Regional studies: Lake Michigan energy forecasts. The econometric approach to electricity supply and demand: review and analysis

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Price and availability of western coal in the midwestern electric utility market, 1974--1982

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Solar availability for winter space heating: an analysis of the calendar period 1953-1975

Solar availability for space heating has been determined from an analysis of SOLMET data tapes for eight US sites. The tapes contain hourly readings of insolation and ambient temperature for the period 1953-1975. Scatter-diagrams of insolation versus heating degree-days, compiled on a daily basis, indicate a wide variation in insolation levels, even during periods of coldest weather. For seven of the eight sites, the peak-day backup energy required by a solar space heating system exceeded 85% of the peak-day energy requirement of a conventional (nonsolar) heating system

Optimal design of seasonal storage for 100% solar space heating in buildings

An analysis is presented of seasonal solar systems that contain water as the sensible heat storage medium. A concise model is developed under the assumption of a fully mixed, uniform temperature, storage tank that permits efficient simulation of long-term (multi-day) system performance over the course of the year. The approach explicitly neglects the effects of short-term (sub-daily) fluctuations in insolation and load, effects that will be extremely small for seasonal solar systems. This approach is useful for examining the major design tradeoffs of concern here. The application considered is winter space heating. The thermal performance of seasonal solar systems that are designed to supply 100% of load without any backup is solved for, under ''reference year'' monthly normal ground temperature and insolation conditions. Unit break-even costs of seasonal storage are estimated by comparing the capital and fuel costs of conventional heating technologies against those of a seasonal solar system. A rough comparison between the alternatives for more severe winters was made by examining statistical variations in winter season conditions over the past several decades. (MHR

Alternating-Site Mechanism of Kinesin-1 Characterized by Single-Molecule FRET Using Fluorescent ATP Analogues

Kinesin-1 motor proteins move along microtubules in repetitive steps of 8 nm at the expense of ATP. To determine nucleotide dwell times during these processive runs, we used a Förster resonance energy transfer method at the single-molecule level that detects nucleotide binding to kinesin motor heads. We show that the fluorescent ATP analog used produces processive motility with kinetic parameters altered <2.5-fold compared with normal ATP. Using our confocal fluorescence kinesin motility assay, we obtained fluorescence intensity time traces that we then analyzed using autocorrelation techniques, yielding a time resolution of ∼1 ms for the intensity fluctuations due to fluorescent nucleotide binding and release. To compare these experimental autocorrelation curves with kinetic models, we used Monte-Carlo simulations. We find that the experimental data can only be described satisfactorily on the basis of models assuming an alternating-site mechanism, thus supporting the view that kinesin's two motor domains hydrolyze ATP and step in a sequential way

Novel Ways to Determine Kinesin-1's Run Length and Randomness Using Fluorescence Microscopy

The molecular motor protein Kinesin-1 drives intracellular transport of vesicles, by binding to microtubules and making hundreds of consecutive 8-nm steps along them. Three important parameters define the motility of such a linear motor: velocity, run length (the average distance traveled), and the randomness (a measure of the stochasticity of stepping). We used total internal reflection fluorescence microscopy to measure these parameters under conditions without external load acting on the motor. First, we tracked the motility of single motor proteins at different adenosine triphosphate (ATP) concentrations and determined both velocity and (for the first time, to our knowledge, by using single-molecule fluorescence assays) randomness. We show that the rate of Kinesin-1 at zero load is limited by two or more exponentially distributed processes at high ATP concentrations, but that an additional, ATP-dependent process becomes the sole rate-limiting process at low ATP concentrations. Next, we measured the density profile of moving Kinesin-1 along a microtubule. This allowed us to determine the average run length in a new way, without the need to resolve single-molecules and to correct for photobleaching. At saturating ATP concentration, we measured a run length of 1070 ± 30 nm. This value did not significantly change for different ATP concentrations