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The first total synthesis of (+)-tanzawaic acid B, a natural polyketide bearing a pentadienoic ester and octalin moiety, has been accomplished. The synthetic improvement from previous synthetic conditions facilitated our gram-scale synthesis of the chiral octalin that possesses seven stereogenic centers and that is the core skeleton of almost all of the tanzawaic acid family.

The first total synthesis of (+)-tanzawaic acid B, a natural polyketide bearing a pentadienoic ester and octalin moiety, has been accomplished. The synthetic improvement from previous synthetic conditions facilitated our gram-scale synthesis of the chiral octalin that possesses seven stereogenic centers and that is the core skeleton of almost all of the tanzawaic acid family.

We propose a robust approach to recovering jointly sparse signals in the presence of outliers. The robust recovery task is cast as a convex optimization problem involving a minimax concave loss function (which is weakly convex) and a strongly convex regularizer (which ensures the overall convexity). The use of the nonconvex loss makes the problem difficult to solve directly by the convex optimization methods even with the well-established firm shrinkage. We circumvent this difficulty by reformulating the problem via the Moreau decomposition so that the objective function becomes a sum of convex functions that can be minimized by the primal-dual splitting method. The parameter designs/ranges for the present specific case are derived to ensure the convergence. We demonstrate the remarkable robustness of the proposed approach against outliers by extensive simulations to the application of multi-lead electrocardiogram as well as synthetic data.

We present an efficient mathematical framework based on the linearly-involved Moreau-enhanced-over-subspace (LiMES) model. Two concrete applications are considered: sparse modeling and robust regression. The popular minimax concave (MC) penalty for sparse modeling subtracts, from the $\ell_1$ norm, its Moreau envelope, inducing nearly unbiased estimates and thus yielding remarkable performance enhancements. To extend it to underdetermined linear systems, we propose the projective minimax concave penalty using the projection onto the input subspace, where the Moreau-enhancement effect is restricted to the subspace for preserving the overall convexity. We also present a novel concept of stable outlier-robust regression which distinguishes noise and outlier explicitly. The LiMES model encompasses those two specific examples as well as two other applications: stable principal component pursuit and robust classification. The LiMES function involved in the model is an ``additively nonseparable'' weakly convex function but is defined with the Moreau envelope returning the minimum of a ``separable'' convex function. This mixed nature of separability and nonseparability allows an application of the LiMES model to the underdetermined case with an efficient algorithmic implementation. Two linear/affine operators play key roles in the model: one corresponds to the projection mentioned above and the other takes care of robust regression/classification. A necessary and sufficient condition for convexity of the smooth part of the objective function is studied. Numerical examples show the efficacy of LiMES in applications to sparse modeling and robust regression., Comment: 17 pages, 10 fugures, journal paper

We propose a robust approach to recovering the jointly-sparse signals in the presence of outliers. We formulate the recovering task as a minimization problem involving three terms: (i) the minimax concave (MC) loss function, (ii) the MC penalty function, and (iii) the squared Frobenius norm. The MC-based loss and penalty functions enhance robustness and group sparsity, respectively, while the squared Frobenius norm induces the convexity. The problem is solved, via reformulation, by the primal-dual splitting method, for which the convergence condition is derived. Numerical examples show that the proposed approach enjoys remarkable outlier robustness.

形態: カラー図版あり, Physical characteristics: Original contains color illustrations, Accepted: 2018-04-16, 資料番号: PA1810060000

Most gastrointestinal stromal tumours (GISTs) are caused by constitutively active mutations in Kit tyrosine kinase. The drug imatinib, a specific Kit inhibitor, improves the prognosis of metastatic GIST patients, but these patients become resistant to the drug by acquiring secondary mutations in the Kit kinase domain. We recently reported that a Kit mutant causes oncogenic signals only on the Golgi apparatus in GISTs. In this study, we show that in GIST, 2-methylcoprophilinamide (M-COPA, also known as "AMF-26"), an inhibitor of biosynthetic protein trafficking from the endoplasmic reticulum (ER) to the Golgi, suppresses Kit autophosphorylation at Y703/Y721/Y730/Y936, resulting in blockade of oncogenic signalling. Results of our M-COPA treatment assay show that Kit Y703/Y730/Y936 in the ER are dephosphorylated by protein tyrosine phosphatases (PTPs), thus the ER-retained Kit is unable to activate downstream molecules. ER-localized Kit Y721 is not phosphorylated, but not due to PTPs. Importantly, M-COPA can inhibit the activation of the Kit kinase domain mutant, resulting in suppression of imatinib-resistant GIST proliferation. Our study demonstrates that Kit autophosphorylation is spatio-temporally regulated and may offer a new strategy for treating imatinib-resistant GISTs.

In this paper, we report the first total synthesis of (+)-coprophilin, an anticoccidial agent, by constructing the chiral linear precursor via a Mukaiyama–Evans aldol reaction and a stereoselective intramolecular Diels–Alder reaction. The proposed method can be used to provide large amounts of (+)-coprophilin, which exhibits a 3,4,5,6,7-pentasubstituted Δ1,2-octalin core structure.

The pintle injector is a promising candidate for propellant-injection systems for various rocket engines. However, fundamental studies focusing on the pintle injector are rather limited, and the effects of key design parameters on combustion behaviors of the injector are still not identified. Therefore, combustion tests of an ethanol/liquid-oxygen rocket-engine combustor with a planar pintle injector are conducted to investigate the effects of total momentum ratio and O/F on the combustion characteristics of the pintle injector. The total momentum ratio and O/F vary from 1.0 to 2.2 and from 0.32 to 3.65, respectively, whereas the combustion pressure is kept constant at approximately 0.4 MPa. The spray structures are observed with high-speed cameras. The characteristic exhaust velocity (C*) efficiency increases with the increase in O/F in the fuel-centered configuration, and the opposite tendency is observed in the oxidizer-centered configuration. The C* efficiency decreases with the increase in the total ...

Insulation resistance measurement is one of the widely used methods to diagnose insulation conditions of turbine generators. Since insulation resistance tends to decrease with the increasing temperature, it needs to be evaluated on exactly the same basis. Insulation resistance of the epoxy-mica based insulation system does have temperature dependence in the temperature range over 40°C, but the insulation resistance is nearly constant in the temperature range under 40°C. In order to study the mechanism of the temperature dependence, current components such as conduction current I G , surface leakage current I L and polarization current I P were measured by applying a DC high voltage across the main insulation under the temperature range of 10°C to 80°C and the time range of 0 to 30 min. The dominant current component of 1 minute value is I P , and it is nearly-constant less than 40°C and tends to increase over 40°C. Therefore the temperature dependence of the insulation resistance is determined by that of I P . Since the insulation resistance is nearly-constant under 40°C, no temperature correction is required as long as it is measured under 40°C.

In this study, we evaluate the influence of fault parameters on the ground motion characteristics and building response characteristics in the near-fault region, in order to develop the seismic design load for the Uemachi fault. We simulate ground motions in near-fault region changing several fault parameters using 3D-FDM. As results, the following conclusions are obtained. 1)Background of fault have little effect to near-fault pulse-like ground motion in the period range T>1.25s. 2)Peak ground velocity is affected by asperity size, rupture velocity, rise time, upper depth of asperity. 3)The pulse period on sedimentary layers depends on that of the bedrock and predominant periods of sedimentary layers. 4)The region where we should consider the influence of pulselike ground motions depends on the ratio of natural periods of buildings and pulse periods of the ground motion.

In recent inland shallow earthquakes, pulse-like ground motions have been observed which subsequently caused severe damage to buildings. However, the response of buildings to pulse-like ground motions has not been sufficiently characterized yet. In this study, we investigate the effect of pulse-like ground motions on the design of structures and define the maximum response of an undamped singledegree-of-freedom (SDOF) system subjected to a sinusoidal pulse as a function of natural period. In addition, design response spectra for pulse-like ground motions are proposed.

It is suggested that the pulse-like ground motions, in the near-fault region, have great impact on the building seismic design. However, the theoretical study on the building response to the pulse-like ground motions input is not sufficiently clarified yet. In this study, the time at maximum response is theoretically evaluated as important factor. Based on that, the theoretical solutions of response spectra, with single-degree-of-freedom system subject to the sinusoidal pulse input, are performed. In addition, we suggested the damping-modification-factor, in accordance with the time at maximum response and the pulse wave period - building period relations.

High-harmonic generation by non-collinear wave mixing in ionized media is demonstrated, in which the phase matching is realized in the direction of difference frequency mixing. The emission angle temporally varies depending on the ionization degree.

51st AIAA/SAE/ASEE Joint Propulsion Conference (July 27-29, 2015.Hilton Orlando) Orlando, Florida, USA., The pintle injector is a promising candidate of the propellant injection systems for a rocket engine with deep throttling capability which is essential for future space transportation missions. However, studies focusing on combustion phenomena in a rocket engine with a pintle injector is rather limited. In this study, optical measurements inside an ethanol/liquid oxygen rocket engine combustor with a planar pintle injector are conducted to clarify spray and flame structures in the pintle injector. Combustion tests where the chamber pressure is 0.36 to 0.40MPa and O/F is 1.15 to 1.40 are conducted. Effects of the injection configuration on spray structures are also evaluated. High speed imaging techniques are used to observe the flame and spray structures under hot fire conditions. Strong chemiluminescence of CH is observed in the vicinity of the impinging point of two propellants. Luminous flame is observed intermittently in the vicinity of the faceplate and the upper wall of the combustor with the direct observation of the flame. Characteristic exhaust velocity efficiency with oxidizercentered configuration is lower than fuel-centered configuration due to the large amount of propellant impinging on the upper wall of the combustor. Periodical phenomena with the frequency of approximately 300Hz which can be related to atomization processes are also observed., 形態: カラー図版あり, Physical characteristics: Original contains color illustrations, 資料番号: AC1600102000, レポート番号: AIAA 2015-3845

Referenceless, or self-reference, thermometry is a technique for mapping temperature differences in the region of interest (ROI) using the baseline phase estimated by extrapolating the field in the surrounding region for estimation (RFE) and subtracting the estimated baseline from the measured field. In the present work a self-reference technique based on complex field estimation using 2D polynomials comprising complex-valued coefficients was proposed and optimized. Numerical simulations with a Gaussian-profiled phase distribution demonstrated that the ROI radius had to be 2.3-2.5 times the standard deviation (SD) of the Gaussian function in order to keep the error below 8% of the peak phase change. The area ratio between the ROI and the RFE had to be larger than 2.0 to maintain the error level. Based on the simulations, and phantom and volunteer experiments, the complex-based method with independently optimized polynomial orders for the two spatial dimensions was compared with the phase-based method using the similar-order optimization strategy. The complex-based method appeared to be useful when phase unwrapping was not removed. Otherwise, the phase-based method yielded equivalent results with less polynomial orders.

Post-processing functions are used to reduce the imperfectness of physical random number generators. At FSE '07, Dichtl considered the case where the physical random number generator outputs independent bits that have a constant bias, and the post-processing function has fixed input and output lengths. In this paper, we first present a number of bounds on deg(n,m), which is a measure of the reduction of biases with n-bit input and m-bit output post-processing functions. We next show the exact values of deg(n,m) for a large class of (n,m) such that 1 ≤ m ≤ n ≤ 16, by using the bounds on deg(n,m) and a computer simulation. We finally discuss how we have derived these numerical values.

Our challenge was to design and implement a dedicated temperature imaging feedback control system to guide and assist in a thermal liver ablation procedure in a double-donut 0.5T open MR scanner. This system has near-real-time feedback capability based on a newly developed “self-referenced” temperature imaging method using “moving-slab” and complex-field-fitting techniques. Two phantom validation studies and one ex vivo experiment were performed to compare the newly developed self-referenced method with the conventional subtraction method and evaluate the ability of the feedback control system in the same MR scanner. The near-real-time feedback system was achieved by integrating the following primary functions: (1) imaging of the moving organ temperature; (2) on-line needle tip tracking; (3) automatic turn-on/off the heating devices; (4) a Windows operating system-based novel user-interfaces. In the first part of the validation studies, microwave heating was applied in an agar phantom using a fast spoiled gradient recalled echo in a steady state sequence. In the second part of the validation and ex vivo study, target visualization, treatment planning and monitoring, and temperature and thermal dose visualization with the graphical user interface of the thermal ablation software were demonstrated. Furthermore, MR imaging with the “self-referenced” temperature imaging method has the ability to localize the hot spot in the heated region and measure temperature elevation during the experiment. In conclusion, we have demonstrated an interactively controllable feedback control system that offers a new method for the guidance of liver thermal ablation procedures, as well as improving the ability to assist ablation procedures in an open MR scanner.

Techniques for the production of three kinds of 192Ir sources, i.e. hairpin, single-pin and seed, for brachytherapy were developed in Japan Atomic Energy Research Institute. Platinumiridium, alloy wire sheathed with platinum tube in advance were irradiated by the JRR-2 or JRR-3 reactor. The platinum tube cuts off beta-rays so as to minimize unnecessary radiation exposure to patients. Irradiation conditions were determined to obtain the radioactivity of 0.74 GBq (20 mCi) for a hairpin, 0.37 GBq (10 mCi) for a single-pin and 0.37 X 10(-1) GBq (1 mCi) for a seed, respectively, at the end of irradiation. Fluctuation in the linear distribution of the radioactivity along the hairpin source or the single-pin source was small enough on the viewpoint of its application. No significant impurity or surface contamination was observed in the source produced with pre-encapsulation. Seed targets were loaded in a polyethylene tube so as to be suitable for the new treatment technique of tumor. Irradiation of seed targets, packed alternately with nylon spacers in a polyethylene tube, was found to be satisfactory for preparing ribbon sources.