benefit from hospital admission for selected patients with suspected myocardial infarction and where diagnostic or therapeutic help in the home was offered, home care did not make any substantial impact on the need for hospital services.If general practitioners do not consider home care to be an acceptable form of management for patients with suspected myocardial infarction, then there is little point in their playing any part when patients develop suspicious symptoms. In fact, general practitioners cannot help most patients who die from a heart attack: a register of all patients with heart attacks in the Nottingham Health District confirmed earlier reports that most deaths occur soon after the onset of symptoms and before medical aid is sought.7 8 If virtually all patients with heart attacks who survive long enough are going to be admitted to hospital, should the general practitioners and patients be persuaded that a call for an emergency ambulance is the appropriate action and not a call for a general practitioner? There is, however, little point in instituting such a programme of public education without an ambulance that can respond appropriately. After two of our earlier studies had shown that a single "coronary" ambulance could not be used effectively,9 10 the emergency and routine functions of our ambulance service were separated, and all the emergency vehicles are now being equipped with defibrillators and their crews specially trained. A programme of community education in the need to call for an emergency ambulance rather than a general practitioner together with public education in cardiopulmonary resuscitation is now beginning, and we shall use our heart attack register to monitor its effect. (51) mmol/24 h. Compared with the screening blood pressure the average decrement of the supine blood pressure in group 1 was 16-0/8-6 mm Hg with placebo, 21-7/11.5 mm Hg with the diuretic, 28-5/17-8 mm Hg with the J8 blocker, and 28 9/18-4 mm Hg with the combined agent; in group 2 these values were 13 3/6-1, 20 3/9-7, 21 3/12-9, and 29-4/16-8 mm Hg, respectively. There was a sharp decrease of the average potassium concentration during chlorthalidone and combination treatment periods (average value 3-3 mmol(mEq)/l).These results suggest that moderate salt restriction used as sole treatment has a limited though demonstrable blood pressure lowering effect but that when it is used as an adjuvant to 0i blocker treatment its value is greatly enhanced.
The transport properties of cement-based materials significantly affect their durability. This results from the fact that most of the damaging reagents are transported, often solved in water, through the open pore space into the microstructure. This paper focuses on simulating water permeation (movement under a gradient of pressure) and water vapor diffusion (movement under a gradient of concentration) through hardened cement paste (hcp). The main goal is to derive the water permeability and the water vapor diffusion coefficient directly from the morphology of the 3D microstructure. For this purpose microtomographic images of a hcp made of ordinary Portland cement are used to represent the microstructure and especially the pore space through which the moisture transport will occur. With the use of a skeletonization algorithm, also known as ''thinning algorithm'', the skeleton or centerline of the pore space is extracted. This skeleton is in a second step converted into a transportation network of cylindrical tubes. Bernoulli's law is applied to every tube for simulating water permeation. The permeability coefficient is then calculated by using Darcy's law. In the case of water vapor diffusion the diffusion coefficient is calculated using Fick's law.
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