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排序方式: 共有461条查询结果,搜索用时 15 毫秒
1.
This paper presents a brief overview of recent approaches to two problems in music information retrieval: query by example and automated source separation. It describes the challenges inherent in musical query by example and the systems that take very different approaches to the problem. The paper also explores approaches to source separation in a musical context, focusing on systems that take distinct approaches to the problem. Finally, it comments about the future directions for digital signal processing (DSP) research in the context of music information retrieval. 相似文献
2.
Varani L. Reggiani L. Kuhn T. Gonzalez T. Pardo D. 《Electron Devices, IEEE Transactions on》1994,41(11):1916-1925
We present a microscopic interpretation of electronic noise in semiconductor materials and two-terminal devices. The theory is based on Monte Carlo simulations of the carrier motion self-consistently coupled with a Poisson solver. Current and voltage noise operations are applied and their respective representations discussed. As application we consider the cases of homogeneous materials, resistors, n+nn + structures, and Schottky-barrier diodes. Phenomena associated with coupling between fluctuations in carrier velocity and self-consistent electric field are quantitatively investigated for the first time. At increasing applied fields hot-carrier effects are found to be of relevant importance in all the cases considered here. As a general result, noise spectroscopy is found to be a source of valuable information to investigate and characterize transport properties of semiconductor materials and devices 相似文献
3.
Nguyen-Huy Dung Pardo Marie-Paule Dogguy.Smiri Leïla 《Materials Research Bulletin》1982,17(3):293-300
The Mn0.23Ga1.85S3 phase belongs to the solid solution , stable at low temperature in the Ga2S3MnS system. It is hexagonal superstructure of the wurtzite, with the Ga2S3α′ type (; Z = 6; space groupe P61 or P65). Its crystal structure has been refined by the least squares method to a final R = 0.06 with 323 independant reflections. This structure is closely related to Ga2S3 α described by Hahn and Frank, and differs only by the partial occupation of the vacant metal site of Ga2S3 by Mn atoms in statistical disorder. 相似文献
4.
A CMOS log-polar image sensor has been designed and fabricated. As a result, a systematic approach has been proposed to design space-variant sensors and layouts. The pixels in this sensor are distributed in a polar fashion; the image plane consists of concentric rings containing the elementary sensing cells. Such a structure, where polygons use any space orientation, does not match very well with current design tools and CMOS fabrication processes. An approach to design nonorthogonal repetitive structures using standard fabrication processes and computer-aided design (CAD) tools is presented. The result of this work is an image sensor, with log-polar structure, suitable for image processing since the log-polar mapping has interesting mathematical and image data reduction properties 相似文献
5.
In this work we present a snake based approach for the segmentation of images of computerized tomography (CT) scans. We introduce a new term for the internal energy and another one for external energy which solve common problems associated with classical snakes in this type of images. A simplified minimizing method is also presented. 相似文献
6.
Ochratoxin A (OTA) is a secondary metabolite produced by several species of Aspergillus and Penicillium; among them Aspergillus ochraceus and Penicillium verrucosum are two ochratoxigenic species capable of growing in different climates and thus contamination of food crops with OTA can occur worldwide. OTA can be found in a wide range of foods such as cereals, coffee, cocoa, spices, beer, wine, dried vine fruit, grapes and meat products. OTA is toxic to animals, it presents neurotoxic, immunotoxic and nephrotoxic effects. It has been implicated in a human kidney disorder known as Balkan Endemic Nephropathy. This review focuses on the ecophysiology of ochratoxin-producing Aspergillus ochraceus and Penicillium verrucosum, the effect of environmental factors on their germination, mycelial growth, and OTA production. Knowledge of environmental conditions required for sucessive stages of fungal development represent the first step towards preventing mycotoxin formation. Predictive models for different stages of fungal development are presented, which allow prediction of the time before spoilage as a function of the abiotic factors. Finally, the implications of these studies in management of barley, coffee and grapes are described. This can help to identify the critical control points in their production, storage and distribution processes. 相似文献
7.
8.
Glutamine 105 in the third transmembrane helix of the thyrotropin-releasing hormone receptor (TRH-R) occupies a position equivalent to a conserved negatively charged residue in receptors for biogenic amines where it acts as counterion interacting with the cationic amine moiety of the ligand. Maximum levels of response to TRH in oocytes expressing wild-type TRH-Rs were indistinguishable from those of oocytes expressing receptors mutated to Glu, Asn, or Asp in position 105. However, the EC50 values for activation of oocyte responses increased more than 500 times in oocytes expressing mutant Glu105 receptors, in which the amido group of Gln105 has been removed by site-directed mutagenesis. Charge effects do not seem to be involved in the huge effect of mutating Gln105 to Glu, since mutation of Gln105 to Asp induces only a 15-fold increase in EC50. Furthermore, no change in EC50 is observed after mutation of Asn110 to Asp. The affinity shift (identified by changes in EC50 values for systems of comparable efficacy) in Glu105 mutant receptors was partially recovered in oocytes expressing Asn105 mutant receptors. These results and those obtained after substitution of Lys, Leu, Tyr, and Ser for Gln105 suggest that the presence and the correct position of the Gln hydrogen bond-donor amido group are important for normal functionality of the receptor. In wild type or Asp105 mutant receptors showing the same maximal responses, decreases in affinity with TRH and methyl-histidyl-TRH correlated with increased dissociation rates of hormone from the receptor. Rapid dilution experiments following subsecond stimulation indicate that the TRH-R is converted rapidly from a form showing fast dissociation kinetics to a form from which the hormone dissociates slowly. Mutation of residue 105 impairs the receptor shift between these two forms. This effect was demonstrated in a direct way by comparing [3H]methyl-histidyl-TRH dissociation rates in COS-7 cells transfected with either wild type or Asp105 mutant TRH-Rs. Thus, residues located in transmembrane helix III positions equivalent to those of the counterions for biogenic amines, regulate hormone-receptor interactions in the TRH receptor (and perhaps other receptors). Furthermore, the nature of the amino acid in these positions may also play a role, directly or indirectly, in conformational changes leading to receptor activation, and hence to signal transduction. 相似文献
9.
Morales D. Pardo L. Vajda I. 《IEEE transactions on systems, man, and cybernetics. Part A, Systems and humans : a publication of the IEEE Systems, Man, and Cybernetics Society》1996,26(6):681-697
Uncertainty is defined in a new manner, as a function of discrete probability distributions satisfying a simple and intuitively appealing weak monotonicity condition. It is shown that every uncertainty is Schur-concave and conversely, every Schur-concave function of distributions is an uncertainty. General properties of uncertainties are systematically studied. Many characteristics of distributions introduced previously in statistical physics, mathematical statistics, econometrics and information theory are shown to be particular examples of uncertainties. New examples are introduced, and traditional as well as some new methods for obtaining uncertainties are discussed. The information defined by decrease of uncertainty resulting from an observation is investigated and related to previous concepts of information. Further, statistical inference about uncertainties is investigated, based on independent observations of system states. In particular, asymptotic distributions of maximum likelihood estimates of uncertainties and uncertainty-related functions are derived, and asymptotically α-level Neyman-Pearson tests of hypotheses about these system characteristics are presented 相似文献
10.
Vicen Ruiz de Porras Juan Carlos Pardo Lucia Notario Olatz Etxaniz Albert Font 《International journal of molecular sciences》2021,22(9)
Since 2010, several treatment options have been available for men with metastatic castration-resistant prostate cancer (mCRPC), including immunotherapeutic agents, although the clinical benefit of these agents remains inconclusive in unselected mCRPC patients. In recent years, however, immunotherapy has re-emerged as a promising therapeutic option to stimulate antitumor immunity, particularly with the use of immune checkpoint inhibitors (ICIs), such as PD-1/PD-L1 and CTLA-4 inhibitors. There is increasing evidence that ICIs may be especially beneficial in specific subgroups of patients with high PD-L1 tumor expression, high tumor mutational burden, or tumors with high microsatellite instability/mismatch repair deficiency. If we are to improve the efficacy of ICIs, it is crucial to have a better understanding of the mechanisms of resistance to ICIs and to identify predictive biomarkers to determine which patients are most likely to benefit. This review focuses on the current status of ICIs for the treatment of mCRPC (either as monotherapy or in combination with other drugs), mechanisms of resistance, potential predictive biomarkers, and future challenges in the management of mCRPC. 相似文献