Intrinsic optical gain of ultrathin silicon quantum wells from first-principles calculations

Optical gains of ultrathin Si(001) quantum wells are calculated from first principles, and found to be positive because of an intrinsic quantum confinement effect. The gain of the ultrathin silicon film is comparable to that of the bulk GaAs if the carrier density is large enough. The impact of surface structure of the silicon film on the efficiency of light emission is also investigated and we found that SiO2 crystal that forms a strainless connection with a Si(001) surface such as quartz enhances optical gain

Granzyme B as a novel factor involved in cardiovascular diseases

SummaryApoptosis plays an important role in cardiovascular diseases such as atherosclerosis, ischemic heart disease, and congestive heart failure. Previous studies have demonstrated that oxidative stress, physiological stress, and inflammatory cytokines such as tumor necrosis factor and Fas ligand are involved in apoptosis of cardiovascular system. We demonstrate that another apoptosis-related pathway, i.e. granzyme B/perforin system is involved in cardiovascular diseases. Expression of granzyme B, a member of serine protease family is increased in acute coronary syndrome, coronary artery disease with end-stage renal disease, and subacute stage of acute myocardial infarction. Although granzyme B is extensively researched in immunological disorders, the role of granzyme B/perforin system was not clear in the cardiovascular field. In addition, little is known regarding the inhibition of granzyme B system in the clinical situation. In this review we demonstrate recent findings of granzyme B in cardiovascular diseases and possible therapeutic applications of inhibiting the granzyme B/perforin system

Mysteries around the graph Laplacian eigenvalue 4

We describe our current understanding on the phase transition phenomenon of the graph Laplacian eigenvectors constructed on a certain type of unweighted trees, which we previously observed through our numerical experiments. The eigenvalue distribution for such a tree is a smooth bell-shaped curve starting from the eigenvalue 0 up to 4. Then, at the eigenvalue 4, there is a sudden jump. Interestingly, the eigenvectors corresponding to the eigenvalues below 4 are semi-global oscillations (like Fourier modes) over the entire tree or one of the branches; on the other hand, those corresponding to the eigenvalues above 4 are much more localized and concentrated (like wavelets) around junctions/branching vertices. For a special class of trees called starlike trees, we obtain a complete understanding of such phase transition phenomenon. For a general graph, we prove the number of the eigenvalues larger than 4 is bounded from above by the number of vertices whose degrees is strictly higher than 2. Moreover, we also prove that if a graph contains a branching path, then the magnitudes of the components of any eigenvector corresponding to the eigenvalue greater than 4 decay exponentially from the branching vertex toward the leaf of that branch.Comment: 22 page

An effect of left ventricular hypertrophy on mild-to-moderate left ventricular diastolic dysfunction

AbstractObjectivesLeft ventricular diastolic dysfunction (LVDD) is associated with a variety of medical conditions. Left ventricular hypertrophy (LVH) is one of the most common abnormalities that induce LVDD. However, it is unclear whether LVH is a predictor of future LVDD deterioration that leads to diastolic heart failure in patients who already have mild-to-moderate LVDD. In this study, we investigated the effect of LVH on LV diastolic function in mild-to-moderate LVDD patients.MethodsOf the patients with mild-to-moderate LVDD (Grade I and II) with preserved left ventricular ejection fraction (EF), 225 with LVH (LVH group) and 225 without LVH (non-LVH group) were consecutively selected. LVDD was defined by the abnormal patterns of Doppler mitral inflow and tissue Doppler. Left ventricular filling pressure (FP) was estimated by the following formula: 1.9 +1.24× [early mitral inflow velocity (E)/early mitral annular velocity (e')]. The Tei index was implemented to assess global (both systolic and diastolic) left ventricular function. Echocardiographic parameters for LVDD, such as isovolumic relaxation time (IVRT), were compared between the two groups.ResultsFP and Tei index were significantly higher in the LVH group compared to the non-LVH group [15.68 mmHg vs. 14.07 mmHg, P < 0.0001, and 0.58 vs. 0.53, P < 0.003, respectively]. IVRT was significantly longer in the LVH group than in the non-LVH group [103.93 ± 23.93 vs. 95.94 ± 20.16, P < 0.0001].ConclusionsIn mild-to-moderate LVDD patients, both FP and the Tei index were significantly higher when LVH was present. This may suggest LVH as a possible predictor for the future development of severe LVDD and diastolic heart failure

Non-LTE Line-Formation and Abundances of Sulfur and Zinc in F, G, and K Stars

Extensive statistical-equilibrium calculations on neutral sulfur and zinc were carried out, in order to investigate how the non-LTE effect plays a role in the determination of S and Zn abundances in F, G, and K stars. Having checked on the spectra of representative F-type stars (Polaris, Procyon, and alpha Per) and the Sun that our non-LTE corrections yield a reasonable consistency between the abundances derived from different lines, we tried an extensive non-LTE reanalysis of published equivalent-width data of S I and Zn I lines for metal-poor halo/disk stars. According to our calculations, S I 9212/9228/9237 lines suffer significant negative non-LTE corrections amounting to <~ 0.2--0.3 dex, while LTE is practically valid for S I 8683/8694 lines. Embarrassingly, as far as the very metal-poor regime is concerned, a marked discordance is observed between the [S/Fe] values from these two abundance indicators, in the sense that the former attains a nearly flat plateau (or even a slight downward bending) while the latter shows an ever-increasing trend with a further lowering of metallicity. The reason for this discrepancy is yet to be clarified. Regarding Zn, we almost confirmed the characteristic tendencies of [Zn/Fe] reported from recent LTE studies (i.e., an evident/slight increase of [Zn/Fe] with a decrease of [Fe/H] for very metal-poor/disk stars), since the non-LTE corrections for the Zn I 4722/4810 and 6362 lines (tending to be positive and gradually increasing towards lower [Fe/H]) are quantitatively of less significance (<~ 0.1 dex).Comment: 33 pages, 7 figures, PASJ, Vol. 57, No. 5 (2005) in pres

<CLINICAL>Clinical results of vital tooth bleaching : 1. In-office bleaching

In recent years, demand for esthetic dentistry has grown, particularly with respect to treatment of discolored anterior teeth. Tooth discoloration and pigmentation can be treated by polishing or bleaching the tooth, or by laminate veneering. Bleaching is widely used, since it allows esthetic restoration without removal of the tooth surface. However, its tooth-bleaching efficacy is often assessed in a subjective manner. This report describes the use of in-office bleaching of tetracycline-induced tooth discoloration and yellowed teeth using Hi-Lite^ and Power Gel^, respectively, and objective assessment of efficacy. In both cases, excellent improvement in tooth color was noted, with a color difference (AE) from baseline of 5.8-6.5. These results support that in-office bleaching using Hi-Lite^ or Power Gel^ is a safe and efficacious method for the treatment of tooth discoloration

Risk factors for cognitive dysfunction after coronary artery bypass graft surgery in patients with type 2 diabetes

ObjectivesThe mechanisms of postoperative cognitive dysfunction in patients with diabetes after coronary artery bypass grafting are not fully understood. We sought to determine which type 2 diabetes–related factors contributed to postoperative cognitive dysfunction at 7 days and 6 months after coronary artery bypass grafting.MethodsOne hundred eighty patients with type 2 diabetes who were scheduled for elective coronary artery bypass grafting were studied. As a control group, 100 patients without diabetes mellitus matched for age, sex, and educational level were examined. Hemodynamic parameters (arterial and jugular venous blood gas values) were measured during cardiopulmonary bypass. All patients underwent a battery of neurologic and neuropsychologic tests the day before surgery, 7 days after surgery, and 6 months after surgery.ResultsAge (odds ratio 1.5, 95% confidence interval 1.3-1.8, P = .03), presence of hypertension (odds ratio 1.8, 95% confidence interval 1.3-2.0, P = .01), jugular venous oxygen saturation less than 50% time (odds ratio 1.5, 95% confidence interval 1.1-2.0, P = .045), presence of ascending aorta atherosclerosis (odds ratio 1.5, 95% confidence interval 1.1-2.6, P = .01), diabetic retinopathy (odds ratio 2.0, 95% confidence interval 1.3-3.0, P = .01), and insulin therapy (odds ratio 2.0, 95% confidence interval 1.3-3.0, P = .05), were associated with cognitive impairment at 7 days. Insulin therapy (odds ratio 2.0, 95% confidence interval 1.3-3.8, P = .01), diabetic retinopathy (odds ratio 1.3, 95% confidence interval 1.2-2.9, P < .01), and hemoglobin A1c (odds ratio 1.9, 95% confidence interval 1.3-3.1, P = .047) were associated with cognitive impairment at 6 postoperative months.ConclusionsInsulin therapy, diabetic retinopathy, and hemoglobin A1c were factors in cognitive impairment at 7 days and 6 months after coronary artery bypass grafting in patients with type 2 diabetes