منابع مشابه
Melting the Iceberg: Contrast Invariance in Visual Cortex
Neurons in visual cortex maintain their selectivity for stimulus orientation despite wide variations in stimulus contrast. Achieving this invariance is a challenge because of the iceberg effect: subthreshold responses are broader in selectivity than firing responses, and increasing contrast would bring them above threshold. An article in this issue of Neuron by Finn et al. explains how neurons ...
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Observations near a large tabular iceberg in theWeddell Sea inMarch and April 2009 show evidence that water from ice melting below the surface is dispersed in two distinct ways. Warm, salty anomalies in T–S diagrams suggest that water from the permanent thermocline is transported vertically as a result of turbulent entrainment of meltwater at the iceberg’s base. Stepped profiles of temperature,...
متن کاملComputing Iceberg Queries Eeciently
Many applications compute aggregate functions over an attribute (or set of attributes) to nd aggregate values above some speci ed threshold. We call such queries iceberg queries, because the number of abovethreshold results is often very small (the tip of an iceberg), relative to the large amount of input data (the iceberg). Such iceberg queries are common in many applications, including data w...
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Calving from the floating termini of outlet glaciers and ice shelves is just the beginning of an interesting chain of events that can subsequently have important impacts on human life and property. Immediately after calving, many icebergs capsize (roll over by 90◦) due to the instability of their initial geometry. As icebergs melt and respond to the cumulative effects of ocean swell, they can a...
متن کاملComputing Iceberg Queries Efficiently
Many applications compute aggregate functions over an attribute (or set of attributes) to find aggregate values above some specified threshold. We call such queries iceberg queries, because the number of abovethreshold results is often very small (the tip of an iceberg), relative to the large amount of input data (the iceberg). Such iceberg queries are common in many applications, including dat...
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ژورنال
عنوان ژورنال: Nature
سال: 1913
ISSN: 0028-0836,1476-4687
DOI: 10.1038/090671d0