1,011 research outputs found
Association between diverticulosis and colonic neoplastic lesions in individuals with a positive faecal immunochemical test
Background The association between diverticulosis and colonic neoplastic lesions has been suggested, but data in literature are conflicting. This study aimed to investigate such a relationship in patients participating in a colorectal cancer screening program who underwent high-quality colonoscopy.Methods Data from consecutive individuals 50-75 years of age with a positive faecal immunological test were considered. Diverticulosis was categorised as present or absent. The prevalence of neoplastic lesions (adenoma, advanced adenoma, and cancer) between individuals with and those without diverticula was compared. A multivariate analysis was performed.Results Overall, data from 970 consecutive individuals were evaluated, and diverticulosis was detected in 354 (36.5%) cases. At least one adenoma was detected in 490 (50.5%) people, at least one advanced adenoma in 264 (27.2%), multiple adenoma in 71 (7.3%), whilst a cancer was diagnosed in 48 (4.9%) cases. At univariate analysis, the adenoma detection rate in patients with diverticula was significantly higher than in controls (55.9% vs 47.4%; p=0.011). At multivariate analysis, presence of diverticulosis was an independent risk factor for both adenoma detection rate (OR=1.58; 95% CI=1.14-2.18; p=0.006) and advanced adenoma (OR=1.57; 95% CI=1.10-2.24; p=0.013), but not for colorectal cancer.Conclusions In a colorectal screening setting, the adenoma detection rate was significantly higher in individuals with diverticulosis than in controls
Spitzer-MIPS survey of the young stellar content in the Vela Molecular Cloud-D
A new, unbiased Spitzer-MIPS imaging survey (~1.8 square degs) of the young
stellar content of the Vela Molecular Cloud-D is presented. The survey is
complete down to 5mJy and 250mJy at 24micron (mu) and 70mu, respectively. 849
sources are detected at 24mu and 52 of them also have a 70mu counterpart. The
VMR-D region is one that we have already partially mapped in dust and gas
millimeter emission, and we discuss the correlation between the Spitzer compact
sources and the mm contours. About half of the 24mu sources are located inside
the region delimited by the 12CO(1-0) contours (corresponding to only one third
of the full area mapped with MIPS) with a consequent density increase of about
100% of the 24mu sources [four times for 70mu ones] moving from outside to
inside the CO contours. About 400 sources have a 2MASS counterpart. So we have
constructed a Ks vs. Ks-[24] diagram and identified the protostellar
population. We find an excess of Class I sources in VMR-D in comparison with
other star forming regions. This result is reasonably biased by the sensitivity
limits, or, alternatively, may reflect a very short lifetime (<=10^6yr) of the
protostellar content in this cloud. The MIPS images have identified embedded
cool objects in most of the previously identified starless cores; in addition,
there are 6 very young, possibly Class 0 objects identified. Finally we report
finding of the driving sources for a set of five out of six very compact
protostellar jets previously discovered in near-infrared images.Comment: 29 pages, 14 figures. To appear in Ap.
Intelligent methods for information access in context: The role of topic descriptors and discriminators
Successful access to information sources on the Web depends on effective methods for identifying the needs of a user and making relevant information resources available when needed. This paper formulates a theoretical framework for the study of context-drivenWeb search and proposes new methods for learning query terms based on the user task. These methods use an incrementally-retrieved, topic-dependent selection of Web documents for term-weight reinforcement reflecting the aptness of the terms in describing and discriminating the topic of the user context. Based on this framework, we propose an incremental search algorithm for information retrieval agents that has the potential to improve significantly over the traditional IR techniques. The new algorithm learns new descriptors by searching for terms that tend to occur often in relevant documents, and learns good discriminators by identifying terms that tend to occur only in the context of the given topic.
We discuss the technical challenges posed by this new framework, outline our agent system architecture, and present an evaluation of the proposed techniques.Red de Universidades con Carreras en Informática (RedUNCI
Teachers\u27 Implicit Racial Attitudes and Classroom Discipline Referral
Teachers often hold lower academic and behavioral expectations for Black students, and they are more likely to make a disciplinary referral for Black students than their white peers for similar infractions. The mechanism underlying this may be teachers’ implicit attitudes about their Black students based on causal attributions. This study examined the connection between teacher implicit racial attitudes and how teachers label potentially disruptive classroom behaviors, addressing two research questions: How are teacher education students’ (TES) implicit racial attitude scores on an implicit bias test related to perceptions about student behavioral challenges in the classroom, and how does this relation affect their decisions to refer students for disciplinary action? The study looked at teacher education students (N=233) who completed three sets of tests: the racial bias section of the Implicit Assessment Test; a set of questions assessing causal attribution based on four vignettes depicting student misbehaviors in a classroom setting; and a demographic questionnaire. This study predicted that TES who scored higher on the racial bias IAT would be more likely to recommend Black students for disciplinary referral. While the hypotheses couldn’t be confirmed, there was evidence that regardless of implicit bias, TES were more likely to believe that Black students had an internal locus of causality and controllability than their white counterparts when presented with similar instances of disordered behavior. Ultimately, this study adds to the literature on TES racial attitudes and the effect of these on their classroom interactions with their students
Evidence for T Tauri-like emission in the EXor V1118 Ori from near-IR and X-ray data
We present a near-IR study of the EXor variable V1118 Ori, performed by
following a slightly declining phase after a recent outburst. In particular,
the near-IR (0.8 - 2.3 micron) spectrum, obtained for the first time, shows a
large variety of emission features of the HI and HeI recombination and CO
overtone. By comparing the observed spectrum with a wind model, a mass loss
rate value is derived along with other parameters whose values are typical of
an accreting T Tauri star. In addition, we have used X-ray data from the XMM
archive, taken in two different epochs during the declining phase monitored in
IR. X-ray emission (in the range 0.5 - 10 keV) permits to derive several
parameters which confirm the T Tauri nature of the source. In the near-IR the
object maintains a low visual extinction during all the activity phases,
confirming that variable extinction does not contribute to brightness
variations. The lack of both a significant amount of circumstellar material and
any evidence of IR cooling from collimated jet/outflow driven by the source,
indicates that, at least this member of the EXor class, is in a late stage of
the Pre-Main Sequence evolution. In the X-ray regime, an evident fading is
present, detected in the post-outburst phase, that cannot be reconciled with
the presence of any absorbing material. This circumstance, combined with the
persistence (in the pre- and post-outburst phases) of a temperature component
at about 10 MK, suggests that accretion has some influence in regulating the
coronal activity
An Entropy-Based Approach for Preserving Diversity in Evolutionary Topical Search
Topic-based information retrieval is the process of matching a topic of interest against the resources that are indexed. An approach for retrieving topicrelevant resources is to generate queries that are able to reflect the topic of interest.
Multi-objective Evolutionary Algorithms have demonstrated great potential to deal with the problem of topical query generation. In an evolutionary approach to topic-based information retrieval the topic of interest is used to generate an initial population of queries, which is evolved towards successively better candidate queries. A common problem with such an approach is poor recall due to loss of genetic diversity. This work proposes a novel strategy inspired on the information theoretic notion of entropy to favor population diversity with the aim of attaining good global recall. Preliminary experiments conducted on a large dataset of labeled documents show the effectiveness of the proposed strategy.Sociedad Argentina de Informática e Investigación Operativa (SADIO
An Entropy-Based Approach for Preserving Diversity in Evolutionary Topical Search
Topic-based information retrieval is the process of matching a topic of interest against the resources that are indexed. An approach for retrieving topicrelevant resources is to generate queries that are able to reflect the topic of interest.
Multi-objective Evolutionary Algorithms have demonstrated great potential to deal with the problem of topical query generation. In an evolutionary approach to topic-based information retrieval the topic of interest is used to generate an initial population of queries, which is evolved towards successively better candidate queries. A common problem with such an approach is poor recall due to loss of genetic diversity. This work proposes a novel strategy inspired on the information theoretic notion of entropy to favor population diversity with the aim of attaining good global recall. Preliminary experiments conducted on a large dataset of labeled documents show the effectiveness of the proposed strategy.Sociedad Argentina de Informática e Investigación Operativa (SADIO
Genetic algorithms for topical web search: A study of different mutation rates
Harvesting topical content is a process that can be done by formulating topic-relevant queries and submitting them to a search engine. The quality of the material collected through this process is highly dependant on the vocabulary used to generate the search queries. In this scenario, selecting good query terms can be seen as an optimization problem where the objective function to be optimized is based on the effectiveness of a query to retrieve relevant material. Three characteristics of this optimization problem are (1) the high-dimensionality of the search space, where candidate solutions are queries and each term corresponds to a different dimension, (2) the existence of acceptable suboptimal solutions, and (3) the possibility of finding multiple solutions. This paper describes optimization techniques based on Genetic Algorithms to evolve “good query terms” in the context of a given topic. We discuss the use of a mutation pool to allow the generation of queries with novel terms, and study the effect of different mutation rates on the exploration of query-space.Red de Universidades con Carreras en Informática (RedUNCI
The Spitzer-IRAC Point Source Catalog of the Vela-D Cloud
This paper presents the observations of the Cloud D in the Vela Molecular
Ridge, obtained with the IRAC camera onboard the Spitzer Space Telescope at the
wavelengths \lambda = 3.6, 4.5, 5.8, 8.0 {\mu}m. A photometric catalog of point
sources, covering a field of approximately 1.2 square degrees, has been
extracted and complemented with additional available observational data in the
millimeter region. Previous observations of the same region, obtained with the
Spitzer MIPS camera in the photometric bands at 24 {\mu}m and 70 {\mu}m, have
also been reconsidered to allow an estimate of the spectral slope of the
sources in a wider spectral range. A total of 170,299 point sources, detected
at the 5-sigma sensitivity level in at least one of the IRAC bands, have been
reported in the catalog. There were 8796 sources for which good quality
photometry was obtained in all four IRAC bands. For this sample, a preliminary
characterization of the young stellar population based on the determination of
spectral slope is discussed; combining this with diagnostics in the
color-magnitude and color-color diagrams, the relative population of young
stellar objects in the different evolutionary classes has been estimated and a
total of 637 candidate YSOs have been selected. The main differences in their
relative abundances have been highlighted and a brief account for their spatial
distribution is given. The star formation rate has been also estimated and
compared with the values derived for other star forming regions. Finally, an
analysis of the spatial distribution of the sources by means of the two-point
correlation function shows that the younger population, constituted by the
Class I and flat-spectrum sources, is significantly more clustered than the
Class II and III sources.Comment: Accepted by Ap
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