Miracle-dz/UniFAR-FTUs huggingface dataset:
Ring (mathematics) Ring (mathematics)

Polynomials, represented here by curves, form a ring under addition and multiplication. In mathematics, a ring is an algebraic structure consisting of a set together with two binary operations usually called addition and multiplication, where the set is an abelian group under addition (called the additive group of the ring) and a monoid under multiplication such that multiplication distributes over addition. a[›] In other words the ring axioms require that addition is commutative, addition and multiplication are associative, multiplication distributes over addition, each element in the set has an additive inverse, and there exists an additive identity. One of the most common examples of a ring is the set of integers endowed with its natural operations of addition and multiplication. Certain variations of the definition of a ring are sometimes employed, and these are outlined later in the article. The branch of mathematics that studies rings is known as ring theory. Ring theorists study properties common to both familiar mathematical structures such as integers and polynomials, and to the many less well-known mathematical structures that also satisfy the axioms of ring theory. The ubiquity of rings makes them a central organizing principle of contemporary mathematics. [1] Ring theory may be used to understand fundamental physical laws, such as those underlying special relativity and symmetry phenomena in molecular chemistry. The concept of a ring first arose from attempts to prove Fermat's last theorem, starting with Richard Dedekind in the 1880s. After contributions from other fields, mainly number theory, the ring notion was generalized and firmly established during the 1920s by Emmy Noether and Wolfgang Krull. [2] Modern ring theory—a very active mathematical discipline—studies rings in their own right. To explore rings, mathematicians have devised various notions to break rings into smaller, better-understandable pieces, such as ideals, quotient rings and simple rings. In addition to these abstract properties, ring theorists also make various distinctions between the theory of commutative rings and noncommutative rings—the former belonging to algebraic number theory and algebraic geometry. A particularly rich theory has been developed for a certain special class of commutative rings, known as fields, which lies within the realm of field theory. Likewise, the corresponding theory for noncommutative rings, that of noncommutative division rings, constitutes an active research interest for noncommutative ring theorists. Since the discovery of a mysterious connection between noncommutative ring theory and geometry during the 1980s by Alain Connes, noncommutative geometry has become …
OPTICAL FLOW FOR GLACIER MOTION ESTIMATION

Abstract. Quantitative measurements of glacier flow over time are an important ingredient for glaciological research, for example to determine the mass balances and the evolution of glaciers. Measuring glacier flow in multi-temporal images involves the estimation of a dense set of corresponding points, which in turn define the flow vectors. Furthermore glaciers exhibit rather difficult radiometry, since their surface usually contains homogeneous areas as well as weak texture and contrast. To date glacier flow is usually observed by manually measuring a sparse set of correspondences, which is labor-intensive and often yields rather irregular point distributions, with the associated problems of interpolating over large areas. In the present work we propose to densely compute motion vectors at every pixel, by using recent robust methods for optic flow computation. Determining the optic flow, i.e. the dense deformation field between two images of a dynamic scene, has been a classic, long-standing research problem in computer vision and image processing. Sophisticated methods exist to optimally balance data fidelity with smoothness of the motion field. Depending on the strength of the local image gradients these methods yield a smooth trade-off between matching and interpolation, thereby avoiding the somewhat arbitrary decision which discrete anchor points to measure, while at the same time mitigating the problem of gross matching errors. We evaluate our method by comparing with manually measured point wise ground truth.
Upper Modeling: A general organization of knowledge for natural language processing

A general, reusable computational resource has been developed within the Penman text generation project for organizing domain knowledge appropriately for linguistic realization. This resource, called the upper model , provides a domain-and task-independent classi(cid:12)cation system that supports sophisticated natural language processing while signi(cid:12)cantly simplifying the interface between domain-speci(cid:12)c knowledge and general linguistic resources. Although levels of abstract semantic organization similar to the upper model are now being sought in many natural language systems, often with a view to exploring appropriate formalization techniques, these mostly su(cid:11)er from either a lack of theoretical constraint concerning their internal contents and organization and the necessary mappings between them and surface realization, or a lack of abstraction which binds them too closely with linguistic form. This paper presents the results of our experiences in designing and using the upper model in a variety of applications over the past 5 years. In particular, we present our conclusions concerning the appropriate organization of an upper model, its domain-independence, and the types of interrelationships that need to be supported between upper model and grammar and semantics. We consider the organization and interrelation-ships that we have found necessary both useful for organizing domain knowledge consistently and vital for sophisticated generation capabilities.
Towards video processing in vehicles under adverse weather conditions

In this contribution we propose methods for vehicle detection and tracking for the Advanced Driver Assistance Systems (ADAS) that work under extremely adverse weather conditions. Most of the state-of-the-art vehicle detection and tracking methods are based either on appearance based vehicle recognition or on extraction and tracking of dedicated image key points. Visibility deterioration due to rain drops and water streaks on the windshield, swirling spray, and fog lead to a drastic performance reduction or even to a complete failure of these approaches. In this contribution we propose several methods for coping with these phenomena. In addition to an extension of the feature-based tracking method, which copes with outliers and temporarily disappearing key points, we present a detection and tracking method based on search for vehicle rear lights and whole rear views in the saturation channel. Utilization of symmetry operators and search space restriction allows to detect and track vehicles even in pouring rain conditions. Furthermore, we present two applications of the above-described methods. Estimation of the strength of spray produced by preceding vehicles allows to draw conclusions about the overall visibility conditions and to adjust the intensity of one's own rear lights. Besides, a restoration of deteriorated image regions becomes possible.
Do FLAIR Vascular Hyperintensities beyond the DWI Lesion Represent the Ischemic Penumbra?

FLAIR images from over 140 patients with acute MCA infarctions were analyzed and compared with images used to estimate the ischemic penumbra. A FLAIR-DWI mismatch was seen in 72% of patients and the authors concluded that this may be used to identify the ischemic penumbra. BACKGROUND AND PURPOSE: In acute stroke with proximal artery occlusion, FLAIR vascular hyperintensities observed beyond the boundaries of the cortical lesion on DWI (newly defined “FLAIR vascular hyperintensity–DWI mismatch”) may be a marker of tissue at risk of infarction. Our aim was to compare the occurrence of FLAIR vascular hyperintensity–DWI mismatch relative to that of perfusion-weighted imaging–DWI mismatch in patients with proximal MCA occlusion before IV thrombolysis. MATERIALS AND METHODS: In 141 consecutive patients with proximal MCA occlusion, 2 independent observers analyzed FLAIR images for the presence of FLAIR vascular hyperintensity–DWI mismatch before IV thrombolysis. PWI-DWI mismatch was defined as Volumehypoperfusion > 1.8 × VolumeDWI, with Volumehypoperfusion > 6 seconds on time to maximum value of the residue function maps in the 94 patients with available PWI. The presence of FLAIR vascular hyperintensity–DWI mismatch, PWI-DWI mismatch, and infarct growth on 24-hour follow-up DWI was compared. RESULTS: A FLAIR vascular hyperintensity–DWI mismatch was present in 102/141 (72%) patients, with an excellent interobserver reliability (κ = 0.91), and a PWI-DWI mismatch, in 61 of the 94 (65%) patients with available PWI. FLAIR vascular hyperintensity–DWI mismatch predicted PWI-DWI mismatch with a sensitivity of 92% (95% CI, 85%–99%) and a specificity of 64% (95% CI, 47%–80%). Patients with FLAIR vascular hyperintensity–DWI mismatch had smaller initial DWI lesion and larger infarct growth (P < .001) than patients without FLAIR vascular hyperintensity–DWI mismatch, even though their final infarcts remained smaller (P < .001). CONCLUSIONS: Albeit being moderately specific, probably due to inclusion of oligemic tissue, the FLAIR vascular hyperintensity–DWI mismatch identifies large PWI-DWI mismatch with high sensitivity.
Nucleation characteristics of stream water and frazil ice nucleation

A drop-freezing experiment was used to study the nucleation characteristics of some natural water samples taken from a supercooled stream in interior Alaska. A histogram of drop-freezing events, the differential nucleus spectrum, and the cumulative nucleus spectrum describe the experimental results. The drops froze over a temperature range from −4.3°C to −13.9°C with an average nucleation temperature of −8.2°C ±1.5°C. The results of these experiments are compared to observations made during periods of frazil ice production in the stream. It is concluded that the supercooling necessary for spontaneous heterogeneous nucleation of ice in a thin surface layer of stream water would be ∼ −4°C. Since the surface temperature of the supercooled stream was found to be 0°C ± 0.5°C, frazil ice crystals cannot be nucleated spontaneously in the surface layer of water.
Luminescence dating of the Wabar meteorite craters, Saudi Arabia

[1] Luminescence dating has been used to find the age of meteorite impact craters at Wabar (Al Hadida) in Saudi Arabia. The luminescence characteristics of the shocked material were determined. Using a variety of luminescence dating techniques applied to impactite formed by the meteorite, and to the underlying sand, the age is found to be 290 ± 38 years. A comparison is made with two possible historically recorded ages. An impact as young as this has implications for the assessment of hazards from the impact on Earth of small meteorites.
Pyrosequencing of Antibiotic-Contaminated River Sediments Reveals High Levels of Resistance and Gene Transfer Elements

The high and sometimes inappropriate use of antibiotics has accelerated the development of antibiotic resistance, creating a major challenge for the sustainable treatment of infections world-wide. Bacterial communities often respond to antibiotic selection pressure by acquiring resistance genes, i.e. mobile genetic elements that can be shared horizontally between species. Environmental microbial communities maintain diverse collections of resistance genes, which can be mobilized into pathogenic bacteria. Recently, exceptional environmental releases of antibiotics have been documented, but the effects on the promotion of resistance genes and the potential for horizontal gene transfer have yet received limited attention. In this study, we have used culture-independent shotgun metagenomics to investigate microbial communities in river sediments exposed to waste water from the production of antibiotics in India. Our analysis identified very high levels of several classes of resistance genes as well as elements for horizontal gene transfer, including integrons, transposons and plasmids. In addition, two abundant previously uncharacterized resistance plasmids were identified. The results suggest that antibiotic contamination plays a role in the promotion of resistance genes and their mobilization from environmental microbes to other species and eventually to human pathogens. The entire life-cycle of antibiotic substances, both before, under and after usage, should therefore be considered to fully evaluate their role in the promotion of resistance.
Information Acquisition and Recall in Location-Aware and Search Engine Retrieval Systems

This paper examines the potential cognitive impact of location aware information systems compared to that of search engines using a dual coding and conjoint retention theoretical framework. Supported by virtual reality or mobile devices, location aware systems deliver information that is relevant for a specific location. Research questions and hypotheses formulated under the assumption that location aware systems are better prepared to contextualize and make information memorable are explored using a planned comparison repeated measures 3 2 treatment; 1 control x 3 pre-test, post-test, one week post-test design. The results indicate that information acquisition in location-aware systems is just as powerful as that facilitated by search engines and that information recall after 1 week of facts is superior when using location-aware systems. The findings reinforce and extend dual coding theory suggesting that spatial and three-dimensional indexing can be one of the channels used in indexing and recalling information. The results also indicate that location-aware applications are a promising technology for distributing information in general and for learning in particular.
Survey of Plagiarism Detection Approaches and Big data Techniques related to Plagiarism Candidate Retrieval

The easy and fast access to the web and the massive existence of databases of information systems today have led to an agile increase in the phenomenon of plagiarism as a serious problem for publishers and researchers. Fact, a number of researchers have discussed this problem by adopting several techniques that can detect plagiarism. Nevertheless, most of these techniques are still insufficient for the detection of intelligent plagiarism, which still needs to be improved. In this paper, we give an overview of the best-known methods of detection of plagiarism that exist. We start with defining the concept of plagiarism and its various forms most used by plagiarists. A thorough study of these approaches is then carried out, by establishing a comparative table of these approaches according to several criteria. Moreover, we finish by defining the concept of big data as well as one of these techniques that called Text mining, which applied in the phase of extraction of documents sources for plagiarism detection.
MERRA: NASA’s Modern-Era Retrospective Analysis for Research and Applications

AbstractThe Modern-Era Retrospective Analysis for Research and Applications (MERRA) was undertaken by NASA’s Global Modeling and Assimilation Office with two primary objectives: to place observations from NASA’s Earth Observing System satellites into a climate context and to improve upon the hydrologic cycle represented in earlier generations of reanalyses. Focusing on the satellite era, from 1979 to the present, MERRA has achieved its goals with significant improvements in precipitation and water vapor climatology. Here, a brief overview of the system and some aspects of its performance, including quality assessment diagnostics from innovation and residual statistics, is given.By comparing MERRA with other updated reanalyses [the interim version of the next ECMWF Re-Analysis (ERA-Interim) and the Climate Forecast System Reanalysis (CFSR)], advances made in this new generation of reanalyses, as well as remaining deficiencies, are identified. Although there is little difference between the new reanalyses i.
Mortality after total hip replacement surgery

Total hip replacement causes a short-term increase in the risk of mortality. It is important to quantify this and to identify modifiable risk factors so that the risk of post-operative mortality can be minimised. We performed a systematic review and critical evaluation of the current literature on the topic. We identified 32 studies published over the last 10 years which provide either 30-day or 90-day mortality data. We estimate the pooled incidence of mortality during the first 30 and 90 days following hip replacement to be 0.30% (95% CI 0.22 to 0.38) and 0.65% (95% CI 0.50 to 0.81), respectively. We found strong evidence of a temporal trend towards reducing mortality rates despite increasingly co-morbid patients. The risk factors for early mortality most commonly identified are increasing age, male gender and co-morbid conditions, particularly cardiovascular disease. Cardiovascular complications appear to have overtaken fatal pulmonary emboli as the leading cause of death after hip replacement. Cite this article: Bone Joint Res 2014;3:175–82.
Development of progressive landslide failure in cohesive materials

The development of progressive failure in slopes is a poorly understood process, and relatively few advances in terms of the mechanics of the development of failure have been made since 1967. However, advances in the understanding of the development of fractures in brittle materials provide new insights into landslide mechanics. In addition, the link between the deformation mechanism and movement type allows interpretation of displacement records to determine the mechanisms acting within a slope. This paper utilizes these insights into deformation processes, combined with “reinflation” stress-path triaxial experiments, to propose a new model for the development of a progressive, first-time failure within a slope. This model is able to explain the development of failure when the factor of safety is greater than unity, the existence of “Saito” linearity (a linear trend when the reciprocal of velocity prior to failure is plotted against time) during tertiary creep, and the development of failures during periods of apparently increasing normal effective stress.
Upwelling and its influence on nutrient concentration in the coastal area of the Hanko Peninsula, entrance of the Gulf of Finland

Abstract Upwelling was found to be a rather common phenomenon in the coastal area of the Hanko Peninsula. Intensive hydrographic and current measurements were made during 10 upwelling episodes in 1987-88. A clear relationship was noted between wind and current direction, and wind direction and change in salinity at 35 m depth during moderate or strong winds. Upwelling was observed as a sudden increase in salinity (Δ S ∼ 1) at 35 m depth and as a slight increase in salinity in the surface layer. When thermal stratification prevailed, the surface layer temperature dropped by as much as 10 °C, and nutrient concentrations increased; that of PO 4 -P from 1-2 μg PO 4 -Pl -1 to 4-8 μg PO 4 -Pl -1 and that of NH 4 -N from 0·5-2 μg NH 4 -Nl -1 up to 20 μg NH 4 -Nl -1 . During upwelling, a strong offshore flow was observed in the surface layer and a compensated onshore flow in a lower layer. In the study area the coastline followed the east-west axis and the upwelling occurred when the wind was from the directions between 190°-280°, and the wind impulse was at least ∼5000 kg m -1 s -1 (50 h of moderate wind). The minimum wind impulse required for upwelling seemed to be inversely proportional to the power of 5-10 of buoyancy. This means that during thermal stratification the necessary wind impulse is fairly constant and that the more homogeneous the water column is the more wind energy is needed (up to 14 000kg m -1 s -1 ).
Determining the Gravitational Gradient Tensor Using Satellite-Altimetry Observations over the Persian Gulf

With the advent of satellite altimetry in 1973, new scientific applications became available in oceanography, climatology, and marine geosciences. Moreover, satellite altimetry provides a significant source of information facilitated in the geoid determination with a high accuracy and spatial resolution. The information from this approach is a sufficient alternate for marine gravity data in the high-frequency modeling of the marine gravity field quantities. The gravity gradient tensor, consisting of the second-order partial derivatives of the gravity potential, provides more localized information than gravity measurements. Marine gravity observations always carry a high noise level due to environmental effects. Moreover, it is not possible to model the high frequencies of the Earth's gravity field in a global scale using these observations. In this article, we introduce a novel approach for a determination of the gravity gradient tensor at sea level using satellite altimetry. Two numerical techniques are applied and compared for this purpose. In particular, we facilitate the radial basis functions (RBFs) and the harmonic splines. As a case study, the gravitational gradient tensor is determined and results presented in the Persian Gulf. Validation of results reveals that the solution of the harmonic spline approach has a better agreement with a theoretical zero-value of the trace of the Marussi gravitational gradient tensor. However, the data-adaptive technique in the RBF approach allows more efficient selection of the parameters and 3-D configuration of RBFs compared to a fixed parameterization by the harmonic splines.
Application of normalized biomass size spectra to laser optical plankton counter net intercomparisons of zooplankton distributions

The optical plankton counter (OPC) and recently the laser OPC (LOPC) have been used primarily in two measurement applications: (1) identification of specific zooplankton species and (2) changes in zooplankton community structure using size-based spectral measurements. The normalized biomass size spectra (NBSS) are one representation of the size-based approach. The present study is based on utilizing the NBSS to describe the conditions or characteristics of the zooplankton community that allow a reasonable intercomparison of net samples and LOPC measurements made simultaneously for data collected during two oceanographic cruises carried out in the Lower Estuary and the Gulf of St. Lawrence in spring 2001 and 2002, respectively. NBSS linear slopes -0.7, or more "blue water" conditions, indicate the potential for reasonable intercomparison of the two methods. This observation applies to smaller-sized zooplankton such as copepodites of Calanus spp. with equivalent spherical diameter <900 μm. The measurement of larger Calanus spp. stages (IV-VI) did not seem affected by the presence of additional aggregates or gelatinous material and reasonable intercomparisons between LOPC and net were obtained for both sampling years. The LOPC signals produced by Calanus spp. (IV-VI) were larger and more easily separated.