Influence of head shape of solid body plunging into water on splash formation

Abstract  

We experimentally investigated the influence of a head shape of a solid body plunging into water on splash formation. Three different head shapes were tested: a hemisphere, cone, and circular cylinder. A hemisphere as a tail shape is common to all three head shapes. We captured images of splash formation using a high-speed CMOS camera. We found that a film flow generated at an early stage when a body impacts the water surface influences subsequent events until the splash sequence is completed. We explain the origin of the film flow according to the principle of conservation of momentum. The film flow as the primary splash originates from water displaced by the head. The meridian line, which connects the head to the tail of the body, affects separation of the film flow and causes the secondary splash. The air cavity generated when the body plunges into the water is also influenced by the head shape. The tertiary splash is formed by a reaction of the air cavity, which is detached from the body. We found that the secondary dome-type splash obstructs growth of the tertiary splash. Thus, we conclude that the head shape affects all events of the splash.     

Study of Strangeness Photoproduction on the Neutron in the Threshold Region

Photoproduction of the neutral kaon on the deuteron has been investigated at the Research Center for Electron Photon Science, Tohoku University. We constructed the Neutral Kaon Spectrometer-2 for the detection of charged particles from the decay of the neutral kaon and the hyperon. We obtained a momentum distribution of K ⁰ with the inclusive measurement. It was consistent with the previous measurement. The total cross section of γ + d → K ⁰ + Λ + p was estimated from the measured integral cross section of γ + d → Λ + X. The total cross section with respect to the photon energy was compared with the theoretical calculations. It favored the Saclay-Lyon A model calculation with the ratio of the neutral to charged coupling constants of the axial-vector meson, K ₁, as ~ ?1.5. The energy dependence and the magnitude of the total cross section were similar to the total cross section of γ + p → K ⁺ Λ.     

Three-dimensional susceptibility-weighted imaging at 3 T using various image analysis methods in the estimation of grading intracranial gliomas

Object

Although three-dimensional (3D), high-spatial resolution susceptibility-weighted imaging (SWI) appears to be valuable in the evaluation of central nervous system gliomas, several evaluation methods are proposed in the literature. The purpose of this study was to evaluate the use of 3D SWI for grading intracranial gliomas with various analysis methods.

Materials and Methods

Twenty-three patients suspected of having gliomas participated in this study. SWI was performed in addition to conventional MR sequences. In 15 cases, post-gadolinium enhanced SWI was also obtained. Imaging evaluation criteria were conventional grade, hypointensity ratio in the tumor-dominant structure of hypointensity on SWI (hemorrhage or vascular structure) and presence of abnormal enhancement surrounding the tumor.

Results

Mean grading scores of conventional grade showed no statistically significant difference among WHO grades. Mean grading scores of hypointensity ratios in the tumor were higher for WHO Grades 3 and 4 than for lower grade tumors (P=.05, Mann–Whitney U test). Hemorrhagic foci were more frequently seen in the higher grade tumor. Post-contrast susceptibility-weighted images of five of 11 WHO Grade 3 and 4 cases showed bright enhancement surrounding the tumor, suggesting a breakdown of the blood–brain barrier.

Conclusions

SWI at 3 T may be a useful method to analyze the structural characteristics of gliomas and to evaluate pathology in vivo. Assessment of hypointensity ratios in the glioma was the most preferable method in grading glioma. However, more studies, specifically concerning a suitable method for image analysis, are needed to establish SWI at 3 T as a useful tool in clinical routine.     

Japanese version of voice handicap index for subjective evaluation of voice disorder

Recently, the Voice Handicap Index (VHI), developed in the United States, has been highlighted as a means to assess a patient's perceptions of the severity of his or her voice disorder. The VHI is based on a self-administered questionnaire that quantifies the degree of a patient's disability related to his/her voice disorder. The questionnaire was translated into Japanese and applied to Japanese patients with various kinds of disordered voice or dysphonia. The results were analyzed and the usefulness discussed. In this study, 546 patients (281 males and 265 females) were included. Mean VHI scores were 36.2/120 in males and 44.1/120 in females. In the male patients, VHI scores were the highest among teens. However, VHI scores did not vary with age in the female patients. Patients with vocal fold paralysis, functional dysphonia, psychological dysphonia, and spasmodic dysphonia showed relatively high VHI scores, whereas those with laryngeal granuloma and laryngopharyngeal reflux disease showed low scores. In most diseases, functional and physiological scores were higher than emotional scores. In any treated patients, those with vocal nodule, vocal polyp, polypoid vocal fold, and recurrent laryngeal nerve paralysis, VHI scores decreased after therapeutic intervention. These findings suggest that the Japanese VHI is a useful tool for monitoring a patient's psychological status, choosing appropriate treatment, and assessing the therapeutic outcome.     

Vector WIMP miracle

Weakly interacting massive particle (WIMP) is well known to be a good candidate for dark matter, and it is also predicted by many new physics models beyond the standard model at the TeV scale. We found that, if the WIMP is a vector particle (spin-one particle) which is associated with some gauge symmetry broken at the TeV scale, the Higgs mass is often predicted to be 120–125 GeV, which is very consistent with the result of Higgs searches recently reported by ATLAS and CMS Collaborations at the Large Hadron Collider experiment. In this Letter, we consider the vector WIMP using a non-linear sigma model in order to confirm this result as general as possible in a bottom-up approach. Near-future prospects to detect the vector WIMP at both direct and indirect detection experiments of dark matter are also discussed.     

Combined volumetric T1, T2 and secular-T2 quantitative MRI of the brain: age-related global changes (preliminary results)

The combined T1, T2 and secular-T2 pixel frequency distributions of 24 adult human brains were studied in vivo using a technique based on the mixed-TSE pulse sequence, dual-space clustering segmentation and histogram gaussian decomposition. Pixel frequency histograms of whole brains and the four principal brain compartments were studied comparatively and as function of age. For white matter, the position of the T1 peak correlates with age (R2 =.7868) when data are fitted to a quadratic polynomial. For gray matter, a weaker age correlation is found (R2 =.3687). T2 and secular-T2 results are indicative of a weaker correlation with age. The technique and preliminary results presented herein may be useful for characterizing normal as well as abnormal aging of the brain, and also for comparison with the results obtained with alternative quantitative MRI methodologies.     

Pseudotwistors

We deal with the Hermitian Hurwitz pairs of signature (, s), + s = 5 + 4, | + 1 – s| = 2 + 4m;, m = 0, 1,.... We introduce the Hurwitz twistors for signature (3, 2) and its dual (1, 4) and we indicate the relationship between Hurwitz and Penrose twistors. The signatures (1, 8) and (7, 6) give rise to pseudotwistors and bitwistors, respectively. For pseudotwistors, we prove a counterpart of the Penrose theorem in the local version, on real analytic solutions of the related spinor equations versus harmonic forms, and in the semiglobal version, on holomorphic solutions of those equations versus Dolbeault cohomology groups. We prove an atomization theorem: There exist complex structures on isometric embeddings for the Hermitian Hurwitz pairs so that the embeddings are real parts of holomorphic mappings.     

Optical properties of six isomers of three dimensionally delocalized <Emphasis Type="Italic">π</Emphasis>-conjugated carbon nanocage

First-principles GW+Bethe-Salpeter method employing all-electron mixed basis approach is applied to hydrocarbon molecules consisting of 78–198 atoms and its theoretical accuracy and performance are evaluated. Based on the confirmed accuracy/reliability of our method, we simulated the UV–vis absorption spectra of previously reported six possible isomers [E. Kayahara et al., Nat. Chem. 4, 2694 (2013)]. We also attempted to identify the most stable isomers of recently synthesized ball-shaped carbon nanocages by taking into account available experimental spectra. The best agreement with the experiment is found for the most unstable isomer, labelled as T. Our simulation strongly suggests that the external experimental conditions such as solution and finite temperature affect stability.