Aircraft landing gear assemblies comprise of various subsystems working in unison to enable functionalities such as taxiing, take-off and landing. As development cycles and prototyping iterations ...begin to shorten, it is important to develop and improve practical methodologies to meet certain design metrics. This paper presents an efficient methodology that applies high-fidelity multi-disciplinary design optimization techniques to commercial landing gear assemblies, for weight, cost, and structural performance by considering both structural and dynamic behaviours. First, a simplified landing gear assembly model was created to complement with an accurate slave link subassembly, generated based of drawings supplied from the industrial partner, Safran Landing Systems. Second, a Multi-Body Dynamic (MBD) analysis was performed using realistic input motion signals to replicate the dynamic behaviour of the physical system. The third stage involved performing topology optimization with results from the MBD analysis; this can be achieved through the utilization of the Equivalent Static Load Method (ESLM). Lastly, topology results were generated and design interpretation was performed to generate two designs of different approaches. The first design involved trying to closely match the topology results and resulted in a design with an overall weight savings of 67%, peak stress increase of 74%, and no apparent cost savings due to complex features. The second design focused on manufacturability and achieved overall weight saving of 36%, peak stress increase of 6%, and an estimated 60% in cost savings.
Titanium matrix composites (TMCs) have several attractive characteristics including high temperature properties, wear resistance and oxidation resistance. In the case of metal matrix composites, it ...is generally desirable to select reinforcements that exhibit suitable interfaces with the matrix, high temperature stability, and similar coefficients of thermal expansion with respect to the matrix. Conventional candidates for reinforcements in TMCs include SiC, Si
3N
4, Al
2O
3, TiC, TiN, TiB, and TiB
2. These materials have high temperature properties, fatigue strength, and wear and oxidation resistance. TMC manufacturing methods can be divided into powder metallurgy and the melting route approach. In the case of powder metallurgy, the processing steps are very complicated, and an agglomeration of reinforcements can cause the deterioration of mechanical properties. In the melting route approach, net-shape forming is hard to obtain due to a high affinity in the molten state, and low fluidity of the melts. However, the melting route approach can provide an economical and sound final casting. In this study, we used the investment casting process for economical considerations. In addition, an in situ synthesis method was also developed to ensure homogeneous distribution and a controlled interfacial reaction between the matrix and reinforcements. The friction and wear behavior of TMCs were investigated using a pin-on-disk wear tester under various conditions and were evaluated using scanning electron microscopy (SEM) analysis.
Selective serotonin reuptake inhibitors have been associated with the risk of restless legs syndrome (RLS), suggesting that dysregulation of serotonergic neurotransmission may provoke or exacerbate ...RLS.
We compared the availability of serotonin transporter (SERT) between 16 drug-naïve patients with RLS and 16 healthy controls. SERT was measured in the pons and medulla via (123)I-2beta-carbomethoxy-3beta-(4-iodophenyl) tropane (beta-CIT) SPECT. A ratio of specific to nonspecific brain uptake (V(3)'') was used for all comparisons. RLS was diagnosed according to the criteria proposed by the National Institute of Health, and its severity was measured using the International RLS Study Group (IRLSSG) Severity Scale.
The availability of SERT was similar in the RLS group and the control group with regards to the pons (1.24 +/- 0.31 vs 1.24 +/- 0.25, p > 0.1) and the medulla (0.99 +/- 0.25 vs 1.00 +/- 0.23, p > 0.1). However, IRLSSG Severity Scale scores increased with decrease of SERT availability in both the pons (beta = -0.50, t = -3.19, p = 0.009) and the medulla (beta = -0.42, t = -2.44, p = 0.03).
Although serotonin transporter (SERT) availability in pons and medulla was similar in the restless legs syndrome (RLS) group and the control group, the severity of RLS symptoms increased as the availability of SERT decreased. These data partially support the hypothesis that an increase of serotonergic neurotransmission in the brainstem may exacerbate RLS, possibly via dual modulations on striatal dopaminergic neurotransmission and on the activities of spinal motor and sensory neurons.
Menopause, a dramatical estrogen-deficient condition, is considered the most significant milestone in women's health.
To investigate the metabolite changes attributed to estrogen deficiency using ...random forest (RF)-based machine learning (ML) modeling strategy in ovariectomized (OVX) mice as well as determine the clinical relevance of selected metabolites in older women.
Untargeted and targeted metabolomic analyses revealed that metabolites related to TCA cycle, sphingolipids, phospholipids, fatty acids, and amino acids, were significantly changed in the plasma and/or muscle of OVX mice. Subsequent ML classifiers based on RF algorithm selected alpha-ketoglutarate (AKG), arginine, carnosine, ceramide C24, phosphatidylcholine (PC) aa C36:6, and PC ae C42:3 in plasma as well as PC aa 34:1, PC aa C34:3, PC aa C36:5, PC aa C32:1, PC aa C36:2, and sphingosine in muscle as top featured metabolites that differentiate the OVX mice from the sham-operated group. When circulating levels of AKG, arginine, and carnosine, which showed the most significant changes in OVX mice blood, were measured in postmenopausal women, higher plasma AKG levels were associated with lower bone mass, weak grip strength, poor physical performance, and increased frailty risk.
Metabolomics- and ML-based methods identified the key metabolites of blood and muscle that were significantly changed after ovariectomy in mice, and the clinical implication of several metabolites was investigated by looking at their correlation with body composition and frailty-related parameters in postmenopausal women. These findings provide crucial context for understanding the diverse physiological alterations caused by estrogen deficiency in women.
Tissue engineering is an important therapeutic strategy for present and future medicine. Recently, functional biomaterial researches have been directed towards the development of improved scaffolds ...for regenerative medicine. Chitosan is a natural polymer from renewable resources, obtained from shell of shellfish, and the wastes of the seafood industry. It has novel properties such as biocompatibility, biodegradability, antibacterial, and wound-healing activity. Furthermore, recent studies suggested that chitosan and its derivatives are promising candidates as a supporting material for tissue engineering applications owing to their porous structure, gel forming properties, ease of chemical modification, high affinity to in vivo macromolecules, and so on. In this review, we focus on the various types of chitosan derivatives and their use in various tissue engineering applications namely, skin, bone, cartilage, liver, nerve and blood vessel.
BACKGROUNDSeveral studies have demonstrated that 11C-methionine positron-emission tomography provides information on prognosis. PURPOSEWe performed a systematic review and meta-analysis of the ...prognostic value of the metabolic and volumetric parameters of 11C-methionine-PET for gliomas. DATA SOURCESA systematic search was performed using the following combination of keywords: "methionine," "PET," "glioma," and "prognosis." STUDY SELECTIONThe inclusion criteria were the use of 11C-methionine-PET as an imaging tool, studies limited to gliomas, studies including metabolic parameters (tumor-to-normal ratio) and/or volumetric parameters (metabolic tumor volume), and studies reporting survival data. The electronic search first identified 181 records, and 14 studies were selected. DATA ANALYSISEvent-free survival and overall survival were the outcome measures of interest. The effect of the tumor-to-normal ratio and metabolic tumor volume on survival was determined by the effect size of the hazard ratio. Hazard ratios were extracted directly from each study when provided or determined by analyzing the Kaplan-Meier curves. DATA SYNTHESISThe combined hazard ratios of the tumor-to-normal ratio for event-free survival was 1.74 with no significance and that of the tumor-to-normal ratio for overall survival was 2.02 with significance. The combined hazard ratio of the metabolic tumor volume for event-free survival was 2.72 with significance and that of the metabolic tumor volume for overall survival was 3.50 with significance. LIMITATIONSThe studies selected were all retrospective, and there were only 4 studies involving the metabolic tumor volume. CONCLUSIONSThe present meta-analysis of 11C-methionine-PET suggests that the tumor-to-normal ratio for overall survival and the metabolic tumor volume for event-free survival and overall survival are significant prognostic factors for patients with gliomas.
This paper presents an adaptive weighted sum (AWS) method for multiobjective optimization problems. The method extends the previously developed biobjective AWS method to problems with more than two ...objective functions. In the first phase, the usual weighted sum method is performed to approximate the Pareto surface quickly, and a mesh of Pareto front patches is identified. Each Pareto front patch is then refined by imposing additional equality constraints that connect the pseudonadir point and the expected Pareto optimal solutions on a piecewise planar hypersurface in the \{m}\-dimensional objective space. It is demonstrated that the method produces a well-distributed Pareto front mesh for effective visualization, and that it finds solutions in nonconvex regions. Two numerical examples and a simple structural optimization problem are solved as case studies.
We present statistical characteristics of 1578 delta Scuti stars including nearby field stars and cluster member stars within the Milky Way. We obtained 46% of these stars (718 stars) from work by ...Rodriguez and collected the remaining 54% of stars (860 stars) from other literature. We updated the entries with the latest information of sky coordinates, color, rotational velocity, spectral type, period, amplitude, and binarity. The majority of our sample is well characterized in terms of typical period range (0.02-0.25 days), pulsation amplitudes (<0.5 mag), and spectral types (A-F type). Given this list of delta Scuti stars, we examined relations between their physical properties (i.e., periods, amplitudes, spectral types, and rotational velocities) for field stars and cluster members, and confirmed that the correlations of properties are not significantly different from those reported in Rodriguez's work. All the delta Scuti stars are cross-matched with several X-ray and UV catalogs, resulting in 27 X-ray and 41 UV-only counterparts. These counterparts are interesting targets for further study because of their uniqueness in showing delta Scuti-type variability and X-ray/UV emission at the same time. The compiled catalog can be accessed through the Web interface http://stardb.yonsei.ac.kr/DeltaScuti.
Abstract The purpose of this study was to evaluate the volumetric change of the upper airway space in 36 Class III patients who had undergone bimaxillary surgery or isolated mandibular setback, and, ...further, to analyse the relation between post-surgical stability and airway change using cone-beam computed tomography (CBCT). A three-dimensional (3D) CBCT examination was performed at three stages: T0 (before surgery), T1 (an average of 4.6 months after surgery), and T2 (an average of 1.4 years after surgery). The results showed that the volumes of the oropharyngeal and hypopharyngeal airways decreased significantly 4.6 months post-surgery in the mandibular setback group ( p < 0.05), and these diminished airways had not recovered 1.4 years post-surgery. In the bimaxillary surgery group, the volume of the oropharyngeal airway also decreased. A Spearman correlation analysis showed that the anteroposterior length of the hypopharyngeal area had a correlation with post-surgical stability in the isolated mandibular surgery group, and that the cross-sectional area of the nasopharynx was correlated with maxillary relapse only in the bimaxillary surgery group ( p < 0.05).
Purpose
This study investigated the degree of tumor cell infiltration in the tumor cavity and ventricle wall based on fluorescent signals of 5-aminolevulinic acid (5-ALA) after removal of the ...magnetic resonance (MR)-enhancing area and analyzed its prognostic significance in glioblastoma.
Methods
Twenty-five newly developed isocitrate dehydrogenase (IDH)-wildtype glioblastomas with complete resection both of MR-enhancing lesions and strong purple fluorescence on resection cavity were retrospectively analyzed. The fluorescent signals of 5-ALA were divided into strong purple, vague pink, and blue colors. The pathologic findings were classified into massively infiltrating tumor cells, infiltrating tumor cells, suspicious single-cell infiltration, and normal-appearing cells. The pathological findings were analyzed according to the fluorescent signals in the resection cavity and ventricle wall.
Results
There was no correlation between fluorescent signals and infiltrating tumor cells in the resection cavity (
p
= 0.199) and ventricle wall (
p
= 0.704) after resection of the MR-enhancing lesion. The median progression-free survival (PFS) and median overall survival (OS) were 12.5 (± 2.1) and 21.1 (± 3.5) months, respectively. In univariate analysis, the presence of definitive infiltrating tumor cells in the resection cavity and ventricle wall was significantly related to the PFS (
p
= 0.002) and OS (
p
= 0.027). In multivariate analysis, the absence of definitive infiltrating tumor cells improved PFS (hazard ratio: 0.184; 95% CI: 0.049–0.690,
p
= 0.012) and OS (hazard ratio: 0.124; 95% CI: 0.015–0.998,
p
= 0.050).
Conclusions
After resection both of the MR-enhancing lesions and strong purple fluorescence on resection cavity, there was no correlation between remnant fluorescent signals and infiltrating tumor cells. The remnant definitive infiltrating tumor cells in the resection cavity and ventricle wall significantly influenced the prognosis of patients with glioblastoma. Aggressive surgical removal of infiltrating tumor cells may improve their prognosis.
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