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https://www.readbyqxmd.com/read/28088842/unbiased-split-variable-selection-for-random-survival-forests-using-maximally-selected-rank-statistics
#1
Marvin N Wright, Theresa Dankowski, Andreas Ziegler
The most popular approach for analyzing survival data is the Cox regression model. The Cox model may, however, be misspecified, and its proportionality assumption may not always be fulfilled. An alternative approach for survival prediction is random forests for survival outcomes. The standard split criterion for random survival forests is the log-rank test statistic, which favors splitting variables with many possible split points. Conditional inference forests avoid this split variable selection bias. However, linear rank statistics are utilized by default in conditional inference forests to select the optimal splitting variable, which cannot detect non-linear effects in the independent variables...
January 15, 2017: Statistics in Medicine
https://www.readbyqxmd.com/read/28088797/automated-interpretation-of-pulmonary-function-tests-in-adults-with-respiratory-complaints
#2
Marko Topalovic, Stefan Laval, Jean-Marie Aerts, Thierry Troosters, Marc Decramer, Wim Janssens
BACKGROUND: The use of pulmonary function tests is primarily based on expert opinion and international guidelines. Current interpretation strategies are using predefined cutoffs for the description of a typical pattern. OBJECTIVES: We aimed to explore the predicted disease outcome based on the American Thoracic Society/European Respiratory Society (ATS/ERS) interpreting strategy. Subsequently, we investigated whether an unbiased machine learning framework integrating lung function with clinical variables may provide alternative decision trees resulting in a more accurate diagnosis...
January 12, 2017: Respiration; International Review of Thoracic Diseases
https://www.readbyqxmd.com/read/28088674/people-s-reasons-for-wanting-to-complete-probation-use-and-predictive-validity-in-an-e-health-intervention
#3
Stephanie A Spohr, Faye S Taxman, Scott T Walters
The criminal justice system tends to emphasize external contingencies (e.g., fees, jail time) to motivate offender compliance. However, people's reasons for desistance vary considerably. This study evaluated the acceptability, utility, and predictive validity of questions that ask about people's reasons for wanting to successfully complete probation. Substance-using probationers (N=113) participated in a web-based computer intervention that targeted substance use and treatment initiation. Questions around seven dimensions of reasons for completing probation were developed to provide tailored feedback during the web-based program...
January 6, 2017: Evaluation and Program Planning
https://www.readbyqxmd.com/read/28088577/analyze-the-beta-waves-of-electroencephalogram-signals-from-young-musicians-and-non-musicians-in-major-scale-working-memory-task
#4
Chien-Chang Hsu, Ching-Wen Cheng, Yi-Shiuan Chiu
Electroencephalograms can record wave variations in any brain activity. Beta waves are produced when an external stimulus induces logical thinking, computation, and reasoning during consciousness. This work uses the beta wave of major scale working memory N-back tasks to analyze the differences between young musicians and non-musicians. After the feature analysis uses signal filtering, Hilbert-Huang transformation, and feature extraction methods to identify differences, k-means clustering algorithm are used to group them into different clusters...
January 11, 2017: Neuroscience Letters
https://www.readbyqxmd.com/read/28088488/average-activity-but-not-variability-is-the-dominant-factor-in-the-representation-of-object-categories-in-the-brain
#5
Hamid Karimi-Rouzbahani, Nasour Bagheri, Reza Ebrahimpour
To categorize the perceived objects, brain utilizes a broad set of its resources and encoding strategies. Yet, it remains elusive how the category information is encoded in the brain. While many classical studies have sought the category information in the across-trials-averaged activity of neurons/neural populations, several recent studies have observed category information also in the within-trial correlated variability of activities between neural populations (i.e. dependent variability). Moreover, other studies have observed that independent variability of activity, which is the variability of the measured neural activity without any influence from correlated variability with other neurons/populations, could also be modulated for improved categorization...
January 11, 2017: Neuroscience
https://www.readbyqxmd.com/read/28088459/strain-development-in-bulk-filled-cavities-of-different-depths-characterized-using-a-non-destructive-acoustic-emission-approach
#6
Annelies Van Ende, Diogo Pedrollo Lise, Jan De Munck, Johan Vanhulst, Martine Wevers, Bart Van Meerbeek
OBJECTIVES: (1) To evaluate the effect of cavity depth and composite type on the interfacial debonding in bulk-filled cavities. (2) To correlate the theoretical shrinkage stress and the level of interfacial debonding determined by acoustic emission (AE). METHODS: 80 sound molars were divided in two groups to receive a Class-I cavity (3.5×3.5mm) with 2.5- or 4.0-mm depth. The cavities were restored with either a conventional paste-like (Filtek Z100, 3M ESPE), a conventional flowable (G-ænial Universal Flo, GC), a bulk-fill paste-like (Tetric EvoCeram Bulk Fill, Ivoclar Vivadent) or a bulk-fill flowable (SDR, Dentsply) composite (n=10)...
January 11, 2017: Dental Materials: Official Publication of the Academy of Dental Materials
https://www.readbyqxmd.com/read/28088316/individual-female-differences-in-chemoattractant-production-change-the-scale-of-sea-urchin-gamete-interactions
#7
Yasmeen H Hussain, Martin Sadilek, Shukri Salad, Richard K Zimmer, Jeffrey A Riffell
Sperm selection by females is an important process influencing fertilization and, particularly in broadcast-spawning organisms, often occurs before sperm reach the egg. Waterborne sperm chemoattractants are one mechanism by which eggs selectively influence conspecific sperm behavior, but it remains an open question whether the eggs from different females produce different amounts of sperm chemoattractant, and how that might influence sperm behavior. Here, we quantify the differences in attractant production between females of the sea urchin species Lytechinus pictus and use computational models and microfluidic sperm chemotaxis assays to determine how differences in chemoattractant production between females affects their ability to attract sperm...
January 11, 2017: Developmental Biology
https://www.readbyqxmd.com/read/28088305/inertial-particle-dynamics-in-large-artery-flows-implications-for-modeling-arterial-embolisms
#8
Debanjan Mukherjee, Shawn C Shadden
The complexity of inertial particle dynamics through swirling chaotic flow structures characteristic of pulsatile large-artery hemodynamics renders significant challenges in predictive understanding of transport of such particles. This is specifically crucial for arterial embolisms, where knowledge of embolus transport to major vascular beds helps in disease diagnosis and surgical planning. Using a computational framework built upon image-based CFD and discrete particle dynamics modeling, a multi-parameter sampling-based study was conducted on embolic particle dynamics and transport...
December 29, 2016: Journal of Biomechanics
https://www.readbyqxmd.com/read/28088261/parquetina-nigrescens-leaves-chemical-profile-and-influence-on-the-physical-and-biochemical-indices-of-sexual-activity-of-male-wistar-rats
#9
Omowumi Titilola Kayode, Musa Toyin Yakubu
OBJECTIVE: The leaves of Parquetina nigrescens have been claimed in folk medicine to be useful for managing sexual dysfunction, but there is inadequate scientific evidence for this claim. This investigation was conducted to assess the effects of aqueous leaf extract of Parquetina nigrescens (AEPN) in rats induced with sexual dysfunction. METHODS: Male rats were allocated into various groups after being induced into sexual dysfunction with paroxetine hydrochloride...
January 2017: Journal of Integrative Medicine
https://www.readbyqxmd.com/read/28088237/association-between-diabetes-mellitus-and-multi-drug-resistant-tuberculosis-a-protocol-for-a-systematic-review-and-meta-analysis
#10
Balewgizie Sileshi Tegegne, Tesfa Dejenie Habtewold, Melkamu Merid Mengesha, Johannes G M Burgerhof
INTRODUCTION: Multi-drug-resistant tuberculosis (MDR-TB) has emerged as a challenge to global tuberculosis (TB) control and remains a major public health concern in many countries. Diabetes mellitus (DM) is an increasingly recognized comorbidity that can both accelerate TB disease and complicate its treatment. The aim of this study is to summarize available evidence on the association of DM and MDR-TB among TB patients and to provide a pooled estimate of risks. METHODS: All studies published in English before October 2016 will be searched using comprehensive search strings through PubMed, EMBASE, Web of Science, and WHO Global Health Library databases which have reported the association of DM and MDR-TB in adults with TB (age > =15)...
January 14, 2017: Systematic Reviews
https://www.readbyqxmd.com/read/28088233/successful-recovery-from-a-subclavicular-ulcer-caused-by-lenvatinib-for-thyroid-cancer-a-case-report
#11
Morimasa Kitamura, Tomomasa Hayashi, Chiaki Suzuki, Shigeru Hirano, Ichiro Tateya, Yo Kishimoto, Koichi Omori
BACKGROUND: There are currently no effective therapeutic methods for locally recurrent, metastatic, or progressive radioactive iodine (RAI)-refractory differentiated thyroid cancer. However, multitargeted tyrosine kinase inhibitors (TKIs) such as lenvatinib or sorafenib have been approved for patients with RAI-refractory differentiated thyroid cancer as a second targeted therapy, and these agents can prolong patient survival. However, several cases have been reported that TKIs have caused fatal complications such as fistula formation or bleeding...
January 14, 2017: World Journal of Surgical Oncology
https://www.readbyqxmd.com/read/28088226/use-of-an-intraoperative-navigation-system-for-retrieving-a-broken-dental-instrument-in-the-mandible-a-case-report
#12
Shintaro Sukegawa, Takahiro Kanno, Akane Shibata, Kenichi Matsumoto, Yuka Sukegawa-Takahashi, Kyosuke Sakaida, Yoshihiko Furuki
BACKGROUND: A fracture of root canal instruments, with a fractured piece protruding beyond the apex, is a troublesome incident during an endodontic treatment. Locating and retrieving them represents a challenge to maxillofacial surgeons because it is difficult to access due to the proximity between the foreign body and vital structures. Although safe and accurate for surgery, radiographs and electromagnetic devices do not provide a precise three-dimensional position. In contrast, computer-aided navigation provides a correlation between preoperatively collected data and intraoperatively encountered anatomy...
January 15, 2017: Journal of Medical Case Reports
https://www.readbyqxmd.com/read/28088189/mars-improving-multiple-circular-sequence-alignment-using-refined-sequences
#13
Lorraine A K Ayad, Solon P Pissis
BACKGROUND: A fundamental assumption of all widely-used multiple sequence alignment techniques is that the left- and right-most positions of the input sequences are relevant to the alignment. However, the position where a sequence starts or ends can be totally arbitrary due to a number of reasons: arbitrariness in the linearisation (sequencing) of a circular molecular structure; or inconsistencies introduced into sequence databases due to different linearisation standards. These scenarios are relevant, for instance, in the process of multiple sequence alignment of mitochondrial DNA, viroid, viral or other genomes, which have a circular molecular structure...
January 14, 2017: BMC Genomics
https://www.readbyqxmd.com/read/28088164/photochemical-generation-of-h2ncnx-h2nncx-h2nc-nx-x-o-s-in-low-temperature-matrices
#14
Tamás Vörös, Győző György Lajgút, Gábor Magyarfalvi, György Tarczay
The [NH2, C, N, O] and the [NH2, C, N, S] molecular systems were investigated by computational and matrix-isolation spectroscopic methods. The determination of the equilibrium structures and relative energies by CCSD(T) method was followed by the computation of the harmonic and anharmonic vibrational wavenumbers, infrared intensities, relative Raman activities, and UV excitation energies. These computed data were used to assist the identification of products obtained by UV laser photolysis of 3,4-diaminofurazan and 3,4-diaminothiadiazole in low-temperature Ar and Kr matrices...
January 14, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/28088161/efficient-free-energy-calculations-by-combining-two-complementary-tempering-sampling-methods
#15
Liangxu Xie, Lin Shen, Zhe-Ning Chen, Mingjun Yang
Although energy barriers can be efficiently crossed in the reaction coordinate (RC) guided sampling, this type of method suffers from identification of the correct RCs or requirements of high dimensionality of the defined RCs for a given system. If only the approximate RCs with significant barriers are used in the simulations, hidden energy barriers with small to medium height would exist in other degrees of freedom (DOFs) relevant to the target process and consequently cause the problem of insufficient sampling...
January 14, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/28088150/optimal-orientation-of-an-asymmetric-top-molecule-with-terahertz-pulses
#16
L H Coudert
Terahertz pulses effects are investigated in an asymmetric top C2v molecule using numerical simulations. The average value of the direction cosine ΦZx is computed solving the time dependent Schrödinger equation for several types of pulses. The H2S molecule taken as a test case is first subject to two short terahertz pulses with a duration smaller than 5 ps, an identical maximum value of the electric field of 2 MV/cm, but a different shape. The thermal average ⟨⟨ΦZx⟩⟩ is calculated for several temperatures, and non-periodic time variations are found even for the lowest temperature...
January 14, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/28088140/ring-polymer-molecular-dynamics-studies-on-the-rate-coefficient-of-the-abstraction-channel-of-hydrogen-plus-ethane-propane-and-dimethyl-ether
#17
Qingyong Meng, Jun Chen
To accurately compute the rates of the abstraction channels of hydrogen plus ethane (Et), propane (Pr), and dimethyl ether (DME), ring-polymer molecular dynamics (RPMD) method is used in conjunction with the recently constructed local permutation invariant polynomial neural-networks potential energy surface of the parent H + CH4 system [Q. Meng et al., J. Chem. Phys. 144, 154312 (2016)]. For H + Et, one of the H atoms in CH4 of the parent system is replaced by a methyl group, while for the H + DME reaction, it is replaced by the methoxyl group...
January 14, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/28088080/a-computer-based-simulator-for-intravascular-photoacoustic-images
#18
Sun Zheng, Yuan Yuan, Han Duoduo
Intravascular photoacoustic (IVPA) is a newly developed catheter-based imaging technique for the diagnosis of arterial atherosclerosis. A framework of simulating IVPA transversal images from a cross-sectional vessel model with given optical and acoustic parameters was presented. The light illumination and transportation in multi-layered wall and atherosclerotic plaque tissues were modeled through Monte Carlo (MC) simulation. The generation and transmission of photoacoustic (PA) waves in the acoustically homogeneous medium were modeled through the PA wave equation, which is solved explicitly with a finite difference time domain (FDTD) algorithm in polar coordinates...
January 6, 2017: Computers in Biology and Medicine
https://www.readbyqxmd.com/read/28088023/a-novel-model-to-predict-gas-phase-hydroxyl-radical-oxidation-kinetics-of-polychlorinated-compounds
#19
Shuang Luo, Zongsu Wei, Richard Spinney, Zhihui Yang, Liyuan Chai, Ruiyang Xiao
In this study, a novel model based on aromatic meta-substituent grouping was presented to predict the second-order rate constants (k) for OH oxidation of PCBs in gas-phase. Since the oxidation kinetics are dependent on the chlorination degree and position, we hypothesized that it may be more accurate for k value prediction if we group PCB congeners based on substitution positions (i.e., ortho (o), meta (m), and para (p)). To test this hypothesis, we examined the correlation of polarizability (α), a quantum chemical based descriptor for k values, with an empirical Hammett constant (σ(+)) on each substitution position...
January 4, 2017: Chemosphere
https://www.readbyqxmd.com/read/28087955/water-as-neutral-oral-contrast-agent-in-abdominopelvic-ct-comparing-effectiveness-with-gastrografin-in-the-same-patient
#20
C H Lee, H Z Gu, B A Vellayappan, C H Tan
INTRODUCTION: Positive oral contrast is no longer deemed necessary for abdominopelvic computed tomography (CT) scans. Studies have shown water to be an equally effective oral contrast agent. However, to our knowledge no study has compared effectiveness between gastrografin and water in the same patient, which will provide a more objective evaluation of the two oral contrast agents. We aim to make a head-to-head comparison of water as neutral oral contrast (OC) against gastrografin as positive OC for abdominopelvic CT scans in the same patient...
December 2016: Medical Journal of Malaysia
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