Identification of the three-element windkessel model incorporating a pressure-dependent compliance

A new one-step computational procedure is presented for estimating the parameters of the nonlinear three-element windkessel model of the arterial system incorporating a pressure-dependent compliance. The data required are pulsatile aortic pressure and flow. The basic assumptions are a steady-state periodic regime and a purely elastic compliant element. By stating two conditions, zero mean flow and zero mean power in the compliant element, peripheral and characteristic resistances are determined through simple closed form formulas as functions of mean values of the square of aortic pressure, the square of aortic flow, and the product of aortic pressure with aortic flow. The pressure across as well as the flow through the compliant element can be then obtained so allowing the calculation of volume variation and compliance as functions of pressure. The feasibility of this method is studied by applying it to both simulated and experimental data relative to different circulatory conditions and comparing the results with those obtained by an iterative parameter optimization algorithm and with the actual values when available. The conclusion is that the proposed method appears to be effective in identifying the three-element windkessel even in the case of nonlinear compliance.     

New closed-form expressions for the estimation of arterial windkessel compliance

Despite advances in public health and medical care, chronic suppurative otitis media is still prevalent around the world. It is most common in developing countries and in certain high risk populations in developed nations, as well as among children who have tympanostomy tubes inserted. Since this chronic infection is caused by persistent acute otorrhea, which in turn is usually secondary to acute otitis media, prevention should be directed toward prompt and appropriate treatment of the acute middle-ear infection. Repair of chronic perforations should prevent recurrence, since reinfection is due either to reflux of pathogenic organisms from the nasopharynx into the middle ear, or water contamination from the external canal. Information from epidemiological studies, which show that populations can be categorized into highest, high, low and lowest prevalence, can be helpful in setting national priorities for prevention and treatment.     

沟通在解决体检工作中矛盾的应用

总结了在体检工作中常见的矛盾成因.主要包括医护人员的自身素质和能力差异、体检环境嘈杂以及医护人员与受检者沟通交流不当等方面,认为正确应用沟通方式、改善服务环境和理念有助于融洽医护人员与受检者之间的关系.     

Michel Foucault and the contradictions of modern thought.

The present paper offers a sympathetic yet critical examination of Michel Foucault's (1994) discussion (in the final chapters of his book, The Order of Things: An Archaeology of the Human Sciences) of the contradictions inherent in the self-consciousness of the modern or post-Kantian mind. Foucault's account of the “empirico-transcendental doublet” of modern thought is shown to provide a useful mapping of humanist, anti-humanist, and postmodern responses to the reflexivity of the modern “episteme”. Foucault is criticized for his insufficiently critical treatment of structuralism (an anti-humanist approach). Foucault is also defended against the charge that he undermines his own position through a form of performative self-contradiction. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Objective evaluation of contradictions between clinical and anatomopathological diagnoses

The effect of experimental coarctation of the aorta at a site above the coeliac bifurcation (site of occurance of spontaneous atherosclerotic lesions) in White Carneau pigeons was examined. Cholesterol content of the aorta in the site where spontaneous atherosclerosis usually occurs (coeliac bifurcation = lesion site) was decreased in pigeons with aortic coarctation. On the other hand, in the region proximal to the site of coarctation which is usually free of atherosclerotic events cholesterol accumulation was increased. A decrease in percent composition of oleic acid (the major fatty acid which increases during atherosclerosis) was noted in the lesion site. These studies have shown regional differences in response of aorta to experimental coarctation in spontaneously atherosclerotic-susceptible pigeons and suggest that lowering of blood pressure at lesion site might decrease cholesterol accumulation and perhaps might retard subsequent atherogenic process.     

The therapist of color and the white patient dyad: contradictions and recognitions

The therapist of color and White patient dyad often involves contradictions and recognitions which are acknowledged through the specific processes and dynamics permeating this dyad. The relationship between self and other is frequently mediated through projection and identification. This article examines this unique interracial and interethnic therapeutic dyad emphasizing its clinical implications through the attribution of otherness, the use of colored screen projection, and the significance of power reversal. Special emphasis is given to the prevalent transferential and countertransferential reactions aided by clinical material. It is concluded that this therapeutic dyad provides a model for cross-cultural encounters where the resolution of contradictions can lead to the recognition of paradoxes, the acknowledgment of ambivalence, and the acceptance of disparate parts of the self.     

Patient compliance in general practice. Factors contributing to poor compliance and suggestions for improvement

Patients from a solo general practice were followed up to determine what factors were common to those who were poor compliers. A multiple treatment programme where oral antibiotics were a part of the programme was the most frequent feature of poorly complying patients, especially amongst 0-9 and 30-39-year-olds, and ENT patients of any age. Improvement may be gained by establishing good rapport with patients, ordering a simple treatment programme and avoiding overprescribing for all patients, but especially for those groups of patients who are particularly poor compliers.     

Parent relationships and compliance in cystic fibrosis

BACKGROUND: Olfactory dysfunction is one of the major complaints in patients suffering from allergic rhinitis. Little is known about the onset of hyposmia in seasonal allergy. METHODS: We performed two prospective studies to examine olfactory function in allergic rhinitis using an established (modified CCCRC) test for olfactory threshold, identification and discrimination. RESULTS: In a pilot study the time-course of olfactory function in 14 patients with allergic rhinitis to grass pollen was examined at the beginning of the season. Olfactory function was evaluated birhinal on day 3, 7, 14, and 21 of the season. Preseasonally, all patients were normosmic. There was a significant decrease in threshold and identification between the third and fourteenth day of the season, resulting in a moderate hyposmia in the mean. Hyposmia was not correlated to subjective symptom of nasal blockage. Therefore, a follow-up study was performed on 17 patients and a control group with a similar study design including measurements of nasal volume flow (rhinomanometry) and an inflammatory cell activation marker (ECP) in nasal secretions. The time-course of the olfactory changes was much better correlated to the inflammatory measure than to nasal volume flow. CONCLUSIONS: Patients with allergic rhinitis develop a significant olfactory dysfunction under allergen exposition. Inflammatory dysfunction of the olfactory epithelium seems to be more important than respiratory dysfunction in the pathomechanism of allergic hyposmia.     

Emotion, motivation, and text comprehension: The detection of contradictions in passages.

The authors investigated the effects of experimentally induced mood rates on the identification of contradictions in text passages and ratings of comprehension in 3 experiments. Mood impaired comprehension in college students across a variety of passages, as evidenced by a depressive impairment in contradiction identification and an increased number of false identifications among depressed participants. Additionally, depressed individuals were less accurate in their judgments of passage difficulty. These findings are consistent with the resource allocation model of mood effects, which attributes impaired comprehension to the activation of intrusive, irrelevant thoughts during reading of the passage It is further argued that these results cannot be explained simply by a deficit in motivation of the depressed participants. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Low-pressure hydrocephalic state and viscoelastic alterations in the brain

Most shunt-dependent hydrocephalic patients present with predictable symptoms of headache and mental status changes when their cerebrospinal fluid shunts malfunction. Their intracranial pressure (ICP) is usually high, and they usually respond to routine shunt revision. This report describes 12 shunted patients who were admitted with the full-blown hydrocephalic syndrome but with low to low-normal ICP. All 12 patients had been maintained previously on medium-pressure shunts. Their symptoms included headache, lethargy, obtundation, and cranial neuropathies. At peak symptoms, their ventricular sizes were large (ventricular/biparietal ratio of 0.35 to 0.45) in six and massive (ventricular/biparietal ratio > 0.45) in six and their ICPs ranged from 2.2 to 6.6 mm Hg, with a mean of 4.4 +/- 1.3 mm Hg (+/- standard deviation), i.e., below or well within the pressure range of their shunts. The pressure volume index of three patients at peak symptoms ranged from 39.2 to 48.5 ml, with a mean of 43.9 +/- 4.6 ml, which represents a 190% increase from the predicted normal value. Seven patients failed to improve with multiple shunt revisions, including the use of low-pressure valves. In 11 patients, symptoms and ventriculomegaly were not reversed except with prolonged external ventricular drainage at subzero pressures (mean external ventricular drainage nadir pressure of -5.7 +/- 3.6 mm Hg, for a mean period of 22.2 days). During external ventricular drainage treatment, symptoms correlated only with ventricular size and not with ICP. All 11 were subsequently treated successfully with a new medium- or low-pressure shunt. One patient was treated successfully with prolonged shunt pumping. We postulate that: 1) the development of this low-pressure hydrocephalic state is related to alteration of the viscoelastic modulus of the brain, secondary to expulsion of extracellular water from the brain parenchyma, and to structural changes in brain tissues due to prolonged overstretching; 2) certain patients are susceptible to developing low-pressure hydrocephalic state because of an innate low brain elasticity due to bioatrophic changes; 3) low-pressure hydrocephalic state symptoms are due not to pressure changes but to brain tissue distortion and cortical ischemia secondary to severe ventricular distortion and elevated radial compressive stresses within the brain; and 4) treatment must be directed toward allowing the entry of water into the brain parenchyma and the restoration of baseline brain viscoelasticity.