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Swift J1818.0−1607 is a radio-emitting magnetar that was discovered in X-ray outburst in March 2020. Starting four days after this outburst, we began a nearly five month multi-frequency observing campaign at 2.2, 8.4, and 32 GHz using telescopes in the NASA Deep Space Network. Using a dual-frequency observing mode, we were able to observe Swift J1818.0−1607 simultaneously at either 2.2 and 8.4 GHz or 8.4 and 32 GHz. Over the course of the campaign, we find that the flux density increases substantially and the spectrum changes from uncharacteristically steep (α < −2.2) to the essentially flat (α ≈ 0) spectrum typical of radio-emitting magnetars. In addition to the expected profile evolution on timescales of days to months, we find that Swift J1818.0−1607 also exhibits mode switching where the pulse profile changes between two distinct shapes on timescales of seconds to minutes. For two of the radio observations, we also had accompanying X-ray observations using the Neutron Star Interior Composition Explorer (NICER) telescope that occurred on the same day. We find a near anti-alignment (0.40 phase cycles) between the peaks of the radio and X-ray pulse profiles, which is most likely explained by an intrinsic misalignment between the X-ray and radio emitting regions.

Fast radio bursts (FRBs) are extragalactic radio flashes of unknown physical origin. Their high luminosities and short durations require extreme energy densities, such as those found in the vicinity of neutron stars and black holes. Studying the burst intensities and polarimetric properties on a wide range of timescales, from milliseconds down to nanoseconds, is key to understanding the emission mechanism. However, high-time-resolution studies of FRBs are limited by their unpredictable activity levels, available instrumentation and temporal broadening in the intervening ionized medium. Here we show that the repeating FRB 20200120E can produce isolated shots of emission as short as about 60 nanoseconds in duration, with brightness temperatures as high as 3 × 10⁴¹ K (excluding relativistic effects), comparable with ‘nano-shots’ from the Crab pulsar. Comparing both the range of timescales and luminosities, we find that FRB 20200120E observationally bridges the gap between known Galactic young pulsars and magnetars and the much more distant extragalactic FRBs. This suggests a common magnetically powered emission mechanism spanning many orders of magnitude in timescale and luminosity. In this Article, we probe a relatively unexplored region of the short-duration transient phase space; we highlight that there probably exists a population of ultrafast radio transients at nanosecond to microsecond timescales, which current FRB searches are insensitive to.

Of the more than $3{,}000$ radio pulsars currently known, only ${\sim}300$ are in binary systems, and only five of these consist of young pulsars with massive non-degenerate companions. We present the discovery and initial timing, accomplished using the Canadian Hydrogen Intensity Mapping Experiment telescope (CHIME), of the sixth such binary pulsar, PSR J2108+4516, a $0.577$-s radio pulsar in a 269-day orbit of eccentricity 0.09 with a companion of minimum mass $11$ M$_{\odot}$. Notably, the pulsar undergoes periods of substantial eclipse, disappearing from the CHIME $400{-}800$ MHz observing band for a large fraction of its orbit, and displays significant dispersion measure and scattering variations throughout its orbit, pointing to the possibility of a circumstellar disk or very dense stellar wind associated with the companion star. Subarcsecond resolution imaging with the Karl G. Jansky Very Large Array unambiguously demonstrates that the companion is a bright, $V \simeq 11$ OBe star, EM* UHA 138, located at a distance of $3.26(14)$ kpc. Archival optical observations of \companion{} approximately suggest a companion mass ranging from $17.5$ M$_{\odot} < M_{\rm c} < 23$ M$_{\odot}$, in turn constraining the orbital inclination angle to $50.3^{\circ} \lesssim i \lesssim 58.3^{\circ}$. With further multi-wavelength followup, PSR J2108+4516 promises to serve as another rare laboratory for the exploration of companion winds, circumstellar disks, and short-term evolution through extended-body orbital dynamics., 20 pages, 12 figures, accepted by ApJ

Over a dozen millisecond pulsars are ablating low-mass companions in close binary systems. In the original "black widow", the 8-hour orbital period eclipsing pulsar PSR J1959+2048 (PSR B1957+20), high energy emission originating from the pulsar is irradiating and may eventually destroy a low-mass companion. These systems are not only physical laboratories that reveal the dramatic result of exposing a close companion star to the relativistic energy output of a pulsar, but are also believed to harbour some of the most massive neutron stars, allowing for robust tests of the neutron star equation of state. Here, we report observations of ZTF J1406+1222, a wide hierarchical triple hosting a 62-minute orbital period black widow candidate whose optical flux varies by a factor of more than 10. ZTF J1406+1222 pushes the boundaries of evolutionary models, falling below the 80 minute minimum orbital period of hydrogen-rich systems. The wide tertiary companion is a rare low metallicity cool subdwarf star, and the system has a Galactic halo orbit consistent with passing near the Galactic center, making it a probe of formation channels, neutron star kick physics, and binary evolution., 63 pages, 15 figures, 2 tables, published in Nature on May 4, 2022

Fast radio bursts (FRBs) represent an exciting frontier in the study of gravitational lensing, due to their brightness, extragalactic nature, and the compact, coherent characteristics of their emission. In a companion work [Kader, Leung+2022], we use a novel interferometric method to search for gravitationally lensed FRBs in the time domain using bursts detected by CHIME/FRB. There, we dechannelize and autocorrelate electric field data at a time resolution of 1.25 ns. This enables a search for FRBs whose emission is coherently deflected by gravitational lensing around a foreground compact object such as a primordial black hole (PBH). Here, we use our non-detection of lensed FRBs to place novel constraints on the PBH abundance outside the Local Group. We use a novel two-screen model to take into account decoherence from scattering screens in our constraints. Our constraints are subject to a single astrophysical model parameter -- the effective distance between an FRB source and the scattering screen, for which we adopt a fiducial distance of 1 parsec. We find that coherent FRB lensing is a sensitive probe of sub-solar mass compact objects. Having observed no lenses in $172$ bursts from $114$ independent sightlines through the cosmic web, we constrain the fraction of dark matter made of compact objects, such as PBHs, to be $f \lesssim 0.8$, if their masses are $\sim 10^{-3} M_{\odot}$., 20 pages, 5 figures

Fast radio bursts (FRBs) are exceptionally luminous flashes of unknown physical origin, reaching us from other galaxies (Petroff et al. 2019). Most FRBs have only ever been seen once, while others flash repeatedly, though sporadically (Spitler et al. 2016, CHIME/FRB Collaboration et al. 2021). Many models invoke magnetically powered neutron stars (magnetars) as the engines producing FRB emission (Margalit & Metzger 2018, CHIME/FRB Collaboration et al. 2020). Recently, CHIME/FRB announced the discovery (Bhardwaj et al. 2021) of the repeating FRB 20200120E, coming from the direction of the nearby grand design spiral galaxy M81. Four potential counterparts at other observing wavelengths were identified (Bhardwaj et al. 2021) but no definitive association with these sources, or M81, could be made. Here we report an extremely precise localisation of FRB 20200120E, which allows us to associate it with a globular cluster (GC) in the M81 galactic system and to place it ~2pc offset from the optical center of light of the GC. This confirms (Bhardwaj et al. 2021) that FRB 20200120E is 40 times closer than any other known extragalactic FRB. Because such GCs host old stellar populations, this association strongly challenges FRB models that invoke young magnetars formed in a core-collapse supernova as powering FRB emission. We propose, instead, that FRB 20200120E is a highly magnetised neutron star formed via either accretion-induced collapse of a white dwarf or via merger of compact stars in a binary system (Margalit et al. 2019). Alternative scenarios involving compact binary systems, efficiently formed inside globular clusters, could also be responsible for the observed bursts., Submitted. Comments welcome

The CHIME/FRB experiment has detected thousands of Fast Radio Bursts (FRBs) due to its sensitivity and wide field of view; however, its low angular resolution prevents it from localizing events to their host galaxies. Very Long Baseline Interferometry (VLBI), triggered by FRB detections from CHIME/FRB will solve the challenge of localization for non-repeating events. Using a refurbished 10-m radio dish at the Algonquin Radio Observatory located in Ontario Canada, we developed a testbed for a VLBI experiment with a theoretical ~, Accepted for publication by AJ

The CHIME/FRB project has detected hundreds of fast radio bursts (FRBs), providing an unparalleled population to probe statistically the foreground media that they illuminate. One such foreground medium is the ionized halo of the Milky Way (MW). We estimate the total Galactic electron column density from FRB dispersion measures (DMs) as a function of Galactic latitude using four different estimators, including ones that assume spherical symmetry of the ionized MW halo and ones that imply more latitudinal-variation in density. Our observation-based constraints of the total Galactic DM contribution for $|b|\geq 30^\circ$, depending on the Galactic latitude and selected model, span 87.8 - 141 pc cm^-3. This constraint implies upper limits on the MW halo DM contribution that range over 52-111 pc cm^-3. We discuss the viability of various gas density profiles for the MW halo that have been used to estimate the halo's contribution to DMs of extragalactic sources. Several models overestimate the DM contribution, especially when assuming higher halo gas masses (~ 3.5 x 10^12 solar masses). Some halo models predict a higher MW halo DM contribution than can be supported by our observations unless the effect of feedback is increased within them, highlighting the impact of feedback processes in galaxy formation., 19 pages, 4 figures. ApJ in press (accepted February 8th, 2023)

Fast radio bursts (FRBs) are brief, energetic, extragalactic flashes of radio emission whose progenitors are largely unknown. Although studying the FRB population is essential for understanding how these astrophysical phenomena occur, such studies have been difficult to conduct without large numbers of FRBs and characterizable observational biases. Using the recently released catalog of 536 FRBs published by the Canadian Hydrogen Intensity Mapping Experiment/Fast Radio Burst (CHIME/FRB) collaboration, we present a study of the FRB population that also calibrates for selection effects. Assuming a Schechter luminosity function, we infer a characteristic energy cut-off of $E_\mathrm{char} =$ $2.38^{+5.35}_{-1.64} \times 10^{41}$ erg and a differential power-law index of $\gamma =$ $-1.3^{+0.7}_{-0.4}$. Simultaneously, we infer a volumetric rate of [$7.3^{+8.8}_{-3.8}$(stat.)$^{+2.0}_{-1.8}$(sys.)]$\times 10^4$ Gpc$^{-3}$ year$^{-1}$ above a pivot energy of 10$^{39}$ erg and below a scattering timescale of 10 ms at 600 MHz, and find we cannot significantly constrain the cosmic evolution of the FRB population with star formation rate. Modeling the host dispersion measure (DM) contribution as a log-normal distribution and assuming a total Galactic contribution of 80 pc cm$^{-3}$, we find a median value of $\mathrm{DM}_\mathrm{host} =$ $84^{+69}_{-49}$ pc cm$^{-3}$, comparable with values typically used in the literature. Proposed models for FRB progenitors should be consistent with the energetics and abundances of the full FRB population predicted by our results. Finally, we infer the redshift distribution of FRBs detected with CHIME, which will be tested with the localizations and redshifts enabled by the upcoming CHIME/FRB Outriggers project., Comment: Revised to reflect published version

We report on NICER X-ray monitoring of the magnetar SGR 1830-0645 covering 223 days following its October 2020 outburst, as well as Chandra and radio observations. We present the most accurate spin ephemerides of the source so far: $\nu=0.096008680(2)$~Hz, $\dot{\nu}=-6.2(1)\times10^{-14}$~Hz~s$^{-1}$, and a significant second and third frequency derivative terms indicative of non-negligible timing noise. The phase-averaged 0.8--7~keV spectrum is well fit with a double-blackbody (BB) model throughout the campaign. The BB temperatures remain constant at 0.46 and 1.2 keV. The areas and flux of each component decreased by a factor of 6, initially through a steep decay trend lasting about 46 days followed by a shallow long-term one. The pulse shape in the same energy range is initially complex, exhibiting three distinct peaks, yet with clear continuous evolution throughout the outburst towards a simpler, single-pulse shape. The rms pulsed fraction is high and increases from about 40% to 50%. We find no dependence of pulse shape or fraction on energy. These results suggest that multiple hotspots, possibly possessing temperature gradients, emerged at outburst-onset, and shrank as the outburst decayed. We detect 84 faint bursts with \nicer, having a strong preference for occurring close to the surface emission pulse maximum the first time this phenomenon is detected in such a large burst sample. This likely implies a very low altitude for the burst emission region, and a triggering mechanism connected to the surface active zone. Finally, our radio observations at several epochs and multiple frequencies reveal no evidence of pulsed or burst-like radio emission., Comment: ApJ accepted

Magnetars are a special subset of the isolated neutron star family, with X-ray and radio emission mainly powered by the decay of their immense magnetic fields. Many attributes of magnetars remain poorly understood: spin-down glitches or the sudden reductions in the star's angular momentum, radio bursts reminiscent of extra-galactic Fast Radio Bursts (FRBs), and transient pulsed radio emission lasting months to years. Here we unveil the detection of a large spin-down glitch event ($|\Delta\nu/\nu| = 5.8_{-1.6}^{+2.6}\times10^{-6}$) from the magnetar SGR~1935+2154 on 2020 October 5 (+/- 1 day). We find no change to the source persistent surface thermal or magnetospheric X-ray behavior, nor is there evidence of strong X-ray bursting activity. Yet, in the subsequent days, the magnetar emitted three FRB-like radio bursts followed by a month long episode of pulsed radio emission. Given the rarity of spin-down glitches and radio signals from magnetars, their approximate synchronicity suggests an association, providing pivotal clues to their origin and triggering mechanisms, with ramifications to the broader magnetar and FRB populations. We postulate that impulsive crustal plasma shedding close to the magnetic pole generates a wind that combs out magnetic field lines, rapidly reducing the star's angular momentum, while temporarily altering the magnetospheric field geometry to permit the pair creation needed to precipitate radio emission., Comment: 51 pages, 3 tables, 8 figures. Accepted for publication in Nature Astronomy

We describe a pipeline to measure scintillation in fast radio bursts (FRBs) detected by CHIME/FRB in the 400-800 MHz band by analyzing the frequency structure of the FRB's spectrum. We use the pipeline to measure the characteristic frequency bandwidths of scintillation between $4-100$ kHz in 12 FRBs corresponding to timescales of $\sim$2-40 $\mu$s for 10 FRBs detected by CHIME/FRB. For the other two FRBs, we did not detect scintillation in the region our analysis is sensitive. We compared the measured scintillation timescales to the NE2001 predictions for the scintillation timescales from the Milky Way. We find a strong correlation to be an indication that in most instances, the observed scintillation of FRBs can be explained by the Milky Way., Comment: 4 pages, 1 figure, for RNAAS

The repeating FRB 20201124A was first discovered by CHIME/FRB in November of 2020, after which it was seen to repeat a few times over several months. It entered a period of high activity in April of 2021, at which time several observatories recorded tens to hundreds more bursts from the source. These follow-up observations enabled precise localization and host galaxy identification. In this paper, we report on the CHIME/FRB-detected bursts from FRB 20201124A, including their best-fit morphologies, fluences, and arrival times. The large exposure time of the CHIME/FRB telescope to the location of this source allows us to constrain its rates of activity. We analyze the repetition rates over different spans of time, constraining the rate prior to discovery to $< 3.4$ day$^{-1}$ (at 3$\sigma$), and demonstrate significant change in the event rate following initial detection. Lastly, we perform a maximum-likelihood estimation of a power-law luminosity function, finding a best-fit index $\alpha = -4.6 \pm 1.3 \pm 0.6$, with a break at a fluence threshold of $F_{\rm min} \sim 16.6$~Jy~ms, consistent with the fluence completeness limit of the observations. This index is consistent within uncertainties with those of other repeating FRBs for which it has been determined., Comment: 19 pages, 6 figures

We present a Monte Carlo-based population synthesis study of fast radio burst (FRB) dispersion and scattering focusing on the first catalog of sources detected with the Canadian Hydrogen Intensity Mapping Experiment Fast Radio Burst (CHIME/FRB) project. We simulate intrinsic properties and propagation effects for a variety of FRB population models and compare the simulated distributions of dispersion measures (DMs) and scattering timescales with the corresponding distributions from the CHIME/FRB catalog. Our simulations confirm the results of previous population studies, which suggested that the interstellar medium of the host galaxy alone (simulated based on the NE2001 model) cannot explain the observed scattering timescales of FRBs. We therefore consider additional sources of scattering, namely, the circumgalactic medium (CGM) of intervening galaxies and the circumburst medium whose properties are modeled based on typical Galactic plane environments. We find that a population of FRBs with scattering contributed by these media is marginally consistent with the CHIME/FRB catalog. In this scenario, our simulations favor a population of FRBs offset from their galaxy centers over a population which is distributed along the spiral arms. However, if the models proposing the CGM as a source of intense scattering are incorrect, then we conclude that FRBs may inhabit environments with more extreme properties than those inferred for pulsars in the Milky Way., Accepted for publication in ApJ

Fast radio bursts (FRBs) are millisecond-duration flashes of radio waves that are visible at distances of billions of light-years. The nature of their progenitors and their emission mechanism remain open astrophysical questions. Here we report the detection of the multi-component FRB 20191221A and the identification of a periodic separation of 216.8(1) ms between its components with a significance of 6.5 sigmas. The long (~3 s) duration and nine or more components forming the pulse profile make this source an outlier in the FRB population. Such short periodicity provides strong evidence for a neutron-star origin of the event. Moreover, our detection favours emission arising from the neutron-star magnetosphere, as opposed to emission regions located further away from the star, as predicted by some models., Comment: Updated to conform to the accepted version

We present the detection of a bright radio burst at radio frequencies between 2.2--2.3 GHz with the NASA Deep Space Network (DSN) 70 m dish (DSS-63) in Madrid, Spain from FRB~20200120E. This repeating fast radio burst (FRB) was recently discovered by the Canadian Hydrogen Intensity Mapping Experiment Fast Radio Burst (CHIME/FRB) instrument and reported to be associated with the M81 spiral galaxy at a distance of 3.6 Mpc. The high time resolution capabilities of the recording system used in this observation, together with the small amount of scattering and intrinsic brightness of the burst, allow us to explore the burst structure in unprecedented detail. We find that the burst has a duration of roughly 30 $\mu$s and is comprised of several narrow components with typical separations of 2--3 $\mu$s. The narrowest component has a width of $\lesssim$ 100 ns, which corresponds to a light travel time size as small as 30 m, the smallest associated with an FRB to date. The peak flux density of the narrowest burst component is 270 Jy. We estimate the total spectral luminosity of the narrowest component of the burst to be 4 $\times$ 10$^{\text{30}}$ erg s$^{\text{-1}}$ Hz$^{\text{-1}}$, which is a factor of $\sim$500 above the luminosities of the so-called "nanoshots" associated with giant pulses from the Crab pulsar. This spectral luminosity is also higher than that of the radio bursts detected from the Galactic magnetar SGR 1935+2154 during its outburst in April 2020, but it falls on the low-end of the currently measured luminosity distribution of extragalatic FRBs. These results provide further support for the presence of a continuum of FRB burst luminosities., Comment: Accepted

We present a multiband study of FRB 20180916B, a repeating source with a 16.3 day periodicity. We report the detection of 4, 1 and 7 bursts from observations spanning 3 days using upgraded Giant Metrewave Radio Telescope (300-500 MHz), Canadian Hydrogen Intensity Mapping Experiment (400-800 MHz) and Green Bank Telescope (600-1000 MHz), respectively. We report the first-ever detection of the source in the 800-1000 MHz range along with one of the widest instantaneous bandwidth detection (200 MHz) at lower frequencies. We identify 30 $\mu$s wide structures in one of the bursts at 800 MHz, making it the lowest frequency detection of such structures for this FRB thus far. There is also a clear indication of high activity of the source at a higher frequency during earlier phases of the activity cycle. We identify a gradual decrease in the rotation measure over two years and no significant variations in the dispersion measure. We derive useful conclusions about progenitor scenarios, energy distribution, emission mechanisms, and variation of downward drift rate of emission with frequency. Our results reinforce that multiband observations are an effective approach to study repeaters and even one-off events to better understand their varying activity and spectral anomalies., Comment: 20 pages, 10 figures

The spectra of repeating fast radio bursts (FRBs) are complex and time-variable, sometimes peaking within the observing band and showing a fractional emission bandwidth of about 10-30%. These spectral features may provide insight into the emission mechanism of repeating fast radio bursts, or they could possibly be explained by extrinsic propagation effects in the local environment. Broadband observations can better quantify this behavior and help to distinguish between intrinsic and extrinsic effects. We present results from a simultaneous 2.25 and 8.36 GHz observation of the repeating FRB 121102 using the 70 m Deep Space Network (DSN) radio telescope, DSS-43. During the 5.7 hr continuous observing session, we detected 6 bursts from FRB 121102, which were visible in the 2.25 GHz frequency band. However, none of these bursts were detected in the 8.36 GHz band, despite the larger bandwidth and greater sensitivity in the higher-frequency band. This effect is not explainable by Galactic scintillation and, along with previous multi-band experiments, clearly demonstrates that apparent burst activity depends strongly on the radio frequency band that is being observed., Comment: 8 pages, 3 figures, 1 table. Accepted for publication in ApJL on 2020 June 8. v2: Updated to match published version

The spectra of fast radio bursts (FRBs) encode valuable information about the source's local environment, underlying emission mechanism(s), and the intervening media along the line of sight. We present results from a long-term multiwavelength radio monitoring campaign of two repeating FRB sources, FRB 121102 and FRB 180916.J0158+65, with the NASA Deep Space Network (DSN) 70-m radio telescopes (DSS-63 and DSS-14). The observations of FRB 121102 were performed simultaneously at 2.3 and 8.4 GHz, and spanned a total of 27.3 hr between 2019 September 19 and 2020 February 11. We detected 2 radio bursts in the 2.3 GHz frequency band from FRB 121102, but no evidence of radio emission was found at 8.4 GHz during any of our observations. We observed FRB 180916.J0158+65 simultaneously at 2.3 and 8.4 GHz, and also separately in the 1.5 GHz frequency band, for a total of 101.8 hr between 2019 September 19 and 2020 May 14. Our observations of FRB 180916.J0158+65 spanned multiple activity cycles during which the source was known to be active and covered a wide range of activity phases. Several of our observations occurred during times when bursts were detected from the source between 400-800 MHz with the Canadian Hydrogen Intensity Mapping Experiment (CHIME) radio telescope. However, no radio bursts were detected from FRB 180916.J0158+65 at any of the frequencies used during our observations with the DSN radio telescopes. We find that FRB 180916.J0158+65's apparent activity is strongly frequency-dependent due to the narrowband nature of its radio bursts, which have less spectral occupancy at high radio frequencies ($\gtrsim$ 2 GHz). We also find that fewer or fainter bursts are emitted from the source at high radio frequencies. We discuss the implications of these results on possible progenitor models of repeating FRBs., Comment: 17 pages, 3 figures, 5 tables, Accepted for publication in ApJL on 2020 November 12

We report on Nuclear Spectroscopic Telescope Array (NuSTAR), Neil Gehrels Swift Observatory (Swift) X-ray Telescope (XRT) and Swift Burst Alert Telescope (BAT) observations of IGR J16493-4348, a wind-fed Supergiant X-ray Binary (SGXB) showing significant superorbital variability. From a discrete Fourier transform of the BAT light curve, we refine its superorbital period to be 20.058 $\pm$ 0.007 days. The BAT dynamic power spectrum and a fractional root mean square analysis both show strong variations in the amplitude of the superorbital modulation, but no observed changes in the period were found. The superorbital modulation is significantly weaker between MJD 55,700 and MJD 56,300. The joint NuSTAR and XRT observations, which were performed near the minimum and maximum of one cycle of the 20 day superorbital modulation, show that the flux increases by more than a factor of two between superorbital minimum and maximum. We find no significant changes in the 3-50 keV pulse profiles between superorbital minimum and maximum, which suggests a similar accretion regime. Modeling the pulse-phase averaged spectra we find a possible Fe K$\alpha$ emission line at 6.4 keV at superorbital maximum. The feature is not significant at superorbital minimum. While we do not observe any significant differences between the pulse-phase averaged spectral continua apart from the overall flux change, we find that the hardness ratio near the broad main peak of the pulse profile increases from superorbital minimum to maximum. This suggests the spectral shape hardens with increasing luminosity. We discuss different mechanisms that might drive the observed superorbital modulation., Comment: 17 pages, 14 figures, 3 tables, accepted for publication in The Astrophysical Journal on 2019 May 15

We report the non-detection of dispersed bursts between 4 and 8 GHz from 2.5 hr of observations of FRB 20200120E at 6 GHz using the Robert C. Byrd Green Bank Telescope. Our fluence limits are several times lower than the average burst fluences reported at 600 and 1400 MHz. We conclude that these non-detections are either due to high-frequency bursts being weaker and/or scintillation-induced modulated. It is also likely that our observations were non-concurrent with any activity window of FRB 20200120E.

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We report on simultaneous radio and X-ray observations of the repeating fast radio burst source FRB 180916.J0158+65 using the Canadian Hydrogen Intensity Mapping Experiment (CHIME), Effelsberg, and Deep Space Network (DSS-14 and DSS-63) radio telescopes and the Chandra X-ray Observatory. During 33 ks of Chandra observations, we detect no radio bursts in overlapping Effelsberg or Deep Space Network observations and a single radio burst during CHIME/FRB source transits. We detect no X-ray events in excess of the background during the Chandra observations. These non-detections imply a 5-$��$ limit of $, 16 pages, 2 figures, submitted to ApJ

The Deep Space Network (DSN) is a worldwide array of radio telescopes that supports NASA's interplanetary spacecraft missions. When the DSN antennas are not communicating with spacecraft, they provide a valuable resource for performing observations of radio magnetars, searches for new pulsars at the Galactic Center, and additional pulsar-related studies. We describe the DSN's capabilities for carrying out these types of observations. We also present results from observations of three radio magnetars, PSR J1745-2900, PSR J1622-4950, and XTE J1810-197, and the transitional magnetar candidate, PSR J1119-6127, using the DSN radio telescopes near Canberra, Australia., Comment: 14 pages, 8 figures, Accepted for publication in Advances in Astronomy on 2019 January 27 (Invited paper for a special issue on magnetars)

We present results from observations of the Galactic Center magnetar, PSR J1745-2900, at 2.3 and 8.4 GHz with the NASA Deep Space Network 70 m antenna, DSS-43. We study the magnetar's radio profile shape, flux density, radio spectrum, and single pulse behavior over a ~1 year period between MJDs 57233 and 57621. In particular, the magnetar exhibits a significantly negative average spectral index of $\langle\alpha\rangle$ = -1.86 $\pm$ 0.02 when the 8.4 GHz profile is single-peaked, which flattens considerably when the profile is double-peaked. We have carried out an analysis of single pulses at 8.4 GHz on MJD 57479 and find that giant pulses and pulses with multiple emission components are emitted during a significant number of rotations. The resulting single pulse flux density distribution is incompatible with a log-normal distribution. The typical pulse width of the components is ~1.8 ms, and the prevailing delay time between successive components is ~7.7 ms. Many of the single pulse emission components show significant frequency structure over bandwidths of ~100 MHz, which we believe is the first observation of such behavior from a radio magnetar. We report a characteristic single pulse broadening timescale of $\langle\tau_{d}\rangle$ = 6.9 $\pm$ 0.2 ms at 8.4 GHz. We find that the pulse broadening is highly variable between emission components and cannot be explained by a thin scattering screen at distances $\gtrsim$ 1 kpc. We discuss possible intrinsic and extrinsic mechanisms for the magnetar's emission and compare our results to other magnetars, high magnetic field pulsars, and fast radio bursts., Comment: 18 pages, 12 figures, Accepted for publication in ApJ on 2018 August 30. v2: Updated to match published version

IGR J16493-4348 is an eclipsing supergiant high-mass X-ray binary (sgHMXB), where accretion onto the compact object occurs via the radially outflowing stellar wind of its early B-type companion. We present an analysis of the system's X-ray variability and periodic modulation using pointed observations (2.5-25 keV) and Galactic bulge scans (2-10 keV) from the Rossi X-ray Timing Explorer (RXTE) Proportional Counter Array (PCA), along with Swift Burst Alert Telescope (BAT) 70-month snapshot (14-195 keV) and transient monitor (15-50 keV) observations. The orbital eclipse profiles in the PCA bulge scans and BAT light curves are modeled using asymmetric and symmetric step and ramp functions. We obtain an improved orbital period measurement of 6.7828 $\pm$ 0.0004 days from an observed minus calculated (O-C) analysis of mid-eclipse times derived from the BAT transient monitor and PCA scan data. No evidence is found for the presence of a strong photoionization or accretion wake. We refine the superorbital period to 20.067 $\pm$ 0.009 days from the discrete Fourier transform (DFT) of the BAT transient monitor light curve. A pulse period of 1093.1036 $\pm$ 0.0004 s is measured from a pulsar timing analysis using pointed PCA observations spanning $\sim$1.4 binary orbits. We present pulse times of arrival (ToAs), circular and eccentric timing models, and calculations of the system's Keplerian binary orbital parameters. We derive an X-ray mass function of $f_{x}(M)$ $=$ 13.2$^{+2.4}_{-2.5}$ $M_{\odot}$ and find a spectral type of B0.5 Ia for the supergiant companion through constraints on the mass and radius of the donor. Measurements of the eclipse half-angle and additional parameters describing the system geometry are provided., Comment: 21 pages, 13 figures, 9 tables, Accepted for publication in ApJ on 2018 November 9

A 24 day period for the low-mass X-ray binary GX 13+1 was previously proposed on the basis of 7 years of RXTE ASM observations (Corbet 2003) and it was suggested that this was the orbital period of the system. This would make it the one of the longest known orbital periods for a Galactic low-mass X-ray binary powered by Roche lobe overflow. We present here the results of: (i) K-band photometry obtained with the SMARTS Consortium CTIO 1.3 telescope on 68 nights over a 10 month interval; (ii) Continued monitoring with the RXTE ASM, analyzed using a semi-weighted power spectrum instead of the data filtering technique previously used; and (iii) Swift BAT hard X-ray observations. Modulation near 24 days is seen in both the K-band and additional statistically independent ASM X-ray observations. However, the modulation in the ASM is not strictly periodic. The periodicity is also not detected in the Swift BAT observations, but modulation at the same relative level as seen with the ASM cannot be ruled out. If the 24 day period is the orbital period of system, this implies that the X-ray modulation is caused by structure that is not fixed in location. A possible mechanism for the X-ray modulation is the dipping behavior recently reported from XMM-Newton observations., Comment: Accepted for publication in the Astrophysical Journal

Recent advances in anode electrocatalysts for low-temperature PEM fuel cells are increasing tolerance for CO in the H 2 -rich anode stream. This study explores the impact of potential improvements in CO-tolerant electrocatalysts on the system efficiency of low-temperature Nafion-based PEM fuel cell systems operating in conjunction with a hydrocarbon autothermal reformer and a preferential CO oxidation (PROx) reactor for CO clean-up. The incomplete H 2 clean-up by PROx reactors with partial CO removal can present conditions where CO-tolerant anode electrocatalysts significantly improve overall system efficiency. Empirical fuel cell performance models were based upon voltage–current characteristics from single-cell MEA tests at varying CO concentrations with new Pt–Mo alloy reformate-tolerant electrocatalysts tested in conjunction with this study. A system-level model for a liquid-fueled PEM fuel cell system with a 5 kW full power output is used to study the trade-offs between the improved performance with decreased CO concentration and the increased penalties from the air supply to the PROx reactor and associated reduction in H 2 partial pressures to the anode. As CO tolerance is increased over current state-of-the-art Pt alloy catalysts, system efficiencies improve due primarily to higher fuel cell voltages and to a lesser extent to reductions in parasitic loads. Furthermore, increasing CO tolerance of anode electrocatalysts allows for the potential for reduced system costs with minimal efficiency penalty by reducing PROx reactor size through reduced CO conversion requirements.

Integrating PEM fuel cells effectively with liquid hydrocarbon reforming requires careful system analysis to assess trade-offs associated with H 2 production, purification, and overall water balance. To this end, a model of a PEM fuel cell system integrated with an autothermal reformer for liquid hydrocarbon fuels (modeled as C 12 H 23 ) and with H 2 purification in a water–gas-shift/membrane reactor is developed to do iterative calculations for mass, species, and energy balances at a component and system level. The model evaluates system efficiency with parasitic loads (from compressors, pumps, and cooling fans), system water balance, and component operating temperatures/pressures. Model results for a 5-kW fuel cell generator show that with state-of-the-art PEM fuel cell polarization curves, thermal efficiencies >30% can be achieved when power densities are low enough for operating voltages >0.72 V per cell. Efficiency can be increased by operating the reformer at steam-to-carbon ratios as high as constraints related to stable reactor temperatures allow. Decreasing ambient temperature improves system water balance and increases efficiency through parasitic load reduction. The baseline configuration studied herein sustained water balance for ambient temperatures ≤35 °C at full power and ≤44 °C at half power with efficiencies approaching ∼27 and ∼30%, respectively.

We have carried out high frequency radio observations of the high magnetic field pulsar PSR J1119-6127 following its recent X-ray outburst. While initial observations showed no evidence of significant radio emission, subsequent observations detected pulsed emission across a large frequency band. In this letter, we report on the initial disappearance of the pulsed emission and its prompt reactivation and dramatic evolution over several months of observation. The periodic pulse profile at S-band (2.3 GHz) after reactivation exhibits a multi-component emission structure, while the simultaneous X-band (8.4 GHz) profile shows a single emission peak. Single pulses were also detected at S-band near the main emission peaks. We present measurements of the spectral index across a wide frequency bandwidth, which captures the underlying changes in the radio emission profile of the neutron star. The high frequency radio detection, unusual emission profile, and observed variability suggest similarities with magnetars, which may independently link the high energy outbursts to magnetar-like behavior., Comment: Accepted for publication in ApJL. 2 figures, 2 tables

Purpose To analyze the clinical characteristics and treatment outcomes of patients with bleb-associated endophthalmitis (BAE). Design Retrospective, noncomparative, interventional case series. Participants Consecutive patients treated at one institution for BAE. Interventions Prompt pars plana vitrectomy (PPV) with intravitreal injection of antibiotics, or prompt vitreous biopsy and intravitreal injection of antibiotics (tap and inject). Methods Retrospective analysis of 68 consecutive cases of BAE between July 1, 1989 and June 30, 2001. Clinical presentation, treatment modality, microbiologic data, and clinical course were analyzed. Visual outcomes were compared between vitrectomy and tap-and-inject groups, culture-positive and culture-negative groups, and early and late times. Main outcome measures Snellen visual acuities (VAs) at 3 months and 12 months after treatment and at most recent follow-up. Results The incidence of no light perception (NLP) at 12 months after treatment for BAE was 35%. Vitreous isolates included streptococcal species (32% of positive cultures), Staphylococcus epidermidis (26%), Enterococcus , and Serratia (12% each). Patients with a positive vitreous culture had significantly worse VA (median, hand movements [HM] at 3 and 12 months after treatment) and a higher rate of NLP vision. Patients treated with tap-and-inject had a significantly worse final VA (medians, HM at 3 months and LP at 12 months) and a significantly higher rate of NLP vision than patients treated with PPV. One third of patients who underwent PPV achieved a final VA of 20/100 or better 12 months after treatment ( P = 0.09). Conclusions Bleb-associated endophthalmitis causes significant visual morbidity. Patients with culture-negative BAE and patients treated with prompt PPV may achieve better visual outcome.

LIGO and Virgo recently completed searches for gravitational waves at their initial target sensitivities, and soon Advanced LIGO and Advanced Virgo will commence observations with even better capabilities. In the search for short duration signals, such as coalescing compact binary inspirals or "burst" events, noise transients can be problematic. Interferometric gravitational-wave detectors are highly complex instruments, and, based on the experience from the past, the data often contain a large number of noise transients that are not easily distinguishable from possible gravitational-wave signals. In order to perform a sensitive search for short-duration gravitational-wave signals it is important to identify these noise artifacts, and to "veto" them. Here we describe such a veto, the bilinear-coupling veto, that makes use of an empirical model of the coupling of instrumental noise to the output strain channel of the interferometric gravitational-wave detector. In this method, we check whether the data from the output strain channel at the time of an apparent signal is consistent with the data from a bilinear combination of auxiliary channels. We discuss the results of the application of this veto on recent LIGO data, and its possible utility when used with data from Advanced LIGO and Advanced Virgo., Minor changes; To appear in Phys. Rev. D

* BACKGROUND AND OBJECTIVES: To eval uate the complication and visual outcomes of residents performing temporal clear cornea (TCC) compared to superior scleral tunnel (SST) phacoemulsification. * PATIENTS AND METHODS: We conducted a retrospective analysis of complications and visual outcomes for 534 phacoemulsification procedures done by third-year residents over a five-year period (June 1992-July 1 997) at the department of ophthalmology, University of Chicago. All cases were completed using a TCC or SST incision. * RESULTS: There was vitreous loss in 6.0% of 348 eyes with TCC incisions and in 11.8% of 186 eyes with SST incisions (P < 0.02). Posterior capsule breaks occurred in 11.5% of the TCC group versus 17.7% in the SST group (P < 0.0453). Best corrected visual acuity of 20/40 or better was achieved in 82.5% of all eyes with TCC incisions and in 75.3% of all eyes with SST incisions (P < 0.05). When 151 patients with previous ophthalmic conditions were excluded, the difference in BCVA between the two groups was not statistically significant. * CONCLUSIONS: Most institutions train residents with the SST technique prior to advancing to TCC. This study demonstrates that with proper teaching, residents can achieve excellent outcomes using TCC incisions, and can therefore be trained in this technique concurrently with SST incisions. Ophthalmic Surg Lasers 2001;32:228-232]

Objective To assess the efficacy of latanoprost additive therapy in patients with intraocular pressure (IOP) out of control while taking maximum-tolerated medications and to determine whether pilocarpine therapy has a dose-dependent adverse effect on the efficacy of latanoprost therapy. Design Noncomparative case series. Participants Sixty-one eyes of 61 patients with chronic glaucoma with IOP out of control while receiving maximum-tolerated medications were treated with latanoprost additive therapy on a compassionate basis. Main outcome measures Follow-up was up to 22 months with a mean of 13.9 ± 5.7 months. Kaplan-Meier survival analysis with Mantel-Cox log-rank test was performed to determine the overall success of latanoprost additive therapy and to compare the success rates of high-dose pilocarpine, low-dose pilocarpine, and no pilocarpine therapies. The criterion for success was avoiding glaucoma surgery with IOP decrease of 20% or greater and final IOP less than 22 mmHg. The IOP change and its significance for patients satisfying and failing the criterion for success also were determined to assess the latanoprost additive therapy. In addition, a number of pretreatment variables, including pilocarpine therapy, were analyzed for a significant effect on the efficacy of latanoprost additive therapy using Cox proportional hazards regression analysis. Results Latanoprost additive therapy significantly lowered mean IOP by 3.9 ± 5.5 mmHg at 3 months and by 3.5 ± 5.8 mmHg at 12 months. The cumulative success rate of the latanoprost additive therapy was 70% at 1 month, 42% at 3 months, 40% at 6 months, and 30% at 12 months. Of the variables studied, only increased number of previous incisional glaucoma surgeries and IOP greater than 24 mmHg before latanoprost additive therapy were significant prognostic factors for failure of latanoprost additive therapy. Pilocarpine therapy in any dose had no significant effect. Conclusion This study supports a trial of latanoprost additive therapy before glaucoma surgery in patients with IOP out of control while receiving maximum-tolerated medications irrespective of pilocarpine therapy and the pilocarpine dosage, especially when the number of previous incisional glaucoma surgery is less than three and the IOP is less than 25 mmHg.

Objective The authors investigated the incidence of capsular opacification requiring YAG capsulotomy after primary trabeculectomy combined with phacoemulsification and implantation of all polymethylmethacrylate intraocular lenses. Design A prospective randomized study. Participants One hundred seventy-four eyes of 174 nonselected patients with primary open-angle glaucoma (POAG) were randomized to either no adjunctive mitomycin C (MMC) (control group of 93 eyes of 93 patients) or adjunctive subconjunctival MMC (MMC group of 81 eyes of 81 patients) during the primary glaucoma triple procedure (PGTP). Intervention Primary glaucoma triple procedure with and without MMC and YAG laser capsulotomy for posterior capsular opacification (PCO) was performed. Main outcome measures The incidences of YAG capsulotomy for PCO were compared between the control and MMC groups and also between the control group and the MMC subgroups (1 minute, 3 minutes, and 5 minutes of MMC application) using Kaplan-Meier analysis with Mantel-Cox log-rank test. Cox proportional hazard regression analysis also was performed to identify significant factors affecting capsular opacification. Results The control and MMC groups were similar in preoperative characteristics. However, the probability of PCO requiring YAG capsulotomy was significantly lower in the MMC group than in the control group ( P = 0.004). Among the MMC subgroups, MMC application for 3 minutes was most effective and significant when compared with that of the control group ( P = 0.002). Although not as significant as the intraoperative use of MMC ( P = 0.002), old age ( P = 0.026) and presence of diabetes mellitus ( P = 0.035) were also identified as significant beneficial factors for decreasing the incidence of YAG capsulotomy for PCO in Cox proportional hazard regression analysis. Conclusion Intraoperative subconjunctival MMC application during combined glaucoma and cataract surgery has a beneficial effect of inhibiting PCO after combined surgery in patients with POAG. Thus, after intraoperative subconjunctival application of MMC at the concentration of 0.5 mg/ml for 3 minutes, the aqueous MMC level must have been great enough to inhibit the lens epithelial cell proliferation to result in a long-term decrease in PCO.

The efficacy of a non-steroidal anti-inflammatory agent, ibuprofen, was evaluated in pain control following periodontal surgery. This type of agent acts peripherally by inhibiting the release of prostaglandins and minimizing the local inflammatory response. Thus there may be an advantage in pre-treatment administration of the drug so as to delay or even prevent postoperative pain. The study was multicentre, involving a Public Hospital Periodontal Unit, two specialist periodontal practices in Sydney, NSW, and two in Canberra, ACT. One hundred and twenty-seven patients who were to undergo periodontal surgery were randomly given either two 200 mg tablets of ibuprofen or two matching placebo tablets at least 30 minutes before administration of local anaesthesia. The procedure was double blind: neither the patient nor the clinician was aware of the tablet identity. Postoperatively, all patients were given labelled ibuprofen for pain relief, but were randomly divided into two groups: As directed who were instructed to take the drug regularly for two days postoperatively, and As required, who were to take the drug only if needed for pain relief. All patients completed a diary recording quantity and time of medication, and regular assessment of pain experience utilizing a visual analogue scale. The As directed group showed no significant difference in pain experience between pre-operative and post-operative only medication, but the As required group experienced significantly less pain and requirement for medication if the ibuprofen was administered pre-operatively.

Hepatitis C Virus sequence studies mainly focus on the viral amplicon containing the Hypervariable region 1 (HVR1) to obtain a sample of sequences from which several population genetics parameters can be calculated. Recent advances in sequencing methods allow for analyzing an unprecedented number of viral variants from infected patients and present a novel opportunity for understanding viral evolution, drug resistance and immune escape. In the present paper, we compared three recent technologies for amplicon analysis: (i) Next-Generation Sequencing; (ii) Clonal sequencing using End-point Limiting-dilution for isolation of individual sequence variants followed by Real-Time PCR and sequencing; and (iii) Mass spectrometry of base-specific cleavage reactions of a target sequence. These three technologies were used to assess intra-host diversity and inter-host genetic relatedness in HVR1 amplicons obtained from 38 patients (subgenotypes 1a and 1b). Assessments of intra-host diversity varied greatly between sequence-based and mass-spectrometry-based data. However, assessments of inter-host variability by all three technologies were equally accurate in identification of genetic relatedness among viral strains. These results support the application of all three technologies for molecular epidemiology and population genetics studies. Mass spectrometry is especially promising given its high throughput, low cost and comparable results with sequence-based methods.

Objective To determine whether there is an increased prevalence of systemic autoimmune diseases in both patients with white spot syndromes (WSS) and their family members. Methods Patients with WSS at participating institutions were asked to complete a questionnaire reporting their own medical histories as well as any autoimmune diseases among their first- and second-degree relatives. Results As of January 1, 2008, 114 questionnaires had been collected, providing medical histories of 114 patients with WSS and 1098 family members. The number of patients with WSS with self-reported systemic autoimmune diseases was 26 (23%). Of 1098 relatives, 106 (10%) had at least 1 autoimmune disease. Systemic autoimmunity was more prevalent in female relatives (13%) as compared with male relatives (6%). In addition, the prevalence of autoimmunity was significantly higher among first-degree relatives (13%) than second-degree relatives (8%). Patients who themselves had systemic autoimmune diseases showed a greater prevalence of systemic autoimmunity among their families as compared with the families of patients without systemic autoimmune diseases. Conclusions Our data indicate that there is an increased prevalence of systemic autoimmunity in both patients with WSS and their first- and second-degree relatives. This suggests that WSS occur in families with inherited immune dysregulation that predisposes to autoimmunity.

Recent advances in anode electrocatalysts for low-temperature PEM fuel cells are increasing tolerance for CO in the H2 -rich anode stream. This study explores the impact of current day and future advances in CO-tolerant electrocatalysts on the system efficiency of low-temperature Nafion-based PEM fuel cell systems operating in conjunction with a hydrocarbon autothermal reformer and a preferential CO oxidation (PROx) reactor for CO clean-up. This study explores the effects of incomplete H2 cleanup by preferential oxidation reactors for partial CO removal, in combination with reformate-tolerant stacks. Empirical fuel cell performance models were based upon voltage-current characteristic from single-cell MEA tests at varying CO concentrations with new alloy reformate-tolerant electrocatalysts tested in conjunction with this study. A system-level model for a 5 kW maximum liquid-fueled system has been used to study the trade-offs between the improved performance with decreased CO concentration and the increased penalties from the air supply to the PROx reactor and associated reduction in H2 partial pressures to the anode. As CO tolerance is increased over current state-of-the-art Pt alloy catalysts system efficiencies improve due to higher fuel cell voltages. Furthermore, increasing CO tolerance of anode electrocatalysts allows for increased reformer efficiency by reducing PROx CO conversion requirements.Copyright © 2009 by ASME

Objective To analyze the microbiologic spectrum and in vitro susceptibility profiles over the last 11 years of organisms isolated from the vitreous of patients with endophthalmitis following cataract surgery. Methods Records of 497 consecutive patients treated at 1 institution for clinically suspected endophthalmitis following cataract surgery from July 1989 through June 2000 were reviewed. Results of microbiologic culture and in vitro antibiotic susceptibility testing from the periods 1989 to 1994 and 1995 to 2000 were compared. Results Between the 2 periods, there was a significant increase in the incidence of gram-positive bacteria (92%-97% of bacterial isolates). There was a significant increase in resistance among all bacterial isolates to ciprofloxacin (23%-37%;P = .02). There was increased resistance among coagulase-negative staphylococci to both ciprofloxacin (20%-38%) and cefazolin (19%-40%). Resistance to bacitracin, trimethoprim-sulfamethoxazole, and vancomycin remained unchanged. Vancomycin retained in vitro efficacy against more than 99% of gram-positive bacteria. Ceftazidime was effective against 100% of gram-negative bacteria tested. Conclusions The spectrum of pathogens causing postcataract endophthalmitis is changing, and resistance to antibiotics used for its prophylaxis has grown. These findings may affect the empirical treatment of postcataract endophthalmitis, as well as the use and choice of antibiotics in patients undergoing cataract surgery.

Purpose To present the microbial spectrum and susceptibilities of isolates in endophthalmitis following penetrating keratoplasty. Design Interventional case series. Methods The 1,074 consecutive cases of endophthalmitis presenting to Wills Eye Hospital between 1989 and 2000 were reviewed. Fourteen patients with endophthalmitis after penetrating keratoplasty were identified, and vitreous biopsy isolates from these patients were examined. Results Eleven (78.6%) of 14 vitreous samples were culture-positive, and two others (14.3%) had organisms viewed on pathology specimen, for a total of 13 (92.9%) organism-proven cases of endophthalmitis. Isolates included 10 (76.9%) gram-positive cocci (six Streptococcus sp., three Staphylococcus sp., one identified on pathology specimen only) and three (23.1%) gram-negative organisms ( Proteus mirabilis , Serratia marcescens , one identified on pathology specimen only). Susceptibilities to organism-appropriate antibiotic testing are reported, including cefazolin (six of eight, 75.0%), ciprofloxacin (four of seven, 57.1%), nafcillin (four of six, 66.7%), and vancomycin (seven of seven, 100.0%). Conclusion This is the largest series on microbial susceptibilities in postpenetrating keratoplasty endophthalmitis. We report a high percentage of culture-positivity, and a high incidence of gram-positive species, and in particular Streptococcus species, with all tested gram-positive organisms susceptible to vancomycin.

To analyze the clinical characteristics and treatment outcomes of patients with bleb-associated endophthalmitis (BAE).Retrospective, noncomparative, interventional case series.Consecutive patients treated at one institution for BAE.Prompt pars plana vitrectomy (PPV) with intravitreal injection of antibiotics, or prompt vitreous biopsy and intravitreal injection of antibiotics (tap and inject).Retrospective analysis of 68 consecutive cases of BAE between July 1, 1989 and June 30, 2001. Clinical presentation, treatment modality, microbiologic data, and clinical course were analyzed. Visual outcomes were compared between vitrectomy and tap-and-inject groups, culture-positive and culture-negative groups, and early and late times.Snellen visual acuities (VAs) at 3 months and 12 months after treatment and at most recent follow-up.The incidence of no light perception (NLP) at 12 months after treatment for BAE was 35%. Vitreous isolates included streptococcal species (32% of positive cultures), Staphylococcus epidermidis (26%), Enterococcus, and Serratia (12% each). Patients with a positive vitreous culture had significantly worse VA (median, hand movements [HM] at 3 and 12 months after treatment) and a higher rate of NLP vision. Patients treated with tap-and-inject had a significantly worse final VA (medians, HM at 3 months and LP at 12 months) and a significantly higher rate of NLP vision than patients treated with PPV. One third of patients who underwent PPV achieved a final VA of 20/100 or better 12 months after treatment (P = 0.09).Bleb-associated endophthalmitis causes significant visual morbidity. Patients with culture-negative BAE and patients treated with prompt PPV may achieve better visual outcome.

The exact frequency and extent of complications after uterine artery embolization (UAE) have yet to be documented in the literature. Ischemic necrosis and rupture of the uterus is a theoretical concern of this procedure. Rupture of the uterus from any cause is a very serious gynecologic complication requiring immediate surgical intervention to prevent death. Ischemic necrosis and rupture of the uterus can occur months after UAE. In our patient they occurred 3 months after UAE for treatment of symptomatic uterine myomas, and required hysterectomy. To our knowledge, this is the first report of ischemic uterine rupture after UAE in the United States.

As periodontics has progressed towards an understanding of the influences of risk factors such as genetics, smoking and stress in the occurrence and severity of periodontal disease, the question of prognosis, so essential to treatment planning, has become even more perplexing to the clinician. A survey of long term clinical practice gives insight into the outcome of therapy relative to initial severity, and modern concepts of bacteria versus host relationships provide directions for greater predictability. However, it is only with observation over time that a more accurate assessment of prognosis can be made, as response to initial therapeutic measures can be determined.

To evaluate the complication and visual outcomes of residents performing temporal clear cornea (TCC) compared to superior scleral tunnel (SST) phacoemulsification.We conducted a retrospective analysis of complications and visual outcomes for 534 phacoemulsification procedures done by third-year residents over a five-year period (June 1992-July 1997) at the department of ophthalmology, University of Chicago. All cases were completed using a TCC or SST incision.There was vitreous loss in 6.0% of 348 eyes with TCC incisions and in 11.8% of 186 eyes with SST incisions (P0.02). Posterior capsule breaks occurred in 1 1.5% of the TCC group versus 17.7% in the SST group (P0.0453). Best corrected visual acuity of 20/40 or better was achieved in 82.5% of all eyes with TCC incisions and in 75.3% of all eyes with SST incisions (P0.05). When 151 patients with previous ophthalmic conditions were excluded, the difference in BCVA between the two groups was not statistically significant.Most institutions train residents with the SST technique prior to advancing to TCC. This study demonstrates that with proper teaching, residents can achieve excellent outcomes using TCC incisions, and can therefore be trained in this technique concurrently with SST incisions.

The Swift/Burst Alert Telescope (BAT) hard X-ray transient monitor provides near real-time coverage of the X-ray sky in the energy range 15-50 keV. The BAT observes 88% of the sky each day with a detection sensitivity of 5.3 mCrab for a full-day observation and a time resolution as fine as 64 seconds. The three main purposes of the monitor are (1) the discovery of new transient X-ray sources, (2) the detection of outbursts or other changes in the flux of known X-ray sources, and (3) the generation of light curves of more than 900 sources spanning over eight years. The primary interface for the BAT transient monitor is a public web page. Between 2005 February 12 and 2013 April 30, 245 sources have been detected in the monitor, 146 of them persistent and 99 detected only in outburst. Among these sources, 17 were previously unknown and were discovered in the transient monitor. In this paper, we discuss the methodology and the data processing and filtering for the BAT transient monitor and review its sensitivity and exposure. We provide a summary of the source detections and classify them according to the variability of their light curves. Finally, we review all new BAT monitor discoveries; for the new sources that are previously unpublished, we present basic data analysis and interpretations., Accepted for publication in the Astrophysical Journal Supplement Series; 85 pages, 22 figures

Peripheral primary cyst of the iris is an uncommon benign condition that may masquerade as a tumor of the ciliary body. Careful examination utilizing the slit lamp and gonioscopy is necessary to successfully differentiate the two.Given their uncommon occurrence and the importance of ruling out melanoma or other malignancies, this review is a guide in the evaluation and diagnosis of patients with this condition.

A system-level simulation tool was developed to understand the challenging trade-offs in integrating PEM fuel cells with both reforming of liquid-fuels (modeled as C12H23) for H2 production and H2 purification with membrane reactors. The model performs iterative detailed thermochemical calculations for mass, species, and energy balances at a component level to assess component operating temperatures and parasitic loads due to compressors (for the cathode flow, autothermal reformer air flow, and anode recirculation flow), pumps (for liquid fuel and water flows for the reformer), and cooling fans (for the fuel cell radiator and the exhaust condenser for water recovery). The results indicate that with current PEM fuel cell polarization curves, thermal efficiencies > 30% can be achieved when parasitic loads are low and fuel cell voltages are high (> 0.75). Water balance can be sustained for the system studied when effective ambient temperatures are

The reduction of gonadotrophin levels, urinary calcium and hot flushes in post-menopausal patients by ethinyl oestradiol is shown to be dose dependent, near maximum response being achieved by a dose of 15 micrograms daily. Equivalent ethinyl oestradiol doses to a number of other gonadal hormone preparations have been assessed using the derived dose-response curve of the reduction in urinary calcium.