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Empirical Models Of Auctions, Susan Athey, Philip A. Haile Mar 2006

Empirical Models Of Auctions, Susan Athey, Philip A. Haile

Cowles Foundation Discussion Papers

Many important economic questions arising in auctions can be answered only with knowledge of the underlying primitive distributions governing bidder demand and information. An active literature has developed aiming to estimate these primitives by exploiting restrictions from economic theory as part of the econometric model used to interpret auction data. We review some highlights of this recent literature, focusing on identification and empirical applications. We describe three insights that underlie much of the recent methodological progress in this area and discuss some of the ways these insights have been extended to richer models allowing more convincing empirical applications. We discuss …

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Optimal Pricing With Recommender Systems, Dirk Bergemann, Deran Ozmen Mar 2006

Optimal Pricing With Recommender Systems, Dirk Bergemann, Deran Ozmen

Cowles Foundation Discussion Papers

We study optimal pricing in the presence of recommender systems. A recommender system affects the market in two ways: (i) it creates value by reducing product uncertainty for the customers and hence (ii) its recommendations can be offered as add-ons which generate informational externalities. The quality of the recommendation add-on is endogenously determined by sales. We investigate the impact of these factors on the optimal pricing by a seller with a recommender system against a competitive fringe without such a system. If the recommender system is sufficiently effective in reducing uncertainty, then the seller prices otherwise symmetric products differently to …

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Fitch Revises Iceland's Outlook To Negative On Widening Macro Imbalances, Fitch Ratings Feb 2006

Fitch Revises Iceland's Outlook To Negative On Widening Macro Imbalances, Fitch Ratings

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No abstract provided.

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Fannie Mae 2006 Overview Plan, Robert Levin Feb 2006

Fannie Mae 2006 Overview Plan, Robert Levin

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No abstract provided.

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Frb Memo From Divisioin Of Banking Supervision And Regulation To Governor Bies Re Upgrade Of Citigroups Risk Management Rating, Federal Reserve System: Board Of Governors Feb 2006

Frb Memo From Divisioin Of Banking Supervision And Regulation To Governor Bies Re Upgrade Of Citigroups Risk Management Rating, Federal Reserve System: Board Of Governors

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No abstract provided.

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Chomsisengphet And Pennington-Cross, The Evolution Of The Subprime Mortgage Market, Souphala Chomsisengphet, Anthony Pennington-Cross Feb 2006

Chomsisengphet And Pennington-Cross, The Evolution Of The Subprime Mortgage Market, Souphala Chomsisengphet, Anthony Pennington-Cross

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No abstract provided.

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Project Performance Assessment Report, World Bank/World Bank Group Jan 2006

Project Performance Assessment Report, World Bank/World Bank Group

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No abstract provided.

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Sec Ocie Entrance Exam Of Bear Stearns, Securities And Exchange Commission: Office Of Compliance Inspections And Examinations (Ocie) Jan 2006

Sec Ocie Entrance Exam Of Bear Stearns, Securities And Exchange Commission: Office Of Compliance Inspections And Examinations (Ocie)

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No abstract provided.

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Ofheo Office Of Examination Ltr To Richard Syron, Jeffrey S. Spohn Jan 2006

Ofheo Office Of Examination Ltr To Richard Syron, Jeffrey S. Spohn

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No abstract provided.

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Herber Sadler Letter To The Ots, The Federal Reserve, Occ, And Fdic Regarding Comment On Joint Advance Notice Of Proposed Rule-Making For Proposed Revisions To The Existing Risk-Based Capital Rules, Herbert Sandler Jan 2006

Herber Sadler Letter To The Ots, The Federal Reserve, Occ, And Fdic Regarding Comment On Joint Advance Notice Of Proposed Rule-Making For Proposed Revisions To The Existing Risk-Based Capital Rules, Herbert Sandler

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No abstract provided.

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Constraining Bubble Dynamics And Mixing With Dissolved Gases: Implications For Productivity Measurements By Oxygen Mass Balance, Roberta C. Hamme, Steven R. Emerson Jan 2006

Constraining Bubble Dynamics And Mixing With Dissolved Gases: Implications For Productivity Measurements By Oxygen Mass Balance, Roberta C. Hamme, Steven R. Emerson

Journal of Marine Research

We used a dynamic mixed layer model to determine carbon export by the oxygen mass balance method from a time series of O2/Ar, N2/Ar and Ne measurements collected at station ALOHA near Hawaii from July 2000 to June 2001. The inert gas measurements constrain the flux of oxygen into the mixed layer from small, collapsing bubbles (injection) to be greater than or equal to the flux from larger bubbles (exchange), with mean estimates of the ratio in the range of 1–2. We also show that monthly observations of temperature and inert gases cannot constrain the rate …

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Generalized Inversion Of The Gent-Cane Model Of The Tropical Pacific With Tropical Atmosphere-Ocean (Tao) Data, A. F. Bennett, B. S. Chua, H. E. Ngodock, D. E. Harrison, M. J. Mcphaden Jan 2006

Generalized Inversion Of The Gent-Cane Model Of The Tropical Pacific With Tropical Atmosphere-Ocean (Tao) Data, A. F. Bennett, B. S. Chua, H. E. Ngodock, D. E. Harrison, M. J. Mcphaden

Journal of Marine Research

We here describe the results of our latest effort to reanalyze TAO monthly mean surface and subsurface temperature observations constrained by a tropical Pacific ocean model, and simultaneously to evaluate the physical consistency of the observations and the model. Both tasks are executed by weak–constraint, four–dimensional variational assimilation of the observations into the model. In this study our reanalysis employs the reduced–gravity Gent–Cane model, combined with the 'KPP–interior' parameterization of vertical turbulent fluxes. With the limited vertical resolution adopted in previous studies of this model, the 'W4DVAR' or inverse method fails to produce an acceptable reanalysis, as the dynamical residuals …

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Physical-Biological Interactions And Their Effect On Phytoplankton Blooms In Fjords And Near-Coastal Waters, Lars Erik Holmedal, Torbjørn Utnes Jan 2006

Physical-Biological Interactions And Their Effect On Phytoplankton Blooms In Fjords And Near-Coastal Waters, Lars Erik Holmedal, Torbjørn Utnes

Journal of Marine Research

A one-dimensional flow model which accounts for turbulence and stratification in the upper ocean has been applied in conjunction with a one-dimensional production-advection-diffusion model to predict the initial evolution of the phytoplankton biomass concentration under given biological and physical conditions. Here the stratification is caused by the salinity which is modeled by a one-dimensional diffusion equation; the density is related to the salinity by a linear relation (state equation). The resulting one-dimensional model has been applied to investigate how local physical conditions affect the initiation of phytoplankton blooms in nutrition rich waters characterized by wind driven currents and salinity stratification. …

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On The Mechanism Of Centennial Thermohaline Oscillations, Florian Sévellec, Thierry Huck, Mahdi Ben Jelloul Jan 2006

On The Mechanism Of Centennial Thermohaline Oscillations, Florian Sévellec, Thierry Huck, Mahdi Ben Jelloul

Journal of Marine Research

Centennial oscillations of the ocean thermohaline circulation are studied in a 2-D latitude-depth model under mixed boundary conditions (i.e. restoring surface temperature and prescribed freshwater flux). The oscillations are revealed through linear stability analysis of a steady state obtained in a single hemisphere configuration. A density variance budget is performed and helps determine the physical processes sustaining these oscillations: the restoring surface temperature appears as a source of density variance – this is a consequence of positively-correlated temperature and salinity anomalies. A minimal model, the Howard-Malkus loop oscillator, enables us to understand physically the oscillatory and growth mechanisms. The centennial …

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Analysis Of Instabilities And Mesoscale Motion In A Terrain-Following Coordinate Ocean Model, Ingerid Fossum, Lars Petter Røed Jan 2006

Analysis Of Instabilities And Mesoscale Motion In A Terrain-Following Coordinate Ocean Model, Ingerid Fossum, Lars Petter Røed

Journal of Marine Research

We perform a combined potential vorticity analysis and energy analysis to analyze instabilities and mesoscale motion in a continuously stratified, terrain-following coordinate ocean model. Care is exercised to ensure that the potential vorticity is conserved along isopycnals in the absence of sources and sinks. We also derive expressions for the energy components and the associated conversion terms suitable for a terrain-following coordinate ocean model. To demonstrate the usefulness of the new combined analysis tool for detection of instabilities, we analyze results from a numerical model experiment in which the ocean model is contained in a long, rectangular channel closed at …

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Tidal Fronts And Their Role In Air-Sea Gas Exchange, B. Baschek, D. M. Farmer, C. Garrett Jan 2006

Tidal Fronts And Their Role In Air-Sea Gas Exchange, B. Baschek, D. M. Farmer, C. Garrett

Journal of Marine Research

Tidal fronts are a common feature of many coastal environments. They are characterized by a surface convergence zone that enhances wave breaking and the generation of gas bubbles due to wave-current interaction. The associated downwelling currents carry bubbles to depths of up to 160 m and increase the amount of air that dissolves from them.An energetic tidal front is formed at the entrance to the Strait of Georgia, BC, Canada, by a hydraulically controlled sill flow with vertical velocities of up to 0.75 m s−1. Extensive ship-board measurements during two cruises are interpreted with models of wave-current interaction …

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A Model Of Methane Concentration Profiles In The Open Ocean, G. C. Nihous, S. M. Masutani Jan 2006

A Model Of Methane Concentration Profiles In The Open Ocean, G. C. Nihous, S. M. Masutani

Journal of Marine Research

Methane-bearing particulate matter formed in the upper ocean layer is allowed to settle and degrade, releasing methane into the water column as a source in one-dimensional advection-diffusion equations. Predicted carbon and methane particulate fluxes are in good agreement with sediment trap data, using parameters of expected magnitude and particulate methane production well within the mixed layer. This suggests a rapid pathway to the atmosphere and reduced effects on methane concentrations below. Vertical advection rates yielding a good fit between methane concentration calculations and data are larger than expected unless methane oxidation is included. This confirms the significance of methane oxidation …

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Bio-Irrigation In Permeable Sediments: An Assessment Of Model Complexity, Filip J. R. Meysman, Oleksiy S. Galaktionov, Britta Gribsholt, Jack J. Middelburg Jan 2006

Bio-Irrigation In Permeable Sediments: An Assessment Of Model Complexity, Filip J. R. Meysman, Oleksiy S. Galaktionov, Britta Gribsholt, Jack J. Middelburg

Journal of Marine Research

Burrowing benthic animals ventilate their burrow networks, and this enhances the transport of solutes in the sediment and exchange with the overlying water column, a process referred to as bio-irrigation. Various models have been proposed to model bio-irrigation, with different levels of sophistication related to model dimensionality and parameter numbers. Here we address the issue of model complexity for bio-irrigation in permeable sediments. To this end, we simulated flowline patterns and tracer signals using (1) a full 3D model that explicitly models the J-shaped geometry of the burrow in a suitable microenvironment surrounding the burrow, (2) a simplified 2D axisymmetric …

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Sandström’S Experiments Revisited, Melissa A. Coman, Ross W. Griffiths, Graham O. Hughes Jan 2006

Sandström’S Experiments Revisited, Melissa A. Coman, Ross W. Griffiths, Graham O. Hughes

Journal of Marine Research

Sandström's (1908, 1916) pioneering experiments led to the conclusion, later referred to as Sandström's 'theorem', that differential heating and cooling cannot drive a sustained circulation when the source of heating is at or above the level of the cooling source. This principle is incorrect on theoretical grounds and is contradicted by modern laboratory results for the particular case of differential heating and cooling along a single horizontal boundary of a box. However, the 'theorem' has remained common currency. In order to explain the contradiction and explore the fundamentally important concepts involved, we re-create the original experiments of a century ago. …

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Estimating Subsurface Horizontal And Vertical Velocities From Sea-Surface Temperature, J. H. Lacasce, A. Mahadevan Jan 2006

Estimating Subsurface Horizontal And Vertical Velocities From Sea-Surface Temperature, J. H. Lacasce, A. Mahadevan

Journal of Marine Research

We examine a dynamical method for estimating subsurface fields (density, pressure, horizontal and vertical velocities) in the upper ocean using sea-surface temperature (SST) and a climatological estimate of the stratification. The method derives from the "surface quasi-geostrophic" (SQG) approximation. The SST is used to generate a potential vorticity (PV) field which is then inverted for the pressure. We examine first the standard SQG model, in which the PV is assumed trapped in a delta-function layer at the surface. We then modify the model by introducing a subsurface PV which is proportional to the surface density and decays exponentially with depth. …

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Accounting For Unresolved Spatial Variability In Marine Ecosystems Using Time Lags, Philip J. Walhead, Adrian P. Martin, Meric A. Srokosz, Mike J. R. Fasham Jan 2006

Accounting For Unresolved Spatial Variability In Marine Ecosystems Using Time Lags, Philip J. Walhead, Adrian P. Martin, Meric A. Srokosz, Mike J. R. Fasham

Journal of Marine Research

The formulation and calibration of models is a vital method for probing and predicting the behavior of marine ecosystems. The ability to do this may suffer, however, if the calibrating data set is subject to significant spatial variability between samples that is not resolved in the model. We propose that some of this variability might be accounted for by variable time lags between sampled water masses which are otherwise assumed to follow a common pattern of ecosystem variability (dynamical trajectory). Using twin tests of fitting models to simulated data sets, we show that realistic levels of meso/sub-mesoscale variability in time …

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Linking Arenicola Marina Irrigation Behavior To Oxygen Transport And Dynamics In Sandy Sediments, Karen Timmermann, Gary T. Banta, Ronnie N. Glud Jan 2006

Linking Arenicola Marina Irrigation Behavior To Oxygen Transport And Dynamics In Sandy Sediments, Karen Timmermann, Gary T. Banta, Ronnie N. Glud

Journal of Marine Research

In this study we examine how the irrigation behavior of the common lugworm Arenicola marina affects the distribution, transport and dynamics of oxygen in sediments using microelectrodes, planar optodes and diagenetic modeling. The irrigation pattern was characterized by a regular recurring periods of active irrigation lasting approximately 15 min separated by a 15 min rest period. The mean pumping rate during irrigation was 52 ml h−1. Oxygen dynamics and distribution around the tail shaft was closely related to irrigation pattern but independent of pumping rate. During irrigation the oxygen concentration in the burrow was high (>80% air …

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Effect Of Pyridostigmine On Heart Rate Recovery After Exercise In Trained Athletes And Sedentary Adults, Thomas Andrew Dewland Jan 2006

Effect Of Pyridostigmine On Heart Rate Recovery After Exercise In Trained Athletes And Sedentary Adults, Thomas Andrew Dewland

Yale Medicine Thesis Digital Library

Acetylcholinesterase inhibition with pyridostigmine has been previously studied in patients with congestive heart failure (CHF), but the effects of this medication on heart rate recovery after exercise and other indices of parasympathetic activity in populations with greater baseline vagal tone has not been fully characterized. Ten healthy, sedentary adults and ten aerobically trained athletes were enrolled in a prospective, double blind, randomized placebo controlled crossover trial. All study subjects were treated with a single dose of oral pyridostigmine 30 mg and matching placebo on separate days. Heart rate variability (HRV) at rest and heart rate recovery (HRR) at one minute …

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Ethnic Differences In Intramyocellular Lipid Levels And Insulin Resistance In Obese Children And Adolescents, David Liska Jan 2006

Ethnic Differences In Intramyocellular Lipid Levels And Insulin Resistance In Obese Children And Adolescents, David Liska

Yale Medicine Thesis Digital Library

The prevalence of insulin resistance and type 2 diabetes mellitus (T2DM) in obese children and adolescents is growing at an alarming rate, especially in ethnic minorities. It is not clear whether young people of different ethnic backgrounds vary in their metabolic response to excessive adiposity. Differences in lipid partitioning in the abdominal fat compartments have been observed among different ethnic groups. The aim of this study was to evaluate whether there are ethnic differences in intramyocellular lipid (IMCL) levels that are related to differences in insulin sensitivity. Eighty-two obese children and adolescents underwent 1) 1H nuclear magnetic resonance (NMR) spectroscopy …

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The Ventilatory Response To Normoxic Hypercapnia In Male Pet-1 Knockout Mice And The Influence Of Female Sex Hormones, Simon Roderick Best Jan 2006

The Ventilatory Response To Normoxic Hypercapnia In Male Pet-1 Knockout Mice And The Influence Of Female Sex Hormones, Simon Roderick Best

Yale Medicine Thesis Digital Library

No abstract provided.

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The 90-Day Dtf Interest Rate: Why Does It Remain Constant?, Peter Rowland Jan 2006

The 90-Day Dtf Interest Rate: Why Does It Remain Constant?, Peter Rowland

Documents

No abstract provided.

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Corrigendum To Diffusivity And Viscosity Dependence In The Linear Thermocline (J. Mar. Res., 62, 743–769), J. H. Lacasce Jan 2006

Corrigendum To Diffusivity And Viscosity Dependence In The Linear Thermocline (J. Mar. Res., 62, 743–769), J. H. Lacasce

Journal of Marine Research

The statement in LaCasce (2004) that the amplitude, A, of the western boundary layer solution (Eq. 25 in the article) is determined by matching at the northern wall to the streamfunction from the northern boundary inner layer solution, ϕin, is incorrect. The correct procedure is to match to the full boundary layer solution at the northern wall, with contributions from both the inner and outer layers. Doing this ensures that the full transport in the northern layer is fed into the western layer...

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Tidal Energy In The Bering Sea, M. G. G. Foreman, P. F. Cummins, J. Y. Cherniawsky, Phyllis Stabeno Jan 2006

Tidal Energy In The Bering Sea, M. G. G. Foreman, P. F. Cummins, J. Y. Cherniawsky, Phyllis Stabeno

Journal of Marine Research

Tidal harmonics computed from TOPEX/POSEIDON altimetry are assimilated into a barotropic, finite element model of the Bering Sea whose accuracy is evaluated though comparisons with independent bottom pressure gauges. The model is used to estimate energy fluxes through each of the Aleutian Passes and Bering Strait and to construct an energy budget for the major tidal constituents. The finite element model does not conserve mass locally and this is shown to give rise to an additional term in the energy budget whose contribution is significant for the prior model, but which is reduced substantially with the assimilation technique. Though the …

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Estimation Of Nonlocal Turbulent Mixing Parameters Derived From Microstructure Profiles, Jaume Piera, Ruben Quesada, Jordi Catalan Jan 2006

Estimation Of Nonlocal Turbulent Mixing Parameters Derived From Microstructure Profiles, Jaume Piera, Ruben Quesada, Jordi Catalan

Journal of Marine Research

The present study proposes a new method for estimating nonlocal mixing parameters from microstructure data processing. The method could be particularly useful in studies of biological-physical interactions at small scale because it overcomes some of the limitations of the eddy diffusivity concept when dealing with the complex vertical pattern of biological and chemical tracers. The proposed method obtains empirically the coefficients of the transilient matrix, this being the discrete descriptor used in nonlocal mixing closure. The estimation is based on microstructure data analysis, in particular Thorpe displacement profiles, and includes three main steps: turbulent patch identification within each profile, turbulent …

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Quantifying Seasonal Air-Sea Gas Exchange Processes Using Noble Gas Time-Series: A Design Experiment, Rachel H. R. Stanley, William J. Jenkins, Scott C. Doney Jan 2006

Quantifying Seasonal Air-Sea Gas Exchange Processes Using Noble Gas Time-Series: A Design Experiment, Rachel H. R. Stanley, William J. Jenkins, Scott C. Doney

Journal of Marine Research

A multi-year time-series of measurements of five noble gases (He, Ne, Ar, Kr, and Xe) at a subtropical ocean location may allow quantification of air-sea gas exchange parameters with tighter constraints than is currently available by other methods. We have demonstrated this using a one-dimensional upper ocean model forced by 6-hourly NCEP reanalysis winds and heat flux for the Sargasso Sea near Bermuda. We performed ensemble model runs to characterize the response of the modeled noble gas saturation anomalies to a range of air-sea gas exchange parameters. We then used inverse calculations to quantify the sensitivity of the parameters to …

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