Application of flexible pin for planetary gear set of wind turbine gearbox.

Wind turbines are eco-friendly energy sources that generate electricity from wind power. Among their various components, gearboxes constitute the most critical loss owing to their longest downtime. To guarantee their durability, a flexible pin was designed based on the original straddle-mounted pin for enhanced tooth load sharing and distribution in the planetary gear set (PGS) of a wind turbine gearbox (WTGB). The improved durability was evaluated by calculating the mesh load factor and face load factor for contact stress and comparing these values with those of the original straddle-mounted pin. The mesh load factor decreased from 1.37 to 1.08, whereas the maximum face load factor decreased slightly, moderating the overall safety factor variation. Furthermore, the structure of the proposed flexible pin model was analyzed and verified that no static failure or interference occurred. Additionally, microgeometry optimization was applied to improve the load distribution. Therefore, it was verified that a flexible pin applied to a single helical-geared PGS, thus far considered impossible, enhances the durability of WTGBs by improving the load sharing and distribution of a PGS. Consequently, the possibility of designing single helical-geared planetary gearboxes with flexible pins to take advantages of both helical gears and flexible pins was shown analytically.

Bipolar and Complementary Resistive Switching Characteristics and Neuromorphic System Simulation in a Pt/ZnO/TiN Synaptic Device.

In this work, a ZnO-based resistive switching memory device is characterized by using simplified electrical conduction models. The conventional bipolar resistive switching and complementary resistive switching modes are accomplished by tuning the bias voltage condition. The material and chemical information of the device stack including the interfacial layer of TiON is well confirmed by transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) analysis. The device exhibits uniform gradual bipolar resistive switching (BRS) with good endurance and self-compliance characteristics. Moreover, complementary resistive switching (CRS) is achieved by applying the compliance current at negative bias and increasing the voltage at positive bias. The synaptic behaviors such as long-term potentiation and long-term depression are emulated by applying consecutive pulse input to the device. The CRS mode has a higher array size in the cross-point array structure than the BRS mode due to more nonlinear I-V characteristics in the CRS mode. However, we reveal that the BRS mode shows a better pattern recognition rate than the CRS mode due to more uniform conductance update.

Could surgical management improve the IVF outcomes in infertile women with endometrioma?: a review.

Endometriosis is a chronic inflammatory condition that affects fertility and could be toxic to the ovary. Endometrioma per se and surgical interventions for endometrioma significantly reduce the ovarian reserve. Therefore, to prepare for surgical intervention for endometrioma, the high-risk group with decreased ovarian reserve must be considered. There is no evidence to support the use of surgical intervention before in vitro fertilization (IVF) to improve the reproductive outcomes of subsequent IVF in infertile women with advanced-stage endometriosis or endometrioma. As surgical treatment has few benefits, IVF could be recommended immediately for aiding conception in these women. However, the reproductive prognosis of IVF may be worse in the more advanced stages of endometriosis. When dysmenorrhea is severe or when cancer is suspected, surgery prior to IVF may be necessary and justified. When the size of the endometrioma is very large, surgery could be required prior to IVF to facilitate access to follicles during oocyte retrieval or to improve the ovarian response to controlled ovarian stimulation. Prolonged pituitary downregulation in women with surgically diagnosed endometriosis may be helpful to increase the clinical pregnancy rate in subsequent IVF cycles. The purpose of this paper was to review the efficiency and clinical application of the surgical intervention and IVF for infertile women with advanced-stage endometriosis or endometrioma.

D-dimer levels and cerebral infarction in critically ill cancer patients.

BACKGROUND: D-dimer levels have been used in the diagnosis of a variety of thrombosis-related diseases. In this study, we evaluated whether measuring D-dimer levels can help to diagnose cerebral infarction (CI) in critically ill cancer patients. METHODS: We retrospectively evaluated all cancer patients who underwent brain magnetic resonance imaging (MRI) between March 2010 and February 2014 at the medical oncology intensive care unit (ICU) of Samsung Medical Center. Brain MRI scanning was performed when CI was suspected due to acute neurological deficits. We compared D-dimer levels between patients ultimately diagnosed as having or not having CI and analyzed diffusion-weighted imaging (DWI) lesion patterns. RESULTS: A total of 88 patients underwent brain MRI scanning due to clinical suspicion of CI; altered mental status and unilateral hemiparesis were the most common neurological deficits. CI was ultimately diagnosed in 43 (49%) patients. According to the DWI patterns, multiple arterial infarctions (40%) were more common than single arterial infarctions (9%). Cryptogenic stroke etiologies were more common (63%) than determined etiologies. There was no significant difference in D-dimer levels between patients with and without CI (P = 0.319). Although D-dimer levels were not helpful in diagnosing CI, D-dimer levels were associated with cryptogenic etiologies in critically ill cancer patients; D-dimer levels were higher in the cryptogenic etiology group than in the determined etiology group or the non-infarction group (P = 0.001). In multivariate analysis, elevated D-dimer levels (> 8.89 µg/mL) were only associated with cryptogenic stroke (adjusted OR 5.46; 95% confidence interval, 1.876-15.857). CONCLUSIONS: Abnormal D-dimer levels may support the diagnosis of cryptogenic stroke in critically ill cancer patients.

The meaning of anti-Müllerian hormone levels in patients at a high risk of poor ovarian response.

Measurements of ovarian reserve play an important role in predicting the clinical results of assisted reproductive technology (ART). The ideal markers of ovarian reserve for clinical applications should have high specificity in order to determine genuine poor responders. Basal follicle-stimulating hormone levels, antral follicle count, and serum anti-Müllerian hormone (AMH) levels have been suggested as ovarian reserve tests that may fulfill this requirement, with serum AMH levels being the most promising parameter. Serum AMH levels have been suggested to be a predictor of clinical pregnancy in ART for older women, who are at a high risk for decreased ovarian response. We reviewed the prognostic significance of ovarian reserve tests for patients undergoing ART treatment, with a particular focus on the significance of serum AMH levels in patients at a high risk of poor ovarian response.

Timing of neurological improvement after acute ischemic stroke and functional outcome.

BACKGROUND: The time of neurological improvement (TNI) after acute ischemic stroke may have a predictive value. METHODS: We evaluated 410 consecutive patients who were admitted within 12 hours of stroke onset. The National Institutes of Health Stroke Scale (NIHSS) was measured on admission and at 1, 3, 7, and 14 days. Neurological improvement was defined as an improvement in the NIHSS score by ≥2 points (NI2) or ≥4 points (NI4) or an NIHSS score of 0. Patients with a Modified Rankin scale (mRS) score of ≤2 were considered to have a good outcome. RESULTS: Patients with earlier TNIs had a lower 3-month mRS score and a higher probability for a good outcome. In the binary and ordinal regression analyses, age, NIHSS score, atrial fibrillation and TNI were independently associated with a good outcome. Receiver operating characteristic curve analyses demonstrated that TNI2 had higher sensitivity and lower specificity than TNI4. The best threshold for predicting outcome was day 3 for TNI2 and day 14 for TNI4. CONCLUSIONS: These results suggest that TNI is independently associated with functional outcome at 90 days. TNI2 may be more useful than TNI4 for early prediction of stroke outcome.

Polymerization shrinkage, flexural and compression properties of low-shrinkage dental resin composites.

This study evaluated the polymerization shrinkage, flexural and compressive properties of low-shrinkage resin composites. For the study, four methacrylate-based and one silorane-based resin composites were light cured using three different light-curing units (LCUs) and their polymerization shrinkage, flexural (strength (FS) and modulus (FM)) and compressive (strength (CS) and modulus (CM)) properties were evaluated. Data were statistically analyzed using ANOVA and a post-hoc Tukey test. The polymerization shrinkage ranged approximately 7.6-14.2 µm for 2-mm thick specimens depending on the resin product and LCU. Filtek LS showed the least shrinkage while the rest shrank approximately 13.2-14.2 µm. However, Filtek LS showed the greatest shrinkage difference for the used LCUs. FS and CS of the tested specimens ranged 96.2-152.1 MPa and 239.2-288.4 MPa, respectively, depending on the resin product and LCU. The highest and lowest FS and FM were recorded for the methacrylate-based resin composites. Among the specimens, Filtek LS showed the lowest CS and CM.

Skin temperature changes in patients with unilateral lumbosacral radiculopathy.

OBJECTIVE: To clarify the relationship of skin temperature changes to clinical, radiologic, and electrophysiological findings in unilateral lumbosacral radiculopathy and to delineate the possible temperature-change mechanisms involved. METHODS: One hundred and one patients who had clinical symptoms and for whom there were physical findings suggestive or indicative of unilateral lumbosacral radiculopathy, along with 27 normal controls, were selected for the study, and the thermal-pattern results of digital infrared thermographic imaging (DITI) performed on the back and lower extremities were analyzed. Local temperatures were assessed by comparing the mean temperature differences (ΔT) in 30 regions of interest (ROIs), and abnormal thermal patterns were divided into seven regions. To aid the diagnosis of radiculopathy, magnetic resonance imaging (MRI) and electrophysiological tests were also carried out. RESULTS: The incidence of disc herniation on MRI was 86%; 43% of patients showed electrophysiological abnormalities. On DITI, 97% of the patients showed abnormal ΔT in at least one of the 30 ROIs, and 79% showed hypothermia on the involved side. Seventy-eight percent of the patients also showed abnormal thermal patterns in at least one of the seven regions. Patients who had motor weakness or lateral-type disc herniation showed some correlations with abnormal DITI findings. However, neither pain severity nor other physical or electrophysiological findings were related to the DITI findings. CONCLUSION: Skin temperature change following lumbosacral radiculopathy was related to some clinical and MRI findings, suggesting muscle atrophy. DITI, despite its limitations, might be useful as a complementary tool in the diagnosis of unilateral lumbosacral radiculopathy.

Effect of energy density on low-shrinkage composite resins: diode-pumped solid state laser versus quartz-tungsten-halogen light-curing unit.

OBJECTIVE: The purpose of the present study was to evaluate the effect of energy density on the polymerization of low-shrinkage composite resins. BACKGROUND DATA: The number of photons needs to initiate the polymerization process can be controlled by light intensity and curing time through the form of energy density. MATERIALS AND METHODS: For the study, two methacrylate-based (Premise [PR] and Venus Diamond [VE]) and one silorane-based (Filtek LS [LS]) composite resins were light cured using a quartz-tungsten-halogen (QTH) light-curing unit (LCU) and a 473 nm diode-pumped solid state (DPSS) laser. Degree of conversion (DC), microhardness, refractive index, and polymerization shrinkage were evaluated under different energy densities. Through the study, the feasibility of DPSS laser as a light source was tested as well. RESULTS: LS showed the highest DC and refractive index both on the top and bottom surfaces, and the least polymerization shrinkage among the tested specimens. For the same or similar energy density, QTH and DPSS showed insignificant DC difference (p>0.05). On the other hand, for microhardness, except for one case at the bottom surface, QTH and DPSS showed significant difference (p<0.001). DPSS generated slightly lower polymerization shrinkage than that by QTH. CONCLUSIONS: DC, microhardness, refractive index, and polymerization shrinkage were linearly correlated with energy density. In most cases, there was a strong linear correlation among DC, mirohardness, and refractive index. The DPSS laser of 473 nm could polymerize low-shrinkage composite resins to the level that was achieved by the conventional QTH unit.

[A case of steroid-induced hyperinfective strongyloidiasis with bacterial meningitis].

Strongyloides stercoralis is a soil transmitted intestinal nematode that is endemic in the tropical and subtropical regions. In most individuals who are infected, chronic, usually asymptomatic, gastrointestinal infection persists. But, in immunocompromized hosts or in patients receiving immunosuppressive therapy, autoinfection of S. stercoralis may result in the dissemination of larvae, leading to fatal hyperinfection and increased rate of complications. We report a case of hyperinfective strongyloidiasis with bacterial meningitis in a patient receiving steroid therapy. Strongyloidiasis was diagnosed by the presence of filariform larvae of S. stercoralis in the bronchoalveolar lavage cytology and upper gastrointestinal endoscopic biopsy specimen. Her clinical symptoms had progressively aggravated and developed bacterial meningitis during treatment. She died despite aggressive antibiotic and antihelminthic therapy.

The relationship between hippocampal volume and cognition in patients with chronic primary insomnia.

BACKGROUND AND PURPOSE: Differences in hippocampal volume (HV) were compared between chronic primary insomniacs (PIs) and good sleepers (GSs), and the relationship between HV and memory function in PIs was investigated to clarify the effect of chronic sleep deprivation on brain structure and cognition. METHODS: Twenty PIs (mean age, 50 years; 18 females) and 20 age-, gender-, and education-matched GSs were enrolled. Brain magnetic resonance imaging (MRI) was performed on a 1.5-T MRI scanner. Left and right HV and intracranial volume (ICV) were measured manually. Nighttime polysomnography and neuropsychological testing were also applied to all subjects. Group differences in HV were analyzed and the relationships between HV and sleep questionnaire data, nighttime polysomnography, and neuropsychological findings were evaluated. RESULTS: Compared to GSs, PIs exhibited significantly increased sleep latency and arousal index and a decreased percentage of REM sleep in nighttime polysomnography, as well as impaired verbal and visual memory, and frontal lobe function. Absolute HV and ICV did not differ significantly between PIs and GSs. In the PIs, right and left HVs were negatively correlated with the duration of insomnia and the arousal index, and positively correlated with the recognition of visual memory. In addition, free recall in verbal memory was positively correlated with left HV in PIs. CONCLUSIONS: These findings suggest that chronic sleep deprivation impairs memory and frontal lobe function, and that a long duration of insomnia and poor sleep quality contribute to a bilateral reduction in HV.

Factors contributing to Korean teachers' attitudes toward students with epilepsy.

We investigated factors contributing to teachers' attitudes toward students with epilepsy. Data were collected from 604 teachers in Korea. The questionnaire included the Scale of Attitudes Toward Persons with Epilepsy (ATPE) and a demographic and teaching experience survey. In stepwise linear regression analysis, ATPE Knowledge scores (P<0.001) and prior experience teaching a student with epilepsy (P=0.001) were identified as significant factors for ATPE Attitude scores. The ATPE Knowledge scores accounted for 50.1% of the variance in the Attitude scores, and experience teaching a student with epilepsy accounted only for 1.0%. Our finding that teachers' knowledge is the most important factor influencing teacher's attitudes toward epilepsy indicates that teachers should be provided with information about epilepsy universally, across geographic settings, educational levels, and experience levels.

Factors contributing to Korean adolescents' perceptions of stigma with respect to epilepsy.

We assessed knowledge and perceptions of epilepsy held by Korean adolescents in the general population, and investigated factors important in adolescents' perceptions of stigma with respect to epilepsy. Surveys were distributed to students at 22 schools. A total of 1377 students participated. Fewer than half of all students (45.1%) reported hearing or reading about epilepsy. Overall, students showed a general lack of familiarity with and knowledge of epilepsy. Stigma perception scores were significantly higher in boys than in girls (P<0.05) and in middle school than in high school (P<0.05) students. We also found that stigma perception scores were significantly correlated with both younger age (r=-0.074, P=0.006) and lower knowledge scores (r=-0.404, P=0.000). Linear regression analysis showed that stigma-related perception was associated with lower knowledge scores (P<0.001) and middle school (P<0.05). These results indicate a need for public education of adolescents in the general population to decrease the stigma associated with epilepsy.