Organizational Purchasing Theory: A Review and Assessment

Mark C. Hall is an Associate Professor in the Department of Marketing at Mankato State University. C.P. Rao is University Professor in the Department of Marketing at the University of Arkansas. Kevin M. Elliott is an Associate Professor in the Department of Marketing at Mankato State University

Intrauterine growth restriction is associated with persistent juxtamedullary expression of renin in the fetal kidney

Intrauterine growth restriction is associated with persistent juxtamedullary expression of renin in the fetal kidney.BackgroundIntrauterine growth restriction (IUGR) has been linked to impaired renal function and hypertension, suggesting that an adverse prenatal environment could alter kidney development and renin production.MethodsImmunohistochemistry and in situ hybridization were employed to localize renin-containing cells (RCCs) in the deep, middle, and superficial zones of autopsy kidney sections, in parallel with histologic maturation, from unexplained stillborn fetuses of normal weight (N = 26) and stillborn fetuses with IUGR (N = 17).ResultsIn the control group, the number of RCC per 100 glomeruli in the deep zone decreased with advancing gestation from 40 at 20weeks gestation to five at term (P < 0.001), whereas the opposite change was found in the superficial zone (increase from 5 per 100 to 55 per 100; P < 0.001). In the IUGR group, the density of RCCs in both the superficial and deep zones was similar to the control group at 20weeks, and no shift in renin gene expression was observed as gestation advanced. Histologic maturation was unaltered.ConclusionsRenin gene expression persists and predominates in the deep renal cortex of the stillborn IUGR fetus, and could contribute to the pathogenesis of neonatal oliguria and/or hypertension during postnatal life

Microscopic theory of single-electron tunneling through molecular-assembled metallic nanoparticles

We present a microscopic theory of single-electron tunneling through metallic nanoparticles connected to the electrodes through molecular bridges. It combines the theory of electron transport through molecular junctions with the description of the charging dynamics on the nanoparticles. We apply the theory to study single-electron tunneling through a gold nanoparticle connected to the gold electrodes through two representative benzene-based molecules. We calculate the background charge on the nanoparticle induced by the charge transfer between the nanoparticle and linker molecules, the capacitance and resistance of molecular junction using a first-principles based Non-Equilibrium Green's Function theory. We demonstrate the variety of transport characteristics that can be achieved through ``engineering'' of the metal-molecule interaction.Comment: To appear in Phys. Rev.

Collisions of Cosmic F- and D-strings

Recent work suggests that fundamental and Dirichlet strings, and their (p,q) bound states, may be observed as cosmic strings. The evolution of cosmic string networks, and therefore their observational signals, depends on what happens when two strings collide. We study this in string perturbation theory for collisions between all possible pairs of strings; different cases involve sphere, disk, and annulus amplitudes. The result also depends on the details of compactification; the dependence on ratios of scales is only logarithmic, but this is still numerically important. We study a range of models and parameters, and find that in most cases these strings can be distinguished from cosmic strings that arise as gauge theory solitons.Comment: 42 pages, 7 figures; v.2: added references, expanded discussion of reconnection in field theor

Black Hole Dynamics From Atmospheric Science

In this note, we derive (to third order in derivatives of the fluid velocity) a 2+1 dimensional theory of fluid dynamics that governs the evolution of generic long-wavelength perturbations of a black brane or large black hole in four-dimensional gravity with negative cosmological constant, applying a systematic procedure developed recently by Bhattacharyya, Hubeny, Minwalla, and Rangamani. In the regime of validity of the fluid-dynamical description, the black-brane evolution will generically correspond to a turbulent flow. Turbulence in 2+1 dimensions has been well studied analytically, numerically, experimentally, and observationally as it provides a first approximation to the large scale dynamics of planetary atmospheres. These studies reveal dramatic differences between fluid flows in 2+1 and 3+1 dimensions, suggesting that the dynamics of perturbed four and five dimensional large AdS black holes may be qualitatively different. However, further investigation is required to understand whether these qualitative differences exist in the regime of fluid dynamics relevant to black hole dynamics.Comment: 16 pages, LaTeX, v2: caveat regarding relativistic vs non-relativistic fluids added v3: typos correcte

Integration of computational modeling with membrane transport studies reveals new insights into amino acid exchange transport mechanisms

Uptake of system L amino acid substrates into isolated placental plasma membrane vesicles in the absence of opposing side amino acid (zero-trans uptake) is incompatible with the concept of obligatory exchange, where influx of amino acid is coupled to efflux. We therefore hypothesized that system L amino acid exchange transporters are not fully obligatory and/or that amino acids are initially present inside the vesicles. To address this, we combined computational modeling with vesicle transport assays and transporter localization studies to investigate the mechanism(s) mediating [14C]L-serine (a system L substrate) transport into human placental microvillous plasma membrane (MVM) vesicles. The carrier model provided a quantitative framework to test the 2 hypotheses that L-serine transport occurs by either obligate exchange or nonobligate exchange coupled with facilitated transport (mixed transport model). The computational model could only account for experimental [14C]L-serine uptake data when the transporter was not exclusively in exchange mode, best described by the mixed transport model. MVM vesicle isolates contained endogenous amino acids allowing for potential contribution to zero-trans uptake. Both L-type amino acid transporter (LAT)1 and LAT2 subtypes of system L were distributed to MVM, with L-serine transport attributed to LAT2. These findings suggest that exchange transporters do not function exclusively as obligate exchangers.—Widdows, K. L., Panitchob, N., Crocker, I. P., Please, C. P., Hanson, M. A., Sibley, C. P., Johnstone, E. D., Sengers, B. G., Lewis, R. M., Glazier, J. D. Integration of computational modeling with membrane transport studies reveals new insights into amino acid exchange transport mechanisms

Cost-Effectiveness of Including a Nurse Specialist in the Treatment of Urinary Incontinence in Primary Care in the Netherlands.

#### Objective Incontinence is an important health problem. Effectively treating incontinence could lead to important health gains in patients and caregivers. Management of incontinence is currently suboptimal, especially in elderly patients. To optimise the provision of incontinence care a global optimum continence service specification (OCSS) was developed. The current study evaluates the costs and effects of implementing this OCSS for community-dwelling patients older than 65 years with four or more chronic diseases in the Netherlands. #### Method A decision analytic model was developed comparing the current care pathway for urinary incontinence in the Netherlands with the pathway as described in the OCSS. The new care strategy was operationalised as the appointment of a continence nurse specialist (NS) located with the general practitioner (GP). This was assumed to increase case detection and to include initial assessment and treatment by the NS. The analysis used a societal perspective, including medical costs, containment products (out-of-pocket and paid by insurer), home care, informal care, and implementation costs. #### Results With the new care strategy a QALY gain of 0.005 per patient is achieved while saving €402 per patient over a 3 year period from a societal perspective. In interpreting these findings it is important to realise that many patients are undetected, even in the new care situation (36%), or receive care for containment only. In both of these groups no health gains were achieved. #### Conclusion Implementing the OCSS in the Netherlands by locating a NS in the GP practice is likely to reduce incontinence, improve quality of life, and reduce costs. Furth

Modelling approaches to the dewetting of evaporating thin films of nanoparticle suspensions

We review recent experiments on dewetting thin films of evaporating colloidal nanoparticle suspensions (nanofluids) and discuss several theoretical approaches to describe the ongoing processes including coupled transport and phase changes. These approaches range from microscopic discrete stochastic theories to mesoscopic continuous deterministic descriptions. In particular, we describe (i) a microscopic kinetic Monte Carlo model, (ii) a dynamical density functional theory and (iii) a hydrodynamic thin film model. Models (i) and (ii) are employed to discuss the formation of polygonal networks, spinodal and branched structures resulting from the dewetting of an ultrathin ‘postcursor film’ that remains behind a mesoscopic dewetting front. We highlight, in particular, the presence of a transverse instability in the evaporative dewetting front, which results in highly branched fingering structures. The subtle interplay of decomposition in the film and contact line motion is discussed. Finally, we discuss a simple thin film model (iii) of the hydrodynamics on the mesoscale. We employ coupled evolution equations for the film thickness profile and mean particle concentration. The model is used to discuss the self-pinning and depinning of a contact line related to the ‘coffee-stain’ effect. In the course of the review we discuss the advantages and limitations of the different theories, as well as possible future developments and extensions

Magnetic fields in protoplanetary disks

Magnetic fields likely play a key role in the dynamics and evolution of protoplanetary discs. They have the potential to efficiently transport angular momentum by MHD turbulence or via the magnetocentrifugal acceleration of outflows from the disk surface, and magnetically-driven mixing has implications for disk chemistry and evolution of the grain population. However, the weak ionisation of protoplanetary discs means that magnetic fields may not be able to effectively couple to the matter. I present calculations of the ionisation equilibrium and magnetic diffusivity as a function of height from the disk midplane at radii of 1 and 5 AU. Dust grains tend to suppress magnetic coupling by soaking up electrons and ions from the gas phase and reducing the conductivity of the gas by many orders of magnitude. However, once grains have grown to a few microns in size their effect starts to wane and magnetic fields can begin to couple to the gas even at the disk midplane. Because ions are generally decoupled from the magnetic field by neutral collisions while electrons are not, the Hall effect tends to dominate the diffusion of the magnetic field when it is able to partially couple to the gas. For a standard population of 0.1 micron grains the active surface layers have a combined column of about 2 g/cm^2 at 1 AU; by the time grains have aggregated to 3 microns the active surface density is 80 g/cm^2. In the absence of grains, x-rays maintain magnetic coupling to 10% of the disk material at 1 AU (150 g/cm^2). At 5 AU the entire disk thickness becomes active once grains have aggregated to 1 micron in size.Comment: 11 pages, 11 figs, aastex.cls. Accepted for publication in Astrophysics & Space Science. v3 corrects bibliograph

Effect of HSV-1 Infection on the Exercise-induced Mobilization of T-cell Subsets

Acute exercise mobilizes highly-differentiated memory and senescent T-cells into the blood compartment, which could have important implications for post-exercise immune surveillance. This response differs in individuals with latent cytomegalovirus (CMV) infection (a herpesvirus), but it is unknown if other latent herpesviruses, such as herpes simplex virus type 1 (HSV-1), also influence this exercise-induced immune response. As HSV-1 infects 50% of the US population, this could have implications for many athletes. PURPOSE: To examine the effects of an acute bout of exercise on the frequency and relative proportion of naïve, memory, and senescent T-cells in the peripheral blood in HSV-1 infected and non-infected participants. METHODS: Eleven HSV-1-infected and twelve non-infected men (mean±SD: Age: 28±5 yrs; VO2max: 40.64±10.15 ml/kg/min) cycled at 85% of their estimated maximum power for 30 min. Blood samples were collected before and immediately after exercise, and mononuclear cells were isolated using density gradient centrifugation. Cells were labeled with monoclonal antibodies to identify naïve (CD28+CD57-KLRG1- or CD45RA+CCR7+), memory (CD28+CD57-KLRG1+, CD45RA+CCR7-, CD45RA-CCR7+, or CD45RA-CCR7-), and senescent (CD28-CD57+KLRG1+) subsets of CD3+CD4+ and CD3+CD8+ T-cells using four-color flow cytometry. HSV-1 serostatus was determined by an ELISA test. Main effects for exercise and serostatus, and exercise x serostatus interaction effects, were detected using maximum likelihood linear mixed models. RESULTS: A main effect for exercise was found on proportions of naïve (-8.82±8.49%), memory (+35.04±26.48%), and senescent (+64.12±56.12%) CD4+ T-cells, as well as on naïve (-21.02±11.56%) and senescent (+53.89±53.26%) CD8+ T-cells (p\u3c0.05). There were main effects for serostatus on proportions of memory CD4+ and CD8+ T-cells, with decreased levels in HSV-1+ subjects in all memory phenotypes examined (p\u3c0.05). Interaction effects between HSV-1 serostatus and exercise were found. HSV-1+ subjects had lower naïve cell counts, and a greater increase in the proportion of senescent cells, post-exercise (p\u3c0.05) than HSV-1-non-infected subjects. CONCLUSIONS: HSV-1 infection led to a decrease of memory T-cell subsets found in peripheral blood. It also influenced the relative response of naïve and senescent T-cells to acute exercise, although this effect was not nearly as great as that seen with other herpesviruses (i.e. CMV). This indicates that individuals with and without latent HSV-1 infection may have a different lymphocyte mobilization in response to exercise