## Steel, Glass, and Plastic Bottles: What is the best choice?

Earlier this year I published a three-part article series titled “What to do with all this plastic?” (Part One, Part Two, and Part Three), which looked at the global problem with plastics accumulating in different areas around the world and innovative concepts communities have adopted to help deal with the abundance of plastic products and manage the growing problem.

Some looked at the creative reuse of plastic water bottles by communities in Uganda, the Philippines, and right here in Macomb County, Michigan. Plant pots, salt shakers, lighting fixtures, irrigation, and even walls for a greenhouse were concepts communities came up with. While the articles highlighted some steps international and local communities are taking to curb the plastic problem it also provided steps to help eliminate it from every day use. One of those steps is to simply carry your own reusable bottle, which we are seeing more and more of these days. In fact, traditional public water fountains are becoming equipped to refill personal water bottles as well.

But between steel, plastic and glass, which is the best? The truth of the matter is that there are pros and cons to owning each.

Stainless steel bottles have a number of pros and cons. Typically, they last longer than glass or plastic because they are corrosion resistant, and do not leach chemicals when exposed to sun/heat. They are generally more expensive than plastic, as the cost to produce them is much higher due to being energy intensive. However, stainless steel is 100 percent recyclable. The best option for selecting stainless steel water bottles is food grade #304 or 18/8, which means there are 18 percent chromium and 8 percent nickel. Additional information on stainless steel water bottles can be found online.
Glass is another option when choosing water bottles. Most of us know that just about every beverage tastes better out of a glass bottle or cup, but the downside is that they are breakable and less likely to last a long time compared to plastic or stainless steel. In addition, recycling rate is low and some public places do not allow glass too. However, in addition to tasting great glass does not leach when left in the sun/heat, but the cost of a glass water bottle is generally much higher than our other two options.
Plastic seems to be the most popular reusable water bottle, although glass and stainless are gaining in popularity for the reasons listed here. Plastic water bottles, or water mugs are cheaper to produce than stainless steel and glass, which makes them very attractive for consumers. However, the recycling rate of some plastic water mugs is low and the life cycles are short too. Plastic water bottles often end up in landfills and can take nearly 700 years before they start to decompose. One of the biggest downsides to plastic water bottles is that they leach, whereas glass and stainless steel do not. Consumers with apprehensions over plastics leaching chemicals may want to review the U.S. Food and Drug Administration for more information, such as the use of Bisphenol A (BPA)-a chemical component often found in polycarbonate plastic. Some manufacturers of reusable water bottles do produce products free of this chemical and typically note that on labels or the item itself. In addition, plastics made with BPA will often have a resin code of 7 appearing on the item.
Additional information on plastics and problems associated with it can be found on Dr. Lee’s website devoted to health and sustainability related challenges.

Whatever reusable water bottle you decide to select in the end will be of overall benefit to you and our environment too. Reusing a water bottle will help keep plastics out of landfills, reduce your urge to purchase beverages in plastic bottles, and in the long-run save you money.

How are you ensuring safe drinking water when away from home and your preferred water treatment system? When it comes to drinking water, Ontario residents often invest in water systems and coolers to ensure a fresh supply of clean drinking water in the home. However, some fill plastic bottles with filtered drinking water and then reuse those bottles over and over. Unfortunately, this practice could be unsanitary. In addition, there are many concerns about the safety of BPA found in some plastic water bottles. While you could buy a BPA-free plastic water bottle, steel water bottles are a better choice. Below are just a few of the many benefits of stainless steel water bottles.

Stainless Steel Water Mugs are Eco-Friendly
Stainless steel is made out of natural elements to start with, and they can be easily recycled into new products when the time comes. Though plastic bottles are often made from recycled materials and can be recycled themselves, both creating and recycling plastic is less friendly to the environment than stainless steel production and recycling.

Stainless Steel Water Bottles are Much More Durable than Plastic
If you’ve ever used a plastic water bottle, you know how flimsy they can be. Some plastic water bottles are meant for one-time use and crush easily. Others are made to be used multiple times. However, those can melt when washed in the dishwasher. Even if you run over a stainless steel water bottle with your truck, it will survive.

Stainless steel bottles can be used under virtually any condition. Because of their versatility and durability, stainless steel water bottles are the bottles of choice for many athletes and adventurers, also are some glass water mugs.

Stainless Steel Water Bottles are Safe
The plastics in recyclable plastic water bottles are thought to be a health risk. Harmful chemicals are emitted from these bottles, and these chemicals might cause cancer. By switching to stainless steel, you can prevent harmful carcinogens from leaching into your drinking water.

Stainless Steel Water Bottles Keep Your Drinking Water Cold or Hot
Why drink lukewarm drinking water from a plastic water bottle when you could use a stainless steel water bottle that insulates the contents for hours? The insulating properties of stainless steel water bottles mean that you can enjoy cool drinking water up to 24 hours after filling the bottle from your water cooler. Hot water stays warm for nearly six hours in a stainless steel bottle.

You Can Wash Stainless Steel Water Bottles in the Dishwasher
Maintain sanitation by regularly washing your stainless steel water bottle in the dishwasher. Stainless steel is completely dishwasher safe, unlike plastic water bottles which could melt or lose their shape. Regular washing eliminates germs that accumulate after usage.

Environmentally friendly, durable, safe, and easy-to-clean, stainless steel water bottles are an excellent alternative to using plastic water bottles. The steel will not rust, and many desirable features are available such as special caps, cool colours, carrying straps, spouts, handles, clips, and unique shapes. You can even get a customised bottle if you’d like.

Don’t make the same mistake that many people who have invested in water systems in Ontario have made. Use stainless steel water bottles when venturing away from home.

## Multiple-Question choice – TABLE for category of question?

I am working on a multiple choice question form. I am using Flask on the back-end and MySQL 5.7 as a database.

• There will be more than 1 end-user. I already made a users table but haven’t work on it yet
• There are multiple questions but I only display one question at once.
• Every question have either 3 or 4 possible choices (A, B, C or A, B, C, D)
• There is always one correct answer
• The user can filter question based on category and get stats by category (% of question answered for this category for example)

Should I create a new table called category which would look like category_id (int, primary_key), category_text (varchar(50))?

CREATE TABLE questions (   question_id int NOT NULL AUTO_INCREMENT,   contributor_id int NOT NULL,   question_text varchar(1000) NOT NULL,   category varchar(50) NOT NULL,   answer_a varchar(200) NOT NULL,   answer_b varchar(200) NOT NULL,   answer_c varchar(200) NOT NULL,   answer_d varchar(200) DEFAULT NULL,   correct_answer varchar(20) NOT NULL,   PRIMARY KEY (question_id) ) ENGINE=InnoDB AUTO_INCREMENT=10 DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci; 

## If your class gives you a choice of skills to be trained in, can you choose a skill you’re already trained in to gain a free skill choice?

I know that if a class would make you trained in a skill you’re already trained in, you can select another skill to become trained in.

My question is about classes that let you pick between certain skills to be trained in, for example the Fighter lets you pick between Acrobatics and Athletics.

If I’m already trained in Athletics because of my background, can I choose Athletics as my Fighter skill, so that I gain another free skill choice, thus having 4+Int skill choices, instead of the usual 3+Int for a Fighter? Or would I be forced to choose Acrobatics?

## Grouping/sorting performance choice between bigint and nvarchar

I want to store a hash-code for a variable-length text field (max 1000 chars) in a database table. The hash-code will be computed and assigned once on insert, and new rows will be inserted very often.

The hash-code will be used mainly for filtering (WHERE), grouping (GROUP BY), and sorting (ORDER BY) in a couple of queries. The database table will hold a few million rows over time, with the probability of identical hash-codes (for identical text) being around 30% (rest being unique).

I have the choice of making the hash-code data type NVARCHAR (SHA1 of text) or BIGINT (converted bytes of SHA1 of text). I think BIGINT will be better in terms of storage space (less pages).

Generally speaking, which of these two data types will be better in terms of performance, considering the operations mentioned above?

My group teethed on D&D 3.5 and loved 4e, but now we’re eager to take advantage of FATE’s more narrative- and character-driven philosophies. However, on our first (DFRPG) game last night, my players frequently seemed spoilt for choice: faced with “what do you want to do?” instead of “which of these options (like 4e’s power cards) would you like to use?”, we sometimes froze like deer in the headlights.

For a player trained in 4e that their choices are largely limited to a set of specific mechanical actions (eg power cards), narrative-based options seem vast and vague. The golden rule of FATE is to first decide what you want to do narratively and then figure out how to model it mechanically, and this is alien to my players’ experience. We like it conceptually, but can’t get a handle on it yet.

I know this is just new-system pains, but what can I do to make the transition easier?

## How can I issue multiple commands from a single query choice in Roll20?

I created a set of macros using the API to generate attributes for characters on Roll20 to refer to their pronouns for use in macros. I currently have it set up with 3 macros, each with 4 lines because I can’t add multiple attributes with a single command.

How can I use a macro to query which set (male, female, or neutral) of pronouns I want to use? I know I should be able to do something like

 ?{Male, Female, or Neutral? | Male,#Pronouns_M | Female,#Pronouns_F | Neutral,#Pronouns_N}  

And that should work, but I’d rather have it where the contents of those sub-macros are in the main one and delete the sub-macros. Problem is, each of the sub macros is 4 lines such as #Pronouns_F

 !setattr --sel --subjective|'she'  !setattr --sel --objective|'her'  !setattr --sel --PossessiveA|'her'  !setattr --sel --PossessiveP|'hers'  

Is this a thing I can do or do I have to settle for the sub macros?

## Uniform Hashing. Understanding space occupancy and choice of functions

I’m having troubles understanding two things from some notes about Uniform Hashing. Here’s the copy-pasted part of the notes:

Let us first argue by a counting argument why the uniformity property, we required to good hash functions, is computationally hard to guarantee. Recall that we are interested in hash functions which map keys in $$U$$ to integers in $$\{0, 1, …, m-1\}$$. The total number of such hash functions is $$m^{|U|}$$, given that each key among the $$|U|$$ ones can be mapped into $$m$$ slots of the hash table. In order to guarantee uniform distribution of the keys and independence among them, our hash function should be anyone of those ones. But, in this case, its representation would need $$\Omega(log_2 m^{|U|}) = \Omega(|U| log_2 m)$$ bits, which is really too much in terms of space occupancy and in the terms of computing time (i.e. it would take at least $$\Omega(\frac{|U|log_2 m}{log_2 |U|})$$ time to just read the hash encoding).

The part I put in bold is the first thing is confusing me.

Why the function should be any one of those? Shouldn’t you avoid a good part of them, like the ones sending every element from the universe $$U$$ into the same number and thus not distributing the elements?

The second thing is the last "$$\Omega$$". Why would it take $$\Omega(\frac{|U|log_2 m}{log_2 |U|})$$ time just to read the hash encoding?

The numerator is the number of bits needed to index every hash function in the space of such functions, the denominator is the size in bits of a key. Why this ratio gives a lower bound on the time needed to read the encoding? And what hash encoding?

## Complexity of finding choice of entries of matrices

Suppose I have a matrix with entries either $$x$$ or $$y$$, where the number of rows = number of columns = $$n$$. If I want to select/circle $$n$$ entries such that for each row, only exactly one is circled, for each column, also exactly one is circled, and such that all entries circled are only $$x$$ (if such a circling of entries exists), what complexity class does this belong to? Thanks!

## Can choice function in SHA algorithm be used in a simplied way?

While going through the official documentation SHA algorithms from NIST here.

There is a choice and Majority function used. Maj(𝑥,𝑦,𝑧)=(𝑥∧𝑦)⊕(𝑥∧𝑧)⊕(𝑦∧𝑧)
Ch(𝑥,𝑦,𝑧)=(𝑥∧𝑦)⊕(¬𝑥∧𝑧)

Can I use Ch (or Maj) function in a simplified version?

eg:

(x^y)⊕(¬𝑥∧𝑧)
=(x^y)^ ¬(¬𝑥∧𝑧) + ¬(x^y)^ (¬𝑥∧𝑧)
=(x^y)^(x + ¬z) + (¬x + ¬y)^ (¬𝑥∧𝑧) can be further simplified as

(x^y) + (¬x ^z)

can above simplified version be used ??