bluuebunny/crossref_metadata_2025 huggingface dataset:
Microvascular permeability during experimental human endotoxemia: an open intervention study
Authors: van Eijk Lucas TGJ , Pickkers Peter , Smits Paul , Broek Wim van den , Bouw Martijn PWJM , van der Hoeven Johannes G
Published: February 2005

Introduction

Septic shock is associated with increased microvascular permeability. As a model for study of the pathophysiology of sepsis, endotoxin administration to humans has facilitated research into inflammation, coagulation and cardiovascular effects. The present study was undertaken to determine whether endotoxin administration to human volunteers can be used as a model to study the sepsis-associated increase in microvascular permeability.

Methods

In an open intervention study conducted in a university medical centre, 16 healthy volunteers were evaluated in the research unit of the intensive care unit. Eight were administered endotoxin intravenously (2 ng/kg Escherichia coli O113) and eight served as control individuals. Microvascular permeability was assessed before and 5 hours after the administration of endotoxin (n = 8) or placebo (n = 8) by three different methods: transcapillary escape rate of I125-albumin; venous occlusion strain-gauge plethysmography to determine the filtration capacity; and bioelectrical impedance analysis to determine the extracellular and total body water.

Results

Administration of endotoxin resulted in the expected increases in proinflammatory cytokines, temperature, flu-like symptoms and cardiovascular changes. All changes were significantly different from those in the control group. In the endotoxin group all microvascular permeability parameters remained unchanged from baseline: transcapillary escape rate of I125-albumin changed from 7.2 ± 0.6 to 7.7 ± 0.9%/hour; filtration capacity changed from 5.0 ± 0.3 to 4.2 ± 0.4 ml/min per 100 ml mmHg × 10-3; and extracellular/total body water changed from 0.42 ± 0.01 to 0.40 ± 0.01 l/l (all differences not significant).

Conclusion

Although experimental human endotoxaemia is frequently used as a model to study sepsis-associated pathophysiology, an endotoxin-induced increase in microvascular permeability in vivo could not be detected using three different methods. Endotoxin administration to human volunteers is not suitable as a model in which to study changes in microvascular permeability.
Uneven distribution of ventilation in acute respiratory distress syndrome
Authors: Rylander Christian , Tylén Ulf , Rossi-Norrlund Rauni , Herrmann Peter , Quintel Michael , Bake Björn
Published: February 2005

Introduction

The aim of this study was to assess the volume of gas being poorly ventilated or non-ventilated within the lungs of patients treated with mechanical ventilation and suffering from acute respiratory distress syndrome (ARDS).

Methods

A prospective, descriptive study was performed of 25 sedated and paralysed ARDS patients, mechanically ventilated with a positive end-expiratory pressure (PEEP) of 5 cmH2O in a multidisciplinary intensive care unit of a tertiary university hospital. The volume of poorly ventilated or non-ventilated gas was assumed to correspond to a difference between the ventilated gas volume, determined as the end-expiratory lung volume by rebreathing of sulphur hexafluoride (EELVSF6), and the total gas volume, calculated from computed tomography images in the end-expiratory position (EELVCT). The methods used were validated by similar measurements in 20 healthy subjects in whom no poorly ventilated or non-ventilated gas is expected to be found.

Results

EELVSF6 was 66% of EELVCT, corresponding to a mean difference of 0.71 litre. EELVSF6 and EELVCT were significantly correlated (r2 = 0.72; P < 0.001). In the healthy subjects, the two methods yielded almost identical results.

Conclusion

About one-third of the total pulmonary gas volume seems poorly ventilated or non-ventilated in sedated and paralysed ARDS patients when mechanically ventilated with a PEEP of 5 cmH2O. Uneven distribution of ventilation due to airway closure and/or obstruction is likely to be involved.
Flexible Hexagonal Tube Framework of a New Nickel Complex Assembled from Intermolecular Hydrogen Bonds
Authors: Kondo Mitsuru , Iwase Takahiro , Fuwa Yumiko , Horiba Tomonori , Miyazawa Makoto , Naito Tetsuyoshi , Maeda Kenji , Yasue Sachie , Uchida Fumio
Published: February 2005

A new nickel tubular framework compound, [Ni(ima)2(MeOH)2]·2MeOH (where ima = 4-imidazoleacetato) has been synthesized, in which the nonmethanolated complex, [Ni(ima)2], selectively reacts with methanol to reconstruct the initial porous framework, which can then incorporate other guest molecules.
Preparation of Aligned Amorphous Silica Nanowires
Authors: Xu Yajie , Cao Chuanbao , Zhang Bing , Zhu Hesun
Published: February 2005

Highly aligned amorphous silica nanowires were prepared on silicon substrate. The products were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS), and selected-area electron diffraction (SAED). The photoluminescence (PL) spectrum of silica nanowires showed strong blue emission peaked at 401 and 440 nm under 274 nm excitation wavelength. The growth mechanism of the nanowires was proposed.
Enzymatic Synthesis of Gold Nanoparticles Wrapped by Glucose Oxidase
Authors: Yasui Kei , Kimizuka Nobuo
Published: February 2005

An enzymatic synthesis route to protein-wrapped gold nanoparticles is developed. Glucose oxidase (GOD) reduces Au(III) ion in the presence of β-d-glucose, and stable gold nanoparticles with average diameter of 14.5 nm are formed. FT-IR spectra, zeta potential and CD spectra of purified nanoparticles indicate that they are stabilized by the adsorbed protein layer.
Quaternary Ammonium Dendrimers as Lewis Base Catalysts for Mukaiyama–Aldol Reaction
Authors: Mizugaki Tomoo , Hetrick Casey E , Murata Makoto , Ebitani Kohki , Amiridis Michael D , Kaneda Kiyotomi
Published: February 2005

Surface-alkylated poly(propylene imine) dendrimer was treated with methyl iodide to afford quaternarized ammonium iodide dendrimer. The quaternarized dendrimer catalyzed the Mukaiyama–Aldol reaction of trimethylsilyl acetal with various aldehydes as a Lewis base in apolar toluene solvent.
Fluorous Glycopeptide Synthesis without Protection of Sugar Hydroxy Groups
Authors: Mizuno Mamoru , Goto Kohtaro , Miura Tsuyoshi
Published: February 2005

The synthesis of a glycopeptide was easily achieved by an Fmoc-strategy based on fluorous chemistry. In this study, hCG(β12-16) having an N-acetylglucosamine was synthesized in good yield using Fmoc-Asn(GlcNAc)-OH without protection of the sugar hydroxy groups by the dimethylphosphinothioic mixed anhydride (Mpt-MA) method. Each synthetic intermediate was able to be easily purified by simple fluorous-organic solvent extraction and monitored by TLC, NMR, and MS.
Synthesis of Porous Nickel Oxide Nanofiber
Authors: Nakasa Akihiko , Suzuki Eiji , Usami Hisanao , Fujimatsu Hitoshi
Published: February 2005

Porous nickel oxide (NiO) nanofibers, structured with and composed of linearly oriented NiO nanoparticles, were synthesized via a simple method using a solution containing ethanol, H2O, NiCl2, and P123 (Pluronic P123, a triblock copolymer H(OCH2CH2)20(OCH(CH3)CH2)70(OCH2)20OH). By adjusting the concentration of P123, this method allows for the control of the fiber morphology and the nanoparticle size.
The simulation of the diurnal cycle of convective precipitation over land in a global model
Authors: Bechtold P. , Chaboureau J.‐P. , Beljaars A. , Betts A. K. , Köhler M. , Miller M. , Redelsperger J.‐L.
Published: February 2005

In the context of the European Cloud Systems project, the problem of the simulation of the diurnal cycle of convective precipitation over land is addressed with the aid of cloud‐resolving (CRM) and single‐column (SCM) model simulations of an idealized midlatitude case for which observations of large‐scale and surface forcing are available. The CRM results are compared to different versions of the European Centre for Medium‐Range Weather Forecasts (ECMWF) convection schemes using different convective trigger procedures and convective closures. In the CRM, maximum rainfall intensity occurs at 15 h (local time). In this idealized midlatitude case, most schemes do not reproduce the afternoon precipitation peak, as (i) they cannot reproduce the gradual growth (typically over 3 hours) of the deep convective cloud layer and (ii) they produce a diurnal cycle of precipitation that is in phase with the diurnal cycle of the convective available potential energy (CAPE) and the convective inhibition (CIN), consistent with the parcel theory and CAPE closure used in the bulk mass‐flux scheme. The scheme that links the triggering to the large‐scale vertical velocity gets the maximum precipitation at the right time, but this may be artificial as the vertical velocity is enforced in the single‐column context.

The study is then extended to the global scale using ensembles of 72‐hour global forecasts at resolution T511 (40 km), and long‐range single 40‐day forecasts at resolution T159 (125 km) with the ECMWF general‐circulation model. The focus is on tropical South America and Africa where the diurnal cycle is most pronounced. The forecasts are evaluated against analyses and observed radiosonde data, as well as observed surface and satellite‐derived rainfall rates. The ECMWF model version with improved convective trigger produces the smallest biases overall. It also shifts the rainfall maximum to 12 h compared to 9.5 h in the original version. In contrast to the SCM, the vertical‐velocity‐dependent trigger does not further improve the phase of the diurnal cycle. However, further work is necessary to match the observed 15 h precipitation peak. Copyright © 2004 Royal Meteorological Society
The sensitivity of a GCM's marine stratocumulus to cloud‐top entrainment
Authors: Lock A. P.
Published: February 2005

It appears that the Met Office general‐circulation model (GCM) represents stratocumulus over the northeast subtropical Pacific Ocean quite accurately—the mean cloud cover is realistically high, the observed mean and diurnal cycle of liquid‐water path is well represented and the capping inversion is at a reasonable height. This suggests that the boundary‐layer thermodynamic budget must also be well modelled. However, one of the dominant terms in this budget is cloud‐top entrainment, which is parametrized explicitly in this model, and is still the subject of much debate in the literature. In order to quantify the sensitivity of the GCM to this parametrization, the results of simulations applying three perturbations of entrainment formulation are presented. One change, to the enhancement of entrainment in the buoyancy‐reversal regime, is found to have little impact. The other two led to a significant reduction of the cloudiness in the stratocumulus area, giving worse agreement with observations. The first of these was to increase the parametrized entrainment rate by a factor of two. The second was to remove the coupling of the entrainment fluxes to the radiative and resolved advective fluxes, an aspect of the implementation previously found necessary to prevent serious numerical errors which generated spurious additional entrainment. It is further hypothesized that the numerical errors can be associated with a signal in the surface heat fluxes in the north‐east Pacific stratocumulus area. This signal can be seen in many other GCMs, suggesting that numerical problems associated with mixing across sharp inversions may be prevalent. © Crown copyright, 2004.
A buoyancy‐based mixing‐length proposal for cloudy boundary layers
Authors: Sáanchez E. , Cuxart J.
Published: February 2005

The parametrization of boundary‐layer clouds is approached here using a turbulence–kinetic energy closure, in conservative variables for non‐precipitating processes and through a new proposal for the turbulence mixing length. A subgrid condensation scheme able to treat partially saturated conditions in a model grid cell is also necessary. An extension of the buoyancy‐based Bougeault–Lacarrère mixing length is proposed, to take into account moist processes, and specifically the effects of phase changes. The asymmetry between upward and downward mixing processes is also considered for partial cloudiness conditions. The new proposal is tested for stratocumulus‐capped marine boundary layers and for shallow cumulus convection, both over land and sea. The validation ismade against large‐eddy simulation results obtained from model intercomparison cases, for stationary regimes as a first step, and then for the diurnal evolution of marine stratocumulus and shallow convection over land. Copyright © 2004 Royal Meteorological Society
The diurnal cycle of shallow cumulus clouds over land: A single‐column model intercomparison study
Authors: Lenderink Geert , Siebesma A. PIER , Cheinet Sylvain , Irons Sarah , Jones Colin G. , Marquet Pascal , üLLER Frank M , Olmeda Dolores , Calvo Javier , Sánchez Enrique , Soares Pedro M. M.
Published: February 2005

An intercomparison study for single‐column models (SCMs) of the diurnal cycle of shallow cumulus convection is reported. The case, based on measurements at the Atmospheric Radiation Measurement program Southern Great Plains site on 21 June 1997, has been used in a large‐eddy simulation intercomparison study before. Results of the SCMs reveal the following general deficiencies: too large values of cloud cover and cloud liquid water, unrealistic thermodynamic profiles, and high amounts of numerical noise. Results are also strongly dependent on vertical resolution.

These results are analysed in terms of the behaviour of the different parametrization schemes involved: the convection scheme, the turbulence scheme, and the cloud scheme. In general the behaviour of the SCMs can be grouped in two different classes: one class with too strong mixing by the turbulence scheme, the other class with too strong activity by the convection scheme. The coupling between (subcloud) turbulence and the convection scheme plays a crucial role. Finally, (in part) motivated by these results several models have been successfully updated with new parametrization schemes and/or their present schemes have been successfully modified. © Royal Meteorological Society, 2004. S. Irons's contribution is Crown copyright
Numerical simulation of the diurnal cycle of marine stratocumulus during FIRE—An LES and SCM modelling study
Authors: Chlond Andreas , Müller Frank , Sednev Igor
Published: February 2005

As part of the European Project on Cloud Systems in Climate Models (EUROCS), the stratocumulus‐topped boundary layer has been simulated using the Max Planck Institute Large‐Eddy Simulation (LES) model and the European Centre Hamburg Version Single Column Model (ECHAM–SCM). We have addressed the full diurnal cycle of stratocumulus off the coast of California based on observations of the First International Satellite Cloud Climatology Project Regional Experiment (FIRE). The results of the LES model demonstrate that the model is capable of reproducing the observed diurnal cycle of the boundary‐layer structure reasonably well. In particular, the LES model reproduces the distinct diurnal variation in liquid‐water path and of turbulence profiles due to the forcing imposed by the short‐wave heating of the cloud layer. In addition, we have examined the sensitivity of our LES results with respect to the assumed values of various external environmental conditions. We found that the largest contribution to the variance of the LES‐derived data products is due to the uncertainties in the cloud‐top jumps of liquid‐water potential temperature and total‐water mixing ratio and to the net radiative forcing.

To evaluate the quality of the representation of stratocumulus in a general circulation model, results from the standard ECHAM–SCM are contrasted with diagnostics from LES simulations. Results of the standard ECHAM–SCM reveal the following deficiencies: values of the liquid‐water path are too low, and unrealistically large levels of turbulent kinetic energy within the cloud layer are due to a numerical instability arising from a decoupling of radiative and diffusive processes. Based on these findings, the SCM has been revised. The modifications include the vertical advection scheme, the numerical treatment of diffusion and radiation, and the combination of the 1.5‐order turbulent closure model with an explicit entrainment closure at the boundary‐layer top in combination with a front tracking/capturing method. It is demonstrated that, with these modifications, the revised SCM produces a fair simulation of the diurnal cycle of the stratocumulus‐topped boundary layer which is significantly improved compared to the one performed with the standard SCM. Copyright © 2004 Royal Meteorological Society
Moisture–convection feedback in the tropics
Authors: Grabowski W. W. , Moncrieff M. W.
Published: February 2005

This paper discusses the large‐scale moisture–convection feedback in the tropics, where spatial fluctuations of deep convection cause perturbations of free‐tropospheric moisture which, in turn, affect the spatial distribution of deep convection. A simple heuristic argument using the timescale of free‐tropospheric humidity change explains why moisture–convection feedback is particularly relevant for tropical intraseasonal oscillations.

The large‐scale dynamical context for moisture–convection feedback is investigated in idealized rotating constant‐sea‐surface‐temperature (‘tropics everywhere’) aquaplanet using cloud‐resolving convection parametrization (CRCP; super‐parametrization) and a traditional convective parametrization (the Emanuel scheme). The large‐scale organization of convection within the equatorial waveguide takes the form of MJO‐like (Madden–Julian Oscillation) coherent structures. First, CRCP simulations are performed in which development of large‐scale free‐tropospheric moisture perturbations is artificially suppressed using relaxation with a timescale of one day. As in previous simulations where much shorter relaxation timescale was used, MJO‐like coherences do not develop and, if already present, they disintegrate rapidly. Second, CRCP simulations that start from planetary‐scale moisture perturbation in the free troposphere are conducted. The ensuing large‐scale velocity perturbations have e‐folding times of five and seven days, respectively, for interactive and prescribed radiation simulations. This supports the conjecture that interactive radiation enhances moisture–convection feedback; an enhanced large‐scale circulation results from differences in radiative cooling between areas having enhanced and suppressed convectively‐generated moisture and cloudiness. Additional support for the role of moisture–convection feedback in intraseasonal oscillations is seen in simulations that apply the Emanuel scheme. The standard configuration of the Emanuel scheme is insensitive to free‐tropospheric humidity and results in weak MJO‐like coherences. A simple modification of the Emanuel scheme that enhances its sensitivity to free‐tropospheric humidity dramatically improves the simulated MJO‐like coherences. Copyright © 2004 Royal Meteorological Society
The impacts of spatial variability on the development of convection
Authors: Stirling A. J. , Petch J. C.
Published: February 2005

A cloud‐resolving model is used to investigate the impact of spatial variability in moisture and temperature on the timing of deep convection over land. Using a simulation of a diurnal cycle of convection, horizontal variations in moisture and temperature are shown to have a significant impact on the development of convection. The onset of deep convection can change by several hours and total rainfall amounts can change by up to 70%.

Further sensitivity studies are carried out to investigate the impacts of vertical location, horizontal scale and magnitude of the variability. It is shown that variability of relative humidity in the boundary layer has the most significant impact and this is linked to its strong influence on local convective inhibition. Horizontal scales larger than 10 km are shown to have the strongest influence on the timing of convection, and the strongest amplitude of convectively generated fluctuations is shown to be on these larger scales. © Royal Meteorological Society, 2004. J. C. Petch's contribution is Crown copyright
Observations and numerical simulations of the diurnal cycle of the EUROCS stratocumulus case
Authors: Duynkerke Peter G. , de Roode Stephan R. , van Zanten Margreet C. , Calvo Javier , Cuxart Joan , Cheinet Sylvain , Chlond Andreas , Grenier Hervé , Jonker Piet J. , Köhler Martin , Lenderink Geert , Lewellen David , Lappen Cara‐lyn , Lock Adrian P. , Moeng Chin‐hoh , Müller Frank , Olmeda Dolores , Piriou Jean‐marcel , Sánchez Enrique , Sednev Igor
Published: February 2005

As part of the European Project on Cloud Systems in Climate Models, the diurnal cycle of stratocumulus has been simulated with Large‐Eddy Simulation (LES) models and Single Column Models (SCMs). The models were initialized and compared with observations collected in marine stratocumulus in July 1987 during the First International Satellite Cloud Climatology Project Regional Experiment. The results of the six LES models are found to be in a fair agreement with the observations. They all capture the distinct diurnal variation in the cloud liquid‐water path, the turbulence profiles and clearly show a decoupled boundary layer during daytime and a vertically well‐mixed boundary layer during the night. Entrainment of relatively dry and warm air from just above the inversion into the boundary layer is the major process modifying the thermodynamic structure of the boundary layer during the night. The differences that arise in the liquid‐water path evolution can therefore be attributed mainly to differences in the entrainment rate. The mean entrainment rates computed from the LES model results are 0.58±0.08 cm s−1 and 0.36±0.03 cm s−1 for the night‐time and daytime periods, respectively. If the horizontal domain size in a LES model is enlarged, mesoscale fluctuations develop. This leads to a broader liquid‐water path distribution and a reduction of the cloud albedo.

To assess the quality of the representation of stratocumulus in general‐circulation models, results from ten SCMs are compared with observations and LES results. The SCM latent and sensible heat fluxes at the surface agree fairly well with the LES results. Many of the SCMs predict a liquid‐water path which is much too low, a cloud cover smaller than unity, and cloud tops that are lower than the observations and the LES results. This results in a much larger amount of downwelling short‐wave radiation absorbed at the sea surface. Improvement of entrainment parametrizations is needed for a better representation of stratocumulus in SCMs.

Observations and LES results of entrainment rates for different stratocumulus cases are compared. The observed entrainment rates in Atlantic stratocumulus clouds during the Atlantic Stratocumulus Transition Experiment (ASTEX) are larger than for the ones over the Pacific Ocean off the coast of California. Results from LES models corroborate these findings. The differences in the entrainment rate can likely be attributed to the smaller inversion jumps of the liquid‐water potential temperature for the ASTEX stratocumulus cases. © Royal Meteorological Society, 2004. A. P. Lock's contribution is Crown copyright
Improved mixing representation in Emanuel's convection scheme
Authors: Grandpeix J.‐Y. , Phillips V. , Tailleux R.
Published: February 2005

Recent empirical and modelling studies suggest that mid‐tropospheric relative humidity (RH) is an important controlling factor of deep atmospheric convection, which appears to be underestimated in present cumulus parametrizations. This indicates the possible presence of shortcomings in the way that entrainment is represented in such parametrizations. This matter was explored in the European Cloud Systems project (EUROCS) by means of an idealized humidity experiment in which the main controlling parameter is RH. In the latter study, cloud‐resolving model (CRM) experiments suggested that a shallow/deep convection transition occurs when RH crosses a threshold value that ranges from about RH=50% to RH=60%.

In this paper, we seek to increase the responsiveness of Emanuel's convection scheme to RH, and to reproduce the threshold behaviour of the idealized humidity case, by replacing the original uniform probability density function (PDF) for mixing fractions by a more flexible two‐parameter bell‐shaped function that allows a wider range of behaviour. The main result is that the parameters of this PDF can be tuned to allow a regime transition to occur near a threshold value of RH≈55%. In contrast to CRM results, however, this transition is between two different regimes of deep convection rather than between a shallow and deep regime. Possible ways to obtain a shallow‐to‐deep transition with Emanuel's scheme are discussed. Copyright © 2004 Royal Meteorological Society
Cloud representation in general‐circulation models over the northern Pacific Ocean: A EUROCS intercomparison study
Authors: Siebesma A. P. , Jakob C. , Lenderink G. , Neggers R. A. J. , Teixeira J. , Van Meijgaard E. , Calvo J. , Chlond A. , Grenier H. , Jones C. , Köhler M. , Kitagawa H. , Marquet P. , Lock A. P. , Müller F. , Olmeda D. , Severijns C.
Published: February 2005

The EUROCS (EUROpean Cloud Systems study) project aims to improve the treatment of cloud systems in regional and global climate and weather prediction models. This paper reports an intercomparison study of cloud representation over the Pacific Ocean for nine climate and weather prediction models. The study consists of an analysis of a June/July/August 1998 period along an idealized trajectory over the Pacific Ocean that encompasses both the ascending and descending branch of the Hadley circulation. The three cloud types that are studied by EUROCS, stratocumulus, shallow cumulus and deep‐convective cloud systems, do all occur in a persistent and geographically separated way, along this trajectory.

The main focus of this study is on processes related to the hydrological cycle within the Hadley circulation. These include the large‐scale dynamics (i.e. the strength of the up‐ and downwelling branches of the Hadley cell), the cloud processes (i.e. cloud cover, cloud amounts and precipitation), and the impact of these processes on the radiation budget both at the top of the atmosphere and at the ocean's surface.

In order to make a quantitative assessment, special care has been taken to select reliable observational datasets. The main conclusions are that (1) almost all models strongly underpredicted both cloud cover and cloud amount in the stratocumulus regions while (2) the situation is opposite in the trade‐wind region and the tropics where cloud cover and cloud amount are overpredicted by most models. These deficiencies result in an overprediction of the downwelling surface short‐wave radiation of typically 60 W m−2 in the stratocumulus regimes and a similar underprediction of 60 W m−2 in the trade‐wind regions and in the intertropical convergence zone (ITCZ). Similar biases for the short‐wave radiation were found at the top of the atmosphere, while discrepancies in the outgoing long‐wave radiation are most pronounced in the ITCZ. © Royal Meteorological Society, 2004. A. P. Lock's contribution is Crown copyright
Competitor See, Competitor Do: Incumbent Entry in New Market Niches
Authors: Debruyne Marion , Reibstein David J.
Published: February 2005

The ability to keep up with changing technology is critical for a company's long-term survival. However, companies have to balance the risk of rushing into new areas and potentially cannibalizing their existing business against the risk of missing the emerging market. This paper investigates when incumbents enter into new market niches created by technological innovation. We argue that market conditions and company-specific characteristics do not suffice to explain incumbents' entry timing, but that entry is a contagious process. Our results demonstrate that incumbents are more likely to respond to innovations in their industry when their counterparts do so. In particular, we show that incumbents are affected by the entry of firms that are similar in size and resources. When a highly similar company enters the new market, it raises the probability that the company enters itself beyond levels based solely on the attractiveness of the market.
Competitive Reactions to Advertising and Promotion Attacks
Authors: Steenkamp Jan-Benedict E. M. , Nijs Vincent R. , Hanssens Dominique M. , Dekimpe Marnik G.
Published: February 2005

How do competitors react to each other's price-promotion and advertising attacks? What are the reasons for the observed reaction behavior? We answer these questions by performing a large-scale empirical study on the short-run and long-run reactions to promotion and advertising shocks in over 400 consumer product categories over a four-year time span.

Our results clearly show that the most predominant form of competitive response is passive in nature. When a reaction does occur, it is usually retaliatory in the same instrument, i.e., promotion attacks are countered with promotions, and advertising attacks are countered with advertising. There are very few long-run consequences of any type of reaction behavior. By linking reaction behavior to both cross- and own-effectiveness, we further demonstrate that passive behavior is often a sound strategy, while firms that do opt to retaliate often use ineffective instruments, resulting in “spoiled arms.” Accommodating behavior is observed in only a minority of cases, and often results in a missed sales opportunity when promotional support is reduced. The ultimate impact of most promotion and advertising campaigns depends primarily on the nature of consumer response, not the vigilance of competitors.
Time-Varying Competition
Authors: Sudhir K. , Chintagunta Pradeep K. , Kadiyali Vrinda
Published: February 2005

Normative models typically suggest that prices rise in periods of high demand and cost. However, in many markets, prices fall when demand or costs rise. This inconsistency occurs because the normative models assume that competitive intensity does not change with demand and cost conditions over time. We therefore introduce the notion of time-varying competition by suggesting that it is important not only to account for the direct effect of demand and cost on prices (e.g., higher demand means higher prices), but also the indirect effect of demand and cost changes on competition (e.g., higher demand could cause more competition and, hence, lower prices).

We develop a general, unified framework to empirically model the direct and indirect effects of demand and cost shifts on pricing in differentiated product markets. Our approach allows us to measure the indirect effect of multiple demand and cost drivers on competitive intensity and test predictions from alternative theories of repeated games. The empirical application is to the U.S. photographic film industry, where there are two main players, Kodak and Fuji.

We find that the indirect effects are highly significant and comparable in magnitude to the direct effects. Competitive intensity is greater in periods of high demand and lower cost and is moderated by whether demand or costs are expected to grow or decline. Interestingly, we find asymmetries in the competitive responses of Kodak and Fuji. While Kodak is sensitive to demand factors, Fuji is sensitive to costs. Our results suggest that market characteristics such as observability of competitor prices can be an important determinant of how competitive intensity is affected by demand and cost conditions.
Reasoning About Competitive Reactions: Evidence from Executives
Authors: Montgomery David B. , Moore Marian Chapman , Urbany Joel E.
Published: February 2005

Much of the empirical research on competitive reactions describes how or why rivals react to a firm's past actions, but stops short of examining whether managers attempt to predict such reactions, which we call strategic competitive reasoning. In three exploratory studies, we find evidence of managers' thinking about competitors' past and future behavior, but little incidence of strategic competitive reasoning. Competitive intelligence experts and other experienced managers' assessment of the results suggests that the relatively low incidence of strategic competitor reasoning is due to perceptions of low returns from anticipating competitor reactions more than to the high cost of doing so. Both the difficulty of obtaining competitive information and the uncertainty associated with predicting competitor behavior contribute to these perceptions. The paper suggests both a need for research on competitive behavior and an opportunity to influence and improve managerial judgment and decision making.
Planning Marketing-Mix Strategies in the Presence of Interaction Effects
Authors: Naik Prasad A. , Raman Kalyan , Winer Russell S.
Published: February 2005

Companies spend millions of dollars on advertising to boost a brand's image and simultaneously spend millions of dollars on promotion that many believe calls attention to price and erodes brand equity. We believe this paradoxical situation exists because both advertising and promotion are necessary to compete effectively in dynamic markets. Consequently, brand managers need to account for interactions between marketing activities and interactions among competing brands. By recognizing interaction effects between activities, managers can consider interactivity trade-offs in planning the marketing-mix strategies. On the other hand, by recognizing interactions with competitors, managers can incorporate strategic foresight in their planning, which requires them to look forward and reason backward in making optimal decisions. Looking forward means that each brand manager anticipates how other competing brands are likely to make future decisions, and then by reasoning backward deduces one's own optimal decisions in response to the best decisions to be made by all other brands. The joint consideration of interaction effects and strategic foresight in planning marketing-mix strategies is a challenging and unsolved marketing problem, which motivates this paper.

This paper investigates the problem of planning marketing mix in dynamic competitive markets. We extend the Lanchester model by incorporating interaction effects, constructing the marketing-mix algorithm that yields marketing-mix plans with strategic foresight, and developing the continuous-discrete estimation method to calibrate dynamic models of oligopoly using market data. Both the marketing-mix algorithm and the estimation method are general, so they can be applied to any other alternative model specifications for dynamic oligopoly markets. Thus, this dual methodology augments the decision-making toolkit of managers, empowering them to tackle realistic marketing problems in dynamic oligopoly markets.

We illustrate the application of this dual methodology by studying the dynamic Lanchester competition across five brands in the detergents market, where each brand uses advertising and promotion to influence its own market share and the shares of competing brands. Empirically, we find that advertising and promotion not only affect the brand shares (own and competitors') but also exert interaction effects, i.e., each activity amplifies or attenuates the effectiveness of the other activity. Normatively, we find that large brands underadvertise and overspend on promotion, while small brands underadvertise and underpromote. Finally, comparative statics reveal managerial insights into how a specific brand should respond optimally to the changes in a competing brand's situation; more generally, we find evidence that competitive responsiveness is asymmetric.
A Prelaunch Diffusion Model for Evaluating Market Defense Strategies
Authors: Roberts John H. , Nelson Charles J. , Morrison Pamela D.
Published: February 2005

This paper describes the development and application of a marketing model to help set an incumbent's defensive marketing strategy prior to a new competitor's launch. The management problem addressed is to assess the market share impact of a new entrant in the residential Australian long distance telephone call market and determine the factors that would influence its dynamics and ultimate market appeal.

The paper uses probability flow models to provide a framework to generate forecasts and assess the determinants of share loss. We develop models at two levels of complexity to give both simple, robust forecasts and more detailed diagnostic analysis of the effect of marketing actions. The models are calibrated prior to the new entrant's launch, enabling preemptive marketing strategies to be put in place by the defending company. The equilibrium level of consideration of the new entrant was driven by respondents' strength of relationship with the defender and inertia, while trial was more price-based. Continued use of the defender depends on both service factors and price. The rate at which share loss eventuates is negatively related to the defender's perceived responsiveness, saving money being the only reason to switch, and risk aversion.

Prelaunch model forecasts, validated six months after launch using both aggregate monthly sales data and detailed tracking surveys, are shown to closely follow the actual evolution of the market. The paper provides a closed-form multistate model of the new entrant's diffusion, a methodology for the prelaunch calibration of dynamic models in practice, and insights into defensive strategies for existing companies facing new entrants.
Comments on Competitive Responsiveness
Authors: Shugan Steven M.
Published: February 2005

Marketing Science features many and diverse articles that analyze competitive responsiveness. Although recent Marketing Science editorials (e.g., Shugan 2002) suggest that competitive responsiveness is only a part of a comprehensive competitive marketing strategy, it remains a vital part. For that reason and many others, Marketing Science is particularly proud of this special issue edited by David J. Reibstein and Dick R. Wittink.

Before introducing and vigorously applauding both the editors and authors of this excellent special issue, we emphasize that competitive responsiveness raises numerous issues, including whether one can forecast outcomes of new policies based on past observations made under old policies (i.e., the Lucas critique) and decisions regarding which variables should be considered endogenous (Shugan 2004), i.e., determined within the model.

Perhaps, normative models are inherently perishable—evolution in market structure requires modifications over time. Also, although complete consistency within the world of the model is aesthetically pleasing, imposing industry-specific exogenous constraints (that might appear unrelated to the modeling assumptions) is sometimes necessary.
An Econometric Analysis of Inventory Turnover Performance in Retail Services
Authors: Gaur Vishal , Fisher Marshall L. , Raman Ananth
Published: February 2005

Inventory turnover varies widely across retailers and over time. This variation undermines the usefulness of inventory turnover in performance analysis, benchmarking, and working capital management. We develop an empirical model using financial data for 311 publicly listed retail firms for the years 1987–2000 to investigate the correlation of inventory turnover with gross margin, capital intensity, and sales surprise (the ratio of actual sales to expected sales for the year). The model explains 66.7% of the within-firm variation and 97.2% of the total variation (across and within firms) in inventory turnover. It yields an alternative metric of inventory productivity, adjusted inventory turnover, which empirically adjusts inventory turnover for changes in gross margin, capital intensity, and sales surprise, and can be applied in performance analysis and managerial decision making. We also compute time trends in inventory turnover and adjusted inventory turnover, and find that both have declined in retailing during the 1987–2000 period.
Engineering Solution of a Basic Call-Center Model
Authors: Whitt Ward
Published: February 2005

An algorithm is developed to rapidly compute approximations for all the standard steady-state performance measures in the basic call-center queueing model M/GI/s/r+GI, which has a Poisson arrival process, independent and identically distributed (IID) service times with a general distribution, s servers, r extra waiting spaces and IID customer abandonment times with a general distribution. Empirical studies of call centers indicate that the service-time and abandon-time distributions often are not nearly exponential, so that it is important to go beyond the Markovian M/M/s/r+M special case, but the general service-time and abandon-time distributions make the realistic model very difficult to analyze directly. The proposed algorithm is based on an approximation by an appropriate Markovian M/M/s/r+M(n) queueing model, where M(n) denotes state-dependent abandonment rates. After making an additional approximation, steady-state waiting-time distributions are characterized via their Laplace transforms. Then the approximate distributions are computed by numerically inverting the transforms. Simulation experiments show that the approximation is quite accurate. The overall algorithm can be applied to determine desired staffing levels, e.g., the minimum number of servers needed to guarantee that, first, the abandonment rate is below any specified target value and, second, that the conditional probability that an arriving customer will be served within a specified deadline, given that the customer eventually will be served, is at least a specified target value.
An ARIMA Supply Chain Model
Authors: Gilbert Kenneth
Published: February 2005

This paper presents a multistage supply chain model that is based on Autoregressive Integrated Moving Average (ARIMA) time-series models. Given an ARIMA model of consumer demand and the lead times at each stage, it is shown that the orders and inventories at each stage are also ARIMA, and closed-form expressions for these models are given.

The paper also discusses the causes of the bullwhip effect, a phenomenon in which variation in demand produces larger variations in upstream orders and inventory. This discussion reveals how different modeling can lead to different insights because they make different assumptions about the cause of the bullwhip effect. These observations are used to develop managerial insights about reducing the bullwhip effect.
Portfolio Investment with the Exact Tax Basis via Nonlinear Programming
Authors: DeMiguel Victor , Uppal Raman
Published: February 2005

Computing the optimal portfolio policy of an investor facing capital gains tax is a challenging problem: because the tax to be paid depends on the price at which the security was purchased (the tax basis), the optimal policy is path dependent and the size of the problem grows exponentially with the number of time periods. Dammon et al. (2001, 2002, 2004), Garlappi et al. (2001), and Gallmeyer et al. (2001) address this problem by approximating the exact tax basis by the weighted average purchase price. Our contribution is threefold. First, we show that the structure of the problem has several attractive features that can be exploited to determine the optimal portfolio policy using the exact tax basis via nonlinear programming. Second, we characterize the optimal portfolio policy in the presence of capital gains tax when using the exact tax basis. Third, we show that the certainty equivalent loss from using the average tax basis instead of the exact basis is very small: it is typically less than 1% for problems with up to 10 periods, and this result is robust to the choice of parameter values and to the presence of transaction costs, dividends, intermediate consumption, labor income, tax reset provision at death, and wash-sale constraints.
An Empirical Analysis of Forecast Sharing in the Semiconductor Equipment Supply Chain
Authors: Terwiesch Christian , Ren Z. Justin , Ho Teck H. , Cohen Morris A.
Published: February 2005

We study the demand forecast-sharing process between a buyer of customized production equipment and a set of equipment suppliers. Based on a large data collection we undertook in the semiconductor equipment supply chain, we empirically investigate the relationship between the buyer's forecasting behavior and the supplier's delivery performance. The buyer's forecasting behavior is characterized by the frequency and magnitude of forecast revisions it requests (forecast volatility) as well as by the fraction of orders that were forecasted but never actually purchased (forecast inflation). The supplier's delivery performance is measured by its ability to meet delivery dates requested by the customers. Based on a duration analysis, we are able to show that suppliers penalize buyers for unreliable forecasts by providing lower service levels. Vice versa, we also show that buyers penalize suppliers that have a history of poor service by providing them with overly inflated forecasts.
Managing Flexible Capacity in a Make-to-Order Environment
Authors: Bish Ebru K. , Muriel Ana , Biller Stephan
Published: February 2005

Flexible capacity has been shown to be very effective to hedge against forecast errors at the investment stage. In a make-to-order environment, this flexibility can also be used to hedge against variability in customer orders in the short term. For that purpose, production levels must be adjusted each period to match current demands, to give priority to the higher margin product, or to satisfy the closest customer. However, this will result in swings in production, inducing larger order variability at upstream suppliers and significantly higher component inventory levels at the manufacturer. Through a stylized two-plant, two-product capacitated manufacturing setting, we show that the performance of the system depends heavily on the allocation mechanism used to assign products to the available capacity. Although managers would be inclined to give priority to higher-margin products or to satisfy customers from their closest production site, these practices lead to greater swings in production, result in higher operational costs, and may reduce profits.
Productivity Change, Technical Progress, and Relative Efficiency Change in the Public Accounting Industry
Authors: Banker Rajiv D. , Chang Hsihui , Natarajan Ram
Published: February 2005

We present evidence on components of productivity change in the public accounting industry toward the end of the 20th century. Using revenue and human resource data from 64 of the 100 largest public accounting firms in the United States for the 1995–1999 period, we analyze productivity change, technical progress, and relative efficiency change over time. The average public accounting firm experienced a productivity growth of 9.5% between 1995 and 1999. We find support for the hypothesis that technical progress rather than an improvement in relative efficiency was the reason for this productivity growth. Firms that were early movers into management advisory services (MAS) and those that emphasized growth in MAS over growth in the traditional audit and tax services enjoyed significantly higher productivity growth than their peers. These firms also contributed significantly more to the industry's technical progress.