Spontaneous Gauge Symmetry Breaking in a Non-Supersymmetric D-brane Model

We investigate a D-brane system in which spontaneous gauge symmetry breaking occurs. The system consists of four D3-branes and three anti-D7-branes at C^3/Z_3 singularity. The singularity is blown up by vacuum expectation values of the states of twisted closed string, whose effects appear as Fayet-Iliopoulos terms in low-energy effective field theory. We derive an effective potential for scalar fields in four-dimensional effective field theory using the technique of superstring world-sheet theory. Since there is no supersymmetry in this system, one-loop masses for some scalar fields are considered. We find some stationary and stable vacua in which the original U(2) x U(1)_1 x U(1)_2 x U(3) gauge symmetry is spontaneously broken to U(1) x U(1)' x U(3) gauge symmetry. Both Fayet-Iliopoulos terms and one-loop masses are necessary for the existence of such vacua. We carefully investigate a geometrical aspect of the gauge symmetry breaking. We show that the gauge symmetry breaking is understood as the separation of D3-branes. Some implications to the possibility of low-scale string models are also discussed.Comment: 13 papges, 2 figure

Flavor structure and coupling selection rule from intersecting D-branes

We study flavor structure and the coupling selection rule in intersecting D-brane configurations. We formulate the selection rule for Yukawa couplings and its extensions to generic n-point couplings. We investigate the possible flavor structure, which can appear from intersecting D-brane configuration, and it is found that their couplings are determined by discrete abelian symmetry. Our studies on the flavor structure and the coupling selection rule show that the minimal matter content of the supersymmetric standard model would have difficulty to derive realistic Yukawa matrices from stringy 3-point couplings at the tree-level. However, extended models have a richer structure, leading to non-trivial mass matrices.Comment: 28 pages, latex, 5 figure

An Analysis of Transient Stresses Produced around Cavities of Arbitrary Shape during the Passage of Traveling Waves

The present paper is concerned with an application of the integral equation method to the analysis of the transient stresses produced around cavities of arbitrary shape, which are excavated in an infinite elastic medium and subject to longitudinal and transverse waves of arbitrary pressure-time history. The method used in the present paper consists of such a technique as devising a solution for the transient problem from the superposition of appropriate steady-state solutions, which are obtained by use of the integral equation. The validity of the present method is demonstrated by several examples such as : (1) steady-state stresses around a circular cavity due to longitudinal and transverse waves, (2) transient stresses around a circular cavity due to stepform longitudinal and transverse waves, and a triangular-form longitudinal wave, (3) transient stresses around a horseshoe-shaped cavity due to a step-formed longitudinal wave. It may be concluded that the present method is advantageously applied to transient problems, specifically with boundaries of arbitrary shape and accompanied also with traveling waves of arbitrary pressue-time history

Search for Near-Infrared Pulsation of the Anomalous X-ray Pulsar 4U 0142+61

We have searched for pulsation of the anomalous X-ray pulsar (AXP) 4U 0142+61 in the K' band ($\lambda_{\rm eff} = 2.11$ $\mu$m) using the fast-readout mode of IRCS at the Subaru 8.2-m telescope. We found no significant signal at the pulse frequency expected by the precise ephemeris obtained by the X-ray monitoring observation with RXTE. Nonetheless, we obtained a best upper limit of 17% (90% C.L.) for the root-mean-square pulse fraction in the K' band. Combined with i' band pulsation (Dhillon et al. 2005), the slope of the pulsed component ($F_\nu \propto \nu^\alpha$) was constrained to $\alpha > -0.87$ (90% C.L.) for an interstellar extinction of $A_{V} = 3.5$.Comment: 11 pages, 3 figures, Accepted for publication in PAS

Infection-prevention performance of local exhaust ventilation under three different underfloor air distribution systems during a face-to-face conversation

Yoshihara J., Yamanaka T., Choi N., et al. Infection-prevention performance of local exhaust ventilation under three different underfloor air distribution systems during a face-to-face conversation. Building and Environment 265, 111911 (2024); https://doi.org/10.1016/j.buildenv.2024.111911.This study proposes using a local exhaust ventilation system (LEV) to prevent airborne infections, especially for short-range conversations. We compared the performance of a hood in three different underfloor air distribution systems (UFAD): floor-supply displacement ventilation (FSDV), horizontal flow-type floor diffuser (HFD), and swirling flow-type floor diffuser (SFD). Two situations were considered: Case A, a consulting room, and Case B, a restaurant or meeting room. The difference in infection risk assessment between using CO2 and artificial saliva particles as tracers of exhaled breath was also discussed. Results indicate that the distribution of exhaled air and infection risk for doctors decreased in the order FSDV < HFD < SFD. Although the effect of introducing hoods was confirmed to a certain degree for the three ventilation methods in Case A, the effect of the hoods on the quanta concentration of the facing person was small in Case B. Comparing airborne infection risks between gas and particles, particle-based airborne infection was smaller in the FSDV due to the more significant impact of particle adhesion and falling. As a limitation, the ventilation rate in the experiment was 1000 m3/h (50 ACH). Therefore, the air supply method had a more significant impact on the results than the hood method. A practical implication of this experiment is that even under high ventilation volumes (50 ACH), the FSDV can reduce the horizontal distribution of the patient's exhaled air and prevent airborne infection. These results should be adapted to smaller spaces such as examination rooms and meeting rooms

Age‐related changes in muscle thickness, echo intensity and shear modulus of the iliocapsularis

Purpose: This study aimed to clarify age-related changes in the iliocapsularis (IC) using indicators of quantity, quality, and mechanical properties. We also compared the age-related changes in the IC and other hip muscles. Methods: Eighty-seven healthy women (ages: 21–82 years, mean age: 45.9 ± 15.7 years) participated in the experiment. We measured thickness, echo intensity, and shear modulus of the IC, iliacus muscle, rectus femoris, and the thickness and shear modulus of the hip joint capsule. Spearman's rank correlation coefficient was used to measure the association of age with variables measured in the muscles and joint capsule. Results: Thickness of the iliacus muscle and rectus femoris decreased significantly with age, but the thickness of the IC and hip joint capsule showed no significant correlation. The echo intensities of the IC, iliacus muscle, and rectus femoris were positively correlated, which increased with age. Furthermore, the shear modulus of the iliacus, rectus femoris, and hip joint capsule showed an increase with age, whereas the shear modulus of the IC exhibited no correlation with age. Conclusion: The muscle quality of the IC changed significantly, unlike that of the iliacus or rectus femoris. Additionally, the correlation with echo intensity was relatively weaker in the IC compared with the iliacus or rectus femoris

A procedure to determine the optimum imaging parameters for atomic/molecular resolution frequency modulation atomic force microscopy

We propose a general procedure to determine the optimum imaging parameters (spring constant and oscillation amplitude) to obtain the optimum resolution in frequency modulation atomic force microscopy. We calculated the effective signal-to-noise ratio for various spring constants and oscillation amplitudes, based on the measurement of frequency shift and energy dissipation versus tip-sample distance curves, to find the optimum. We applied this procedure for imaging a lead phthalocyanine (PbPc) thin film on a MoS2(0001) substrate, and found that the optimum parameters were about 5 N/m and 20 nm, respectively. An improved signal-to-noise ratio was attained in a preliminary experiment using parameters which were close to the calculated optimum

Rat small intestinal transplantation: a comparison of the cuff and hand-suture methods.

The rat model is ideal for investigating various reactions to small intestinal transplantation (SIT). The conventional surgical model (hand-suture method), however, requires microsurgical techniques and remains difficult for beginners to perform at a high success rate. We have employed the SIT model using the cuff method, by which the vessels are anastomosed without sutures. All of the fellows who used the hand-suture models needed over 8 +/- 5.8 months until they achieved a 70% success rate. In contrast, the fellows employing the cuff method mastered SIT models after 6 weeks' practice. The cuff technique is a simplified and quickly mastered alternative to the hand-suture method that may be desirable for researchers who wish to apply the method to SIT experiments and whose primary purpose is not microsurgery.</p

Structured Water Molecules on Membrane Proteins Resolved by Atomic Force Microscopy

Water structuring on the outer surface of protein molecules called the hydration shell is essential as well as the internal water structures for higher-order structuring of protein molecules and their biological activities in vivo. We now show the molecular-scale hydration structure measurements of native purple membrane patches composed of proton pump proteins by a noninvasive three-dimensional force mapping technique based on frequency modulation atomic force microscopy. We successfully resolved the ordered water molecules localized near the proton uptake channels on the cytoplasmic side of the individual bacteriorhodopsin proteins in the purple membrane. We demonstrate that the three-dimensional force mapping can be widely applicable for molecular-scale investigations of the solid–liquid interfaces of various soft nanomaterials

Serum type IV collagen-degrading enzyme in hepatocellular carcinoma with metastasis.

The activity of serum type IV collagen-degrading enzyme was measured in 18 patients with hepatocellular carcinoma (HCC). The enzyme activity was significantly higher, in HCC patients with a tumor thrombus in the portal vein than in healthy controls, liver cirrhosis patients and HCC patients without a tumor thrombus. Moreover, the activity in HCC patients with lung metastasis tended to be higher than that in HCC patients without lung metastasis. The activity of serum type IV collagen-degrading enzyme did not correlate with tumor size, serum alpha-fetoprotein level, or macroscopic classification of tumor growth. These results suggest that the activity of serum type IV collagen-degrading enzyme represents the metastatic potential or the ongoing metastatic activity of HCC. The enzyme is a useful serum marker of metastasis from HCC.</p