2.1 - Gloves to help subsistence farmers

Mitchell van Schepen, University of Guelph, Canada

Background

The world’s 1 billion women and girls participating in subsistence farming pull weeds by hand to improve their crops and also collect firewood for cooking, resulting in their hands becoming rough and sore (Figure 1). This can be caused by wood splinters being lodged into their skin (Schaffner, 2013). Pulling weeds for hours on end can peel away layers of skin (Food and Agriculture Organization, 2016). The hands of those farmers can also become dirty and smelly from planting seeds in the soil or spreading manure by hand. To avoid the common aforementioned problems as well as hand injuries, such as cuts and scrapes, they could wear gloves on their hands, see the second picture, (Schaffner, 2013). Gloves are very common in the modern world and can be used for construction, farming, and medical practices. Gloves provide a durable layer between the skin on your hands and whatever you are working with (Espasandín-Arias & Goossens, 2014). There are a few different materials used to make gloves, along with different sizes and grips. With over one billion women and girls working on farms around the world, this grueling work can be made safer and more efficient when wearing gloves.

Rubber and cloth are the two main kinds of gloves produced (Melco, 2016). They both have their own benefits and drawbacks respectively. A benefit from rubber gloves is their ability to resist water from coming in contact with a farmer's skin, see part two, (Espasandín-Arias & Goossens, 2014). While cloth gloves can be beneficial because they can draw moisture away from their hands and can be easily washed to be cleaned. Because rubber gloves are usually meant to be disposed of after single use they tend to be cheaper to make and thus cheaper to buy. Yet some rubber gloves can be made thicker to reuse and are slightly more durable (Melco, 2016). Cloth gloves are designed to be washed after being used and last a long time under normal working conditions.

Along with the different materials gloves are made of, there are also different arm lengths. Some gloves are cut off just in front or around the wrist. While others can be up to and over the elbow and everywhere in between (Melco, 2016). The benefits of the shorter gloves is comfort, no bunching around wrist or elbow, and they can be quickly put on or removed. The benefits of the long gloves are more protection, the entire forearm will be covered. All the while there is less of a chance of getting debris in their gloves because the opening is farther away from what you are working with. Farmers can also work in deeper water or mud with the long rubber gloves without getting your hands wet.

When working with smooth items such as hoes and some fruits and vegetables they can be slippery (Food and Agriculture Organization, 2016). A way to help farmer's hold on to the tools is to get gloves with grips (Melco, 2016). Both rubber and cloth gloves can have grips. Rubber gloves will have ridges in the molds to form grips and granular materials can be added to the outside before drying (Melco, 2016). Another option is to make the rubber gloves out of a non-slip rubber (Melco, 2016). Because cloth alone does not provide grip, cloth gloves must be dipped in liquid rubber to be able to grip smooth objects. The rubber used for grips on cloth gloves can either be non-slip smooth rubber or be rigid (Melco, 2016).

Physical Protection

Protection is the main benefit from using gloves. Repetitive motions, such as when pounding grain, can cause irritation to the skin. When collecting firewood the sticks and logs can scratch or cut the skin (Food and Agriculture Organization, 2016). Weeds can be rough and by scratching their hands many times they can become cut and sore (Espasandín-Arias & Goossens, 2014). By lifting and pulling heavy items the top layer of your skin will separate from the next, causing a blister, by wearing gloves they now will prevent blistering because the glove will act as the top layer of skin and prevent the actual skin from separating (Schaffner, 2013). Manure has a lot of bacteria in it which are harmful if they are swallow, so keeping them away from the hands used to eat with is very beneficial (Furlong, et al., 2015). If farmers are working with firewood or in construction the cloth gloves will work better because they are more durable (Food and Agriculture Organization, 2016). The disposable rubber gloves would be the worst to use in this scenario because they are so thin, stick to jobs were the main goals are to keep hands dry and dirt free when using disposable rubber gloves.

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Cholesky decomposition

1 Properties and structure of the algorithm

1.1 General description

The Cholesky decomposition algorithm was first proposed by Andre-Louis Cholesky (October 15, 1875 - August 31, 1918) at the end of the First World War shortly before he was killed in battle. He was a French military officer and mathematician. The idea of this algorithm was published in 1924 by his fellow officer and, later, was used by Banachiewicz in 1938 [7]. In the Russian mathematical literature, the Cholesky decomposition is also known as the square-root method [1-3] due to the square root operations used in this decomposition and not used in Gaussian elimination.

Originally, the Cholesky decomposition was used only for dense real symmetric positive definite matrices. At present, the application of this decomposition is much wider. For example, it can also be employed for the case of Hermitian matrices. In order to increase the computing performance, its block versions are often applied.

In the case of sparse matrices, the Cholesky decomposition is also widely used as the main stage of a direct method for solving linear systems. In order to reduce the memory requirements and the profile of the matrix, special reordering strategies are applied to minimize the number of arithmetic operations. A number of reordering strategies are used to identify the independent matrix blocks for parallel computing systems.

1.2 Mathematical description

Input data: a symmetric positive definite matrix A whose elements are denoted by aij).

Output data: the lower triangular matrix L whose elements are denoted by lij).