Objectives
To examine the thermoregulatory and fluid‐electrolyte responses of firefighters ingesting ice slurry and carbohydrate–electrolyte solutions before and after firefighting operations.
Methods
Twelve volunteer firefighters put on fireproof clothing and ingested 5 g/kg of beverage in an anteroom at 25°C and 50% relative humidity (RH; pre‐ingestion), and then performed 30 minutes of exercise on a cycle ergometer (at 125 W for 10 minutes and then 75 W for 20 minutes) in a room at 35℃ and 50% RH. The participants then returned to the anteroom, removed their fireproof clothing, ingested 20 g/kg of beverage (post‐ingestion), and rested for 90 minutes. Three combinations of pre‐ingestion and post‐ingestion beverages were provided: a 25℃ carbohydrate–electrolyte solution for both (CH condition); 25℃ water for both (W condition); and a −1.7℃ ice slurry pre‐exercise and 25℃ carbohydrate–electrolyte solution post‐exercise (ICE condition).
Results
The elevation of body temperature during exercise was lower in the ICE condition than in the other conditions. The sweat volume during exercise was lower in the ICE condition than in the other conditions. The serum sodium concentration and serum osmolality were lower in the W condition than in the CH condition.
Conclusions
The ingestion of ice slurry while firefighters were wearing fireproof clothing before exercise suppressed the elevation of body temperature during exercise. Moreover, the ingestion of carbohydrate–electrolyte solution by firefighters after exercise was useful for recovery from dehydration.
Steganography aims to make communication invisible by hiding genuine information in innocuous objects. We have proposed the SMF steganography that enables to hide information into Standard MIDI Files (SMF). The SMF is widely used as a standard storage format of the data of Musical Instrumental Digital Interface (MIDI). Most of digital musical instruments and personal computers equip the MIDI. Our hiding method utilizes a redundancy of the description of note events (note on/off) in SMF. Some note events which are performed simultaneously are allowed as correct contents of SMF even if they are described in any order. Therefore, we can permute the order of such note events according to the embedded data without changing their sounds. To clarify the potential of the SMF steganography, we calculate the embeddable data size about over three hundred SMFs that are opened to the public on the Internet. As a result, the embedding rate, which is the percentage of embeddable data size to cover SMF size, shows about 1% on average, and the best case reaches about 4%. We also clarify the influence of the Quantize function (which adjusts the timing of note events) on the embeddable data size.
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