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research methods

Paul D Blischak, Julia Chifman, Andrea D Wolfe, Laura S Kubatko
The analysis of hybridization and gene flow among closely related taxa is a common goal for researchers studying speciation and phylogeography. Many methods for hybridization detection use simple site pattern frequencies from observed genomic data and compare them to null models that predict an absence of gene flow. The theory underlying the detection of hybridization using these site pattern probabilities exploits the relationship between the coalescent process for gene trees within population trees and the process of mutation along the branches of the gene trees...
March 19, 2018: Systematic Biology
Riza Eka Saputra, Yayuk Astuti, Adi Darmawan
This work investigated the synthesis of dimethoxydimethylsilane:tetraethoxysilane (DMDMS:TEOS) silica thin films as well as the effect of DMDMS:TEOS molar ratios and calcination temperature on hydrophobic properties of silica thin films and its correlation with the FTIR spectra behaviour. The silica thin films were synthesized by sol-gel method using combination of DMDMS and TEOS as silica precursors, ethanol as solvent and ammonia as catalyst, with DMDMS and TEOS molar ratio of 10:90, 25:75, 50:50, 75:25 and 90:10...
March 14, 2018: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
Karl Kuntzelman, L Jack Rhodes, Lillian N Harrington, Vladimir Miskovic
There is a broad family of statistical methods for capturing time series regularity, with increasingly widespread adoption by the neuroscientific community. A common feature of these methods is that they permit investigators to quantify the entropy of brain signals - an index of unpredictability/complexity. Despite the proliferation of algorithms for computing entropy from neural time series data there is scant evidence concerning their relative stability and efficiency. Here we evaluated several different algorithmic implementations (sample, fuzzy, dispersion and permutation) of multiscale entropy in terms of their stability across sessions, internal consistency and computational speed, accuracy and precision using a combination of electroencephalogram (EEG) and synthetic 1/ƒ noise signals...
March 18, 2018: Brain and Cognition
Reid Tingley, Georgia Ward-Fear, Lin Schwarzkopf, Matthew J Greenlees, Benjamin L Phillips, Gregory Brown, Simon Clulow, Jonathan Webb, Robert Capon, Andy Sheppard, Tanja Strive, Mark Tizard, Richard Shine
Our best hope of developing innovative methods to combat invasive species is likely to come from the study of high-profile invaders that have attracted intensive research not only into control, but also basic biology. Here we illustrate that point by reviewing current thinking about novel ways to control one of the world’s most well-studied invasions: that of the cane toad in Australia. Recently developed methods for population suppression include more effective traps based on the toad’s acoustic and pheromonal biology...
June 2017: Quarterly Review of Biology
Burcu Şerbetçioğlu Sert, Benan İnan, Didem Özçimen
In recent years, algal bioethanol production comes into prominence as a trend towards sustainable development. Due to being sustainable energy source and environmental friendly, bioethanol production from algae is becoming increasingly popular all over the world. However, yield of bioethanol production from algae is lower than first generation feedstock's currently, and needs to be improved. In order to increase bioethanol yield, pre-treatments should be performed as cell disruption process on algal biomass...
March 2018: Acta Chimica Slovenica
Seyed Mostafa Hasan Nasrollahi, Mohammad Ali Ghasemzadeh, Mohammad Reza Zolfaghari
The synthesis of heterocyclic compounds has been a topic of significant interest because of their broad applications. In this research an effective and eco-friendly approach for the synthesis 1,4-dihydropyridines has been developed via the four-component reactions of arylamines, acetylenedicarboxylates, aromatic aldehydes and ethyl acetoacetate in the presence of Fe3O4@SiO2@OSO3H nanocomposite under solvent-free conditions. The advantages of this method involve the green reaction conditions, simple workup, broad substrates, excellent yields and the reuse of the nanocatalyst...
March 2018: Acta Chimica Slovenica
Wenjun Liu, Mengli Liu, Jinde Yin, Hao Chen, Wei Lu, Shaobo Fang, Hao Teng, Ming Lei, Peiguang Yan, Zhiyi Wei
Two-dimensional materials have become the focus of research for their photoelectric properties, and are employed as saturable absorption materials. Currently, the challenge is how to further improve the modulation depth of saturable absorbers (SAs) based on two-dimensional materials. In this paper, three kinds of WSe2 films with different thicknesses are prepared using the chemical vapor deposition method. The nonlinear optical responses of the WSe2 films including the nonlinear saturable absorption and nonlinear refractive index are characterized by the double-balanced detection method and Z-scan experiments...
March 21, 2018: Nanoscale
Nedeljka Ivković, Maja Racic, Radoslavka Lecic, Djordje Bozovic, Milan Kulic
AIMS: To evaluate whether serum estrogen level is associated with chronic pain, masticatory dysfunction, and depressive symptoms and/or somatization in women with temporomandibular disorders (TMD) and different menstrual cycle status. METHODS: A total of 64 women were allocated into one of three groups: one composed of women with normal menstrual cycles (Group 1), one composed of pregnant women (Group 2), and one composed of women in surgical menopause (Group 3)...
March 21, 2018: Journal of Oral & Facial Pain and Headache
Frédéric Kosmowski, Tigist Worku
Crop cultivar identification is fundamental for agricultural research, industry and policies. This paper investigates the feasibility of using visible/near infrared hyperspectral data collected with a miniaturized NIR spectrometer to identify cultivars of barley, chickpea and sorghum in the context of Ethiopia. A total of 2650 grains of barley, chickpea and sorghum cultivars were scanned using the SCIO, a recently released miniaturized NIR spectrometer. The effects of data preprocessing techniques and choosing a machine learning algorithm on distinguishing cultivars are further evaluated...
2018: PloS One
Tomáš Glomb, Adam Mertel, Zdeněk Pospíšil, Zdeněk Stachoň, Aleš Chalupa
Early in the Ptolemaic era, Egyptian cults, particularly those of Isis and Sarapis, spread successfully to ports across the ancient Aegean Sea. Leading researchers in the field claim that the spread of these cults was influenced by multiple factors, ones that were mainly economic or political in character. However, the question of which factors had more weight or impact than others in the process of the early spread of Egyptian cults has not yet been answered in academic discussion. This could be related to the fact that the issue of the spread of religious innovations in the ancient Mediterranean has been addressed mainly by established historiographical methods such as the collection and critical analysis of archaeological and literary sources...
2018: PloS One
Kena Song, Zirui Wang, Ruchuan Liu, Guo Chen, Liyu Liu
Exploring the complicated development of tumors and metastases needs a deep understanding of the physical and biological interactions between cancer cells and their surrounding microenvironments. One of the major challenges is the ability to mimic the complex 3-D tissue microenvironment that particularly influences cell proliferation, migration, invasion, and apoptosis in relation to the extracellular matrix (ECM). Traditional cell culture is unable to create 3-D cell scaffolds resembling tissue complexity and functions, and, in the past, many efforts were made to realize the goal of obtaining cell clusters in hydrogels...
March 21, 2018: International Journal of Molecular Sciences
Tan Li, Qingguo Zhang, Ying Zhang
The assessment of forest ecosystem services can quantify the impact of these services on human life and is the main basis for formulating a standard of compensation for these services. Moreover, the calculation of the indirect value of forest ecosystem services should not be ignored, as has been the case in some previous publications. A low compensation standard and the lack of a dynamic coordination mechanism are the main problems existing in compensation implementation. Using comparison and analysis, this paper employed accounting for both the costs and benefits of various alternatives...
March 21, 2018: International Journal of Environmental Research and Public Health
Dong An, Chengchen Guo, Yanan Chen
Analysis of polycyclic aromatic hydrocarbons (PAHs) in air and water sources is a key part of environmental chemistry research, since most PAHs are well known to be associated with negative health impacts on humans. This study explores an approach for analyzing PAH mixtures with advanced nuclear magnetic resonance (NMR) spectroscopic techniques including high-resolution one-dimensional (1D) NMR spectroscopy and diffusion-ordered NMR spectroscopy (DOSY NMR). With this method, different kinds of PAHs can be detected and differentiated from a mixture with high resolution...
March 21, 2018: Materials
Patrick U Osadebe
The study was carried out to assess the difficulty index of each item of an Economics Achievement test with the Rasch model. The infit and outfit as well as the reliability of the test were determined. Three research questions were drawn to guide the study. A sample of 200 was randomly selected using simple random sampling of balloting and proportionate stratified random sampling. The instrument of the study was an Economics Achievement Test with 100 items. The test has face and content validities. It has a reliability coefficient of 0...
2018: Journal of Applied Measurement
W Holmes Finch, Maria Hernandez Finch, Brian F French, David E McIntosh, Lauren Moss
An important aspect of the educational and psychological evaluation of individuals is the selection of scales with appropriate evidence of reliability and validity for inferences and uses of the scores for the population of interest. One key aspect of validity is the degree to which a scale fairly assesses the construct(s) of interest for members of different subgroups within the population. Typically, this issue is addressed statistically through assessment of differential item functioning (DIF) of individual items, or differential test functioning (DTF) of sets of items within the same measure...
2018: Journal of Applied Measurement
Yang Gao, Xiaoliang Fang, Janping Tan, Ting Lu, Linkun Pan, Fu-Zhen Xuan
Wearable strain sensors based on nanomaterial/elastomer composites have potential applications in flexible electronic skin, human motion detection, human-machine interfaces, etc. In this research, a type of high performance strain sensors have been developed using fragmentized carbon nanotube/polydimethylsiloxane (CNT/PDMS) composites. The CNT/PDMS composites were ground into fragments, and a liquid-induced densification method was used to fabricate the strain sensors. The strain sensors showed high sensitivity with gauge factors (GFs) larger than 200 and a broad strain detection range up to 80%, much higher than those strain sensors based on unfragmentized CNT/PDMS composites (GF <1)...
March 21, 2018: Nanotechnology
Asmahan Elgellaie, Elfriede Ashcroft, Theresa A Larkin
Intramuscular injections given at the dorsogluteal and ventrogluteal sites are intended for the gluteus maximus and gluteus medius muscles, respectively. However, little research has confirmed the reliability of these sites for the presence and thickness of the target and other muscles, and subcutaneous fat. This study characterised and compared these at the V-method and G-method ventrogluteal sites and dorsogluteal site (n=60). Gluteus maximus, medius and minimus were identified at each site, plus tensor fascia latae at ventrogluteal sites...
March 22, 2018: British Journal of Nursing: BJN
Jacquelyn J Cragg, Freda M Warner, Matthew S Shupler, Catherine R Jutzeler, Neil Cashman, David G T Whitehurst, John K Kramer
BACKGROUND: The prevalence of pain among people with a variety of individual neurological conditions has been estimated. However, information is limited about chronic pain among people with neurological conditions overall, and about the conditions for which chronic pain is most prevalent. To fill these information gaps, a common method of pain assessment is required. DATA AND METHODS: The data are from the Survey on Living with Neurological Conditions in Canada, a cross-sectional national survey...
March 21, 2018: Health Reports
Cheng-Yu Shih, René Streubel, Johannes Heberle, Alexander Letzel, Maxim V Shugaev, Chengping Wu, Michael Schmidt, Bilal Gökce, Stephan Barcikowski, Leonid V Zhigilei
The synthesis of chemically clean and environmentally friendly nanoparticles through pulsed laser ablation in liquids has shown a number of advantages over conventional chemical synthesis methods and has evolved into a thriving research field attracting laboratory and industrial applications. The fundamental understanding of processes leading to the nanoparticle generation, however, still remains elusive. In particular, the origin of bimodal nanoparticle size distributions in femto- and picosecond laser ablation in liquids, where small nanoparticles (several nanometers) with narrow size distribution are commonly observed to coexist with larger (tens to hundreds of nanometers) ones, has not been explained so far...
March 21, 2018: Nanoscale
Matilde Inglese, Maria Petracca
PURPOSE OF REVIEW: Clinical MRI is of paramount importance for multiple sclerosis diagnosis but lacks the specificity to investigate the pathogenic mechanisms underlying disease onset and progression. The application of advanced magnetic resonance (MR) sequences allows the characterization of diverse and complex pathological mechanisms, granting insights into multiple sclerosis natural history and response to treatment. RECENT FINDINGS: This review provides an update on the most recent international guidelines for optimal standard imaging of multiple sclerosis and discusses advantages and limitations of advanced imaging approaches for investigating inflammation, demyelination and neurodegeneration...
March 19, 2018: Current Opinion in Neurology
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