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Epilepsy surgery success is dependent on accurate localization of the epileptogenic zone. Despite the use of invasive EEG using subdural grids and strips, surgical failures can occur. In this series, we explore the utility of a second evaluation with stereoelectroencephalography in patients whose initial invasive evaluation with subdural grid electrodes was unsuccessful in localizing seizure origin. We conducted a retrospective review of patients who underwent subdural grid evaluation (SDE) at our center and identified patients who underwent a re‐evaluation with stereoelectroencephalography (SEEG). We identified three patients who had both subdural and SEEG electrodes in the region of the identified epileptogenic zone in whom the initial SDE evaluation failed to make the patients seizure‐free. Two of these patients underwent a second resection and became seizure‐free. Stereoelectroencephalography can be useful in the re‐evaluation and re‐operation of patients who previously had surgical failure using SDE.

Stimulated parametric down-conversion is a nonlinear optical process that can be used for phase conjugation and frequency conversion of an optical field. A precise description of the outgoing stimulated field has been developed for the case where the input pump and seed fields are coherent. However, partially coherent beams can have interesting and important characteristics that are absent in coherent beams. One example is the twist phase, a novel optical phase that can appear in partially coherent Gaussian beams and gives rise to a nonzero orbital angular momentum. Here, we consider stimulated down-conversion for partially coherent input fields. As a case study, we use twisted Gaussian Schell-Model beams as the seed and pump beams in stimulated parametric down-conversion. It is shown both theoretically and experimentally that the stimulated idler beam can be written as a twisted Gaussian Schell-Model beam, where the beam parameters are determined entirely by the seed and pump. When the pump beam is coherent, the twist phase of the idler is the conjugate of that of the seed. These results could be useful for the correction of wavefront distortion such as in atmospheric turbulence in optical communication channels, and synthesis of partially coherent beams.

In this Letter, Young’s double-slit experiment with vector vortex beams is investigated. We present the results for various Poincaré–Hopf index beams of this class considering all four major types. Polarization associated morphological changes in the far-field interference pattern are studied both theoretically and experimentally. The Fraunhofer pattern consists of lattices of polarization singularities of the generic type, located on a line, in a direction perpendicular to the slit. The number of linear lattices varies as a function of Poincaré–Hopf index η of the beam that is diffracted, and the number of intensity nulls occurring along the vertical line is equal to |η|.

We demonstrate theoretically and experimentally coherence-induced polarization changes in higher-order vector vortex beams (VVBs) with polarization singularity. The prominent depolarization on decreasing the transverse correlation width in a focused partially coherent VVB provides a means to shape the intensity profile and degree of polarization (DOP) while preserving the polarization distribution. The intensity variation and DOP dip are found to be dependent on the polarization singularity index of the beam. Our results may provide an additional degree of freedom in myriad applications presently projected with VVBs.

Emerging adulthood is a key developmental period of identity (including sexual and romantic identity). Sexual self-image, or the intersection between body image and sexual behaviors/sexuality, has implications for mental health and sexual health at this critical developmental stage. Text messages are a ubiquitous method of communication for emerging adults, and sexting (i.e., text messages with sexualized content) has both positive and negative health and relationship effects. We examine how emerging adult couples use text messages to communicate about their sexual self-image. We analyzed 20 emerging adult couples’ text messages in the first six months of their relationship for themes related to how bodies were discussed in the context of sexual activity. We used both content and tonal qualitative analyses. We found six themes: (1) complimenting, (2) affirming, (3) sharing information, (4) expressing boundaries, (5) asserting agency, and (6) expressing desires. Although the majority of research focused on sexting focuses on risk or negative outcomes, we find that sexting as it relates to bodies can be a source of comfort, affirmation, expression of desires, and boundary setting. Our findings point to opportunities for increasing communication skills to improve sexual health and body empowerment among emerging adults.

Free-space optical communication is hindered by turbulence resulting in spatial modal dispersion of the optical beam. Here we mimic in the laboratory the far-field turbulence effects on entangled photons in the polarization basis. We make use of a diffractive optical element to simulate turbulence distortions and measure the entanglement as a function of the turbulence strength. We show that the standard method of coincidence detection using single-mode-fiber coupling to single-photon counters results in spatial mode dependence of entanglement even though it is not measured with spatial modes. We find that the overall coupling inefficiency of the detected coincidence caused by spatial mode dispersion in free space can be corrected by the use of a multimode fiber. Our results suggest that care is required in the choice of a detection system for free-space quantum communication systems.

This Letter presents the essence of our recent experimental study on generic singularities carrying spatially partially coherent, polychromatic dark hollow beams (PDHBs). To the best of our knowledge, this is the first experimental demonstration of generic singularities-induced wavefront tearing in focused polychromatic beams.

It is shown that the generation of surface plasmons on a metal-dielectric interface, i.e., a Au-double-slit and air interface, appreciably affects the intensity of the diffracted light. With a specific example of Au-double-slit and electro-optic devices before the slits, the spectral switching in the diffracted field with the polychromatic light is shown for the first time, to our knowledge. It is found that at the observation point due to the surface plasmon effect the intensity of the diffracted light periodically increases and decreases with the separation of the double-slit.

Slowing down of light pulses to ∼1.9 mm/s has been obtained theoretically in SBN:75 via degenerate two-wave mixing (TWM) configuration. The optical delay has been tuned by varying the input pulse width & beam crossing angle. At the optimum beam crossing angle (2θ ∼ 10◦), very high TWM gain ∼107has been achieved. Maximum fractional delay (FD) of 1.04 and 0.20 is obtained for 150 ms pulse in case of SBN:75 and SBN:60 respectively. Further, the optical delay, group velocity, FWHM, pulse broadening and amplification in case of SBN:75 is compared with SBN:60. SBN:75 showed minimal pulse broadening, large amplification (∼105), five times more FD and two degrees of higher optical delay than that of SBN:60.

IntroductionLeber’s hereditary optic neuropathy is a mitochondrially-inherited disorder characterized by bilateral, painless visual loss, which leads to severe optic atrophy.1LHON can be associated with an MS-like illness referred to as Harding’s disease.2We report two siblings, who both harbour the 11778 mtDNA mutation, but manifest markedly different clinical phenotypes; a male with classical LHON and a female with Harding’s disease.Methods and ResultsA 61-year-old female, who was diagnosed with MS 22 years ago was referred to our service for a second opinion. She developed unilateral painless visual loss in her 20’s, was diagnosed with optic neuritis and treated with corticosteroids with some recovery. A second episode of more severe visual loss at age 39 left her with visual impairment to less than finger counting. 4 years later, she had an episode of dysarthria and gait ataxia. MRI showed multifocal white matter lesions involving the juxta-cortical and periventricular regions, cerebellar peduncle and cervical cord. Targeted views of the optic pathways showed hyperintensity of the left optic nerve, with involvement extending into the optic canal.The patient has one brother who was diagnosed with LHON at age 37 after presenting with severe painless bilateral sequential visual loss. Genetic testing of the index patient confirmed the presence of the same mutation identified in her brother. ConclusionLHON and Harding’s disease demonstrate a great degree of variability in clinical phenotype and penetrance between males and females as well as individuals within the same family.3While there is no evidence for screening MS cohorts for the LHON, consider genetic testing in patients with severe and persistent bilateral visual loss or with a suggestive family history.4ReferencesHarding AE, Sweeney MG, Miller DH, Mumford CJ, Kellar-Wood H, Menard D,McDonald WI, Compston DA. Occurrence of a multiple sclerosis-like illness in women who have a Leber’s hereditary optic neuropathy mitochondrial DNA mutation. Brain. 1992 August;115 ( Pt 4):979–89.Palace J. Multiple sclerosis associated with Leber’s Hereditary Optic Neuropathy. J Neurol Sci. 2009 November 15;286(1–2):24–7. Review.Pfeffer G, Burke A, Yu-Wai-Man P, Compston DAS, Chinnery PF. Clinical features of MS associated with Leber hereditary optic neuropathy mtDNA mutations. Neurology. 2013;81(24):2073–2081.Yu-Wai-Man P, Chinnery PF. Leber hereditary optic neuropathy. In: Pagon RA MP, Adam Ardinger HH eds. GeneReviews. Seattle, WA: University of Washington, Seattle; 2013. Accessed May 7, 2018.