Image-free real-time target tracking by single-pixel detection.

Image-based target tracking methods rely on continuous image acquisition and post-processing, which will result in low tracking efficiency. To realize real-time tracking of fast moving objects, we propose an image-free target tracking scheme based on the discrete cosine transform and single-pixel detection. Our method avoids calculating all the phase values, so the number of samples can be greatly reduced. Furthermore, complementary modulation is applied to reduce the measurement noise, and background subtraction is applied to enhance the contrast. The results of simulations and experiments demonstrate that the proposed scheme can accomplish the tracking task in a complex background with a sampling ratio of less than 0.59% of the Nyquist-Shannon criterion, thereby significantly reducing the measurement time. The tracking speed can reach 208 fps at a spatial resolution of 128 × 128 pixels with a tracking error of no more than one pixel. This technique provides a new idea for real-time tracking of fast-moving targets.

[Repair of posterior mitral valve prolapsed: comparative study of three different approaches].

OBJECTIVE: To compared outcomes of robotic mitral valve repair with those of standard sternotomy, and right anterolateral thoracotomy. METHOD: From August 2010 to July 2011, 70 patients with degenerative mitral valve disease and posterior leaflet prolapsed scheduled for elective isolated mitral valve repair were prospectively nonrandomized to undergo mitral valve operation by standard sternotomy (n = 30), right anterolateral thoracotomy (n = 30), or a robotic approach (n = 10). There were 49 male and 21 female patients, aging from 16 to 70 years with a mean of 53.4 years. Outcomes of the three groups were compared. RESULTS: Mitral valve repair was achieved in all patients except 1 patient in the standard group. There were no in-hospital deaths. The median operation time [(300 ± 41) min, (184 ± 20) min and (169 ± 22) min, F = 112.5, P < 0.01], cardiopulmonary bypass time [(139 ± 26) min, (82 ± 20) min and (69 ± 23) min, F = 36.8, P < 0.01], aortic cross-clamping time [(93 ± 23) min, (47 ± 10) min and (38 ± 8) min, F = 75.0, P < 0.01] were longer for robotic than standard sternotomy and right anterolateral thoracotomy. The robotic group had shortest time of mechanical ventilation time [(4.9 ± 2.1) h, (5.3 ± 4.5) h and (14.1 ± 10.2) h, F = 13.2, P < 0.01], ICU time [(15.1 ± 2.1) h, (16.4 ± 5.4) h and (28.7 ± 16.1) h, F = 11.6, P < 0.01], postoperative hospital stay time [(4.6 ± 1.0) d, (5.7 ± 1.7) d and (8.8 ± 5.1) d, F = 8.0, P < 0.01] with the lowest of drainage [(192 ± 200) ml, (215 ± 163) ml and (405 ± 239) ml, F = 7.1, P < 0.01] and ratio of the patients needed blood transfusion (0, 20.0% and 66.7%, χ(2) = 22.7, P < 0.01). Patients were followed up 6 to 17 months, with 100% completed. No patients died during follow-ups, and no moderate or more mitral regurgitation was observed. The robotic group had the shortest time of return to normal activities compared with the other two groups [(2.4 ± 0.7) weeks, (4.2 ± 1.2) weeks and (8.2 ± 1.8) weeks, F = 83.0, P < 0.01]. CONCLUSION: This study shows mitral valve repair via the right anterolateral thoracotomy and a robotic approach is safe and feasible, with good cosmetic results and rapid postoperative recovery, and is worthy of clinical selective application.

[Association between expression of chromogranin A and myocardial fibrosis in patients with dilated cardiomyopathy].

OBJECTIVE: To observe the possible correlation between expression of chromogranin A (CGA) and myocardial fibrosis and investigate the potential role of CGA in the development of myocardial fibrosis in patients with dilated cardiomyopathy (DCM). METHODS: Surgical myocardial specimen from 10 DCM patients underwent successful orthotopic cardiac transplantation, and 3 normal myocardial specimen from brain-dead organ donors were obtained. CGA-mRNA, COLI-mRNA, COLIII-mRNA and ADAMTS-1-mRNA were analyzed by real-time PCR. The location and expression of CGA were assessed by immunohistochemistry(INH)with anti-CGA antibody. The collagen specific picrosirius red staining was applied on transversal myocardial slides and the collagen volume fraction (CVF) was calculated. The correlation between CGA and CVF was analyzed. RESULTS: Cytoplasmic expression of CGA assessed by INH showed large amount of strong positive granules densely arranged in the epicardial and endocardial myocardiocytes in DCM specimen while there was only few sparse granules in the normal myocardium (P < 0.05). CVF was significantly higher in DCM myocardial specimen than that in normal specimen (P < 0.001). CGA-mRNA was significantly correlated with COLI-mRNA (r = 0.729), COLIII-mRNA (r = 0.95) and ADAMTS-1-mRNA (r = 0.665, all P < 0.05). Moreover, collagen deposition location was almost identical with the strong positive expression location of CGA. CONCLUSION: We demonstrated for the first time that the deposition of CGA was related with the myocardial fibrosis in DCM heart, therefore, CGA might play an important role by influencing myocardial remodeling and fibrosis in DCM patients.

Multistep Heterogeneous Nucleation in Binary Mixtures of Charged Colloidal Spheres.

Nucleation plays a decisive role in determining the crystal structure and size distribution; however, understanding of the fundamentals of nucleation is quite limited. In particular, it is unclear whether a nucleus forms spontaneously from solution via a single- or multiple-step process. Here we show how a binary mixture of charged colloidal spheres nucleates heterogeneously on a flat substrate by means of Bragg microscopy, laser diffraction, and laser microscopy. In contrast with the conventional one-step and two-step nucleation mechanisms, a novel pathway of multistep heterogeneous nucleation under certain experimental conditions is highlighted by four steps: initial homogeneous fluid → prenucleation clusters → preordered prenucleation clusters → intermediate ordered phase → final crystal. It is expected that the obtained results would be helpful in rationalizing the rich phase behavior exhibited by the binary mixture systems and in developing better and broadly applicable nucleation models as well as in designing defect-free single-crystal alloys.

Complications after endovascular repair of Stanford type A (ascending) aortic dissection.

Endovascular treatment has emerged as a less traumatic alternative treatment for several diseases of the thoracic aorta. However, the complications of the endovascular management of ascending aortic dissections are still high. We present a case of two iatrogenic complications after endovascular repair (EVAR) of type A (ascending) aortic dissection. Retrograde aortic dissection at the proximal part of the aortic endovascular graft and a guidewire-induced iatrogenic left ventricular pseudoaneurysm were presented in this patient after the stent-grafting procedure. Fourteen months later, surgical replacement of the ascending aorta and proximal arch was performed and the left ventricular pseudoaneurysm was treated successfully by linear closure. The patient recovered uneventfully. Although aortic endovascular grafting is apparently less traumatic, indications and potential complications related to the stent graft should be considered with great care.