Foreign body responses in central nervous system mimic natural wound responses and alter biomaterial functions

Biomaterials hold promise for diverse therapeutic applications in the central nervous system (CNS). Little is known about molecular factors that determine CNS foreign body responses (FBRs) in vivo , or about how such responses influence biomaterial function. Here, we probed these factors using a platform of injectable hydrogels readily modified to present interfaces with different representative physiochemical properties to host cells. We show that biomaterial FBRs mimic specialized multicellular CNS wound responses not present in peripheral tissues, which serve to isolate damaged neural tissue and restore barrier functions. Moreover, we found that the nature and intensity of CNS FBRs are determined by definable properties. For example, cationic, anionic or nonionic interfaces with CNS cells elicit quantifiably different levels of stromal cell infiltration, inflammation, neural damage and amyloid production. The nature and intensity of FBRs significantly influenced hydrogel resorption and molecular delivery functions. These results characterize specific molecular mechanisms that drive FBRs in the CNS and have important implications for developing effective biomaterials for CNS applications

Temporal Insensitivity of Willingness to Pay: How do they evaluate in CVM?

In addition to scope and scale embedding effects, temporal insensitivity of willingness to pay, also known as temporal embedding effect, has been a well known anomaly in eliciting willingness to pay for environmental quality change, especially over time. Stevens et al. (1997) defines two types of temporal embedding effects: strong insensitivity and weak insensitivity to payment schedule. This paper proposes an alternative definition of the temporal insensitivity. Temporal insensitivity implies that a subject in the survey responds consistently to value elicitation questions regardless of payment schemes. The sequential test tests the temporal insensitivity using the oyster reef restoration programs in Chesapeake Bay. Test results show that willingness to pay for the program is insensitive to the payment scheme or to the length of benefit stream of the project. Discount rates imbedded in cost stream vary significantly among the combination of project lengths and payment schemes.Temporal insensitivity of willingness to pay, Temporal embedding effect, Implicit discount rate, Sequential test, Demand and Price Analysis,

Generalized Estimation Methods for Non-i.i.d. Binary Data: An Application to Dichotomous Choice Contingent Valuation

We challenge the assumption of i.i.d random utility across alternatives embedded in typical applications of logit models to dichotomous choice contingent valuation data. Using a Gumbel mixed distribution which nests a number of traditional models, we show that the logistic distribution is not a suitable distribution for contingent valuation analysis.Research Methods/ Statistical Methods,

REVISITING BID DESIGN ISSUES IN CONTINGENT VALUATION

A uniform bid design from a predetermined uniform distribution is proposed as a practical and robust alternative to existing optimal or naïve bid designs. Analytics and simulations show that the uniform design provides efficiency better than naïve designs under ideal conditions and outperforms optimal designs with poor initial information.Research Methods/ Statistical Methods,

Are Shocks to the Terms of Trade Shocks to Productivity?

International trade is frequently thought of as a production technology in which the inputs are exports and the outputs are imports. Exports are transformed into imports at the rate of the price of exports relative to the price of imports: the reciprocal of the terms of trade. Cast this way, a change in the terms of trade acts as a productivity shock. Or does it? In this paper, we show that this line of reasoning cannot work in standard models. Starting with a simple model and then generalizing, we show that changes in the terms of trade have no first-order effect on productivity when output is measured as chain-weighted real gross domestic product. The terms of trade do affect real income and consumption in a country, and we show how measures of real income change with the terms of trade at business cycle frequencies and during financial crises.

How important is the new goods margin in international trade?

We propose a methodology for studying changes in bilateral trade due to countries exporting goods that they did not export previously or exported only in small quantities. Applying this methodology to country pairs that undergo trade liberalization and to pairs in which one of the countries undergoes significant structural transformation, we find large increases on this extensive—or new goods—margin. Looking at country pairs with no major trade policy change or structural change, however, we find little or no increases on the extensive margin. Studying time series on trade by commodity, we find that data from before 1988 and 1989, when most major trading countries moved to the Harmonized System, are not compatible with data from afterward.International trade ; Free trade

Why have economic reforms in Mexico not generated growth?

Following its opening to trade and foreign investment in the mid-1980s, Mexico’s economic growth has been modest at best, particularly in comparison with that of China. Comparing these countries and reviewing the literature, we conclude that the relation between openness and growth is not a simple one. Using standard trade theory, we find that Mexico has gained from trade, and by some measures, more so than China. We sketch out a theory in which developing countries can grow faster than the United States by reforming. As a country becomes richer, this sort of catch-up becomes more difficult. Absent continuing reforms, Chinese growth is likely to slow down sharply, perhaps leaving China at a level less than Mexico’s real GDP per working-age person.

Sudden stops, sectoral reallocations, and the real exchange rate

A sudden stop of capital flows into a developing country tends to be followed by a rapid switch from trade deficits to surpluses, a depreciation of the real exchange rate, and decreases in output and total factor productivity. Substantial reallocation takes place from the nontraded sector to the traded sector. We construct a multisector growth model, calibrate it to the Mexican economy, and use it to analyze Mexico's 1994?95 crisis. When subjected to a sudden stop, the model accounts for the trade balance reversal and the real exchange rate depreciation, but it cannot account for the decreases in GDP and TFP. Extending the model to include labor frictions and variable capital utilization, we still find that it cannot quantitatively account for the dynamics of output and productivity without losing the ability to account for the movements of other variables.Financial crises