Magnetic Resonance Imaging of Carotid Atherosclerosis

__Abstract__ Worldwide, about 17 million people die from cardiovascular disease (CVD) each year, chiefly from ischemic heart disease and stroke.(1) Amongst those, stroke, the most common manifestation of cerebrovascular disease, has been the leading cause of serious, long-term disability in adults worldwide (1990-2010) (2) There are two main types of stroke — ischemic and hemorrhagic. Ischemic stroke is more common and caused by an obstruction in the cerebral vasculature. The causes of ischemic strokes are heterogeneous, including atherosclerosis in the large arteries such as the carotid arteries (see fig 1.), lacunar infarctions and cardiogenic embolism. In this thesis, I will focus on carotid atherosclerosis as it is the most prominent to identify patients with a high risk of ischemic stroke. Atherosclerotic plaques can rupture which will lead to thrombo-embolization into the intracranial circulation or to acute occlusion of the carotid artery. Despite major advances in treatment strategies, ischemic stroke due to carotid atherosclerotic remains a serious public health problem. Current screening and diagnostic methods are insufficient to identify the plaques that have a high rupture risk and thus to select the individual before he is confronted with an ischemic stroke. One of the strategies to better face the challenges of cerebrovascular disease and improve well being of the population and of the individual includes early recognition of the vulnerable high-risk atherosclerotic plaque

Who is covered and who under-reports: An empirical analysis of access to social insurance on the Egyptian labor market

This working paper investigates the dynamics and determinants of having access to social insurance coverage on the Egyptian labor market among wage and non-wage workers. The results show that men, older, married, better educated, and white collar highly skilled workers are more likely to have social insurance coverage. Access to social insurance is more likely to exist in the public sector and in large private enterprises. Furthermore, acquiring social insurance coverage in the private wage work sector does not often come at first entry; but it takes some time to gain such access. In contrast, experience is not important for acquiring social insurance coverage among non-wage workers. Underreporting insurable wages is negatively correlated with levels of education and labor market experience, and the likelihood of underreporting increases with monthly basic salary and years to retirement age

Social protection in Egypt: A policy overview

The need to address the shortcomings of Egypt’s current social protection system as part of a broader process of developing a new social contract between the Egyptian government and its citizens has been noted for a number of years. With a new government recently put in place, Egypt is now at a potential turning point in terms of implementing unfinished reforms to the system or proposing alternative ones. The aim of this paper is therefore to provide an overview and assessment of current public social protection mechanisms and suggest directions for new policy measures. The social and health insurance systems are covered, as well as the social assistance program that provides non-contributory pensions. Recommended policy measures to improve the current social protection system fall into three inter-related categories: strengthening the link between contribution and benefit levels, expanding coverage, and improving the administration of the system

Who is covered and who underreports: Access to social insurance on the Egyptian labor market

In Egypt, as in many developing countries, the convergence of poverty and lack of social security places the working poor in a vulnerable situation that mandates immediate action in research and programmatic interventions. Before the January 25th revolution, a focus on social security was relevant in view of the insecurities instigated by increasing market liberalization and the shrinking role of the state in services and employment. The revolution and its aftermath heightened a sense of insecurity and labor protests mandated a serious re-evaluation of recent labor market policies and the social protection system in Egypt. Issues of social security, employment, and household livelihood strategies are of particular relevance now more than ever. This policy brief identifies the worker- and enterprise-level determinants of having social insurance coverage on the Egyptian labor market among wage and nonwage workers. It also sheds light on the phenomenon of underreporting the basic salary to the social security authority in the private wage sector

AUTOMATIC STEERING CONTROL OF RICE TRANSPLANTER (PART 2) : Control Method

田植機の自動操向制御の一手段として, 既に植え付けられた苗列を検出し, それに沿ってならい操向制御を行うことを目的として, 苗検出回路の改良と, 記憶・論理回路による制御方式の試行を行った。1) 検出回路は, OPアンプによる非反転増幅器により, 苗の抵抗を電圧に変えて検出する方式である。この回路の検出限界を固定抵抗を用いて測定したところ, 約33MΩであった。2) 検出信号は比較回路でオン・オフ信号に変換された後, 単安定マルチ・バイブレータをトリガし, 一定幅(0.1秒)のパルスが出力される。3) このパルスをタイミング・パルスとして, シフト・レジスタを用いた記憶回路で, 現在検出中の苗の5株前までの田植機の状態を保持し, 論理回路で論理演算を行って, 田植機の左旋回, 直進, 右旋回を決定する。4)この検出回路により, 苗の茎部を接触した場合は100%, 葉部を接触した場合でも約60%の検出能力があることが判った。5)記憶回路及び論理回路は, ほぼ初期の目的は達成でき, 田植機のずれが大きくなれば, 制御出力パルスの時間が長くなり, 走行速度が速くなるにつれ出力パルスの幅が短かくなる。 / This research was investigated as a method for the automatic steering of rice transplanter. It is the purpose of this research that the rice transplanter is steered automatically along the plant row which is transplanted previously. In this report, the detecting method mentioned in the previous report was improved and the controlling method by using memory and logical circuit was tried. (1) The detecting method was as follows. The electrical resistance of rice plant was converted to DC voltage by a non-inverting buffer amplifier with 741 type operational amplifier and the rice plant was detected. The detecting limit of this circuit was about 33MΩ. This value was extended more than the previous report. (2) The detected signal was converted to ON-OFF signal by a comparator, and it was triggered a monostable multivibrator IC. So the IC generated a fixed width pulse (0.1 second) when the sensor detected a rice plant. (3) The memory circuit held the condition of rice transplanter. This circuit was consisted in 5 bits serial-in, parallel-out shift register, so the rice plants of 5 hills were memorized and shifted by the timing pulse generated at a monostable multivibrator IC. The left turn, straight running, and right turn of transplanter was decided by the logical operations of the output signal of shift registers. (4) The memory and logical circuits almost achieved the initial purpose. If the error of transplanter was large, the holding time of pulse which controlled the transplanter became long. If the traveling speed of transplanter was fast, the pulse width became short, so the contolling time of transplanter changed according to the error and the traveling speed

High shear stress relates to intraplaque haemorrhage in asymptomatic carotid plaques

Background and aims Carotid artery plaques with vulnerable plaque components are related to a higher risk of cerebrovascular accidents. It is unknown which factors drive vulnerable plaque development. Shear stress, the frictional force of blood at the vessel wall, is known to influence plaque formation. We evaluated the association between shear stress and plaque components (intraplaque haemorrhage (IPH), lipid rich necrotic core (LRNC) and/or calcifications) in relatively small carotid artery plaques in asymptomatic persons. Methods Participants (n = 74) from the population-based

High shear stress relates to intraplaque haemorrhage in asymptomatic carotid plaques

AbstractBackground and aimsCarotid artery plaques with vulnerable plaque components are related to a higher risk of cerebrovascular accidents. It is unknown which factors drive vulnerable plaque development. Shear stress, the frictional force of blood at the vessel wall, is known to influence plaque formation. We evaluated the association between shear stress and plaque components (intraplaque haemorrhage (IPH), lipid rich necrotic core (LRNC) and/or calcifications) in relatively small carotid artery plaques in asymptomatic persons.MethodsParticipants (n = 74) from the population-based Rotterdam Study, all with carotid atherosclerosis assessed on ultrasound, underwent carotid MRI. Multiple MRI sequences were used to evaluate the presence of IPH, LRNC and/or calcifications in plaques in the carotid arteries. Images were automatically segmented for lumen and outer wall to obtain a 3D reconstruction of the carotid bifurcation. These reconstructions were used to calculate minimum, mean and maximum shear stresses by applying computational fluid dynamics with subject-specific inflow conditions. Associations between shear stress measures and plaque composition were studied using generalized estimating equations analysis, adjusting for age, sex and carotid wall thickness.ResultsThe study group consisted of 93 atherosclerotic carotid arteries of 74 participants. In plaques with higher maximum shear stresses, IPH was more often present (OR per unit increase in maximum shear stress (log transformed) = 12.14; p = 0.001). Higher maximum shear stress was also significantly associated with the presence of calcifications (OR = 4.28; p = 0.015).ConclusionsHigher maximum shear stress is associated with intraplaque haemorrhage and calcifications