ABSTRACT
Background: Several manifestations of cutaneous leishmaniasis are related to the host's immune system and the species of parasite. Objective: There have been some studies on the relationship between vitamin D statuses in infectious diseases including cutaneous leishmaniasis. However, the results of these studies have been inconsistent. Materials and Methods: In this cross-sectional study, 147 patients with leishmaniasis were recruited and divided into the following categories: acute cutaneous leishmaniasis (<1 year) (n = 51), chronic cutaneous leishmaniasis (more than 1 year) (n = 26), and leishmaniasis recidivans (the appearance of new papular lesions around a previous scar) (n = 20), and a group of participants without leishmaniasis (n = 50), as a control group. Serum 25-hydroxyvitamin D [25(OH) D] level was analyzed. Result: There were significant differences in serum 25(OH) D between the groups with acute or chronic leishmaniasis and those with recidivans leishmaniasis (P = 0.013 and P = 0.022, respectively). The median serum level of vitamin D in the acute group was 13.7 ng/mL, in the chronic group was 16.05 ng/mL, in the recidivans group was 21.75 ng/mL, and in the control group was 17.97 ng/mL. Conclusion: Higher serum concentrations of 25(OH) vitamin D levels being associated with leishmaniasis recidivans.
ABSTRACT
A new control approach to achieve robust hopping against perturbations in the sagittal plane is presented in this paper. In perturbed hopping, vertical body alignment has a significant role for stability. Our approach is based on the virtual pendulum concept, recently proposed, based on experimental findings in human and animal locomotion. In this concept, the ground reaction forces are pointed to a virtual support point, named virtual pivot point (VPP), during motion. This concept is employed in designing the controller to balance the trunk during the stance phase. New strategies for leg angle and length adjustment besides the virtual pendulum posture control are proposed as a unified controller. This method is investigated by applying it on an extension of the spring loaded inverted pendulum (SLIP) model. Trunk, leg mass and damping are added to the SLIP model in order to make the model more realistic. The stability is analyzed by Poincaré map analysis. With fixed VPP position, stability, disturbance rejection and moderate robustness are achieved, but with a low convergence speed. To improve the performance and attain higher robustness, an event-based control of the VPP position is introduced, using feedback of the system states at apexes. Discrete linear quartic regulator is used to design the feedback controller. Considerable enhancements with respect to stability, convergence speed and robustness against perturbations and parameter changes are achieved.
