Multiple-packet forwarding protocols for frequency-hop packet radio networks

Reliable data distribution within multiple-hop spread-spectrum packet radio networks requires high performance from the network protocols. The high variability in quality among the links and the unique characteristics of frequency-hop spread-spectrum signaling impose special requirements for network protocols that are to be employed in frequency-hop packet radio networks. These features can be exploited in the forwarding protocols by allowing multiple packets to be included in each forwarding attempt. The use of multiple-packet transmissions exploits the capture property of frequency-hop signaling, and it reduces the overhead required for acknowledgments. A potential trade-off arises because the use of multiple-packet transmissions increases the throughput, but in some situations it can also increase the delay. Two new transmission protocols that employ multiple-packet transmissions are described, and their performance is evaluated.     

MRAM:内存的新潮流(上)

Freescale运用自旋电子技术制作了新的非易失性RAM,本文对此进行了详细介绍.     

Research issues in cancer survivorship: report of a workshop sponsored by the Office of Cancer Survivorship, National Cancer Institute

We present the results of a prospective, randomised study comparing PBPC and BM focusing on engraftment, acute and chronic GVHD and survival. Forty patients with haematological malignancies received HLA-identical sibling BM (group A) or PBPC (group B). Evaluable patients were 19 (A) and 18 (B). Median age was 35 (17-56) in A and 29.5 (9-51) in B. Conditioning was mainly Bu-Cy2; GVHD prophylaxis was CSA-MTX. PBPC were harvested after 5 days of G-CSF 10 microg/kg/day. Median days for an ANC >0.5 x 10(9)/l was 18 (13-30) in A and 16 (11-25) in B (P = 0.10). Platelets >20 x 10(9)/l occurred at +17 (10-40) in A and +12 (9-36) in B (P = 0.01). The probability of > or =2 grade a-GVHD was 19% (A) and 27% (B) (P = 0.53). The probability of all grade c-GVHD was 70% with BM. In spite of the small number of patients in group B (PBPC), our data suggest the great majority of them will have c-GVHD (P = 0.08); extensive disease was present in 50 and 100%, respectively (P = 0.05). The estimates of overall survival for A and B at 1000 days are 51 and 47%, respectively (P = 0.67); DFS at 1000 days are 52 and 58%, respectively (P = 0.50). PBPC resulted in faster platelet engraftment. The incidence of acute and chronic GVHD was similar in both groups, but the severity of c-GVHD was higher with PBPC. No differences in survival and DFS have been observed to date.     

Evidence for a requirement for both phospholipid and phosphotyrosine binding via the Shc phosphotyrosine-binding domain in vivo

The adapter protein Shc is a critical component of mitogenic signaling pathways initiated by a number of receptors. Shc can directly bind to several tyrosine-phosphorylated receptors through its phosphotyrosine-binding (PTB) domain, and a role for the PTB domain in phosphotyrosine-mediated signaling has been well documented. The structure of the Shc PTB domain demonstrated a striking homology to the structures of pleckstrin homology domains, which suggested acidic phospholipids as a second ligand for the Shc PTB domain. Here we demonstrate that Shc binding via its PTB domain to acidic phospholipids is as critical as binding to phosphotyrosine for leading to Shc phosphorylation. Through structure-based, targeted mutagenesis of the Shc PTB domain, we first identified the residues within the PTB domain critical for phospholipid binding in vitro. In vivo, the PTB domain was essential for localization of Shc to the membrane, as mutant Shc proteins that failed to interact with phospholipids in vitro also failed to localize to the membrane. We also observed that PTB domain-dependent targeting to the membrane preceded the PTB domain's interaction with the tyrosine-phosphorylated receptor and that both events were essential for tyrosine phosphorylation of Shc following receptor activation. Thus, Shc, through its interaction with two different ligands, is able to accomplish both membrane localization and binding to the activated receptor via a single PTB domain.     

Polymorphic programming II. An orthogonal tagged high level architecture abstract machine

This paper describes the implementation of a very powerful high level language from the standpoint of those features rarely found in other languages. These are constancy, polymorphism, user-defined types, orthogonal data structures, and field selectors and routines as assignable values. It examines the characteristics of these features in order to show how they are implemented. They greatly influence the architecture of the underlying abstract machine which is described. Finally the paper highlights several important instructions such as those for routine calling and data structure management. It also shows how the list as a data type in a language can be exploited in the implementation of assignment and parameter passing.     

X-ray Powder Diffraction Structural Phase-Transition Study of La(Cr1-xMnx)O3 (x = 0 to 0.25) Using the Rietveld Method of Analysis

The La(Cr_1-xMn_x)O₃ (x = 0 to 0.25) system exhibited a displacive phase transformation from an orthorhombic to a rhombohedral structure at temperatures ranging from about 256°C at x = 0 to 305°C at x = 0.25. The Rietveld method of X-ray analysis was used to determine structural characteristics and to assay phase concentrations when multiple phases were present. Indications were that the Mn ions on the B site affected the transition temperature through an ionic size effect; i.e., Mn³⁺, with a larger ionic size than Cr³⁺, increased the transition temperature while the presence of the smaller Mn⁴⁺ ions reduced it. A hysteresis was also observed with respect to the phase transformation as a function of temperature. The phase transformation was associated with a change in the rotation of the oxygen octahedra from an antiphase to an in-phase tilt sequence.     

A protein kinase C agonist, selective for the beta I isozyme, induces E-selectin and VCAM-1 expression on HUVEC but does not translocate PKC

A protein kinase C (PKC) agonist selective for the beta I isozyme, 12-deoxyphorbol 13-phenylacetate 20-acetate (dPPA), induced NF-kappa B-like binding activity and surface expression of E-selectin and VCAM-1 in human umbilical vein endothelial cells (HUVEC), similar to the effects of tumor necrosis factor-alpha (TNF-alpha). Induction of E-selectin and VCAM-1 expression by dPPA was completely inhibited by the PKC inhibitors staurosporine and Ro31-7549. The PKC inhibitors also reduce TNF-alpha-induced VCAM-1 expression. However, neither dPPA nor TNF-alpha translocated PKC from the cytosolic to the plasma or nuclear membrane particulate fractions in HUVEC. These results indicate that activation of the beta I PKC isozyme is sufficient for expression of E-selectin and VCAM-1, and suggest that PKC may mediate the effects of TNF-alpha and dPPA without requiring the translocation normally associated with activation of PKC.     

An Open-Loop Computer-Based Drug Infusion System

This study reports the development of a computer-based infusion system and methodology to produce and maintain selected plasma concentrations. The method identifies pharmacokinetic infusion parameters for subjects from bolus injection response data, employs these values in control equations implemented by a portable microcomputer and computer-controlled infusion pump, and achieves and maintains selected stepwise drug levels by intravenous drug infusion. Infusion studies with four dogs and five humans resulted in correlation coefficients of 0.98 for the dogs and 0.94 for the humans, with rms errors in maintaining the drug concentration at the desired level of 13.4 and 19.3 percent, respectively. An analysis of error demonstrated that: 1) the control error was less than the value of the pharmacokinetic parameter estimation error in determining a single parameter value, 2) errors in several parameters can have cancelling or additive effects depending on their sign, and 3) an error in the sum of two of the model parameters (A and B) directly translates to equivalent time-independent error in the controlled level.     

Determination of the molecular weight distribution of polyisoprene by random scission

cis-Polyisoprene in dilute solution in toluene (plus antioxidant) undergoes random scission when exposed to γ-radiation. The possibility of using this scission in a method to assess the width of the molecular weight distribution of the polymer has been explored and found potentially useful in situations where conventional methods provide little information.