267 research outputs found
Support Vector Machine classification of strong gravitational lenses
The imminent advent of very large-scale optical sky surveys, such as Euclid
and LSST, makes it important to find efficient ways of discovering rare objects
such as strong gravitational lens systems, where a background object is
multiply gravitationally imaged by a foreground mass. As well as finding the
lens systems, it is important to reject false positives due to intrinsic
structure in galaxies, and much work is in progress with machine learning
algorithms such as neural networks in order to achieve both these aims. We
present and discuss a Support Vector Machine (SVM) algorithm which makes use of
a Gabor filterbank in order to provide learning criteria for separation of
lenses and non-lenses, and demonstrate using blind challenges that under
certain circumstances it is a particularly efficient algorithm for rejecting
false positives. We compare the SVM engine with a large-scale human examination
of 100000 simulated lenses in a challenge dataset, and also apply the SVM
method to survey images from the Kilo-Degree Survey.Comment: Accepted by MNRA
Observations of radio-quiet quasars at 10mas resolution by use of gravitational lensing
We present VLA detections of radio emission in four four-image gravitational
lens systems with quasar sources: HS0810+2554, RXJ0911+0511, HE04351223 and
SDSSJ0924+0219, and e-MERLIN observations of two of the systems. The first
three are detected at a high level of significance, and SDSS J0924+0219 is
detected. HS0810+2554 is resolved, allowing us for the first time to achieve
10-mas resolution of the source frame in the structure of a radio quiet quasar.
The others are unresolved or marginally resolved. All four objects are among
the faintest radio sources yet detected, with intrinsic flux densities in the
range 1-5Jy; such radio objects, if unlensed, will only be observable
routinely with the Square Kilometre Array. The observations of HS0810+2554,
which is also detected with e-MERLIN, strongly suggest the presence of a
mini-AGN, with a radio core and milliarcsecond scale jet. The flux densities of
the lensed images in all but HE0435-1223 are consistent with smooth galaxy lens
models without the requirement for smaller-scale substructure in the model,
although some interesting anomalies are seen between optical and radio flux
densities. These are probably due to microlensing effects in the optical.Comment: Accepted by MNRA
Prune Belly Syndrome
Prune belly syndrome is a rare congenital disorder of the urinary system, characterized by a triad of abnormalities. The aetiology is not known. Many infants are either stillborn or die within the first few weeks of life from severe lung or kidney problems, or a combination of congenital anomalies
Effect of Rhizobium and Phosphate Solubilizing Bacterial Inoculants on Symbiotic Traits, Nodule Leghemoglobin, and Yield of Chickpea Genotypes
A field experiment was carried out during the rabi season of 2004-05 to find out the effect of Rhizobium and phosphate solubilizing bacterial (PSB) inoculants on symbiotic traits, nodule leghemoglobin, and yield of five elite genotypes of chickpea. Among the chickpea genotypes, IG-593 performed better in respect of symbiotic parameters including nodule number, nodule fresh weight, nodule dry weight, shoot dry weight, yield attributes and yield. Leghemoglobin content (2.55 mg g −1 of fresh nodule) was also higher under IG-593. Among microbial inoculants, the Rhizobium + PSB was found most effective in terms of nodule number (27.66 nodules plant −1 ), nodule fresh weight (144.90 mg plant −1 ), nodule dry weight (74.30 mg plant −1 ), shoot dry weight (11.76 g plant −1 ), and leghemoglobin content (2.29 mg g −1 of fresh nodule) and also showed its positive effect in enhancing all the yield attributing parameters, grain and straw yields
The Atacama Cosmology Telescope: CO(J = 3 - 2) mapping and lens modeling of an ACT-selected dusty star-forming galaxy
We report Northern Extended Millimeter Array (NOEMA) CO()
observations of the dusty star-forming galaxy ACT-S\,J020941+001557 at , which was detected as an unresolved source in the Atacama Cosmology
Telescope (ACT) equatorial survey. Our spatially resolved spectral line data
support the derivation of a gravitational lens model from 37 independent
velocity channel maps using a pixel-based algorithm, from which we infer a
velocity-dependent magnification factor with a
luminosity-weighted mean \left\approx 13. The resulting
source-plane reconstruction is consistent with a rotating disk, although other
scenarios cannot be ruled out by our data. After correction for lensing, we
derive a line luminosity , a cold gas mass , a dynamical mass , and a gas mass
fraction . The line brightness
temperature ratio of relative to a Green Bank Telescope
CO() detection may be elevated by a combination of external heating of
molecular clouds, differential lensing, and/or pointing errors.Comment: 8 pages, 5 figures, accepted to Ap
Detectability of colorectal neoplasia with fluorine-18-2-fluoro-2-deoxy-D-glucose positron emission tomography and computed tomography (FDG-PET/CT)
The purpose of this study was to analyze the detectability of colorectal neoplasia with fluorine-18-2-fluoro-2-deoxy-d-glucose positron emission tomography/computed tomography (FDG-PET/CT).
Data for a total of 492 patients who had undergone both PET/CT and colonoscopy were analyzed. After the findings of PET/CT and colonoscopy were determined independently, the results were compared in each of the six colonic sites examined in all patients. The efficacy of PET/CT was determined using colonoscopic examination as the gold standard.
In all, 270 colorectal lesions 5 mm or more in size, including 70 pathologically confirmed malignant lesions, were found in 172 patients by colonoscopy. The sensitivity and specificity of PET/CT for detecting any of the colorectal lesions were 36 and 98%, respectively. For detecting lesions 11 mm or larger, the sensitivity was increased to 85%, with the specificity remaining consistent (97%). Moreover, the sensitivity for tumors 21 mm or larger was 96% (48/50). Tumors with malignant or high-grade pathology were likely to be positive with PET/CT. A size of 10 mm or smaller [odds ratio (OR) 44.14, 95% confidence interval (95% CI) 11.44-221.67] and flat morphology (OR 7.78, 95% CI 1.79-36.25) were significant factors that were associated with false-negative cases on PET/CT.
The sensitivity of PET/CT for detecting colorectal lesions is acceptable, showing size- and pathology-dependence, suggesting, for the most part, that clinically relevant lesions are detectable with PET/CT. However, when considering PET/CT for screening purposes caution must be exercised because there are cases of false-negative results
Dinoprostone vaginal insert (DVI) versus adjunctive sweeping of membranes and DVI for term induction of labor.
AIM: To compare the efficacy and safety of dinoprostone vaginal insert (DVI) alone versus DVI with adjunctive sweeping of membranes (ASM) for induction of labor (IOL). METHODS: Single-center, prospective, randomized controlled trial; women with singleton term pregnancies, cervical dilation ≥1 and <3 cm, intact membranes allocated to either DVI or DVI with ASM. The primary outcome was vaginal delivery within 24 h of insertion. Secondary outcomes included mean time from insertion to delivery, tachysystole, operative delivery for non-reassuring fetal status (NRFS), tocolytics, fetal outcomes, pain information, and subject satisfaction. RESULTS: One hundred and four received DVI (Group 1) alone and 104 DVI with ASM (Group 2). The rate of vaginal delivery within 24 h was 53% versus 56%, cesarean rate 8.7% versus 10.6% in Groups 1 and 2 respectively. Although the duration of labor was similar in both groups, about 6% of women required additional ripening with dinoprostone vaginal tablets in Group 2 compared to 11.5% in Group 1 (p-value = 0.2). The frequency of hyperstimulation syndrome, failed induction, analgesic requirements, and fetal outcomes were comparable. The majority (83%-86%) in either cohort were satisfied with their labor experience. Multivariate logistic regression demonstrated a slightly better chance for vaginal delivery within 24 h (odds ratio [OR] 1.22 [95% confidence interval, CI 0.65-2.29]; p-value 0.53] for DVI with ASM, although statistically insignificant. Younger maternal age and multiparity (OR 10.36 [95% CI 4.88-23.67]; p-value <0.0001) contributed to successful IOL. CONCLUSION: DVI with ASM is at least as efficacious as DVI for cervical ripening with no increase in morbidity. Although DVI with ASM group less often needed additional dinoprostone tablets to complete the process of IOL (p-value = 0.2), adjunctive sweeping has not been shown to have a significant impact on the duration of labor or mode of delivery
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