12,407 research outputs found
Completing incomplete cohort fertility schedules
This paper develops a simple age-period-cohort framework in completing incomplete cohort fertility schedules, and makes full use of 1917--2005 U.S. data to obtain robust outcomes. Empirically, we indicate that the period effect is the key to transforming a fertility level into a fertility schedule. Accompanied by the smoothed version of tempo-variance-adjusted total fertility rates proposed in Kohler and Philipov (2001), we approximate the cohort fertility schedules fairly well and the estimates of all distributional parameters can be thereby obtained. Our approach is easy to implement and the data requirement is relatively light, indicating that the proposed method is readily applicable to countries whose data lengths are insufficiently long, and would be helpful for further empirical investigation of the relationship between cohort fertility behavior and other cohort-specific socioeconomic factors.APC model, cohort fertility schedule, fertility forecast
Dependence of Nanocrystal Dimensionality on the Polymer Nanomorphology, Anisotropic Optical Absorption, and Carrier Transport in P3HT:TiO2 Bulk Heterojunctions
[[abstract]]It is known that the nanoscale morphological organization of donors or acceptors in bulk heterojunction (BHJ) solar cells is critical to device performance and strongly affects carrier generation, transporting, and collection. This work demonstrates the dependence of nanocrystal dimensionality and organization on the polymer nanomorphology in P3HT:TiO2 hybrid bulk heterojunctions, which were revealed using grazing-incidence X-ray diffraction (GIXRD) using a synchrotron X-ray beam and electron tomography. We further performed a multiscale molecular dynamic simulation to understand the morphological orientation of a polymer blended with TiO2 nanoparticles (NPs) or nanorods (NRs). The correlation between polymer nanoscale morphology and the dimensionality and anisotropy of nanocrystals in P3HT:TiO2 hybrids clearly explains the observation of different optical absorption and carrier transport behaviors in directions perpendicular or parallel to the film substrate. Our results provide crucial information toward understanding the interplay between nanocrystal dimensionality and polymer morphology in developing organic/inorganic hybrid electronic devices such as thin film transistors (TFTs) or photovoltaics (PVs).[[notice]]補正完畢[[incitationindex]]SCI[[booktype]]電子版[[iscallforpapers]]
Temperature-dependent permittivity of annealed and unannealed gold films
Due to local field enhancement and subwavelength confinements,
nano-plasmonics provide numerous novel applications. Simultaneously, as an
efficient nanoscale heat generator from inherent absorption, thermo-plasmonics
is emerging as an important branch. However, although significant temperature
increase is involved in applications, detailed characterization of metal
permittivity at different temperatures and corresponding thermo-derivative are
lacking. In this work, we extract the permittivity of gold from 300K to the
annealing temperature of 570K. By comparing annealed and unannealed films, more
than one-order difference in thermo-derivative of permittivity is revealed,
resulting in unexpectedly large variation of plasmonic properties. Our result
is valuable not only for characterizing extensively used unannealed
nanoparticles, but also for designing future thermo-nano-plasmonic systems.Comment: 6 pages, 4 figures, revised and published on Optics Expres
Highly efficient coherent optical memory based on electromagnetically induced transparency
Quantum memory is an important component in the long-distance quantum
communication system based on the quantum repeater protocol. To outperform the
direct transmission of photons with quantum repeaters, it is crucial to develop
quantum memories with high fidelity, high efficiency and a long storage time.
Here, we achieve a storage efficiency of 92.0(1.5)\% for a coherent optical
memory based on the electromagnetically induced transparency (EIT) scheme in
optically dense cold atomic media. We also obtain a useful time-bandwidth
product of 1200, considering only storage where the retrieval efficiency
remains above 50\%. Both are the best record to date in all kinds of the
schemes for the realization of optical memory. Our work significantly advances
the pursuit of a high-performance optical memory and should have important
applications in quantum information science.Comment: 5 pages, 5 figures, supplementary materials: 12 pages, 4 figure
Effectiveness of influenza vaccination in patients with end-stage renal disease receiving hemodialysis: a population-based study.
BackgroundLittle is known on the effectiveness of influenza vaccine in ESRD patients. This study compared the incidence of hospitalization, morbidity, and mortality in end-stage renal disease (ESRD) patients undergoing hemodialysis (HD) between cohorts with and without influenza vaccination.MethodsWe used the insurance claims data from 1998 to 2009 in Taiwan to determine the incidence of these events within one year after influenza vaccination in the vaccine (N = 831) and the non-vaccine (N = 3187) cohorts. The vaccine cohort to the non-vaccine cohort incidence rate ratio and hazard ratio (HR) of morbidities and mortality were measured.ResultsThe age-specific analysis showed that the elderly in the vaccine cohort had lower hospitalization rate (100.8 vs. 133.9 per 100 person-years), contributing to an overall HR of 0.81 (95% confidence interval (CI) 0.72-0.90). The vaccine cohort also had an adjusted HR of 0.85 [95% CI 0.75-0.96] for heart disease. The corresponding incidence of pneumonia and influenza was 22.4 versus 17.2 per 100 person-years, but with an adjusted HR of 0.80 (95% CI 0.64-1.02). The vaccine cohort had lowered risks than the non-vaccine cohort for intensive care unit (ICU) admission (adjusted HR 0.20, 95% CI 0.12-0.33) and mortality (adjusted HR 0.50, 95% CI 0.41-0.60). The time-dependent Cox model revealed an overall adjusted HR for mortality of 0.30 (95% CI 0.26-0.35) after counting vaccination for multi-years.ConclusionsESRD patients with HD receiving the influenza vaccination could have reduced risks of pneumonia/influenza and other morbidities, ICU stay, hospitalization and death, particularly for the elderly
A New Combined Boost Converter with Improved Voltage Gain as a Battery-Powered Front-End Interface for Automotive Audio Amplifiers
High boost DC/DC voltage conversion is always indispensable in a power electronic interface of certain battery-powered electrical equipment. However, a conventional boost converter works for a wide duty cycle for such high voltage gain, which increases power consumption and has low reliability problems. In order to solve this issue, a new battery-powered combined boost converter with an interleaved structure consisting of two phases used in automotive audio amplifier is presented. The first phase uses a conventional boost converter; the second phase employs the inverted type. With this architecture, a higher boost voltage gain is able to be achieved. A derivation
of the operating principles of the converter, analyses of its topology, as well as a closed-loop control designs are performed in this study. Furthermore, simulations and experiments are also performed using input voltage of 12 V for a 120Wcircuit. A reasonable duty cycle is selected to reach output voltage of 60 V, which corresponds to static voltage gain of five. The converter achieves a maximum measured conversion efficiency of 98.7% and the full load efficiency of 89.1%
Electroluminescence from Strained Ge membranes and Implications for an Efficient Si-Compatible Laser
We demonstrate room-temperature electroluminescence (EL) from light-emitting
diodes (LED) on highly strained germanium (Ge) membranes. An external stressor
technique was employed to introduce a 0.76% bi-axial tensile strain in the
active region of a vertical PN junction. Electrical measurements show an on-off
ratio increase of one order of magnitude in membrane LEDs compared to bulk. The
EL spectrum from the 0.76% strained Ge LED shows a 100nm redshift of the center
wavelength because of the strain-induced direct band gap reduction. Finally,
using tight-binding and FDTD simulations, we discuss the implications for
highly efficient Ge lasers.Comment: 4 Pages, 5 figure
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Cucurbitacin E inhibits the Yes‑associated protein signaling pathway and suppresses brain metastasis of human non‑small cell lung cancer in a murine model.
Human non‑small cell lung cancer (NSCLC) is associated with an extremely poor prognosis especially for the 40% of patients who develop brain metastasis, and few treatment strategies exist. Cucurbitacin E (CuE), an oxygenated tetracyclic triterpenoid isolated from plants particularly of the family Cucurbitaceae, has shown anti‑tumorigenic properties in several types of cancer, yet the mechanism remains unclear. Yes‑associated protein (YAP), a main mediator of the Hippo signaling pathway, promotes tumorigenesis, drug resistance and metastasis in human NSCLC. The present study was designed to ascertain whether CuE inhibits YAP and its downstream gene expression in the human NSCLC cell lines H2030‑BrM3 (K‑rasG12C mutation) and PC9‑BrM3 (EGFRΔexon19 mutation), which have high potential for brain metastasis. The efficacy of CuE in suppressing brain metastasis of H2030‑BrM3 cells in a murine model was also investigated. It was found that after CuE treatment in H2030‑BrM3 and PC9‑BrM3 cells, YAP protein expression was decreased, and YAP signaling GTIIC reporter activity and expression of the downstream genes CTGF and CYR61 were significantly (P<0.01) decreased. CuE treatment also reduced the migration and invasion abilities of the H2030‑BrM3 and PC9‑BrM3 cells. Finally, our in vivo study showed that CuE treatment (0.2 mg/kg) suppressed H2030‑BrM3 cell brain metastasis and that mice treated with CuE survived longer than the control mice treated with 10% DMSO (P=0.02). The present study is the first to demonstrate that CuE treatment inhibits YAP and the signaling downstream gene expression in human NSCLC in vitro, and suppresses brain metastasis of NSCLC in a murine model. More studies to verify the promising efficacy of CuE in inhibiting brain metastasis of NSCLC and various other cancers may be warranted
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