Tag Archives: lifehack

Preventing cheating is hopeless in online learning

Technology makes cheating easy even in in-person exams with invigilators next to the test-taker. For example, in-ear wireless headphones not visible externally can play a loop recording of the most important concepts of the tested material. A development of this idea is to use a hidden camera in the test-takers glasses or pen to send the exam contents to a helper who looks up the answers and transmits the spoken solutions via the headphones. Without a helper, sophisticated programming is needed: the image of the exam from the hidden camera is sent to a text-recognition (OCR) program, which pipes it to a web search or an online solver such as Wolfram Alpha, then uses a text-to-speech program to speak the results into the headphones.

A small screen on the inside of the glasses would be visible to a nearby invigilator, so is a risky way to transmit solutions. A small projector in the glasses could in theory display a cheat sheet right into the eye. The reflection from the eye would be small and difficult to detect even looking into the eyes of the test-taker, which are mostly pointed down at the exam.

If the testing is remote, then the test-taker could manipulate the cameras through which the invigilators watch, so that images of cheat sheets are replaced with the background and the sound of helpers saying answers is removed. The sound is easy to remove with a microphone near the mouth of the helper, the input of which is subtracted from the input of the computer webcam. A more sophisticated array of microphones feeding sound into small speakers near the web camera’s microphone can be used to subtract a particular voice from the web camera’s stereo microphone’s input. The technology is the same as in noise-cancelling headphones.

Replacing parts of images is doable even if the camera and its software are provided by the examiners and completely non-manipulable. The invigilators’ camera can be pointed at a screen which displays an already-edited video of the test-taker. The editing is fast enough to make it nearly real-time. The idea of the edited video is the same as in old crime movies where a photo of an empty room is stuck in front of a stationary security camera. Then the guard sees the empty room on the monitor no matter what actually goes on in the room.

There is probably a way to make part of the scene invisible to a camera even with 19th century technology, namely the Pepper’s Ghost illusion with a two-way mirror. The edges of the mirror have to be hidden somehow.

Clock and ads projected on the ceiling

At a public swimming pool, the clocks on the wall are usually small, far and hard to see through droplet-covered goggles. The clock is relevant for planning to finish by a certain time and for tracking one’s speed (lap time). A solution is to use a projector to show a large clock on the ceiling, or to draw the numbers on the ceiling with a laser – essentially a programmed pointer.

The ceiling is also an untapped advertising display space, not just at swimming pools and gyms, but in any building. Ceiling ads are more valuable in swimming pools, gyms and yoga studios than in most other structures, because people doing backstroke, bench press or fish pose are facing the ceiling, which is not the case in a majority of buildings.

The floor is also mostly unused ad space. Projecting ads on the floor is not as useful as the ceiling, because people walking through the projector beam block the display.

Preventing overeating by advance cooking

A commitment device that prevents overeating is to only buy food that needs cooking (raw meat or fish, dry goods such as rice, flour, beans), and only buy drinks with zero calories. After each meal, measure out the ingredients for the next meal. The ingredients may be put into a pressure cooker, slow cooker, microwave or other gadget with a timer to cook, so the food is ready at the next mealtime, but not before. This procedure leaves no ready-to-eat food to snack on between mealtimes and no option to eat a larger portion than planned. The reason to portion out the next meal right after the previous meal is to do it while not hungry, thereby preventing oneself from increasing the portion size.

Sufficiently fast food delivery breaks the commitment, because it permits ordering a snack that arrives before the next mealtime. Such delivered food is typically processed and unhealthy. Vending machines, convenience stores, takeout restaurants or other sources of ready food in or near the building also weaken the commitment. Quarantine strengthens the commitment, reducing the temptation to go out seeking food.

Eating a balanced diet is more difficult when restricting food to only categories that need significant preparation time. Fruits and most vegetables can be eaten raw and juices give quick calories due to their high glycaemic index. Frozen fruits and vegetables are more difficult to snack on immediately, thus ease commitment without compromising health. Frozen fruit juice concentrate similarly delays gratification for at least a few minutes. Small berries thaw very quickly in water, so are a temptation.

Lifehacks to prevent overeating (from Youtube): eat in front of a mirror, avoid distractions like a computer, TV or smartphone while eating, use small dishes (Japanese style).

Virtual reality helmet for video calling

Current virtual reality headsets can display video calls, but the person wearing the VR goggles is filmed from outside these. A face with its top half covered by VR goggles is not very expressive, which somewhat defeats the purpose of a video call. The solution is a sphere around the head with the webcam inside it and the video of the other caller projected on the inside. An astronaut’s helmet is an analogy.

To prevent suffocation, the sphere should not be airtight – small CPU fans can be installed at the top or back to circulate air in and out. This also prevents humidity buildup. For headphones as well, I would prefer some ventilation of the area covered.

Multiple webcams pointed at the face allow for 3D imaging, so the video call could take full advantage of the 3D display of virtual reality headsets. However, 3D display relies on projecting a different image to each eye. If the video call is simply projected on the inside of the sphere, then it is a single image and the 3D effect is lost. One solution is to point a small data projector at each eye to display different images. Then the sphere is not needed, just cameras and projectors attached to a stick attached to a headband. A Dilbert comic had this idea, but I cannot find the link on the web.

Bending polycarbonate glasses

Polycarbonate glasses (sunglasses, safety goggles) can be bent to better fit one’s head by heating the thermoplastic polymer with a lighter, gas stove or other heat source. Example photos are below. Polycarbonate is not flammable and tolerates repeated heating and cooling. The only problem is that the paint discolours when heated and the plastic buckles and wrinkles when bent, so the lenses should not be heated, lest they become unusable. However, for the handles, a better fit outweighs cosmetic appearance in many applications.

Asking questions of yourself

To make better decisions, ask about all your activities “Am I doing this right? Is there a better way?” I would have benefited from considering such questions about many everyday tasks. For example, I brushed my teeth wrong (sawing at the roots) until late teens, brushed my teeth at the wrong time (right after a meal when the enamel is soft) until my 30s. I only learned to cut my own hair in my mid-20s, and this was the highest-return investment I ever made, because a hair clipper costs as much as a haircut, so pays for itself with the first use.

Peeling a kiwi with a spoon is far easier than slicing with a knife. All it took to learn this was one web search, but it required asking myself the question of whether I was peeling fruit optimally. Same for extracting the seed from an avocado.

Cracking the shell of a hard-boiled egg, making two holes at the ends and blowing air under the membrane before peeling is another trick I wish I had known earlier.

Microwaved food is cooler in the centre, so to avoid scalding one’s mouth, it is helpful to start eating it from the middle. Cooked food left in a covered cooking pot or transferred to a storage container while still mildly hot does not go bad at room temperature for several days – doing this experiment required posing this hypothesis. Drinking without touching the bottle with one’s mouth turns out to be quite easy and is widespread in India.

Only after learning to drive did I start meaningfully using gears on a bicycle, and it took about 15 years more to start shifting approximately correctly (pedalling cadence 60-100 rotations per minute, downshifting before stopping, avoiding cross-geared riding). Similarly for basic bike maintenance like cleaning and oiling the chain, selecting the appropriate front and rear tire pressure given one’s weight and tire widths. Seat height is one thing I figured out early, but not handlebar height.

As a teenager, I would have benefited from asking myself whether I was overtraining, whether my nutrition was reasonable, how soon to return to training after various injuries and whether to seek medical assistance with these. Questioning the competence of coaches and doing a simple web search for sports medicine resources would have prevented following some of their mistaken advice.

Sometimes asking yourself the question reveals that you are already doing the task correctly. On the internet, people claim that they do not use shampoo, just water, and their hair stays clean-smelling and more lush than using detergent. An experiment not to use shampoo was a failure for me, causing greasy hair and lots of dandruff after a few days. The optimality of shampoo may depend on individual scalp and hair characteristics. On the other hand, a single-blade disposable razor and cold water give me a better shave than multi-bladed fancy brands with foam (that get clogged), and the disposable razor stays sharp enough for a month or two of everyday shaving.

When going to teach, it may be worth asking whether the room is the correct one, even if some students show up and the room is free, because once in this situation I was in a room with the right label, but in the wrong building.

On the other hand, constantly doubting oneself is unhealthy and unhelpful. If enough evidence points one way, then it is time to make up one’s mind.

Book-like screen arrangement

Office computer screens are mostly kept in the landscape orientation, but are usually used for documents, which are in the portrait format. Modern screens can be rotated to portrait mode, which makes reading print-view documents easier, or at least allows a larger fraction of the document to be displayed. Taking this one step further, for markup languages (XML, LaTeX) or programming, it is often helpful to see both the code and the compiled output side by side. This may be displayed on one large split screen in landscape orientation or two vertically oriented screens in a book-like arrangement, as in the following image.

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Multifunctional layered clothing

Hiking websites recommend wearing layers, because these make adjusting between warm and cold weather or uphill and downhill walking simple. One thick garment would only work for cold, but taking it off when it gets too hot may leave only too thin clothing.

The same principle of layers applies for everyday clothes. My office is 12 degrees in winter mornings, so I wear two pairs of pants, sometimes two vests and a fleece. Instead of one thick pair of pants that would only suit cold temperatures, thin pants can be worn singly in warm weather and doubled up in cold.

For cycling in the cold, shorts can be worn under long athletic slacks. This principle should also work for hats – two thin fleece ski caps instead of one thick, but I have not tested it. Similarly, two pairs of socks. Although, just like with thick socks, if doubled socks make the shoes fit too tightly, then the reduced circulation increases the cold feeling.

Toe warmer making instructions on the internet suggest using the cut-off front parts of old socks. A more multifunctional option is to roll back existing socks halfway, so both the toe and the ankle part of the sock cover the toes, as in the following image.

Cut socks only work as toe warmers, but rolled-back socks can be used year round.

Food calories are not directly related to obesity

It seems that the change in bodyweight should be a strictly increasing function of calories eaten minus calories spent. The first caveat to this claim is that calories in the food eaten do not equal the calories absorbed, which is what matters for weight gain. People differ in the efficiency of their digestion – that is what bariatric surgery relies on. Also, food labels use calories measured by the burn method (dry the food, burn it, measure the heat output), which ignores for example that coarsely chewed food chunks pass through the digestive tract relatively unchanged, thus contribute few nutrients to the organism. An extreme example is wholegrain flax (linseeds) that remain undigested due to a waxy coating. In nature, seed dispersal by birds relies on the indigestibility of the seeds.

Even if calories absorbed could be accurately measured, the type of food eaten would still matter for weight gain due to imperfect willpower. Some foods are more addictive than others, notably those rich in refined carbohydrates – an easy example is drinks that are essentially sugar-water. Consuming a given amount of calories from high-glycaemic-load sucrose makes people eat more sooner on average than ingesting the same calories from slowly digested whole grains or unsaturated fat. Similarly, ignoring willpower limitations is why abstinence-based programs to prevent sexually transmitted infections, which naively might be expected to be 100% effective, are in fact ineffective (Underhill et al 2007, doi:10.1136/bmj.39245.446586.BE).

There are various tricks to circumvent limited willpower to win the game against one’s future tempted self. To reduce temptation, food should be out of sight outside mealtimes (in cupboards, drawers, fridge) and unhealthy snacks should not be bought at all. Even seeing dishes and cutlery may trigger cravings, in which case these too should be placed out of sight when not in use.

Avoiding grocery shopping while hungry is an old piece of advice, which may be taken further by having someone else buy your food. Two people can even agree to grocery-shop for each other according to shopping lists exchanged beforehand. Online ordering may be a solution, but of course the merchants want customers to buy more, so advertise tempting foods with photos on their website. These ads can be blocked with some effort. A more sophisticated solution is to have one’s own user interface (front end) interact with the merchant’s website – scrape the data on inventory and prices, send commands to buy.

Chair material should be breathable

Strangely enough, fancy office chairs are often upholstered in leather or other non-breathable material. After an hour or so, sitting in them gets uncomfortable because the moisture does not evaporate from the skin that is separated from the chair only by some cloth. However, people usually sit in office chairs for hours at a time, and I doubt that the chairs are designed to deliberately provide some discomfort to encourage users to occasionally stand up for health reasons. Especially in a hot climate when the air conditioning may break down or just be too weak, a breathable chair would make much more sense. Making a mesh chair is simple: stretch a breathable fabric on the chair frame. The small holes in the fabric let moisture evaporate from the surface. A mesh chair is probably cheaper to manufacture than a leather-upholstered one.

A reason for using leather may be to signal wealth by using a material associated with expensiveness.

Modern synthetic meshes are as durable as leather for practical purposes, because sitting in a chair is not a high-wear use.