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https://www.readbyqxmd.com/read/29150760/slow-passage-through-a-hopf-bifurcation-in-excitable-nerve-cables-spatial-delays-and-spatial-memory-effects
#1
L M Bilinsky, S M Baer
It is well established that in problems featuring slow passage through a Hopf bifurcation (dynamic Hopf bifurcation) the transition to large-amplitude oscillations may not occur until the slowly changing parameter considerably exceeds the value predicted from the static Hopf bifurcation analysis (temporal delay effect), with the length of the delay depending upon the initial value of the slowly changing parameter (temporal memory effect). In this paper we introduce new delay and memory effect phenomena using both analytic (WKB method) and numerical methods...
November 17, 2017: Bulletin of Mathematical Biology
https://www.readbyqxmd.com/read/29150693/a-collection-of-genetically-engineered-populus-trees-reveals-wood-biomass-traits-that-predict-glucose-yield-from-enzymatic-hydrolysis
#2
Sacha Escamez, Madhavi Latha Gandla, Marta Derba-Maceluch, Sven-Olof Lundqvist, Ewa J Mellerowicz, Leif J Jönsson, Hannele Tuominen
Wood represents a promising source of sugars to produce bio-based renewables, including biofuels. However, breaking down lignocellulose requires costly pretreatments because lignocellulose is recalcitrant to enzymatic saccharification. Increasing saccharification potential would greatly contribute to make wood a competitive alternative to petroleum, but this requires improving wood properties. To identify wood biomass traits associated with saccharification, we analyzed a total of 65 traits related to wood chemistry, anatomy and structure, biomass production and saccharification in 40 genetically engineered Populus tree lines...
November 17, 2017: Scientific Reports
https://www.readbyqxmd.com/read/29150667/a-molecular-mechanism-of-symmetry-breaking-in-the-early-chick-embryo
#3
Clemente F Arias, Miguel A Herrero, Claudio D Stern, Federica Bertocchini
The first obvious sign of bilateral symmetry in mammalian and avian embryos is the appearance of the primitive streak in the future posterior region of a radially symmetric disc. The primitive streak marks the midline of the future embryo. The mechanisms responsible for positioning the primitive streak remain largely unknown. Here we combine experimental embryology and mathematical modelling to analyse the role of the TGFβ-related molecules BMP4 and Vg1/GDF1 in positioning the primitive streak. Bmp4 and Vg1 are first expressed throughout the embryo, and then become localised to the future anterior and posterior regions of the embryo, where they will, respectively, inhibit or induce formation of the primitive streak...
November 17, 2017: Scientific Reports
https://www.readbyqxmd.com/read/29150367/ileocolic-intussusception-predicting-the-probability-of-success-of-ultrasound-guided-saline-enema-from-clinical-and-sonographic-data
#4
REVIEW
A Soria, L Riaza, D Cuadras, X Tarrado, L Krauel
BACKGROUND/PURPOSE: To identify factors that dim the efficacy of ultrasound guided saline enema (USGSE) and to design a mathematical model for predicting the probability of success of USGSE. METHODS: Retrospective review of patients admitted with the diagnosis of ileocolic intussusception from 2009 to 2014. Demographics, clinical and sonographic data were reviewed. RESULTS: 116 first episodes of ileocolic intussusceptions. 109 USGSE attempts were analyzed...
November 14, 2017: Journal of Pediatric Surgery
https://www.readbyqxmd.com/read/29150260/prioritizing-and-optimizing-sustainable-measures-for-food-waste-prevention-and-management
#5
Jorge Cristóbal, Valentina Castellani, Simone Manfredi, Serenella Sala
Food waste has gained prominence in the European political debate thanks to the recent Circular Economy package. Currently the waste hierarchy, introduced by the Waste Framework Directive, has been the rule followed to prioritize food waste prevention and management measures according to the environmental criteria. But when considering other criteria along with the environmental one, such as the economic, other tools are needed for the prioritization and optimization. This paper addresses the situation in which a decision-maker has to design a food waste prevention programme considering the limited economic resources in order to achieve the highest environmental impact prevention along the whole food life cycle...
November 14, 2017: Waste Management
https://www.readbyqxmd.com/read/29149765/sorption-desorption-of-antimony-species-onto-calcined-hydrotalcite-surface-structure-and-control-of-competitive-anions
#6
Leonel Vinicius Constantino, Juliana Nunes Quirino, Taufik Abrão, Paulo Sérgio Parreira, Alexandre Urbano, Maria Josefa Santos
Calcined hydrotalcite can be applied to remove anionic contaminants from aqueous systems such as antimony species due to its great anion exchange capacity and high surface area. Hence, this study evaluated antimonite and antimonate sorption-desorption processes onto calcined hydrotalcite in the presence of nitrate, sulfate and phosphate. Sorption and desorption experiments of antimonite and antimonate were carried out in batch equilibrium and the post-sorption solids were analyzed by X-ray fluorescence (EDXRF)...
November 10, 2017: Journal of Hazardous Materials
https://www.readbyqxmd.com/read/29149173/trade-off-and-flexibility-in-the-dynamic-regulation-of-the-cullin-ring-ubiquitin-ligase-repertoire
#7
Ronny Straube, Meera Shah, Dietrich Flockerzi, Dieter A Wolf
Cullin-RING ubiquitin ligases (CRLs) catalyze the ubiquitylation of substrates many of which are degraded by the 26S proteasome. Their modular architecture enables recognition of numerous substrates via exchangeable substrate receptors that competitively bind to a cullin scaffold with high affinity. Due to the plasticity of these interactions there is ongoing uncertainty how cells maintain a flexible CRL repertoire in view of changing substrate loads. Based on a series of in vivo and in vitro studies, different groups proposed that the exchange of substrate receptors is mediated by a protein exchange factor named Cand1...
November 17, 2017: PLoS Computational Biology
https://www.readbyqxmd.com/read/29149069/temperature-uncertainty-analysis-of-injection-mechanism-based-on-kriging-modeling
#8
Dongdong You, Dehui Liu, Xiaomo Jiang, Xueyu Cheng, Xiang Wang
A kriging modeling method is proposed to conduct the temperature uncertainty analysis of an injection mechanism in squeeze casting. A mathematical model of temperature prediction with multi input and single output is employed to estimate the temperature spatiotemporal distributions of the injection mechanism. The kriging model applies different weights to the independent variables according to spatial location of sample points and their correlation, thus reducing the estimation variance. The predicted value of the kriging model is compared with the sample data at the corresponding position to investigate the influence of the temperature uncertainty of the injection mechanism on the injection process including friction...
November 17, 2017: Materials
https://www.readbyqxmd.com/read/29149054/a-dual-polymer-fiber-fizeau-interferometer-for-simultaneous-measurement-of-relative-humidity-and-temperature
#9
Chao-Tsung Ma, Yu-Wei Chang, Yuan-Jie Yang, Cheng-Ling Lee
This paper presents a novel design method in which a dual-polymer fiber Fizeau interferometer (DPFFI) is proposed for simultaneously measuring relative humidity (RH) and temperature (T). Since the polymer is intrinsically highly sensitive to both RH and T, the polymer fiber Fizeau interferometer (PFFI) exhibits cross-sensitivity of RH and T. In general, it is difficult to demodulate the optical responses from both variations of RH and T using a single PFFI. If two PFFIs with different structures are combined, they will individually exhibit distinct sensitivity responses with respect to RH and T, respectively...
November 17, 2017: Sensors
https://www.readbyqxmd.com/read/29148804/a-nanobionic-light-emitting-plant
#10
Seon-Yeong Kwak, Juan Pablo Giraldo, Min Hao Wong, Volodymyr Koman, Tedrick Lew, Jon Ell, Mark Weidman, Rosalie Sinclair, Markita P Landry, William A Tisdale, Michael S Strano
The engineering of living plants for visible light emission and sustainable illumination is compelling because plants possess independent energy generation and storage mechanisms and autonomous self-repair. Herein, we demonstrate a plant nanobionic approach that enables exceptional luminosity and lifetime utilizing four chemically-interacting nanoparticles, including firefly luciferase conjugated silica (SNP-Luc), D-luciferin releasing poly(lactic-co-glycolic acid) (PLGA-LH2), coenzyme A functionalized chitosan (CS-CoA) and semiconductor nanocrystal phosphors for longer wavelength modulation...
November 17, 2017: Nano Letters
https://www.readbyqxmd.com/read/29147828/a-reliable-spectral-method-to-reaction-diffusion-equations-in-entrapped-cell-photobioreactor-packed-with-gel-granules-using-chebyshev-wavelets
#11
M Salai Mathi Selvi, G Hariharan, K Kannan
A mathematical model of a reaction-diffusion within an entrapped-cell photobioreactor packed with gel granules containing immobilized photosynthetic bacterial cells is discussed. A theoretical model is based on a system of coupled nonlinear reaction-diffusion equations. In this research work, we have developed an efficient wavelet-based spectral approach for solving the proposed model. Analytical expressions for the concentration of substrate and product are established for all values of reaction-diffusion parameters using second kind Chebyshev wavelet method...
November 17, 2017: Journal of Membrane Biology
https://www.readbyqxmd.com/read/29147036/measuring-arithmetic-a-psychometric-approach-to-understanding-formatting-effects-and-domain-specificity
#12
Katherine T Rhodes, Lee Branum-Martin, Julie A Washington, Lynn S Fuchs
Using multitrait, multimethod data, and confirmatory factor analysis, the current study examined the effects of arithmetic item formatting and the possibility that across formats, abilities other than arithmetic may contribute to children's answers. Measurement hypotheses were guided by several leading theories of arithmetic cognition. With a sample of 1314 3rd grade students (age M=103.24 months, SD=5.41 months), Abstract Code Theory, Encoding Complex Theory, Triple Code Theory, and the Exact versus Approximate Calculations Hypothesis were evaluated, using 11 measures of arithmetic with symbolic problem formats (e...
October 2017: Journal of Educational Psychology
https://www.readbyqxmd.com/read/29147005/binary-phase-masks-for-easy-system-alignment-and-basic-aberration-sensing-with-spatial-light-modulators-in-sted-microscopy
#13
André Klauss, Florian Conrad, Carsten Hille
The use of binary phase patterns to improve the integration and optimization of spatial light modulators (SLM) in an imaging system, especially a confocal microscope, is proposed and demonstrated. The phase masks were designed to create point spread functions (PSF), which exhibit specific sensitivity to major disturbances in the optical system. This allows direct evaluation of misalignment and fundamental aberration modes by simple visual inspection of the focal intensity distribution or by monitoring the central intensity of the PSF...
November 16, 2017: Scientific Reports
https://www.readbyqxmd.com/read/29146925/to-infinity-and-some-glimpses-of-beyond
#14
Panayotis G Kevrekidis, Constantinos I Siettos, Yannis G Kevrekidis
When mathematical and computational dynamic models reach infinity in finite time, extending analysis and numerics beyond it becomes a notorious challenge. We suggest how, upon suitable transformations, it may become possible to go beyond infinity with the solution becoming again well behaved and the computations continuing normally. In our Ordinary Differential Equation examples the crossing of infinity occurs instantaneously. For Partial Differential Equations, the crossing of infinity may persist for finite time, necessitating the introduction of buffer zones, within which an appropriate transformation is adaptively identified...
November 16, 2017: Nature Communications
https://www.readbyqxmd.com/read/29146694/spatiotemporal-distribution-of-%C3%AE-amyloid-in-alzheimer-s-disease-results-from-heterogeneous-regional-carrying-capacities
#15
Alex Whittington, David J Sharp, Roger N Gunn
β-amyloid (Aβ) accumulation in the brain is one of two pathological hallmarks of Alzheimer's Disease (AD) and its spatial distribution has been studied extensively ex vivo. We apply mathematical modelling to Aβ in vivo PET imaging data in order to investigate competing theories of Aβ spread in AD. Our results provide evidence that Aβ accumulation starts in all brain regions simultaneously and that its spatiotemporal distribution is a result of heterogeneous regional carrying capacities (regional maximum possible concentration of Aβ) for the aggregated protein rather than longer term spreading from seed regions...
November 16, 2017: Journal of Nuclear Medicine: Official Publication, Society of Nuclear Medicine
https://www.readbyqxmd.com/read/29146667/building-better-bridges-into-stem-a-synthesis-of-25-years-of-literature-on-stem-summer-bridge-programs
#16
Michael Ashley, Katelyn M Cooper, Jacqueline M Cala, Sara E Brownell
Summer bridge programs are designed to help transition students into the college learning environment. Increasingly, bridge programs are being developed in science, technology, engineering, and mathematics (STEM) disciplines because of the rigorous content and lower student persistence in college STEM compared with other disciplines. However, to our knowledge, a comprehensive review of STEM summer bridge programs does not exist. To provide a resource for bridge program developers, we conducted a systematic review of the literature on STEM summer bridge programs...
2017: CBE Life Sciences Education
https://www.readbyqxmd.com/read/29146178/use-of-mathematical-modelling-to-assess-the-impact-of-vaccines-on-antibiotic-resistance
#17
REVIEW
Katherine E Atkins, Erin I Lafferty, Sarah R Deeny, Nicholas G Davies, Julie V Robotham, Mark Jit
Antibiotic resistance is a major global threat to the provision of safe and effective health care. To control antibiotic resistance, vaccines have been proposed as an essential intervention, complementing improvements in diagnostic testing, antibiotic stewardship, and drug pipelines. The decision to introduce or amend vaccination programmes is routinely based on mathematical modelling. However, few mathematical models address the impact of vaccination on antibiotic resistance. We reviewed the literature using PubMed to identify all studies that used an original mathematical model to quantify the impact of a vaccine on antibiotic resistance transmission within a human population...
November 13, 2017: Lancet Infectious Diseases
https://www.readbyqxmd.com/read/29145509/untargeted-mass-spectrometry-discloses-plasma-solute-levels-poorly-controlled-by-hemodialysis
#18
Tammy L Sirich, Pavel A Aronov, Jonathan Fullman, Khanh Nguyen, Natalie S Plummer, Timothy W Meyer
Many solutes have been reported to remain at higher plasma levels relative to normal than the standard index solute urea in hemodialysis patients. Untargeted mass spectrometry was employed to compare solute levels in plasma and plasma ultrafiltrate of hemodialysis patients and normal subjects. Quantitative assays were employed to check the accuracy of untargeted results for selected solutes and additional measurements were made in dialysate and urine to estimate solute clearances and production. Comparison of peak areas indicated that many solutes accumulated to high levels in hemodialysis patients, with average peak areas in plasma ultrafiltrate of dialysis patients being more than 100 times greater than those in normals for 123 features...
2017: PloS One
https://www.readbyqxmd.com/read/29145389/the-use-of-ambient-humidity-conditions-to-improve-influenza-forecast
#19
Jeffrey Shaman, Sasikiran Kandula, Wan Yang, Alicia Karspeck
Laboratory and epidemiological evidence indicate that ambient humidity modulates the survival and transmission of influenza. Here we explore whether the inclusion of humidity forcing in mathematical models describing influenza transmission improves the accuracy of forecasts generated with those models. We generate retrospective forecasts for 95 cities over 10 seasons in the United States and assess both forecast accuracy and error. Overall, we find that humidity forcing improves forecast performance (at 1-4 lead weeks, 3...
November 16, 2017: PLoS Computational Biology
https://www.readbyqxmd.com/read/29145014/ecotracer-analyzing-concentration-of-contaminants-and-radioisotopes-in-an-aquatic-spatial-dynamic-food-web-model
#20
William J Walters, Villy Christensen
Ecotracer is a tool in the Ecopath with Ecosim (EwE) software package used to simulate and analyze the transport of contaminants such as methylmercury or radiocesium through aquatic food webs. Ecotracer solves the contaminant dynamic equations simultaneously with the biomass dynamic equations in Ecosim/Ecospace. In this paper, we give a detailed description of the Ecotracer module and analyze the performance on two problems of differing complexity. Ecotracer was modified from previous versions to more accurately model contaminant excretion, and new numerical integration algorithms were implemented to increase accuracy and robustness...
November 13, 2017: Journal of Environmental Radioactivity
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