Chemical characteristics of air from different source regions during the second Pacific Exploratory Mission in the Tropics (PEM-Tropics B)

Ten-day backward trajectories are used to determine the origins of air parcels arriving at locations of airborne DC-8 chemical measurements during NASA's second Pacific Exploratory Mission in the Tropics B that was conducted during February-April 1999. Chemical data at sites where the trajectories had a common geographical origin and transport history are grouped together, and statistical measures of chemical characteristics are computed. Temporal changes in potential temperature are used to determine whether trajectories experienced a significant convective influence during the 10-day period. Trajectories describing the aged marine Southern Hemispheric category remain over the South Pacific Ocean during the 10-day period, and their corresponding chemical signature indicates very clean air. The category aged marine air in the Northern Hemisphere is found to be somewhat dirtier. Subdividing its trajectories based on the direction from which the air had traveled is found to be important in explaining the various chemical signatures. Similarly, long-range northern hemispheric trajectories passing over Asia are subdivided depending on whether they had followed a mostly zonal path, had originated near the Indian Ocean, or had originated near Central or South America and subsequently experienced a stratospheric influence. Results show that the chemical signatures of these subcategories are different from each other. The chemical signature of the southern hemispheric long-range transport category apparently exhibits the effects of pollution from Australia, southern Africa, and South America. Parcels originating over Central and northern South America are found to contain the strongest pollution signature of all categories, due to biomass burning and other sources. The convective category exhibits enhanced values of nitrogen species, probably due to emissions from lightning associated with the convection. Values of various species, including peroxides and acids, confirm that parcels were influenced by the removal of soluble gas and particle species due to precipitation. Finally, current results are compared with those from the first PEM-Tropics mission that was conducted in the same region during the southern hemispheric dry season (August-October 1996) when extensive biomass burning occurred. Results show that air samples during PEM-Tropics B are considerably cleaner than those of its dry season counterpart. Copyright 2001 by the American Geophysical Union

Photochemical production and evolution of selected C2-C5 alkyl nitrates in tropospheric air influenced by Asian outflow

The photochemical production and evolution of six C2-C5 alkyl nitrates (ethyl-, 1-propyl-, 2-propyl-, 2-butyl-, 2-pentyl-, and 3-pentyl nitrate) was investigated using selected data from 5500 whole air samples collected downwind of Asia during the airborne Transport and Chemical Evolution over the Pacific (TRACE-P) field campaign (February-April 2001). Air mass age was important for selecting appropriate field data to compare with laboratory predictions of C5 alkyl nitrate production rates. In young, highly polluted air masses, the ratio between the production rates of 3-pentyl nitrate and 2-pentyl nitrate from n-pentane was 0.60-0.65. These measured ratios show excellent agreement with results from a field study in Germany (0.63 ± 0.06), and they agree better with predicted ratios from older laboratory kinetic studies (0.63-0.66) than with newer laboratory results (0.73 ± 0.08). TRACE-P samples that did not show influence from marine alkyl nitrate sources were used to investigate photochemical alkyl nitrate evolution. Relative to 2-butyl nitrate/n-butane, the measured ratios of ethyl nitrate/ethane and 2-propyl nitrate/propane showed notable deviations from modeled values based on laboratory kinetic data, suggesting additional Asian sources of their alkyl peroxy radical precursors. By contrast, the measured ratios of 1-propyl-, 2-pentyl-, and 3-pentyl nitrate to their respective parent hydrocarbons were fairly close to modeled values. The 1-propyl nitrate findings contrast with field studies in North America, and suggest that air downwind of Asia was not significantly impacted by additional 1-propyl nitrate precursors. The sensitivity of modeled photochemical processing times to hydroxyl radical concentration, altitude, city ventilation times, and dilution is discussed

Two binary stars gravitational waves - homotopy perturbation method

Homotopy perturbation is one of the newest methods for numerical analysis of deferential equations. We have used for solving wave equation around a black hole. Our conclusions have this method far reaching consequences for comparison of theoritical physics and experimental physics.Comment: The manuscript considers the important problem of solve equation wave around a black hole. We have solved that by using Homotopy perturbation methods. Homotopy perturbation is one of the newest methods for numerical analysis of deferential equations. Our conclusions have far reaching consequences for comparison of theoritical physics and experimental physic

Ethanol extract of Hedyotis diffusa willd. induction of apoptosis via PI3K/Akt and XIAP pathways in human leukemic THP-1 cells

Hedyotis diffusa (H. diffusa) Willd. is known to induce apoptosis in cancer cells. However, the molecular mechanism of its anti-cancer activity has not been fully elucidated. In this study, we found that the ethanol extract of H. diffusa Willd. (EEHDW) reduced cell viability and induced apoptosis in a dose- and time-dependent manner in human leukemic THP-1 cells. The induction of apoptosis was also accompanied by the down regulation of PI3K/Akt and the inhibitor of apoptosis protein (IAP) family proteins. Moreover, we observed that EEHDW treatment resulted in activation of caspase-3, which may partly explain the anti-cancer activity of EEHDW.Key words: Hedyotis diffusa Willd., THP-1, apoptosis, caspase

Wavelength-multiplexed duplex transceiver based on III-V/Si hybrid integration for off-chip and on-chip optical interconnects

A six-channel wavelength-division-multiplexed optical transceiver with a compact footprint of 1.5 x 0.65 mm(2) for off-chip and on-chip interconnects is demonstrated on a single silicon-on-insulator chip. An arrayed waveguide grating is used as the (de)multiplexer, and III-V electroabsorption sections fabricated by hybrid integration technology are used as both modulators and detectors, which also enable duplex links. The 30-Gb/s capacity for each of the six wavelength channels for the off-chip transceiver is demonstrated. For the on-chip interconnect, an electrical-to-electrical 3-dB bandwidth of 13 GHz and a data rate of 30 Gb/s per wavelength are achieved

First-principles calculations and experimental studies of: XYZ 2 thermoelectric compounds: Detailed analysis of van der Waals interactions

First-principles calculations can accelerate the search for novel high-performance thermoelectric materials. However, the prediction of the thermoelectric properties is strongly dependent on the approximations used for the calculations. Here, thermoelectric properties were calculated with different computational approximations (i.e., PBE-GGA, HSE06, spin-orbit coupling and DFT-D3) for three layered XYZ2 compounds (TmAgTe2, YAgTe2, and YCuTe2). In addition to the computations, the structural, electrical and thermal properties of these compounds were measured experimentally and compared to the computations. An enhanced prediction of the crystal structure and heat capacity was achieved with the inclusion of van der Waals interactions due to more accurate modeling of the interatomic forces. In particular, a large shift of the acoustic phonons and low-frequency optical phonons to lower frequencies was observed from the dispersion-optimized structure. From the phonon dispersion curves of these compounds, the ultralow thermal conductivity in the investigated XYZ2 compounds could be described by a recent developed minimum thermal conductivity model. For the prediction of the electrical conductivity, a temperature-dependent relaxation time was used, and it was limited by acoustic phonons. While HSE06 has only a small influence on the electrical properties due to a computed band gap energy of >0.25 eV, the inclusion of both van der Waals interactions and spin-orbit coupling leads to a more accurate band structure, resulting in better prediction of electrical properties. Furthermore, the experimental thermoelectric properties of YAgTe2, TmAg0.95Zn0.05Te2 and TmAg0.95Mg0.05Te2 were measured, showing an increase in zT of TmAg0.95Zn0.05Te2 by more than 35% (zT = 0.47 ± 0.12) compared to TmAgTe2

Image Co-localization by Mimicking a Good Detector's Confidence Score Distribution

Given a set of images containing objects from the same category, the task of image co-localization is to identify and localize each instance. This paper shows that this problem can be solved by a simple but intriguing idea, that is, a common object detector can be learnt by making its detection confidence scores distributed like those of a strongly supervised detector. More specifically, we observe that given a set of object proposals extracted from an image that contains the object of interest, an accurate strongly supervised object detector should give high scores to only a small minority of proposals, and low scores to most of them. Thus, we devise an entropy-based objective function to enforce the above property when learning the common object detector. Once the detector is learnt, we resort to a segmentation approach to refine the localization. We show that despite its simplicity, our approach outperforms state-of-the-art methods.Comment: Accepted to Proc. European Conf. Computer Vision 201

Apoptosis induced by Staphylococcus aureus in human monocytic U937 cells involves Akt and mitogen-activated protein (MAPK) phosphorylation

Staphylococcus aureus (S. aureus) is a leading etiologic agent of nosocomial and community-acquired infectious diseases. Numerous studies have shown that, S. aureus could promote apoptosis in host cells. Unfortunately, the cellular and molecular mechanisms responsible for this phenomenon are still poorly understood. The present study aims to elucidate the signaling mechanisms involved in S. aureus-induced U937 cells apoptosis by investigating the role of phosphatidylinositol 3-kinase/Akt (PI3K/Akt), mitogen-activated protein (MAPK) and caspases. Our results showed that, i decreased the expression of phosphorylation-Akt. In contrast, S. aureus increased phosphorylation-JNK1/2, phosphorylation-ERK1/2 and phosphorylation-p38 MAPK. Treatment of U937 cells with S. aureus resulted in the activation of caspase-3 and -9. Furthermore, caspases inhibitors, SP600125 (JNK inhibitor), SB203580 (p38MAPK inhibitor) and PD98059 (ERK inhibitor) decreased apoptosis in U937 cells. However, LY294002 (Akt inhibitor) increased U937 cells apoptosis. Taken together, our study for the first time suggest that S. aureus is able to enhance apoptosis of U937 cells through inhibition of PI3K/Akt and activation of MAPK signaling pathways.Key words: Staphylococcus aureus, mitogen-activated protein (MAPK), apoptosis, U937