Performance analysis of optimal channel estimation and multiuser detection in a randomly-spread CDMA channel

<正> This paper analyzes performance of optimal channel estimation and multiuser detection(MUD) in a block-fading code-division multiple-access (CDMA) channel on the assumptions of randomspreading and large-system limit,by using the replica method developed in statistical mechanics.The authors find that the asymptotic spectral efficiency of the linear minimum mean-squared error(LMMSE) MUD which was proposed and analyzed by Evans and Tse in 2000 is indistinguishable fromthat of the optimal MUD for small system loads.Our results imply that performance of MUD scarcelyimproves even if one spends more computational cost than that of the LMMSE MUD,i.e.,at most thecube of the number of users,on the above-described conditions.     

Perfluoroalkyl substances in the blood samples from a male population of Sweden

Temporal trends of perfluoroalkyl substances （PFASs） have been determined in the blood samples from several countries globally including a female population in Sweden recently, yet little is known about the time trends in the blood levels of these compounds in Swedish male populations over recent years. In this study, the fourteen target PFASs consisted of four perfluorosulfonates （PFSAs） and ten perfluorocarboxylates （PFCAs） in the whole blood samples, collected from 153 Swedish elderly men during the period between 2008 and 2010, were analyzed via ultra-performance liquid chromatography-tandem mass spectrometry （UPLC-MS/MS）. As the dominant PFASs contaminants in the blood samples, perfluorooctane sulfo- nate （PFOS） showed the highest geometric mean （GM） at 8.5 ng/mL, ranging from 1.7 to 29 ng/mL, while blood perfluorooctanoic acid （PFOA） contained the GM of 1.8 ng/mL, ranging from 0.35 to 6.4 ng/mL. Both the levels of these two compounds were lower than those determined in the blood samples of Swedish elderly pop- ulations derived from the late 1990s. According to the temporal trend analysis, over the three years, the blood levels of PFOS in Swedish male populations declined 16 % per annum, while those of perfluoroundecanoic acid （PFUnDA） increased 6.1% per annum, which were con- sistent with those reported previously for the populations from other countries.     

Death of mature T cells by separate ligation of CD4 and the T-cell receptor for antigen

Effector T cells are restricted to recognizing antigens associated with major histocompatibility complex (MHC) molecules. Specific recognition is mediated by the alpha beta heterodimer of the T-cell receptor (TCR)/CD3 complex, although other membrane components are involved in T-cell antigen recognition and functions. There has been much controversy in this regard over the part played by the CD4 glycoprotein. It is known that expression of CD4 correlates closely with the cell's ability to recognize antigens bound to class II MHC molecules and that CD4 can bind to class II molecules. Also monoclonal antibodies to CD4 can modify signals generated through the TCR/CD3 complex. It has therefore been proposed that CD4 binds to class II molecules, coaggregates with the TCR-CD3 complex and aids the activation of T cells. But given that TCR can itself impart restriction on the cell, it remains unclear whether the contribution of CD4-derived signals to those generated through the TCR alpha beta-CD3 complex is central to this activation. Here we report that when preceded by ligation of CD4, signalling through TCR alpha beta results in T cell unresponsiveness due to the induction of activation dependent cell death by apoptosis. These results imply that CD4 is critically involved in determining the outcome of signals generated through TCR, and could explain why the induction of effector T cells needs to be MHC-restricted.     

Possible involvement of indolamines in the glycogenic effect of the convulsant methionine sulfoximine in rat brain.

The aim of the present investigation was to look for the mechanisms causing disturbances in carbohydrate metabolism during the action of the epileptogenic agent methionine sulfoximine. The levels of glucose, glycogen, and indolamines were measured in seven different regions of rat brain. Methionine sulfoximine induced a decrease in serotonin level which was roughly dose-dependent. There were no obvious changes in tryptophan and 5-hydroxyindoleacetic levels in any area. Methionine sulfoximine induced the known increase in glucose and glycogen levels. The direct precursor of serotonin. 5-hydroxytryptophan, and benserazide (a decarboxylase inhibitor) were then injected into rats in association with methionine sulfoximine. In this case, methionine sulfoximine failed to induce seizures. Moreover, the serotonin level was unchanged and the carbohydrate content did not significantly increase. There was only a rise in 5-hydroxyindoleacetic acid level. This work shows a striking parallelism between serotonin decrease and glycogen increase.     

Introduction: integrins, dynamic cell receptors

Integrins are a family of adhesive receptors consisting of α- and β-subunits which attach cells together via adhesive protein ligands or bind cells to extracellular matrix. They are found on virtually all cell types and link the external ligand to the cytoskeleton of the cell. Integrins also act as signal transducers both from the outside of the cell to the interior and also inside-out. Their main functions are in recognition and in tight but regulated binding. The series of reviews presented here cover both basic aspects of integrin function, including signal transduction, snake disintegrins and structure and function of I-domains in some integrin α-subunits, as well as the role of integrins in diseases, cancer, inflammation and cardiovascular diseases. The search for suitable inhibitors of integrins for treatment of these diseases and future prospects for their use are also discussed.     

Cytoadherence of knobless Plasmodium falciparum-infected erythrocytes and its inhibition by a human monoclonal antibody

Red blood cells infected with mature stages of the malaria parasite Plasmodium falciparum bind to the endothelial lining of capillaries and venules. This sequestration is important for the survival of the parasite but may have severe consequences for the host. For example, it is involved in the causation of cerebral malaria which carries 25% mortality. Knob-like protrusions present on the surface of infected erythrocytes have been considered necessary but not sufficient for this cytoadherence. Here we describe the adhesion to endothelial cells of infected erythrocytes which do not have knobs. A human monoclonal antibody (33G2) which was specific for an epitope containing regularly spaced dimers of glutamic acid present in the repeated amino-acid sequences of some defined P. falciparum antigens was found to inhibit cyto-adherence and may therefore be an important reagent for elucidating the molecular basis of parasite sequestration.     

Facilitation of voltage-gated ion channels in frog neuroglia by nerve impulses

The functions of glial cells in the nervous system are not well defined, with the exception of myelin production by oligodendrocytes, uptake of amino-acid synaptic transmitters, and a contribution to extracellular potassium homeostasis. Neuroglia have receptors for neurotransmitters which may be involved in neuron-glia interactions. Recent studies have demonstrated voltage-gated ion channels in glial membranes. In a study of the optic nerve of the frog, small areas of the surface were examined with the loose patch-clamp method, and voltage-gated Na+ and K+ channels, presumably located in the membranes of the astrocytes forming the glia limitans, were identified. We now report that nerve impulses in the axons of the frog optic nerve transiently alter the properties of the voltage-dependent membrane channels of the surface glial cells (astrocytes), a demonstration of a new form of neuron-glia interaction.