Asymmetric mass ratios for bright double neutron-star mergers.

The discovery of a radioactively powered kilonova associated with the binary neutron-star merger GW170817 remains the only confirmed electromagnetic counterpart to a gravitational-wave event1,2. Observations of the late-time electromagnetic emission, however, do not agree with the expectations from standard neutron-star merger models. Although the large measured ejecta mass3,4 could be explained by a progenitor system that is asymmetric in terms of the stellar component masses (that is, with a mass ratio q of 0.7 to 0.8)5, the known Galactic population of merging double neutron-star systems (that is, those that will coalesce within billions of years or less) has until now consisted only of nearly equal-mass (q > 0.9) binaries6. The pulsar PSR J1913+1102 is a double system in a five-hour, low-eccentricity (0.09) orbit, with an orbital separation of 1.8 solar radii7, and the two neutron stars are predicted to coalesce in [Formula: see text] million years owing to gravitational-wave emission. Here we report that the masses of the pulsar and the companion neutron star, as measured by a dedicated pulsar timing campaign, are 1.62 ± 0.03 and 1.27 ± 0.03 solar masses, respectively. With a measured mass ratio of q = 0.78 ± 0.03, this is the most asymmetric merging system reported so far. On the basis of this detection, our population synthesis analysis implies that such asymmetric binaries represent between 2 and 30 per cent (90 per cent confidence) of the total population of merging binaries. The coalescence of a member of this population offers a possible explanation for the anomalous properties of GW170817, including the observed kilonova emission from that event.

An extreme magneto-ionic environment associated with the fast radio burst source FRB 121102.

Fast radio bursts are millisecond-duration, extragalactic radio flashes of unknown physical origin. The only known repeating fast radio burst source-FRB 121102-has been localized to a star-forming region in a dwarf galaxy at redshift 0.193 and is spatially coincident with a compact, persistent radio source. The origin of the bursts, the nature of the persistent source and the properties of the local environment are still unclear. Here we report observations of FRB 121102 that show almost 100 per cent linearly polarized emission at a very high and variable Faraday rotation measure in the source frame (varying from +1.46 × 105 radians per square metre to +1.33 × 105 radians per square metre at epochs separated by seven months) and narrow (below 30 microseconds) temporal structure. The large and variable rotation measure demonstrates that FRB 121102 is in an extreme and dynamic magneto-ionic environment, and the short durations of the bursts suggest a neutron star origin. Such large rotation measures have hitherto been observed only in the vicinities of massive black holes (larger than about 10,000 solar masses). Indeed, the properties of the persistent radio source are compatible with those of a low-luminosity, accreting massive black hole. The bursts may therefore come from a neutron star in such an environment or could be explained by other models, such as a highly magnetized wind nebula or supernova remnant surrounding a young neutron star.

A direct localization of a fast radio burst and its host.

Fast radio bursts are astronomical radio flashes of unknown physical nature with durations of milliseconds. Their dispersive arrival times suggest an extragalactic origin and imply radio luminosities that are orders of magnitude larger than those of all known short-duration radio transients. So far all fast radio bursts have been detected with large single-dish telescopes with arcminute localizations, and attempts to identify their counterparts (source or host galaxy) have relied on the contemporaneous variability of field sources or the presence of peculiar field stars or galaxies. These attempts have not resulted in an unambiguous association with a host or multi-wavelength counterpart. Here we report the subarcsecond localization of the fast radio burst FRB 121102, the only known repeating burst source, using high-time-resolution radio interferometric observations that directly image the bursts. Our precise localization reveals that FRB 121102 originates within 100 milliarcseconds of a faint 180-microJansky persistent radio source with a continuum spectrum that is consistent with non-thermal emission, and a faint (twenty-fifth magnitude) optical counterpart. The flux density of the persistent radio source varies by around ten per cent on day timescales, and very long baseline radio interferometry yields an angular size of less than 1.7 milliarcseconds. Our observations are inconsistent with the fast radio burst having a Galactic origin or its source being located within a prominent star-forming galaxy. Instead, the source appears to be co-located with a low-luminosity active galactic nucleus or a previously unknown type of extragalactic source. Localization and identification of a host or counterpart has been essential to understanding the origins and physics of other kinds of transient events, including gamma-ray bursts and tidal disruption events. However, if other fast radio bursts have similarly faint radio and optical counterparts, our findings imply that direct subarcsecond localizations may be the only way to provide reliable associations.

A repeating fast radio burst.

Fast radio bursts are millisecond-duration astronomical radio pulses of unknown physical origin that appear to come from extragalactic distances. Previous follow-up observations have failed to find additional bursts at the same dispersion measure (that is, the integrated column density of free electrons between source and telescope) and sky position as the original detections. The apparent non-repeating nature of these bursts has led to the suggestion that they originate in cataclysmic events. Here we report observations of ten additional bursts from the direction of the fast radio burst FRB 121102. These bursts have dispersion measures and sky positions consistent with the original burst. This unambiguously identifies FRB 121102 as repeating and demonstrates that its source survives the energetic events that cause the bursts. Additionally, the bursts from FRB 121102 show a wide range of spectral shapes that appear to be predominantly intrinsic to the source and which vary on timescales of minutes or less. Although there may be multiple physical origins for the population of fast radio bursts, these repeat bursts with high dispersion measure and variable spectra specifically seen from the direction of FRB 121102 support an origin in a young, highly magnetized, extragalactic neutron star.

A millisecond pulsar in a stellar triple system.

Gravitationally bound three-body systems have been studied for hundreds of years and are common in our Galaxy. They show complex orbital interactions, which can constrain the compositions, masses and interior structures of the bodies and test theories of gravity, if sufficiently precise measurements are available. A triple system containing a radio pulsar could provide such measurements, but the only previously known such system, PSR B1620-26 (refs 7, 8; with a millisecond pulsar, a white dwarf, and a planetary-mass object in an orbit of several decades), shows only weak interactions. Here we report precision timing and multiwavelength observations of PSR J0337+1715, a millisecond pulsar in a hierarchical triple system with two other stars. Strong gravitational interactions are apparent and provide the masses of the pulsar M[Symbol: see text](1.4378(13), where M[Symbol: see text]is the solar mass and the parentheses contain the uncertainty in the final decimal places) and the two white dwarf companions (0.19751(15)M[Symbol: see text] and 0.4101(3))M[Symbol: see text], as well as the inclinations of the orbits (both about 39.2°). The unexpectedly coplanar and nearly circular orbits indicate a complex and exotic evolutionary past that differs from those of known stellar systems. The gravitational field of the outer white dwarf strongly accelerates the inner binary containing the neutron star, and the system will thus provide an ideal laboratory in which to test the strong equivalence principle of general relativity.

Transient radio bursts from rotating neutron stars.

The radio sky is relatively unexplored for transient signals, although the potential of radio-transient searches is high. This was demonstrated recently by the discovery of a previously unknown type of source, varying on timescales of minutes to hours. Here we report a search for radio sources that vary on much shorter timescales. We found eleven objects characterized by single, dispersed bursts having durations between 2 and 30 ms. The average time intervals between bursts range from 4 min to 3 h with radio emission typically detectable for <1 s per day. From an analysis of the burst arrival times, we have identified periodicities in the range 0.4-7 s for ten of the eleven sources, suggesting origins in rotating neutron stars. Despite the small number of sources detected at present, their ephemeral nature implies a total Galactic population significantly exceeding that of the regularly pulsing radio pulsars. Five of the ten sources have periods >4 s, and the rate of change of the pulse period has been measured for three of them; for one source, we have inferred a high magnetic field strength of 5 x 10(13) G. This suggests that the new population is related to other classes of isolated neutron stars observed at X-ray and gamma-ray wavelengths.

An expanding radio nebula produced by a giant flare from the magnetar SGR 1806-20.

Soft gamma-ray repeaters (SGRs) are 'magnetars', a small class of slowly spinning neutron stars with extreme surface magnetic fields, B approximately 10(15) gauss (refs 1 , 2 -3). On 27 December 2004, a giant flare was detected from the magnetar SGR 1806-20 (ref. 2), only the third such event recorded. This burst of energy was detected by a variety of instruments and even caused an ionospheric disturbance in the Earth's upper atmosphere that was recorded around the globe. Here we report the detection of a fading radio afterglow produced by this outburst, with a luminosity 500 times larger than the only other detection of a similar source. From day 6 to day 19 after the flare from SGR 1806-20, a resolved, linearly polarized, radio nebula was seen, expanding at approximately a quarter of the speed of light. To create this nebula, at least 4 x 10(43) ergs of energy must have been emitted by the giant flare in the form of magnetic fields and relativistic particles.

An increased estimate of the merger rate of double neutron stars from observations of a highly relativistic system.

The merger of close binary systems containing two neutron stars should produce a burst of gravitational waves, as predicted by the theory of general relativity. A reliable estimate of the double-neutron-star merger rate in the Galaxy is crucial in order to predict whether current gravity wave detectors will be successful in detecting such bursts. Present estimates of this rate are rather low, because we know of only a few double-neutron-star binaries with merger times less than the age of the Universe. Here we report the discovery of a 22-ms pulsar, PSR J0737-3039, which is a member of a highly relativistic double-neutron-star binary with an orbital period of 2.4 hours. This system will merge in about 85 Myr, a time much shorter than for any other known neutron-star binary. Together with the relatively low radio luminosity of PSR J0737-3039, this timescale implies an order-of-magnitude increase in the predicted merger rate for double-neutron-star systems in our Galaxy (and in the rest of the Universe).

Self-monitoring of Blood Pressure in Patients With Hypertension-Related Multi-morbidity: Systematic Review and Individual Patient Data Meta-analysis.

BACKGROUND: Studies have shown that self-monitoring of blood pressure (BP) is effective when combined with co-interventions, but its efficacy varies in the presence of some co-morbidities. This study examined whether self-monitoring can reduce clinic BP in patients with hypertension-related co-morbidity. METHODS: A systematic review was conducted of articles published in Medline, Embase, and the Cochrane Library up to January 2018. Randomized controlled trials of self-monitoring of BP were selected and individual patient data (IPD) were requested. Contributing studies were prospectively categorized by whether they examined a low/high-intensity co-intervention. Change in BP and likelihood of uncontrolled BP at 12 months were examined according to number and type of hypertension-related co-morbidity in a one-stage IPD meta-analysis. RESULTS: A total of 22 trials were eligible, 16 of which were able to provide IPD for the primary outcome, including 6,522 (89%) participants with follow-up data. Self-monitoring was associated with reduced clinic systolic BP compared to usual care at 12-month follow-up, regardless of the number of hypertension-related co-morbidities (-3.12 mm Hg, [95% confidence intervals -4.78, -1.46 mm Hg]; P value for interaction with number of morbidities = 0.260). Intense interventions were more effective than low-intensity interventions in patients with obesity (P < 0.001 for all outcomes), and possibly stroke (P < 0.004 for BP control outcome only), but this effect was not observed in patients with coronary heart disease, diabetes, or chronic kidney disease. CONCLUSIONS: Self-monitoring lowers BP regardless of the number of hypertension-related co-morbidities, but may only be effective in conditions such obesity or stroke when combined with high-intensity co-interventions.

H2O2 mediates O2 toxicity in cultured fetal rat distal lung epithelial cells.

It is unknown which of the reactive oxygen species is primarily responsible for the cytotoxicity of 95% O2 for rat distal fetal lung epithelial cells in vitro. Incubation of cells with 25 U/ml polyethylene glycol (PEG)-conjugated SOD and 50 U/ml PEG-catalase, but not PEG-SOD or SOD mimics alone, significantly reduced 95% O2-mediated cytotoxicity. Liposome-entrapped catalase, without SOD, also significantly reduced 95% O2-mediated cytotoxicity. Increased formation of lipid hydroperoxides, as assessed by the formation of 8-isoprostane and aldehydes, was attenuated by both 100 microM Trolox, a vitamin E analogue, and by 5 microM U74389G, an amino steroid. Trolox, but not U74389G, prevented an increase in cell-derived H2O2, hydroxyl radical and 95% O2-mediated cytotoxicity. An increase in hydroxyl radical formation, but not cell death, observed in 95% O2, was prevented by 0.1 microM phenanthrolene, a cell permeant iron chelator. DNA extracts of rat distal fetal lung epithelial cells maintained under serum-free conditions had an electrophoretic pattern consistent with some degree of apoptosis. However, no increase in laddering was seen with exposure to 95% O2. These data are consistent with hydrogen peroxide, but not lipid hydroperoxides or hydroxyl radical, being a critical effector of O2-mediated necrotic cell death in distal lung epithelial cells.

Establishment of cell lines of uveal melanoma. Methodology and characteristics.

Six continuous cell lines have been established from choroidal and ciliary body melanomas. These lines have been maintained in culture for at least 100 in vitro population doublings for periods over 1 year. They were established initially using a human diploid fibroblast strain MRC-5 as a feeder layer. Cells were grown in Ham's F-12 medium containing fetal bovine and horse sera and supplemented with glucose, cholera toxin, and epidermal growth factor. Culture doubling times ranged from 72-96 hr; cloning efficiencies ranged from 1-5% in the absence of a feeder layer. Six cell lines were studied in detail by electron microscopy, and all were found to have evidence of melanosomes and/or premelanosomes. The morphology of the cells was characteristic of melanomas as defined by the Callender classification, with cell types ranging from spindle A to epithelioid. Karyotypic studies revealed the presence of only human chromosomes with modal numbers ranging from 48-54 in the different lines.

Effects of 5-(N,N-diethylamino)-n-pentyl-3,4,5-trimethoxybenzoate hydrochloride (TMB-5) on cardiovascular systems.

The effects of 5-(N,N-diethylamino)-pentyl-3,4,5-trimethoxybenzoate hydrochloride (TMB-5) were studied pharmacologically on smooth muscle, skeletal muscle, blood vessel and cardiac preparations. In all cases, TMB-5 inhibited muscle contractions induced by muscle stimulants such as acetylcholine, norepinephrine, KCl and BaCl2, indicating that the muscle inhibition induced by TMB-5 is unrelated to specific receptors. TMB-5 was found to be most potent in inhibiting skeletal muscles (at 10(-6)-10(-5) M level) and least effective in inhibiting smooth muscles (at 10(-4)-10(-3) M level). The potency of vascular inhibition was in between these two levels (at 10(-4) M level). The ability of TMB-5 to raise the threshold of cardiac arrhythmias was quite good at 7X10(-7)-7X10(-6) M. It is concluded that TMB-5 could be a good antiarrhythmic agent with some skeletal muscle relaxation action.

Thermodynamics of hydrolysis of oligosaccharides.

Microcalorimetry has been used to determine enthalpy changes for the hydrolysis of a series of oligosaccharides. High-pressure liquid chromatography was used to determine the extents of reaction and to check for any possible side reactions. The enzyme glucan 1,4-alpha-glucosidase was used to bring about the following hydrolysis reactions: (A) maltose(aq) + H2O(liq) = 2D-glucose(aq); (B) maltotriose(aq) + 2H2O(liq) = 3D-glucose(aq); (C) maltotetraose(aq) + 3H2O(liq) = 4D-glucose(aq); (D) maltopentaose(aq) + 4H2O(liq) = 5D-glucose(aq); (E) maltohexaose(aq) + 5H2O(liq) = 6D-glucose(aq); (F) maltoheptaose(aq) + 6H2O(liq) = 7D-glucose(aq); (G) amylose(aq) + nH2O(liq) = (n + 1) D-glucose(aq); and (H) panose(aq) + 2H2O(liq) = 3D-glucose(aq); (J) isomaltotriose(aq) + 2H2O(liq) = 3D-glucose(aq). The enzyme beta-fructofuranosidase was used for the reactions: (K) raffinose(aq) + H2O(liq) = alpha-D-melibiose(aq) + D-fructose(aq); and (L) stachyose(aq) + H2O(liq) = o-alpha-D-galactopyranosyl-(1----6)- alpha-o-D-galactopyranosyl-(1----6)-alpha-D-glucopyranose + D-fructose(aq). The results of the calorimetric measurements (298.15 K, 0.1 M sodium acetate buffer, pH 4.44-6.00) are: delta H0A = -4.55 +/- 0.10, delta H0B = -9.03 +/- 0.10, delta H0C = -13.79 +/- 0.15, delta H0D = -18.12 +/- 0.10, delta H0E = -22.40 +/- 0.15, delta H0F = -26.81 +/- 0.20, delta H0H = 1.46 +/- 0.40, delta H0J = 11.4 +/- 2.0, delta H0K = -15.25 +/- 0.20, and delta H0L = -14.93 +/- 0.20 kJ mol-1. The enthalpies of hydrolysis of two different samples of amylose were 1062 +/- 20 and 2719 +/- 100 kJ mol-1, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

The Patient Findings Questionnaire: one solution to an important standardized patient examination problem.

PURPOSE: To describe the Patient Findings Questionnaire (PFQ) and compare its scores and pass/fail decisions with those obtained from standardized patient (SP) examination checklists. METHOD: Checklists and PFQs were used to assess data acquisition by 790 second-year medical students. PFQs were composed of multiple-choice items designed to determine whether examines had acquired key historical patient information. RESULTS: At the item level, the two measurement methods yielded the same decisions about data acquisition on 88% of observed occasions. Most discrepancies (74%) involved SPs rating examinees as having elicited information when the examinee was unable to answer the associated PFQ item. At the test level, the two instruments yielded the same pass/fail decision on a large majority of occasions. CONCLUSIONS: The PFQ and checklist yielded similar data acquisition scores and decisions at the item and test levels. Replacement of the checklist with the PFQ should result in examinees' behaving in a way more consistent with recommended interviewing practices.

Effect of avian-human joint attention on allospecific vocal learning by grey parrots (Psittacus erithacus).

The authors studied whether grey parrots (Psittacus erithacus) would learn referential English vocalizations if training lacked full social interaction with humans. In previous studies, grey parrots learned human vocalizations most readily when training simultaneously demonstrated the meaning (full reference) and function (full contextual applicability) of the utterance and actively engaged the subject in learning (full interaction). Those studies, however, did not contrast effects of limited and full interaction or examine how interaction affects contextual applicability. Because an important factor in child language acquisition is joint attention-the social interaction between caretaker and human infant concerning objects and actions in their environment-the authors contrasted training in which joint attention was present or absent (i.e., full vs. limited interaction) and found that 2 parrots did not learn in the absence of joint attention but did learn English labels when full interaction was present.

The three mechanisms for coronary artery disease progression: insights into future management.

The basic mechanisms of atherosclerotic progression have been well elucidated during the last few years. Basic experimental and clinical information has helped define the three stages of progression. In this review we outline the pathologic and clinical differences between slow, rapid, and intermediate progression. The eight morphologically different lesions (types I, II, III, IV, Va, Vb, Vc, and VI) in their various stages are defined. The relationship between specific type of lesion and chronic endothelial injury, cardiac risk factors, and increased vascular permeability to lipids is noteworthy. In regard to the acute coronary syndromes, the fate of plaque rupture and our understanding of "passive" vs. "active" rupture are defined. In addition to the phenomenon of plaque rupture, the thrombogenicity of atherosclerotic plaques in the genesis of coronary syndromes is described. The combination of plaque disruption and a high thrombogenic risk profile--including local and systemic factors--is vital to understanding the genesis of the acute coronary syndromes. In approaching the use of these new insights to arrest or reverse the atherosclerotic process, it is essential to remember that the disease process starts early in life and takes many years to progress to the symptomatic stage. The future holds promise for the development of preventive strategies to halt the progression of coronary disease--the number one killer in the United States.

Rapid analysis of sugars in fruit juices by FT-NIR spectroscopy.

A simple analytical procedure using FT-NIR and multivariate techniques for the rapid determination of individual sugars in fruit juices was evaluated. Different NIR detection devices and sample preparation methods were tested by using model solutions to determine their analytical performance. Aqueous solutions of sugar mixtures (glucose, fructose, and sucrose; 0-8% w/v) were used to develop a calibration model. Direct measurements were made by transflection using a reflectance accessory, by transmittance using a 0.5-mm cell, and by reflectance using a fiberglass paper filter. FT-NIR spectral data were transformed to the second derivative. Partial least-squares regression (PLSR) was used to create calibration models that were cross-validated (leave-one-out approach). The prediction ability of the models was evaluated on fruit juices and compared with HPLC and standard enzymatic techniques. The PLSR loading spectra showed characteristic absorption bands for the different sugars. Models generated from transmittance spectra gave the best performance with standard error of prediction (SEP) <0.10% and R(2) of 99.9% that accurately and precisely predicted the sugar levels in juices, whereas lower precision was obtained with models generated from reflectance spectra. FT-NIR spectroscopy allowed for the rapid ( approximately 3 min analysis time), accurate and non-destructive analysis of sugars in juices and could be applied in quality control of beverages or to monitor for adulteration or contamination.

Aqueous humor dynamics in monkeys with laser-induced glaucoma.

This study determines the effects of laser-induced glaucoma on aqueous humor dynamics of 18 cynomolgus monkeys. Baseline measurements of 12 monkeys included intraocular pressure (IOP) by pneumatonometry, aqueous flow by fluorophotometry and outflow facility by tonography. Beginning 4 to 14 days later, the trabecular meshwork of one eye was treated repeatedly with laser photocoagulation until elevated IOP was induced. Thirty-six to 75 days after the last laser treatment, all measurements were repeated. Between 1.7 and 11.4 years after laser treatment, the same 12 monkeys plus 6 additional monkeys underwent IOP and aqueous flow measurements. In addition, outflow facility was determined with fluorophotometry, and uveoscleral outflow was both calculated (n=18) and measured with an intracameral tracer (n=7). In glaucoma eyes compared to control eyes (n=12), IOP was increased (p<0.04) by at least 8 mmHg at Time 1 (1 to 3 months) or Time 2 (3 to 4 years) after laser treatment; aqueous flow was reduced (p=0.0007) by 46% at Time 1 but returned to baseline levels at Time 2; tonographic outflow facility was reduced (p=0.0008) by 71% at Time 1. In lasered eyes compared to control eyes, fluorophotometric outflow facility was reduced (p=0.0008; n=18) by 63%, and uveoscleral outflow was increased (p<0.05), whether calculated or measured with tracers at least 1 year after laser treatment. The increased IOP in monkeys with laser-induced glaucoma was caused by a sustained reduction in outflow facility. The uveoscleral outflow increase was not enough to prevent the rise in IOP.

Preclinical efficacy of travoprost, a potent and selective FP prostaglandin receptor agonist.

Travoprost is the isopropyl ester prodrug of a high affinity, selective FP prostaglandin full receptor agonist. In contrast to travoprost acid's high affinity and efficacy at the FP receptor, there is only sub-micromolar affinity for the DP, EP1, EP3, EP4, IP, and TP receptors. Travoprost produced a lower incidence of ocular irritation than PGF20 isopropyl ester at a dose of 1 microg in the New Zealand albino (NZA) rabbit. Topical ocular application of travoprost produced a marked miotic effect in cats following doses of 0.01, 0.03 and 0.1 microg. In the ocular hypertensive monkey, b.i.d. application of 0.1 and 0.3 microg of travoprost afforded peak reduction in intraocular pressure (IOP) of 22.7% and 28.6%, respectively. Topical application of travoprost was well tolerated in rabbits, cats and monkeys, causing no ocular irritation or discomfort at doses up to 1 microg. Travoprost is a promising ocular hypotensive prostaglandin FP derivative that has the ocular hypotensive efficacy of PGF2alpha isopropyl ester but with less severe ocular side effects.

Exercise in the healthy older adult.

Habitual exercise provides numerous health benefits to the older adult. While dynamic aerobic activities increase stamina and lung capacity, isometric or resistance training improves muscle strength and endurance. Long-term benefits of continued exercise include a decreased risk of death from heart disease, enhanced balance and mobility, a decreased risk of diabetes, and an improvement in depressive symptoms. While the hazards of exercise relate predominantly to extremes of intensity and duration, all older adults should consult with a physician before beginning a new activity program. A prescription for exercise should include both aerobic and resistance training components, and frequent follow-up to improve adherence is highly recommended.