Maximal Height Scaling of Kinetically Growing Surfaces

The scaling properties of the maximal height of a growing self-affine surface with a lateral extent $L$ are considered. In the late-time regime its value measured relative to the evolving average height scales like the roughness: $h^{*}_{L} \sim L^{\alpha}$. For large values its distribution obeys $\log{P(h^{*}_{L})} \sim -A({h^{*}_{L}}/L^{\alpha})^{a}$, charaterized by the exponential-tail exponent $a$. In the early-time regime where the roughness grows as $t^{\beta}$, we find $h^{*}_{L} \sim t^{\beta}[\ln{L}-({\beta\over \alpha})\ln{t} + C]^{1/b}$ where either $b=a$ or $b$ is the corresponding exponent of the velocity distribution. These properties are derived from scaling and extreme-values arguments. They are corroborated by numerical simulations and supported by exact results for surfaces in 1D with the asymptotic behavior of a Brownian path.Comment: One reference added. Minor stylistic changes in the abstarct and the paper. 4 pages, 3 figure

HIV-1 Transgenic Rat: Selective Alterations In Motivation And Histological Examination Of Medium Spiny Neurons Of The Nucleus Accumbens

Motivational alterations in HIV-1+ individuals are associated with decreased performance on tasks involving frontal-subcortical circuitry and the nucleus accumbens. In the present study, the HIV-1 transgenic (Tg) rat was used to assess long-term HIV-1 viral protein exposure on motivated behavior using activity chambers (40x40cm) and voluntary wheel running. Adult ovariectomized female HIV-1 Tg animals (n=21) to F344 controls (n=26) were pair-housed under a 12:12 light/dark cycle. Voluntary running was measured with 34 cm-diameter running wheels for ~60 minutes/day for 3 ½ months. There were no significant differences between HIV-1 Tg and F344 control rats in voluntary wheel running during the light phase. Animals were subsequently run in the nocturnal phase of their light/dark cycle. The F344 controls continued to escalate their overall running distances and surpassed the stabilized HIV-1 Tg group after ~4 weeks of nocturnal running, until reaching their asymptotic plateau at week 11. Neither maximal running speed, nor the latency to initiate running or running bout length were significantly different between groups. However, the groups were different in the number of running bouts per session, as a function of the HIV-1 transgene. Collectively, the selective alterations in the motivation for voluntary wheel running and activity chamber locomotor activity, suggests a disruption of the motivational circuitry within the HIV-1 Tg rat brain. Examination of Medium Spiny Neurons of the nucleus accumbens showed significant alterations in dendritic spine length and spine head diameter. Further study of these alterations in spine parameters may help elucidate the mechanisms of motivational alterations in HIV-1+individuals

The contact process on finite homogeneous trees revisited

We consider the contact process with infection rate $\lambda$ on $\mathbb{T}_n^d$, the $d$-ary tree of height $n$. We study the extinction time $\tau_{\mathbb{T}_n^d}$, that is, the random time it takes for the infection to disappear when the process is started from full occupancy. We prove two conjectures of Stacey regarding $\tau_{\mathbb{T}_n^d}$. Let $\lambda_2$ denote the upper critical value for the contact process on the infinite $d$-ary tree. First, if $\lambda < \lambda_2$, then $\tau_{\mathbb{T}_n^d}$ divided by the height of the tree converges in probability, as $n \to \infty$, to a positive constant. Second, if $\lambda > \lambda_2$, then $\log \mathbb{E}[\tau_{\mathbb{T}_n^d}]$ divided by the volume of the tree converges in probability to a positive constant, and $\tau_{\mathbb{T}_n^d}/\mathbb{E}[\tau_{\mathbb{T}_n^d}]$ converges in distribution to the exponential distribution of mean 1.Comment: 22 pages, 1 figur

Overlaps and Pathwise Localization in the Anderson Polymer Model

We consider large time behavior of typical paths under the Anderson polymer measure. If $P$ is the measure induced by rate $\kappa,$ simple, symmetric random walk on $Z^d$ started at $x,$ this measure is defined as d\mu(X)={Z^{-1} \exp\{\beta\int_0^T dW_{X(s)}(s)\}dP(X) where $\{W_x:x\in Z^d\}$ is a field of $iid$ standard, one-dimensional Brownian motions, $\beta>0, \kappa>0$ and $Z$ the normalizing constant. We establish that the polymer measure gives a macroscopic mass to a small neighborhood of a typical path as $T \to \infty$, for parameter values outside the perturbative regime of the random walk, giving a pathwise approach to polymer localization, in contrast with existing results. The localization becomes complete as $\frac{\beta^2}{\kappa}\to\infty$ in the sense that the mass grows to 1. The proof makes use of the overlap between two independent samples drawn under the Gibbs measure $\mu$, which can be estimated by the integration by parts formula for the Gaussian environment. Conditioning this measure on the number of jumps, we obtain a canonical measure which already shows scaling properties, thermodynamic limits, and decoupling of the parameters

Integrating direct messaging with flood alerts and warnings:insights into effectiveness from a registered public user population

Direct messaging involving simultaneous mass transmission of brief text or voice messages to large numbers of recipients has become a frontline method in flood hazard communications. Messages are intended to serve as cues, drawing recipients' attention to changing conditions, yet the actual effectiveness of direct messaging among recipient groups remains under-examined. This article considers direct messaging within the Floodline public flood warning service in Scotland, implemented by the Scottish Environment Protection Agency (SEPA). Within Floodline, messaging is integrated with alerting and warning information, termed straightforwardly ‘Flood Alerts’ and ‘Flood Warnings’. Collaborating with SEPA, we conducted an online questionnaire survey of registered Floodline direct messaging recipients. In this article, our analysis focusses specifically on responses to three open-ended questions included in this survey, with an iterative qualitative coding approach employed to interpret themes of meaning from the question responses. This analysis gives a clear indication that recipients value Floodline and direct messaging. However, there are also questions raised over the utility of Flood Alerts and related messaging, which we elaborate in the findings and discussion, along with the scope for adding content, linking to other information, and developing closer relationships. Changes being developed by SEPA align with several of these findings.</p

Integrating direct messaging with flood alerts and warnings:insights into effectiveness from a registered public user population

Direct messaging involving simultaneous mass transmission of brief text or voice messages to large numbers of recipients has become a frontline method in flood hazard communications. Messages are intended to serve as cues, drawing recipients' attention to changing conditions, yet the actual effectiveness of direct messaging among recipient groups remains under-examined. This article considers direct messaging within the Floodline public flood warning service in Scotland, implemented by the Scottish Environment Protection Agency (SEPA). Within Floodline, messaging is integrated with alerting and warning information, termed straightforwardly ‘Flood Alerts’ and ‘Flood Warnings’. Collaborating with SEPA, we conducted an online questionnaire survey of registered Floodline direct messaging recipients. In this article, our analysis focusses specifically on responses to three open-ended questions included in this survey, with an iterative qualitative coding approach employed to interpret themes of meaning from the question responses. This analysis gives a clear indication that recipients value Floodline and direct messaging. However, there are also questions raised over the utility of Flood Alerts and related messaging, which we elaborate in the findings and discussion, along with the scope for adding content, linking to other information, and developing closer relationships. Changes being developed by SEPA align with several of these findings.</p