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排序方式: 共有485条查询结果,搜索用时 359 毫秒
1.
B Conrad E Weidmann G Trucco WA Rudert R Behboo C Ricordi H Rodriquez-Rilo D Finegold M Trucco 《Canadian Metallurgical Quarterly》1994,371(6495):351-355
Insulin-dependent diabetes mellitus (IDDM) is a T-cell-mediated autoimmune disease whose onset is believed to be triggered by unknown environmental factors acting on a predisposing genetic background. Islet-infiltrating T (IIT) cells from two IDDM patients, who had died at the onset of the disease from brain swelling as a complication of ketoacidosis, were analysed. The results provided evidence for the involvement of a pancreatic islet cell membrane-bound superantigen as a diabetes aetiopathogenetic factor. There was a selective expansion of a T-cell receptor (TCR) variable segment of the beta-chain (V beta 7) in these IIT cells in association with unselected V alpha-chain segments; extensive junctional diversity of the TCR V beta 7 chains; and evidence of positive selection, after exposure to diabetic islet cell membrane preparations, of V beta 7+ T-cell clones among peripheral blood lymphocytes from non-diabetic individuals. 相似文献
2.
Laura Francesca Pisani Gian Eugenio Tontini Carmine Gentile Beatrice Marinoni Isabella Teani Nicoletta Nandi Pasquale Creo Emanuele Asti Luigi Bonavina Maurizio Vecchi Luca Pastorelli 《International journal of molecular sciences》2021,22(11)
Interleukin (IL)-33 is a member of the interleukin (IL)-1 family of cytokines linked to the development of inflammatory conditions and cancer in the gastrointestinal tract. This study is designed to investigate whether IL-33 has a direct effect on human gastric epithelial cells (GES-1), the human gastric adenocarcinoma cell line (AGS), and the gastric carcinoma cell line (NCI-N87) by assessing its role in the regulation of cell proliferation, migration, cell cycle, and apoptosis. Cell cycle regulation was also determined in ex vivo gastric cancer samples obtained during endoscopy and surgical procedures. Cell lines and tissue samples underwent stimulation with rhIL-33. Proliferation was assessed by XTT and CFSE assays, migration by wound healing assay, and apoptosis by caspase 3/7 activity assay and annexin V assay. Cell cycle was analyzed by means of propidium iodine assay, and gene expression regulation was assessed by RT-PCR profiling. We found that IL-33 has an antiproliferative and proapoptotic effect on cancer cell lines, and it can stimulate proliferation and reduce apoptosis in normal epithelial cell lines. These effects were also confirmed by the analysis of cell cycle gene expression, which showed a reduced expression of pro-proliferative genes in cancer cells, particularly in genes involved in G0/G1 and G2/M checkpoints. These results were confirmed by gene expression analysis on bioptic and surgical specimens. The aforementioned results indicate that IL-33 may be involved in cell proliferation in an environment- and cell-type-dependent manner. 相似文献
3.
4.
Emanuele Viola 《Computational Complexity》2009,18(3):337-375
We prove new results on the circuit complexity of approximate majority, which is the problem of computing the majority of a given bit string whose fraction of 1’s is bounded away from 1/2 (by
a constant). We then apply these results to obtain new relationships between probabilistic time, BPTime (t), and alternating time, ∑O(1)Time (t). Our main results are the following:
相似文献
1. | We prove that depth-3 circuits with bottom fan-in (log n)/2 that compute approximate majority on n bits must have size at least 2n0.12^{n^{0.1}}. As a corollary we obtain that there is no black-box proof that BPTime (t) í ?2\subseteq \sum_2Time (o(t2)). This complements the (black-box) result that BPTime (t) í ?2\subseteq \sum_2Time (t2 · poly log t) (Sipser and Gács, STOC ’83; Lautemann, IPL ’83). |
2. | We prove that approximate majority is computable by uniform polynomial-size circuits of depth 3. Prior to our work, the only known polynomial-size depth-3 circuits for approximate majority were non-uniform (Ajtai, Ann. Pure Appl. Logic ’83). We also prove that BPTime (t) í ?3\subseteq \sum_3Time (t · poly log t). This complements our results in (1). |
3. | We prove new lower bounds for solving QSAT3 ? ?3\in \sum_3Time (n · poly log n) on probabilistic computational models. In particular, we prove that solving QSAT3 requires time n1+Ω(1) on Turing machines with a random-access input tape and a sequential-access work tape that is initialized with random bits. No nontrivial lower bound was previously known on this model (for a function computable in linear space). |
5.
In this paper, we address markerless full-body articulated human motion tracking from multi-view video sequences acquired in a studio environment. The tracking is formulated as a multi-dimensional non-linear optimisation and solved using particle swarm optimisation (PSO), a swarm-intelligence algorithm which has gained popularity in recent years due to its ability to solve difficult non-linear optimisation problems. We show that a small number of particles achieves accuracy levels comparable with several recent algorithms. PSO initialises automatically, does not need a sequence-specific motion model and recovers from temporary tracking divergence through the use of a powerful hierarchical search algorithm (HPSO). We compare experimentally HPSO with particle filter (PF), annealed particle filter (APF) and partitioned sampling annealed particle filter (PSAPF) using the computational framework provided by Balan et al. HPSO accuracy and consistency are better than PF and compare favourably with those of APF and PSAPF, outperforming it in sequences with sudden and fast motion. We also report an extensive experimental study of HPSO over ranges of values of its parameters. 相似文献
6.
A synchronizing word for a given synchronizing DFA is called minimal if none of its proper factors is synchronizing. We characterize the class of synchronizing automata having only finitely many minimal synchronizing words (the class of such automata is denoted by FG). Using this characterization we prove that any such automaton possesses a synchronizing word of length at most 3n-5. We also prove that checking whether a given DFA A is in FG is co-NP-hard and provide an algorithm for this problem which is exponential in the number of states A. 相似文献
7.
Emanuele Bertarelli Alberto Corigliano Andreas Greiner Jan G. Korvink 《Microsystem Technologies》2011,17(1):165-173
A novel design strategy to avoid pull-in occurrence in electrostatic micro electro mechanical systems is proposed. It combines
charge control with ring electrodes, on a circular geometry. This idea is introduced here for the design of efficient and
reliable high stroke electrostatic diaphragm micropumps, while it has a broad potential applicability. A minimal lumped one
degree-of-freedom model is derived and used to introduce and demonstrate the proposed approach for a circular plate geometry.
Finite element models are subsequently adopted for a more detailed device modelling. As expected, charge control exhibits
a stabilizing effect with respect to voltage drive, but not sufficient to achieve a full-range stability for the considered
geometry. When the electrode area is properly defined, stability range can be extended up to gap closure in the central part
of the membrane. In this configuration, the increase in voltage required for full-range device drive would be relevant, while
in charge control the penalty is considerably lower. Finally, loading conditions and geometrical parameters for an optimized
actuation are suggested. 相似文献
8.
Emanuele Maiorana Jordi Solé-Casals Patrizio Campisi 《Machine Vision and Applications》2016,27(8):1351-1360
Electroencephalography (EEG) has been recently investigated as a biometric modality for automatic people recognition purposes. Several studies have shown that brain signals possess subject-specific traits that allow distinguishing people. Nonetheless, extracting discriminative characteristics from EEG recordings may be a challenging task, due to the significant presence of artifacts in the acquired data. In order to cope with such issue, in this paper we evaluate the effectiveness of some preprocessing techniques in automatically removing undesired EEG contributions, with the aim of improving the achievable recognition rates. Specifically, methods based on blind source separation and sample entropy estimation are here investigated. An extensive set of experimental tests, performed over a large database comprising recordings taken from 50 healthy subjects during three distinct sessions spanning a period of about one month, in both eyes-closed and eyes-open conditions, is carried out to analyze the performance of the proposed approaches. 相似文献
9.
This paper proposes a novel class of Command Governor (CG) strategies for input and state-related constrained discrete-time LTI systems subject to bounded disturbances in the absence of explicit state or output measurements. While in traditional CG schemes the set-point manipulation is undertaken on the basis of either the actual measure of the state or its suitable estimation, it is shown here that the CG design problem can be solved, with limited performance degradation and with similar properties, also in the case that such an explicit measure is not available. This approach, which will be referred to as the Feed-Forward CG (FF-CG) approach, may be a convenient alternative CG solution in all situations whereby the cost of measuring the state may be a severe limitation, e.g. in distributed or decentralized applications. In order to evaluate the method proposed here, numerical simulations on a physical example have been undertaken and comparisons with the standard state-based CG solution reported. 相似文献
10.
We study the problem of the amount of information required to perform fast broadcasting in tree networks. The source located
at the root of a tree has to disseminate a message to all nodes. In each round each informed node can transmit to one child.
Nodes do not know the topology of the tree but an oracle knowing it can give a string of bits of advice to the source which can then pass it down the tree with the source message. The quality of a broadcasting algorithm with
advice is measured by its competitive ratio: the worst case ratio, taken over n-node trees, between the time of this algorithm and the optimal broadcasting time in the given tree. Our goal is to find a
trade-off between the size of advice and the best competitive ratio of a broadcasting algorithm for n-node trees. We establish such a trade-off with an approximation factor of O(n
ε
), for an arbitrarily small positive constant ε. This is the first communication problem for which a trade-off between the size of advice and the efficiency of the solution
is shown for arbitrary size of advice. 相似文献