Determinants of Conductive Hearing Loss in Tympanic Membrane Perforation

ObjectivesTympanic membrane perforations are common, but there have been few studies of the factors determining the extent of the resulting conductive hearing loss. The aims of this study were to determine whether the size of tympanic membrane perforation, pneumatization of middle ear & mastoid cavity, and location of perforation were correlated with air-bone gap (ABG) of patients.MethodsForty-two patients who underwent tympanoplasty type I or myringoplasty were included and preoperative audiometry were analyzed. Digital image processing was applied in computed tomography for the estimation of middle ear & mastoid pneumatization volume and tympanic membrane photograph for the evaluation of perforation size and location.ResultsPreoperative mean ABG increased with perforation size (P=0.018), and correlated inversely with the middle ear & mastoid volume (P=0.005). However, perforations in anterior versus posterior locations showed no significant differences in mean ABG (P=0.924).ConclusionThe degree of conductive hearing loss resulting from a tympanic membrane perforation would be expected with the size of perforation and pneumatization of middle ear and mastoid

Analysis of P1 Latency in Normal Hearing and Profound Sensorineural Hearing Loss

ObjectivesP1 is a robust positivity at a latency of 50-150 msec in the auditory evoked potential of young children. It has been reported that over the first 2-3 years of life, there is a rapid decrease of the latency and the mean P1 latency in adults with normal hearing is approximately 60 msec. This study was designed to evaluate the change of the P1 latency in Koreans with normal hearing according to age and to compare this with the P1 latency of young patients with profound sensorineural hearing loss before and/or after cochlear implantation.MethodsAmong the patients who visited the Department of Otorhinolaryngology at Seoul National University Hospital from June 2007 to September 2009, the P1 response was recorded in 53 patients in the normal hearing group, in 13 patients in the pre-cochlear implantation (CI) group and in 10 patients in the post-CI group. A synthesized consonant-vowel syllable /ba/ was used to elicit the evoked responses. The evoked responses were collected using the center of the frontal head. For each subject, an individual grand average waveform was computed by averaging the ten recordings. The P1 latency was visually identified as a robust positivity in the waveform.ResultsFor the normal hearing group, the P1 latency showed the pattern of shortening as the age increased (coefficient, -0.758; P<0.001). For the pre-CI group, 10 cases showed delayed latencies and 3 cases did not show the P1 wave. For the post-CI group, the P1 latencies showed a less delayed tendency than those of the pre-CI group, but this was not statistically different.ConclusionThis report provides the standard value of the P1 latency at each age in Koreans for the first time and the findings support that the maturation of the central auditory pathways could be measured objectively using the P1 latency

Design strategy of highly efficient nonlinear optical orange‐colored crystals with two electron‐withdrawing groups

A new class of highly efficient nonlinear optical organic salt crystals is reported. In nonlinear optics based on organic materials, it is well known that using two electron-withdrawing groups (EWGs) onto cationic electron acceptors instead of conventional one EWG remarkably enhances microscopic optical nonlinearity for chromophores. However, the corresponding organic crystals possessing enhanced large macroscopic optical nonlinearity have not been reported yet. Herein, a design strategy is proposed for obtaining highly efficient nonlinear optical crystals based on two EWGs in cationic electron acceptors. Introducing a phenolic electron donor, promoting a head-to-tail interionic assembly, along with a two-EWG N-pyrimidinyl pyridinium electron acceptor in cationic chromophores results in a preferred non-centrosymmetric, perfectly parallel alignment of chromophores in crystal. Newly designed OPR (4-(4-hydroxystyryl)-1-(pyrimidin-2-yl)pyridinium) crystals exhibit approximately two times larger effective first hyperpolarizability than that of analogous N-alkyl OHP (4-(4-hydroxystyryl)-1-methylpyridinium) crystals based on only one EWG. OPR crystals exhibit comparable second-order optical nonlinearity to benchmark red-colored DAST (4-(4-(dimethylamino)styryl)-1-methylpyridinium 4-methylbenzenesulfonate) crystals, but a significant blue-shifted absorption resulting in orange-color crystals. Therefore, phenolic organic salt crystals using two EWGs are highly promising materials for various nonlinear optical applications

A new class of organic crystals with extremely large hyperpolarizability : efficient THz wave generation with wide flat‐spectral‐band

In organic π-conjugated crystals, enhancing molecular optical nonlinearity of chromophores (e.g., first hyperpolarizability β ≥ 300 × 10−30 esu) in most cases unfortunately results in zero macroscopic optical nonlinearity, which is a bottleneck in organic nonlinear optics. In this study, a new class of nonlinear optical organic crystals introducing a chromophore possessing an extremely large first hyperpolarizability is reported. With newly designed 4-(4-(4-(hydroxymethyl)piperidin-1-yl)styryl)-1-(pyrimidin-2-yl)pyridin-1-ium (PMPR) chromophore, incorporating a head-to-tail cation-anion O-H⋯O hydrogen-bonding synthon and an optimal selection of molecular anion into crystals results in extremely large macroscopic optical nonlinearity with effective first hyperpolarizability of 335 × 10−30 esu. This is in sharp contrast to zero value for previously reported analogous crystals. An ultrathin PMPR crystal with a thickness of ≈10 µm exhibits excellent terahertz (THz) wave generation performance. Both i) broadband THz wave generation with a wide flat-spectral-band in the range of 0.7–3.4 THz defined at −3 dB and high upper cut-off generation frequency of > 7 THz as well as ii) high-generation efficiency (5 times higher THz amplitude than ZnTe crystal with a mm-scale thickness) are simultaneously achieved. Therefore, new PMPR crystals are highly promising materials for diverse applications in nonlinear optics and THz photonics

Single nanowire-based UV photodetectors for fast switching

Relatively long (30 µm) high quality ZnO nanowires (NWs) were grown by the vapor-liquid-solid (VLS) technique. Schottky diodes of single NW were fabricated by putting single ZnO NW across Au and Pt electrodes. A device with ohmic contacts at both the sides was also fabricated for comparison. The current-voltage (I-V) measurements for the Schottky diode show clear rectifying behavior and no reverse breakdown was seen down to -5 V. High current was observed in the forward bias and the device was found to be stable up to 12 V applied bias. The Schottky barrier device shows more sensitivity, lower dark current, and much faster switching under pulsed UV illumination. Desorption and re-adsorption of much smaller number of oxygen ions at the Schottky junction effectively alters the barrier height resulting in a faster response even for very long NWs. The NW was treated with oxygen plasma to improve the switching. The photodetector shows high stability, reversibility, and sensitivity to UV light. The results imply that single ZnO NW Schottky diode is a promising candidate for fabricating UV photodetectors

High‐density organic electro‐optic crystals for ultra‐broadband THz spectroscopy

Ultra-broadband THz photonics covering the 0.3–20 THz range provides a very attractive foundation for a wide range of basic research and industrial applications. However, the lack of ultra-broadband THz devices has yet to be overcome. In this work, high-density organic electro-optic crystals are newly developed for efficient THz wave generation in a very broad THz spectral range and are successfully used for a broadband THz time-domain spectroscopy. The new organic THz generator crystals, namely the OHP-TFS crystals, have very low void volume, high density, and are shown to cover the ultra-broadband THz spectrum up to about 15 THz, which cannot be easily accessed with the more widely used inorganic-based THz generators. In addition to the very favorable broadband properties, the generated THz electric-field amplitude at the pump wavelength of 1560 nm is about 40 times higher than that generated by a commercial inorganic THz generator (ZnTe crystal). By using the newly developed OHP-TFS as generation crystal in a compact table-top all-organic THz time-domain spectrometer based on a low-cost telecom fiber laser, the optical characteristics of a model material are successfully determined in the broad 1.5–12.5 THz range with high accuracy

Organic broadband THz generators optimized for efficient near‐infrared optical pumping

New organic THz generators are designed herein by molecular engineering of the refractive index, phonon mode, and spatial asymmetry. These benzothiazolium crystals simultaneously satisfy the crucial requirements for efficient THz wave generation, including having nonlinear optical chromophores with parallel alignment that provide large optical nonlinearity; good phase matching for enhancing the THz generation efficiency in the near-infrared region; strong intermolecular interactions that provide restraining THz self-absorption; high solubility that promotes good crystal growth ability; and a plate-like crystal morphology with excellent optical quality. Consequently, the as-grown benzothiazolium crystals exhibit excellent characteristics for THz wave generation, particularly at near-infrared pump wavelengths around 1100 nm, which is very promising given the availability of femtosecond laser sources at this wavelength, where current conventional THz generators deliver relatively low optical-to-THz conversion efficiencies. Compared to a 1.0-mm-thick ZnTe crystal as an inorganic benchmark, the 0.28-mm-thick benzothiazolium crystal yields a 19 times higher peak-to-peak THz electric field with a broader spectral bandwidth (>6.5 THz) when pumped at 1140 nm. The present work provides a valuable approach toward realizing organic crystals that can be pumped by near-infrared sources for efficient THz wave generation

Working Memory Impairment in Fibromyalgia Patients Associated with Altered Frontoparietal Memory Network

BACKGROUND: Fibromyalgia (FM) is a disorder characterized by chronic widespread pain and frequently associated with other symptoms. Patients with FM commonly report cognitive complaints, including memory problem. The objective of this study was to investigate the differences in neural correlates of working memory between FM patients and healthy subjects, using functional magnetic resonance imaging (MRI). METHODOLOGY/PRINCIPAL FINDINGS: Nineteen FM patients and 22 healthy subjects performed an n-back memory task during MRI scan. Functional MRI data were analyzed using within- and between-group analysis. Both activated and deactivated brain regions during n-back task were evaluated. In addition, to investigate the possible effect of depression and anxiety, group analysis was also performed with depression and anxiety level in terms of Beck depression inventory (BDI) and Beck anxiety inventory (BAI) as a covariate. Between-group analyses, after controlling for depression and anxiety level, revealed that within the working memory network, inferior parietal cortex was strongly associated with the mild (r = 0.309, P = 0.049) and moderate (r = 0.331, P = 0.034) pain ratings. In addition, between-group comparison revealed that within the working memory network, the left DLPFC, right VLPFC, and right inferior parietal cortex were associated with the rating of depression and anxiety? CONCLUSIONS/SIGNIFICANCE: Our results suggest that the working memory deficit found in FM patients may be attributable to differences in neural activation of the frontoparietal memory network and may result from both pain itself and depression and anxiety associated with pain

DJ-1 Null Dopaminergic Neuronal Cells Exhibit Defects in Mitochondrial Function and Structure: Involvement of Mitochondrial Complex I Assembly

DJ-1 is a Parkinson's disease-associated gene whose protein product has a protective role in cellular homeostasis by removing cytosolic reactive oxygen species and maintaining mitochondrial function. However, it is not clear how DJ-1 regulates mitochondrial function and why mitochondrial dysfunction is induced by DJ-1 deficiency. In a previous study we showed that DJ-1 null dopaminergic neuronal cells exhibit defective mitochondrial respiratory chain complex I activity. In the present article we investigated the role of DJ-1 in complex I formation by using blue native-polyacrylamide gel electrophoresis and 2-dimensional gel analysis to assess native complex status. On the basis of these experiments, we concluded that DJ-1 null cells have a defect in the assembly of complex I. Concomitant with abnormal complex I formation, DJ-1 null cells show defective supercomplex formation. It is known that aberrant formation of the supercomplex impairs the flow of electrons through the channels between respiratory chain complexes, resulting in mitochondrial dysfunction. We took two approaches to study these mitochondrial defects. The first approach assessed the structural defect by using both confocal microscopy with MitoTracker staining and electron microscopy. The second approach assessed the functional defect by measuring ATP production, O2 consumption, and mitochondrial membrane potential. Finally, we showed that the assembly defect as well as the structural and functional abnormalities in DJ-1 null cells could be reversed by adenovirus-mediated overexpression of DJ-1, demonstrating the specificity of DJ-1 on these mitochondrial properties. These mitochondrial defects induced by DJ-1mutation may be a pathological mechanism for the degeneration of dopaminergic neurons in Parkinson's disease