2494 research outputs found
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Characterization and robust nature of newly isolated oleaginous marine yeast Rhodosporidium spp. from coastal water of Northern China
No full textAbstract
A total of ten marine yeast strains isolated from Bohai Sea, Northern China were identified to be members of three genera Rhodosporidium , Rhodotorula , and Cryptococcus . Two representative strains Rhodosporidium TJUWZ4 and Cryptococcus TJUWZA11 with high lipid content based on Nile red staining method were further characterized. A wide range of culture conditions (C and N sources, pH, temperature, salinity and C/N ratio) were tested to characterize the biomass and lipid production (yield and productivity) of these strains. Results indicated that Rhodosporidium TJUWZ4 was capable of achieving lipid yield up to 44% and 0.09\ua0g/l\u2013h productivity on glucose and peptone medium at pH 4, 20\ua0\ub0C, 30% salinity, and C/N 80. Three fatty acids, namely oleic acid (18:1), palmitic acid (C16:0) and linoleic acid (18:2) were the major intracellular fatty acids, which accounted for 90% of total lipids. With promising features for intracellular lipid accumulation, Rhodosporidium TJUWZ4 is a robust strain with great potentials for application in biodiesel production from renewable feedstocks
Hopf bifurcations in an extended Lorenz system
No full textAbstract
In this work, we study Hopf bifurcations in the extended Lorenz system,
x
\u2d9
=
y
,
y
\u2d9
=
m
x
\u2212
n
y
\u2212
m
x
z
\u2212
p
x
3
,
z
\u2d9
=
\u2212
a
z
+
b
x
2
, with five parameters
m
,
n
,
p
,
a
,
b
\u2208
R
. For some values of the parameters, this system can be transformed to the classical Lorenz system. In this paper, we give conditions for occurrence of Hopf bifurcation at the equilibrium points. We find totally three limit cycles, each of them located around one of the three equilibria of the system. Numerical simulations illustrate the validity of these conditions and the existence of limit cycles.
MSC: 37G15, 70K50
The modified degenerate q-Bernoulli polynomials arising from p-adic invariant integral on Z p
No full textAbstract
Dolgy et al. introduced the modified degenerate Bernoulli polynomials, which are different from Carlitz\u2019s degenerate Bernoulli polynomials (see Dolgy et al. in Adv. Stud. Contemp. Math. (Kyungshang) 26(1):1-9,
2016
). In this paper, we study some explicit identities and properties for the modified degenerate q -Bernoulli polynomials arising from the p -adic invariant integral on
Z
p
.
MSC: 11B68, 11S40, 11S80
On solutions of fractional Riccati differential equations
No full textAbstract
We apply an iterative reproducing kernel Hilbert space method to get the solutions of fractional Riccati differential equations. The analysis implemented in this work forms a crucial step in the process of development of fractional calculus. The fractional derivative is described in the Caputo sense. Outcomes are demonstrated graphically and in tabulated forms to see the power of the method. Numerical experiments are illustrated to prove the ability of the method. Numerical results are compared with some existing methods
Activity-based Twitter sampling for content-based and user-centric prediction models
No full textAbstract
Increasingly more applications rely on crowd-sourced data from social media. Some of these applications are concerned with real-time data streams, while others are more focused on acquiring temporal footprints from historical data. Nevertheless, determining the subset of \u201ccredible\u201d users is crucial. While the majority of sampling approaches focus on individual static networks, dynamic user activity over time is usually not considered, which may result in activity gaps in the collected data. Models based on noisy and missing data can significantly degrade in performance. In this study, we demonstrate how to sample Twitter users in order to produce more credible data for temporal prediction models. We present an activity-based sampling approach where users are selected based on their historical activities in Twitter. The predictability of the collected content from activity-based and random sampling is compared in a content-based and user-centric temporal model. The results indicate the importance of an activity-oriented sampling method for the acquisition of more credible content for temporal models
Short-term prediction of NO 2 and NO x concentrations using multilayer perceptron neural network: a case study of Tabriz, Iran
No full textAbstract
Introduction
Due to the health effects caused by airborne pollutants in urban areas, forecasting of air quality parameters is one of the most important topics of air quality research. During recent years, statistical models based on artificial neural networks (ANNs) have been increasingly applied and evaluated for forecasting of air quality.
Methods
The development of ANN and multiple linear regressions (MLRs) has been applied to short-term prediction of the NO
2
and NO
x
concentrations as a function of meteorological conditions. The optimum structure of ANN was determined by a trial and error method. We used hourly NO
x
and NO
2
concentrations and metrological parameters, automatic monitoring network during October and November 2012 for two monitoring sites (Abrasan and Farmandari sites) in Tabriz, Iran.
Results
Designing of the network architecture is based on the approximation theory of Kolmogorov, and the structure of ANN with 30 neurons had the best performance. ANN trained by scaled-conjugate-gradient (trainscg) training algorithm has implemented to model. It also demonstrates that MLP neural networks offer several advantages over linear MLR models. The results show that the correlation coefficient ( R
2
) values are 0.92 and 0/94 for NO
2
and NO
x
concentrations, respectively. But in MLR model, R
2
values were 0.41 and 0.44 for NO
2
and NO
x
concentrations, respectively.
Conclusions
This work shows that MLP neural networks can accurately model the relationship between local meteorological data and NO
2
and NO
x
concentrations in an urban environment compared to linear models
Prospective surveillance of healthcare associated infections in a Cambodian pediatric hospital
No full textAbstract
Background
Healthcare associated infections (HAI) are the most common preventable adverse events following admission to healthcare facilities. Data from low-income countries are scarce. We sought to prospectively define HAI incidence at Angkor Hospital for Children (AHC), a Cambodian pediatric referral hospital.
Methods
Prospective HAI surveillance was introduced for medical admissions to AHC. Cases were identified on daily ward rounds and confirmed using locally adapted Centers for Disease Control and Prevention (CDC) definitions. During the surveillance period, established infection prevention and control (IPC) activities continued, including hand hygiene surveillance. In addition, antimicrobial stewardship practices such as the creation of an antimicrobial guideline smartphone app were introduced.
Results
Between 1st January and 31st December 2015 there were 3,263 medical admissions and 102 HAI cases. The incidence of HAI was 4.6/1,000 patient-days (95% confidence interval 3.8\u20135.6) and rates were highest amongst neonates. Median length of stay was significantly longer in HAI cases: 25\ua0days versus 5\ua0days for non-HAI cases ( p \u2009<\u20090.0001). All-cause in-hospital mortality increased from 2.0 to 16.1% with HAI ( p \u2009<\u20090.0001). Respiratory infections were the most common HAI (54/102; 52.9%). Amongst culture positive infections, Gram-negative organisms predominated (13/16; 81.3%). Resistance to third generation cephalosporins was common, supporting the use of more expensive carbapenem drugs empirically in HAI cases. The total cost of treatment for all 102 HCAI cases combined, based on additional inpatient days, was estimated to be $299,608.
Conclusions
Prospective HAI surveillance can form part of routine practice in low-income healthcare settings. HAI incidence at AHC was relatively low, but human and financial costs remained high due to increased carbapenem use, prolonged admissions and higher mortality rates
An assessment of moisture induced damage in Blickling Hall in Norfolk, England, via environmental monitoring
No full textAbstract
In the last few decades, extreme weather events mostly characterized by more intense and frequent precipitation and wind incidents have risen, and current climatic projections strongly suggest that this trend will keep its pace in the future. These climatic conditions pose additional hygrothermal loading onto the built environment, which may lead to moisture induced deterioration and even strength reduction in masonry. Despite their already long service lives, this impact may in time become problematic for historic buildings, which, by nature of their design and construction, interact with moisture and climate to a far greater degree than modern buildings. The PARNASSUS project was set up with the aim of identifying and quantifying the impact of environment on historic buildings in the face of a changing climate. As part of this project, an extensive environmental monitoring campaign was carried out between 2012 and 2014 at Blicking Hall, a National Trust property in Norfolk, England, with the aim of providing further insight into the building\u2019s overall performance under hygrothermal loading. Environmental monitoring work targeted not only indoor and outdoor conditions, but provided information about the temperature and relative humidity profiles across the walls by means of in-wall probes. Wind and rain gauges helped quantify other environmental parameters. This paper presents the findings from this environmental monitoring work, with specific emphasis on the basement suffering from sustained saturation in vapour phase and resulting biological growth, as well as the Long Gallery, where Blickling\u2019s valuable library is kept
Water-mediated NOE: a promising tool for interrogating interfacial clay\u2013xenobiotic interactions
No full textAbstract
Background
The sorption of anthropogenic compounds on clay minerals is a complex molecular process with important implications for the fate of agrochemicals and organic pollutants in the environment.
Results
The present study illustrates the use of a water-mediated NOE approach to study clay binding interactions. This method exploits the interfacial water layer on clay surfaces as a hydrogen reservoir for magnetization transfer. The interactions of four different xenobiotics with clay suspension were investigated through this method to demonstrate its capability to screen for the clay\u2013xenobiotic molecular affinity. Further, based on the NOE build-up rates, epitope map of clay\u2013xenobiotic interactions can be generated, explaining the orientation and mechanism of the interactions.
Conclusions
The water-mediated NOE approach has the potential to reveal key insights into the role that interfacial water plays in the binding process, providing a better understanding of the partitioning of anthropogenic compounds from bulk water into aqueous clay suspensions.
Graphical abstract
An exploratory study of ESL writing by junior secondary students in China: text type, register and textual features
No full textAbstract
While interest in L2 writing research has increased exponentially in recent years, research on adolescent L2 writing remains relatively scarce. Drawing on the framework of functional text analysis, namely context-based text typology and register theory, the present study aimed to explore Chinese adolescent L2 writing from the perspective of writing as meaning making. Ten instances of writing tasks written by a class of 50 junior secondary students from Guangzhou, China were collected. Context-based text typology and field, mode tenor from register theory were used to analyze the participants\u2019 writing. The findings revealed that recommending was the dominant text type in the students\u2019 writing because of the influence of the exam-driven culture. Moreover, tenor awareness was lacking in the students\u2019 writing. Relevant Chinese secondary L2 writing curriculum design and pedagogy recommendations are provided