Structural and vibrational properties of two-dimensional MnxOy\rm Mn_xO_y nanolayers on Pd(100)

Using different experimental techniques combined with density functional based theoretical methods we have explored the formation of interface-stabilized manganese oxide structures grown on Pd(100) at (sub)monolayer coverage. Amongst the multitude of phases experimentally observed we focus our attention on four structures which can be classified into two distinct regimes, characterized by different building blocks. Two oxygen-rich phases are described in terms of MnO(111)-like O-Mn-O trilayers, whereas the other two have a lower oxygen content and are based on a MnO(100)-like monolayer structure. The excellent agreement between calculated and experimental scanning tunneling microscopy images and vibrational electron energy loss spectra allows for a detailed atomic description of the explored models.Comment: 14 pages, 11 figure

X-ray Properties of the Weak Seyfert 1 Nucleus in NGC 4639

We obtained observations of NGC 4639 with ASCA in order to investigate its mildly active Seyfert 1 nucleus at hard X-ray energies. Koratkar et al. (1995) have previously shown that the nucleus is a pointlike source in the ROSAT soft X-ray band. We detected in the 2-10 keV band a compact central source with a luminosity of 8.3E+40 erg/s. Comparison of the ASCA data with archival data taken with the Einstein and ROSAT satellites shows that the nucleus varies on timescales of months to years. The variability could be intrinsic, or it could be caused by variable absorption. More rapid variability, on a timescale of \~10^4 s, may be present in the ASCA data. The spectrum from 0.5 to 10 keV is well described by a model consisting of a lightly absorbed (N_H = 7.3E+20 cm^-2) power law with a photon index of 1.68. We find no evidence for significant emission from a thermal plasma; if present, it can account for no more than 25% of the flux in the 0.5-2.0 keV band. The limited photon statistics of our data do not allow us to place significant limits on the presence of iron K emission. (abridged)Comment: To appear in The Astrophysical Journal. LaTex, 18 pages including embedded figures and table

The X-ray Emission from the Nucleus of the Dwarf Elliptical Galaxy NGC 3226

We present the first high resolution X-ray image of the dwarf elliptical galaxy NGC 3226. The data were obtained during an observation of the nearby Seyfert Galaxy NGC 3227 using the Chandra X-ray Observatory. We detect a point X-ray source spatially consistent with the optical nucleus of NGC 3226 and a recently-detected, compact, flat-spectrum, radio source. The X-ray spectrum can be measured up to ~10 keV and is consistent with a power law with a photon index 1.7 <~ Gamma <~ 2.2, or thermal bremmstrahlung emission with 4 <~ kT <~ 10 keV. In both cases the luminosity in the 2--10 keV band ~10^{40} h_{75}^{-1} erg/s. We find marginal evidence that the nucleus varies within the observation. These characteristics support evidence from other wavebands that NGC 3226 harbors a low-luminosity, active nucleus. We also comment on two previously-unknown, fainter X-ray sources <~ 15 arcsec from the nucleus of NGC 3226. Their proximity to the nucleus (with projected distances <~ 1.3/h_{75} kpc) suggests both are within NGC 3226, and thus have luminosities (~few x 10^{38} -- few x 10^{39} erg/s) consistent with black-hole binary systems.Comment: Accepted for publication in ApJ. Figures in colo

Accretion Properties of A Sample of Hard X-ray (<60keV) Selected Seyfert 1 Galaxies

We examine the accretion properties in a sample of 42 hard (3-60keV) X-ray selected nearby broad-line AGNs. The energy range in the sample is harder than that usually used in the similar previous studies. These AGNs are mainly complied from the RXTE All Sky Survey (XSS), and complemented by the released INTEGRAL AGN catalog. The black hole masses, bolometric luminosities of AGN, and Eddington ratios are derived from their optical spectra in terms of the broad H$\beta$ emission line. The tight correlation between the hard X-ray (3-20keV) and bolometric/line luminosity is well identified in our sample. Also identified is a strong inverse Baldwin relationship of the H$\beta$ emission line. In addition, all these hard X-ray AGNs are biased toward luminous objects with high Eddington ratio (mostly between 0.01 to 0.1) and low column density ($<10^{22} \mathrm{cm^{-2}}$), which is most likely due to the selection effect of the surveys. The hard X-ray luminosity is consequently found to be strongly correlated with the black hole mass. We believe the sample completeness will be improved in the next few years by the ongoing Swift and INTEGRAL missions, and by the next advanced missions, such as NuSTAR, Simbol-X, and NeXT. Finally, the correlation between RFe (=optical FeII/H$\beta$) and disk temperature as assessed by $T\propto (L/L_{\mathrm{Edd}})M_{\mathrm{BH}}^{-1}$ leads us to suggest that the strength of the FeII emission is mainly determined by the shape of the ionizing spectrum.Comment: 28 pages, 7 figures, 2 tables, accepted by A

Implications from the optical to UV flux ratio of FeII emission in quasars

We investigate FeII emission in Broad Line Region (BLR) of AGNs by analyzing the FeII(UV), FeII(4570) and MgII emission lines in 884 quasars in the Sloan Digital Sky Survey (SDSS) Quasar catalog in a redshift range of 0.727 < z < 0.804. FeII(4570)/FeII(UV) is used to infer the column density of FeII-emitting clouds and explore the excitation mechanism of FeII emission lines. As suggested before in various works, the classical photoionization models fail to account for FeII(4570)/FeII(UV) by a factor of 10, which may suggest anisotropy of UV FeII emission; otherwise, an alternative heating mechanism like shock is working. The column density distribution derived from FeII(4570)/FeII(UV) indicates that radiation pressure plays an important role in BLR gas dynamics. We find a positive correlation between FeII(4570)/FeII(UV) and the Eddington ratio. We also find that almost all FeII-emitting clouds are to be under super-Eddington conditions unless ionizing photon fraction is much smaller than that previously suggested. Finally we propose a physical interpretation of a striking set of correlations between various emission-line properties, known as ``Eigenvector 1''.Comment: 10 pages, 10 figures, accepted for publication in MNRA

An early resource characterization of deep learning on wearables, smartphones and internet-of-things devices

Detecting and reacting to user behavior and ambient context are core elements of many emerging mobile sensing and Internet-of-Things (IoT) applications. However, extracting accurate infer-ences from raw sensor data is challenging within the noisy and complex environments where these systems are deployed. Deep Learning { is one of the most promising approaches for overcom-ing this challenge, and achieving more robust and reliable infer-ence. Techniques developed within this rapidly evolving area of machine learning are now state-of-the-art for many inference tasks (such as, audio sensing and computer vision) commonly needed by IoT and wearable applications. But currently deep learning al-gorithms are seldom used in mobile/IoT class hardware because they often impose debilitating levels of system overhead (e.g., memory, computation and energy). Efforts to address this bar-rier to deep learning adoption are slowed by our lack of a system-atic understanding of how these algorithms behave at inference time on resource constrained hardware. In this paper, we present the-rst { albeit preliminary { measurement study of common deep learning models (such as Convolutional Neural Networks and Deep Neural Networks) on representative mobile and embed-ded platforms. The aim of this investigation is to begin to build knowledge of the performance characteristics, resource require-ments and the execution bottlenecks for deep learning models when being used to recognize categories of behavior and context. The results and insights of this study, lay an empirical foundation for the development of optimization methods and execution envi-ronments that enable deep learning to be more readily integrated into next-generation IoT, smartphones and wearable systems

On the relation of optical obscuration and X-ray absorption in Seyfert galaxies

The optical classification of a Seyfert galaxy and whether it is considered X-ray absorbed are often used interchangeably. But there are many borderline cases and also numerous examples where the optical and X-ray classifications appear to be in conflict. In this article we re-visit the relation between optical obscuration and X-ray absorption in AGNs. We make use of our "dust color" method (Burtscher et al. 2015) to derive the optical obscuration A_V and consistently estimated X-ray absorbing columns using 0.3--150 keV spectral energy distributions. We also take into account the variable nature of the neutral gas column N_H and derive the Seyfert sub-classes of all our objects in a consistent way. We show in a sample of 25 local, hard-X-ray detected Seyfert galaxies (log L_X / (erg/s) ~ 41.5 - 43.5) that there can actually be a good agreement between optical and X-ray classification. If Seyfert types 1.8 and 1.9 are considered unobscured, the threshold between X-ray unabsorbed and absorbed should be chosen at a column N_H = 10^22.3 / cm^2 to be consistent with the optical classification. We find that N_H is related to A_V and that the N_H/A_V ratio is approximately Galactic or higher in all sources, as indicated previously. But in several objects we also see that deviations from the Galactic ratio are only due to a variable X-ray column, showing that (1) deviations from the Galactic N_H/A_V can simply be explained by dust-free neutral gas within the broad line region in some sources, that (2) the dust properties in AGNs can be similar to Galactic dust and that (3) the dust color method is a robust way to estimate the optical extinction towards the sublimation radius in all but the most obscured AGNs.Comment: 7 pages, 3 figures, accepted for publication by A&A; updated PDF to include abstrac

Risk Factors for the Development of Cataract in Children with Uveitis

PURPOSE: To determine the risk factors for the development of cataract in children with uveitis of any etiology. DESIGN: Cohort study. METHODS: Two hundred forty-seven eyes of 140 children with uveitis were evaluated for the development of vision-affecting cataract. Demographic, clinical, and treatment data were collected between the time of presentation and the first instance cataract was recorded or findings at final follow-up. Main outcome measures included the prevalence of cataract and distribution by type of uveitis, incidence of new onset cataract time to cataract development, and risk factors for the development of cataract. RESULTS: The prevalence of cataract in our cohort was 44.2% and was highest among eyes with panuveitis (77.1%), chronic anterior uveitis (48.3%), and intermediate uveitis (48.0%). The overall incidence of newly diagnosed cataract was 0.09 per eye-year, with an estimated 69% to develop uveitis-related cataract with time. The main factors related with cataract development were the number of uveitis flares per year (hazard ratio [HR] = 3.06 [95% confidence interval {CI}, 2.15–4.35], P < .001), cystoid macular edema (HR = 2.87 [95% CI, 1.41–5.82], P = .004), posterior synechia at presentation (HR = 2.85 [95% CI, 1.53–5.30], P = .001), and use of local injections of corticosteroids (HR = 2.37 [95% CI, 1.18–4.75], P = .02). Treatments with systemic and topical corticosteroids were not significant risk factors. CONCLUSIONS: In this study, we found that development of cataract is common among pediatric eyes with uveitis and is most strongly related to the extent of inflammation recurrences and ocular complications. We suggest that controlling the inflammation, even using higher doses of systemic and topical corticosteroids, is of importance in preventing ocular complications, such as cataract. Uveitis accounts for 10–15% of blindness in the developed world.1 Although pediatric uveitis is relatively uncommon, accounting for only 5–10% of all uveitis cases,2 it affects young patients, who in most cases are otherwise healthy. Vision loss results from ongoing inflammation that leads to ocular structural changes, such as cataract, corneal opacities, optic neuropathy, and retinal lesions. The most common causes of vision loss in children with uveitis are cataract, glaucoma, and chronic cystoid macular edema (CME).2, 3 In addition, any chronic visual obstruction can result in the development of amblyopia in younger children, with vision loss persisting after the inciting cause is treated.4 Such changes, together with the need for long-term treatment and continuous monitoring, can have a profound impact on their development, independence, and education. The prevalence of cataract in eyes with uveitis ranges from 20–64%,4, 5, 6, 7 and it is the most common complication of uveitis in children,8 occurring in approximately 35% of children with juvenile idiopathic arthritis (JIA)-associated uveitis9 and increasing ≤80% in adults.10, 11 Cataract progression can be the result of persistent intraocular inflammation,12, 13 can be caused by surgery for uveitis complications (eg, trabeculectomies and repair of retinal detachments), or can be a consequence of uveitis treatment, particularly the use of local or systemic corticosteroids.14, 15, 16, 17 It results in reduced visual acuity and can have a detrimental effect on the development and academic achievements of these children.18 Studies have examined risk factors for the development of cataract among children with JIA-associated uveitis, identifying risk factors such as the presence of posterior synechiae (PS) at presentation,12, 19 the use of systemic corticosteroids,13 topical corticosteroid therapy exceeding 3 drops a day,12 or persistent, uncontrolled active inflammation,3 while early treatment with methotrexate delayed cataract progression.19 However, JIA is a unique cause of uveitis, often localized to the anterior chamber, with frequent intraocular structural changes and the early use of systemic immunosuppressive agents. It may not represent the same risks as other causes of pediatric uveitis. We examined disease- and treatment-related risk factors for cataract development in children with uveitis of any etiology. We investigated clinical and ophthalmologic characteristics, as well as treatment strategies in relation to the time interval between the first presentation with uveitis and cataract development

Molecular Gas in Infrared Ultraluminous QSO Hosts

We report CO detections in 17 out of 19 infrared ultraluminous QSO (IR QSO) hosts observed with the IRAM 30m telescope. The cold molecular gas reservoir in these objects is in a range of 0.2--2.1$\times 10^{10}M_\odot$ (adopting a CO-to-${\rm H_2}$ conversion factor $\alpha_{\rm CO}=0.8 M_\odot {\rm (K km s^{-1} pc^2)^{-1}}$). We find that the molecular gas properties of IR QSOs, such as the molecular gas mass, star formation efficiency ($L_{\rm FIR}/L^\prime_{\rm CO}$) and the CO (1-0) line widths, are indistinguishable from those of local ultraluminous infrared galaxies (ULIRGs). A comparison of low- and high-redshift CO detected QSOs reveals a tight correlation between L$_{\rm FIR}$ and $L^\prime_{\rm CO(1-0)}$ for all QSOs. This suggests that, similar to ULIRGs, the far-infrared emissions of all QSOs are mainly from dust heated by star formation rather than by active galactic nuclei (AGNs), confirming similar findings from mid-infrared spectroscopic observations by {\it Spitzer}. A correlation between the AGN-associated bolometric luminosities and the CO line luminosities suggests that star formation and AGNs draw from the same reservoir of gas and there is a link between star formation on $\sim$ kpc scale and the central black hole accretion process on much smaller scales.Comment: 30 pages, 9 figures, accepted for publication in The Astrophysical Journa

A study on text-score disagreement in online reviews

In this paper, we focus on online reviews and employ artificial intelligence tools, taken from the cognitive computing field, to help understanding the relationships between the textual part of the review and the assigned numerical score. We move from the intuitions that 1) a set of textual reviews expressing different sentiments may feature the same score (and vice-versa); and 2) detecting and analyzing the mismatches between the review content and the actual score may benefit both service providers and consumers, by highlighting specific factors of satisfaction (and dissatisfaction) in texts. To prove the intuitions, we adopt sentiment analysis techniques and we concentrate on hotel reviews, to find polarity mismatches therein. In particular, we first train a text classifier with a set of annotated hotel reviews, taken from the Booking website. Then, we analyze a large dataset, with around 160k hotel reviews collected from Tripadvisor, with the aim of detecting a polarity mismatch, indicating if the textual content of the review is in line, or not, with the associated score. Using well established artificial intelligence techniques and analyzing in depth the reviews featuring a mismatch between the text polarity and the score, we find that -on a scale of five stars- those reviews ranked with middle scores include a mixture of positive and negative aspects. The approach proposed here, beside acting as a polarity detector, provides an effective selection of reviews -on an initial very large dataset- that may allow both consumers and providers to focus directly on the review subset featuring a text/score disagreement, which conveniently convey to the user a summary of positive and negative features of the review target.Comment: This is the accepted version of the paper. The final version will be published in the Journal of Cognitive Computation, available at Springer via http://dx.doi.org/10.1007/s12559-017-9496-