Friday, April 13, 2001
Happy Friday 13th and Happy Good Friday! Easter is just around the corner! Just remember, dying eggs is fun but don't eat too many!
So my week went by fairly quickly, I must happily say. I'm left with a lab today at 3pm, then an EMS shift from 7-11. Today's lab is with the intro engineering course, and we will be comparing MP3 and CD audio. About 99% of the MP3 music properly encoded (with a quality encoder) at 128 kbps and 44.1 kHz is entirely indistinguishable from CD audio. However, the amount of data in the MP3 is about 80-90% smaller than that of uncompressed CD data.
How? Simple, but ingenious. Do you notice that when you're driving fast in a car, you can't hear small noises? Or when you pull off the freeway, you need to turn the radio down? These are the effects of the audio masking phenomenon. Each frequency of sound has the ability to mask, or hide, certain frequencies that are slightly softer in amplitude (volume). The end result? CDs record every sound from the studio; with MP3, the bottom line is if you can't hear it, don't keep it. In fact, over 90% of the audio your CD plays is inaudible due to masking. Although not technically comparable, you can get an idea when an audio CD holds 70 minutes of music, while a data CD holding purely MP3 audio can store almost 10 hours of music, of the same quality.
My summer jobs are looking promising. After contacting my supervisor at the Aquatic Center, they will be able to schedule me based on my own summer dates, which happen to be one month earlier than theirs. Even cooler, Tualatin Hills Park and Recreation District (THPRD) has signed on to a Public Access Defibrillation (PAD) program, in partnership with OHSU and Tualatin Valley Fire. This means that nine THPRD sites, including the Aquatic and Tennis Centers (Rec Center Complex), Somerset West, and the Nature Park, will be equipped with Automated External Defibrillators (AEDs). Six of the remaining THPRD facilities will receive study-approved CPR training, but no AEDs. In exchange for reporting data and cooperating with the study, at the end of the 12-18 month period, ALL District facilities will then be outfitted with AEDs, and all staff will be trained in their use. That's over $50,000 of equipment and training, at no cost to the District.
Does CPR save lives? Yes and no. CPR sustains minimal oxygen flow to the body's vital organs to keep the body alive. However, in cases of cardiac arrest with a shockable rhythm, a victim who receives the first AED shock within 1 minute has a staggering 60-70% survival rate. What's a shockable rhythm? Ventricular fibrillation (v-fib) or pulseless ventricular tachycardia (v-tach) are both shockable by an AED and are the most common in sudden cardiac arrest. V-fib is when the heart beats irregularly, while v-tach is a very rapid beat; both are completely ineffective for circulating blood, and although the heart is technically beating, a pulse will not be felt.
So why do we need PAD? Unfortunately, survival rates for sudden cardiac arrest decrease by 10% after every minute without defibrillation, with or without CPR. The PAD program emphasizes early defibrillation--the first shock within 3 minutes of losing a pulse. Although paramedics carry lifesaving drugs and CPR has sustained the bodies organs, the damage to the heart will often be irreparable by the time of their arrival, usually 5-6 minutes.
That's today's lesson, so until next time...
Aaron
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