The application of various chromatographic technique to the mixed esters prepared from shellac has led to the discovery of ether-linked polymer fragments in shellac and the isolation and identification of a number of hitherto unrecognised aliphatic acids including saturated and unsaturated non-hydroxy acids, 6-keto-tetr'adecanoic acid, 6-hydroxytetradecanoic acid, 10-hydroxyhexadec-9-enoic acid, 16-hydroxyhexadecanoic acid, threo 9,10-dihydroxytetradecanoic acid. Appendix Lipolytic Studies of some Seed Oils containing Sterculic Acid. The sterculic acid containing seed oils, Eombacopsis glabra, Sterculia parviflora and Sterculia macrophylla, were examined and subjected to hydrolysis with pancreatic lipase.

Isolated and identified crab axons have been used to study the forms of the repetitive responses to direct current. Using techniques which enable the responses of isolated axons to be studied at the site of imposed electrical currents, the responses can be classified into five major groups with two subdivisions:- Group 1. Axons showing no marked supernormality during the recovery cycle, that repeat over a wide range of frequencies when stimulated by direct current, with frequency increasing smoothly with the strength of applied current, Group ia. To direct current these axons yield a train of impulses, the intervals between which progressively lengthen. Group ib. To direct current these axons yield a train of impulses the Intervals between which, for some time at least, progressively shorten. Group ll. Axons showing a pronounced supemomality during the recovery cycle, that repeat over only a limited frequency range. Group lla. Axons capable of long latencies, with oscillatory subthreshold potentials before and after the repetitive response. Group llb. Axons showing only short latencies, and lacking subthreshold oscillations before the repetitive response, but nevertheless with oscillations following the response. Group lll. Axons with a prolonged long-lived supemormality during the recovery cycle, which can be correlated with a prolonged action potential. They can repeat over a wide range of frequencies stimulated by direct current, but lack true local potentials for all action potentials except the first. Group lV. Axons with a relatively prolonged subnormality during the recovery cycle. They show short trains of action potentials, the amplitude of which progressively decreases even to near threshold currents, and the interspike intervals show a smooth increase. Group V. Axons unable to repeat to direct current, having a low safety factor and high threshold. They are capable of only short latencies. The single action potential shows a considerable variation in amplitude. A wide varied of experiments have been carried out, which have shown that several factors influence the form of the repetitive response in crab axons, and that the inadequacy of previous theories stems from their oversimplification. The factors show to operate in determining the form of these responses are:- 1. Changes in the resistance of the axon membrane, so that a constant current pulse will not cause the sane potential displacement while it acts. These changes can occur as the result of ionic accumulation outside the axon, or from the active process of delayed rectification. 2. The duration and from of the recovery cycle limits the upper frequency of the repetitive response, as well as influencing it at other times. 3. Sustained depolarisation depresses excitability, by lengthening the repolarisation time of an action potential and the period of recovery following it, as can be seen when the threshold potential for the spike rises throughout a repetitive response. 4. Changes in the membrane potential that result from the accumulation of ions in the near vicinity of the axon membrane. These changes, although they show some interdependence, are often difficult to completely eliminate any particular one by experiment. Although these factors have not been measured quantitatively, on account of technical difficulties inherent in the use of crab axons, they are sufficient to provide a coherent interpretation of repetition.

Dormancy in many aquatic angiosperms is characterized by the production of turions, specialized vegetative buds which function as both propagules and perennating organs. In temperate climate species, induction of dormancy is usually associated with short days, often in conjunction with low temperatures. By contrast, the turions of Potamogeton crispus are formed around midsummer and the species grows luxuriantly throughout the winter. The environmental factors controlling turion formation in Potamogeton crispus were investigated under natural and laboratory conditions. Potamogeton obtusifolius, a typical temperate climate species exhibiting autumnal turion production, was studied for comparative purposes. Phenological development of natural populations in two Scottish lakes was compared with seasonal measurements of temperature, daylength, underwater light attenuation and light quality (the red and far red wavelength bands). Temperature and photoperiod were identified as the primary environmental factors regulating turion formation in both species. Laboratory experiments confirmed the field observation that turions are produced by Potamogeton crispus in response to long days (greater than 12 to 16h) and high temperatures (greater than 16°C). In Potamogeton obtusifolius, turion production is associated with short days and high temperatures. Because of the complexity of the underwater light climate, the effect of light quantity (irradiance) and light quality on turion production could not be determined. Laboratory experiments showed that under inductive photoperiodic and temperature conditions, low red:far red ratios and low irradiance inhibited turion formation in Potamogeton crispus. The action of phytochrome in the perception of the long day photoperiodic signal and the quantitative effect of sucrose concentration on the magnitude of turion production in Potamogeton crispus was investigated. A model of phytochrome action in the control of photoperiodic and photomorphogenetic responses in aquatic angiosperms is presented and the role of turions in the life history of Potamogeton crispus and Potamogeton obtusifolius is assessed.

No description available.

To aid climate policy decisions, accurate quantitative descriptions of the uncertainty in climate outcomes under various possible policies are needed. Here, we apply an earth systems model to describe the uncertainty in climate projections under two different policy scenarios. This study illustrates an internally consistent uncertainty analysis of one climate assessment modeling framework, propagating uncertainties in both economic and climate components, and constraining climate parameter uncertainties based on observation. We find that in the absence of greenhouse gas emissions restrictions, there is a one in forty chance that global mean surface temperature change will exceed 4.9 degrees C by the year 2100. A policy case with aggressive emissions reductions over time lowers the temperature change to a one in forty chance of exceeding 3.2 degrees C, thus reducing but not eliminating the chance of substantial warming. / Abstract in HTML and technical report in PDF available on the Massachusetts Institute of Technology Joint Program on the Science and Policy of Global Change Website. (http://mit.edu/globalchange/www/) / Includes bibliographical references (p. 19-21).

The experiment reported here tests the case of so-called exclusionary manipulation of emission permit markets, i.e., when a dominant firm -- here a monopolist -- increases its holding of permits in order to raise its rivals' costs and thereby gain more on a product market. Earlier studies have claimed that this type of market manipulation is likely to substantially reduce the social gains of permit trading and even result in negative gains. The experiment designed here parallels institutional and informat ional conditions likely to hold in real trade with carbon permits among electricity producers. Although the dominant firm withheld supply from the electricity market, the outcome seems to reject the theory of exclusionary manipulation. In later trading p eriods, closing prices on both markets, permit holdings and total electricity production are near competitive levels. Social gains of emissions trading are higher than in earlier studies. / Abstract in HTML and technical report in PDF available on the Massachusetts Institute of Technology Joint Program on the Science and Policy of Global Change Website. (http://mit.edu/globalchange/www/) / Includes bibliographical references (p. 18-19).

The effects of air pollution on vegetation may provide an important control on the carbon cycle that has not yet been widely considered. Prolonged exposure to high levels of ozone, in particular, has been observed to inhibit photosynthesis by direct cellu lar damage within the leaves and through changes in stomatal conductance. We have incorporated empirical equations derived for trees (hardwoods and pines) and crops into the Terrestrial Ecosystem Model version 4.3 (TEM 4.3) to explore the effects of ozon e on net primary production and carbon sequestration across the conterminous United States. Our results show up to a 5% reduction in Net Primary Production (NPP) in response to modeled historical ozone levels during the late 1980s to early 1990s. The lar ge st decreases (over 20% in some locations) occur in the eastern U.S. and Midwest, during months with high ozone levels and high productivity. Carbon sequestration during the 1980s is reduced by 30 to 70 Tg C/yr with the presence of ozone, or 5 to 23% o f recent estimates of the total carbon sequestration for the U.S. Thus the effects of ozone on NPP and carbon sequestration should be factored into future calculations of the U.S. carbon budget. / Abstract in HTML and technical report in PDF available on the Massachusetts Institute of Technology Joint Program on the Science and Policy of Global Change Website. (http://mit.edu/globalchange/www/) / Includes bibliographical references (p. 20-21)

This paper uses bottom-up engineering information as a basis for modeling new technologies within the MIT Emissions Prediction and Policy Analysis (EPPA) model, a computable general equilibrium model of the world economy. Natural gas combined cycle (NGCC) without carbon capture and sequestration (CCS), natural gas combined cycle with CCS, and integrated coal gasification with CCS power generation technologies are introduced into the EPPA model. These compete in the electricity sector with conventional fos sil generation, nuclear, hydro, wind, and biomass power generation. Engineering cost data are used together with EPPA data, including the underlying Social Accounting Matrix (SAM) and supplementary physical energy accounts, to assure that technologies, w h en simulated within the model, meet thermodynamic efficiency limits, and that they reflect regional differences in the cost structure of the electric sector. Alternative capital vintaging approaches are investigated and an explicit treatment of market p enetration of new technologies is developed. Simulations through 2100 show the introduction of the new technologies and their decline as fuel and input prices, and carbon policies, change. A general result is that NGCC plants with or without capture, wh il e currently less costly methods of abating carbon emissions from the electric sector based on engineering data, play only a limited and short-term role in meeting carbon limits. By 2050 the coal CCS plants, currently the most costly of the three techno logies, dominate in the simulated policy scenarios because rising gas prices raise the cost of the gas-based technologies. / Abstract in HTML and technical report in PDF available on the Massachusetts Institute of Technology Joint Program on the Science and Policy of Global Change Website. (http://mit.edu/globalchange/www/) / Includes bibliographical references (p. 22).

The deep-ocean heat uptake (DOHU) in transient climate changes is studied using an ocean general circulation model (OGCM) and its adjoint. The model configuration consists of idealized Pacific and Atlantic basins. The model is forced with the anomalies of surface heat and freshwater fluxes from a global warming scenario with a coupled model using the same ocean configuration. In the scenario CO₂ concentration increases 1% per year. The heat uptake calculated from the coupled model and from the adjoint are virtually identical, showing that the heat uptake by the OGCM is a linear process. After 70 years the ocean heat uptake is almost evenly distributed within the layers above 200 m, between 200 and 700 m, and below 700 m (about 20 x 10^22 J in each). The effect of anomalous surface fresh water flux on the DOHU is negligible. Analysis of CMIP-2 data for the same global warming scenario shows that qualitatively similar results apply to coupled atmosphere-ocean GCMs. The penetration of surface heat flux to the deep ocean in our OGCM occurs mainly in the North Atlantic and the Southern Ocean, since both the sensitivity of DOHU to the surface heat flux and the magnitude of anomalous surface heat flux are large in these two regions. The DOHU relies on the reduction of convection and Gent-McWilliams mixing in the North Atlantic, and the reduction of Gent-McWilliams mixing in the Southern Ocean. / Abstract in HTML and technical report in PDF available on the Massachusetts Institute of Technology Joint Program on the Science and Policy of Global Change Website. (http://mit.edu/globalchange/www/) / Includes bibliographical references (p. 20-23).

Sensitivities of the net heat flux into the deep-ocean (Qnet) and of the deep-ocean heat content (DOC) below 700 m are studied using an ocean general circulation model and its adjoint. Both are found to have very similar sensitivities. The sensitivity to the surface freshwater flux (E-P-R) is positive in the Atlantic, but negative in the Pacific and Southern Ocean. A positive sensitivity to the downward net surface heat flux is found only in the North Atlantic north of 40 degrees N and the Southern Ocean. The diapycnal diffusivity of temperature affects Qnet and DOC positively in a large area of the tropics and subtropics in both the Pacific and Atlantic Ocean. The isopycnal diffusivity contributes to Qnet and DOC mainly in the Southern Ocean. Detailed analysis indicates that the surface freshwater flux affects Qnet and DOC by changing vertical velocity, temperature stratification, and overturning circulation. The downward net surface heat flux appears to increase Qnet and DOC by strengthening vertical advection and isopycnal mixing. The contribution of isopycnal diffusivity to Qnet and DOC is largely associated with the vertical heat flux due to isopycnal mixing. Similarly, the diapycnal diffusivity of temperature modulates Qnet and DOC through the downward heat flux due to diapycnal diffusion. The uncertainties of Qnet and DOC are estimated based on the sensitivities and error bars of observed surface forcing and oceanic diffusivities. For DOC, they are about 0.7 degrees K (1 degree K = 3 x 10^24 J) for the isopycnal diffusiv ity, 0.4 degrees K for the diapycnal diffusivity of temperature, 0.3 degrees K for the surface freshwater flux, and 0.1 degrees K for the net surface heat flux and zonal wind stress. Our results suggest that the heat uptake by ocean GCMs in climate experiments is sensitive to the isopycnal diffusivity as well to the diapycnal thermal diffusivity. / Abstract in HTML and technical report in PDF available on the Massachusetts Institute of Technology Joint Program on the Science and Policy of Global Change Website. (http://mit.edu/globalchange/www/) / Includes bibliographical references (p. 25-30).