1,702 research outputs found
Variable O VI and N V emission from the X-ray binary LMC X-3 : heating of the black hole companion
Based on high-resolution ultraviolet spectroscopy obtained with the Far Ultraviolet Spectroscopic Explorer (FUSE) and the Cosmic Origins Spectrograph, we present new detections of Ovi and Nv emission from the black hole X-ray binary (XRB) system LMCX-3. We also update the ephemeris of the XRB using recent radial velocity measurements obtained with the echelle spectrograph on the Magellan-Clay telescope. We observe significant velocity variability of the UV emission, and we find that the Ovi and Nv emission velocities follow the optical velocity curve of the XRB. Moreover, the Ovi and Nv intensities regularly decrease between binary phase=0.5 and 1.0, which suggests that the source of the UV emission is increasingly occulted as the B star in the XRB moves from superior to inferior conjunction. These trends suggest that illumination of the B star atmosphere by the intense X-ray emission from the accreting black hole creates a hot spot on one side of the B star, and this hot spot is the origin of the Ovi and Nv emission. However, the velocity semiamplitude of the ultraviolet emission, K-UV approximate to 180 km s(-1), is lower than the optical semiamplitude; this difference could be due to rotation of the B star. Comparison of the FUSE observations taken in 2001 November and 2004 April shows a significant change in the Ovi emission characteristics: in the 2001 data, the Ovi region shows both broad and narrow emission features, while in 2004 only the narrow Ovi emission is clearly present. Rossi X-ray Timing Explorer data show that the XRB was in a high/soft state in the 2001 November epoch but was in a transitional state in 2004 April, so the shape of the X-ray spectrum might change the properties of the region illuminated on the B star and thus change the broad versus narrow characteristics of the UV emission. If our hypothesis about the origin of the highly ionized emission is correct, then careful analysis of the emission occultation could, in principle, constrain the inclination of the XRB and the mass of the black hole
Clincal Observation of Grouping Responsibility Model of Immersion foot nursing In Maternity Ward
目的:责任制护理是一种以病人为中心,在护理过程中运用医学、护理、心理、生理、社会等学科的知识,观察分析病人的全面健康情况,进行有计划和系统的护理,从而提高护理质量和护理人员的素质。引入浸足1号进行整体护理,观察其临床效果。方法:在产科实施分组责任制护理,可以使护士为病人提供连续、全程、无缝隙的护理服务。引入浸足1号护理分为试验组和对照组,使试验组患者增加了家的感觉,并促进了产妇体质的尽快恢复。结果:在实施过程中,我们改变了原来的排班模式,使病人在住院期间有固定的责任护士,增强了护士的责任心,调动了护士的积极性,加强了护患沟通,减少了护理差错和纠纷,提高了护理质量,同时把护士的被动服务变为了主动服务,大大提高了护理质量,促进了产妇康复进程,试验组与对照组比较,护理质量明显提高,统计学比较有显著差异,P<0.05。结论:引入浸足1号护理提高了病人、医生的满意度,提高了护士的自身价值。Objective: Nursing responsibility system is patient centered system, using medicine, nursing, psychology, social and other disciplines of knowledge in the process of nursing, observing and comprehensively analyzing the health condition of patient, proceeding with a systematic nursing plan, so as to improve the quality of nursing and nursing staff quality. Introduction of immersion foot 1 of holistic nursing care, to observe its clinical effect. Methods:The implementation of the system of grouping responsibility nursing in obstetrics, can enable nurses to provide continuous, full, and non-breaking nursing service for patients . Introduction of immersion foot 1 nurses were divided into experimental group and control group, the experimental group increases the feeling of home, which promote maternal physical recovery. Results:In the process of implementation, we changed the original scheduling model, so as to make the patient had the fixed nurses during hospitalization, to strengthen the responsibility of nurses, to arouse the enthusiasm of nurses, to strengthen communication between nurses and patients, to reduce nursing errors and disputes, to improve the quality of care. Meanwhile the nurses change passive service in order to active service, which greatly improved the quality of nursing and promoted maternal rehabilitation process. Compare the experimental group with control group, and significantly improved the quality of nursing, there was statistical significant difference between the groups P<0.05. Conclusion: Introduction of immersion foot 1 care improves patient, physician satisfaction, and the nurses' value
Further Evidence for Variable Synchrotron Emission in XTE J1118+480 in Outburst
We present simultaneous multicolor infrared and optical photometry of the
black hole X-ray transient XTE J1118+480 during its short 2005 January
outburst, supported by simultaneous X-ray observations. The variability is
dominated by short timescales, ~10s, although a weak superhump also appears to
be present in the optical. The optical rapid variations, at least, are well
correlated with those in X-rays. Infrared JHKs photometry, as in the previous
outburst, exhibits especially large amplitude variability. The spectral energy
distribution (SED) of the variable infrared component can be fitted with a
power-law of slope alpha=-0.78 where Fnu is proportional to nu^alpha. There is
no compelling evidence for evolution in the slope over five nights, during
which time the source brightness decayed along almost the same track as seen in
variations within the nights. We conclude that both short-term variability, and
longer timescale fading, are dominated by a single component of constant
spectral shape. We cannot fit the SED of the IR variability with a credible
thermal component, either optically thick or thin. This IR SED is, however,
approximately consistent with optically thin synchrotron emission from a jet.
These observations therefore provide indirect evidence to support jet-dominated
models for XTE J1118+480 and also provide a direct measurement of the slope of
the optically thin emission which is impossible based on the average spectral
energy distribution alone.Comment: Accepted for publication in the Astrophysical Journa
Vaccines against toxoplasma gondii : challenges and opportunities
Development of vaccines against Toxoplasma gondii infection in humans is of high priority, given the high burden of disease in some areas of the world like South America, and the lack of effective drugs with few adverse effects. Rodent models have been used in research on vaccines against T. gondii over the past decades. However, regardless of the vaccine construct, the vaccines have not been able to induce protective immunity when the organism is challenged with T. gondii, either directly or via a vector. Only a few live, attenuated T. gondii strains used for immunization have been able to confer protective immunity, which is measured by a lack of tissue cysts after challenge. Furthermore, challenge with low virulence strains, especially strains with genotype II, will probably be insufficient to provide protection against the more virulent T. gondii strains, such as those with genotypes I or II, or those genotypes from South America not belonging to genotype I, II or III. Future studies should use animal models besides rodents, and challenges should be performed with at least one genotype II T. gondii and one of the more virulent genotypes. Endpoints like maternal-foetal transmission and prevention of eye disease are important in addition to the traditional endpoint of survival or reduction in numbers of brain cysts after challenge
Spatio-Temporal Characteristics of Global Warming in the Tibetan Plateau during the Last 50 Years Based on a Generalised Temperature Zone - Elevation Model
Temperature is one of the primary factors influencing the climate and ecosystem, and examining its change and fluctuation could elucidate the formation of novel climate patterns and trends. In this study, we constructed a generalised temperature zone elevation model (GTEM) to assess the trends of climate change and temporal-spatial differences in the Tibetan Plateau (TP) using the annual and monthly mean temperatures from 1961-2010 at 144 meteorological stations in and near the TP. The results showed the following: (1) The TP has undergone robust warming over the study period, and the warming rate was 0.318°C/decade. The warming has accelerated during recent decades, especially in the last 20 years, and the warming has been most significant in the winter months, followed by the spring, autumn and summer seasons. (2) Spatially, the zones that became significantly smaller were the temperature zones of -6°C and -4°C, and these have decreased 499.44 and 454.26 thousand sq km from 1961 to 2010 at average rates of 25.1% and 11.7%, respectively, over every 5-year interval. These quickly shrinking zones were located in the northwestern and central TP. (3) The elevation dependency of climate warming existed in the TP during 1961-2010, but this tendency has gradually been weakening due to more rapid warming at lower elevations than in the middle and upper elevations of the TP during 1991-2010. The higher regions and some low altitude valleys of the TP were the most significantly warming regions under the same categorizing criteria. Experimental evidence shows that the GTEM is an effective method to analyse climate changes in high altitude mountainous regions
Synthesis and Characterization of Glomerate GaN Nanowires
Glomerate GaN nanowires were synthesized on Si(111) substrates by annealing sputtered Ga2O3/Co films under flowing ammonia at temperature of 950 °C. X-ray diffraction, scanning electron microscopy, high resolution transmission electron microscopy and Fourier transformed infrared spectra were used to characterize the morphology, crystallinity and microstructure of the as-synthesized samples. Our results show that the samples are of hexagonal wurtzite structure. For the majority of GaN nanowires, the length is up to tens of microns and the diameter is in the range of 50–200 nm. The growth process of the GaN nanowires is dominated by Co–Ga–N alloy mechanism
Long-term monitoring of the TeV emission from Mrk 421 with the ARGO-YBJ experiment
ARGO-YBJ is an air shower detector array with a fully covered layer of
resistive plate chambers. It is operated with a high duty cycle and a large
field of view. It continuously monitors the northern sky at energies above 0.3
TeV. In this paper, we report a long-term monitoring of Mrk 421 over the period
from 2007 November to 2010 February. This source was observed by the
satellite-borne experiments Rossi X-ray Timing Explorer and Swift in the X-ray
band. Mrk 421 was especially active in the first half of 2008. Many flares are
observed in both X-ray and gamma-ray bands simultaneously. The gamma-ray flux
observed by ARGO-YBJ has a clear correlation with the X-ray flux. No lag
between the X-ray and gamma-ray photons longer than 1 day is found. The
evolution of the spectral energy distribution is investigated by measuring
spectral indices at four different flux levels. Hardening of the spectra is
observed in both X-ray and gamma-ray bands. The gamma-ray flux increases
quadratically with the simultaneously measured X-ray flux. All these
observational results strongly favor the synchrotron self-Compton process as
the underlying radiative mechanism.Comment: 30 pages, 8 figure
The ARGO-YBJ Experiment Progresses and Future Extension
Gamma ray source detection above 30TeV is an encouraging approach for finding
galactic cosmic ray origins. All sky survey for gamma ray sources using wide
field of view detector is essential for population accumulation for various
types of sources above 100GeV. To target the goals, the ARGO-YBJ experiment has
been established. Significant progresses have been made in the experiment. A
large air shower detector array in an area of 1km2 is proposed to boost the
sensitivity. Hybrid detection with multi-techniques will allow a good
discrimination between different types of primary particles, including photons
and protons, thus enable an energy spectrum measurement for individual specie.
Fluorescence light detector array will extend the spectrum measurement above
100PeV where the second knee is located. An energy scale determined by balloon
experiments at 10TeV will be propagated to ultra high energy cosmic ray
experiments
Observation of Multi-Tev Diffuse Gamma Rays from the Galactic Plane with the Tibet Air Shower Array
Data from the Tibet-III air shower array (with energies around 3 TeV) and
from the Tibet-II array (with energies around 10 TeV) have been searched for
diffuse gamma rays from the Galactic plane. These arrays have an angular
resolution of about 0.9 degrees. The sky regions searched are the inner Galaxy,
20 degrees <= l <= 55 degrees, and outer Galaxy, 140 degrees <= l <= 225
degrees, and |b| <= 2 degrees or <= 5 degrees. No significant Galactic plane
gamma-ray excess was observed. The 99% confidence level upper limits for
gamma-ray intensity obtained are (for |b| <= 2 degrees) 1.1 times 10^{-15}
cm^{-2}s^{-1}sr^{-1}MeV^{-1} at 3 TeV and 4.1 times 10^{-17}
cm^{-2}s^{-1}sr^{-1}MeV^{-1} at 10 TeV for the inner Galaxy, and 3.6 times
10^{-16} cm^{-2}s^{-1}sr^{-1}MeV^{-1} at 3 TeV and 1.3 times 10^{-17}
cm^{-2}s^{-1}sr^{-1}MeV^{-1} at 10 TeV for the outer Galaxy, assuming a
differential spectral index of 2.4. The upper limits are significant in the
multi-TeV region when compared to those from Cherenkov telescopes in the lower
energy region and other air shower arrays in the higher energy region; however,
the results are not sufficient to rule out the inverse Compton model with a
source electron spectral index of 2.0.Comment: 22 pages, 8 figures, Accepted for publication in Ap
Magnetic Behavior of Surface Nanostructured 50-nm Nickel Thin Films
Thermally evaporated 50-nm nickel thin films coated on borosilicate glass substrates were nanostructured by excimer laser (0.5 J/cm2, single shot), DC electric field (up to 2 kV/cm) and trench-template assisted technique. Nanoparticle arrays (anisotropic growth features) have been observed to form in the direction of electric field for DC electric field treatment case and ruptured thin film (isotropic growth features) growth for excimer laser treatment case. For trench-template assisted technique; nanowires (70–150 nm diameters) have grown along the length of trench template. Coercive field and saturation magnetization are observed to be strongly dependent on nanostructuring techniques
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