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Medium 9781591200796

2. Cells, DNA Damage, and DNA Repair

Giampapa M.D., Vincent C. Basic Health Publications ePub


Cells, DNA Damage, and DNA Repair


—The Talmud

Cells are the basic unit in every organism, from one-celled bacteria to human beings. They make up all of the body’s tissues, including skin, organs, bones, nerves, and blood. Cells carry out all of the body’s functions. New cells are created by existing cells as the result of cell division, ensuring the continuity of life. Cell division is the mechanism by which traits are passed from one generation to the next. When a cell divides, the genetic material within the so-called parent cell is distributed equally to the two daughter cells, making them genetically identical to the parent. If our cells did not divide and reproduce, we would not grow through the stages of human development. Even when we reach adulthood, cell division remains necessary to replace damaged or dying cells with new, healthy offspring. Depending on their function, some cells divide once a day or even more often. By contrast, some of the most highly specialized cells in the body, such as nerve cells, may not divide at all, although science is beginning to question the long-held assumption that nerve cells that die are never replaced.

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Medium 9781576336205

Heat and Gases: ASVAB Physics

Ace Academics Ace Academics ePub
Medium 9781593578169


Jean Baur JIST Publishing ePub

As mentioned in the introduction, I fell into the outplacement field (career coaching) in the mid-1990s through an odd set of circumstances. I had worked as a corporate trainer, flying all around the country giving classes on business writing and presentation skills. Then I had transitioned back to writing and spent five years writing press releases, articles, and monographs for an educational company. That work ended and I was stuck because I really didn’t want to go back into training and there didn’t seem to be other writing assignments nearby. (It was at this time that I was also writing fiction and trying to get that published—a huge uphill battle.)

My son was 9 and my daughter was 19—just off to college. My husband was working at a local college as an adjunct, which meant not great pay and no benefits. So I was under real financial pressure to find work, but I knew more about what I didn’t want to do than what I did. (What I tell my clients now when I hear a similar message is that this is a great place to start. Knowing what you don’t want to do gives you the beginning of a plan.)

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Medium 9780596521677

3. Fancy Phone Tricks

David Pogue O'Reilly Media ePub

Once you've savored the exhilaration of making phone calls on the iPhone, you're ready to graduate to some of its fancier tricks: voicemail, sending text messages, using AT&T features like Caller ID and Call Forwarding, and using a Bluetooth headset or car kit.

Without a doubt, Visual Voicemail is one of the iPhone's big selling points. On the iPhone, you don't dial in to check for answering-machine messages people have left for you. You don't enter a password. You don't sit through some Ambien-addled recorded lady saying, "You have17messages. To hear your messages, press 1. When you have finished, you may hang up"

Instead, whenever somebody leaves you a message, the phone wakes up, and a message on the screen lets you know who the message is from. You also hear a sound, unless you've turned that option off (Brightness) or turned on the silencer switch (Silencer Switch, Volume Keys).

That's your cue to tap HomePhoneVoicemail. There, you see all your messages in a tidy chronological list. (The list shows the callers' names if they're in your Contacts list, or their numbers otherwise.) You can listen to them in any orderyou're not forced to listen to your three long-winded friends before discovering that there's an urgent message from your boss. It's a game-changer.

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Medium 9780596009250

5. Parallel System Tools

Mark Lutz O'Reilly Media ePub

Most computers spend a lot of time doing nothing. If you start a system monitor tool and watch the CPU utilization, youll see what I meanits rare to see one hit 100 percent, even when you are running multiple programs.[*] There are just too many delays built into software: disk accesses, network traffic, database queries, waiting for users to click a button, and so on. In fact, the majority of a modern CPUs capacity is often spent in an idle state; faster chips help speed up performance demand peaks, but much of their power can go largely unused.

Early on in computing, programmers realized that they could tap into such unused processing power by running more than one program at the same time. By dividing the CPUs attention among a set of tasks, its capacity need not go to waste while any given task is waiting for an external event to occur. The technique is usually called parallel processing because many tasks seem to be performed at once, overlapping and parallel in time. Its at the heart of modern operating systems, and it gave rise to the notion of multiple active-window computer interfaces weve all come to take for granted. Even within a single program, dividing processing into tasks that run in parallel can make the overall system faster, at least as measured by the clock on your wall.

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