Optically induced forces and torques:Interactions between nanoparticles in a laser beam

Distinctive optical forces and torques arise between nanoparticles irradiated by intense laser radiation. These forces, associated with a pairwise process of stimulated scattering, prove to enable the possibility of producing significant modifications to both the form and magnitude of interparticle forces, with additional contributions arising in the case of dipolar materials. Moreover, such forces have the capacity to generate unusual patterns of nanoscale response, entirely controlled by the input beam characteristics- principally the optical frequency, intensity, and polarization. Based on quantum electrodynamical theory, a general result is secured for the laser-induced force under arbitrary conditions, incorporating both static and dynamic coupling mechanisms. Specific features of the results are identified for pairs of particles with prolate cylindrical symmetry, e.g., carbon nanotubes, where it is shown that the laser-induced forces and torques are sensitive functions of the pair spacing and orientation, and the laser beam geometry; significantly, they can be either repulsive or attractive according to conditions. For nanoparticles trapped in a Laguerre-Gaussian laser beam the results also reveal additional and highly distinctive torques that suggest further possibilities for nanomanipulation with light. The paper concludes with a discussion on several potential applications of such forces. © 2005 The American Physical Society

Analysis of the Sphingolipid Profile in Regenerating Skeletal Muscle of a Murine Model of Type 1 Diabetes Mellitus

Type 1 Diabetes Mellitus (T1DM) is an autoimmune disease that destroys the pancreatic β-cells. Poor skeletal muscle regeneration and atrophy are associated with T1DM, termed diabetic myopathy, which includes an accumulation of muscle lipids. Sphingolipids are a class of lipids that display powerful cellular effects and are implicated in roles in skeletal muscle regeneration and diabetic myopathy. However, sphingolipids have yet to be quantified in regenerating skeletal muscle of animal models of T1DM. This project aimed to examine the sphingolipid profile of wild type (WT) and Ins2Akita+/- (Akita) mice following cardiotoxin(CTX)-induced injury. 22 WT and 20 Akita mice received an injection of CTX in their quadriceps, gastrocnemius-plantaris-soleus complex, and tibialis anterior (TA) muscles. Muscle samples were collected at 1, 3, 5, and 7 days post-injury. TAs of WT and Akita mice were cryosectioned and stained with BODIPY 493/503 to visualize lipids. Total lipids were elevated in the injured Akita mice (p=0.044). Liquid Chromatography-Mass Spectrometry was used to assess sphingolipid content of injured and uninjured quadriceps of both WT and Akita mice. Analysis revealed that C22:0 (p=0.003) and C24:0 (p=0.003) ceramides and ceramide-1-phosphate (C1P; p\u3c0.001), were elevated in the Akita mice, whereas C24:1 (p\u3c0.001) ceramide content was reduced in the Akita mice. Finally, SDS-PAGE and Western blot analysis of the uninjured and injured GPS complexes in WT and Akita mice was done to quantify CerK protein expression. Analysis revealed no statistically significant differences at any time-point post-injury (p\u3e0.05). This represents the first analysis of sphingolipids in regenerating skeletal muscle in a model of T1DM. Quantification of ceramides and C1P revealed significant differences between WT and Akita mice indicating a potential role in diabetic myopathy. Despite increased concentrations of some ceramides and C1P, there were no significant differences in CerK expression, suggesting that an alternative route of ceramide phosphorylation likely exists, however, no candidate mechanism has been identified. Future studies will be needed to examine the role of various sphingolipids in skeletal muscle regeneration and diabetic myopathy

Stakeholders' perspectives towards the use of the Comprehensive Health Assessment Program (CHAP) for adults with intellectual disabilities in Manitoba

Background: No standardized tool is used in Canada for comprehensive health assessments of adults with intellectual disabilities. This study was conducted to determine the feasibility of implementing the Comprehensive Health Assessment Program (CHAP) in Manitoba, Canada. Method: This was a qualitative study using a purposive sample of physicians, nurse practitioners, support workers and families. Data were collected through individual interviews and focus groups and were analysed using content analysis. Results: Use of the CHAP was perceived as beneficial for persons with intellectual disabilities. Improved continuity of care was of the reported benefits. Six barriers for the future implementation of the CHAP were identified including the time required to complete the CHAP, and the perceived lack of physicians’ willingness to do comprehensive assessments. Conclusion: The future implementation of the CHAP was strongly supported. For its successful implementation, training of healthcare professionals and support staff and change in regulations and policies were recommended