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Liu, Yuanyuan, Xingmei Li, Fang Fang, Fayong Zhang, Jingying Chen i Zhizhong Zeng. "Visual Focus of Attention and Spontaneous Smile Recognition Based on Continuous Head Pose Estimation by Cascaded Multi-Task Learning". International Journal of Pattern Recognition and Artificial Intelligence 33, nr 07 (7.06.2019): 1940006. http://dx.doi.org/10.1142/s0218001419400068.
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Multi-person Visual focus of attention (M-VFOA) and spontaneous smile (SS) recognition are important for persons’ behavior understanding and analysis in class. Recently, promising results have been reported using special hardware in constrained environment. However, M-VFOA and SS remain challenging problems in natural and crowd classroom environment, e.g. various poses, occlusion, expressions, illumination and poor image quality, etc. In this study, a robust and un-invasive M-VFOA and SS recognition system has been developed based on continuous head pose estimation in the natural classroom. A novel cascaded multi-task Hough forest (CM-HF) combined with weighted Hough voting and multi-task learning is proposed for continuous head pose estimation, tip of the nose location and SS recognition, which improves accuracies of recognition and reduces the training time. Then, M-VFOA can be recognized based on estimated head poses, environmental cues and prior states in the natural classroom. Meanwhile, SS is classified using CM-HF with local cascaded mouth-eyes areas normalized by the estimated head poses. The method is rigorously evaluated for continuous head pose estimation, multi-person VFOA recognition, and SS recognition on some public available datasets and real-class video sequences. Experimental results show that our method reduces training time greatly and outperforms the state-of-the-art methods for both performance and robustness with an average accuracy of 83.5% on head pose estimation, 67.8% on M-VFOA recognition and 97.1% on SS recognition in challenging environments.
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Huang, Huajuan, Dao Tao, Xiuxi Wei i Yongquan Zhou. "Adaptive Image Enhancement Algorithm Based on Variable Step Fruit Fly Optimization Algorithm and Nonlinear Beta Transform". Biomimetics 8, nr 2 (22.05.2023): 212. http://dx.doi.org/10.3390/biomimetics8020212.
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Due to the traditional use of manual methods for the parameter adjustment of a nonlinear beta transform, which is inefficient and unstable, an adaptive image enhancement algorithm based on a variable step size fruit fly optimization algorithm and a nonlinear beta transform is proposed. Utilizing the intelligent optimization characteristics of the fruit fly algorithm, we automatically optimize the adjustment parameters of a nonlinear beta transform to achieve better image enhancement effects. Firstly, the dynamic step size mechanism is introduced into the fruit fly optimization algorithm (FOA) to obtain a variable step size fruit fly optimization algorithm (VFOA). Then, with the adjustment parameters of the nonlinear beta transform as the optimization object, and the gray variance of the image as the fitness function, an adaptive image enhancement algorithm (VFOA-Beta) is obtained by combining the improved fruit fly optimization algorithm with the nonlinear beta function. Finally, nine sets of photos were used to test the VFOA-Beta algorithm, while seven other algorithms were used for comparative experiments. The test results show that the VFOA-Beta algorithm can significantly enhance images and achieve better visual effects, which has a certain practical application value.
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Indi, Chirag S., Varun Pritham, Vasundhara Acharya i Krishna Prakasha. "Detection of Malpractice in E-exams by Head Pose and Gaze Estimation". International Journal of Emerging Technologies in Learning (iJET) 16, nr 08 (23.04.2021): 47. http://dx.doi.org/10.3991/ijet.v16i08.15995.
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Examination malpractice is a deliberate wrong doing contrary to official examina-tion rules designed to place a candidate at unfair advantage or disadvantage. The proposed system depicts a new use of technology to identify malpractice in E-Exams which is essential due to growth of online education. The current solu-tions for such a problem either require complete manual labor or have various vulnerabilities that can be exploited by an examinee. The proposed application en-compasses an end-to-end system that assists an examiner/evaluator in deciding whether a student passes an online exam without any probable attempts of mal-practice or cheating in e-exams with the help of visual aids. The system works by categorizing the student’s VFOA (visual focus of attention) data by capturing the head pose estimates and eye gaze estimates using state-of-the-art machine learn-ing techniques. The system only requires the student (test-taker) to have a func-tioning internet connection along with a webcam to transmit the feed. The exam-iner is alerted when the student wavers in his VFOA, from the screen greater than X, a predefined threshold of times. If this threshold X is crossed, the appli-cation will save the data of the person when his VFOA is off the screen and send it to the examiner to be manually checked and marked whether the action per-formed by the student was an attempt at malpractice or just momentary lapse in concentration. The system use a hybrid classifier approach where two different classifiers are used, one when gaze values are being read successfully (which may fail due to various reasons like transmission quality or glare from his specta-cles), the model falls back to the default classifier which only reads the head pose values to classify the attention metric, which is used to map the student’s VFOA to check the likelihood of malpractice. The model has achieved an accuracy of 96.04 percent in classifying the attention metric.
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Vosper, J. V. "Maximum oscillation frequencies andftsensitivities of two groups of single-VFOA active-RC oscillators". International Journal of Electronics 88, nr 7 (lipiec 2001): 759–72. http://dx.doi.org/10.1080/00207210110052874.
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Wentz, Laurel M., P. S. Webb i Kate Burks. "A Comprehensive Method of Assessing Body Composition Using Kinanthropometry in Human Performance Training". Journal of Special Operations Medicine 22, nr 2 (2022): 37. http://dx.doi.org/10.55460/vfoy-zeg6.
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Munro, Erin, i Nancy Kopell. "Subthreshold somatic voltage in neocortical pyramidal cells can control whether spikes propagate from the axonal plexus to axon terminals: a model study". Journal of Neurophysiology 107, nr 10 (15.05.2012): 2833–52. http://dx.doi.org/10.1152/jn.00709.2011.
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There is suggestive evidence that pyramidal cell axons in neocortex may be coupled by gap junctions into an “axonal plexus” capable of generating very fast oscillations (VFOs) with frequencies exceeding 80 Hz. It is not obvious, however, how a pyramidal cell in such a network could control its output when action potentials are free to propagate from the axons of other pyramidal cells into its own axon. We address this problem by means of simulations based on three-dimensional reconstructions of pyramidal cells from rat somatosensory cortex. We show that somatic depolarization enables propagation via gap junctions into the initial segment and main axon, while somatic hyperpolarization disables it. We show further that somatic voltage cannot effectively control action potential propagation through gap junctions on minor collaterals; action potentials may therefore propagate freely from such collaterals regardless of somatic voltage. In previous work, VFOs are all but abolished during the hyperpolarization phase of slow oscillations induced by anesthesia in vivo. This finding constrains the density of gap junctions on collaterals in our model and suggests that axonal sprouting due to cortical lesions may result in abnormally high gap junction density on collaterals, leading in turn to excessive VFO activity and hence to epilepsy via kindling.
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Andrade, Maureen S. "International Student Persistence: Integration or Cultural Integrity?" Journal of College Student Retention: Research, Theory & Practice 8, nr 1 (maj 2006): 57–81. http://dx.doi.org/10.2190/9my5-256h-vfva-8r8p.
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Bernstein, Zale P., Stephen P. Brooks, Asher Chanan-Khan, Sandra O. Gollnick, Mark J. Gilbert, Kena C. Miller i Thomas B. Tomasi. "Granulocyte-macrophage colony-stimulating factor (GM-CSF) restores allostimulatory function to accessory cells in patients with AIDS". HIV Clinical Trials 3, nr 3 (maj 2002): 219–24. http://dx.doi.org/10.1310/hp8b-nf27-vfwa-80yx.
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Buttigieg, Christopher P., i Gerd Sapiano. "A critical examination of the VFA framework – the VFA agent and beyond". Law and Financial Markets Review 14, nr 1 (12.07.2019): 48–58. http://dx.doi.org/10.1080/17521440.2019.1640421.
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Hanajima, Ritsuko, Robert Chen, Peter Ashby, Andres M. Lozano, William D. Hutchison, Karen D. Davis i Jonathan O. Dostrovsky. "Very Fast Oscillations Evoked by Median Nerve Stimulation in the Human Thalamus and Subthalamic Nucleus". Journal of Neurophysiology 92, nr 6 (grudzień 2004): 3171–82. http://dx.doi.org/10.1152/jn.00363.2004.
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Very fast oscillations (VFOs; 500–1,500 Hz) are associated with sensory-evoked potentials (SEPs), but their origin is unknown. To characterize the origins of VFOs, we studied 35 patients with deep brain stimulation (DBS) electrodes [15 with thalamic and 20 with the subthalamic nucleus (STN) electrodes]. We recorded median nerve stimulation–evoked SEPs from the thalamus and STN with microelectrodes during stereotactic surgery and from the contacts of the DBS electrodes postoperatively. We also examined the firing of individual neurons in thalamus in relation to the VFOs. In the thalamus, VFOs with frequencies around 1,000 Hz were superimposed on slow potentials. Both slow and fast SEP components showed phase reversals in the somatosensory thalamus [ventralis caudalis (Vc)]. Median nerve poststimulus time histograms showed that single thalamic neurons fired at preferred times at intervals between 0.8 to 1.2 ms that were synchronous with the VFOs, although the neurons fired only once or a few times per trial. In the STN, low-amplitude SEPs with VFOs were observed at a latency similar to the thalamic SEPs. The VFOs from STN probably represent volume conduction, possibly from the medial lemniscus. We conclude that the thalamic VFOs are generated within Vc and that they induce time-locked firing in a network of neurons.
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Gieseke, Sunna. "GKV feiert, vfa beklagt Strafmodell". Im Focus Onkologie 16, nr 6 (czerwiec 2013): 73. http://dx.doi.org/10.1007/s15015-013-0513-z.
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Traub, Roger D. "Fast Oscillations and Epilepsy". Epilepsy Currents 3, nr 3 (maj 2003): 77–79. http://dx.doi.org/10.1046/j.1535-7597.2003.03301.x.
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Very fast oscillations, 80 Hz and greater (designated here VFOs or “ripples”) have been observed in the hippocampus and neocortex, under a variety of conditions that are summarized briefly later. VFOs may be of relevance for normal brain function ( 1 – 4 ) and could also be of relevance in the initiation of focal epileptic seizures ( 5 , 6 ). To determine whether such relevance indeed exists, an understanding of the cellular mechanisms of VFOs is essential. For purposes of this commentary, I shall assume that all forms of VFOs are governed by a few common basic underlying principles. Future experimental data may show that assumption to be false, but for now, the assumption at least allows the formulation of straightforward hypotheses that could stimulate experiments.
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AYDIN, Mehmet Maruf, Emine DAĞISTAN i Zeliha COŞGUN. "Metabolik sendromda visseral ve subkutan yağ miktari ve hepatosteatozun bilgisayarli tomografi ile kantitatif değerlendirilmesi". Cukurova Medical Journal 47, nr 2 (30.06.2022): 481–88. http://dx.doi.org/10.17826/cumj.1037220.
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Purpose: We aimed to evaluate visceral and subcutaneous fat tissue and its association with hepatosteatosis on computed tomography (CT) scans to determine cut-off criteria for metabolic syndrome, measure abdominal obesity directly based on the visceral fat tissue area (VFTA) rather than indirectly based on waist circumference and obtain supportive findings by density measurements in addition to the VFTA measurements.Materials and Methods: The Hounsfield unit (HU) values, visceral, subcutaneous fat areas and HU values of 108 patients diagnosed with metabolic syndrome (MS) were determined according to the National Cholesterol Education Program Adult Treatment Panel III 2001 Criteria by retrospectively analyzing their abdominal CT images taken for various reasons. The relationships of the obtained values with each other and to MS were evaluated.Results: The strongest predictor of MS was VFTA, and 156.47 cm² was the most significant value with 74.1% sensitivity and 58.6% specificity. An HU value of -102.99 for visceral fat tissue density (VFTD) was found as the second most significant finding with 75% sensitivity and 57.6% specificity. The VFTA values of the patients with hepatosteatosis were higher, and increased VFTA values were associated with lower VFTD values.Conclusion: The most important supportive finding was the demonstration of the possibility of measuring abdominal obesity, which has an important place among criteria, directly by measuring VFTA, rather than indirectly based on waist circumference.
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Pratiwi, Putri Devi, i Dwi Kartikasari. "SUBSTITUSI FILLER DENGAN LIMBAH KARBIT TERHADAP CAMPURAN ASPAL PANAS HOT ROLLED SHEET – BASE COURSE (HRS-BC)". JMTS: Jurnal Mitra Teknik Sipil 4, nr 3 (4.08.2021): 519. http://dx.doi.org/10.24912/jmts.v0i0.11850.
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In hot asphalt mixtures, fillers are used, fillers are used as fillers between coarser aggregate particles, fillers also function to increase the binding energy (cohesion) of asphalt concrete. This study uses waste carbide as an alternative to filler in the HRS-BC asphalt mixture, this study aims to determine the results of the Marshall test, namely stability, VFWA, VMA, VIM, Flow, and MQ. This research uses experimental research method. Composition Variation The substitution of carbide waste used is 0%, 40%, 50%, and 60% of the weight of the filler. The results of the study obtained a mixture of 0% carbide waste with stability values of 871.13 kg, VFWA 75.18 kg, VMA 22.55 kg, VIM 7.01 kg, flow 3.80 mm, MQ 229.29. variation 40% stability value is 629.20 kg, VFWA 65.69 kg, VMA 25.09 kg, VIM 10.05 kg, flow 2.85 mm, MQ 226.52. variation of 50% stability value is 1011.76 kg, VFWA 72.75 kg, VMA 23.15 kg, VIM 7.72 kg, flow 2.50 mm, MQ 410.00. variation of 60% stability value is 1291.26 kg, VFWA 71.67 kg, VMA 23.41 kg, VIM 8.04 kg, flow 2.30 mm, MQ value 562.35. from the results of the study it can be concluded that the use of carbide waste at a variation of 60% is the most effective mixture according to the General Specifications Division 6: 2016 Asphalt Pavement.ABSTRAKDalam campuran aspal panas digunakan bahan pengisi filler,Filler digunakan sebagai bahan pengisi antar partikel agregat yang lebih kasar,filler juga berfungsi meningkatkan energi ikat (kohesi) pada aspal beton. penelitian ini menggunakan limbah karbit sebagai alternatif pengganti filler pada campuran aspal HRS-BC, penelitian ini bertujuan untuk mengetahui hasil pengujian marshall test yaitu stabilitas,VFWA,VMA,VIM,Flow,dan MQ. Penelitian ini menggunakan metode penelitian Eksperimen. Komposisi Variasi Substitusi limbah karbit yang digunakan sebesar 0%, 40%, 50%, dan 60% dari berat filler. hasil penelitian didapatkan campuran limbah karbit variasi 0% nilai stabilitas sebesar 871,13 kg, VFWA 75,18 kg, VMA 22,55 kg, VIM 7,01 kg, flow 3,80 mm, MQ 229,29. variasi 40% nilai stabilitas sebesar 629,20 kg, VFWA 65,69 kg, VMA 25,09 kg, VIM 10,05 kg, flow 2,85 mm, MQ 226,52. variasi 50% nilai stabilitas sebesar 1011,76 kg, VFWA 72,75 kg, VMA 23,15 kg, VIM 7,72 kg, flow 2,50 mm, MQ 410,00. variasi 60% nilai stabilitas sebesar 1291,26 kg, VFWA 71,67 kg, VMA 23,41 kg, VIM 8,04 kg, flow 2,30 mm, nilai MQ 562,35. dari hasil penelitian dapat disimpulkan bahwa penggunaan limbah karbit pada variasi 60% adalah campuran yang paling efektif sesuai Spesifikasi Spesifikasi Umum Divisi 6 : 2016 Perkerasan Aspal.
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Abe, Yuriko, Ryousuke Tonouchi, Mitsuhiko Hara, Tomoo Okada, Eric H. Jego, Tetsuya Taniguchi, Tsugumichi Koshinaga i Ichiro Morioka. "Visceral Fat Area Measured by Abdominal Bioelectrical Impedance Analysis in School-Aged Japanese Children". Journal of Clinical Medicine 11, nr 14 (17.07.2022): 4148. http://dx.doi.org/10.3390/jcm11144148.
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Abdominal bioelectrical impedance analysis (aBIA) has been in use to measure visceral fat area (VFA) in adults. Accurately measuring visceral fat using aBIA in children is challenging. Forty-six school-aged Japanese children aged 6–17 years (25 boys and 21 girls) were included in this study. All were measured, and their VFA obtained using aBIA (VFA-aBIA) and abdominal computed tomography (CT) (VFA-CT) were compared. VFA-aBIA was corrected using the Passing–Bablok method (corrected VFA-aBIA). The relationships between corrected VFA-aBIA and obesity-related clinical factors were analyzed, including non-alcoholic fatty liver disease (NAFLD) and serum leptin and adiponectin levels. Boys had higher VFA-CT than girls (p = 0.042), although no significant differences were found in their waist circumference, waist-to-height ratio, and body mass index. The corrected VFA-aBIA using y = 9.600 + 0.3825x (boys) and y = 7.607 + 0.3661x (girls) correlated with VFA-CT in both boys and girls. The corrected VFA-aBIA in patients with NAFLD was higher than that in those without NAFLD. Serum leptin and adiponectin levels were positively and negatively correlated with corrected VFA-aBIA, respectively. In conclusion, corrected VFA-aBIA was clearly correlated with VFA-CT and was related to NAFLD and serum leptin and adiponectin levels in school-aged Japanese children.
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Sukphun, Prawat, Sureewan Sittijunda i Alissara Reungsang. "Volatile Fatty Acid Production from Organic Waste with the Emphasis on Membrane-Based Recovery". Fermentation 7, nr 3 (19.08.2021): 159. http://dx.doi.org/10.3390/fermentation7030159.
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In recent years, interest in the biorefinery concept has emerged in the utilization of volatile fatty acids (VFAs) produced by acidogenic fermentation as precursors for various biotechnological processes. This has attracted substantial attention to VFA production from low-cost substrates such as organic waste and membrane based VFA recovery techniques to achieve cost-effective and environmentally friendly processes. However, there are few reviews which emphasize the acidogenic fermentation of organic waste into VFAs, and VFA recovery. Therefore, this article comprehensively summarizes VFA production, the factors affecting VFA production, and VFA recovery strategies using membrane-based techniques. Additionally, the outlook for future research on VFA production is discussed.
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Brennan, Caitlin A., Cindy R. DeLoney-Marino i Mark J. Mandel. "Chemoreceptor VfcA Mediates Amino Acid Chemotaxis in Vibrio fischeri". Applied and Environmental Microbiology 79, nr 6 (11.01.2013): 1889–96. http://dx.doi.org/10.1128/aem.03794-12.
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ABSTRACTFlagellar motility and chemotaxis byVibrio fischeriare important behaviors mediating the colonization of its mutualistic host, the Hawaiian bobtail squid. However, none of the 43 putative methyl-accepting chemotaxis proteins (MCPs) encoded in theV. fischerigenome has been previously characterized. Using both an available transposon mutant collection and directed mutagenesis, we isolated mutants for 19 of these genes, and screened them for altered chemotaxis to six previously identified chemoattractants. Only one mutant was defective in responding to any of the tested compounds; the disrupted gene was thus namedvfcA(VibriofischerichemoreceptorA; locus tag VF_0777). In soft-agar plates, mutants disrupted invfcAdid not exhibit the serine-sensing chemotactic ring, and the pattern of migration in the mutant was not affected by the addition of exogenous serine. Using a capillary chemotaxis assay, we showed that, unlike wild-typeV. fischeri, thevfcAmutant did not undergo chemotaxis toward serine and that expression ofvfcAon a plasmid in the mutant was sufficient to restore the behavior. In addition to serine, we demonstrated that alanine, cysteine, and threonine are strong attractants for wild-typeV. fischeriand that the attraction is also mediated by VfcA. This study thus provides the first insights into howV. fischeriintegrates information from one of its 43 MCPs to respond to environmental stimuli.
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Wauters, Christine, Mark Delaere i Jef Lysens. "Karel Goeyvaerts'Litanie Vfor harpsichord and tape or several harpsichords". Contemporary Music Review 19, nr 4 (styczeń 2000): 115–27. http://dx.doi.org/10.1080/07494460000640471.
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Ozato, Naoki, Shinnichiro Saitou, Tohru Yamaguchi, Mitsuhiro Katashima, Mina Misawa, Songee Jung, Kenta Mori i in. "Association between Visceral Fat and Brain Structural Changes or Cognitive Function". Brain Sciences 11, nr 8 (4.08.2021): 1036. http://dx.doi.org/10.3390/brainsci11081036.
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Visceral fat accumulation is an independent risk factor for cardiovascular disease and mortality. Visceral fat is a causal risk factor for hypertension and type 2 diabetes, which was reported as one of the risk factors for dementia. Visceral fat areas (VFA) might be clinically important to prevent dementia; however, the association between VFA and cognitive function in the elderly remains unknown. We aimed to evaluate the association between brain structural abnormalities using magnetic resonance imaging (MRI) and VFA, and the association between cognitive function and VFA, in the elderly. A total of 2364 healthy individuals were enrolled, and we excluded those diagnosed with dementia. Participants were divided into a high-VFA and a low-VFA group based on median VFA. The high-VFA group had significantly lower cognitive function than the low-VFA group (p = 0.025), after adjustment for related factors using a linear regression model. Regarding brain structure in MRI, VFA remained significantly associated with white matter lesions (odds ratio (OR), 1.90; 95% confidence interval (1.33–2.70); adjusted p < 0.001) and perivascular space (OR, 1.28; 95% confidence interval (1.02–1.61); adjusted p = 0.033). Further follow-up studies are needed, but reducing visceral fat might be important, not only to prevent cardiovascular disease but also to prevent dementia.
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Asano, Takeharu, Naoto Kubota, Norihiro Koizumi, Kazunori Itani, Tsuyoshi Mitake, Kazuhito Yuhashi, Hongen Liao i in. "Novel and Simple Ultrasonographic Methods for Estimating the Abdominal Visceral Fat Area". International Journal of Endocrinology 2017 (2017): 1–12. http://dx.doi.org/10.1155/2017/8796069.
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Objectives.To evaluate the abdominal visceral fat area (VFA), we developed novel ultrasonographic (US) methods for estimating.Methods.100 male volunteers were recruited, and their VFA was calculated by two novel US methods, the triangle method and the ellipse method. The VFA calculated by these methods was compared with the VFA calculated by CT.Results.Both the VFA calculated by the triangle method (r=0.766,p<0.001) and the ellipse method (r=0.781,p<0.001) showed a high correlation coefficient with the VFA calculated by CT. Also, the VFA calculated by our novel methods were significantly increased in subjects with one or more metabolic risk factors than in those without any risk factors. Furthermore, the correlation coefficients obtained using the two methods were enhanced by the addition of multiple regression analysis (with the triangle method,r=0.8586,p<0.001; with the ellipse method,r=0.8642,p<0.001).Conclusions.The VFA calculated by the triangle or ellipse method showed a high correlation coefficient with the VFA calculated by CT. These US methods are easy to use, they involve no radiation exposure, and the measurements can be conducted frequently. We hope that our simple methods would be widely adopted for the evaluation of VFA.
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Pei, Donghong, John A. Quirein, Bruce E. Cornish, Dan Quinn i Norman R. Warpinski. "Velocity calibration for microseismic monitoring: A very fast simulated annealing (VFSA) approach for joint-objective optimization". GEOPHYSICS 74, nr 6 (listopad 2009): WCB47—WCB55. http://dx.doi.org/10.1190/1.3238365.
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To accurately locate microearthquakes that are genetically related to hydraulic fracture stimulation, a thorough knowledge of the velocity structure between monitoring and fracturing treatment wells is essential. Very fast simulated annealing (VFSA) is implemented to invert for a flat-layered velocity model between wells using perforation or string-shot data. A two-point ray-tracing method is used to find the ray parameter [Formula: see text] for a ray traveling from a source to a receiver. The original traveltime-calculation formula is modified to account for the borehole source-receiver geometry. VFSA is used as a tool to optimize P- and S-wave velocities simultaneously. Unlike previous applications of VFSA, two improvements result from a new study: (1) both P- and S-wave arrival-time misfits are considered in a joint-objective function, and (2) P- and S-wave velocities are perturbed simultaneously during annealing. The inverted velocities follow the true values closely with a very small root-mean-square error, indicating the inverted model is close to the global minimum solution whose rms error should be zero for synthetic examples. Data noise contaminates inverted models, but not substantially in synthetic test results. A comparison of models inverted using VFSA and Occam’s inversion technique indicates that inverted models using VFSA are superior to those using Occam’s method in terms of velocity accuracy.
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Bannink, A., J. France i J. Dijkstra. "Improving the prediction of rumen volatile fatty acids in lactating dairy cows". Proceedings of the British Society of Animal Science 1996 (marzec 1996): 240. http://dx.doi.org/10.1017/s1752756200594320.
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Volatile fatty acids (VFA) constitute the largest fraction of metabolizable energy absorbed from the gastrointestinal tract of dairy cows. The molar proportion of individual VFA is important because individual VFA have a different fate in intermediary metabolism. However, rumen models predict the VFA molar proportions inaccurately from feed characteristics (Dijkstra, 1993). To investigate what model elements are responsible for this inaccuracy, modified descriptions of several elements were tested and sensitivity of VFA predictions was determined. This simulation study aims to identify model elements whose improved description can contribute to a more accurate prediction of VFA molar proportions.
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Bannink, A., J. France i J. Dijkstra. "Improving the prediction of rumen volatile fatty acids in lactating dairy cows". Proceedings of the British Society of Animal Science 1996 (marzec 1996): 240. http://dx.doi.org/10.1017/s0308229600032037.
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Volatile fatty acids (VFA) constitute the largest fraction of metabolizable energy absorbed from the gastrointestinal tract of dairy cows. The molar proportion of individual VFA is important because individual VFA have a different fate in intermediary metabolism. However, rumen models predict the VFA molar proportions inaccurately from feed characteristics (Dijkstra, 1993). To investigate what model elements are responsible for this inaccuracy, modified descriptions of several elements were tested and sensitivity of VFA predictions was determined. This simulation study aims to identify model elements whose improved description can contribute to a more accurate prediction of VFA molar proportions.
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Liu, Yongke, Dong Guo, Zhaojian Niu, Yuliang Wang, Guanghua Fu, Yanbing Zhou, Qingkai Xue, Xinliang Jin i Zhiqi Gong. "Prediction of the Risk of Laparoscopy-Assisted Gastrectomy by Comparing Visceral Fat Area and Body Mass Index". Gastroenterology Research and Practice 2018 (13.09.2018): 1–7. http://dx.doi.org/10.1155/2018/1359626.
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Propose. The purpose of this study was to compare the accuracy of visceral fat area (VFA) and body mass index (BMI) in predicting the risk of laparoscopic-assisted gastrectomy. Methods. Clinicopathological and imaging data of 133 patients who underwent laparoscopy-assisted gastrectomy were recorded, including 17 cases of conversion to open surgery. The remaining 116 patients were retrospectively analyzed after we excluded 17 patients who had been transferred to laparotomy. The patients were divided into two groups according to BMI (≤25 kg/m2: BMI-L group; >25 kg/m2: BMI-H group) and VFA (≤100 cm2: VFA-L group; >100 cm2: VFA-H group). Clinical outcomes were compared between the BMI and VFA subgroups. Results. There were no differences in intraoperative blood loss and the number of harvested lymph nodes between low and high patients defined by BMI and VFA (p>0.050). However, in the comparison of patients who underwent laparoscopic resection only, it was found that the operation time and intraoperative blood loss of the VFA-H group were more than those of the VFA-L group (p<0.050). Compared to the VFA-L group, the VFA-H group had later first exhaust time (p=0.018), more complications (p<0.001), and longer hospital stays (p=0.049). However, no similar conclusion was obtained in the BMI group (p>0.050). Conclusion. This study demonstrates that VFA better evaluates the difficulty of laparoscopy-assisted gastrectomy and the risk of postoperative complications than BMI.
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Yu, Zhiyong, Rongxin Tang, Kai Yuan, Hai Lin, Xin Qian, Xiaohua Deng i Shiyun Liu. "Investigation of Parameter Effects on Virtual-Spring-Force Algorithm for Wireless-Sensor-Network Applications". Sensors 19, nr 14 (12.07.2019): 3082. http://dx.doi.org/10.3390/s19143082.
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Virtual-force algorithms (VFAs) have been widely studied for accurate node deployment in wireless-sensor-network (WSN) applications. Their main purpose is to achieve the maximum coverage area with the minimum number of sensor nodes in the target area. Recently, we reported a new VFA based on virtual spring force (VFA-SF) and discussed in detail the corresponding efficiency via statistical analysis. The optimized strategy by adding an external central force (VFA-SF-OPT) was presented, which effectively eliminates the coverage hole or twisted structure in the final network distribution. In this paper, the parameter effects on VFA-SF and the VFA-SF-OPT were further investigated: (1) Node velocity dramatically affects the convergence rate of the node-deployment process. (2) A suitable external central force improves equilibrium distance and reduces energy consumption. (3) The effects of VFA-SF and VFA-SF-OPT for different types of obstacles are discussed. Generally, by choosing suitable parameters, both VFA-SF and VFA-SF-OPT can effectively improve node deployment and energy consumption for the whole sensor network. The results give important insight in parameter selection and information fusion in the application of a large-scale WSN.
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Giduthuri, Anthony T., i Birgitte K. Ahring. "Current Status and Prospects of Valorizing Organic Waste via Arrested Anaerobic Digestion: Production and Separation of Volatile Fatty Acids". Fermentation 9, nr 1 (23.12.2022): 13. http://dx.doi.org/10.3390/fermentation9010013.
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Volatile fatty acids (VFA) are intermediary degradation products during anaerobic digestion (AD) that are subsequently converted to methanogenic substrates, such as hydrogen (H2), carbon dioxide (CO2), and acetic acid (CH3COOH). The final step of AD is the conversion of these methanogenic substrates into biogas, a mixture of methane (CH4) and CO2. In arrested AD (AAD), the methanogenic step is suppressed to inhibit VFA conversion to biogas, making VFA the main product of AAD, with CO2 and H2. VFA recovered from the AAD fermentation can be further converted to sustainable biofuels and bioproducts. Although this concept is known, commercialization of the AAD concept has been hindered by low VFA titers and productivity and lack of cost-effective separation methods for recovering VFA. This article reviews the different techniques used to rewire AD to AAD and the current state of the art of VFA production with AAD, emphasizing recent developments made for increasing the production and separation of VFA from complex organic materials. Finally, this paper discusses VFA production by AAD could play a pivotal role in producing sustainable jet fuels from agricultural biomass and wet organic waste materials.
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Kadowaki, Satoshi, Yoshifumi Tamura, Yuki Someya, Kageumi Takeno, Hideyoshi Kaga, Daisuke Sugimoto, Saori Kakehi i in. "Fatty Liver Has Stronger Association With Insulin Resistance Than Visceral Fat Accumulation in Nonobese Japanese Men". Journal of the Endocrine Society 3, nr 7 (20.05.2019): 1409–16. http://dx.doi.org/10.1210/js.2019-00052.
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Abstract Context Asians have a high prevalence of insulin resistance, even in the nonobese state. Whereas both visceral fat accumulation (VFA) and fatty liver (FL) have been shown to be associated with insulin resistance, it is still unclear which is a better marker to predict insulin resistance in nonobese Asians. Objective The aim of this study was to investigate the relation between VFA or FL and insulin resistance in nondiabetic nonobese Japanese men who do not have diabetes. Design and Participants We studied 87 nonobese (body mass index <25 kg/m2) Japanese men without diabetes. Using a two-step hyperinsulinemic euglycemic clamp, we evaluated insulin sensitivity in adipose tissue, muscle, and liver. Intrahepatic lipid and abdominal visceral fat area were measured by 1H-magnetic resonance spectroscopy and MRI, respectively. Subjects were divided into four groups based on the presence or absence of VFA (visceral fat area ≥100 cm2) and FL (intrahepatic lipid ≥ 5%): control (non-VFA, non-FL; n = 54), VFA only (n = 18), FL only (n = 7), and VFA plus FL (n = 8). Results Subjects in the FL only and VFA plus FL groups had insulin resistance in adipose tissue and muscle, as well as relatively lower hepatic insulin sensitivity. The specific insulin sensitivities in these organs were comparable in the VFA only and control groups. Conclusions In nonobese Japanese men without diabetes, subjects with FL only or VFA plus FL but not VFA only had insulin resistance, suggesting that FL may be a more useful clinical marker than VFA to predict insulin resistance in nonobese Japanese men without diabetes.
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Almazroi, Abdulwahab Ali, Eman A. Aldhahri, Mahmood A. Al-Shareeda i Selvakumar Manickam. "ECA-VFog: An efficient certificateless authentication scheme for 5G-assisted vehicular fog computing". PLOS ONE 18, nr 6 (23.06.2023): e0287291. http://dx.doi.org/10.1371/journal.pone.0287291.
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Fifth-generation (5G)-enabled vehicular fog computing technologies have always been at the forefront of innovation because they support smart transport like the sharing of traffic data and cooperative processing in the urban fabric. Nevertheless, the most important factors limiting progress are concerns over message protection and safety. To cope with these challenges, several scholars have proposed certificateless authentication schemes with pseudonyms and traceability. These schemes avoid complicated management of certificate and escrow of key in the public key infrastructure-based approaches in the identity-based approaches, respectively. Nevertheless, problems such as high communication costs, security holes, and computational complexity still exist. Therefore, this paper proposes an efficient certificateless authentication called the ECA-VFog scheme for fog computing with 5G-assisted vehicular systems. The proposed ECA-VFog scheme applied efficient operations based on elliptic curve cryptography that is supported by a fog server through a 5G-base station. This work conducts a safety analysis of the security designs to analysis the viability and value of the proposed ECA-VFog scheme. In the performance ovulation section, the computation costs for signing and verification process are 2.3539 ms and 1.5752 ms, respectively. While, the communication costs and energy consumption overhead of the ECA-VFog are 124 bytes and 25.610432 mJ, respectively. Moreover, comparing the ECA-VFog scheme to other existing schemes, the performance estimation reveals that it is more cost-effective with regard to computation cost, communication cost, and energy consumption.
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Bergman, E. N. "Energy contributions of volatile fatty acids from the gastrointestinal tract in various species". Physiological Reviews 70, nr 2 (1.04.1990): 567–90. http://dx.doi.org/10.1152/physrev.1990.70.2.567.
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The VFA, also known as short-chain fatty acids, are produced in the gastrointestinal tract by microbial fermentation of carbohydrates and endogenous substrates, such as mucus. This can be of great advantage to the animal, since no digestive enzymes exist for breaking down cellulose or other complex carbohydrates. The VFA are produced in the largest amounts in herbivorous animal species and especially in the forestomach of ruminants. The VFA, however, also are produced in the lower digestive tract of humans and all animal species, and intestinal fermentation resembles that occurring in the rumen. The principal VFA in either the rumen or large intestine are acetate, propionate, and butyrate and are produced in a ratio varying from approximately 75:15:10 to 40:40:20. Absorption of VFA at their site of production is rapid, and large quantities are metabolized by the ruminal or large intestinal epithelium before reaching the portal blood. Most of the butyrate is converted to ketone bodies or CO2 by the epithelial cells, and nearly all of the remainder is removed by the liver. Propionate is similarly removed by the liver but is largely converted to glucose. Although species differences exist, acetate is used principally by peripheral tissues, especially fat and muscle. Considerable energy is obtained from VFA in herbivorous species, and far more research has been conducted on ruminants than on other species. Significant VFA, however, are now known to be produced in omnivorous species, such as pigs and humans. Current estimates are that VFA contribute approximately 70% to the caloric requirements of ruminants, such as sheep and cattle, approximately 10% for humans, and approximately 20-30% for several other omnivorous or herbivorous animals. The amount of fiber in the diet undoubtedly affects the amount of VFA produced, and thus the contribution of VFA to the energy needs of the body could become considerably greater as the dietary fiber increases. Pigs and some species of monkey most closely resemble humans, and current research should be directed toward examining the fermentation processes and VFA metabolism in those species. In addition to the energetic or nutritional contributions of VFA to the body, the VFA may indirectly influence cholesterol synthesis and even help regulate insulin or glucagon secretion. In addition, VFA production and absorption have a very significant effect on epithelial cell growth, blood flow, and the normal secretory and absorptive functions of the large intestine, cecum, and rumen. The absorption of VFA and sodium, for example, seem to be interdependent, and release of bicarbonate usually occurs during VFA absorption.(ABSTRACT TRUNCATED AT 400 WORDS)
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Er, Leay Kiaw, Meng-Chun Lin, Yao-Chou Tsai, Jong-Kai Hsiao, Chung-Yi Yang, Chin-Chen Chang, Kang-Yung Peng, Jeff S. Chueh i Vin-Cent Wu. "Association of visceral adiposity and clinical outcome among patients with aldosterone producing adenoma". BMJ Open Diabetes Research & Care 8, nr 1 (lipiec 2020): e001153. http://dx.doi.org/10.1136/bmjdrc-2019-001153.
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IntroductionPrimary aldosteronism (PA) is a common form of secondary hypertension that has significant cardiovascular events and increased prevalence of metabolic syndrome and diabetics. Although plasma aldosterone concentration is positively correlated with visceral fat area (VFA) in non-PA individuals, the role of visceral adiposity associated with clinical success after surgery is not known.Research design and methodsWe analyzed patients who underwent adrenalectomy for aldosterone-producing adenoma (APA) at the Taiwan PA Investigator group. VFA was calculated from the abdominal CT scan at APA diagnosis, and all patients received adrenalectomy.ResultsThe study involved 100 consecutive patients with APA (42 males; mean age 49.3 years) matched with 41 essential hypertension (EH) patients. Patients with APA had smaller VFA (p=0.010) than their EH counterparts. Multiple linear regression analysis revealed that the duration of hypertension (p=0.007), but not plasma aldosterone, was negatively correlated with VFA in patients with APA. Logistic regression analysis showed that log VFA (OR=0.065, p<0.001) and duration of hypertension before PA diagnosis (OR=0.919, p=0.011) can predict complete clinical success after adrenalectomy. Multifactor-adjusted generalized additive model demonstrated that log VFA <9.2 was associated with complete cure of hypertension. Furthermore, VFA was increased at 6 months after adrenalectomy (p=0.045).ConclusionsPatients with APA had smaller VFA than their EH counterparts, and VFA increased after adrenalectomy. Clinical complete cure of hypertension after surgery was associated with smaller VFA and shorter duration of hypertension at PA diagnosis, suggesting a potential interplay of visceral adiposity and aldosterone of the patients with APA.
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Kinoshita, Keita, Naoki Ozato, Tohru Yamaguchi, Kenta Mori, Yoshihisa Katsuragi, Takuji Yasukawa, Koichi Murashita, Shigeyuki Nakaji i Kazushige Ihara. "Association between visceral fat and influenza infection in Japanese adults: A population-based cross-sectional study". PLOS ONE 17, nr 7 (26.07.2022): e0272059. http://dx.doi.org/10.1371/journal.pone.0272059.
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Background Several studies have reported that obesity is associated with influenza infection; however, the role of visceral fat remains unclear. The aim of this study was to investigate the association between visceral fat and influenza infection in community-dwelling Japanese adults. Methods A cross-sectional study was performed using data from an annual community-based health check-up conducted from May to June in 2019. In total, 1,040 Japanese adults aged 20–89 years were enrolled in this study. Influenza infection status was determined by participants’ responses to a self-administered questionnaire. The visceral fat area (VFA) was measured using a bioimpedance-type visceral fat meter. Participants were classified into four groups using the following cut-off points: VFA < 100 cm2 was set as the reference category according to the Japanese criteria, 100 ≤ VFA < 150 cm2, 150 ≤ VFA < 200 cm2, and 200 cm2 ≤ VFA. Logistic regression models were used to assess the association between VFA and influenza infection. Results In total, 119 participants had influenza infections in the past year. In the multivariate adjusted model, a higher VFA was significantly associated with increased influenza infection; the adjusted odds ratio for 200 cm2 ≤ VFA was 5.03 [95% confidence interval (CI): 1.07–23.6], that for 150 ≤ VFA < 200 cm2 was 1.97 (95% CI: 0.71–5.45), and that for 100 ≤ VFA < 150 cm2 was 1.62 (95% CI: 0.84–3.12), compared with that for VFA < 100 cm2 (p for trend = 0.049). These findings were confirmed in the same cohort the following year. Conclusions Our results suggest that visceral fat accumulation is associated with influenza infection. Large-scale prospective studies using diagnostic information for influenza infection are required to confirm this association.
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Deng, Ke, Xin Zhang, Ying Liu, Gai Ping Cheng, Hong Ping Zhang, Ting Wang, Lei Wang, Wei Min Li, Gang Wang i Lisa Wood. "Visceral obesity is associated with clinical and inflammatory features of asthma: A prospective cohort study". Allergy and Asthma Proceedings 41, nr 5 (1.09.2020): 348–56. http://dx.doi.org/10.2500/aap.2020.41.200054.
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Background: Although studies have consistently linked obesity and asthma, the potential influence of visceral obesity on asthma has not been well investigated. Objective: To study the associations of visceral fat area (VFA) and clinical and inflammatory features of asthma and to further explore the effects of VFA on the future risk of asthma exacerbation. Methods: A 12-month prospective cohort study based on the Australasian Severe Asthma Network was designed to observe patients with stable asthma grouped by the median value of VFA. The clinical and inflammatory features of asthma were compared between the low VFA (VFAlow) and high VFA (VFAhigh) groups. Relationships between VFA and clinical and inflammatory features of asthma were analyzed by using correlation analysis. Univariate and multivariable negative binomial regression analyses were performed to investigate the association of VFA with exacerbations within a 12-month follow-up period. Results: The patients in the VFAhigh group were older and had a longer asthma duration. Interleukin (IL) 6 and IL-8 in sputum were higher, whereas fractional exhaled nitric oxide (FeNO) and blood eosinophils were lower in the VFAhigh group. Gender-differentiated correlations of VFA with clinical and inflammatory variables were observed in age, FeNO, immunoglobulin E, blood total white cells and neutrophils, and sputum IL-1β and IL-8. Furthermore, compared with the VFAlow group, the VFAhigh group was at significantly increased risk of moderate-to-severe exacerbations (adjusted incidence rate ratio [IRR] 1.55 [95% confidence interval {CI}, 1.06‐2.28; p = 0.025), severe exacerbations (adjusted IRR 2.25 [95% CI, 1.26‐4.04]; p = 0.007), and emergency visits (adjusted IRR 5.33 [95% CI, 1.78‐17.16]; p = 0.003). Conclusion: The level of VFA was associated with specific clinical and inflammatory characteristics of asthma. Furthermore, VFA, as an independent risk factor, was associated with an increased risk of exacerbations. It indicated that VFA would provide more potential clinical implications for asthma management.
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Shiltagh, Nadia Adnan, i Maab Alaa Hussein. "Data Aggregation in Wireless Sensor Networks Using Modified Voronoi Fuzzy Clustering Algorithm". Journal of Engineering 21, nr 4 (1.12.2015): 42–60. http://dx.doi.org/10.31026/j.eng.2015.04.03.
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Data centric techniques, like data aggregation via modified algorithm based on fuzzy clustering algorithm with voronoi diagram which is called modified Voronoi Fuzzy Clustering Algorithm (VFCA) is presented in this paper. In the modified algorithm, the sensed area divided into number of voronoi cells by applying voronoi diagram, these cells are clustered by a fuzzy C-means method (FCM) to reduce the transmission distance. Then an appropriate cluster head (CH) for each cluster is elected. Three parameters are used for this election process, the energy, distance between CH and its neighbor sensors and packet loss values. Furthermore, data aggregation is employed in each CH to reduce the amount of data transmission which lead to extend the network lifetime and reduce the traffic that may be accrue in the buffer of sink node. Each cluster head collected data from its members and forwards it to the sink node. A comparative study between modified VFCA and LEACH protocol is implemented in this paper and shows that the modified VFCA is more efficient than LEACH protocol in terms of network lifetime and average energy consumption. Another comparative study between modified VFCA and K-Means clustering algorithm is presented and shows that the modified VFCA is more efficient than K-Means clustering algorithm in terms of packets transmitted to sink node, buffer utilization, packet loss values and running time. A simulation process is developed and tested using Matlab R2010a program in a computer having the following properties: windows 7 (32-bit operating system), core i7, RAM 4GB, hard 1TB.
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Hayashi, Yoshinori, Hirohide Yokokawa, Hiroshi Fukuda, Mizue Saita, Taiju Miyagami, Yuichi Takahashi, Teruhiko Hisaoka i Toshio Naito. "Association between Visceral or Subcutaneous Fat Accumulation and B-Type Natriuretic Peptide among Japanese Subjects: A Cross-Sectional Study". Journal of Clinical Medicine 10, nr 6 (23.03.2021): 1315. http://dx.doi.org/10.3390/jcm10061315.
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Background: Some previous studies have shown reduced levels of plasma B-type natriuretic peptide (BNP) in individuals with obesity. We aimed to estimate the relationship between BNP and abdominal fat distribution, adjusted for confounding factors. Methods: This cross-sectional study included 1806 Japanese individuals (981 men and 825 women) who underwent a medical health check-up. Analyzed data included age, sex, visceral fat area (VFA), and subcutaneous fat area (SFA) as obtained from computed tomography, blood pressure, and blood test results including BNP. Multiple linear regression analysis was used to examine the association between BNP, VFA, and SFA after adjusting for age, sex, comorbidities, and body mass index. Results: In the models analyzed separately for VFA and SFA, BNP correlated independently with VFA in multiple linear regression analysis among all subjects and in both men and women, while SFA correlated inversely with BNP in all subjects and women but not in men. In the model that included both VFA and SFA, BNP correlated independently with VFA, but SFA and BNP were not correlated in any models. Conclusion: Higher VFA showed an independent, significant association with lower BNP. In addition, the inverse correlation with BNP was stronger for VFA than for SFA.
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Li, Cheng, Bingxian Kang, Ting Zhang, Hongru Gu, Qingqing Man, Pengkun Song, Zhen Liu i in. "High Visceral Fat Area Attenuated the Negative Association between High Body Mass Index and Sarcopenia in Community-Dwelling Older Chinese People". Healthcare 8, nr 4 (12.11.2020): 479. http://dx.doi.org/10.3390/healthcare8040479.
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The association between obesity and sarcopenia remains controversial. The present study was conducted to explore the associations among body mass index (BMI), visceral fat area (VFA), and sarcopenia in older people and analyze their potential mechanisms. This cross-sectional study included 861 community-dwelling older Chinese people from three regions of China. BMI, VFA, muscle mass, muscle strength, physical performance, body composition, and metabolic markers were measured. Muscle mass and muscle strength were positively correlated with BMI, but were negatively correlated with VFA. Simple overweight/obesity was negatively associated with sarcopenia (OR = 0.07, 95% CI = 0.03~0.18), and the OR value was lower than combined obesity (OR = 0.16, 95% CI = 0.09~0.28). Fat free mass and total body protein were positively associated with high BMI but negatively associated with high VFA. Furthermore, high VFA was adversely associated with some metabolic risk factors of sarcopenia. Combination of BMI and VFA increased diagnostic efficiency of low muscle mass and sarcopenia. In conclusion, high BMI was negatively associated with sarcopenia, while high VFA attenuated the negative association between high BMI and sarcopenia. The opposite association may partially be attributed to their different associations with body composition and metabolic risk factors of sarcopenia. Therefore, bedsides BMI, VFA and its interaction with BMI should be considered in sarcopenia prevention.
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Ozato, Saito, Yamaguchi, Katashima, Tokuda, Sawada, Katsuragi, Imoto, Ihara i Nakaji. "Association between Nutrients and Visceral Fat in Healthy Japanese Adults: A 2-Year Longitudinal Study Brief Title: Micronutrients Associated with Visceral Fat Accumulation". Nutrients 11, nr 11 (7.11.2019): 2698. http://dx.doi.org/10.3390/nu11112698.
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: High visceral fat area (VFA) is a stronger predictor of cardiovascular disease and overall mortality than body mass index or waist circumference. VFA may be decreased by proper dietary habits. Although previous epidemiologic studies demonstrated an association between nutritional components or foodstuffs and VFA, only the associations of a few nutrients, such as dietary fiber and calcium, are reported. We performed a comprehensive 2-year longitudinal study in more than 624 healthy people and analyzed 33 micronutrients to investigate nutrients that contribute to changes in visceral fat. Our analyses revealed that “macronutrients” and “micronutrients” were “mutual confounders”. Therefore, when evaluating the association between VFA and micronutrients, associations were adjusted by macronutrients. The ingestion of 7 nutrients: soluble dietary fiber, manganese, potassium, magnesium, vitamin K, folic acid, and pantothenic acid, which are abundant components in vegetable diets, was significantly inversely correlated with a change in VFA. Additionally, a change in the ingestion of one nutrient, monounsaturated fat, was significantly positively correlated with a change in VFA. These associations were independent of body mass index and waist circumference. Thus, a predominantly vegetable diet may decrease VFA. In addition, adjusting the intake of macronutrients might help to clarify the association of micronutrients with VFA.
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Ezebuiro, N. C. "Derivation of volatile fatty acids concentration-independent optimum trace elements configuration and elucidation of optimization kinetics of biomethanization processes". Nigerian Journal of Biotechnology 38, nr 1 (28.07.2021): 194–208. http://dx.doi.org/10.4314/njb.v38i1.22.
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Trace elements (TEs) requirements for improved volatile fatty acids (VFA) degradation during biomethanization depend on VFA concentration of a reactor and the temperature of the process. While temperature remains relatively constant, VFA concentrations change in the course of biomethanization and this implies that for efficient VFA degradation, different trace elements configurations (TEC) should be supplemented. While this is the most efficient approach, it is impractical and constitutes a challenge for the effective use of TEs in the optimization of biomethanization processes. To alleviate this challenge, we modelled the biomethanization efficiency of various VFA concentration-dependent (VCD) TEs configuration as scenarios and derived a TEs configuration that produced optimum biomethanization across a wider range of VFA concentrations. The study was carried out at 37oC using different concentrations of fixed VFA composition and TEs configurations as scenarios. Response surface model and desirability function were used to determine and compare the biomethanization efficiency of the scenarios, and to derive a VFA concentration-independent (VCI) TEs configuration. Michaelis-Menten kinetics for two parameters was used to ascertain that the mechanism by which TEs supplementation enhanced mesophilic biomethanization was through an increase in maximum reaction rate (MRR). However, the enhancement was accompanied by an insignificant decline in inverse affinity (IA).
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Pandrangi, Vivek, Daniel Mandel, Norman Gellada, Cindy Kallman, Karen Zaghiyan i Phillip Fleshner. "Abdominal Visceral Fat Area and Chronic Pouchitis after Ileal Pouch-Anal Anastomosis". American Surgeon 83, nr 10 (październik 2017): 1029–32. http://dx.doi.org/10.1177/000313481708301003.
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Chronic pouchitis (CP) after ileal pouch-anal anastomosis is a significant clinical problem. Adipose tissues produce antiinflammatory cytokines and chemokines. We evaluated the association between abdominal visceral fat area (VFA) and CP. Patients with a preoperative CT evaluation were included. The diagnosis of CP was confirmed in all cases by endoscopy with afferent ileal limb intubation. Patients were allocated into groups of high VFA and low VFA. The study cohort of 52 patients had a median body mass index of 22 (range, 14–32). Indications for surgery were medically refractory disease in 46 (88%) patients and cancer/dysplasia in six (12%) patients. Median VFA was 27.1 (range, 1–144). Six (12%) patients developed CP. Low VFA patients were significantly younger (29 vs 45 years; P < 0.0001), had lower body mass index (20.4 vs 24.7; P < 0.0001), had surgery more commonly for medically refractory disease than for cancer or dysplasia (100 vs 77%; P = 0.02), and had a higher incidence of CP than high VFA patients (23 vs 0%; P = 0.02). Multiple linear regression analysis demonstrated that only low VFA was associated with CP (P = 0.009). An association is present between VFA and CP after ileal pouch-anal anastomosis, implicating adipocytes in the pathogenesis of inflammatory bowel disease.
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Yesil, H., A. E. Tugtas, A. Bayrakdar i B. Calli. "Anaerobic fermentation of organic solid wastes: volatile fatty acid production and separation". Water Science and Technology 69, nr 10 (12.03.2014): 2132–38. http://dx.doi.org/10.2166/wst.2014.132.
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Anaerobic fermentation of organic municipal solid waste was investigated using a leach-bed reactor (LBR) to assess the volatile fatty acid (VFA) production efficiency. The leachate recycle rate in the LBR affected the VFA composition of the leachate. A six-fold increase in the recycle rate resulted in an increase of the acetic acid fraction of leachate from 24.7 to 43.0%. The separation of VFAs via leachate replacement resulted in higher total VFA production. VFA separation from synthetic VFA mix and leachate of a fermented organic waste was assessed via a counter-current flow polytetrafluoroethylene (PTFE) membrane contactor. Acetic and propionic acid permeation fluxes of 13.12 and 14.21 g/m2.h were obtained at low feed pH values when a synthetic VFA mix was used as a feed solution. The highest selectivity was obtained for caproic acid compared to that of other VFAs when synthetic VFA mix or leachate was used as a feed solution. High pH values and the presence of suspended solids in the leachate adversely affected the permeation rate.
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Jonker, Arjan, Sharon M. Hickey, John C. McEwan, Suzanne J. Rowe, Peter H. Janssen, Sarah MacLean, Edgar Sandoval i in. "Genetic parameters of plasma and ruminal volatile fatty acids in sheep fed alfalfa pellets and genetic correlations with enteric methane emissions1". Journal of Animal Science 97, nr 7 (19.06.2019): 2711–24. http://dx.doi.org/10.1093/jas/skz162.
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Abstract Animal-to-animal variation in methane (CH4) emissions determined in respiration chambers has a genetic basis, but rapid phenotyping methods that can be applied on-farm are required to enable increased genetic progress by the farming industry. Fermentation of carbohydrates in the rumen results in the formation of VFA with hydrogen (H2) as a byproduct that is used for CH4 formation. Generally, fermentation pathways leading to acetate are associated with the most H2 production, less H2 formation is associated with butyrate production, and propionate and valerate production are associated with reduced H2 production. Therefore, VFA may constitute a potential correlated proxy for CH4 emissions to enable high-throughput animal screening. The objective of the present study was to determine the genetic parameters for ruminal and plasma VFA concentrations in sheep fed alfalfa (Medicago sativa L.) pellets and their genetic (rg) and phenotypic (rp) correlations with CH4 emissions. Measurements of CH4 emissions in respiration chambers and ruminal (stomach tubing 18 h from last meal) and blood plasma (3 h post-feeding) VFA concentrations were made on 1,538 lambs from 5 birth years (2007 and 2009 to 2012) aged between 5 and 10 mo, while the animals were fed alfalfa pellets at 2.0 times maintenance requirements in 2 equal size meals (0900 and 1500 h). These measurements were repeated twice (rounds) 14 d apart. Mean (± SD) CH4 production was 24.4 ± 3.08 g/d, and the mean CH4 yield was 15.8 ± 1.51 g/kg DMI. Mean concentration of total ruminal VFA was 52.2 mM, with concentrations of acetate, propionate and butyrate of 35.97, 8.83, and 4.02 mM, respectively. Ruminal total VFA concentration had heritability (h2) and repeatability estimates (± SE) of 0.24 ± 0.05 and 0.35 ± 0.03, respectively, and similar estimates were found for acetate, propionate, and butyrate. Blood plasma concentrations of VFA had much lower estimates of h2 and repeatability than ruminal VFA. Genetic correlations with CH4 yield were greatest for total concentrations of ruminal VFA and acetate, with 0.54 ± 0.12 and 0.56 ± 0.12, respectively, which were much greater than their corresponding rp. The rp and rg of ruminal VFA proportions and blood VFAs with CH4 emissions were in general lower than for ruminal VFA concentrations. However, minor ruminal VFA proportions had also moderate rg with CH4 yield. Pre-feeding concentrations of total VFA and acetate were the strongest correlated proxies to select sheep that are genetically low CH4 emitters.
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Ito, Ayako, Takao Ando, Aya Nozaki, Ai Haraguchi, Ichiro Horie i Atsushi Kawakami. "VISCERAL AND SUBCUTANEOUS FAT INCREASED AFTER TREATMENT OF GRAVES DISEASE". Endocrine Practice 26, nr 5 (maj 2020): 484–91. http://dx.doi.org/10.4158/ep-2019-0459.
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Objective: Patients with Graves disease (GD) tend to gain weight after treatment, but it remains unknown if weight gain is associated with an increase in the visceral and/or subcutaneous fat areas (VFA, SFA). Methods: We enrolled 25 newly diagnosed GD patients (22 females, median age 33.0 years) and studied their clinical parameters, and VFA and SFA measured by a dual bioelectric impedance analysis. We divided them into 2 groups based on the rates of change in the VFA and SFA, and we compared clinical parameters at the baseline between the groups to evaluate factors that influence increases in the VFA and/or SFA with treatment. Results: The patients' body weight (BW), VFA, and SFA were significantly increased after a 6-month treatment (BW: from 54.3 ± 10.3 kg to 58.0 ± 11.2 kg; P<.001; VFA: from 47.1 ± 21.3 cm2 to 54.7 ± 23.4 cm2; P = .004; SFA: from 159.8 ± 85.9 cm2 to 182.2 ± 82.9 cm2; P = .008). The percent changes of BW correlated with the SFA (ρ = .591, P = .002), but not with the VFA. The patients with larger VFA increases had significantly less VFA at the baseline compared to those with smaller increases, expressed as median and interquartile range (33.9 cm2 [22.7 to 47.5 cm2] versus 54.5 cm2 [45.2 to 64.0], respectively; P = .011). A larger increase in the SFA was negatively associated with serum alkaline phosphatase. An increase in the SFA was associated with free triiodothyronine (T3) in a multivariate logistic analysis (odds ratio: 0.80 [0.59 to 0.97]; P = .013). Conclusion: The patients' BW, VFA, and SFA were increased after GD treatment. The increase in SFA seemed to contribute to weight gain and was associated with a low baseline level of free T3. Abbreviations: ALP = alkaline phosphatase; BMI = body mass index; BW = body weight; GD = Graves disease; SFA = subcutaneous fat area; T3 = triiodothyronine; T4 = thyroxine; TG = triglycerides; VFA = visceral fat areas
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TANAKA, Hiroshi, Kazutaka KURODA i Michihiro YONAGA. "Biological Removal of VFA from Animal Wastes". Nihon Chikusan Gakkaiho 63, nr 1 (1992): 54–59. http://dx.doi.org/10.2508/chikusan.63.54.
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Robinson, D. L., J. Goopy i R. S. Hegarty. "Can rumen methane production be predicted from volatile fatty acid concentrations?" Animal Production Science 50, nr 6 (2010): 630. http://dx.doi.org/10.1071/an09214.
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Rumen cannulated sheep (n = 12) were tested at each of three feeding levels: 0.8, 1.24 and 1.6 times maintenance. The ration (lucerne chaff) was provided in eight equal portions to emulate morning and afternoon grazing. After at least 10 days adaptation to each feeding level, methane production was measured in an open circuit calorimeter for 22 h using the same feeding regime. During measurement, 10 rumen samples were taken for volatile fatty acid (VFA) analysis by an indwelling rumen probe with a sampling tube that passed outside the calorimeter. Feed intake was strongly correlated with daily methane production (DMP, r = 0.87). Both methane production and VFA concentrations showed bimodal patterns related to the feeding cycle, but feed intake had a much smaller effect on VFA concentrations than on methane production rate. Average VFA concentration was a poor predictor of DMP. The best predictor, propionate concentration, explained 26% of the variance in DMP. The weakness of the association between VFA concentrations and methane production could be a consequence of differences in rumen volume and differences in VFA absorption associated with feeding level, although the possibility of accumulation of alternate fermentation end products or re-fermentation of VFA cannot be excluded. It is concluded that none of the suite of VFA parameters assessed offers a useful tool to predict daily methane production in grazing sheep.
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Hellemans, J., i M. De Kelver. "Using a computer to illustratePproportional toTandPproportional to 1/Vfor air". Physics Education 28, nr 2 (marzec 1993): 129–31. http://dx.doi.org/10.1088/0031-9120/28/2/013.
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Srigutomo, Wahyu, Cahyo Aji Hapsoro, Acep Purqon, Warsa, Doddy Sutarno i Tsuneomi Kagiyama. "Nonlinear Inversion Using Very Fast Simulated Annealing for Horizontal Electric Dipole Time-Domain Electromagnetic Data". Journal of Electromagnetic Engineering and Science 21, nr 5 (30.11.2021): 379–90. http://dx.doi.org/10.26866/jees.2021.5.r.46.
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A nonlinear stochastic inversion scheme, called very fast simulated annealing (VFSA), was applied to the time-domain electromagnetic data generated from a horizontal electric dipole. The forward formulation of the vertical magnetic field was expressed in the Laplace domain by applying the Hankel integral transform. Time-domain transformation was performed by applying the inverse Laplace transform using the Gaver–Stehfest algorithm. In this study, for noise-free synthetic data, the VFSA scheme yielded the smallest misfit and an inverted resistivity model that resembled the test model. The addition of 5% random noise to the synthetic data produced the same level of misfit and a model that still mimicked the test model. However, the addition of 10% noise to the synthetic data resulted in a misfit value that was three times that of the first two values and a resistivity model with a large discrepancy with the test model, particularly at large depths. These results indicate the efficacy of the VFSA inversion scheme for inferring the subsurface resistivity structure from the electromagnetic data. This inversion scheme was applied to field data measured in a volcanic environment. The general pattern of the resistivity structure inferred by the VFSA inversion is consistent with the structure obtained previously by using a deterministic inversion scheme.
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Srivichai, Piyavadee, Chumaporn Rodsrida, Nakit Chansamut i Wirinya Mueangchang. "Study on the Potential Use of Modified Tapioca Starch Sludge Waste for Volatile Fatty Acid Generation". Trends in Sciences 19, nr 3 (20.01.2022): 2146. http://dx.doi.org/10.48048/tis.2022.2146.
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Starch sludge (SS) is a bulky main waste from modified tapioca starch production, a high potential substrate for alternative volatile fatty acids (VFA) production. Because it has relatively high organic content in SS is easy and fast to convert into VFA. However, there are limitations when fed overloading rate to anaerobic digestion (AD) system affecting the VFA production yield and system performance. This research aims to study the effect of initial feeding concentrations of SS between 0.5 and 2.5 % total volatile solids (TVS) on the VFA production efficiency by applying a batch continuously stirred tank reactor (CSTR) for digestion. The maximum VFA yield was 115 mg VFA/g TVS at a feeding rate of 2.0 % TVS of SS after 4 days of digestion. The digestion system could run under proper system performance and stability by showing higher pH. Besides, acetic acid was the predominant VFA intermediate indicating great effective digestion. Finally, the main bacteria in the inoculum were Arenimonas up to 33 % because it preferred to grow on glucose. And inoculum obtained from the beverage plant’s wastewater treatment system. These were so useful to select the inoculum for organic starch digestion.
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Huq, Nabila A., Glenn R. Hafenstine, Xiangchen Huo, Hannah Nguyen, Stephen M. Tifft, Davis R. Conklin, Daniela Stück i in. "Toward net-zero sustainable aviation fuel with wet waste–derived volatile fatty acids". Proceedings of the National Academy of Sciences 118, nr 13 (15.03.2021): e2023008118. http://dx.doi.org/10.1073/pnas.2023008118.
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With the increasing demand for net-zero sustainable aviation fuels (SAF), new conversion technologies are needed to process waste feedstocks and meet carbon reduction and cost targets. Wet waste is a low-cost, prevalent feedstock with the energy potential to displace over 20% of US jet fuel consumption; however, its complexity and high moisture typically relegates its use to methane production from anaerobic digestion. To overcome this, methanogenesis can be arrested during fermentation to instead produce C2 to C8 volatile fatty acids (VFA) for catalytic upgrading to SAF. Here, we evaluate the catalytic conversion of food waste–derived VFAs to produce n-paraffin SAF for near-term use as a 10 vol% blend for ASTM “Fast Track” qualification and produce a highly branched, isoparaffin VFA-SAF to increase the renewable blend limit. VFA ketonization models assessed the carbon chain length distributions suitable for each VFA-SAF conversion pathway, and food waste–derived VFA ketonization was demonstrated for >100 h of time on stream at approximately theoretical yield. Fuel property blending models and experimental testing determined normal paraffin VFA-SAF meets 10 vol% fuel specifications for “Fast Track.” Synergistic blending with isoparaffin VFA-SAF increased the blend limit to 70 vol% by addressing flashpoint and viscosity constraints, with sooting 34% lower than fossil jet. Techno-economic analysis evaluated the major catalytic process cost-drivers, determining the minimum fuel selling price as a function of VFA production costs. Life cycle analysis determined that if food waste is diverted from landfills to avoid methane emissions, VFA-SAF could enable up to 165% reduction in greenhouse gas emissions relative to fossil jet.
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Tantaoui, H., K. Nassar i S. Janani. "AB0620 MODIFICATION OF THE DECISION OF THE ANTI-OSTEOPOROSIS TREATMENT AFTER PERFORMING THE VFA". Annals of the Rheumatic Diseases 80, Suppl 1 (19.05.2021): 1344.2–1344. http://dx.doi.org/10.1136/annrheumdis-2021-eular.3318.
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Background:Spinal fractures are the most common of all osteoporotic fractures. Its diagnosis is essential, because the discovery of a vertebral fracture testifies the gravity of osteoporosis and modifies the therapeutic intervention threshold by justifying a specific anti-osteoporosis treatment. The evolution of densitometers now makes it possible to take a true X-ray image using software called “Vertebral Fracture Assessment” or VFA.Objectives:To assess the impact of VFA results on therapeutic decision-making after measuring bone mineral density.Methods:We conducted a retrospective and descriptive study in the rheumatology department.We included all patient followed at the consultation for bone pathologies, in whom a measurement of bone mineral density and a supplementation of VFA were performed. Clinical data, BMD, VFA and the therapeutic decision by anti-osteoporosis treatment before and after VFA were collected.Results:Sixty-one patients were included. The mean age was 62.8 years [38 - 85 years]. Sex ratio (female / male) was 19.3. At BMD level, patients with osteoporosis and osteopenia were 49% and 51% respectively. VFA objectified at least one spinal fracture in 64% of patients. Prior to VFA, anti-osteoporosis therapy was indicated to 49% of patients, based on clinical data and BMD. After performing VFA, the prescription of anti-osteoporosis therapy was indicated to 80% of patients.Conclusion:Patients who had no indication for osteoporosis treatment based on BMD data, VFA was able to modify their therapeutic treatment by detecting vertebral fractures in patients who had back pain.Disclosure of Interests:None declared.
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Song, Kyo Young, i Jung Ho Shim. "Clinical significance of obesity index (VFA versus BMI) as a risk factor for gastric cancer surgery." Journal of Clinical Oncology 30, nr 4_suppl (1.02.2012): 139. http://dx.doi.org/10.1200/jco.2012.30.4_suppl.139.
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139 Background: Obesity is considered as a major perioperative risk factor in various cancer surgeries. We aimed to elucidate the effect of two different obesity index, such as VFA (visceral fat area) and BMI (body mass index), on gastrectomy. Methods: From Mar 2009 to July 2010, 632 patients with diagnosed gastric carcinoma underwent curative gastrecomy at Seoul St. Mary’s hospital. We reviewed patients’ clinicopatholic data and collected 187 patients who had data including BMI, VFA and SFA. Patients with body mass index (BMI) ≥ 25 kg/m 2 were defined as obese and visceral fat area (VFA) ≥ 100 were defined as centrally obese. Results: Out of a total 187 patients, eighty patients were in the high BMI group and 107 patients were in the low BMI group. We selected patients with high VFA and low BMI (group A) and compared to the patients with low VFA and low BMI (group B). Out of a total 107 patients in low BMI, seventy three patients were censored as high VFA, and age older than 60 and male patients were prevalent in this group (p=0.045 and 0.046). The operation time (OT) and estimated blood loss (EBL) were significantly higher in group A than group B (p=0.043 and p=0.05). Conclusions: VFA and BMI are correlated each other and successfully represent patients’ obesity. However in selected patients, such as male patients with age older than sixty, VFA more practically represent their obesity.
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Hikita, Kosuke, Naokazu Chiba, Masashi Nakagawa, Itsuki Koganezawa, Kei Yokozuka, Toshimichi Kobayashi, Toru Sano i in. "Efficacy of Peak Hounsfield Units of the Visceral Fat Area in Predicting Postoperative Complications after Pancreaticoduodenectomy". Digestive Surgery 37, nr 4 (2020): 331–39. http://dx.doi.org/10.1159/000505060.
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Background: Morbidity following pancreaticoduodenectomy (PD) has been reported to remain high. This study sought to measure the peak Hounsfield units (HUs) of visceral attenuation in patients undergoing PD and to assess the quality of adipocytes by comparing these measurements with perioperative factors. Methods: Patients undergoing PD were retrospectively identified (n = 108). Abdominal perimeter, subcutaneous fat area (SFA), visceral fat area (VFA), and peak HU of the VFA were measured. Logistic regression analysis was used to identify independent predictors of postoperative pancreatic fistula (POPF) or complications. Histopathological examination was performed for qualitative diagnosis of the stromal tissue. Results: The overall rate of POPF was 16%, and severe complications occurred in 23% of the cases. A criterion for peak HU of the VFA only independently predicted POPF (p = 0.007) in the multivariate analysis. A criterion for peak HU of the VFA (p = 0.015) was associated with an increased rate of postoperative severe complications in the univariate analysis. The peak HU of the VFA was significantly correlated with abdominal perimeter (p < 0.001) and VFA (p < 0.001). The peak HU of the VFA was significantly correlated with adipocyte diameter (p < 0.001) and the ratio of stromal connective tissue area around the adipocytes (p < 0.001). Conclusion: The peak HU of the VFA was an independent factor contributing to severe complications, including POPF after PD. It reflects the amount of stromal connective tissue around the adipocytes.