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Minggu, 14 November 2010

Imfulsif


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Imfulsif



"mudah-mudahan kita bisa menjadi anak yang berbakti kepada orang tua...like ohm was said " There is no need a master plan, it's just a simple plan, but it's perfect.." nice quote, perfect to make them proud - amin
~Dhd&Riki~



Impulsivity


Orbitofrontal cortex, part of the prefrontal cortex

Impulsivity (or impulsiveness) is a personality trait characterized by the inclination of an individual to initiate behavior without adequate forethought as to the consequences of their actions, acting on the spur of the moment. Eysenck and Eysenck related impulsivity to risk-taking, lack of planning, and making up one's mind quickly. Impulsivity has been shown to be a major component of various neuropsychiatric disorders such as ADHD, substance abuse disorders and bipolar disorder. Impulsivity has been shown to have a genetic component and may be inheritable. Abnormal patterns of impulsivity may also be an acquired trait as a result of various neurodegenerative diseases, traumatic brain injury (TBI), hypoxic ischemic encephalopathy, intrauterine hypoxia, bacterial or viral infections or neurotoxicity as a result of chemical exposure. The orbitofrontal cortex and right inferior frontal gyrus have been shown to play a part in impulse control.[1][2][3]

As a personality trait, impulsivity is part of normal behavior as it contributes to adaptive functioning. To do something and not be aware, especially for young children, is relatively common. Recent psychological research has suggested that there are various facets of impulsivity.[4] Some researchers have proposed a 3-factor model according to impulsivity; attentional ("getting easily bored"), motor ("going into action") and cognitive ("inability to plan") factors. Recent theories[5] have suggested five separate aspects of impulsivity:[6]

  • Positive urgency; the tendency to act rashly while in a positive mood.
  • Negative urgency; the tendency to act rashly while in a negative mood.
  • Lack of premeditation; the inability to anticipate the future consequences of actions.
  • Lack of perseverance; the inability to follow through on a task
  • Sensation-seeking; the experience of positive feelings towards risky actions.

Psychometric tests for impulsivity

  • Lifetime History of Impulsive Behaviors; a self-report questionnaire of the lifetime prevalence of impulsive behavior.[7]
  • UPPS Impulsive Behavior Scale (Whiteside and Lynam; 2001); a 45-item self-report questionnaire which distinguishes four facets of impulsivity: urgency, lack of premeditation, lack of perseverance, and sensation-seeking. It is scored on a 4-point scale from Strongly Agree to Strongly Disagree.[8]
    • UPPS-P Impulsive Behavior Scale (UPPS-P); a revised version of the UPPS is a 59-item self-report questionnaire that adds an additional factor, "positive urgency".[9]
    • UPPS-R Interview (UPPS-R); Semi-structured interview format for UPPS-P Impulsive Behavior Scale.
  • Barratt Impulsiveness Scale; a 30-item self-report questionnaire.[10]

References

  1. ^ Corsini, Raymond Joseph, 1999, The Dictionary of Psychology, Psychology Press, ISBN 158391028X, p. 476.
  2. ^ Berlin HA, Rolls ET, Kischka U. Impulsivity, time perception, emotion and reinforcement sensitivity in patients with orbitofrontal cortex lesions. Brain. 2004 May;127(Pt 5):1108-26. Epub 2004 Feb 25. PMID 14985269
  3. ^ Salmond CH, Menon DK, Chatfield DA, Pickard JD, Sahakian BJ. Deficits in decision-making in head injury survivors.J Neurotrauma. 2005 Jun;22(6):613-22. PMID 15941371
  4. ^ Varieties of impulsivity, J.L. Evenden, Psychopharmacology, 1999, Volume 146, Number 4.
  5. ^ Whiteside SP, Lynam DR. The Five Factor Model and impulsivity: Using a structural model of personality to understand impulsivity. Pers Indiv Differ 2001; 30: 669-89.
  6. ^ Emotion-based Dispositions to Rash Action: Positive and Negative Urgency Melissa A. Cyders and Gregory T. Smith. Article
  7. ^ Schmidt CA, Fallon AE, Coccaro EF. Assessment of behavioral and cognitive impulsivity: development and validation of the Lifetime History of Impulsive Behaviors Interview. Psychiatry Res. 2004 Apr 30;126(2):107-21. PMID 15123390
  8. ^ Whiteside SP, Lynam DR. Understanding the role of impulsivity and externalizing psychopathology in alcohol abuse: application of the UPPS impulsive behavior scale.Exp Clin Psychopharmacol. 2003 Aug;11(3):210-7. PMID 12940500
  9. ^ Perales JC, Verdejo-Garcia A, Moya M, Lozano O, Perez-Garcia M. Bright and dark sides of impulsivity: Performance of women with high and low trait impulsivity on neuropsychological tasks. J Clin Exp Neuropsychol. 2009 Apr 8:1-18. [Epub ahead of print] PMID 19358009
  10. ^ Patton JH, Stanford MS, Barratt ES. Factor structure of the Barratt impulsiveness scale. J Clin Psychol. 1995 Nov;51(6):768-74. PMID 8778124


Impulse (physics)

Classical mechanics
History of classical mechanics · Timeline of classical mechanics
[hide]Fundamental concepts
Space · Time · Velocity · Speed · Mass · Acceleration · Gravity · Force · Impulse · Torque / Moment / Couple · Momentum · Angular momentum · Inertia · Moment of inertia · Reference frame · Energy · Kinetic energy · Potential energy · Mechanical work · Virtual work · D'Alembert's principle

In classical mechanics, an impulse is defined as the integral of a force with respect to time. When a force is applied to a rigid body it changes the momentum of that body. A small force applied for a long time can produce the same momentum change as a large force applied briefly, because it is the product of the force and the time for which it is applied that is important. The impulse is equal to the change of momentum.

Contents


Mathematical derivation

Impulse I produced from time t1 to t2 is defined to be[1]

\mathbf{I} = \int_{t_1}^{t_2} \mathbf{F}\, dt

where F is the force applied from t1 to t2.

From Newton's second law, force is related to momentum p by

\mathbf{F} = \frac{d\mathbf{p}}{dt}.

Therefore

\begin{align}  \mathbf{I} &= \int_{t_1}^{t_2} \frac{d\mathbf{p}}{dt}\, dt \\  &= \int_{t_1}^{t_2} d\mathbf{p} \\  &= \Delta \mathbf{p}, \end{align}

where Δp is the change in momentum from time t1 to t2. This is often called the impulse-momentum theorem.[2]

As a result, an impulse may also be regarded as the change in momentum of an object to which a force is applied. The impulse may be expressed in a simpler form when both the force and the mass are constant:

\mathbf{I} = \mathbf{F}\,\Delta t = m \,\Delta \mathbf{v} = \Delta\mathbf{p}

where

F is the constant total net force applied,
Δt is the time interval over which the force is applied,
m is the constant mass of the object,
Δv is the change in velocity produced by the force in the considered time interval, and
m Δv = Δ(mv) is the change in linear momentum.

It is often the case that not just one but both of these two quantities vary.

In the technical sense, impulse is a physical quantity, not an event or force. The term "impulse" is also used to refer to a fast-acting force. This type of impulse is often idealized so that the change in momentum produced by the force happens with no change in time. This sort of change is a step change, and is not physically possible. This is a useful model for computing the effects of ideal collisions (such as in game physics engines).

Impulse has the same units (in the International System of Units, kg·m/s = N·s) and dimensions (MLT−1) as momentum.

Impulse can be calculated using the equation

\mathbf{F}\,\Delta t = \Delta  p = mv_1 - mv_0 \,

where

F is the constant total net force applied,
t is the time interval over which the force is applied,
m is the constant mass of the object,
v1 is the final velocity of the object at the end of the time interval, and
v0 is the initial velocity of the object when the time interval begins.

See also

Notes

  1. ^ Hibbeler, Russell C. (2010), Engineering Mechanics, 12th edition, Pearson Prentice Hall, p. 222, ISBN 0-13-607791-9
  2. ^ See, for example, section 9.2, page 257, of Serway (2004).

Bibliography

  • Serway, Raymond A.; Jewett, John W. (2004). Physics for Scientists and Engineers (6th ed. ed.). Brooks/Cole. ISBN 0-534-40842-7.
  • Tipler, Paul (2004). Physics for Scientists and Engineers: Mechanics, Oscillations and Waves, Thermodynamics (5th ed. ed.). W. H. Freeman. ISBN 0-7167-0809-4.

External links

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