A closed-form linear multi-step algorithm for the steady-state response of high-speed flexible mechanisms

Based on the general form of linear multi-step methods, a closed-form algorithm for the steady-state solution of periodically time-dependent vibrating systems—high-speed flexible mechanisms with uniform rotation input can be taken as a special case—is developed. The algorithm is tested by three examples and verified by comparing the computational responses with the previously published experimental results. Besides, the computational results also show that this algorithm, compared with Fourier series method, is of higher accuracy and far higher computational efficiency.     

Structural features of crayfish phasic and tonic neuromuscular terminals

We examined the fine structure of terminals of the phasic and tonic excitatory axon to the crayfish limb extensor muscle. The phasic terminals are known to release 50-100 times more transmitter for a small length of terminal for a single impulse. Phasic terminals labeled with horseradish peroxidase (HRP) were relatively thin and contained a single unbranched mitochondrion; tonic terminals were much thicker, and their varicosities contained several multibranched mitochondria. Tonic terminals devoted a larger proportion of their total volume to mitochondria. The percentage volume of clear synaptic vesicles was slightly higher in phasic axon terminals, but as the tonic axon terminals were fivefold larger in volume, the total synaptic volume is much greater in tonic than phasic terminals. The number of synapses per length of terminal, and the total number of active zones per length of terminal, were greater for tonic terminals, and individual synapses were, on average, slightly larger in surface contact area for tonic terminals. In contrast, individual active zones were, on average, longer in phasic synapses. A higher proportion (50%) of phasic synapses had multiple active zones than was the case for tonic synapses (16%), and pairs of closely spaced active zones were more frequently found on phasic synapses. These findings clearly rule out synapse and active zone number as a factor contributing to higher transmitter output, but suggest that active zone size and synaptic complexity, as evidenced by multiple closely spaced active zones in a single synapse, are likely to play a causal role in the greater transmitter release of the phasic terminal. Even synapse complexity would not be enough to account fully for the large difference in terminal transmitter output, and additional factors may include electrical and biochemical differences.     

Carbamoyl phosphate synthetase: a tunnel runs through it

BACKGROUND: Sensitivity to specific allergens and increased sensitivity to common spasmogens are characteristic features of allergic asthma and are also features demonstrated by tissues passively sensitized with serum from atopic donors, displaying high levels of IgE. It is evident that the specific response to allergen is related to circulating levels of allergen-specific IgE, but it is unclear whether the histamine hypersensitivity is also related to this immunoglobulin. OBJECTIVE: The objective was to deplete IgE in the serum of a donor with high levels of total and allergen-specific IgE and compare specific-allergen sensitivity and sensitivity to histamine in tissues passively sensitized with either the whole serum or the IgE-depleted serum. METHODS: Serum from a Dermatophagoides farinae-sensitive asthmatic (total IgE = 1047 U/mL, D. farinae-specific IgE > 17.5 U/mL) was subjected to an immunomagnetic separation technique to reduce the levels of IgE (total and specific) to below 10 U/mL. Bronchial tissue from six non-atopic donors was then passively sensitized overnight with either the whole serum or IgE-depleted serum and D. farinae and histamine sensitivity were evaluated the next day using standard organ bath techniques. RESULTS: Passive sensitization with the whole serum resulted in the development of sensitivity to D. farinae and increased sensitivity to histamine (750+/-169 mg contraction to 10 U/mL D. farinae, histamine pEC50 5.64+/-0.16 and max. 813+/-109 mg in sensitized vs 37+/-34 mg contraction to 10 U/mL D. farinae histamine pEC50 5.05+/-0.23 and max. 490+/-84 in non-sensitized tissues, P>0.05). Incubation with IgE-depleted serum still produced histamine hypersensitivity (histamine pEC50 5.57+/-0.16 and max. 737+/-70 mg P>0.05), but no significant response to allergen was detected (20+/-13 mg contraction to 10 U/mL D. farinae). CONCLUSION: These results demonstrate, that increased reactivity to histamine and airway contraction to allergen induced by passive sensitization, occur through independent mechanisms and that, unlike allergen-sensitivity, histamine hypersensitivity is caused by a serum factor other than IgE.     

The mediating role of anxiety in self-reported somatic complaints of depressed adolescents

This study examined the mediating role of anxiety in the self-reports of somatic complaints in 96 depressed adolescent inpatients. Sixty-four subjects with major depressive episodes and comorbid anxiety disorders (MDE-A) determined from the Diagnostic Interview for Children and Adolescents--Revised (DICA-R) reported significantly more somatic complaints than 32 adolescents having major depressive episodes without comorbid anxiety (MDE). An analysis of covariance demonstrated that, with anxiety symptoms controlled, MDE and MDE-A groups did not differ significantly in somatic complaints. A hierarchical multiple-regression analysis revealed that, with demographic and anxiety symptoms controlled, depressive symptoms did not contribute to the explanation or prediction of somatic complaints. The results suggest that anxious, but not depressive symptoms, are independently associated with somatic complaints. The results are discussed in light of new affective models of psychopathology.     

Family dysfunction, alexithymia, and client attachment to therapist.

Alexithymia involves problems differentiating affective states such as fear, sadness, or anger; difficulty expressing feelings; and a tendency to rely on external cues rather than internal experience for making decisions. This study examined alexithymia as a possible mediator by which dysfunctional family environment in childhood affects adult clients' attachment relationship to their therapist. Clients (N?=?61) completed measures of dysfunctional family structure (Family Structure Survey), alexithymia (Toronto Alexithymia Scale), and their counseling relationship (Client Attachment to Therapist Scale). Findings suggest that fear of separation was associated with both alexithymia and poor client attachment to therapist. Parent–child role reversal was associated with problems in identifying feelings. Role reversal and marital conflict were both associated with problems in client attachment to therapist. Results suggest that alexithymia may be a significant mediator of the relationship between family dysfunction and client attachment to therapist. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Syntax Channelling and Other Issues affecting Innovation in the Graphical User Interface

Does the modern commercial Graphical User Interface constrain the developer of graphics applications into certain interaction styles? This paper looks at the Microsoft Windows environment as an example, with particular reference to the question of interaction modes, screen real-estate and visual appearance. The concept of syntax channelling is introduced to help analyse the problem of modality, and the question of button-down versus button-up dragging is debated in the context of a range of commercial applications, and possible consequences for upper limb disorder. A Windows application developed by the author involving the implementation of a variety of innovative interfacing techniques is presented.