By U. Anktos. Trevecca Nazarene University. 2017.
Through it order triamterene 75mg on-line, we communicate verbally and nonverbally, express emotions and thoughts, and feed our bodies. The ¯uidity, individuality, and complexity of the musculature of the face complicate attempts to accurately model the subtlety of facial expression. In the early 1980s, Platt and Badler (21) simulated the human face using a three- layered model of skin, muscle, and bone. The muscle is a group of muscle-®ber points that are connected by elastic arcs to the overlying skin and underlying bone. By integrating the network of points, one can demonstrate how the application of force or tension on one section of the model will e¨ect more distant areas of the same surface (16). Pieper (22) created a detailed model of the face using reconstructed images from CT and MRI scans of a patient. His program, Computer-Aided Plastic Surgery (CAPS), allows the planning, analysis, and visualization of plastic sur- gery on the soft tissues of the face. It is a prototype computer program that a surgeon could use as a sketch pad to predict and compare the outcome of facial plastic procedures on a patient-speci®c physical model. The CAPS program uses a FEM to simulate plastic surgery by removing certain elements and then rede®ning the remaining elements as sharing their (formerly separate) borders, just as a sur- geon excises tissue and de®nes new shared edges with sutures. When the com- puter calculates the distorting forces and applies this to the patient-speci®c model, it is possible to visualize the consequences of the surgery. This has been used for excisions of tumors, for cleft lip repairs, and for rhinoplaties. Although the above projects have begun to put together a virtual human, to a large extent these models are based on normal anatomy and physiology. They generally use a patient data, like the Virtual Human Data from NLM, to create a generic person. I will now elaborate on some of the factor that need to be addressed by future mathematical models and software programs. They are important for not only medical applications but for many commercial and military applications. Although they are critical for medical applications, they have advanced beyond the capabilities of the human body models.
The circular cylinder shown in the figure is in neutral equilib- rium because disturbance from equilibrium position in the horizontal plane does not bring out new forces quality triamterene 75 mg. If on the other hand the elliptical cylinder is tilted a little, the new contact force that arises will rotate it back to its equilibrium configuration. The top row (a) pre- sents examples of unstable (U), neutral (N), and stable (S) equilibrium of rigid ob- jects. The middle row (b) classifies the various configurations of a rod under sta- tic equilibrium. The bottom row (c) illustrates that for nonrigid structures static equilibrium does not neccessarily correspond to the configuration where the cen- ter of gravity is at a minimum height. The height d of the center of mass of the rod for the configurations from left to right are given by the equations: d 5 L sin 30° cos 30° d 5 (L/2) sin 60° d 5 (L/2) sin 30° The configuration on the far right corresponds to the smallest value of d and is, therefore, in stable equilibrium. For structures other than a rigid body, stable equilibrium does not necessarily correspond to the configu- ration that brings the center of gravity to minimum height. Consider, for example, the structure composed of two flat plates and a spring (Fig. The plates are hinged at one edge and are also connected by a spring at midlength. The free ends of the plates are free to slide on the flat surface shown in the figure. If the gravitational force and the react- ing contact force were the only external loads acting on the structure, sta- ble equilibrium would have corresponded to the configuration where the two plates lay flat on the horizontal plane. In that configuration, how- ever, the spring would have been stretched drastically and therefore could snap with the smallest of the disturbance.
A broad range of virtual exploratory tools and options are available that enable users to investigate structures in ways not possible in the real world (Fig generic triamterene 75mg online. Students are able to repeatedly ``dissect' structures and regions or to reconstruct any area from its component parts. A scene from the Anatomic Visualizer learning module ``Anatomy of the Ear,' highlighting the study guide portion of the application. The tabs on the right side of the study guide provide ready access to each segment of the lesson. The forward and back arrows and the numeric indicator provide navigation within the tab sections. Study guide pages, such as the one shown, can include descriptive text and links to additional resources. Anatomic orientation can be maintained regardless of view or magni®cation, and ana- tomic position can be re-established through other menu-bar options. More- over, within any lesson and at any time, a student may choose to access addi- tional information resources (e. Current lessons are based in large part, on anatomic polygonal models derived from the National Library of 8. A scene from the Anatomic Visualizer learning module ``Clinical Anatomy of the Skull' includes the study guide and array of virtual tools. It depicts the use of the clipping plane to create dynamic cross-sections of the skull. The menu bar in the lower right side of the screen has the following tools (right to left) scaling, unlink, link, highlight, orient part, orient whole, clipping plane, ¯ag, probe, ruler, and space draw. The smaller menu bar at the lower left side has (right to left) search, grid on/o¨, study guide on/o¨. These models were pro- duced and supplied by Visible Productions (Fort Collins, CO).
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