Anti-platelet therapy: ADP receptor antagonists.

The P2Y(12) receptor on platelets with which ADP interacts has an important role in promoting platelet function and thereby platelet involvement in both haemostasis and thrombosis. Agents that act as antagonists at this receptor are thus likely to provide effective antithrombotic therapy, provided that there are no adverse effects on haemostasis. Here we describe the ADP receptor antagonists that are available and in development. We also consider their mode of action and ask whether there are additional mechanisms through which they exert their inhibitory effects on platelet function

Robust fault detection for networked systems with distributed sensors

Copyright [2011] IEEE. This material is posted here with permission of the IEEE. Such permission of the IEEE does not in any way imply IEEE endorsement of any of Brunel University's products or services. Internal or personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution must be obtained from the IEEE by writing to [email protected]. By choosing to view this document, you agree to all provisions of the copyright laws protecting it.This paper is concerned with the robust fault detection problem for a class of discrete-time networked systems with distributed sensors. Since the bandwidth of the communication channel is limited, packets from different sensors may be dropped with different missing rates during the transmission. Therefore, a diagonal matrix is introduced to describe the multiple packet dropout phenomenon and the parameter uncertainties are supposed to reside in a polytope. The aim is to design a robust fault detection filter such that, for all probabilistic packet dropouts, all unknown inputs and admissible uncertain parameters, the error between the residual (generated by the fault detection filter) and the fault signal is made as small as possible. Two parameter-dependent approaches are proposed to obtain less conservative results. The existence of the desired fault detection filter can be determined from the feasibility of a set of linear matrix inequalities that can be easily solved by the efficient convex optimization method. A simulation example on a networked three-tank system is provided to illustrate the effectiveness and applicability of the proposed techniques.This work was supported by national 973 project under Grants 2009CB320602 and 2010CB731800, and the NSFC under Grants 60721003 and 60736026

Current distribution of collective thermal depinning of Josephson vortices in naturally stacked Josephson junctions

We investigated the thermal-depinning current (I(c)) distribution of Josephson vortices (JVs) in naturally stacked Bi(2)Sr(2)CaCu(2)O(8+delta) intrinsic Jospehson junctions in tesla-range magnetic fields and at different field tilt angles from the in-plane position. The I(c) distribution in the thermal-activation regime contains accurate information on the bias and magnetic-field dependence of the Josephson-vortex pinning potential. In a few-tesla-range magnetic field, JVs in a row in a junction, strongly coupled with each other, are pinned or depinned like a single physical entity at a single pinning center. In the best-aligned in-plane magnetic field, the edge pinning is most relevant and is insensitive to the field strength. In the presence of pancake vortices (PVs) in a slightly tilted field, however, the PV pinning deepens the JV pinning potential linearly with the number of PVs.open1122sciescopu

Microstructure and bonding behavior of fiber-mortar interface in fiber-reinforced concrete

The interfacial properties between fiber and matrix play a critical role in the overall mechanical responses of composite materials. In this paper, the glass fiber-mortar interfacial microstructure in fiber reinforced concrete (FRC) is visualized and characterized using X-ray microscopy. Additionally, three types of fiber-mortar interface (glass fiber, high modulus polyvinyl alcohol (PVA) fiber, and basalt fiber) are analyzed by scanning electron microscopy and energy dispersive X-ray spectroscopy. The results revealed a lot of microcracks along with the glass fiber-mortar interface; moreover, the hydration product of the glass/PVA/basalt fiber-mortar interface was much lower than that of the mortar matrix. Because microcracks or lower hydration product have such a negative effect on the interfacial bonding between fiber and mortar, the objective of this paper was to provide an analysis of this problem through extensive testing of their bonding properties. Specimens made of three types of fiber were tested along with three different mortar types under tensile stress and a combined stress state to investigate the interfacial bond properties between fiber and mortar. Results show that both of the tensile and shear bond strength of the interface were not only improved by stronger mortar matrix, but also significantly affected by fiber type. Furthermore, when the interface failed by slipping along the interfacial area, the interface showed an increasing shear bond strength with the increase of compressive stress. This was not the case when failure was due to the crushing of mortar. Finally, the FRC splitting tensile strength was tested to demonstrate the bonding mechanism effects on the FRC mechanical properties

Transport of magnetic flux and mass in Saturn's inner magnetosphere

It is well accepted that cold plasma sourced by Enceladus is ultimately lost to the solar wind, while the magnetic flux convecting outward with the plasma must return to the inner magnetosphere. However, whether the interchange or reconnection, or a combination of the two processes is the dominant mechanism in returning the magnetic flux is still under debate. Initial Cassini observations have shown that the magnetic flux returns in the form of flux tubes in the inner magnetosphere. Here we investigate those events with 10 year Cassini magnetometer data and confirm that their magnetic signatures are determined by the background plasma environments: inside (outside) the plasma disk, the returning magnetic field is enhanced (depressed) in strength. The distribution, temporal variation, shape, and transportation rate of the flux tubes are also characterized. The flux tubes break into smaller ones as they convect in. The shape of their cross section is closer to circular than fingerlike as produced in the simulations based on the interchange mechanism. In addition, no sudden changes in any flux tube properties can be found at the “boundary” which has been claimed to separate the reconnection and interchange-dominant regions. On the other hand, reasonable cold plasma loss rate and outflow velocity can be obtained if the transport rate of the magnetic flux matches the reconnection rate, which supports reconnection alone as the dominant mechanism in unloading the cold plasma from the inner magnetosphere and returning the magnetic flux from the tail

Impact and spreading of microdrops on homo- and heterogeneous solids: Modelling and benchmark simulations

This paper was presented at the 3rd Micro and Nano Flows Conference (MNF2011), which was held at the Makedonia Palace Hotel, Thessaloniki in Greece. The conference was organised by Brunel University and supported by the Italian Union of Thermofluiddynamics, Aristotle University of Thessaloniki, University of Thessaly, IPEM, the Process Intensification Network, the Institution of Mechanical Engineers, the Heat Transfer Society, HEXAG - the Heat Exchange Action Group, and the Energy Institute.The finite element framework developed for the high accuracy computation of dynamic wetting phenomena in Sprittles & Shikhmurzaev, Int. J. Num. Meth. Fluids 2011 is used to develop a code for the simulation of unsteady flows such as microdrop impact and spreading. The accuracy of the code for describing free-surface flows is tested by comparing its results to those obtained in previous numerical studies for the large amplitude oscillations of free liquid drops in zero gravity. The capability of our code to produce high resolution benchmark calculations for dynamic wetting flows, using either conventional modelling or the more sophisticated interface formation model, is demonstrated by simulating microdrop impact and spreading on surfaces of greatly differing wettability. The simulations allow one to see features of the drop shape which are beyond the resolution of experiments. Directions of our research programme that follows the presented study are outlined

Postpartum Haemorrhage in a Secondary Level Health Care Centre in Kebbi State, Nigeria

Background: Postpartum haemorrhage [PPH] is a major cause of maternal morbidity and mortality in Nigeria. Some women are at greater risk of postpartum haemorrhage than others. Obstetric care is provided at three levels of care in Nigeria; primary, secondary and tertiary (specialist care) levels, with substantial difference in quality between the levels.Objectives: The objective of the study was to record the pattern of presentation and the mode of management of the patients with PPH in a secondary-level health care delivery centre.Method: The records of patients seen with PPH over a three-year period from January 2004 to December 2006 at a government general hospital in Northwestern Nigeria were retrieved to extract information about the socio-demographic and clinical attributes of the patients, including the mode ofmanagement of their clinical problems.Result: During the period, 55 patients were managed for postpartum haemorrhage; 45 for primary PPH and 10 for secondary PPH. They all received uterotonic agaents and blood transfusion in the course ofmanagement.Conclusion: Early presentation, prompt management, and availability of uterotonic agents and blood transfusion services are necessary in the management of postpartum haemorrhage as delay in prompt management leads to avoidable maternal deaths.Key Words: Haemorrhage, Childbirth, Blood Transfusio

Indications for Caesarean Section at a Nigerian District Hospital

Background: Caesarean section (CS) is a common surgical procedure performed in women of reproductive age. The numerous indications for a CS may be due to foetal or maternal problems. Though it is a life saving procedure, it also carries a higher morbidity and mortality than vagina delivery.Method: This is a retrospective study conducted from January 2005 to December 2006 at a secondary health facility located in a rural setting in Nigeria. The maternity ward and theatre registers were the sources of data.Results: There were fourteen indications for the 155-caeserean sections performed with obstructed labour being the highest indication. Obstructed labour, eclampsia and pre-eclampsia were the major indications for caeserean section. There were 4 (2.6%) Maternal deaths and 19(12.2%) stillbirths out of the 156 babies delivered.Conclusion: Lack of utilization antenatal care services present in the locality and late presentation are some of the risks of maternal mortality and poor foetal outcome. The populace need to be educated on the importance of antenatal care.Key Words: Caesarean Section; Indications; Nigerian Hospita