4,293 research outputs found
Explainable Severity ranking via pairwise n-hidden comparison: a case study of glaucoma
Primary open-angle glaucoma (POAG) is a chronic and progressive optic nerve
condition that results in an acquired loss of optic nerve fibers and potential
blindness. The gradual onset of glaucoma results in patients progressively
losing their vision without being consciously aware of the changes. To diagnose
POAG and determine its severity, patients must undergo a comprehensive dilated
eye examination. In this work, we build a framework to rank, compare, and
interpret the severity of glaucoma using fundus images. We introduce a
siamese-based severity ranking using pairwise n-hidden comparisons. We
additionally have a novel approach to explaining why a specific image is deemed
more severe than others. Our findings indicate that the proposed severity
ranking model surpasses traditional ones in terms of diagnostic accuracy and
delivers improved saliency explanations.Comment: 4 page
Spectral Energy Distributions of 6.7 GHz methanol masers
The 6.7 GHz maser transition of methanol has been found exclusively towards
massive star forming regions. A majority of the masers have been found to lack
the presence of any associated radio continuum. This could be due to the maser
emission originating prior to the formation of an HII region around the central
star, or from the central object being too cool to produce a HII region. One
way to distinguish between the two scenarios is to determine and model the
spectral energy distributions (SEDs) of the masers. We observed a sample of 20
6.7 GHz methanol masers selected from the blind Arecibo survey, from centimeter
to submillimeter wavelengths. We combined our observations with existing data
from various Galactic plane surveys to determine SEDs from centimeter to
near-infrared wavelengths. We find that 70% of the masers do not have any
associated radio continuum, with the rest of the sources being associated with
hypercompact and ultracompact HII regions. Modeling the SEDs shows them to be
consistent with rapidly accreting massive stars, with accretion rates well
above 10^{-3} M_sun/yr. The upper limits on the radio continuum are also
consistent with any ionized region being confined close to the stellar surface.
This confirms the paradigm of 6.7 GHz methanol masers being signposts of early
phases of massive star formation, mostly prior to the formation of a
hypercompact HII region.Comment: 15 pages, 4 figures; Accepted by A&
Trigonometric Parallaxes of Massive Star-Forming Regions. IX. The Outer Arm in the First Quadrant
We report a trigonometric parallax measurement with the Very Long Baseline
Array for the water maser in the distant high-mass star-forming region
G75.30+1.32. This source has a heliocentric distance of 9.25+-0.45 kpc, which
places it in the Outer arm in the first Galactic quadrant. It lies 200 pc above
the Galactic plane and is associated with a substantial HI enhancement at the
border of a large molecular cloud. At a Galactocentric radius of 10.7 kpc,
G75.30+1.32 is in a region of the Galaxy where the disk is significantly warped
toward the North Galactic Pole. While the star-forming region has an
instantaneous Galactic orbit that is nearly circular, it displays a significant
motion of 18 km/s toward the Galactic plane. The present results, when combined
with two previous maser studies in the Outer arm, yield a pitch angle of about
12 degrees for a large section of the arm extending from the first quadrant to
the third.Comment: 19 pages, 5 figures, 4 tables, accepted by The Astrophysical Journa
Trigonometric Parallaxes of Massive Star Forming Regions: V. G23.01-0.41 and G23.44-0.18
We report trigonometric parallaxes for the massive star-forming regions
G23.01-0.41 and G23.44-0.18, corresponding to distances of 4.59 [+0.38/-0.33]
kpc and 5.88 [+1.37/-0.93] kpc, respectively. The distance to G23.01-0.41 is
smaller than its near kinematic distance assuming a standard model of the Milky
Way and less than half of its far kinematic distance, which has usually been
assumed. This places it in the Crux-Scutum spiral arm. The distance to
G23.44-0.18 is close to its near kinematic distance and most likely places it
in the Norma spiral arm near the end of the Galactic bar. Combining the
distance and proper motions with observed radial velocities gives the location
and full space motion of the star forming regions. We find large deviations
from circular Galactic orbits for these sources: both sources show peculiar
motions of 20 to 30 km/s counter to Galactic rotation and toward the Galactic
center. These large peculiar motions might be the result of gravitational
perturbations from the Galactic bar.Comment: The Astrophysical Journal, accepted, 14 pages, 6 Figures, also
available at http://www.mpifr-bonn.mpg.de/staff/abrunthaler/pub.shtm
The infrared dust bubble N22: an expanding HII region and the star formation around it
Aims. To increase the observational samples of star formation around
expanding Hii regions, we analyzed the interstellar medium and star formation
around N22.
Methods. We used data extracted from the seven large-scale surveys from
infrared to radio wavelengths. In addition we used the JCMT observations of the
J = 3-2 line of 12CO emission data released on CADC and the 12CO J = 2-1 and J
=3-2 lines observed by the KOSMA 3 m telescope. We performed a multiwavelength
study of bubble N22.
Results. A molecular shell composed of several clumps agrees very well with
the border of N22, suggesting that its expansion is collecting the surrounding
material. The high integrated 12CO line intensity ratio (ranging from 0.7 to
1.14) implies that shocks have driven into the molecular clouds. We identify
eleven possible O-type stars inside the Hii region, five of which are located
in projection inside the cavity of the 20 cm radio continuum emission and are
probably the exciting-star candidates of N22. Twenty-nine YSOs (young stellar
objects) are distributed close to the dense cores of N22. We conclude that star
formation is indeed active around N22; the formation of most of YSOs may have
been triggered by the expanding of the Hii region. After comparing the
dynamical age of N22 and the fragmentation time of the molecular shell, we
suggest that radiation-driven compression of pre-existing dense clumps may be
ongoing.Comment: accepted in A&A 30/05/2012. arXiv admin note: text overlap with
arXiv:1010.5430 by other author
Heterologous expression screens in Nicotiana benthamiana identify a candidate effector of the wheat Yellow Rust Pathogen that associates with processing bodies
Rust fungal pathogens of wheat (Triticum spp.) affect crop yields worldwide. The molecular mechanisms underlying the virulence of these pathogens remain elusive, due to the limited availability of suitable molecular genetic research tools. Notably, the inability to perform high-throughput analyses of candidate virulence proteins (also known as effectors) impairs progress. We previously established a pipeline for the fast-forward screens of rust fungal candidate effectors in the model plant Nicotiana benthamiana. This pipeline involves selecting candidate effectors in silico and performing cell biology and protein-protein interaction assays in planta to gain insight into the putative functions of candidate effectors. In this study, we used this pipeline to identify and characterize sixteen candidate effectors from the wheat yellow rust fungal pathogen Puccinia striiformis f sp tritici. Nine candidate effectors targeted a specific plant subcellular compartment or protein complex, providing valuable information on their putative functions in plant cells. One candidate effector, PST02549, accumulated in processing bodies (P-bodies), protein complexes involved in mRNA decapping, degradation, and storage. PST02549 also associates with the P-body-resident ENHANCER OF mRNA DECAPPING PROTEIN 4 (EDC4) from N. benthamiana and wheat. We propose that P-bodies are a novel plant cell compartment targeted by pathogen effectors
The role of magnetic islands in modifying long range temporal correlations of density fluctuations and local heat transport
This work explores the relation between magnetic islands, long range temporal correlations and heat transport. A low order rational surface (t = 3/2) was purposely scanned outward through an electron cyclotron resonance heated (ECRH) plasma in the TJ-II stellarator. Density turbulence and the poloidal flow velocity were characterized using a two channel Doppler reflectometer. Simultaneously, the ECRH power was modulated to characterize heat transport, using measurements from a 12 channel electron cyclotron emission diagnostic. A systematic variation of the poloidal velocity was found to be associated with the t = 3/2 rational surface. Near the rational surface, the Hurst exponent, quantifying the nature of long-range correlations, was reduced below 0.5 (indicating subdiffusion), while at radii smaller than that of the rational surface, it was found to be significantly enhanced (superdiffusion). In the latter region, heat transport was enhanced as well, thus establishing a link between density fluctuations and anomalous heat transport. The observed variation of the Hurst exponent was consistent with a magnetohydrodynamic turbulence simulation
Biometric Risk Factors for Angle Closure Progression After Laser Peripheral Iridotomy
IMPORTANCE: Laser peripheral iridotomy (LPI) is the most common primary treatment for primary angle closure disease (PACD). However, there are sparse data guiding the longitudinal care of PAC suspect (PACS) eyes after LPI. OBJECTIVE: To elucidate the anatomic effects of LPI that are associated with a protective outcome against progression from PACS to PAC and acute angle closure (AAC) and to identify biometric factors that predict progression after LPI. DESIGN, SETTING, AND PARTICIPANTS: This was a retrospective analysis of data from the Zhongshan Angle Closure Prevention (ZAP) trial, a study of mainland Chinese people aged 50 to 70 years with bilateral PACS who received LPI in 1 randomly selected eye. Gonioscopy and anterior-segment optical coherence tomography (AS-OCT) imaging were performed 2 weeks after LPI. Progression was defined as the development of PAC or an acute angle closure (AAC) attack. Cohort A included a random mix of treated and untreated eyes, and cohort B included only eyes treated with LPI. Univariable and multivariable Cox regression models were developed to assess biometric risk factors for progression in cohorts A and B. Data were analyzed from January 4 to December 22, 2022. MAIN OUTCOME AND MEASURE: Six-year progression to PAC or AAC. RESULTS: Cohort A included 878 eyes from 878 participants (mean [SD] age, 58.9 [5.0] years; 726 female [82.7%]) of whom 44 experienced progressive disease. In a multivariable analysis, treatment (hazard ratio [HR], 0.67; 95% CI, 0.34-1.33; P = .25) was no longer associated with progression after adjusting for age and trabecular iris space area at 500 μm (TISA at 500 μm) at the 2-week visit. Cohort B included 869 treated eyes from 869 participants (mean [SD] age, 58.9 [5.0] years; 717 female [82.5%]) of whom 19 experienced progressive disease. In multivariable analysis, TISA at 500 μm (HR, 1.33 per 0.01 mm2 smaller; 95% CI, 1.12-1.56; P = .001) and cumulative gonioscopy score (HR, 1.25 per grade smaller; 95% CI, 1.03-1.52; P = .02) at the 2-week visit were associated with progression. Persistent angle narrowing on AS-OCT (TISA at 500 μm ≤0.05 mm2; HR, 9.41; 95% CI, 3.39-26.08; P <.001) or gonioscopy (cumulative score ≤6; HR, 2.80; 95% CI, 1.13-6.93; P =.04) conferred higher risk of progression. CONCLUSIONS AND RELEVANCE: Study results suggest that persistent angle narrowing detected by AS-OCT or cumulative gonioscopy score was predictive of disease progression in PACS eyes after LPI. These findings suggest that AS-OCT and gonioscopy may be performed to identify patients at high risk of developing angle closure who may benefit from closer monitoring despite patent LPI
Long-Term Risk and Prediction of Progression in Primary Angle Closure Suspect
IMPORTANCE: Identifying primary angle closure suspect (PACS) eyes at risk of angle closure is crucial for its management. However, the risk of progression and its prediction are still understudied in long-term longitudinal studies about PACS. OBJECTIVE: To explore baseline predictors and develop prediction models for the 14-year risk of progression from PACS to primary angle closure (PAC). DESIGN, SETTING, AND PARTICIPANTS: This cohort study involved participants from the Zhongshan Angle Closure Prevention trial who had untreated eyes with PACS. Baseline examinations included tonometry, ultrasound A-scan biometry, and anterior segment optical coherence tomography (AS-OCT) under both light and dark conditions. Primary angle closure was defined as peripheral anterior synechiae in 1 or more clock hours, intraocular pressure (IOP) greater than 24 mm Hg, or acute angle closure. Based on baseline covariates, logistic regression models were built to predict the risk of progression from PACS to PAC during 14 years of follow-up. RESULTS: The analysis included 377 eyes from 377 patients (mean [SD] patient age at baseline, 58.28 [4.71] years; 317 females [84%]). By the 14-year follow-up visit, 93 eyes (25%) had progressed from PACS to PAC. In multivariable models, higher IOP (odds ratio [OR], 1.14 [95% CI, 1.04-1.25] per 1-mm Hg increase), shallower central anterior chamber depth (ACD; OR, 0.81 [95% CI, 0.67-0.97] per 0.1-mm increase), and shallower limbal ACD (OR, 0.96 [95% CI, 0.93-0.99] per 0.01 increase in peripheral corneal thickness) at baseline were associated with an increased 14-year risk of progression from PACS to PAC. As for AS-OCT measurements, smaller light-room trabecular-iris space area (TISA) at 500 μm from the scleral spur (OR, 0.86 [95% CI, 0.77-0.96] per 0.01-mm2 increase), smaller light-room angle recess area (ARA) at 750 μm from the scleral spur (OR, 0.93 [95% CI, 0.88-0.98] per 0.01-mm2 increase), and smaller dark-room TISA at 500 μm (OR, 0.89 [95% CI, 0.80-0.98] per 0.01-mm2 increase) at baseline were identified as predictors for the 14-year risk of progression. The prediction models based on IOP and central and limbal ACDs showed moderate performance (area under the receiver operating characteristic curve, 0.69; 95% CI, 0.63-0.75) in predicting progression from PACS to PAC, and inclusion of AS-OCT metrics did not improve the model's performance. CONCLUSIONS AND RELEVANCE: This cohort study suggests that higher IOP, shallower central and limbal ACDs, and smaller TISA at 500 μm and light-room ARA at 750 μm may serve as baseline predictors for progression to PAC in PACS eyes. Evaluating these factors can aid in customizing PACS management
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