds the archetypal dwarf nova Z Camelopardalis. The Z Cam shell demonstrates that at least some dwarf novae must have undergone classical nova eruptions in the past, and that at least some classical novae become dwarf novae long after their nova thermonuclear outbursts, in accord with the hibernation scenario of cataclysmic binaries. Here we report the detection of a fragmented 'shell', 3 arcmin in diameter, surrounding the dwarf novamore » AT Cancri. This second discovery demonstrates that nova shells surrounding Z Cam-type dwarf novae cannot be very rare. The shell geometry is suggestive of bipolar, conical ejection seen nearly pole-on. A spectrum of the brightest AT Cnc shell knot is similar to that of the ejecta of the classical nova GK Per, and of Z Cam, dominated by [N II] emission. Galaxy Evolution Explorer FUV imagery reveals a similar-sized, FUV-emitting shell. We determine a distance of 460 pc to AT Cnc, and an upper limit to its ejecta mass of {approx}5 Multiplication-Sign 10{sup -5} M {sub Sun }, typical of classical novae.« less

Nova Delphini 2013: Backyard Analysis of a Classical Nova

NASA Astrophysics Data System (ADS)

Reid, Piper

2014-01-01

On August 14, 2013, Nova Delphini was discovered by Koichi Itagaki. This nova erupted to a maximum brightness of magnitude 4.4 by August 16, 2013. The extraordinary brightness of this event has allowed many amateur astronomers to have the chance to study it. More than 750 amateur astronomers have contributed to the AAVSO photometry database of Nova Delphini.1 The amount and quality of spectroscopic data gathered is unprecedented as well, as over 700 individual spectra have been collected so far in the ARAS database.2 A nova is a class of variable star that undergoes a cataclysmic eruption, which can be observed through a sudden increase in brightness that declines over a series of months or years. At the center of a nova is an accreting white dwarf star which is collecting hydrogen from its surroundings. The accreting mass causes a nuclear reaction on the surface of the white dwarf and as the pressure increases the reaction becomes super-critical and a thermonuclear runaway is ignited causing the brightness increase as well as triggering the ejection of a shell of material form the star. The stages of a classical nova outburst are outlined along with techniques available to amateur astronomers for study of these phenomena. The author’s equipment and software setup are detailed. Results obtained using a low resolution grating, Schmidt-cassegrain telescope and CCD camera that were acquired while Nova Delphini was in the “fireball stage” 3 and subsequent “iron curtain phase”3 are compared and discussed. Results obtained using a high resolution spectroscope, Schmidt-cassegrain telescope and CCD camera that were acquired during the “lifting of the iron curtain phase”3 are also presented. References 1. Turner, Rebecca. “AAVSO - Nova Del 2013” 20 Aug 2013 Web. 8 Sep 2013 nova-del-2013> 2. Tessier, Francois. “ARAS Spectral Database - Nova-Del-2013” 22 Sep 2013 Web. 22 Sep 2013 Novae/Nova

A Model for the Quiescent Phase of the Recurrent Nova U Scorpii.

PubMed

Hachisu; Kato; Kato; Matsumoto; Nomoto

2000-05-10

A theoretical light curve is constructed for the quiescent phase of the recurrent nova U Scorpii in order to resolve the existing distance discrepancy between the outbursts (d approximately 6 kpc) and the quiescences (d approximately 14 kpc). Our U Sco model consists of a very massive white dwarf (WD), an accretion disk (ACDK) with a flaring-up rim, and a lobe-filling, slightly evolved, main-sequence star (MS). The model properly includes an accretion luminosity of the WD, a viscous luminosity of the ACDK, and a reflection effect of the MS and the ACDK irradiated by the WD photosphere. The B light curve is well reproduced by a model of 1.37 M middle dot in circle WD + 1.5 M middle dot in circle MS (0.8-2.0 M middle dot in circle MS is acceptable) with an ACDK having a flaring-up rim and the inclination angle of the orbit i approximately 80&j0;. The calculated color is rather blue (B-V approximately 0.0) for a suggested mass accretion rate of 2.5x10-7 M middle dot in circle yr-1, thus indicating a large color excess of E(B-V) approximately 0.56 with the observational color of B-V=0.56 in quiescence. Such a large color excess corresponds to an absorption of AV approximately 1.8 and AB approximately 2.3, which reduces the distance to 6-8 kpc. This is in good agreement with the distance estimation of 4-6 kpc for the latest outburst. Such a large intrinsic absorption is very consistent with the recently detected period change of U Sco, which is indicating a mass outflow of approximately 3x10-7 M middle dot in circle yr-1 through the outer Lagrangian points in quiescence.

Cecilia Payne-Gaposchkin, Henry Norris Russell Lecture: Fifty Years of Novae

NASA Astrophysics Data System (ADS)

Burbidge, E. M.

1999-05-01

It is easy to pick out my most memorable meeting of the AAS: the 149th meeting held in January, 1977, and hosted by the University of Hawaii, in Honolulu, HI. It was the meeting at which two traditions of the Society were broken, and we moved into the era of equal opportunity for women astronomers. Cecilia Payne-Gaposchkin received the highest award of the AAS: the Henry Norris Russell Lectureship. This award had never before been available to women, otherwise Cecilia would, years earlier, have been honored for the many achievements in her lifetime of renowned astronomical research. And I, the first woman to be elected President of the AAS, had the honor of presenting the illuminated scroll to Cecilia, and of introducing her on the platform where she delivered the Henry Norris Russell Prize Lecture, entitled ``Fifty Years of Novae"(1) . Cecilia opened by comparing the experience of young and old scientists in achieving exciting results from their research, and then led us through the history of the discoveries of and about some famous novae. She described the physical picture that emerged from studies of their light curves, their spectra, and the discovery of their binary nature. Three important tables were included, listing data on cataclysmic binaries (dwarf novae) and their link to the nova phenomenon in general. She recalled that she and Sergei Gaposchkin had hesitated between the names catastrophic and cataclysmic for the dwarf novae, and decided on the latter, from the dictionary definitions of those two terms: ``a cataclysm is a great and general flood" while a catastrophe ``is a final event". The nova phenomenon is recurrent, as are the dwarf novae, and both involve an outpouring of a flood of energy. She concluded by describing her 50 years' experience with novae as presenting ``the contemporary portrait of a nova", rather than a final picture, and by forecasting that the next 50 years of discovering and studying novae will be as full of surprises as the

Boron neutron capture therapy induces cell cycle arrest and cell apoptosis of glioma stem/progenitor cells in vitro.

PubMed

Sun, Ting; Zhang, Zizhu; Li, Bin; Chen, Guilin; Xie, Xueshun; Wei, Yongxin; Wu, Jie; Zhou, Youxin; Du, Ziwei

2013-08-06

Glioma stem cells in the quiescent state are resistant to clinical radiation therapy. An almost inevitable glioma recurrence is due to the persistence of these cells. The high linear energy transfer associated with boron neutron capture therapy (BNCT) could kill quiescent and proliferative cells. The present study aimed to evaluate the effects of BNCT on glioma stem/progenitor cells in vitro. The damage induced by BNCT was assessed using cell cycle progression, apoptotic cell ratio and apoptosis-associated proteins expression. The surviving fraction and cell viability of glioma stem/progenitor cells were decreased compared with differentiated glioma cells using the same boronophenylalanine pretreatment and the same dose of neutron flux. BNCT induced cell cycle arrest in the G2/M phase and cell apoptosis via the mitochondrial pathway, with changes in the expression of associated proteins. Glioma stem/progenitor cells, which are resistant to current clinical radiotherapy, could be effectively killed by BNCT in vitro via cell cycle arrest and apoptosis using a prolonged neutron irradiation, although radiosensitivity of glioma stem/progenitor cells was decreased compared with differentiated glioma cells when using the same dose of thermal neutron exposure and boronophenylalanine pretreatment. Thus, BNCT could offer an appreciable therapeutic advantage to prevent tumor recurrence, and may become a promising treatment in recurrent glioma.

THE CHANGE OF THE ORBITAL PERIODS ACROSS ERUPTIONS AND THE EJECTED MASS FOR RECURRENT NOVAE CI AQUILAE AND U SCORPII

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schaefer, Bradley E.

2011-12-01

I report on the cumulative results from a program started 24 years ago designed to measure the orbital period change of recurrent novae (RNe) across an eruption. The goal is to use the orbital period change to measure the mass ejected during each eruption as the key part of trying to measure whether the RNe white dwarfs are gaining or losing mass over an entire eruption cycle, and hence whether they can be progenitors for Type Ia supernovae. This program has now been completed for two eclipsing RNe: CI Aquilae (CI Aql) across its eruption in 2000 and U Scorpiimore » (U Sco) across its eruption in 1999. For CI Aql, I present 78 eclipse times from 1991 to 2009 (including four during the tail of the 2000 eruption) plus two eclipses from 1926 and 1935. For U Sco, I present 67 eclipse times, including 46 times during quiescence from 1989 to 2009, plus 21 eclipse times in the tails of the 1945, 1999, and 2010 eruptions. The eclipse times during the tails of eruptions are systematically and substantially shifted with respect to the ephemerides from the eclipses in quiescence, with this being caused by shifts of the center of light during the eruption. These eclipse times are plotted on an O - C diagram and fitted to models with a steady period change ( P-dot ) between eruptions (caused by, for example, conservative mass transfer) plus an abrupt period change ({Delta}P) at the time of eruption. The primary uncertainty arises from the correlation between {Delta}P with P-dot , such that a more negative P-dot makes for a more positive {Delta}P. For CI Aql, the best fit is {Delta}P = -3.7{sup +9.2}{sub -7.3} Multiplication-Sign 10{sup -7}. For U Sco, the best fit is {Delta}P = (+ 43 {+-} 69) Multiplication-Sign 10{sup -7} days. These period changes can directly give a dynamical measure of the mass ejected (M{sub ejecta}) during each eruption with negligible sensitivity to the stellar masses and no uncertainty from distances. For CI Aql, the 1{sigma} upper limit is M

Typical examples of classical novae

NASA Technical Reports Server (NTRS)

Hack, Margherita; Selvelli, Pierluigi; Bianchini, Antonio; Duerbeck, Hilmar W.

1993-01-01

Because of the very complicated individualistic behavior of each nova, we think it necessary to review the observations of a few well-observed individuals. We have selected a few objects of different speed classes, which have been extensively observed. They are: V1500 Cygni 1975, a very fast nova; V603 Aql 1918, fast nova; CP Pup 1942, fast nova; GK Per 1901, fast nova; V 1668 Cyg 1979, moderately fast nova; FH Ser 1970, slow nova; DQ Her 1934, slow nova; T Aur 1891, slow nova; RR Pic 1925, slow nova; and HR Del 1967, very slow nova.

Typical examples of classical novae

NASA Astrophysics Data System (ADS)

Hack, Margherita; Selvelli, Pierluigi; Bianchini, Antonio; Duerbeck, Hilmar W.

1993-09-01

Because of the very complicated individualistic behavior of each nova, we think it necessary to review the observations of a few well-observed individuals. We have selected a few objects of different speed classes, which have been extensively observed. They are: V1500 Cygni 1975, a very fast nova; V603 Aql 1918, fast nova; CP Pup 1942, fast nova; GK Per 1901, fast nova; V 1668 Cyg 1979, moderately fast nova; FH Ser 1970, slow nova; DQ Her 1934, slow nova; T Aur 1891, slow nova; RR Pic 1925, slow nova; and HR Del 1967, very slow nova.

Boron neutron capture therapy induces cell cycle arrest and cell apoptosis of glioma stem/progenitor cells in vitro

PubMed Central

2013-01-01

Background Glioma stem cells in the quiescent state are resistant to clinical radiation therapy. An almost inevitable glioma recurrence is due to the persistence of these cells. The high linear energy transfer associated with boron neutron capture therapy (BNCT) could kill quiescent and proliferative cells. Methods The present study aimed to evaluate the effects of BNCT on glioma stem/progenitor cells in vitro. The damage induced by BNCT was assessed using cell cycle progression, apoptotic cell ratio and apoptosis-associated proteins expression. Results The surviving fraction and cell viability of glioma stem/progenitor cells were decreased compared with differentiated glioma cells using the same boronophenylalanine pretreatment and the same dose of neutron flux. BNCT induced cell cycle arrest in the G2/M phase and cell apoptosis via the mitochondrial pathway, with changes in the expression of associated proteins. Conclusions Glioma stem/progenitor cells, which are resistant to current clinical radiotherapy, could be effectively killed by BNCT in vitro via cell cycle arrest and apoptosis using a prolonged neutron irradiation, although radiosensitivity of glioma stem/progenitor cells was decreased compared with differentiated glioma cells when using the same dose of thermal neutron exposure and boronophenylalanine pretreatment. Thus, BNCT could offer an appreciable therapeutic advantage to prevent tumor recurrence, and may become a promising treatment in recurrent glioma. PMID:23915425

Novae as distance indicators

NASA Technical Reports Server (NTRS)

Ford, Holland C.; Ciardullo, Robin

1988-01-01

Nova shells are characteristically prolate with equatorial bands and polar caps. Failure to account for the geometry can lead to large errors in expansion parallaxes for individual novae. When simple prescriptions are used for deriving expansion parallaxes from an ensemble of randomly oriented prolate spheroids, the average distance will be too small by factors of 10 to 15 percent. The absolute magnitudes of the novae will be underestimated and the resulting distance scale will be too small by the same factors. If observations of partially resolved nova shells select for large inclinations, the systematic error in the resulting distance scale could easily be 20 to 30 percent. Extinction by dust in the bulge of M31 may broaden and shift the intrinsic distribution of maximum nova magnitudes versus decay rates. We investigated this possibility by projecting Arp's and Rosino's novae onto a composite B - 6200A color map of M31's bulge. Thirty two of the 86 novae projected onto a smooth background with no underlying structure due to the presence of a dust cloud along the line of sight. The distribution of maximum magnitudes versus fade rates for these unreddened novae is indistinguishable from the distribution for the entire set of novae. It is concluded that novae suffer very little extinction from the filamentary and patchy distribution of dust seen in the bulge of M31. Time average B and H alpha nova luminosity functions are potentially powerful new ways to use novae as standard candles. Modern CCD observations and the photographic light curves of M31 novae found during the last 60 years were analyzed to show that these functions are power laws. Consequently, unless the eruption times for novae are known, the data cannot be used to obtain distances.

Nova Sco 2011 No. 2 = PNV J16364440-4132340 = PNV J16364300-4132460

NASA Astrophysics Data System (ADS)

Waagen, Elizabeth O.

2011-09-01

Announcement of discovery of Nova Sco 2011 No. 2 = PNV J16364440-4132340 = PNV J16364300-4132460. Discovered independently by John Seach (Chatsworth Island, NSW, Australia, on 2011 Sep. 06.37 UT at mag=9.8 (DSLR)) and by Yuji Nakamura (Kameyama, Mie, Japan, on 2011 Sep. 06.4313 UT at mag=9.7 C (CCD)). Posted on the IAU Central Bureau for Astronomical Telegrams Transient Object Confirmation Page (TOCP) as PNV J16364440-4132340 (Nakamura) and PNV J16364300-4132460 (Seach); identifications consolidated in VSX under PNV J16364440-4132340. Spectra obtained by A. Arai et al. on 2011 Sep. 7.42 UT suggest a highly reddened Fe II-type classical nova. Spectra by F. Walter and J. Seron obtained Sep. 2011 8.091 UT confirm a young galactic nova; they report spectra are reminiscent of an early recurrent nova. Initially announced in AAVSO Special Notice #251 (Matthew Templeton) and IAU Central Bureau Electronic Telegram 2813 (Daniel W. E. Green, ed.). Finder charts with sequence may be created using the AAVSO Variable Star Plotter (http://www.aavso.org/vsp). Observations should be submitted to the AAVSO International Database. See full Alert Notice for more details and observations.

Nova-like variables

NASA Technical Reports Server (NTRS)

Ladous, Constanze

1993-01-01

On grounds of different observable characteristics five classes of nova-like objects are distinguished: the UX Ursae Majoris stars, the antidwarf novae, the DQ Herculis stars, the AM Herculis stars, and the AM Canum Venaticorum stars. Some objects have not been classified specifically. Nova-like stars share most observable features with dwarf novae, except for the outburst behavior. The understanding is that dwarf novae, UX Ursae Majoris stars, and anti-dwarf novae are basically the same sort of objects. The difference between them is that in UX Ursae Majoris stars the mass transfer through the accretion disc always is high so the disc is stationary all the time; in anti-dwarf novae for some reason the mass transfer occasionally drops considerably for some time, and in dwarf novae it is low enough for the disc to undergo semiperiodic changes between high and low accretion events. DQ Herculis stars are believed to possess weakly magnetic white dwarfs which disrupt the inner disc at some distance from the central star; the rotation of the white dwarf can be seen as an additional photometric period. In AM Herculis stars, a strongly magnetic white dwarf entirely prevents the formation of an accretion disk and at the same time locks the rotation of the white dwarf to the binary orbit. Finally, AM Canum Venaticorum stars are believed to be cataclysmic variables that consist of two white dwarf components.

Nova V2214 Ophiuchi 1988 - A magnetic nova inside the period gap

NASA Technical Reports Server (NTRS)

Baptista, R.; Jablonski, F. J.; Cieslinski, D.; Steiner, J. E.

1993-01-01

The discovery of a coherent photometric modulation in Nova Oph 1988 with period 0.117515 +/- 0.000002 d, which is associated with the orbital period of the underlying binary, is reported. On the basis of photometric observations, it is concluded that Nova V2214 Oph 1988 is a magnetic nova with an orbital period inside the period gap. The inclusion of this system in the statistics of novae suggests that there is no period gap for novae and that there is a clear correlation between the occurrence of novae with short orbital periods and the presence of magnetic white dwarfs. It is suggested that funneling of the accretion flow onto the magnetic poles favors the conditions for a thermonuclear runaway, increasing the frequency of eruptions for magnetic systems.

V1369 Cen High-resolution Panchromatic Late Nebular Spectra in the Context of a Unified Picture for Nova Ejecta

NASA Astrophysics Data System (ADS)

Mason, Elena; Shore, Steven N.; De Gennaro Aquino, Ivan; Izzo, Luca; Page, Kim; Schwarz, Greg J.

2018-01-01

Nova Cen 2013 (V1369 Cen) is the fourth bright nova observed panchromatically through high-resolution UV+optical multiepoch spectroscopy. It is also the nova with the richest set of spectra (in terms of both data quality and number of epochs) thanks to its exceptional brightness. Here, we use the late nebular spectra taken between day ∼250 and day ∼837 after outburst to derive the physical, geometrical, and kinematical properties of the nova. We compare the results with those determined for the other panchromatic studies in this series: T Pyx, V339 Del (nova Del 2013), and V959 Mon (nova Mon 2012). From this we conclude that in all these novae the ejecta geometry and phenomenology can be consistently explained by clumpy gas expelled during a single, brief ejection episode and in ballistic expansion, and not by a wind. For V1369 Cen the ejecta mass (∼1 × 10‑4 M⊙) and filling factor (0.1 ≤ f ≤ 0.2) are consistent with those of classical novae but larger (by at least an order of magnitude) than those of T Pyx and the recurrent novae. V1369 Cen has an anomalously high (relative to solar) N/C ratio that is beyond the range currently predicted for a CO nova, and the Ne emission line strengths are dissimilar to those of typical ONe or CO white dwarfs.

When does an old nova become a dwarf nova? Kinematics and age of the nova shell of the dwarf nova AT Cancri

NASA Astrophysics Data System (ADS)

Shara, Michael M.; Drissen, Laurent; Martin, Thomas; Alarie, Alexandre; Stephenson, F. Richard

2017-02-01

The Z Cam-type dwarf nova AT Cancri (AT Cnc) displays a classical nova (CN) shell, demonstrating that mass transfer in cataclysmic binaries decreases substantially after a CN eruption. The hibernation scenario of cataclysmic binaries predicts such a decrease, on a time-scale of a few centuries. In order to measure the time since AT Cnc's last CN eruption, we have measured the radial velocities of a hundred clumps in its ejecta with SITELLE, Canada-France-Hawaii Telescope's recently commissioned imaging Fourier transform spectrometer. These range from -455 to +490 km s-1. Coupled with the known distance to AT Cnc of 460 pc, the size of AT Cnc's shell, and a simple model of nova ejecta deceleration, we determine that the last CN eruption of this system occurred 330_{-90}^{+135} yr ago. This is the most rapid transition from a high mass-transfer rate, nova-like variable to a low mass-transfer rate, dwarf nova yet measured, and in accord with the hibernation scenario of cataclysmic binaries. We conclude by noting the similarity in the deduced outburst date (within a century of 1686 CE) of AT Cnc to a `guest star' reported in the constellation Cancer by Korean observers in 1645 CE.

The Galactic Nova Rate Revisited

NASA Astrophysics Data System (ADS)

Shafter, A. W.

2017-01-01

Despite its fundamental importance, a reliable estimate of the Galactic nova rate has remained elusive. Here, the overall Galactic nova rate is estimated by extrapolating the observed rate for novae reaching m≤slant 2 to include the entire Galaxy using a two component disk plus bulge model for the distribution of stars in the Milky Way. The present analysis improves on previous work by considering important corrections for incompleteness in the observed rate of bright novae and by employing a Monte Carlo analysis to better estimate the uncertainty in the derived nova rates. Several models are considered to account for differences in the assumed properties of bulge and disk nova populations and in the absolute magnitude distribution. The simplest models, which assume uniform properties between bulge and disk novae, predict Galactic nova rates of ˜50 to in excess of 100 per year, depending on the assumed incompleteness at bright magnitudes. Models where the disk novae are assumed to be more luminous than bulge novae are explored, and predict nova rates up to 30% lower, in the range of ˜35 to ˜75 per year. An average of the most plausible models yields a rate of {50}-23+31 yr-1, which is arguably the best estimate currently available for the nova rate in the Galaxy. Virtually all models produce rates that represent significant increases over recent estimates, and bring the Galactic nova rate into better agreement with that expected based on comparison with the latest results from extragalactic surveys.

A statistical analysis of IUE spectra of dwarf novae and nova-like stars

NASA Technical Reports Server (NTRS)

Ladous, Constanze

1990-01-01

First results of a statistical analysis of the IUE International Ultraviolet Explorer archive on dwarf novae and nova like stars are presented. The archive contains approximately 2000 low resolution spectra of somewhat over 100 dwarf novae and nova like stars. Many of these were looked at individually, but so far the collective information content of this set of data has not been explored. The first results of work are reported.

Gamma Rays from Classical Novae

NASA Technical Reports Server (NTRS)

1997-01-01

NASA at the University of Chicago, provided support for a program of theoretical research into the nature of the thermonuclear outbursts of the classical novae and their implications for gamma ray astronomy. In particular, problems which have been addressed include the role of convection in the earliest stages of nova runaway, the influence of opacity on the characteristics of novae, and the nucleosynthesis expected to accompany nova outbursts on massive Oxygen-Neon-Magnesium (ONeMg) white dwarfs. In the following report, I will identify several critical projects on which considerable progress has been achieved and provide brief summaries of the results obtained:(1) two dimensional simulation of nova runaway; (2) nucleosynthesis of nova modeling; and (3) a quasi-analytic study of nucleosynthesis in ONeMg novae.

Hydrodynamic Simulations of Classical Novae: Accretion onto CO White Dwarfs as SN Ia Progenitors

NASA Astrophysics Data System (ADS)

Starrfield, Sumner; Bose, Maitrayee; Iliadis, Christian; Hix, William R.; José, Jordi; Hernanz, Margarita

2017-06-01

We have continued our studies of accretion onto white dwarfs by following the evolution of thermonuclear runaways on Carbon Oxygen (CO) white dwarfs. We have varied the mass of the white dwarf and the composition of the accreted material but chosen to keep the mass accretion rate at 2 x 10^{-10} solar masses per year to obtain the largest amount of accreted material possible with rates near to those observed. We assume either 25% core material or 50% core material has been mixed into the accreting material prior to the explosion. We use our 1D, lagrangian, hydrodynamic code: NOVA. We will report on the results of these simulations and compare the ejecta abundances to those measured in pre-solar grains that are thought to arise from classical nova explosions. These results will also be compared to recent results with SHIVA (Jose and Hernanz). We find that in all cases and for all white dwarf masses that less mass is ejected than accreted and, therefore, the white dwarf is growing in mass as a result of the accretion and resulting explosion.This work was supported in part by NASA under the Astrophysics Theory Program grant 14-ATP14-0007 and the U.S. DOE under Contract No. DE-FG02- 97ER41041. SS acknowledges partial support from NASA, NSF, and HST grants to ASU and WRH is supported by the U.S. Department of Energy, Office of Nuclear Physics. The results reported herein benefitted from collaborations and/or information exchange within NASA’s Nexus for Exoplanet System Science (NExSS) research coordination network sponsored by NASA’s Science Mission Directorate.

A luminous, blue progenitor system for the type Iax supernova 2012Z

NASA Astrophysics Data System (ADS)

McCully, Curtis; Jha, Saurabh W.; Foley, Ryan J.; Bildsten, Lars; Fong, Wen-Fai; Kirshner, Robert P.; Marion, G. H.; Riess, Adam G.; Stritzinger, Maximilian D.

2014-08-01

Type Iax supernovae are stellar explosions that are spectroscopically similar to some type Ia supernovae at the time of maximum light emission, except with lower ejecta velocities. They are also distinguished by lower luminosities. At late times, their spectroscopic properties diverge from those of other supernovae, but their composition (dominated by iron-group and intermediate-mass elements) suggests a physical connection to normal type Ia supernovae. Supernovae of type Iax are not rare; they occur at a rate between 5 and 30 per cent of the normal type Ia rate. The leading models for type Iax supernovae are thermonuclear explosions of accreting carbon-oxygen white dwarfs that do not completely unbind the star, implying that they are `less successful' versions of normal type Ia supernovae, where complete stellar disruption is observed. Here we report the detection of the luminous, blue progenitor system of the type Iax SN 2012Z in deep pre-explosion imaging. The progenitor system's luminosity, colours, environment and similarity to the progenitor of the Galactic helium nova V445 Puppis suggest that SN 2012Z was the explosion of a white dwarf accreting material from a helium-star companion. Observations over the next few years, after SN 2012Z has faded, will either confirm this hypothesis or perhaps show that this supernova was actually the explosive death of a massive star.

A luminous, blue progenitor system for the type Iax supernova 2012Z.

PubMed

McCully, Curtis; Jha, Saurabh W; Foley, Ryan J; Bildsten, Lars; Fong, Wen-fai; Kirshner, Robert P; Marion, G H; Riess, Adam G; Stritzinger, Maximilian D

2014-08-07

Type Iax supernovae are stellar explosions that are spectroscopically similar to some type Ia supernovae at the time of maximum light emission, except with lower ejecta velocities. They are also distinguished by lower luminosities. At late times, their spectroscopic properties diverge from those of other supernovae, but their composition (dominated by iron-group and intermediate-mass elements) suggests a physical connection to normal type Ia supernovae. Supernovae of type Iax are not rare; they occur at a rate between 5 and 30 per cent of the normal type Ia rate. The leading models for type Iax supernovae are thermonuclear explosions of accreting carbon-oxygen white dwarfs that do not completely unbind the star, implying that they are 'less successful' versions of normal type Ia supernovae, where complete stellar disruption is observed. Here we report the detection of the luminous, blue progenitor system of the type Iax SN 2012Z in deep pre-explosion imaging. The progenitor system's luminosity, colours, environment and similarity to the progenitor of the Galactic helium nova V445 Puppis suggest that SN 2012Z was the explosion of a white dwarf accreting material from a helium-star companion. Observations over the next few years, after SN 2012Z has faded, will either confirm this hypothesis or perhaps show that this supernova was actually the explosive death of a massive star.

The Spectroscopic Evolution of the Symbiotic-like Recurrent Nova V407 Cygni During Its 2010 Outburst. 2. The Circumstellar Environment and the Aftermath

NASA Technical Reports Server (NTRS)

Shore, S. N.; Wahlgren, G. M.; Augusteijn, T.; Liimets, T.; Koubsky, P.; Slechta, M.; Votruba, V.

2011-01-01

The nova outburst of V407 Cyg in 2010 Mar. 10 was the first observed for this star but its close resemblance to the well known symbiotic-like recurrent nova RS Oph suggests that it is also a member of this rare type of Galactic novae. The nova was the first detected at gamma-ray energies and is the first known nova explosion for this system. The extensive multiwavelength coverage of this outburst makes it an ideal comparison with the few other outbursts known for similar systems. We extend our previous analysis of the Mira and the expanding shock from the explosion to detail the time development of the photoionized Mira wind, circumstellar medium, and shocked circumstellar environment to derive their physical parameters and how they relate to large scale structure of the environment, extending the previous coverage to more than 500 days after outburst. We use optical spectra obtained at high resolution with the Nordic Optical Telescope (NOT) (R approx. =.45000 to 65000) and medium resolution Ondrejov Observatory (R approx. = 12000) data and compare the line variations with publicly available archival measurements at 30 GHz OVNR and at X-rays with Swift during the first four months of the outburst, through the end of the epoch of strong XR emission. We use nebular diagnostics and high resolution profile variations to derive the densities and locations of the extended emission. We find that the higher the ionization and/or the higher the excitation energy, the more closely the profiles resemble the He II/Ca V-type high velocity shock profile discussed in Paper I. This also accounts for the comparative development of the [N II] and [O III] isoelectronic transitions: the [O III] 4363A profile does not show the low velocity peaks while the excited [N II] 5754A does. If nitrogen is mainly N(+3) or higher in the shock, the upper state of the [N II] nebular lines will contribute but if the oxygen is O(+2) then this line is formed by recombination, masking the nebular

The spectroscopic evolution of novae in the bulge of M31 and a search for their possible origin in the M31 globular cluster system

NASA Astrophysics Data System (ADS)

Tomaney, Austin Bede

Results are presented from a three year (1987 to 1989) spectroscopic and photometric survey of novae in M3l's bulge, the first comprehensive study of novae outside the Galactic and Magellanic Cloud systems. Nine novae were detected and monitored and their spectra cover a range of outburst states from early decline to the early nebular phases. Broad agreement in spectral morphology and evolution is found with Galactic novae. Since Galactic novae are mainly disk objects, this indicates that novae outburst properties are not critically dependent on the metallicity of the progenitor population. However, in this sample, and in a sample of four M31 nova spectra taken in 1983, no fast, violent outbursts frequently associated with nova systems containing ONeMg white dwarfs were found, suggestive of a systematic difference between the observed proportion of such outbursts between Galactic and M31 bulge novae. Three novae in the sample were observed on succeeding nights during the transition phase of their evolution. Extraordinary variations in some nightly line strengths, particularly the N III lines, were discovered. It is argued that this variability reflects the deposition of drag energy by the secondary star during the common envelope phase of nova evolution and is indicative of a key phase in mass loss from nova systems. Observations include the spectroscopic coverage of an extremely slow nova from 1987 to l990, during the object's evolution in the nebula phase. This provided a unique opportunity to make the first detailed comparison of the evolution and properties of an extra galactic nova with those in our own Galaxy. The roughly solar abundances obtained are typical of similar slow Galactic novae. Further observations are also presented of a unique outburst in 1988 that was independently discovered and reported by Rich et al. These data confirm the inferences of other observers that the outburst differed markedly from that of a typical classical nova. Finally an

CI Aql monitoring needed to support HST observations

NASA Astrophysics Data System (ADS)

Waagen, Elizabeth O.

2016-10-01

Dr. Edward Sion (Villanova University) has requested AAVSO observers' assistance in monitoring the recurrent nova CI Aql in support of observations with the Hubble Space Telescope Cosmic Origins Spectrograph scheduled for October 31 - November 2, 2016, and November 3 - November 5, 2016. These observations are part of a study on short orbital period recurrent novae as Supernovae Type Ia progenitors. It is essential to know 24 hours prior to the HST COS observations that CI Aql is not in outburst, in order to protect the instrumentation. Observers are asked to keep an eye on CI Aql with nightly snapshot images (V preferred) from now until November 12, and to report their observations promptly. It will be especially important to know the brightness of CI Aql each night for October 28 through November 7 UT. Visual observations are welcome. CI Aql (Nova Aql 1917) has had recurrent outbursts in 1941 and 2000, brightening to V 8.5. At minimum it is V 16-16.5 or fainter. Finder charts with sequence may be created using the AAVSO Variable Star Plotter (https://www.aavso.org/vsp). Observations should be submitted to the AAVSO International Database. See full Alert Notice for more details.

High-resolution Interferometric Observations of Nova RS Ophiuchi and a Proposed Unification Model for Persistent Dust Creation in Recurrent Novae

NASA Astrophysics Data System (ADS)

Barry, R. K.; Danchi, W. C.

2008-12-01

We review observations of nova RS Ophiuchi using long-baseline near-infrared and mid-infrared interferometry at three observatories: the Keck Interferometer in the Nulling mode (KIN), the Palomar Testbed Interferometer (PTI), and the Infrared and Optical Telescope Array (IOTA). We discuss these observations in the context of a unifying model of the system that includes an increase in density in the plane of the orbit of the two stars created by a spiral shock wave caused by the motion of the stars through the cool wind of the red giant star. We discuss how recent observations using the Spitzer Space Telescope and the VLTI support this proposed model.

An extensive optical study of V2491 Cyg (Nova Cyg 2008 N.2), from maximum brightness to return to quiescence

NASA Astrophysics Data System (ADS)

Munari, U.; Siviero, A.; Dallaporta, S.; Cherini, G.; Valisa, P.; Tomasella, L.

2011-04-01

The photometric and spectroscopic evolution of the He/N and very fast Nova Cyg 2008 N.2 (V2491 Cyg) is studied in detail. A primary maximum was reached at V = 7.45 ± 0.05 on April 11.37 (±0.1) 2008 UT, followed by a smooth decline characterized by t2V=4.8 days, and then a second maximum was attained at V = 9.49 ± 0.03, 14.5 days after the primary one. This is the only third nova to have displayed a secondary maximum, after V2362 Cyg and V1493 Aql. The development and energetics of the secondary maximum is studied in detail. The smooth decline that followed was accurately monitored until day +144 when the nova was 8.6 mag fainter than maximum brightness, well into its nebular phase, with its line and continuum emissivity declining as t-3. The reddening affecting the nova was EB- V = 0.23 ± 0.01, and the distance of 14 kpc places the nova at a height above the galactic plane of 1.1 kpc, larger than typical for He/N novae. The expansion velocity of the bulk of ejecta was 2000 km/s, with complex emission profiles and weak P-Cyg absorptions during the optically thick phase, and saddle-like profiles during the nebular phase. Photo-ionization analysis of the emission line spectrum indicates that the mass ejected by the outburst was 5.3 × 10 -6 M ⊙ and the mass fractions to be X = 0.573, Y = 0.287, Z = 0.140, with those of individual elements being N = 0.074, O = 0.049, Ne = 0.015. The metallicity of the accreted material was [Fe/H] = -0.25, in line with ambient value at the nova galacto-centric distance. Additional spectroscopic and photometric observations at days +477 and +831 show the nova returned to the brightness level of the progenitor and to have resumed the accretion onto the white dwarf.

Nova Discovery Efficiency 1890-2014; Only 43%±6% of the Brightest Nova Are Discovered

NASA Astrophysics Data System (ADS)

Schaefer, Bradley E.

2014-06-01

Galactic nova discovery has always been the domain of the best amateur astronomers, with the only substantial exception being the use of the Harvard plates from 1890-1947. (Modern CCD surveys have not produced any significant nova discoveries.) From 1890-1946, novae were discovered by gentlemen who deeply knew the stars in the sky and who checked for new stars on every clear night. This all changed when war surplus binoculars became commonly available, so the various organizations (e.g., AAVSO, BAA) instructed their hunters to use binoculars to regularly search small areas of the Milky Way. In the 1970s the hunters largely switched to blinking photographs, while they switched to CCD images in the 1990s, all exclusively in Milky Way regions. Currently, most hunters use 'go-to' scopes to look deeply only in the Milky Way, use weekly or monthly cadences, never go outside to look up at the light-polluted skies, and do not have the stars memorized at all. This situation is good for catching many faint novae, but is inefficient for catching the more isotropic and systematically-fast bright novae.I have made an exhaustive analysis of all known novae to isolate the effects on the relative discovery efficiency as a function of decade, the elongation from the Sun, the Moon's phase, the declination, the peak magnitude, and the duration of the peak. For example, the relative efficiency for novae south of declination -33° is 0.5 before 1953, 0.2 from 1953-1990, and 0.8 after 1990. My analysis gives the overall discovery efficiency to be 43%±6%, 30%, 22%, 12%, and 6% for novae peaking brighter than 2, 4, 6, 8, and 10 mag. Thus, the majority of first magnitude novae are being missed. The bright novae are lost because they are too close to the Sun, in the far south, and/or very fast. This is illustrated by the discovery rate for Vpeak<2 novae being once every five years before 1946, yet only one such nova (V1500 Cyg) has been seen in the last 68 years. A critical consequence of

Constraints on the Progenitor System of the Type Ia Supernova 2014J from Pre-Explosion Hubble Space Telescope Imaging

NASA Technical Reports Server (NTRS)

Kelly, Patrick L.; Fox, Ori D.; Filippenko, Alexei V.; Cenko, S. Bradley; Prato, Lisa; Schaefer, Gail; Shen, Ken J.; Zheng, WeiKang; Graham, Melissa L.; Tucker, Brad E.

2014-01-01

We constrain the properties of the progenitor system of the highly reddened Type Ia supernova (SN Ia) 2014J in Messier 82 (M82; d (is) approx. 3.5 Mpc). We determine the supernova (SN) location using Keck-II K-band adaptive optics images, and we find no evidence for flux from a progenitor system in pre-explosion near-ultraviolet through near-infrared Hubble Space Telescope (HST) images. Our upper limits exclude systems having a bright red giant companion, including symbiotic novae with luminosities comparable to that of RS Ophiuchi. While the flux constraints are also inconsistent with predictions for comparatively cool He-donor systems (T (is) approximately 35,000 K), we cannot preclude a system similar to V445 Puppis. The progenitor constraints are robust across a wide range of RV and AV values, but significantly greater values than those inferred from the SN light curve and spectrum would yield proportionally brighter luminosity limits. The comparatively faint flux expected from a binary progenitor system consisting of white dwarf stars would not have been detected in the pre-explosion HST imaging. Infrared HST exposures yield more stringent constraints on the luminosities of very cool (T (is) less than 3000 K) companion stars than was possible in the case of SN Ia 2011fe.

Explosive lithium production in the classical nova V339 Del (Nova Delphini 2013).

PubMed

Tajitsu, Akito; Sadakane, Kozo; Naito, Hiroyuki; Arai, Akira; Aoki, Wako

2015-02-19

The origin of lithium (Li) and its production process have long been uncertain. Li could be produced by Big Bang nucleosynthesis, interactions of energetic cosmic rays with interstellar matter, evolved low-mass stars, novae, and supernova explosions. Chemical evolution models and observed stellar Li abundances suggest that at least half the Li may have been produced in red giants, asymptotic giant branch (AGB) stars, and novae. No direct evidence, however, for the supply of Li from evolved stellar objects to the Galactic medium has hitherto been found. Here we report the detection of highly blue-shifted resonance lines of the singly ionized radioactive isotope of beryllium, (7)Be, in the near-ultraviolet spectra of the classical nova V339 Del (Nova Delphini 2013) 38 to 48 days after the explosion. (7)Be decays to form (7)Li within a short time (half-life of 53.22 days). The (7)Be was created during the nova explosion via the alpha-capture reaction (3)He(α,γ)(7)Be (ref. 5). This result supports the theoretical prediction that a significant amount of (7)Li is produced in classical nova explosions.

A XMM-Newton Observation of Nova LMC 1995, a Bright Supersoft X-ray Source

NASA Technical Reports Server (NTRS)

Orio, Marina; Hartmann, Wouter; Still, Martin; Greiner, Jochen

2003-01-01

Nova LMC 1995, previously detected during 1995-1998 with ROSAT, was observed again as a luminous supersoft X-ray source with XMM-Newton in December of 2000. This nova offers the possibility to observe the spectrum of a hot white dwarf, burning hydrogen in a shell and not obscured by a wind or by nebular emission like in other supersoft X-ray sources. Notwithstanding uncertainties in the calibration of the EPIC instruments at energy E<0.5 keV, using atmospheric models in Non Local Thermonuclear Equilibrium we derived an effective temperature in the range 400,000-450,000 K, a bolometric luminosity Lbolabout equal to 2.3 times 10 sup37 erg s sup-l, and we verified that the abundance of carbon is not significantly enhanced in the X-rays emitting shell. The RGS grating spectra do not show emission lines (originated in a nebula or a wind) observed for some other supersoft X-ray sources. The crowded atmospheric absorption lines of the white dwarf cannot be not resolved. There is no hard component (expected from a wind, a surrounding nebula or an accretion disk), with no counts above the background at E>0.6 keV, and an upper limit Fx,hard = 10 sup-14 erg s sup-l cm sup-2 to the X-ray flux above this energy. The background corrected count rate measured by the EPIC instruments was variable on time scales of minutes and hours, but without the flares or sudden obscuration observed for other novae. The power spectrum shows a peak at 5.25 hours, possibly due to a modulation with the orbital period. We also briefly discuss the scenarios in which this nova may become a type Ia supernova progenitor.

NOVA, A BRIEF .....

ERIC Educational Resources Information Center

WHITING, RICHARD; AND OTHERS

NOVA IS AN EXPERIMENTAL, 6-YEAR JUNIOR-SENIOR HIGH SCHOOL. ASPECTS OF THE PROGRAM INCLUDE THE TRIMESTER SYSTEM, THE CONTINUOUS PROGRESS CURRICULUM, TEAM TEACHING, A CLASS SCHEDULE OF FOUR 70-MINUTE PERIODS PER WEEK, THE USE OF DATA-PROCESSING EQUIPMENT, AND MODERN INSTRUCTIONAL AIDS. NOVA IS ORGANIZED CAMPUS-STYLE WITH INDIVIDUAL BUILDINGS DEVOTED…

The NOvA Technical Design Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ayres, D.S.; Drake, G.R.; Goodman, M.C.

Technical Design Report (TDR) describes the preliminary design of the NOvA accelerator upgrades, NOvA detectors, detector halls and detector sites. Compared to the March 2006 and November 2006 NOvA Conceptual Design Reports (CDR), critical value engineering studies have been completed and the alternatives still active in the CDR have been narrowed to achieve a preliminary technical design ready for a Critical Decision 2 review. Many aspects of NOvA described this TDR are complete to a level far beyond a preliminary design. In particular, the access road to the NOvA Far Detector site in Minnesota has an advanced technical design atmore » a level appropriate for a Critical Decision 3a review. Several components of the accelerator upgrade and new neutrino detectors also have advanced technical designs appropriate for a Critical Decision 3a review. Chapter 1 is an Executive Summary with a short description of the NOvA project. Chapter 2 describes how the Fermilab NuMI beam will provide a narrow band beam of neutrinos for NOvA. Chapter 3 gives an updated overview of the scientific basis for the NOvA experiment, focusing on the primary goal to extend the search for {nu}{sub {mu}} {yields} {nu}{sub e} oscillations and measure the sin{sup 2}(2{theta}{sub 13}) parameter. This parameter has not been measured in any previous experiment and NOvA would extend the search by about an order of magnitude beyond the current limit. A secondary goal is to measure the dominant mode oscillation parameters, sin{sup 2}(2{theta}{sub 23}) and {Delta}m{sub 32}{sup 2} to a more precise level than previous experiments. Additional physics goals for NOvA are also discussed. Chapter 4 describes the Scientific Design Criteria which the Fermilab accelerator complex, NOvA detectors and NOvA detector sites must satisfy to meet the physics goals discussed in Chapter 3. Chapter 5 is an overview of the NOvA project. The changes in the design relative to the NOvA CDR are discussed. Chapter 6 summarizes

Fritz Zwicky: Novae Become Supernovae

NASA Astrophysics Data System (ADS)

Koenig, T.

2005-12-01

The Swiss physicist Fritz Zwicky (1898-1974) dabbled in a plethora of disciplines, including astronomy and astrophysics. His dabblings were with vested interest and he has left quite an impact. His first great success was his nova research. In the early 1930s, while supermarkets and Superman were flying, he labelled the distinctly brighter nova Supernova. It had been believed that novae were the collision of two stars, but Zwicky came to recognize supernovae as a phenomenon quite distinct from novae. He and Walter Baade explained supernova by melding astronomy and physics and in this aim they created neutron stars, explained the origin of cosmic rays, initiated the first sky survey, and confirmed that a number of historical novae were indeed supernovae. This was truly an important work in the history of astrophysics.

School Psychology in Nova Scotia

ERIC Educational Resources Information Center

King, Sara; McGonnell, Melissa; Noyes, Amira

2016-01-01

Registration as a psychologist in Nova Scotia can be at the master's or doctoral level; however, the Nova Scotia Board of Examiners in Psychology has announced a move to the doctoral degree as the entry-level to practice. Many school psychologists in Nova Scotia practice at the master's level; therefore, this change could affect school psychology…

Nova Mus 2008 = QY Mus

NASA Astrophysics Data System (ADS)

Templeton, Matthew R.

2008-10-01

Nova Mus 2008 = QY Mus was discovered by William Liller, Vina del Mar, Chile, on 2008 September 28.998 UT at magnitude 8.6 (Tech Pan film + orange filter). The position is RA = 13h 16m 36.44s , Dec = -67d 36m 47.8s (from P. Nelson). This object was announced as a nova in IAU Circular 8990 (Daniel W.E. Green, editor). The nova classification was determined using low-resolution spectra by W. Liller indicating the presence of broad H-alpha lines at least 2300 angstroms wide. Several observers confirmed the nova and provided photometry. The position above was provided by Peter Nelson (Ellinbank, Vic., Aus.), and is averaged from four separate exposures (rms error approx. 0.4 arcseconds). The GCVS team have formally designated Nova Mus 2008 as QY MUS. Observations should be reported to the AAVSO International Database as QY MUS.

The awakening of a classical nova from hibernation.

PubMed

Mróz, Przemek; Udalski, Andrzej; Pietrukowicz, Paweł; Szymański, Michał K; Soszyński, Igor; Wyrzykowski, Łukasz; Poleski, Radosław; Kozłowski, Szymon; Skowron, Jan; Ulaczyk, Krzysztof; Skowron, Dorota; Pawlak, Michał

2016-09-29

Cataclysmic variable stars-novae, dwarf novae, and nova-likes-are close binary systems consisting of a white dwarf star (the primary) that is accreting matter from a low-mass companion star (the secondary). From time to time such systems undergo large-amplitude brightenings. The most spectacular eruptions, with a ten-thousandfold increase in brightness, occur in classical novae and are caused by a thermonuclear runaway on the surface of the white dwarf. Such eruptions are thought to recur on timescales of ten thousand to a million years. In between, the system's properties depend primarily on the mass-transfer rate: if it is lower than a billionth of a solar mass per year, the accretion becomes unstable and the matter is dumped onto the white dwarf during quasi-periodic dwarf nova outbursts. The hibernation hypothesis predicts that nova eruptions strongly affect the mass-transfer rate in the binary, keeping it high for centuries after the event. Subsequently, the mass-transfer rate should significantly decrease for a thousand to a million years, starting the hibernation phase. After that the nova awakes again-with accretion returning to the pre-eruption level and leading to a new nova explosion. The hibernation model predicts cyclical evolution of cataclysmic variables through phases of high and low mass-transfer. The theory gained some support from the discovery of ancient nova shells around the dwarf novae Z Camelopardalis and AT Cancri, but direct evidence for considerable mass-transfer changes prior, during and after nova eruptions has not hitherto been found. Here we report long-term observations of the classical nova V1213 Cen (Nova Centauri 2009) covering its pre- and post-eruption phases and precisely documenting its evolution. Within the six years before the explosion, the system revealed dwarf nova outbursts indicative of a low mass-transfer rate. The post-nova is two orders of magnitude brighter than the pre-nova at minimum light with no trace of dwarf

First optical candidate for a recovered classical nova in a globular cluster - Nova 1938 in M14

NASA Technical Reports Server (NTRS)

Shara, Michael M.; Potter, Michael; Moffat, Anthony F. J.; Hogg, Helen S.; Wehlau, Amelia

1986-01-01

U, B, V, R, and H-alpha CCD frames of the field of the nova which appeared in the globular cluster M14 in 1938 have been compared with the nova discovery images. On the basis of positional coincidence, brightness, and blue color, a candidate nova was identified and its right ascension and declination to within 1 arcsec each. Confirmation of the candidate and detailed study of the quiescent nova will probably require Hubble Space Telescope observations.

INFRARED SPECTROSCOPY OF SYMBIOTIC STARS. IX. D-TYPE SYMBIOTIC NOVAE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hinkle, Kenneth H.; Joyce, Richard R.; Fekel, Francis C.

2013-06-10

Time-series spectra of the near-infrared 1.6 {mu}m region have been obtained for five of the six known D-type symbiotic novae. The spectra map the pulsation kinematics of the Mira component in the Mira-white dwarf binary system and provide the center-of-mass velocity for the Mira. No orbital motion is detected in agreement with previous estimates of orbital periods {approx}>100 yr and semimajor axes {approx}50 AU. The 1-5 {mu}m spectra of the Miras show line weakening during dust obscuration events. This results from scattering and continuum emission by 1000 K dust. In the heavily obscured HM Sge system the 4.6 {mu}m COmore » spectrum formed in 1000 K gas is seen in emission against an optically thick dust continuum. Spectral features that are typically produced in either the cool molecular region or the expanding circumstellar region of late-type stars cannot be detected in the D-symbiotic novae. This is in accord with the colliding wind model for interaction between the white dwarf and Mira. Arguments are presented that the 1000 K gas and dust are not Mira circumstellar material but are in the wind interaction region of the colliding winds. CO is the first molecule detected in this region. We suggest that dust condensing in the intershock region is the origin of the dust obscuration. This model explains variations in the obscuration. Toward the highly obscured Mira in HM Sge the dust zone is estimated to be {approx}0.1 AU thick. The intershock wind interaction zone appears thinnest in the most active systems. Drawing on multiple arguments masses are estimated for the system components. The Miras in most D-symbiotic novae have descended from intermediate mass progenitors. The large amount of mass lost from the Mira combined with the massive white dwarf companion suggests that these systems are supernova candidates. However, timescales and the number of objects make these rare events.« less

A Hubble Space Telescope survey for novae in M87.I. light and color curves, spatial distributions, and the nova rate

DOE PAGES

Shara, Michael M.; Doyle, Trisha F.; Lauer, Tod R.; ...

2016-11-08

The Hubble Space Telescope has imaged the central part of M87 over a 10 week span, leading to the discovery of 32 classical novae (CNe) and nine fainter, likely very slow, and/or symbiotic novae. In this first paper of a series, we present the M87 nova finder charts, and the light and color curves of the novae. We demonstrate that the rise and decline times, and the colors of M87 novae are uncorrelated with each other and with position in the galaxy. The spatial distribution of the M87 novae follows the light of the galaxy, suggesting that novae accreted by M87 during cannibalistic episodes are well-mixed. Conservatively using only the 32 brightest CNe we derive a nova rate for M87:more » $${363}_{-45}^{+33}$$ novae yr –1. We also derive the luminosity-specific classical nova rate for this galaxy, which is $${7.88}_{-2.6}^{+2.3}\\,{\\mathrm{yr}}^{-1}/{10}^{10}\\,{L}_{\\odot }{,}_{K}$$. Both rates are 3–4 times higher than those reported for M87 in the past, and similarly higher than those reported for all other galaxies. As a result, we suggest that most previous ground-based surveys for novae in external galaxies, including M87, miss most faint, fast novae, and almost all slow novae near the centers of galaxies.« less

In vitro culture of stress erythroid progenitors identifies distinct progenitor populations and analogous human progenitors.

PubMed

Xiang, Jie; Wu, Dai-Chen; Chen, Yuanting; Paulson, Robert F

2015-03-12

Tissue hypoxia induces a systemic response designed to increase oxygen delivery to tissues. One component of this response is increased erythropoiesis. Steady-state erythropoiesis is primarily homeostatic, producing new erythrocytes to replace old erythrocytes removed from circulation by the spleen. In response to anemia, the situation is different. New erythrocytes must be rapidly made to increase hemoglobin levels. At these times, stress erythropoiesis predominates. Stress erythropoiesis is best characterized in the mouse, where it is extramedullary and utilizes progenitors and signals that are distinct from steady-state erythropoiesis. In this report, we use an in vitro culture system that recapitulates the in vivo development of stress erythroid progenitors. We identify cell-surface markers that delineate a series of stress erythroid progenitors with increasing maturity. In addition, we use this in vitro culture system to expand human stress erythroid progenitor cells that express analogous cell-surface markers. Consistent with previous suggestions that human stress erythropoiesis is similar to fetal erythropoiesis, we demonstrate that human stress erythroid progenitors express fetal hemoglobin upon differentiation. These data demonstrate that similar to murine bone marrow, human bone marrow contains cells that can generate BMP4-dependent stress erythroid burst-forming units when cultured under stress erythropoiesis conditions. © 2015 by The American Society of Hematology.

Nova-driven winds in globular clusters

NASA Technical Reports Server (NTRS)

Scott, E. H.; Durisen, R. H.

1978-01-01

Recent sensitive searches for H-alpha emission from ionized intracluster gas in globular clusters have set upper limits that conflict with theoretical predictions. It is suggested that nova outbursts heat the gas, producing winds that resolve this discrepancy. The incidence of novae in globular clusters, the conversion of kinetic energy of the nova shell to thermal energy of the intracluster gas, and the characteristics of the resultant winds are discussed. Calculated emission from the nova-driven models does not conflict with any observations to date. Some suggestions are made concerning the most promising approaches for future detection of intracluster gas on the basis of these models. The possible relationship of nova-driven winds to globular cluster X-ray sources is also considered.

Synoptic GNIRS XD Spectra ToO Novae

NASA Astrophysics Data System (ADS)

Woodward, Chick; Helton, Andrew; Spitzer/Chandra Team

2007-02-01

Novae are important contributors to galactic chemical enrichment on local scales. NIR spectroscopy of novae provides information about the elemental abundances of the gas and dust in the ejecta dispersing into the ISM as well as kinematic information related to the outburst. We propose to obtain synoptic GNIRS spectra of select Target of Opportunity (ToO) novae in the Magellanic Clouds (MC) and the galaxy to study the dynamics of the ejecta, to determine the temporal evolution of coronal lines and recombination lines (measuring their strength and velocity profiles), and to determine abundances. Being all equidistant, MC nova permit a more robust analysis of distant-dependent physical parameters of outburst than is generally possible for Galactic novae. The GNIRS data will provide critical spectral coverage and synoptic data to complement extant Spitzer and Chandra nova programs. Triggering of the GNIRS program will occur when a nova becomes brighter than V=12 mag, (assuming that adequate PWFS guide stars exist) as reported in the IAUC or CBET.

A Hubble Space Telescope Survey for Novae in M87. I. Light and Color Curves, Spatial Distributions, and the Nova Rate

NASA Astrophysics Data System (ADS)

Shara, Michael M.; Doyle, Trisha F.; Lauer, Tod R.; Zurek, David; Neill, J. D.; Madrid, Juan P.; Mikołajewska, Joanna; Welch, D. L.; Baltz, Edward A.

2016-11-01

The Hubble Space Telescope has imaged the central part of M87 over a 10 week span, leading to the discovery of 32 classical novae (CNe) and nine fainter, likely very slow, and/or symbiotic novae. In this first paper of a series, we present the M87 nova finder charts, and the light and color curves of the novae. We demonstrate that the rise and decline times, and the colors of M87 novae are uncorrelated with each other and with position in the galaxy. The spatial distribution of the M87 novae follows the light of the galaxy, suggesting that novae accreted by M87 during cannibalistic episodes are well-mixed. Conservatively using only the 32 brightest CNe we derive a nova rate for M87: {363}-45+33 novae yr‑1. We also derive the luminosity-specific classical nova rate for this galaxy, which is {7.88}-2.6+2.3 {yr}}-1/{10}10 {L}ȯ {,}K. Both rates are 3–4 times higher than those reported for M87 in the past, and similarly higher than those reported for all other galaxies. We suggest that most previous ground-based surveys for novae in external galaxies, including M87, miss most faint, fast novae, and almost all slow novae near the centers of galaxies. Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by AURA, Inc., under NASA contract NAS 5-26555.

Discovery of a New Classical Nova Shell Around a Nova-like Cataclysmic Variable

NASA Astrophysics Data System (ADS)

Guerrero, Martín A.; Sabin, Laurence; Tovmassian, Gagik; Santamaría, Edgar; Michel, Raul; Ramos-Larios, Gerardo; Alarie, Alexandre; Morisset, Christophe; Bermúdez Bustamante, Luis C.; González, Chantal P.; Wright, Nicholas J.

2018-04-01

The morphology and optical spectrum of IPHASX J210204.7+471015, a nebula classified as a possible planetary nebula are, however, strikingly similar to those of AT Cnc, a classical nova shell around a dwarf nova. To investigate its true nature, we have obtained high-resolution narrowband [O III] and [N II] images and deep optical spectra. The nebula shows an arc of [N II]-bright knots notably enriched in nitrogen, while an [O III]-bright bow shock is progressing throughout the ISM. Diagnostic line ratios indicate that shocks are associated with the arc and bow shock. The central star of this nebula has been identified by its photometric variability. Time-resolved photometric and spectroscopic data of this source reveal a period of 4.26 hr, which is attributed to a binary system. The optical spectrum is notably similar to that of RW Sex, a cataclysmic variable star (CV) of the UX UMa nova-like (NL) type. Based on these results, we propose that IPHASX J210204.7 + 471015 is a classical nova shell observed around a CV-NL system in quiescence.

High-cadence Multi-color Observations of the Dwarf Nova KSP-OT-201503a by the KMTNet Supernova Program

NASA Astrophysics Data System (ADS)

Brown, Shannon; Moon, Dae-Sik; Ni, Yuan Qi; Drout, Maria; Antoniadis, John; Afsariardchi, Niloufar; Cha, Sang-Mok; Lee, Yongseok

2018-06-01

We report multicolor BVI monitoring and spectroscopic classification of the dwarf nova KSP-OT-201503a. The transient was detected by the Korean Microlensing Telescope Network (KMTNet) Supernova Program (KSP) in 2015 March, reached a peak apparent magnitude V ≃ 17.3 mag from a quiescent magnitude V ≃ 22.6 mag, and lasted for approximately 17 days. Our high-cadence sampling allows us to identify distinctive phases consisting of a rapid ascent, a main outburst composed of a flat plateau followed by a gradual dimming, and a quick decline. We observe the sharp transition between the ascent phase and main outburst phase, likely related to the deceleration of the heating front as it passes through the accretion disk. These features in the light curves indicate that the outburst is outside-in. Archival data reveal the outburst history of the source, showing at least three outbursts between 2011 and 2015. These are equally separated by approximately 25 months, though we find a recurrence time as short as 189 days is compatible with the archival data. An optical spectrum obtained 701 days from outburst peak shows prominent Balmer emission lines superimposed on a blue continuum, consistent with a cataclysmic variable in quiescence. The outburst properties of KSP-OT-201503a closely resemble those of U Gem-type dwarf novae usually associated with younger, longer-period systems above the period gap of 2–3 hr observed in cataclysmic variables. This suggests that the source may be a rare U Gem-type dwarf nova with a long recurrence time, though we are unable to rule out the possibility that KSP-OT-201503a lies below the period gap.

Outburst-related period changes of recurrent nova CI aquilae

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wilson, R. E.; Honeycutt, R. K., E-mail: honey@astro.indiana.edu, E-mail: rewilson@ufl.edu

2014-11-01

Pre-outburst and post-outburst light curves and post-outburst eclipse timings are analyzed to measure any period (P) change related to nova CI Aql's outburst of early 2000 and a mean post-outburst dP/dt, which then lead to estimates of the accreting component's rate of mass (M) change and its overall outburst-related change of mass over roughly a decade of observations. We apply a recently developed procedure for unified analysis of three timing-related data types (light curves, radial velocities, and eclipse timings), although with only light curves and timings in this case. Fits to the data are reasonably good without need for amore » disk in the light-curve model, although the disk certainly exists and has an important role in our post-outburst mass flow computations. Initial experiments showed that, although there seems to be an accretion hot spot, it has essentially no effect on derived outburst-related ΔP or on post-outburst dP/dt. Use of atomic time (HJED) in place of HJD also has essentially nil effect on ΔP and dP/dt. We find ΔP consistently negative in various types of solutions, although at best only marginally significant statistically in any one experiment. Pre-outburst HJD {sub 0} and P results are given, as are post-outburst HJD {sub 0}, P, and dP/dt, with light curves and eclipse times as joint input, and also with only eclipse time input. Post-outburst dP/dt is negative at about 2.4σ. Explicit formulae for mass transfer rates and epoch-to-epoch mass change are developed and applied. A known offset in the magnitude zero point for 1991-1994 is corrected.« less

NOVA.

ERIC Educational Resources Information Center

WGBH-TV, Boston, MA.

News clippings, reviews, and feature articles about the Public Broadcasting System science-adventure series "Nova" are collected here. Included are comments from the New York Times, Washington Post, Christian Science Monitor, and TV Guide. Commentaries are primarily favorable and include synopses of various episodes. (DGC)

The Nova-Dwarf Nova Connection

NASA Astrophysics Data System (ADS)

De Marco, Orsola

The extraordinary discovery that thermonuclear runaway (TNR) processed material lives on the white dwarf (WD) surface in the dwarf nova (DN) system VW Hyi is in direct conflict with the currently accepted model for DNe. The WD in VW Hyi should be continuously buried in solar-abundance material accreted from its fully-convective, low-mass main sequence companion. IT ISNT. There are either subtle metallicity-varying forces at work, or the current theory of DNe is completely wrong. Only by monitoring the abundances of key elements throughout an entire dwarf nova cycle will we be able to observe the rate of change of key abundance ratios by accretion and mixing processes, and hence deduce the relative importance of diffusion (in removing metals), accretion (in adding metals) and (non-party line but possible) local nuclear burning. FUSE is ideal for this task, because its spectral range contains key lines of important elements, because of its high temperature sensitivity and because in its wavelength range, the VW Hyi spectrum is totally dominated by the WD. VW Hyi is the obvious candidate for this project, because we already know that its abundances are indicative of recent TNR processing.

BLOBS IN SPACE: THE LEGACY OF A NOVA

NASA Technical Reports Server (NTRS)

2002-01-01

TThe prolific number of eruptions by the recurrent nova T Pyxidis has attracted the attention of many telescopes. The image on the left, taken by a ground-based telescope, shows shells of gas around the star that were blown off during several eruptions. Closer inspection by the Hubble Space Telescope (right-hand image), however, reveals that the shells are not smooth at all. In fact, this high-resolution image shows that the shells are actually more than 2,000 gaseous blobs packed into an area that is 1 light-year across. Resembling shrapnel from a shotgun blast, the blobs may have been produced by the nova explosion, the subsequent expansion of gaseous debris, or collisions between fast-moving and slow- moving gas from several eruptions. False color has been applied to this image to enhance details in the blobs. The ground-based image was taken Jan. 19, 1995 by the European Southern Observatory's New Technology Telescope in La Silla, Chile. The Hubble telescope picture is a compilation of data taken on Feb. 26, 1994, and June 16, Oct. 7, and Nov. 10, 1995, by the Wide Field and Planetary Camera 2. T Pyxidis is 6,000 light-years away in the dim southern constellation Pyxis, the Mariner's Compass. Credits: Mike Shara, Bob Williams, and David Zurek (Space Telescope Science Institute); Roberto Gilmozzi (European Southern Observatory); Dina Prialnik (Tel Aviv University); and NASA.

Olivier Chesneau's Work on Novae

NASA Astrophysics Data System (ADS)

Millour, F.; Lagadec, E.

2015-12-01

Olivier Chesneau founded a brand new field of observational astrophysics with his attempts to resolve the novae expanding fireball from the very first days of the explosion. With the images he could get, he showed that novae do indeed explode in an aspherical way, leading to a change of paradigm for the physics of these yet-poorly understood catastrophic systems. He also set the stage for a new way of estimating novae distances, by directly measuring the sky-size of the fireball and comparing it with spectroscopic scales, taking into account the tremendous effects of the fireball geometry.

The spectroscopic evolution of the recurrent nova T Pyxidis during its 2011 outburst. III. The ultraviolet development from iron curtain through the post-X-ray turnoff

NASA Astrophysics Data System (ADS)

De Gennaro Aquino, I.; Shore, S. N.; Schwarz, G. J.; Mason, E.; Starrfield, S.; Sion, E. M.

2014-02-01

We continue the analysis of the multiwavelength evolution of the recurrent nova T Pyx during its 2011 outburst, focussing on the spectral development on the 1150-3000 Å region. This extraordinary data set presents the longest temporal baseline high resolution view of the ultraviolet for any nova to date (classical or recurrent). The observations cover the early Fe-curtain stage, when the UV was completely optically thick, to 834 days after discovery when the outburst was effectively over. We present an analysis of dynamics and abundances of the interstellar species whose resonance lines are accessible in the UV. The Lyα profile is consistent with only interstellar absorption at all epochs and agrees with the H I 21 cm column density. The distance obtained to T Pyx is about 5 kpc, based on the ISM analysis. For the ejecta evolution we have been able to follow the changes in ionization and structure with previously unobtained resolution and cadence. The excited state isoelectronic transitions of C III, N IV], and O V displayed the same detached absorption lines as the optical He I transitions during the optical maximum. This is explained as resonance absorption within the ejecta of FUV ground state lines from the 300-1000 Å range. The resonance lines of all species showed absorption components between -1000 and -3000 km s-1 as soon as the Fe-curtain turned transparent (from day 105); these persisted at the same velocities and varied in strength from one ion to another through day 834. The last ultraviolet spectrum, taken more than 800 days after outburst, showed the same absorption lines on N V and C IV as day 105. There was no evidence of circumstellar absorbers. This and the related observations of profile evolution effectively rule out any wind model for the spectrum. The picture that emerges is of ejecta that became optically thin after visual maximum as the X-ray emission became visible following an outwardly propagating ionization front and for which the

IM Nor monitoring requested for HST COS observations

NASA Astrophysics Data System (ADS)

Waagen, Elizabeth O.

2017-02-01

Dr. Ed Sion (Villanova University) and colleagues have requested AAVSO observers' assistance in monitoring the symbiotic-type recurrent nova IM Nor in support of observations with the Hubble Space Telescope Cosmic Origins Spectrograph scheduled for 2017 February 13 - 17 UT. These observations are part of a study on short orbital period recurrent novae as Supernovae Type Ia progenitors. It is essential to know 24 hours prior to the HST COS observations that IM Nor is not in outburst, in order to protect the instrumentation. Also, photometry is needed throughout the HST window to insure knowledge of the brightness of the system. Observers are asked to monitor IM Nor with nightly snapshot images (V preferred) from now through February 20, and to report their observations promptly. It will be especially important to know the brightness of IM Nor each night through February 17 UT. Finder charts with sequence may be created using the AAVSO Variable Star Plotter (https://www.aavso.org/vsp). Observations should be submitted to the AAVSO International Database. See full Alert Notice for more details.

Unusual ``Stunted'' Outbursts in Old Novae and Nova-Like Cataclysmic Variables

NASA Astrophysics Data System (ADS)

Honeycutt, R. K.; Robertson, J. W.; Turner, G. W.

1998-06-01

Outbursts averaging 0.6 mag in amplitude and 10 days in width are described in five old novae and nova-like cataclysmic variables: UU Aqr, Q Cyg, CP Lac, X Ser, and RW Sex. These stars are thought to be high mass transfer rate systems for which the accretion disk is expected to be stable against the thermal instability responsible for dwarf nova outbursts. The widths and spacings of these events are similar to those of dwarf nova eruptions, but the amplitudes are significantly smaller, or ``stunted.'' The outbursts are sometimes accompanied by dips. These dips have amplitudes that are similar to the outbursts' but have shapes that scatter significantly more than the shapes of the outbursts. The outbursts and dips sometimes occur as pairs and are sometimes isolated. We are not able at this time to determine a single common mechanism for this behavior, or even to conclude that some mechanisms are preferred. Rather, we characterize these phenomena with regard to outburst shapes and frequency of occurrence and explore a range of possible causes, including truncated disks, mass transfer modulations, and Z Camelopardalis type behavior. Arguments are assembled for and against such possible mechanisms, and key observations are suggested. It appears unlikely that accretion disk instabilities are the single common cause of these phenomena, and we are left with either a combination of accretion disk and mass transfer events or a situation in which mass transfer events are somehow responsible for all these varied behaviors.

NOVA Fall 2002 Teacher's Guide.

ERIC Educational Resources Information Center

Ransick, Kristina; Rosene, Dale; Sammons, James; Turck, Mary

This NOVA teacher's guide presents activities, information, and teaching ideas from the Public Broadcasting System's (PBS) NOVA television program series. Episodes include: (1) "Mysterious Life of Caves" which investigates the role microbes play in the creation of some limestone caves; (2) "Lost Roman Treasure" which follows…

Nova M33N 2012-10a

NASA Astrophysics Data System (ADS)

Alothman, Nourah

In this thesis I present a study and measurement of a Nova in M33 galaxy type N 2012-10a (which is type of binary star) using data that were collected by the ROTSE IIIb robotic telescope and another observatory. I study the fundamental properties of the light curve and determined the brightness and the velocity of this type of nova. I analyzed the spectra that were measured by the Hobby-Eberly Telescope (HET) at the McDonald Observatory. In addition, I compared this type of nova to other types of Novae.

The 2011 Eruption of the Recurrent Nova T Pyxidis: The Discovery, the Pre-eruption Rise, the Pre-eruption Orbital Period, and the Reason for the Long Delay

NASA Astrophysics Data System (ADS)

Schaefer, Bradley E.; Landolt, Arlo U.; Linnolt, Michael; Stubbings, Rod; Pojmanski, Grzegorz; Plummer, Alan; Kerr, Stephen; Nelson, Peter; Carstens, Rolf; Streamer, Margaret; Richards, Tom; Myers, Gordon; Dillon, William G.

2013-08-01

We report the discovery by M. Linnolt on JD 2,455,665.7931 (UT 2011 April 14.29) of the sixth eruption of the recurrent nova T Pyxidis. This discovery was made just as the initial fast rise was starting, so with fast notification and response by observers worldwide, the entire initial rise was covered (the first for any nova), and with high time resolution in three filters. The speed of the rise peaked at 9 mag day-1, while the light curve is well fit over only the first two days by a model with a uniformly expanding sphere. We also report the discovery by R. Stubbings of a pre-eruption rise starting 18 days before the eruption, peaking 1.1 mag brighter than its long-time average, and then fading back toward quiescence 4 days before the eruption. This unique and mysterious behavior is only the fourth known (with V1500 Cyg, V533 Her, and T CrB) anticipatory rise closely spaced before a nova eruption. We present 19 timings of photometric minima from 1986 to 2011 February, where the orbital period is fast increasing with P/\\dot{P}=+313{,000} yr. From 2008 to 2011, T Pyx had a small change in this rate of increase, so that the orbital period at the time of eruption was 0.07622950 ± 0.00000008 days. This strong and steady increase of the orbital period can only come from mass transfer, for which we calculate a rate of (1.7-3.5) × 10-7 M ⊙ yr-1. We report 6116 magnitudes between 1890 and 2011, for an average B = 15.59 ± 0.01 from 1967 to 2011, which allows for an eruption in 2011 if the blue flux is nearly proportional to the accretion rate. The ultraviolet-optical-infrared spectral energy distribution is well fit by a power law with f νvpropν1.0, although the narrow ultraviolet region has a tilt with a fit of f νvpropν1/3. We prove that most of the T Pyx light is not coming from a disk, or any superposition of blackbodies, but rather is coming from some nonthermal source. We confirm the extinction measure from IUE with E(B - V) = 0.25 ± 0.02 mag.

THE 2011 ERUPTION OF THE RECURRENT NOVA T PYXIDIS: THE DISCOVERY, THE PRE-ERUPTION RISE, THE PRE-ERUPTION ORBITAL PERIOD, AND THE REASON FOR THE LONG DELAY

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schaefer, Bradley E.; Landolt, Arlo U.; Linnolt, Michael

We report the discovery by M. Linnolt on JD 2,455,665.7931 (UT 2011 April 14.29) of the sixth eruption of the recurrent nova T Pyxidis. This discovery was made just as the initial fast rise was starting, so with fast notification and response by observers worldwide, the entire initial rise was covered (the first for any nova), and with high time resolution in three filters. The speed of the rise peaked at 9 mag day{sup -1}, while the light curve is well fit over only the first two days by a model with a uniformly expanding sphere. We also report themore » discovery by R. Stubbings of a pre-eruption rise starting 18 days before the eruption, peaking 1.1 mag brighter than its long-time average, and then fading back toward quiescence 4 days before the eruption. This unique and mysterious behavior is only the fourth known (with V1500 Cyg, V533 Her, and T CrB) anticipatory rise closely spaced before a nova eruption. We present 19 timings of photometric minima from 1986 to 2011 February, where the orbital period is fast increasing with P/ P-dot =+313,000 yr. From 2008 to 2011, T Pyx had a small change in this rate of increase, so that the orbital period at the time of eruption was 0.07622950 {+-} 0.00000008 days. This strong and steady increase of the orbital period can only come from mass transfer, for which we calculate a rate of (1.7-3.5) Multiplication-Sign 10{sup -7} M{sub Sun} yr{sup -1}. We report 6116 magnitudes between 1890 and 2011, for an average B = 15.59 {+-} 0.01 from 1967 to 2011, which allows for an eruption in 2011 if the blue flux is nearly proportional to the accretion rate. The ultraviolet-optical-infrared spectral energy distribution is well fit by a power law with f{sub {nu}}{proportional_to}{nu}{sup 1.0}, although the narrow ultraviolet region has a tilt with a fit of f{sub {nu}}{proportional_to}{nu}{sup 1/3}. We prove that most of the T Pyx light is not coming from a disk, or any superposition of blackbodies, but rather is coming from some

A Hubble Space Telescope survey for novae in M87 - III. Are novae good standard candles 15 d after maximum brightness?

NASA Astrophysics Data System (ADS)

Shara, Michael M.; Doyle, Trisha F.; Pagnotta, Ashley; Garland, James T.; Lauer, Tod R.; Zurek, David; Baltz, Edward A.; Goerl, Ariel; Kovetz, Attay; Machac, Tamara; Madrid, Juan P.; Mikołajewska, Joanna; Neill, J. D.; Prialnik, Dina; Welch, D. L.; Yaron, Ofer

2018-02-01

Ten weeks of daily imaging of the giant elliptical galaxy M87 with the Hubble Space Telescope (HST) has yielded 41 nova light curves of unprecedented quality for extragalactic cataclysmic variables. We have recently used these light curves to demonstrate that the observational scatter in the so-called maximum-magnitude rate of decline (MMRD) relation for classical novae is so large as to render the nova-MMRD useless as a standard candle. Here, we demonstrate that a modified Buscombe-de Vaucouleurs hypothesis, namely that novae with decline times t2 > 10 d converge to nearly the same absolute magnitude about two weeks after maximum light in a giant elliptical galaxy, is supported by our M87 nova data. For 13 novae with daily sampled light curves, well determined times of maximum light in both the F606W and F814W filters, and decline times t2 > 10 d we find that M87 novae display M606W,15 = -6.37 ± 0.46 and M814W,15 = -6.11 ± 0.43. If very fast novae with decline times t2 < 10 d are excluded, the distances to novae in elliptical galaxies with stellar binary populations similar to those of M87 should be determinable with 1σ accuracies of ± 20 per cent with the above calibrations.

Radio Observations of Nova Muscae 2018 and Nova Carinae 2018 (ASASSN-18fv)

NASA Astrophysics Data System (ADS)

Ryder, S. D.; Kool, E. C.; Chomiuk, L.

2018-04-01

The two optically-bright Galactic novae in Musca (CBET #4473, ATel #11183, #11201, #11212, #11296) and in Carina (ATel #11454, #11456, #11457, #11460, #11468) were observed at radio wavelengths using the Australia Telescope Compact Array (ATCA) on 2018 Apr 3.3 UT. Nova Muscae 2018 has faded by a factor of 3 at 9.0 and 5.5 GHz since peaking at > 30 mJy/bm in mid-March.

Magnetic novae

NASA Astrophysics Data System (ADS)

Zemko, Polina; Orio, Marina

2016-07-01

We present the results of optical and X-ray observations of two quiescent novae, V2491 Cyg and V4743 Sgr. Our observations suggest the intriguing possibility of localization of hydrogen burning in magnetic novae, in which accretion is streamed to the polar caps. V2491 Cyg was observed with Suzaku more than 2 years after the outburst and V4743 Sgr was observed with XMM Newton 2 and 3.5 years after maximum. In the framework of a monitoring program of novae previously observed as super soft X-ray sources we also obtained optical spectra of V4743 Sgr with the SALT telescope 11.5 years after the eruption and of V2491 Cyg with the 6m Big Azimutal Telescope 4 and 7 years post-outburst. In order to confirm the possible white dwarf spin period of V2491 Cyg measured in the Suzaku observations we obtained photometric data using the 90cm WIYN telescope at Kitt Peak and the 1.2 m telescope in Crimea. We found that V4743 Sgr is an intermediate polar (IP) and V2491 Cyg is a strong IP candidate. Both novae show modulation of their X-ray light curves and have X-ray spectra typical of IPs. The Suzaku and XMM Newton exposures revealed that the spectra of both novae have a very soft blackbody-like component with a temperature close to that of the hydrogen burning white dwarfs in their SSS phases, but with flux by at least two orders of magnitude lower, implying a possible shrinking of emitting regions in the thin atmosphere that is heated by nuclear burning underneath it. In quiescent IPs, independently of the burning, an ultrasoft X-ray flux component originates at times in the polar regions irradiated by the accretion column, but the soft component of V4743 Sgr disappeared in 2006, indicating that the origin may be different from accretion. We suggest it may have been due to an atmospheric temperature gradient on the white dwarf surface, or to continuing localized thermonuclear burning at the bottom of the envelope, before complete turn-off. The optical spectra of V2491 Cyg and V

Recent progress in understanding the eruptions of classical novae

NASA Technical Reports Server (NTRS)

Shara, Michael M.

1988-01-01

Dramatic progress has occurred in the last two decades in understanding the physical processes and events leading up to, and transpiring during the eruption of a classical nova. The mechanism whereby a white dwarf accreting hydrogen-rich matter from a low-mass main-sequence companion produces a nova eruption has been understood since 1970. The mass-transferring binary stellar configuration leads inexorably to thermonuclear runaways detected at distances of megaparsecs. Summarized here are the efforts of many researchers in understanding the physical processes which generate nova eruptions; the effects upon nova eruptions of different binary-system parameters (e.g., chemical composition or mass of the white dwarf, different mass accretion rates); the possible metamorphosis from dwarf to classical novae and back again; and observational diagnostics of novae, including x ray and gamma ray emission, and the characteristics and distributions of novae in globular clusters and in extragalactic systems. While the thermonuclear-runaway model remains the successful cornerstone of nova simulation, it is now clear that a wide variety of physical processes, and three-dimensional hydrodynamic simulations, will be needed to explain the rich spectrum of behavior observed in erupting novae.

Recurrent nova M31N 2008-12a: The 2017-eruption X-ray turn-off seen by Swift/XRT

NASA Astrophysics Data System (ADS)

Henze, M.; Darnley, M. J.; Shafter, A. W.; Kafka, S.; Kato, M.; Williams, S. C.; et al.

2018-01-01

The detection of supersoft X-ray source (SSS) emission from the 2017 eruption (ATel #11116) of the rapidly recurring nova M31N 2008-12a (Henze et al. 2014, 2015a, 2015b; Darnley et al. 2014, 2015, 2016) with the Neil Gehrels Swift observatory was announced in ATel #11130.

X-ray Modeling of Classical Novae

NASA Astrophysics Data System (ADS)

Nemeth, Peter

2010-01-01

It has been observed and theoretically supported in the last decade that the peak of the spectral energy distribution of classical novae gradually shifts to higher energies at constant bolometric luminosity after a nova event. For this reason, comprehensive evolutionary studies require spectral analysis in multiple spectral bands. After a nova explosion, the white dwarf can maintain stable surface hydrogen burning, the duration of which strongly correlates with the white dwarf mass. During this stage the peak of the luminosity is in the soft X-ray band (15 - 60 Angstroms). By extending the modeling range of TLUSTY/SYNSPEC, I analyse the luminosity and abundance evolution of classical novae. Model atoms required for this work were built using atomic data from NIST/ASD and TOPBASE. The accurate but incomplete set of energy levels and radiative transitions in NIST were completed with calculated data from TOPBASE. Synthetic spectra were then compared to observed data to derive stellar parameters. I show the capabilities and validity of this project on the example of V4743 Sgr. This nova was observed with both Chandra and XMM-Newton observatories and has already been modeled by several scientific groups (PHOENIX, TMAP).

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

PubMed

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 Hubble Space Telescope survey for novae in M87 – III. Are novae good standard candles 15 d after maximum brightness?

DOE PAGES

Shara, Michael M.; Doyle, Trisha F.; Pagnotta, Ashley; ...

2017-11-16

Ten weeks of daily imaging of the giant elliptical galaxy M87 with the Hubble Space Telescope (HST) has yielded 41 nova light curves of unprecedented quality for extragalactic cataclysmic variables. We have recently used these light curves to demonstrate that the observational scatter in the so-called maximum-magnitude rate of decline (MMRD) relation for classical novae is so large as to render the nova-MMRD useless as a standard candle. Here in this paper, we demonstrate that a modified Buscombe–de Vaucouleurs hypothesis, namely that novae with decline times t2 > 10 d converge to nearly the same absolute magnitude about two weeksmore » after maximum light in a giant elliptical galaxy, is supported by our M87 nova data. For 13 novae with daily sampled light curves, well determined times of maximum light in both the F606W and F814W filters, and decline times t 2 > 10 d we find that M87 novae display M606W,15 = -6.37 ± 0.46 and M814W,15 = -6.11 ± 0.43. If very fast novae with decline times t 2 < 10 d are excluded, the distances to novae in elliptical galaxies with stellar binary populations similar to those of M87 should be determinable with 1σ accuracies of ± 20 percent with the above calibrations.« less

A Hubble Space Telescope survey for novae in M87 – III. Are novae good standard candles 15 d after maximum brightness?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shara, Michael M.; Doyle, Trisha F.; Pagnotta, Ashley

Ten weeks of daily imaging of the giant elliptical galaxy M87 with the Hubble Space Telescope (HST) has yielded 41 nova light curves of unprecedented quality for extragalactic cataclysmic variables. We have recently used these light curves to demonstrate that the observational scatter in the so-called maximum-magnitude rate of decline (MMRD) relation for classical novae is so large as to render the nova-MMRD useless as a standard candle. Here in this paper, we demonstrate that a modified Buscombe–de Vaucouleurs hypothesis, namely that novae with decline times t2 > 10 d converge to nearly the same absolute magnitude about two weeksmore » after maximum light in a giant elliptical galaxy, is supported by our M87 nova data. For 13 novae with daily sampled light curves, well determined times of maximum light in both the F606W and F814W filters, and decline times t 2 > 10 d we find that M87 novae display M606W,15 = -6.37 ± 0.46 and M814W,15 = -6.11 ± 0.43. If very fast novae with decline times t 2 < 10 d are excluded, the distances to novae in elliptical galaxies with stellar binary populations similar to those of M87 should be determinable with 1σ accuracies of ± 20 percent with the above calibrations.« less

Integration of the Super Nova early warning system with the NOvA Trigger

DOE Office of Scientific and Technical Information (OSTI.GOV)

Habig, Alec; Zirnstein, Jan

The NOvA experiment, with a baseline of 810km, samples Fermilab’s upgraded NuMI beam with a Near Detector on-site and a Far Detector (FD) at Ash River, MN, to observe oscillations of muon neutrinos. The 344,064 liquid scintillator-filled cells of the 14 kton FD provide high granularity of a large detector mass and enable us to also study non-accelerator based neutrinos with our Data Driven Trigger framework. This paper will focus on the real time integration of the SNEWS with the NOvA Trigger where we have set up an XML-RPC based messaging system to inject the SNEWS signal directly into ourmore » trigger. In conclusion, this presents a departure from the E-Mail based notification mechanism used by SNEWS in the past and allows NOvA more control over propagation and transmission timing.« less

Integration of the Super Nova early warning system with the NOvA Trigger

DOE PAGES

Habig, Alec; Zirnstein, Jan

2015-12-23

The NOvA experiment, with a baseline of 810km, samples Fermilab’s upgraded NuMI beam with a Near Detector on-site and a Far Detector (FD) at Ash River, MN, to observe oscillations of muon neutrinos. The 344,064 liquid scintillator-filled cells of the 14 kton FD provide high granularity of a large detector mass and enable us to also study non-accelerator based neutrinos with our Data Driven Trigger framework. This paper will focus on the real time integration of the SNEWS with the NOvA Trigger where we have set up an XML-RPC based messaging system to inject the SNEWS signal directly into ourmore » trigger. In conclusion, this presents a departure from the E-Mail based notification mechanism used by SNEWS in the past and allows NOvA more control over propagation and transmission timing.« less

The active quiescence of HR Del (Nova Del 1967). The ex-nova HR Del

NASA Astrophysics Data System (ADS)

Selvelli, P.; Friedjung, M.

2003-04-01

This new UV study of the ex-nova HR Del is based on all of the data obtained with the International Ultraviolet Explorer (IUE) satellite, and includes the important series of spectra taken in 1988 and 1992 that have not been analyzed so far. This has allowed us to make a detailed study of both the long-timescale and the short-timescale UV variations, after the return of the nova, around 1981-1982, to the pre-outburst optical magnitude. After the correction for the reddening (EB-V=0.16), adopting a distance d =850 pc we have derived a mean UV luminosity close to LUV ~ 56 Lsun, the highest value among classical novae in ``quiescence". Also the ``average" optical absolute magnitude (Mv=+2.30) is indicative of a bright object. The UV continuum luminosity, the HeII 1640 Å emission line luminosity, and the optical absolute magnitude all give a mass accretion rate dot {M} very close to 1.4x 10-7 Msun yr-1, if one assumes that the luminosity of the old nova is due to a non-irradiated accretion disk. The UV continuum has declined by a factor less than 1.2 over the 13 years of the IUE observations, while the UV emission lines have faded by larger factors. The continuum distribution is well fitted with either a black body of 33 900 K, or a power-law Flambda ~ lambda -2.20. A comparison with the grid of models of Wade & Hubeny (\\cite{Wade}) indicates a low M1 value and a relatively high dot {M} but the best fittings to the continuum and the line spectrum come from different models. We show that the ``quiescent" optical magnitude at mv ~ 12 comes from the hot component and not from the companion star. Since most IUE observations correspond to the ``quiescent" magnitude at mv ~ 12, the same as in the pre-eruption stage, we infer that the pre-nova, for at least 70 years prior to eruption, was also very bright at near the same LUV, Mv, dot {M}, and T values as derived in the present study for the ex-nova. The wind components in the P Cyg profiles of the CIV 1550 Å and NV 1240 �

Copernicus observations of Nova Cygni 1975

NASA Technical Reports Server (NTRS)

Jenkins, E. B.; Snow, T. P.; Upson, W. L.; Anderson, R.; Starrfield, S. G.; Gallagher, J. S.; Friedjung, M.; Linsky, J. L.; Henry, R. C.; Moos, H. W.

1977-01-01

Near-ultraviolet radiation from Nova Cygni 1975 was detected by the Copernicus satellite on five occasions from 1975 September 1 to 1975 September 9. The nova was not seen in the UV after this date. The principal result was the observation of a broad emission feature from the Mg II doublet at 2800 A. The absence of strong UV radiation at shorter wavelengths suggests that these lines are produced by collisional excitation in the outer layers of an expanding shell with electron temperature of approximately 4000 K. The absence of observed emission lines from highly ionized species indicates that the amount of material with log T between 4.4 and 5.7 is less than 0.001 times that which produces the Mg II emission. The continuum flux in the near-UV decreased as the nova evolved, showing that the total luminosity decreased as the nova faded in the visible.

Expanded Very Large Array Nova Project Observations of the Classical Nova V1723 Aquilae

NASA Astrophysics Data System (ADS)

Krauss, Miriam I.; Chomiuk, Laura; Rupen, Michael; Roy, Nirupam; Mioduszewski, Amy J.; Sokoloski, J. L.; Nelson, Thomas; Mukai, Koji; Bode, M. F.; Eyres, S. P. S.; O'Brien, T. J.

2011-09-01

We present radio light curves and spectra of the classical nova V1723 Aql obtained with the Expanded Very Large Array (EVLA). This is the first paper to showcase results from the EVLA Nova Project, which comprises a team of observers and theorists utilizing the greatly enhanced sensitivity and frequency coverage of EVLA radio observations, along with observations at other wavelengths, to reach a deeper understanding of the energetics, morphology, and temporal characteristics of nova explosions. Our observations of V1723 Aql span 1-37 GHz in frequency, and we report on data from 14 to 175 days following the time of the nova explosion. The broad frequency coverage and frequent monitoring show that the radio behavior of V1723 Aql does not follow the classic Hubble-flow model of homologous spherically expanding thermal ejecta. The spectra are always at least partially optically thin, and the flux rises on faster timescales than can be reproduced with linear expansion. Therefore, any description of the underlying physical processes must go beyond this simple picture. The unusual spectral properties and light curve evolution might be explained by multiple emitting regions or shocked material. Indeed, X-ray observations from Swift reveal that shocks are likely present.

Expanded Very Large Array Nova Project Observations of the Classical NovaV1723 Aquilae

NASA Technical Reports Server (NTRS)

Krauss, Miriam I.; Chomiuk, Laura; Rupen, Michael; Roy, Nirupam; Mioduszewski, Amy J.; Sokoloski, J. L.; Nelson, Thomas; Mukai, Koji; Bode, M. F.; Eyres, S. P. S.;

ORIGINS OF ABSORPTION SYSTEMS OF CLASSICAL NOVA V2659 CYG (NOVA CYG 2014)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Arai, A.; Kawakita, H.; Shinnaka, Y.

2016-10-10

We report on high-dispersion spectroscopy results of a classical nova V2659 Cyg (Nova Cyg 2014) that are taken 33.05 days after the V -band maximum. The spectrum shows two distinct blueshifted absorption systems originating from H i, Fe ii, Ca ii, etc. The radial velocities of the absorption systems are −620 km s{sup −1}, and −1100 to −1500 km s{sup −1}. The higher velocity component corresponds to the P-Cygni absorption features frequently observed in low-resolution spectra. Much larger numbers of absorption lines are identified at the lower velocity. These mainly originate from neutral or singly ionized Fe-peak elements (Fe i,more » Ti ii, Cr ii, etc.). Based on the results of our spectroscopic observations, we discuss the structure of the ejecta of V2659 Cyg. We conclude that the low- and high-velocity components are likely to be produced by the outflow wind and the ballistic nova ejecta, respectively.« less

Laying the foundation for a digital Nova Scotia

NASA Astrophysics Data System (ADS)

Bond, J.

2016-04-01

In 2013, the Province of Nova Scotia began an effort to modernize its coordinate referencing infrastructure known as the Nova Scotia Coordinate Referencing System (NSCRS). At that time, 8, active GPS stations were installed in southwest Nova Scotia to evaluate the technology's ability to address the Province's coordinate referencing needs. The success of the test phase helped build a business case to implement the technology across the entire Province. It is anticipated that by the end of 2015, 40 active GPS stations will be in place across Nova Scotia. This infrastructure, known as the Nova Scotia Active Control Stations (NSACS) network, will allow for instantaneous, centimetre level positioning across the Province. Originally designed to address the needs of the surveying community, the technology has also proven to have applications in mapping, machine automation, agriculture, navigation, emergency response, earthquake detection and other areas. In the foreseeable future, all spatial data sets captured in Nova Scotia will be either directly or indirectly derived from the NSACS network. The technology will promote high accuracy and homogenous spatial data sets across the Province. The technology behind the NSACS and the development of the system are described. Examples of how the technology is contributing to a digital Nova Scotia are presented. Future applications of the technology are also considered.

NovaSearch Online: Research Experience in Astronomy 101

NASA Astrophysics Data System (ADS)

Pilachowski, C. A.; Rector, T.; Morris, F.; Tebbe, H.

2003-12-01

A new website at the University of Indiana Bloomington allows undergraduate, introductory astronomy students to participate in original research, discovering novae in the Andromeda Galaxy. Sequences of CCD images obtained with the WIYN 0.9-m telescope at Kitt Peak of the central region of Andromeda are displayed on the Web as Flash movies, allowing students to identify novae as new, blinking stars. Tools are provided to estimate the magnitude of the novae and to determine the Julian date of observations, so that students can plot light curves. The goal of NovaSearch is to engage students in the process of discovery, applying the content they learn from textbooks and lectures to real observations and the creation of new knowledge. NovaSearch is supplemented with live video interactions with on-site observers and remote observing at the 0.9-m telescope. For many students, NovaSearch is their first experience with science as a creative, human activity. NovaSearch is available for examination and use at www.astro.indiana.edu/novasearch/ Support from the SBC Fellows program at Indiana University, as well as from the National Science Foundation through grant ESI 0101982 to the National Optical Astronomy Observatory, is gratefully acknowledged.

FUSE Observations of Galactic and LMC Novae in Outburst

NASA Technical Reports Server (NTRS)

Huschildt, P. H.

2001-01-01

This document is a collection of five abstracts from papers written on the 'FUSE Observations of Galactic and LMC Novae in Outburst'. The titles are the following: (1) Analyzing FUSE Observations of Galactic and LMC Novae; (2) Detailed NLTE Model Atmospheres for Novae during Outburst: Modeling Optical and Ultraviolet Observations for Nova LMC 1988; (3) Numerical Solution of the Expanding Stellar Atmosphere Problem; (4) A Non-LTE Line-Blanketed Expanding Atmosphere Model for A-supergiant Alpha Cygni; and (5) Non-LTE Model Atmosphere Analysis of the Early Ultraviolet Spectra of Nova Andromedae 1986. A list of journal publications is also included.

NOVA2-mediated RNA regulation is required for axonal pathfinding during development.

PubMed

Saito, Yuhki; Miranda-Rottmann, Soledad; Ruggiu, Matteo; Park, Christopher Y; Fak, John J; Zhong, Ru; Duncan, Jeremy S; Fabella, Brian A; Junge, Harald J; Chen, Zhe; Araya, Roberto; Fritzsch, Bernd; Hudspeth, A J; Darnell, Robert B

2016-05-25

The neuron specific RNA-binding proteins NOVA1 and NOVA2 are highly homologous alternative splicing regulators. NOVA proteins regulate at least 700 alternative splicing events in vivo, yet relatively little is known about the biologic consequences of NOVA action and in particular about functional differences between NOVA1 and NOVA2. Transcriptome-wide searches for isoform-specific functions, using NOVA1 and NOVA2 specific HITS-CLIP and RNA-seq data from mouse cortex lacking either NOVA isoform, reveals that NOVA2 uniquely regulates alternative splicing events of a series of axon guidance related genes during cortical development. Corresponding axonal pathfinding defects were specific to NOVA2 deficiency: Nova2-/- but not Nova1-/- mice had agenesis of the corpus callosum, and axonal outgrowth defects specific to ventral motoneuron axons and efferent innervation of the cochlea. Thus we have discovered that NOVA2 uniquely regulates alternative splicing of a coordinate set of transcripts encoding key components in cortical, brainstem and spinal axon guidance/outgrowth pathways during neural differentiation, with severe functional consequences in vivo.

Mesenchymal progenitor cells for the osteogenic lineage.

PubMed

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.

Dust Evolution in Nova Cassiopeia 1993

NASA Astrophysics Data System (ADS)

Eyres, S. P. S.; Evans, A.; Geballe, T. R.; Davies, J. K.; Rawlings, J. M. C.

1997-07-01

We present UKIRT spectroscopy of Nova Cassiopeia 1993 (= V705 Cas) in KLNQ bands, taken in 1994 and 1995. Fitting the continuum indicates a dust temperature T ˜ 740 750 K in the latter part of 1994; this is similar to earlier measurements, and consistent with the “isothermal” behaviour observed in novae with optically thick dust shells. The β-index drops from 0.8 to 0.4 over the same period. This suggests grain growth; grain diameter increases from < 0.54 µm around day 256, to > 0.57 µm by day 342. The UIR features differ from those in other Galactic sources, and are similar to those in V842 Cen. This suggests fundamental differences between the UIR carriers, or environments, in novae and other Galactic sources. The silicate feature is consistent with an amorphous structure, in contrast to previous novae. We believe that grains in V705 Cas form two populations: silicates, and hydrocarbons.

Detecting Nova Shells around known Cataclysmic Variable systems

NASA Astrophysics Data System (ADS)

Xhakaj, Enia; Kupfer, Thomas; Prince, Thomas A.

2017-01-01

Nova shells are hydrogen-rich nebulae around Cataclysmic Variables that are created when a Nova outburst takes place. Learning more about Nova shells can help us get a better understanding of the long-term evolution of white dwarfs in active Cataclysmic Variables. In this project, we present the search for Nova shells around 1700 Cataclysmic Variables, using Hα images from the Palomar Transient Factory (PTF) survey. The PTF Hα survey started in 2009 using the 48’’ Oschin telescope at Palomar Observatory and is the first of its type covering the whole northern hemisphere while reaching 18 mags in 60 seconds of exposure. We concentrated our search on the IAU catalogue of Historical Novae, as well as on the SDSS and the Ritter-Kolb catalogue of Cataclysmic Variables. We numerically analyzed radial profiles centered on the target sources to search for excess emission potentially associated with the shells. Out of 1700 Cataclysmic Variables present in these catalogues, we detected 25 Nova shells, out of which 20 are not observed before.

NOVA2-mediated RNA regulation is required for axonal pathfinding during development

PubMed Central

Saito, Yuhki; Miranda-Rottmann, Soledad; Ruggiu, Matteo; Park, Christopher Y; Fak, John J; Zhong, Ru; Duncan, Jeremy S; Fabella, Brian A; Junge, Harald J; Chen, Zhe; Araya, Roberto; Fritzsch, Bernd; Hudspeth, A J; Darnell, Robert B

2016-01-01

The neuron specific RNA-binding proteins NOVA1 and NOVA2 are highly homologous alternative splicing regulators. NOVA proteins regulate at least 700 alternative splicing events in vivo, yet relatively little is known about the biologic consequences of NOVA action and in particular about functional differences between NOVA1 and NOVA2. Transcriptome-wide searches for isoform-specific functions, using NOVA1 and NOVA2 specific HITS-CLIP and RNA-seq data from mouse cortex lacking either NOVA isoform, reveals that NOVA2 uniquely regulates alternative splicing events of a series of axon guidance related genes during cortical development. Corresponding axonal pathfinding defects were specific to NOVA2 deficiency: Nova2-/- but not Nova1-/- mice had agenesis of the corpus callosum, and axonal outgrowth defects specific to ventral motoneuron axons and efferent innervation of the cochlea. Thus we have discovered that NOVA2 uniquely regulates alternative splicing of a coordinate set of transcripts encoding key components in cortical, brainstem and spinal axon guidance/outgrowth pathways during neural differentiation, with severe functional consequences in vivo. DOI: http://dx.doi.org/10.7554/eLife.14371.001 PMID:27223325

Near-Infrared Emission Lines of Nova Cassiopeiae 1995

NASA Astrophysics Data System (ADS)

Rudy, R. J.; Lynch, D. K.; Mazuk, S. M.; Venturini, C. C.; Puetter, R. C.

2000-12-01

The slow nova V 723 Cas (Nova Cas 1995) exhibits comparatively narrow emission features (FWHM 500 km sec-1) that make it ideal for classifying weak lines and lines blended with stronger features. We present spectra from 0.8-2.5 microns that track the gradual incrase in excitation of Nova Cas and discuss the emission lines that were present. During the period encompassed by these observations Nova Cas reached only moderate excitation-the most energetic coronal lines were [S VIII] 9913 and [Al IX] 20444; lines such as [S IX] 12523 that are prominent in some novae were not detected. Additional coronal lines present include [Si VI] 19641, [Ca VIII] 23205, and [Si VII] 24807. New lines identified include features of [Fe V], [Fe VI]. These iron features are not coronal lines, arising from transitions among low-lying terms rather than within the ground term itself. Also detected was [Ti VI] 17151 that was first identified in V1974 Cygni (Nova Cyg 1992), and possibly [Ti VII] 22050. Accurate wavelengths for a number of unidentified lines are also presented. These unidentified features are discussed with regard to their likely level of excitation and their presence in other novae. This work was supported by the IR&D program of the Aerospace Corporation. RCP acknowledges support from NASA.

On Presolar Stardust Grains from CO Classical Novae

NASA Astrophysics Data System (ADS)

Iliadis, Christian; Downen, Lori N.; José, Jordi; Nittler, Larry R.; Starrfield, Sumner

2018-03-01

About 30%–40% of classical novae produce dust 20–100 days after the outburst, but no presolar stardust grains from classical novae have been unambiguously identified yet. Although several studies claimed a nova paternity for certain grains, the measured and simulated isotopic ratios could only be reconciled, assuming that the grains condensed after the nova ejecta mixed with a much larger amount of close-to-solar matter. However, the source and mechanism of this potential post-explosion dilution of the ejecta remains a mystery. A major problem with previous studies is the small number of simulations performed and the implied poor exploration of the large nova parameter space. We report the results of a different strategy, based on a Monte Carlo technique, that involves the random sampling over the most important nova model parameters: the white dwarf composition; the mixing of the outer white dwarf layers with the accreted material before the explosion; the peak temperature and density; the explosion timescales; and the possible dilution of the ejecta after the outburst. We discuss and take into account the systematic uncertainties for both the presolar grain measurements and the simulation results. Only those simulations that are consistent with all measured isotopic ratios of a given grain are accepted for further analysis. We also present the numerical results of the model parameters. We identify 18 presolar grains with measured isotopic signatures consistent with a CO nova origin, without assuming any dilution of the ejecta. Among these, the grains G270_2, M11-334-2, G278, M11-347-4, M11-151-4, and Ag26 have the highest probability of a CO nova paternity.

Spectral and photometric study of the symbiotic nova RS ophiuchus in quiet phase

NASA Astrophysics Data System (ADS)

Kondratyeva, L.; Rspaev, F.; Krugov, M.; Serebryanskiy, A.

2017-07-01

The results of spectral and photometric study of the recurrent Nova RS Ophiuchus are presented and discussed. Observations were carried out in 2009-2016. During these eight years the fluxes of HI and FeII emission lines have slightly decreased by a factor of 3 - 4. Hα and Hβ exhibit double-peaked profiles with a central absorption. The ratio of the blue and red peaks intensities(V/R) varies from 0.3 to 1.0 for Hβ and from 0.4 to 0.7 for Hα. Possible correlations between changes of the ratio and other spectral parameters were investigated. Dependence of V/R on the radial velocity of absorbtion component is found out.

The distances of the Galactic Novae

NASA Astrophysics Data System (ADS)

Ozdonmez, Aykut; Guver, Tolga; Cabrera-Lavers, Antonio; Ak, Tansel

2016-07-01

Using location of the RC stars on the CMDs obtained from the UKIDSS, VISTA and 2MASS photometry, we have derived the reddening-distance relations towards each Galactic nova for which at least one independent reddening measurement exists. We were able to determine the distances of 72 Galactic novae and set lower limits on the distances of 45 systems. The reddening curves of the systems are presented. These curves can be also used to estimate reddening or the distance of any source, whose location is close to the position of the nova in our sample. The distance measurement method in our study can be easily applicable to any source, especially for ones that concentrated along the Galactic plane.

Can isolated single black holes produce X-ray novae?

NASA Astrophysics Data System (ADS)

Matsumoto, Tatsuya; Teraki, Yuto; Ioka, Kunihito

2018-03-01

Almost all black holes (BHs) and BH candidates in our Galaxy have been discovered as soft X-ray transients, so-called X-ray novae. X-ray novae are usually considered to arise from binary systems. Here, we propose that X-ray novae are also caused by isolated single BHs. We calculate the distribution of the accretion rate from interstellar matter to isolated BHs, and find that BHs in molecular clouds satisfy the condition of the hydrogen-ionization disc instability, which results in X-ray novae. The estimated event rate is consistent with the observed one. We also check an X-ray novae catalogue (Corral-Santana et al.) and find that 16/59 ˜ 0.27 of the observed X-ray novae are potentially powered by isolated BHs. The possible candidates include IGR J17454-2919, XTE J1908-094, and SAX J1711.6-3808. Near-infrared photometric and spectroscopic follow-ups can exclude companion stars for a BH census in our Galaxy.

GE-17ALTERATION OF THE p53 PATHWAY AND ANCESTRAL PROGENITORS ARE ASSOCIATED WITH TUMOR RECURRENCE IN GLIOBLASTOMA

PubMed Central

Kim, Hoon; Zheng, Siyuan; Amini, Seyed; Virk, Selene; Mikkelsen, Tom; Brat, Daniel; Sougnez, Carrie; Muller, Florian; Hu, Jian; Sloan, Andrew; Cohen, Mark; Van Meir, Erwin; Scarpace, Lisa; Lander, Eric; Gabriel, Stacey; Getz, Gad; Meyerson, Matthew; Chin, Lynda; Barnholtz-Sloan, Jill; Verhaak, Roel

2014-01-01

To evaluate evolutionary patterns of GBM recurrence, we analyzed whole genome sequencing (WGS) and multi-sector exome sequencing data from pairs of primary and posttreatment GBM. WGS on ten primary-recurrent pairs detected a median number of 12,214 mutations which we utilized to uncover clonal structures, by analyzing the distribution of mutation cellular frequencies (the fraction of tumor cells harboring a mutation). On average, 41 % of the mutations were shared by primary and recurrence. The majority of shared mutations were clonal in both primary and recurrence, but we also observed many clonal mutations that were uniquely detected in either the primary or the recurrence. This raises the intriguing possibility that major tumor clones in the primary tumor and disease relapse both evolved from a shared ancestral tumor cell population. At least one subclone was identified in the majority of WGS samples, and we observed groups of mutations that were at low cancer cell fractions in both primary and recurrence, suggesting that both subclones evolved from the same ancestral tumor cells separate from the major clone ancestral cells. To address the possibility that the lack of overlap between subsequent tumors was due to intratumoral heterogeneity, we analyzed exome sequencing from a second tumor sector of seven primary and six recurrent tumors. We found that the majority of "second biopsy" mutations were not conserved between time points, suggesting that intratumoral heterogeneity did not explain the large number of mutations uniquely detected in primary and recurrence. The limited overlap of mutations in primary and recurrence provides evidence for ancestral tumor cell populations that could not be eradicated by therapy, while offspring cell populations contained unique mutations, were selectively killed by treatment and could therefore no longer be detected after disease relapse. This study has provided new insights into patterns and dynamics of tumor evolution.

A Self-consistent Model for a Full Cycle of Recurrent Novae—Wind Mass-loss Rate and X-Ray Luminosity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kato, Mariko; Saio, Hideyuki; Hachisu, Izumi, E-mail: mariko.kato@hc.st.keio.ac.jp

2017-04-01

An unexpectedly slow evolution in the pre-optical-maximum phase was suggested in the very short recurrence period of nova M31N 2008-12a. To obtain reasonable nova light curves we have improved our calculation method by consistently combining optically thick wind solutions of hydrogen-rich envelopes with white dwarf (WD) structures calculated by a Henyey-type evolution code. The wind mass-loss rate is properly determined with high accuracy. We have calculated light curve models for 1.2 M {sub ⊙} and 1.38 M {sub ⊙} WDs with mass accretion rates corresponding to recurrence periods of 10 yr and 1 yr, respectively. The outburst lasts 590/29 days,more » in which the pre-optical-maximum phase is 82/16 days, for 1.2/1.38 M {sub ⊙}, respectively. Optically thick winds start at the end of the X-ray flash and cease at the beginning of the supersoft X-ray phase. We also present supersoft X-ray light curves including a prompt X-ray flash and later supersoft X-ray phase.« less

Nova in Ophiuchus

NASA Astrophysics Data System (ADS)

Templeton, Matthew R.

2009-08-01

Nova Ophiuchi 2009 was discovered by Koichi Itagaki, Teppo-Cho, Yamagata, Japan, at unfiltered CCD magnitude 10.1 on August 16.515 UT, and confirmed by him on Aug. 16.526. After posting to the CBET Unconfirmed Observations page, the object was confirmed independently by several observers. The discovery and confirmatory information were intially reported in CBET 1910, CBET 1911, and AAVSO Special Notice #166. The nova, located in a very crowded field within the Milky Way, is reported by T. Kato (vsnet-alert 11399) to have a large B-V (+1.6), indicating it is highly reddened. N Oph 2009 has been assigned the identifiers VSX J173819.7-264413 and the AUID 000-BJP-605. Please submit observations to the AAVSO International Database using the name N OPH 2009.

Orbital eccentricity in classical novae

NASA Technical Reports Server (NTRS)

Edwards, D. A.; Pringle, J. E.

1987-01-01

The effect on the orbital parameters of a classical nova of the ejection of mass during the nova explosion is considered. The most easily observable consequence is the generation of a small eccentricity in the orbit which leads to a luminosity modulation at a period just longer than the orbital period. Observation of such an effect would have implications not just for interpreting the dynamics of the explosion but also for measuring the secular effect of tidal interaction after the outburst.

Outflows from Compact Objects in Supernovae and Novae

NASA Astrophysics Data System (ADS)

Vlasov, Andrey Dmitrievich

Originally thought of as a constant and unchanging place, the Universe is full of dramas of stars emerging, dying, eating each other, colliding, etc. One of the first transient phenomena noticed were called novae (the name means "new" in Latin). Years later, supernovae were discovered. Despite their names, both novae and supernovae are events in relatively old stars, with supernovae marking the point of stellar death. Known for thousands of years, supernovae and novae remain among the most studied events in our Universe. Supernovae strongly influence the circumstellar medium, enriching it with heavy elements and shocking it, facilitating star formation. Cosmic rays are believed to be accelerated in shocks from supernovae, with small contribution possibly coming from novae. Even though the basic physics of novae is understood, many questions remain unanswered. These include the geometry of the ejecta, why some novae are luminous radio or gamma-ray sources and others are not, what is the ultimate fate of recurrent novae, etc. Supernova explosions are the primary sources of elements heavier than hydrogen and helium. The elements up to nuclear masses A around 100 can form through successive nuclear fusion in the cores of stars starting with hydrogen. Beyond iron, the fusion becomes endothermic instead of exothermic. In addition, for these nuclear masses the temperatures required to overcome the Coulomb barriers are so high that the nuclei are dissociated into alpha particles and free nucleons. Hence all elements heavier than A around 100 should have formed by some other means. These heavier nuclear species are formed by neutron capture on seed nuclei close to or heavier than iron-group nuclei. Depending on the ratio between neutron-capture timescale and beta-decay timescale, neutron-capture processes are called rapid or slow (r- and s-processes, respectively). The s-process, which occurs near the valley of stable isotopes, terminates at Bi (Z=83), because after Bi

Progenitor Epithelium

PubMed Central

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

BVRI Hα Photometric Evolution of Nova 2007 IN M 33

NASA Astrophysics Data System (ADS)

Munari, U.; Siviero, A.; Henden, A.; Dintinjana, B.; Mikuž, H.; Ochner, P.; Tomasoni, S.

The BVRCIC and Hα light curves of Nova 2007, located in the galaxy M 33, are presented. They display the fastest decline ever observed for a nova in this galaxy (Δ B = 0.40 ± 0.01 mag/day). Color indices of the nova match those of its counterparts in the Galaxy. The nova was discovered when it was already two magnitudes down from maximum (estimated to have occurred on September 13 at B = 15.5 mag).

Novae in External Galaxies: M51, M87, and M101

NASA Astrophysics Data System (ADS)

Shafter, A. W.; Ciardullo, R.; Pritchet, C. J.

2000-02-01

As part of a program to determine the stellar population of novae, we have conducted a multiepoch Hα survey of the galaxies M51, M87, and M101. A total of nine and 12 novae were detected in the spiral galaxies M51 and M101, respectively, during four epochs of observation, and two epochs of observation yielded a total of nine novae in the giant elliptical galaxy M87. After correcting for the effective survey time and for the fraction of luminosity sampled, we find global nova rates of 18+/-7, 91+/-34, and 12+/-4 novae per year for M51, M87, and M101, respectively. After normalizing to the total K-band luminosity of each galaxy, we estimate luminosity-specific nova rates for M51, M87, and M101 of 1.09+/-0.47, 2.30+/-0.99, and 0.97+/-0.38 novae per year per 1010 solar luminosities in K. When we compare these data with measured values for the luminosity-specific nova rates of other galaxies, we find no compelling evidence for a significant variation with Hubble type. Possible ramifications of this result are discussed within the context of current theoretical models for nova production in galaxies.

The Oligodendrocyte Progenitor Response to Demyelination

DTIC Science & Technology

2006-01-01

DATE 2006 2. REPORT TYPE 3. DATES COVERED 00-00-2006 to 00-00-2006 4. TITLE AND SUBTITLE The Oligodendrocyte Progenitor Response to Demyelination...material in the thesis manuscript entitled: “The Oligodendrocyte Progenitor Response to Demyelination” is appropriately acknowledged and, beyond... oligodendrocyte progenitor (OP) amplification prior to remyelination. Myelin transcription factor 1 (Myt1) influences OP proliferation, differentiation, and

The Impact of Liver Graft Injury on Cancer Recurrence Posttransplantation.

PubMed

Li, Chang-Xian; Man, Kwan; Lo, Chung-Mau

2017-11-01

Liver transplantation is the most effective treatment for selected patients with hepatocellular carcinoma. However, cancer recurrence, posttransplantation, remains to be the critical issue that affects the long-term outcome of hepatocellular carcinoma recipients. In addition to tumor biology itself, increasing evidence demonstrates that acute-phase liver graft injury is a result of hepatic ischemia reperfusion injury (which is an inevitable consequence during liver transplantation) and may promote cancer recurrence at late phase posttransplantation. The liver grafts from living donors, donors after cardiac death, and steatotic donors have been considered as promising sources of organs for liver transplantation and are associated with high incidence of liver graft injury. The acute-phase liver graft injury will trigger a series of inflammatory cascades, which may not only activate the cell signaling pathways regulating the tumor cell invasion and migration but also mobilize the circulating progenitor and immune cells to facilitate tumor recurrence and metastasis. The injured liver graft may also provide the favorable microenvironment for tumor cell growth, migration, and invasion through the disturbance of microcirculatory barrier function, induction of hypoxia and angiogenesis. This review aims to summarize the latest findings about the role and mechanisms of liver graft injury resulted from hepatic ischemia reperfusion injury on tumor recurrence posttransplantation, both in clinical and animal cohorts.

Nova Lupi 2011

NASA Astrophysics Data System (ADS)

Waagen, Elizabeth O.

2011-08-01

Announcement of discovery of Nova Lupi 2011 = PNV J14542000-5505030. Discovered by Nicholas Brown (Quinns Rocks, Western Australia) on 2011 Aug. 4.73 UT at unfiltered mag=10.2 (tmax 400 film). Posted on the IAU Central Bureau for Astronomical Telegrams Transient Object Confirmation Page (TOCP) as PNV J14542000-5505030. Spectra obtained by Fred Walter (SUNY Stony Brook) 2011 August 9.0132 UT with the SMARTS 1.5m RC spectrograph at Cerro Tololo and reported in ATEL #3536 confirms that the object is an Fe II nova near maximum. Initially announced in [vsnet-alert 13560] (Nicholas Brown) and in AAVSO Special Notice #247 (Arne Henden). Finder charts with sequence may be created using the AAVSO Variable Star Plotter (http://www.aavso.org/vsp). Observations should be submitted to the AAVSO International Database. See full Alert Notice for more details and observations.

The progenitors of stripped-envelope supernovae

NASA Astrophysics Data System (ADS)

Elias-Rosa, N.

2013-05-01

The type Ib/c SNe are those explosions which come from massive star populations, but lack hydrogen and helium. These have been proposed to originate in the explosions of massive Wolf-Rayet stars, and we should easily be able to detect the very luminous, young progenitors if they exist. However, there has not been any detection of progenitors so far. I present the study of two extinguished Type Ic SNe 2003jg and 2004cc. In both cases there is no clear evidence of a direct detection of their progenitors in deep pre-explosion images. Upper limits derived by inserting artificial stars of known brightness at random positions around the progenitor positions (M_v>-8.8 and M_v>-9 magnitudes for the progenitors of SN 2003jg and SN 2004cc, respectively) are brighter than those expected for a massive WC (Wolf-Rayet, carbon-rich) or WO (Wolf-Rayet, oxygen-rich) (e.g., approximately between -3 and -6 in the LMC). Therefore, this is perhaps further evidence that the most massive stars may give rise to black-holes forming SNe, or it is an undetected, compact massive star hidden by a thick dust lane. However the extinction toward these SNe is currently one of the largest known. Even if these results do not directly reveal the nature of the type Ic SN progenitors, they can help to characterize the dusty environment which surrounded the progenitor of the stripped-envelope CC-SNe.

Observations and simulations of nova Vul 1984 no. 2: A nova with ejecta rich in oxygen, neon, and magnesium

NASA Technical Reports Server (NTRS)

Starrfield, S.; Sonneborn, G.; Stryker, L. L.; Sparks, Warren M.; Truran, James W.; Ferland, Gary; Wagner, R. M.; Gallagher, J. S.; Wade, R.; Williams, R. E.

1988-01-01

Nova Vul 1984 no. 2 was observed with IUE from Dec. 1984 through Nov. 1987. The spectra are characterized by strong lines from Mg, Ne, C, Si, O, N, and other elements. Data obtained in the ultraviolet, infrared, and optical show that this nova is ejecting material rich in oxygen, neon, and magnesium.

Slow magnetic monopoles search in NOvA

NASA Astrophysics Data System (ADS)

Antoshkin, Alexander; Frank, Martin

2018-04-01

The NOvA far detector is well suited for finding exotic particles due to its technical features (see [1]). One type of those exotic particles is a "slow" magnetic monopole. It is assumed that the energy deposition of such monopoles should be enough to be registered (see [2]). Measurement of the expected signals was performed on the NOvA test bench at JINR (see [3]). Result of this measurement allows us to perform slow monopole's research using NOvA software and hardware with high efficiency. As a whole, the research can lead to a discovery, or it can limit the existence of monopoles in a wide range of parameters, previously unreachable in other experiments (MACRO, SLIM, RICE, IceCube). Several special software tools have been developed. Slow Monopole Trigger has been created and implemented in the NOvA Data-Driven-Trigger system. Also, an online reconstruction algorithm has been developed and tested on 5% of the data. A technical description of these tools and current results of the analysis are presented in this work.

Liquid Scintillator Production for the NOvA Experiment

DOE PAGES

Mufson, S.; Baugh, B.; Bower, C.; ...

2015-04-15

The NOvA collaboration blended and delivered 8.8 kt (2.72M gal) of liquid scintillator as the active detector medium to its near and far detectors. The composition of this scintillator was specifically developed to satisfy NOvA's performance requirements. A rigorous set of quality control procedures was put in place to verify that the incoming components and the blended scintillator met these requirements. The scintillator was blended commercially in Hammond, IN. The scintillator was shipped to the NOvA detectors using dedicated stainless steel tanker trailers cleaned to food grade.

Search for gamma-ray emission from Galactic novae with the Fermi -LAT

NASA Astrophysics Data System (ADS)

Franckowiak, A.; Jean, P.; Wood, M.; Cheung, C. C.; Buson, S.

2018-02-01

Context. A number of novae have been found to emit high-energy gamma rays (>100 MeV). However, the origin of this emission is not yet understood. We report on the search for gamma-ray emission from 75 optically detected Galactic novae in the first 7.4 years of operation of the Fermi Large Area Telescope using the Pass 8 data set. Aims: We compile an optical nova catalog including light curves from various resources and estimate the optical peak time and optical peak magnitude in order to search for gamma-ray emission to determine whether all novae are gamma-ray emitters. Methods: We repeated the analysis of the six novae previously identified as gamma-ray sources and developed a unified analysis strategy that we then applied to all novae in our catalog. We searched for emission in a 15 day time window in two-day steps ranging from 20 days before to 20 days after the optical peak time. We performed a population study with Monte Carlo simulations to set constraints on the properties of the gamma-ray emission of novae. Results: Two new novae candidates have been found at 2σ global significance. Although these two novae candidates were not detected at a significant level individually, taking them together with the other non-detected novae, we found a sub-threshold nova population with a cumulative 3σ significance. We report the measured gamma-ray flux for detected sources and flux upper limits for novae without significant detection. Our results can be reproduced by several gamma-ray emissivity models (e.g., a power-law distribution with a slope of 2), while a constant emissivity model (i.e., assuming novae are standard candles) can be rejected.

Search for gamma-ray emission from Galactic novae with the Fermi-LAT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Franckowiak, A.; Jean, P.; Wood, M.

Context. A number of novae have been found to emit high-energy gamma rays (>100 MeV). However, the origin of this emission is not yet understood. We report on the search for gamma-ray emission from 75 optically detected Galactic novae in the first 7.4 years of operation of the Fermi Large Area Telescope using the Pass 8 data set. Aims. We compile an optical nova catalog including light curves from various resources and estimate the optical peak time and optical peak magnitude in order to search for gamma-ray emission to determine whether all novae are gamma-ray emitters. Methods. We repeated themore » analysis of the six novae previously identified as gamma-ray sources and developed a unified analysis strategy that we then applied to all novae in our catalog. We searched for emission in a 15 day time window in two-day steps ranging from 20 days before to 20 days after the optical peak time. We performed a population study with Monte Carlo simulations to set constraints on the properties of the gamma-ray emission of novae. Results. Two new novae candidates have been found at ~ 2σ global significance. Although these two novae candidates were not detected at a significant level individually, taking them together with the other non-detected novae, we found a sub-threshold nova population with a cumulative 3σ significance. We report the measured gamma-ray flux for detected sources and flux upper limits for novae without significant detection. Lastly, our results can be reproduced by several gamma-ray emissivity models (e.g., a power-law distribution with a slope of 2), while a constant emissivity model (i.e., assuming novae are standard candles) can be rejected.« less

Search for gamma-ray emission from Galactic novae with the Fermi-LAT

DOE PAGES

Franckowiak, A.; Jean, P.; Wood, M.; ...

2018-02-05

Context. A number of novae have been found to emit high-energy gamma rays (>100 MeV). However, the origin of this emission is not yet understood. We report on the search for gamma-ray emission from 75 optically detected Galactic novae in the first 7.4 years of operation of the Fermi Large Area Telescope using the Pass 8 data set. Aims. We compile an optical nova catalog including light curves from various resources and estimate the optical peak time and optical peak magnitude in order to search for gamma-ray emission to determine whether all novae are gamma-ray emitters. Methods. We repeated themore » analysis of the six novae previously identified as gamma-ray sources and developed a unified analysis strategy that we then applied to all novae in our catalog. We searched for emission in a 15 day time window in two-day steps ranging from 20 days before to 20 days after the optical peak time. We performed a population study with Monte Carlo simulations to set constraints on the properties of the gamma-ray emission of novae. Results. Two new novae candidates have been found at ~ 2σ global significance. Although these two novae candidates were not detected at a significant level individually, taking them together with the other non-detected novae, we found a sub-threshold nova population with a cumulative 3σ significance. We report the measured gamma-ray flux for detected sources and flux upper limits for novae without significant detection. Lastly, our results can be reproduced by several gamma-ray emissivity models (e.g., a power-law distribution with a slope of 2), while a constant emissivity model (i.e., assuming novae are standard candles) can be rejected.« less

Neutrino Physics in the NOvA Experiment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sanchez, Mayly

2016-09-19

The objective of the experimental neutrino physics program at ISU is to contribute to the NOvA experiment in order to enable the measurement of the unknown neutrino parameters: the CP violation phase and the mass hierarchy. In the Summer of 2015, the NOvA Collaboration released results from the first year of data collected by the experiment. The ISU group played an important role in various aspects of these results including authoring one of the two resulting publications. During this project period and with the support of this grant the PI and her group made leading contributions both in data analysismore » and operations to the NOvA experiment.« less

WD+RG systems as the progenitors of type Ia supernovae

NASA Astrophysics Data System (ADS)

Wang, Bo; Han, Zhan-Wen

2010-03-01

Type Ia supernovae (SNe Ia) play an important role in the study of cosmic evolution, especially in cosmology. There are several progenitor models for SNe Ia proposed in the past years. By considering the effect of accretion disk instability on the evolution of white dwarf (WD) binaries, we performed detailed binary evolution calculations for the WD + red-giant (RG) channel of SNe Ia, in which a carbon-oxygen WD accretes material from a RG star to increase its mass to the Chandrasekhar mass limit. According to these calculations, we mapped out the initial and final parameters for SNe Ia in the orbital period-secondary mass (log Pi - Mi2) plane for various WD masses for this channel. We discussed the influence of the variation of the duty cycle value on the regions for producing SNe Ia. Similar to previous studies, this work also indicates that the long-period dwarf novae offer possible ways for producing SNe Ia. Meanwhile, we find that the surviving companion stars from this channel have a low mass after the SN explosion, which may provide a means for the formation of the population of single low-mass WDs (<0.45 Modot).

Discovery of an Apparent Nova in M81

NASA Astrophysics Data System (ADS)

Hornoch, K.; Kucakova, H.; Williams, S. C.; Henze, M.; Sala, G.; Jose, J.; Figueira, J.; Sin, P.; Meusinger, H.; Darnley, M. J.; Kaur, A.; Hartmann, D. H.; Shafter, A. W.

2017-12-01

The M81 nova monitoring collaboration reports the discovery of an apparent nova in M81 on a co-added 3150-s unfiltered CCD frame taken on 2017 Dec. 2.127 UT with the 0.65-m telescope at Ondrejov (OND).

Discovery of a Probable Nova in M81

NASA Astrophysics Data System (ADS)

Hornoch, K.; Kucakova, H.; Williams, S. C.; Henze, M.; Sala, G.; Jose, J.; Meusinger, H.; Darnley, M. J.; Kaur, A.; Hartmann, D. H.; Shafter, A. W.

2018-01-01

The M81 nova monitoring collaboration reports the discovery of a probable nova in M81 on a co-added 3150-s unfiltered CCD frame taken on 2018 Jan. 30.776 UT with the 0.65-m telescope at Ondrejov (OND).

Discovery of two Probable Novae in M81

NASA Astrophysics Data System (ADS)

Hornoch, K.; Kucakova, H.; Henze, M.; Sala, G.; Jose, J.; Figueira, J.; Sin, P.; Hernanz, M.; Williams, S. C.; Meusinger, H.; Darnley, M. J.; Kaur, A.; Hartmann, D. H.; Shafter, A. W.

2017-09-01

The M81 nova monitoring collaboration reports the discovery of two probable novae in M81 on a co-added 2700-s unfiltered CCD frame taken on 2017 Sep. 18.129 UT with the 0.65-m telescope at Ondrejov (OND).

Discovery of a Probable Nova in M81

NASA Astrophysics Data System (ADS)

Hornoch, K.; Kucakova, H.; Williams, S. C.; Henze, M.; Sala, G.; Jose, J.; Figueira, J.; Sin, P.; Meusinger, H.; Darnley, M. J.; Kaur, A.; Hartmann, D. H.; Shafter, A. W.

2017-12-01

The M81 nova monitoring collaboration reports the discovery of a probable nova in M81 on a co-added 2610-s unfiltered CCD frame taken on 2017 Dec. 26.016 UT with the 0.65-m telescope at Ondrejov (OND).

Nucleosynthesis and the nova outburst

NASA Technical Reports Server (NTRS)

Starrfield, S.; Truran, J.W.; Wiescher, M.; Sparks, W.M.

1995-01-01

A nova outburst is the consequence of the accretion of hydrogen rich material onto a white dwarf and it can be considered as the largest hydrogen bomb in the Universe. The fuel is supplied by a secondary star in a close binary system while the strong degeneracy of the massive white dwarf acts to contain the gas during the early stages of the explosion. The containment allows the temperature in the nuclear burning region to exceed 10(sup 8)K under all circumstances. As a result a major fraction of CNO nuclei in the envelope are transformed into (beta)(sup +)-unstable nuclei. We discuss the effects of these nuclei on the evolution. Recent observational studies have shown that there are two compositional classes of novae; one which occurs on carbon-oxygen white dwarfs, and a second class that occurs on oxygen-neon-magnesium white dwarfs. In this review we will concentrate on the latter explosions since they produce the most interesting nucleosynthesis. We report both on the results of new observational determinations of nova abundances and, in addition, new hydrodynamic calculations that examine the consequences of the accretion process on 1.0M(sub (circle dot)), 1.25M(sub (circle dot)), and 1.35M(sub (circle dot)) white dwarfs. Our results show that novae can produce (sup 22)Na, (sup 26)Al, and other intermediate mass nuclei in interesting amounts. We will present the results of new calculations, done with updated nuclear reaction rates and opacities, which exhibit quantitative differences with respect to published work.

Evolution of Nova-Dependent Splicing Regulation in the Brain

PubMed Central

Živin, Marko; Darnell, Robert B

2007-01-01

A large number of alternative exons are spliced with tissue-specific patterns, but little is known about how such patterns have evolved. Here, we study the conservation of the neuron-specific splicing factors Nova1 and Nova2 and of the alternatively spliced exons they regulate in mouse brain. Whereas Nova RNA binding domains are 94% identical across vertebrate species, Nova-dependent splicing silencer and enhancer elements (YCAY clusters) show much greater divergence, as less than 50% of mouse YCAY clusters are conserved at orthologous positions in the zebrafish genome. To study the relation between the evolution of tissue-specific splicing and YCAY clusters, we compared the brain-specific splicing of Nova-regulated exons in zebrafish, chicken, and mouse. The presence of YCAY clusters in lower vertebrates invariably predicted conservation of brain-specific splicing across species, whereas their absence in lower vertebrates correlated with a loss of alternative splicing. We hypothesize that evolution of Nova-regulated splicing in higher vertebrates proceeds mainly through changes in cis-acting elements, that tissue-specific splicing might in some cases evolve in a single step corresponding to evolution of a YCAY cluster, and that the conservation level of YCAY clusters relates to the functions encoded by the regulated RNAs. PMID:17937501

RZ Leonis Minoris bridging between ER Ursae Majoris-type dwarf nova and nova-like system

NASA Astrophysics Data System (ADS)

Kato, Taichi; Ishioka, Ryoko; Isogai, Keisuke; Kimura, Mariko; Imada, Akira; Miller, Ian; Masumoto, Kazunari; Nishino, Hirochika; Kojiguchi, Naoto; Kawabata, Miho; Sakai, Daisuke; Sugiura, Yuki; Furukawa, Hisami; Yamamura, Kenta; Kobayashi, Hiroshi; Matsumoto, Katsura; Wang, Shiang-Yu; Chou, Yi; Ngeow, Chow-Choong; Chen, Wen-Ping; Panwar, Neelam; Lin, Chi-Sheng; Hsiao, Hsiang-Yao; Guo, Jhen-Kuei; Lin, Chien-Cheng; Omarov, Chingis; Kusakin, Anatoly; Krugov, Maxim; Starkey, Donn R.; Pavlenko, Elena P.; Antonyuk, Kirill A.; Sosnjvskij, Aleksei A.; Antonyuk, Oksana I.; Pit, Nikolai V.; Baklanov, Alex V.; Babina, Julia V.; Itoh, Hiroshi; Padovan, Stefano; Akazawa, Hidehiko; Kafka, Stella; de Miguel, Enrique; Pickard, Roger D.; Kiyota, Seiichiro; Shugarov, Sergey Yu.; Chochol, Drahomir; Krushevska, Viktoriia; Sekeráš, Matej; Pikalova, Olga; Sabo, Richard; Dubovsky, Pavol A.; Kudzej, Igor; Ulowetz, Joseph; Dvorak, Shawn; Stone, Geoff; Tordai, Tamás; Dubois, Franky; Logie, Ludwig; Rau, Steve; Vanaverbeke, Siegfried; Vanmunster, Tonny; Oksanen, Arto; Maeda, Yutaka; Kasai, Kiyoshi; Katysheva, Natalia; Morelle, Etienne; Neustroev, Vitaly V.; Sjoberg, George

2016-12-01

We observed RZ LMi, which is renowned for its extremely short (˜19 d) supercycle and is a member of a small, unusual class of cataclysmic variables called ER UMa-type dwarf novae, in 2013 and 2016. In 2016, the supercycles of this object substantially lengthened in comparison to the previous measurements to 35, 32, and 60 d for three consecutive superoutbursts. We consider that the object virtually experienced a transition to the nova-like state (permanent superhumper). This observed behavior reproduced the prediction of the thermal-tidal instability model extremely well. We detected a precursor in the 2016 superoutburst and detected growing (stage A) superhumps with a mean period of 0.0602(1) d in 2016 and in 2013. Combined with the period of superhumps immediately after the superoutburst, the mass ratio is not as small as in WZ Sge-type dwarf novae, having orbital periods similar to RZ LMi. By using least absolute shrinkage and selection operator (Lasso) two-dimensional power spectra, we detected possible negative superhumps with a period of 0.05710(1) d. We estimated an orbital period of 0.05792 d, which suggests a mass ratio of 0.105(5). This relatively large mass ratio is even above that of ordinary SU UMa-type dwarf novae, and it is also possible that the exceptionally high mass-transfer rate in RZ LMi may be a result of a stripped secondary with an evolved core in a system evolving toward an AM CVn-type object.

The NOvA software testing framework

NASA Astrophysics Data System (ADS)

Tamsett, M.; C Group

2015-12-01

The NOvA experiment at Fermilab is a long-baseline neutrino experiment designed to study vε appearance in a vμ beam. NOvA has already produced more than one million Monte Carlo and detector generated files amounting to more than 1 PB in size. This data is divided between a number of parallel streams such as far and near detector beam spills, cosmic ray backgrounds, a number of data-driven triggers and over 20 different Monte Carlo configurations. Each of these data streams must be processed through the appropriate steps of the rapidly evolving, multi-tiered, interdependent NOvA software framework. In total there are greater than 12 individual software tiers, each of which performs a different function and can be configured differently depending on the input stream. In order to regularly test and validate that all of these software stages are working correctly NOvA has designed a powerful, modular testing framework that enables detailed validation and benchmarking to be performed in a fast, efficient and accessible way with minimal expert knowledge. The core of this system is a novel series of python modules which wrap, monitor and handle the underlying C++ software framework and then report the results to a slick front-end web-based interface. This interface utilises modern, cross-platform, visualisation libraries to render the test results in a meaningful way. They are fast and flexible, allowing for the easy addition of new tests and datasets. In total upwards of 14 individual streams are regularly tested amounting to over 70 individual software processes, producing over 25 GB of output files. The rigour enforced through this flexible testing framework enables NOvA to rapidly verify configurations, results and software and thus ensure that data is available for physics analysis in a timely and robust manner.

High Energy Neutrino Physics with NOvA

DOE Office of Scientific and Technical Information (OSTI.GOV)

Coan, Thomas

2016-09-09

Knowledge of the position of energy deposition in “hit” detector cells of the NOvA neutrino detector is required by algorithms for pattern reconstruction and particle identification necessary to interpret the raw data. To increase the accuracy of this process, the majority of NOvA's 350 000 far detector cell shapes, including distortions, were measured as they were constructed. Using a special laser scanning system installed at the site of the NOvA far detector in Ash River, MN, we completed algorithmic development and measured shape parameters for the far detector. The algorithm and the measurements are “published” in NOνA’s document database (docmore » #10389, “Cell Center Finder for the NOνA Far Detector Modules”).« less

π0 mass reconstruction in NOvA Far Detector.

NASA Astrophysics Data System (ADS)

Edayath, Sijith

2017-01-01

NOvA is a long-baseline neutrino oscillation experiment with functionally identical, segmented, tracking calorimeter Near and Far detectors. The detectors lie 14.6 mrad off-axis from the Fermilab NuMI beam, with a well-defined peak in neutrino energy at 2 GeV. The absolute calibration of the energy scale of the detectors is a major systematic uncertainty in long-baseline oscillation search in NOvA. Neutrino detectors make use of some standard candles for absolute energy calibration. Stopping muon energy distributions, Michel electron energy distributions, and invariant π0 mass are among them. In this talk, we cover NOvA's use of a new method to identify π0 with cosmic origins in the NOvA Far Detector. We employ a computer vision based particle identifier using convolutional neural networks (CVN) to identify π0s, complementing an existing strategy to identify π0 from the neutrino beam using more traditional methods in the Near Detector. Registered for PhD at Cochin University of Science and Technology, India and doing research in NOvA experiment at Fermilab.

PAH emission from Nova Cen 1986

NASA Technical Reports Server (NTRS)

Hyland, A. R. Harry; Mcgregor, P. J.

1989-01-01

The discovery of broad emission features between 3.2 and 3.6 microns were reported in the spectrum of Nova Cen 1986 (V842 Cen) some 300 days following outburst and remaining prominent for several months. The general characteristics of these features are similar to those attributed to polycyclic hydrocarbon (PAH) molecules in other dusty sources, although the relative strengths are different, and these observations provide the first clear evidence for molecular constituents other than graphite particles in the ejecta of novae.

The geographic accessibility of pharmacies in Nova Scotia.

PubMed

Law, Michael R; Heard, Deborah; Fisher, Judith; Douillard, Jay; Muzika, Greg; Sketris, Ingrid S

2013-01-01

Geographic proximity is an important component of access to primary care and the pharmaceutical services of community pharmacies. Variations in access to primary care have been found between rural and urban areas in Canadian and international jurisdictions. We studied access to community pharmacies in the province of Nova Scotia. We used information on the locations of 297 community pharmacies operating in Nova Scotia in June 2011. Population estimates at the census block level and network analysis were used to study the number of Nova Scotia residents living within 800 m (walking) and 2 km and 5 km (driving) distances of a pharmacy. We then simulated the impact of pharmacy closures on geographic access in urban and rural areas. We found that 40.3% of Nova Scotia residents lived within walking distance of a pharmacy; 62.6% and 78.8% lived within 2 km and 5 km, respectively. Differences between urban and rural areas were pronounced: 99.2% of urban residents lived within 5 km of a pharmacy compared with 53.3% of rural residents. Simulated pharmacy closures had a greater impact on geographic access to community pharmacies in rural areas than urban areas. The majority of Nova Scotia residents lived within walking or short driving distance of at least 1 community pharmacy. While overall geographic access appears to be lower than in the province of Ontario, the difference appears to be largely driven by the higher proportion of rural dwellers in Nova Scotia. Further studies should examine how geographic proximity to pharmacies influences patients' access to traditional and specialized pharmacy services, as well as health outcomes and adherence to therapy. Can Pharm J 2013;146:39-46.

Ultraviolet spectroscopy of old novae and symbiotic stars

NASA Technical Reports Server (NTRS)

Lambert, D. L.; Slovak, M. H.; Shields, G. A.; Ferland, G. J.

1981-01-01

The IUE spectra are presented for two old novae and for two of the symbiotic variables. Prominent emission line spectra are revealed as a continuum whose appearance is effected by the system inclination. These data provide evidence for hot companions in the symbiotic stars, making plausible the binary model for these peculiar stars. Recent IUE spectra of dwarf novae provide additional support for the existence of optically thick accretion disks in active binary systems. The ultraviolet data of the eclipsing dwarf novae EX Hya and BV Cen appear flatter than for the noneclipsing systems, an effect which could be ascribed to the system inclination.

Animal models relevant to human prostate carcinogenesis underlining the critical implication of prostatic stem/progenitor cells

PubMed Central

Mimeault, Murielle; Batra, Surinder K.

2012-01-01

Recent development of animal models relevant to human prostate cancer (PC) etiopathogenesis has provided important information on the specific functions provided by key gene products altered during disease initiation and progression to locally invasive, metastatic and hormone-refractory stages. Especially, the characterization of transgenic mouse models has indicated that the inactivation of distinct tumor suppressor proteins such as phosphatase tensin homolog deleted on chromosome 10 (PTEN), Nkx3.1, p27KIP1 and p53 and retinoblastoma (pRb) may cooperate for the malignant transformation of prostatic stem/progenitor cells into PC stem/progenitor cells and tumor development and metastases. Moreover, the sustained activation of diverse oncogenic signaling elements, including epidermal growth factor receptor (EGFR), sonic hedgehog, Wnt/β-catenin, c-Myc, Akt and nuclear factor-kappaB (NF-κB) also may contribute to the acquisition of more aggressive and hormone-refractory phenotypes by PC stem/progenitor cells and their progenies during disease progression. Importantly, it has also been shown that an enrichment of PC stem/progenitor cells expressing stem cell-like markers may occur after androgen deprivation therapy and docetaxel treatment in the transgenic mouse models of PC suggesting the critical implication of these immature PC cells in treatment resistance, tumor re-growth and disease recurrence. Of clinical interest, the molecular targeting of distinct gene products altered in PC cells by using different dietary compounds has also been shown to counteract PC initiation and progression in animal models supporting their potential use as chemopreventive or chemotherapeutic agents for eradicating the total tumor cell mass, improving current anti-hormonal and chemotherapies and preventing disease relapse. PMID:21396984

Loss of the tumor suppressor p15Ink4b enhances myeloid progenitor formation from common myeloid progenitors.

PubMed

Rosu-Myles, Michael; Taylor, Barbara J; Wolff, Linda

2007-03-01

The tumor suppressor p15Ink4b (Ink4b) is a cell-cycle inhibitor that is inactivated in a high percentage of acute myeloid leukemia and myeloid dysplasia syndrome cases. Despite this, the role of Ink4b in hematopoiesis remains unclear. Here we examined the role of Ink4b in blood cell formation using Ink4b-deficient (Ink4b(-/-)) mice. We compared the bone marrow (BM) of Ink4b(-/-) and wild-type mice using flow cytometric, colony-forming unit and competitive repopulating assays (CRA). The proliferation, differentiation, self-renewal, and apoptosis of progenitor cells were further compared by in vitro and in vivo methods. BM from Ink4b(-/-) mice contained increased numbers of granulocyte-monocyte progenitors and Gr-1(+) cells and showed a competitive advantage over wild-type cells in myeloid cell formation by CRA. Ink4b(-/-) progenitors did not demonstrate increased proliferation, self-renewing potential, or reduced apoptosis. Instead, Ink4b(-/-) common myeloid progenitors (CMPs) showed increased myeloid progenitor formation concomitant with reduced erythroid potential. This work establishes a role for Ink4b in regulating the differentiation of CMPs and indicates that loss of Ink4b enhances the formation of myeloid progenitors.

Atypical dust species in the ejecta of classical novae

NASA Astrophysics Data System (ADS)

Helton, L. A.; Evans, A.; Woodward, C. E.; Gehrz, R. D.

2011-03-01

A classical nova outburst arises from a thermonuclear runaway in the hydrogen-rich material accreted onto the surface of a white dwarf in a binary system. These explosions can produce copious amounts of heavy element enriched material that are ejected violently into the surrounding interstellar medium. In some novae, conditions in the ejecta are suitable for the formation of dust of various compositions, including silicates, amorphous carbon, silicon carbide, and hydrocarbons. Multiple dust grain types are sometimes produced in the same system. CO formation in novae may not reach saturation, thus invalidating the usual paradigm in which the C:O ratio determines the dust species. A few novae, such as V705 Cas and DZ Cru, have exhibited emission features near 6, 8, and 11 μmthat are similar to "Unidentified Infrared" (UIR) features, but with significant differences in position and band structure. Here, we present Spitzer IRS spectra of two recent dusty novae, V2361 Cyg and V2362 Cyg, that harbor similar peculiar emission structures superimposed on features arising from carbonaceous grains. In other astronomical objects, such as star forming regions and young stellar objects, emission peaks at 6.2, 7.7, and 11.3 μmhave been associated with polycyclic aromatic hydrocarbon (PAH) complexes. We suggest that hydrogenated amorphous carbon (HAC) may be the source of these features in novae based upon the spectral behavior of the emission features and the conditions under which the dust formed.

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

NASA Astrophysics Data System (ADS)

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.

SCIENCE AT NOVA.

ERIC Educational Resources Information Center

Broward County Schools, Fort Lauderdale, FL.

THE SCIENCE PROGRAM AT NOVA HIGH SCHOOL IS STRUCTURED TO MEET THE NEEDS OF A SCIENTIFIC SOCIETY. THE JUNIOR HIGH PROGRAM EMPHASIZES THE ACCUMLATION, TABULATION, AND ANALYSIS OF DATA. THE SENIOR HIGH PROGRAM MAKES USE OF THESE PROCESSES IN THE INVESTIGATION OF VARIOUS SUBJECT AREAS. THE UNITS COMPOSING THE HIGH SCHOOL CURRICULUM ARE DESCRIBED. UNIT…

Microstructures of Rare Silicate Stardust from Nova and Supernovae

NASA Technical Reports Server (NTRS)

Nguyen, A. N.; Keller, L. P.; Rahman, Z.; Messenger, S

2011-01-01

Most silicate stardust analyzed in the laboratory and observed around stellar environments derives from O-rich red giant and AGB stars [1,2]. Supernova (SN) silicates and oxides are comparatively rare, and fewer than 10 grains from no-va or binary star systems have been identified to date. Very little is known about dust formation in these stellar environments. Mineralogical studies of only three O-rich SN [3-5] and no nova grains have been performed. Here we report the microstructure and chemical makeup of two SN silicates and one nova grain.

Circulating endothelial progenitor cells and cardiovascular outcomes.

PubMed

Werner, Nikos; Kosiol, Sonja; Schiegl, Tobias; Ahlers, Patrick; Walenta, Katrin; Link, Andreas; Böhm, Michael; Nickenig, Georg

2005-09-08

Endothelial progenitor cells derived from bone marrow are believed to support the integrity of the vascular endothelium. The number and function of endothelial progenitor cells correlate inversely with cardiovascular risk factors, but the prognostic value associated with circulating endothelial progenitor cells has not been defined. The number of endothelial progenitor cells positive for CD34 and kinase insert domain receptor (KDR) was determined with the use of flow cytometry in 519 patients with coronary artery disease as confirmed on angiography. After 12 months, we evaluated the association between baseline levels of endothelial progenitor cells and death from cardiovascular causes, the occurrence of a first major cardiovascular event (myocardial infarction, hospitalization, revascularization, or death from cardiovascular causes), revascularization, hospitalization, and death from all causes. A total of 43 participants died, 23 from cardiovascular causes. A first major cardiovascular event occurred in 214 patients. The cumulative event-free survival rate increased stepwise across three increasing baseline levels of endothelial progenitor cells in an analysis of death from cardiovascular causes, a first major cardiovascular event, revascularization, and hospitalization. After adjustment for age, sex, vascular risk factors, and other relevant variables, increased levels of endothelial progenitor cells were associated with a reduced risk of death from cardiovascular causes (hazard ratio, 0.31; 95 percent confidence interval, 0.16 to 0.63; P=0.001), a first major cardiovascular event (hazard ratio, 0.74; 95 percent confidence interval, 0.62 to 0.89; P=0.002), revascularization (hazard ratio, 0.77; 95 percent confidence interval, 0.62 to 0.95; P=0.02), and hospitalization (hazard ratio, 0.76; 95 percent confidence interval, 0.63 to 0.94; P=0.01). Endothelial progenitor-cell levels were not predictive of myocardial infarction or of death from all causes. The level of

The geographic accessibility of pharmacies in Nova Scotia

PubMed Central

Heard, Deborah; Fisher, Judith; Douillard, Jay; Muzika, Greg; Sketris, Ingrid S.

2013-01-01

Introduction: Geographic proximity is an important component of access to primary care and the pharmaceutical services of community pharmacies. Variations in access to primary care have been found between rural and urban areas in Canadian and international jurisdictions. We studied access to community pharmacies in the province of Nova Scotia. Methods: We used information on the locations of 297 community pharmacies operating in Nova Scotia in June 2011. Population estimates at the census block level and network analysis were used to study the number of Nova Scotia residents living within 800 m (walking) and 2 km and 5 km (driving) distances of a pharmacy. We then simulated the impact of pharmacy closures on geographic access in urban and rural areas. Results: We found that 40.3% of Nova Scotia residents lived within walking distance of a pharmacy; 62.6% and 78.8% lived within 2 km and 5 km, respectively. Differences between urban and rural areas were pronounced: 99.2% of urban residents lived within 5 km of a pharmacy compared with 53.3% of rural residents. Simulated pharmacy closures had a greater impact on geographic access to community pharmacies in rural areas than urban areas. Conclusion: The majority of Nova Scotia residents lived within walking or short driving distance of at least 1 community pharmacy. While overall geographic access appears to be lower than in the province of Ontario, the difference appears to be largely driven by the higher proportion of rural dwellers in Nova Scotia. Further studies should examine how geographic proximity to pharmacies influences patients’ access to traditional and specialized pharmacy services, as well as health outcomes and adherence to therapy. Can Pharm J 2013;146:39-46. PMID:23795168

Late stages in the evolution of classical novae

NASA Technical Reports Server (NTRS)

Starrfield, S.; Krautter, J.; Sonneborn, G.; Shore, S. N.; Wagner, R. M.; Austin, S.; Saizar, P.; Ferland, G.; Wade, R.; Gehrz, R. D.

1990-01-01

We have begun a study of the long term evolution of novae in outburst in order to determine the means by which they return in quiescence when nuclear burning has ended. This project involves both IUE and optical observations and theoretical predictions. Recently, in the initial observational part of this project, we have obtained IUE Short Wavelength Prime (SWP) spectra of GQ Mus 1983 and QU Vul 1984. Each spectrum was a 16 hour exposure using a combined US1 plus Vilspa shift. No novae have been studied in the UV for as long as QU Vul and GQ Mus and observations of their spectral evolution are providing unique data on the turn-off time scale. We have also obtained the spectra of old novae from the IUE archives in order to compare and contrast the existing spectra with those of GQ Mus and Qu Vul. The theoretical prediction is that a nova should be very hot just before turnoff but x ray observations from EXOSAT do not confirm this prediction.

Independent Discovery of a Probable Nova in M81

NASA Astrophysics Data System (ADS)

Kucakova, H.; Hornoch, K.; Williams, S. C.; Henze, M.; Sala, G.; Jose, J.; Meusinger, H.; Darnley, M. J.; Kaur, A.; Hartmann, D. H.; Shafter, A. W.

2018-03-01

The M81 nova monitoring collaboration reports the independent discovery of a probable nova in M81 on a co-added 1350-s unfiltered CCD frame taken on 2018 Mar. 21.952 UT with the 0.65-m telescope at Ondrejov.

Independent Discovery of a Probable Nova in M81

NASA Astrophysics Data System (ADS)

Hornoch, K.; Kucakova, H.; Williams, S. C.; Henze, M.; Sala, G.; Jose, J.; Meusinger, H.; Darnley, M. J.; Kaur, A.; Hartmann, D. H.; Shafter, A. W.

2018-04-01

The M81 nova monitoring collaboration reports the independent discovery of a probable nova in M81 on a co-added 2700-s unfiltered CCD frame taken on 2018 Apr. 2.815 UT with the 0.65-m telescope at Ondrejov.

Firework Nova

NASA Image and Video Library

2017-12-08

Nova Stars are essentially giant fusion reactions occurring in the vacuum of space. Because stars have so much mass, they possess powerful gravitational force—but they don’t collapse because of the outward force generated by nuclear fusion, continually converting hydrogen atoms to helium. Sometimes stars begin orbiting each other, forming a binary star system. Typically this involves a white dwarf star and a red giant. Orbiting the red giant like a moon, the dwarf star rips matter from its companion until it essentially gags on the excess, coughing hot gas and radiation into space. This dramatic phenomenon is relatively common, and the white dwarf is not destroyed in the resulting nova. To learn more about x-ray emissions, read about NASA’s Chandra mission: www.nasa.gov/mission_pages/chandra/main/ --- Original caption: In Hollywood blockbusters, explosions are often among the stars of the show. In space, explosions of actual stars are a focus for scientists who hope to better understand their births, lives, and deaths and how they interact with their surroundings. Using NASA’s Chandra X-ray Observatory, astronomers have studied one particular explosion that may provide clues to the dynamics of other, much larger stellar eruptions. A team of researchers pointed the telescope at GK Persei, an object that became a sensation in the astronomical world in 1901 when it suddenly appeared as one of the brightest stars in the sky for a few days, before gradually fading away in brightness. Today, astronomers cite GK Persei as an example of a “classical nova,” an outburst produced by a thermonuclear explosion on the surface of a white dwarf star, the dense remnant of a Sun-like star. Read Full Article: www.nasa.gov/mission_pages/chandra/mini-supernova-explosi... NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a

Results of Statewide TerraNova Testing, Fall 1998.

ERIC Educational Resources Information Center

La Marca, Paul M.

This summary provides key findings about state, district, and school level performance on the TerraNova examinations (CTB/McGraw Hill) in Nevada in 1998-1999. The TerraNova tests are used to assess students in grades 4, 8, and 10 as stipulated by Nevada law. Within this summary, a description of performance as measured by national percentile…

The Distance to Nova V959 Mon from VLA Imaging

NASA Astrophysics Data System (ADS)

Linford, J. D.; Ribeiro, V. A. R. M.; Chomiuk, L.; Nelson, T.; Sokoloski, J. L.; Rupen, M. P.; Mukai, K.; O'Brien, T. J.; Mioduszewski, A. J.; Weston, J.

2015-06-01

Determining reliable distances to classical novae is a challenging but crucial step in deriving their ejected masses and explosion energetics. Here we combine radio expansion measurements from the Karl G. Jansky Very Large Array with velocities derived from optical spectra to estimate an expansion parallax for nova V959 Mon, the first nova discovered through its γ-ray emission. We spatially resolve the nova at frequencies of 4.5-36.5 GHz in nine different imaging epochs. The first five epochs cover the expansion of the ejecta from 2012 October to 2013 January, while the final four epochs span 2014 February-May. These observations correspond to days 126 through 199 and days 615 through 703 after the first detection of the nova. The images clearly show a non-spherical ejecta geometry. Utilizing ejecta velocities derived from three-dimensional modeling of optical spectroscopy, the radio expansion implies a distance between 0.9 ± 0.2 and 2.2 ± 0.4 kpc, with a most probable distance of 1.4 ± 0.4 kpc. This distance implies a γ-ray luminosity of 0.6× {{10}35} erg s-1, which is much less than the prototype γ-ray-detected nova, V407 Cyg, possibly due to the lack of a red giant companion in the V959 Mon system. V959 Mon also has a much lower γ-ray luminosity than other classical novae detected in γ-rays to date, indicating a range of at least a factor of 10 in the γ-ray luminosities for these explosions.

Independent Discovery of an Apparent Nova in M81

NASA Astrophysics Data System (ADS)

Hornoch, K.; Kucakova, H.; Williams, S. C.; Henze, M.; Sala, G.; Jose, J.; Meusinger, H.; Darnley, M. J.; Kaur, A.; Hartmann, D. H.; Shafter, A. W.

2018-02-01

The M81 nova monitoring collaboration reports the independent discovery of an apparent nova in M81 on a co-added 2700-s unfiltered CCD frame taken on 2018 Feb. 19.039 UT with the 0.65-m telescope at Ondrejov (OND).

Embryonic Heart Progenitors and Cardiogenesis

PubMed Central

Brade, Thomas; Pane, Luna S.; Moretti, Alessandra; Chien, Kenneth R.; Laugwitz, Karl-Ludwig

2013-01-01

The mammalian heart is a highly specialized organ, comprised of many different cell types arising from distinct embryonic progenitor populations during cardiogenesis. Three precursor populations have been identified to contribute to different myocytic and nonmyocytic cell lineages of the heart: cardiogenic mesoderm cells (CMC), the proepicardium (PE), and cardiac neural crest cells (CNCCs). This review will focus on molecular cues necessary for proper induction, expansion, and lineage-specific differentiation of these progenitor populations during cardiac development in vivo. Moreover, we will briefly discuss how the knowledge gained on embryonic heart progenitor biology can be used to develop novel therapeutic strategies for the management of congenital heart disease as well as for improvement of cardiac function in ischemic heart disease. PMID:24086063

Epidemiological study of dogs with otitis externa in Cape Breton, Nova Scotia

PubMed Central

Perry, Laura R.; MacLennan, Bernard; Korven, Rebecca; Rawlings, Timothy A.

2017-01-01

From May 2008 to December 2013, 320 cases of otitis externa were diagnosed among 2012 dogs undergoing routine physical examinations at Celtic Creatures Veterinary Clinic, Sydney River, Nova Scotia for a diagnosis frequency of 15.9% [95% confidence interval (CI): 14.3% to 17.6%]. Twenty-four percent of these dogs exhibited 1 or multiple recurrences despite initial treatment with topical antimicrobial/anti-inflammatory solutions. The frequency of diagnosis was significantly higher in breeds with pendulous ears, but was not affected by ear hairiness. There were no seasonal patterns in the frequency of diagnosis. In clinical examination of 60 dogs with otitis externa, bacteria were evident in 47% of infections. Of 10 genera cultured, Staphylococcus spp. and diptheroids were most common. In this study, analysis of clinical records provided insights into the local prevalence of otitis externa and the efficacy of treatment in routine clinical situations. PMID:28216686

Near-infrared and optical studies of the highly obscured nova V1831 Aquilae (Nova Aquilae 2015)

NASA Astrophysics Data System (ADS)

Banerjee, D. P. K.; Srivastava, Mudit K.; Ashok, N. M.; Munari, U.; Hambsch, F.-J.; Righetti, G. L.; Maitan, A.

2018-01-01

Near-infrared (NIR) and optical photometry and spectroscopy are presented for the nova V1831 Aquilae, covering the early decline and dust-forming phases during the first ∼90 d after its discovery. The nova is highly reddened due to interstellar extinction. Based solely on the nature of the NIR spectrum, we are able to classify the nova to be of the Fe II class. The distance and extinction to the nova are estimated to be 6.1 ± 0.5 kpc and Av ∼ 9.02, respectively. Lower limits of the electron density, emission measure and ionized ejecta mass are made from a Case B analysis of the NIR Brackett lines, while the neutral gas mass is estimated from the optical [O I] lines. We discuss the cause of the rapid strengthening of the He I 1.0830-μm line during the early stages. V1831 Aql formed a modest amount of dust fairly early (∼19.2 d after discovery); the dust shell is not seen to be optically thick. Estimates of the dust temperature, dust mass and grain size are made. Dust formation commences around day 19.2 at a condensation temperature of 1461 ± 15 K, suggestive of a carbon composition, following which the temperature is seen to decrease gradually to 950 K. The dust mass shows a rapid initial increase, which we interpret as being due to an increase in the number of grains, followed by a period of constancy, suggesting the absence of grain destruction processes during this latter time. A discussion of the evolution of these parameters is made, including certain peculiarities seen in the grain radius evolution.

Ultrastructure of extrusomes in hypotrichous ciliate Pseudourostyla nova

NASA Astrophysics Data System (ADS)

Zhou, Yao; Wang, Zhengjun; Zhang, Jun; Gu, Fukang

2011-01-01

The ultrastructure of extrusomes of the hypotrichous ciliate Pseudourostyla nova was observed in scanning and transmission electron microscopy and enzyme-cytochemistry. The results show that the distribution, morphological characteristics, morphogenesis process, and extrusive process of the extrusomes in P. nova are different from the trichocysts in Paramecium, suggesting that the extrusomes of P. nova can respond to environmental stimuli, play an important role in the defense of this species, and cannot be regarded as "trichocysts". The results also suggest that the extrusomes might be originated from the Golgi apparatus and mature in the cytoplasm; after the extrusion of mature extrusomes, the residual substance might be reabsorbed and reused by the ciliate cell via food vacuoles, and take part in material recycling of the cell.

Discovery of a New Photometric Sub-class of Faint and Fast Classical Novae

NASA Astrophysics Data System (ADS)

Kasliwal, M. M.; Cenko, S. B.; Kulkarni, S. R.; Ofek, E. O.; Quimby, R.; Rau, A.

2011-07-01

We present photometric and spectroscopic follow-up of a sample of extragalactic novae discovered by the Palomar 60 inch telescope during a search for "Fast Transients In Nearest Galaxies" (P60-FasTING). Designed as a fast cadence (1 day) and deep (g < 21 mag) survey, P60-FasTING was particularly sensitive to short-lived and faint optical transients. The P60-FasTING nova sample includes 10 novae in M 31, 6 in M 81, 3 in M 82, 1 in NGC 2403, and 1 in NGC 891. This significantly expands the known sample of extragalactic novae beyond the Local Group, including the first discoveries in a starburst environment. Surprisingly, our photometry shows that this sample is quite inconsistent with the canonical maximum-magnitude-rate-of-decline (MMRD) relation for classical novae. Furthermore, the spectra of the P60-FasTING sample are indistinguishable from classical novae. We suggest that we have uncovered a sub-class of faint and fast classical novae in a new phase space in luminosity-timescale of optical transients. Thus, novae span two orders of magnitude in both luminosity and time. Perhaps the MMRD, which is characterized only by the white dwarf mass, was an oversimplification. Nova physics appears to be characterized by a relatively rich four-dimensional parameter space in white dwarf mass, temperature, composition, and accretion rate.

A LIGHT CURVE ANALYSIS OF CLASSICAL NOVAE: FREE-FREE EMISSION VERSUS PHOTOSPHERIC EMISSION

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hachisu, Izumi; Kato, Mariko, E-mail: hachisu@ea.c.u-tokyo.ac.jp, E-mail: mariko@educ.cc.keio.ac.jp

2015-01-10

We analyzed light curves of seven relatively slower novae, PW Vul, V705 Cas, GQ Mus, RR Pic, V5558 Sgr, HR Del, and V723 Cas, based on an optically thick wind theory of nova outbursts. For fast novae, free-free emission dominates the spectrum in optical bands rather than photospheric emission, and nova optical light curves follow the universal decline law. Faster novae blow stronger winds with larger mass-loss rates. Because the brightness of free-free emission depends directly on the wind mass-loss rate, faster novae show brighter optical maxima. In slower novae, however, we must take into account photospheric emission because of theirmore » lower wind mass-loss rates. We calculated three model light curves of free-free emission, photospheric emission, and their sum for various white dwarf (WD) masses with various chemical compositions of their envelopes and fitted reasonably with observational data of optical, near-IR (NIR), and UV bands. From light curve fittings of the seven novae, we estimated their absolute magnitudes, distances, and WD masses. In PW Vul and V705 Cas, free-free emission still dominates the spectrum in the optical and NIR bands. In the very slow novae, RR Pic, V5558 Sgr, HR Del, and V723 Cas, photospheric emission dominates the spectrum rather than free-free emission, which makes a deviation from the universal decline law. We have confirmed that the absolute brightnesses of our model light curves are consistent with the distance moduli of four classical novae with known distances (GK Per, V603 Aql, RR Pic, and DQ Her). We also discussed the reason why the very slow novae are about ∼1 mag brighter than the proposed maximum magnitude versus rate of decline relation.« less

X ray and gamma ray emission from classical nova outbursts

NASA Technical Reports Server (NTRS)

Truran, James W.; Starrfield, Sumner; Sparks, Warren M.

1992-01-01

The outbursts of classical novae are now recognized to be consequences of thermonuclear runaways proceeding in accreted hydrogen-rich shells on white dwarfs in close binary systems. For the conditions that are known to exist in these environments, it is expected that soft x-rays can be emitted, and indeed x-rays were detected from a number of novae. The circumstances for which we expect novae to produce significant x-ray fluxes and provide estimates of the luminosities and effective temperatures are described. It is also known that at the high temperatures that are known to be achieved in this explosive hydrogen-burning environment, significant production of both Na-22 and Al-26 will occur. In this context, we identify the conditions for which gamma-ray emission may be expected to result from nova outbursts.

Research Developments in Li-Paczyński Novae (II): Observational Aspect

NASA Astrophysics Data System (ADS)

Shan-qin, Wang; Zi-gao, Dai; Xue-feng, Wu

2016-10-01

Since the LP-Nova models were proposed, and the short gamma-ray burst (SGRB) afterglows were confirmed, people have actively made searches for the evidence of the existence of LP-Novae among the optical (or near-infrared) counterparts of SGRBs. In this paper, we first summarize these observational progresses before 2012 in Section 2. In Section 3 and 4, we respectively introduce the basic properties of GRBs 130603B and 060614, as well as the theoretical interpretation for their near-infrared (NIR) counterparts, and their NIR excess may be the signature of the existence of LP-Novae. In Section 5, we describe the basic properties of GRB 080503, and the theoretical interpretation for its optical and X-ray counterparts, and the later re-brightening of its optical and X-ray light curves is explained as the ejecta radiation (merger-nova radiation) of magnetar heating after the neutron star merging. If the interpretations for the SGRB-associated optical and infrared counterparts are correct, they may provide the first series of direct evidence to show that SGRBs and some special LGRBs are originated from the compact star mergers. Besides LP-novae (and merger-novae), the high-speed orbital motion before the compact star merging and the merger itself will produce strong gravitational-wave bursts (GWBs). In the coming era of gravitational wave detection, the theoretical and observational studies on the electromagnetic counterparts of compact star mergers will receive more and more attentions. Due to the larger uncertainty of GWB's location, the LP-Novae associated with GWBs can serve as the best candidates for the precise location of GWBs. The fast developing high-cadence and wide-field optical-NIR surveys will make effective explorations on the LP-Novae and similar phenomena, and interact the detection and research of gravitational waves. Therefore, in the last section we present the methods for the future detections of LP-Novae, and the prospect of their multi

Constraining Calcium Production in Novae

NASA Astrophysics Data System (ADS)

Tiwari, Pranjal; C. Fry, C. Wrede Team; A. Chen, J. Liang Collaboration; S. Bishop, T. Faestermann, D. Seiler Collaboration; R. Hertenberger, H. Wirth Collaboration

2017-09-01

Calcium is an element that can be produced by thermonuclear reactions in the hottest classical novae. There are discrepancies between the abundance of Calcium observed in novae and expectations based on astrophysical models. Unbound states 1 MeV above the proton threshold affect the production of Calcium in nova models because they act as resonances in the 38 K(p , γ) 39 Ca reaction present. This work describes an experiment to measure the energies of the excited states of 39 Ca . We will bombard a thin target of 40 Ca with a beam of 22 MeV deuterons, resulting in tritons and 39Ca. We will use a Q3D magnetic spectrograph from the MLL in Garching, Germany to momenta analyze the tritons to observe the excitation energies of the resulting 39 Ca states. Simulations have been run to determine the optimal spectrograph settings. We decided to use a chemically stable target composed of CaF2 , doing so resulted in an extra contaminant, Fluorine, which is dealt with by measuring the background from a LiF target. These simulations have led to settings and targets that will result in the observation of the 39 Ca states of interest with minimal interference from contaminants. Preliminary results from this experiment will be presented. National Sciences and Engineering Research Council of Canada and U.S. National Science Foundation.

A deep optical imaging study of the nebular remnants of classical novae

NASA Astrophysics Data System (ADS)

Slavin, A. J.; O'Brien, T. J.; Dunlop, J. S.

1995-09-01

An optical imaging study of old nova remnants has revealed previously unobserved features in the shells of 13 classical novae - DQ Her, FH Ser, HR Del, GK Per, V1500 Cyg, T Aur, V533 Her, NQ Vul, V476 Cyg, DK Lac, LV Vul, RW UMi and V450 Cyg. These data indicate a possible correlation between nova speed class and the ellipticity of the resulting remnants - those of faster novae tend to comprise randomly distributed clumps of ejecta superposed on spherically symmetric diffuse material, whilst slower novae produce more structured ellipsoidal remnants with at least one and sometimes several rings of enhanced emission. By measuring the extent of the resolved shells and combining this information with previously published ejection speeds, we use expansion parallax to estimate distances for the 13 novae. Whilst we are able to deduce new information about every nova, it is notable that these observations include the first detections of shells around the old novae V450 Cyg and NQ Vul, and that velocity-resolved images of FH Ser and DQ Her have enabled us to estimate their orbital inclinations. Our observations of DQ Her also show that the main ellipsoidal shell is constricted by three rings and surrounded by a faint halo; this halo contains long tails extending outwards from bright knots, perhaps indicating that during or after outburst a fast inner wind has broken through the fractured principal shell.

Gamma-ray emission from internal shocks in novae

NASA Astrophysics Data System (ADS)

Martin, P.; Dubus, G.; Jean, P.; Tatischeff, V.; Dosne, C.

2018-04-01

Context. Gamma-ray emission at energies ≥100 MeV has been detected from nine novae using the Fermi Large Area Telescope (LAT), and can be explained by particle acceleration at shocks in these systems. Eight out of these nine objects are classical novae in which interaction of the ejecta with a tenuous circumbinary material is not expected to generate detectable gamma-ray emission. Aim. We examine whether particle acceleration at internal shocks can account for the gamma-ray emission from these novae. The shocks result from the interaction of a fast wind radiatively-driven by nuclear burning on the white dwarf with material ejected in the initial runaway stage of the nova outburst. Methods: We present a one-dimensional model for the dynamics of a forward and reverse shock system in a nova ejecta, and for the associated time-dependent particle acceleration and high-energy gamma-ray emission. Non-thermal proton and electron spectra are calculated by solving a time-dependent transport equation for particle injection, acceleration, losses, and escape from the shock region. The predicted emission is compared to LAT observations of V407 Cyg, V1324 Sco, V959 Mon, V339 Del, V1369 Cen, and V5668 Sgr. Results: The ≥100 MeV gamma-ray emission arises predominantly from particles accelerated up to 100 GeV at the reverse shock and undergoing hadronic interactions in the dense cooling layer downstream of the shock. The emission rises within days after the onset of the wind, quickly reaches a maximum, and its subsequent decrease reflects mostly the time evolution of the wind properties. Comparison to gamma-ray data points to a typical scenario where an ejecta of mass 10-5-10-4 M⊙ expands in a homologous way with a maximum velocity of 1000-2000 km s-1, followed within a day by a wind with a velocity <2000 km s-1 and a mass-loss rate of 10-4-10-3 M⊙ yr-1 declining over a time scale of a few days. Because of the large uncertainties in the measurements, many parameters of the

Evaluating local food programs: the case of Select Nova Scotia.

PubMed

Knight, Andrew J

2013-02-01

This study evaluated the effectiveness of the buy local food program Select Nova Scotia; a government program with the goal to increase awareness and consumption of Nova Scotia produced and processed agri-food products by Nova Scotians and visitors. The evaluation methodology was based on prior evaluation resources and local food consumer research. Data were gathered through a web panel survey; 877 respondents completed the survey in June 2010. The results suggest that the program is reaching a wider audience than just those predisposed to local food initiatives. In addition, awareness of Select Nova was related to perceptions of local benefits and barriers, as well as purchase motivation and behavior. Respondents who were aware of Select Nova Scotia rated societal benefits as more important and viewed location and price as less of a barrier; they were also more likely to be highly motivated to purchase local foods. This study also informs results found in previous consumer research studies and identifies marketing opportunities to enhance the effectiveness of local food programs. The results suggest that societal benefits might be used as a way to differentiate products with similar attributes. Copyright © 2012 Elsevier Ltd. All rights reserved.

Search for Gamma-Ray Emission from Galactic Novae using Fermi-LAT Pass 8

NASA Astrophysics Data System (ADS)

Buson, Sara; Franckowiak, Anna; Cheung, Teddy; Jean, Pierre; Fermi-LAT Collaboration

2016-01-01

Recently Galactic novae have been identified as a new class of GeV gamma-ray emitters, with 6 detected so far with the Fermi Large Area Telescope (Fermi-LAT) data. Based on optical observations we have compiled a catalog of ~70 Galactic novae, which peak (in optical) during the operations of the Fermi mission. Based on the properties of known gamma-ray novae we developed a search procedure that we apply to all novae in the catalog to detect these slow transient sources or set flux upper limits using the Fermi-LAT Pass 8 data set. This is the first time a large sample of Galactic novae has been uniformly studied.

Identification and isolation of adult liver stem/progenitor cells.

PubMed

Tanaka, Minoru; Miyajima, Atsushi

2012-01-01

Hepatoblasts are considered to be liver stem/progenitor cells in the fetus because they propagate and differentiate into two types of liver epithelial cells, hepatocytes and cholangiocytes. In adults, oval cells that emerge in severely injured liver are considered facultative hepatic stem/progenitor cells. However, the nature of oval cells has remained unclear for long time due to the lack of a method to isolate them. It has also been unclear whether liver stem/progenitor cells exist in normal adult liver. Recently, we and others have successfully identified oval cells and adult liver stem/progenitor cells. Here, we describe the identification and isolation of mouse liver stem/progenitor cells by utilizing antibodies against specific cell surface marker molecules.

Argonne's Vilas Pol on NOVA!

ScienceCinema

None

2018-05-18

Can innovations in materials science help clean up our world? Argonne's material scientist Vilas Pol guest starred on NOVA's "Making Stuff: Cleaner," where David Pogue explored the rapidly-developing science and business of clean energy.

A survey of IRAS data on 41 classical novae

NASA Astrophysics Data System (ADS)

Harrison, T. E.; Gehrz, R. D.

1988-09-01

The IRAS database has been searched for detections of 41 classical novae using coadditions of survey scans; 15 were detected. IRAS temporal observations of novae in outburst are discussed. The observed long-wavelength infrared distributions of DQ Her, and possibly HR Del, can be explained by emission from small (a of about 0.1 microns) dust grains heated by the central object. An alternative explanation for the energy distributions of DQ Her and HR Del is emission from fine-structure lines. FH Ser and LW Ser display energy distributions that have color temperatures much too hot to be due to heating of dust by the central source in any plausible scenario. Line emission is probably the best explanation of their observed energy distributions. The novae NQ Vul and LV Vul have energy distributions that may be contaminated by emission from galactic cirrus. The unusual object PL 1547.3-5612 exhibits an energy distribution that does not resemble those of planetary nebulae or other novae detected in this sample. An IRAS low-resolution spectrum of RR Tel shows the 10-micron silicate emission feature.

Organic molecules, ions, and rare isotopologues in the remnant of the stellar-merger candidate, CK Vulpeculae (Nova 1670)

NASA Astrophysics Data System (ADS)

Kamiński, T.; Menten, K. M.; Tylenda, R.; Karakas, A.; Belloche, A.; Patel, N. A.

2017-11-01

Context. CK Vulpeculae (CK Vul) is an enigmatic star whose outburst was observed in 1670-72. A stellar-merger event was proposed to explain its ancient eruption. Aims: We aim to investigate the composition of the molecular gas recently discovered in the remnant of CK Vul. Deriving the chemical, elemental, and isotopic composition is crucial for identifying the nature of the object and obtaining clues on its progenitor(s). Methods: We observed millimeter and submillimeter-wave spectra of CK Vul using the IRAM 30 m and APEX telescopes. Radiative-transfer modeling of the observed molecular features was performed to yield isotopic ratios for various elements. Results: The spectra of CK Vul reveal a very rich molecular environment of low excitation (Tex ≲ 12 K). Atomic carbon and twenty-seven different molecules, including two ions, were identified. They range from simple diatomic to complex polyatomic species of up to seven atoms large. The chemical composition of the molecular gas is indicative of carbon and nitrogen-driven chemistry but oxides are also present. Additionally, the abundance of fluorine may be enhanced. The spectra are rich in isotopologues that are very rare in most known sources. All stable isotopes of C, N, O, Si, and S are observed and their isotopic ratios are derived. Conclusions: The composition of the remnant's molecular gas is most peculiar and gives rise to a very unique millimeter and submillimeter spectrum. The observation of ions and complex molecules suggests the presence of a photoionizing source but its nature (a central star or shocks) remains unknown. The elemental and isotopic composition of the gas cannot be easily reconciled with standard stellar nucleosynthesis but processing in hot CNO cycles and partial helium burning can explain most of the chemical peculiarities. The isotopic ratios of CK Vul are remarkably close to those of presolar "nova grains" but the link of Nova 1670 to objects responsible for these grains is unclear

Independent Discovery of a Probable Luminous Nova in M81

NASA Astrophysics Data System (ADS)

Hornoch, K.; Kucakova, H.; Williams, S. C.; Henze, M.; Sala, G.; Jose, J.; Meusinger, H.; Darnley, M. J.; Kaur, A.; Hartmann, D. H.; Shafter, A. W.

2018-04-01

The M81 nova monitoring collaboration reports the independent discovery of a probable luminous nova in M81 on a co-added 4410-s unfiltered CCD frame taken on 2018 Apr. 9.044 UT with the 0.65-m telescope at Ondrejov.

White Dwarf/M Dwarf Binaries as Single Degenerate Progenitors of Type Ia Supernovae

NASA Astrophysics Data System (ADS)

Wheeler, J. Craig

2012-10-01

Limits on the companions of white dwarfs in the single-degenerate scenario for the origin of Type Ia supernovae (SNe Ia) have gotten increasingly tight, yet igniting a nearly Chandrasekhar mass C/O white dwarf from a condition of near hydrostatic equilibrium provides compelling agreement with observed spectral evolution. The only type of non-degenerate stars that survive the tight limits, MV >~ 8.4 on the SN Ia in SNR 0509-67.5 and MV >~ 9.5 in the remnant of SN 1572, are M dwarfs. While M dwarfs are observed in cataclysmic variables, they have special properties that have not been considered in most work on the progenitors of SNe Ia: they have small but finite magnetic fields and they flare frequently. These properties are explored in the context of SN Ia progenitors. White dwarf/M dwarf pairs may be sufficiently plentiful to provide, in principle, an adequate rate of explosions even with slow orbital evolution due to magnetic braking or gravitational radiation. Even modest magnetic fields on the white dwarf and M dwarf will yield adequate torques to lock the two stars together, resulting in a slowly rotating white dwarf, with the magnetic poles pointing at one another in the orbital plane. The mass loss will be channeled by a "magnetic bottle" connecting the two stars, landing on a concentrated polar area on the white dwarf. This enhances the effective rate of accretion compared to spherical accretion. Luminosity from accretion and hydrogen burning on the surface of the white dwarf may induce self-excited mass transfer. The combined effects of self-excited mass loss, polar accretion, and magnetic inhibition of mixing of accretion layers give possible means to beat the "nova limit" and grow the white dwarf to the Chandrasekhar mass even at rather moderate mass accretion rates.

Thyroid hormone accelerates the differentiation of adult hippocampal progenitors.

PubMed

Kapoor, R; Desouza, L A; Nanavaty, I N; Kernie, S G; Vaidya, V A

2012-09-01

Disrupted thyroid hormone function evokes severe physiological consequences in the immature brain. In adulthood, although clinical reports document an effect of thyroid hormone status on mood and cognition, the molecular and cellular changes underlying these behavioural effects are poorly understood. More recently, the subtle effects of thyroid hormone on structural plasticity in the mature brain, in particular on adult hippocampal neurogenesis, have come to be appreciated. However, the specific stages of adult hippocampal progenitor development that are sensitive to thyroid hormone are not defined. Using nestin-green fluorescent protein reporter mice, we demonstrate that thyroid hormone mediates its effects on hippocampal neurogenesis by influencing Type 2b and Type 3 progenitors, although it does not alter proliferation of either the Type 1 quiescent progenitor or the Type 2a amplifying neural progenitor. Thyroid hormone increases the number of doublecortin (DCX)-positive Type 3 progenitors, and accelerates neuronal differentiation into both DCX-positive immature neurones and neuronal nuclei-positive granule cell neurones. Furthermore, we show that this increase in neuronal differentiation is accompanied by a significant induction of specific transcription factors involved in hippocampal progenitor differentiation. In vitro studies using the neurosphere assay support a direct effect of thyroid hormone on progenitor development because neurospheres treated with thyroid hormone are shifted to a more differentiated state. Taken together, our results indicate that thyroid hormone mediates its neurogenic effects via targeting Type 2b and Type 3 hippocampal progenitors, and suggests a role for proneural transcription factors in contributing to the effects of thyroid hormone on neuronal differentiation of adult hippocampal progenitors. © 2012 The Authors. Journal of Neuroendocrinology © 2012 British Society for Neuroendocrinology.

AXIN2 expression predicts prostate cancer recurrence and regulates invasion and tumor growth.

PubMed

Hu, Brian R; Fairey, Adrian S; Madhav, Anisha; Yang, Dongyun; Li, Meng; Groshen, Susan; Stephens, Craig; Kim, Philip H; Virk, Navneet; Wang, Lina; Martin, Sue Ellen; Erho, Nicholas; Davicioni, Elai; Jenkins, Robert B; Den, Robert B; Xu, Tong; Xu, Yucheng; Gill, Inderbir S; Quinn, David I; Goldkorn, Amir

2016-05-01

Treatment of prostate cancer (PCa) may be improved by identifying biological mechanisms of tumor growth that directly impact clinical disease progression. We investigated whether genes associated with a highly tumorigenic, drug resistant, progenitor phenotype impact PCa biology and recurrence. Radical prostatectomy (RP) specimens (±disease recurrence, N = 276) were analyzed by qRT-PCR to quantify expression of genes associated with self-renewal, drug resistance, and tumorigenicity in prior studies. Associations between gene expression and PCa recurrence were confirmed by bootstrap internal validation and by external validation in independent cohorts (total N = 675) and in silico. siRNA knockdown and lentiviral overexpression were used to determine the effect of gene expression on PCa invasion, proliferation, and tumor growth. Four candidate genes were differentially expressed in PCa recurrence. Of these, low AXIN2 expression was internally validated in the discovery cohort. Validation in external cohorts and in silico demonstrated that low AXIN2 was independently associated with more aggressive PCa, biochemical recurrence, and metastasis-free survival after RP. Functionally, siRNA-mediated depletion of AXIN2 significantly increased invasiveness, proliferation, and tumor growth. Conversely, ectopic overexpression of AXIN2 significantly reduced invasiveness, proliferation, and tumor growth. Low AXIN2 expression was associated with PCa recurrence after RP in our test population as well as in external validation cohorts, and its expression levels in PCa cells significantly impacted invasiveness, proliferation, and tumor growth. Given these novel roles, further study of AXIN2 in PCa may yield promising new predictive and therapeutic strategies. © 2016 Wiley Periodicals, Inc.

On the decay of outbursts in dwarf novae nad X-ray novae

NASA Technical Reports Server (NTRS)

Cannizzo, John K.

1994-01-01

We perform computations using a time-dependent model for the accretion disk limit-cycle mechanism to examine the decay of the optical light following the peak of a dwarf nova outburst. We present the results of a parameter study of the physical input variables which affect the decay rate. In the model, the decay is brought about by a cooling transition front which begins at large radii in the disk and moves inward. The nature of the decay is strongly influenced by the radial dependence of the accretion disk viscosity parameter alpha. To obtain exponential decays for typical dwarf nova parameters, we require alpha proportional to r(exp epsilon(sub 0)), where epsilon(sub 0) approximately = 0.3-0.4. The exact value of epsilon(sub 0) which produces exponential decays depends on factors such as the mass of the accreting star and the inner radius of the accretion disk. Therefore, the observed ubiquity of exponential decays in two different types of systems (dwarf novae and X-ray novae) leads us to believe that alpha is an unnatural scaling for the viscosity. The physics of the cooling transition front must be self-regulating in that the timescale (-parital derivative of lnSigma(r)/partial derivative +)(exp -1) (where Sigma is the surface density) for mass extraction across the front remains constant. This may be consistent with a scaling alpha proportional to (h/r)(exp n), where h is the local disk semi-thickness and n approximately 1-2. As regards the speed of the cooling front, we find v(sub F)(r) proportional to r(exp p), where p approximately 3 at large radii, with an abrupt transition to p approximately 0 at some smaller radius. The r(exp 3) dependence is much steeper than has been found by previous workers and appears to result from the strong variation of specific heat within the cooling front when the front resides at a large radius in the disk. The outflow of disk material across the cooling front causes a significant departure of dln T(sub dff0/dln r from the

Nova Southeastern University Calendars

Science.gov Websites

Now / Request Info Giving Alumni Select A College Nova Southeastern University Abraham S. Fischler NSU has to offer undergraduate students. Student Life Learn why the years you spend at NSU will be II teams. Living on Campus On campus housing options for undergraduate and graduate students. Clubs

Tracking the NOvA Detectors' Performance

NASA Astrophysics Data System (ADS)

Psihas, Fernanda; NOvA Collaboration

2016-03-01

The NOvA experiment measures long baseline νμ -->νe oscillations in Fermilab's NuMI beam. We employ two detectors equipped with over 10 thousand sets of data-taking electronics; avalanche photo diodes and front end boards which collect and process the scintillation signal from particle interactions within the detectors. These sets of electronics -as well as the systems which power and cool them- must be monitored and maintained at precise working conditions to ensure maximal data-taking uptime, good data quality and a lasting life for our detectors. This poster describes the automated systems used on NOvA to simultaneously monitor our data quality, diagnose hardware issues, track our performance and coordinate maintenance for the detectors.

Naval Observatory Vector Astrometry Software (NOVAS) Version 3.1:Fortran, C, and Python Editions

NASA Astrophysics Data System (ADS)

Kaplan, G. H.; Bangert, J. A.; Barron, E. G.; Bartlett, J. L.; Puatua, W.; Harris, W.; Barrett, P.

2012-08-01

The Naval Observatory Vector Astrometry Software (NOVAS) is a source - code library that provides common astrometric quantities and transformations to high precision. The library can supply, in one or two subroutine or function calls, the instantaneous celestial position of any star or planet in a variety of coordinate systems. NOVAS also provides access to all of the building blocks that go into such computations. NOVAS is used for a wide variety of applications, including the U.S. portions of The Astronomical Almanac and a number of telescope control systems. NOVAS uses IAU recommended models for Earth orientation, including the IAU 2006 precession theory, the IAU 2000A and 2000B nutation series, and diurnal rotation based on the celestial and terrestrial intermediate origins. Equinox - based quantities, such as sidereal time, are also supported. NOVAS Earth orientation calculations match those from SOFA at the sub - microarcsecond level for comparable transformations. NOVAS algorithms for aberration an d gravitational light deflection are equivalent, at the microarcsecond level, to those inherent in the current consensus VLBI delay algorithm. NOVAS can be easily connected to the JPL planetary/lunar ephemerides (e.g., DE405), and connections to IMCCE and IAA planetary ephemerides are planned. NOVAS Version 3.1 introduces a Python edition alongside the Fortran and C editions. The Python edition uses the computational code from the C edition and currently mimics the function calls of the C edition. Future versions will expand the functionality of the Python edition to exploit the object - oriented features of Python. In the Version 3.1 C edition, the ephemeris - access functions have been revised for use on 64 - bit systems and for improved performance in general. NOVAS source code, auxiliary files, and documentation are available from the USNO website (http://aa.usno.navy.mil/software/novas/novas_info.php).

β Decay as a Probe of Explosive Nucleosynthesis in Classical Novae

NASA Astrophysics Data System (ADS)

Wrede, C.; Bennett, M. B.; Liddick, S. N.; Bardayan, D. W.; Bowe, A.; Brown, B. A.; Chen, A. A.; Chipps, K. A.; Cooper, N.; Fry, C.; Glassman, B.; Irvine, D.; José, J.; Langer, C.; Larson, N.; McNeice, E. I.; Meisel, Z.; Montes, F.; Naqvi, F.; Pain, S. D.; O'Malley, P.; Ortez, R.; Ong, W.; Pereira, J.; Pérez-Loureiro, D.; Prokop, C.; Quaglia, J.; Quinn, S.; Santia, M.; Schatz, H.; Schwartz, S. B.; Simon, A.; Shanab, S.; Spyrou, A.; Suchyta, S.; Thiagalingam, E.; Thompson, P.; Walters, M.

Classical novae are common thermonuclear explosions in the Milky Way galaxy, occurring on the surfaces of white-dwarf stars that are accreting hydrogen-rich material from companion stars. Nucleosynthesis in classical novae depends on radiative proton-capture reaction rates on radioactive nuclides. Many of these reactions cannot be measured directly at current accelerator facilities due to the lack of intense, high-quality, radioactive-ion beams at the relevant energies. Since most of these reactions proceed via resonant capture, their rates can be determined indirectly by measuring the properties of the resonances. At the National Superconducting Cyclotron Laboratory, we have used the β-delayed γ decays of 26P and 31Cl to populate resonances in 26Si and 31S and study the radiative proton captures on 25Al and 30P, respectively. These were two out of the three most important nuclear-physics uncertainties associated with the observable products of nova nucleosynthesis. The 26P experiment has enabled a more accurate estimate of the nova contribution to the long-lived Galactic 26Al detected with γ-ray telescopes. The 31Cl experiment, currently under analysis, will calibrate potential nova thermometers and mixing meters based on elemental abundance ratios, and facilitate the identification of pre-solar nova grain candidates found in primitive meteorites based on isotopic ratios.

Nova Scorpii 2011 = PNV J16551100-3838120

NASA Astrophysics Data System (ADS)

Waagen, Elizabeth O.

2011-06-01

Announces the discovery of Nova Scorpii 2011 = PNV J16551100-3838120 by John Seach (Chatsworth Island, NSW, Australia) on 2011 June 1.40 UT at magnitude 9.5 (DSLR + orange filter). Spectra by Bernard Heathcote (South Yarra, Vic, Australia) on Jun 2.4896 UT, A. Arai, T. Kajikawa, and M. Nagashima (Kyoto Sangyo University, Japan) on 2011 June 2.68 UT, and Masayuki Yamanaka and Ryosuke Itoh (Hiroshima University, Japan) on Jun 2 UT indicate a highly-reddened classical nova. Initially reported to the AAVSO by Seach and announced in AAVSO Special Notice #240 (Arne Henden) and IAU CBET 2735 (Daniel W. E. Green, ed.). The object was designated PNV J18102135-2305306 when posted on the Central Bureau's Transient Objects Confirmation Page (TOCP) webpage. Finder charts with sequence may be created using the AAVSO Variable Star Plotter (http://www.aavso.org/vsp). Observations should be submitted to the AAVSO International Database. See full Alert Notice for more details, observations, and links to images. [Nova Sco 2011 subsequently assigned the name V1312 Sco

Discovery of an old nova shell surrounding the cataclysmic variable V1315 Aql

NASA Astrophysics Data System (ADS)

Sahman, D. I.; Dhillon, V. S.; Littlefair, S. P.; Hallinan, G.

2018-07-01

Following our tentative discovery of a faint shell around V1315 Aql reported in Sahman et al., we undertook deep Hα imaging and intermediate-resolution spectroscopy of the shell. We find that the shell has its geometric centre located on V1315 Aql. The mass, spectral features, and density of the shell are consistent with other nova shells, rather than planetary nebulae or supernova remnants. The radial velocity of the shell is consistent with the systemic velocity of V1315 Aql. We believe this evidence strongly suggests that the shell originates from an earlier nova event. This is the first nova shell discovered around a nova-like and supports the theory of nova-induced cycles in mass transfer rates (hibernation theory) first proposed by Shara et al.

Dust formation in Nova Oph 2017 (TCP J17394608-2457555)

NASA Astrophysics Data System (ADS)

Joshi, Vishal; Banerjee, D. P. K.; Srivastava, Mudit

2017-06-01

Ongoing NIR observations of Nova Oph 2017 indicate the possible onset of dust formation in Nova Oph 2017. Monitoring in the JHKs bands shows a steady rise in the J-K color from around 1.4 on 5 June 2017 to 2.0 on 13 June 2017.

Model Atmospheres for Novae in Outburst: Summary of Research

NASA Technical Reports Server (NTRS)

Hauschildt, Peter H.

1999-01-01

This paper presents a final report and summary of research on Model Atmospheres for Novae in Outburst. Some of the topics include: 1) Detailed NLTE (non-local thermodynamic equilibrium) Model Atmospheres for Novae during Outburst: II. Modeling optical and ultraviolet observations of Nova LMC 1988 #1; 2) A Non-LTE Line-Blanketed Stellar Atmosphere Model of the Early B Giant epsilon CMa; 3) Spectroscopy of Low Metallicity Stellar atmospheres; 4) Infrared Colors at the Stellar/Substellar Boundary; 5) On the abundance of Lithium in T CrB; 6) Numerical Solution of the Expanding Stellar Atmosphere Problem; and 7) The NextGen Model Atmosphere grid for 3000 less than or equal to T (sub eff) less than or equal to 10000K.

Faint Object Camera observations of a globular cluster nova field

NASA Technical Reports Server (NTRS)

Margon, Bruce; Anderson, Scott F.; Downes, Ronald A.; Bohlin, Ralph C.; Jakobsen, Peter

1991-01-01

The Faint Object Camera onboard Hubble Space Telescope has obtained U and B images of the field of Nova Ophiuchi 1938 in the globular cluster M14 (NGC 6402). The candidate for the quiescent nova suggested by Shara et al. (1986) is clearly resolved into at least six separate images, probably all stellar, in a region of 0.5 arcsec. Although two of these objects are intriguing as they are somewhat ultraviolet, the actual nova counterpart remains ambiguous, as none of the images in the field has a marked UV excess. Many stars within the 1.4 arcsec (2 sigma) uncertainty of the nova outburst position are viable counterparts if only astrometric criteria are used for selection. The 11 x 11 arcsec frames easily resolve several hundred stars in modest exposures, implying that HST even in its current optical configuration will be unique for studies of very crowded fields at moderate (B = 22) limiting magnitudes.

PDL Progenitor-Mediated PDL Recovery Contributes to Orthodontic Relapse.

PubMed

Feng, L; Yang, R; Liu, D; Wang, X; Song, Y; Cao, H; He, D; Gan, Y; Kou, X; Zhou, Y

2016-08-01

Periodontal ligament (PDL) is subjected to mechanical force during physiologic activities. PDL stem /: progenitor cells are the main mesenchymal stem cells in PDL. However, how PDL progenitors participate in PDL homeostasis upon and after mechanical force is largely unknown. In this study, force-triggered orthodontic tooth movement and the following relapse were used as models to demonstrate the response of PDL progenitors and their role in PDL remodeling upon and after mechanical force. Upon orthodontic force, PDL collagen on the compression side significantly degraded, showing a broken and disorganized pattern. After force withdrawal, the degraded PDL collagen recovered during the early stage of relapse. Correspondingly, increased CD90(+) PDL progenitors with suppressed expression of type I collagen (Col-I) were observed upon orthodontic force, whereas these cells accumulated at the degradation regions and regained Col-I expression after force withdrawal during early relapse. Our results further showed that compressive force altered cell morphology and repressed collagen expression in cultured PDL progenitors, which both recovered after force withdrawal. Force withdrawal-induced recovery of collagen expression in cultured PDL progenitors could be regulated by transforming growth factor-β (TGF-β), a key molecule for tissue homeostasis and extracellular matrix remodeling. More interesting, inhibiting the regained Col-I expression in CD90(+) PDL progenitors by blocking TGF-β interrupted PDL collagen recovery and partially inhibited the early relapse. These data suggest that PDL progenitors can respond to mechanical force and may process intrinsic stability to recover to original status after force withdrawal. PDL progenitors with intrinsic stability are required for PDL recovery and consequently contribute to early orthodontic relapse, which can be regulated by TGF-β signaling. © International & American Associations for Dental Research 2016.

Optical and Near-infrared Study of Nova V2676 Oph 2012

DOE Office of Scientific and Technical Information (OSTI.GOV)

Raj, A.; Das, R. K.; Walter, F. M., E-mail: ashish.raj@iiap.res.in

2017-02-01

We present optical spectrophotometric and near-infrared (NIR) photometric observations of the nova V2676 Oph covering the period from 2012 March 29 through 2015 May 8. The optical spectra and photometry of the nova have been taken from SMARTS and Asiago; the NIR photometry was obtained from SMARTS and Mt. Abu. The spectra were dominated by strong H i lines from the Balmer series, Fe ii, N i, and [O i] lines in the initial days, typical of an Fe ii type nova. The measured FWHM for the H β and H α lines was 800–1200 km s{sup −1}. There wasmore » pronounced dust formation starting 90 days after the outburst. The J − K color was the largest among recent dust-forming novae.« less

Biology and flow cytometry of proangiogenic hematopoietic progenitors cells.

PubMed

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.

Naval Observatory Vector Astrometry Software (NOVAS) Version 3.1, Introducing a Python Edition

NASA Astrophysics Data System (ADS)

Barron, Eric G.; Kaplan, G. H.; Bangert, J.; Bartlett, J. L.; Puatua, W.; Harris, W.; Barrett, P.

2011-01-01

The Naval Observatory Vector Astrometry Software (NOVAS) is a source-code library that provides common astrometric quantities and transformations. NOVAS calculations are accurate at the sub-milliarcsecond level. The library can supply, in one or two subroutine or function calls, the instantaneous celestial position of any star or planet in a variety of coordinate systems. NOVAS also provides access to all of the building blocks that go into such computations. NOVAS Version 3.1 introduces a Python edition alongside the Fortran and C editions. The Python edition uses the computational code from the C edition and, currently, mimics the function calls of the C edition. Future versions will expand the functionality of the Python edition to harness the object-oriented nature of the Python language, and will implement the ability to handle large quantities of objects or observers using the array functionality in NumPy (a third-party scientific package for Python). NOVAS 3.1 also adds a module to transform GCRS vectors to the ITRS; the ITRS to GCRS transformation was already provided in NOVAS 3.0. The module that corrects an ITRS vector for polar motion has been modified to undo that correction upon demand. In the C edition, the ephemeris-access functions have been revised for use on 64-bit systems and for improved performance in general. NOVAS, including documentation, is available from the USNO website (http://www.usno.navy.mil/USNO/astronomical-applications/software-products/novas).

Cross Check of NOvA Oscillation Probabilities

DOE Office of Scientific and Technical Information (OSTI.GOV)

Parke, Stephen J.; Messier, Mark D.

2018-01-12

In this note we perform a cross check of the programs used by NOvA to calculate the 3-flavor oscillation probabilities with a independent program using a different method. The comparison is performed at 6 significant figures and the agreement,more » $$|\\Delta P|/P$$ is better than $$10^{-5}$$, as good as can be expected with 6 significant figures. In addition, a simple and accurate alternative method to calculate the oscillation probabilities is outlined and compared in the L/E range and matter density relevant for the NOvA experiment.« less

NOVA: A new multi-level logic simulator

NASA Technical Reports Server (NTRS)

Miles, L.; Prins, P.; Cameron, K.; Shovic, J.

1990-01-01

A new logic simulator that was developed at the NASA Space Engineering Research Center for VLSI Design was described. The simulator is multi-level, being able to simulate from the switch level through the functional model level. NOVA is currently in the Beta test phase and was used to simulate chips designed for the NASA Space Station and the Explorer missions. A new algorithm was devised to simulate bi-directional pass transistors and a preliminary version of the algorithm is presented. The usage of functional models in NOVA is also described and performance figures are presented.

Transfusion Support for ABO-Incompatible Progenitor Cell Transplantation

PubMed Central

Kopko, Patricia M.

2016-01-01

Summary ABO-incompatible transplants comprise up to 50% of allogeneic progenitor cell transplants. Major, minor and bidirectional ABO-incompatible transplants each have unique complications that can occur, including hemolysis at the time of progenitor cell infusion, hemolysis during donor engraftment, passenger lymphocyte syndrome, delayed red blood cell engraftment, and pure red cell aplasia. Appropriate transfusion support during the different phases of the allogeneic progenitor cell transplant process is an important part of ABO-incompatible transplantation. PMID:27022318

The Nova Upgrade Facility for ICF ignition and gain

NASA Astrophysics Data System (ADS)

Lowdermilk, W. H.; Campbell, E. M.; Hunt, J. T.; Murray, J. R.; Storm, E.; Tobin, M. T.; Trenholme, J. B.

1992-01-01

Research on Inertial Confinement Fusion (ICF) is motivated by its potential defense and civilian applications, including ultimately the generation of electric power. The U.S. ICF Program was reviewed recently by the National Academy of Science (NAS) and the Fusion Policy Advisory Committee (FPAC). Both committees issued final reports in 1991 which recommended that first priority in the ICF program be placed on demonstrating fusion ignition and modest gain (G less than 10). The U.S. Department of Energy and Lawrence Livermore National Laboratory (LLNL) have proposed an upgrade of the existing Nova Laser Facility at LLNL to accomplish these goals. Both the NAS and FPAC have endorsed the upgrade of Nova as the optimal path to achieving ignition and gain. Results from Nova Upgrade Experiments will be used to define requirements for driver and target technology both for future high-yield military applications, such as the Laboratory Microfusion Facility (LMF) proposed by the Department of Energy, and for high-gain energy applications leading to an ICF engineering test facility. The central role and modifications which Nova Upgrade would play in the national ICF strategy are described.

Reporter-Based Isolation of Developmental Myogenic Progenitors

PubMed Central

Kheir, Eyemen; Cusella, Gabriella; Messina, Graziella; Cossu, Giulio; Biressi, Stefano

2018-01-01

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. PMID:29674978

Nova Superposed on Yavine Corona

NASA Image and Video Library

1998-06-04

The view from NASA's Magellan spacecraft shows a 100-km-wide nova superposed on Yavine Corona. Coronae are roughly circular, volcanic features believed to form over hot upwellings of magma within the Venusian mantle. http://photojournal.jpl.nasa.gov/catalog/PIA00150

Binary Orbits as the Driver of Gamma-Ray Emission and Mass Ejection in Classical Novae

NASA Technical Reports Server (NTRS)

Chomiuk, Laura; Linford, Justin D.; Yang, Jun; O'Brien, T. J.; Paragi, Zsolt; Mioduszewski, Amy J.; Beswick, R. J.; Cheung, C. C.; Mukai, Koji; Nelson, Thomas

2014-01-01

Classical novae are the most common astrophysical thermonuclear explosions, occurring on the surfaces of white dwarf stars accreting gas from companions in binary star systems. Novae typically expel about 10 (sup -4) solar masses of material at velocities exceeding 1,000 kilometers per second.However, the mechanism of mass ejection in novae is poorly understood, and could be dominated by the impulsive flash of thermonuclear energy, prolonged optically thick winds or binary interaction with the nova envelope. Classical novae are now routinely detected at giga-electronvolt gamma-ray wavelengths, suggesting that relativistic particles are accelerated by strong shocks in the ejecta. Here we report high-resolution radio imaging of the gamma-ray-emitting nova V959 Mon. We find that its ejecta were shaped by the motion of the binary system: some gas was expelled rapidly along the poles as a wind from the white dwarf, while denser material drifted out along the equatorial plane, propelled by orbital motion..At the interface between the equatorial and polar regions, we observe synchrotron emission indicative of shocks and relativistic particle acceleration, thereby pinpointing the location of gamma-ray production. Binary shaping of the nova ejecta and associated internal shocks are expected to be widespread among novae, explaining why many novae are gamma-ray emitters.

Identifying the progenitors of present-day early-type galaxies in observational surveys: correcting `progenitor bias' using the Horizon-AGN simulation

NASA Astrophysics Data System (ADS)

Martin, G.; Kaviraj, S.; Devriendt, J. E. G.; Dubois, Y.; Pichon, C.; Laigle, C.

2018-03-01

As endpoints of the hierarchical mass-assembly process, the stellar populations of local early-type galaxies encode the assembly history of galaxies over cosmic time. We use Horizon-AGN, a cosmological hydrodynamical simulation, to study the merger histories of local early-type galaxies and track how the morphological mix of their progenitors evolves over time. We provide a framework for alleviating `progenitor bias' - the bias that occurs if one uses only early-type galaxies to study the progenitor population. Early types attain their final morphology at relatively early epochs - by z ˜ 1, around 60 per cent of today's early types have had their last significant merger. At all redshifts, the majority of mergers have one late-type progenitor, with late-late mergers dominating at z > 1.5 and early-early mergers becoming significant only at z < 0.5. Progenitor bias is severe at all but the lowest redshifts - e.g. at z ˜ 0.6, less than 50 per cent of the stellar mass in today's early types is actually in progenitors with early-type morphology, while, at z ˜ 2, studying only early types misses almost all (80 per cent) of the stellar mass that eventually ends up in local early-type systems. At high redshift, almost all massive late-type galaxies, regardless of their local environment or star formation rate, are progenitors of local early-type galaxies, as are lower mass (M⋆ < 1010.5 M_{⊙}) late-types as long as they reside in high-density environments. In this new era of large observational surveys (e.g. LSST, JWST), this study provides a framework for studying how today's early-type galaxies have been built up over cosmic time.

SALT high-resolution spectroscopy of nova PNV J15384000-4744500

NASA Astrophysics Data System (ADS)

Aydi, E.; Buckley, D. A. H.; Mohamed, S.; Whitelock, P. A.

2018-06-01

We report on high-resolution spectroscopy of PNV J15384000-4744500 which was reported as a possible nova by Rob Kaufman (Bright, Victoria, Australia; CBAT follow-up: http://www.cbat.eps.harvard.edu/unconf/followups/J15384000-4744500.html) and confirmed as a classical nova by F. Walter (ATel #11681).

The Potential of NovaNET Communications for Education and Instruction.

ERIC Educational Resources Information Center

Steinberg, Esther R.

Intended to suggest ways of implementing the potential of NovaNet beyond its current applications, this report begins with an overview of current educational applications of telecommunications systems. It is noted that NovaNET is not only a successful computer system for presenting instructional courseware, but that it also supports…

15 CFR 904.102 - Procedures upon receipt of a NOVA.

Code of Federal Regulations, 2010 CFR

2010-01-01

... (Continued) NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE GENERAL REGULATIONS CIVIL PROCEDURES Civil Penalties § 904.102 Procedures upon receipt of a NOVA. (a) The respondent has 30 days from... 15 Commerce and Foreign Trade 3 2010-01-01 2010-01-01 false Procedures upon receipt of a NOVA. 904...

15 CFR 904.102 - Procedures upon receipt of a NOVA.

Code of Federal Regulations, 2011 CFR

2011-01-01

... (Continued) NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE GENERAL REGULATIONS CIVIL PROCEDURES Civil Penalties § 904.102 Procedures upon receipt of a NOVA. (a) The respondent has 30 days from... 15 Commerce and Foreign Trade 3 2011-01-01 2011-01-01 false Procedures upon receipt of a NOVA. 904...

A Search for Novae in the M31 Globular Cluster System

NASA Astrophysics Data System (ADS)

Tomaney, Austin; Crotts, Arlin; Shafter, Allen

1992-12-01

Roughly 10% of all low mass X-ray binaries (LMXB's, neutron star - low mass sequence close binaries) are found in Galactic globular clusters (GC's) implying an enhancement per unit mass of roughly three orders of magnitude of these objects inside GC's compared with the field. Fabian, Pringle and Rees (1975) suggested that these lcose binary systems may be formed via tidal capture in the dense cluster cores. Similar arguments are likely to apply to nova systems which are cataclysmic variables (CV's) consisting of a close binary white dwarf - low mass main sequence star. Supporting arguments include the discovery over the past century of two novae in Galactic GC's, and the existence of low luminosity X-ray sources in GC's (Hertz and Grindlay 1983). In addition, surveys for novae in M31 indicate that the specfic density of novae in its bulge is an order of magnitude higher than its disk and it has been argued by Ciardullo et al. (1987) that novae in the bulge of M31 have been spawned inside GC's and subsequently ejected into the field. We present the results of a search (during 1988 and 1989) of over 200 M31 GC's using a fibre multi-object spectrograph to detect Hα emission, a signature of a potential nova eruptions. No eruptions were detected over an effective survey time of one year for the entire known M31 GC system. Although the lower mass of white dwarfs compared with neutron stars implies their effective capture cross section is smaller, we argue that since novae occur much more frequently on high mass white dwarfs this survey provides a sensitive test to the number of high mass CV's in GC's and their enhancement is unlikely to be as high as LMXB's.

Results from the NOvA Experiment

NASA Astrophysics Data System (ADS)

Smith, Erica

The NOvA experiment is a long-baseline accelerator-based neutrino oscillation experiment. It uses the upgraded NuMI beam from Fermilab to measure electron-neutrino appearance and muon-neutrino disappearance between the Near Detector, located at Fermilab, and the Far Detector, located at Ash River, Minnesota. The NuMI beam has recently reached and surpassed the 700 kW power benchmark. NOvA’s primary physics goals include precision measurements of oscillation parameters, such as 𝜃23 and the atmospheric mass-squared splitting, along with probes of the mass hierarchy and of the CP violating phase. This talk will present the latest NOvA results, based on a neutrino beam exposure equivalent to 6.05 × 1020 protons-on-target.

First Neutrino Oscillation Results from the NOvA experiment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sachdev, Kanika

2016-11-29

NOvA is a long-baseline neutrino oscillation experiment on the NuMI muon neutrino beam at Fermilab. It consists of two functionally identical, nearly fully-active liquid-scintillator tracking calorimeters. The Near Detector (ND) at Fermilab is used to study the neutrino beam spectrum and composition before oscillations occur. The Far Detector in northern Minnesota, 810 km away, observes the oscillated beam and is used to extract the oscillation parameters. NOvA is designed to observe oscillations in two channels: disappearance channel ( ν μ → ν μ ) and ν e appearance channel ( ν μ → ν e ). This paper reports themore » measurements of both these channels based on the first NOvA data taken from February 16, 2014 till May 15, 2015« less

Life after eruption VII: A search for stunted outbursts in thirteen post-novae

NASA Astrophysics Data System (ADS)

Vogt, N.; Tappert, C.; Puebla, E. C.; Fuentes-Morales, I.; Ederoclite, A.; Schmidtobreick, L.

2018-06-01

The results of a photometric campaign during three observing seasons 2013 - 2016 at the Cerro Tololo International Observatory (1.3-meter SMARTS telescope) are presented. The aim was to detect "stunted" outbursts in a total of 13 post novae more than 38 years after maximum brightness registered in their nova eruption light curve. In six of the targets (V728 Sco 1862, V1059 Sgr 1898, V849 Oph 1919, V363 Sgr 1927, HS Pup 1963 and V2572 Sgr 1969) we detected such dwarf nova-like mini-outbursts, with mean amplitudes between 0.2m and 2.2m and typical FWHM of 4-11 days, repeating every 9-32 days. The most regular outburst behavior is present in the eclipsing post-nova V728 Sco. In our sample there is no significant correlation between the occurrences of stunted outbursts and the time passed since the nova eruption maximum. However, considering all 15 post-novae that have been reported to show stunted outbursts we found a possible tendency for increasing outburst amplitudes at the rate 0.52 ± 0.23 mag/century during 30 - 250 years after nova eruption. This tendency is still doubtful due to the low number of cases available. If the stunted outburst activity is related to the mass transfer rate \\dot{M}, we conclude that the secular decrease of \\dot{M} predicted by the hibernation scenario must be at much longer time scales than ˜200 years actually covered with post-nova observations.

NOvA: Exploring Neutrino Mysteries

ScienceCinema

Vahle, Tricia; Messier, Mark

2018-01-16

Neutrinos are a mystery to physicists. They exist in three different flavors and mass states and may be able to give hints about the origins of the matter-dominated universe. A new long-baseline experiment led by Fermilab called NOvA may provide some answers.

NOvA: Exploring Neutrino Mysteries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vahle, Tricia; Messier, Mark

2012-09-06

Neutrinos are a mystery to physicists. They exist in three different flavors and mass states and may be able to give hints about the origins of the matter-dominated universe. A new long-baseline experiment led by Fermilab called NOvA may provide some answers.

On the Accretion Rates of SW Sextantis Nova-like Variables

NASA Astrophysics Data System (ADS)

Ballouz, Ronald-Louis; Sion, Edward M.

2009-06-01

We present accretion rates for selected samples of nova-like variables having IUE archival spectra and distances uniformly determined using an infrared method by Knigge. A comparison with accretion rates derived independently with a multiparametric optimization modeling approach by Puebla et al. is carried out. The accretion rates of SW Sextantis nova-like systems are compared with the accretion rates of non-SW Sextantis systems in the Puebla et al. sample and in our sample, which was selected in the orbital period range of three to four and a half hours, with all systems having distances using the method of Knigge. Based upon the two independent modeling approaches, we find no significant difference between the accretion rates of SW Sextantis systems and non-SW Sextantis nova-like systems insofar as optically thick disk models are appropriate. We find little evidence to suggest that the SW Sex stars have higher accretion rates than other nova-like cataclysmic variables (CVs) above the period gap within the same range of orbital periods.

Chandra Discovers Eruption and Pulsation in Nova Outburst

NASA Astrophysics Data System (ADS)

2001-09-01

NASA's Chandra X-ray Observatory has discovered a giant outburst of X-rays and unusual cyclical pulsing from a white dwarf star that is closely orbiting another star -- the first time either of these phenomena has been seen in X-rays. The observations are helping scientists better understand the thermonuclear explosions that occur in certain binary star systems. The observations of Nova Aquilae were reported today at the "Two Years of Science with Chandra" symposium by an international team led by Sumner Starrfield of Arizona State University. "We found two important results in our Chandra observations. The first was an underlying pulsation every 40 minutes in the X-ray brightness, which we believe comes from the cyclical expansion and contraction of the outer layers of the white dwarf," said Starrfield. "The other result was an enormous flare of X-rays that lasted for 15 minutes. Nothing like this has been seen before from a nova, and we don't know how to explain it." Novas occur on a white dwarf (a star which used up all its nuclear fuel and shrank to roughly the size of the Earth) that is orbiting a normal size star. Strong gravity tides drag hydrogen gas off the normal star and onto the white dwarf, where it can take more than 100,000 years for enough hydrogen to accumulate to ignite nuclear fusion reactions. Gradually, these reactions intensify until a cosmic-sized hydrogen bomb blast results. The outer layers of the white dwarf are then blown away, producing a nova outburst that can be observed for a period of months to years as the material expands into space. "Chandra has allowed us to see deep into the gases ejected by this giant explosion and extract unparalleled information on the evolution of the white dwarf whose surface is exploding," said Jeremy Drake of the Harvard-Smithsonian Center for Astrophysics. The brightening of Nova Aquilae was first detected by optical astronomers in December 1999. "Although this star is at a distance of more than 6

Archival Investigation of Outburst Sites and Progenitors of Extragalactic Intermediate-Luminosity Mid-IR Transients

NASA Astrophysics Data System (ADS)

Bond, Howard

2017-08-01

Our team is using Spitzer in a long-term search for extragalactic mid-infrared (MIR) variable stars and transients-the SPIRITS project (SPitzer InfraRed Intensive Transients Survey). In this first exploration of luminous astrophysical transients in the infrared, we have discovered a puzzling new class. We call them SPRITEs: eSPecially Red Intermediate-luminosity Transient Events. They have maximum MIR luminosities between supernovae and classical novae, but are not detected in the optical to deep limits. To date, we have discovered more than 50 SPRITEs in galaxies out to 17 Mpc. In this Archival Research proposal, we request support in order to investigate the pre-eruption sites in HST images of some 3 dozen SPRITEs discovered to date, and an additional 2 dozen that we are likely to find until the end of Spitzer observing in late 2018. Our aims are (1) characterize the pre-outburst environments at HST resolution in the visible and near-IR, to understand the stellar populations, stellar ages and masses, and interstellar medium at the outburst sites; (2) search for progenitors; (3) help prepare the way for a better understanding of the nature of extragalactic IR transients that will be investigated by JWST.

Non-LTE model atmosphere analysis of Nova Cygni 1992

NASA Technical Reports Server (NTRS)

Hauschildt, P. H.; Starrfield, S.; Austin, S.; Wagner, R. M.; Shore, S. N.; Sonneborn, G.

1994-01-01

We use spherically symmetric non-local thermodynamic equilibrium (non-LTE), line-blanketed, expanding model atmospheres to analyze the International Ultraviolet Explorer (IUE) and optical spectra of Nova Cygni 1992 during the early phases of its outburst. We find that the first IUE spectrum obtained just after discovery on 1992 February 20, is best reproduced by a model atmosphere with a steep density gradient and homologous expansion, whereas the IUE and optical spectra obtained on February 24 show an extended, optically thick, wind structure. Therefore, we distinguish two phases of the early evolution of the nova photosphere: the initial, rapid, 'fireball' phase and the subsequent, much longer, optically thick 'wind' phase. The importance of line-blanketing in nova spectra is demonstrated. Our preliminary abundance analysis implies that hydrogen is depeleted in the ejecta, corresponding to abundance enhancements of Fe by a factor of approximately 2 and of CNO by more than a factor of 10 when compared to solar abundances. The synthetic spectra reproduce both the observed pseudo-continua as well as most of the observed features from the UV to the optical spectral range and demonstrate the importance of obtaining nearly simultaneous UV and optical spectra for performing accurate analyses of expanding stellar atmospheres (for both novae and supernovae).

Nova Ophiuchus 2017 as a Probe of 13C Nucleosynthesis and Carbon Monoxide Formation and Destruction in Classical Novae

NASA Astrophysics Data System (ADS)

Joshi, Vishal; Banerjee, D. P. K.; Srivastava, Mudit

2017-12-01

We present a series of near-infrared spectra of Nova Ophiuchus 2017 in the K band that record the evolution of the first overtone CO emission in unprecedented detail. Starting from 11.7 days after maximum, when CO is first detected at great strength, the spectra track the CO emission to +25.6 days by which time it is found to have rapidly declined in strength by almost a factor of ∼35. The cause for the rapid destruction of CO is examined in the framework of different mechanisms for CO destruction, namely, an increase in photoionizating flux, chemical pathways of destruction, or destruction by energetic nonthermal particles created in shocks. From LTE modeling of the CO emission, the 12C/13C ratio is determined to be 1.6 ± 0.3. This is consistent with the expected value of this parameter from nucleosynthesis theory for a nova eruption occuring on a low mass (∼ 0.6 {M}ȯ ) carbon–oxygen core white dwarf. The present 12C/13C estimate constitutes one of the most secure estimates of this ratio in a classical nova.

Strategies to reverse endothelial progenitor cell dysfunction in diabetes.

PubMed

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.

Constraining Core-collapse Supernova Theory Predictions with 400 Progenitor Masses

NASA Astrophysics Data System (ADS)

Murphy, Jeremiah

2017-08-01

A new era is emerging in which we will have hundreds of progenitor masses for supernovae (SNe) and supernova remnants (SNRs); we propose to develop the statistical and theoretical tools needed to interpret this data. Two of the fundamental predictions of stellar evolution theory are that stars more massive than about 8 solar masses will explode and that some of these stars will not explode and form black holes. These statements are clear and simple, yet constraining them with observations has remained elusive until recently. For many years, the rate of progenitor discovery was steady but slow; each progenitor discovery required rare serendipitous pre-cursor imaging. With this steady drip of direct imaging, the number of progenitor masses numbered no more than 20. Recently, we developed a technique that increased the number of progenitor masses by a factor of 10 or more. In this new technique, we use HST photometry to age-date the stellar populations surrounding SNRs. From this age, we derive a progenitor mass for each SNR. We currently have progenitor masses for 115 SNRs in M31 and M33, soon we will have 300 more from M83, and there are hundreds more SNRs that could be analyzed in other nearby galaxies. To prepare for this watershed, we propose to develop the Bayesian framework needed to properly infer the progenitor mass distribution. This work will culminate in a direct constraint on the predictions of core-collapse supernova theory.

The Stony Brook/SMARTS Atlas of (mostly) Southern Novae

NASA Astrophysics Data System (ADS)

Walter, F. M.

2014-12-01

The Stony Brook/SMARTS Atlas of (mostly) Southern Novae is an on-line compendium of data on 69 novae, mostly in the southern hemisphere, observed since 2003 April. The data consist of low resolution spectra (400< R <4000) and optical and near-IR photometry obtained with the SMARTS telescopes. I shall describe the atlas and the data, and then present some examples of the data analyzes being undertaken with this synoptic data set.

Premyogenic progenitors derived from human pluripotent stem cells expand in floating culture and differentiate into transplantable myogenic progenitors.

PubMed

Sakai-Takemura, Fusako; Narita, Asako; Masuda, Satoru; Wakamatsu, Toshifumi; Watanabe, Nobuharu; Nishiyama, Takashi; Nogami, Ken'ichiro; Blanc, Matthias; Takeda, Shin'ichi; Miyagoe-Suzuki, Yuko

2018-04-26

Human induced pluripotent stem cells (hiPSCs) are a potential source for cell therapy of Duchenne muscular dystrophy. To reliably obtain skeletal muscle progenitors from hiPSCs, we treated hiPS cells with a Wnt activator, CHIR-99021 and a BMP receptor inhibitor, LDN-193189, and then induced skeletal muscle cells using a previously reported sphere-based culture. This protocol greatly improved sphere formation efficiency and stably induced the differentiation of myogenic cells from hiPS cells generated from both healthy donors and a patient with congenital myasthenic syndrome. hiPSC-derived myogenic progenitors were enriched in the CD57(-) CD108(-) CD271(+) ERBB3(+) cell fraction, and their differentiation was greatly promoted by TGF-β inhibitors. TGF-β inhibitors down-regulated the NFIX transcription factor, and NFIX short hairpin RNA (shRNA) improved the differentiation of iPS cell-derived myogenic progenitors. These results suggest that NFIX inhibited differentiation of myogenic progenitors. hiPSC-derived myogenic cells differentiated into myofibers in muscles of NSG-mdx 4Cv mice after direct transplantation. Our results indicate that our new muscle induction protocol is useful for cell therapy of muscular dystrophies.

NOVA Fall 1998 Teacher's Guide.

ERIC Educational Resources Information Center

Colombo, Luann

This teacher's guide is designed to accompany the PBS television program "NOVA." Six science activities correspond to: (1) "Lost at Sea: The Search for Longitude,, which researches and charts the shortest course to circumnavigate the globe; (2) "Chasing El Nino," which formulates a question and designs an experiment to…

An Emerging Wine Region in Nova Scotia, Canada: Terroir Trials and Tribulations

NASA Astrophysics Data System (ADS)

Cameron, B. I.; Ketter, B. S.; Karakis, S.

2012-12-01

Nova Scotia, strategically located on Canada's east coast, is an emerging wine region, whose distinctive wines are garnering international acclaim. Nova Scotia has a long and rich tradition of growing grapes for wine dating back as far as 1611. Nova Scotia's mesoclimates, glacial soils, and proximity to the Atlantic Ocean form a complex alliance to create a unique and expressive terroir. Tidal Bay is a new appellation wine for Nova Scotia stylistically defined as a fresh, crisp and high-acid blend of white grapes. There are four main wine-growing regions in Nova Scotia, all influenced by the warming effects of the Bay of Fundy and Atlantic Ocean: Malagash Peninsula, Annapolis Valley, Bear River Valley and the South Shore. Nova Scotia currently has 14 producing wineries with many more in the development stage. Nova Scotia grape growers not only have had success developing mature and consistent hybrids, but in recent years several vinifera have flourished in this cool climate area. The white hybrids include L'Acadie Blanc, New York Muscat, Seyval Blanc, and Vidal Blanc. The white vinifera include chardonnay, riesling, pinot gris, and sauvignon blanc. Red hybrids are Baco Noir, Leon Millet, Lucie Kuhlmann, and Marechal Foch, whereas the only red vinifera is pinot noir. Nova Scotia has nearly perfect climatic conditions for making world class icewines and sparkling wines. A preliminary GIS analysis of climate, topographic, geology and soil data helps to define Nova Scotia's terroir. Annual precipiatation varies from 10 to 21.6 cm/year with a vast majority of the wineries located in regions with the lowest rainfall. Daily average temperature ranges from 5.5 to 7.5°C, degree growing days above 5°C from 1382 to 1991, and mean August temperature from 15.6 to 19.3 °C. Wineries cluster in the warmest regions based on these temperature measures to assist grape ripening. Soils in these diverse wine regions can range from silty, sandy and clay loams to more gravel-rich sandy

ASASSN-18gb: Discovery of A Probable Nova in NGC 3109

NASA Astrophysics Data System (ADS)

Brimacombe, J.; Vallely, P.; Stanek, K. Z.; Kochanek, C. S.; Brown, J. S.; Shields, J.; Thompson, T. A.; Shappee, B. J.; Holoien, T. W.-S.; Prieto, J. L.; Bersier, D.; Dong, Subo; Bose, S.; Chen, Ping; Stritzinger, M.; Holmbo, S.

2018-03-01

During the ongoing All Sky Automated Survey for SuperNovae (ASAS-SN, Shappee et al. 2014), using data from the quadruple 14-cm "Payne-Gaposchkin" telescope in Sutherland, South Africa, we discovered a new transient source, most likely a nova, in the Local Group galaxy NGC 3109.

Liverpool Telescope Spectroscopy of the Nova Eruption from V392 Persei

NASA Astrophysics Data System (ADS)

Darnley, M. J.; Copperwheat, C. M.; Harvey, E. J.; Healy, M. W.

2018-05-01

Here we report Liverpool Telescope (LT; Steele et al. 2004) spectroscopy of the recent nova eruption (ATel #11588) from the known dwarf nova system V392 Per. A Fermi & gamma;-ray detection of the eruption has also been reported (ATel #11590) along with additional photometry (ATel #11594).

Measurement of Reactions on 30P for Nova Nucleosynthesis

NASA Astrophysics Data System (ADS)

Ma, Z.; Guidry, M. W.; Hix, W. R.; Smith, M. S.

2003-05-01

Replace these paragraphs with your abstract. We encourage you to include a sentence acknowledging your funding agency. In a recent study the 30P(p,gamma)31S rate played a crucial role in the synthesis of heavier nuclear species, from Si to Ca, in nova outbursts on ONe White Dwarfs [1]. The adopted rate of this reaction, based on a Hauser-Feshbach calculation [2], has a large uncertainty and could be as much as a factor of 100 too high or too low [3]. In their study, Jose et al.[1] varied the 30P(p,gamma)31S reaction rate within this uncertainty and found that, when rate is reduced by a factor of 100, the synthesis of elements above Si is lowered by a factor 10 with respect to the values found with the nominal rate. This has important consequences for nova nucleosynthesis, as overproduction of isotopes in the Si to Ca mass region has been observed in the ejecta from some nova explosions (e.g.,[4,5]). While generally valid at higher temperatures, Hauser-Feshbach calculations of the rates at nova temperatures can have large uncertainties. At these temperatures, the rate is more likely dominated by a few individual nuclear resonances. At present there are about 10 31S resonances known above the 30P + p threshold that may contribute to the 30P(p,gamma)31S reaction rate at nova temperatures. The excitation energies of these levels are known but spins and parities (for all but two) are not. We plan to measure the 30P(p,p)30P and 30P(p,gamma)31S reactions at HRIBF to better determine this reaction rate. A detailed description of the experiments will be given. We are also conducting a new nova nucleosynthesis simulation over multiple spatial zones of the exploding envelope to investigate the influence of the 30P(p,gamma)31S reaction rate on nova nucleosynthesis. The results of these calculations will be discussed. 1. Jose , J., Coc, A., Hernanz, M., Astrophys. J., 560, 897(2001). 2. Thielemann, F.-K et al., 1987, Advances in Nuclear Astrophysics, ed. E. Vangioni-Flam ( Gif

Muscle: a source of progenitor cells for bone fracture healing.

PubMed

Henrotin, Yves

2011-12-22

Bone repair failure is a major complication of open fracture, leading to non-union of broken bone extremities and movement at the fracture site. This results in a serious disability for patients. The role played by the periosteum and bone marrow progenitors in bone repair is now well documented. In contrast, limited information is available on the role played by myogenic progenitor cells in bone repair. In a recent article published in BMC Musculoskeletal Disorders, Liu et al. compared the presence of myogenic progenitor (MyoD lineage cells) in closed and open fractures. They showed that myogenic progenitors are present in open, but not closed fractures, suggesting that muscle satellite cells may colonize the fracture site in the absence of intact periosteum. Interestingly, these progenitors sequentially expressed a chondrogenic and, thereafter, an osteoblastic phenotype, suggestive of a functional role in the repair process. This finding opens up new perspectives for the research of orthopedic surgical methods, which could maximize myogenic progenitor access and mobilization to augment bone repair. Please see related article: http://www.biomedcentral.com/1471-2474/12/288.

Spectroscopic confirmation and photometry of the first reported nova in NGC 147

NASA Astrophysics Data System (ADS)

Fabrika, S.; Vinokurov, A.; Solovyeva, Yu.; Valeev, A. F.; Makarov, D. I.; Hornoch, K.; Kucakova, H.; Korotkiy, S.; Henze, M.; Shafter, A. W.

2017-12-01

We report optical spectroscopic confirmation of the recent nova TCP J00333837+4836022 in the Local Group dwarf spheroidal galaxy NGC 147. The nova was discovered 2017 Dec. 22.4056 UT by K. Itagaki (Yamagata, Japan).

[Pedagogical Professional Development of Medical Teachers: The Experience of NOVA Medical School / Universidade Nova de Lisboa].

PubMed

Marques, Joana; Rosado-Pinto, Patrícia

2017-03-31

To be a college teacher requires a permanent effort in developing specific competencies, namely in the pedagogical domain. This paper aims both to describe the pedagogical professional development program offered by the Medical Education Office of NOVA Medical School of Universidade Nova de Lisboa and to analyse its role in the enhancement of reflection around curriculum and teaching practice. Description of the pedagogical programme offered between 2010 and 2016. We focused the analysis on different kinds of data - opinions of the participants in the training programme (questionnaire before and after the training); pedagogical products elaborated by the participants in the programme - design of lessons, modules or curricular units; questionnaire sent in 2016 to NOVA Medical School teachers responsible for the curricular units, about the contribution of their disciplines to the accomplishment of the core learning outcomes of the NOVA Medical School medical graduates. The pedagogical training needs identified by the teachers focused mainly on improving practice, critically analysing the curriculum and sharing experiences. Globally the training programme was deeply appreciated and considered very good by 97% of the participants. The lesson plans delivered showed that the teachers were able to integrate and apply the concepts developed during the training. The answers from the 46 faculty responsible for the curricular units (the majority of them had attended the Medical Education Office training programme) highlighted their capacity to critically approach content and pedagogical strategies within their disciplines as well as their contribution to the main goals of the medical curriculum. The results underlined the importance of a pedagogical training focused on the critical analysis of curriculum and pedagogical practice. On the other hand, the pedagogical products analyzed revealed great mastery by teachers of the content and pedagogical strategies present in the

Polarimetry and spectroscopy of the "oxygen flaring" DQ Herculis-like nova: V5668 Sagittarii (2015)

NASA Astrophysics Data System (ADS)

Harvey, E. J.; Redman, M. P.; Darnley, M. J.; Williams, S. C.; Berdyugin, A.; Piirola, V. E.; Fitzgerald, K. P.; O'Connor, E. G. P.

2018-03-01

Context. Classical novae are eruptions on the surface of a white dwarf in a binary system. The material ejected from the white dwarf surface generally forms an axisymmetric shell of gas and dust around the system. The three-dimensional structure of these shells is difficult to untangle when viewed on the plane of the sky. In this work a geometrical model is developed to explain new observations of the 2015 nova V5668 Sagittarii. Aim. We aim to better understand the early evolution of classical nova shells in the context of the relationship between polarisation, photometry, and spectroscopy in the optical regime. To understand the ionisation structure in terms of the nova shell morphology and estimate the emission distribution directly following the light curve's dust-dip. Methods: High-cadence optical polarimetry and spectroscopy observations of a nova are presented. The ejecta is modelled in terms of morpho-kinematics and photoionisation structure. Results: Initially observational results are presented, including broadband polarimetry and spectroscopy of V5668 Sgr nova during eruption. Variability over these observations provides clues towards the evolving structure of the nova shell. The position angle of the shell is derived from polarimetry, which is attributed to scattering from small dust grains. Shocks in the nova outflow are suggested in the photometry and the effect of these on the nova shell are illustrated with various physical diagnostics. Changes in density and temperature as the super soft source phase of the nova began are discussed. Gas densities are found to be of the order of 109 cm-3 for the nova in its auroral phase. The blackbody temperature of the central stellar system is estimated to be around 2.2 × 105 K at times coincident with the super soft source turn-on. It was found that the blend around 4640 Å commonly called "nitrogen flaring" is more naturally explained as flaring of the O II multiplet (V1) from 4638-4696 Å, i.e. "oxygen flaring

Heterogeneity and Fgf dependence of adult neural progenitors in the zebrafish telencephalon.

PubMed

Ganz, Julia; Kaslin, Jan; Hochmann, Sarah; Freudenreich, Dorian; Brand, Michael

2010-08-15

Adult telencephalic neurogenesis is a conserved trait of all vertebrates studied. It has been investigated in detail in rodents, but very little is known about the composition of neurogenic niches and the cellular nature of progenitors in nonmammalian vertebrates. To understand the components of the progenitor zones in the adult zebrafish telencephalon and the link between glial characteristics and progenitor state, we examined whether canonical glial markers are colocalized with proliferation markers. In the adult zebrafish telencephalon, we identify heterogeneous progenitors that reside in two distinct glial domains. We find that the glial composition of the progenitor zone is linked to its proliferative behavior. Analyzing both fast-cycling proliferating cells as well as slowly cycling progenitors, we find four distinct progenitor types characterized by differential expression of glial markers. Importantly, a significant proportion of progenitors do not display typical radial glia characteristics. By blocking or activating Fgf signaling by misexpression of a dominant negative Fgf-receptor 1 or Fgf8a, respectively, we find that ventral and dorsal progenitors in the telencephalon also differ in their requirement for Fgf signaling. Together with data on the expression of Fgf signaling components in the ventricular zone of the telencephalon, this suggests that Fgf signaling directly regulates proliferation of specific subsets of adult telencephalic progenitors in vivo. Taken together our results show that adult neural progenitor cells are heterogeneous with their respect to distribution into two distinct glial domains and their dependence upon Fgf signaling as a proliferative cue in the zebrafish telencephalon.

Nova Centauri 2013 = PNV J13544700-5909080

NASA Astrophysics Data System (ADS)

Waagen, Elizabeth O.

2013-12-01

Announces the discovery of V1369 Cen = Nova Cen 2013 = PNV J13544700-5909080 by John Seach (Chatsworth Island, NSW, Australia) at unfiltered magnitude 5.5 on 2013 December 02.692 UT. Low-resolution spectra obtained by Locke on Dec. 03.3776 UT and by Kaufman on Dec. 03.621 UT show strong Ha and Hb emission lines, indicating the object is a nova. Announced on IAU CBAT Central Bureau Electronic Telegram 3732 (Daniel W. E. Green, ed.). Finder charts with sequences may be created using the AAVSO Variable Star Plotter (http://www.aavso.org/vsp). Observations should be submitted to the AAVSO International Database. See full Alert Notice for more details and observations.

Far Ultraviolet Spectroscopy of Seven Nova-Like Variables

NASA Astrophysics Data System (ADS)

Mizusawa, Trisha; Merritt, Jason; Ballouz, Ronald-Louis; Bonaro, Michael; Foran, Sean; Plumberg, Christopher; Stewart, Heather; Wiley, Trayer; Sion, Edward M.

2010-03-01

We present the results of a multicomponent synthetic spectral analysis of the archival far ultraviolet spectra of several key nova-like variables including members of the SW Sex, RW Tri, UX UMa, and VY Scl subclasses: KR Aur, RW Tri, V825 Her, V795 Her, BP Lyn, V425 Cas, and HL Aqr. Accretion rates as well as the possible flux contribution of the accreting white dwarf are included in our analysis. Except for RW Tri, which has a reliable trigonometric parallax, we computed the distances to the nova-like systems using the method of Knigge. Our analysis of seven archival IUE spectra of RW Tri at its parallax distance of 341 pc consistently indicates a low mass (˜0.4 M⊙) white dwarf and an average accretion rate, . For KR Aur, we estimate that the white dwarf has Teff = 29,000 ± 2000 K, log g = 8.4, and contributes 18% of the far-UV flux, while an accretion disk with accretion rate at an inclination of 41° contributes the remainder. We find that an accretion disk dominates the far-UV spectrum of V425 Cas but a white dwarf contributes nonnegligibly with approximately 18% of the far-UV flux. For the two high state nova-likes, HL Aqr and V825 Her, their accretion disks totally dominate with and 3 × 10-9 M⊙ yr-1, respectively. For BP Lyn we find while for V795 Her, we find an accretion rate of . We discuss the implications of our results for the evolutionary status of nova-like variables.

3D Hydrodynamic Simulation of Classical Novae Explosions

NASA Astrophysics Data System (ADS)

Kendrick, Coleman J.

2015-01-01

This project investigates the formation and lifecycle of classical novae and determines how parameters such as: white dwarf mass, star mass and separation affect the evolution of the rotating binary system. These parameters affect the accretion rate, frequency of the nova explosions and light curves. Each particle in the simulation represents a volume of hydrogen gas and are initialized randomly in the outer shell of the companion star. The forces on each particle include: gravity, centrifugal, coriolis, friction, and Langevin. The friction and Langevin forces are used to model the viscosity and internal pressure of the gas. A velocity Verlet method with a one second time step is used to compute velocities and positions of the particles. A new particle recycling method was developed which was critical for computing an accurate and stable accretion rate and keeping the particle count reasonable. I used C++ and OpenCL to create my simulations and ran them on two Nvidia GTX580s. My simulations used up to 1 million particles and required up to 10 hours to complete. My simulation results for novae U Scorpii and DD Circinus are consistent with professional hydrodynamic simulations and observed experimental data (light curves and outburst frequencies). When the white dwarf mass is increased, the time between explosions decreases dramatically. My model was used to make the first prediction for the next outburst of nova DD Circinus. My simulations also show that the companion star blocks the expanding gas shell leading to an asymmetrical expanding shell.

Diabetes Care Program of Nova Scotia: Celebrating 25 Years of Improving Diabetes Care in Nova Scotia.

PubMed

Payne, Jennifer I; Dunbar, Margaret J; Talbot, Pamela; Tan, Meng H

2018-06-01

The Diabetes Care Program of Nova Scotia (DCPNS)'s mission is "to improve, through leadership and partnerships, the health of Nova Scotians living with, affected by, or at risk of developing diabetes." Working together with local, provincial and national partners, the DCPNS has improved and standardized diabetes care in Nova Scotia over the past 25 years by developing and deploying a resourceful and collaborative program model. This article describes the model and highlights its key achievements. With balanced representation from frontline providers through to senior decision makers in health care, the DCPNS works across the age continuum, supporting the implementation of national clinical practice guidelines and, when necessary, developing provincial guidelines to meet local needs. The development and implementation of standardized documentation and data collection tools in all diabetes centres created a robust opportunity for the development and expansion of the DCPNS registry. This registry provides useful clinical and statistical information to staff, providers within the circle of care, management and senior leadership. Data are used to support individual care, program planning, quality improvement and business planning at both the local and the provincial levels. The DCPNS supports the sharing of new knowledge and advances through continuous education for providers. The DCPNS's ability to engage diabetes educators and key physician champions has ensured balanced perspectives in the creation of tools and resources that can be effective in real-world practice. The DCPNS has evolved to become an illustrative example of the chronic care model in action. Copyright © 2017 Diabetes Canada. Published by Elsevier Inc. All rights reserved.

BK Lyncis: the oldest old nova and a Bellwether for cataclysmic variable evolution

NASA Astrophysics Data System (ADS)

Patterson, Joseph; Uthas, Helena; Kemp, Jonathan; de Miguel, Enrique; Krajci, Thomas; Foote, Jerry; Hambsch, Franz-Josef; Campbell, Tut; Roberts, George; Cejudo, David; Dvorak, Shawn; Vanmunster, Tonny; Koff, Robert; Skillman, David; Harvey, David; Martin, Brian; Rock, John; Boyd, David; Oksanen, Arto; Morelle, Etienne; Ulowetz, Joseph; Kroes, Anthony; Sabo, Richard; Jensen, Lasse

2013-09-01

We summarize the results of a 20-yr campaign to study the light curves of BK Lyn, a nova-like star strangely located below the 2 to 3 h orbital-period gap in the family of cataclysmic variables (CVs). Two apparent superhumps dominate the nightly light curves, with periods 4.6 per cent longer, and 3.0 per cent shorter, than the orbital period. The first appears to be associated with the star's brighter states (V ˜ 14), while the second appears to be present throughout and becomes very dominant in the low state (V ˜ 15.7). It is plausible that these arise, respectively, from a prograde apsidal precession and a retrograde nodal precession of the star's accretion disc. Starting in the year 2005, the star's light curve became indistinguishable from that of a dwarf nova - in particular, that of the ER UMa subclass. No such clear transition has ever been observed in a CV before. Reviewing all the star's oddities, we speculate: (a) BK Lyn is the remnant of the probable nova on 101 December 30, and (b) it has been fading ever since, but it has taken ˜2000 yr for the accretion rate to drop sufficiently to permit dwarf-nova eruptions. If such behaviour is common, it can explain other puzzles of CV evolution. One: why the ER UMa class even exists (because all members can be remnants of recent novae). Two: why ER UMa stars and short-period nova-likes are rare (because their lifetimes, which are essentially cooling times, are short). Three: why short-period novae all decline to luminosity states far above their true quiescence (because they are just getting started in their post-nova cooling). Four: why the orbital periods, accretion rates and white dwarf temperatures of short-period CVs are somewhat too large to arise purely from the effects of gravitational radiation (because the unexpectedly long interval of enhanced post-nova brightness boosts the mean mass-transfer rate). And maybe even five: why very old, post-period-bounce CVs are hard to find (because the higher mass

Conversion of immortal liver progenitor cells into pancreatic endocrine progenitor cells by persistent expression of Pdx-1.

PubMed

Jin, Cai-Xia; Li, Wen-Lin; Xu, Fang; Geng, Zhen H; He, Zhi-Ying; Su, Juan; Tao, Xin-Rong; Ding, Xiao-Yan; Wang, Xin; Hu, Yi-Ping

2008-05-01

The conversion of expandable liver progenitor cells into pancreatic beta cells would provide a renewable cell source for diabetes cell therapy. Previously, we reported the establishment of liver epithelial progenitor cells (LEPCs). In this work, LEPCs were modified into EGFP/Pdx-1 LEPCs, cells with stable expression of both Pdx-1 and EGFP. Unlike previous work, with persistent expression of Pdx-1, EGFP/Pdx-1 LEPCs acquired the phenotype of pancreatic endocrine progenitor cells rather than giving rise to insulin-producing cells directly. EGFP/Pdx-1 LEPCs proliferated vigorously and expressed the crucial transcription factors involved in beta cell development, including Ngn3, NeuroD, Nkx2.2, Nkx6.1, Pax4, Pax6, Isl1, MafA and endogenous Pdx-1, but did not secrete insulin. When cultured in high glucose/low serum medium supplemented with cytokines, EGFP/Pdx-1 LEPCs stopped proliferating and gave rise to functional beta cells without any evidence of exocrine or other islet cell lineage differentiation. When transplanted into diabetic SCID mice, EGFP/Pdx-1 LEPCs ameliorated hyperglycemia by secreting insulin in a glucose regulated manner. Considering the limited availability of beta cells, we propose that our experiments will provide a framework for utilizing the immortal liver progenitor cells as a renewable cell source for the generation of functional pancreatic beta cells.

The direct identification of core-collapse supernova progenitors.

PubMed

Van Dyk, Schuyler D

2017-10-28

To place core-collapse supernovae (SNe) in context with the evolution of massive stars, it is necessary to determine their stellar origins. I describe the direct identification of SN progenitors in existing pre-explosion images, particularly those obtained through serendipitous imaging of nearby galaxies by the Hubble Space Telescope I comment on specific cases representing the various core-collapse SN types. Establishing the astrometric coincidence of a SN with its putative progenitor is relatively straightforward. One merely needs a comparably high-resolution image of the SN itself and its stellar environment to perform this matching. The interpretation of these results, though, is far more complicated and fraught with larger uncertainties, including assumptions of the distance to and the extinction of the SN, as well as the metallicity of the SN environment. Furthermore, existing theoretical stellar evolutionary tracks exhibit significant variations one from the next. Nonetheless, it appears fairly certain that Type II-P (plateau) SNe arise from massive stars in the red supergiant phase. Many of the known cases are associated with subluminous Type II-P events. The progenitors of Type II-L (linear) SNe are less established. Among the stripped-envelope SNe, there are now a number of examples of cool, but not red, supergiants (presumably in binaries) as Type IIb progenitors. We appear now finally to have an identified progenitor of a Type Ib SN, but no known example yet for a Type Ic. The connection has been made between some Type IIn SNe and progenitor stars in a luminous blue variable phase, but that link is still thin, based on direct identifications. Finally, I also describe the need to revisit the SN site, long after the SN has faded, to confirm the progenitor identification through the star's disappearance and potentially to detect a putative binary companion that may have survived the explosion.This article is part of the themed issue 'Bridging the gap: from

Bipolar gas outflow from the nova V458 Vul

NASA Astrophysics Data System (ADS)

Goranskij, V. P.; Barsukova, E. A.; Fatkhullin, T. A.

2010-06-01

Classical nova V458 Vul (N Vul 2007 No.1) was detected as a supersoft X-ray source by the Swift XRT (ATel#1246, #1603). This star is interesting with its spectral class change: features of Fe II class nova completely changed by features of He/N class in the SSS phase (T.N. Tarasova, IBVS No.5807). We performed spectral observations of V458 Vul with the Russian 6-m telescope BTA and spectral camera SCORPIO on 2010 June 9.84 UT.

Endothelial progenitor cells in chronic obstructive pulmonary disease and emphysema

PubMed Central

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

Motor neurons and oligodendrocytes arise from distinct cell lineages by progenitor recruitment

PubMed Central

Ravanelli, Andrew M.; Appel, Bruce

2015-01-01

During spinal cord development, ventral neural progenitor cells that express the transcription factors Olig1 and Olig2, called pMN progenitors, produce motor neurons and then oligodendrocytes. Whether motor neurons and oligodendrocytes arise from common or distinct progenitors in vivo is not known. Using zebrafish, we found that motor neurons and oligodendrocytes are produced sequentially by distinct progenitors that have distinct origins. When olig2+ cells were tracked during the peak period of motor neuron formation, most differentiated as motor neurons without further cell division. Using time-lapse imaging, we found that, as motor neurons differentiated, more dorsally positioned neuroepithelial progenitors descended to the pMN domain and initiated olig2 expression. Inhibition of Hedgehog signaling during motor neuron differentiation blocked the ventral movement of progenitors, the progressive initiation of olig2 expression, and oligodendrocyte formation. We therefore propose that the motor neuron-to-oligodendrocyte switch results from Hedgehog-mediated recruitment of glial-fated progenitors to the pMN domain subsequent to neurogenesis. PMID:26584621

Neuropeptides: Developmental Signals in Placode Progenitor Formation

PubMed Central

Lleras-Forero, Laura; Tambalo, Monica; Christophorou, Nicolas; Chambers, David; Houart, Corinne; Streit, Andrea

2013-01-01

Summary Few families of signaling factors have been implicated in the control of development. Here, we identify the neuropeptides nociceptin and somatostatin, a neurotransmitter and neuroendocrine hormone, as a class of developmental signals in both chick and zebrafish. We show that signals from the anterior mesendoderm are required for the formation of anterior placode progenitors, with one of the signals being somatostatin. Somatostatin controls ectodermal expression of nociceptin, and both peptides regulate Pax6 in lens and olfactory progenitors. Consequently, loss of somatostatin and nociceptin signaling leads to severe reduction of lens formation. Our findings not only uncover these neuropeptides as developmental signals but also identify a long-sought-after mechanism that initiates Pax6 in placode progenitors and may explain the ancient evolutionary origin of neuropeptides, predating a complex nervous system. PMID:23906067

Observational Implications of a Fall-back Crust around a Quark-nova Compact Remnant: Application to AXPs and SGRs

NASA Astrophysics Data System (ADS)

Leahy, Denis A.; Ouyed, R.; Niebergal, B.

2006-12-01

Mass is ejected from a quark stars formed by the Quark-Nova process (Ouyed, Dey and Dey, 2002 A&A, 390, L39; Keranen, Ouyed and Jaikumar 2005 ApJ, 681, 485). Some fraction of this ejecta is below escape velocity and falls back toward the compact object. If the magnetic field of the compact object is high enough, the fall-back material forms a shell of iron-rich material which then evolves quasi-statically. We explore the formation and evolution of such a fall-back crust (so-called because the material originates in the crust of the neutron star progenitor to the quark-nova). We find the resulting properites have application to the observed properties of Soft Gamma-ray Repeaters (SGRs) and Anomolous X-ray Pulsars (AXPs). These observed features of SGRs and AXPs are: (i) the two types of bursts (giant and regular); (ii) the spin-up and spin-down episodes during and following the bursts with associated persistant increases in period derivative ; (iii) the energetics of the boxing day burst, SGR1806+20; (iv) the presence of an Iron line as observed in SGR1900+14; (v) the correlation between the far-Infrared and the X-ray fluxes during the bursting episode and the quiescent phase; (vi) the hard X-ray component observed in SGRs during the giant bursts, and (vii) the discrepancy between the ages of SGRs/AXPs and their supernova remnants. We also find a natural evolutionary relationship between SGRs and AXPs in our model which predicts that only the youngest SGRs/AXPs are most likely to exhibit strong bursting. We acknowledge funding for this research from the Natural Science and Engineering Research Council of Canada.

Strong earthquakes, novae and cosmic ray environment

NASA Technical Reports Server (NTRS)

Yu, Z. D.

1985-01-01

Observations about the relationship between seismic activity and astronomical phenomena are discussed. First, after investigating the seismic data (magnitude 7.0 and over) with the method of superposed epochs it is found that world seismicity evidently increased after the occurring of novae with apparent magnitude brighter than 2.2. Second, a great many earthquakes of magnitude 7.0 and over occurred in the 13th month after two of the largest ground level solar cosmic ray events (GLEs). The causes of three high level phenomena of global seismic activity in 1918-1965 can be related to these, and it is suggested that according to the information of large GLE or bright nova predictions of the times of global intense seismic activity can be made.

Tycho Brahe and the Nova of 1572

NASA Astrophysics Data System (ADS)

Gingerich, O.

2005-12-01

The brilliant Nova of 1572 marked the beginning of the end of Aristotelian cosmology and provided the defining moment when the young Tycho Brahe became a professional astronomer. He received more than a ton of gold from the Danish king to build his Uraniborg Observatory. His instruments, the finest produced in the pre-telescopic age, enabled him to establish that both the nova and the Comet of 1577 lay beyond the moon, contrary to Aristotle's teaching. His major attempt to establish the distance to Mars (in order to distinguish between the Ptolemaic and Copernican cosmologies) failed, but left in its wake a magnificently accurate set of data that enabled Kepler to make the greatest advance in celestial mechanics since Copernicus himself.

NOVA[R] Spring 2002 Teacher's Guide.

ERIC Educational Resources Information Center

Armstrong, Peter; Ransick, Kristi; Rosene, Dale; Sammons, James

The guide presents lesson plans from "NOVA" which targets middle school and junior high school students and meet the National Science Education Standards. Lessons include: (1) "Neanderthals on Trial"; (2) "Fireworks"; (3) "Secrets, Lies and Atomic Spies"; (4) "Bioterror"; (5) "The Missing…

An X-ray survey of nine historical novae. [HEAO 2 observations

NASA Technical Reports Server (NTRS)

Becker, R. H.; Marshall, F. E.

1980-01-01

The Einstein Observatory imaging proportional counter was used to search for X-ray emission from nine nearby historical novae. Six of the novae were detected with estimated X-ray intensities between .1 to 4 keV of 10 to the -13th power to 10 to the -11th power ergs/sq cm-s, comparable to the intensities of previously detected cataclysmic variables. The X-ray intensity of one of the novae, V603 Aql, varies over times of several hundred seconds. The data suggest a correlation between the decay rate of the historical outburst and the current X-ray luminosity. Alternatively, the X-ray luminosity may be related to the inclination of the binary system.

Alumni Association | Nova Southeastern University

Science.gov Websites

toward a better future for our students, faculty and staff members, alumni, and community. Read The ! Apply Now / Request Info Giving Alumni Select A College Nova Southeastern University Abraham S. Fischler NSU has to offer undergraduate students. Student Life Learn why the years you spend at NSU will be

Nucleic Acid Encoding A Lectin-Derived Progenitor Cell Preservation Factor

DOEpatents

Colucci, M. Gabriella; Chrispeels, Maarten J.; Moore, Jeffrey G.

2001-10-30

The invention relates to an isolated nucleic acid molecule that encodes a protein that is effective to preserve progenitor cells, such as hematopoietic progenitor cells. The nucleic acid comprises a sequence defined by SEQ ID NO:1, a homolog thereof, or a fragment thereof. The encoded protein has an amino acid sequence that comprises a sequence defined by SEQ ID NO:2, a homolog thereof, or a fragment thereof that contains an amino acid sequence TNNVLQVT. Methods of using the encoded protein for preserving progenitor cells in vitro, ex vivo, and in vivo are also described. The invention, therefore, include methods such as myeloablation therapies for cancer treatment wherein myeloid reconstitution is facilitated by means of the specified protein. Other therapeutic utilities are also enabled through the invention, for example, expanding progenitor cell populations ex vivo to increase chances of engraftation, improving conditions for transporting and storing progenitor cells, and facilitating gene therapy to treat and cure a broad range of life-threatening hematologic diseases.

Atmospheric PCB concentrations at Terra Nova Bay, Antarctica.

PubMed

Gambaro, Andrea; Manodori, Laura; Zangrando, Roberta; Cincinelli, Alessandra; Capodaglio, Gabriele; Cescon, Paolo

2005-12-15

Concentrations of gas-phase polychlorobiphenyls (PCBs) were studied over an austral summer at a site in Terra Nova Bay, Antarctica. Gas-phase concentrations of individual PCB congeners in the atmosphere of Terra Nova Bay ranged from below the detection limit to 0.25 pg m(-3), with a mean concentration of sigmaPCB of 1.06 pg m(-3). The PCB profile was dominated by lower-chlorinated PCB congeners; in fact >78% of the total PCB content was due to congeners with 1-4 chlorine atoms and only about 10% with 5-7 chlorines, whereas higher-chlorinated PCB congeners were below detection limits. The mean sigmaPCB concentration obtained in this study were lower than those reported in previous Antarctic studies. Temporal concentration profiles of sigmaPCB do not correspond to seasonal temperature changes. In consideration of the low PCB concentrations observed, the studies with the wind roses, the regression between In P(PCB) and T(-1), and the distribution of congeners, we can hypothesize that PCB local source contributions are not very important, whereas long-distance transport is the prevalent factor bringing PCBs to Terra Nova Bay.

Discovery of an old nova shell surrounding the cataclysmic variable V1315 Aql

NASA Astrophysics Data System (ADS)

Sahman, D. I.; Dhillon, V. S.; Littlefair, S. P.; Hallinan, G.

2018-04-01

Following our tentative discovery of a faint shell around V1315 Aql reported in Sahman et al. (2015), we undertook deep Hα imaging and intermediate-resolution spectroscopy of the shell. We find that the shell has its geometric centre located on V1315 Aql. The mass, spectral features and density of the shell are consistent with other nova shells, rather than planetary nebulae or supernova remnants. The radial velocity of the shell is consistent with the systemic velocity of V1315 Aql. We believe this evidence strongly suggests that the shell originates from an earlier nova event. This is the first nova shell discovered around a novalike, and supports the theory of nova-induced cycles in mass transfer rates (hibernation theory) first proposed by Shara et al. (1986).

Noninvasive Imaging of Administered Progenitor Cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Steven R Bergmann, M.D., Ph.D.

The objective of this research grant was to develop an approach for labeling progenitor cells, specifically those that we had identified as being able to replace ischemic heart cells, so that the distribution could be followed non-invasively. In addition, the research was aimed at determining whether administration of progenitor cells resulted in improved myocardial perfusion and function. The efficiency and toxicity of radiolabeling of progenitor cells was to be evaluated. For the proposed clinical protocol, subjects with end-stage ischemic coronary artery disease were to undergo a screening cardiac positron emission tomography (PET) scan using N-13 ammonia to delineate myocardial perfusionmore » and function. If they qualified based on their PET scan, they would undergo an in-hospital protocol whereby CD34+ cells were stimulated by the administration of granulocytes-colony stimulating factor (G-CSF). CD34+ cells would then be isolated by apharesis, and labeled with indium-111 oxine. Cells were to be re-infused and subjects were to undergo single photon emission computed tomography (SPECT) scanning to evaluate uptake and distribution of labeled progenitor cells. Three months after administration of progenitor cells, a cardiac PET scan was to be repeated to evaluate changes in myocardial perfusion and/or function. Indium oxine is a radiopharmaceutical for labeling of autologous lymphocytes. Indium-111 (In-111) decays by electron capture with a t{sub ½} of 67.2 hours (2.8 days). Indium forms a saturated complex that is neutral, lipid soluble, and permeates the cell membrane. Within the cell, the indium-oxyquinolone complex labels via indium intracellular chelation. Following leukocyte labeling, ~77% of the In-111 is incorporated in the cell pellet. The presence of red cells and /or plasma reduces the labeling efficacy. Therefore, the product needed to be washed to eliminate plasma proteins. This repeated washing can damage cells. The CD34 selected product was a

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

NASA Astrophysics Data System (ADS)

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.

Finally, the Progenitor of the Type Ib iPTF13bvn

NASA Astrophysics Data System (ADS)

Van Dyk, Schulyer

2017-08-01

Supernovae (SNe) are among the most powerful events in the Universe and have a profound influence on galaxy evolution. Whereas we have been able to identify the luminous red supergiant progenitor stars of the most common core-collapse explosions, the hydrogen-rich Type II, the progenitors of hydrogen-poor Type Ib and Type Ic have been far more elusive. To strip away a SN Ib/c progenitor's outer layers, theoretical models with either (a) a highly-massive star with prodigious winds during the Wolf-Rayet phase or (b) a somewhat lower-mass star in a close, mass-exchange binary system have been proposed. One example exists so far of a progenitor identification, for the SN Ib iPTF13bvn in NGC 5806. Both models have been invoked to explain this event, although most evidence to date points toward the binary model. Our combined team observed this SN with WFC3 in Cycle 22, about 2 years after explosion, to investigate whether the progenitor had disappeared. As a result, we were able to report that indeed it had. We also attempted to better characterize the nature of the progenitor by subtracting our images from the pre-explosion HST data. Unfortunately, the old SN was apparently still conspicuously present. We therefore propose to reimage the SN site, when the SN should then be well below detectability, to produce high-quality templates of the host galaxy for subtraction. We can then finally fully reveal the progenitor and understand its true nature. iPTF13bvn is one of the most important historical SNe and will most probably be the best available case of a SN Ib progenitor for HST's remaining lifetime. It is imperative to understand the nature of this SN and its progenitor object.

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

PubMed

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.

ASAS-SN Discovery of a Possible Galactic Nova ASASSN-18ix

NASA Astrophysics Data System (ADS)

Stanek, K. Z.; Kochanek, C. S.; Shields, J. V.; Thompson, T. A.; Chomiuk, L.; Strader, J.; Shappee, B. J.; Holoien, T. W.-S.; Prieto, J. L.; Dong, Subo; Stritzinger, M.

2018-04-01

During the ongoing All Sky Automated Survey for SuperNovae (ASAS-SN, Shappee et al. 2014), using data from multiple ASAS-SN telescopes, we detect a new bright transient source, possibly a classical nova, but it might also be a young, large amplitude outburst of a cataclysmic variable Object RA (J2000) DEC (J2000) Gal l (deg) Gal b (deg) Disc.

Restablished Accretion in Post-outburst Classical Novae Revealed by X-rays

NASA Astrophysics Data System (ADS)

Hernanz, Margarita; Ferri, Carlo; Sala, Glòria

2009-05-01

Classical novae are explosions on accreting white dwarfs (hereinafter WDs) in cataclysmic variables (hereinafter CVs) a hydrogen thermonuclear runaway on top of the WD is responsible for the outburst. X-rays provide a unique way to study the turn-off of H-burning, because super soft X-rays reveal the hot WD photosphere, but also to understand how accretion is established again in the binary system. Observations with XMM-Newton of some post-outburst novae have revealed such a process, but a coverage up to larger energies -as Simbol-X will provide- is fundamental to well understand the characteristics of the binary system and of the nova ejecta. We present a brief summary of our results up to now and prospects for the Simbol-X mission.

NOVA[R] Spring 2001 Teacher's Guide.

ERIC Educational Resources Information Center

WGBH-TV, Boston, MA.

This teacher's guide is designed to accompany the PBS television program "NOVA" and features six activities. "Sultan's Lost Treasure" presents the attempts of an archaeologist and his team to salvage an ancient ship wreck. "Vanished!" investigates what happened to the Stardust airliner in 1947 which disappeared during…

Nova Scotia. Reference Series No. 32.

ERIC Educational Resources Information Center

Department of External Affairs, Ottawa (Ontario).

This booklet, one of a series featuring the Canadian provinces, presents a brief overview of Nova Scotia and is suitable for teacher reference or student reading. Separate sections discuss the geography and climate, history, economic development, fishing, agriculture, forestry, mining, manufacturing, energy, education, arts and culture, and…

New insights from a statistical analysis of IUE spectra of dwarf novae and nova-like stars. I - Inclination effects in lines and continua

NASA Technical Reports Server (NTRS)

La Dous, Constanze

1991-01-01

IUE observations of dwarf novae at maximum at quiescence and novalike objects at the high brightness state are analyzed for effects of the inclination angle on the emitted continuum and line radiation. A clear pattern in the continuum flux distribution is exhibited only by dwarf novae at maximum where some 80 percent of the non-double-eclipsing systems show essentially identical distributions. This result is not in disagreement with theoretical expectations. All classes of objects exhibit a clear, but in each case different, dependence of the line radiation on the inclination angle.

Altered gene products involved in the malignant reprogramming of cancer stem/progenitor cells and multitargeted therapies

PubMed Central

Mimeault, Murielle; Batra, Surinder K.

2013-01-01

Recent studies in the field of cancer stem cells have revealed that the alterations in key gene products involved in the epithelial-mesenchymal transition (EMT) program, altered metabolic pathways such as enhanced glycolysis, lipogenesis and/or autophagy and treatment resistance may occur in cancer stem/progenitor cells and their progenies during cancer progression. Particularly, the sustained activation of diverse developmental cascades such as hedgehog, epidermal growth factor receptor (EGFR), Wnt/β-catenin, Notch, transforming growth factor-β (TGF-β)/TGF-βR receptors and/or stromal cell-derived factor-1 (SDF-1)/CXC chemokine receptor 4 (CXCR4) can play critical functions for high self-renewal potential, survival, invasion and metastases of cancer stem/progenitor cells and their progenies. It has also been observed that cancer cells may be reprogrammed to re-express different pluripotency-associated stem cell-like markers such as Myc, Oct-3/4, Nanog and Sox-2 along the EMT process and under stressful and hypoxic conditions. Moreover, the enhanced expression and/or activities of some drug resistance-associated molecules such as Bcl-2, Akt/molecular target of rapamycin (mTOR), nuclear factor-kappaB (NF-κB), hypoxia-inducible factors (HIFs), macrophage inhibitory cytokine-1 (MIC-1) and ATP-binding cassette (ABC) multidrug transporters frequently occur in cancer cells during cancer progression and metastases. These molecular events may cooperate for the survival and acquisition of a more aggressive and migratory behavior by cancer stem/progenitor cells and their progenies during cancer transition to metastatic and recurrent disease states. Of therapeutic interest, these altered gene products may also be exploited as molecular biomarkers and therapeutic targets to develop novel multitargeted strategies for improving current cancer therapies and preventing disease relapse. PMID:23994756

V390 Nor = Nova Normae 2007

NASA Astrophysics Data System (ADS)

Waagen, Elizabeth O.

2007-06-01

Nova Normae 2007 was discovered photographically by William Liller on June 15.086 UT at magnitude 9.4. Precise position measured by G. Bolt from his unfiltered CCD image of June 16.7 UT: 16:32:11.51 -45:09:13.4 (2000.0). Giorgio Di Scala reported to the AAVSO that a low-resolution spectrum indicates a nova a week or so after outburst, with strong H-alpha emission. E. Kazarovets, Sternberg Astronomical Institute, reports that N Nor 07 has been assigned the name V390 Nor. Discovery originally announced in IAU Central Bureau Electronic Telegram 982 (Daniel W. E. Green) and AAVSO Special Notice #49 (Arne Henden). Information in this Alert Notice was received at AAVSO from William Liller, Giorgio Di Scala, or via IAU Circular No. 8850, ed. Daniel W. E. Green. A chart for V390 Nor is available via the Variable Star Plotter (VSP). Go to: http://www.aavso.org/observing/charts/vsp/ and enter the name V390 NOR.

Vascular wall progenitor cells in health and disease.

PubMed

Psaltis, Peter J; Simari, Robert D

2015-04-10

The vasculature plays an indispensible role in organ development and maintenance of tissue homeostasis, such that disturbances to it impact greatly on developmental and postnatal health. Although cell turnover in healthy blood vessels is low, it increases considerably under pathological conditions. The principle sources for this phenomenon have long been considered to be the recruitment of cells from the peripheral circulation and the re-entry of mature cells in the vessel wall back into cell cycle. However, recent discoveries have also uncovered the presence of a range of multipotent and lineage-restricted progenitor cells in the mural layers of postnatal blood vessels, possessing high proliferative capacity and potential to generate endothelial, smooth muscle, hematopoietic or mesenchymal cell progeny. In particular, the tunica adventitia has emerged as a progenitor-rich compartment with niche-like characteristics that support and regulate vascular wall progenitor cells. Preliminary data indicate the involvement of some of these vascular wall progenitor cells in vascular disease states, adding weight to the notion that the adventitia is integral to vascular wall pathogenesis, and raising potential implications for clinical therapies. This review discusses the current body of evidence for the existence of vascular wall progenitor cell subpopulations from development to adulthood and addresses the gains made and significant challenges that lie ahead in trying to accurately delineate their identities, origins, regulatory pathways, and relevance to normal vascular structure and function, as well as disease. © 2015 American Heart Association, Inc.

Constraints on the neutrino flux in NOvA using the near detector data

DOE PAGES

Maan, Kuldeep K.

2016-12-19

NOvA, a long-baseline neutrino oscillation experiment at Fermilab, is designed to measure electron-neutrino appearance and muon-neutrino disappearance in the NuMI beam. NOvA comprises of two finely segmented liquid scintillator detectors at 14 mrad off-axis in the NuMI beam. An accurate prediction of the neutrino flux is needed for precision oscillation and cross-section measurements. Data from the hadron-production experiments and, importantly, from the NOvA Near Detector provide powerful constraints on the muon-neutrino and electron-neutrino fluxes. In particular, the measurement of the neutrino-electron elastic scattering provides an in situ constraint on the absolute flux. Lastly, this poster presents the data-driven predictions ofmore » the NOvA muonneutrino and electron-neutrino flux, and outlines future improvements in the flux determination.« less

VEGF is a chemoattractant for FGF-2–stimulated neural progenitors

PubMed Central

Zhang, Huanxiang; Vutskits, Laszlo; Pepper, Michael S.; Kiss, Jozsef Z.

2003-01-01

Mmigration of undifferentiated neural progenitors is critical for the development and repair of the nervous system. However, the mechanisms and factors that regulate migration are not well understood. Here, we show that vascular endothelial growth factor (VEGF)-A, a major angiogenic factor, guides the directed migration of neural progenitors that do not display antigenic markers for neuron- or glia-restricted precursor cells. We demonstrate that progenitor cells express both VEGF receptor (VEGFR) 1 and VEGFR2, but signaling through VEGFR2 specifically mediates the chemotactic effect of VEGF. The expression of VEGFRs and the chemotaxis of progenitors in response to VEGF require the presence of fibroblast growth factor 2. These results demonstrate that VEGF is an attractive guidance cue for the migration of undifferentiated neural progenitors and offer a mechanistic link between neurogenesis and angiogenesis in the nervous system. PMID:14691144

Spectroscopy of the nova candidate M31-2008-10b

NASA Astrophysics Data System (ADS)

Di Mille, F.; Ciroi, S.; Orio, M.; Rafanelli, P.; Bianchini, A.; Nelson, T.; Andreuzzi, G.

2008-10-01

We obtained a low resolution spectrum of the nova candidate M31-2008-10b ( see CBAT M31 nova page) on 2008 October 26.12 UT. The observations were performed with TNG + DOLORES spectrograph 20 days after the first detection (see Atel #1790 ). The spectrum (in the 330-790 nm range, with resolution 1 nm) shows strong Balmer lines superimposed on a flat continuum.

Detection of Highly-Absorbed X-rays from Nova Mus 2018 with Swift

NASA Astrophysics Data System (ADS)

Nelson, Thomas; Kuin, Paul; Mukai, Koji; Page, Kim; Chomiuk, Laura; Kawash, Adam; Sokoloski, J. L.; Linford, Justin; Rupen, Michael P.; Mioduszewski, Amy

2018-03-01

We report the detection of X-rays from Nova Mus 2018 with the Swift XRT instrument. We have been carrying out weekly monitoring of the nova with Swift since its discovery on 2018 Jan 15 (see ATel #11220), and observations up to 2018 Feb 24 yielded X-ray non-detections.

Transcriptome Profiles of Isolated Murine Achilles Tendon Proper- and Peritenon- Derived Progenitor Cells.

PubMed

Mienaltowski, Michael J; Cánovas, Angela; Fates, Valerie A; Hampton, Angela R; Pechanec, Monica Y; Islas-Trejo, Alma; Medrano, Juan F

2018-06-21

Progenitor cells of the tendon proper and peritenon have unique properties that could impact their utilization in tendon repair strategies. While a few markers have been found to aid in distinguishing progenitors cells from each region, there is great value in identifying more markers. In this study, we hypothesized that RNAseq could be used to improve our understanding of those markers that define these cell types. Transcriptome profiles were generated for pools of mouse Achilles tendon progenitor cells from both regions and catalogues of potential markers were generated. Moreover, common (e.g., glycoprotein, signaling, and proteinaceous extracellular matrix) and unique (e.g., cartilage development versus angiogenesis and muscle contraction) biological processes and molecular functions were described for progenitors from each region. Real-time quantitative PCR of a subset of genes was used to gain insight into the heterogeneity amongst individual progenitor colonies from each region. Markers like Scx, Mkx, Thbs4, and Wnt10a were consistently able to distinguish tendon proper progenitors from peritenon progenitors; expression variability for other genes suggested greater cell type complexity for potential peritenon progenitor markers. This is the first effort to define Achilles tendon progenitor markers by region. Further efforts to investigate the value of these catalogued markers are required by screening more individual colonies of progenitors for more markers. Findings from this study advance efforts in the discernment of cell type specific markers for tendon proper and peritenon progenitor cells; insight into marker sets could improve tracking and sorting strategies for these cells for future therapeutic strategies. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Thymus-autonomous T cell development in the absence of progenitor import.

PubMed

Martins, Vera C; Ruggiero, Eliana; Schlenner, Susan M; Madan, Vikas; Schmidt, Manfred; Fink, Pamela J; von Kalle, Christof; Rodewald, Hans-Reimer

2012-07-30

Thymus function is thought to depend on a steady supply of T cell progenitors from the bone marrow. The notion that the thymus lacks progenitors with self-renewal capacity is based on thymus transplantation experiments in which host-derived thymocytes replaced thymus-resident cells within 4 wk. Thymus grafting into T cell-deficient mice resulted in a wave of T cell export from the thymus, followed by colonization of the thymus by host-derived progenitors, and cessation of T cell development. Compound Rag2(-/-)γ(c)(-/-)Kit(W/Wv) mutants lack competitive hematopoietic stem cells (HSCs) and are devoid of T cell progenitors. In this study, using this strain as recipients for wild-type thymus grafts, we noticed thymus-autonomous T cell development lasting several months. However, we found no evidence for export of donor HSCs from thymus to bone marrow. A diverse T cell antigen receptor repertoire in progenitor-deprived thymus grafts implied that many thymocytes were capable of self-renewal. Although the process was most efficient in Rag2(-/-)γ(c)(-/-)Kit(W/Wv) hosts, γ(c)-mediated signals alone played a key role in the competition between thymus-resident and bone marrow-derived progenitors. Hence, the turnover of each generation of thymocytes is not only based on short life span but is also driven via expulsion of resident thymocytes by fresh progenitors entering the thymus.

NFIX Regulates Neural Progenitor Cell Differentiation During Hippocampal Morphogenesis

PubMed Central

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

Direct Reprogramming of Mouse Fibroblasts into Functional Skeletal Muscle Progenitors.

PubMed

Bar-Nur, Ori; Gerli, Mattia F M; Di Stefano, Bruno; Almada, Albert E; Galvin, Amy; Coffey, Amy; Huebner, Aaron J; Feige, Peter; Verheul, Cassandra; Cheung, Priscilla; Payzin-Dogru, Duygu; Paisant, Sylvain; Anselmo, Anthony; Sadreyev, Ruslan I; Ott, Harald C; Tajbakhsh, Shahragim; Rudnicki, Michael A; Wagers, Amy J; Hochedlinger, Konrad

2018-05-08

Skeletal muscle harbors quiescent stem cells termed satellite cells and proliferative progenitors termed myoblasts, which play pivotal roles during muscle regeneration. However, current technology does not allow permanent capture of these cell populations in vitro. Here, we show that ectopic expression of the myogenic transcription factor MyoD, combined with exposure to small molecules, reprograms mouse fibroblasts into expandable induced myogenic progenitor cells (iMPCs). iMPCs express key skeletal muscle stem and progenitor cell markers including Pax7 and Myf5 and give rise to dystrophin-expressing myofibers upon transplantation in vivo. Notably, a subset of transplanted iMPCs maintain Pax7 expression and sustain serial regenerative responses. Similar to satellite cells, iMPCs originate from Pax7 + cells and require Pax7 itself for maintenance. Finally, we show that myogenic progenitor cell lines can be established from muscle tissue following small-molecule exposure alone. This study thus reports on a robust approach to derive expandable myogenic stem/progenitor-like cells from multiple cell types. Copyright © 2018 The Author(s). Published by Elsevier Inc. All rights reserved.

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

PubMed Central

Hui, Subhra Prakash; Nag, Tapas Chandra; Ghosh, Sukla

2015-01-01

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. PMID:26630262

The lowest-metallicity type II supernova from the highest-mass red supergiant progenitor

NASA Astrophysics Data System (ADS)

Anderson, J. P.; Dessart, L.; Gutiérrez, C. P.; Krühler, T.; Galbany, L.; Jerkstrand, A.; Smartt, S. J.; Contreras, C.; Morrell, N.; Phillips, M. M.; Stritzinger, M. D.; Hsiao, E. Y.; González-Gaitán, S.; Agliozzo, C.; Castellón, S.; Chambers, K. C.; Chen, T.-W.; Flewelling, H.; Gonzalez, C.; Hosseinzadeh, G.; Huber, M.; Fraser, M.; Inserra, C.; Kankare, E.; Mattila, S.; Magnier, E.; Maguire, K.; Lowe, T. B.; Sollerman, J.; Sullivan, M.; Young, D. R.; Valenti, S.

2018-05-01

Red supergiants have been confirmed as the progenitor stars of the majority of hydrogen-rich type II supernovae1. However, while such stars are observed with masses >25 M⊙ (ref. 2), detections of >18 M⊙ progenitors remain elusive1. Red supergiants are also expected to form at all metallicities, but discoveries of explosions from low-metallicity progenitors are scarce. Here, we report observations of the type II supernova, SN 2015bs, for which we infer a progenitor metallicity of ≤0.1 Z⊙ from comparison to photospheric-phase spectral models3, and a zero-age main-sequence mass of 17–25 M⊙ through comparison to nebular-phase spectral models4,5. SN 2015bs displays a normal ‘plateau’ light-curve morphology, and typical spectral properties, implying a red supergiant progenitor. This is the first example of such a high-mass progenitor for a ‘normal’ type II supernova, suggesting a link between high-mass red supergiant explosions and low-metallicity progenitors.

Circulating hematopoietic progenitor cells in patients affected by Chornobyl accident.

PubMed

Bilko, N M; Dyagil, I S; Russu, I Z; Bilko, D I

2016-12-01

High radiation sensitivity of stem cells and their ability to accumulate sublethal radiation damage provides the basis for investigation of hematopoietic progenitors using in vivo culture methodology. Unique samples of peripheral blood and bone marrow were derived from the patients affected by Chornobyl accident during liquidation campaign. To investigate functional activity of circulating hematopoietic progenitor cells from peripheral blood and bone marrow of cleanup workers in early and remote periods after the accident at Chornobyl nuclear power plant (CNPP). The assessment of the functional activity of circulating hematopoietic progenitor cells was performed in samples of peripheral blood and bone marrow of 46 cleanup workers, who were treated in the National Scientific Center for Radiation Medicine of the Academy of Medical Sciences of Ukraine alongside with 35 non radiated patients, who served as a control. Work was performed by culturing peripheral blood and bone marrow mononuclear cells in the original gel diffusion capsules, implanted into the peritoneal cavity of CBA mice. It was shown that hematopoietic progenitor cells could be identified in the peripheral blood of liquidators of CNPP accident. At the same time the number of functionally active progenitor cells of the bone marrow was significantly decreased and during the next 10 years after the accident, counts of circulating progenitor cells in the peripheral blood as well as functionally active hematopoietic cells in bone marrow returned to normal levels. It was shown that hematopoietic progenitor cells are detected not only in the bone marrow but also in the peripheral blood of liquidators as a consequence of radiation exposure associated with CNPP accident. This article is a part of a Special Issue entitled "The Chornobyl Nuclear Accident: Thirty Years After".

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

PubMed

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.

Combined KIT and FGFR2b Signaling Regulates Epithelial Progenitor Expansion during Organogenesis

PubMed Central

Lombaert, Isabelle M.A.; Abrams, Shaun R.; Li, Li; Eswarakumar, Veraragavan P.; Sethi, Aditya J.; Witt, Robert L.; Hoffman, Matthew P.

2013-01-01

Summary Organ formation and regeneration require epithelial progenitor expansion to engineer, maintain, and repair the branched tissue architecture. Identifying the mechanisms that control progenitor expansion will inform therapeutic organ (re)generation. Here, we discover that combined KIT and fibroblast growth factor receptor 2b (FGFR2b) signaling specifically increases distal progenitor expansion during salivary gland organogenesis. FGFR2b signaling upregulates the epithelial KIT pathway so that combined KIT/FGFR2b signaling, via separate AKT and mitogen-activated protein kinase (MAPK) pathways, amplifies FGFR2b-dependent transcription. Combined KIT/FGFR2b signaling selectively expands the number of KIT+K14+SOX10+ distal progenitors, and a genetic loss of KIT signaling depletes the distal progenitors but also unexpectedly depletes the K5+ proximal progenitors. This occurs because the distal progenitors produce neurotrophic factors that support gland innervation, which maintains the proximal progenitors. Furthermore, a rare population of KIT+FGFR2b+ cells is present in adult glands, in which KIT signaling also regulates epithelial-neuronal communication during homeostasis. Our findings provide a framework to direct regeneration of branched epithelial organs. PMID:24371813

Targeting human oligodendrocyte progenitors for myelin repair☆

PubMed Central

Dietz, Karen C.; Polanco, Jessie J.; Pol, Suyog U.; Sim, Fraser J.

2017-01-01

Oligodendrocyte development has been studied for several decades, and has served as a model system for both neurodevelopmental and stem/progenitor cell biology. Until recently, the vast majority of studies have been conducted in lower species, especially those focused on rodent development and remyelination. In humans, the process of myelination requires the generation of vastly more myelinating glia, occurring over a period of years rather than weeks. Furthermore, as evidenced by the presence of chronic demyelination in a variety of human neurologic diseases, it appears likely that the mechanisms that regulate development and become dysfunctional in disease may be, in key ways, divergent across species. Improvements in isolation techniques, applied to primary human neural and oligodendrocyte progenitors from both fetal and adult brain, as well as advancements in the derivation of defined progenitors from human pluripotent stem cells, have begun to reveal the extent of both species-conserved signaling pathways and potential key differences at cellular and molecular levels. In this article, we will review the commonalities and differences in myelin development between rodents and man, describing the approaches used to study human oligodendrocyte differentiation and myelination, as well as heterogeneity within targetable progenitor pools, and discuss the advances made in determining which conserved pathways may be both modeled in rodents and translate into viable therapeutic strategies to promote myelin repair. PMID:27001544

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

PubMed

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.

PubMed

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.

APC sets the Wnt tone necessary for cerebral cortical progenitor development

PubMed Central

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

2017-01-01

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. PMID:28916710

Experimental measurements of hydrodynamic instabilities on NOVA of relevance to astrophysics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Budil, K S; Cherfils, C; Drake, R P

1998-09-11

Large lasers such as Nova allow the possibility of achieving regimes of high energy densities in plasmas of millimeter spatial scales and nanosecond time scales. In those plasmas where thermal conductivity and viscosity do not play a significant role, the hydrodynamic evolution is suitable for benchmarking hydrodynamics modeling in astrophysical codes. Several experiments on Nova examine hydrodynamically unstable interfaces. A typical Nova experiment uses a gold millimeter-scale hohlraum to convert the laser energy to a 200 eV blackbody source lasting about a nanosecond. The x-rays ablate a planar target, generating a series of shocks and accelerating the target. The evolvingmore » area1 density is diagnosed by time-resolved radiography, using a second x-ray source. Data from several experiments are presented and diagnostic techniques are discussed.« less

Optical Spectroscopy of Nova Ophiuchi 2015 (PNV J17291350-1846120)

NASA Astrophysics Data System (ADS)

Danilet, A. B.; Holoien, T. W.-S.; Wagner, R. M.; Woodward, C. E.; Starrfield, S.; Wilber, A.; Walter, F.; Shore, S.

2015-04-01

Following the discovery by Y. Sakurai (Ibaraki-ken, Japan) on 2015 Mar. 29.766 UT of a new stellar object of magnitude 12.2 in Ophiuchus (S. Nakano, CBET 4086) and its subsequent confirmation as a likely He/N classical nova (K Ayani, CBET 4086), we obtained a spectrum (range: 398-685 nm; resolution 0.3 nm) of Nova Oph 2015 on 2015 April 1.459 UT with the 2.4 m Hiltner telescope (+OSMOS) of the MDM Observatory on Kitt Peak.

Hmga2 regulates self-renewal of retinal progenitors.

PubMed

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.

Innovation and Skills Development in the Rural Voluntary Sector in Nova Scotia

ERIC Educational Resources Information Center

Canadian Rural Partnership, 2002

2002-01-01

This report is a summary of discussions that took place at the Rural Voluntary Sector Leaders' Dialogue, entitled "Innovation and Skills Development in the Rural Voluntary Sector in Nova Scotia", held in Truro, Nova Scotia on September 20, 2002. Many of the discussions took place in brainstorming sessions at which no limits were placed…

Spectroscopic and Photometric Behaviour of Nova Cygni 1992 IN the First Nine Months Following Outburst

NASA Astrophysics Data System (ADS)

Chochol, D.; Hric, L.; Urban, Z.; Komzik, R.; Grygar, J.; Papousek, J.

1993-09-01

We present the results of UBV photometry and high dispersion 360-500 nm spectroscopy of Nova Cygni 1992 (= V 1974 Cyg), obtained between February 25 and November 9, 1992. Our data cover the early decline, transition and nebular stages of the evolution of the nova. We discuss the photometric and spectroscopic behaviour of the star during the first nine months after outburst and briefly compare our findings with the data already published by other authors. We have classified the nova as a fast one with t2,V = 16 d, t2,B = 23 d, and t3,V = 42 d, t3,B = 51 d. We have derived the absolute magnitudes of the nova at maximum to be M0,V = -7.67 and M0,B = -7.49. The latter value yields a mass of 0.83 Msun for the white dwarf component. The values of the distance modulus 12.23 and the colour excess EB-V = +0.32 correspond to a distance r = 1.77 kpc. We have found a period of 0.814 days by period analysis of photoelectric V data obtained before the nova declined 3m. During the nebular stage, forbidden lines of highly ionized neon were prominent, confirming the 0-Ne-Mg classification of the nova. The outburst of Nova Cygni 1992 was apparently caused by a super-Eddington thermonuclear runaway on the surface of an evolutionarily eroded O-Ne-Mg white dwarf.

Advances in hepatic stem/progenitor cell biology

PubMed Central

Verhulst, Stefaan; Best, Jan; van Grunsven, Leo A.; Dollé, Laurent

2015-01-01

The liver is famous for its strong regenerative capacity, employing different modes of regeneration according to type and extent of injury. Mature liver cells are able to proliferate in order to replace the damaged tissue allowing the recovery of the parenchymal function. In more severe scenarios hepatocytes are believed to arise also from a facultative liver progenitor cell compartment. In human, severe acute liver failure and liver cirrhosis are also both important clinical targets in which regeneration is impaired, where the role of this stem cell compartment seems more convincing. In animal models, the current state of ambiguity regarding the identity and role of liver progenitor cells in liver physiology dampens the enthusiasm for the potential use of these cells in regenerative medicine. The aim of this review is to give the basics of liver progenitor cell biology and discuss recent results vis-à-vis their identity and contribution to liver regeneration. PMID:26600740

Identification of oocyte progenitor cells in the zebrafish ovary.

PubMed

Draper, Bruce W

2012-01-01

Zebrafish breed year round and females are capable of producing thousands of eggs during their lifetime. This amazing fecundity is due to the fact that the adult ovary, contains premeiotic oocyte progenitor cells, called oogonia, which produce a continuous supply of new oocytes throughout adult life. Oocyte progenitor cells can be easily identified based on their expression of Vasa, and their characteristic nuclear morphology. Thus, the zebrafish ovary provides a unique and powerful system to study the genetic regulation of oocyte production in a vertebrate animal. A method is presented here for identifying oocyte progenitor cells in the zebrafish ovary using whole-mount confocal immunofluorescence that is simple and accurate.

Gamma-ray emission concurrent with the nova in the symbiotic binary V407 Cygni.

PubMed

Abdo, A A; Ackermann, M; Ajello, M; Atwood, W B; Baldini, L; Ballet, J; Barbiellini, G; Bastieri, D; Bechtol, K; Bellazzini, R; Berenji, B; Blandford, R D; Bloom, E D; Bonamente, E; Borgland, A W; Bouvier, A; Brandt, T J; Bregeon, J; Brez, A; Brigida, M; Bruel, P; Buehler, R; Burnett, T H; Buson, S; Caliandro, G A; Cameron, R A; Caraveo, P A; Carrigan, S; Casandjian, J M; Cecchi, C; Celik, O; Charles, E; Chaty, S; Chekhtman, A; Cheung, C C; Chiang, J; Ciprini, S; Claus, R; Cohen-Tanugi, J; Conrad, J; Corbel, S; Corbet, R; DeCesar, M E; den Hartog, P R; Dermer, C D; de Palma, F; Digel, S W; Donato, D; do Couto e Silva, E; Drell, P S; Dubois, R; Dubus, G; Dumora, D; Favuzzi, C; Fegan, S J; Ferrara, E C; Fortin, P; Frailis, M; Fuhrmann, L; Fukazawa, Y; Funk, S; Fusco, P; Gargano, F; Gasparrini, D; Gehrels, N; Germani, S; Giglietto, N; Giordano, F; Giroletti, M; Glanzman, T; Godfrey, G; Grenier, I A; Grondin, M-H; Grove, J E; Guiriec, S; Hadasch, D; Harding, A K; Hayashida, M; Hays, E; Healey, S E; Hill, A B; Horan, D; Hughes, R E; Itoh, R; Jean, P; Jóhannesson, G; Johnson, A S; Johnson, R P; Johnson, T J; Johnson, W N; Kamae, T; Katagiri, H; Kataoka, J; Kerr, M; Knödlseder, J; Koerding, E; Kuss, M; Lande, J; Latronico, L; Lee, S-H; Lemoine-Goumard, M; Garde, M Llena; Longo, F; Loparco, F; Lott, B; Lovellette, M N; Lubrano, P; Makeev, A; Mazziotta, M N; McConville, W; McEnery, J E; Mehault, J; Michelson, P F; Mizuno, T; Moiseev, A A; Monte, C; Monzani, M E; Morselli, A; Moskalenko, I V; Murgia, S; Nakamori, T; Naumann-Godo, M; Nestoras, I; Nolan, P L; Norris, J P; Nuss, E; Ohno, M; Ohsugi, T; Okumura, A; Omodei, N; Orlando, E; Ormes, J F; Ozaki, M; Paneque, D; Panetta, J H; Parent, D; Pelassa, V; Pepe, M; Pesce-Rollins, M; Piron, F; Porter, T A; Rainò, S; Rando, R; Ray, P S; Razzano, M; Razzaque, S; Rea, N; Reimer, A; Reimer, O; Reposeur, T; Ripken, J; Ritz, S; Romani, R W; Roth, M; Sadrozinski, H F-W; Sander, A; Parkinson, P M Saz; Scargle, J D; Schinzel, F K; Sgrò, C; Shaw, M S; Siskind, E J; Smith, D A; Smith, P D; Sokolovsky, K V; Spandre, G; Spinelli, P; Stawarz, Ł; Strickman, M S; Suson, D J; Takahashi, H; Takahashi, T; Tanaka, T; Tanaka, Y; Thayer, J B; Thayer, J G; Thompson, D J; Tibaldo, L; Torres, D F; Tosti, G; Tramacere, A; Uchiyama, Y; Usher, T L; Vandenbroucke, J; Vasileiou, V; Vilchez, N; Vitale, V; Waite, A P; Wallace, E; Wang, P; Winer, B L; Wolff, M T; Wood, K S; Yang, Z; Ylinen, T; Ziegler, M; Maehara, H; Nishiyama, K; Kabashima, F; Bach, U; Bower, G C; Falcone, A; Forster, J R; Henden, A; Kawabata, K S; Koubsky, P; Mukai, K; Nelson, T; Oates, S R; Sakimoto, K; Sasada, M; Shenavrin, V I; Shore, S N; Skinner, G K; Sokoloski, J; Stroh, M; Tatarnikov, A M; Uemura, M; Wahlgren, G M; Yamanaka, M

2010-08-13

Novae are thermonuclear explosions on a white dwarf surface fueled by mass accreted from a companion star. Current physical models posit that shocked expanding gas from the nova shell can produce x-ray emission, but emission at higher energies has not been widely expected. Here, we report the Fermi Large Area Telescope detection of variable gamma-ray emission (0.1 to 10 billion electron volts) from the recently detected optical nova of the symbiotic star V407 Cygni. We propose that the material of the nova shell interacts with the dense ambient medium of the red giant primary and that particles can be accelerated effectively to produce pi(0) decay gamma-rays from proton-proton interactions. Emission involving inverse Compton scattering of the red giant radiation is also considered and is not ruled out.

Wnt Signaling Specifies Anteroposterior Progenitor Zone Identity in the Drosophila Visual Center.

PubMed

Suzuki, Takumi; Trush, Olena; Yasugi, Tetsuo; Takayama, Rie; Sato, Makoto

2016-06-15

During brain development, various types of neuronal populations are produced from different progenitor pools to produce neuronal diversity that is sufficient to establish functional neuronal circuits. However, the molecular mechanisms that specify the identity of each progenitor pool remain obscure. Here, we show that Wnt signaling is essential for the specification of the identity of posterior progenitor pools in the Drosophila visual center. In the medulla, the largest component of the visual center, different types of neurons are produced from two progenitor pools: the outer proliferation center (OPC) and glial precursor cells (GPCs; also known as tips of the OPC). We found that OPC-type neurons are produced from the GPCs at the expense of GPC-type neurons when Wnt signaling is suppressed in the GPCs. In contrast, GPC-type neurons are ectopically induced when Wnt signaling is ectopically activated in the OPC. These results suggest that Wnt signaling is necessary and sufficient for the specification of the progenitor pool identity. We also found that Homothorax (Hth), which is temporally expressed in the OPC, is ectopically induced in the GPCs by suppression of Wnt signaling and that ectopic induction of Hth phenocopies the suppression of Wnt signaling in the GPCs. Thus, Wnt signaling is involved in regionalization of the fly visual center through the specification of the progenitor pool located posterior to the medulla by suppressing Hth expression. Brain consists of considerably diverse neurons of different origins. In mammalian brain, excitatory and inhibitory neurons derive from the dorsal and ventral telencephalon, respectively. Multiple progenitor pools also contribute to the neuronal diversity in fly brain. However, it has been unclear how differences between these progenitor pools are established. Here, we show that Wnt signaling, an evolutionarily conserved signaling, is involved in the process that establishes the differences between these progenitor

Constraints on core-collapse supernova progenitors from explosion site integral field spectroscopy

NASA Astrophysics Data System (ADS)

Kuncarayakti, H.; Anderson, J. P.; Galbany, L.; Maeda, K.; Hamuy, M.; Aldering, G.; Arimoto, N.; Doi, M.; Morokuma, T.; Usuda, T.

2018-05-01

Context. Observationally, supernovae (SNe) are divided into subclasses according to their distinct characteristics. This diversity naturally reflects the diversity in the progenitor stars. It is not entirely clear, however, how different evolutionary paths leading massive stars to become an SN are governed by fundamental parameters such as progenitor initial mass and metallicity. Aims: This paper places constraints on progenitor initial mass and metallicity in distinct core-collapse SN subclasses through a study of the parent stellar populations at the explosion sites. Methods: Integral field spectroscopy (IFS) of 83 nearby SN explosion sites with a median distance of 18 Mpc has been collected and analysed, enabling detection and spectral extraction of the parent stellar population of SN progenitors. From the parent stellar population spectrum, the initial mass and metallicity of the coeval progenitor are derived by means of comparison to simple stellar population models and strong-line methods. Additionally, near-infrared IFS was employed to characterise the star formation history at the explosion sites. Results: No significant metallicity differences are observed among distinct SN types. The typical progenitor mass is found to be highest for SN type Ic, followed by type Ib, then types IIb and II. Type IIn is the least associated with young stellar populations and thus massive progenitors. However, statistically significant differences in progenitor initial mass are observed only when comparing SNe IIn with other subclasses. Stripped-envelope SN progenitors with initial mass estimates lower than 25 M⊙ are found; they are thought to be the result of binary progenitors. Confirming previous studies, these results support the notion that core-collapse SN progenitors cannot arise from single-star channels only, and both single and binary channels are at play in the production of core-collapse SNe. Near-infrared IFS suggests that multiple stellar populations with

Alternative splicing disabled by Nova2.

PubMed

Park, Tae-Ju; Curran, Tom

2010-06-24

Disabled-1 is a key signaling molecule in the Reelin pathway that plays a critical role in neuronal migration and positioning during brain development. In this issue of Neuron, Yano et al. demonstrate that the neuron-specific RNA binding protein Nova2 contributes to neuronal migration by regulating alternative splicing of disabled-1.

Self-organization and progenitor targeting generate stable patterns in planarian regeneration.

PubMed

Atabay, Kutay Deniz; LoCascio, Samuel A; de Hoog, Thom; Reddien, Peter W

2018-04-27

During animal regeneration, cells must organize into discrete and functional systems. We show that self-organization, along with patterning cues, govern progenitor behavior in planarian regeneration. Surgical paradigms allowed the manipulation of planarian eye regeneration in predictable locations and numbers, generating alternative stable neuroanatomical states for wild-type animals with multiple functional ectopic eyes. We used animals with multiple ectopic eyes and eye transplantation to demonstrate that broad progenitor specification, combined with self-organization, allows anatomy maintenance during regeneration. We propose a model for regenerative progenitors involving (i) migratory targeting cues, (ii) self-organization into existing or regenerating eyes, and (iii) a broad zone, associated with coarse progenitor specification, in which eyes can be targeted by progenitors. These three properties help explain how tissues can be organized during regeneration. Copyright © 2018 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.

Bipotential adult liver progenitors are derived from chronically injured mature hepatocytes

PubMed Central

Tarlow, Branden D.; Pelz, Carl; Naugler, Willscott E.; Wakefield, Leslie; Wilson, Elizabeth M.; Finegold, Milton J.; Grompe, Markus

2014-01-01

Summary Adult liver progenitor cells are biliary-like epithelial cells that emerge only under injury conditions in the periportal region of the liver. They exhibit phenotypes of both hepatocytes and bile ducts. However, their origin and their significance to injury repair remain unclear. Here, we used a chimeric lineage tracing system to demonstrate that hepatocytes contribute to the progenitor pool. RNA-sequencing, ultrastructural analysis, and in vitro progenitor assays revealed that hepatocyte-derived progenitors were distinct from their biliary-derived counterparts. In vivo lineage tracing and serial transplantation assays showed that hepatocyte-derived proliferative ducts retained a memory of their origin and differentiated back into hepatocytes upon cessation of injury. Similarly, human hepatocytes in chimeric mice also gave rise to biliary progenitors in vivo. We conclude that human and mouse hepatocytes can undergo reversible ductal metaplasia in response to injury, expand as ducts and subsequently contribute to restoration of the hepatocyte mass. PMID:25312494

Renal blood flow and oxygenation drive nephron progenitor differentiation.

PubMed

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.

FGF/EGF signaling regulates the renewal of early nephron progenitors during embryonic development.

PubMed

Brown, Aaron C; Adams, Derek; de Caestecker, Mark; Yang, Xuehui; Friesel, Robert; Oxburgh, Leif

2011-12-01

Recent studies indicate that nephron progenitor cells of the embryonic kidney are arranged in a series of compartments of an increasing state of differentiation. The earliest progenitor compartment, distinguished by expression of CITED1, possesses greater capacity for renewal and differentiation than later compartments. Signaling events governing progression of nephron progenitor cells through stages of increasing differentiation are poorly understood, and their elucidation will provide key insights into normal and dysregulated nephrogenesis, as well as into regenerative processes that follow kidney injury. In this study, we found that the mouse CITED1(+) progenitor compartment is maintained in response to receptor tyrosine kinase (RTK) ligands that activate both FGF and EGF receptors. This RTK signaling function is dependent on RAS and PI3K signaling but not ERK. In vivo, RAS inactivation by expression of sprouty 1 (Spry1) in CITED1(+) nephron progenitors results in loss of characteristic molecular marker expression and in increased death of progenitor cells. Lineage tracing shows that surviving Spry1-expressing progenitor cells are impaired in their subsequent epithelial differentiation, infrequently contributing to epithelial structures. These findings demonstrate that the survival and developmental potential of cells in the earliest embryonic nephron progenitor cell compartment are dependent on FGF/EGF signaling through RAS.

DNMT1 maintains progenitor function in self-renewing somatic tissue.

PubMed

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.

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

PubMed

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.

A hydrodynamic study of a slow nova outburst. [computerized simulation of thermonuclear runaway in white dwarf envelope

NASA Technical Reports Server (NTRS)

Sparks, W. M.; Starrfield, S.; Truran, J. W.

1978-01-01

The paper reports use of a Lagrangian implicit hydrodynamics computer code incorporating a full nuclear-reaction network to follow a thermonuclear runaway in the hydrogen-rich envelope of a 1.25 solar-mass white dwarf. In this evolutionary sequence the envelope was assumed to be of normal (solar) composition and the resulting outburst closely resembles that of the slow nova HR Del. In contrast, previous CNO-enhanced models resemble fast nova outbursts. The slow-nova model ejects material by radiation pressure when the high luminosity of the rekindled hydrogen shell source exceeds the local Eddington luminosity of the outer layers. This is in contrast to the fast nova outburst where ejection is caused by the decay of the beta(+)-unstable nuclei. Nevertheless, radiation pressure probably plays a major role in ejecting material from the fast nova remnants. Therefore, the sequence from slow to fast novae can be interpreted as a sequence of white dwarfs with increasing amounts of enhanced CNO nuclei in their hydrogen envelopes, although other parameters such as the white-dwarf mass and accretion rate probably contribute to the observed variation between novae.

Endothelial progenitor cells--an evolving story.

PubMed

Pearson, Jeremy D

2010-05-01

The first description of endothelial progenitor cells (EPC) in 1997 led rapidly to substantial changes in our understanding of angiogenesis, and within 5 years to the first clinical studies in humans using bone marrow derived EPC to enhance coronary neovascularisation and cardiac function after myocardial ischemia. However, to improve the success of this therapy a clearer understanding of the biology of EPC is needed. This article summarises recent data indicating that most EPC are not, in fact, endothelial progenitors but can be better described as angiogenic monocytes, and explores the implications this has for their future therapeutic use. Copyright 2009 Elsevier Inc. All rights reserved.

A search for sterile neutrinos at the NOvA Far Detector

NASA Astrophysics Data System (ADS)

Aurisano, Adam; Davies, Gavin S.; Kafka, Gareth K.; Sousa, Alex; Suter, Louise; Yang, Shaokai

2017-09-01

NOvA is the current United States flagship long-baseline neutrino experiment designed to study the properties of neutrino oscillations. It consists of two functionally identical detectors each located 14.6 mrad off the central axis from the Fermilab NuMI neutrino beam. The Near Detector is located 1 km downstream from the beam source, and the Far Detector is located 810 km away in Ash River, Minnesota. This long baseline, combined with the ability of the NuMI facility to switch between nearly pure neutrino and anti-neutrino beams, allows NOvA to make precision measurements of neutrino mixing angles, potentially determine the neutrino mass hierarchy, and begin searching for CP violating effects in the lepton sector. However, NOvA can also probe more exotic scenarios, such as oscillations between the known active neutrinos and new sterile species. We will showcase the first search for sterile neutrinos in a 3 + 1 model at NOvA. The analysis presented searches for a deficit in the rate of neutral current events at the Far Detector using the Near Detector to constrain the predicted spectrum. This analysis was performed using data taken between February 2014 and May 2016 corresponding to 6.05 × 1020 protons on target.

SOX2 expression levels distinguish between neural progenitor populations of the developing dorsal telencephalon.

PubMed

Hutton, Scott R; Pevny, Larysa H

2011-04-01

The HMG-Box transcription factor SOX2 is expressed in neural progenitor populations throughout the developing and adult central nervous system and is necessary to maintain their progenitor identity. However, it is unclear whether SOX2 levels are uniformly expressed across all neural progenitor populations. In the developing dorsal telencephalon, two distinct populations of neural progenitors, radial glia and intermediate progenitor cells, are responsible for generating a majority of excitatory neurons found in the adult neocortex. Here we demonstrate, using both cellular and molecular analyses, that SOX2 is differentially expressed between radial glial and intermediate progenitor populations. Moreover, utilizing a SOX2(EGFP) mouse line, we show that this differential expression can be used to prospectively isolate distinct, viable populations of radial glia and intermediate cells for in vitro analysis. Given the limited repertoire of cell-surface markers currently available for neural progenitor cells, this provides an invaluable tool for prospectively identifying and isolating distinct classes of neural progenitor cells from the central nervous system. Copyright © 2011 Elsevier Inc. All rights reserved.

Metallicity Differences in Type Ia Supernova Progenitors Inferred from Ultraviolet Spectra

NASA Astrophysics Data System (ADS)

Foley, Ryan J.; Kirshner, Robert P.

2013-05-01

Two "twin" Type Ia supernovae (SNe Ia), SNe 2011by and 2011fe, have extremely similar optical light-curve shapes, colors, and spectra, yet have different ultraviolet (UV) continua as measured in Hubble Space Telescope spectra and measurably different peak luminosities. We attribute the difference in the UV continua to significantly different progenitor metallicities. This is the first robust detection of different metallicities for SN Ia progenitors. Theoretical reasoning suggests that differences in metallicity also lead to differences in luminosity. SNe Ia with higher progenitor metallicities have lower 56Ni yields and lower luminosities for the same light-curve shape. SNe 2011by and 2011fe have different peak luminosities (ΔMV ≈ 0.6 mag), which correspond to different 56Ni yields: M_11fe(^{56}Ni) / M_11by(^{56}Ni) = 1.7^{+0.7}_{-0.5}. From theoretical models that account for different neutron-to-proton ratios in progenitors, the differences in 56Ni yields for SNe 2011by and 2011fe imply that their progenitor stars were above and below solar metallicity, respectively. Although we can distinguish progenitor metallicities in a qualitative way from UV data, the quantitative interpretation in terms of abundances is limited by the present state of theoretical models.

Multiple prethymic defects underlie age-related loss of T progenitor competence

PubMed Central

Zediak, Valerie P.; Maillard, Ivan

2007-01-01

Aging in mice and humans is characterized by declining T-lymphocyte production in the thymus, yet it is unclear whether aging impacts the T-lineage potential of hematopoietic progenitors. Although alterations in the lymphoid progenitor content of aged mouse bone marrow (BM) have been described, irradiation-reconstitution experiments have failed to reveal defects in T-lineage potential of BM hematopoietic progenitors or purified hematopoietic stem cells (HSCs) from aged mice. Here, we assessed T-progenitor potential in unmanipulated recipient mice without conditioning irradiation. T-progenitor potential was reduced in aged BM compared with young BM, and this reduction was apparent at the earliest stages of intrathymic differentiation. Further, enriched populations of aged HSCs or multipotent progenitors (MPPs) gave rise to fewer T-lineage cells than their young counterparts. Whereas the T-precursor frequency within the MPP pool was unchanged, there was a 4-fold decline in T-precursor frequency within the HSC pool. In addition, among the T-competent HSC clones, there were fewer highly proliferative clones in the aged HSC pool than in the young HSC pool. These results identify T-compromised aged HSCs and define the nature and cellular sites of prethymic, age-related defects in T-lineage differentiation potential. PMID:17456721

Collision Tomography: Physical Properties of Possible Progenitors of the Andromeda Stellar Stream

NASA Astrophysics Data System (ADS)

Miki, Yohei; Mori, Masao; Rich, R. Michael

2016-08-01

To unveil a progenitor of the Andromeda Giant Stellar Stream, we investigate the interaction between an accreting satellite galaxy and the Andromeda Galaxy using an N-body simulation. We perform a comprehensive exploration of the properties of the progenitor dwarf galaxy, using 247 models of varying mass, mass distribution, and size. We show that the binding energy of the progenitor is the crucial parameter in reproducing the Andromeda Giant Stellar Stream and the shell-like structures surrounding the Andromeda Galaxy. As a result of the simulations, the progenitor must satisfy a simple scaling relation between the core radius, the total mass and the tidal radius. Using this relation, we successfully constrain the physical properties of the progenitors to have masses ranging from 5× {10}8{M}⊙ to 5× {10}9{M}⊙ and central surface densities around {10}3 {M}⊙ {{pc}}-2. A detailed comparison between our result and the nearby observed galaxies indicates that possible progenitors of the Andromeda Giant Stellar Stream include a dwarf elliptical galaxy, a dwarf irregular galaxy, and a small spiral galaxy.

Nova Sagittarii 2014 = PNV J18250860-2236024 AND Erratum

NASA Astrophysics Data System (ADS)

Waagen, Elizabeth O.

2014-02-01

Details of discovery of Nova Sagittarii 2014 (PNV J18250860-2236024) and procedures for observing and reporting observations are announced. Discovered by Sigeru Furuyama (Tone-machi, Ibaraki-ken, Japan) andreported by S. Nakano (Sumoto, Japan) at unfiltered CCD magnitude 8.7 on 2014 Jan. 26.857 UT. Coordinates: R.A. 18 25 08.60 Decl. = -22 36 02.4 (2000.0). Nova Sgr 2014 is Fe II-type classical nova past maximum, per low-resolution spectra obtained by A. Arai on 2014 Jan. 30.87 UT. Announced in IAU CBAT CBET 3802 (D. W. E. Green, ed.). Finder charts with sequence may be created using the AAVSO Variable Star Plotter (http://www.aavso.org/vsp). Observations should be submitted to the AAVSO International Database. See full Alert Notice for more details and observations. Also, an Erratum is reported. In AAVSO Alert Notice 496, Mati Morel (MMAT, Thornton, NSW, Australia) was credited with the discovery of the 1989 outburst of V745 Sco. The discoverer was William Liller (LIW, Vina del Mar, Chile), who observed V745 Sco on 1989 July 30.08 UT at magnitude 9.7 (PROBLICOM discovery using 2415 film with orange filter).

Synthetic Spectral Analysis of the Far Ultraviolet Spectra of the Old Nova HR Del

NASA Astrophysics Data System (ADS)

Robertson, Jordan; Sion, E.

2012-05-01

We present a synthetic spectral analysis of the archival IUE far ultraviolet spectra of the post-nova, HR Del (Nova Del 1967). The system has an estimated white dwarf mass of 0.55 Msun (Ritter and Kolb 2003), orbital period P_orb = 0.214165 days, estimated orbital inclination of 40 degrees (Keurster 1988) and distance determinations in the literature ranging from 970 pc to 285 pc. The spectra reveal P Cygni profiles indicative of wind outflow from the disk and closely resemble the IUE spectra of UX UMa nova-likes, which have never had recorded outbursts. We de-reddened the archival IUE spectra using E(B-V) = 0.16. Our synthetic spectral analysis utilized optically thick, steady state accretion disk models and white dwarf model atmospheres that we constructed using TLUSTY and SYNSPEC (Hubeny 1988, Hubeny and Lanz (1995). Our input parameters were the white dwarf mass, inclination and a range of accretion rates for which we found the best-fitting model. We report the results of our model fitting and compare HR Del with other post-novae at comparable times past their nova outburst. This work was supported by NSF grant 0807892 to Villanova University

The Convolutional Visual Network for Identification and Reconstruction of NOvA Events

DOE Office of Scientific and Technical Information (OSTI.GOV)

Psihas, Fernanda

In 2016 the NOvA experiment released results for the observation of oscillations in the vμ and ve channels as well as ve cross section measurements using neutrinos from Fermilab’s NuMI beam. These and other measurements in progress rely on the accurate identification and reconstruction of the neutrino flavor and energy recorded by our detectors. This presentation describes the first application of convolutional neural network technology for event identification and reconstruction in particle detectors like NOvA. The Convolutional Visual Network (CVN) Algorithm was developed for identification, categorization, and reconstruction of NOvA events. It increased the selection efficiency of the ve appearancemore » signal by 40% and studies show potential impact to the vμ disappearance analysis.« less

DNA damage tolerance in hematopoietic stem and progenitor cells in mice

PubMed Central

Pilzecker, Bas; Buoninfante, Olimpia Alessandra; van den Berk, Paul; Lancini, Cesare; Song, Ji-Ying; Citterio, Elisabetta

2017-01-01

DNA damage tolerance (DDT) enables bypassing of DNA lesions during replication, thereby preventing fork stalling, replication stress, and secondary DNA damage related to fork stalling. Three modes of DDT have been documented: translesion synthesis (TLS), template switching (TS), and repriming. TLS and TS depend on site-specific PCNA K164 monoubiquitination and polyubiquitination, respectively. To investigate the role of DDT in maintaining hematopoietic stem cells (HSCs) and progenitors, we used PcnaK164R/K164R mice as a unique DDT-defective mouse model. Analysis of the composition of HSCs and HSC-derived multipotent progenitors (MPPs) revealed a significantly reduced number of HSCs, likely owing to increased differentiation of HSCs toward myeloid/erythroid-associated MPP2s. This skewing came at the expense of the number of lymphoid-primed MPP4s, which appeared to be compensated for by increased MPP4 proliferation. Furthermore, defective DDT decreased the numbers of MPP-derived common lymphoid progenitor (CLP), common myeloid progenitor (CMP), megakaryocyte-erythroid progenitor (MEP), and granulocyte-macrophage progenitor (GMP) cells, accompanied by increased cell cycle arrest in CMPs. The HSC and MPP phenotypes are reminiscent of premature aging and stressed hematopoiesis, and indeed progressed with age and were exacerbated on cisplatin exposure. Bone marrow transplantations revealed a strong cell intrinsic defect of DDT-deficient HSCs in reconstituting lethally irradiated mice and a strong competitive disadvantage when cotransplanted with wild-type HSCs. These findings indicate a critical role of DDT in maintaining HSCs and progenitor cells, and in preventing premature aging. PMID:28761001

Observations and Analysis of the GK Persei Nova Shell and its "Jet-like" Feature

NASA Astrophysics Data System (ADS)

Harvey, E.; Redman, M. P.; Boumis, P.; Akras, S.

2015-12-01

GK Persei (1901, the "Firework Nebula") is an old but bright nova remnant that offers a chance to probe the physics and kinematics of nova shells. The kinematics in new and archival longslit optical echelle spectra were analysed using the SHAPE software. New imaging from the Aristarchos telescope continues to track the proper motion, extinction and structural evolution of the knots, which have been observed intermittently over several decades. We present for the first time, kinematical constraints on a large faint "jet" feature, that was previously detected beyond the shell boundary. These observational constraints allow for the generation of models for individual knots, interactions within knot complexes, and the "jet" feature. Put together, and taking into account dwarf-nova accelerated winds emanating from the central source, these data and models give a deeper insight into the GK Per nova remnant as a whole.

Gamma-Ray Emission Concurrent with the Nova in the Symbiotic Binary V407 Cygni

DOE PAGES

Abdo, A. A.; Ackermann, M.; Ajello, M.; ...

2010-08-13

Novae are thermonuclear explosions on a white dwarf surface fueled by mass accreted from a companion star. Current physical models posit that shocked expanding gas from the nova shell can produce x-ray emission, but emission at higher energies has not been widely expected. Here in this paper, we report the Fermi Large Area Telescope detection of variable γ-ray emission (0.1 to 10 billion electron volts) from the recently detected optical nova of the symbiotic star V407 Cygni. We propose that the material of the nova shell interacts with the dense ambient medium of the red giant primary and that particlesmore » can be accelerated effectively to produce π 0 decay γ-rays from proton-proton interactions. Lastly, emission involving inverse Compton scattering of the red giant radiation is also considered and is not ruled out.« less

Searches for sterile neutrinos with NOvA

DOE PAGES

Davies, Gavin S.; Aurisano, Adam; Kafka, Gareth K.; ...

2016-11-15

Contradictory evidence has been presented on the issue of neutrino mixing between the three known active neutrinos and light sterile neutrino species. Apparent short-baseline neutrino oscillations observed by the LSND and MiniBooNE experiments, the collective evidence of the reactor neutrino anomaly, and the gallium anomaly all point towards sterile neutrinos with mass at the 1 eV level. While these results are tantalizing, they are not conclusive as they are in tension with null results from other short-baseline experiments, and with disappearance searches in longbaseline and atmospheric experiments. The NOvA (NuMI Off-Axis v e Appearance) experiment may help clarify the situationmore » by searching for disappearance of active neutrinos from the NuMI (Neutrinos from the Main Injector) beam over a baseline of 810 km. We describe the method used by NOvA to look for oscillations into sterile neutrinos at the Far Detector (FD) through the disappearance of neutral-current (NC) neutrino events, including preliminary results of this search. In addition, the Near Detector (ND) is well suited for searching for anomalous short-baseline oscillations and probing the LSND and MiniBooNE sterile neutrino allowed regions using a variety of final states. We also present a novel method for selecting samples with high purity at the ND using convolutional neural networks. Furthermore, based on this method, the sensitivity to anomalous short-baseline nt appearance are shown, and searches for anomalous v e appearance and v μ disappearance at the NOvA ND are presented.« less

Computer Simulation of Magnetic Nova Shell Expantion

NASA Astrophysics Data System (ADS)

Dudnikova, Galina; Nikitin, Sergei; Snytnikov, Valeri; Vshivkov, Vitali

2000-10-01

An asymmetrical character of the shell expantion observed at many Nova may be associated with infuence of an inherent star magnetic field. Magneto-dipole energy of a Nova is much less than a kinetic energy of an exploding envelope. By this reason the conventional hydrodynamic models of point-like explosion with a spherical outward-directed shock wave do not consider effect of star magnetic field on the plasma movement. We used the numerical model based on the system of equations of the hybrid type( MHD approximation for electrons and Vlasov kinetic equations for ions). PIC-method for solving Vlasov equations was used. It gives an opportunaty to consider a complicated multi-flow motion of particles in plasma at super-Alfven velocity. At the beginning there is an immobile (cold) background plasma of a homogeneous concentration in a cylindrical region with a dipole magnetic field. Into the central spherical region of radius R, where the magnetic field remains uniform and constant , the external plasma does not penetrate with elastic reflections of ions at the spherical core surface. This boundary is spaced at r<Nova's shell in near-star medium.

Toxicity assessment in marine sediment for the Terra Nova environmental effects monitoring program (1997-2010)

NASA Astrophysics Data System (ADS)

Whiteway, Sandra A.; Paine, Michael D.; Wells, Trudy A.; DeBlois, Elisabeth M.; Kilgour, Bruce W.; Tracy, Ellen; Crowley, Roger D.; Williams, Urban P.; Janes, G. Gregory

2014-12-01

This paper discusses toxicity test results on sediments from the Terra Nova offshore oil development. The Terra Nova Field is located on the Grand Banks approximately 350 km southeast of Newfoundland (Canada). The amphipod (Rhepoxynius abronius) survival and solid phase luminescent bacteria (Vibrio fischeri, or Microtox) assays were conducted on sediment samples collected from approximately 50 stations per program year around Terra Nova during baseline (1997), prior to drilling, and in 2000, 2001, 2002, 2004, 2006, 2008 and 2010 after drilling began. The frequency of toxic responses in the amphipod toxicity test was low. Of the ten stations that were toxic in environmental effects monitoring (EEM) years, only one (station 30(FE)) was toxic in more than one year and could be directly attributed to Terra Nova project activities. In contrast, 65 (18%) of 364 EEM samples were toxic to Microtox. Microtox toxicity in EEM years was not related to distance from Terra Nova drill centres or concentrations of >C10-C21 hydrocarbons or barium, the primary constituents of the synthetic-based drill muds used at Terra Nova. Of the variables tested, fines and strontium levels showed the strongest (positive) correlations with toxicity. Neither fines nor strontium levels were affected by drill cuttings discharge at Terra Nova, except at station 30(FE) (and that station was not toxic to Microtox). Benthic macro-invertebrate abundance, richness and diversity were greater in toxic than in non-toxic sediments. Therefore, Microtox responses indicating toxicity were associated with positive biological responses in the field. This result may have been an indirect function of the increased abundance of most invertebrate taxa in less sandy sediments with higher gravel content, where fines and strontium levels and, consequently, toxicity to Microtox were high; or chemical substances released by biodegradation of organic matter, where invertebrates are abundant, may be toxic to Microtox. Given

Career Development at Nova Southeastern University

Science.gov Websites

. Handshake Handshake is NSU Career Development's fast and powerful online platform for students, alumni, and ! Apply Now / Request Info Giving Alumni Select A College Nova Southeastern University Abraham S. Fischler NSU has to offer undergraduate students. Student Life Learn why the years you spend at NSU will be

DNMT1 Maintains Progenitor Function in Self-Renewing Somatic Tissue

PubMed Central

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 maintenance,8 a clear role for DNMT1 in maintaining the progenitor state in constantly replenished somatic tissues, such as mammalian epidermis, is unknown. 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 revealed that a significant portion of epidermal differentiation gene promoters were methylated in self-renewing conditions but were subsequently demethylated during differentiation. Furthermore, we show that UHRF1,9,10 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, Gadd45A11,12 and B13, 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. PMID:20081831

A Detailed Observational Analysis of V1324 Sco, the Most Gamma-Ray-luminous Classical Nova to Date

NASA Astrophysics Data System (ADS)

Finzell, Thomas; Chomiuk, Laura; Metzger, Brian D.; Walter, Frederick M.; Linford, Justin D.; Mukai, Koji; Nelson, Thomas; Weston, Jennifer H. S.; Zheng, Yong; Sokoloski, Jennifer L.; Mioduszewski, Amy; Rupen, Michael P.; Dong, Subo; Starrfield, Sumner; Cheung, C. C.; Woodward, Charles E.; Taylor, Gregory B.; Bohlsen, Terry; Buil, Christian; Prieto, Jose; Wagner, R. Mark; Bensby, Thomas; Bond, I. A.; Sumi, T.; Bennett, D. P.; Abe, F.; Koshimoto, N.; Suzuki, D.; Tristram, P. J.; Christie, Grant W.; Natusch, Tim; McCormick, Jennie; Yee, Jennifer; Gould, Andy

2018-01-01

It has recently been discovered that some, if not all, classical novae emit GeV gamma-rays during outburst, but the mechanisms involved in the production ofgamma-rays are still not well understood. We present here a comprehensive multiwavelength data set—from radio to X-rays—for the most gamma-ray-luminous classical nova to date, V1324 Sco. Using this data set, we show that V1324 Sco is a canonical dusty Fe II-type nova, with a maximum ejecta velocity of 2600 km s‑1 and an ejecta mass of a few × {10}-5 {M}ȯ . There is also evidence for complex shock interactions, including a double-peaked radio light curve which shows high brightness temperatures at early times. To explore why V1324 Sco was so gamma-ray luminous, we present a model of the nova ejecta featuring strong internal shocks and find that higher gamma-ray luminosities result from higher ejecta velocities and/or mass-loss rates. Comparison of V1324 Sco with other gamma-ray-detected novae does not show clear signatures of either, and we conclude that a larger sample of similarly well-observed novae is needed to understand the origin and variation of gamma-rays in novae.

Differences and similarities between human and chimpanzee neural progenitors during cerebral cortex development

PubMed Central

Mora-Bermúdez, Felipe; Badsha, Farhath; Kanton, Sabina; Camp, J Gray; Vernot, Benjamin; Köhler, Kathrin; Voigt, Birger; Okita, Keisuke; Maricic, Tomislav; He, Zhisong; Lachmann, Robert; Pääbo, Svante; Treutlein, Barbara; Huttner, Wieland B

2016-01-01

Human neocortex expansion likely contributed to the remarkable cognitive abilities of humans. This expansion is thought to primarily reflect differences in proliferation versus differentiation of neural progenitors during cortical development. Here, we have searched for such differences by analysing cerebral organoids from human and chimpanzees using immunohistofluorescence, live imaging, and single-cell transcriptomics. We find that the cytoarchitecture, cell type composition, and neurogenic gene expression programs of humans and chimpanzees are remarkably similar. Notably, however, live imaging of apical progenitor mitosis uncovered a lengthening of prometaphase-metaphase in humans compared to chimpanzees that is specific to proliferating progenitors and not observed in non-neural cells. Consistent with this, the small set of genes more highly expressed in human apical progenitors points to increased proliferative capacity, and the proportion of neurogenic basal progenitors is lower in humans. These subtle differences in cortical progenitors between humans and chimpanzees may have consequences for human neocortex evolution. DOI: http://dx.doi.org/10.7554/eLife.18683.001 PMID:27669147

Synthetic Spectral Ananlysis of the Nova-Like Variable KQ Mon

NASA Astrophysics Data System (ADS)

Wolfe, Aaron; Sion, E.

2011-01-01

KQ Mon is classified as a nova-like variable with an uncertain orbital period of 0.128 d. Optical spectra (Zwitter, T. & Munari, U.1994, A&AS, 107, 503) reveal no emission lines but strong Balmer absorption features. High speed flickering has been observed indicative of accretion. IUE spectra reveal deep absorption lines due to C III, C II, Si III, Si IV, C IV, He II but no P Cygni profiles indicative of outflow. Its classification in Ritter and Kolb (2006) as a UX UMa type nova-like is uncertain. We have carried out the first synthetic spectral analysis of the IUE archival spectra of KQ Mon with realistic accretion disk models with vertical structure and high gravity photosphere models. The results of our model atmosphere and model accretion disk analyses are presented. We discuss the properties that we have derived for KQ Mon and compare KQ Mon with other nova-like variables viewed at low inclination. This work was supported in part by NSF grant AST0807892 to Villanova University.

DAQ Software Contributions, Absolute Scale Energy Calibration and Background Evaluation for the NOvA Experiment at Fermilab

DOE Office of Scientific and Technical Information (OSTI.GOV)

Flumerfelt, Eric Lewis

2015-08-01

The NOvA (NuMI Off-axis v e [nu_e] Appearance) Experiment is a long-baseline accelerator neutrino experiment currently in its second year of operations. NOvA uses the Neutrinos from the Main Injector (NuMI) beam at Fermilab, and there are two main off-axis detectors: a Near Detector at Fermilab and a Far Detector 810 km away at Ash River, MN. The work reported herein is in support of the NOvA Experiment, through contributions to the development of data acquisition software, providing an accurate, absolute-scale energy calibration for electromagnetic showers in NOvA detector elements, crucial to the primary electron neutrino search, and through anmore » initial evaluation of the cosmic background rate in the NOvA Far Detector, which is situated on the surface without significant overburden. Additional support work for the NOvA Experiment is also detailed, including DAQ Server Administration duties and a study of NOvA’s sensitivity to neutrino oscillations into a “sterile” state.« less

On the interpretation and implications of nova abundances: An abundance of riches or an overabundance of enrichments

NASA Technical Reports Server (NTRS)

Livio, Mario; Truran, James W.

1994-01-01

We reexamine the question of the frequency of occurrence of oxygen-neon-magnesium (ONeMg) degenerate dwarfs in classical nova systems, in light of recent observations which have been interpreted as suggesting that 'neon novae' can be associated with relatively low mass white dwarfs. Determinations of heavy-element concentrations in nova ejecta are reviewed, and possible interpretations of their origin are examined. We conclude that, of the 18 classical novae for which detailed abundance analyses are availble, only two (or possibly three) seem unambiguously to demand the presence of an underlying ONeMg white dwarf: V693 CrA 1981, V1370 Aql 1982, and possibly QU Vul 1984. Three other novae which exhibit significant neon enrichments, relative to their total heavy-element concentrations, are RR Pic 1925, V977, Sco 1989, and LMC 1990 No. 1. This result is entirely consistent with present frequency estimates, and our interpretation of the lower levels of enrichment in other systems explains, in a natural way, the existence of relatively low mass white dwarfs in some of the 'neon' novae.

Identification, Characterization, and Utilization of Adult Meniscal Progenitor Cells

DTIC Science & Technology

2015-09-01

the development of knee osteoarthritis (OA). New treatments centered on the stem/progenitor cell population resident within the adult meniscus will be...cells, stem cells, progenitor cells, meniscus healing, meniscus repair, osteoarthritis 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT...changes that occur after injury. As a result, meniscal injuries are a common underlying cause of post-traumatic osteoarthritis . This is particularly

Identification, Characterization, and Utilization of Adult Meniscal Progenitor Cells

DTIC Science & Technology

2016-09-01

development of knee osteoarthritis (OA). New treatments centered on the stem/progenitor cell population resident within the adult meniscus will be key to...cells, progenitor cells, meniscus healing, meniscus repair, osteoarthritis 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT 18. NUMBER...common underlying cause of post- traumatic osteoarthritis . This is particularly striking in young, healthy individuals such as military personnel

Luminal Progenitors Restrict Their Lineage Potential during Mammary Gland Development

PubMed Central

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

2015-01-01

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. PMID:25688859

Luminal progenitors restrict their lineage potential during mammary gland development.

PubMed

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.

Drug discovery for Diamond-Blackfan anemia using reprogrammed hematopoietic progenitors

PubMed Central

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

Early patterning and specification of cardiac progenitors in gastrulating mesoderm

PubMed Central

Devine, W Patrick; Wythe, Joshua D; George, Matthew; Koshiba-Takeuchi, Kazuko; Bruneau, Benoit G

2014-01-01

Mammalian heart development requires precise allocation of cardiac progenitors. The existence of a multipotent progenitor for all anatomic and cellular components of the heart has been predicted but its identity and contribution to the two cardiac progenitor ‘fields’ has remained undefined. Here we show, using clonal genetic fate mapping, that Mesp1+ cells in gastrulating mesoderm are rapidly specified into committed cardiac precursors fated for distinct anatomic regions of the heart. We identify Smarcd3 as a marker of early specified cardiac precursors and identify within these precursors a compartment boundary at the future junction of the left and right ventricles that arises prior to morphogenesis. Our studies define the timing and hierarchy of cardiac progenitor specification and demonstrate that the cellular and anatomical fate of mesoderm-derived cardiac cells is specified very early. These findings will be important to understand the basis of congenital heart defects and to derive cardiac regeneration strategies. DOI: http://dx.doi.org/10.7554/eLife.03848.001 PMID:25296024

Photoionisation modelling of Nova LMC 1990 #1

NASA Technical Reports Server (NTRS)

Dopita, M. A.; Meatheringham, S. J.; Sutherland, R.; Williams, R. E.; Starrfield, S.; Sonneborn, G.; Shore, S.

1992-01-01

Nova LMC 1990A was a very fast Ne-O-Mg nova, for which a particularly dense coverage of spectral observation in both the UV and optical was obtained. The data for the nebular phase were subjected to an analysis by the photoionization modeling code MAPPINGS 2. The following parameters were obtained: L(sub max) = 8 x 10(exp 4) solar luminosity, T(sub eff) = 2 x 10(exp 5) K and the mass of ejecta = 5/5 x 10(exp -5) solar mass. The abundnace ratios in the ejecta were similar to those obtained by Williams et al. (1985) in the case of V693 CrA 1981. The N/O ratio and the overabundance of Al is consistent with ourburst on a ONeMg white dwarf of mass approximately equal to 1.2 solar mass, but the super-Eddington luminosity, and amount of mass ejected presents some problems to theory.

Waiting Points in Nova and X-ray Burst Nucleosynthesis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sunayama, Tomomi; Smith, Michael Scott; Lingerfelt, Eric J

2008-01-01

In nova and X-ray burst nucleosynthesis, waiting points are nuclei in the reaction path which interrupt the nuclear flow towards heavier nuclei, typically because of a weak proton capture reaction and a long beta+ lifetime. Waiting points can influence the energy generation and final abundances synthesized in these explosions. We have constructed a systematic, quantitative set of criteria to identify rp-process waiting points, and use them to search for waiting points in post-processing simulations of novae and X-ray bursts. These criteria have been incorporated into the Computational Infrastructure for Nuclear Astrophysics, online at nucastrodata.org, to enable anyone to run customizedmore » searches for waiting points.« less

Waiting Points in Nova and X-ray burst Nucleosynthesis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sunayama, Tomomi; Oak Ridge Institute for Science Education, Oak Ridge, Tennessee 37831-0117; Smith, Michael S.

2008-05-21

In nova and X-ray burst nucleosynthesis, waiting points are nuclei in the reaction path which delay the nuclear flow towards heavier nuclei, typically because of a weak proton capture reaction and a long {beta}{sup +} lifetime. Waiting points can influence the energy generation and final abundances synthesized in these explosions. We have constructed a systematic, quantitative set of criteria to identify rp-process waiting points, and use them to search for waiting points in post-processing simulations of novae and X-ray bursts. These criteria have been incorporated into the Computational Infrastructure for Nuclear Astrophysics, online at nucastrodata.org, to enable anyone to runmore » customized searches for waiting points.« less

Fibroblast growth factor receptor-Frs2α signaling is critical for nephron progenitors.

PubMed

Di Giovanni, Valeria; Walker, Kenneth A; Bushnell, Daniel; Schaefer, Caitlin; Sims-Lucas, Sunder; Puri, Pawan; Bates, Carlton M

2015-04-01

Previous studies using transgenic Pax3cre mice have revealed roles for fibroblast growth factor receptors (Fgfrs) and Fgfr substrate 2α (Frs2α) signaling in early metanephric mesenchyme patterning and in ureteric morphogenesis. The role of Fgfr/Frs2α signaling in nephron progenitors is unknown. Thus, we generated mouse models using BAC transgenic Six2EGFPcre (Six2cre) mediated deletion of Fgfrs and/or Frs2α in nephron progenitors. Six2cre mediated deletion of Fgfr1 or Fgfr2 alone led to no obvious kidney defects. Six2creFgfr1(flox/flox)Fgfr2(flox/flox) (Fgfr1/2(NP-/-)) mice generate a discernable kidney; however, they develop nephron progenitor depletion starting at embryonic day 12.5 (E12.5) and later demonstrate severe cystic dysplasia. To determine the role of Frs2α signaling downstream of Fgfr2 in Fgfr1/2(NP-/-) mice, we generated Six2cre(,)Fgfr1(flox/flox)Fgfr2(LR/LR) (Fgfr1(NP-/-)Fgfr2(LR/LR)) mice that have point mutations in the Frs2α binding site of Fgfr2. Like Fgfr1/2(NP-/-) mice, Fgfr1(NP-/-)Fgfr2(LR/LR) develop nephron progenitor depletion, but it does not start until E14.5 and older mice have less severe cystic dysplasia than Fgfr1/2(NP-/-) To determine the role of Frs2α alone in nephron progenitors, we generated Six2creFrs2'A(flox/flox) (Frs2a(NP-/-)) mice. Frs2a(NP-/-)mice also develop nephron progenitor depletion and renal cysts, although these occurred later and were less severe than in the other Six2cre mutant mice. The nephron progenitor loss in all Six2cre mutant lines was associated with decreased Cited1 expression and increased apoptosis versus controls. FAC-sorted nephron progenitors in Six2cre Frs2'A(flox/flox) mice demonstrated evidence of increased Notch activity versus controls, which likely drives the progenitor defects. Thus, Fgfr1 and Fgfr2 have synergistic roles in maintaining nephron progenitors; furthermore, Fgfr signaling in nephron progenitors appears to be mediated predominantly by Frs2α. Copyright © 2015 Elsevier Inc

NovaNET 2008-09 Evaluation. Impact Evaluation. E&R Report No. 09.36

ERIC Educational Resources Information Center

Bulgakov-Cook, Dina

2010-01-01

NovaNET is a technology-based teacher-facilitated educational approach used at schools to support students at risk of not meeting graduation requirements to accrue credits in a variety of subjects. NovaNET contributes to the WCPSS goal of closing achievement gaps and creating opportunities for all students to graduate on time. In 2008-09, 38…

Low- and high-LET radiation drives clonal expansion of lung progenitor cells in vivo

PubMed Central

Farin, Alicia M.; Manzo, Nicholas D.; Kirsch, David G.; Stripp, Barry R.

2015-01-01

Abundant populations of epithelial progenitor cells maintain the epithelium along the proximal-to-distal axis of the airway. Exposure of lung tissue to ionizing radiation leads to tissue remodeling and potential cancer initiation or progression. However, little is known about the effects of ionizing radiation on airway epithelial progenitor cells. We hypothesized that ionizing radiation exposure will alter the behavior of airway epithelial progenitor cells in a radiation dose- and quality-dependent manner. To address this hypothesis, we cultured primary airway epithelial cells isolated from mice exposed to various doses of 320 kVp X-ray or 600 MeV/nucleon 56Fe ions in a 3D epithelial-fibroblast co-culture system. Colony-forming efficiency of the airway epithelial progenitor cells was assessed at culture day 14. In vivo clonogenic and proliferative potentials of airway epithelial progenitor cells were measured after exposure to ionizing radiation by lineage tracing and IdU incorporation. Exposure to both X-rays and 56Fe resulted in a dose dependent decrease in the ability of epithelial progenitors to form colonies in vitro. In vivo evidence for increased clonogenic expansion of epithelial progenitors was observed after exposure to both X-rays and 56Fe. Interestingly, we found no significant increase in the epithelial proliferative index, indicating that ionizing radiation does not promote increased turnover of the airway epithelium. Therefore, we propose a model in which radiation induces a dose-dependent decrease in the pool of available progenitor cells, leaving fewer progenitors able to maintain the airway long-term. This work provides novel insights into the effects of ionizing radiation exposure on airway epithelial progenitor cell behavior. PMID:25564721

The Expanding Bipolar Shell of the Helium Nova V445 Puppis

NASA Astrophysics Data System (ADS)

Woudt, P. A.; Steeghs, D.; Karovska, M.; Warner, B.; Groot, P. J.; Nelemans, G.; Roelofs, G. H. A.; Marsh, T. R.; Nagayama, T.; Smits, D. P.; O'Brien, T.

2009-11-01

From multi-epoch adaptive optics imaging and integral field unit spectroscopy, we report the discovery of an expanding and narrowly confined bipolar shell surrounding the helium nova V445 Puppis (Nova Puppis 2000). An equatorial dust disc obscures the nova remnant, and the outflow is characterized by a large polar outflow velocity of 6720 ± 650 km s-1 and knots moving at even larger velocities of 8450 ± 570 km s-1. We derive an expansion parallax distance of 8.2 ± 0.5 kpc and deduce a pre-outburst luminosity of the underlying binary of log L/L sun = 4.34 ± 0.36. The derived luminosity suggests that V445 Puppis probably contains a massive white dwarf accreting at high rate from a helium star companion making it part of a population of binary stars that potentially lead to supernova Ia explosions due to accumulation of helium-rich material on the surface of a massive white dwarf.

V2676 Oph: Estimating Physical Parameters of a Moderately Fast Nova

NASA Astrophysics Data System (ADS)

Raj, A.; Pavana, M.; Kamath, U. S.; Anupama, G. C.; Walter, F. M.

2018-03-01

Using our previously reported observations, we derive some physical parameters of the moderately fast nova V2676 Oph 2012 #1. The best-fit Cloudy model of the nebular spectrum obtained on 2015 May 8 shows a hot white dwarf source with TBB≍1.0×105 K having a luminosity of 1.0×1038 erg/s. Our abundance analysis shows that the ejecta are significantly enhanced relative to solar, He/H=2.14, O/H=2.37, S/H=6.62 and Ar/H=3.25. The ejecta mass is estimated to be 1.42×10-5 M⊙. The nova showed a pronounced dust formation phase after 90 d from discovery. The J-H and H-K colors were very large as compared to other molecule- and dust-forming novae in recent years. The dust temperature and mass at two epochs have been estimated from spectral energy distribution fits to infrared photometry.

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

PubMed

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.

Dependence of corneal stem/progenitor cells on ocular surface innervation.

PubMed

Ueno, Hiroki; Ferrari, Giulio; Hattori, Takaaki; Saban, Daniel R; Katikireddy, Kishore R; Chauhan, Sunil K; Dana, Reza

2012-02-21

Neurotrophic keratopathy (NK) is a corneal degeneration associated with corneal nerve dysfunction. It can cause corneal epithelial defects, stromal thinning, and perforation. However, it is not clear if and to which extent epithelial stem cells are affected in NK. The purpose of this study was to identify the relationship between corneolimbal epithelial progenitor/stem cells and sensory nerves using a denervated mouse model of NK. NK was induced in mice by electrocoagulation of the ophthalmic branch of the trigeminal nerve. The absence of corneal nerves was confirmed with β-III tubulin immunostaining and blink reflex test after 7 days. ATP-binding cassette subfamily G member 2 (ABCG2), p63, and hairy enhancer of split 1 (Hes1) were chosen as corneolimbal stem/progenitor cell markers and assessed in denervated mice versus controls by immunofluorescent microscopy and real-time PCR. In addition, corneolimbal stem/progenitor cells were detected as side population cells using flow cytometry, and colony-forming efficiency assay was performed to assess their function. ABCG2, p63, and Hes1 immunostaining were significantly decreased in denervated eyes after 7 days. Similarly, the expression levels of ABCG2, p63, K15, Hes1, and N-cadherin transcripts were also significantly decreased in denervated eyes. Stem/progenitor cells measured as side population from NK mice were decreased by approximately 75% compared with normals. In addition, the authors found a significant (P = 0.038) reduction in colony-forming efficiency of stem/progenitor cells harvested from denervated eyes. Corneolimbal stem/progenitor cells are significantly reduced after depletion of sensory nerves. The data suggest a critical role of innervation in maintaining stem cells and/or the stem cell niche.

Multiscale recurrence quantification analysis of order recurrence plots

NASA Astrophysics Data System (ADS)

Xu, Mengjia; Shang, Pengjian; Lin, Aijing

2017-03-01

In this paper, we propose a new method of multiscale recurrence quantification analysis (MSRQA) to analyze the structure of order recurrence plots. The MSRQA is based on order patterns over a range of time scales. Compared with conventional recurrence quantification analysis (RQA), the MSRQA can show richer and more recognizable information on the local characteristics of diverse systems which successfully describes their recurrence properties. Both synthetic series and stock market indexes exhibit their properties of recurrence at large time scales that quite differ from those at a single time scale. Some systems present more accurate recurrence patterns under large time scales. It demonstrates that the new approach is effective for distinguishing three similar stock market systems and showing some inherent differences.

TEAD and YAP regulate the enhancer network of human embryonic pancreatic progenitors.

PubMed

Cebola, Inês; Rodríguez-Seguí, Santiago A; Cho, Candy H-H; Bessa, José; Rovira, Meritxell; Luengo, Mario; Chhatriwala, Mariya; Berry, Andrew; Ponsa-Cobas, Joan; Maestro, Miguel Angel; Jennings, Rachel E; Pasquali, Lorenzo; Morán, Ignasi; Castro, Natalia; Hanley, Neil A; Gomez-Skarmeta, Jose Luis; Vallier, Ludovic; Ferrer, Jorge

2015-05-01

The genomic regulatory programmes that underlie human organogenesis are poorly understood. Pancreas development, in particular, has pivotal implications for pancreatic regeneration, cancer and diabetes. We have now characterized the regulatory landscape of embryonic multipotent progenitor cells that give rise to all pancreatic epithelial lineages. Using human embryonic pancreas and embryonic-stem-cell-derived progenitors we identify stage-specific transcripts and associated enhancers, many of which are co-occupied by transcription factors that are essential for pancreas development. We further show that TEAD1, a Hippo signalling effector, is an integral component of the transcription factor combinatorial code of pancreatic progenitor enhancers. TEAD and its coactivator YAP activate key pancreatic signalling mediators and transcription factors, and regulate the expansion of pancreatic progenitors. This work therefore uncovers a central role for TEAD and YAP as signal-responsive regulators of multipotent pancreatic progenitors, and provides a resource for the study of embryonic development of the human pancreas.

Cerebellar Granule Cell Replenishment Post-Injury by Adaptive Reprogramming of Nestin+ Progenitors

PubMed Central

Wojcinski, Alexandre; Lawton, Andrew K.; Bayin, N Sumru.; Lao, Zhimin; Stephen, Daniel N.; Joyner, Alexandra L.

2017-01-01

Regeneration of several organs involves adaptive reprogramming of progenitors, however, the intrinsic capacity of the developing brain to replenish lost cells remains largely unknown. In this study, we discovered that the developing cerebellum has unappreciated progenitor plasticity, since it undergoes near full growth and functional recovery following acute depletion of granule cells, the most plentiful neuron population in the brain. We demonstrate that following postnatal ablation of granule cell progenitors, Nestin-expressing progenitors (NEPs) specified during mid-embryogenesis to produce astroglia and interneurons, switch their fate and generate granule neurons in mice. Moreover, Hedgehog-signaling in two NEP populations is crucial not only for the compensatory replenishment of granule neurons but also to scale interneuron and astrocyte numbers. Thus we provide insights into the mechanisms underlying robustness of circuit formation in the cerebellum, and speculate that adaptive reprogramming of progenitors in other brain regions plays a greater role than appreciated in developmental regeneration. PMID:28805814

The Dwarf Nova SY Cancri and its Environs

NASA Astrophysics Data System (ADS)

Landolt, A. U.; Clem, J. L.

2018-06-01

Multicolor UBVRI photometry, collected intermittedly over a period of 22 years, is presented for the dwarf nova SY Cancri. Additional UBVRI photometry for a handful of sequence stars in the vicinity of SY Cancri is also presented.

Firework Nova

NASA Image and Video Library

2015-07-02

In Hollywood blockbusters, explosions are often among the stars of the show. In space, explosions of actual stars are a focus for scientists who hope to better understand their births, lives, and deaths and how they interact with their surroundings. Using NASA’s Chandra X-ray Observatory, astronomers have studied one particular explosion that may provide clues to the dynamics of other, much larger stellar eruptions. A team of researchers pointed the telescope at GK Persei, an object that became a sensation in the astronomical world in 1901 when it suddenly appeared as one of the brightest stars in the sky for a few days, before gradually fading away in brightness. Today, astronomers cite GK Persei as an example of a “classical nova,” an outburst produced by a thermonuclear explosion on the surface of a white dwarf star, the dense remnant of a Sun-like star.

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

PubMed

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.

Infrared spectroscopy of the remnant of Nova Sco 2014: a symbiotic star with too little circumstellar matter to decelerate the ejecta

NASA Astrophysics Data System (ADS)

Munari, U.; Banerjee, D. P. K.

2018-03-01

Pre-outburst 2MASS and WISE photometry of Nova Sco 2014 (V1534 Sco) has suggested the presence of a cool giant at the location of the nova in the sky. The spectral evolution recorded for the nova did not, however, support a direct partnership because no flash-ionized wind and no deceleration of the ejecta were observed, contrary to the behaviour displayed by other novae which erupted within symbiotic binaries like V407 Cyg or RS Oph. We have therefore obtained 0.8-2.5 μm spectra of the remnant of Nova Sco 2014 in order to ascertain if a cool giant is indeed present and if it is physically associated with the nova. The spectrum shows the presence of a M6III giant, reddened by E(B - V) = 1.20, displaying the typical and narrow emission-line spectrum of a symbiotic star, including He I 1.0830 μm with a deep P-Cyg profile. This makes Nova Sco 2014 a new member of the exclusive club of novae that erupt within a symbiotic binary. Nova Sco 2014 shows that a nova erupting within a symbiotic binary does not always come with a deceleration of the ejecta, contrary to the common belief. Many other similar systems may lay hidden in past novae, especially in those that erupted prior to the release of the 2MASS all-sky infrared survey, which could be profitably cross-matched now against them.

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

PubMed

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.

Mutually exclusive signaling signatures define the hepatic and pancreatic progenitor cell lineage divergence

PubMed Central

Rodríguez-Seguel, Elisa; Mah, Nancy; Naumann, Heike; Pongrac, Igor M.; Cerdá-Esteban, Nuria; Fontaine, Jean-Fred; Wang, Yongbo; Chen, Wei; Andrade-Navarro, Miguel A.; Spagnoli, Francesca M.

2013-01-01

Understanding how distinct cell types arise from multipotent progenitor cells is a major quest in stem cell biology. The liver and pancreas share many aspects of their early development and possibly originate from a common progenitor. However, how liver and pancreas cells diverge from a common endoderm progenitor population and adopt specific fates remains elusive. Using RNA sequencing (RNA-seq), we defined the molecular identity of liver and pancreas progenitors that were isolated from the mouse embryo at two time points, spanning the period when the lineage decision is made. The integration of temporal and spatial gene expression profiles unveiled mutually exclusive signaling signatures in hepatic and pancreatic progenitors. Importantly, we identified the noncanonical Wnt pathway as a potential developmental regulator of this fate decision and capable of inducing the pancreas program in endoderm and liver cells. Our study offers an unprecedented view of gene expression programs in liver and pancreas progenitors and forms the basis for formulating lineage-reprogramming strategies to convert adult hepatic cells into pancreatic cells. PMID:24013505

Distribution and Characterization of Progenitor Cells within the Human Filum Terminale

PubMed Central

Jaff, Nasren; Ossoinak, Amina; Jansson, Katarina; Hägerstrand, Anders; Johansson, Clas B.; Brundin, Lou; Svensson, Mikael

2011-01-01

Background Filum terminale (FT) is a structure that is intimately associated with conus medullaris, the most caudal part of the spinal cord. It is well documented that certain regions of the adult human central nervous system contains undifferentiated, progenitor cells or multipotent precursors. The primary objective of this study was to describe the distribution and progenitor features of this cell population in humans, and to confirm their ability to differentiate within the neuroectodermal lineage. Methodology/Principal Findings We demonstrate that neural stem/progenitor cells are present in FT obtained from patients treated for tethered cord. When human or rat FT-derived cells were cultured in defined medium, they proliferated and formed neurospheres in 13 out of 21 individuals. Cells expressing Sox2 and Musashi-1 were found to outline the central canal, and also to be distributed in islets throughout the whole FT. Following plating, the cells developed antigen profiles characteristic of astrocytes (GFAP) and neurons (β-III-tubulin). Addition of PDGF-BB directed the cells towards a neuronal fate. Moreover, the cells obtained from young donors shows higher capacity for proliferation and are easier to expand than cells derived from older donors. Conclusion/Significance The identification of bona fide neural progenitor cells in FT suggests a possible role for progenitor cells in this extension of conus medullaris and may provide an additional source of such cells for possible therapeutic purposes. Filum terminale, human, progenitor cells, neuron, astrocytes, spinal cord. PMID:22096566

Single progenitor model for GW150914 and GW170104

NASA Astrophysics Data System (ADS)

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.

Role of medullary progenitor cells in epithelial cell migration and proliferation

PubMed Central

Chen, Dong; Chen, Zhiyong; Zhang, Yuning; Park, Chanyoung; Al-Omari, Ahmed

2014-01-01

This study is aimed at characterizing medullary interstitial progenitor cells and to examine their capacity to induce tubular epithelial cell migration and proliferation. We have isolated a progenitor cell side population from a primary medullary interstitial cell line. We show that the medullary progenitor cells (MPCs) express CD24, CD44, CXCR7, CXCR4, nestin, and PAX7. MPCs are CD34 negative, which indicates that they are not bone marrow-derived stem cells. MPCs survive >50 passages, and when grown in epithelial differentiation medium develop phenotypic characteristics of epithelial cells. Inner medulla collecting duct (IMCD3) cells treated with conditioned medium from MPCs show significantly accelerated cell proliferation and migration. Conditioned medium from PGE2-treated MPCs induce tubule formation in IMCD3 cells grown in 3D Matrigel. Moreover, most of the MPCs express the pericyte marker PDGFR-b. Our study shows that the medullary interstitium harbors a side population of progenitor cells that can differentiate to epithelial cells and can stimulate tubular epithelial cell migration and proliferation. The findings of this study suggest that medullary pericyte/progenitor cells may play a critical role in collecting duct cell injury repair. PMID:24808539

ASASSN-18ca: Discovery of A Probable Nova in M31

NASA Astrophysics Data System (ADS)

Brimacombe, J.; Vallely, P.; Stanek, K. Z.; Kochanek, C. S.; Brown, J. S.; Shields, J.; Thompson, T. A.; Shappee, B. J.; Holoien, T. W.-S.; Prieto, J. L.; Bersier, D.; Dong, Subo; Bose, S.; Chen, Ping; Stritzinger, M.; Holmbo, S.

2018-02-01

During the ongoing All Sky Automated Survey for SuperNovae (ASAS-SN or "Assassin"), using data from the quadruple 14-cm "Leavitt" telescope in Fort Davis, Texas, we discovered a new transient source, most likely a nova, in the nearby galaxy M31. ASASSN-18ca (AT 2018pp) was discovered in images obtained on UT 2018-02-08.07 at g 16.5 mag. We do not detect (g > 18.6) the object in images taken on UT 2018-02-06.12 and before.

Inhibition of cyclooxygenase (COX)-2 affects endothelial progenitor cell proliferation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Colleselli, Daniela; Bijuklic, Klaudija; Mosheimer, Birgit A.

2006-09-10

Growing evidence indicates that inducible cyclooxygenase-2 (COX-2) is involved in the pathogenesis of inflammatory disorders and various types of cancer. Endothelial progenitor cells recruited from the bone marrow have been shown to be involved in the formation of new vessels in malignancies and discussed for being a key point in tumour progression and metastasis. However, until now, nothing is known about an interaction between COX and endothelial progenitor cells (EPC). Expression of COX-1 and COX-2 was detected by semiquantitative RT-PCR and Western blot. Proliferation kinetics, cell cycle distribution and rate of apoptosis were analysed by MTT test and FACS analysis.more » Further analyses revealed an implication of Akt phosphorylation and caspase-3 activation. Both COX-1 and COX-2 expression can be found in bone-marrow-derived endothelial progenitor cells in vitro. COX-2 inhibition leads to a significant reduction in proliferation of endothelial progenitor cells by an increase in apoptosis and cell cycle arrest. COX-2 inhibition leads further to an increased cleavage of caspase-3 protein and inversely to inhibition of Akt activation. Highly proliferating endothelial progenitor cells can be targeted by selective COX-2 inhibition in vitro. These results indicate that upcoming therapy strategies in cancer patients targeting COX-2 may be effective in inhibiting tumour vasculogenesis as well as angiogenic processes.« less

The Nova-Canton Trough and the Late Cretaceous evolution of the central Pacific

NASA Astrophysics Data System (ADS)

Joseph, Devorah; Taylor, Brain; Shor, Alexander N.; Yamazaki, Toshitsugu

Free-air gravity anomalies derived from satellite altimetry data show that the major Pacific fracture zones, from the Pau to Marquesas, are co-polar about an Euler pole located at 150.5°W, 34.6°S for the period preceding chron 33 and including a large portion of the Cretaceous Normal Superchron. They also show continuity of the Clipperton Fracture Zone through the Line Islands to the Nova-Canton ridge and trough; this Canton-Clipperton trend is co-polar to the same pole. Sidescan-sonar and bathymetry data in the Nova-Canton Trough region reveal N140°E-striking abyssal hill topography south of the N70°E-striking structures of the Nova-Canton Trough and crustal fabric striking normal to the trough (N160°E) to the north. We conclude that the Nova-Canton Trough is the Middle Cretaceous extension of the Clipperton Fracture Zone. We propose that the anomalous depths (7000-8400 m) of the trough between 167°30'-168°30'W are the result of a complex plate reorganization. Conjugate magnetic anomaly lineations M1-M3 in the Phoenix lineations between the Central Pacific Fracture Zone and the Phoenix Fracture Zone and the absence of lineations younger than anomaly M3 west of the Phoenix Fracture Zone suggest that spreading may have gradually ceased along the Pacific-Phoenix system from west to east. We infer that the remaining active segment of the Pacific-Phoenix spreading system after anomaly M1 time was the easternmost section of the Phoenix lineations. At ˜M0 time, the Pacific-Phoenix spreading axis stretched from lineated bathymetric depressions lying between 180°W and the Phoenix Islands to ˜168°W and included the western deep of the Nova-Canton Trough. We hypothesize that accretion terminated on the Pacific-Phoenix spreading axis shortly after M0 time and that the absence of an M0 isochron in the region between the eastern Phoenix lineations and the Nova-Canton Trough, or along the Nova-Canton Trough itself, may be due to a decrease in spreading rate prior to

Nova Sco 2016 No. 2 = PNV J17225112-3158349 = ASASSN-16kd

NASA Astrophysics Data System (ADS)

Waagen, Elizabeth O.

2016-09-01

AAVSO Alert Notice 550 announces the independent discovery of Nova Sco 2016 No. 2 = ASASSN-16kd = PNV J17225112-3158349 = V1656 Sco by Shigehisa Fujikawa (Kan'onji, Kagawa, Japan) at unfiltered CCD magnitude 11.6 on 2016 September 06.481 UT; and by ASAS-SN (Stanek et al., ATel #9469) at 12.13 V on 2016 September 06.00 UT. Spectroscopy indicating that Nova Sco 2016 No. 2 is a highly reddened classical Fe II-type nova was obtained by Arai and Honda (CBET 4320); by Bohlsen (ATel #9477); by Bersier et al. (ATel #9478); and by Prieto et al. (ATel #9479). Finder charts with sequence may be created using the AAVSO Variable Star Plotter (https://www.aavso.org/vsp). Observations should be submitted to the AAVSO International Database. See full Alert Notice for more details.

Very high-energy γ -ray observations of novae and dwarf novae with the MAGIC telescopes

DOE PAGES

Ahnen, M. L.

2015-10-01

In the last five years the Fermi Large Area Telescope (LAT) instrument detected GeV γ-ray emission from five novae. The GeV emission can be interpreted in terms of an inverse Compton process of electrons accelerated in a shock. In this case it is expected that protons in the same conditions can be accelerated to much higher energies. Consequently they may produce a second component in the γ-ray spectrum at TeV energies.

ASASSN-16eg: New candidate for a long-period WZ Sge-type dwarf nova

NASA Astrophysics Data System (ADS)

Wakamatsu, Yasuyuki; Isogai, Keisuke; Kimura, Mariko; Kato, Taichi; Vanmunster, Tonny; Stone, Geoff; Tordai, Tamás; Richmond, Michael; Miller, Ian; Oksanen, Arto; Itoh, Hiroshi; Akazawa, Hidehiko; Kiyota, Seiichiro; de Miguel, Enrique; Pavlenko, Elena P.; Antonyuk, Kirill A.; Antonyuk, Oksana I.; Neustroev, Vitaly V.; Sjoberg, George; Dubovsky, Pavol A.; Pickard, Roger D.; Nogami, Daisaku

2017-12-01

We report on our photometric observations of the 2016 superoutburst of ASASSN-16eg. This object showed a WZ Sge-type superoutburst with prominent early superhumps with a period of 0.075478(8) d and a post-superoutburst rebrightening. During the superoutburst plateau, it showed ordinary superhumps with a period of 0.077880(3) d and a period derivative of 10.6(1.1) × 10-5 in stage B. The orbital period (Porb), which is almost identical with the period of the early superhumps, is exceptionally long for a WZ Sge-type dwarf nova. The mass ratio (q = M2/M1) estimated from the period of developing (stage A) superhumps is 0.166(2), which is also too large for a WZ Sge-type dwarf nova. This suggests that the 2 : 1 resonance can be reached in such high-q systems, contrary to our expectation. Such conditions are considered to be achieved if the mass-transfer rate is much lower than those in typical SU UMa-type dwarf novae that have comparable orbital periods to ASASSN-16eg, and a resultant accumulation of a large amount of matter on the disk is realized at the onset of an outburst. We examined other candidates for long-period WZ Sge-type dwarf novae for their supercycles, which are considered to reflect the mass-transfer rate, and found that V1251 Cyg and RZ Leo have longer supercycles than those of other WZ Sge-type dwarf novae. This result indicates that these long-period objects including ASASSN-16eg have a low mass-transfer rate in comparison to other WZ Sge-type dwarf novae.

Role of progenitor cell producing normal vagina by metaplasia in laparoscopic peritoneal vaginoplasty

PubMed Central

Mhatre, Pravin N.; Narkhede, Hemraj R.; Pawar, P. Amol; Mhatre, P. Jyoti; Kumar, Das Dhanjit

2016-01-01

CONTEXT: Host of vaginoplasty techniques have been described. None has been successful in developing normal vagina. Laparoscopic peritoneal vaginoplasty (LPV) is performed in Mayer–Rokitansky–Küster–Hauser syndrome (MRKHS) culminating in normal vagina. AIMS: This study aims to confirm normal development of neovagina by anatomical and functional parameters of histology, cytology, and ultrasonography (USG) in LPV. To identify peritoneal progenitor cell by OCT4/SOX2 markers. To demonstrate the metaplastic conversion of peritoneum to neovagina and the progenitor cell concentration, distribution pattern. SETTINGS AND DESIGN: This is prospective experimental study, conducted at teaching hospital and private hospital. SUBJECTS AND METHODS: Fifteen women of MRKHS underwent LPV followed by histology, cytology, two-/three-dimensional USG of neovagina. Four women underwent peritoneal biopsy for identification of progenitor cells with OCT4/SOX2 markers. One patient underwent serial biopsies for 4 weeks for histology and progenitor cell immunohistochemistry. RESULTS: Normal vaginal histology and cytology were apparent. USG of neovagina showed normal appearance and blood flow. Two peritoneal samples confirmed the presence of progenitor cells. Serial biopsies demonstrated the epithelial change from single to multilayer with stromal compaction and neoangiogenesis. The progenitor cells concentration and different distribution patterns were described using SOX2/OCT4 markers. CONCLUSIONS: We have shown successful peritoneal metaplastic conversion to normal vagina in LPV. The progenitor cell was identified in normal peritoneum using SOX2/OCT4 markers. The progenitor cell concentration and pattern were demonstrated at various stages of neovaginal development. PMID:28216908

Terra Nova Bay Polynya, Antarctica

NASA Technical Reports Server (NTRS)

2007-01-01

In Terra Nova Bay, off the Scott Coast of Victoria Land, Antarctica, a large pocket of open water persists throughout most of the Southern Hemisphere winter, even while most of the rest of the Antarctic coastline is firmly embraced by the frozen Southern Ocean. This pocket of open water--a polynya--results from exceptionally strong winds that blow downslope from the Trans-Antarctic Mountains. These fierce katabatic winds drive the sea ice eastward. Since the dominant ice drift pattern in the area is northward, the Drygalski Ice Tongue prevents the bay from being re-populated with sea ice. This image of the Terra Nova Bay polynya was captured by the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's Aqua satellite on October 16, 2007. Sea ice sits over the Ross Sea like a cracked and crumbling windshield. Blue-tinged glaciers flow down from the Trans-Antarctic Mountains. Although glaciers can appear blue because of melt water, they can also get that tint when the wind scours and polishes the ice surface. Given the strength of the katabatic winds along this part of the Antarctic coast, it is likely that the blue color of these glaciers is a result of their having been swept clean of snow. The large image has a spatial resolution (level of detail) of 250 meters per pixel.

Fermi-LAT Gamma-Ray Detections of Classical Novae V1369 Centauri 2013 and V5668 Sagittarii 2015

NASA Astrophysics Data System (ADS)

Cheung, C. C.; Jean, P.; Shore, S. N.; Stawarz, Ł.; Corbet, R. H. D.; Knödlseder, J.; Starrfield, S.; Wood, D. L.; Desiante, R.; Longo, F.; Pivato, G.; Wood, K. S.

2016-08-01

We report the Fermi Large Area Telescope (LAT) detections of high-energy (>100 MeV) γ-ray emission from two recent optically bright classical novae, V1369 Centauri 2013 and V5668 Sagittarii 2015. At early times, Fermi target-of-opportunity observations prompted by their optical discoveries provided enhanced LAT exposure that enabled the detections of γ-ray onsets beginning ˜2 days after their first optical peaks. Significant γ-ray emission was found extending to 39-55 days after their initial LAT detections, with systematically fainter and longer-duration emission compared to previous γ-ray-detected classical novae. These novae were distinguished by multiple bright optical peaks that encompassed the time spans of the observed γ-rays. The γ-ray light curves and spectra of the two novae are presented along with representative hadronic and leptonic models, and comparisons with other novae detected by the LAT are discussed.

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

PubMed Central

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

2016-01-01

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. PMID:27827819

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

PubMed

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.

Analyses of cell surface molecules on hepatic stem/progenitor cells in mouse fetal liver.

PubMed

Kakinuma, Sei; Ohta, Haruhiko; Kamiya, Akihide; Yamazaki, Yuji; Oikawa, Tsunekazu; Okada, Ken; Nakauchi, Hiromitsu

2009-07-01

Hepatic stem/progenitor cells possess active proliferative ability and the capacity for differentiation into hepatic and cholangiocytic lineages. Our group and others have shown that a prospectively defined population in mid-gestational fetal liver contains hepatic stem/progenitor cells. However, the phenotypes of such cells are incompletely elucidated. We analyzed the profile of cell-surface molecules on primary hepatic stem/progenitor cells. Expression of cell surface molecules on primary hepatic stem/progenitor cells in mouse mid-gestational fetal liver was analyzed using flow cytometric multicolor analyses and colony-formation assays. The potential of the cells for liver repopulation was examined by transplantation assay. We found that CD13 (aminopeptidase N) was detected on the cells of the previously reported (Dlk/Pref-1(+)) hepatic stem/progenitor fraction. Colony-formation assays revealed that the CD13(+) fraction, compared with the Dlk(+) fraction, of non-hematopoietic cells in fetal liver was enriched in hepatic stem/progenitor cells. Transplantation assay showed the former fraction exhibited repopulating potential in regenerating liver. Moreover, flow cytometric analysis for over 90 antigens demonstrated enrichment of hepatic stem/progenitor cells using several positive selection markers, including (hitherto unknown) CD13, CD73, CD106, and CD133. Our data indicated that CD13 is a positive selection marker for hepatic stem/progenitor cells in mid-gestational fetal liver.

Cataclysmic variables and related objects

NASA Technical Reports Server (NTRS)

Hack, Margherita; Ladous, Constanze; Jordan, Stuart D. (Editor); Thomas, Richard N. (Editor); Goldberg, Leo; Pecker, Jean-Claude

1993-01-01

This volume begins with an introductory chapter on general properties of cataclysmic variables. Chapters 2 through 5 of Part 1 are devoted to observations and interpretation of dwarf novae and nova-like stars. Chapters 6 through 10, Part 2, discuss the general observational properties of classical and recurrent novae, the theoretical models, and the characteristics and models for some well observed classical novae and recurrent novae. Chapters 11 through 14 of Part 3 are devoted to an overview of the observations of symbiotic stars, to a description of the various models proposed for explaining the symbiotic phenomenon, and to a discussion of a few selected objects, respectively. Chapter 15 briefly examines the many unsolved problems posed by the observations of the different classes of cataclysmic variables and symbiotic stars.

Light-curve Analysis of Neon Novae

NASA Astrophysics Data System (ADS)

Hachisu, Izumi; Kato, Mariko

2016-01-01

We analyzed light curves of five neon novae, QU Vul, V351 Pup, V382 Vel, V693 CrA, and V1974 Cyg, and determined their white dwarf (WD) masses and distance moduli on the basis of theoretical light curves composed of free-free and photospheric emission. For QU Vul, we obtained a distance of d ˜ 2.4 kpc, reddening of E(B - V) ˜ 0.55, and WD mass of MWD = 0.82-0.96 {M}⊙ . This suggests that an oxygen-neon WD lost a mass of more than ˜ 0.1 {M}⊙ since its birth. For V351 Pup, we obtained d˜ 5.5 {{kpc}}, E(B-V)˜ 0.45, and {M}{{WD}}=0.98-1.1 {M}⊙ . For V382 Vel, we obtained d˜ 1.6 {{kpc}}, E(B-V)˜ 0.15, and {M}{{WD}}=1.13-1.28 {M}⊙ . For V693 CrA, we obtained d˜ 7.1 {{kpc}}, E(B-V)˜ 0.05, and {M}{{WD}}=1.15-1.25 {M}⊙ . For V1974 Cyg, we obtained d˜ 1.8 {{kpc}}, E(B-V)˜ 0.30, and {M}{{WD}}=0.95-1.1 {M}⊙ . For comparison, we added the carbon-oxygen nova V1668 Cyg to our analysis and obtained d˜ 5.4 {{kpc}}, E(B-V)˜ 0.30, and {M}{{WD}}=0.98-1.1 {M}⊙ . In QU Vul, photospheric emission contributes 0.4-0.8 mag at most to the optical light curve compared with free-free emission only. In V351 Pup and V1974 Cyg, photospheric emission contributes very little (0.2-0.4 mag at most) to the optical light curve. In V382 Vel and V693 CrA, free-free emission dominates the continuum spectra, and photospheric emission does not contribute to the optical magnitudes. We also discuss the maximum magnitude versus rate of decline relation for these novae based on the universal decline law.

Identification, Characterization, and Utilization of Adult Meniscal Progenitor Cells

DTIC Science & Technology

2015-09-01

pluripotent stem cells for osteoarthritis drug screening . Arthritis Rheumatol. 66, 3062–3072. Xia, Y., Zheng, S., Bidthanapally, A., 2008. Depth-dependent...the development of knee osteoarthritis (OA). New treatments centered on the stem /progenitor cell population resident within the adult meniscus will be...biology to develop a profile of repair cells in the adult meniscus, track meniscal stem /progenitor cell (MSPC) behavior within meniscus as function of

TOX3 regulates neural progenitor identity.

PubMed

Sahu, Sanjeeb Kumar; Fritz, Alina; Tiwari, Neha; Kovacs, Zsuzsa; Pouya, Alireza; Wüllner, Verena; Bora, Pablo; Schacht, Teresa; Baumgart, Jan; Peron, Sophie; Berninger, Benedikt; Tiwari, Vijay K; Methner, Axel

2016-07-01

The human genomic locus for the transcription factor TOX3 has been implicated in susceptibility to restless legs syndrome and breast cancer in genome-wide association studies, but the physiological role of TOX3 remains largely unknown. We found Tox3 to be predominantly expressed in the developing mouse brain with a peak at embryonic day E14 where it co-localizes with the neural stem and progenitor markers Nestin and Sox2 in radial glia of the ventricular zone and intermediate progenitors of the subventricular zone. Tox3 is also expressed in neural progenitor cells obtained from the ganglionic eminence of E15 mice that express Nestin, and it specifically binds the Nestin promoter in chromatin immunoprecipitation assays. In line with this, over-expression of Tox3 increased Nestin promoter activity, which was cooperatively enhanced by treatment with the stem cell self-renewal promoting Notch ligand Jagged and repressed by pharmacological inhibition of Notch signaling. Knockdown of Tox3 in the subventricular zone of E12.5 mouse embryos by in utero electroporation of Tox3 shRNA revealed a reduced Nestin expression and decreased proliferation at E14 and a reduced migration to the cortical plate in E16 embryos in electroporated cells. Together, these results argue for a role of Tox3 in the development of the nervous system. Copyright © 2016 Elsevier B.V. All rights reserved.

Dependence of Corneal Stem/Progenitor Cells on Ocular Surface Innervation

PubMed Central

Ueno, Hiroki; Ferrari, Giulio; Hattori, Takaaki; Saban, Daniel R.; Katikireddy, Kishore R.; Chauhan, Sunil K.

2012-01-01

Purpose. Neurotrophic keratopathy (NK) is a corneal degeneration associated with corneal nerve dysfunction. It can cause corneal epithelial defects, stromal thinning, and perforation. However, it is not clear if and to which extent epithelial stem cells are affected in NK. The purpose of this study was to identify the relationship between corneolimbal epithelial progenitor/stem cells and sensory nerves using a denervated mouse model of NK. Methods. NK was induced in mice by electrocoagulation of the ophthalmic branch of the trigeminal nerve. The absence of corneal nerves was confirmed with β-III tubulin immunostaining and blink reflex test after 7 days. ATP-binding cassette subfamily G member 2 (ABCG2), p63, and hairy enhancer of split 1 (Hes1) were chosen as corneolimbal stem/progenitor cell markers and assessed in denervated mice versus controls by immunofluorescent microscopy and real-time PCR. In addition, corneolimbal stem/progenitor cells were detected as side population cells using flow cytometry, and colony-forming efficiency assay was performed to assess their function. Results. ABCG2, p63, and Hes1 immunostaining were significantly decreased in denervated eyes after 7 days. Similarly, the expression levels of ABCG2, p63, K15, Hes1, and N-cadherin transcripts were also significantly decreased in denervated eyes. Stem/progenitor cells measured as side population from NK mice were decreased by approximately 75% compared with normals. In addition, the authors found a significant (P = 0.038) reduction in colony-forming efficiency of stem/progenitor cells harvested from denervated eyes. Conclusions. Corneolimbal stem/progenitor cells are significantly reduced after depletion of sensory nerves. The data suggest a critical role of innervation in maintaining stem cells and/or the stem cell niche. PMID:22232434

NuMI Flux Predictions for NOvA and MINERvA

NASA Astrophysics Data System (ADS)

Aliaga Soplin, Leonidas; Nova Collaboration; Minerva Collaboration

2017-01-01

The determination of the neutrino flux in any conventional neutrino beam presents a challenge for the current and future short and long baseline neutrino experiments. The uncertainties associated with the production and attenuation of the hadrons in the beamline materials along with those associated with the beam optics have a big effect in the knowledge of the flux. For experiments like MINERvA and NOvA, understanding the flux is crucial since it enters directly into every neutrino-nucleus cross-section measurement. The majority of this work involves predicting the neutrino flux using dedicated hadron production measurements from hadron-nucleus collisions. The predictions at the MINERvA and NOvA near detectors are presented as well as the results of incorporating in-situ MINERvA data that can provide additional constraints. These results have been fully implemented in MINERvA and they are currently use for its cross-section analysis. The implementation for NoVA is underway. The procedure and conclusions of this work will have a big impact on future hadron production experiments and on determining the flux for the upcoming DUNE experiment.

Effects of transplanted circulating endothelial progenitor cells and platelet microparticles in atherosclerosis development.

PubMed

Georgescu, Adriana; Alexandru, Nicoleta; Andrei, Eugen; Dragan, Emanuel; Cochior, Daniel; Dias, Sérgio

2016-08-01

Atherosclerosis is an inflammatory disease, in which risk factors such as hyperlipidemia and hypertension affect the arterial endothelium, resulting in dysfunction, cell damage or both. The number of circulating endothelial progenitor cells and microparticles provides invaluable outcome prediction for atherosclerosis disease. However, evidence for the therapeutic potential of endothelial progenitor cells and microparticles in atherosclerosis development is limited. Our study was designed to investigate the possible protective role of a cell therapy-based approach, using endothelial progenitor cells and the dual behaviour of circulating platelet microparticles, on atherosclerosis development in hypertensive-hypercholesterolemic hamster model. Consequently, control hamsters received four intravenous inoculations of: (1) 1×10(5) endothelial progenitor cells of healthy origins in one dose per month, during four months of diet-induced atherosclerosis, and after hypertensive-hypercholesterolemic diet for further four months; (2) in a second set of experiments, 1×10(5) endothelial progenitor cells of healthy origins or/and 1×10(5) platelet microparticles of atherosclerotic origins were inoculated every other month during hypertensive-hypercholesterolemic diet. Endothelial progenitor cell treatment had the following effects: (1) re-established plasmatic parameters: cholesterol and triglyceride concentrations, blood pressure, heart rate, cytokine and chemokine profiles, platelet microparticle pro-thrombotic activity and endothelial progenitor cell paracrine activity reflected by cytokine/chemokine detection; (2) reduced lipid, macrophage and microparticle accumulation in liver; (3) reduced atherosclerosis development, revealed by decreased lipid, macrophage and microparticle content of arterial wall; (4) induced the recruitment and incorporation of endothelial progenitor cells into liver and arterial wall; (5) improved arterial dysfunction by increasing contraction and

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

PubMed

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.

Isospin mixing reveals 30P(p, γ) 31S resonance influencing nova nucleosynthesis

DOE PAGES

Bennett, M. B.; Wrede, C.; Brown, B. A.; ...

2016-03-08

Here, the thermonuclear 30P(p, γ) 31S reaction rate is critical for modeling the final elemental and isotopic abundances of ONe nova nucleosynthesis, which affect the calibration of proposed nova thermometers and the identification of presolar nova grains, respectively. Unfortunately, the rate of this reaction is essentially unconstrained experimentally, because the strengths of key 31S proton capture resonance states are not known, largely due to uncertainties in their spins and parities. Using the β decay of 31Cl, we have observed the β-delayed γ decay of a 31S state at E x = 6390.2(7) keV, with a 30P(p, γ) 31S resonance energymore » of E r = 259.3(8) keV, in the middle of the 30P(p, γ) 31S Gamow window for peak nova temperatures. This state exhibits isospin mixing with the nearby isobaric analog state at E x = 6279.0(6) keV, giving it an unambiguous spin and parity of 3/2 + and making it an important l = 0 resonance for proton capture on 30P.« less

The electrification of Nova Scotia, 1884--1973: Technological modernization as a response to regional disparity

NASA Astrophysics Data System (ADS)

King, Lionel Bradley

This dissertation investigates local attempts to use technology as a force for regional rehabilitation in the economically-depressed Maritime region of Canada. At the time of Confederation in 1867, the Maritime province of Nova Scotia was prosperous, progressive, and cultured. By the end of the 1910s, the province had entered a long period of economic and social decline. Recent historiography has shown that, far from passively accepting their fate, Nova Scotians and other Maritimers, actively resisted marginalization with political, cultural, or social action. The thesis expands upon that literature by exploring technology-based strategies of provincial rehabilitation using Thomas P. Hughes's systems perspective and David E. Nye's semiotic approach. In doing so, it applies methods from the social constructivist school of the history of technology to the larger concerns of Maritime Canadian historiography. In large part, the North American culture of technology determined the ways in which Nova Scotians applied technological solutions to provincial concerns. Technology has long been central to the Western idea of progress. As the "high technology" of the late nineteenth and early twentieth centuries, electricity reinforced that view: its ephemeral nature and silent efficiency led people to endow it with transformative, even mystical, powers. As a result, Nova Scotians, adopted a program of electrical modernization in the late 1910s as a remedy for regional disparity. The Nova Scotia government's first step was the creation of an Ontario-style hydroelectric commission designed to bring order to the province's fragmented and inefficient electrical network. Over the next few decades, the Nova Scotia Power Commission implemented rural electrification, home modernization, and regional system-building models that had already proven successful in Ontario and the United States. The system-building philosophies behind these programs were adapted to local conditions and

The Orbital Period of the Classical Nova V458 Vul

NASA Astrophysics Data System (ADS)

Goranskij, V. P.; Metlova, N. V.; Barsukova, E. A.; Burenkov, A. N.; Soloviev, V. Ya.

2008-07-01

Classical nova V458 Vul (N Vul 2007 No.1) was detected as a supersoft X-ray source (SSS) by the Swift XRT several times in the time range between 2007 October 18 and 2008 June 18 (J. Drake et al., ATel #1246 and #1603). Our V photometry shows the plateau in the light curve continued since January till June 2008. This feature accompanies usually the SSS phases in some classical novae. The fragmentary monitoring during plateau shows night- to-night variability with the amplitudes between 1.2 and 0.4 mag and rapid variability by 0.1 mag in the time scale of an hour.

New sidescan sonar and gravity evidence that the Nova-Canton Trough is a fracture zone

NASA Astrophysics Data System (ADS)

Joseph, Devorah; Taylor, Brian; Shor, Alexander N.

1992-05-01

A 1990 sidescan sonar survey in the eastern region of the Nova-Canton Trough mapped 138°-striking abyssal-hill fabric trending into 70°-striking trough structures. The location and angle of intersection of the abyssal hills with the eastern Nova-Canton Trough effectively disprove a spreading-center origin of this feature. Free-air gravity anomalies derived from satellite altimetry data show continuity, across the Line Islands, of the Nova-Canton Trough with the Clipperton Fracture Zone. The Canton-Clipperton trend is copolar, about a pole at 30°S, 152°W, with other coeval Pacific-Farallon fracture-zone segments, from the Pau to Marquesas fracture zones. This copolarity leads us to postulate a Pacific-Farallon spreading pattern for the magnetic quiet zone region north and east of the Manihiki Plateau, with the Nova-Canton Trough originating as a transform fault in this system.

Increased Cardiac Myocyte Progenitors in Failing Human Hearts

PubMed Central

Kubo, Hajime; Jaleel, Naser; Kumarapeli, Asangi; Berretta, Remus M.; Bratinov, George; Shan, Xiaoyin; Wang, Hongmei; Houser, Steven R.; Margulies, Kenneth B.

2009-01-01

Background Increasing evidence, derived mainly from animal models, supports the existence of endogenous cardiac renewal and repair mechanisms in adult mammalian hearts that could contribute to normal homeostasis and the responses to pathological insults. Methods and Results Translating these results, we isolated small c-kit+ cells from 36 of 37 human hearts using primary cell isolation techniques and magnetic cell sorting techniques. The abundance of these cardiac progenitor cells was increased nearly 4-fold in patients with heart failure requiring transplantation compared with nonfailing controls. Polychromatic flow cytometry of primary cell isolates (<30 μm) without antecedent c-kit enrichment confirmed the increased abundance of c-kit+ cells in failing hearts and demonstrated frequent coexpression of CD45 in these cells. Immunocytochemical characterization of freshly isolated, c-kit–enriched human cardiac progenitor cells confirmed frequent coexpression of c-kit and CD45. Primary cardiac progenitor cells formed new human cardiac myocytes at a relatively high frequency after coculture with neonatal rat ventricular myocytes. These contracting new cardiac myocytes exhibited an immature phenotype and frequent electric coupling with the rat myocytes that induced their myogenic differentiation. Conclusions Despite the increased abundance and cardiac myogenic capacity of cardiac progenitor cells in failing human hearts, the need to replace these organs via transplantation implies that adverse features of the local myocardial environment overwhelm endogenous cardiac repair capacity. Developing strategies to improve the success of endogenous cardiac regenerative processes may permit therapeutic myocardial repair without cell delivery per se. PMID:18645055

Observations of Core-Collapse Supernovae with Candidate Progenitor Identifications.

NASA Astrophysics Data System (ADS)

Elias-Rosa, Nancy; van Dyk, Schuyler D.

2010-02-01

Supernovae (SNe) have a profound effect on galaxies. They are clearly very important events deserving of intense study. Yet, even with nearly 4000 historical SNe, we know relatively little about the stars which give rise to these powerful explosions. The main limitation has been the lack of spatial resolution in pre-SN imaging data. However, since 1999 our team has been at the vanguard of directly identifying the progenitor stars of Core-Collapse (CC-) SNe in Hubble Space Telescope (HST) images. From this exciting new line of study, the emerging trend from a growing number of detections for Type II-Plateau SNe is that their progenitors appear to be relatively low mass (8-20 M_⊙) red supergiants, although more cases are needed. The nature of the progenitors of Type Ib/c SNe, a subset of which are associated with the amazing gamma-ray bursts, remains ambiguous. In HST Cycle 17 we are expecting to trigger our ToO observations using ACS/HRC (GO-11575) on 4 nearby (within 17 Mpc) CC-SNe, to determine the identities of the progenitors. It is conceivable that at least half of these will be discovered in the southern hemisphere. To fully characterize the progenitor star, we require detailed light curves and spectral evolution for the SNe, starting soon after discovery, to estimate the reddening to the SNe, characterize the overall luminosity and obtain a better understanding of the physics of the event. Therefore, to support the HST work, we are requesting up to 2 ToO triggers during semester 2010A, where we will monitor the SNe in BVRI with ANDICAM, and the 300 l/mm grating with the Goodman.

Hydrodynamic Simulations of Classical Nova explosions: predictions of 7Be and 7Li production and the growth to the Chandrasekhar Limit

NASA Astrophysics Data System (ADS)

Starrfield, Sumner; Bose, Maitrayee; Iliadis, Christian; Hix, William R.; Wagner, R. Mark; Woodward, Charles E.; Jose', Jordi; Hernanz, Margarita

2018-01-01

We have continued our studies of Classical Nova explosions by following the evolution of thermonuclear runaways (TNRs) on Carbon Oxygen white dwarfs (WDs). We have varied both the mass of the WD and the composition of the accreted material. We now rely on the results of multi-D studies of TNRs in WDs that accrete only Solar matter. They find that mixing with the core occurs after the TNR is well underway, reaching enrichment levels in agreement with observations of the ejecta abundances. We, therefore, accrete only Solar matter with NOVA (our 1-D, fully implicit, hydro code) until the TNR is initiated and then switch the accreted composition to a mixed composition: either 25% core and 75% Solar or 50% core and 50% Solar. Because the amount of accreted material is inversely proportional to the initial 12C abundance, by accreting Solar matter the amount of material taking part in the outburst is larger than if we had used mixed material from the beginning. We follow the TNR through the peak and tabulate the amount of ejected gases, their velocities and abundances. We also predict the amount of 7Li and 7Be produced and ejected by the explosion and compare our predictions to the observations in a companion poster describing the LBT measurements of 7Li in V5668 Sgr. We also compare our abundance predictions to those measured in pre-solar grains that may arise from Classical Nova explosions. Our predictions are also compared to results with SHIVA (Josè and Hernanz). Finally, many of these simulations eject significantly less mass than accreted and, therefore, the WD is growing in mass toward the Chandrasekhar Limit. This suggests that the single degenerate scenario is still a viable option for SN Ia progenitors. This work was supported in part by NASA under the Astrophysics Theory Program grant 14-ATP14-0007 and the U.S. DOE under Contract No. DE-FG02- 97ER41041. SS acknowledges partial support from NASA and HST grants to ASU and WRH is supported by the U.S. Department

Fermi-LAT gamma ray detections of classical novae V1369 centauri 2013 and V5668 Sagittarii 2015

DOE PAGES

Cheung, C. C.; Jean, P.; Shore, S. N.; ...

2016-07-27

Here, we report the Fermi Large Area Telescope (LAT) detections of high-energy (>100 MeV) γ-ray emission from two recent optically bright classical novae, V1369 Centauri 2013 and V5668 Sagittarii 2015. Furthermore, at early times, Fermi target-of-opportunity observations prompted by their optical discoveries provided enhanced LAT exposure that enabled the detections of γ-ray onsets beginning ~2 days after their first optical peaks. Significant γ-ray emission was found extending to 39–55 days after their initial LAT detections, with systematically fainter and longer-duration emission compared to previous γ-ray-detected classical novae. These novae were distinguished by multiple bright optical peaks that encompassed the timemore » spans of the observed γ-rays. Finally, we discussed the γ-ray light curves and spectra of the two novae are presented along with representative hadronic and leptonic models, and comparisons with other novae detected by the LAT.« less

Muon Neutrino Disappearance in NOvA with a Deep Convolutional Neural Network Classifier

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rocco, Dominick Rosario

2016-03-01

The NuMI Off-axis Neutrino Appearance Experiment (NOvA) is designed to study neutrino oscillation in the NuMI (Neutrinos at the Main Injector) beam. NOvA observes neutrino oscillation using two detectors separated by a baseline of 810 km; a 14 kt Far Detector in Ash River, MN and a functionally identical 0.3 kt Near Detector at Fermilab. The experiment aims to provide new measurements of Δm 2 and θ23 and has potential to determine the neutrino mass hierarchy as well as observe CP violation in the neutrino sector. Essential to these analyses is the classification of neutrino interaction events in NOvA detectors.more » Raw detector output from NOvA is interpretable as a pair of images which provide orthogonal views of particle interactions. A recent advance in the field of computer vision is the advent of convolutional neural networks, which have delivered top results in the latest image recognition contests. This work presents an approach novel to particle physics analysis in which a convolutional neural network is used for classification of particle interactions. The approach has been demonstrated to improve the signal efficiency and purity of the event selection, and thus physics sensitivity. Early NOvA data has been analyzed (2.74×10 20 POT, 14 kt equivalent) to provide new best- fit measurements of sin 2(θ23) = 0.43 (with a statistically-degenerate compliment near 0.60) and |Δm2 | = 2.48 × 10 -3 eV 2.« less

Embryonic mescencephalon derived neurospheres contain progenitors as well as differentiated neurons and glia.

PubMed

Khaing, Zin Z; Roberts, James L

2009-01-01

Stem cells and progenitor cells in the central nervous system may have potential for therapeutic use in patients with degenerative diseases or after injury. Neural precursor cells can be grown in culture in the presence of mitogens as aggregates termed neurospheres (NSs), as a source of proliferating progenitor cells. Withdrawal of mitogen and allowing the NSs to adhere to a substrate is the conventional way to study the differentiation potential of the progenitor cells propagated in NSs form. Here we asked if differentiation occurs within NSs cultured in the normal manner, in the presence of mitogen. We used non-passaged NSs derived from E13.5 mouse ventral mesencephalon. The NSs contained not only progenitor cells but also phenotypically-differentiated neurons and glia, in the presence of mitogen. Extracellular matrix molecules (fibronectin, laminin and collagen type IV) were also detected within these NSs, which may aid in the differentiation of progenitors inside the NSs. The cell types within NSs were also organized in a way that the differentiated cells were found in the inner cell mass while progenitors were found in the outer region. Additionally, the proportion of differentiated cell types within the NSs was also affected by exposure to different mitogens. Moreover, when placed together in to co-culture, dissociated embryonic striatal and mesencephalic cells aggregated spontaneously to form mixed NSs, enhancing the eventual differentiation into dopaminergic neurons from progenitors within these NSs. Therefore, the NSs contained progenitor cells and differentiated neurons and glial cells. In addition, NS culture system can be used to study cellular differentiation in vitro in non-adherent conditions.

Progenitor Masses for Every Nearby Historic Core-Collapse Supernova

NASA Astrophysics Data System (ADS)

Williams, Benjamin

2016-10-01

Some of the most energetic explosions in the Universe are the core-collapse supernovae (CCSNe) that arise from the death of massive stars. They herald the birth of neutron stars and black holes, are prodigious emitters of neutrinos and gravitational waves, influence galactic hydrodynamics, trigger further star formation, and are a major site for nucleosynthesis, yet even the most basic elements of CCSN theory are poorly constrained by observations. Specifically, there are too few observations to constrain the progenitor mass distribution and fewer observations still to constrain the mapping between progenitor mass and explosion type (e.g. IIP IIL, IIb, Ib/c, etc.). Combining previous measurements with 9 proposed HST pointings covering 13 historic CCSNe, we plan to obtain progenitor mass measurements for all cataloged historic CCSNe within 8 Mpc, optimizing observational mass constraints for CCSN theory.

Osteoclast fusion is initiated by a small subset of RANKL-stimulated monocyte progenitors, which can fuse to RANKL-unstimulated progenitors.

PubMed

Levaot, Noam; Ottolenghi, Aner; Mann, Mati; Guterman-Ram, Gali; Kam, Zvi; Geiger, Benjamin

2015-10-01

Osteoclasts are multinucleated, bone-resorbing cells formed via fusion of monocyte progenitors, a process triggered by prolonged stimulation with RANKL, the osteoclast master regulator cytokine. Monocyte fusion into osteoclasts has been shown to play a key role in bone remodeling and homeostasis; therefore, aberrant fusion may be involved in a variety of bone diseases. Indeed, research in the last decade has led to the discovery of genes regulating osteoclast fusion; yet the basic cellular regulatory mechanism underlying the fusion process is poorly understood. Here, we applied a novel approach for tracking the fusion processes, using live-cell imaging of RANKL-stimulated and non-stimulated progenitor monocytes differentially expressing dsRED or GFP, respectively. We show that osteoclast fusion is initiated by a small (~2.4%) subset of precursors, termed "fusion founders", capable of fusing either with other founders or with non-stimulated progenitors (fusion followers), which alone, are unable to initiate fusion. Careful examination indicates that the fusion between a founder and a follower cell consists of two distinct phases: an initial pairing of the two cells, typically lasting 5-35 min, during which the cells nevertheless maintain their initial morphology; and the fusion event itself. Interestingly, during the initial pre-fusion phase, a transfer of the fluorescent reporter proteins from nucleus to nucleus was noticed, suggesting crosstalk between the founder and follower progenitors via the cytoplasm that might directly affect the fusion process, as well as overall transcriptional regulation in the developing heterokaryon. Copyright © 2015 Elsevier Inc. All rights reserved.

Derivation and characterization of hepatic progenitor cells from human embryonic stem cells.

PubMed

Zhao, Dongxin; Chen, Song; Cai, Jun; Guo, Yushan; Song, Zhihua; Che, Jie; Liu, Chun; Wu, Chen; Ding, Mingxiao; Deng, Hongkui

2009-07-31

The derivation of hepatic progenitor cells from human embryonic stem (hES) cells is of value both in the study of early human liver organogenesis and in the creation of an unlimited source of donor cells for hepatocyte transplantation therapy. Here, we report for the first time the generation of hepatic progenitor cells derived from hES cells. Hepatic endoderm cells were generated by activating FGF and BMP pathways and were then purified by fluorescence activated cell sorting using a newly identified surface marker, N-cadherin. After co-culture with STO feeder cells, these purified hepatic endoderm cells yielded hepatic progenitor colonies, which possessed the proliferation potential to be cultured for an extended period of more than 100 days. With extensive expansion, they co-expressed the hepatic marker AFP and the biliary lineage marker KRT7 and maintained bipotential differentiation capacity. They were able to differentiate into hepatocyte-like cells, which expressed ALB and AAT, and into cholangiocyte-like cells, which formed duct-like cyst structures, expressed KRT19 and KRT7, and acquired epithelial polarity. In conclusion, this is the first report of the generation of proliferative and bipotential hepatic progenitor cells from hES cells. These hES cell-derived hepatic progenitor cells could be effectively used as an in vitro model for studying the mechanisms of hepatic stem/progenitor cell origin, self-renewal and differentiation.

Using the Nova Southeastern University Web Site

Science.gov Websites

audiences (i.e. students, alumni, faculty, staff, vendors), the site still provides categorized resource pages for current students, faculty, and staff. Information for these groups can be accessed through the Now / Request Info Giving Alumni Select A College Nova Southeastern University Abraham S. Fischler

Optical evolution of Nova Ophiuchi 2007 = V2615 Oph

NASA Astrophysics Data System (ADS)

Munari, U.; Henden, A.; Valentini, M.; Siviero, A.; Dallaporta, S.; Ochner, P.; Tomasoni, S.

2008-06-01

The moderately fast Nova Oph 2007 reached maximum brightness on 2007 March 28 at V= 8.52, B-V=+1.12, V-RC=+0.76, V-IC=+1.59 and RC-IC=+0.83, after fast initial rise and a pre-maximum halt lasting a week. Decline times were tV2= 26.5, tB2= 30, tV3= 48.5 and tB3= 56.5 d. The distance to the nova is d= 3.7 ± 0.2 kpc, the height above the Galactic plane is z= 215 pc, the reddening is E(B-V) = 0.90 and the absolute magnitude at maximum is MmaxV=-7.2 and MmaxB=-7.0. The spectrum four days before maximum resembled a F6 supergiant, in an agreement with broad-band colours. It later developed into that of a standard `Fe ii'-class nova. Nine days past maximum, the expansion velocity estimated from the width of Hα emission component was ˜730 km s-1, and the displacement from it of the principal and diffuse-enhanced absorption systems was ˜650 and 1380 km s-1, respectively. Dust probably formed and disappeared during the period from 82 to 100 d past maximum, causing (at peak dust concentration) an extinction of ΔB= 1.8 mag and an extra ΔE(B-V) = 0.44 reddening.

An evaluation of Nova Scotia's alcohol ignition interlock program.

PubMed

Vanlaar, Ward G M; Mainegra Hing, Marisela; Robertson, Robyn D

2017-03-01

Alcohol ignition interlock programs for offenders aim to reduce recidivism among convicted drink drivers. This study presents an evaluation of Nova Scotia's interlock program implemented in 2008 in order to assess its effectiveness to reduce impaired driving and to help identify areas for improvement. Data used include conviction and crash records of individual participants; provincial monthly counts of alcohol-related charges, convictions and fatal and serious crashes; and interlock logged events. Methods used include descriptive statistics, survival analysis, time series and logistic regression analysis. With respect to specific deterrence (i.e., preventing recidivism) there was a 90% reduction in recidivism among voluntary participants since participation in the interlock program and a 79% reduction after these participants exited from the program. With respect to general deterrence (i.e., referring to a preventative effect on the entire population of drivers in Nova Scotia) there were temporary decreases in the numbers of alcohol-related charges (13.32%) and convictions (9.93%) and a small significant decrease in the number of fatal and serious injury alcohol-related crashes, following the implementation of the program. The evidence suggests the interlock program was better at preventing harm due to alcohol-impaired driving than the alternative of not using the interlock program. Recommendations were formulated supporting the continuation of the interlock program in Nova Scotia. Copyright © 2017 Elsevier Ltd. All rights reserved.

Compensatory Response by Late Embryonic Tubular Epithelium to the Reduction in Pancreatic Progenitors

PubMed Central

Nishimura, Wataru; Kapoor, Archana; El Khattabi, Ilham; Jin, Wanzhu; Yasuda, Kazuki; Bonner-Weir, Susan; Sharma, Arun

2015-01-01

Early in pancreatic development, epithelial cells of pancreatic buds function as primary multipotent progenitor cells (1°MPC) that specify all three pancreatic cell lineages, i.e., endocrine, acinar and duct. Bipotent "Trunk" progenitors derived from 1°MPC are implicated in directly regulating the specification of endocrine progenitors. It is unclear if this specification process is initiated in the 1°MPC where some 1°MPC become competent for later specification of endocrine progenitors. Previously we reported that in Pdx1 tTA/+ ;tetO MafA (bigenic) mice inducing expression of transcription factor MafA in Pdx1-expressing (Pdx1+) cells throughout embryonic development inhibited the proliferation and differentiation of 1°MPC cells, resulting in reduced pancreatic mass and endocrine cells by embryonic day (E) 17.5. Induction of the transgene only until E12.5 in Pdx1+ 1°MPC was sufficient for this inhibition of endocrine cells and pancreatic mass at E17.5. However, by birth (P0), as we now report, such bigenic pups had significantly increased pancreatic and endocrine volumes with endocrine clusters containing all pancreatic endocrine cell types. The increase in endocrine cells resulted from a higher proliferation of tubular epithelial cells expressing the progenitor marker Glut2 in E17.5 bigenic embryos and increased number of Neurog3-expressing cells at E19.5. A BrdU-labeling study demonstrated that inhibiting proliferation of 1°MPC by forced MafA-expression did not lead to retention of those progenitors in E17.5 tubular epithelium. Our data suggest that the forced MafA expression in the 1°MPC inhibits their competency to specify endocrine progenitors only until E17.5, and after that compensatory proliferation of tubular epithelium gives rise to a distinct pool of endocrine progenitors. Thus, these bigenic mice provide a novel way to characterize the competency of 1°MPC for their ability to specify endocrine progenitors, a critical limitation in our

Observational properties of massive black hole binary progenitors

NASA Astrophysics Data System (ADS)

Hainich, R.; Oskinova, L. M.; Shenar, T.; Marchant, P.; Eldridge, J. J.; Sander, A. A. C.; Hamann, W.-R.; Langer, N.; Todt, H.

2018-01-01

Context. The first directly detected gravitational waves (GW 150914) were emitted by two coalescing black holes (BHs) with masses of ≈ 36 M⊙ and ≈ 29 M⊙. Several scenarios have been proposed to put this detection into an astrophysical context. The evolution of an isolated massive binary system is among commonly considered models. Aims: Various groups have performed detailed binary-evolution calculations that lead to BH merger events. However, the question remains open as to whether binary systems with the predicted properties really exist. The aim of this paper is to help observers to close this gap by providing spectral characteristics of massive binary BH progenitors during a phase where at least one of the companions is still non-degenerate. Methods: Stellar evolution models predict fundamental stellar parameters. Using these as input for our stellar atmosphere code (Potsdam Wolf-Rayet), we compute a set of models for selected evolutionary stages of massive merging BH progenitors at different metallicities. Results: The synthetic spectra obtained from our atmosphere calculations reveal that progenitors of massive BH merger events start their lives as O2-3V stars that evolve to early-type blue supergiants before they undergo core-collapse during the Wolf-Rayet phase. When the primary has collapsed, the remaining system will appear as a wind-fed high-mass X-ray binary. Based on our atmosphere models, we provide feedback parameters, broad band magnitudes, and spectral templates that should help to identify such binaries in the future. Conclusions: While the predicted parameter space for massive BH binary progenitors is partly realized in nature, none of the known massive binaries match our synthetic spectra of massive BH binary progenitors exactly. Comparisons of empirically determined mass-loss rates with those assumed by evolution calculations reveal significant differences. The consideration of the empirical mass-loss rates in evolution calculations will

The 1991-2012 light curve of the old nova HR Lyrae

DOE Office of Scientific and Technical Information (OSTI.GOV)

Honeycutt, R. K.; Shears, J.; Kafka, S.

2014-05-01

The 22 yr light curve of HR Lyr, acquired with a typical cadence of 2-6 days, is examined for periodic and quasi-periodic variations. No persistent periodicities are revealed. Rather, the light curve variations often take the form of nearly linear rises and falls having typical e-folding times of about 100 days. Occasional ∼0.6 mag outbursts are also seen, with properties similar to those of small outbursts found in some nova-like cataclysmic variables. When the photometry is formed into yearly averages, a decline of 0.012 ± 0.005 mag yr{sup –1} is apparent, consistent with the fading of irradiation-induced M-dot following themore » nova. The equivalent width of Hα is tabulated at three epochs over the interval 1986-2008 in order to compare with a recent result for DK Lac in which Hα was found to be fading 50 yr after the nova. However, our results for such a fading in HR Lyr are inconclusive.« less

The search for Ixodes dammini and Borrelia burgdorferi in Nova Scotia

PubMed Central

Bell, Colin R; Specht, Harold B; Coombs, B Ann

1992-01-01

Twenty-four Ixodes dammini ticks (23 adults and one nymph) have been recovered in Nova Scotia since 1984. There has not been a systematic search for larvae and none has been identified. The recovery of the nymph from a road-killed yellow throat bird, Geothypis trichas, in late May 1990 supports the contention that migrating birds are bringing deer ticks into the province every spring. In March and April 1991, four adult deer ticks were identified, suggesting that these ticks had overwintered. These deer tick specimens indicate that it is possible that I dammini is becoming established in Nova Scotia, if it is not already established. There has been no evidence for the existence of Borrelia burgdorferi in the province. The spirochete was not cultured from 650 Dermacentor variabilis ticks, nor were antibodies detected in a small sample of feral rodents using an indirect fluorescent antibody test. A survey of 137 dog sera samples, analyzed by enzyme-linked immunosorbent assay, also proved negative. There has been no confirmed indigenous case of Lyme disease in Nova Scotia to date. PMID:22416195

The search for Ixodes dammini and Borrelia burgdorferi in Nova Scotia.

PubMed

Bell, C R; Specht, H B; Coombs, B A

1992-09-01

Twenty-four Ixodes dammini ticks (23 adults and one nymph) have been recovered in Nova Scotia since 1984. There has not been a systematic search for larvae and none has been identified. The recovery of the nymph from a road-killed yellow throat bird, Geothypis trichas, in late May 1990 supports the contention that migrating birds are bringing deer ticks into the province every spring. In March and April 1991, four adult deer ticks were identified, suggesting that these ticks had overwintered. These deer tick specimens indicate that it is possible that I dammini is becoming established in Nova Scotia, if it is not already established. There has been no evidence for the existence of Borrelia burgdorferi in the province. The spirochete was not cultured from 650 Dermacentor variabilis ticks, nor were antibodies detected in a small sample of feral rodents using an indirect fluorescent antibody test. A survey of 137 dog sera samples, analyzed by enzyme-linked immunosorbent assay, also proved negative. There has been no confirmed indigenous case of Lyme disease in Nova Scotia to date.

Test bench for measurements of NOvA scintillator properties at JINR

NASA Astrophysics Data System (ADS)

Velikanova, D. S.; Antoshkin, A. I.; Anfimov, N. V.; Samoylov, O. B.

2018-04-01

The NOvA experiment was built to study oscillation parameters, mass hierarchy, CP- violation phase in the lepton sector and θ23 octant, via vɛ appearance and vμ disappearance modes in both neutrino and antineutrino beams. These scientific goals require good knowledge about NOvA scintillator basic properties. The new test bench was constructed and upgraded at JINR. The main goal of this bench is to measure scintillator properties (for solid and liquid scintillators), namely α/β discrimination and Birk's coefficients for protons and other hadrons (quenching factors). This knowledge will be crucial for recovering the energy of the hadronic part of neutrino interactions with scintillator nuclei. α/β discrimination was performed on the first version of the bench for LAB-based and NOvA scintillators. It was performed again on the upgraded version of the bench with higher statistic and precision level. Preliminary result of quenching factors for protons was obtained. A technical description of both versions of the bench and current results of the measurements and analysis are presented in this work.

Haploinsufficiency for the Six2 gene increases nephron progenitor proliferation promoting branching and nephron number.

PubMed

Combes, Alexander N; Wilson, Sean; Phipson, Belinda; Binnie, Brandon B; Ju, Adler; Lawlor, Kynan T; Cebrian, Cristina; Walton, Sarah L; Smyth, Ian M; Moritz, Karen M; Kopan, Raphael; Oshlack, Alicia; Little, Melissa H

2018-03-01

The regulation of final nephron number in the kidney is poorly understood. Cessation of nephron formation occurs when the self-renewing nephron progenitor population commits to differentiation. Transcription factors within this progenitor population, such as SIX2, are assumed to control expression of genes promoting self-renewal such that homozygous Six2 deletion results in premature commitment and an early halt to kidney development. In contrast, Six2 heterozygotes were assumed to be unaffected. Using quantitative morphometry, we found a paradoxical 18% increase in ureteric branching and final nephron number in Six2 heterozygotes, despite evidence for reduced levels of SIX2 protein and transcript. This was accompanied by a clear shift in nephron progenitor identity with a distinct subset of downregulated progenitor genes such as Cited1 and Meox1 while other genes were unaffected. The net result was an increase in nephron progenitor proliferation, as assessed by elevated EdU (5-ethynyl-2'-deoxyuridine) labeling, an increase in MYC protein, and transcriptional upregulation of MYC target genes. Heterozygosity for Six2 on an Fgf20-/- background resulted in premature differentiation of the progenitor population, confirming that progenitor regulation is compromised in Six2 heterozygotes. Overall, our studies reveal a unique dose response of nephron progenitors to the level of SIX2 protein in which the role of SIX2 in progenitor proliferation versus self-renewal is separable. Copyright © 2017 International Society of Nephrology. Published by Elsevier Inc. All rights reserved.

Recurrent Meningitis.

PubMed

Rosenberg, Jon; Galen, Benjamin T

2017-07-01

Recurrent meningitis is a rare clinical scenario that can be self-limiting or life threatening depending on the underlying etiology. This review describes the causes, risk factors, treatment, and prognosis for recurrent meningitis. As a general overview of a broad topic, the aim of this review is to provide clinicians with a comprehensive differential diagnosis to aide in the evaluation and management of a patient with recurrent meningitis. New developments related to understanding the pathophysiology of recurrent meningitis are as scarce as studies evaluating the treatment and prevention of this rare disorder. A trial evaluating oral valacyclovir suppression after HSV-2 meningitis did not demonstrate a benefit in preventing recurrences. The data on prophylactic antibiotics after basilar skull fractures do not support their use. Intrathecal trastuzumab has shown promise in treating leptomeningeal carcinomatosis from HER-2 positive breast cancer. Monoclonal antibodies used to treat cancer and autoimmune diseases are new potential causes of drug-induced aseptic meningitis. Despite their potential for causing recurrent meningitis, the clinical entities reviewed herein are not frequently discussed together given that they are a heterogeneous collection of unrelated, rare diseases. Epidemiologic data on recurrent meningitis are lacking. The syndrome of recurrent benign lymphocytic meningitis described by Mollaret in 1944 was later found to be closely related to HSV-2 reactivation, but HSV-2 is by no means the only etiology of recurrent aseptic meningitis. While the mainstay of treatment for recurrent meningitis is supportive care, it is paramount to ensure that reversible and treatable causes have been addressed for further prevention.

Insm1 promotes the transition of olfactory progenitors from apical and proliferative to basal, terminally dividing and neuronogenic.

PubMed

Rosenbaum, Jason N; Duggan, Anne; García-Añoveros, Jaime

2011-02-01

Insm1 is a zinc-finger transcription factor transiently expressed throughout the developing nervous system in late progenitors and nascent neurons. Insm1 is also highly expressed in medulloblastomas and other neuroendocrine tumors. We generated mice lacking the Insm1 gene and used them to elucidate its role in neurogenic proliferation of the embryonic olfactory epithelium. We found that deletion of Insm1 results in more apical cells and fewer nascent and mature neurons. In the embryonic olfactory epithelium of Insm1 mutants we detect fewer basal progenitors, which produce neurons, and more apical progenitors, which at this stage produce additional progenitors. Furthermore, in the mutants we detect fewer progenitors expressing NEUROD1, a marker of terminally dividing, neuronogenic (neuron-producing) progenitors (immediate neuronal precursors), and more progenitors expressing ASCL1, a marker of the transit amplifying progenitors that migrate from the apical to the basal edges of the epithelium while dividing to generate the terminal, neuronogenic progenitors. Finally, with timed administration of nucleoside analogs we demonstrate that the Insm1 mutants contain fewer terminally dividing progenitors at embryonic day 12.5. Altogether, these results suggest a role for Insm1 in promoting the transition of progenitors from apical and proliferative to basal, terminal and neuronogenic. This role appears partially conserved with that of its nematode ortholog, egl-46. The similar effects of Insm1 deletion on progenitors of embryonic olfactory epithelium and cortex point to striking parallels in the development of these neuroepithelia, and particularly between the basal progenitors of olfactory epithelium and the subventricular zone progenitors of cortex.

Retinoid-signaling in progenitors controls specification and regeneration of the urothelium

PubMed Central

Reiley, Maia; Laufer, Ed; Metzger, Daniel; Liang, Fengxia; Liao, Yi; Sun, Tung-Tien; Aronow, Bruce; Rosen, Roni; Mauney, Josh; Adam, Rosalyn; Rosselot, Carolina; Van Batavia, Jason; McMahon, Andrew; McMahon, Jill; Guo, Jin-Jin; Mendelsohn, Cathy

2013-01-01

The urothelium is a stratified epithelium that prevents exchange of water and toxic substances between the urinary tract and blood. It is composed of Keratin-5-expressing-basal-cells (K5-BCs), intermediate cells and superficial cells specialized for synthesis and transport of uroplakins that assemble into the apical barrier. K5-BCs are considered to be a progenitor cell type in the urothelium and other stratified epithelia. Fate mapping studies however, reveal that P-cells, a transient population, are urothelial progenitors in the embryo, intermediate cells are superficial cell progenitors in the adult regenerating urothelium, and K5-BCs are a distinct lineage. Our studies indicate that retinoids, potent regulators of ES cells and other progenitors, are also required in P-cells and intermediate cells for their specification. These observations have important implications for tissue engineering and repair, and ultimately, may lead to treatments that prevent loss of the urothelial barrier, a major cause of voiding dysfunction and bladder pain syndrome. PMID:23993789

Culture and Characterization of Circulating Endothelial Progenitor Cells in Patients with Renal Cell Carcinoma.

PubMed

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 <0.001). A colony of circulating endothelial progenitor cells first emerged significantly earlier in patient than in control preparations (6.72 vs 14.67 days, p <0.001). The 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 <0.001). The circulating endothelial progenitor cell level correlated positively with the number of patient colonies (r = 0.762, p <0.001). 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 <0.001). Earlier emergence of circulating endothelial progenitor cell colonies, a higher cell culture success rate and more colonies were found for patients with renal cell carcinoma than for healthy controls. Results

NOvA: Building a Next Generation Neutrino Experiment

ScienceCinema

Perko, John; Williams, Ron; Miller, Bill

2018-01-16

The NOvA neutrino experiment is searching for the answers to some of the most fundamental questions of the universe. This video documents how collaboration between government research institutions like Fermilab, academia and industry can create one of the largest neutrino detectors in the world.

The Type IIb Supernova 2013df and its Cool Supergiant Progenitor

NASA Technical Reports Server (NTRS)

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.;

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

PubMed

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.

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

PubMed Central

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.

2015-01-01

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. PMID:26597788

A transient radio jet in an erupting dwarf nova.

PubMed

Körding, Elmar; Rupen, Michael; Knigge, Christian; Fender, Rob; Dhawan, Vivek; Templeton, Matthew; Muxlow, Tom

2008-06-06

Astrophysical jets seem to occur in nearly all types of accreting objects, from supermassive black holes to young stellar objects. On the basis of x-ray binaries, a unified scenario describing the disc/jet coupling has evolved and been extended to many accreting objects. The only major exceptions are thought to be cataclysmic variables: Dwarf novae, weakly accreting white dwarfs, show similar outburst behavior to x-ray binaries, but no jet has yet been detected. Here we present radio observations of a dwarf nova in outburst showing variable flat-spectrum radio emission that is best explained as synchrotron emission originating in a transient jet. Both the inferred jet power and the relation to the outburst cycle are analogous to those seen in x-ray binaries, suggesting that the disc/jet coupling mechanism is ubiquitous.

Safety and Effectiveness of NovaSure® Endometrial Ablation After Placement of Essure® Micro-Inserts

PubMed Central

Price, Pamela; Burkhart, Jamie; Johnson, Jamie

2012-01-01

Abstract Objective: In-office NovaSure® after Essure® is a clinical paradigm for which physicians are seeking information. A PubMed search (July 2011) revealed no peer-reviewed articles describing this treatment sequence. To address the paucity of data on this topic, patients who had undergone Essure followed by NovaSure in a private practice office between July 1, 2008 and December 31, 2009 were evaluated. The objective was to evaluate safety and feasibility of in-office NovaSure after Essure, and to determine if the effectiveness of either procedure was altered by this treatment sequence. Design: This was a retrospective cohort study of 117 women (ages 24–52). Methods: Patients underwent Essure followed by NovaSure in two in-office sessions, separated by a median of 14 days. All patients had menorrhagia and desired permanent sterilization. A postprocedure patient questionnaire was administered to assess satisfaction and perceived effectiveness. Results: Among patients who underwent Essure followed by NovaSure, 83/117 (71%) returned for a 3-month hysterosalpingogram (HSG). Satisfactory placement and tubal occlusion were noted in 79/83 (95%) of these patients. Amenorrhea or spotting was observed in 72/97 (74%) of patients, 22/97 (23%) reported a satisfactory decrease in menstrual flow, and 3/97 (3%) reported ablation failure. Essure followed by NovaSure did not decrease the effectiveness of either procedure, and no adverse events were attributed to the combination of the two procedures. Patients reported high levels of satisfaction with both procedures. Conclusions: In women seeking permanent birth control and menorrhagia reduction, in-office Essure followed by NovaSure appeared to be safe, effective, and associated with high patient satisfaction. (J GYNECOL SURG 28:1) PMID:24761128

From fuzzy recurrence plots to scalable recurrence networks of time series

NASA Astrophysics Data System (ADS)

Pham, Tuan D.

2017-04-01

Recurrence networks, which are derived from recurrence plots of nonlinear time series, enable the extraction of hidden features of complex dynamical systems. Because fuzzy recurrence plots are represented as grayscale images, this paper presents a variety of texture features that can be extracted from fuzzy recurrence plots. Based on the notion of fuzzy recurrence plots, defuzzified, undirected, and unweighted recurrence networks are introduced. Network measures can be computed for defuzzified recurrence networks that are scalable to meet the demand for the network-based analysis of big data.

Endothelial Progenitor Cells as Shuttle of Anticancer Agents.

PubMed

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

PubMed Central

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

Mature Hepatocytes Exhibit Unexpected Plasticity by Direct Dedifferentiation into Liver Progenitor Cells in Culture

PubMed Central

Chen, Yixin; Wong, Philip P.; Sjeklocha, Lucas; Steer, Clifford J.; Sahin, M. Behnan

2011-01-01

Although there have been numerous reports describing the isolation of liver progenitor cells from adult liver, their exact origin has not been clearly defined; and the role played by mature hepatocytes as direct contributors to the hepatic progenitor cell pool has remained largely unknown. Here we report strong evidence that mature hepatocytes in culture have the capacity to dedifferentiate into a population of adult liver progenitors without genetic or epigenetic manipulations. By using highly-purified mature hepatocytes, which were obtained from untreated, healthy rat liver and labeled with fluorescent dye PKH2, we found that hepatocytes in culture gave rise to a population of PKH2-positive liver progenitor cells. These cells, Liver Derived Progenitor Cells or LDPCS, which share phenotypic similarities with oval cells, were previously reported to be capable of forming mature hepatocytes both in culture and in animals. Studies done at various time points during the course of dedifferentiation cultures revealed that hepatocytes rapidly transformed into liver progenitors within one week through a transient oval cell-like stage. This finding was supported by lineage-tracing studies involving double-transgenic AlbuminCreXRosa26 mice expressing β-galactosidase exclusively in hepatocytes. Cultures set up with hepatocytes obtained from these mice resulted in generation of β-galactosidase-positive liver progenitor cells demonstrating that they were a direct dedifferentiation product of mature hepatocytes. Additionally, these progenitors differentiated into hepatocytes in vivo when transplanted into rats that had undergone retrorsine pretreatment and partial hepatectomy. Conclusion Our studies provide strong evidence for the unexpected plasticity of mature hepatocytes to dedifferentiate into progenitor cells in culture; and this may potentially have a significant impact on the treatment of liver diseases requiring liver or hepatocyte transplantation. PMID:21953633

Local Thermonuclear Runaways in Dwarf Novae?

NASA Astrophysics Data System (ADS)

Shara, Michael

2012-10-01

We have no hope of understanding the structure and evolution of a class of astrophysical objects if we cannot identify the dominant energy source of those objects.The Disk Instability Model {DIM} postulates that Dwarf Nova {DN} outbursts are powered by runaway accretion from an accretion disk onto a White Dwarf {WD} in a red dwarf-WD mass transferring binary. Ominously, HST observations {e.g. Sion et al. 2001} of WD surface abundances hint at a significant shortcoming of the DIM. The data from the present proposal will be able to unequivocally demonstrate if the observed highly Carbon-depleted and Nitrogen-enhanced abundances on WD surfaces {NOT predicted by DIM} vary with binary orbital phase, or throughout a DN quiescence cycle, or from cycle to cycle. These same data will test if predicted {but never observed} Local Thermonuclear Runaways {"Nuclear-powered mini-novas"} occur on the WDs of DN. Such events could trigger or even power DN, providing the long-sought physical mechanism of DN eruptions that DIM lacks. As a "free" bonus, the same data may also directly detect the diffusion of accreted metals in a WD atmosphere for the first time, or provide significant limits on the diffusion rate.

On the progenitors of Type Ia supernovae

NASA Astrophysics Data System (ADS)

Livio, Mario; Mazzali, Paolo

2018-03-01

We review all the models proposed for the progenitor systems of Type Ia supernovae and discuss the strengths and weaknesses of each scenario when confronted with observations. We show that all scenarios encounter at least a few serious difficulties, if taken to represent a comprehensive model for the progenitors of all Type Ia supernovae (SNe Ia). Consequently, we tentatively conclude that there is probably more than one channel leading SNe Ia. While the single-degenerate scenario (in which a single white dwarf accretes mass from a normal stellar companion) has been studied in some detail, the other scenarios will need a similar level of scrutiny before any firm conclusions can be drawn.

Using SN 1987A light echoes to determine mass loss from the progenitor

NASA Technical Reports Server (NTRS)

Crotts, Arlin P. S.; Kunkel, William E.

1991-01-01

The hypothesis that the blue progenitor of SN 1987A passed through a blue supergiant phase ending with the expulsion of the outer envelope is tested. The many light echoes seen near SN 1987A were used to search for a mass flow from the progenitor and for abrupt density changes at the limits of this smooth mass flow. The progenitor needed roughly a million yr to create these structures, assuming a constant mass loss at 15 km/s. The dust in the region is small-grained and isotropically scattering. Interaction between the progenitor blue supergiant and red supergiant winds is probably contained within a roughly spherical structure 1.5 pc in diameter.

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

PubMed

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.

Improving the {sup 33}S(p,{gamma}){sup 34}Cl Reaction Rate for Models of Classical Nova Explosions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Parikh, A.; Faestermann, Th.; Kruecken, R.

2011-10-28

Reduced uncertainty in the thermonuclear rate of the {sup 33}S(p,{gamma}){sup 34}Cl reaction would help to improve our understanding of nucleosynthesis in classical nova explosions. At present, models are generally in concordance with observations that nuclei up to roughly the calcium region may be produced in these explosive phenomena; better knowledge of this rate would help with the quantitative interpretation of nova observations over the S-Ca mass region, and contribute towards the firm establishment of a nucleosynthetic endpoint. As well, models find that the ejecta of nova explosions on massive oxygen-neon white dwarfs may contain as much as 150 times themore » solar abundance of {sup 33}S. This characteristic isotopic signature of a nova explosion could possibly be observed through the analysis of microscopic grains formed in the environment surrounding a nova and later embedded within primitive meteorites. An improved {sup 33}S(p,{gamma}){sup 34}Cl rate (the principal destruction mechanism for {sup 33}S in novae) would help to ensure a robust model prediction for the amount of {sup 33}S that may be produced. Finally, constraining this rate could confirm or rule out the decay of an isomeric state of {sup 34}Cl(E{sub x} = 146 keV, t{sub 1/2} = 32 m) as a source for observable gamma-rays from novae. We have performed several complementary experiments dedicated to improving our knowledge of the {sup 33}S(p,{gamma}){sup 34}Cl rate, using both indirect methods (measurement of the {sup 34}S({sup 3}He,t){sup 34}Cl and {sup 33}S({sup 3}He,d){sup 34}Cl reactions with the Munich Q3D spectrograph) and direct methods (in normal kinematics at CENPA, University of Washington, and in inverse kinematics with the DRAGON recoil mass separator at TRIUMF). Our results will be used with nova models to facilitate comparisons of model predictions with present and future nova observables.« less

Declining lymphoid progenitor fitness promotes aging-associated leukemogenesis.

PubMed

Henry, Curtis J; Marusyk, Andriy; Zaberezhnyy, Vadym; Adane, Biniam; DeGregori, James

2010-12-14

Aging is associated with the functional decline of cells, tissues, and organs. At the same time, age is the single most important prognostic factor in the development of most human cancers, including chronic myelogenous and acute lymphoblastic leukemias initiated by Bcr-Abl oncogenic translocations. Prevailing paradigms attribute the association between aging and cancers to the accumulation of oncogenic mutations over time, because the accrual of oncogenic events is thought to be the rate-limiting step in initiation and progression of cancers. Conversely, aging-associated functional decline caused by both cell-autonomous and non-cell-autonomous mechanisms is likely to reduce the fitness of stem and progenitor cell populations. This reduction in fitness should be conducive for increased selection of oncogenic mutations that can at least partially alleviate fitness defects, thereby promoting the initiation of cancers. We tested this hypothesis using mouse hematopoietic models. Our studies indicate that the dramatic decline in the fitness of aged B-lymphopoiesis coincides with altered receptor-associated kinase signaling. We further show that Bcr-Abl provides a much greater competitive advantage to old B-lymphoid progenitors compared with young progenitors, coinciding with restored kinase signaling pathways, and that this enhanced competitive advantage translates into increased promotion of Bcr-Abl-driven leukemias. Moreover, impairing IL-7-mediated signaling is sufficient to promote selection for Bcr-Abl-expressing B progenitors. These studies support an unappreciated causative link between aging and cancer: increased selection of oncogenic mutations as a result of age-dependent alterations of the fitness landscape.

Basal Cells Are a Multipotent Progenitor Capable of Renewing the Bronchial Epithelium

PubMed Central

Hong, Kyung U.; Reynolds, Susan D.; Watkins, Simon; Fuchs, Elaine; Stripp, Barry R.

2004-01-01

Commitment of the pulmonary epithelium to bronchial and bronchiolar airway lineages occurs during the transition from pseudoglandular to cannalicular phases of lung development, suggesting that regional differences exist with respect to the identity of stem and progenitor cells that contribute to epithelial maintenance in adulthood. We previously defined a critical role for Clara cell secretory protein-expressing (CE) cells in renewal of bronchiolar airway epithelium following injury. Even though CE cells are also the principal progenitor for maintenance of the bronchial airway epithelium, CE cell injury is resolved through a mechanism involving recruitment of a second progenitor cell population that we now identify as a GSI-B4 reactive, cytokeratin-14-expressing basal cell. These cells exhibit multipotent differentiation capacity as assessed by analysis of cellular phenotype within clones of LacZ-tagged cells. Clones were derived from K14-expressing cells tagged in a cell-type-specific fashion by ligand-regulable Cre recombinase-mediated genomic rearrangement of the ROSA26 recombination substrate allele. We conclude that basal cells represent an alternative multipotent progenitor cell population of bronchial airways and that progenitor cell selection is dictated by the type of airway injury. PMID:14742263

Determining Data Quality for the NOvA Experiment