现有防疫通风措施及基于先进气流组织的源头控制技术应用

新冠疫情暴发后,如何应对呼吸道传染病的传播这一难题再次摆在了人们面前.通风是最重要的工程防疫措施,ASHRAE、REHVA、SHASE以及中国的相关机构、学会就如何利用暖通空调系统有效防控COVID-19的传播相继出台了指导性文件.总结和分析系列指导性文件中有关通风量和气流组织方面的内容,发现现有工程防疫措施尚存在诸多...     

Radiation hybrid map of the mouse genome.

Radiation hybrid (RH) maps are a useful tool for genome analysis, providing a direct method for localizing genes and anchoring physical maps and genomic sequence along chromosomes. The construction of a comprehensive RH map for the human genome has resulted in gene maps reflecting the location of more than 30,000 human genes. Here we report the first comprehensive RH map of the mouse genome. The map contains 2,486 loci screened against an RH panel of 93 cell lines. Most loci (93%) are simple sequence length polymorphisms (SSLPs) taken from the mouse genetic map, thereby providing direct integration between these two key maps. We performed RH mapping by a new and efficient approach in which we replaced traditional gel- or hybridization-based assays by a homogeneous 5'-nuclease assays involving a single common probe for all genetic markers. The map provides essentially complete connectivity and coverage across the genome, and good resolution for ordering loci, with 1 centiRay (cR) corresponding to an average of approximately 100 kb. The RH map, together with an accompanying World-Wide Web server, makes it possible for any investigator to rapidly localize sequences in the mouse genome. Together with the previously constructed genetic map and a YAC-based physical map reported in a companion paper, the fundamental maps required for mouse genomics are now available.     

fMRI evidence for objects as the units of attentional selection.

Contrasting theories of visual attention emphasize selection by spatial location, visual features (such as motion or colour) or whole objects. Here we used functional magnetic resonance imaging (fMRI) to test key predictions of the object-based theory, which proposes that pre-attentive mechanisms segment the visual array into discrete objects, groups, or surfaces, which serve as targets for visual attention. Subjects viewed stimuli consisting of a face transparently superimposed on a house, with one moving and the other stationary. In different conditions, subjects attended to the face, the house or the motion. The magnetic resonance signal from each subject's fusiform face area, parahippocampal place area and area MT/MST provided a measure of the processing of faces, houses and visual motion, respectively. Although all three attributes occupied the same location, attending to one attribute of an object (such as the motion of a moving face) enhanced the neural representation not only of that attribute but also of the other attribute of the same object (for example, the face), compared with attributes of the other object (for example, the house). These results cannot be explained by models in which attention selects locations or features, and provide physiological evidence that whole objects are selected even when only one visual attribute is relevant.     

A radiation hybrid map of the rat genome containing 5,255 markers.

A whole-genome radiation hybrid (RH) panel was used to construct a high-resolution map of the rat genome based on microsatellite and gene markers. These include 3,019 new microsatellite markers described here for the first time and 1,714 microsatellite markers with known genetic locations, allowing comparison and integration of maps from different sources. A robust RH framework map containing 1,030 positions ordered with odds of at least 1,000:1 has been defined as a tool for mapping these markers, and for future RH mapping in the rat. More than 500 genes which have been mapped in mouse and/or human were localized with respect to the rat RH framework, allowing the construction of detailed rat-mouse and rat-human comparative maps and illustrating the power of the RH approach for comparative mapping.     

A single EFEMP1 mutation associated with both Malattia Leventinese and Doyne honeycomb retinal dystrophy.

Malattia Leventinese (ML) and Doyne honeycomb retinal dystrophy (DHRD) refer to two autosomal dominant diseases characterized by yellow-white deposits known as drusen that accumulate beneath the retinal pigment epithelium (RPE). Both loci were mapped to chromosome 2p16-21 (refs 5,6) and this genetic interval has been subsequently narrowed. The importance of these diseases is due in large part to their close phenotypic similarity to age-related macular degeneration (AMD), a disorder with a strong genetic component that accounts for approximately 50% of registered blindness in the Western world. Just as in ML and DHRD, the early hallmark of AMD is the presence of drusen. Here we use a combination of positional and candidate gene methods to identify a single non-conservative mutation (Arg345Trp) in the gene EFEMP1 (for EGF-containing fibrillin-like extracellular matrix protein 1) in all families studied. This change was not present in 477 control individuals or in 494 patients with age-related macular degeneration. Identification of this mutation may aid in the development of an animal model for drusen, as well as in the identification of other genes involved in human macular degeneration.     

Distortion of proximodistal information causes JNK-dependent apoptosis in Drosophila wing.

Distinct and evolutionarily conserved signal-transduction cascades mediate the survival or death of cells during development. The c-Jun amino-terminal kinases (JNKs) of the mitogen-activated protein kinase superfamily are involved in apoptotic signalling in various cultured cells. However, the role of the JNK pathway in development is less well understood. In Drosophila, Decapentaplegic (Dpp; a homologue of transforming growth factor-beta) and Wingless (Wg; a Wnt homologue) proteins are secretory morphogens that act cooperatively to induce formation of the proximodistal axis of appendages. Here we show that either decreased Dpp signalling in the distal wing cells or increased Dpp signalling in the proximal wing cells causes apoptosis. Inappropriate levels of Dpp signalling lead to aberrant morphogenesis in the respective wing zones, and these apoptotic zones are also determined by the strength of the Wg signal. Our results indicate that distortion of the positional information determined by Dpp and Wg signalling gradients leads to activation of the JNK apoptotic pathway, and the consequent induction of cell death thereby maintains normal morphogenesis.     

Integrin cytoplasmic tyrosine motif is required for outside-in alphaIIbbeta3 signalling and platelet function.

Integrins not only bind adhesive ligands, they also act as signalling receptors. Both functions allow the integrin alphaIIbbeta3 to mediate platelet aggregation. Platelet agonists activate alphaIIbbeta3 (inside-out signalling) to allow the binding of soluble fibrinogen. Subsequent platelet aggregation leads to outside-in alphaIIbbeta3 signalling, which results in calcium mobilization, tyrosine phosphorylation of numerous proteins including beta3 itself, increased cytoskeletal reorganisation and further activation of alphaIIbbeta3. Thus, outside-in signals enhance aggregation, although the mechanisms and functional consequences of specific signalling events remain unclear. Here we describe a mouse that expresses an alphaIIbbeta3 in which the tyrosines in the integrin cytoplasmic tyrosine motif have been mutated to phenylalanines. These mice are selectively impaired in outside-in alphaIIbbeta3 signalling, with defective aggregation and clot-retraction responses in vitro, and an in vivo bleeding defect which is characterized by a pronounced tendency to rebleed. These data provide evidence for an important role of outside-in signalling in platelet physiology. Furthermore, they identify the integrin cytoplasmic tyrosine motif as a key mediator of beta-integrin signals and a potential target for new therapeutic agents.     

Structure of Cdc42 in complex with the GTPase-binding domain of the 'Wiskott-Aldrich syndrome' protein.

The Rho-family GTP-hydrolysing proteins (GTPases), Cdc42, Rac and Rho, act as molecular switches in signalling pathways that regulate cytoskeletal architecture, gene expression and progression of the cell cycle. Cdc42 and Rac transmit many signals through GTP-dependent binding to effector proteins containing a Cdc42/Rac-interactive-binding (CRIB) motif. One such effector, the Wiskott-Aldrich syndrome protein (WASP), is postulated to link activation of Cdc42 directly to the rearrangement of actin. Human mutations in WASP cause severe defects in haematopoletic cell function, leading to clinical symptoms of thrombocytopenia, immunodeficiency and eczema. Here we report the solution structure of a complex between activated Cdc42 and a minimal GTPase-binding domain (GBD) from WASP. An extended amino-terminal GBD peptide that includes the CRIB motif contacts the switch I, beta2 and alpha5 regions of Cdc42. A carboxy-terminal beta-hairpin and alpha-helix pack against switch II. The Phe-X-His-X2-His portion of the CRIB motif and the alpha-helix appear to mediate sensitivity to the nucleotide switch through contacts to residues 36-40 of Cdc42. Discrimination between the Rho-family members is likely to be governed by GBD contacts to the switch I and alpha5 regions of the GTPases. Structural and biochemical data suggest that GBD-sequence divergence outside the CRIB motif may reflect additional regulatory interactions with functional domains that are specific to individual effectors.     

基于麦克斯韦电路理论的方环散射体

不同于传统数值计算方法,麦克斯韦电路(MC)理论融合了场的理论和路的理论,使二者高效地结合在一起.运用麦克斯韦电路理论分析方环散射体,研究方环散射体的MC求解方法以及MC的宽带特性,求出其散射电流,数值实验结果与矩量法结果吻合良好.研究还发现,MC可以在一个较宽的频带上得到准确电流解,因此,比其他数值方法更加高效和实用.