A performance evaluation of commercial fibrinogen reference preparations and assays for Clauss and PT-derived fibrinogen

The wide availability of fibrinogen estimations based on the prothrombin time (PT-Fg) has caused concern about the variability and clinical utility of fibrinogen assays. In a multi-centre study, we investigated fibrinogen assays using various reagents and analysers, Clauss assays generally gave good agreement, although one reagent gave 15-30% higher values in DIC and thrombolysis. Two commercial reference preparations had much lower potencies than the manufacturers declared, and plasma turbidity influenced parallelism in some Clauss assays, PT-Fg assays gave higher values than Clauss and showed calibrant dependent effects, the degree of disparity correlating with calibrant and test sample turbidity. Analyser and thromboplastin dependent differences were noted. The relationship between Clauss and PT-Fg assays was sigmoid, and the plateau of maximal PT-Fg differed by about 2 g/l between reagents. ELISA and immunonephelometric assays correlated well, but with a high degree of scatter. Antigen levels were higher than Clauss, but slightly lower than PT-Fg assays, which appeared to be influenced by degraded fibrinogen. Clauss assays are generally reproducible between centres, analysers and reagents, but PT-Fg assays are not reliable in clinical settings

An Easily Constructed, Tuning Free, Ultra-broadband Probe for NMR

We have developed an easy to construct, non-resonant wideband NMR probe. The probe is of the saddle coil geometry and is designed such that the coil itself forms a transmission line. The probe thus requires no tuning or matching elements. We use the probe with a spectrometer whose duplexer circuitry employs a simple RF switch instead of the more common lambda/4 lines, so the entire probe and spectrometer perform in an essentially frequency-independent manner. Despite being designed with electro- and magnetostatic formulas, the probe performs well at frequencies up to 150 MHz and beyond. We expect that with additional design effort, the probe could be modified for use at significantly higher frequencies. Because our construction method relies on commercial circuit fabrication techniques, identical probes can be easily and accurately produced

Structure of the regulatory hyaluronan binding domain in the inflammatory leukocyte homing receptor CD44

Adhesive interactions involving CD44, the cell surface receptor for hyaluronan, underlie fundamental processes such as inflammatory leukocyte homing and tumor metastasis. Regulation of such events is critical and appears to be effected by changes in CD44 N-glycosylation that switch the receptor "on" or "off" under appropriate circumstances. How altered glycosylation influences binding of hyaluronan to the lectin-like Link module in CD44 is unclear, although evidence suggests additional flanking sequences peculiar to CD44 may be involved. Here we show using X-ray crystallography and NMR spectroscopy that these sequences form a lobular extension to the Link module, creating an enlarged HA binding domain and a formerly unidentified protein fold. Moreover, the disposition of key N-glycosylation sites reveals how specific sugar chains could alter both the affinity and avidity of CD44 HA binding. Our results provide the necessary structural framework for understanding the diverse functions of CD44 and developing novel therapeutic strategies

Propagation of Ultrasonic Waves in Liquid Mixtures and Intermolecular Forces II

The electronic properties of clean and sulfur-terminated surfaces of InSb(001) and (111) B are investigated using x-ray photoemission spectroscopy and high-resolution electron energy loss spectroscopy. The clean surfaces exhibit upward band bending (electron depletion) consistent with the charge neutrality level in InSb lying at the valence band maximum. The surface Fermi level to valence band maximum separation is increased for the S terminated compared with the clean surface, leading to flat bands and downward band bending (electron accumulation) for the (001) and (111) B surfaces, respectively. This is discussed in terms of compensation of native acceptor surface states. (C) 2008 American Institute of Physics. [DOI: 10.1063/1.3000567

Mangarara Formation: exhumed remnants of a middle Miocene, temperate carbonate, submarine channel-fan system on the eastern margin of Taranaki Basin, New Zealand

The middle Miocene Mangarara Formation is a thin (1–60 m), laterally discontinuous unit of moderately to highly calcareous (40–90%) facies of sandy to pure limestone, bioclastic sandstone, and conglomerate that crops out in a few valleys in North Taranaki across the transition from King Country Basin into offshore Taranaki Basin. The unit occurs within hemipelagic (slope) mudstone of Manganui Formation, is stratigraphically associated with redeposited sandstone of Moki Formation, and is overlain by redeposited volcaniclastic sandstone of Mohakatino Formation. The calcareous facies of the Mangarara Formation are interpreted to be mainly mass-emplaced deposits having channelised and sheet-like geometries, sedimentary structures supportive of redeposition, mixed environment fossil associations, and stratigraphic enclosure within bathyal mudrocks and flysch. The carbonate component of the deposits consists mainly of bivalves, larger benthic foraminifers (especially Amphistegina), coralline red algae including rhodoliths (Lithothamnion and Mesophyllum), and bryozoans, a warm-temperate, shallow marine skeletal association. While sediment derivation was partly from an eastern contemporary shelf, the bulk of the skeletal carbonate is inferred to have been sourced from shoal carbonate factories around and upon isolated basement highs (Patea-Tongaporutu High) to the south. The Mangarara sediments were redeposited within slope gullies and broad open submarine channels and lobes in the vicinity of the channel-lobe transition zone of a submarine fan system. Different phases of sediment transport and deposition (lateral-accretion and aggradation stages) are identified in the channel infilling. Dual fan systems likely co-existed, one dominating and predominantly siliciclastic in nature (Moki Formation), and the other infrequent and involving the temperate calcareous deposits of Mangarara Formation. The Mangarara Formation is an outcrop analogue for middle Miocene-age carbonate slope-fan deposits elsewhere in subsurface Taranaki Basin, New Zealand

Poissonian communications : free space optical data transfer at the few-photon level

Communicating information at the few photon level typically requires some complexity in the transmitter or receiver in order to operate in the presence of noise. This in turn incurs expense in the necessary spatial volume and power consumption of the system. In this work we present a self-synchronised free-space optical communications system based on simple, compact and low power consumption semiconductor devices. A temporal encoding method, implemented using a gallium nitride micro-LED source and a silicon single photon avalanche photo-detector (SPAD) demonstrates data transmission at rates up to 100 kb/s for 8.25 pW received power, corresponding to 27 photons per bit. Furthermore, the signals can be decoded in the presence of both constant and modulated background noise at levels significantly exceeding the signal power. The systems low power consumption and modest electronics requirements are demonstrated employing it as a communications channel between two nano-satellite simulator systems

Unexpected patterns of Epstein-Barr virus transcription revealed by a High throughput PCR array for absolute quantification of viral mRNA

We have validated a flexible, high-throughput and relatively inexpensive RT-QPCR array platform for absolute quantification of Epstein–Barr virus transcripts in different latent and lytic infection states. Several novel observations are reported. First, during infection of normal B cells, Wp-initiated latent gene transcripts remain far more abundant following activation of the Cp promoter than was hitherto suspected. Second, EBNA1 transcript levels are remarkably low in all forms of latency, typically ranging from 1 to 10 transcripts per cell. EBNA3A, -3B and -3C transcripts are likewise very low in Latency III, typically at levels similar to or less than EBNA1 transcripts. Thirdly, a subset of lytic gene transcripts is detectable in Burkitt lymphoma lines at low levels, including: BILF1, which has oncogenic properties, and the poorly characterized LF1, LF2 and LF3 genes. Analysis of seven African BL biopsies confirmed this transcription profile but additionally revealed significant expression of LMP2 transcripts

Towards using LED arrays for relative alignment of cube satellite clusters

A structured illumination system based on microscale light-emitting diode arrays provides a low size, mass and power approach to monitor the relative angular alignment of nano-satellites operating in cluster configuration

Initial State Interactions for K−K^--Proton Radiative Capture

The effects of the initial state interactions on the $K^--p$ radiative capture branching ratios are examined and found to be quite sizable. A general coupled-channel formalism for both strong and electromagnetic channels using a particle basis is presented, and applied to all the low energy $K^--p$ data with the exception of the {\it 1s} atomic level shift. Satisfactory fits are obtained using vertex coupling constants for the electromagnetic channels that are close to their expected SU(3) values.Comment: 16 pages, uses revte