16 research outputs found
Obscuration beyond the nucleus: infrared quasars can be buried in extreme compact starbursts
In the standard quasar model, the accretion disk obscuration is due to the
canonical dusty torus. Here, we argue that a substantial part of the quasar
obscuration can come from the interstellar medium (ISM) when the quasars are
embedded in compact starbursts. We use an obscuration-unbiased sample of 578
infrared (IR) quasars at and archival ALMA submillimeter host
galaxy sizes to investigate the ISM contribution to the quasar obscuration. We
calculate SFR and ISM column densities for the IR quasars and a control sample
of submillimeter galaxies (SMGs) not hosting quasar activity and show that: (1)
the quasar obscured fraction is constant up to , and then increases towards higher SFR, suggesting that the ISM
obscuration plays a significant role in starburst host galaxies, and (2) at
, the SMGs and IR quasars have
similarly compact submillimeter sizes () and,
consequently, the ISM can heavily obscure the quasar, even reaching
Compton-thick () levels in extreme cases.
Based on our results, we infer that of the IR quasars with
are obscured solely by the ISM.Comment: Accepted for publication in MNRAS Letter
Cost efficient prediction of Cabernet Sauvignon wine quality
The quality of wines can be assessed both from chemical/biological tests and sensory tests (which rely mainly on human experts). Determining which is the subset of tests to be used is a difficult problem. Each test has its own contribution for predicting the quality of wines and, in addition, its own cost. We use our own database, consisting of 32 wine characteristics applied to 180 wine samples. In addition we use wine quality labels assigned by a wine expert. To the extent of our knowledge, this is the first study of this kind on wines from Washington State, and also the first wine study in general to include cost minimization of the measurements as a goal. Our approach is based on two stages. First, we identify reasonably good classifiers (from a given set of classifiers). Next, we search for the optimal subset of features to maximize the performance of the best classifier and also minimize the overall cost of the measurements. As a result, through our method we can answer queries like âthe best performing subset of tests for a given threshold costâ
Pacing strategy and change in body composition during a deca iron triathlon
We investigated the timeline of performances in the three races of the âWorld Challenge Deca Iron
Triathlonâ, held in 2006, 2007 and 2009, where the athletes completed one Ironman triathlon daily on 10
consecutive days. The association of anthropometric characteristics such as body fat estimated using
bioelectrical impedance analysis and previous experience in ultra-triathlon with race time was investigated
using multiple linear regression analysis. Forty-nine athletes participated in these three races; 23 (47%)
participants completed the race within 8,817 (1,322) min. Day 1 was the fastest with 762 (86) min; the
slowest was Day 10 with 943 (167) min (P < 0.05). The time per Ironman increased during the race
(P < 0.05). Body mass and fat mass decreased whereas lean body mass increased (P < 0.05). Race time
was related to both the number of finished Triple Iron triathlons (P = 0.028) and the personal best time
in a Triple Iron triathlon (P < 0.0001). We concluded that performance in a Deca Iron triathlon decreased throughout the competition, with the fastest race on Day 1 and the slowest on Day 10. The number of finished Triple Iron triathlons and the personal best time in a Triple Iron triathlon, but not anthropometry, were related to race time. To conclude, athletes need to have a high number of previously completed Triple Iron triathlons, as well as a fast personal best time in a Triple Iron triathlon, in order to finish a Deca Iron triathlon successfully
Fuzzy ARTMAP Prediction of Biological Activities for Potential HIV-1 Protease Inhibitors Using a Small Molecular Data Set
Obtaining satisfactory results with neural networks depends on the availability of large data samples. The use of small training sets generally reduces performance. Most classical Quantitative Structure-Activity Relationship (QSAR) studies for a specific enzyme system have been performed on small data sets. We focus on the neuro-fuzzy prediction of biological activities of HIV-1 protease inhibitory compounds when inferring from small training sets. We propose two computational intelligence prediction techniques which are suitable for small training sets, at the expense of some computational overhead. Both techniques are based on the FAMR model. The FAMR is a Fuzzy ARTMAP (FAM) incremental learning system used for classification and probability estimation. During the learning phase, each sample pair is assigned a relevance factor proportional to the importance of that pair. The two proposed algorithms in this paper are: 1) The GA-FAMR algorithm, which is new, consists of two stages: a) During the first stage, we use a genetic algorithm (GA) to optimize the relevances assigned to the training data. This improves the generalization capability of the FAMR. b) In the second stage, we use the optimized relevances to train the FAMR. 2) The Ordered FAMR is derived from a known algorithm. Instead of optimizing relevances, it optimizes the order of data presentation using the algorithm of Dagher et al. In our experiments, we compare these two algorithms with an algorithm not based on the FAM, the FS-GA-FNN introduced in . We conclude that when inferring from small training sets, both techniques are efficient, in terms of generalization capability and execution time. The computational overhead introduced is compensated by better accuracy. Finally, the proposed techniques are used to predict the biological activities of newly designed potential HIV-1 protease inhibitors
Host Dark Matter Halos of Wide-field Infrared Survey Explorer-selected Obscured and Unobscured Quasars: Evidence for Evolution
Obscuration in quasars may arise from steep viewing angles along the dusty torus, or instead may represent a distinct phase of supermassive black hole growth. We test these scenarios by probing the host dark matter halo environments of âŒ1.4 million Wide-field Infrared Survey Explorer-selected obscured and unobscured quasars at ăză = 1.4 using angular clustering measurements as well as cross-correlation measurements of quasar positions with the gravitational lensing of the cosmic microwave background. We interpret these signals within a halo occupation distribution framework to conclude that obscured systems reside in more massive effective halos (âŒ1012.9 hâ1 Mâ) than their unobscured counterparts (âŒ1012.6 hâ1 Mâ), though we do not detect a difference in the satellite fraction. We find excellent agreement between the clustering and lensing analyses and show that this implies the observed difference is robust to uncertainties in the obscured quasar redshift distribution, highlighting the power of combining angular clustering and weak lensing measurements. This finding appears in tension with models that ascribe obscuration exclusively to orientation of the dusty torus along the line of sight, and instead may be consistent with the notion that some obscured quasars are attenuated by galaxy-scale or circumnuclear material during an evolutionary phase
Effect of a multistage ultraendurance triathlon on aldosterone, vasopressin, extracellular water and urine electrolytes
Prolonged endurance exercise over several days induces increase in extracellular water (ECW). We aimed to investigate an association between the increase in ECW and the change in aldosterone and vasopressin in a multistage ultraendurance triathlon, the 'World Challenge Deca Iron Triathlon' with 10 Ironman triathlons within 10 days. Before and after each Ironman, body mass, ECW, urinary [Na(+)], urinary [K(+)], urinary specific gravity, urinary osmolality and aldosterone and vasopressin in plasma were measured. The 11 finishers completed the total distance of 38 km swimming, 1800 km cycling and 422 km running within 145.5 (18.8) hours and 25 (22) minutes. ECW increased by 0.9 (1.1) L from 14.6 (1.5) L prerace to 15.5 (1.9) L postrace (P < 0.0001). Aldosterone increased from 70.8 (104.5) pg/mL to 102.6 (104.6) pg/mL (P = 0.033); vasopressin remained unchanged. The increase in ECW was related neither to postrace aldosterone nor to postrace vasopressin. In conclusion, ECW and aldosterone increased after this multistage ultraendurance triathlon, but vasopressin did not. The increase in ECW and the increase in aldosterone were not associated
Obscuration beyond the nucleus: infrared quasars can be buried in extreme compact starbursts
In the standard quasar model, the accretion disk obscuration is due to the canonical dusty torus. Here, we argue that a substantial part of the quasar obscuration can come from the interstellar medium (ISM) when the quasars are embedded in compact starbursts. We use an obscuration-unbiased sample of 578 infrared (IR) quasars at z â 1 â 3 and archival ALMA submillimeter host galaxy sizes to investigate the ISM contribution to the quasar obscuration. We calculate SFR and ISM column densities for the IR quasars and a control sample of submillimeter galaxies (SMGs) not hosting quasar activity and show that: (1) the quasar obscured fraction is constant up to SFRâ300Mâyrâ1â , and then increases towards higher SFR, suggesting that the ISM obscuration plays a significant role in starburst host galaxies, and (2) at SFRâł300Mâyrâ1, the SMGs and IR quasars have similarly compact submillimeter sizes (â Reâ0.5â3kpcâ ) and, consequently, the ISM can heavily obscure the quasar, even reaching Compton-thick (â NH>1024cmâ2) levels in extreme cases. Based on our results, we infer that â10â30% of the IR quasars with SFRâł300Mâyrâ1Â are obscured solely by the ISM