The traditional frequency-shift methods for islanding detection of grid-connected PV inverters-the active frequency drift method and the slip-mode frequency-shift method-become ineffective under certain paralleled RLC loads. The automatic phase-shift method is proposed in this paper to alleviate this problem. The method is based on the phase shift of the sinusoidal inverter output current. When the utility malfunctions, the phase-shift algorithm keeps the frequency of the inverter terminal voltage deviating until the protection circuit is triggered. Simulation and experiments are performed for verification.

This is the first multicenter prospective study of outcomes of tibial neurolysis in diabetics with neuropathy and chronic compression of the tibial nerve in the tarsal tunnels. A total of 38 surgeons enrolled 628 patients using the same technique for diagnosis of compression, neurolysis of four medial ankle tunnels, and objective outcomes: ulceration, amputation, and hospitalization for foot infection. Contralateral limb tibial neurolysis occurred in 211 patients for a total of 839 operated limbs. Kaplan-Meier proportional hazards were used for analysis. New ulcerations occurred in 2 (0.2%) of 782 patients with no previous ulceration history, recurrent ulcerations in 2 (3.8%) of 57 patients with a previous ulcer history, and amputations in 1 (0.2%) of 839 at risk limbs. Admission to the hospital for foot infections was 0.6%. In patients with diabetic neuropathy and chronic tibial nerve compression, neurolysis can result in prevention of ulceration and amputation, and decrease in hospitalization for foot infection.

Optical microscopy is an invaluable tool for studies of materials and biological entities. With the current progress in nanotechnology and microbiology imaging tools with ever increasing spatial resolution are required. However, the spatial resolution of the conventional microscopy is limited by the diffraction of light waves to a value of the order of 200 nm. Thus, viruses, proteins, DNA molecules and many other samples are impossible to visualize using a regular microscope. The new ways to overcome this limitation may be based on the concept of superlens introduced by J. Pendry [1]. This concept relies on the use of materials which have negative refractive index in the visible frequency range. Even though superlens imaging has been demonstrated in recent experiments [2], this technique is still limited by the fact that magnification of the planar superlens is equal to 1.In this communication we introduce a new design of the magnifying superlens and demonstrate it in the experiment. Our design has some common features with the recently proposed "optical hyperlens" [3], "metamaterial crystal lens" [4], and the plasmon-assisted microscopy technique [5]. The internal structure of the magnifying superlens is shown in Fig

Predictive ability of a positive Tinel sign over the tibial nerve in the tarsal was evaluated as a prognostic sign in determining sensory outcomes after distal tibial neurolysis in diabetics with chronic nerve compression at this location. Outcomes were evaluated with a visual analog score (VAS) for pain and measurements of the cutaneous pressure threshold/two-point discrimination. A multicenter prospective study enrolled 628 patients who had a positive Tinel sign. Of these patients, 465 (74%) had VAS >5. Each patient had a release of the tarsal tunnel and a neurolysis of the medial and lateral plantar and calcaneal tunnels. Subsequent, contralateral, identical surgery was done in 211 of the patients (152 of which had a VAS >5). Mean VAS score decreased from 8.5 to 2.0 (p <0.001) at 6 months, and remained at this level for 3.5 years. Sensibility improved from a loss of protective sensation to recovery of some two-point discrimination during this same time period. It is concluded that a positive Tinel sign over the tibial nerve at the tarsal tunnel in a diabetic patient with chronic nerve compression at this location predicts significant relief of pain and improvement in plantar sensibility.

Optical microscopy is an invaluable tool for studies of materials and biological entities. With the current progress in nanotechnology and microbiology imaging tools with ever increasing spatial resolution are required. However, the spatial resolution of the conventional microscopy is limited by the diffraction of light waves to a value of the order of 200 nm. Thus, viruses, proteins, DNA molecules and many other samples are impossible to visualize using a regular microscope. The new ways to overcome this limitation may be based on the concept of superlens introduced by J. Pendry [1]. This concept relies on the use of materials which have negative refractive index in the visible frequency range. Even though superlens imaging has been demonstrated in recent experiments [2], this technique is still limited by the fact that magnification of the planar superlens is equal to 1.In this communication we introduce a new design of the magnifying superlens and demonstrate it in the experiment. Our design has some common features with the recently proposed "optical hyperlens" [3], "metamaterial crystal lens" [4], and the plasmon-assisted microscopy technique [5]. The internal structure of the magnifying superlens is shown in Fig