Investigating Light Curve Modulation via Kernel Smoothing. I. Application to 53 fundamental mode and first-overtone Cepheids in the LMC

Recent studies have revealed a hitherto unknown complexity of Cepheid pulsation. We implement local kernel regression to search for both period and amplitude modulations simultaneously in continuous time and to investigate their detectability, and test this new method on 53 classical Cepheids from the OGLE-III catalog. We determine confidence intervals using parametric and non-parametric bootstrap sampling to estimate significance and investigate multi-periodicity using a modified pre-whitening approach that relies on time-dependent light curve parameters. We find a wide variety of period and amplitude modulations and confirm that first overtone pulsators are less stable than fundamental mode Cepheids. Significant temporal variations in period are more frequently detected than those in amplitude. We find a range of modulation intensities, suggesting that both amplitude and period modulations are ubiquitous among Cepheids. Over the 12-year baseline offered by OGLE-III, we find that period changes are often non-linear, sometimes cyclic, suggesting physical origins beyond secular evolution. Our method more efficiently detects modulations (period and amplitude) than conventional methods reliant on pre-whitening with constant light curve parameters and more accurately pre-whitens time series, removing spurious secondary peaks effectively.Comment: Re-submitted including revisions to Astronomy and Astrophysic

TIPS for social security?

Social security

Retail deposit sweep programs: issues for measurement, modeling and analysis

Since January 1994, many banks in the United States have initiated retail-deposit sweep programs which reduce statutory reserve requirements by re-labeling transaction deposits as money market deposit accounts. As a result, approximately half of aggregate transaction deposits are now excluded from M1. This re-labeling is invisible to customers and, hence, cannot affect their demand for transaction balances. Nevertheless, a recent article in this Journal explored the effect of this invisible re-labeling on M1 demand. This note emphasizes that those results are spurious, and offers additional examples of measurement distortions due to retail deposit sweep activity.Bank reserves ; Money supply

Meeting the Y2K demand for base money

Year 2000 date conversion (Computer systems)

The first U.S. quantitative easing: the 1930s

During 1932, with congressional support, the Fed purchased approximately $1 billion in Treasury securities.Monetary policy ; Financial crises

The effect of mortgage refinancing on money demand and the monetary aggregates

Money supply ; Mortgages

Monetary policy's third interest rate

Interest rates

Editor's introduction

Economic development ; Economic conditions