The Commercial Structure of Pedestrian Streets and Shopping Districts - Three Cases from Finland

Kävelykadut ovat tunnustettu tapa elävöittää keskusta-alueiden kauppaa. Aluksi moni kauppias epäilee kävelykadun tuomia muutoksia, mutta kokemus osoittaa, että kävelykadut ovat olleet menestyksekkäitä ja nostavat siellä olevien yritysten myyntiä. Jotkut yritykset eivät kuitenkin hyödy kävelykaduista, kun taas toiset hyötyvät paljon kun katu muuttuu kävelykaduksi. Tämä pro gradu -tutkielma tutkii kävelykatujen kaupallista rakennetta, jotta saataisiin selville minkätyyppiset yritykset löytyvät kävelykadulta. Tuloksia verrataan sen kaupallisen keskusvyöhykkeen kaupalliseen rakenteeseen missä kävelykatu sijaitsee. Näin saadaan selville erot kaupallisessa rakenteessa. Pro gradu tutkii myös miten tavallisia ketjuyritykset ovat kävelykaduilla ja kaupallisissa keskusvyöhykkeissä. Tutkimusaineisto koottiin kaupallisen inventoinnin avulla, joka suoritettiin kolmessa suomalaisessa kaupungissa: Tammisaaressa, Keravalla ja Porissa. Saatu aineisto luokiteltiin ja tulokset piirrettiin kartalle. Perustilastollisia menetelmiä käytettiin tulosten analysoimisessa. Tulokset eriteltiin kävelykadun, kauppakeskusten ja muiden paikkojen osalta ja luokiteltiin yleisluokkiin vähittäiskauppa, ravintola ja muu palvelu. Tulokset näyttävät, että on olemassa selkeitä eroja kun vertaa kävelykatuja ja kaupallisia keskusvyöhykkeitä. Kävelykaduilla on paljon enemmän vähittäiskauppoja, etenkin muotikauppoja, kuin muilla kaduilla. Kauppakeskuksilla on samantapainen kaupallinen rakenne kuin kävelykaduilla kun taas muilla kaduilla esiintyy vähemmän vähittäiskauppoja ja enemmän palveluyrityksiä. Ravintolat ovat melkein yhtä tavallisia koko kaupallisessa keskusvyöhykkeessä. Ketjuyritysten osalta tulokset ovat epäselviä. On olemassa osviittaa siitä, että ne ovat tavallisempia kävelykaduilla, etenkin suurissa kaupungeissa. Saatua tulosta ei ole kuitenkin tarpeeksi, jotta varmaa tietoa olisi saatu. Viimeisten 10–15 vuoden ajan Suomen kävelykadut ovat muuttuneet enemmän ravintolavaltaisiksi muiden palveluiden kustannuksella. Vähittäiskauppojen määrä on pysynyt vakaana. Suomalaiset kävelykadut eroavat kaupalliselta rakenteeltaan pohjoismaisista kävelykaduista, joilla on enemmän vähittäiskauppoja ja vähemmän palveluyrityksiä. Tapauskohtaisissa tuloksissa esiintyy paljon eroavaisuuksia. Paikalliset tekijät ovat usein voimakkaampia kuin yleiset teoriat kauppojen sijainnista kävelykaduilla. Yleisesti ottaen tulokset tukevat teoreettista viitekehystä. Tulokset antavat tarkempaa tietoa kävelykatujen ja kaupallisten keskusvyöhykkeiden kaupallisesta rakenteesta ja siitä, mitkä tekijät tähän vaikuttaa.

Can one electrochemically measure the statistical morphology of a rough electrode

We have developed a theory for an electrochemical way of measuring the statistical properties of a nonfractally rough electrode. We obtained the expression for the current transient on a rough electrode which shows three times regions: short and long time limits and the transition region between them. The expressions for these time ranges are exploited to extract morphological information about the surface roughness. In the short and long time regimes, we extract information regarding various morphological features like the roughness factor, average roughness, curvature, correlation length, dimensionality of roughness, and polynomial approximation for the correlation function. The formulas for the surface structure factors (the measure of surface roughness) of rough surfaces in terms of measured reversible and diffusion-limited current transients are also obtained. Finally, we explore the feasibility of making such measurements.

Monte-Carlo estimation of time-dependent statistical characteristics of random dynamical systems

The problem of estimating the time-dependent statistical characteristics of a random dynamical system is studied under two different settings. In the first, the system dynamics is governed by a differential equation parameterized by a random parameter, while in the second, this is governed by a differential equation with an underlying parameter sequence characterized by a continuous time Markov chain. We propose, for the first time in the literature, stochastic approximation algorithms for estimating various time-dependent process characteristics of the system. In particular, we provide efficient estimators for quantities such as the mean, variance and distribution of the process at any given time as well as the joint distribution and the autocorrelation coefficient at different times. A novel aspect of our approach is that we assume that information on the parameter model (i.e., its distribution in the first case and transition probabilities of the Markov chain in the second) is not available in either case. This is unlike most other work in the literature that assumes availability of such information. Also, most of the prior work in the literature is geared towards analyzing the steady-state system behavior of the random dynamical system while our focus is on analyzing the time-dependent statistical characteristics which are in general difficult to obtain. We prove the almost sure convergence of our stochastic approximation scheme in each case to the true value of the quantity being estimated. We provide a general class of strongly consistent estimators for the aforementioned statistical quantities with regular sample average estimators being a specific instance of these. We also present an application of the proposed scheme on a widely used model in population biology. Numerical experiments in this framework show that the time-dependent process characteristics as obtained using our algorithm in each case exhibit excellent agreement with exact results. (C) 2010 Elsevier Inc. All rights reserved.

Statistical thermodynamics of lattice models in zeolites: Implications of local versus global mean field interactions

The statistical thermodynamics of adsorption in caged zeolites is developed by treating the zeolite as an ensemble of M identical cages or subsystems. Within each cage adsorption is assumed to occur onto a lattice of n identical sites. Expressions for the average occupancy per cage are obtained by minimizing the Helmholtz free energy in the canonical ensemble subject to the constraints of constant M and constant number of adsorbates N. Adsorbate-adsorbate interactions in the Brag-Williams or mean field approximation are treated in two ways. The local mean field approximation (LMFA) is based on the local cage occupancy and the global mean field approximation (GMFA) is based on the average coverage of the ensemble. The GMFA is shown to be equivalent in formulation to treating the zeolite as a collection of interacting single site subsystems. In contrast, the treatment in the LMFA retains the description of the zeolite as an ensemble of identical cages, whose thermodynamic properties are conveniently derived in the grand canonical ensemble. For a z coordinated lattice within the zeolite cage, with epsilon(aa) as the adsorbate-adsorbate interaction parameter, the comparisons for different values of epsilon(aa)(*)=epsilon(aa)z/2kT, and number of sites per cage, n, illustrate that for -1 0. We compare the isotherms predicted with the LMFA with previous GMFA predictions [K. G. Ayappa, C. R. Kamala, and T. A. Abinandanan, J. Chem. Phys. 110, 8714 (1999)] (which incorporates both the site volume reduction and a coverage-dependent epsilon(aa)) for xenon and methane in zeolite NaA. In all cases the predicted isotherms are very similar, with the exception of a small steplike feature present in the LMFA for xenon at higher coverages. (C) 1999 American Institute of Physics. [S0021-9606(99)70333-8].

PRUNE and PROBE-two modular web services for protein-protein docking

The protein-protein docking programs typically perform four major tasks: (i) generation of docking poses, (ii) selecting a subset of poses, (iii) their structural refinement and (iv) scoring, ranking for the final assessment of the true quaternary structure. Although the tasks can be integrated or performed in a serial order, they are by nature modular, allowing an opportunity to substitute one algorithm with another. We have implemented two modular web services, (i) PRUNE: to select a subset of docking poses generated during sampling search (http://pallab.serc.iisc.ernet.in/prune) and (ii) PROBE: to refine, score and rank them (http://pallab.serc.iisc.ernet.in/probe). The former uses a new interface area based edge-scoring function to eliminate > 95% of the poses generated during docking search. In contrast to other multi-parameter-based screening functions, this single parameter based elimination reduces the computational time significantly, in addition to increasing the chances of selecting native-like models in the top rank list. The PROBE server performs ranking of pruned poses, after structure refinement and scoring using a regression model for geometric compatibility, and normalized interaction energy. While web-service similar to PROBE is infrequent, no web-service akin to PRUNE has been described before. Both the servers are publicly accessible and free for use.

An investigation into the feasibility of fetal lung maturity prediction using statistical textural features

Fetal lung and liver tissues were examined by ultrasound in 240 subjects during 24 to 38 weeks of gestational age in order to investigate the feasibility of predicting the maturity of the lung from the textural features of sonograms. A region of interest of 64 X 64 pixels is used for extracting textural features. Since the histological properties of the liver are claimed to remain constant with respect to gestational age, features obtained from the lung region are compared with those from liver. Though the mean values of some of the features show a specific trend with respect to gestation age, the variance is too high to guarantee definite prediction of the gestational age. Thus, we restricted our purview to an investigation into the feasibility of fetal lung maturity prediction using statistical textural features. Out of 64 features extracted, those features that are correlated with gestation age and less computationally intensive are selected. The results of our study show that the sonographic features hold some promise in determining whether the fetal lung is mature or immature.

Efficient statistical modeling for the compression of tree structured intermediate code

We propose a scheme for the compression of tree structured intermediate code consisting of a sequence of trees specified by a regular tree grammar. The scheme is based on arithmetic coding, and the model that works in conjunction with the coder is automatically generated from the syntactical specification of the tree language. Experiments on data sets consisting of intermediate code trees yield compression ratios ranging from 2.5 to 8, for file sizes ranging from 167 bytes to 1 megabyte.

Voltage and Temperature Scalable Standard Cell Leakage Models Based on Stacks for Statistical Leakage Characterization

With extensive use of dynamic voltage scaling (DVS) there is increasing need for voltage scalable models. Similarly, leakage being very sensitive to temperature motivates the need for a temperature scalable model as well. We characterize standard cell libraries for statistical leakage analysis based on models for transistor stacks. Modeling stacks has the advantage of using a single model across many gates there by reducing the number of models that need to be characterized. Our experiments on 15 different gates show that we needed only 23 models to predict the leakage across 126 input vector combinations. We investigate the use of neural networks for the combined PVT model, for the stacks, which can capture the effect of inter die, intra gate variations, supply voltage(0.6-1.2 V) and temperature (0 - 100degC) on leakage. Results show that neural network based stack models can predict the PDF of leakage current across supply voltage and temperature accurately with the average error in mean being less than 2% and that in standard deviation being less than 5% across a range of voltage, temperature.