The Nurse

What follows is a short story I wrote for a class about a year ago. I had to write a story about a cancer treatment machine in the 80s that had gone haywire due to some faulty programming. The machine was known as the Therac-25 and is a pretty interesting story in and of itself. The story was used as cautionary for computer science majors to be careful.


 

Nancy was diagnosed with brain cancer several months ago, but was trying to face it with a stiff upper lip. Her doctor told her that she was lucky to have caught it so early, and while she was young enough to recover quickly. Enduring radiation therapy and the following chemotherapy at older ages can be very brutal on a body, but she should make it through. Surviving the treatment should be the hardest part, and with any luck, she would be free of cancer when it was over. She desperately wanted that.

Nancy was a mother of two children, a boy named John and a girl named Sally. They were growing up so fast, but her oldest, John, was still only 12. She knew her children needed a strong mother, even more so as they entered their formative teenage years. She did not want to confront what would happen if she was not around for them, and she poured her energy into positive thinking. They told her it helped to think positive, so she was trying very hard to do that.

She enjoyed the amount of success she had with her career as well. She was a director of accounts for a global distribution company, and was on track to become a vice president, if she continued to play her cards right. She was also still very much in love with her husband Jack. They had been married 20 years, and she still got butterflies when she thought about him sometimes. He had been a constant friend, lover, and was an amazing father to their children. She was not sure what he would do without her, but she could not bear to think of that either. The financial aspects alone might ruin him, and she realized they might not have made the best financial decisions.

“Misses Neal?” came the voice of the cheery nurse.

Nancy snapped out of her introspection. “Yes?” she replied.

“Please, if you’ll follow me, we are ready to begin the treatment now.”

Nancy rose and followed the nurse down the hall into a very bare looking room with a very large machine in the middle of it. The nurse walked over to a bed lying in front of the machine and smiled, “If you would lie down here please?” Nancy obliged wordlessly. She felt a bit odd with the large machine looming over her. It felt like the machine had a giant eye staring down at her as she took her place. The room began to close in around her, and she felt a sense of impending doom, as if the eye would judge her unworthy of the life-giving treatment it was made to bestow.

The nurse could see her discomfort, and placed a reassuring arm on her shoulder as she finished laying a heavy leaden blanket across her. “The blanket will keep the part of you we don’t want exposed to the radiation safe, and please don’t worry Misses Neal, this is the most advanced machine of its type in the world.”

Nancy managed a smile and a nod as the nurse walked away. She had been told what to expect when the treatment began, and she tried to prepare herself, lying perfectly still, taking regular breathes, and trying to relax. She heard a voice say “We are going to begin now.” The machine began to make noises as its great eye moved into place, then a clicking and whirring noise began. It felt a bit like a drum was pounding in her head when it started, and she wasn’t sure if this was normal. Soon it started to feel like a low grade electrical shock was coursing through her head, and it felt like the world was getting further away. The pain and the noise were becoming oppressive, and she wanted to cry out, but she couldn’t. Her eyes were closed, but bright patterns were dancing before her. Just when she thought she could not take any more it was over.

Nancy heard the nurse walk into the door and say “I hope she is ok.”

“I’m fine,” Nancy responded.

“Hmmm… oh, good!” said the nurse. Nancy heard her say “I’m not sure that went according to plan…”

“What didn’t go according to plan?”

The nurse looked at Nancy like she had seen a ghost. “Did I say that out loud? I’m sorry, I didn’t mean anything by it!” Nancy heard “Doctor Martin is going to kill me for that!”

“Why is Doctor Martin going to kill you?!” Nancy gasped ash she shot bolt upright. “What went wrong?!”

The nurse looked horrified. Nancy heard her say “Nothing!” repeatedly while a stream of obscenities and panic flooded into her ears… Nancy tried to reassure herself that it was her ears that were hearing everything, while the world began to crack around her. She could feel everything the nurse in front of her was thinking and feeling. Nancy began to sob uncontrollably and curled up into a ball on the floor. She wanted it stop. She wished the nurse would go away and stop bothering her with her thoughts. Soon all she heard was the sound of her own sobbing. She opened her eyes.

The nurse was gone.

Differential Pressure Sensors as Specific Gravity Sensors

A while back I was brainstorming with a coworker, and we got the idea that a pressure sensor could be used to detect specific gravity of fermenting beer. This would solve a rather small problem, but potentially disastrous one, for a home brewer like myself. The issue is knowing when your beer is… beer. Usually before you put your wort (Literally unfinished beer) away you take a gravity reading. This reading tells you the amount of stuff (Mainly sugar) that is held in suspension in the wort. Then you put some yeast in the wort, close it up, and wait for the yeast to consume the sugar that was suspended in your wort.

Knowing when that has happened can be a tricky business, especially with a type of yeast or beer style you have never made before. Temperature and acidity can play a big role in this process too, so figuring it out is important. Sadly, the only way most home brewers have to tell when the yeast has done its job is to take another specific gravity reading. This involves sanitizing your equipment, opening your fermenting vessel and either getting a sample or dropping your sanitized meter into the wort. If your wort was not finished, or worse yet, hadn’t even started, you risk introducing a foreign contaminant at this point.

So, the idea is you could build an apparatus that would sit in your wort, and give you a constant specific gravity reading. This would involve two different length tubes, and a sensor that could tell you the pressure difference between those tubes. These sensors exist, and are readily available, so why not give it a try? After a bit of digging around I found Mouser part number 987-SM5852015WD3LR and decided to try it.

Differential pressure sensor with different length tubes attached

The sensor on my bread board with the tubes attached.

After getting everything on my breadboard, and hooking the analog output of the sensor to my volt meter I dropped it into a 5 gallon bucket of pure water. I also took a reading off of my tried and true specific gravity meter. My specific gravity meter read 1.00 (What it should in water), and the pressure sensor was throwing .3 volts at my voltmeter. This was the first sign that this might not work. With the sensor already reading .3 volts it meant it was already close too its maximum reading.

Pressure sensing apparatus attached to voltmeter and submerged into water.

Pressure sensing apparatus attached to voltmeter and submerged into water.

I then added 5 pounds of sugar, mixed until it was suspended in the water, and took another reading with my specific gravity meter. This time it read 1.44, which is not to far from what an actual fresh wort reading might be. Then I put in the pressure sensor, and got the exact same result. .3 volts. So, I proved at least that this sensor is not sensitive enough for what I was trying to do.

Perhaps there is a sensor out there sensitive enough for this type of measurement. If you hear about one let me know, and I’ll keep looking. Until that sensor comes along, I might try some experiments with testing the wort’s capacitance … This might prove more fruitful than the pressure sensor. If you have another idea, please be sure to let me know.

So here I am

I just moved my domain, and my site over to a new host. The old one was giving me fits that I just could not handle. I lost a couple of things in the move, but nothing worth mentioning at all. The truth is that I have not done anything with this domain, and that makes me sad…

Anyway, I do intended to use this as a personal diary of sorts. I need to do a much better job of documenting my hobbies, and this is where I intend to do it. I like to grow my vegetable garden, can and pickle its produce, tinker with electronics, and enjoy home brewing  I’m a simple man with simple pleasures, what can I say? Anyway, I hope I can at least document my own trials and maybe be of help to some others if they should find anything I write!