24,571 research outputs found
Induction of donor-specific transplantation tolerance to skin and cardiac allografts using mixed chimerism in (A + B → A) in rats
Mixed allogeneic chimerism (A + B → A) was induced in rats by reconstitution of lethally irradiated LEW recipients with a mixture of T-cell depleted (TCD) syngeneic and TCD allogeneic ACI bone marrow. Thirty-seven percent of animals repopulated as stable mixed lymphopoietic chimeras, while the remainder had no detectable allogeneic chimerism. When evaluated for evidence of donor-specific transplantation tolerance, only those recipients with detectable allogeneic lymphoid chimerism exhibited acceptance of donor-specific skin and cardiac allografts. Despite transplantation over a major histocompatibility complex (MHC)- and minor-disparate barrier, animals accepted donor-specific ACI skin and primarily vascularized cardiac allografts permanently, while rejecting third party Brown Norway (BN) grafts. The tolerance induced was also donor-specific in vitro as evidenced by specific hyporeactivity to the allogeneic donor lymphoid elements, yet normal reactivity to MHC-disparate third party rat lymphoid cells. This model for mixed chimerism in the rat will be advantageous to investigate specific transplantation tolerance to primarily vascularized solid organ grafts that can be performed with relative ease in the rat, but not in the mouse, and may provide a method to study the potential existence of organ- or tissue-specific alloantigens in primarily vascularized solid organ allografts. © 1993
Technology innovation truly international? Evidence of comparative study on index of patent internationalization, 1981-2008
Shortcuts through Colocation Facilities
Network overlays, running on top of the existing Internet substrate, are of
perennial value to Internet end-users in the context of, e.g., real-time
applications. Such overlays can employ traffic relays to yield path latencies
lower than the direct paths, a phenomenon known as Triangle Inequality
Violation (TIV). Past studies identify the opportunities of reducing latency
using TIVs. However, they do not investigate the gains of strategically
selecting relays in Colocation Facilities (Colos). In this work, we answer the
following questions: (i) how Colo-hosted relays compare with other relays as
well as with the direct Internet, in terms of latency (RTT) reductions; (ii)
what are the best locations for placing the relays to yield these reductions.
To this end, we conduct a large-scale one-month measurement of inter-domain
paths between RIPE Atlas (RA) nodes as endpoints, located at eyeball networks.
We employ as relays Planetlab nodes, other RA nodes, and machines in Colos. We
examine the RTTs of the overlay paths obtained via the selected relays, as well
as the direct paths. We find that Colo-based relays perform the best and can
achieve latency reductions against direct paths, ranging from a few to 100s of
milliseconds, in 76% of the total cases; 75% (58% of total cases) of these
reductions require only 10 relays in 6 large Colos.Comment: In Proceedings of the ACM Internet Measurement Conference (IMC '17),
London, GB, 201
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