Wave dynamics on toroidal surface

Wave dynamics on curved surfaces has attracted growing attention due to its close resemblance to the warped space time governed by general relativity. It also opens up opportunities for designing functional optical devices such as geodesic lenses. In this work we study the wave dynamics on the surface of a torus, a shape of considerable interest due to its nontrivial topology. Governed by the conservation of angular momentum, light propagates on the torus in two different types of modes: one is able to twist around and sweep through the whole surface of the torus; the other is confined within a certain angular range along the torus latitude direction. The confined mode exhibits an interesting self focusing or imaging behavior, which, similar to a geometric lens, shows no dependence of wavelength and thus suffers no chromatic aberration. By changing the geometric parameters of the torus, both the focusing point and the focusing distance can be controlled. Our work provides a new approach to manipulation of light propagation on a curved surface under the conservation of angular momentum

Extremely discrepant mutation spectrum of SLC26A4 between Chinese patients with isolated Mondini deformity and enlarged vestibular aqueduct

<p>Abstract</p> <p>Background</p> <p>Mutations in <it>SLC26A4 </it>cause Pendred syndrome (hearing loss with goiter) or DFNB4 (non-syndromic hearing loss with inner ear malformation, such as enlarged vestibular aqueduct or Mondini deformity). The relationship between mutations in <it>SLC26A4 </it>and Mondini deformity without enlarged vestibular aqueduct has not been studied in any Chinese deaf population. The purpose of this study was to assess whether mutations in the <it>SLC26A4 </it>gene cause Mondini deformity without an enlarged vestibular aqueduct (isolated Mondini deformity) in a Chinese population.</p> <p>Methods</p> <p>In total, 144 patients with sensorineural hearing loss were included and subjected to high-resolution temporal bone CT. Among them, 28 patients with isolated Mondini dysplasia (MD group), 50 patients with enlarged vestibular aqueduct with Mondini dysplasia (EVA with MD group), 50 patients with enlarged vestibular aqueduct without Mondini dysplasia (EVA group), and 16 patients with other types of inner ear malformations (IEM group) were identified. The coding exons of <it>SLC26A4 </it>were analyzed in all subjects.</p> <p>Results</p> <p>DNA sequence analysis of <it>SLC26A4 </it>was performed in all 144 patients. In the different groups, the detection rate of the <it>SLC26A4 </it>mutation differed. In the isolated MD group, only one single allelic mutation in <it>SLC26A4 </it>was found in one patient (1/28, 3.6%). In the EVA with MD group, biallelic and monoallelic <it>SLC26A4 </it>mutations were identified in 46 patients (46/50, 92.0%) and three patients (3/50, 6.0%), respectively. Also, in the EVA group, biallelic and monoallelic <it>SLC26A4 </it>mutations were identified in 46 patients (46/50, 92.0%) and three patients (3/50, 6.0%), respectively. These percentages were identical to those in the EVA plus MD group. Only two patients carried monoallelic mutations of the <it>SLC26A4 </it>gene in the IEM group (2/16, 12.5%). There were significant differences in the frequency of <it>SLC26A4 </it>mutation among the groups (P < 0.001). The detection rate of <it>SLC26A4 </it>mutation in the isolated MD group was significantly lower than in the EVA group (with or without MD; P < 0.001), and there was no significant difference in the detection rate of <it>SLC26A4 </it>between the MD group and IEM group (P > 0.5).</p> <p>Conclusion</p> <p>Although mutations in the <it>SLC26A4 </it>gene were frequently found in Chinese EVA patients with and without MD, there was no evidence to show a relationship between isolated MD and the <it>SLC26A4 </it>gene in the Chinese population examined. Hearing impairment in patients with isolated MD may be caused by factors other than mutations in the <it>SLC26A4 </it>gene.</p

Molecular Etiology of Hearing Impairment in Inner Mongolia: mutations in SLC26A4 gene and relevant phenotype analysis

<p>Abstract</p> <p>Background</p> <p>The molecular etiology of hearing impairment in Chinese has not been thoroughly investigated. Study of <it>GJB2 </it>gene revealed that 30.4% of the patients with hearing loss in Inner Mongolia carried <it>GJB2 </it>mutations. The <it>SLC26A4 </it>gene mutations and relevant phenotype are analyzed in this study.</p> <p>Methods</p> <p>One hundred and thirty-five deaf patients were included. The coding exons of <it>SLC26A4 </it>gene were sequence analyzed in 111 patients, not including 22 patients carrying bi-allelic <it>GJB2 </it>mutations or one patient carrying a known <it>GJB2 </it>dominant mutation as well as one patient with <it>mtDNA </it>1555A>G mutation. All patients with <it>SLC26A4 </it>mutations or variants were subjected to high resolution temporal bone CT scan and those with confirmed enlarged vestibular aqueduct and/or other inner ear malformation were then given further ultrasound scan of thyroid and thyroid hormone assays.</p> <p>Results</p> <p>Twenty-six patients (19.26%, 26/135) were found carrying <it>SLC26A4 </it>mutation. Among them, 17 patients with bi-allelic <it>SLC26A4 </it>mutations were all confirmed to have EVA or other inner ear malformation by CT scan. Nine patients were heterozygous for one <it>SLC26A4 </it>mutation, including 3 confirmed to be EVA or EVA and Mondini dysplasia by CT scan. The most common mutation, IVS7-2A>G, accounted for 58.14% (25/43) of all <it>SLC26A4 </it>mutant alleles. The shape and function of thyroid were confirmed to be normal by thyroid ultrasound scan and thyroid hormone assays in 19 of the 20 patients with EVA or other inner ear malformation except one who had cystoid change in the right side of thyroid. No Pendred syndrome was diagnosed.</p> <p>Conclusion</p> <p>In Inner Mongolia, China, mutations in <it>SLC26A4 </it>gene account for about 12.6% (17/135) of the patients with hearing loss. Together with <it>GJB2 </it>(23/135), <it>SLC26A4 </it>are the two most commonly mutated genes causing deafness in this region. Pendred syndrome is not detected in this deaf population. We established a new strategy that detects <it>SLC26A4 </it>mutations prior to the temporal bone CT scan to find EVA and inner ear malformation patients. This model has a unique advantage in epidemiologic study of large deaf population.</p

Comprehensive molecular etiology analysis of nonsyndromic hearing impairment from typical areas in China

<p>Abstract</p> <p>Background</p> <p>Every year, 30,000 babies are born with congenital hearing impairment in China. The molecular etiology of hearing impairment in the Chinese population has not been investigated thoroughly. To provide appropriate genetic testing and counseling to families, we performed a comprehensive investigation of the molecular etiology of nonsyndromic deafness in two typical areas from northern and southern China.</p> <p>Methods</p> <p>A total of 284 unrelated school children with hearing loss who attended special education schools in China were enrolled in this study, 134 from Chifeng City in Inner Mongolia and the remaining 150 from Nangtong City in JiangSu Province. Screening was performed for <it>GJB2</it>, <it>GJB3</it>, <it>GJB6</it>, <it>SLC26A4</it>, <it>12S rRNA</it>, <it>and tRNA</it>^{<it>ser</it>(<it>UCN</it>)}genes in this population. All patients with <it>SLC26A4 </it>mutations or variants were subjected to high-resolution temporal bone CT scan to verify the enlarged vestibular aqueduct.</p> <p>Results</p> <p>Mutations in the <it>GJB2 </it>gene accounted for 18.31% of the patients with nonsyndromic hearing loss, 1555A>G mutation in mitochondrial DNA accounted for 1.76%, and <it>SLC26A4 </it>mutations accounted for 13.73%. Almost 50% of the patients with nonsyndromic hearing loss in these typical Chinese areas carried <it>GJB2 </it>or <it>SLC26A4 </it>mutations. No significant differences in mutation spectrum or prevalence of <it>GJB2 </it>and <it>SLC26A4 </it>were found between the two areas.</p> <p>Conclusion</p> <p>In this Chinese population, 54.93% of cases with hearing loss were related to genetic factors. The <it>GJB2 </it>gene accounted for the etiology in about 18.31% of the patients with hearing loss, <it>SLC26A4 </it>accounted for about 13.73%, and <it>mtDNA </it>1555A>G mutation accounted for 1.76%. Mutations in <it>GJB3, GJB6</it>, and <it>mtDNA tRNA</it>^{<it>ser</it>(<it>UCN</it>)}were not common in this Chinese cohort. Conventionally, screening is performed for <it>GJB2</it>, <it>SLC26A4</it>, and mitochondrial <it>12S rRNA </it>in the Chinese deaf population.</p

Pancharatnam-Berry Phase Induced Spin-Selective Transmission in Herringbone Dielectric Metamaterials

A dielectric metamaterial approach for achieving spin‐selective transmission of electromagnetic waves is proposed. The design is based on spin‐controlled constructive or destructive interference between propagating phase and Pancharatnam–Berry phase. The dielectric metamaterial, consisting of monolithic silicon herringbone structures, exhibits a broadband operation in the terahertz regime

High-Efficiency Asymmetric Transmission of Circularly Polarized THz waves using a Dielectric Herringbone Metasurface

An interesting topic is that of metamaterials imparting chiral responses which invoke a disparity between opposite handednesses of circularly polarised (CP) light. Most chiral metamaterials are either 3D-helical structures [1] or stacked metallic structures with twisted orientations [2]. These structures allow selective transmission of one CP whilst prohibiting or reflecting the other, termed Circular Dichroism. However, for 2D chiral metamaterials, this is not so. Instead, the cross-polarisation conversion of one CP to another is different. The original work in [3] used an anisotropic lossy planar-chiral “fish-scale” structure to exhibit this effect, termed Asymmetric Transmission (AT). However, these responses are small with efficiencies less than 25%. Works to improve efficiency used 3D arrangements. Work in [4] achieved much higher efficiency than for the 2D planar-chiral structures, but due to the metallic construction absorption losses were unavoidable; such losses were given as 37%. Here, we propose a means of achieving AT using a loss-free mechanism at 1THz frequency by constructing Monolithic Herringbone metamaterials from a dielectric medium [5]. This device works by a spin-selective interference of CP light, due to Pancharatnam-Berry (PB) phases, in conjunction with a propagative dynamic phase (Fig. 2) causing constructive interference for TRL and destructive for TLR Jones matrix components. An analytical derivation (Fig. 1a) was found to agree well with numerical simulations (Fig. 1b) for the design. These results indicate a conversion efficiency of LCP to RCP (TRL) exceeding 80%. Fabrication of Intrinsic Silicon was used for the devices (Fig. 2) and THz Time Domain Spectroscopy (THz-TDS) was used to characterise the samples, showing a 60% spin-conversion efficiency (Fig. 3). Such a device is robust and is not easily degraded by errors in fabrication

GJB2 mutation spectrum in 2063 Chinese patients with nonsyndromic hearing impairment

Background: Mutations in GJB2 are the most common molecular defects responsible for autosomal recessive nonsyndromic hearing impairment (NSHI). The mutation spectra of this gene vary among different ethnic groups. Methods: In order to understand the spectrum and frequency of GJB2 mutations in the Chinese population, the coding region of the GJB2 gene from 2063 unrelated patients with NSHI was PCR amplified and sequenced. Results: A total of 23 pathogenic mutations were identified. Among them, five (p.W3X, c.99delT, c.155_c.158delTCTG, c.512_c.513insAACG, and p.Y152X) are novel. Three hundred and seven patients carry two confirmed pathogenic mutations, including 178 homozygotes and 129 compound heterozygotes. One hundred twenty five patients carry only one mutant allele. Thus, GJB2 mutations account for 17.9% of the mutant alleles in 2063 NSHI patients. Overall, 92.6% (684/739) of the pathogenic mutations are frame-shift truncation or nonsense mutations. The four prevalent mutations; c.235delC, c.299_c.300delAT, c.176_c.191del16, and c.35delG, account for 88.0% of all mutantalleles identified. The frequency of GJB2 mutations (alleles) varies from 4% to 30.4% among different regions of China. It also varies among different sub-ethnic groups. Conclusion: In some regions of China, testing of the three most common mutations can identify at least one GJB2 mutant allele in all patients. In other regions such as Tibet, the three most common mutations account for only 16% the GJB2 mutant alleles. Thus, in this region, sequencing of GJB2 would be recommended. In addition, the etiology of more than 80% of the mutant alleles for NSHI in China remains to be identified. Analysis of other NSHI related genes will be necessary