Model-based vs. model-free visual servoing: A Performance evaluation in microsystems

In this paper, model-based and model-free image based visual servoing (VS) approaches are implemented on a microassembly workstation, and their regulation and tracking performances are evaluated. A precise image based VS relies on computation of the image jacobian. In the model-based visual servoing, the image Jacobian is computed via calibrating the optical system. Precisely calibrated model based VS promises better positioning and tracking performance than the model-free approach. However, in the model-free approach, optical system calibration is not required due to the dynamic Jacobian estimation, thus it has the advantage of adapting to the different operating modes

Effect of Metabolic Rate on Mitochondrial Efficiency during Exercise in Human Skeletal Muscle in vivo

Introduction: Recent evidence in isolated mitochondria and permeabilized muscle fibers in ex vivo using simultaneous measurements of O2 consumption and ATP production suggest that mitochondrial efficiency provides an additional mechanism to fine-tune oxidative phosphorylation rate to ATP demand in skeletal muscle. However, in the absence of a direct measurement of both VO2 and ATP synthesis from the same region of the contracting muscle, whether this mechanism plays a role in the skeletal muscle in vivo is still unknown. Purpose: Using a noninvasive approach combining phosphorus and proton magnetic resonance spectroscopy (31P/1H-MRS), the present study aimed to determine skeletal muscle ATP synthesis rate and muscle VO2 during a graded dynamic plantar flexion exercise to determine mitochondrial efficiency in contracting skeletal muscle contraction. Method: To measure mitochondrial efficiency under physiological conditions, we applied a recently developed methodological approach in ex vivo to human gastrocnemius muscle in vivo using 31P/1H-MRS noninvasive techniques. We conducted a series of constant workloads and ischemic protocols to assess oxidative ATP synthesis (ATPox) rate and Myoglobin-derived oxygen consumption (Mb-derived VO2). Specifically, during two separate visits, in 12 healthy, sedentary to recreationally active young male adults, we determined the ATPox rate by measuring the initial phosphocreatine (PCr) resynthesis rate during recovery and Mb-derived VO2 during 30 seconds of occlusion at the end of each given exercise workload. Results: The calculated mean power output during constant load performed by all subjects increased linearly at each incremental workload for both 1H and 31P visits. The mean percent coefficient of variation (CV%) at all exercise workloads (25% of WRmax= 6.0 ± 6.6, 50% of WRmax = 4.5 ± 2.7, 75% of WRmax = 4.9 ± 3.9, 100% = 7.0 ± 4.5) demonstrated high reliability and reproductivity in power output between each visit. The mean concentration of PCr consumption at the steady state remained constant between 25 and 50% of WRmax (28.6 ± 1.7 and 28.2 ± 1.4, respectively) but increased linearly beyond 50% of WRmax (75% = 22.9 ± 1.4 mM and 100%= 18.0 ± 1.4 mM, respectively). Mean intracellular pH was not significantly different between 25 and 50% of submaximal workloads (6.98 ± 0.02 and 6.97 ± 0.02, respectively). Intracellular pH dropped to 6.94 ± 0.02 during the last min of exercise at 75% of WRmax and further decreased at 100% of WRmax, (6.87 ± 0.03). The percentage of Mb oxygenation level and partial pressure of oxygen(PO2) at the steady state exhibited a consistent linear decline with increasing workload. Accordingly, a distinct and strong linear relationship was found between the MbO2 and workload (r2 = 0.71). Similarly, as the exercise workload increased, the ATPox synthesis rate also increased linearly throughout all exercise workloads (r2 = 0.45). In contrast, there was no significant change in Mb-derived VO2 with increased exercise workload averaged over a 30 s (r2 = 0.36) and 10 s time frame (r2 = 0.17). As a result, there was no significant correlation between ATPox synthesis rate and Mb-derived VO2 across exercise intensities. However, at rest, the P/O ratio in the gastrocnemius muscle was 1.95 ± 0.68, consistent with theoretical values and previous studies in mice. Conclusion: Despite the decrease in MbO2 (%), Mb-derived VO2 from both 30 and 10 s averages remained relatively constant during the ischemic protocol, likely due to O2 availability limitation induced by the prolonged occlusion and the slow time-resolution for measuring the dMb signal, which precluded the quantification of mitochondrial efficiency during exercise. However, mitochondrial efficiency calculated at rest was in agreement with previously documented values using other methodologies and thus can provide an additional parameter to more comprehensively evaluate mitochondrial function in vivo

Anatomical and visual outcomes of ranibizumab injections in retinal pigment epithelium tears

ABSTRACT Purpose: To report the anatomical and visual results in patients diagnosed as having retinal pigment epithelium (RPE) tears after receiving ranibizumab injections. Methods: Eyes diagnosed as having RPE tears with a minimum 6-month follow-up were retrospectively evaluated. Each eye was treated with at least three doses of ranibizumab at monthly intervals. Best-corrected visual acuity (BCVA), anterior segment findings, intraocular pressure, and fundus examination results were evaluated during control visits. Color fundus photography, fundus fluorescein angiographies, fundus autofluorescence, and spectral domain optical coherence tomography (SD-OCT) images were obtained. The height of pigment epithelial detachment (PED) was measured by SD-OCT. Results: Twelve eyes with RPE tears were studied. Nine eyes (75%) developed RPE tears during ranibizumab injections for choroidal neovascularization (eight eyes with vascularized PED and one eye with choroidal osteoma), and tears occurred in three eyes before any injections. The median number of ranibizumab injections after diagnosis of RPE tears was 3 (min 2, max 5). In the most recent follow-up visit, there was no statistically significant correlation between the grade of RPE and logMAR of BCVA (p>0.05, r=0.112). Eight of twelve eyes had PED, and seven of these had irregular PED contours before injection therapy. The mean PED height was 447 ± 122 µm. Conclusions: In this series, RPE tears developed mostly after intravitreal anti-VEGF injections for vascularized PED. Increased vertical height and irregular contours of the PEDs can be risk factors for the formation of RPE tears. The continuation of anti-VEGF therapy after tear formation is beneficial for vision improvement in eyes with RPE tears

Primary cutaneous adenoid cystic carcinoma of the eyelid and literature review

ABSTRACTPrimary cutaneous adenoid cystic carcinoma (PCACC) is a rare malignant epithelial tumor most commonly observed in the scalp and skin of the chest and originating from the palpebral portion of the lacrimal gland in the orbit. Here we describe the diagnosis and treatment of a rare case of PCACC in an eye of a 52-year-old male. The patient presented with a mass lesion of the right lower eyelid. During incisional biopsy, lack of encapsulation and a secretion pattern different to that of chalazion was observed, which differentiated the lesion from chalazion. Pathological analysis revealed the diagnosis of PCACC. This case highlights the importance of careful inspection for macroscopic differentiation of PCACC from chalazion after initial surgery and pathological evaluation of all surgically removed mass lesions for accurate diagnosis and treatment

Macular Findings Obtained by Spectral Domain Optical Coherence Tomography in Retinopathy of Prematurity

Purpose. To examine the macular findings obtained with spectral domain optical coherence tomography (SD OCT) in infants with retinopathy of prematurity (ROP). Materials and Methods. The macular SD OCT images of 190 premature infants were analyzed. Data regarding central foveal thickness (CFT), cystoid macular edema (CME), and cyst grading were compared. The relationships of CFT with gestational age and birth weight were investigated. Results. The results were obtained from 358 eyes of 179 infants (81 females and 98 males) of a mean gestational age of 30.9±2.7 weeks and a mean birth weight of 1609±477 g. ROP was diagnosed in 126 eyes and CME in 139 eyes. A significantly greater percentage of eyes with ROP were found to have CME (54%) compared to eyes without ROP (31%; P=0.001). The incidence of CME was 46.3% for stage 1 ROP, 57.1% for stage 2, and 87.5% for stage 3. There was a weakly inverse correlation between CFT, gestational age, and birth weight (P=0.025, r=-0.227; P=0.002, r=-0.182, resp., Spearman correlation test). Conclusions. High-quality SD OCT images can be obtained from premature infants using the iVue system. Severity and frequency of CME in premature infants increase as stage of ROP increases

A comparative study of conventional visual servoing schemes in microsystem applications

This paper presents an experimental comparison of conventional (calibrated and uncalibrated) image based visual servoing methods in various microsystem applications. Both visual servoing techniques were tested on a microassembly workstation, and their regulation and tracking performances are evaluated. Calibrated visual servoing demands the optical system calibration for the image Jacobian estimation and if a precise optical system calibration is done, it ensures a better accuracy, precision and settling time compared with the uncalibrated approach. On the other hand, in the uncalibrated approach, optical system calibration is not required and since the Jacobian is estimated dynamically, it is more flexible

Choroidal Thickness in Patients with Mild Cognitive Impairment and Alzheimer’s Type Dementia

Aim. To asses both choroidal thickness differences among Alzheimer’s type dementia (ATD) patients, mild cognitive impairment (MCI) patients, and healthy control (C) subjects and choroidal thickness relationships with cognitive performance. Methods. A total of 246 eyes of 123 people (41 ATD, 38 MCI, and 44 healthy C subjects) were included in this study. Complete ophthalmological and neurological examination was performed in all subjects. Choroidal thicknesses (CT) were measured at seven locations: the fovea, 500-1500-3000 μm temporal and 500-1500-3000 μm nasal to the fovea by enhanced depth imaging optical coherence tomography (EDI-OCT). Detailed neurological examination including mini mental state examination (MMSE) test which evaluates the cognitive function was applied to all participants. Results. The ages and genders of all participants were similar in all groups. Compared with healthy C subjects, the CT measurements at all regions were significantly thinner both in patients with ATD and in patients with MCI than in healthy C subjects (p<0.05). The MMSE scores were significantly different among ATD patients, MCI patients, and healthy C subjects. They were 19.3±1.8, 24.8±0.9, and 27.6±1.2 in ATD, MCI, and healthy controls, respectively (p<0.001). There were also significant correlation between MMSE score and choroidal thickness at each location (p<0.05). Conclusions. CT was reduced in ATD patients and MCI patients. Since vascular structures were affected in ATD patients and MCI patients, they had thin CT. Besides CT was correlated with degree of cognitive impairment. Therefore CT may be a new biomarker in diagnosis and follow-up of MCI and ATD patients

Evaluation of the effect of mitral stenosis severity on the left ventricular systolic function using isovolumic myocardial acceleration

Background: Isovolumic acceleration (IVA) is a new tissue Doppler parameter in the as­sessment of systolic function of both left and right ventricles. It remains unaffected with the changes in pre- and after-load within the physiological range. The aim of our study was to assess the effect of mitral stenosis degree, which is determined by echocardiography, on the left ventricular (LV) function using IVA. Methods: A total number of 62 patients with mitral stenosis (MS) and 32 healthy controls were examined. The severity of MS (mild, moderate, and severe) was determined on the basis of mitral valve area (MVA) and the mean diastolic mitral gradient findings. The peak myocardial velocities during isovolumic contraction, systole, early diastole and late diastole were measured by using tissue Doppler imaging (TDI). Results: All TDI-derived global LV basal wall systolic (peak myocardial isovolumic contra­ction velocity, peak myocardial systolic velocity and IVA), and diastolic velocities (peak early and late diastolic velocities) were significantly decreased in the patients with MS, compared to the healthy patients (p &lt; 0.001, for all). However, IVA was not different when the degree of MS was evaluated (p = 0.114). In addition, IVA was not correlated with the MVA (r = 0.185, p = 0.150). Conclusions: Left ventricular function is impaired in patients with MS regardless of the severity of the disease.