922 resultados para Traditional enrichment method


Relevância:

20.00% 20.00%

Publicador:

Resumo:

Over 80% of women diagnosed with advanced-stage ovarian cancer die as a result of disease recurrence due to failure of chemotherapy treatment. In this study, using two distinct ovarian cancer cell lines (epithelial OVCA 433 and mesenchymal HEY) we demonstrate enrichment in a population of cells with high expression of CSC markers at the protein and mRNA levels in response to cisplatin, paclitaxel and the combination of both. We also demonstrate a significant enhancement in the sphere forming abilities of ovarian cancer cells in response to chemotherapy drugs. The results of these in vitro findings are supported by in vivo mouse xenograft models in which intraperitoneal transplantation of cisplatin or paclitaxel-treated residual HEY cells generated significantly higher tumor burden compared to control untreated cells. Both the treated and untreated cells infiltrated the organs of the abdominal cavity. In addition, immunohistochemical studies on mouse tumors injected with cisplatin or paclitaxel treated residual cells displayed higher staining for the proliferative antigen Ki67, oncogeneic CA125, epithelial E-cadherin as well as cancer stem cell markers such as Oct4 and CD117, compared to mice injected with control untreated cells. These results suggest that a short-term single treatment of chemotherapy leaves residual cells that are enriched in CSC-like traits, resulting in an increased metastatic potential. The novel findings in this study are important in understanding the early molecular mechanisms by which chemoresistance and subsequent relapse may be triggered after the first line of chemotherapy treatment.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

BACKGROUND Asthma severity and control can be measured both subjectively and objectively. Sputum analysis for evaluation of percentage of sputum eosinophilia directly measures airway inflammation, and is one method of objectively monitoring asthma. Interventions for asthma therapies have been traditionally based on symptoms and spirometry. OBJECTIVES To evaluate the efficacy of tailoring asthma interventions based on sputum analysis in comparison to clinical symptoms (with or without spirometry/peak flow) for asthma related outcomes in children and adults. SEARCH STRATEGY We searched the Cochrane Airways Group Specialised Register of Trials, the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE and reference lists of articles. The last search was on 31 October 2006. SELECTION CRITERIA All randomised controlled comparisons of adjustment of asthma therapy based on sputum eosinophils compared to traditional methods (primarily clinical symptoms and spirometry/peak flow). DATA COLLECTION AND ANALYSIS Results of searches were reviewed against pre-determined criteria for inclusion. Three sets of reviewers selected relevant studies.Two review authors independently assessed trial quality extracted data. Authors were contacted for further information but none were received. Data was analysed as "treatment received" and sensitivity analyses performed. MAIN RESULTS Three adult studies were included; these studies were clinically and methodologically heterogenous (use of medications, cut off for percentage of sputum eosinophils and definition of asthma exacerbation). There were no eligible paediatric studies. Of 246 participants randomised, 221 completed the trials. In the meta-analysis, a significant reduction in number of participants who had one or more asthma exacerbations occurred when treatment was based on sputum eosinophils in comparison to clinical symptoms; pooled odds ratio (OR) was 0.49 (95% CI 0.28 to 0.87); number needed to treat to benefit (NNTB) was 6 (95% CI 4 to 32).There were also differences between groups in the rate of exacerbation (any exacerbation per year) and severity of exacerbations defined by requirement for use of oral corticosteroids but the reduction in hospitalisations was not statistically significant. Data for clinical symptoms, quality of life and spirometry were not significantly different between groups. The mean dose of inhaled corticosteroids per day was similar in both groups and no adverse events were reported. However sputum induction was not always possible. AUTHORS' CONCLUSIONS Tailored asthma interventions based on sputum eosinophils is beneficial in reducing the frequency of asthma exacerbations in adults with asthma. This review supports the use of sputum eosinophils to tailor asthma therapy for adults with frequent exacerbations and severe asthma. Further studies need to be undertaken to strengthen these results and no conclusion can be drawn for children with asthma.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Phospholipids are the key structural component of cell membranes, and recent advances in electrospray ionization mass spectrometry provide for the fast and efficient analysis of these compounds in biological extracts.1-3 The application of electrospray ionization tandem mass spectrometry (ESI-MS/MS) to phospholipid analysis has demonstrated several key advantages over the more traditional chromatographic methods, including speed and greater structural information.4 For example, the ESI-MS/MS spectrum of a typical phospholipidsparticularly in negative ion modesreadily identifies the carbon chain length and the degree of unsaturation of each of the fatty acids esterified to the parent molecule.5 A critical limitation of conventional ESI-MS/MS analysis, however, is the inability to uniquely identify the position of double bonds within the fatty acid chains. This is especially problematic given the importance of double bond position in determining the biological function of lipid classes.6 Previous attempts to identify double bond position in intact phospholipids using mass spectrometry employ either MS3 or offline chemical derivatization.7-11 The former method requires specialized instrumentation and is rarely applied, while the latter methods suffer from complications inherent in sample handling prior to analysis. In this communication we outline a novel on-line approach for the identification of double bond position in intact phospholipids. In our method, the double bond(s) present in unsaturated phospholipids are cleaved by ozonolysis within the ion source of a conventional ESI mass spectrometer to give two chemically induced fragment ions that may be used to unambiguously assign the position of the double bond. This is achieved by using oxygen as the electrospray nebulizing gas in combination with high electrospray voltages to initiate the formation of an ozoneproducing.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

We present a mini-scale method for nuclear run-on transcription assay. In our method, all the centrifuge steps can be carried out by using micro-tubes for short time (5 min each) throughout the process, including isolation of transcriptionally active nuclei and purification of labeled RNA after synthesis of RNA in isolated nuclei. The assay can be performed using a small amount of plant tissue, which enables analysis of developmental changes in transcriptional status of given genes in a single individual plant. Successful results were obtained using the tissues of flower and leaf of petunia and embryo of pea, suggesting that the method is potentially applicable to a variety of plant tissues.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

All design classes followed a systematic design approach, that, in an abstract way, can be characterized by figure 1. This approach is based on our design approach [1] that we labeled DUTCH (design for users and tasks, from concepts to handles).Consequently, each course starts with collecting, modeling, and analyzing an existing situation. The next step is the development of a vision on a future domain world where new technology and / or new representations have been implemented. This second step is the first tentative global design that will be represented in scenarios or prototypes and can be assessed. This second design model is based on both the client’s requirements and technological possibilities and challenges. In an iterative way multiple instantiations of detail design may follow, that each can be assessed and evaluated again...

Relevância:

20.00% 20.00%

Publicador:

Resumo:

MicroRNAs (miRNAs) are a class of small non-coding RNAs with a critical role in development and environmental responses. Efficient and reliable detection of miRNAs is an essential step towards understanding their roles in specific cells and tissues. However, gel-based assays currently used to detect miRNAs are very limited in terms of throughput, sensitivity and specificity. Here we provide protocols for detection and quantification of miRNAs by RT-PCR. We describe an end-point and real-time looped RT-PCR procedure and demonstrate detection of miRNAs from as little as 20 pg of plant tissue total RNA and from total RNA isolated from as little as 0.1 l of phloem sap. In addition, we have developed an alternative real-time PCR assay that can further improve specificity when detecting low abundant miRNAs. Using this assay, we have demonstrated that miRNAs are differentially expressed in the phloem sap and the surrounding vascular tissue. This method enables fast, sensitive and specific miRNA expression profiling and is suitable for facilitation of high-throughput detection and quantification of miRNA expression.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

With the growing size and variety of social media files on the web, it’s becoming critical to efficiently organize them into clusters for further processing. This paper presents a novel scalable constrained document clustering method that harnesses the power of search engines capable of dealing with large text data. Instead of calculating distance between the documents and all of the clusters’ centroids, a neighborhood of best cluster candidates is chosen using a document ranking scheme. To make the method faster and less memory dependable, the in-memory and in-database processing are combined in a semi-incremental manner. This method has been extensively tested in the social event detection application. Empirical analysis shows that the proposed method is efficient both in computation and memory usage while producing notable accuracy.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Traditional nearest points methods use all the samples in an image set to construct a single convex or affine hull model for classification. However, strong artificial features and noisy data may be generated from combinations of training samples when significant intra-class variations and/or noise occur in the image set. Existing multi-model approaches extract local models by clustering each image set individually only once, with fixed clusters used for matching with various image sets. This may not be optimal for discrimination, as undesirable environmental conditions (eg. illumination and pose variations) may result in the two closest clusters representing different characteristics of an object (eg. frontal face being compared to non-frontal face). To address the above problem, we propose a novel approach to enhance nearest points based methods by integrating affine/convex hull classification with an adapted multi-model approach. We first extract multiple local convex hulls from a query image set via maximum margin clustering to diminish the artificial variations and constrain the noise in local convex hulls. We then propose adaptive reference clustering (ARC) to constrain the clustering of each gallery image set by forcing the clusters to have resemblance to the clusters in the query image set. By applying ARC, noisy clusters in the query set can be discarded. Experiments on Honda, MoBo and ETH-80 datasets show that the proposed method outperforms single model approaches and other recent techniques, such as Sparse Approximated Nearest Points, Mutual Subspace Method and Manifold Discriminant Analysis.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Finite element models of bones can be created by deriving geometry from anx-ray CT scan. Material properties such as the elastic modulus can then be applied using either a single or set of homogeneous values, or individual elements can have local values mapped onto them. Values for the elastic modulus can be derived from the CT density values using an elasticityversus density relationship. Many elasticity–density relationships have been reported in the literature for human bone. However, while ovine in vivo models are common in orthopaedic research, no work has been done to date on creating FE models of ovine bones. To create these models and apply relevant material properties, an ovine elasticity-density relationship needs to be determined. Using fresh frozen ovine tibias the apparent density of regions of interest was determined from a clinical CT scan. The bones were the sectioned into cuboid samples of cortical bone from the regions of interest. Ultrasound was used to determine the elastic modulus in each of three directions – longitudinally, radially and tangentially. Samples then underwent traditional compression testing in each direction. The relationships between apparent density and both ultrasound, and compression modulus in each directionwere determined. Ultrasound testing was found to be a highly repeatable non-destructive method of calculating the elastic modulus, particularly suited to samples of this size. The elasticity-density relationships determined in the longitudinal direction were very similar between the compression and ultrasound data over the density range examined.A clear difference was seen in the elastic modulus between the longitudinal and transverse directions of the bone samples, and a transverse elasticity-density relationship is also reported.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Accurate and detailed measurement of an individual's physical activity is a key requirement for helping researchers understand the relationship between physical activity and health. Accelerometers have become the method of choice for measuring physical activity due to their small size, low cost, convenience and their ability to provide objective information about physical activity. However, interpreting accelerometer data once it has been collected can be challenging. In this work, we applied machine learning algorithms to the task of physical activity recognition from triaxial accelerometer data. We employed a simple but effective approach of dividing the accelerometer data into short non-overlapping windows, converting each window into a feature vector, and treating each feature vector as an i.i.d training instance for a supervised learning algorithm. In addition, we improved on this simple approach with a multi-scale ensemble method that did not need to commit to a single window size and was able to leverage the fact that physical activities produced time series with repetitive patterns and discriminative features for physical activity occurred at different temporal scales.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The aim of this thesis is to show how character analysis can be used to approach conceptions of saga authorship in medieval Iceland. The idea of possession is a metaphor that is adopted early in the thesis, and is used to describe Icelandic sagas as works in which traditional material is subtly interpreted by medieval authors. For example, we can say that if authors claim greater possession of the sagas, they interpret, and not merely record, the sagas' historical information. On the other hand, tradition holds onto its possession of the narrative whenever it is not possible for an author to develop his own creative and historical interests. The metaphor of possession also underpins the character analysis in the thesis, which is based on the idea that saga authors used characters as a vehicle by which to possess saga narratives and so develop their own historical interests. The idea of possession signals the kinds of problems of authorship study which are addressed here, in particular, the question of the authors' sense of saga writing as an act either of preservation or of creation. While, in that sense, the thesis represents an additional voice in a long-standing debate about the saga writers' relation to their source materials, I argue against a clear-cut distinction between creative and non-creative authors, and focus instead on the wide variation in authorial control over saga materials. This variation suggests that saga authorship is a multi-functional activity, or one which co-exists with tradition. Further, by emphasising characterisation as a method, I am adding to the weight of scholarship that seeks to understand the sagas in terms of their literary effects. The Introduction and chapter one lay out the theoretical scope of this thesis. My aim in these first two sections is to inform the reader of the type of critical questions that arise when authorship is approached in relation to characterisation, and to suggest an interpretive framework with which to approach these questions. In the Introduction this aim manifests as a brief discussion of the application of the term "authorship" to the medieval Icelandic corpus, a definition of the scope of this study, and an introduction to the connections, made throughout this thesis, between saga authors, the sagas' narrative style, and the style of characterisation in the sagas. Chapter one is a far more detailed discussion of our ability to make these connections. In particular, the chapter develops the definition of the analytical term "secondary authorship" that I introduce in order to delineate the type of characterisation that is of most interest in this thesis. "Secondary authorship" is a literary term that aims to sharpen our approach to saga authors' relationship to their characters by focusing on characters who make representations about the events of the saga. The term refers to any instance in which characters behave in a manner that resembles the creativity, interpretation, and understanding associated with authorship more generally. Character analysis cannot, however, be divorced from socio-historical approaches to the saga corpus. Most importantly, the sagas themselves are socio-historical representations that claim some degree of truth value. This claim that the sagas make by implication about their historicity is the starting point of a discussion of authorship in medieval Iceland. Therefore, at the beginning of chapter one I discuss some of the approaches to the social context of saga writing. This discussion serves as an introduction to both the culture of saga writing in medieval Iceland and to the nature of the sagas' historical perspective, and reflects my sense that literary interpretations of the sagas cannot be isolated from the historical discourses that frame them. The chapter also discusses possession, which, as I note above, is used alongside the concept of secondary authorship to describe the saga authors' relationship with the stories and characters of the past. At the close of chapter one, I offer a preliminary list the various functions of saga authorship, and give some examples of secondary authorship. From this point I am able to tie my argument about secondary authorship to specific examples from the sagas. Chapter two examines the effect of family obligations and domestic points of view in the depiction of characters' choices and conception of themselves. The examples that are given in that chapter - from Gisla saga Súrssonar and Íslendinga saga - are the first of a number of textual analyses that demonstrate the application of the concepts of secondary authorship and possession of saga narratives. The relationship between narratives about national and domestic matters shows how authorial creativity in the area of kinship obligation provides the basis for the saga's development of historical themes. Thus, the two major case studies given in chapter two tie authorial engagement with characters to the most influential social institution in early and medieval Iceland, the family. The remaining chapters represent similar attempts to relate authorial possession of saga characters to central socio-historical themes in the sagas, such as the settlement process in early Iceland and its influence on the development of regional political life (chapter three). Likewise, the strong authorial interest in an Icelander's journey to Norway in Heimskringla is presented as evidence of the author's use of a saga character to express an Icelandic interpretation of Norwegian history and to promote a sense that Iceland shared the ownership of regal history with Norway (chapter four). In that authorial engagement with the Icelander abroad, we witness saga characterisation being used as a basis for historical interpretation and the means by which foreign traditions and influence, not least the narratives of royal lives and of the Christianisation, are claimed as part of medieval Icelanders' self-conception. While saga authors observe the conventions of saga narration, characters are often subtly positioned as the authors' interpretive mirrors, especially clear than when they act as secondary authors. Nowhere is this more apparent than in Brennu- Njáls saga, which contains many characters who voice the author's claim to interpret the past. Even Hrútr Herjólfsson, through his remarkable perception of events and his conspicuous comments about them, acts as a secondary author by enabling the author to emphasise the importance of the disposition of characters. In Laxdœla saga and Þorgils saga ok Hafliða, authorial interest in characters' perception is matched by the thematising of learning, from the inception of knowledge as prophecy or advice to complete understanding by saga characters (chapter six). In Þorgils saga skarða, a character's inner development from an excessively ambitious and politically ruthless youth to a Christian leader killed by his kinsman allows the author to shape a political life into a lesson about leadership and the community's ability to moderate and contain the behaviour of extraordinary individuals. The portrayal draws on methods of characterisation that we can identify in Grettis saga Ásmundarson, Fóstbrœðra saga, and Orkneyinga saga. A comparison of the characterisation of figures with intense political or military ambitions suggests that saga authors were interested in the community's ability to balance their strength and ability with a degree of social moderation. The discussion of these sagas shows that character study can be used to analyse how the saga authors added their own voice to the voices passed down to medieval Icelanders in traditional narratives. Authorial engagement with characters allowed inherited traditions about early Norway and Iceland and records of thirteenth century events to be transformed into sophisticated historical works with highly creative elements. Through secondary authorship, saga authors took joint-possession of narratives and contested the power of tradition in setting the interpretive framework of a saga.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

In this paper, the inherent mechanism of social benefits associated with smart grid development is examined based on the pressure state response (PSR) model from resource economics. The emerging types of technology brought up by smart grid development are regarded as pressures. The improvements of the performance and efficiency of power system operation, such as the enhanced capability of accommodating renewable energy generation, are regarded as states. The effects of smart grid development on society are regarded as responses. Then, a novel method for evaluating social benefits from smart grid development is presented. Finally, the social benefits from smart grid development in a province in northwest China are carried out by using the developed evaluation system, and reasonable evaluation results are attained.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Interior permanent-magnet synchronous motors (IPMSMs) become attractive candidates in modern hybrid electric vehicles and industrial applications. Usually, to obtain good control performance, the electric drives of this kind of motor require one position, one dc link, and at least two current sensors. Failure of any of these sensors might lead to degraded system performance or even instability. As such, sensor fault resilient control becomes a very important issue in modern drive systems. This paper proposes a novel sensor fault detection and isolation algorithm based on an extended Kalman filter. It is robust to system random noise and efficient in real-time implementation. Moreover, the proposed algorithm is compact and can detect and isolate all the sensor faults for IPMSM drives. Thorough theoretical analysis is provided, and the effectiveness of the proposed approach is proven by extensive experimental results.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

In this paper, we consider the problem of document ranking in a non-traditional retrieval task, called subtopic retrieval. This task involves promoting relevant documents that cover many subtopics of a query at early ranks, providing thus diversity within the ranking. In the past years, several approaches have been proposed to diversify retrieval results. These approaches can be classified into two main paradigms, depending upon how the ranks of documents are revised for promoting diversity. In the first approach subtopic diversification is achieved implicitly, by choosing documents that are different from each other, while in the second approach this is done explicitly, by estimating the subtopics covered by documents. Within this context, we compare methods belonging to the two paradigms. Furthermore, we investigate possible strategies for integrating the two paradigms with the aim of formulating a new ranking method for subtopic retrieval. We conduct a number of experiments to empirically validate and contrast the state-of-the-art approaches as well as instantiations of our integration approach. The results show that the integration approach outperforms state-of-the-art strategies with respect to a number of measures.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Cougars, Grannies, Evil Stepmothers, and Menopausal Hot Flashers: Roles, Representations of Age and the Non-traditional Romance Heroine is an examination of the stereotyped roles of age and the under-representation of women over forty as worthy protagonists in romance fiction.