How could mental states affect illness and disease?

Although large bodies of research and clinical practice exist for each of these domains, those which assume the causal efficacy of mental states (psychotherapy and psychosomatic medicine) do not fit comfortably into the reductionist, mater-ialist paradigm which currently predominates in Western philosophy and science.

For example, according to Churchland (1988) all descriptions of or theories about human nature based on conscious experience may be thought of as prescientific forms of 'folk psychology' which are destined to be replaced by some future, advanced neurophysiology. In short, all descriptions of mind or conscious experi-ence will turn out to be descriptions of states of the brain. If so, all claims about mental causation would turn out to be 'prescientific' claims about physical causation and the clinical consequence might be that psychotherapy will even-tually be replaced by some advanced form of physical medicine. While confidence in the eventual success of reductionism might be premature (see the discussion of reductionism above), competition between mental and physical accounts has been very apparent in some therapeutic domains, for example in psychiatry and psychosomatic medicine (reviewed by McMahon and Sheikh, 1989).

McMahon and Sheikh point out that nineteenth-century physicians recognized the existence of 'nervous' disorders (headache, chronic fatigue, dyspepsia, etc.) for which no known structural defect could be found, but they took it for granted that the body was a machine governed by mechanistic laws on which the mind could have no influence. Consequently, somatic complaints without a discernible structural basis were frequently classified as 'imaginary'. Freud's account of conversion hysteria and its treatment gradually led to a change of medical opinion. As Freud noted, 'a disturbance that can be set right by means of psychic influences can itself have been nothing else than psychical' (quoted in Ferenczi et al., 1921: 11). By the 1920s, belief in psychogenesis was widespread and was thought by its proponents to herald the dawn of a new holistic medicine. The Journal Psychosomatic Medicine was founded in 1939, and by 1942 a chapter devoted to psychosomatic medicine had appeared in Osler's standard medical textbook Principles and Practice of Medicine.

However, this early enthusiasm did not fulfil its promise. As McMahon and Sheikh point out, there continued to be a mismatch between clinical observation and acceptable causal explanation. Freud himself took the view that the leap from 'a mental to a somatic innervation' (which takes place in hysteria) 'can never be fully comprehensible to us' (Freud, 1968 [1909]: 17). One response to this in subsequent theories of medicine was to treat conscious states as mere correlates of brain states; only the latter were thought to be the actual (physical) causes of somatic disorders (e.g. Troland, 1932). Another response was to redefine con-scious states in behavioural terms (e.g. Sheehan, 1943). Occasionally, conditions thought to be examples of mental causation were dramatically shown to result from physical causes. For example, for many years patients with acute or chronic respiratory failure had been differentiated into 'fighters' (who battled to stay alive) and 'nonfighters' (who floated away gently, without apparent distress). Subsequently it was shown that fighters had normal pressure of carbon dioxide (Pco₂) in the blood, whereas nonfighters had been given oxygen at high Pco₂ levels and were narcotized by carbon dioxide consequently they were underventilating and died quietly, often while being given high levels of oxygen (Donald, 1972: 318-319).

While belief in psychogenesis and psychosomatic disorders within medicine

persisted, from the 1970s onwards psychological factors are given less promin-ence in medical textbooks (McMahon and Sheikh, 1989). A similar dilution of the causal role of mind in physiological disorders occurs over this period in the standard Diagnostic and Statistical Manual of Mental Disorders (DSM) published by the American Psychiatric Association. For example, DSM II, pub-lished in 1968, refers specifically to a category of 'psychophysiologic disorders'; in DSM-III-R, published in 1987, this category disappears.

Question 1 :-  A boat is rowed at a velocity of 20 km/hour across a river. The velocity of stream is 8 km/hour. Determine the resultant velocity of the boat.

Solution:

 Taking downstream direction as x and direction across the river as y, it is given that 

Vx = 8 km/hour Vy = 20 km/hour

 The resultant velocity

 V=√(8²+20²) =21.54 km/hour 

α = tan-¹ Vy/Vx= tan-¹ 20/8 

=68.20°

Question 2:- The guy wire of the electrical pole shown in Fig. 1.9(a) makes 60° to the horizontal and is carrying a force of 60 kN. Find the horizontal and vertical components of the force.

Solution: 

Figure (b) shows the resolution of force 

F = 20 kN 

into its components in horizontal and vertical components. 

From the figure it is clear that 

Fx =F cos 60° =20 cos 60° =10 kN (to the left)

 Fy= F sin 60°  =20 sin 60° = 17.32 kN (downward)

 Introduction to Mechanics of Solids

The state of rest & the state of motion of the bodies under the action of different forces has engaged the attention of mathematicians and scientists for many centuries.  The branch of physical science that deal with the state of rest (or) the state of motion of bodies is termed as mechanics. Starting from the analysis of rigid bodies under gravitational force and application of simple forces the mechanics has grown into the analysis of complex structures like multistorey buildings, aircrafts, space crafts and robotics under complex system of forces like dynamic forces, atmospheric forces and temperature forces.

Archemedes (287-212 BC), Galileo (1564-1642), Sir Issac Newton (1642-1727) and Einstein

(1878-1955) have contributed a lot to the development of mechanics. Contributions by Varignon,

Euler, and D. Alemberts are also substantial. The mechanics developed by these researchers may

be grouped as

(i) Classical mechanics/Newtonian mechanics

(ii) Relativistic mechanics

(iii) Quantum mechanics/Wave mechanics.

Sir Issac Newton, the principal architect of mechanics, consolidated the philosophy and experimental findings developed around the state of rest and state of motion of the bodies and put-forth them in the form of three laws of motion as well as the law of gravitation. The mechanics based on these laws is called Classical mechanics or New-tonian mechanics.

Albert Einstein proved that New-tonian mechanics fails to explain the behaviour of high speed (speed of light) bodies. He put-forth the theory of Relativistic mechanics.

Schrödinger (1887-1961) and Broglie (1892-1965) showed that New-tonian mechanics fails to explain the behaviour of particles when atomic distances are concerned. They put-forth the theory of Quantum mechanics.

Engineers are keen to use the laws of mechanics to actual field problems. Application of laws of mechanics to field problems is termed as Engineering mechanics. For all the problems between atomic distances to high speed distances there are various engineering problems for which Newtonian mechanics has stood the test of time and hence is the mechanics used by engineers.

The various bodies on which engineers are interested to apply laws of mechanics may be classified as

(i) Solids and

(ii) Fluids.

The bodies which do not change their shape or size appreciably when the forces are applied are termed as Solids while the bodies which change their shape or size appreciably even when small forces are applied are termed as Fluids. Stone, steel, concrete etc. are the example of solids while water, gases are the examples of fluids.

 BASIC TERMINOLOGIES IN MECHANICS

The following are the terms basic to the study of mechanics, which should be understood clearly.

Mass

The quantity of the matter possessed by a body is called mass. The mass of a body will not change unless the body is damaged and part of it is physically separated. If the body is taken out in a space craft, the mass will not change but its weight may change due to the change in gravitational force. The body may even become weightless when gravitational force vanishes but the mass remain the same.

Time

The time is the measure of succession of events. The successive event selected is the rotation of earth about its own axis and this is called a day. To have convenient units for various activities, a day is divided into 24 hours, an hour into 60 minutes and a minute into 60 seconds. Clocks are the instruments developed to measure time. To overcome difficulties due to irregularities in the earths rotation, the unit of time is taken as second which is defined as the duration of 9192631770 period of radiation of the cesium-133 atom.

Space

The geometric region in which study of body is involved is called space. A point in the space may be referred with respect to a predetermined point by a set of linear and angular measurements. The reference point is called the origin and the set of measurements as coordinates. If the coordinates involved are only in mutually perpendicular directions, they are known as cartesian coordination. If the coordinates involve angles as well as the distances, it is termed as Polar Coordinate System.

Length

It is a concept to measure linear distances. The diameter of a cylinder may be 300 mm, the height of a building may be 15 m, the distance between two cities may be 400 km.

Actually metre is the unit of length. However depending upon the sizes involved micro, milli or kilo metre units are used for measurements. A metre is defined as length of the standard bar of platinum-iradium kept at the International Bureau of weights and measures. To overcome the difficulties of accessibility and reproduction now metre is defined as 1690763.73 wavelength of krypton-86 atom.

Continuum

A body consists of several matters. It is a well known fact that each particle can be subdivided into molecules, atoms and electrons. It is not possible to solve any engineering problem by treating a body as conglomeration of such discrete particles. The body is assumed to be a continuous distribution of matter. In other words the body is treated as continuum.

Rigid Body

A body is said to be rigid, if the relative positions of any two particles do not change under the action of the forces acting on it. In Fig. 1.1 (a), point A and B are the original positions in a body. After the application of forces F1, F2, F3, the body takes the position as shown in Fig. 1.1(b). A' and B' are the new positions of A and B. If the body is treated as rigid, the relative position of A'B' and AB are the same i.e.

A'B' = AB

Many engineering problems can be solved by assuming bodies rigid

Particle

A particle may be defined as an object which has only mass and no size. Theoretically speaking such a body cannot exist. However in dealing with problems involving distances considerably larger compared to the size of the body, the body may be treated as a particle, without sacrificing accuracy.

For example:

A bomber aeroplane is a particle for a gunner operating from the ground.

A ship in mid sea is a particle in the study of its relative motion from a control tower.

In the study of movement of the earth in celestial sphere, earth is treated as a particle.

Force

Force is an important term used in solid mechanics. Newton's first law states that everybody continues in its state of rest or of uniform motion in a straight line unless it is compelled by an external agency acting on it. This leads to the definition of force as force is an external agency which changes or tends to change the state of rest or uniform linear motion of the body'. Magnitude of force is defined by Newton's second law. It states that the rate of change of momentum of a body is directly proportional to the impressed force and it takes place in the direction of the force acting on it. Noting that rate of change of velocity is acceleration, and the product of mass and velocity is momentum we can derive expression for the force as given below:

From Newton's second law of motion 

Force= rate of change of momentum 

         =rate of change of (mass x velocity)

पाइल नींव संरचना का वह हिस्सा है जिसका उपयोग संरचना के भार को जमीन की सतह से कुछ गहराई पर स्थित मजबूत वाली जमीन तक ले जाने और भार को स्थानांतरित करने के लिए किया जाता है।

पाइलिंग तकनीक से तात्पर्य नींव के पाइल लगाने के लिए उपयोग की जाने वाली विधियों से है, जो ऊर्ध्वाधर संरचनात्मक तत्व हैं जिनका उपयोग इमारतों, पुलों और अन्य संरचनाओं को सहारा देने के लिए किया जाता है।

पाइल लगाने की तकनीकें निम्नलिखित हैं:

A. संचालित पाइल (विस्थापन पाइल): इन पाइलो को पाइल का उपयोग करके जमीन में ठोक कर या हाइड्रोलिक हथौड़ा द्वारा स्थापित किया जाता है

B. बोर पाइल्स (गैर-विस्थापन पाइल्स): ये पाइल्स जमीन में छेद करके और इसे कंक्रीट या अन्य सहायक सामग्री से भरकर बनाए जाते हैं।

A. पाइल ड्राइविंग विधियाँ (विस्थापन पाइल)

पाइल ड्राइविंग के तरीकों को निम्नानुसार वर्गीकृत किया जा सकता है:

a. वजन/हथौड़ा  गिराना (प्रभाव हथौड़े)

b. कंपन (कंपन हथौड़े)

c. जैकिंग

d. जेटिंग

e. विस्फोट

हथौड़ों को आम तौर पर दो समूहों में विभाजित किया जाता है

1. प्रभाव

2. कम्पायमान

1. प्रभाव हथौड़ों को भाप, हवा या डीजल द्वारा मैन्युअल रूप से या स्वचालित रूप से उठाया जा सकता है और यह एकल या दोहरे कार्य  वाले भी हो सकते हैं।

2. कंपन हथौड़ा एक मशीन है जिसका उपयोग पाइल  पर उच्च आवृत्ति कंपन लगा  करके जमीन में पाइल  को धसाने  के लिए किया जाता है।

ड्रॉप हैमर/हथौड़ों

ड्रॉप हैमर सबसे सरल और सबसे पुराना प्रकार का इम्पैक्ट हैमर है। लगभग पाइल के वजन के बराबर वजन वाले हथौड़े को गाइड में उचित ऊंचाई पर उठाया जाता है और पाइल के सिर पर प्रहार करने के लिए छोड़ा जाता है।

ड्रॉप हथौड़ों के दो मुख्य प्रकार हैं:

1. एकल-कार्य  हथौड़ा

2. डबल-कार्य  हथौड़ा

1.एकल-कार्य  हथौड़ा

यह हथौड़ा प्रकार रैम को ऊपर उठाने के लिए भाप या संपीड़ित हवा के दबाव का उपयोग करता है, फिर स्वचालित रूप से दबाव को छोड़ देता है जिससे रैम स्वतंत्र रूप से नीचे गिरता है और ड्राइव कैप पर प्रहार करता है।

2.डबल-एक्टिंग हथौड़ा

भाप या संपीड़ित हवा का उपयोग स्ट्रोक के नीचे वाले भाग पर रैम को अतिरिक्त ऊर्जा प्रदान करने के लिए भी किया जाता है, नीचे के स्ट्रोक पर दबाव और कम स्ट्रोक दूरी के संयोजन के परिणामस्वरूप परिचालन दर सामान्यतः 90 से 150 वार प्रति मिनट होती है।

कंपन द्वारा पाइल लगाना 

कंपन हथौड़े का कार्य सामान्यतः विद्धुत शक्ति या हाइड्रॉलिक शक्ति का प्रयोग करके किया जाता है । कंपन की तीव्रता इतनी होनी चाहिए की पाइल की सतह को तोड़ सके । कंपन विधि का प्रयोग रेतीली एवं बजरी वाले सतह के लिए अधिक उपयुक्त होता है ।    

B फ्रेंकी पाइल्स (संचालित कास्ट-इन-सीटू)

निर्माण क्रम

ट्यूब की स्थिति और आवरण के तल पर जलरोधी बजरी प्लग का निर्माण, जिससे मिट्टी और/या पानी इसमें प्रवेश न कर सके।

आंतरिक हथौड़े का उपयोग करके प्लग पर नीचे से  चलाने से आवरण पार्श्व विस्थापन द्वारा मिट्टी की सतह को संपीड़ित कर देता है।

पाइल  की लगाने मे  गहराई से  प्लग को बाहर निकालने और पाइल को गहराई मे डाल कर कास्ट-इन-सिटू के  आधार के निर्माण के लिए सूखी कंक्रीट को डाल  कर  करना चाहिए ।

कंक्रीटिंग चरण को करने से पहले सुदृढीकरण/प्रबलित करना  चाहिए ।

शाफ्ट की कंक्रीटिंग।

ड्राइविंग ट्यूब को निकालना और पुनर्प्राप्ति।

लाभ

1. पाइल  की लंबाई आसानी से समायोज्य है

2. विस्तृत/बड़ा आधार के कारण उत्कृष्ट समाधान है ।

3. समान भार के लिए अन्य पाइल  प्रकारों की तुलना में कम सामग्री का उपयोग करना ।

नुकसान

1. अपेक्षाकृत महंगा होना । 

2. लगाने मे धीमी समय लगाना 

3. बहुत शोर वाली स्थापना होना 

4. बड़े अवरोधों के कारण ड्रिलिंग नहीं की जा सकती।