Myocardial Infarction

Myocardial infarction (MI), commonly known as a heart attack is the disease of the blood vessels supplying the heart muscle (Myocardium) i.e. coronary heart disease. The area of heart muscle that has either zero flow or so little flow that it cannot sustain cardiac muscle function is said to be infracted and the overall process is called a myocardial infarction. MI are of two types; transmural and subendocardial. Mainly it is caused due to oxidative stress and atherosclerosis.Chest pain is the most common symptom of acute MI and is often described as a sensation of tightness, pressure, or squeezing. Other symptoms include diaphoresis (an excessive form of sweating), Shortness of breath (dyspnea), weakness, light-headedness, nausea, vomiting, and palpitations. The most common symptoms of MI in women include dyspnea, weakness, and fatigue, sleep disturbances. It can be treated by using blockers, diuretics, ACE inhibitors, calcium channel blockers and nitrates.

Flutter of Rectangular Plate at Non-Zero Flow Yaw Angle

Panel flutter is a phenomenon of self-exciting vibrations of skin panels of flight vehicles moving at high speeds. There are two types of panel flutter. The first one is the coupled-mode flutter, which is caused by the interaction of two panel eigenmodes. The second type is the single-mode flutter, in this case the coalescence of eigenfrequencies and a significant change in the oscillation mode shape does not take place. The stability of the infinite series of thin elastic rectangular plates simply supported along all edges is investigated in this study. The non-zero flow yaw angle with supersonic leading edge is considered. We use potential flow theory to derive expression for the unsteady aerodynamic pressure distribution over the oscillating plate. The plate motion equation, after the substitution of expression for unsteady aerodynamic pressure, with simply supported boundary conditions, is an integro-differential eigenvalue problem for finding complex eigenvalues. We use the Bubnov–Galerkin procedure for finding eigenvalues. Thus, the flutter criterion is the sign of imaginary part of eigenvalue. Flutter boundaries for the first eigenfrequencies were computed for non-zero yaw angles We show how the single-mode and coupled-mode flutter boundaries are changed with the change of the yaw angle.

Hydrological, Environmental and Taxonomical Heterogeneity during the Transition from Drying to Flowing Conditions in a Mediterranean Intermittent River

Intermittent rivers and ephemeral streams (IRES) are increasingly studied because of their often-unique aquatic and terrestrial biodiversity, biogeochemical processes and associated ecosystem services. This study is the first to examine the hydrological, physicochemical and taxonomic variability during the dry-wet transition of an intermittent river in the Chilean Mediterranean Zone. Based on 30-years of river monitoring data and the TREHS tool, the hydrology of the river was characterised. Overall, the river shows a significant reduction in streamflow (−0.031 m3/s per year) and a substantial increase of zero flow days (+3.5 days per year). During the transition of hydrological states, variations were observed in the environmental conditions and invertebrate communities. During the drying phase, abundance, richness, and diversity were highest, while species turn-over was highest during base flow conditions. The disconnected pools and the flow resumption phases were characterised by high proportions of lentic taxa and non-insects, such as the endemic species of bivalves, gastropods, and crustaceans, highlighting the relevance of disconnected pools as refuges. Future climatic change scenarios are expected to impact further the hydrology of IRES, which could result in the loss of biodiversity. Biomonitoring and conservation programmes should acknowledge these important ecosystems.

Simulating streamflow in a temporary karst river system

<p>Most of the basins in the Mediterranean Region are characterized by a large spatial gradient in rainfall and temperature and heterogeneity in lithology, soil, and land use. Such environmental factors determine a specific hydrological regime of the river systems that generally includes periods of absence of flow and flash flood events.</p><p>In the past decades, several countries in South Europe did not invest resources for the monitoring of the intermittent river systems. Currently, several basins have limited time series of streamflow and water quality data. In addition, it is not rare the case of climate stations not well distributed in the basin as well as the presence of several gaps in the time series.</p><p>The lithology and geological features are among the main factors affecting the flow regime, playing a crucial role in groundwater and surface-water interaction and water exchange for which the flow may appear and disappear along with the river network. In such a complex environment, the hydrological and water quality model set up and run may be challenging.</p><p>Through a case study, this work aims to face some challenges and to define problem-solving in simulating hydrology in Mediterranean basins. The area is characterized by (i) heterogeneity in lithology with karst areas, (ii) limited flow data availability for calibrating the model, (iii) flow intermittence in the river network. The Soil and Water Assessment Tool (SWAT) was applied to the Canale D’aiedda  (Puglia, Italy), a temporary karst river basin under the Mediterranean climate and with limited data availability. Different solutions were tested to simulate the hydrological processes in the karstic areas including both GIS elaborations and model parameters settings and modifications. Among the main parameters, infiltration and transmission losses and soil hydraulic parameters resulted in the most relevant in simulating hydrology in the karst areas. To calibrate the model, a split-in-space procedure was adopted to overcome the limited streamflow measurement availability. Finally, a zero-flow threshold was introduced to predict the number of zero-flow days in the intermittent river reaches, simulating accurately the flow intermittence and the extreme low flow.</p><p>The results show that by using specific strategies in setting-up and calibrating the model, the SWAT model is able to simulate daily streamflow with acceptable performances in complex river basins.</p>

A space hurricane over the Earth’s polar ionosphere

In Earth’s low atmosphere, hurricanes are destructive due to their great size, strong spiral winds with shears, and intense rain/precipitation. However, disturbances resembling hurricanes have not been detected in Earth’s upper atmosphere. Here, we report a long-lasting space hurricane in the polar ionosphere and magnetosphere during low solar and otherwise low geomagnetic activity. This hurricane shows strong circular horizontal plasma flow with shears, a nearly zero-flow center, and a coincident cyclone-shaped aurora caused by strong electron precipitation associated with intense upward magnetic field-aligned currents. Near the center, precipitating electrons were substantially accelerated to ~10 keV. The hurricane imparted large energy and momentum deposition into the ionosphere despite otherwise extremely quiet conditions. The observations and simulations reveal that the space hurricane is generated by steady high-latitude lobe magnetic reconnection and current continuity during a several hour period of northward interplanetary magnetic field and very low solar wind density and speed.