The Bay Scallop, Argopecten irradians, in Florida Coastal Waters

The bay scallop, Argopecten irradians, supported a small commercial fishery in Florida from the late 1920’s through the 1940’s; peak landings were in 1946 (214,366 lbs of meats), but it currently supports one of the most popular and family-oriented fisheries along the west coast of Florida. The primary habitat of the short-lived (18 months) bay scallop is seagrass beds. Peak spawning occurs in the fall. Human population growth and coastal development that caused habitat changes and reduced water quality probably are the main causes of a large decline in the scallop’s abundance. Bay scallop restoration efforts in bays where they have become scarce have centered on releasing pediveligers and juveniles into grass beds and holding scallops in cages where they woul

A separation of the reactions in photosynthesis by means of intermittent light

Experiments on photosynthesis in intermittent light have been made on two occasions. Brown and Escombe, in 1905, made use of a rotating sector to study the effect of light intensity on the photosynthesis of leaves. They found three-quarters of the light from a given source could be cut out in each revolution of the sector without decreasing the rate of photosynthesis. Willstätter (1918, p. 240) explains that this was probably due to the low concentration of carbon dioxide available for the leaves. The short periods of light would be sufficient to reduce all the carbon dioxide which could reach the cells by diffusion during the dark periods. In 1919-20 Warburg made experiments on Chlorella similar to those of Brown and Escombe on leaves. Instead of stating his results as amount of photosynthesis per total elapsed time, as Brown and Escombe did, he gave photosynthesis per total time during which the cells were illuminated. Since he used sectors which cut out half the incident light in each revolution, the time during which the cells were illuminated was always half of the elapsed time of an experiment. Working with a high intensity of light and a high concentration of carbon dioxide, Warburg found that a given amount of light reduced more carbon dioxide when allowed to fall on the cells intermittently than when allowed to fall on them continuously. The improvement in the yield of the intermittent over the yield in continuous light depended on the frequency of the flashing. With a frequency of four periods per minute the improvement was 10 per cent, and with a frequency of 8000 per minute it was 100 per cent. Warburg proposed two alternative explanations for the improvement in the yield of the intermittent light. Either the reduction of carbon dioxide continues in the dark, or it proceeds twice as fast during the brief light flash as during the same length of time in continuous light. He considers the latter explanation more likely, and assumes that certain steps in the photosynthetic process continue in the dark until a dark equilibrium is reached. After the dark period a short flash of light would find a higher concentration of reactive substance ready for it than is available in continuous light, and would be able to effect more decomposition than an equal amount of continuous light. The experiments described in this paper indicate, we think, that the steps in photosynthesis which proceed in the dark involve what has hitherto been known as the Blackman reaction. Probably the reduction of carbon dioxide is not completed during the photochemical part of the process. A more correct way of representing the sequence of events in intermittent light would be as follows. Two steps are involved in the reduction of carbon dioxide: a reaction in which light is absorbed, followed by a reaction not requiring light -- the so called Blackman reaction. If the light intensity is high the photochemical reaction is capable of proceeding at great speed, but in continuous light it can go no faster than the Blackman reaction. We suppose that the product formed in the photochemical reaction is converted to some other substance by the Blackman reaction, and at the same time the chlorophyll is set free to take part again in the photochemical reaction. If a green cell is illuminated, we think that the photochemical reaction proceeds rapidly until an equilibrium concentration of its product is formed. After this the photochemical reaction proceeds only as fast as the Blackmail reaction removes the intermediate product. If the cell is now darkened, the photochemical reaction stops at once, but the Blackman reaction continues until its raw material, the product formed by the photochemical reaction, is exhausted. After this nothing further happens until the cell is again illuminated. Higher efficiency of the light would be obtained if each light flash lasted only long enough to build up the equilibrium concentration of the intermediate product, and each dark period were long enough to allow the Blackman reaction time to use up all the intermediate product present at the moment the light period ended. In Warburg's flicker experiments the light and dark periods were always of equal length. He found that the amount of work done by the light could be increased by shortening both the light and the dark periods. This indicates that his light periods were too long for maximum efficiency. In the latter part of each light period the photochemical reaction must have been brought down to near the speed of the Blackman reaction. Using 133 light flashes per second, Warburg obtained an improvement of 100 per cent over the continuous light yield. We were able to improve the continuous light yield 300 per cent to 400 per cent by using only 50 flashes per second and making the light flashes much shorter than the dark periods. This opened the possibility of determining the length of the dark period necessary for the complete removal of the intermediate product formed in a light flash of given intensity and duration. Lengthening the dark period should improve the yield until there is time enough for all the intermediate product formed in each light flash to be removed before the next light flash. In this paper we describe experiments which show that the necessary dark time is about 0.03 to 0.4 of a second, depending on the temperature. Further experiments are described to show certain characteristics of the reactions taking place both in the light and in the dark

Evaluating true BCI communication rate through mutual information and language models.

Brain-computer interface (BCI) systems are a promising means for restoring communication to patients suffering from "locked-in" syndrome. Research to improve system performance primarily focuses on means to overcome the low signal to noise ratio of electroencephalogric (EEG) recordings. However, the literature and methods are difficult to compare due to the array of evaluation metrics and assumptions underlying them, including that: 1) all characters are equally probable, 2) character selection is memoryless, and 3) errors occur completely at random. The standardization of evaluation metrics that more accurately reflect the amount of information contained in BCI language output is critical to make progress. We present a mutual information-based metric that incorporates prior information and a model of systematic errors. The parameters of a system used in one study were re-optimized, showing that the metric used in optimization significantly affects the parameter values chosen and the resulting system performance. The results of 11 BCI communication studies were then evaluated using different metrics, including those previously used in BCI literature and the newly advocated metric. Six studies' results varied based on the metric used for evaluation and the proposed metric produced results that differed from those originally published in two of the studies. Standardizing metrics to accurately reflect the rate of information transmission is critical to properly evaluate and compare BCI communication systems and advance the field in an unbiased manner

Fire on the Mountain: the Bronze and Iron Alpine Ash Altar Material in the Frankfurth Collection at the Milwaukee Public Museum

Milwaukee Public Museum (MPM) Accession 213 is one of many collections orphaned by nineteenth century antiquarian collecting practices. Much of the European prehistoric and early historic material in MPM Accession 213 was collected in a single two-year period from December 1889 to December 1891, but the sudden death of the donor--William Frankfurth--and the passage of a decade between collection and donation left the museum without much context for the materials. Among the artifacts in MPM Accession 213 is a collection of almost 350 metal objects from prehistoric and early historic Europe that have yet to be examined or contextualized. Through archival research and comparative analysis, I demonstrate that the prehistoric metalwork present in this collection comes from one or more of seven identifiable sites--the Grumserbühel, the Sinichkopf, the Segenbühel/Hochbühel, the Fachegg, the Tartscherbühel, the Sonnenburgerbühel, and the Tuiflslammer--all of which have produced evidence of a specific type of prehistoric context called Brandopferplätze [places for burnt sacrifices], also known as Alpine ash altar sites. Alpine ash altar sites offer a unique glimpse into the ritual life of prehistoric European populations because they were in continuous use from the Bronze Age to the Roman period. Using the excavation history of each of these sites, it was possible to narrow down the probable candidates to three of the known sites, as well as at least one unknown Roman site. The artifacts were then categorized and analyzed for presence/absence and degree of damage against existing collections from other Alpine ash altar sites to assess the likelihood of the material coming from this type of context. It was expected that the material profile would closely match the presence/absence of materials from more recently excavated Alpine ash altar sites, and thus provide a foundation for further research into the origins of MPM Accession 213

Introduction to Measurement with Theory.

This paper is the introduction to the forthcoming Macroeconomic Dynamics Special Issue on Measurement with Theory. The Guest Editors of the special issue are William A. Barnett, W. Erwin Diewert, Shigeru Iwata, and Arnold Zellner. The authors of this detailed introduction and commentary are William A. Barnett, W. Erwin Diewert, and Arnold Zellner. The included papers are part of a larger initiative to promote measurement with theory in economics.Measurement; index number theory; aggregation theory.

More efficient use of fertilizers

Cover title

Correcting soil deficiencies for more and better forage from permanent pastures

Cover title.Includes bibliographical references