Re-Assessing the U.S. Quality Adjustment to Computer Prices: The Role of Durability and Changing Software

In the second-half of the 1990s, the positive impact of information technology on productivity growth for the United States became apparent. The measurement of this productivity improvement depends on hedonic procedures adopted by the Bureau of Labor Statistics (BLS) and Bureau of Economic Analysis (BEA). In this paper we suggest a new reason why conventional hedonic methods may overstate the price decline of personal computers. We model computers as a durable good and suppose that software changes over time, which influences the efficiency of a computer. Anticipating future increases in software, purchasers may "overbuy" characteristics, in the sense that the purchased bundle of characteristics is not fully utilized in the first months or year that a computer is owned. In this case, we argue that hedonic procedures do not provide valid bounds on the true price of computer services at the time the machine is purchased with the concurrent level of software. To assess these theoretical results we estimate the model and find that before 2000 the hedonic price index constructed with BLS methods overstates the fall in computer prices. After 2000, however, the BLS hedonic index falls more slowly, reflecting the reduced marginal cost of acquiring (and therefore marginal benefit to users) of characteristics such as RAM, hard disk space or speed.

Some Inconvenient Truths About Climate Change Policy: The Distributional Impacts of Transportation Policies

Instead of efficiently pricing greenhouse gases, policy makers have favored measures that implicitly or explicitly subsidize low carbon fuels. We simulate a transportation-sector cap & trade program (CAT) and three policies currently in use: ethanol subsidies, a renewable fuel standard (RFS), and a low carbon fuel standard (LCFS). Our simulations confirm that the alternatives to CAT are quite costly—2.5 to 4 times more expensive. We provide evidence that the persistence of these alternatives in spite of their higher costs lies in the political economy of carbon policy. The alternatives to CAT exhibit a feature that make them amenable to adoption|a right skewed distribution of gains and losses where many counties have small losses, but a smaller share of counties gain considerably—as much as $6,800 per capita, per year. We correlate our estimates of gains from CAT and the RFS with Congressional voting on the Waxman-Markey cap & trade bill, H.R. 2454. Because Waxman-Markey (WM) would weaken the RFS, House members likely viewed the two policies as competitors. Conditional on a district's CAT gains, increases in a district's RFS gains are associated with decreases in the likelihood of voting for WM. Furthermore, we show that campaign contributions are correlated with a district's gains under each policy and that these contributions are correlated with a Member's vote on WM.Institute of Transportation Studies at UC Davi

Some Inconvenient Truths About Climate Change Policy: The Distributional Impacts of Transportation Policies

Instead of efficiently pricing greenhouse gases, policy makers have favored measures that implicitly or explicitly subsidize low carbon fuels. We simulate a transportation-sector cap & trade program (CAT) and three policies currently in use: ethanol subsidies, a renewable fuel standard (RFS), and a low carbon fuel standard (LCFS). Our simulations confirm that the alternatives to CAT are quite costly–2.5 to 4 times more expensive. We provide evidence that the persistence of these alternatives in spite of their higher costs lies in the political economy of carbon policy. The alternatives to CAT exhibit a feature that make them amenable to adoption–a right skewed distribution of gains and losses where many counties have small losses, but a smaller share of counties gain considerably–as much as $6,800 per capita, per year. We correlate our estimates of gains from CAT and the RFS with Congressional voting on the Waxman-Markey cap & trade bill, H.R. 2454. Because Waxman-Markey (WM) would weaken the RFS, House members likely viewed the two policies as competitors. Conditional on a district's CAT gains, increases in a district's RFS gains are associated with decreases in the likelihood of voting for WM. Furthermore, we show that campaign contributions are correlated with a district's gains under each policy and that these contributions are correlated with a Member's vote on WM.

Stabilität von Herzglykosiden in wässrigen bzw. wässrig fermentierten Extrakten aus der Meerzwiebel (Drimia maritima (L.) Stearn)

In der vorliegenden Studie wurden ein rein wässriger Extrakt und ein wässrig fermentierter Extrakt, hergestellt nach dem Homöopathischem Arzneibuch (HAB), aus der Meerzwiebel (Drimia maritima (L.) Stearn) bei unterschiedlichen Temperatur- und Lichtbedingungen gelagert. In regelmäßigen Abständen wurde die Stabilität der Herzglykoside in diesen Extrakten mittels HPLC-DAD-MSn bewertet. Die geringsten Abbauraten der Einzelkomponenten wurden bei einer Lagerung im Dunkeln bei 5 °C ermittelt. Schon eine Temperaturerhöhung auf 20 °C beschleunigte den Abbau bzw. die Metabolisierung der Bufadienolide. Die geringste Stabilität wurde unter Belichtung bei 20 °C ermittelt. Außerdem war ein deutlicher Unterschied zwischen den auf unterschiedliche Weisen gewonnenen Extrakten beobachtbar. So wiesen die Herzglykoside im Extrakt, der nach HAB hergestellt wurde, eine deutliche höhere Stabilität unter allen Lagerbedingungen auf. Stichwörter: Meerzwiebel, Herzglykoside, Stabilität, Belichtung, Pflanzenextrakt, Drimia maritima (L.) Stearn Stability of cardiac glycosides in aqueous and fermented aqueous extracts from sea squill (Drimia maritima L. Stearn)In the present study an aqueous and a fermented aqueous extract, obtained according to the German Homoeopathic Pharmacopoeia (GHP), from sea squill (Drimia maritima (L.) Stearn) were stored under different light and temperature conditions. Stability of cardiac glycosides in these extracts was evaluated periodically by HPLC-DAD-MS. Lowest degradation rates of individual compounds were observed upon storage at 5 °C in the dark. Increasing the temperature at 20 °C accelerated compound degradation and the formation of bufadienolide metabolites. Poorest stability was found upon storage at 20 °C with light exposure. Furthermore, clear-cut differences were observed between the extracts obtained according to different protocols. Stability of cardiac glycosides in the extract obtained according to the GHP was generally improved, irrespective of the storage conditions. Keywords: sea squill, cardiac glycosides, stability, light exposure, plant extract, Drimia maritima (L.) Stear

Biological measurement beyond the quantum limit

Quantum noise places a fundamental limit on the per photon sensitivity attainable in optical measurements. This limit is of particular importance in biological measurements, where the optical power must be constrained to avoid damage to the specimen. By using non-classically correlated light, we demonstrated that the quantum limit can be surpassed in biological measurements. Quantum enhanced microrheology was performed within yeast cells by tracking naturally occurring lipid granules with sensitivity 2.4 dB beyond the quantum noise limit. The viscoelastic properties of the cytoplasm could thereby be determined with a 64% improved measurement rate. This demonstration paves the way to apply quantum resources broadly in a biological context