N=4 Instanton Calculus in Omega and R-R Backgrounds

We study the instanton calculus for N=4 super Yang-Mills theory in ten-dimensional Omega-background with the R-symmetry Wilson line gauge field. From the ADHM construction of instantons in the background, we obtain the deformed instanton effective action. For a certain case we get the effective action of N=2^* theory in the Omega-background. We also study the low-energy effective D(-1)-brane action for the D3/D(-1)-brane system in the R-R 3-form field strength backgrounds and find that the action agrees with the instanton effective action in the Omega-background.Comment: 28 page

N=2 Instanton Effective Action in Omega-background and D3/D(-1)-brane System in R-R Background

We study the relation between the ADHM construction of instantons in the Omega-background and the fractional D3/D(-1)-branes at the orbifold singularity of C \times C^2/Z_2 in Ramond-Ramond (R-R) 3-form field strength background. We calculate disk amplitudes of open strings connecting the D3/D(-1)-branes in certain R-R background to obtain the D(-1)-brane effective action deformed by the R-R background. We show that the deformed D(-1)-brane effective action agrees with the instanton effective action in the Omega-background.Comment: 35 pages, no figures, references adde

Instanton Calculus in Deformed N=4 Super Yang-Mills Theories

We study the instanton effective action of four-dimensional deformed N=4 supersymmetric Yang-Mills theory in the presence of constant, self-dual Ramond-Ramond (R-R) 3-form background in type IIB superstring theory. We compare the instanton effective action with the low-energy effective action on D(-1)-branes in the D3-D(-1) system in the same background. We find that discrepancy appears at the second order of the R-R background, which was also observed in deformed N=2 theory. This discrepancy is resolved if the action of the deformed gauge theory is improved by introducing a term with coordinate-dependent gauge coupling. We obtain the same deformed instanton effective action from super Yang-Mills theory in ten-dimensional Omega-background by dimensional reduction. We also discuss another type of R-R 3-form background which corresponds to massive deformations of the instanton effective action.Comment: 33 pages, no figures, typos corrected, version to appear in JHE

Postural control in persons with unilateral trans-femoral amputation using center of pressure : effect of socket types

片側大腿切断者の立位姿勢制御の特徴を明らかにする目的で,社会的活動レベルにある片側大腿切断者6名を対象に,静止立位と計算課題を同時に行った場合の姿勢制御について足圧中心点の変位を指標に検討した.事前に光刺激による反応時間を測定し計算課題が注意を分散させ得る課題であること確認した.足圧中心点の測定は,静止立位で10秒間行い,総軌跡長,矩形面積,健患位置,前後位置を算出し,健常者との比較,計算課題の有無による比較を行った.その結果,片側大腿切断者は健常者より総軌跡長,矩形面積が有意に大きかったが,両者とも二重課題の影響は受けなかった.また,片側大腿切断者は静止立位時足圧中心点が健側へ偏倚しており,二重課題時はさらに健側へ偏倚させる方略で姿勢制御していた.ソケットの違いによる比較では,坐骨収納型ソケットより四辺形ソケット使用者の方が安定する傾向にあった.The purpose of this study was to clarify the characteristics of postural control in persons with amputation and to examine the influence of two socket types. A group of six men with unilateral trans-femoral amputation (amputation group, AG) participated in this study. A group of twenty healthy men (control group, CG), matched for age, were also tested. The subjects performed two tests as follows: (1)quiet upright standing task (single-task, ST) and (2)upright standing and concurrent attention-demanding task (calculation task) (dual-task, DT). The center of pressure (CP) was measured using a force platform during the two conditions. In addition, the trajectory length (LNG), the rectilinear area (REA), and the lateral and fore-aft direction were calculated. Significant differences were observed between AG and CG concerning LNG and REA in ST (p<.05). But the effect of a cognitive task on the efficiency of postural control was not shown in either group. In contrast with CG, CP in AG showed a movement to the non-amputation side in the lateral direction (p<.05). Further, CP was moved to the non-amputation side as an effect of the cognitive task (p<.05). In regard to the effect by socket type, there was a tendency for LNG and REA in the quadrilateral socket to be smaller than in the ischial-ramal containment socket