Efficient fiber-coupled single-photon source based on quantum dots in a photonic-crystal waveguide.

Many photonic quantum information processing applications would benefit from a high brightness, fiber-coupled source of triggered single photons. Here, we present a fiber-coupled photonic-crystal waveguide single-photon source relying on evanescent coupling of the light field from a tapered out-coupler to an optical fiber. A two-step approach is taken where the performance of the tapered out-coupler is recorded first on an independent device containing an on-chip reflector. Reflection measurements establish that the chip-to-fiber coupling efficiency exceeds 80 %. The detailed characterization of a high-efficiency photonic-crystal waveguide extended with a tapered out-coupling section is then performed. The corresponding overall single-photon source efficiency is 10.9 % ± 2.3 %, which quantifies the success probability to prepare an exciton in the quantum dot, couple it out as a photon in the waveguide, and subsequently transfer it to the fiber. The applied out-coupling method is robust, stable over time, and broadband over several tens of nanometers, which makes it a highly promising pathway to increase the efficiency and reliability of planar chip-based single-photon sources.

A Psychosocial Approach to Understanding Underground Spaces.

With a growing need for usable land in urban areas, subterranean development has been gaining attention. While construction of large underground complexes is not a new concept, our understanding of various socio-cultural aspects of staying underground is still at a premature stage. With projected emergence of underground built environments, future populations may spend much more of their working, transit, and recreational time in underground spaces. Therefore, it is essential to understand the challenges and advantages that such environments have to improve the future welfare of users of underground spaces. The current paper discusses various psycho-social aspects of underground spaces, the impact they can have on the culture shared among the occupants, and possible solutions to overcome some of these challenges.

Lymphoepithelial carcinoma of the salivary glands.

RATIONALE: Lymphoepithelial carcinoma (LEC) is a rare malignancy with the histopathological feature of undifferentiated carcinoma and an intermixed reactive lymphoplasmacytic infiltration. Although clinically significant because of its malignant nature, it is difficult to make a differential diagnosis by preoperative imaging. Here, we report 3 cases of primary LEC arising in the major salivary glands, which showed unusual imaging features unlike other malignant tumors. PATIENT CONCERNS: Our first case is a 44-year-old man with LEC in the right parotid gland, the second case is a 71-year-old woman with LEC in the right submandibular gland, and the third case is a 35-year-old woman with LEC in the right parotid gland. All of the patients presented with a palpable mass of variable duration. DIAGNOSES: Computed tomography (CT) scans revealed a relatively well-defined, slightly hyperattenuated exophytic solid mass that had homogeneous well-enhanced regions. Ultrasonography (US) in the first 2 cases showed well-defined, hypoechoic solid masses with posterior enhancement. The CT findings seem to be benign tumors, but US features are compatible with highly cellular and hypervascular tumors. INTERVENTIONS: The resection of the involved salivary gland with postoperative radiation therapy was performed. OUTCOMES: There was no evidence of recurrence or metastasis after 5 years in all 3 patients. LESSONS: Understanding these unusual imaging findings may be helpful in detecting LEC, and may also help clinicians provide adequate management to patients, such as surgery with adjuvant radiotherapy, because of its malignant entity.

Magnetite Biomineralization in Magnetospirillum magneticum Is Regulated by a Switch-like Behavior in the HtrA Protease MamE.

Magnetotactic bacteria are aquatic organisms that produce subcellular magnetic particles in order to orient in the earth's geomagnetic field. MamE, a predicted HtrA protease required to produce magnetite crystals in the magnetotactic bacterium Magnetospirillum magneticum AMB-1, was recently shown to promote the proteolytic processing of itself and two other biomineralization factors in vivo Here, we have analyzed the in vivo processing patterns of three proteolytic targets and used this information to reconstitute proteolysis with a purified form of MamE. MamE cleaves a custom peptide substrate with positive cooperativity, and its autoproteolysis can be stimulated with exogenous substrates or peptides that bind to either of its PDZ domains. A misregulated form of the protease that circumvents specific genetic requirements for proteolysis causes biomineralization defects, showing that proper regulation of its activity is required during magnetite biosynthesis in vivo Our results represent the first reconstitution of the proteolytic activity of MamE and show that its behavior is consistent with the previously proposed checkpoint model for biomineralization.

Mitochondrial respiratory complex I deficiency simulating spinal muscular atrophy.

Two female patients with clinical features resembling spinal muscular atrophy were presented. Patient 1 presented with hypotonia and proximal weakness of extremities at age 4 months. Electromyography revealed motor neuronopathy suggestive of spinal muscular atrophy. Patient 2 presented with severe hypotonia, motor weakness, and joint contractures since birth. Muscle biopsy findings were consistent with spinal muscular atrophy. However, deletions in the survival motor neuron gene and the neuronal apoptosis inhibitor protein gene were not found in both patients. They finally manifested clinical features unlike spinal muscular atrophy: epileptic seizure, cardiomyopathy, and spasticity. The clinical course of each patient was not like that of spinal muscular atrophy type I. Mitochondrial respiratory chain complex enzyme activities in cultured skin fibroblasts were measured. Respiratory complex I enzyme activity was decreased, suggestive of isolated complex I deficiency in both patients. In conclusion, in patients who have clinical features resembling spinal muscular atrophy but no deletions in the spinal muscular atrophy gene, the possibility of the mitochondrial respiratory chain complex I deficiency should be considered.