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111.
Mesoporous alumina has been synthesised by the solution combustion synthesis method. While often the synthesis of mesoporous
materials with a relatively narrow pore distribution requires the use of a template, this technique allows a simple and rapid
synthesis of pure alumina without the use of any templating agent: by regulating the synthesis conditions is possible to obtain
from relatively low surface area α-alumina to high surface mesoporous γ-alumina. The porosity of the latter was assessed chiefly
by density functional method and was found to be in the range 2.8–3.5 nm. Low angle X-ray diffraction experiments demonstrated
a partial ordering of the structure, with a periodicity in the range 5.5–6.9 nm. The addition of lanthanum to the alumina
was tested and found to confer a good temperature resistance to the alumina, without modifying the mesoporous structure. After
a prolonged heat treatment at 900 °C the mesoporosity of lanthanum-modified samples was retained, even if the pores size increased
and the specific surface area decreased. 相似文献
112.
Matteo Colombo 《Minds and Machines》2010,20(2):183-202
According to John Haugeland, the capacity for “authentic intentionality” depends on a commitment to constitutive standards
of objectivity. One of the consequences of Haugeland’s view is that a neurocomputational explanation cannot be adequate to
understand “authentic intentionality”. This paper gives grounds to resist such a consequence. It provides the beginning of
an account of authentic intentionality in terms of neurocomputational enabling conditions. It argues that the standards, which
constitute the domain of objects that can be represented, reflect the statistical structure of the environments where brain
sensory systems evolved and develop. The objection that I equivocate on what Haugeland means by “commitment to standards”
is rebutted by introducing the notion of “florid, self-conscious representing”. Were the hypothesis presented plausible, computational
neuroscience would offer a promising framework for a better understanding of the conditions for meaningful representation. 相似文献
113.
Martini Maria G. Istepanian Robert S. H. Mazzotti Matteo Philip Nada 《Mobile Computing, IEEE Transactions on》2010,9(1):5-16
M-health is an emerging area of research and one of the key challenges in future research in this area is medical video streaming over wireless channels. Contrasting requirements of almost lossless compression and low available bandwidth have to be tackled in medical quality video streaming in ultrasound and radiology applications. On one side, compression techniques need to be conservative, in order to avoid removing perceptively important information; on the other side, error resilience and correction should be provided, with the constraint of a limited bandwidth. A quality-driven, network-aware approach for joint source and channel coding based on a controller structure specifically designed for enhanced video streaming in a robotic teleultrasonography system is presented. The designed application based on robotic teleultrasonography is described and the proposed method is simulated in a wireless environment in two different scenarios; the video quality improvement achievable through the proposed scheme in such an application is remarkable, resulting in a peak signal-to-noise ratio (PSNR) improvement of more than 4 dB in both scenarios. 相似文献
114.
Sueva Cantalupo Vito Alessandro Lasorsa Roberta Russo Immacolata Andolfo Giuseppe DAlterio Barbara Eleni Rosato Giulia Frisso Pasquale Abete Gian Marco Cassese Giuseppe Servillo Ivan Gentile Carmelo Piscopo Matteo Della Monica Giuseppe Fiorentino Giuseppe Russo Pellegrino Cerino Carlo Buonerba Biancamaria Pierri Massimo Zollo Achille Iolascon Mario Capasso 《International journal of molecular sciences》2021,22(10)
Genome-wide association studies (GWAS) found locus 3p21.31 associated with severe COVID-19. CCR5 resides at the same locus and, given its known biological role in other infection diseases, we investigated if common noncoding and rare coding variants, affecting CCR5, can predispose to severe COVID-19. We combined single nucleotide polymorphisms (SNPs) that met the suggestive significance level (P ≤ 1 × 10−5) at the 3p21.31 locus in public GWAS datasets (6406 COVID-19 hospitalized patients and 902,088 controls) with gene expression data from 208 lung tissues, Hi-C, and Chip-seq data. Through whole exome sequencing (WES), we explored rare coding variants in 147 severe COVID-19 patients. We identified three SNPs (rs9845542, rs12639314, and rs35951367) associated with severe COVID-19 whose risk alleles correlated with low CCR5 expression in lung tissues. The rs35951367 resided in a CTFC binding site that interacts with CCR5 gene in lung tissues and was confirmed to be associated with severe COVID-19 in two independent datasets. We also identified a rare coding variant (rs34418657) associated with the risk of developing severe COVID-19. Our results suggest a biological role of CCR5 in the progression of COVID-19 as common and rare genetic variants can increase the risk of developing severe COVID-19 by affecting the functions of CCR5. 相似文献
115.
The nonholonomic nature of rolling between rigid bodies can be exploited to achieve dextrous manipulation of industrial parts
with minimally complex robotic effectors. While for parts with smooth surfaces a relatively well-developed theory exists,
planning for parts with only piecewise smooth surfaces is largely an open problem.
The problem of arbitrarily displacing and reorienting a polyhedron by means of rotations about edges belonging to a fixed
plane is considered. Relevant theoretical results are reviewed, and a polynomial time algorithm is proposed that allows planning
such motions. The effects of finite accuracy in representing problem data, as well as the operational and computational complexity
of the method are considered in detail.
Received November 15, 1996; revised February 12, 1998. 相似文献
116.
Wine ageing in wood barrels is a traditional practice in quality wine-making areas. It is generally believed that the organoleptic characteristics of wines aged in barrels are deeply influenced by wood geographical origin, as well as by age of barrels (new or used). 相似文献
117.
A new 3 D.O.F. spatial parallel mechanism 总被引:3,自引:0,他引:3
Marco Ceccarelli 《Mechanism and Machine Theory》1997,32(8):895-902
This paper describes a new 3 D.O.F. parallel mechanism. The kinematic chain is composed of leg mechanisms containing articulated parallelograms and a peculiar connection with ball joints and prismatic guides has been utilised to obtain suitable direct kinematics and easy actuation. The engineering feasibility has been illustrated by investigating on the basic kinematic performances. Particularly, an analytical algorithm has been developed for displacement analysis which permits an easy workspace evaluation and path generation for trajectory and orientation capabilities. 相似文献
118.
Anna Stainer Paola Faverio Sara Busnelli Martina Catalano Matteo Della Zoppa Almerico Marruchella Alberto Pesci Fabrizio Luppi 《International journal of molecular sciences》2021,22(12)
Idiopathic pulmonary fibrosis (IPF), the most lethal form of interstitial pneumonia of unknown cause, is associated with a specific radiological and histopathological pattern (the so-called “usual interstitial pneumonia” pattern) and has a median survival estimated to be between 3 and 5 years after diagnosis. However, evidence shows that IPF has different clinical phenotypes, which are characterized by a variable disease course over time. At present, the natural history of IPF is unpredictable for individual patients, although some genetic factors and circulating biomarkers have been associated with different prognoses. Since in its early stages, IPF may be asymptomatic, leading to a delayed diagnosis. Two drugs, pirfenidone and nintedanib, have been shown to modify the disease course by slowing down the decline in lung function. It is also known that 5–10% of the IPF patients may be affected by episodes of acute and often fatal decline. The acute worsening of disease is sometimes attributed to identifiable conditions, such as pneumonia or heart failure; but many of these events occur without an identifiable cause. These idiopathic acute worsenings are termed acute exacerbations of IPF. To date, clinical biomarkers, diagnostic, prognostic, and theranostic, are not well characterized. However, they could become useful tools helping facilitate diagnoses, monitoring disease progression and treatment efficacy. The aim of this review is to cover molecular mechanisms underlying IPF and research into new clinical biomarkers, to be utilized in diagnosis and prognosis, even in patients treated with antifibrotic drugs. 相似文献
119.
Paolo Costa Matteo Cesana Stefano Brambilla Luca Casartelli 《Pervasive and Mobile Computing》2009,5(5):526-541
The choice of the transmission power levels adopted in Wireless Sensor Networks (WSNs) is critical to determine the performance of the network itself in terms of energy efficiency, connectivity and spatial reuse, since it has direct impact on the physical network topology.In this paper, a cooperative, lightweight and fully distributed approach is introduced to adaptively tune the transmission power of sensors in order to match local connectivity constraints. To accurately evaluate the topology control solution, a small-scale testbed based on MicaZ sensor nodes is deployed in indoor and outdoor scenarios. Practical measures on local and multi-hop connectivity, convergence time and emitted power are used to compare the proposed approach against previous solutions. Moreover, mathematical programming formulations of the topology (power) control problem are introduced to assess the optimality of the distributed algorithm. Finally, simulation analysis complements the experimental evaluation in large-scale static and mobile WSN scenarios, where a testbed implementation becomes unfeasible. 相似文献
120.