Pe Num Bra

The Great Recession has shuffled Clay Jannon out of his life as a web-design drone, and serendipity, sheer curiosity and the ability to climb a ladder like a monkey have landed him a new gig working the night shift at Mr. Penumbra’s 24-Hour Bookstore. But Clay begins to realize that this store is even more curious than its name suggests. There are only a few customers, but they come in repeatedly and never seem to actually buy anything. Instead they “check out” impossibly obscure volumes from strange corners of the store, all according to some elaborate, long-standing arrangement with the gnomic Mr. Penumbra. The store must be a front for something larger, Clay concludes, and soon he has embarked on a complex analysis of the customers’ behaviour and roped his friends into helping him figure out just what’s going on. But once they take their findings to Mr. Penumbra, they discover the secrets extend far beyond the walls of the bookstore. Evoking both the fairy-tale charm of Haruki Murakami and the enthusiastic novel-of-ideas wizardry of Neal Stephenson or Umberto Eco, Mr. Penumbra’s 24-Hour Bookstore is exactly what it sounds like—an establishment you have to enter and will never want to leave.

From Robin Sloan, author of Mr. Penumbra’s 24-Hour Bookstore, the story of Mr. Penumbra’s first trip to San Francisco—and of how he got entangled with the city’s most unusual always-open enterprise . . . It is August 1969. The Summer of Love is a fading memory. The streets of San Francisco pulse to the sounds of Led Zeppelin and Marvin Gaye. And of jackhammers: A futuristic pyramid of a skyscraper is rising a few blocks from City Lights bookstore and an unprecedented subway tunnel is being built under the bay. Meanwhile, south of the city, orchards are quickly giving way to a brand-new industry built on silicon. But young Ajax Penumbra has not arrived in San Francisco looking for free love or a glimpse of the technological future. He is seeking a book—the single surviving copy of the Techne Tycheon, a mysterious volume that has brought and lost great fortune for anyone who has owned it. The last record of the book locates it in the San Francisco of more than a century earlier, and on that scant bit of evidence, Penumbra’s university has dispatched him west to acquire it for their library. After a few weeks of rigorous hunting, Penumbra feels no closer to his goal than when he started. But late one night, after another day of dispiriting dead ends, he stumbles across a 24-hour bookstore, and the possibilities before him expand exponentially . . .

The Ischemic Penumbra presents the current status of concepts and research on this topic and identifies the latest methods for clinicians to quickly and efficiently recognize viable cerebral tissue for enhanced stroke management. Focusing on state-of-the-science technologies and current trends, the book examines imaging strategies utilizing PET, SP

The second volume in the trilogy—“a complex, bizarre, and unique vision of the near future with a kaleidoscopic mix of politics, pop, and paranoia” (Bruce Sterling, author of The Hacker Crackdown). World War Three continues. A nuclear strike has laid waste to much of Europe. And the fascists and fundamentalists of the Second Alliance are diligently working on Project Total Eclipse—a nightmare scenario that seeks to establish the SA’s control over a much wider territory through a takeover of the first orbiting space colony in human history. And they are running out of patience with the New Resistance—technologically skilled guerillas who are the only ones standing in the way of their grand plans for apartheid and world domination . . . This extraordinary trilogy, which anticipated such phenomena as surveillance drones and the rising threat of right-wing authoritarianism, is a riveting saga of out-of-control corporate power, a near-future world riven by rage and fear, and the need for individuals to stand up and fight back if they want to hold on to their freedom. “Vivid, dense, powerful imagery . . . hard to put down.” —The Washington Post

Penumbra Theatre Company was founded in 1976 by Lou Bellamy as a venue for African American voices within the Twin Cities theatre scene and has stood for more than thirty-five years at the intersection of art, culture, politics, and local community engagement. It has helped launch the careers of many internationally respected theatre artists and has been repeatedly recognized for its artistic excellence as the nation’s foremost African American theatre. Penumbra is the first-ever history of this barrier-breaking institution. Based on extensive interviews with actors, directors, playwrights, producers, funders, and critics, Macelle Mahala’s book offers a multifaceted view of the theatre and its evolution. Penumbra follows the company’s emergence from the influential Black Arts and settlement house movements; the pivotal role Penumbra played in the development of August Wilson’s career and, in turn, how Wilson became an avid supporter and advocate throughout his life; the annual production of Black Nativity as a community-building performance; and the difficult economics of African American theatre production and how Penumbra has faced these challenges for nearly four decades. Penumbra is a testament to how a theatre can respond to and thrive within changing political and cultural realities while contributing on a national scale to the African American presence on the American stage. It is a celebration of theatre as a means of social and cultural involvement—both local and national—and ultimately, of Penumbra’s continuing legacy of theatre that is vibrant, diverse, and vital.

Guest-edited by Agostino De Rosa, Alessio Bortot and Francesco Bergamo Penumbra, from the Latin paene (almost) and umbra (shadow), can be defined as an intermediate zone of transition between light and shadow. Penumbra is therefore that space, both physical and imaginary, where everything is possible: it is the place of the uncanny, where presence and/or absence can produce wonder or horror. This AD positions the presence of this archetype in the contemporary world of architecture, investigating the ways it permeates different expressive forms – from critical theory to architectural drawing, from design and planning to photography. The contributors illustrate and discuss how penumbra has shaped their creativity and modified their approach to the design process. As a physical phenomenon, penumbra has supra-historical and global connotations; nonetheless, different cultures elaborate its symbolism in different ways. Its wide semantic spectrum powerfully inspires creative forms that hover between fullness and emptiness, presence and absence, past and future. The critical perspectives in this issue offer a wide analysis of penumbra’s expressive potential and the key to an in-depth understanding of this elusive layer of reality. Contributors: Matthias Bärmann, Silvia Benedito, Filippo Bricolo, Edwin Carels, Javier Corvalán, Dris Kettani, Stephen Kite, Giancarlo Mazzanti, Akira Mizuta Lippit, Susanna Pisciella, Renato Rizzi, Paul O Robinson, and Antonella Soldaini. Featured architects and artists: Alexander Savvich Brodsky, Neri&Hu studio, Quay Brothers, Ursula Schulz-Dornburg, and Marco Tirelli.

A method for calculating orbital shadow terminator points is presented. The current method employs the use of an iterative process which is used for an accurate determination of shadow points. This calculation methodology is required, since orbital perturbation effects can introduce large errors when a spacecraft orbits a planet in a high altitude and/or highly elliptical orbit. To compensate for the required iteration methodology, all reference frame change definitions and calculations are performed with quaternions. Quaternion algebra significantly reduces the computational time required for the accurate determination of shadow terminator points.

The ischemic penumbra was initially defined by Symon, Lassen and colleagues in the 1970s as an area of brain tissue with inadequate blood flow to maintain electric activity of neurons but adequate blood flow to preserve the function of the ion channels. This area of tissue, receiving enough blood to survive but not enough to function, often surrounds or abuts the irreversibly damaged core in ischemic stroke. It was shown that if blood flow could be restored to this area of marginal perfusion, the tissue could survive and function again, and growth of the core could be prevented. Based on seminal PET studies, penumbra or "penumbral tissue" eventually took on a subtly different meaning - the area of brain that is destined to progress to infarct unless blood flow is restored within a particular time window. The penumbra thus became the target for all acute stroke interventions - to preserve viability of the tissue and restore function. New imaging techniques, including diffusion and perfusion MRI and CT perfusion, were developed to rapidly identify individuals with penumbra, who were thought to be the best candidates for aggressive interventions to restore blood flow, particularly beyond the licensed time-window for IV thrombolysis. However, most clinical trials have failed to establish the usefulness of identifying candidates for treatment in this way using pre-specified protocols and primary endpoints. These trials have used different and sometimes unvalidated thresholds of hypoperfusion as well as irreversible infarct and various definitions of significant penumbra (or mismatch between irreversible infarct and hypoperfused, but salvageable tissue), and reanalysis of their data using more refined image processing showed post-hoc positivity. They have also evaluated outcome in a variety of ways, with few studies measuring the direct effect of restoring blood flow on the function of the penumbral tissue. Therefore, important remaining questions include how to define, characterize, and image the penumbra in acute stroke to achieve the greatest reliability and validity for what we want to measure, and whether this concept, so defined, provides an optimal target for stroke therapy using state-of-the-art trial design.