bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Core of a Production Economy with Asymmetric Information
Authors: Schwalbe Ulrich 
Published: October 2003

ABSTRACTThe paper analyses the core of a production economy with asymmetric information. Due to the incompleteness of information the transactions an agent can make are restricted. However, if the agent joins a coalition, his information changes according to an exogenously given information rule. The production possibilities of a coalition are described by a technology set and information that the coalition can employ in production. This information depends on the information of the coalition members and is also described by an information rule. Given that the technology sets satisfy some regularity conditions, a production economy with asymmetric information generates a well‐defined cooperative game. It is shown that the core of this game and thus the core of the underlying economy is non‐empty provided that the technology sets satisfy a balancedness condition. This result holds independently of the given information rules.
Regimes of Interest Rates, Income Shares, Savings and Investment: A Kaleckian Model and Empirical Estimations for some Advanced OECD Economies
Authors: Hein Eckhard , Ochsen Carsten 
Published: October 2003

ABSTRACTThe first part of the paper deals with the effects of an exogenous variation in the monetary interest rate on the real equilibrium position of the economic system in a Kaleckian effective demand model. Different regimes of accumulation are derived and it is shown that a negative relation between the interest rate and the equilibrium rates of capacity utilization, accumulation and profit usually expected in post‐Keynesian theory only exists under special conditions. In the second part the model is applied to the data of some major OECD countries, the relevant coefficients are estimated and the relevance for an explanation of the course of GDP and capital stock growth since the early 1960s is discussed.
Wage Hikes as Supply and Demand Shock
Authors: Jerger Jürgen , Michaelis Jochen 
Published: October 2003

ABSTRACTWage hikes affect production costs and hence are usually analysed as supply shocks. There is a long‐standing debate, however, about demand effects of wage variations. In this paper, we bring together these two arguments in a Kaldorian model with group‐specific saving rates and a production technology that allows for redistribution between workers and entrepreneurs following a wage hike. We thereby pinpoint the conditions under which (a) wage variations affect aggregate demand and (b) the positive demand effects of wage hikes may even overcompensate the negative supply effects on aggregate employment (‘purchasing power argument’). We conclude by noting that, whereas demand effects are very likely to occur, the conditions under which the purchasing power argument does indeed hold are very unrealistic.
Contracts, the Spot Market Wage and Unemployment Benefits
Authors: Skåtun John Douglas , Theodossiou Ioannis 
Published: October 2003

ABSTRACTThis paper presents a model of the labour market with a contract and a spot market sector. Contracts are binding and enforceable, but unemployed contract workers are free to work in the spot market. The contracting wage is shown to be constant across states. A non‐trivial result shows that the spot market wage is increasing with product price. An increase in product price has an ambiguous effect on contract employment. An increase in unemployment benefits increases the contracting sector wage whilst stabilizing the spot market wage, and may have ambiguous effects on unemployment.
Mortality, the Trade‐off between Child Quality and Quantity, and Demo‐economic Development
Authors: Strulik Holger 
Published: October 2003

ABSTRACTAn economy is investigated where parents observe wage rates, interest rates and child mortality and decide about savings and the quantity and quality of their children. Expenditure on child quality causes human capital accumulation as an external effect. If mortality is high parents prefer to have many children and spend only essential rearing effort. Without human capital accumulation the economy may stabilize in an equilibrium of economic stagnation and high population growth. If mortality is low parents prefer to have only few children and spend comparatively large fractions of income on their quality. With human capital accumulation the economy is capable of long‐run growth. The paper also shows the possibility of an endogenously explained demographic transition and a development aid program on education is discussed.
Representative Layer Theory for Diffuse Reflectance
Authors: Dahm Donald J. , Dahm Kevin D. 
Published: October 2003

The fractions of light absorbed by and remitted from samples consisting of different numbers of plane parallel layers can be related with the use of statistical equations. The fractions of incident light absorbed ( A), remitted ( R), and transmitted ( T) by a sample of any thickness can be related by an absorption/remission function, A( R,T): A( R,T) = [(1 - R)2 - T2]/ R = (2 - A - 2 R) A/ R = 2 A0/ R0. Being independent of sample thickness, this function is a material property in the same sense as is the linear absorption coefficient in transmission spectroscopy. The absorption and remission coefficients for the samples are obtained by extrapolating the measured absorption and remission fractions for real layers to the fraction absorbed ( A0) and remitted ( R0) by a hypothetical layer of infinitesimal thickness. A sample of particulate solids can be modeled as a series of layers, each of which is representative of the sample as a whole. In order for the layer to be representative of the properties of the individual particles of which it is comprised, it should nowhere be more than a single particle thick, and should have the same void fraction as the sample; further, the volume fraction and cross-sectional surface area fraction of each particle type in the layer should be identical to its volume fraction and surface area fraction in the sample as a whole. At lower absorption levels, the contribution of a particle of a particular type to the absorption of a sample is approximately weighted in proportion to its volume fraction, while its contribution to remission is approximately weighted in proportion to the fraction of cross-sectional surface area that the particle type makes up in the representative layer.
Intermittent parathyroid hormone (1–34) enhances mechanical strength and density of new bone after distraction osteogenesis in rats
Authors: Seebach C. , Skripitz R. , Andreassen T. T. , Aspenberg P. 
Published: October 2003

AbstractDistraction osteogenesis is used both for leg lengthening and for bone transportation in the treatment of fractures and non‐unions. The main problem with this method is that the time until full recovery may be up to a year, partly because of the time needed for the new formed bone to consolidate and become strong enough for weight bearing. We have studied whether intermittent parathyroid hormone (PTH(1–34)) could accelerate the consolidation of new formed bone after distraction osteogenesis in rats. Forty‐seven, 3‐months‐old male Sprague–Dawley rats underwent lengthening of the right femur using an external fixator. After a middiaphyseal osteotomy and a 7‐day latency period, the callus was distracted during 10 days, with a distraction rate of 0.25 mm twice a day. The consolidation time was either 20 days or 40 days after distraction was completed. A dose of 60 μg of human PTH(1–34)/kg body weight/injection or vehicle was given every second day beginning 30 days before the rats were killed. Both femura of each rat were subjected to mechanical testing and dual‐energy X‐ray absorptiometry. Blinded histological examination was done for the distracted femura.In the 20 days consolidation experiment, PTH(1–34) increased ultimate load (56%), stiffness (117%), total regenerate callus volume (58%), callus BMC (24%) and histologic bone density (35%) compared to untreated distraction osteogenesis specimens. In the 40 days consolidation experiment, PTH(1–34) increased ultimate load (54%), stiffness (55%), callus BMC (33%) and histologic bone density (23%) compared to untreated distraction osteogenesis specimens. Total regenerate callus volume was unchanged.The contralateral femur also became stronger, stiffer and denser under PTH(1–34) treatment, but to a lesser degree. PTH(1–34) might become useful to shorten the consolidation time after distraction osteogenesis in humans. © 2003 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved.
The response of benthic rhizopods to sediment disturbance does not support the intermediate disturbance hypothesis
Authors: Garstecki Tobias , Wickham Stephen A. 
Published: October 2003

Disturbance is one of the mechanisms which counteract competitive exclusion of populations in resource‐limited communities, thereby facilitating coexistence and maintaining community species diversity. The intermediate disturbance hypothesis predicts maximum diversity at intermediate disturbance intensities and frequencies. This paper reports results of an experimental test of this hypothesis using a coastal benthic community of rhizopods (Protozoa: Rhizopoda), and experimental sediment resuspension as a simulated natural disturbance. We carried out two experiments of 5 d duration which focussed on the effects of resuspension intensity and frequency, respectively, on the abundance, species richness and on the Shannon‐Weaver diversity index of rhizopod communities in surface sediments of natural sediment cores from the coastal southern Baltic. Care was taken to adjust the experimental treatments to the natural disturbance regime in this area.Twenty‐four and 28 rhizopod species were present during the intensity and frequency experiment, respectively. Small bacterivorous rhizopods of the Vannellidae, Cochliopodidae, Paramoebidae and Rhizopoda incertae sedis dominated the communities during both experiments. Rhizopod abundance, species richness and diversity increased towards the end of the intensity experiment, but they did not show effects of disturbance intensity. Similarly, no effects of disturbance frequency were found during the frequency experiment. Our results indicate that coexistence and community diversity maintenance in benthic rhizopod communities, and probably in benthic heterotrophic protistan communities in general, may rely on different mechanisms than intermediate disturbance, such as trophic niche separation and high rates of dispersal and colonisation.
How litter quality affects mass loss and N loss from decomposing Sphagnum
Authors: Limpens Juul , Berendse Frank 
Published: October 2003

Nitrogen (N) deposition may affect litter decomposition and may thus have an impact on the rate of carbon (C) sequestration in Sphagnum peatlands. We present results from four separate experiments aimed at delineating the effects of litter N‐enrichment, Sphagnum species, stem part of Sphagnum, and place of incubation on decomposition rate and N release. We measured mass loss and N loss from litterbags incubated at 10‐15 cm in the field for one year.Mass loss was positively related to the N/C quotient of the litter, but depended strongly on the range in N/C quotients observed; only a distinct difference in N/C quotients affected mass loss. Although hummock species decayed at a slower rate than hollow species, the differences between the species became less pronounced for old stem parts and for N‐enriched litter. Old stem parts decayed at a slower rate than young stem parts, except for S. papillosum. Neither position of incubation (low hummock or hollow), nor the inorganic N concentration of the incubation environment affected mass loss. N loss was mainly determined by, and positively related to, the N/C quotient of the litter; species and stem part had minor effects. Above a N/C quotient of about 0.015, net N loss was observed for all species.We conclude that decomposition of Sphagnum is stimulated by N deposition. As the latter also affects litter N concentration and thus N release, we think that positive feedbacks through changing litter quality should be taken into account when modelling the effects of N deposition on Sphagnum peatlands and C sequestration in these systems.
Neuropeptide Y (NPY) Delays the Oestrogen‐Induced Luteinizing Hormone (LH) Surge in the Ovariectomized Ewe: Further Evidence That NPY has a Predominant Negative Effect on LH Secretion in the Ewe
Authors: Estrada K. M. , Pompolo S. , Morris M. J. , Tilbrook A. J. , Clarke I. J. 
Published: October 2003

AbstractStudies in rats suggest that neuropeptide Y (NPY) plays a stimulatory role in the generation of the preovulatory luteinizing hormone (LH) surge, via the Y1 receptor. We have investigated this issue using the oestradiol benzoate (EB)‐treated ovariectomized (OVX) ewe which is a model for the preovulatory LH surge. A Y1 receptor antagonist (BIBO3304) was infused (25 µg/h) into the third cerebral ventricle (III‐V) from 2 h before EB injection for 24 h, and had no effect on the ensuing LH surge. Using in situ hybridization, we then examined expression of NPY mRNA in the arcuate nucleus during the luteal, follicular and oestrous phases of the oestrous cycle, and found that levels were greatest during the luteal phase. Thus, reduced NPY synthesis might be an integral factor in the events leading to the cyclic preovulatory LH surge. This was tested by infusion of NPY (25 µg/h) into the III‐V (as above). The NPY infusion delayed the LH surge until the infusion was ceased. High levels of NPY expression during the luteal phase of the oestrous cycle may be caused by progesterone. Thus, we determined whether NPY cells possess progesterone receptors (PR) and whether progesterone treatment up‐regulates NPY mRNA expression in the arcuate nucleus. Immunohistochemistry for NPY and PR was performed in OVX, oestrogen‐treated ewes, but no NPY cells of the arcuate nucleus were seen to colocalize PR. In situ hybridization for NPY was performed in OVX and OVX ewes treated with progesterone. There was no significant effect of progesterone treatment on NPY mRNA expression in the arcuate nucleus. We conclude that chronically elevated levels of NPY block the preovulatory surge of gonadotropin‐releasing hormone/LH secretion in sheep, but high levels of NPY mRNA expression in the luteal phase of the oestrous cycle cannot be explained by an action of progesterone.
Neurone‐Specific Expression and Regulation of the Pufferfish Isotocin and Vasotocin Genes in Transgenic Mice
Authors: Gilligan P. , Brenner S. , Venkatesh B. 
Published: October 2003

AbstractWe used comparative genetics to investigate the location, structure and evolution of the oxytocin and vasopressin gene regulatory regions. The pufferfish, Fugu rubripes, is an attractive vertebrate model for comparison because of its maximal evolutionary distance from mammals and short intergenic regions. To determine whether regulatory DNA is conserved between oxytocin and vasopressin, and their Fugu homologs, isotocin and vasotocin, we generated transgenic mice bearing overlapping Fugu cosmids that contained the isotocin and/or vasotocin genes as well as short isotocin (5 kb) and vasotocin (9 kb) constructs. Our study shows that the Fugu isotocin and vasotocin genes express specifically in the mouse oxytocinergic and vasopressinergic neurones, respectively, and that the cis‐regulatory elements which mediate neurone‐specific expression are located within the short transgene constructs tested. Thus, the neurone‐specific expression of the oxytocin and vasopressin gene families, and the mechanisms mediating the cell‐specificity, evolved before the divergence of the fish and mammalian lineages. Salt‐loading of transgenic mice induced an increase in abundance of isotocin, but not vasotocin mRNA in the cognate neurones. It appears that either the vasotocin gene does not respond to osmotic perturbations or the vasotocin transgene construct tested lacks osmotic response elements. Comparisons of homologous flanking sequences of the Fugu and mouse genes identified several short matching sequences, which are candidate regulatory elements.
Food Restriction During Lactation Results in Prolonged Hyposensitivity to the Positive‐Feedback Effects of Oestradiol
Authors: Abizaid A. , Service G. , Woodside B. 
Published: October 2003

AbstractFood restriction prolongs lactational infertility in rats. Here, we investigated whether an attenuated response to the positive‐feedback effects of oestrogen on luteinizing hormone release contributed to this effect. The ability of oestrogen to induce surges in luteinizing hormone in ad libitum fed and food‐restricted dams at different times of lactation was compared. The results showed that, on day 20 postpartum, ad libitum fed dams showed luteinizing hormone surges after oestrogen treatment, but food‐restricted dams did not. Ovariectomy or RU486 treatment restored the ability of oestrogen to induce luteinizing hormone surges in food‐restricted dams, and chronic progesterone exposure reduced oestrogen‐induced surges of luteinizing hormone in ad libitum fed ovariectomized dams. Food restriction also resulted in a reduced ability of oestrogen to induce progesterone receptor immunoreactivity, but did not reduce the number of oestrogen receptors (ERα) in the anteroventralperiventricular area. As with the surge in luteinizing hormone, the effects of food restriction on oestrogen induction of progesterone receptors were mediated by progesterone. Together, these results suggest that the ability of food restriction to extend the length of lactational diestrus is mediated, in part, by a decrease in sensitivity to the positive‐feedback effects of oestrogen. This results from high circulating concentrations of progesterone which apparently reduce the ability of oestrogen to induce progesterone receptor expression.
Changes in Agouti‐Related Peptide During the Ring Dove Breeding Cycle in Relation to Prolactin and Parental Hyperphagia
Authors: Strader A. D. , Buntin J. D. 
Published: October 2003

AbstractRing doves (Streptopelia risoria) exhibit marked increases in food consumption and decreases in body weight when they are provisioning their young. This study examined changes in hypothalamic immunostaining for agouti‐related peptide (AGRP), an endogenous melanocortin receptor antagonist and appetite stimulant, during the ring dove breeding cycle. Because prolactin is orexigenic in doves, and is elevated in blood at the onset of parental hyperphagia, we also explored the possibility that prolactin‐induced hyperphagia is associated with AGRP changes. The numbers of AGRP‐immunoreactive (ir) cells within the tuberal hypothalamus were maximal during the prelaying period of the breeding cycle but decreased dramatically during early incubation. AGRP‐ir cell numbers began to increase again during late incubation and reached a peak during the early and late posthatching stages. Because posthatching elevations in AGRP‐ir were temporally associated with marked elevations in parental food intake, and because AGRP is orexigenic in doves, these findings suggest that increased AGRP activity in the dove tuberal hypothalamus may contribute to parental hyperphagia. Rising prolactin secretion during late incubation and early posthatching may initiate this increase in AGRP‐ir, since intracerebroventricular administration of prolactin significantly elevated food intake and AGRP‐ir cell numbers in the tuberal hypothalamus of nonbreeding doves. Prolactin‐induced elevations in AGRP‐ir cell numbers persisted when the confounding effects of weight gain that accompany prolactin‐induced hyperphagia in nonbreeding doves were eliminated by a food restriction procedure, thereby suggesting that prolactin can directly influence AGRP activity under neutral energy state conditions.
Enhanced Up‐Regulation of Corticotropin‐Releasing Hormone Gene Expression in Response to Restraint Stress in the Hypothalamic Paraventricular Nucleus of Oxytocin Gene‐Deficient Male Mice
Authors: Nomura M. , Saito J. , Ueta Y. , Muglia L. J. , Pfaff D. W. , Ogawa S. 
Published: October 2003

AbstractThe neuropeptide oxytocin is released not only into the blood, but also within the brain in response to various stressors. Accumulating evidence suggests that central oxytocin may play a major role in the regulation of neuroendocrine responses to stress. In the present study, using the oxytocin knockout mouse model, we tested whether oxytocin might act to attenuate stress‐induced up‐regulation of corticotropin‐releasing hormone (CRH) mRNA expression in the brain. The expression of CRH mRNA in the paraventricular nucleus (PVN) after 4 h of restraint stress was examined in oxytocin gene‐deficient (OTKO), wild‐type and heterozygous male mice using in situ hybridization histochemistry. We found that basal levels of CRH mRNA were not different among the three genotypes. Although restraint stress resulted in a significant increase of CRH mRNA expression in the PVN regardless of genotype, the degree of stress induced‐up‐regulation was significantly higher in OTKO mice than in wild‐type mice. The effects of restraint stress on the expression of the arginine vasopressin (AVP) and the oxytocin genes were also examined. Unlike CRH mRNA, basal expression (in nonstressed control groups) of AVP mRNA in OTKO mice, as well as oxytocin mRNA in heterozygous mice, was significantly lower in the PVN and the supraoptic nucleus than in wild‐type mice. After restraint stress, the expression of AVP mRNA was significantly increased in the PVN of OTKO mice compared to the nonstressed control group, whereas the expression of both AVP and oxytocin mRNA were unchanged in the PVN and the supraoptic nucleus of wild‐type and heterozygous mice. Finally, in a separate set of mice, restraint stress‐induced Fos expression was also examined in several brain regions involved in stress response, including the lateral septum, the bed nucleus of the stria terminalis (BNST), the medial preoptic area, the PVN, the medial and central amygdala using immunohistochemistry. After 90 min of restraint stress, the number of Fos‐expressing cells significantly increased in all brain regions examined regardless of genotype. However, the number of stress‐induced Fos‐expressing cells in the BNST and the medial amygdala of OTKO mice was significantly lower than in wild‐type mice. Collectively, the findings in the present study suggest that oxytocin may regulate stress‐induced CRH gene expression in the PVN. Furthermore, neuronal activity in the BNST and the medial amygdala may be involved in this neuroendocrine regulatory system.