We report the detection of a γ-ray bubble spanning at least 100deg2 in ultra-high energy (UHE) up to a few PeV in the direction of the star-forming region Cygnus X, implying the presence super ...PeVatron(s) accelerating protons to at least 10 PeV. A log-parabola form with the photon index Γ(E)=(2.71±0.02)+(0.11±0.02)×log10(E/10TeV) is found fitting the gamma-ray energy spectrum of the bubble well. UHE sources, “hot spots” correlated with very massive molecular clouds, and a quasi-spherical amorphous γ-ray emitter with a sharp central brightening are observed in the bubble. In the core of ∼0.5°, spatially associating with a region containing massive OB association (Cygnus OB2) and a microquasar (Cygnus X-3), as well as previously reported multi-TeV sources, an enhanced concentration of UHE γ-rays is observed with 2 photons at energies above 1 PeV. The general feature of the bubble, the morphology, and the energy spectrum, are reasonably reproduced by the assumption of a particle accelerator in the core, continuously injecting protons into the ambient medium.
Permafrost degradation within a warming climate poses a
significant environmental threat through both the permafrost carbon feedback
and damage to human communities and infrastructure. Understanding ...this
threat relies on better understanding and numerical representation of
thermo-hydrological permafrost processes and the subsequent accurate
prediction of permafrost dynamics. All models include simplified
assumptions, implying a tradeoff between model complexity and prediction
accuracy. The main purpose of this work is to investigate this tradeoff when
applying the following commonly made assumptions: (1) assuming equal density
of ice and liquid water in frozen soil, (2) neglecting the effect of
cryosuction in unsaturated freezing soil, and (3) neglecting advective heat
transport during soil freezing and thaw. This study designed a set of 62
numerical experiments using the Advanced Terrestrial Simulator (ATS v1.2) to
evaluate the effects of these choices on permafrost hydrological outputs,
including both integrated and pointwise quantities. Simulations were
conducted under different climate conditions and soil properties from three
different sites in both column- and hillslope-scale configurations. Results
showed that amongst the three physical assumptions, soil cryosuction is the
most crucial yet commonly ignored process. Neglecting cryosuction, on
average, can cause 10 %–20 % error in predicting
evaporation, 50 %–60 % error in discharge, 10 %–30 % error in thaw depth, and 10 %–30 % error in soil temperature
at 1 m beneath the surface. The prediction
error for subsurface temperature and water saturation is more obvious at
hillslope scales due to the presence of lateral flux. By comparison, using
equal ice–liquid density has a minor impact on most hydrological metrics of
interest but significantly affects soil water saturation with an averaged
5 %–15 % error. Neglecting advective heat transport
presents the least error, 5 % or even much lower, in most metrics of
interest for a large-scale Arctic tundra system without apparent influence
caused by localized groundwater flow, and it can decrease the simulation time
at hillslope scales by 40 %–80 %. By challenging these
commonly made assumptions, this work provides permafrost hydrology
scientists an important context for understanding the underlying physical
processes, including allowing modelers to better choose the appropriate
process representation for a given modeling experiment.
The impacts of different crop rotation systems with their corresponding management practices on grain yield, greenhouse gas emissions, and fertilizer nitrogen (N) and irrigation water use ...efficiencies are not well documented. This holds especially for the North China Plain which provides the staple food for hundreds of millions of people and where groundwater resources are polluted with nitrate and depleted through irrigation. Here, we report on fertilizer N and irrigation water use, grain yields, and nitrous oxide (N2O) and methane (CH4) emissions of conventional and optimized winter wheat–summer maize double-cropping systems, and of three alternative cropping systems, namely a winter wheat–summer maize (or soybean)–spring maize system, with three harvests in two years; and a single spring maize system with one crop per year. The results of this two-year study show that the optimized double-cropping system led to a significant increase in grain yields and a significant decrease in fertilizer N use and net greenhouse gas intensity, but the net greenhouse gas N2O emissions plus CH4 uptake and the use of irrigation water did not decrease relative to the conventional system. Compared to the conventional system the net greenhouse gas emissions, net greenhouse gas intensity and use of fertilizer N and irrigation water decreased in the three alternative cropping systems, but at the cost of grain yields except in the winter wheat–summer maize–spring maize system. Net uptake of CH4 by the soil was little affected by cropping system. Average N2O emission factors were only 0.17% for winter wheat and 0.53% for maize. In conclusion, the winter wheat–summer maize–spring maize system has considerable potential to decrease water and N use and decrease N2O emissions while maintaining high grain yields and sustainable use of groundwater.
•Yields, resource use efficiency and N2O+CH4 emission differ among cropping systems.•An alternative cropping system is recommended for the North China Plain region.•A rotation cycle of it is in sequence winter wheat, summer maize and spring maize.•This alternative is better than an optimized winter wheat–summer maize system.•It is sustainable due to saving water and N, maintaining yields and reducing GHG.
We consider the
n
-dimensional generalized Liénard system
d
d
t
ϕ
p
(
x
(
t
)
−
C
x
(
t
−
τ
)
)
′
+
d
d
t
∇
F
(
x
(
t
−
τ
)
)
+
∇
G
(
x
(
t
−
δ
(
t
)
)
)
=
e
(
t
)
driven by the scalar
p-Laplacian,
...C
is an
n
×
n
symmetric matrix of constants.
Using the degree theory, we establish some criteria to guarantee the existence of periodic solutions for the above system, which generalize and improve on the corresponding results in the related literature.
Commercially available passivation methods for white-rust protection of Hot-Dip Galvanized steel have been applied for chromate passivation. However, hexavalent chromium (Cr-VI) is highly toxic and ...carcinogenic. Therefore, in this paper, we put forth a new means for white-rust protection of Hot-Dip Galvanized steel based on the effects of corrosion inhibitors. In this study, the passivation solution combines the advantages of inorganic salt passivation, silane passivation and resin passivation. The corrosion resistance of the inorganic and organic composite passivation films with corrosion inhibitors was determined by a neutral salt spray test and electrochemical Tafel polarization curves. The surface chemistry of the coatings was monitored by scanning electron microscopy (SEM), X-ray Photoelectron spectroscopy (XPS) and Fourier transform infrared reflection absorption spectroscopy (FTIR). And further studying on the formation mechanism of the passivation film was carried out. The SEM indicated that the top surface of the passivation film was transparent, smooth, uniform and compact. The XPS and FTIR results showed that the passivation film consisted mainly of organic functional groups including-(CH2)n-, -OH, N-H, C=O, C-Si, C-O-C, C-N, Si-O-Si, Si-O-C and so on. The corrosion resistance of passivation film with corrosion inhibitors was significantly improved than that of the passivation film without corrosion inhibitor. After 96h of the corrosion test, the corrosion area was found to be less than 5 %, which indicated that the passivation film greatly improved the corrosion resistance of the hot-dip galvanized sheet, and exhibited a very good protective effect so that can met some industrial applications.DOI: http://dx.doi.org/10.5755/j01.ms.24.3.16330
High density oligonucleotide microarrays (OMAs) have been used recently to profile gene expression in lung carcinoma tissue homogenates. The length of the lists of potentially interesting genes ...generated by these studies is daunting, and biological and clinical relevance of these lists remains to be validated. Moreover, specific identification of individual biomarkers that might be used for early detection and surveillance has not been the objective of these early studies. We have developed a schema for combining the data derived from the OMA analysis of a few lung cancer cell lines with immunohistochemical testing of tissue microarrays to rapidly identify biomarkers of potential clinical relevance. Initially, we profiled gene expression in lung tumor cell lines using the Affymetrix HG-U95Av2 OMA. RNA from 2 non-small cell lung cancer (NSCLC) cell lines (A549 and H647) and 2 small cell lung cancer (SCLC) cell lines (SHP-77 and UMC-19) were tested. Cells from 1 histologically and cytogenetically normal bronchial epithelial primary culture from a volunteer who had never smoked and 10 samples of histologically unremarkable lung tissue from resection specimens served as normalization controls. Array results were analyzed with Gene Spring software. Results were confirmed by reverse transcription-PCR in an expanded number of cell lines. We then validated the cell line data by immunohistochemical testing for protein using a tissue microarray containing 187 NSCLC clinical samples. Of the 20 most highly expressed genes in the tumor lines, 6 were members of the cancer/testis antigen (CTAG) gene group including 5 MAGE-A subfamily members and NY-ESO-1. SCLC lines strongly expressed all of the MAGE-A genes as well as NY-ESO-1, whereas NSCLC lines expressed a subset of MAGE-A genes at a lower level of intensity and failed to express NY-ESO-1. Reverse transcription-PCR of an extended series of 25 lung cancer cell lines including 13 SCLC, 9 NSCLC, and 3 mesothelioma lines indicated that MAGE-A10 and NY-ESO-1 were expressed only by SCLC, and that MAGE-A1, 3, 6, 12, and 4b were expressed by both SCLC and NSCLC. By immunohistochemistry using the monoclonal antibody 6C1 that recognizes several MAGE-A gene subfamily members, 44% of NSCLC clearly expressed MAGE-A proteins in cytoplasm and/or nucleus. Expression of MAGE-A genes did not correlate with survival but did correlate with histological classification with squamous carcinomas more frequently MAGE-A positive than other NSCLC types (P < 0.00002). We conclude that expression of CTAG gene products, whereas apparently not of prognostic importance, may be useful for early detection and surveillance because of a high level of specificity for central airway squamous and small cell carcinomas.
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