1) Which of the following is an essential element of persuasive messages?A) TrustB) MarketingC) SalesD) ValueE) Action
Which of the following is an essential element of persuasive messages?
Answer:
Answer:
A
Explanation: A)Whether you're trying to convince people to help fund your new business via Kickstarter, asking your boss for a raise, or promoting a concert, trust is an essential element of persuasion. If people don't believe in you, they won't believe in what you're promoting.
Which of the following best describes the goals of persuasion?
Answer:
Answer:
B
Explanation: B)Persuasion-the attempt to change an audience's attitudes, beliefs, or actions. Because persuasive messages ask audiences to give something of value (money in exchange for a product, for example)or take substantial action (such as changing a corporate policy), they are more challenging to write than routine messages.
Which of the following is true for persuasive messages?
Answer:
Answer:
C
Explanation: C)In today's information-saturated business environment, having a great idea or a great product is no longer enough. Every day, untold numbers of good ideas go unnoticed and good products go unsold simply because the messages meant to promote them aren't compelling enough to be heard above the competitive noise.
Steps in planning successful persuasive messages include what?
Answer:
Messages that try to convince the audience to consider then purchase products and services are called what?
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When planning a persuasive message,which of the following is the least important consideration when considering the audience?
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The age,gender,income,education and other quantifiable characteristic of people are called what?
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Personality,attitudes,lifestyle and other psychological characteristics of an audience are known as what?
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Before attempting to change someone's attitudes,beliefs or actions,what must be understood?
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To encourage a positive response to your persuasive message,which of the following would be most effective?
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Which of the following would not encourage a positive response to your message?
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Explaining your reasons and building interest before asking for a decision or action is an example of what?
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Which of the following has the greatest impact on the effectiveness of persuasive messages in the workplace?
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Which of the following is least likely to encourage a positive response to a persuasive message?
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To convince a skeptical audience,which of the following should be done?
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Emphasizing beliefs,attitudes and background experiences is one way to establish what?
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When completing a persuasive message,which of the following helps determine the distribution process?
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During the completion process for the persuasive message,which of the following matches the purpose and organization to the needs of the audience?
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Persuasive messages are often unexpected and unwelcome.
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Most persuasive messages use an indirect approach.
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Inhaltsverzeichnis
- 9.2 Soil permeability relates to soil texture and structure
- Permeability variation according to soil texture
- Permeability variation according to soil structure
- 9.4 Measurement of soil permeability in the laboratory
- 9.5 Measurement of soil permeability in the field
- The visual evaluation of the permeability rate of soil horizons
- A simple field test for estimating soil permeability
- A more precise field test for measuring permeability rates
- 9.6 Determining coefficients of permeability
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Soil permeability is the property of the soil to transmit water and air and is one of the most important qualities to consider for fish culture. |
A pond built in impermeable soil will lose little water through seepage. | ||
The more permeable the soil, the greater the seepage. Some soil is so permeable and seepage so great that it is not possible to build a pond without special construction techniques. You will learn about these techniques in a later volume in this series. |
Soils are generally made up of layers and soil quality often varies greatly from one layer to another. Before pond construction, it is important to determine the relative position of the permeable and impermeable layers. The design of a pond should be planned to avoid having a permeable layer at the bottom to prevent excessive water loss into the subsoil by seepage. |
The dikes of the pond should be built with soil which will ensure a good water retention. Again, soil quality will have to be checked with this in mind.
Many factors affect soil permeability. Sometimes they are extremely localized, such as cracks and holes, and it is difficult to calculate representative values of permeability from actual measurements. A good study of soil profiles provides an essential check on such measurements. Observations on soil texture, structure, consistency, colour/mottling, layering, visible pores and depth to impermeable layers such as bedrock and claypan* form the basis for deciding if permeability measurements are likely to be representative.
Note: you have already learned that soil is made up of a number of horizons, each of them usually having different physical and chemical properties. To determine the permeability of soil as a whole, each horizon should be studied separately.
9.2 Soil permeability relates to soil texture and structure
The size of the soil pores is of great importance with regard to the rate of infiltration (movement of water into the soil) and to the rate of percolation (movement of water through the soil). Pore size and the number of pores closely relate to soil texture and structure, and also influence soil permeability.
Permeability variation according to soil texture
Usually, the finer the soil texture, the slower the permeability, as shown below:
Soil | Texture | Permeability |
Clayey soils | Fine | From very slow to very rapid |
Loamy soils | Moderately fine | |
Moderately coarse | ||
Sandy soils | Coarse |
Example
Average permeability for different soil textures in cm/hour
Sand | 5.0 |
Sandy loam | 2.5 |
Loam | 1.3 |
Clay loam | 0.8 |
Silty clay | 0.25 |
Clay | 0.05 |
Permeability variation according to soil structure
Structure may greatly modify the permeability rates shown above, as follows:
From very slow to very rapid | ||
1 This may vary according to the degree to which the structure is developed.
It is common practice to alter the soil structure to reduce permeability, for example, in irrigated agriculture through the puddling of rice fields and in civil engineering through the mechanical compaction* of earthen dams. Similar practices may be applied to fish-ponds to reduce water seepage.
Permeability is commonly measured in terms of the rate of water flow through the soil in a given period of time. It is usually expressed either as a permeability rate in centimetres per hour (cm/h), millimetres per hour (mm/h), or centimetres per day (cm/d), or as a coefficient of permeability k in metres per second (m/s) or in centimetres per second (cm/s). | Example |
For agriculture and conservation uses, soil permeability classes are based on permeability rates, and for civil engineering, soil permeability classes are based on the coefficient of permeability (see Tables 15 and 16).
For fish culture, two methods are generally used to determine soil permeability. They are:
- The coefficient of permeability;
- The seepage rate.
For the siting of ponds and the construction of dikes, the coefficient of permeability is generally used to qualify the suitability of a particular soil horizon:
- Dikes without any impermeable clay core may be built from soils having a coefficient of permeability less than
K = 1 x 10-4 m/s; - Pond bottoms may be built into soils having a coefficient of permeability less than K = 5 x 10-6 m/s.
For pond management, the seepage rate is generally used:
- In commercial pond culture, an average seepage rate of 1 to 2 cm/d is considered acceptable, but corrective measures should be taken to reduce soil permeability when higher values exist, particularly when they reach 10 cm/d or more.
9.4 Measurement of soil permeability in the laboratory
When you take an undisturbed sample to a testing laboratory, to measure permeability, a column of soil is placed under specific conditions such as water saturation and constant head of water. The result will be given to you either as a permeability rate (see Table 15), or as a coefficient of permeability (see Table 16).
TABLE 15
1 Saturated samples under a constant water head of 1.27 cm | TABLE 16
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9.5 Measurement of soil permeability in the field
To measure soil permeability in the field, you can use one of the following tests:
- The visual evaluation of the permeability rate of soil horizons;
- A simple field test for estimating soil permeability;
- A more precise field test measuring permeability rates.
The visual evaluation of the permeability rate of soil horizons
The permeability of individual soil horizons may be evaluated by the visual study of particular soil characteristics which have been shown by soil scientists to be closely related to permeability classes. The most significant factor in evaluating permeability is structure: its type, grade, and aggregation characteristics, such as the relationship between the length of horizontal and vertical axes of the aggregates and the direction and amount of overlap.
Although neither soil texture nor colour mottling alone are reliable clues, these soil properties may help to estimate permeability when considered together with the structural characteristics. To evaluate visually the permeability of soil horizons:
- Examine a fresh soil profile in an open pit;
- Determine the soil horizons present;
- Using
Table 17A
, evaluate the permeability class to which each horizon belongs, carefully studying the structural characteristics of the soil; - Confirm your results through the other soil properties shown in
Table 17B;
- Ranges of permeability rates may then be found in
Table 15.
TABLE 17A
Visual indicators of permeability: structural characteristics of soil
TABLE 17 B
Visual Indicators of permeability: texture, physical behaviour and colour of soil
A simple field test for estimating soil permeability
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A more precise field test for measuring permeability rates
Note: you could also use the visual method (see Tables 17A and 17B) to estimate permeability. |
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Note: water seeps into the soil both horizontally and vertically, but you need only be concerned with the vertical water seepage because this is mainly what happens in ponds. |
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- At first, the water will seep down rather quickly, and you will have to refill as it disappears. When the pores of the soil are full of water, seepage will slow down. You are then ready to measure the permeability of the soil horizon at the bottom of the hole;
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Permeability rate in mm/h | Suitability of horizon for a pond bottom |
Slower than 2 | Acceptable seepage: soil suitable |
2-5 | Fast seepage: soil suitable ONLY if seepage due to soil structure which will disappear when pond is filled |
5-20 | Excessive seepage: soil unsuitable unless seepage can be reduced as described below |
If the permeability rate is faster than 5 mm/h, this may be owing to a strongly developed structure in the soil. In such cases, you try to reduce the permeability rate by destroying the structure, as follows:
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- If this new permeability rate does not exceed 4 mm/h, you may consider this soil horizon as suitable for a pond bottom. However, the entire bottom of the pond will have to be puddled before filling it with water;
- If this new permeability rate exceeds 4 mm/h, this may be owing to the presence of a permeable soil horizon under the horizon you have tested. Such a permeable layer is often found between layers of soil which are semi- permeable or even impermeable;
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Note: when building your pond, you do not necessarily need to remove a shallow permeable layer if there is a deeper layer of soil which is not permeable and will serve to hold the water. You must, however, build the pond dikes down to the deeper non-permeable layer to form an enclosed basin and to avoid horizontal water seepage (see Section 9.0).
9.6 Determining coefficients of permeability
To obtain a more accurate measurement of soil permeability, you can perform the following test in the field which will give you a value for the coefficient of permeability:
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Example |
- Measure exactly the total depth of the hole (H) and its diameter (D).
Express all measurements in metres
(m): for example
H = 1.15 m and D = 12 cm or 0.12 m
- For each of the above two consecutive measurements of time/distance, calculate the
coefficient of permeability K
using the following formula:
K= (D÷2) x In (h2÷ h2) / 2 (t2- t1)
where (D ÷ 2) is the radius of the hole or
half its diameter in metres; In refers to the Napierian or natural logarithm;
h2 and h2 are the two consecutive depths of water in metres, h2 at the start and h2 at the end of the time interval;
(t2 - t1 ) expresses the time interval between two consecutive measurements, in seconds;
Note: the h-values may be readily calculated as the differences between the total depth of the hole H and the successive P values. Be careful to express all the measurements in metres and seconds so as to obtain K in m/s.
- Now compare your K values (in m/s) with those in Table 16.
Example
If (D ÷ 2) = 0.12 m ÷ 2 = 0.06 m and H = 1.15 m, calculations of the various K values are made progressively according to the formula (see Table 18).
Note: for obtaining the natural logarithm of (h2 ÷ h2), you will have to use either a logarithmic table or a pocket calculator.
Remember that 10 - 6 = 0.000001 and 6.8 x 10-6 = 0.0000068, the negative exponent of 10 reflecting the decimal place to be given to the multiplicant.
If you wish to compare a K value (m/s) with permeability rates (cm/day), multiply K by 8 640 000 or 864 x 104 such as for example:
K = 1 x 10-5 m/s = 86.4 cm/day
TABLE 18
Successive steps for the calculation of coefficients of permeability on the basis of field
measurements
(for a test hole with H = 1.15 m and D = 0.12 m)
NOTE: The formula for calculating coefficients of permeability is K = [(D ÷ 2) x In (h2 ÷ h2)] / 2 (t2 - t1)
or A ÷ B (see Section 9.6).