The Fiscal Impact of Urban Growth on Municipalities

In this paper, panel regression analysis is used to examine the fiscal impact of urban growth on per-capita or per-household expenditures of providing municipal services in the province of Ontario, Canada. Three variables are used to measure growth: households, population and assessment. Using a panel data set for 68 municipalities, we find that for the most part, urban growth has no effect on per-capita or per-household expenditures. The policy implications of these results are discussed

Determinants Of Residents Recycling Behaviour

Environmental concerns, combined with the scarcity of landfill sites have made recycling a more desirable alternative to traditional methods of garbage disposal. The purpose of the paper is to determine the factors that influence recycling behaviour. We also examine the socio-demographic characteristics of those who recycle. Logistic regression and means-end-based laddering techniques are used. The results of this research should be helpful in designing public campaigns to promote recycling

Theoretical and experimental investigations of passive and ultrasound-enhanced transdermal drug delivery

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, February 2007.Includes bibliographical references.In the initial investigation of this thesis, Fick's second law of diffusion was modified to describe both the transient, and the steady-state, transdermal transport of hydrophilic permeants through unbranched, aqueous pore channels. This new transport model, combined with dual radiolabeled diffusion experiments, was then used to separately evaluate how the porosity, the tortuosity, and the hindrance factor of the aqueous pore channels that exist in the skin varied as the extent of skin perturbation due to simultaneous treatment of the skin with low-frequency ultrasound (US) and a chemical enhancer, the surfactant sodium lauryl sulfate (SLS), and as the radius of the hydrophilic permeant delivered across the skin, were increased. This investigation revealed that the values of the hindrance factor and of the tortuosity decreased as the radius of the hydrophilic permeant increased, and that the value of the porosity of the aqueous pore channels increased as the extent of skin perturbation due to the application of US increased. This last result suggested that low-frequency US primarily enhances the transport of hydrophilic permeants by increasing the fraction of the skin surface occupied by the aqueous pore channels.(cont.) This modeling approach was next applied to the passive delivery of hydrophobic permeants through the branched pathways located in the intercellular lipid bilayer domain of untreated stratum corneum (SC), the outermost layer of the skin. The existence of these branched pathways led to the development of a new theoretical model, the Two-Tortuosity Model, which requires two tortuosity factors to account for: 1) the effective diffusion path length, and 2) the total volume of the branched, intercellular transport pathways, both of which may be evaluated from known values of the SC structure. After validating the Two-Tortuosity model with simulated SC diffusion experiments in FEMLAB (a finite element software package), the vehicle-bilayer partition coefficient, Kb, and the lipid bilayer diffusion coefficient, Db, in untreated human SC were evaluated using this new model for two hydrophobic permeants, naphthol (Kb = 233 + 44, Db = 1.6*10-7 + 0.3*10-7 cm2/s) and testosterone (Kb = 100 + 14, Db = 1.8*10-8 + 0.2*10-8 cm2/s). This investigation demonstrated that the new proposed method to evaluate Kb and Db is more direct than previous methods, in which SC permeation experiments were combined with octanol-water partition experiments, or with SC solute release experiments, to evaluate Kb and Db.(cont.) Previous studies on ultrasound-mediated transdermal drug delivery had hypothesized that the discrete regions which form on the surface of skin treated with low-frequency US in the presence of a colored permeant are regions of high permeability. To test this hypothesis, full-thickness pig skin was treated simultaneously with low-frequency US and SLS in the presence of a hydrophilic fluorescent permeant, sulforhodamine B (SRB), which was used to observe the location of the hypothesized localized transport regions (LTRs) and of the surrounding regions of US-treated skin (the non-LTRs). After US-pretreatment, diffusion masking experiments, a novel experimental method in which hydrophobic vacuum grease was selectively applied to the skin surface, demonstrated that the permeability of calcein, another hydrophilic fluorescent permeant, in the LTRs was -80-fold greater than in the non-LTRs. Furthermore, measurements of the skin electrical resistivity in both the LTRs and the non-LTRs revealed significant decreases relative to the skin electrical resistivity in untreated skin (-5000-fold and -170-fold, respectively), suggesting that two levels of significant structural perturbation exist in skin treated simultaneously with ultrasound and SLS.(cont.) Finally, an analysis of the porosity-to-tortuosity ratio values suggested that transcellular transdermal transport pathways exist within the LTRs. To confirm the results of the previous investigation, the transdermal delivery of SRB and of rhodamine B hexyl ester (RBHE), a fluorescent hydrophobic permeant, in skin treated with low-frequency ultrasound (US) and/or a chemical enhancer (SLS) relative to untreated skin (the control) was analyzed with dual-channel two-photon microscopy (TPM). An analysis of the average fluorescence intensity profiles as a function of skin depth, obtained from the TPM images, revealed that SRB and RBHE penetrated beyond the stratum corneum and into the viable epidermis only in the LTRs of US-treated and of US/SLS-treated skin. Further analysis of the average fluorescence intensity profiles and of the enhancements in the vehicle-skin partition coefficient, the intensity gradient, and the effective diffusion path length confirmed that a chemical enhancer was required in the coupling medium during US-treatment to obtain two significant levels of increased penetration of SRB and RBHE into the skin.(cont.) Finally, by comparing the heights and the widths of the fluorescence intensity peaks obtained from the dual-channel TPM images, the existence of transcellular pathways was confirmed in the LTRs of US-treated and of US/SLS-treated skin for SRB and RBHE, as well as in SLS-treated skin for SRB. In the final investigation of this thesis, the differences in the hindrance factor, the porosity, and the tortuosity of the aqueous pore channels located in the LTRs and in the non-LTRs were evaluated for the delivery of four hydrophilic permeants (urea, mannitol, raffinose, and inulin) using the transport model developed in the initial investigation of this thesis combined with dual radiolabeled diffusion masking experiments. In this analysis, three different idealized cases were examined. In the first case, where the porosity and the tortuosity were assumed to be independent of the permeant radius, the hindrance factor, and, therefore, the average pore radius, was found to be statistically larger in the LTRs than in the non-LTRs. In the second case, where a distribution of pore radii was assumed to exist in the skin, no meaningful results could be obtained due to the large variation in the shape of the distribution of pore radii used in the analysis.(cont.) In the final case, where infinitely large aqueous pores were assumed to exist in the skin, the value of the porosity of the LTRs was found to be 3- to 8-fold larger than that of the non-LTRs, while there little difference was found in the values of the tortuosity of the LTRs and of the non-LTRs.by Joseph Kushner, IV.Ph.D

Dual-Channel Two-Photon Microscopy Study of Transdermal Transport in Skin Treated with Low-Frequency Ultrasound and a Chemical Enhancer

Visualization of transdermal permeant pathways is necessary to substantiate model-based conclusions drawn using permeability data. The aim of this investigation was to visualize the transdermal delivery of sulforhodamine B (SRB), a fluorescent hydrophilic permeant, and of rhodamine B hexyl ester (RBHE), a fluorescent hydrophobic permeant, using dual-channel two-photon microscopy (TPM) to better understand the transport pathways and the mechanisms of enhancement in skin treated with low-frequency ultrasound (US) and/or a chemical enhancer (sodium lauryl sulfate – SLS) relative to untreated skin (the control). The results demonstrate that (1) both SRB and RBHE penetrate beyond the stratum corneum and into the viable epidermis only in discrete regions (localized transport regions – LTRs) of US treated and of US/SLS-treated skin, (2) a chemical enhancer is required in the coupling medium during US treatment to obtain two significant levels of increased penetration of SRB and RBHE in US-treated skin relative to untreated skin, and (3) transcellular pathways are present in the LTRs of US treated and of US/SLS-treated skin for SRB and RBHE, and in SLS-treated skin for SRB. In summary, the skin is greatly perturbed in the LTRs of US treated and US/SLS-treated skin with chemical enhancers playing a significant role in US-mediated transdermal drug delivery

Simulation of Sweep-Jet Flow Control, Single Jet and Full Vertical Tail

This work is a simulation technology demonstrator, of sweep jet flow control used to suppress boundary layer separation and increase the maximum achievable load coefficients. A sweep jet is a discrete Coanda jet that oscillates in the plane parallel to an aerodynamic surface. It injects mass and momentum in the approximate streamwise direction. It also generates turbulent eddies at the oscillation frequency, which are typically large relative to the scales of boundary layer turbulence, and which augment mixing across the boundary layer to attack flow separation. Simulations of a fluidic oscillator, the sweep jet emerging from a nozzle downstream of the oscillator, and an array of sweep jets which suppresses boundary layer separation are performed. Simulation results are compared to data from a dedicated validation experiment of a single oscillator and its sweep jet, and from a wind tunnel test of a full-scale Boeing 757 vertical tail augmented with an array of sweep jets. A critical step in the work is the development of realistic time-dependent sweep jet inflow boundary conditions, derived from the results of the single-oscillator simulations, which create the sweep jets in the full-tail simulations. Simulations were performed using the computational fluid dynamics (CFD) solver Overow, with high-order spatial discretization and a range of turbulence modeling. Good results were obtained for all flows simulated, when suitable turbulence modeling was used

The Conventional Wisdom about Cross-Haul

Current proponents of neoclassical analysis sometimes exclude imperfect competition as a serious explanation of certain pricing behavior. The authors in this paper focus on the 1981 Southern Plywood antitrust litigation demonstrating that behavior from that case is readily explained within a traditional monopoly/basing-point pricing model whereas alternative economic explanations claiming price-taking behavior must rely upon external explanatory factors. The authors suggest a simple algebraic model to facilitate distinguishing whether observed pricing is or is not consistent with a price-taking explanation.

Geometry of jet spaces and integrable systems

An overview of some recent results on the geometry of partial differential equations in application to integrable systems is given. Lagrangian and Hamiltonian formalism both in the free case (on the space of infinite jets) and with constraints (on a PDE) are discussed. Analogs of tangent and cotangent bundles to a differential equation are introduced and the variational Schouten bracket is defined. General theoretical constructions are illustrated by a series of examples.Comment: 54 pages; v2-v6 : minor correction

ACC/AHA Guidelines for the Management of Patients With ST-Elevation Myocardial Infarction—Executive Summary A Report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Writing Committee to Revise the 1999 Guidelines for the Management of Patients With Acute Myocardial Infarction)

Although considerable improvement has occurred in the process of care for patients with ST-elevation myocardial infarction (STEMI), room for improvement exists (1–3). The purpose of the present guideline is to focus on the numerous advances in the diagnosis and management of patients with STEMI since 1999. This is reflected in the changed name of the guideline: “ACC/AHA Guidelines for the Management of Patients With ST-Elevation Myocardial Infarction.” The final recommendations for indications for a diagnostic procedure, a particular therapy, or an intervention in patients with STEMI summarize both clinical evidence and expert opinion (Table 1).To provide clinicians with a set of recommendations that can easily be translated into the practice of caring for patients with STEMI, this guideline is organized around the chronology of the interface between the patient and the clinician. The full guideline is available at http://www.acc.org/clinical/guidelines/stemi/index.htm