Are there sex differences in pain? For experimentally delivered somatic stimuli, females have lower thresholds, greater ability to discriminate, higher pain ratings, and less tolerance of noxious stimuli than males. These differences, however, are small, exist only for certain forms of stimulation and are affected by many situational variables such as presence of disease, experimental setting, and even nutritive status. For endogenous pains, women report more multiple pains in more body regions than men. With no obvious underlying rationale, some painful (...) diseases are more prevalent among females, others among males and, for many diseases, symptoms differ between females and males. Sex differences in attitudes exist that affect not only reporting, coping, and responses to treatment, but also measurement and treatment. So many variables are operative, however, that the most striking feature of sex differences in reported pain experience is the apparent overall lack of them. On the other hand, deduction from known biological sex differences suggests that these are powerful sex differences in the operation of pain mechanisms. First, the vaginal canal provides an additional route in women for internal trauma and invasion by pathological agents that puts them at greater risk for developing hyperalgesia in multiple body regions. Second, sex differences in temporal patterns are likely to give rise to sex differences in how pain is and stimuli are interpreted, a situation that could lead to a greater variability and wider range of pains without obvious peripheral pathology among females. Third, sex differences in the actions of sex hormones suggest pain-relevant differences in the operation of many neuroactive agents, opiate and nonopiate systems, nerve growth factor, and the sympathetic system. Thus, while inductive analysis of existing data demonstrate more similarities than differences in pain experience between females and males, deductive analysis suggests important operational sex differences in its production. (shrink)

Provides a comprehensive report on the mother-child bond and the emotional effects of and behavioral response to maternal deprivation.

Essence is an interesting and deep concept of the ontology. This paper argues that the essence of object is composed of three connected and different parts. The first is the feature of noumenon contained in the object, such as the mathematical content of the quality and structure of object. By revealing the content, man is able to know some fundamental features of object, and then easily find the orient of the object in the physical world. The second is the inner (...) nature of object, especially the cardinal nature. It, keeping with the traditional cognition, indicates that thought probes deeply into the inner nature of object, and then knows allkinds of mechanisms and functions. The third refers to the relationship between one thing and another. By comprehending the relationship on macro‐ and whole stand, man can recognize the core mechanism of things. Based on above processes, metaphysically the whole knowledge on the essence of object has been finished. In addition the dialectical relations between universality and individuality, absolute idea and relativity are in need of comprehending in practice referring to the essence of things. (shrink)