Anderson Localization of Polar Eigenmodes in Random Planar Composites

Anderson localization of classical waves in disordered media is a fundamental physical phenomenon that has attracted attention in the past three decades. More recently, localization of polar excitations in nanostructured metal-dielectric films (also known as random planar composite) has been subject of intense studies. Potential applications of planar composites include local near-field microscopy and spectroscopy. A number of previous studies have relied on the quasistatic approximation and a direct analogy with localization of electrons in disordered solids. Here I consider the localization problem without the quasistatic approximation. I show that localization of polar excitations is characterized by algebraic rather than by exponential spatial confinement. This result is also valid in two and three dimensions. I also show that the previously used localization criterion based on the gyration radius of eigenmodes is inconsistent with both exponential and algebraic localization. An alternative criterion based on the dipole participation number is proposed. Numerical demonstration of a localization-delocalization transition is given. Finally, it is shown that, contrary to the previous belief, localized modes can be effectively coupled to running waves.Comment: 22 pages, 7 figures. Paper was revised and a more precise definition of the participation number given, data for figures recalculated accordingly. Accepted to J. Phys.: Cond. Mat

On the Convergence of the Born Series in Optical Tomography with Diffuse Light

We provide a simple sufficient condition for convergence of Born series in the forward problem of optical diffusion tomography. The condition does not depend on the shape or spatial extent of the inhomogeneity but only on its amplitude.Comment: 23 pages, 7 figures, submitted to Inverse Problem

Multiple Projection Optical Diffusion Tomography with Plane Wave Illumination

We describe a new data collection scheme for optical diffusion tomography in which plane wave illumination is combined with multiple projections in the slab imaging geometry. Multiple projection measurements are performed by rotating the slab around the sample. The advantage of the proposed method is that the measured data can be much more easily fitted into the dynamic range of most commonly used detectors. At the same time, multiple projections improve image quality by mutually interchanging the depth and transverse directions, and the scanned (detection) and integrated (illumination) surfaces. Inversion methods are derived for image reconstructions with extremely large data sets. Numerical simulations are performed for fixed and rotated slabs

Interest Group Survival: Shared Interests Versus Competition for Resources

Population ecology theory on interest group populations is examined to determine the implications for group membership levels in the states. Using the assumptions of the competitive exclusion principle, it is hypothesized that relatively new interest groups should not directly compete for space, but should instead have a positive influence on each other's membership levels. A group's membership level should also be a function of space, energy, and political mobilization factors. Multiple regression analysis is applied to a fifty-state data set using the membership levels of five gay and lesbian interest groups as dependent variables. The hypotheses are confirmed—interest groups avoid direct competition for space by adapting into different issue niches. The results of these findings for a population ecology theory of interest groups are discussed along with directions for future research

The route and timing of hydrogen sulfide therapy critically impacts intestinal recovery following ischemia and reperfusion injury

PURPOSE: Hydrogen sulfide (H2S) has many beneficial properties and may serve as a novel treatment in patients suffering from intestinal ischemia-reperfusion injury (I/R). The purpose of this study was to examine the method of delivery and timing of administration of H2S for intestinal therapy during ischemic injury. We hypothesized that 1) route of administration of hydrogen sulfide would impact intestinal recovery following acute mesenteric ischemia and 2) preischemic H2S conditioning using the optimal mode of administration as determined above would provide superior protection compared to postischemic application. METHODS: Male C57BL/6J mice underwent intestinal ischemia by temporary occlusion of the superior mesenteric artery. Following ischemia, animals were treated according to one of the following (N=6 per group): intraperitoneal or intravenous injection of GYY4137 (H2S-releasing donor, 50mg/kg in PBS), vehicle, inhalation of oxygen only, inhalation of 80ppm hydrogen sulfide gas. Following 24-h recovery, perfusion was assessed via laser Doppler imaging, and animals were euthanized. Perfusion and histology data were assessed, and terminal ileum samples were analyzed for cytokine production following ischemia. Once the optimal route of administration was determined, preischemic conditioning with H2S was undertaken using that route of administration. All data were analyzed using Mann-Whitney. P-values <0.05 were significant. RESULTS: Mesenteric perfusion following intestinal I/R was superior in mice treated with intraperitoneal (IP) GYY4137 (IP vehicle: 25.6±6.0 vs. IP GYY4137: 79.7±15.1; p=0.02) or intravenous (IV) GYY4137 (IV vehicle: 36.3±5.9 vs. IV GYY4137: 100.7±34.0; p=0.03). This benefit was not observed with inhaled H2S gas (O2 vehicle: 66.6±11.4 vs. H2S gas: 81.8±6.0; p=0.31). However, histological architecture was only preserved with intraperitoneal administration of GYY4127 (IP vehicle: 3.4±0.4 vs. IP GYY4137: 2±0.3; p=0.02). Additionally, IP GYY4137 allowed for significant attenuation of inflammatory chemokine production of IL-6, IP-10 and MIP-2. We then analyzed whether there was a difference between pre- and postischemic administration of IP GYY4137. We found that preconditioning of animals with intraperitoneal GYY4137 only added minor improvements in outcomes compared to postischemic application. CONCLUSION: Therapeutic benefits of H2S are superior with intraperitoneal application of an H2S donor compared to other administration routes. Additionally, while intraperitoneal treatment in both the pre- and postischemic period is beneficial, preischemic application of an H2S donor was found to be slightly better. Further studies are needed to examine long term outcomes and further mechanisms of action prior to widespread clinical application. TYPE OF STUDY: Basic science. LEVEL OF EVIDENCE: N/A

Gun Policy, Opinion, Tragedy, and Blame Attribution: The Conditional Influence of Issue of Frames

This is the publisher's version, which is also available electronically from: http://dx.doi.org/10.1111/0022-3816.00077.Political events and policy discussion set parameters for debate and help to determine how an issue comes to be defined. Though existing research has examined the effects of alternative representations of political issues on public opinion, less attention has been given to highly salient issues, such as gun policy, and the potential effect of framing on causal attributions of blame for tragic events. This study expands the framing research to include opinion on policies concerning guns as well as the attributions of blame following the school shooting in Littleton, Colorado. We test several hypotheses using data from two field polls—one examining support for concealed handgun laws and the other examining blame attribution following the shootings at Columbine High School. We find that alternative gun frames influence opinion about concealed handgun laws as well as attributions of blame for Columbine. However, the effect is conditional, hinging on the nature of respondents’ predisposition and existing knowledge. We consider these findings within the context of the policy-making process. “The aftermath of that shooting . . . has had an even more profound impact on the country than all the school shootings last year did. And you can see it by what is happening in the Congress now.” —President Clinton referring to the impact of the Littleton, Colorado, school shootings on the gun policy debate (Sobieraj 1999) “I have to tell you, it’s amazing to us, there’s a whole lot of us going “Wow” . . . After all these school shootings we thought maybe we could get a discussion going, introduce some ideas, but this is tremendous.” —Janet Parshall of the Family Research Council after the House passed three religious amendments meant to reduce school violence following the Littleton shootings (Rosin 1999

The Role of Intersectional Stereotypes on Evaluations of Gay and Lesbian Political Candidates

This is the publisher's version, which is also available electronically from: http://dx.doi.org/10.1017/S1743923X09990511Social scientists are increasingly taking a more complex theoretical approach to the role of stereotyping in the electorate’s evaluation of political candidates.Within this literature, most studies investigate the impact of one stereotype on the public’s evaluation of candidates from an underrepresented group. We build on and extend this literature by exploring what we term “intersectional stereotyping”: The role of stereotypes in shaping the electorate’s evaluation of political candidates who share dual membership in stigmatized groups — women and sexual minorities. We empirically examine the impact of intersectional stereotyping in a unique 2003 survey of national adults. Our results indicate that gender, both of the respondent and the candidate, plays a key role in shaping attitudes toward gay and lesbian political candidates. These findings suggest that intersectional stereotyping plays a nuanced role in evaluations of candidates; in certain contexts gender stereotypes are more significant, and at other times stereotypes about sexual minorities appear to be driving evaluations of candidates