Evolution of the symbiotic nova RX Puppis

We present and discuss a hundred year history of activity of the hot component of RX Pup based on optical photometry and spectroscopy. The outburst evolution of RX Pup resembles that of other symbiotic novae whereas at quiescence the hot component shows activity (high and low activity states) resembling that of symbiotic recurrent novae T CrB and RS Oph.Comment: To appear in in M. Hernanz, J. Jose, eds, Classical Novae Explosions, AIP; 5 pages, 2 figure

Evolution of the symbiotic nova RX Puppis

We present and discuss a hundred year history of activity of the hot component of RX Pup based on optical photometry and spectroscopy. The outburst evolution of RX Pup resembles that of other symbiotic novae whereas at quiescence the hot component shows activity (high and low activity states) resembling that of symbiotic recurrent novae T CrB and RS Oph.Comment: To appear in in M. Hernanz, J. Jose, eds, Classical Novae Explosions, AIP; 5 pages, 2 figure

Acoustically modulated magnetic resonance imaging of gas-filled protein nanostructures

Non-invasive biological imaging requires materials capable of interacting with deeply penetrant forms of energy such as magnetic fields and sound waves. Here, we show that gas vesicles (GVs), a unique class of gas-filled protein nanostructures with differential magnetic susceptibility relative to water, can produce robust contrast in magnetic resonance imaging (MRI) at sub-nanomolar concentrations, and that this contrast can be inactivated with ultrasound in situ to enable background-free imaging. We demonstrate this capability in vitro, in cells expressing these nanostructures as genetically encoded reporters, and in three model in vivo scenarios. Genetic variants of GVs, differing in their magnetic or mechanical phenotypes, allow multiplexed imaging using parametric MRI and differential acoustic sensitivity. Additionally, clustering-induced changes in MRI contrast enable the design of dynamic molecular sensors. By coupling the complementary physics of MRI and ultrasound, this nanomaterial gives rise to a distinct modality for molecular imaging with unique advantages and capabilities

An Efficient and Cost-Effective Nose-Only Inhalational Chamber for Rodents: Design, Optimization and Validation

The mainstay treatment of pulmonary disorders lies around the direct drug targeting to the lungs using a nebulizer, metered-dose inhaler, or dry powder inhaler. Only few inhalers are available in the market that could be used for inhalational drug delivery in rodents. However, the available rodent inhalers invariably require high cost and maintenance, which limits their use at laboratory scale. The present work, therefore, was undertaken to develop a simple, reliable, and cost-effective nose-only inhalation chamber with holding capacity of three mice at a time. The nebulized air passes directly and continuously from the central chamber to mouthpiece and maintains an aerosol cloud for rodents to inhale. Laser diffraction analysis indicated volume mean diameter of 4.02 ± 0.30 μm, and the next-generation impactor studies, however, revealed mean mass aerodynamic diameter of 3.40 ± 0.27 μm, respectively. An amount of 2.05 ± 0.20 mg of voriconazole (VRC) was available for inhalation at each delivery port of the inhaler. In vivo studies indicated the deposition of 76.12 ± 19.50 μg of VRC in the mice lungs when nebulized for a period of 20 min. Overall, the developed nose-only inhalation chamber offers a reliable means of generating aerosols and successfully exposing mice to nebulization

Biomolecular Ultrasound and Sonogenetics

Visualizing and modulating molecular and cellular processes occurring deep within living organisms is fundamental to our study of basic biology and disease. Currently, the most sophisticated tools available to dynamically monitor and control cellular events rely on light-responsive proteins, which are difficult to use outside of optically transparent model systems, cultured cells, or surgically accessed regions owing to strong scattering of light by biological tissue. In contrast, ultrasound is a widely used medical imaging and therapeutic modality that enables the observation and perturbation of internal anatomy and physiology but has historically had limited ability to monitor and control specific cellular processes. Recent advances are beginning to address this limitation through the development of biomolecular tools that allow ultrasound to connect directly to cellular functions such as gene expression. Driven by the discovery and engineering of new contrast agents, reporter genes, and bioswitches, the nascent field of biomolecular ultrasound carries a wave of exciting opportunities

Optical and infrared observations of the supernova SN 1999el

Optical and near-infrared light curves of the Type IIn supernova 1999el in NGC 6951 are presented. A period of 220 days (416 days in the near-infrared) is covered from the first observation obtained a few days before maximum light. Spectroscopic observations are also discussed. Using as a distance calibrator the Type Ia SN 2000E, which occurred some months later in the same galaxy, and fitting a blackbody law to the photometric data we obtain a maximum bolometric luminosity for SN 1999el of $\sim 10^{44}$ erg s$^{-1}$. In general, the photometric properties of SN 1999el are very similar to those of SN 1998S, a bright and well studied Type IIn SN, showing a fast decline in all observed bands similar to those of Type II-L SNe. The differences with SN 1998S are analyzed and ascribed to the differences in a pre-existing circumstellar envelope in which dust was already present at the moment of the SN outburst. We infer that light echoes may play a possibly significant role in affecting the observed properties of the light curves, although improved theoretical models are needed to account for the data. We conclude that mass loss in the progenitor RG stars is episodic and occurs in an asymmetric way. This implies that collapsing massive stars appear as normal Type II SN if this occurs far from major mass loss episodes, whereas they appear as Type IIn SNe if a large mass loss episode is in progress.Comment: 30 pages, 8 figures, figure 1 available as jpeg file, ApJ in pres

Spectroscopy of Blue Stragglers and Turnoff Stars in M67 (NGC 2682)

We have analyzed high-resolution spectra of relatively cool blue stragglers and main sequence turnoff stars in the old open cluster M67 (NGC 2682). We attempt to identify blue stragglers whose spectra are least contaminated by binary effects (contamination by a binary companion or absorption by circumstellar material). These ``best'' stragglers have metallicities ([Fe/H] = -0.05) and abundance ratios of the blue stragglers are not significantly different from those of the turnoff stars. Based on arguments from hydrodynamical models of stellar collisions, we assert that the current upper limits for the lithium abundances of all blue stragglers observed in M67 (by us and others) are consistent with no mixing during the formation process, assuming pre-main sequence and main sequence depletion patterns observed for M67 main sequence stars. We discuss composition signatures that could more definitively distinguish between blue straggler formation mechanisms in open cluster stars. We confirm the spectroscopic detection of a binary companion to the straggler S 1082. From our spectra, we measure a projected rotational speed of 90+/-20 km/sec for the secondary, and find that its radial velocity varies with a peak-to-peak amplitude of ~ 25 km/sec. Because the radial velocities do not vary with a period corresponding to the partial eclipses in the system, we believe this system is currently undergoing mass transfer. In addition we present evidence that S 984 is a true blue straggler (and not an unresolved pair). If this can be proven, our detection of lithium may indicate a collisional origin.Comment: 20 pages, 4 figures, to appear in October 2000 A

HST FUV spectroscopy of the short orbital period recurrent nova CI Aql: Implications for white dwarf mass evolution

An HST COS Far UV spectrum (1170 A to 1800 A) was obtained for the short orbital period recurrent novae (T Pyxidis subclass), CI Aquilae. CI Aql is the only classical CV known to have two eclipses of sensible depth per orbit cycle and also have pre- and post-outburst light curves that are steady enough to allow estimates of mass and orbital period changes. Our FUV spectral analysis with model accretion disks and NLTE high gravity photospheres, together with the Gaia parallax, reveal CI Aql's FUV light is dominated by an optically thick accretion disk with an accretion rate of the order of $4\times 10^{-8}$ $M_{\odot}/yr$. Its database of light curves, radial velocity curves, and eclipse timings is among the best for any CV. Its orbit period ($P$), $dP/dt$, and reference time are re-derived via simultaneous analysis of the three data types, giving a dimensionless post-outburst $dP/dt$ of $-2.49\pm 0.95\times 10^{-10}$. Lack of information on loss of orbital to rotational angular momentum leads to some uncertainty in the translation of $dP/dt$ to white dwarf mass change rate, $dM_1/dt$, but within the modest range of $+4.8\times 10^{-8}$ to $+7.8\times 10^{-8}$ $M_{\odot} /yr$. The estimated white dwarf mass change through outburst for CI Aql, based on simple differencing of its pre- and post outburst orbit period, is unchanged from the previously published $+5.3 \times 10^{-6} M_{\odot}$. At the WD's estimated mass increase rate, it will terminate as a Type Ia supernova within 10 million years