2- to 20-year myelomeningocele follow-up outcomes from a referral center in Southern Iran: the Shiraz experience.

BACKGROUND: The current convention for treatment of children with myelomeningocele (MMC) is timely surgical intervention combined with long-term follow-up by a multidisciplinary specialized team. This study aims to investigate the outcomes of MMC patients treated at Namazi Hospital. METHODS: All children presenting to Namazi Hospital with myelomeningocele between May 2001 and August 2020 were eligible for this study. For those with a documented telephone number, follow-up phone surveys with the patient's caregivers, on top of the review of the medical documents were carried out to assess mortality, morbidities, and the functional outcome of the care provided to them. RESULTS: A total of 125 patients were studied (62 females). All of the patients were followed up for a mean duration of 6.28 years (range 1-23 years). The majority were located in the lumbosacral area. All of the patients underwent postnatal surgical intervention for MMC in Namazi Hospital. Mean age at surgery was 9.51 days. There were statistically significant differences between urinary and bowel incontinence and presence of scoliosis, MMT grading of the lower limbs, school attendance, number of readmissions, and requirement of laminectomy at the initial surgical intervention. CONCLUSIONS: This study is the first to characterize the long-term outcomes of MMC patients in Iran. This study illustrates that there is a great need for improved access to and coordination of care in antenatal, perioperative, and long-term stages to improve morbidity and mortality.

Strictly conformal transformation optics for directivity enhancement and unidirectional cloaking of a cylindrical wire antenna.

Using conformal transformation optics, a cylindrical shell made of an isotropic refractive index material is designed to improve the directivity of a wire antenna while making it unidirectionally invisible. If the incident wave comes from a specific direction, it is guided around the wire. Furthermore, when an electrical current is used to excite the wire, the dielectric shell transforms the radiated wave into two lateral beams, improving directivity. The refractive index of the dielectric shell is calculated using the transformation optics recipe after establishing a closed-form conformal mapping between an annulus and a circle with a slit. The refractive index is then modified and discretized using a hexagonal lattice. Ray-tracing and full-wave simulations with COMSOL Multiphysics are used to validate the functionality of the proposed shell.

H-plane horn antenna with enhanced directivity using conformal transformation optics.

Conformal transformation optics is employed to enhance an H-plane horn's directivity by designing a graded-index all-dielectric lens. The transformation is applied so that the phase error at the aperture is gradually eliminated inside the lens, leading to a low-profile high-gain lens antenna. The physical space shape is modified such that singular index values are avoided, and the optical path inside the lens is rescaled to eliminate superluminal regions. A prototype of the lens is fabricated using three-dimensional printing. The measurement results show that the realized gain of an H-plane horn antenna can be improved by 1.5-2.4 dB compared to a reference H-plane horn.

Directivity enhancement of a cylindrical wire antenna by a graded index dielectric shell designed using strictly conformal transformation optics.

A transformation-optical method is presented to enhance the directivity of a cylindrical wire antenna by using an all-dielectric graded index medium. The strictly conformal mapping between two doubly connected virtual and physical domains is established numerically. Multiple directive beams are produced, providing directive emission. The state-of-the-art optical path rescaling method is employed to mitigate the superluminal regions. The resulting transformation medium is all-dielectric and nondispersive, which can provide broadband functionality and facilitate the realization of the device using available fabrication technologies. The realization of the device is demonstrated by dielectric perforation based on the effective medium theory. The device's functionality is verified by carrying out both ray-tracing and full-wave simulations using finite-element-based software COMSOL Multiphysics.

Controlling refractive index of transformation-optics devices via optical path rescaling.

We present a general method of designing optical devices based on optical conformal mapping and rescaling the optical path along a given bunch of rays. It provides devices with the same functionality as those based purely on conformal mapping, but enables to manipulate the refractive index to a great extent-for instance, eliminate superluminal regions of space as well as reduce the refractive index in other regions significantly. The method is illustrated in two examples, a waveguide coupler and a plasmonic bump cloak, and numerical simulations confirm its functionality.

Reflectionless compact nonmagnetic optical waveguide coupler design based on transformation optics.

The design of an optical waveguide coupler has several challenges, such as reflection losses at the interfaces of the coupler, material complexity for optical applications, and the coupling between arbitrary materials at the input and the output of the coupler. In this paper, for the first time to the best of our knowledge, we propose a solution to overcome the above difficulties. For this purpose, we introduce an auxiliary transformation function and an impedance scaling function. The auxiliary function specifies the matched dielectric materials at the input and output interfaces of the coupler, and the scaling function suppresses the reflections and makes the material nonmagnetic for transverse magnetic (TM) polarization. As a result, an optical waveguide coupler is designed that can ideally couple two waveguides with arbitrary dielectric materials and arbitrary cross sections using a nonmagnetic material. Validation of the design method is done by using COMSOL Multiphysics.