Anomalies, D-flatness and Small Instantons

Recently, Witten has proposed a mechanism for symmetry enhancement in $SO(32)$ heterotic string theory, where the singularity obtained by shrinking an instanton to zero size is resolved by the appearance of an $Sp(1)$ gauge symmetry. In this short letter, we consider spacetime constraints from anomaly cancellation in six dimensions and D-flatness and demonstrate a subtlety which arises in the moduli space when many instantons are shrunk to zero size.Comment: 8 pages, harvma

Televised Gender Roles in Children’s Media: Covert Messages

Encountering stereotypes promulgated by media representations is a daily occurrence. Information perpetuated in the media continually influences how people view the world. Female gender roles portrayed in television, for example, have altered from the 1950s stay-at-home mother portrayed by Barbara Billingsley in Leave It To Beaver, to postmodern portrayals of independent actress/mothers such as Jane Seymour. The messages that such diverse personifications suggest of motherhood are equally disparate. While television once perpetuated images of mothers as in the home caregivers, this domestic characterization has evolved into moms who now venture actively into the world

Tear Down These Walls: New Genre Public Art and Art Education

Public genre art education follows the lead established by the professional art world to engage the public with artforms that depart from traditional media usage and intentions to encourage collaboration, the demystification of art processes, and societal reconstruction. Termed new genre public art, Suzanne Lacy (1995) described in Mapping the Terrain: New Genre Public Art a new sensibility exhibited in the past three decades by artists who deal with the most profound issues of our time “in manners that resemble political and social activity but is distinguished by its aesthetic sensibility”

Gravitational Couplings of D-branes and O-planes

An explicit calculation is performed to check all the tangent bundle gravitational couplings of Dirichlet branes and Orientifold planes by scattering $q$ gravitons with a $p+1$ form Ramond-Ramond potential in the world-volume of a $D(p+2q)$-brane. The structure of the D-brane Wess-Zumino term in the world-volume action is confirmed, while a different O-plane Wess-Zumino action is obtained

D-brane form factors at high energy

We study the high energy, fixed angle, asymptotics of D-brane form factors to all orders in string perturbation theory, using the Gross-Mende saddle point techniques. The effective interaction size of all D-branes grows linearly with the energy as (alpha') E/n, where n is the order of perturbation theory, except for the D-instanton, whose form factor is dominated by end-point contributions, and remains point-like at high orders. The qualitative features are independent of the R-R or NS-NS character of the states used to probe the D-brane.Comment: 8pp. Some errors corrected and references adde

Covariant Gauge Fixing for Super IIA D-branes

For the kappa-symmetric super IIA D-brane action by the canonical approach we construct an equivalent effective action which is characterized by an auxiliary scalar field. By analyzing the canonical equations of motion for the kappa-symmetry-gauge-fixed action we find a suitable conformal-like covariant gauge fixing of reparametrization symmetry to obtain a simplified effective action where the non-linear square root structure is removed. We discuss how the two effective actions are connected.Comment: 9 pages, LaTeX2e, no figures, one reference adde

D-Branes and Bundles on Elliptic Fibrations

We study the D-brane spectrum on a two-parameter Calabi-Yau model. The analysis is based on different tools in distinct regions of the moduli space: wrapped brane configurations on elliptic fibrations near the large radius limit, and SCFT boundary states at the Gepner point. We develop an explicit correspondence between these two classes of objects, suggesting that boundary states are natural quantum generalizations of bundles. We also find interesting D-brane dynamics in deep stringy regimes. The most striking example is, perhaps, that nonsupersymmetric D6-D0 and D4-D2 large radius configurations become stable BPS states at the Gepner point.Comment: 22 page

Anomalies, Dualities, and Topology of D=6 N=1 Superstring Vacua

We consider various aspects of compactifications of the Type I/heterotic $Spin(32)/\Z_2$ theory on K3. One family of such compactifications includes the standard embedding of the spin connection in the gauge group, and is on the same moduli space as the compactification of the heterotic $E_8\times E_8$ theory on K3 with instanton numbers (8,16). Another class, which includes an orbifold of the Type I theory recently constructed by Gimon and Polchinski and whose field theory limit involves some topological novelties, is on the moduli space of the heterotic $E_8\times E_8$ theory on K3 with instanton numbers (12,12). These connections between $Spin(32)/\Z_2$ and $E_8\times E_8$ models can be demonstrated by T duality, and permit a better understanding of non-perturbative gauge fields in the (12,12) model. In the transformation between $Spin(32)/\Z_2$ and $E_8\times E_8$ models, the strong/weak coupling duality of the (12,12) $E_8\times E_8$ model is mapped to T duality in the Type I theory. The gauge and gravitational anomalies in the Type I theory are canceled by an extension of the Green-Schwarz mechanism.Comment: 48 page

Modeling Regional Recycling and Remanufacturing Processes: From Micro to Macro

This paper reports progress in modeling recycling and remanufacturing processes within metropolitan regional economies at the micro and macro levels. The paper presents interim results from a multi-year, inter-institutional research project funded by the National Science Foundation. We identify a number of issues that have arisen from an in-depth industry level analysis of obsolete and waste products generated in the Seattle, WA and Atlanta, GA metro regions from waste electronics (e-waste) and carpet production and consumption. The two metro regions were selected for comparative analysis because Seattle is a recognized leader in e-waste recycling and sustainable development programs, while Atlanta has been slow to embrace recycling but is only 70 miles from the center of US carpet manufacturing (Dalton) and has an industry trade association that has set aggressive targets for carpet recycling and remanufacturing, e-waste forms the focus of this paper. We provide a detailed elaboration of processes at the micro-level, along with an enumeration of problems and solutions in characterizing these new industries, including an integration with environmental Life Cycle Assessment, and embedding the results in a macro-economic modeling framework

Recycling and Remanufacturing in Input-Output Models

Recycling and remanufacturing activities are gaining in importance, as a growing population and economy use up and wear out modern products, exhaust landfill capacity, threaten the environment, and discard potentially valuable and increasingly scarce resources. As an example, an estimated five billion pounds of carpet were sent to landfills in 2003 (CARE, 2003). Likewise, Americans discard computers, cell phones, LCDs and other electronic devices at an alarming rate. Estimates range from 100 to 250 million such items each year. As discard volumes rise and as resource scarcity becomes more critical, recycling, re-use, and remanufacturing have begun to take hold at ever more substantial scales. To understand the implications of these activities for economic development and sustainability, new methods of tracking their impacts must be developed. While at first blush it might be assumed that these activities could be modeled as could any other new industry, a number of characteristics peculiar to recycling and remanufacturing complicate the process. This paper enumerates a number of such dimensions of recycling, re-use, and remanufacturing, and lays out a scheme for extending the traditional approach