bluuebunny/crossref_metadata_2025 huggingface dataset:
Aerodynamic force generation and power requirements in forward flight in a fruit fly with modeled wing motion
Authors: Sun Mao , Wu Jiang Hao
Published: July 2003

Aerodynamic force generation and power requirements in forward flight in a fruit fly with modeled wing motion were studied using the method of computational fluid dynamics. The Navier-Stokes equations were solved numerically. The solution provided the flow velocity and pressure fields, from which the vorticity wake structure and the unsteady aerodynamic forces and torques were obtained (the inertial torques due to the acceleration of the wing-mass were computed analytically). From the flow-structure and force information, insights were gained into the unsteady aerodynamic force generation. On the basis of the aerodynamic and inertial torques, the mechanical power was obtained, and its properties were investigated.

The unsteady force mechanisms revealed previously for hovering (i.e. delayed stall, rapid acceleration at the beginning of the strokes and fast pitching-up rotation at the end of the strokes) apply to forward flight. Even at high advance ratios, e.g. J=0.53-0.66 (J is the advance ratio), the leading edge vortex does not shed (at such advance ratios, the wing travels approximately 6.5 chord lengths during the downstroke).

At low speeds (J≈0.13), the lift (vertical force) for weight support is produced during both the down- and upstrokes (the downstroke producing approximately 80% and the upstroke producing approximately 20% of the mean lift), and the lift is contributed mainly by the wing lift; the thrust that overcomes the body drag is produced during the upstroke, and it is contributed mainly by the wing drag. At medium speeds (J≈0.27),the lift is mainly produced during the downstroke and the thrust mainly during the upstroke; both of them are contributed almost equally by the wing lift and wing drag. At high speeds (J≈0.53), the lift is mainly produced during the downstroke and is mainly contributed by the wing drag; the thrust is produced during both the down- and upstrokes, and in the downstroke, is contributed by the wing lift and in the upstroke, by the wing drag.

In forward flight, especially at medium and high flight speeds, the work done during the downstroke is significantly greater than during the upstroke. At advance ratios J≈0.13, 0.27 and 0.53, the work done during the downstroke is approximately 1.6, 2.8 and 4.2 times as much as that during the upstroke, respectively.

At J=0 (hovering), the body-mass-specific power is approximately 29 W kg-1; at J=0.13 and 0.27, the power is approximately 10% less than that of hovering; at J=0.40, the power is approximately the same as that of hovering; when J is further increased, the power increases sharply. The graph of power against flying speeds is approximately J-shaped.

From the graph of power against flying speeds, it is predicted that the insect usually flies at advance ratios between zero and 0.4, and for fast flight, it would fly at an advance ratio between 0.4 and 0.53.
Effect of a mono-specific algal diet on immune functions in two bivalve species -Crassostrea gigasandRuditapes philippinarum
Authors: Delaporte Maryse , Soudant Philippe , Moal Jeanne , Lambert Christophe , Quéré Claudie , Miner Philippe , Choquet Gwénaëlle , Paillard Christine , Samain Jean-François
Published: July 2003

The impact of diets upon the fatty acid composition of haemocyte polar lipids and consequently upon immune parameters has been tested in the oyster Crassostrea gigas and the clam Ruditapes philippinarum. Oysters and clams were fed each of three cultured algae: Chaetoceros calcitrans, which is rich in 20:5(n-3) and 20:4(n-6) and poor in 22:6(n-3) fatty acids; T-Iso (Isochrysis sp.), which is rich in 22:6(n-3) and deficient in 20:5(n-3) and 20:4(n-6); and Tetraselmis suecica, which is deficient in 22:6(n-3) and contains only small amounts of 20:5(n-3) and 20:4(n-6).

Fatty acid composition of haemocyte polar lipids was greatly affected by the diet. Oysters and clams fed C. calcitrans maintained a higher proportion of 20:5(n-3) and 20:4(n-6) in their haemocyte polar lipids, while these polyunsaturated fatty acids decreased drastically for animals fed T-Iso. However, the T-Iso diet maintained 22:6(n-3) in haemocyte polar lipids of both species. Higher 20:5(n-3) and 20:4(n-6)contents in diets appeared to have a positive effect upon total haemocyte count, granulocyte percentage, phagocytic rate and oxidative activity of clam haemocytes. Similarly, a positive effect of 20:5(n-3) on oxidative activity of oyster haemocytes was observed but to a lesser extent than in clams. Interestingly, when oyster haemocytes are submitted to a stressful condition,a positive effect of a higher dietary 22:6(n-3) content on the phagocytic rate was noticed.
Thermal acclimation of surfactant secretion and its regulation by adrenergic and cholinergic agonists in type II cells isolated from warm-active and torpid golden-mantled ground squirrels,Spermophilus lateralis
Authors: Ormond Carol J. , Orgeig Sandra , Daniels Christopher B. , Milsom William K.
Published: July 2003

Homeothermic mammals experience pulmonary surfactant dysfunction with relatively small fluctuations in body temperature. However, ground squirrels survive dramatic changes in body temperature during hibernation, when body temperature drops from 37°C to 0-5°C during prolonged torpor bouts. Using type II cells isolated from both warm-active and torpid squirrels, we determined the effect of assay temperature, autonomic agonists and torpor on surfactant secretion. Basal secretion was significantly higher in type II cells isolated from torpid squirrels compared with warm-active squirrels when assayed at the body temperature of the animal from which they were isolated(4°C and 37°C, respectively). A change in assay temperature significantly decreased surfactant secretion. However, the change in secretory rate between 37°C and 4°C was less than expected if due to temperature alone (Q10 range=0.8-1.2). Therefore, the surfactant secretory pathway in squirrel type II cells demonstrates some temperature insensitivity. When incubated at the body temperature of the animal from which the cells were isolated, the adrenergic agonist, isoproterenol, significantly increased surfactant secretion in both warm-active and torpid squirrel type II cells. However, the cholinergic agonist, carbamylcholine chloride, only increased secretion in torpid squirrel type II cells when incubated at 4°C. Torpor did not affect basal cAMP production from isolated type II cells. However, the production of cAMP appears to be upregulated in response to isoproterenol in torpid squirrel type II cells. Thus, at the cellular level, both the secretory and regulatory pathways involved in surfactant secretion are thermally insensitive. Upregulating basal secretion and increasing the sensitivity of type II cells to cholinergic stimulation may be adaptative characteristics of torpor that enable type II cells to function effectively at 0-5°C.
Screening of second messengers involved in photocyte bioluminescence control of three ophiuroid species (Ophiuroidea: Echinodermata)
Authors: Vanderlinden C. , Dewael Y. , Mallefet J.
Published: July 2003

We investigated the effects of cyclic nucleotides (cGMP and cAMP) and inositol triphosphate/diacylglycerol pathways on the KCl-induced luminescence control of the ophiuroid species Amphiura filiformis, Ophiopsila aranea and Ophiopsila californica. Results show that dibutyrylcGMP, the cGMP analogue, and sodium nitroprusside, the guanylyl cyclase activator, had no effect on the luminescence of O. aranea and O. californica. On the other hand, cGMP could be involved in an inhibitory control in A. filiformis. Dibutyryl-cAMP, the cAMP analogue, and forskolin, the adenylyl cyclase activator, had no effect on maximal light emission, but the adenylyl cyclase inhibitors MDL-12,330A and SQ22,536 affected the kinetics of light production in both Ophiopsilaspecies and strongly reduced KCl-induced luminescence in A. filiformis and O. aranea, suggesting cAMP pathway involvement in photogenesis. The phospholipase C inhibitor U-73122 also strongly reduced KCl-induced luminescence in all three species but this effect seems to be unspecific since U-73343, the inactive analogue of U-73122, equally inhibited photogenesis. Therefore, the results suggest that luminescence control of A. filiformis, O. aranea and O. californica is mediated by cAMP in synergy with calcium.
Effects of temperature and extracellular pH on metabolites: kinetics of anaerobic metabolism in resting muscle by 31P- and 1H-NMR spectroscopy
Authors: Vezzoli Alessandra , Gussoni Maristella , Greco Fulvia , Zetta Lucia
Published: July 2003

Environmental stress, such as low temperature, extracellular acidosis and anoxia, is known to play a key role in metabolic regulation. The aim of the present study was to gain insight into the combined temperature-pH regulation of metabolic rate in frog muscle, i.e. an anoxia-tolerant tissue. The rate of exergonic metabolic processes occurring in resting isolated muscles was determined at 15°C and 25°C as well as at extracellular pH values higher (7.9), similar (7.3) and lower (7.0) than the physiological intracellular pH. 31P and 1H nuclear magnetic resonance spectroscopy high-resolution measurements were carried out at 4.7 T in isolated frog (Rana esculenta) gastrocnemius muscle during anoxia to assess, by means of reference compounds, the concentration of all phosphate metabolites and lactate. Intra- and extracellular pH was also determined.

In the range of examined temperatures (15-25°C), the temperature dependence of anaerobic glycolysis was found to be higher than that of PCr depletion (Q10=2.3). High-energy phosphate metabolism was confirmed to be the initial and preferential energy source. The rate of phosphocreatine hydrolysis did not appear to be affected by extracellular pH changes. By contrast, independent of the intracellular pH value, at the higher temperature(25°C) a lowering of the extracellular pH from 7.9 to 7.0 caused a depression in lactate accumulation. This mechanism was ascribed to the transmembrane proton concentration gradient. This parameter was demonstrated to regulate glycolysis, probably through a reduced lactate efflux, depending on the activity of the lactate-H+ co-transporter.

The calculated intracellular buffer capacity was related to intra- and extracellular pH and temperature. At the experimental extracellular pH of 7.9 and at a temperature of 15°C and 25°C, calculated intracellular buffering capacity was 29.50 μmol g-1 pH unit-1 and 69.98 μmol g-1 pH unit-1, respectively.
Species-specific effects of single sensillum ablation on mating position inDrosophila
Authors: Acebes Angel , Cobb Matthew , Ferveur Jean-François
Published: July 2003

Dipteran insects show a wide range of species-specific mating positions. Interspecific transitions from one position to another may reflect sexual or natural selection, or be pleiotropic consequences of other genetic changes. Like many cyclorrhaphan flies, Drosophila species mate with the male on the back of the female, positioned centrally. Mechanosensory sensilla on the male genitalia of three species of the melanogaster species sub-group of Drosophila have species-specific effects on mating position and on courtship success: ablation of a single pair of bristles on the genital claspers of D. melanogaster males halved homotypic mating success, and unilateral ablation produced a contralateral asymmetry in the male's mating posture. Ablation of mechanoreceptors on the male genital lateral plate affected mating posture less radically and had no effect on mating frequency. Surprisingly, ablation of sensilla on the claspers of D. simulans and D. sechellia males showed no effect on homotypic mating. A similar result was found for D. melanogaster × D. simulans hybrid males. The existence of major differences in the sensory bases of mating position and copulation success in closely related species shows how differing mating positions may have evolved and underlines the need for detailed functional studies in studying the evolution of insect genitalia:homologous structures may serve different functions in different species.
Flexural stiffness in insect wings I. Scaling and the influence of wing venation
Authors: Combes S. A. , Daniel T. L.
Published: July 2003

During flight, many insect wings undergo dramatic deformations that are controlled largely by the architecture of the wing. The pattern of supporting veins in wings varies widely among insect orders and families, but the functional significance of phylogenetic trends in wing venation remains unknown, and measurements of the mechanical properties of wings are rare. In this study, we address the relationship between venation pattern and wing flexibility by measuring the flexural stiffness of wings (in both the spanwise and chordwise directions) and quantifying wing venation in 16 insect species from six orders. These measurements show that spanwise flexural stiffness scales strongly with the cube of wing span, whereas chordwise flexural stiffness scales with the square of chord length. Wing size accounts for over 95% of the variability in measured flexural stiffness; the residuals of this relationship are small and uncorrelated with standardized independent contrasts of wing venation characters. In all species tested, spanwise flexural stiffness is 1-2 orders of magnitude larger than chordwise flexural stiffness. A finite element model of an insect wing demonstrates that leading edge veins are crucial in generating this spanwise-chordwise anisotropy.
Flexural stiffness in insect wings II. Spatial distribution and dynamic wing bending
Authors: Combes S. A. , Daniel T. L.
Published: July 2003

The dynamic, three-dimensional shape of flapping insect wings may influence many aspects of flight performance. Insect wing deformations during flight are largely passive, and are controlled primarily by the architecture and material properties of the wing. Although many details of wing structure are well understood, the distribution of flexural stiffness in insect wings and its effects on wing bending are unknown. In this study, we developed a method of estimating spatial variation in flexural stiffness in both the spanwise and chordwise direction of insect wings. We measured displacement along the wing in response to a point force, and modeled flexural stiffness variation as a simple mathematical function capable of approximating this measured displacement. We used this method to estimate flexural stiffness variation in the hawkmoth Manduca sexta, and the dragonfly Aeshna multicolor. In both species, flexural stiffness declines sharply from the wing base to the tip, and from the leading edge to the trailing edge; this variation can be approximated by an exponential decline. The wings of M. sexta also display dorsal/ventral asymmetry in flexural stiffness and significant differences between males and females. Finite element models based on M. sexta forewings demonstrate that the measured spatial variation in flexural stiffness preserves rigidity in proximal regions of the wing,while transferring bending to the edges, where aerodynamic force production is most sensitive to subtle changes in shape.
A Simple and Facile Chemo- and Regioselective Deprotection of Acetonides Using Silica Supported Sodium Hydrogen Sulfate as a Heterogeneous Catalyst
Authors: Mahender G , Ramu R , Ramesh C , Das Biswanath
Published: July 2003

Silica supported sodium hydrogen sulfate (NaHSO4·SiO2) has been found to be an efficient heterogeneous catalyst for chemo- and regioselective deprotection of acetonides at room temperature to produce the corresponding diols in excellent yields.
A Phthalocyanine Producing Green, Ocher, and Red Colors Depending on the Central Metals
Authors: Fukuda Takamitsu , Ono Kosuke , Homma Shigetsugu , Kobayashi Nagao
Published: July 2003

Metal complexes of a highly deformed 1,4,8,11,15,18,22,25-octaphenylphthalocyanine have been synthesized, and found to show various colors ranging from bright green, ocher, and red depending on the central metal employed.
Efficient and Rapid One-pot Conversions of Aldehydes into Nitriles and Ketones into Amides Using Silica Chloride under Microwave Irradiation
Authors: Srinivas K V N S , Mahender I , Das Biswanath
Published: July 2003

Under solvent free conditions, several aldehydes and ketones were efficiently and rapidly converted into the corresponding nitriles and amides respectively by treatment with hydroxylamine hydrochloride under microwave irradiation using silica chloride as catalyst. The yields of the products were very high and the time required for their preparation was very short compared to conventional heating experiments.
Crystal Structure of 1-Butyl-3-methylimidazolium Chloride. A Clue to the Elucidation of the Ionic Liquid Structure
Authors: Saha Satyen , Hayashi Satoshi , Kobayashi Akiko , Hamaguchi Hiro-o
Published: July 2003

A single crystal of 1-butyl-3-methylimidazolium chloride [bmim]Cl, a prototype ionic liquid, has successfully been prepared and an X-ray crystallographic analysis has been performed. It reveals the presence of a hydrogen bonding network involving the chloride anion and the ring as well as the n-butyl hydrogen atoms, a strong hydrophobic interaction between the two n-butyl groups of the [bmim] cations, and a unique corrugated sheets structure of the imidazolium rings. Considering the similarity of the Raman spectra of crystalline and liquid states, we suspect that the three dimensional structure determined in the present study also exist, at least partially, in the ionic liquid state.
Deuterium Migration Mechanism in Chiral Thiolactam Formation by Neutron Diffraction Analysis
Authors: Hosoya Takaaki , Uekusa Hidehiro , Ohashi Yuji , Ohhara Takashi , Kimura Hiroyuki , Noda Yukio
Published: July 2003

The single-crystal neutron diffraction revealed that in the process of photo-induced β-thiolactam formation from N,N-dibenzyl-1-cyclohexenecarbothioamide a deuterium atom bonded to the benzyl carbon atom is transferred to the intramolecular cyclohexene carbon to occupy the equatorial position of the produced cyclohexyl ring.
Synthesis of β-Thiophene-Substituted 21,23-Dithiaporphyrins
Authors: Agarwal Neeraj , Mishra Sarada P , Kumar A , Ravikanth M
Published: July 2003

β-Thiophene-substituted 21,23-dithiaporphyrins with substituents like methyl and phenyl groups were synthesized and characterized.
Blue-shifted Hydrogen Bonds with Proton-donors Incapable of Rehybridization
Authors: Wang Jin-Ti , Feng Yong , Liu Lei , Li Xiao-Song , Guo Qing-Xiang
Published: July 2003

Blue-shifted hydrogen bonds were found for F–He–H···Y (Y = N2, CO, and He) systems where the proton-donor (He) was incapable of rehybridization. This finding indicated that rehybridization is not a generally applicable driving force for the blue shift.
Formation of a Novel Polymeric Cadmium(II) Complex Bridged by Sulfur and Thiocyanato Ions
Authors: Li Sheng-Li , Wu Jie-Ying , Zhang Xuan-Jun , Tian Yu-Peng , Jiang Min-Hua , Chen Zu-Yao , Usman Anwar , Fun Hoong-Kun
Published: July 2003

The title complex, {[N(CH3)4]2[Cd(SCN)2S]}n, was prepared by self-assembling from the reaction of a methanol/water (volume ratio, 1/1) solution containing cadmium(II) thiocyanate with equivalent amount of tetramethylammonium thiocyanate. The result of single X-ray determination for the complex reveals that a novel polymeric cadmium(II) complex bridged by sulfur and thiocyanato ions was obtained, which formed a two-dimensional (2D) structure.
Photostimulated Long-lasting Phosphorescence in Rare-earth-doped Glasses
Authors: Qiu Jianrong , Jiang Xiongwei , Zhu Congshan , Si Jinhai , Li Chengyu , Su Qiang , Hirao Kazuyuki
Published: July 2003

Tb3+-doped glass sample emits bright and long-lasting phosphorescence after irradiation by an 800-nm femtosecond pulsed laser. Long-lasting phosphorescence is observed once again after further excitation by 365-nm UV light when the femtosecond laser-induced long-lasting phosphorescence cannot be detected.
1,4-Addition of Arylsiloxanes to Enones Catalyzed by Dicationic Palladium(II) Complexes in Aqueous Media
Authors: Nishikata Takashi , Yamamoto Yasunori , Miyaura Norio
Published: July 2003

Catalytic 1,4-addition of arylsiloxanes to enones was carried out at 75 °C in the presence of a dicationic palladium(II) catalyst in aqueous 1,4-dioxane. A nitrile-free complex generated in situ from Pd(dba)2 and Cu(BF4)2 in the presence of dppe or dppben was recognized to be the best catalyst to achieve high yields for the representative enones and enals.
Synthesis of New Donor–Acceptor Norbornadiene Derivatives
Authors: Nagai Takabumi , Takahashi Ikuko , Nishikubo Tadatomi
Published: July 2003

New donor–acceptor norbornadiene derivatives (NBDs) were synthesized from Diels–Alder reaction of methoxyphenylpentamethylcyclopendadiene with acetylene derivatives containing electron-withdrawing groups. These NBD derivatives have absorption in the visible region and photoisomerized to give thermally stable quadricyclane derivatives (QCs) with fair durability.
Unusual Enhancement of Ethylene Polymerization Activity of Benzyl Zirconium Complexes by Benzylation of the Imino Moiety of 2-(N-Aryliminomethyl)pyrrolyl Ligand
Authors: Tsurugi Hayato , Yamagata Tsuneaki , Tani Kazuhide , Mashima Kazushi
Published: July 2003

Reaction of Zr(CH2Ph)4 (1) with one equiv. of 2-(N-aryliminomethyl)pyrrolyl ligands (2a–e) in toluene afforded two types of products, depending upon the bulkiness of the aryl moiety. The reactions of 1 with two equiv. of the most sterically bulky 2e afforded complex 5e, whose pseudo octahedral geometry around the zirconium atom and totally dissymmetric cis-dibenzyl structure were elucidated. The high catalytic activity for ethylene polymerization was obtained by using complexes 3a and 3b.
A Novel Orthogonal Joint by Hydrogen Bonding. Pybox Ligand and Secondary Dialkylammonium Cation Complexes
Authors: Sada Kazuki , Sugimoto Takahiro , Tani Takahiro , Tateishi Yuuichi , Yi Tao , Shinkai Seiji , Maeda Hiroyuki , Tohnai Norimitsu , Miyata Mikiji
Published: July 2003

A novel supramolecular orthogonal joint via hydrogen bonds was constructed by a molecular complex between 2,6-bis(2-oxazolyl)pyridnes (pybox) and secondary dialkylammonium tetraphenylborates.
Reverse Micelle-assisted Route to Control Diameters of ZnO Nanorods by Selecting Different Precursors
Authors: Li Zhengquan , Xie Yi , Xiong Yujie , Zhang Rong , He Wei
Published: July 2003

A reverse micelle-assisted route was reported to prepare ZnO nanorods from two different precursors, Zn(NH3)42+ and Zn(OH)42−, respectively. The reverse micelles were used as microreactors, which lead into anisotropic growth of ZnO crystals during a simple solvothermal process.
A Well Characterized Example of Conversion of Molecular Configuration Depending on the Existence of Intermolecular Interactions
Authors: Zhu Qin-Yu , Zhang Yong , Dai Jie , Bian Guo-Qing , Jia Ding-Xian , Zhang Jia-Sheng , Guo Lin
Published: July 2003

A new complex [Ag(L)2]ClO4·2CH2Cl2 (1) (L = 4′, 5′-diaza-9′-(4,5-dimethylthio-1,3-dithiole-2-ylidene)fluorene) was synthesized. It was confirmed by 1H NMR and X-ray structure determination that when the molecules crystallize out from solution, a conversion of molecular configuration occurs because of the strong intermolecular interactions.
Optimal Pricing Mechanisms with Unknown Demand
Authors: Segal Ilya
Published: July 2003

The standard profit-maximizing multiunit auction intersects the submitted demand curve with a preset reservation supply curve, which is determined using the distribution from which the buyers' valuations are drawn. However, when this distribution is unknown, a preset supply curve cannot maximize monopoly profits. The optimal pricing mechanism in this situation sets a price for each buyer on the basis of the demand distribution inferred statistically from other buyers' bids. The resulting profit converges to the optimal monopoly profit with known demand as the number of buyers goes to infinity, and convergence can be substantially faster than with sequential price experimentation.
Animal Spirits Through Creative Destruction
Authors: Francois Patrick , Lloyd-Ellis Huw
Published: July 2003

We show how a Schumpeterian process of creative destruction can induce rational, herd behavior by entrepreneurs across diverse sectors as if fueled by “animal spirits.” Consequently, a multisector economy, in which productivity improvements are made by independent, profit-seeking entrepreneurs, exhibits regular booms, slowdowns, and downturns as part of the long-run growth process. Our cyclical equilibrium has higher average growth, but lower welfare than the corresponding acyclical one. We show how a negative relationship can emerge between volatility and growth across cycling economies, and assess the extent to which our model matches several features of actual business cycles.
Make Versus Buy in Trucking:Asset Ownership, Job Design, and Information
Authors: Baker George P , Hubbard Thomas N
Published: July 2003

Explaining patterns of asset ownership is a central goal of both organizational economics and industrial organization. We develop a model of asset ownership in trucking, which we test by examining how the adoption of different classes of on-board computers (OBCs) between 1987 and 1997 influenced whether shippers use their own trucks for hauls or contract with for-hire carriers. We find that OBCs' incentive-improving features pushed hauls toward private carriage, but their resource-allocation-improving features pushed them toward for-hire carriage. We conclude that ownership patterns in trucking reflect the importance of both incomplete contracts and of job design and measurement issues.
Wages and Employment in the United States and Germany:What Explains the Differences?
Authors: Beaudry Paul , Green David A
Published: July 2003

Over the last 20 years the wage-education relationships in the United States and Germany have evolved very differently, while the education compositions of employment have evolved in a parallel fashion. In this paper, we show how these patterns shed light on the nature of recent technological change and highlight the importance of taking into account movements in the ratio of human capital to physical capital when examining changes in the returns to skill. Our analysis indicates that the United States could have prevented the increase in wage inequality observed in the 1980's by a faster accumulation of physical capital.
Dynamic Speculative Attacks
Authors: Chamley Christophe
Published: July 2003

This paper presents a model of rational Bayesian agents with speculative attacks in a regime of exchange rate which is pegged within a band. Speculators learn from the observation of the exchange rate within the band whether their mass is sufficiently large for a successful attack. Multiple periods are necessary for the existence of speculative attacks. Various defense policies are analyzed. A trading policy by the central bank may defend the peg if it is unobserved and diminishes the market's information for the coordination of speculators.
The Performance of Forecast-Based Monetary Policy Rules Under Model Uncertainty
Authors: Levin Andrew , Wieland Volker , Williams John C
Published: July 2003

We investigate the performance of forecast-based monetary policy rules using five macroeconomic models that reflect a wide range of views on aggregate dynamics. We identify the key characteristics of rules that are robust to model uncertainty; such rules respond to the one-year-ahead inflation forecast and to the current output gap and incorporate a substantial degree of policy inertia. In contrast, rules with longer forecast horizons are less robust and are prone to generating indeterminacy. Finally, we identify a robust benchmark rule that performs very well in all five models over a wide range of policy preferences.
Optimal Design of Research Contests
Authors: Che Yeon-Koo , Gale Ian
Published: July 2003

Procurement of an innovation often requires substantial effort by potential suppliers. Motivating effort may be difficult if the level of effort and quality of the resulting innovation are unverifiable, if innovators cannot benefit directly by marketing their innovations, and if the buyer cannot extract up-front payments from suppliers. We study the use of contests to procure an innovation in such an environment. An auction in which two suppliers are invited to innovate and then bid their prizes is optimal in a large class of contests. If contestants are asymmetric, it is optimal to handicap the most efficient one.
What Do Bargainers' Preferences Look Like? Experiments with a Convex Ultimatum Game
Authors: Andreoni James , Castillo Marco , Petrie Ragan
Published: July 2003

The ultimatum game, by its all-or-nothing nature, makes it difficult to discern what kind of preferences may be generating choices. We explore a game that convexifies the decisions, allowing us a better look at the indifference curves of bargainers while maintaining the subgame-perfect equilibrium. We conclude that bargainers' preferences are convex and regular but not always monotonic. Money-maximization is the sole concern for about half of the subjects, while the other half reveal a preference for fairness. We also found, unexpectedly, the importance of risk aversion among money-maximizing proposers, which in turn generates significant bargaining power for fair-minded responders.
One Size Fits All? Heckscher-Ohlin Specialization in Global Production
Authors: Schott Peter K
Published: July 2003

This paper introduces a new technique for testing the Heckscher-Ohlin model that allows for the possibility that countries with sufficiently disparate endowments specialize in unique subsets of goods. Results based upon industry-level data reject one-size-fits-all homogeneity in favor of Heckscher-Ohlin specialization. Results also reveal that industry-level data hide substantial intra-industry heterogeneity, violating the assumptions of the model and complicating the interpretation of results from earlier research. A methodology for adjusting industry output to reflect underlying product variation is introduced. Reestimation of the model using adjusted aggregates in place of standard industry classifications provides strong support for Heckscher-Ohlin specialization.
A Theory of Defensive Skill-Biased Innovation and Globalization
Authors: Thoenig Mathias , Verdier Thierry
Published: July 2003

This paper considers a dynamic model of innovations in which firms can endogenously bias the direction of technological change. Both in a North–North and North–South context, we show that, when globalization triggers an increased threat of technological leapfrogging or imitation, firms tend to respond to that threat by biasing the direction of their innovations towards skilled-labor-intensive technologies. We show that this process of defensive skill-biased innovations generates an increase in wage inequalities in both regions. We then discuss suggestive empirical evidence of the existence of defensive skill-biased technical change.
School Choice: A Mechanism Design Approach
Authors: Abdulkadiroğlu Atila , Sönmez Tayfun
Published: July 2003

A central issue in school choice is the design of a student assignment mechanism. Education literature provides guidance for the design of such mechanisms but does not offer specific mechanisms. The flaws in the existing school choice plans result in appeals by unsatisfied parents. We formulate the school choice problem as a mechanism design problem and analyze some of the existing school choice plans including those in Boston, Columbus, Minneapolis, and Seattle. We show that these existing plans have serious shortcomings, and offer two alternative mechanisms each of which may provide a practical solution to some critical school choice issues.
Multiproduct Quality Competition:Fighting Brands and Product Line Pruning
Authors: Johnson Justin P , Myatt David P
Published: July 2003

Firms selling multiple quality-differentiated products frequently alter their product lines when a competitor enters the market. We present a model of multiproduct monopoly and duopoly using a general “upgrades” approach that yields a powerful analytical framework. We provide an explanation for the common strategies of using “fighting brands” and of product line “pruning.” The optimal strategy depends on whether entry prompts an incumbent to expand or contract its total output. We also present a general condition that guarantees that a monopolist will sell but a single product. Our model addresses other issues, including intertemporal price discrimination and “damaged goods.”
Information, International Substitutability, and Globalization
Authors: Rauch James E , Trindade Vitor
Published: July 2003

Improved information allows home firms to rule out more potential foreign trade partners in advance of attempting to form a match. The increased responsiveness to country wage or goods price differentials resulting from this better first cut causes the general-equilibrium elasticity of substitution between national labor forces or the Armington elasticity of substitution between domestic and imported output to increase. Further results include an increase in the elasticity of domestic labor demand, an increase in the extent to which reductions in conventional trade barriers equalize national wages, and reduced “natural protection” for domestic producers.
Do Government Grants to Private Charities Crowd Out Giving or Fund-raising?
Authors: Andreoni James , Payne A. Abigail
Published: July 2003

Economists have long observed that crowding out of government grants to private charities is incomplete. The accepted belief is that givers treat the grants as imperfect substitutes for private giving. We theoretically and empirically investigate a second reason: the strategic response of a charity will be to reduce fund-raising efforts after receiving a grant. Employing panel data from arts and social service organizations, we find that government grants cause significant reductions in fund-raising. This adds a new dimension to the policy discussions—analysts should account for the behavioral responses of the charity, as well as the donors, to government grants.
Forward and Backward Intergenerational Goods: Why Is Social Security Good for the Environment?
Authors: Rangel Antonio
Published: July 2003

This paper studies the ability of nonmarket institutions to invest optimally in forward intergenerational goods (FIGs), such as education and the environment, when agents are selfish or exhibit paternalistic altruism. We show that backward intergenerational goods (BIGs), such as social security, play a crucial role in sustaining investment in FIGs: without them investment is inefficiently low, but with them optimal investment is possible. We also show that making the provision of BIGs mandatory crowds out the voluntary provision of FIGs, and that population aging can increase investment in FIGs.
Relational Incentive Contracts
Authors: Levin Jonathan
Published: July 2003

Standard incentive theory models provide a rich framework for studying informational problems but assume that contracts can be perfectly enforced. This paper studies the design of self-enforced relational contracts. I show that optimal contracts often can take a simple stationary form, but that self-enforcement restricts promised compensation and affects incentive provision. With hidden information, it may be optimal for an agent to supply the same inefficient effort regardless of cost conditions. With moral hazard, optimal contracts involve just two levels of compensation. This is true even if performance measures are subjective, in which case optimal contracts terminate following poor performance.
Re-visioning refugee health: the Victorian Immigrant Health Programme
Authors: Murray S. B. , Skull S. A.
Published: July 2003

Few published data are available to support the development and management of health services for refugees in developed countries, despite evidence that refugees are at high risk of suffering a wide range of both physical and mental health problems. Meeting the health needs of increasing numbers of refugees worldwide in culturally acceptable and financially feasible ways is a key challenge to our healthcare systems. This paper reports on seven platforms identified in the development of the Victorian Immigrant Health Programme (VIHP) that the VIHP believes should underpin the management and delivery of healthcare to newly arrived refugees. Sharing this information facilitates and promotes essential collaborative work in the field of refugee health, and assists to prevent duplicate efforts, given constraints on resources for refugee healthcare provision in Australia and elsewhere.
Top-rated British business research: has the emperor got any clothes?
Authors: Lilford R. J. , Dobbie F. , Warren R. , Braunholtz D. , Boaden R.
Published: July 2003

Business schools have great prestige and charge large amounts of money for their courses. But how good is the science on which they base their prescriptions for action? To find out we examined the published output from the only three British business schools with the highest (5*) research assessment ranking at the time the articles were published. We conclude that theory development and model construction are often elegant. However, the methods used to obtain primary empirical information to confirm or refute the theories or populate models are poor, at least from a positivist or pragmatic ontological perspective. Large scale comparative studies made up only a small proportion of research output from the business schools. Literature reviews were not systematic. The sampling frame and rationale for selection of cases for study are inadequately described. The methods of data collection were frequently not given in sufficient detail to enable the study to be replicated and the conclusions tended to go far beyond what the data by themselves could support. However, this does not have to be the case-there are excellent examples of research in social sciences. We conclude, therefore, that top-rated British business research is a scantily clad emperor.
A province-wide study of the association between hospital resource allocation and length of stay
Authors: Needham Dale M. , Anderson Geoff , Pink George H. , McKillop Ian , Tomlinson George A. , Detsky Allan S.
Published: July 2003

The relationship between hospital resource allocation and clinical efficiency is poorly understood. Within the single-payer healthcare system in Ontario, Canada, the association between hospital spending patterns and length of stay was studied using data from 1117 090 patient discharges in 1997/8 at 162 of 171 acute care hospitals. A weighted regression model was created using an overall hospital length of stay index (actual length of stay divided by predicted length of stay) as the dependent variable. Control variables included: hospital size, teaching activity, occupancy rate, rural location and geographic region. Four independent spending variables were defined as a percentage of total hospital spending: nursing, ambulatory care, administration and support, and diagnostics and therapeutics. The reduced regression model had an r-squared of 0.45. Across all spending variables, hospitals spending relatively too little or too much had significantly longer length of stay. Hospitals' overall pattern of resource allocation was also significantly associated with length of stay. Thus, measurable clinical effects can be seen with resource allocation decisions made by hospital management, supporting the need for rigorous decision-making processes. Future research should focus on exploring the nature of this relationship and the potential interdependencies among hospital services that cause this effect.
Adoption of regulatory compliance programmes across United States healthcare organizations: a view of institutional disobedience
Authors: Lorence D. P. , Richards M. C.
Published: July 2003

The growing acceptance of evidence-based decision-support systems in healthcare organizations has resulted in recognition of information accuracy as a key area of organizational management. In the United States, rigid data mandates related to information management have met with some resistance from healthcare provider groups, who have traditionally found little relevance between personalized healthcare practice and accurate information. Variation in management practice poses quality problems in such an environment, since it precludes comparisons across larger markets or areas, a critical component of evidence-based quality assessments. In this study, a national census of health information managers was employed to provide a benchmark of the degree of such variation, examining how proper billing compliance practices vary across organization types as well as market area indicators. Findings here suggest that managers continue to ignore, to some extent, regulatory compliance standards, despite nationwide laws that mandate adoption of uniform compliance practices and programmes. The level of adoption of compliance management in this study varied significantly across practice characteristics and areas, suggesting the existence of barriers to cross-market comparative performance assessment.
Gaining and maintaining commitment to large-scale change in healthcare organizations
Authors: Narine L. , Persaud D. D.
Published: July 2003

Healthcare administrators have sought to improve the quality of healthcare services by using organizational change as a lever. Unfortunately, evaluations of organizational change efforts in areas such as total quality management (TQM), continuous quality improvement (CQI), and organizational restructuring have indicated that these change programmes have not fulfilled their promise in improving service delivery. Furthermore, there are no easy answers as to why so many large-scale change programmes are unsuccessful. The aim of this analysis is to provide insights into practices that may be utilized to improve the chances of successful change management. It is proposed that in order to effect change, implementers must first gain commitment to the change. This is done by ensuring organizational readiness for change, surfacing dissatisfaction with the present state, communicating a clear vision of the proposed change, promoting participation in the change effort, and developing a clear and consistent communication plan. However gaining commitment is not enough. Many change programmes have been initially perceived as being successful but long-term success has been elusive. Therefore, maintaining commitment during the uncertainty associated with the transition period is imperative. This can be done by successfully managing the transition using action steps such as consolidating change using feedback mechanisms and making the change a permanent part of the organization's culture.
The tendering process: flaws and all
Authors: Spurgeon Peter , Hicks Carolyn
Published: July 2003

The tendering process has become the dominant and now traditional approach to the allocation of research and consultancy projects. This is largely built around the notion that it ensures accountability and probity within the allocative procedure, and that high quality of work and 'value for money' are the outcomes. It appears to have become an institutionalized and unchallengeable process. Yet it is rarely costed in terms of the true resource implications for all the organizations involved, nor is quality assessed in terms of alternative processes that might be employed.

This paper explores the tendering process in terms of factors that may suggest that the quality of work produced via the tendering process is not always as good as it might be. Also in a hypothetical example involving the university sector and the National Health Service, data are presented indicating that the overall cost to the public sector is often actually greater than the value of the contract being allocated. An alternative preferred provider relationship-based allocative process is advocated as an improvement to the current established tendering procedure.
Break-even analysis revisited: the need to adjust for profitability, the collection rate and autonomous income
Authors: Broyles R. W. , Narine L. , Khaliq A.
Published: July 2003

This paper modifies traditional break-even analysis and develops a model that reflects the influence of variation in payer mix, the collection rate, profitability and autonomous income on the desired volume alternative. The augmented model indicates that a failure to adjust for uncollectibles and the net surplus results in a systematic understatement of the desired volume alternative. Conversely, a failure to adjust for autonomous income derived from the operation of cafeterias, gift shops or an organization's investment in marketable securities produces an overstatement of the desired volume. In addition, this paper uses Microsoft® Excel to develop a spreadsheet that constructs a pro forma income statement, expressed in terms of the contribution margin. The spreadsheet also relies on the percentage of sales or revenue approach to prepare a balance sheet from which indicators of fiscal performance are calculated. Hence, the analysis enables the organization to perform a sensitivity analysis of potential changes in the desired volume, the operating margin, the current ratio, the debt: equity ratio and the amount of cash derived from operations that are associated with expected variation in payer mix, the collection rate, grouped by payer, the net surplus and autonomous income.
Constructing management practice in the new public management: the case of mental health managers
Authors: Connolly M. , Jones N.
Published: July 2003

There has been a growth in managerialism of professionals in the Public Sector. This paper contributes to this debate by examining perceptions of senior managers in mental health services within Health Authorities, NHS Trusts and Local Authorities' Social Services departments in Wales. The paper explores how different professions responded differently to the growth of managerialism. The results suggest important differences and similarities between management in health and social services settings.
Success and failure: a case study of two rural telemedicine projects
Authors: Whitten Pamela , Adams Inez
Published: July 2003

We studied two rural telemedicine projects in the state of Michigan: one that enjoyed success and steady growth in activity, and one that experienced frustration and a lack of clinical utilization. Multiple data collection strategies were employed during study periods, which lasted approximately one year. Both projects enjoyed a grassroots approach and had dedicated project coordinators. However, the more successful project benefited from resources and expertise not available to the less successful project. In addition, the more successful project possessed a more formalized organizational structure for the telemedicine application. A comparison of the two projects leads to a simple conclusion. Telemedicine programmes are positioned within larger health organizations and do not operate in a vacuum. It is crucial that the organization in which it is intended to launch telemedicine is examined carefully first. Each organization operates within a larger environment, which is often constrained by fiscal, geographical and personnel factors. All these will affect the introduction of telemedicine.