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Achieving efficient and fair bandwidth allocation while minimizing packet loss and bottleneck queue in high bandwidth-delay product networks has long been a daunting challenge. Existing end-to-end congestion control (e.g., TCP) and traditional congestion notification schemes (e.g., TCP+AQM/ECN) have significant limitations in achieving this goal. While the XCP protocol addresses this challenge, it requires multiple bits to encode the congestion-related information exchanged between routers and end-hosts. Unfortunately, there is no space in the IP header for these bits, and solving this problem involves a non-trivial and time-consuming standardization process. In this paper, we design and implement a simple, low-complexity protocol, called variable-structure congestion control protocol (VCP), that leverages only the existing two ECN bits for network congestion feedback, and yet achieves comparable performance to XCP, i.e., high utilization, negligible packet loss rate, low persistent queue length, and reasonable fairness. On the downside, VCP converges significantly slower to a fair allocation than XCP. We evaluate the performance of VCP using extensive ns2 simulations over a wide range of network scenarios and find that it significantly outperforms many recently-proposed TCP variants, such as HSTCP, FAST, CUBIC, etc. To gain insight into the behavior of VCP, we analyze a simplified fluid model and prove its global stability for the case of a single bottleneck shared by synchronous flows with identical round-trip times.
Scaling the Li-ion industry to multiple TWh/year will be challenging with NMC-class cathodes because of the cost and resource constraints arising from the use of nickel and/or cobalt. Disordered rocksalt cathodes DRX can be synthesized with almost any transition metal and offer a likely alternative to replace Ni-containing layered cathode materials. Since their invention in 2014 understanding and performance improvement of DRX materials has made significant progress. Materials based on Mn and Ti, which can be synthesized from inexpensive precursors, have shown that specific energies between 650 to 850Wh/kg can be maintained during extended cycling. The ability of these materials to substitute some O by F also provides them with excellent stability even up to high voltage. Since they lose little or no oxygen when highly charged, they are also like to provide high safety. Rate capability, which early on posed a problem for DRX cathodes, has been improved through multiple strategies, and 200mA/g and higher rates can now be achieved without substantial capacity loss. Because these compounds can be synthesized from standard Mn-oxide and Ti-oxide precursors they have the potential to be a low-cost, resource abundant alternative to NMC class materials.
Recent extraordinary advances in cancer immunotherapy rely primarily on marshaling T cell responses. Here we discuss how NK cell responses can be amplified. We find that MHC I-deficient tumors induce anergy of NK cells but that cytokine therapy restores NK cell activity and increases the survival of mice bearing MHC I-deficient tumors.
This dissertation describes work in the field of computational biology. We present three results on algorithms for comparing strings with applications for DNA and protein sequence analysis. We also describe the first application of machine learning to the problem of predicting the cellular localization sites of proteins from their sequences.
An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
The objectives of this project have been twofold: (1) to develop a theoretical model for designing bubble-column reactors and assessing their performance and (2) to characterize the performance of a laboratory-scale bubble-column reactor. The theoretical part of the project has focused the effects of gas-liquid mass transfer; axial dispersion of gas, liquid, and catalyst; ad the interplay between the kinetics of Fischer-Tropsch synthesis and the water-gas-shift reaction. The experimental portion of the project has focused the effects of reaction conditions on product distribution and, in particular, the conditions under which gas-liquid mass transfer becomes important. Any independent set of experiments was undertaken to investigate the chemistry of carbonaceous deposits formed during Fischer-Tropsch synthesis. 8 refs.
Research Article| March 01, 2009 Age constraints on alleged "footprints" preserved in the Xalnene Tuff near Puebla, Mexico Joshua M. Feinberg; Joshua M. Feinberg * 11Institute for Rock Magnetism, Department of Geology and Geophysics, University of Minnesota, 310 Pillsbury Drive SE, Minneapolis, Minnesota 55455, USA *E-mail: feinberg@umn.edu. Search for other works by this author on: GSW Google Scholar Paul R. Renne; Paul R. Renne 22Berkeley Geochronology Center, 2455 Ridge Road, Berkeley, California 94709, USA 33University of California–Berkeley, Department of Earth and Planetary Science, 340 McCone Hall, Berkeley, California 94720, USA Search for other works by this author on: GSW Google Scholar Joaquin Arroyo-Cabrales; Joaquin Arroyo-Cabrales 44Laboratorio de Arqueozoología, Subdirección de Laboratorios y Apoyo Académico, Instituto Nacional de Antropología e Historia, 06060 México, D.F. Mexico Search for other works by this author on: GSW Google Scholar Michael R. Waters; Michael R. Waters 55Center for the Study of the First Americans, Departments of Anthropology and Geography, Texas A&M University, College Station, Texas 77843–4352, USA Search for other works by this author on: GSW Google Scholar Patricia Ochoa-Castillo; Patricia Ochoa-Castillo 66Subdirección de Arqueología, Museo Nacional de Antropología, Reforma y Gandhi s/n, CP 11560, México, D.F. Mexico Search for other works by this author on: GSW Google Scholar Mario Perez-Campa Mario Perez-Campa 77Secretariá Técnica, Instituto Nacional de Antropología e Historia, 06700, México, D.F. Mexico Search for other works by this author on: GSW Google Scholar Geology (2009) 37 (3): 267–270. https://doi.org/10.1130/G24913A.1 Article history received: 06 Mar 2008 rev-recd: 27 Oct 2008 accepted: 06 Nov 2008 first online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Joshua M. Feinberg, Paul R. Renne, Joaquin Arroyo-Cabrales, Michael R. Waters, Patricia Ochoa-Castillo, Mario Perez-Campa; Age constraints on alleged "footprints" preserved in the Xalnene Tuff near Puebla, Mexico. Geology 2009;; 37 (3): 267–270. doi: https://doi.org/10.1130/G24913A.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract Impressions in a basaltic tuff located around Valsequillo Reservoir near Puebla, Mexico, have been interpreted as human and animal footprints along an ancient lakeshore, and are cited as evidence of the presence of humans in North America at 40 ka B.P. In this paper, we present new data that challenge this interpretation. Paleomagnetic analyses of the Xalnene Tuff, and lavas from the volcano from which it erupted, yield fully reversed magnetic polarities, indicating that the tuff was deposited prior to the last geomagnetic reversal (the Brunhes-Matuyama ca. 790 ka). 40Ar/39Ar dating of Xalnene lapilli and lava from the source volcano yields indistinguishable ages of ~1.3 Ma, consistent with a period of reversed magnetic polarity (C1r.2r). Additional paleomagnetic measurements of individual millimeter-size lapilli indicate that the pyroclastic grains within the Xalnene Tuff have not been disturbed or rotated since their initial deposition, thereby ruling out the possibility that the tuff was reworked by wave action along the shores of an ancient lacustrine environment. This and other evidence indicate that the marks observed in the stone quarry site are not human ichnofossils. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.
Metal ion cofactors are necessary for prenyltransferase enzymes. Magnesium and manganese can be used as metal ion cofactor by rubber transferase (a cis-prenyltransferase) associated with purified rubber particles. The rubber initiation rate, biosynthetic rate, and molecular weight produced in vitro from Hevea brasiliensis rubber transferase is regulated by metal ion concentration. In addition, varies significantly with [Mg(2+)]. decreases from 8000 +/- 600 microM at [Mg(2+)] = 4 mM to 68 +/- 10 microM at [Mg(2+)] = 8 mM and increases back to 970 +/- 70 microM at [Mg(2+)] = 30 mM. The highest affinity of rubber transferase for IPP.Mg occurred when [Mg(2+)] = A(max) (metal concentration that gives highest IPP incorporation rate). A metal ion is required for rubber biosynthesis, but an excess of metal ions interacts with the rubber transferase inhibiting its activity. The results suggest that H. brasiliensis could use [Mg(2+)] as a regulatory mechanism for rubber biosynthesis and molecular weight in vivo.
