Relativistic stars in f(R) gravity, and absence thereof

Several f(R) modified gravity models have been proposed which realize the correct cosmological evolution and satisfy solar system and laboratory tests. Although nonrelativistic stellar configurations can be constructed, we argue that relativistic stars cannot be present in such f(R) theories. This problem appears due to the dynamics of the effective scalar degree of freedom in the strong gravity regime. Our claim thus raises doubts on the viability of f(R) models.Comment: 9 pages, 7 figures, v2: references added, minor corrections, version accepted for publication in PR

Can higher curvature corrections cure the singularity problem in f(R) gravity?

Although $f(R)$ modified gravity models can be made to satisfy solar system and cosmological constraints, it has been shown that they have the serious drawback of the nonexistence of stars with strong gravitational fields. In this paper, we discuss whether or not higher curvature corrections can remedy the nonexistence consistently. The following problems are shown to arise as the costs one must pay for the $f(R)$ models that allow for neutrons stars: (i) the leading correction must be fine-tuned to have the typical energy scale $\mu \lesssim 10^{-19}$ GeV, which essentially comes from the free fall time of a relativistic star; (ii) the leading correction must be further fine-tuned so that it is not given by the quadratic curvature term. The second problem is caused because there appears an intermediate curvature scale and laboratory experiments of gravity will be under the influence of higher curvature corrections. Our analysis thus implies that it is a challenge to construct viable $f(R)$ models without very careful and unnatural fine-tuning.Comment: 9 pages, 9 figures, v2: minor modifications, version accepted for publication in Phys. Rev.

自己くま取り効果を応用したリニア電磁アクチュエータの研究

取得学位：博士(工学)，学位授与番号：博乙第95号，学位授与年月日：平成7年3月25日,学位授与年：199

Blood pressure in heart failure management and prevention

Hypertension is a leading cause of heart failure and other cardiovascular diseases. Its role in the pathogenesis of heart failure with reduced ejection fraction (HFrEF) differs from that in heart failure with preserved ejection fraction (HFpEF). Moreover, rigorous blood pressure control may reduce the incidence of heart failure. However, once heart failure develops, prognosis is affected by blood pressure, which may differ between patients with and without heart failure. Therefore, the association between guideline-directed medical therapy (GDMT) for heart failure and its uptitration must be considered for blood pressure management and should not be overlooked. Heart failure medications affect the blood pressure and efficacy per baseline blood pressure value. This review discusses the potential mechanisms by which hypertension leads to HFrEF or HFpEF, the impact of hypertension on incident heart failure, and the recommended approaches for blood pressure management in patients with heart failure. </p

Analysis of the Wheeler-DeWitt Equation beyond Planck Scale and Dimensional Reduction

We solve the Wheeler-DeWitt equation for {\it four}-dimensional Einstein gravity as an expansion in powers of the Planck mass by means of a heat kernel regularization. Our results suggest that in the universe with a very small radius or with a very large curvature beyond a Planck scale expectation values of operators are reduced to calculations in a path integral representation of {\it three}-dimensional Einstein gravity.Comment: 9 pages, latex file, KOBE-TH-94-0

Loss of Parp-1 affects gene expression profile in a genome-wide manner in ES cells and liver cells

BACKGROUND: Many lines of evidence suggest that poly(ADP-ribose) polymerase-1 (Parp-1) is involved in transcriptional regulation of various genes as a coactivator or a corepressor by modulating chromatin structure. However, the impact of Parp-1-deficiency on the regulation of genome-wide gene expression has not been fully studied yet. RESULTS: We employed a microarray analysis covering 12,488 genes and ESTs using mouse Parp-1-deficient (Parp-1(-/-)) embryonic stem (ES) cell lines and the livers of Parp-1(-/- )mice and their wild-type (Parp-1(+/+)) counterparts. Here, we demonstrate that of the 9,907 genes analyzed, in Parp-1(-/- )ES cells, 9.6% showed altered gene expression. Of these, 6.3% and 3.3% of the genes were down- or up-regulated by 2-fold or greater, respectively, compared with Parp-1(+/+ )ES cells (p < 0.05). In the livers of Parp-1(-/- )mice, of the 12,353 genes that were analyzed, 2.0% or 1.3% were down- and up-regulated, respectively (p < 0.05). Notably, the number of down-regulated genes was higher in both ES cells and livers, than that of the up-regulated genes. The genes that showed altered expression in ES cells or in the livers are ascribed to various cellular processes, including metabolism, signal transduction, cell cycle control and transcription. We also observed expression of the genes involved in the pathway of extraembryonic tissue development is augmented in Parp-1(-/- )ES cells, including H19. After withdrawal of leukemia inhibitory factor, expression of H19 as well as other trophoblast marker genes were further up-regulated in Parp-1(-/- )ES cells compared to Parp-1(+/+ )ES cells. CONCLUSION: These results suggest that Parp-1 is required to maintain transcriptional regulation of a wide variety of genes on a genome-wide scale. The gene expression profiles in Parp-1-deficient cells may be useful to delineate the functional role of Parp-1 in epigenetic regulation of the genomes involved in various biological phenomena

Risk factors for initial antibiotic treatment failure in patients with aspiration pneumonia

Sulbactam/ampicillin （SBT/ABPC） and ceftriaxone （CTRX） are the initial antibiotics recommended for treating aspiration pneumonia without risk factors for drug-resistant pathogens. However, the condition of some patients does not improve with these antibiotics. Therefore, we investigated the new risk factors associated with failure of initial antibiotic treatment in patients with aspiration pneumonia. This study included 487 patients diagnosed with aspiration pneumonia who received initial antibiotic treatment with SBT/ABPC or CTRX, and were hospitalized at the Respiratory Medicine Department of the Yokohama City Minato Red Cross Hospital. The outcome was initial antibiotic treatment failure, which was defined as a change from initial to secondary antibiotic treatment. The characteristics of patients with and without antibiotic treatment failure were compared using univariate analyses, and significant independent risk factors for the initial antibiotic treatment failure were selected using multivariate analyses. The mean age of the patients was 84.1 ± 9.6 years; 302 （62％） of them were men and 93 patients experienced antibiotic treatment failure. Logistic regression analysis extracted no restriction of diet on admission （odds ratio ［OR］, 3.23; 95% confidence interval ［CI］, 1.35-7.74）, history of hospitalization due to aspiration pneumonia （OR, 1.81; 95％CI, 1.12-2.93）, the severity of pneumonia （OR, 1.37; 95％CI, 1.01-1.86）, and C-reactive protein （CRP） level （OR, 1.26; 95％CI, 1.09-1.45） as risk factors for initial antibiotic treatment failure. Our results suggested that no restriction of diet on admission, history of hospitalization due to aspiration pneumonia, severity of pneumonia, and increased CRP levels were the risk factors associated with failure of initial antibiotic treatment in patients with aspiration pneumonia. These factors will be useful for determining an effective initial treatment strategy for patients with aspiration pneumonia