6,237 research outputs found
The wind tunnels of the national full-scale aerodynamics complex
A brief overview is given of the National Full-scale Aerodynamics Complex. Its geometry, design, construction and testing conditions and models are examined
Anion transporter: highly cell-type-specific expression of distinct polypeptides and transcripts in erythroid and nonerythroid cells
Affinity-purified antibodies and cDNA probes specific for the chicken erythrocyte anion transporter (also referred to as band 3) have been used to demonstrate that this protein is expressed in a highly cell- type-specific manner in the avian kidney. Indirect immunofluorescence analysis indicates that this polypeptide is present in only a small subset of total kidney cells and is predominantly localized to the proximal convoluted tubule of this organ. Chicken erythrocytes synthesize and accumulate two structurally and serologically related band 3 polypeptides. The polypeptide that accumulates in kidney membranes has an apparent molecular weight greater than either of its erythroid counterparts. This diversity is also reflected at the RNA level, as the single band 3 mRNA species detected during various stages of erythroid development is distinct in size from that found in kidney cells. Genomic DNA blot analysis suggests that both the erythroid and kidney band 3 RNAs arise from a single gene. Furthermore, of the adult tissues we have examined that are known to express ankyrin and spectrin polypeptides, only kidney accumulates detectable levels of the band 3 mRNA and polypeptide. These observations suggest that a subset of kidney cells use an anion transport mechanism analogous to that of erythrocytes and that band 3 is expressed in a noncoordinate manner with other components of the erythroid membrane skeleton in nonerythroid cells
Tissue-specific Expression of Distinct Spectrin and Ankyrin Transcripts in Erythroid and Nonerythroid Cells
cDNA probes for three components of the erythroid membrane skeleton, α spectrin, β spectrin, and ankyrin, were obtained by using monospecific antibodies to screen a λgt11 expression vector library containing cDNA prepared from chicken erythroid poly(A)^+ RNA. Each cDNA appears to hybridize to one gene type in the chicken genome. Qualitatively distinct RNA species in myogenic and erythroid cells are detected for β spectrin and ankyrin, while α spectrin exists as a single species of transcript in all tissues examined. This tissue-specific expression of RNAs is regulated quantitatively during myogenesis in vitro, since all three accumulate only upon myoblast fusion. Furthermore, RNAs for two of the three genes do not accumulate to detectable levels in chicken embryo fibroblasts, demonstrating that their accumulation can be noncoordinate. These observations suggest that independent gene regulation and tissue-specific production of heterogeneous transcripts from the β spectrin and ankyrin genes underlie the formation of distinct membrane skeletons in erythroid and muscle cells
Immune Suppression in Auto-Immune Hemolytic Anemia
The acquired auto-immune hemolytic anemias represent a diversity of disease states in which the most constant immunologic finding is a positive direct anti-human globulin test (van Loghem, 1965; Swisher et al, 1965). This is true of the symptomatic variety of acquired hemolytic anemia as well as the idiopathic form. The positive Coomb\u27s test has been seen in association with primary atypical pneumonias, occasionally in favism, in some bacterial and drug induced hemolytic anemias, in patients with malignancies of the lymphoid tissues, and in collagen-vascular disorders--chiefly SLE
Dangerous Territoriality of American Securities Law: A Proposal for an Integrated Global Securities Market, The
Market participants, academicians, and governmental officials debated how the United States government should structure multiple securities exchanges for several years before Congress mandated the establishment of the National Market System in the 1975 Amendments to the Securities Exchange Act of 1934. During the intervening twenty-five years, recurring issues concerning the transparency, fragmentation, and fairness of the National Market System have remained unresolved. Recently, the globalization of securities markets and the development of Internet technology that permits cost-effective transnational securities trades and markets have exacerbated these issues. In fact, Internet technology makes the development of an integrated global securities market not only feasible, but optimal. This essay reviews the SEC\u27s approach to the National Market System with an emphasis on developments since the advent of the Cyber-age. The review shows that, despite technological developments that have propelled markets towards globalization, the SEC has taken a distinctly territorial approach in creating a safe harborf rom registrationf or foreign stock ex-changes that utilize the Internet. At present, the SEC is considering the conditions under which such a foreign exchange must register. This essay argues that the SEC should focus more on the systems architecture offoreign securities exchanges and less on its present territorial approach. While maintaining the National Market System and the existing safe harbor, this essay argues that market participants should apply for, and the SEC should consider, granting registration to an Internet-based securities market. The SEC should not base this grant of registration upon the geographic locus of the exchange, or of its members or issuers. Rather, the SEC should grant the registration upon a showing that the exchange\u27s systems architecturefu rthers the objectives of thef ederal securities laws. The proposed integrated global securities market ( IGSM ) would serve as a SRO/exchange that would accept listings from an issuer as long as the issuer meets the disclosure requirements of its home jurisdiction. An issuer listed on the IGSM could not be traded on another exchange, unless that exchange participated in the price/time priority order book of the IGSM. This condition would resolve many of the difficulties that have plagued the National Market System. The IGSM proposal takes account of considerations of regulatory competition because: (1) the price of an issuer\u27s shares traded on the IGSM would reflect the issuer\u27s home country standard of disclosure; (2) the IGSM would compete for listings against other exchanges with higher or lower mandatory levels of disclosure, including those in the National Market System; and (3) the IGSM prevents the listing of an issuer from a strict regulatory regime being traded on an exchange from a lax regulatory regime, i.e., regulatory free-ridin
Dangerous Territoriality of American Securities Law: A Proposal for an Integrated Global Securities Market, The
Market participants, academicians, and governmental officials debated how the United States government should structure multiple securities exchanges for several years before Congress mandated the establishment of the National Market System in the 1975 Amendments to the Securities Exchange Act of 1934. During the intervening twenty-five years, recurring issues concerning the transparency, fragmentation, and fairness of the National Market System have remained unresolved. Recently, the globalization of securities markets and the development of Internet technology that permits cost-effective transnational securities trades and markets have exacerbated these issues. In fact, Internet technology makes the development of an integrated global securities market not only feasible, but optimal. This essay reviews the SEC\u27s approach to the National Market System with an emphasis on developments since the advent of the Cyber-age. The review shows that, despite technological developments that have propelled markets towards globalization, the SEC has taken a distinctly territorial approach in creating a safe harborf rom registrationf or foreign stock ex-changes that utilize the Internet. At present, the SEC is considering the conditions under which such a foreign exchange must register. This essay argues that the SEC should focus more on the systems architecture offoreign securities exchanges and less on its present territorial approach. While maintaining the National Market System and the existing safe harbor, this essay argues that market participants should apply for, and the SEC should consider, granting registration to an Internet-based securities market. The SEC should not base this grant of registration upon the geographic locus of the exchange, or of its members or issuers. Rather, the SEC should grant the registration upon a showing that the exchange\u27s systems architecturefu rthers the objectives of thef ederal securities laws. The proposed integrated global securities market ( IGSM ) would serve as a SRO/exchange that would accept listings from an issuer as long as the issuer meets the disclosure requirements of its home jurisdiction. An issuer listed on the IGSM could not be traded on another exchange, unless that exchange participated in the price/time priority order book of the IGSM. This condition would resolve many of the difficulties that have plagued the National Market System. The IGSM proposal takes account of considerations of regulatory competition because: (1) the price of an issuer\u27s shares traded on the IGSM would reflect the issuer\u27s home country standard of disclosure; (2) the IGSM would compete for listings against other exchanges with higher or lower mandatory levels of disclosure, including those in the National Market System; and (3) the IGSM prevents the listing of an issuer from a strict regulatory regime being traded on an exchange from a lax regulatory regime, i.e., regulatory free-ridin
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