Preemption in Capacity and Price Determination - A Study of Endogenous Timing of Decisions for Homogeneous Markets

Endogenous timing can help to derive the time structure of decision making instead of assuming it as exogenously given. In our study we consider a homogeneous market where, like in the model of Kreps and Scheinkman (1983), sellers determine "sales capacities" before prices. Sellers must serve customers, but at higher costs when demand exceeds "capacitiy". Our model allows for preemption in "capacity" as well as in price determination. Since preemption means to decide before the random choice of cost parameters reflecting the stochastic nature of (excess) "capacity" costs, preemptive commitments are no obviously better timing dispositions.

Surface and bottom boundary layer dynamics on a shallow submarine bank : southern flank of Georges Bank

Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution August 1999The thesis investigates the circulation at a 76-m deep study site on the southern flank of Georges Bank, a shallow submarine bank located between the deeper Gulf of Maine and the continental slope. Emphasis is placed on the vertical structure of the bottom boundary layer driven by the semi diurnal tides and the flow field's response to wind forcing. The observational analysis presented here is based on a combination of moored array and bottom tripod-mounted current, temperature, conductivity, and meteorological data taken between February and August 1995. Results from the bottom boundary layer analysis are compared to numerical model predictions for tidal flow over rough bottom topography. The flow response to wind forcing is examined and brought into context with the existing understanding of the wind-induced circulation in the Georges Bank region. Particular attention is given to the vertical distribution of the wind-driven currents, whose variation with background stratification is discussed and compared to observations from open ocean studies.The research presented in this thesis was generously supported by the National Science Foundation under grants OCE 93-13671 and OCE 96-32357 as part of the U.S. GLOBEC/Georges Bank Program

Analyzing coarsened categorical data with or without probabilistic information

In some applications, only a coarsened version of a categorical outcome variable can be observed. Parametric inference based on the maximum likelihood approach is feasible in principle, but it cannot be covered computationally by standard software tools. In this article, we present two commands facilitating maximum likelihood estimation in this situation for a wide range of parametric models for categorical outcomes-in the cases both of a nominal and an ordinal scale. In particular, the case of probabilistic information about the possible values of the outcome variable is also covered. Two examples motivating this scenario are presented and analyzed

Drivers of greener print choices: an exploratory study of print consumer environmentalism

Not Include

Effekt von endogenem und exogenem FGF-2 auf die hippokampale Neurogenese

Die Literatur beschreibt den Fibroblasten-Wachstumsfaktor -2 (FGF-2) als einen wesentlichen Faktor der Regulation der Neurogenese. Die adulte Neurogenese findet hauptsächlich in der subventrikulären Zone der lateralen Ventrikel sowie der subgranulären Zone des Gyrus Dentatus (DG) statt. Die meisten Studien untersuchten den Einfluss von exogen appliziertem FGF-2 auf die Proliferation der Zellen. Wir waren daran interessiert, die Rolle des endogenen FGF-2 auf proliferierende, differenzierende und migrierende Zellen der Neurogenese im DG zu untersuchen. Durch immunhistochemische Untersuchungen mit Markern für proliferierende, differenzierende und migrierende Zellen im DG der FGF-2+/+ und der FGF-2-/- Mäuse konnten wir feststellen, dass das Fehlen des endogenen FGF-2 zu einer drastischen Reduktion der Neurogenese führt und eine Erhöhung des Zelltodes zur Folge hat. An hippokampalen Slices untersuchten wir, ob der Verlust des endogenen FGF-2 und die damit verbundene Reduktion der Neurogenese sowie der ansteigende Zelltod durch die akute Zugabe von exogenem FGF-2 kompensiert werden kann. Die Ergebnisse zeigen, dass durch die akute Behandlung der FGF-2-/- Slices mit FGF-2 weder die Reduktion der Neurogenese noch die Erhöhung des Zelltodes kompensiert werden. Auch die akute Blockierung des endogenen FGF-2 mittels eines FGF-2 neutralisierenden Antikörpers zeigte keinen Einfluss auf die hippokampale Neurogenese, ein wichtiger Hinweis, dass der FGF-2-/- Phänotyp wahrscheinlich nicht auf einem akuten FGF-2-Mangel beruht, sondern wahrscheinlich komplexere Ursachen hat. Weiterhin wurde der Einfluss des Alterns sowie der Einfluss von FGF-2 im Alter auf die Neurogenese untersucht. Immunhistochemisch konnten wir zeigen, dass die Neurogenese im Alter noch statt findet, aber drastisch reduziert ist. Endogenes FGF-2 scheint im Alter weniger wichtig für die Neurogenese zu sein. Es wurden keine signifikanten Unterschiede in der Anzahl neurogenetischer Zellen im DG alter FGF-2+/+ und FGF-2-/- Mäuse beobachtet. Ein klinischer Aspekt dieser Arbeit war die Untersuchung des Zusammenhanges zwischen Depressionen und Neurogenese. Es ist bekannt, dass sich während der Depression das hippokampale Volumen und auch die Neurogenese verringert. Mittels immunhistochemischer Studien konnten wir die Reduktion der Neurogenese in bulbektomierten Mäusen (Depressionsmodel) bestätigen. Da Serotonin in die Regulation der Depression involviert sein soll und auch einen mitogenen Effekt auf die Neurogenese zu haben scheint, haben wir den Effekt der Antidepressiva Amitriptylin und Citalopram untersucht. Nach der Behandlung der bulbektomierten Tiere mit diesen Antidepressiva konnten wir immunhistochemisch keine Steigerung der Neurogenese beobachten. Da FGF-2, wie oben bereits beschrieben, die Neurogenese fördern soll, haben wir den Einfluss von FGF-2 auf die Neurogenese bulbektomierter Tiere untersucht. Die Applikation von FGF-2 in die Ventrikel bulbektomierter Tiere zeigte keinen signifikanten Effekt auf die Neurogenese. Zusammenfassend scheint FGF-2 ein bedeutender Faktor der Neurogenese zu sein, welcher weniger allein, sondern über die Involvierung in weitere Signalwege das Überleben der Zellen sowie deren Differenzierung und Migration fördert

Surface and bottom boundary layer dynamics on a shallow submarine bank : southern flank of Georges Bank

Thesis (Ph. D.)--Joint Program in Physical Oceanography (Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences; and the Woods Hole Oceanographic Institution), 1999.Includes bibliographical references.The thesis investigates the circulation at a 76-m deep study site on the southern flank of Georges Bank, a shallow submarine bank located between the deeper Gulf of Maine and the continental slope. Emphasis is placed on the vertical structure of the bottom boundary layer driven by the semidiurnal tides and the flow field's response to wind forcing. The observational analysis presented here is based on a combination of moored array and bottom tripod-mounted current, temperature, conductivity, and meteorological data taken between February and August 1995. Results from the bottom boundary layer analysis are compared to numerical model predictions for tidal flow over rough bottom topography. The flow response to wind forcing is examined and brought into context with the existing understanding of the wind-induced circulation in the Georges Bank region. Particular attention is given to the vertical distribution of the wind-driven currents, whose variation with background stratification is discussed and compared to observations from open ocean studies.by Sandra Regina Warner.Ph.D

The vertical structure of the bottom boundary layer on the southern flank of the George Bank during late winter

Thesis (B.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1996.Includes bibliographical references (p. 81-83).by Sandra R. Werner.B.S

Age-at-death estimation in archaeological samples: Differences in population means resulting from different aging methods can be predicted from the mean ages of method-specific reference samples

Age mimicry is a well-known phenomenon in the application of osteological age-estimation methods. Age mimicry refers to the fact that predicting age-at-death from a specific trait (age indicator) based on the relation observed in a specific reference sample implies that age estimates to some degree reflect the age structure of the reference sample. In particular, the estimated population mean in a target population in which an age-estimation method is applied is shifted towards the mean in the method-specific reference sample. Consequently, differences in population means between different age-estimation methods in the same target population may be due to differences in mean age of the reference samples used to develop the age-estimation methods. We aim at quantifying the expected magnitude for such differences. Fifteen different traditional age-estimation methods were applied to a sample of 675 adult individuals from the early medieval cemetery of Mannheim-Seckenheim. The relation of the observed estimated population age means and the mean age in the reference samples was analyzed by linear regression. We find that up to 80% of the variation in the estimated population age means can be explained by the variation of the mean age in the reference samples. Furthermore, differences in the magnitude of 3 to 4 years in the mean age between two reference samples can imply a 1-year difference in estimated target population age means. Because large differences in mean age between reference samples used to develop different age-estimation methods are common, some care is needed in interpreting differences between individual age estimates or population mean age estimates in cases where different age-estimation techniques are used

Modulation of the Sympatho-Vagal Balance during Sleep: Frequency Domain Study of Heart Rate Variability and Respiration

Sleep is a complex state characterized by important changes in the autonomic modulation of the cardiovascular activity. Heart rate variability (HRV) greatly changes during different sleep stages, showing a predominant parasympathetic drive to the heart during non-rapid eye movement (NREM) sleep and an increased sympathetic activity during rapid eye movement (REM) sleep. Respiration undergoes important modifications as well, becoming deeper and more regular with deep sleep and shallower and more frequent during REM sleep. The aim of the present study is to assess both autonomic cardiac regulation and cardiopulmonary coupling variations during different sleep stages in healthy subjects, using spectral and cross-spectral analysis of the HRV and respiration signals. Polysomnographic sleep recordings were performed in 11 healthy women and the HRV signal and the respiration signal were obtained. The spectral and cross-spectral parameters of the HRV signal and of the respiration signal were computed at low frequency and at breathing frequency (high frequency, HF) during different sleep stages. Results attested a sympatho-vagal balance shift toward parasympathetic modulation during NREM sleep and toward sympathetic modulation during REM sleep. Spectral analysis of the HRV signal and of the respiration signal indicated a higher respiration regularity during deep sleep, and a higher parasympathetic drive was also confirmed by an increase in the coherence between the HRV and the respiration signal in the HF band during NREM sleep. Our findings about sleep stage-dependent variations in the HRV signal and in the respiratory activity are in line with previous evidences and confirm spectral analysis of the HRV and the respiration signal to be a suitable tool for investigating cardiac autonomic modulation and cardio-respiratory coupling during sleep

Wohlergehen von Bioschweinen und Umweltwirkungen – (k)ein Widerspruch? Haltungssysteme der Bio-Schweine in Europa im Vergleich

Das Haltungssystem hat Einfluss auf Gesundheit, Wohlergehen und Umweltauswirkungen von Bioschweinen; Freilandhaltung ist grundsätzlich vorteilhaft für das Tierwohlergehen und teilweise Freilandhaltung hinsichtlich Umweltwirkung. Durch gutes Management können jedoch grundsätzlich in jedem System gute Ergebnisse erzielt werden. Die Ergebnisse der Studie können als Basis der Weiterentwicklung der Bioschweinehaltungssysteme in Europa dienen. Sofern die Voraussetzungen am Betrieb gegeben sind (z.B. ausreichend Flächen) und gutes Management gewährleistet ist, können Stallhaltungsbetriebe das Tierwohlergehen steigern, indem beispielsweise die Sauen saisonal im Freiland gehalten werden. Andererseits kann die Umweltwirkung mancher Freilandbetriebe voraussichtlich reduziert werden, indem Mastschweine teilweise im Stall gehalten werden. Das Haltungssystem sollte jedenfalls den Möglichkeiten des Betriebes entsprechen