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Pencil art workshop : techniques, ideas, and inspiration for drawing and designing with pencil
\"In Pencil Art Workshop, artist and illustrator Matt Rota shows to achieve various techniques using graphite, and includes the work of an international gallery of artists for inspiration\"-- Provided by publisher.
Book
Cats : secrets of observational drawing
\"Whether scribbling out a quick sketch with minimal detail, or making a finished portrait where every silky hair and polished whisker stands out, the best cat artists can capture the very essence of feline-ness. How do they do it? Firsthand observation of cats will tell you a lot about the way they sit, yawn, position their tails, and curl up to sleep, but it won't tell you how to get those things down on paper. Classic Sketchbook: Cats is the second in a series of instructional books that began with Classic Sketchbook: Botanicals. The series shows how it's done by looking at details of museum-quality works, then coaching readers through the techniques with the help an expert's suggestions. In this case the expert is Patricia Wynne, a noted illustrator with a specialty in animals. Wynne will guide you through fur, paws, and eyes, as well as cats sleeping, playing, or pouncing. Her unique instructions places a close-up of a drawing or painting by a noted artist like Gauguin, Chardin, Gwen John, and Theodore Steinlen on the left side of the page. And on the right side of the page Patricia Wynne coaches you with detailed, step-by-step drawings, that illuminate the process\"-- Provided by publisher.
Book
Generic Eigenstructures of Hermitian Pencils
We obtain the generic complete eigenstructures of complex Hermitian n x n matrix pencils with rank at most r (with r <= n). To do this, we prove that the set of such pencils is the union of a finite number of bundle closures, where each bundle is the set of complex Hermitian n x n pencils with the same complete eigenstructure (up to the specific values of the distinct finite eigenvalues). We also obtain the explicit number of such bundles and their codimension. The cases r = n, corresponding to general Hermitian pencils, and r < n exhibit surprising differences, since for r < n the generic complete eigenstructures can contain only real eigenvalues, while for r = n they can contain real and nonreal eigenvalues. Moreover, we will see that the sign characteristic of the real eigenvalues plays a relevant role for determining the generic eigenstructures.
Journal Article
Validation of the RayStation Monte Carlo dose calculation algorithm using a realistic lung phantom
Purpose Our purposes are to compare the accuracy of RaySearch's analytical pencil beam (APB) and Monte Carlo (MC) algorithms for clinical proton therapy and to present clinical validation data using a novel animal tissue lung phantom. Methods We constructed a realistic lung phantom composed of a rack of lamb resting on a stack of rectangular natural cork slabs simulating lung tissue. The tumor was simulated using 70% lean ground lamb meat inserted in a spherical hole with diameter 40 ± 5 mm carved into the cork slabs. A single‐field plan using an anterior beam and a two‐field plan using two anterior‐oblique beams were delivered to the phantom. Ion chamber array measurements were taken medial and distal to the tumor. Measured doses were compared with calculated RayStation APB and MC calculated doses. Results Our lung phantom enabled measurements with the MatriXX PT at multiple depths in the phantom. Using the MC calculations, the 3%/3 mm gamma index pass rates, comparing measured with calculated doses, for the distal planes were 74.5% and 85.3% for the APB and 99.1% and 92% for the MC algorithms. The measured data revealed up to 46% and 30% underdosing within the distal regions of the target volume for the single and the two field plans when APB calculations are used. These discrepancies reduced to less than 18% and 7% respectively using the MC calculations. Conclusions RaySearch Laboratories' Monte Carlo dose calculation algorithm is superior to the pencil‐beam algorithm for lung targets. Clinicians relying on the analytical pencil‐beam algorithm should be aware of its pitfalls for this site and verify dose prior to delivery. We conclude that the RayStation MC algorithm is reliable and more accurate than the APB algorithm for lung targets and therefore should be used to plan proton therapy for patients with lung cancer.
Journal Article