Store Sizes Research Articles

Probability of Quantal Secretion and the Mobilization of Vesicles at the Active Zones of Endplates

A vesicle mobilization model is developed for active zones of motor-nerve terminals. In the model, vesicles from a storage pool are recruited to an available pool where they are docked at the active zone, the latter pool being replenished by endocytosis. The predictions of this model are then compared with experimental results on these active zones. If a styryl dye (FM 1-43) is used to stain all of the vesicles at motor-nerve terminals then the stores of vesicles associated with different active zones are shown to vary considerably in size. Under the assumption that the available pool size is proportional to the storage pool size, the mobilization model shows that the extent of destaining of these stores during a particular period of stimulation is proportional to the size of the storage pool, this size being indicated by the initial staining. This is not so under the alternative assumption that the available pool size does not vary proportionally with store size. If the two pools are proportional then the number of quanta released from the available pool is proportional to the storage pool size. Experimental results indicate that there is a linear relationship between destaining and staining, as well as between quantal release and staining at different sites along motor-nerve terminals, thus favouring the hypothesis that available pool size (or the size of the active zone) and store size are proportional. Given that there are very different store sizes along the length of motor-nerve terminals, this analysis provides further evidence for the non-uniform probability of quantal secretion at different active zones within a single motor-nerve terminal.

The hurst effect and its implications for extrapolating process rates

AbstractIn long‐term records of climatic or hydrological events, persistent periods of high and low values are measured by the ‘rescaled range’, which is defined for a sequence of n consecutive values. As n increases the rescaled range for historic sequences increases as nH for 0·5 < H < = 1. This is the Hurst effect. Sequences of independent random events give H = 0·5, while sequences in which the values are successive positions of a random walk (i.e. the sum of independent events) give H = 1. Intermediate values of H may be obtained from fractal sequences, from sequences with a steadily changing mean, or through a storage model. In all but the fractal case H exceeds 0·5 for a time related to the duration of the changing mean or the response time of the store.An exponential storage model has been explored in some detail. Storage models have the advantage of offering a plausible physical mechanism for persistence. Analysis of simulated sequences shows that the Hurst effect is evident for about 30 x the response time of the store, so that relatively modest store sizes are enough to explain observed Hurst effects over available periods of record. Comparison with empirical values shows that high H values seem to be associated with large physical stores.Whether the Hurst effect is due to storage effects or climatic or other change imposed from outside, the effect on longterm process rates is strong. Short‐term measurements of process rates show compressed variances and simple extrapolation is likely to produce large errors. If it is assumed that long‐term rates are strongly influenced by climatic variables, then measurements may be used to obtain parameters of a climatic model for differences in process rates. Errors in extrapolation will be least where the model has a sound physical basis.A first implication for magnitude and frequency distributions is that the sequence of events may be as important as their distribution over time in determining process impact. A second conclusion is that the geomorphic history of an area is inevitably dominated by a sequence of larger and larger events receding into the past, and that the Hurst exponent over geologic time‐spans measures the extent of that domination.

Price Behavior and Store Size in Grocery Retailing

The effects of different store sizes on relative prices are derived for three types of price behavior in grocery retailing. A theoretical model is formulated and estimated using prices collected by the Central Bureau of Statistics in Norway for the consumer price index. The results indicate that recommended prices are adopted to a large extent in all store sizes, as the general price levels did not differ significantly. However, the largest stores are demand oriented in the sense that products with a high share of the average household's budget were relatively lower priced, while the opposite was the case for less important products. The general markup level was adjusted to capture demand variations over the year. I. Introduction In grocery retailing, small stores have exhibited a high exit rate during the last couple of decades. At the same time, relatively large stores are prominent among the new entries. This development is a result of many factors which operate on both the supply and the demand side and has caused the average size of stores to increase and the total number of stores to decrease. On the demand side, one of the factors which has been proposed to explain the increasing tendency for consumers to patronize large stores is that they offer lower prices. However, store characteristics other than the general price level may account for the growth of large stores. As far as prices are concerned, the structure of prices may be more important than the general level of prices. The assortment of a grocery retailer usually contains more than a thousand items. Consequently, it is virtually impossible for consumers to consider all prices. Their attention is concentrated on the prices of a limited number of items which are used as cues for the overall price level. Demand at the store level is particularly elastic for some products and rather inelastic for others, as elaborated by Holton (1957). This makes it profitable to use different margins for different products. Furthermore, cross-price elasticities within the assortment should be taken into account if the aim is to maximize profits. The ability to set prices in accordance with demand relations may vary with store size. The largest stores probably have profes

INFLATION: ITS IMPACT ON RETAIL TRADING

The impact of inflation on the trading of food retailers in North America shows itself in various ways: in store closures, in the rise of independent retailer strength, in polarisation of store sizes and in the targeting of marketing efforts. These are the major consequences of inflation which Richard Currie, speaking at the CIES annual executive congress last year, pinpointed. Although looking specifically at the North American scene, his paper has relevance to the European situation, especially in his references to the marked effect on inflation that even a small change in productivity may have.

A method of minimizing the costs of combine-harvesting and high temperature grain drying

A model was developed to minimize the average cost of harvesting and drying over 10 years taking into account machine and grain loss costs from harvesting and of a high temperature drier and wet grain store. The number of days that could be worked was determined from weather parameters. The effect of different weather regions and of different drier and store sizes was considered. It was demonstrated that the optimum size and speed of combine-harvester and size of grain store could be determined. The model can therefore be used to quantify the costs of harvesting or to evaluate the effect of different loss characteristics of the grain or combine-harvester.

Method of using redundancy in very large computer stores

The organisation of a very large random-access computer store which uses redundancy in the form of error-correcting codes is described. The improvements in manufacturing yield which can be achieved by means of such redundancy are emphasised in the form of examples. However, with typical basic store sizes in the capacity range 10 7 -10 8 bits, some of the most significant improvements in manufacturing yield are achieved by programmed assembly which makes use of the ease of testability of such redundant systems. The conclusion is that widespread use of the proposed technique of design and manufacture can result in significant savings, both to designer and customer.