Nitric oxide synthase:non-canonical expression patterns

Science can move ahead by questioning established or canonical views and, so it may be with the enzymes, nitric oxide synthases (NOS). Nitric oxide (NO) is generated by NOS isoforms that are often described by their tissue-specific expression patterns. NOS1 (nNOS) is abundant in neural tissue, NOS2 is upregulated in activated macrophages and known as inducible NOS (iNOS), and NOS3 (eNOS) is abundant in endothelium where it regulates vascular tone. These isoforms are described as constitutive or inducible, but in this perspective we question the broad application of these labels. Are there instances where “constitutive” NOS (NOS1 and NOS3) are inducibly expressed; conversely, are there instances where NOS2 is constitutively expressed? NOS1 and NOS3 inducibility may be linked to post-translational regulation, making their actual patterns activity much more difficult to detect. Constitutive NOS2 expression has been observed in several tissues, especially the human pulmonary epithelium where it may regulate airway tone. These data suggest that expression of the three NOS enzymes may include non-established patterns. Such information should be useful in designing strategies to modulate these important enzymes in different disease states

Heavy Quark Symmetry Predictions for Weakly Bound B-Meson Molecules

Recently the Belle collaboration discovered two resonances, Zb(10610) and Zb(10650), that lie very close to the B\bar{B}^* and B^*\bar{B}^* thresholds, respectively. It is natural to suppose that these are molecular states of bottom and anti-bottom mesons. Under this assumption, we introduce an effective field theory for the Zb(10610) and Zb(10650), as well as similar unobserved states that are expected on the basis of heavy quark spin symmetry. The molecules are assumed to arise from short-range interactions that respect heavy quark spin symmetry. We use the theory to calculate line shapes in the vicinity of B^{(*)}\bar{B}^{(*)} thresholds as well as two-body decay rates of the new bottom meson bound states. We derive new heavy quark spin symmetry predictions for the parameters appearing in the line shapes as well as the total and partial widths of the states.Comment: 17 pages, 2 figure

Corporate Average Fuel Economy Standards and the Market for New Vehicles

This paper presents an overview of the economics literature on the effect of Corporate Average Fuel Economy (CAFE) standards on the new vehicle market. Since 1978, CAFE has imposed fuel economy standards for cars and light trucks sold in the U.S. market. This paper reviews the history of the standards, followed by a discussion of the major upcoming changes in implementation and stringency. It describes strategies that firms can use to meet the standards and reviews the CAFE literature as it applies to the new vehicle market. The paper concludes by highlighting areas for future research in light of the upcoming changes to CAFE.CAFE, costs, structural estimation

On the instrumental value of hypothetical and counterfactual thought.

People often engage in “offline simulation”, considering what would happen if they performed certain actions in the future, or had performed different actions in the past. Prior research shows that these simulations are biased towards actions a person considers to be good—i.e., likely to pay off. We ask whether, and why, this bias might be adaptive. Through computational experiments we compare five agents who differ only in the way they engage in offline simulation, across a variety of different environment types. Broadly speaking, our experiments reveal that simulating actions one already regards as good does in fact confer an advantage in downstream decision making, although this general pattern interacts with features of the environment in important ways. We contrast this bias with alternatives such as simulating actions whose outcomes are instead uncertain

New vehicle characteristics and the cost of the corporate average fuel economy standard

Recent legislation has increased the Corporate Average Fuel Economy (CAFÉ) standard by 40 percent, which represents the first major increase in the standard since its creation in 1975. Previous analysis of the CAFÉ standard has focused on the short run effects, in which vehicle characteristics are held fixed, or the long run, when firms can adopt new powertrain technology. This paper focuses on the medium run, when firms can choose characteristics such as weight and power, and have a limited ability to adopt engine technology. We first document the historical importance of the medium run and then estimate consumers’ willingness-to-pay for fuel efficiency, power and weight. We employ a unique empirical strategy that accounts for the characteristics’ endogeneity, which has not been addressed in the literature, by using variation in the set of engine models used in vehicle models. The results imply that an increase in power has an equal effect on vehicle sales as a proportional increase in fuel efficiency. We then simulate the medium run effects of an increase in the CAFÉ standard. The policy reduces producer and consumer welfare and causes substantial transfers across firms, but the effects are significantly smaller than in previous studies.Fuel

Private sector responses to public investments and policy reforms: The case of fertilizer and maize market development in Kenya

millions fed, food security, Fertilizer, maize, Liberalization market,

How slowing senescence changes life expectancy

Mortality decline has historically been a result of reductions in the level of mortality at all ages. The slope of mortality increase with age has been remarkably stable. A number of leading researchers on aging, however, suggest that the next revolution of longevity increase will be the result of slowing down the rate of aging, lessening the rate at which mortality increases as we get older. In this paper, we show mathematically how varying the pace of senescence influences life expectancy. We provide a formula that holds for any baseline hazard function. Our result is analogous to Keyfitz's "entropy" relationship for changing the level of mortality. Interestingly, the influence of the shape of the baseline schedule on the effect of senescence changes is the complement of that found for level changes. We also provide a generalized formulation that mixes level and slope effects.

Cohort postponement and period measures

We introduce a new class of models in which demographic behavior such as fertility is postponed by differing amounts depending only on cohort membership. We show how this model fits into a general framework of period and cohort postponement that includes the existing models in the literature, notably those of Bongaarts and Feeney and Kohler and Philipov. The cohort-based model shows the effects of cohort shifts on period fertility measures and provides an accompanying tempo-adjusted measure of period total fertility in the absence of observed shifts. Simulation reveals that when postponement is governed by cohorts, the cohort-based indicator outperforms the Bongaarts and Feeney model that is now in widespread use. The cohort-based model is applied to fertility in several modern populations.

The price of gasoline and the demand for fuel economy: evidence from monthly new vehicles sales data

This paper uses a unique data set of monthly new vehicle sales by detailed model from 1978- 2007, and implements a new identification strategy to estimate the effect of the price of gasoline on consumer demand for fuel economy. We control for unobserved vehicle and consumer characteristics by using within model-year changes in the price of gasoline and vehicle sales. We find a significant demand response, as nearly half of the decline in market share of U.S. manufacturers from 2002-2007 was due to the increase in the price of gasoline. On the other hand, an increase in the gasoline tax would only modestly affect average fuel economy.Gasoline ; Automobiles - Prices