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https://www.readbyqxmd.com/read/28215045/a-generalized-partially-linear-mean-covariance-regression-model-for-longitudinal-proportional-data-with-applications-to-the-analysis-of-quality-of-life-data-from-cancer-clinical-trials
#1
Xueying Zheng, Guoyou Qin, Dongsheng Tu
Motivated by the analysis of quality of life data from a clinical trial on early breast cancer, we propose in this paper a generalized partially linear mean-covariance regression model for longitudinal proportional data, which are bounded in a closed interval. Cholesky decomposition of the covariance matrix for within-subject responses and generalized estimation equations are used to estimate unknown parameters and the nonlinear function in the model. Simulation studies are performed to evaluate the performance of the proposed estimation procedures...
February 19, 2017: Statistics in Medicine
https://www.readbyqxmd.com/read/28214390/robust-peptidoglycan-growth-by-dynamic-and-variable-multi-protein-complexes
#2
REVIEW
Manuel Pazos, Katharina Peters, Waldemar Vollmer
In Gram-negative bacteria such as Escherichia coli the peptidoglycan sacculus resides in the periplasm, a compartment that experiences changes in pH value, osmolality, ion strength and other parameters depending on the cell's environment. Hence, the cell needs robust peptidoglycan growth mechanisms to grow and divide under different conditions. Here we propose a model according to which the cell achieves robust peptidoglycan growth by employing dynamic multi-protein complexes, which assemble with variable composition from freely diffusing sets of peptidoglycan synthases, hydrolases and their regulators, whereby the composition of the active complexes depends on the cell cycle state - cell elongation or division - and the periplasmic growth conditions...
February 15, 2017: Current Opinion in Microbiology
https://www.readbyqxmd.com/read/28213832/dynamic-fluorescence-microscopy-of-cellular-uptake-of-intercalating-model-drugs-by-ultrasound-activated-microbubbles
#3
B H A Lammertink, R Deckers, M Derieppe, I De Cock, I Lentacker, G Storm, C T W Moonen, C Bos
PURPOSE: The combination of ultrasound and microbubbles can facilitate cellular uptake of (model) drugs via transient permeabilization of the cell membrane. By using fluorescent molecules, this process can be studied conveniently with confocal fluorescence microscopy. This study aimed to investigate the relation between cellular uptake and fluorescence intensity increase of intercalating model drugs. PROCEDURES: SYTOX Green, an intercalating fluorescent dye that displays >500-fold fluorescence enhancement upon binding to nucleic acids, was used as a model drug for ultrasound-induced cellular uptake...
February 17, 2017: Molecular Imaging and Biology: MIB: the Official Publication of the Academy of Molecular Imaging
https://www.readbyqxmd.com/read/28213759/convection-of-a-colloidal-suspension-in-a-hele-shaw-cell
#4
B L Smorodin, I N Cherepanov, S N Ishutov, B I Myznikova
The results of a theoretical study are presented dealing with convective heat and mass transfer in a colloidal suspension through a Hele-Shaw cell heated from below. The numerical analysis, based on a multi-component model, reveals that for a certain range of parameter values the dynamical regimes of travelling waves as well as oscillatory fingering formation are stable. The bifurcation phenomena and nonlinear evolution of spatiotemporal patterns that develop in the colloid suspension are modeled and discussed, paying special attention to the combined effects of gravity sedimentation, thermal diffusion with positive separation ratio and convection...
February 2017: European Physical Journal. E, Soft Matter
https://www.readbyqxmd.com/read/28213113/a-variational-bayesian-inference-method-for-parametric-imaging-of-pet-data
#5
M Castellaro, G Rizzo, M Tonietto, M Veronese, F E Turkheimer, M A Chappell, A Bertoldo
In dynamic Positron Emission Tomography (PET) studies, compartmental models provide the richest information on the tracer kinetics of the tissue. Inverting such models at the voxel level is however quite challenging due to the low signal-to-noise ratio of the time activity curves. In this study, we propose the use of a Variational Bayesian (VB) approach to efficiently solve this issue and thus obtain robust quantitative parametric maps. VB was adapted to the non-uniform noise distribution of PET data. Moreover, we propose a novel hierarchical scheme to define the model parameter priors directly from the images in case such information are not available from the literature, as often happens with new PET tracers...
February 14, 2017: NeuroImage
https://www.readbyqxmd.com/read/28212786/interplay-between-microbial-trait-dynamics-and-population-dynamics-revealed-by-the-combination-of-laboratory-experiment-and-computational-approaches
#6
Kenta Suzuki, Yuji Yamauchi, Takehito Yoshida
Filament formation is a common bacterial defense mechanism and possibly has a broad impact on microbial community dynamics. In order to examine the impact of filament formation on population dynamics, we developed an experimental system with a filamentous bacterium Flectobacillus sp. MWH38 and a ciliate predator Tetrahymena pyriformis. In this system, the effective defense of Flectobacillus resulted in the extinction of Tetrahymena by allowing almost no population growth. The result of a kairomone experiment suggested the existence of chemical signals for filament formation...
February 14, 2017: Journal of Theoretical Biology
https://www.readbyqxmd.com/read/28212667/assessing-the-interruption-of-the-transmission-of-human-helminths-with-mass-drug-administration-alone-optimizing-the-design-of-cluster-randomized-trials
#7
Roy Anderson, Sam Farrell, Hugo Turner, Judd Walson, Christl A Donnelly, James Truscott
BACKGROUND: A method is outlined for the use of an individual-based stochastic model of parasite transmission dynamics to assess different designs for a cluster randomized trial in which mass drug administration (MDA) is employed in attempts to eliminate the transmission of soil-transmitted helminths (STH) in defined geographic locations. The hypothesis to be tested is: Can MDA alone interrupt the transmission of STH species in defined settings? Clustering is at a village level and the choice of clusters of villages is stratified by transmission intensity (low, medium and high) and parasite species mix (either Ascaris, Trichuris or hookworm dominant)...
February 17, 2017: Parasites & Vectors
https://www.readbyqxmd.com/read/28212283/the-effects-of-tocotrienol-and-lovastatin-co-supplementation-on-bone-dynamic-histomorphometry-and-bone-morphogenetic-protein-2-expression-in-rats-with-estrogen-deficiency
#8
Kok-Yong Chin, Saif Abdul-Majeed, Norazlina Mohamed, Soelaiman Ima-Nirwana
Both tocotrienol and statins are suppressors of the mevalonate pathway. Supplementation of tocotrienol among statin users could potentially protect them against osteoporosis. This study aimed to compare the effects of tocotrienol and lovastatin co-supplementation with individual treatments on bone dynamic histomorphometric indices and bone morphogenetic protein-2 (BMP-2) gene expression in ovariectomized rats. Forty-eight female Sprague-Dawley rats were randomized equally into six groups. The baseline was sacrificed upon receipt...
February 15, 2017: Nutrients
https://www.readbyqxmd.com/read/28212103/simulation-of-healing-threshold-in-strain-induced-inflammation-through-a-discrete-informatics-model
#9
Israr Ibrahim, Sanjay Venkata Oruganti, Ramana Pidaparti
Respiratory diseases such as asthma and acute respiratory distress syndrome as well as acute lung injury involve inflammation at the cellular level. The inflammation process is very complex and is characterized by the emergence of cytokines along with other changes in cellular processes. Due to the complexity of the various constituents that makes up the inflammation dynamics, it is necessary to develop models that can complement experiments to fully understand inflammatory diseases. In this study, we developed a discrete informatics model based on cellular automata (CA) approach to investigate the influence of elastic field (stretch/strain) on the dynamics of inflammation and account for probabilistic adaptation based on statistical interpretation of existing experimental data...
February 15, 2017: IEEE Journal of Biomedical and Health Informatics
https://www.readbyqxmd.com/read/28212088/multi-scale-7dof-view-adjustment
#10
Isaac Cho, Jialei Li, Zachary Wartell
Multi-scale virtual environments contain geometric details ranging over several orders of magnitude and typically employ out-of-core rendering techniques. When displayed in virtual reality systems this entails using a 7 degree-of-freedom (DOF) view model where view scale is a separate 7th DOF in addition to 6DOF view pose. Dynamic adjustment of this and other view parameters become very important to usability. In this paper, we evaluate how two adjustment techniques interact with uni- and bi-manual 7 degree-of-freedom navigation in DesktopVR and a CAVE...
February 13, 2017: IEEE Transactions on Visualization and Computer Graphics
https://www.readbyqxmd.com/read/28211963/a-parametric-model-of-the-brain-vascular-system-for-estimation-of-the-arterial-input-function-aif-at-the-tissue-level
#11
Siamak P Nejad-Davarani, Hassan Bagher-Ebadian, James R Ewing, Douglas C Noll, Tom Mikkelsen, Michael Chopp, Quan Jiang
In this paper, we introduce a novel model of the brain vascular system, which is developed based on laws of fluid dynamics and vascular morphology. This model is used to address dispersion and delay of the arterial input function (AIF) at different levels of the vascular structure and to estimate the local AIF in DCE images. We developed a method based on the simplex algorithm and Akaike information criterion to estimate the likelihood of the contrast agent concentration signal sampled in DCE images belonging to different layers of the vascular tree or being a combination of different signal levels from different nodes of this structure...
February 17, 2017: NMR in Biomedicine
https://www.readbyqxmd.com/read/28211961/an-extended-vascular-model-for-less-biased-estimation-of-permeability-parameters-in-dce-t1-images
#12
Siamak P Nejad-Davarani, Hassan Bagher-Ebadian, James R Ewing, Douglas C Noll, Tom Mikkelsen, Michael Chopp, Quan Jiang
One of the key elements in dynamic contrast enhanced (DCE) image analysis is the arterial input function (AIF). Traditionally, in DCE studies a global AIF sampled from a major artery or vein is used to estimate the vascular permeability parameters; however, not addressing dispersion and delay of the AIF at the tissue level can lead to biased estimates of these parameters. To find less biased estimates of vascular permeability parameters, a vascular model of the cerebral vascular system is proposed that considers effects of dispersion of the AIF in the vessel branches, as well as extravasation of the contrast agent (CA) to the extravascular-extracellular space...
February 17, 2017: NMR in Biomedicine
https://www.readbyqxmd.com/read/28211906/dynamics-of-male-meiotic-recombination-frequency-during-plant-development-using-fluorescent-tagged-lines-in-arabidopsis-thaliana
#13
Fan Li, Nico De Storme, Danny Geelen
Meiotic homologous recombination plays a central role in creating genetic variability, making it an essential biological process relevant to evolution and crop breeding. In this study, we used pollen-specific fluorescent tagged lines (FTLs) to measure male meiotic recombination frequency during the development of Arabidopsis thaliana. Interestingly, a subset of pollen grains consistently shows loss of fluorescence expression in tested lines. Using nine independent FTL intervals, the spatio-temporal dynamics of male recombination frequency was assessed during plant development, considering both shoot type and plant age as independent parameters...
February 13, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28211736/short-time-behavior-and-criticality-of-driven-lattice-gases
#14
Urna Basu, Valerio Volpati, Sergio Caracciolo, Andrea Gambassi
The nonequilibrium short-time critical behaviors of driven and undriven lattice gases are investigated via Monte Carlo simulations in two spatial dimensions starting from a fully disordered initial configuration. In particular, we study the time evolution of suitably defined order parameters, which account for the strong anisotropy introduced by the homogeneous drive. We demonstrate that, at short times, the dynamics of all these models is unexpectedly described by an effective continuum theory in which transverse fluctuations, i...
February 3, 2017: Physical Review Letters
https://www.readbyqxmd.com/read/28211607/physiological-motion-modeling-for-organ-mounted-robots
#15
Nathan A Wood, David Schwartzman, Marco A Zenati, Cameron N Riviere
BACKGROUND: Organ-mounted robots passively compensate heartbeat and respiratory motion. In model-guided procedures, this motion can be a significant source of information that can be used to aid in localization or to add dynamic information to static preoperative maps. METHODS: Models for estimating periodic motion are proposed for both position and orientation. These models are then tested on animal data and optimal orders are identified. Finally, methods for online identification are demonstrated...
February 17, 2017: International Journal of Medical Robotics + Computer Assisted Surgery: MRCAS
https://www.readbyqxmd.com/read/28211544/upper-critical-field-reaches-90%C3%A2-tesla-near-the-mott-transition-in-fulleride-superconductors
#16
Y Kasahara, Y Takeuchi, R H Zadik, Y Takabayashi, R H Colman, R D McDonald, M J Rosseinsky, K Prassides, Y Iwasa
Controlled access to the border of the Mott insulating state by variation of control parameters offers exotic electronic states such as anomalous and possibly high-transition-temperature (Tc) superconductivity. The alkali-doped fullerides show a transition from a Mott insulator to a superconductor for the first time in three-dimensional materials, but the impact of dimensionality and electron correlation on superconducting properties has remained unclear. Here we show that, near the Mott insulating phase, the upper critical field Hc2 of the fulleride superconductors reaches values as high as ∼90 T-the highest among cubic crystals...
February 17, 2017: Nature Communications
https://www.readbyqxmd.com/read/28210799/dynamic-contrast-enhanced-mr-imaging-pharmacokinetic-parameters-as-predictors-of-treatment-response-of-brain-metastases-in-patients-with-lung-cancer
#17
Grégory Kuchcinski, Emilie Le Rhun, Alexis B Cortot, Elodie Drumez, Romain Duhal, Maxime Lalisse, Julien Dumont, Renaud Lopes, Jean-Pierre Pruvo, Xavier Leclerc, Christine Delmaire
OBJECTIVES: To determine the diagnostic accuracy of pharmacokinetic parameters measured by dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI) in predicting the response of brain metastases to antineoplastic therapy in patients with lung cancer. METHODS: Forty-four consecutive patients with lung cancer, harbouring 123 newly diagnosed brain metastases prospectively underwent conventional 3-T MRI at baseline (within 1 month before treatment), during the early (7-10 weeks) and midterm (5-7 months) post-treatment period...
February 16, 2017: European Radiology
https://www.readbyqxmd.com/read/28210658/patellar-maltracking-persists-in-adolescent-females-with-patellofemoral-pain-a-longitudinal-study
#18
Victor R Carlson, Barry P Boden, Aricia Shen, Jennifer N Jackson, Katharine E Alter, Frances T Sheehan
BACKGROUND: Patellofemoral pain is one of the most common conditions seen in sports medicine practices, particularly among adolescent females. However, the natural history of the underlying pathology in patellofemoral pain during puberty remains poorly understood. PURPOSE: The purpose of this longitudinal study is to assess changes in patellar maltracking patterns in subjects with patellofemoral pain as they mature from mid- to late adolescence. STUDY DESIGN: Cohort study; Level of evidence, 3...
February 2017: Orthopaedic Journal of Sports Medicine
https://www.readbyqxmd.com/read/28210218/phasic-firing-and-coincidence-detection-by-subthreshold-negative-feedback-divisive-or-subtractive-or-better-both
#19
Gemma Huguet, Xiangying Meng, John Rinzel
Phasic neurons typically fire only for a fast-rising input, say at the onset of a step current, but not for steady or slow inputs, a property associated with type III excitability. Phasic neurons can show extraordinary temporal precision for phase locking and coincidence detection. Exemplars are found in the auditory brain stem where precise timing is used in sound localization. Phasicness at the cellular level arises from a dynamic, voltage-gated, negative feedback that can be recruited subthreshold, preventing the neuron from reaching spike threshold if the voltage does not rise fast enough...
2017: Frontiers in Computational Neuroscience
https://www.readbyqxmd.com/read/28210057/a-comparison-of-the-balance-and-gait-function-between-children-with-down-syndrome-and-typically-developing-children
#20
Hee-Kyoung Jung, EunJung Chung, Byoung-Hee Lee
[Purpose] The purpose of this study was to compare the balance and gait functions of children with Down syndrome and typically developing children according to age. [Subjects and Methods] The subjects were 16 children with Down syndrome and 20 children with typical development. The one leg standing test, Romberg's test (open eyes/closed eyes), sharpened Romberg's (open eyes/closed eyes), functional reaching test and GAITRite were used for this study in order to measure the children's balance and gait function...
January 2017: Journal of Physical Therapy Science
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