Introduction of JWG activities next API 610

Kojima 한국소음진동공학회 2009 한국소음진동공학회 강습회 Vol.2009 No.3

Extension of Completely Positive Cone Relaxation to Moment Cone Relaxation for Polynomial Optimization

Arima, N.,Kim, S.,Kojima, M. Springer Science + Business Media 2016 Journal of optimization theory and applications Vol.168 No.3

<P>We propose the moment cone relaxation for a class of polynomial optimization problems to extend the results on the completely positive cone programming relaxation for the quadratic optimization model by Arima, Kim and Kojima. The moment cone relaxation is constructed to take advantage of sparsity of the polynomial optimization problems, so that efficient numerical methods can be developed in the future. We establish the equivalence between the optimal value of the polynomial optimization problem and that of the moment cone relaxation under conditions similar to the ones assumed in the quadratic optimization model.</P>

Designing matching mechanisms under constraints: An approach from discrete convex analysis

Kojima, Fuhito,Tamura, Akihisa,Yokoo, Makoto Elsevier 2018 JOURNAL OF ECONOMIC THEORY Vol.176 No.-

<P><B>Abstract</B></P> <P>We consider two-sided matching problems where agents on one side of the market (hospitals) are required to satisfy certain distributional constraints. We show that when the preferences and constraints of the hospitals can be represented by an M<SUP>♮</SUP>-concave function, (i) the generalized Deferred Acceptance (DA) mechanism is strategyproof for doctors, (ii) it produces the doctor-optimal stable matching, and (iii) its time complexity is proportional to the square of the number of possible contracts. Furthermore, we provide sufficient conditions under which the generalized DA mechanism satisfies these desirable properties. These conditions are applicable to various existing works and enable new applications as well, thereby providing a recipe for developing desirable mechanisms in practice.</P>

Effective Use of Hedging in Scientific Manuscripts: Advice to Non-Native English-Speaking Researchers

Kojima Takako,Popiel Helena A. 대한의학회 2023 Journal of Korean medical science Vol.38 No.17

Risk management of a company

Kojima Toshiro 한국재난정보학회 2013 한국재난정보학회 학술대회 Vol.2013 No.2

Dynamic Coronary 320-Row CT Angiography Using Low-Dose Contrast and Temporal Maximum Intensity Projection: A Comparison with Standard Coronary CT Angiography

Kojima Tsukasa,Yamasaki Yuzo,Kamitani Takeshi,Yabuuchi Hidetake,Shirasaka Takashi,Shimomiya Yamato,Kondo Masatoshi,Hamasaki Hiroshi,Kato Toyoyuki,Nagao Michinobu,Honda Hiroshi 아시아심장혈관영상의학회 2019 Cardiovascular Imaging Asia Vol.3 No.1

Objective: The smallest diagnostically sufficient amount of contrast media (CM) should be used for coronary computed tomography angiography (CCTA) to minimize the risk of contrast- induced nephrotoxicity in elderly patients with coronary artery disease. The purpose of this study was to propose dynamic-CCTA using a low dose of CM and temporal maximum intensity projection (TMIP) and to investigate its image quality compared to standard-CCTA. Materials and Methods: Participants comprised 30 patients with coronary artery disease who underwent dynamic-CCTA and standard-CCTA using 320-row CT. Dynamic-CCTA was continuously performed at mid-diastole throughout 15–25 cardiac cycles after bolus injection of CM [103 mg iodine/kg body weight (mgI/kg)]. TMIP-CCTA was reconstructed from three-phase dynamic-CCTA data, including a phase with peak enhancement of the ascending aorta. Standard-CCTA was performed using a standard CM dose (259 mgI/kg). Image quality of both TMIP-CCTA and standard-CCTA was analyzed. Results: The amount of CM used in TMIP-CCTA and standard-CCTA was 16.2±2.6 mL and 40.1±7.3 mL, respectively. The mean effective radiation dose was not significantly different between the two methods. Mean coronary attenuation was significantly lower for TMIP-CCTA than standard-CCTA [346.9±82.8 Hounsfield units (HU) vs. 455.4±75.3 HU, p<0.05]. Image noise was significantly lower for TMIP-CCTA than standard-CCTA (20.0±3.2 HU vs. 28.1± 3.6 HU, p<0.05). There were no differences in signal-to-noise ratio and visual assessment scores between the two methods. Conclusion: TMIP-CCTA can be performed using more than 50% less CM with the same image quality as standard-CCTA.

Proper Scholarly Writing for Non-Native English-Speaking Authors: Choosing Active and Passive Voice, Rewording, and Refining Texts

Kojima Takako,Popiel Helena A. 대한의학회 2022 Journal of Korean medical science Vol.37 No.44

Heart rate variability and behavioral alterations during prepartum period in dairy cows as predictors of calving: a preliminary study

Kojima Tomoki,Huang Chen-Yu,Yayou Ken-ichi 아세아·태평양축산학회 2024 Animal Bioscience Vol.37 No.5

Objective: Parturition is crucial for dams, their calves, and cow managers. The prediction of calving time, which assists cow managers to decide on the relocation of cows to maternity pens and necessity of human supervision, is a pivotal aspect of livestock farming. However, existing methods of predicting calving time in dairy cows based on hormonal changes and clinical symptoms are time-consuming and yield unreliable predictions. Accordingly, we investigated whether heart rate variability (HRV) which is a non-invasive assessment of autonomic nervous system (ANS) activity and behavior during the prepartum period would be useful for predicting calving time in dairy cows. Methods: Eight pregnant cows were surveilled under electrocardiogram and video recordings for HRV and behavioral analyses, respectively. HRV parameters in time and frequency domains were evaluated. A 24-h time budget was calculated for each of six types of behavior (standing and lying with or without rumination, sleeping, and eating). Results: Heart rate on calving day is considerably higher than those recorded on the days preceding calving. Low frequency power declined, whereas high frequency power escalated on the calving day compared to the period between 24 and 48 h before calving. The time budget for ruminating while lying decreased and that while standing increased markedly on the calving day compared to those allocated on the preceding days; nonetheless, the total time budget for ruminating did not differ during the prepartum period. Conclusion: We elucidated the ANS activity and behavioral profiles during prepartum period. Our results confirm that HRV parameters and behavior are useful for predicting calving time, and interestingly indicate that the time budget for ruminating while standing (or lying) may serve as a valuable predictor of calving. Collectively, our findings lay the foundation for future investigations to determine other potential predictors and formulate an algorithm for predicting calving time.

Formation of a Ruthenium(IV)-Oxo Complex by Electron-Transfer Oxidation of a Coordinatively Saturated Ruthenium(II) Complex and Detection of Oxygen-Rebound Intermediates in C–H Bond Oxygenation

Kojima, Takahiko,Nakayama, Kazuya,Ikemura, Kenichiro,Ogura, Takashi,Fukuzumi, Shunichi American Chemical Society 2011 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.133 No.30

<P>A coordinatively saturated ruthenium(II) complex having tetradentate tris(2-pyridylmethyl)amine (TPA) and bidentate 2,2′-bipyridine (bpy), [Ru(TPA)(bpy)]<SUP>2+</SUP> (<B>1</B>), was oxidized by a Ce(IV) ion in H<SUB>2</SUB>O to afford a Ru(IV)-oxo complex, [Ru(O)(H<SUP>+</SUP>TPA)(bpy)]<SUP>3+</SUP> (<B>2</B>). The crystal structure of the Ru(IV)-oxo complex <B>2</B> was determined by X-ray crystallography. In <B>2</B>, the TPA ligand partially dissociates to be in a facial tridentate fashion and the uncoordinated pyridine moiety is protonated. The spin state of <B>2</B>, which showed paramagnetically shifted NMR signals in the range of 60 to −20 ppm, was determined to be an intermediate spin (<I>S</I> = 1) by the Evans’ method with <SUP>1</SUP>H NMR spectroscopy in acetone-<I>d</I><SUB>6</SUB>. The reaction of <B>2</B> with various oraganic substrates in acetonitrile at room temperature afforded oxidized and oxygenated products and a solvent-bound complex, [Ru(H<SUP>+</SUP>TPA)(bpy)(CH<SUB>3</SUB>CN)], which is intact in the presence of alcohols. The oxygenation reaction of saturated C–H bonds with <B>2</B> proceeds by two-step processes: the hydrogen abstraction with <B>2</B>, followed by the dissociation of the alcohol products from the oxygen-rebound complexes, Ru(III)-alkoxo complexes, which were successfully detected by ESI-MS spectrometry. The kinetic isotope effects in the first step for the reaction of dihydroanthrathene (DHA) and cumene with <B>2</B> were determined to be 49 and 12, respectively. The second-order rate constants of C–H oxygenation in the first step exhibited a linear correlation with bond dissociation energies of the C–H bond cleavage.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jacsat/2011/jacsat.2011.133.issue-30/ja2037645/production/images/medium/ja-2011-037645_0013.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ja2037645'>ACS Electronic Supporting Info</A></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ja2037645'>ACS Electronic Supporting Info</A></P>

Photochemical Activation of Ruthenium(II)–Pyridylamine Complexes Having a Pyridine-<i>N</i>-Oxide Pendant toward Oxygenation of Organic Substrates

Kojima, Takahiko,Nakayama, Kazuya,Sakaguchi, Miyuki,Ogura, Takashi,Ohkubo, Kei,Fukuzumi, Shunichi American Chemical Society 2011 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.133 No.44

<P>Ruthenium(II)–acetonitrile complexes having η<SUP>3</SUP>-tris(2-pyridylmethyl)amine (TPA) with an uncoordinated pyridine ring and diimine such as 2,2′-bipyridine (bpy) and 2,2′-bipyrimidine (bpm), [Ru<SUP>II</SUP>(η<SUP>3</SUP>-TPA)(diimine)(CH<SUB>3</SUB>CN)]<SUP>2+</SUP>, reacted with <I>m</I>-chloroperbenzoic acid to afford corresponding Ru(II)–acetonitrile complexes having an uncoordinated pyridine-<I>N</I>-oxide arm, [Ru<SUP>II</SUP>(η<SUP>3</SUP>-TPA-O)(diimine)(CH<SUB>3</SUB>CN)]<SUP>2+</SUP>, with retention of the coordination environment. Photoirradiation of the acetonitrile complexes having diimine and the η<SUP>3</SUP>-TPA with the uncoordinated pyridine-<I>N</I>-oxide arm afforded a mixture of [Ru<SUP>II</SUP>(TPA)(diimine)]<SUP>2+</SUP>, intermediate-spin (<I>S</I> = 1) Ru(IV)–oxo complex with uncoordinated pyridine arm, and intermediate-spin Ru(IV)–oxo complex with uncoordinated pyridine-<I>N</I>-oxide arm. A Ru(II) complex bearing an oxygen-bound pyridine-<I>N</I>-oxide as a ligand and bpm as a diimine ligand was also obtained, and its crystal structure was determined by X-ray crystallography. Femtosecond laser flash photolysis of the isolated <I>O</I>-coordinated Ru(II)–pyridine-<I>N</I>-oxide complex has been investigated to reveal the photodynamics. The Ru(IV)–oxo complex with an uncoordinated pyridine moiety was alternatively prepared by reaction of the corresponding acetonitrile complex with 2,6-dichloropyridine-<I>N</I>-oxide (Cl<SUB>2</SUB>py-O) to identify the Ru(IV)–oxo species. The formation of Ru(IV)–oxo complexes was concluded to proceed via intermolecular oxygen atom transfer from the uncoordinated pyridine-<I>N</I>-oxide to a Ru(II) center on the basis of the results of the reaction with Cl<SUB>2</SUB>py-O and the concentration dependence of the consumption of the starting Ru(II) complexes having the uncoordinated pyridine-<I>N</I>-oxide moiety. Oxygenation reactions of organic substrates by [Ru<SUP>II</SUP>(η<SUP>3</SUP>-TPA-O)(diimine)(CH<SUB>3</SUB>CN)]<SUP>2+</SUP> were examined under irradiation (at 420 ± 5 nm) and showed selective allylic oxygenation of cyclohexene to give cyclohexen-1-ol and cyclohexen-1-one and cumene oxygenation to afford cumyl alcohol and acetophenone.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jacsat/2011/jacsat.2011.133.issue-44/ja207572z/production/images/medium/ja-2011-07572z_0005.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ja207572z'>ACS Electronic Supporting Info</A></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ja207572z'>ACS Electronic Supporting Info</A></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ja207572z'>ACS Electronic Supporting Info</A></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ja207572z'>ACS Electronic Supporting Info</A></P>