Transfer of ultra-low phase noise microwave references over the JANET Aurora fibre network using a femtosecond optical frequency comb

An ultra-low phase noise microwave frequency is transferred over 82 km of installed fibre by propagation of a 30 nm bandwidth optical frequency comb (104 modes). The phase noise induced along the fibre by vibrations and thermal effects is suppressed by implementing a noise cancellation scheme where a portion of the light is sent back to the transmitter through the same fibre. The 6th harmonic of the repetition rate detected before and after the pulse train has travelled a round trip are phase compared and used to generate an error signal that controls a fibre stretcher to compensate for the fibre-induced phase fluctuations. Optical amplifiers are used to compensate for the fibre attenuation and dispersion compensation modules are also employed

Phantom Maps and Homology Theories

We study phantom maps and homology theories in a stable homotopy category S via a certain Abelian category A. We express the group P(X,Y) of phantom maps X -> Y as an Ext group in A, and give conditions on X or Y which guarantee that it vanishes. We also determine P(X,HB). We show that any composite of two phantom maps is zero, and use this to reduce Margolis's axiomatisation conjecture to an extension problem. We show that a certain functor S -> A is the universal example of a homology theory with values in an AB 5 category and compare this with some results of Freyd.Comment: 25 pages, AMSLaTeX, to appear in Topolog

Generalised Moore spectra in a triangulated category

In this paper we consider a construction in an arbitrary triangulated category T which resembles the notion of a Moore spectrum in algebraic topology. Namely, given a compact object C of T satisfying some finite tilting assumptions, we obtain a functor which "approximates" objects of the module category of the endomorphism algebra of C in T. This generalises and extends a construction of Jorgensen in connection with lifts of certain homological functors of derived categories. We show that this new functor is well-behaved with respect to short exact sequences and distinguished triangles, and as a consequence we obtain a new way of embedding the module category in a triangulated category. As an example of the theory, we recover Keller's canonical embedding of the module category of a path algebra of a quiver with no oriented cycles into its u-cluster category for u>1.Comment: 26 pages, improvement to exposition of the proof of Theorem 3.

Gorenstein duality for real spectra

Following Hu and Kriz, we study the C 2 -spectra BPℝ⟨n⟩hni and Eℝ(n) that refine the usual truncated Brown-Peterson and the Johnson-Wilson spectra. In particular, we show that they satisfy Gorenstein duality with a representation grading shift and identify their Anderson duals. We also compute the associated local cohomology spectral sequence in the cases n = 1 and 2

MODIFICATION BY FRAILTY STATUS OF AMBIENT AIR POLLUTION EFFECTS ON LUNG FUNCTION IN OLDER ADULTS IN THE CARDIOVASCULAR HEALTH STUDY

Older adult susceptibility to air pollution health effects is well-recognized. Advanced age may act as a partial surrogate for conditions associated with aging. The authors investigated whether gerontologic frailty (a clinical health status metric) modified the effects of ambient ozone or particulate matter (PM10) air pollution on lung function in 3382 older adults using 7 years of followup data from the Cardiovascular Health Study (CHS) and the CHS Environmental Factors Ancillary Study. Monthly average pollution and annual frailty assessments were related to up to 3 repeated measurements of lung function using novel cumulative summaries of pollution and frailty histories that account for duration as well as concentration. Frailty history was found to modify long-term pollution effects on Forced Vital Capacity (FVC). For example, the decrease in FVC associated with a 70 ppb-month increase in the cumulative sum of monthly average O3 exposure was 8.8 mL (95% confidence interval (CI): 7.4, 10.1) for a woman who had spent the prior 7 years prefrail or frail compared to 3.3 mL (95% CI: 2.7, 4.0) for a similar not frail woman (interaction P\u3c0.001)

Smartphone-based, rapid, wide-field fundus photography for diagnosis of pediatric retinal diseases

PurposeAn important, unmet clinical need is for cost-effective, reliable, easy-to-use, and portable retinal photography to evaluate preventable causes of vision loss in children. This study presents the feasibility of a novel smartphone-based retinal imaging device tailored to imaging the pediatric fundus.MethodsSeveral modifications for children were made to our previous device, including a child-friendly 3D printed housing of animals, attention-grabbing targets, enhanced image stitching, and video-recording capabilities. Retinal photographs were obtained in children undergoing routine dilated eye examination. Experienced masked retina-specialist graders determined photograph quality and made diagnoses based on the images, which were compared to the treating clinician's diagnosis.ResultsDilated fundus photographs were acquired in 43 patients with a mean age of 6.7 years. The diagnoses included retinoblastoma, Coats' disease, commotio retinae, and optic nerve hypoplasia, among others. Mean time to acquire five standard photographs totaling 90-degree field of vision was 2.3 ± 1.1 minutes. Patients rated their experience of image acquisition favorably, with a Likert score of 4.6 ± 0.8 out of 5. There was 96% agreement between image-based diagnosis and the treating clinician's diagnosis.ConclusionsWe report a handheld smartphone-based device with modifications tailored for wide-field fundus photography in pediatric patients that can rapidly acquire fundus photos while being well-tolerated.Translational relevanceAdvances in handheld smartphone-based fundus photography devices decrease the technical barrier for image acquisition in children and may potentially increase access to ophthalmic care in communities with limited resources