3,511 research outputs found
Salinity effect and seed priming treatments on the germination of Suaeda salsa in the tidal marsh of the Yellow River estuary
The effects of salinity and seed priming treatments (hydropriming, water, KNO3 and KH2PO3) on the germination of the euhalophyte Suaeda salsa in intertidal zone of the Yellow River estuary were investigated. Results show that the seed germination percentage decreased with increasing NaCl concentration, and at the high NaCl level (800 mM), the lowest germination percentage was recorded. At the low NaCl levels, the highest germination rate was observed on day two and the seedling length was promoted slightly. In contrast, the germination delayed and the seedling length decreased at the high salinity. According to the survival functions, we also found that, at the low salinity, the seeds germinated quickly at the initial days and then the germination rate decreased, while few seeds germinated at the initial days at the high salinity. From the results of germination percentage and seedling length, we found that the effect of Yellow river water on germination was similar to the 400 mM NaCl. For priming treatments, the hydropriming has no promotion to the seeds germination, but it promoted the seedling growth at the river water and 400 mM NaCl. Seeds primed with KNO3 could improve the germination at the low salinity, while priming with KH2PO4 could improve the seedling growth at the high salinity, indicating that seed priming with proper nutrient (N, P) solutions could improve the germination or seedling growth as the nutrient (N, P) availability in the soil of S. salsa marsh was very limited.Keywords: Suaeda salsa, germination, salinity, priming, Yellow River estuar
Theatrical performance in the tourism industry: An Importance-Satisfaction Analysis
Theatrical performances have been developed quickly in many tourism destinations in China; however, little research has been focused on this important area. This study examined tourists’ perceptions towards The Romance of the Song Dynasty, one of the most successful performances targeted at tourists in China. Using Importance-Satisfaction Analysis (ISA), this study revealed that the most important and satisfied attributes by tourists were primarily associated with the core service attributes (i.e., performing art), whereas the most unimportant and dissatisfied attributes by tourists were mainly associated with the peripheral service attributes (i.e., venue environment, service, and tourist management). Both theoretical and practical contributions were provided in this study
Digit-only sauropod pes trackways from China - evidence of swimming or a preservational phenomenon?
For more than 70 years unusual sauropod trackways have played a pivotal role in debates about the swimming ability of sauropods. Most claims that sauropods could swim have been based on manus-only or manus-dominated trackways. However none of these incomplete trackways has been entirely convincing, and most have proved to be taphonomic artifacts, either undertracks or the result of differential depth of penetration of manus and pes tracks, but otherwise showed the typical pattern of normal walking trackways. Here we report an assemblage of unusual sauropod tracks from the Lower Cretaceous Hekou Group of Gansu Province, northern China, characterized by the preservation of only the pes claw traces, that we interpret as having been left by walking, not buoyant or swimming, individuals. They are interpreted as the result of animals moving on a soft mud-silt substrate, projecting their claws deeply to register their traces on an underlying sand layer where they gained more grip during progression. Other sauropod walking trackways on the same surface with both pes and manus traces preserved, were probably left earlier on relatively firm substrates that predated the deposition of soft mud and silt . Presently, there is no convincing evidence of swimming sauropods from their trackways, which is not to say that sauropods did not swim at all
Robust radiative cooling via surface phonon coupling-enhanced emissivity from SiO2 micropillar arrays
Silicon dioxide (SiO2) is a prominent candidate for radiative cooling applications due to its low absorption in solar wavelengths (0.25-2.5 µm) and exceptional stability. However, its bulk phonon-polariton band results in a strong reflection peak in the atmospheric transparency window (8-13 µm), making it difficult to meet the requirements for sub-ambient passive radiative cooling. Herein, we demonstrate that SiO2 micropillar arrays can effectively suppress infrared reflection at 8-13 µm and enhance the infrared emissivity by optimizing the micropillar array structure. We created a pattern with a height, spacing, and diameter of approximately 1.45 µm, 0.15 µm, and 0.35 µm, respectively, on top of a bulk SiO2 substrate using reactive ion etching. The resulting surface phonon coupling of the micropillar array led to an increase in the thermal emissivity from 0.79 to 0.94. Outdoor tests show that the SiO2 cooler with an optimized micropillar array can generate an average temperature drop of 5.5 °C throughout the daytime underneath an irradiance of 843.1 W/m^2 at noon. Furthermore, the micropillar arrays endow the SiO2 cooler with remarkable hydrophobic properties, attributed to the formation of F/C compounds introduced during the etching process. Finally, we also replicated the micropillar pattern onto the surface of industrial optical solar reflectors (OSRs), demonstrating similar emissivity and hydrophobicity enhancements. Our findings revealed an effective strategy for modifying the thermal management features of durable SiO2 layers, which can be harnessed to cool OSRs and other similar sky-facing devices
A Note on Encodings of Phylogenetic Networks of Bounded Level
Driven by the need for better models that allow one to shed light into the
question how life's diversity has evolved, phylogenetic networks have now
joined phylogenetic trees in the center of phylogenetics research. Like
phylogenetic trees, such networks canonically induce collections of
phylogenetic trees, clusters, and triplets, respectively. Thus it is not
surprising that many network approaches aim to reconstruct a phylogenetic
network from such collections. Related to the well-studied perfect phylogeny
problem, the following question is of fundamental importance in this context:
When does one of the above collections encode (i.e. uniquely describe) the
network that induces it? In this note, we present a complete answer to this
question for the special case of a level-1 (phylogenetic) network by
characterizing those level-1 networks for which an encoding in terms of one (or
equivalently all) of the above collections exists. Given that this type of
network forms the first layer of the rich hierarchy of level-k networks, k a
non-negative integer, it is natural to wonder whether our arguments could be
extended to members of that hierarchy for higher values for k. By giving
examples, we show that this is not the case
Estradiol and testosterone levels in patients undergoing partial hepatectomy - A possible signal for hepatic regeneration?
In five adult male patients undergoing a 40-60% partial hepatectomy, serum sex hormone levels before and after hepatic resection were determined. Blood was drawn immediately prior to each surgical procedure and at specified time points postoperatively. Compared to hormone levels found prior to surgery, following major hepatic resection, estradiol levels increase at 24 and 48 hr, while testosterone levels decline, being significantly reduced at 96 and 144 hr. These data demonstrate that adult males who undergo a 40-60% partial hepatectomy experience alterations in their sex hormone levels similar to those observed in male rats following a 70% hepatectomy. These changes in sex hormone levels have been associated in animals with an alteration of the sex hormone receptor status of the liver that is thought to participate in the initiation of the regenerative response. These studies suggest, but do not prove, that in man, as in the case of the rat, sex hormones may participate in the initiation of or at least modulate in part the regenerative response that occurs following a major hepatic resection. © 1989 Plenum Publishing Corporation
Bridging Time Scales in Cellular Decision Making with a Stochastic Bistable Switch
Cellular transformations which involve a significant phenotypical change of
the cell's state use bistable biochemical switches as underlying decision
systems. In this work, we aim at linking cellular decisions taking place on a
time scale of years to decades with the biochemical dynamics in signal
transduction and gene regulation, occuring on a time scale of minutes to hours.
We show that a stochastic bistable switch forms a viable biochemical mechanism
to implement decision processes on long time scales. As a case study, the
mechanism is applied to model the initiation of follicle growth in mammalian
ovaries, where the physiological time scale of follicle pool depletion is on
the order of the organism's lifespan. We construct a simple mathematical model
for this process based on experimental evidence for the involved genetic
mechanisms. Despite the underlying stochasticity, the proposed mechanism turns
out to yield reliable behavior in large populations of cells subject to the
considered decision process. Our model explains how the physiological time
constant may emerge from the intrinsic stochasticity of the underlying gene
regulatory network. Apart from ovarian follicles, the proposed mechanism may
also be of relevance for other physiological systems where cells take binary
decisions over a long time scale.Comment: 14 pages, 4 figure
30 inch Roll-Based Production of High-Quality Graphene Films for Flexible Transparent Electrodes
We report that 30-inch scale multiple roll-to-roll transfer and wet chemical
doping considerably enhance the electrical properties of the graphene films
grown on roll-type Cu substrates by chemical vapor deposition. The resulting
graphene films shows a sheet resistance as low as ~30 Ohm/sq at ~90 %
transparency which is superior to commercial transparent electrodes such as
indium tin oxides (ITO). The monolayer of graphene shows sheet resistances as
low as ~125 Ohm/sq with 97.4% optical transmittance and half-integer quantum
Hall effect, indicating the high-quality of these graphene films. As a
practical application, we also fabricated a touch screen panel device based on
the graphene transparent electrodes, showing extraordinary mechanical and
electrical performances
Designing programs for eliminating canine rabies from islands: Bali, Indonesia as a case study
<p>Background:
Canine rabies is one of the most important and feared zoonotic diseases in the world. In some regions rabies elimination is being successfully coordinated, whereas in others rabies is endemic and continues to spread to uninfected areas. As epidemics emerge, both accepted and contentious control methods are used, as questions remain over the most effective strategy to eliminate rabies. The Indonesian island of Bali was rabies-free until 2008 when an epidemic in domestic dogs began, resulting in the deaths of over 100 people. Here we analyze data from the epidemic and compare the effectiveness of control methods at eliminating rabies.</p>
<p>Methodology/Principal Findings:
Using data from Bali, we estimated the basic reproductive number, R0, of rabies in dogs, to be ~1·2, almost identical to that obtained in ten–fold less dense dog populations and suggesting rabies will not be effectively controlled by reducing dog density. We then developed a model to compare options for mass dog vaccination. Comprehensive high coverage was the single most important factor for achieving elimination, with omission of even small areas (<0.5% of the dog population) jeopardizing success. Parameterizing the model with data from the 2010 and 2011 vaccination campaigns, we show that a comprehensive high coverage campaign in 2012 would likely result in elimination, saving ~550 human lives and ~$15 million in prophylaxis costs over the next ten years.</p>
<p>Conclusions/Significance:
The elimination of rabies from Bali will not be achieved through achievable reductions in dog density. To ensure elimination, concerted high coverage, repeated, mass dog vaccination campaigns are necessary and the cooperation of all regions of the island is critical. Momentum is building towards development of a strategy for the global elimination of canine rabies, and this study offers valuable new insights about the dynamics and control of this disease, with immediate practical relevance.</p>
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