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排序方式: 共有349条查询结果,搜索用时 31 毫秒
341.
Recent studies with adeno-associated virus (AAV) have shown that site-specific integration is directed by DNA sequence motifs that are present in both the viral replication origin and the chromosomal preintegration DNA and that specify binding and nicking sites for the viral regulatory Rep protein. This finding raised the question as to whether other parvovirus regulatory proteins might direct site-specific recombination with DNA targets that contain origin sequences functionally equivalent to those described for AAV. To investigate this question, active and inactive forms of the minute virus of mice (MVM) 3' replication origin, derived from a replicative-form dimer-bridge intermediate, were propagated in an Epstein-Barr virus-based shuttle vector which replicates as an episome in a cell-cycle-dependent manner in mammalian cells. Upon MVM infection of these cells, the infecting genome integrated into episomes containing the active-origin sequence reported to be efficiently nicked by the MVM regulatory protein NS1. In contrast, MVM did not integrate into episomes containing either the inactive form of the origin sequence reported to be inefficiently nicked by NS1 or the active form from which the NS1 consensus nick site had been deleted. The structure of the cloned MVM episomal recombinants displayed several features previously described for AAV episomal and chromosomal recombinants. The findings indicate that the rules which govern AAV site-specific recombination also apply to MVM and suggest that site-specific chromosomal insertions may be achievable with different autonomous parvovirus replicator proteins which recognize binding and nicking sites on the target DNA. 相似文献
342.
In this paper, we consider the problem of linearly prefiltering and coding a random process which is to be sampled in time and transmitted over a noisy channel. We take the linear reconstruction filter at the receiving end to be fixed and known, and we then determine the form of the optimum linear prefilter subject to a power constraint on its output. If the process to be filtered is described using a state-space representation, the prefilter can be realized as a continuous Kalman filter followed by a digital filter which in general has memory. If the duration of the impulse response of the reconstruction filter is less than the interval between adjacent samples, the digital filter becomes a memoryless matrix coder. 相似文献
343.
AbstractThis study explores the relationship between art and urban boundaries using the case study of a fringe theatre festival in the Israeli mixed-city of Acre. While mixed cities today are understood as agglomerations of enclaves, maintained and reinforced by boundaries, urban designers and artists have used art as a culture-led regeneration strategy through which these boundaries may be breached. This study undermines the shared assumption of both fields: that art has the power to breach boundaries, by juxtaposing a city’s artistic activity with its segregation patterns and boundaries. Using super-positioning, the findings of two research methods have been integrated: urban research and ethnographic field work. The article shows that although the artistic activity in question is rooted in an avant-garde radical desire to subvert socioeconomic structures, it actually produces new versions and interpretations of the same segregations and boundaries in both space and society. 相似文献
344.
Tissue engineering aims at developing functional substitutes for damaged tissues and organs. Before transplantation, cells are generally seeded on biomaterial scaffolds that recapitulate the extracellular matrix and provide cells with information that is important for tissue development. Here we review the nanocomposite nature of the extracellular matrix, describe the design considerations for different tissues and discuss the impact of nanostructures on the properties of scaffolds and their uses in monitoring the behaviour of engineered tissues. We also examine the different nanodevices used to trigger certain processes for tissue development, and offer our view on the principal challenges and prospects of applying nanotechnology in tissue engineering. 相似文献
345.
探讨了饱和强化粘塑性介质中的动态损伤演化规律,给出了损伤演化微分方程。利用动态破碎的能量描述,确定了动态破碎碎块平均尺寸与材料孔隙度的定量关系。最后给出了动态损伤与破碎规律的数值结果。 相似文献
346.
Eyal Malka Ilana Perelshtein Anat Lipovsky Yakov Shalom Livnat Naparstek Nina Perkas Tal Patick Rachel Lubart Yeshayahu Nitzan Ehud Banin Aharon Gedanken 《Small (Weinheim an der Bergstrasse, Germany)》2013,9(23):4069-4076
Zinc‐doped copper oxide nanoparticles are synthesized and simultaneously deposited on cotton fabric using ultrasound irradiation. The optimization of the processing conditions, the specific reagent ratio, and the precursor concentration results in the formation of uniform nanoparticles with an average size of ≈30 nm. The antibacterial activity of the Zn‐doped CuO Cu0.88Zn0.12O in a colloidal suspension or deposited on the fabric is tested against Escherichia coli (Gram negative) and Staphylococcus aureus (Gram positive) bacteria. A substantial enhancement of 10 000 times in the antimicrobial activity of the Zn–CuO nanocomposite compared to the pure CuO and ZnO nanoparticles (NPs) is observed after 10 min exposure to the bacteria. Similar activities are observed against multidrug‐resistant bacteria (MDR), (i.e., Methicillin‐resistant S. aureus and MDR E. coli) further emphasizing the efficacy of this composite. Finally, the mechanism for this enhanced antibacterial activity is presented. 相似文献
347.
Shimrit Heiliczer Asaf Wilensky Tal Gaver Olga Georgiev Sharleen Hamad Alina Nemirovski Rivka Hadar Yair Sharav Doron J. Aframian Joseph Tam Yaron Haviv 《International journal of molecular sciences》2022,23(21)
The endocannabinoid system is involved in physiological and pathological processes, including pain generation, modulation, and sensation. Its role in certain types of chronic orofacial pain (OFP) has not been thoroughly examined. By exploring the profiles of specific salivary endocannabinoids (eCBs) in individuals with different types of OFP, we evaluated their use as biomarkers and the influence of clinical parameters and pain characteristics on eCB levels. The salivary levels of anandamide (AEA), 2-arachidonoyl glycerol (2-AG), and their endogenous breakdown product arachidonic acid (AA), as well as the eCB-like molecules N-palmitoylethanolamide (PEA) and N-oleoylethanolamide (OEA), were assessed in 83 OFP patients and 43 pain-free controls using liquid chromatography/tandem mass spectrometry. Patients were grouped by diagnosis: post-traumatic neuropathy (PTN), trigeminal neuralgia (TN), temporomandibular disorder (TMD), migraine, tension-type headache (TTH), and burning mouth syndrome (BMS). Correlation analyses between a specific diagnosis, pain characteristics, and eCB levels were conducted. Significantly lower levels of 2-AG were found in the TN and TTH groups, while significantly lower PEA levels were found in the migraine group. BMS was the only group with elevated eCBs (AEA) versus the control. Significant correlations were found between levels of specific eCBs and gender, health-related quality of life (HRQoL), BMI, pain duration, and sleep awakenings. In conclusion, salivary samples exhibited signature eCBs profiles for major OFP disorders, especially migraine, TTH, TN, and BMS. This finding may pave the way for using salivary eCBs biomarkers for more accurate diagnoses and management of chronic OFP patients. 相似文献
348.
Brama Haya Dery Lihi Grinshpoun Tal 《International Journal of Information Security》2023,22(2):525-540
International Journal of Information Security - The problem of attacks on neural networks through input modification (i.e., adversarial examples) has attracted much attention recently. Being... 相似文献
349.
With the advent of on-site robotic tools, they can be deployed for editing landscapes – defined as the modulation of grounds with a high degree of sensitivity to matter and form. The paper contributes a theoretical grounding and two experimental frameworks for territorial-based robotic fabrication. Each experimental framework supports a robotic capacity for informing and forming grounds, demonstrated in relation to extreme territories using simulation setups. The frameworks include (1) a layer-sensitive modulation for protecting topsoil and (2) a performance-based robotic forming for creating wind barriers. For each framework, the paper proposes a setup, an exploration method, and an evaluation process. Drawing on the presented frameworks, the paper outlines three potentials of territorial-based robotic fabrication: the capability to modulate grounds vertically, the possibility to perform cross-scalar forming, and the opportunity to form dynamic, performative landscapes. The paper concludes with potential ways in which robotic tools could be leveraged for advancing precise landscape editing across scales. 相似文献