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Elasticity of short DNA molecules: theory and experiment for contour lengths of 0.6-7 microm.

PubMed

Seol, Yeonee; Li, Jinyu; Nelson, Philip C; Perkins, Thomas T; Betterton, M D

2007-12-15

The wormlike chain (WLC) model currently provides the best description of double-stranded DNA elasticity for micron-sized molecules. This theory requires two intrinsic material parameters-the contour length L and the persistence length p. We measured and then analyzed the elasticity of double-stranded DNA as a function of L (632 nm-7.03 microm) using the classic solution to the WLC model. When the elasticity data were analyzed using this solution, the resulting fitted value for the persistence length p(wlc) depended on L; even for moderately long DNA molecules (L = 1300 nm), this apparent persistence length was 10% smaller than its limiting value for long DNA. Because p is a material parameter, and cannot depend on length, we sought a new solution to the WLC model, which we call the "finite wormlike chain (FWLC)," to account for effects not considered in the classic solution. Specifically we accounted for the finite chain length, the chain-end boundary conditions, and the bead rotational fluctuations inherent in optical trapping assays where beads are used to apply the force. After incorporating these corrections, we used our FWLC solution to generate force-extension curves, and then fit those curves with the classic WLC solution, as done in the standard experimental analysis. These results qualitatively reproduced the apparent dependence of p(wlc) on L seen in experimental data when analyzed with the classic WLC solution. Directly fitting experimental data to the FWLC solution reduces the apparent dependence of p(fwlc) on L by a factor of 3. Thus, the FWLC solution provides a significantly improved theoretical framework in which to analyze single-molecule experiments over a broad range of experimentally accessible DNA lengths, including both short (a few hundred nanometers in contour length) and very long (microns in contour length) molecules.
Generalized theory of semiflexible polymers.

PubMed

Wiggins, Paul A; Nelson, Philip C

2006-03-01

DNA bending on length scales shorter than a persistence length plays an integral role in the translation of genetic information from DNA to cellular function. Quantitative experimental studies of these biological systems have led to a renewed interest in the polymer mechanics relevant for describing the conformational free energy of DNA bending induced by protein-DNA complexes. Recent experimental results from DNA cyclization studies have cast doubt on the applicability of the canonical semiflexible polymer theory, the wormlike chain (WLC) model, to DNA bending on biologically relevant length scales. This paper develops a theory of the chain statistics of a class of generalized semiflexible polymer models. Our focus is on the theoretical development of these models and the calculation of experimental observables. To illustrate our methods, we focus on a specific, illustrative model of DNA bending. We show that the WLC model generically describes the long-length-scale chain statistics of semiflexible polymers, as predicted by renormalization group arguments. In particular, we show that either the WLC or our present model adequately describes force-extension, solution scattering, and long-contour-length cyclization experiments, regardless of the details of DNA bend elasticity. In contrast, experiments sensitive to short-length-scale chain behavior can in principle reveal dramatic departures from the linear elastic behavior assumed in the WLC model. We demonstrate this explicitly by showing that our toy model can reproduce the anomalously large short-contour-length cyclization factors recently measured by Cloutier and Widom. Finally, we discuss the applicability of these models to DNA chain statistics in the context of future experiments.
Methods for modeling cytoskeletal and DNA filaments

NASA Astrophysics Data System (ADS)

Andrews, Steven S.

2014-02-01

This review summarizes the models that researchers use to represent the conformations and dynamics of cytoskeletal and DNA filaments. It focuses on models that address individual filaments in continuous space. Conformation models include the freely jointed, Gaussian, angle-biased chain (ABC), and wormlike chain (WLC) models, of which the first three bend at discrete joints and the last bends continuously. Predictions from the WLC model generally agree well with experiment. Dynamics models include the Rouse, Zimm, stiff rod, dynamic WLC, and reptation models, of which the first four apply to isolated filaments and the last to entangled filaments. Experiments show that the dynamic WLC and reptation models are most accurate. They also show that biological filaments typically experience strong hydrodynamic coupling and/or constrained motion. Computer simulation methods that address filament dynamics typically compute filament segment velocities from local forces using the Langevin equation and then integrate these velocities with explicit or implicit methods; the former are more versatile and the latter are more efficient. Much remains to be discovered in biological filament modeling. In particular, filament dynamics in living cells are not well understood, and current computational methods are too slow and not sufficiently versatile. Although primarily a review, this paper also presents new statistical calculations for the ABC and WLC models. Additionally, it corrects several discrepancies in the literature about bending and torsional persistence length definitions, and their relations to flexural and torsional rigidities.
Modeling AFM-induced PEVK extension and the reversible unfolding of Ig/FNIII domains in single and multiple titin molecules.

PubMed Central

Zhang, B; Evans, J S

2001-01-01

Molecular elasticity is associated with a select number of polypeptides and proteins, such as titin, Lustrin A, silk fibroin, and spider silk dragline protein. In the case of titin, the globular (Ig) and non-globular (PEVK) regions act as extensible springs under stretch; however, their unfolding behavior and force extension characteristics are different. Using our time-dependent macroscopic method for simulating AFM-induced titin Ig domain unfolding and refolding, we simulate the extension and relaxation of hypothetical titin chains containing Ig domains and a PEVK region. Two different models are explored: 1) a series-linked WLC expression that treats the PEVK region as a distinct entropic spring, and 2) a summation of N single WLC expressions that simulates the extension and release of a discrete number of parallel titin chains containing constant or variable amounts of PEVK. In addition to these simulations, we also modeled the extension of a hypothetical PEVK domain using a linear Hooke's spring model to account for "enthalpic" contributions to PEVK elasticity. We find that the modified WLC simulations feature chain length compensation, Ig domain unfolding/refolding, and force-extension behavior that more closely approximate AFM, laser tweezer, and immunolocalization experimental data. In addition, our simulations reveal the following: 1) PEVK extension overlaps with the onset of Ig domain unfolding, and 2) variations in PEVK content within a titin chain ensemble lead to elastic diversity within that ensemble. PMID:11159428
High flexibility of DNA on short length scales probed by atomic force microscopy.

PubMed

Wiggins, Paul A; van der Heijden, Thijn; Moreno-Herrero, Fernando; Spakowitz, Andrew; Phillips, Rob; Widom, Jonathan; Dekker, Cees; Nelson, Philip C

2006-11-01

The mechanics of DNA bending on intermediate length scales (5-100 nm) plays a key role in many cellular processes, and is also important in the fabrication of artificial DNA structures, but previous experimental studies of DNA mechanics have focused on longer length scales than these. We use high-resolution atomic force microscopy on individual DNA molecules to obtain a direct measurement of the bending energy function appropriate for scales down to 5 nm. Our measurements imply that the elastic energy of highly bent DNA conformations is lower than predicted by classical elasticity models such as the worm-like chain (WLC) model. For example, we found that on short length scales, spontaneous large-angle bends are many times more prevalent than predicted by the WLC model. We test our data and model with an interlocking set of consistency checks. Our analysis also shows how our model is compatible with previous experiments, which have sometimes been viewed as confirming the WLC.
Kinetics of interior loop formation in semiflexible chains.

PubMed

Hyeon, Changbong; Thirumalai, D

2006-03-14

Loop formation between monomers in the interior of semiflexible chains describes elementary events in biomolecular folding and DNA bending. We calculate analytically the interior distance distribution function for semiflexible chains using a mean field approach. Using the potential of mean force derived from the distance distribution function we present a simple expression for the kinetics of interior looping by adopting Kramers theory. For the parameters, that are appropriate for DNA, the theoretical predictions in comparison with the case are in excellent agreement with explicit Brownian dynamics simulations of wormlike chain (WLC) model. The interior looping times (tauIC) can be greatly altered in the cases when the stiffness of the loop differs from that of the dangling ends. If the dangling end is stiffer than the loop then tauIC increases for the case of the WLC with uniform persistence length. In contrast, attachment of flexible dangling ends enhances rate of interior loop formation. The theory also shows that if the monomers are charged and interact via screened Coulomb potential then both the cyclization (tauc) and interior looping (tauIC) times greatly increase at low ionic concentration. Because both tauc and tauIC are determined essentially by the effective persistence length [lp(R)] we computed lp(R) by varying the range of the repulsive interaction between the monomers. For short range interactions lp(R) nearly coincides with the bare persistence length which is determined largely by the backbone chain connectivity. This finding rationalizes the efficacy of describing a number of experimental observations (response of biopolymers to force and cyclization kinetics) in biomolecules using WLC model with an effective persistence length.
The snakelike chain character of unstructured RNA.

PubMed

Jacobson, David R; McIntosh, Dustin B; Saleh, Omar A

2013-12-03

In the absence of base-pairing and tertiary structure, ribonucleic acid (RNA) assumes a random-walk conformation, modulated by the electrostatic self-repulsion of the charged, flexible backbone. This behavior is often modeled as a Kratky-Porod "wormlike chain" (WLC) with a Barrat-Joanny scale-dependent persistence length. In this study we report measurements of the end-to-end extension of poly(U) RNA under 0.1 to 10 pN applied force and observe two distinct elastic-response regimes: a low-force, power-law regime characteristic of a chain of swollen blobs on long length scales and a high-force, salt-valence-dependent regime consistent with ion-stabilized crumpling on short length scales. This short-scale structure is additionally supported by force- and salt-dependent quantification of the RNA ion atmosphere composition, which shows that ions are liberated under stretching; the number of ions liberated increases with increasing bulk salt concentration. Both this result and the observation of two elastic-response regimes directly contradict the WLC model, which predicts a single elastic regime across all forces and, when accounting for scale-dependent persistence length, the opposite trend in ion release with salt concentration. We conclude that RNA is better described as a "snakelike chain," characterized by smooth bending on long length scales and ion-stabilized crumpling on short length scales. In monovalent salt, these two regimes are separated by a characteristic length that scales with the Debye screening length, highlighting the determining importance of electrostatics in RNA conformation. Copyright © 2013 Biophysical Society. Published by Elsevier Inc. All rights reserved.
The Snakelike Chain Character of Unstructured RNA

PubMed Central

Jacobson, David R.; McIntosh, Dustin B.; Saleh, Omar A.

2013-01-01

In the absence of base-pairing and tertiary structure, ribonucleic acid (RNA) assumes a random-walk conformation, modulated by the electrostatic self-repulsion of the charged, flexible backbone. This behavior is often modeled as a Kratky-Porod “wormlike chain” (WLC) with a Barrat-Joanny scale-dependent persistence length. In this study we report measurements of the end-to-end extension of poly(U) RNA under 0.1 to 10 pN applied force and observe two distinct elastic-response regimes: a low-force, power-law regime characteristic of a chain of swollen blobs on long length scales and a high-force, salt-valence-dependent regime consistent with ion-stabilized crumpling on short length scales. This short-scale structure is additionally supported by force- and salt-dependent quantification of the RNA ion atmosphere composition, which shows that ions are liberated under stretching; the number of ions liberated increases with increasing bulk salt concentration. Both this result and the observation of two elastic-response regimes directly contradict the WLC model, which predicts a single elastic regime across all forces and, when accounting for scale-dependent persistence length, the opposite trend in ion release with salt concentration. We conclude that RNA is better described as a “snakelike chain,” characterized by smooth bending on long length scales and ion-stabilized crumpling on short length scales. In monovalent salt, these two regimes are separated by a characteristic length that scales with the Debye screening length, highlighting the determining importance of electrostatics in RNA conformation. PMID:24314087
How a short double-stranded DNA bends

NASA Astrophysics Data System (ADS)

Shin, Jaeoh; Lee, O.-Chul; Sung, Wokyung

2015-04-01

A recent experiment using fluorescence microscopy showed that double-stranded DNA fragments shorter than 100 base pairs loop with the probabilities higher by the factor of 102-106 than predicted by the worm-like chain (WLC) model [R. Vafabakhsh and T. Ha, Science 337, 1101(2012)]. Furthermore, the looping probabilities were found to be nearly independent of the loop size. The results signify a breakdown of the WLC model for DNA mechanics which works well on long length scales and calls for fundamental understanding for stressed DNA on shorter length scales. We develop an analytical, statistical mechanical model to investigate what emerges to the short DNA under a tight bending. A bending above a critical level initiates nucleation of a thermally induced bubble, which could be trapped for a long time, in contrast to the bubbles in both free and uniformly bent DNAs, which are either transient or unstable. The trapped bubble is none other than the previously hypothesized kink, which releases the bending energy more easily as the contour length decreases. It leads to tremendous enhancement of the cyclization probabilities, in a reasonable agreement with experiment.
Landslide susceptibility mapping for a landslide-prone area (Findikli, NE of Turkey) by likelihood-frequency ratio and weighted linear combination models

NASA Astrophysics Data System (ADS)

Akgun, Aykut; Dag, Serhat; Bulut, Fikri

2008-05-01

Landslides are very common natural problems in the Black Sea Region of Turkey due to the steep topography, improper use of land cover and adverse climatic conditions for landslides. In the western part of region, many studies have been carried out especially in the last decade for landslide susceptibility mapping using different evaluation methods such as deterministic approach, landslide distribution, qualitative, statistical and distribution-free analyses. The purpose of this study is to produce landslide susceptibility maps of a landslide-prone area (Findikli district, Rize) located at the eastern part of the Black Sea Region of Turkey by likelihood frequency ratio (LRM) model and weighted linear combination (WLC) model and to compare the results obtained. For this purpose, landslide inventory map of the area were prepared for the years of 1983 and 1995 by detailed field surveys and aerial-photography studies. Slope angle, slope aspect, lithology, distance from drainage lines, distance from roads and the land-cover of the study area are considered as the landslide-conditioning parameters. The differences between the susceptibility maps derived by the LRM and the WLC models are relatively minor when broad-based classifications are taken into account. However, the WLC map showed more details but the other map produced by LRM model produced weak results. The reason for this result is considered to be the fact that the majority of pixels in the LRM map have high values than the WLC-derived susceptibility map. In order to validate the two susceptibility maps, both of them were compared with the landslide inventory map. Although the landslides do not exist in the very high susceptibility class of the both maps, 79% of the landslides fall into the high and very high susceptibility zones of the WLC map while this is 49% for the LRM map. This shows that the WLC model exhibited higher performance than the LRM model.
Withdrawal of care: a 10-year perspective at a Level I trauma center.

PubMed

Sise, Michael J; Sise, C Beth; Thorndike, Jonathan F; Kahl, Jessica E; Calvo, Richard Y; Shackford, Steven R

2012-05-01

Withdrawal or limitation of care (WLC) in trauma patients has not been well studied. We reviewed 10 years of deaths at our adult Level I trauma center to identify the patients undergoing WLC and to describe the process of trauma surgeon-managed WLC. This is a retrospective review of WLC. Each patient was assigned to one of three modes of WLC: care withdrawn, limited or no resuscitation, or organ harvest. Frequency, timing, and circumstances of WLC, including family involvement, ethics committee consultation, palliative care, and hospice, were reviewed. From 2000 through 2009, 375 patients died with WLC (54% of all deaths; 93% at ≥ 24 hours). For age ≥ 65 years, 80% were WLC. Overall, 15% had advance directive documents. Traumatic brain or high cervical spine injury was the cause of death in 63%. Factors associated with WLC included age, comorbidities, injury mechanism and severity, and nontrauma activation status. At time of death, 316 (84%) WLC were under trauma surgeon management. In this group, mode of WLC was care withdrawn in 74%, organ harvest in 20%, and limited or no resuscitation in 6%. Rationale for WLC in non-organ harvest patients was poor neurologic prognosis in 86% and futility in 76%. When family was identified, end-of-life discussions with physicians occurred in 100%. Conflicts over WLC occurred in 6.6% and were not associated with any demographic group. Ethics committee was involved in 2.8%. For care-withdrawn patients, median time to death from first WLC order was 6.6 hours. Palliative care and hospice consults (6% and 9%) increased yearly. WLC occurred in over 50% of all trauma deaths and exceeded 90% at ≥ 24 hours. Hospice and palliative care were increasingly important adjuncts to WLC. Guidelines for WLC should be developed to ensure quality end-of-life care for trauma patients in whom further care is futile. III, therapeutic study.
Hydrological regulation drives regime shifts: evidence from paleolimnology and ecosystem modeling of a large shallow Chinese lake.

PubMed

Kong, Xiangzhen; He, Qishuang; Yang, Bin; He, Wei; Xu, Fuliu; Janssen, Annette B G; Kuiper, Jan J; van Gerven, Luuk P A; Qin, Ning; Jiang, Yujiao; Liu, Wenxiu; Yang, Chen; Bai, Zelin; Zhang, Min; Kong, Fanxiang; Janse, Jan H; Mooij, Wolf M

2017-02-01

Quantitative evidence of sudden shifts in ecological structure and function in large shallow lakes is rare, even though they provide essential benefits to society. Such 'regime shifts' can be driven by human activities which degrade ecological stability including water level control (WLC) and nutrient loading. Interactions between WLC and nutrient loading on the long-term dynamics of shallow lake ecosystems are, however, often overlooked and largely underestimated, which has hampered the effectiveness of lake management. Here, we focus on a large shallow lake (Lake Chaohu) located in one of the most densely populated areas in China, the lower Yangtze River floodplain, which has undergone both WLC and increasing nutrient loading over the last several decades. We applied a novel methodology that combines consistent evidence from both paleolimnological records and ecosystem modeling to overcome the hurdle of data insufficiency and to unravel the drivers and underlying mechanisms in ecosystem dynamics. We identified the occurrence of two regime shifts: one in 1963, characterized by the abrupt disappearance of submerged vegetation, and another around 1980, with strong algal blooms being observed thereafter. Using model scenarios, we further disentangled the roles of WLC and nutrient loading, showing that the 1963 shift was predominantly triggered by WLC, whereas the shift ca. 1980 was attributed to aggravated nutrient loading. Our analysis also shows interactions between these two stressors. Compared to the dynamics driven by nutrient loading alone, WLC reduced the critical P loading and resulted in earlier disappearance of submerged vegetation and emergence of algal blooms by approximately 26 and 10 years, respectively. Overall, our study reveals the significant role of hydrological regulation in driving shallow lake ecosystem dynamics, and it highlights the urgency of using multi-objective management criteria that includes ecological sustainability perspectives when implementing hydrological regulation for aquatic ecosystems around the globe. © 2016 John Wiley & Sons Ltd.
Are changes in objective working hour characteristics associated with changes in work-life conflict among hospital employees working shifts? A 7-year follow-up.

PubMed

Karhula, Kati; Koskinen, Aki; Ojajärvi, Anneli; Ropponen, Annina; Puttonen, Sampsa; Kivimäki, Mika; Härmä, Mikko

2018-06-01

To investigate whether changes in objective working hour characteristics are associated with parallel changes in work-life conflict (WLC) among hospital employees. Survey responses from three waves of the Finnish Public Sector study (2008, 2012 and 2015) were combined with payroll data from 91 days preceding the surveys (n=2 482, 93% women). Time-dependent fixed effects regression models adjusted for marital status, number of children and stressfulness of the life situation were used to investigate whether changes in working hour characteristics were associated with parallel change in WLC. The working hour characteristics were dichotomised with cut-points in less than or greater than 10% or less than or greater than25% occurrence) and WLC to frequent versus seldom/none. Change in proportion of evening and night shifts and weekend work was significantly associated with parallel change in WLC (adjusted OR 2.19, 95% CI 1.62 to 2.96; OR 1.71, 95% CI 1.21 to 2.44; OR 1.63, 95% CI 1.194 to 2.22, respectively). Similarly, increase or decrease in proportion of quick returns (adjusted OR 1.45, 95% CI 1.10 to 1.89) and long work weeks (adjusted OR 1.26, 95% CI 1.04 to 1.52) was associated with parallel increase or decrease in WLC. Single days off and very long work weeks showed no association with WLC. Changes in unsocial working hour characteristics, especially in connection with evening shifts, are consistently associated with parallel changes in WLC. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.
Are changes in objective working hour characteristics associated with changes in work-life conflict among hospital employees working shifts? A 7-year follow-up

PubMed Central

Karhula, Kati; Koskinen, Aki; Ojajärvi, Anneli; Puttonen, Sampsa; Kivimäki, Mika; Härmä, Mikko

2018-01-01

Objective To investigate whether changes in objective working hour characteristics are associated with parallel changes in work-life conflict (WLC) among hospital employees. Methods Survey responses from three waves of the Finnish Public Sector study (2008, 2012 and 2015) were combined with payroll data from 91 days preceding the surveys (n=2 482, 93% women). Time-dependent fixed effects regression models adjusted for marital status, number of children and stressfulness of the life situation were used to investigate whether changes in working hour characteristics were associated with parallel change in WLC. The working hour characteristics were dichotomised with cut-points in less than or greater than 10% or less than or greater than25% occurrence) and WLC to frequent versus seldom/none. Results Change in proportion of evening and night shifts and weekend work was significantly associated with parallel change in WLC (adjusted OR 2.19, 95% CI 1.62 to 2.96; OR 1.71, 95% CI 1.21 to 2.44; OR 1.63, 95% CI 1.194 to 2.22, respectively). Similarly, increase or decrease in proportion of quick returns (adjusted OR 1.45, 95% CI 1.10 to 1.89) and long work weeks (adjusted OR 1.26, 95% CI 1.04 to 1.52) was associated with parallel increase or decrease in WLC. Single days off and very long work weeks showed no association with WLC. Conclusions Changes in unsocial working hour characteristics, especially in connection with evening shifts, are consistently associated with parallel changes in WLC. PMID:29367350
Work-life conflict and musculoskeletal disorders: a cross-sectional study of an unexplored association

PubMed Central

2011-01-01

Background The health consequences of work-family or rather work-life conflict (WLC) have been studied by numerous researchers. The work-related causes of musculoskeletal disorders (MSD) are also well explored. And stress (at work) has been found to be a consequence of WLC as well as a cause of MSD. But very little is known about a potential association between WLC and MSD and the possible mediating role of stress in this relationship. Methods Survey data collected in 2007 among the workforces of four large companies in Switzerland were used for this study. The study population covered 6091 employees. As the exposure variable and hypothesized risk factor for MSD, WLC was measured by using a 10-item scale based on an established 18-item scale on work-family conflict. The outcome variables used as indicators of MSD were (low) back pain and neck/shoulder pain. Stress as the assumed intervening variable was assessed by a validated single-item measure of general stress perception. Correlation coefficients (r), standardized regression coefficients (β) and multiple adjusted odds ratios (OR) were calculated as measures of association. Results WLC was found to be quite strongly associated with MSD (β = .21). This association turned out to be substantially confounded by physical strain at work, workload and job autonomy and was considerably reduced but far from being completely eliminated after adjusting for general stress as another identified risk factor of MSD and a proven strong correlate of WLC (r = .44). A significant and relevant association still remained (β = .10) after having controlled for all considered covariates. This association could be fully attributed to only one direction of WLC, namely the work-to-life conflict. In subsequent analyses, a clear gradient between this WLC direction and both types of MSD was found, and proved to be consistent for both men and women. Employees who were most exposed to such work-to-life conflict were also most at risk and showed a fivefold higher prevalence rate (19%-42%) and also an up to sixfold increased relative risk (OR = 3.8-6.3) of suffering greatly from these types of MSD compared with the least exposed reference group showing very low WLC in this direction. Including stress in the regression models again reduced the strength of the association significantly (OR = 1.9-4.1), giving an indication for a possible indirect effect of WLC on MSD mediated by stress. Conclusion Future research and workplace interventions for the prevention of MSD need to consider WLC as an important stressor, and the MSD risk factor identified in this study. PMID:21410950
Work-life conflict and musculoskeletal disorders: a cross-sectional study of an unexplored association.

PubMed

Hämmig, Oliver; Knecht, Michaela; Läubli, Thomas; Bauer, Georg F

2011-03-16

The health consequences of work-family or rather work-life conflict (WLC) have been studied by numerous researchers. The work-related causes of musculoskeletal disorders (MSD) are also well explored. And stress (at work) has been found to be a consequence of WLC as well as a cause of MSD. But very little is known about a potential association between WLC and MSD and the possible mediating role of stress in this relationship. Survey data collected in 2007 among the workforces of four large companies in Switzerland were used for this study. The study population covered 6091 employees. As the exposure variable and hypothesized risk factor for MSD, WLC was measured by using a 10-item scale based on an established 18-item scale on work-family conflict. The outcome variables used as indicators of MSD were (low) back pain and neck/shoulder pain. Stress as the assumed intervening variable was assessed by a validated single-item measure of general stress perception. Correlation coefficients (r), standardized regression coefficients (β) and multiple adjusted odds ratios (OR) were calculated as measures of association. WLC was found to be quite strongly associated with MSD (β=.21). This association turned out to be substantially confounded by physical strain at work, workload and job autonomy and was considerably reduced but far from being completely eliminated after adjusting for general stress as another identified risk factor of MSD and a proven strong correlate of WLC (r=.44). A significant and relevant association still remained (β=.10) after having controlled for all considered covariates. This association could be fully attributed to only one direction of WLC, namely the work-to-life conflict. In subsequent analyses, a clear gradient between this WLC direction and both types of MSD was found, and proved to be consistent for both men and women. Employees who were most exposed to such work-to-life conflict were also most at risk and showed a fivefold higher prevalence rate (19%-42%) and also an up to sixfold increased relative risk (OR = 3.8-6.3) of suffering greatly from these types of MSD compared with the least exposed reference group showing very low WLC in this direction. Including stress in the regression models again reduced the strength of the association significantly (OR=1.9-4.1), giving an indication for a possible indirect effect of WLC on MSD mediated by stress. Future research and workplace interventions for the prevention of MSD need to consider WLC as an important stressor, and the MSD risk factor identified in this study. © 2011 Hämmig et al; licensee BioMed Central Ltd.
Effect of genomic long-range correlations on DNA persistence length: from theory to single molecule experiments.

PubMed

Moukhtar, Julien; Faivre-Moskalenko, Cendrine; Milani, Pascale; Audit, Benjamin; Vaillant, Cedric; Fontaine, Emeline; Mongelard, Fabien; Lavorel, Guillaume; St-Jean, Philippe; Bouvet, Philippe; Argoul, Françoise; Arneodo, Alain

2010-04-22

Sequence dependency of DNA intrinsic bending properties has been emphasized as a possible key ingredient to in vivo chromatin organization. We use atomic force microscopy (AFM) in air and liquid to image intrinsically straight (synthetic), uncorrelated (hepatitis C RNA virus) and persistent long-range correlated (human) DNA fragments in various ionic conditions such that the molecules freely equilibrate on the mica surface before being captured in a particular conformation. 2D thermodynamic equilibrium is experimentally verified by a detailed statistical analysis of the Gaussian nature of the DNA bend angle fluctuations. We show that the worm-like chain (WLC) model, commonly used to describe the average conformation of long semiflexible polymers, reproduces remarkably well the persistence length estimates for the first two molecules as consistently obtained from (i) mean square end-to-end distance measurement and (ii) mean projection of the end-to-end vector on the initial orientation. Whatever the operating conditions (air or liquid, concentration of metal cations Mg(2+) and/or Ni(2+)), the persistence length found for the uncorrelated viral DNA underestimates the value obtained for the straight DNA. We show that this systematic difference is the signature of the presence of an uncorrelated structural intrinsic disorder in the hepatitis C virus (HCV) DNA fragment that superimposes on local curvatures induced by thermal fluctuations and that only the entropic disorder depends upon experimental conditions. In contrast, the WLC model fails to describe the human DNA conformations. We use a mean-field extension of the WLC model to account for the presence of long-range correlations (LRC) in the intrinsic curvature disorder of human genomic DNA: the stronger the LRC, the smaller the persistence length. The comparison of AFM imaging of human DNA with LRC DNA simulations confirms that the rather small mean square end-to-end distance observed, particularly for G+C-rich human DNA molecules, more likely results from a large-scale intrinsic curvature due to a persistent distribution of DNA curvature sites than from some increased flexibility.
Blue light cystoscopy with hexylaminolevulinate: Our 7 years experience.

PubMed

Lacetera, Vito; Cantoro, Ubaldo; Montesi, Lorenzo; Cantoro, Daniele; Cervelli, Bernardo; Cicetti, Antonio; Gabrielloni, Giuliana; Milella, Domenico; Montesi, Michele; Morcellini, Roberto; Parri, Gianni; Recanatini, Emilio; Beatrici, Valerio

2017-03-31

The objective of the present study is to evaluate the diagnostic accuracy of hexylaminolevulinate (HAL) blue light cystoscopy compared with standard white light cystoscopy (WLC) in daily practice. An observational, comparative, controlled (within patient) study was carried out at our Center. 61 consecutive patients with suspected or confirmed bladder cancer were recruited for the study from January 2008 until January 2015. Patients with suspected bladder cancer (positive cytology with negative WLC) or history of previous high-grade NMIBC or CIS were included in the study. Biopsies/resection of each positive lesion/suspicious areas were always taken after the bladder was inspected under WLC and BLC. Diagnoses of bladder tumor or CIS were considered as positive results, and the presence of normal urothelium in the biopsy specimen as negative result. 61 BLC were performed. 15/61 (24.5%) with suspected initial diagnosis of NMIBC and 46/61 (75.5%) with a history of high-risk non-muscle invasive bladder cancer (NMIBC). We performed a total of 173 biopsies/TURBT of suspicious areas: 129 positive only to the BLC and 44 both positive to WLC and BLC. 84/173 biopsies/TURBT were positive for cancer. All 84 NMIBC were positive to the BLC, while 35/84 were positive to the WLC with a sensitivity of BLC and WLC respectively of 100% and 41.7%. Sensitivity of WLC for highgrade NMIBC and CIS was 34.1% and 39% respectively while sensitivity of BLC for high-grade NMIBC and CIS was 100%. The specificity of the WLC was 79.9% compared to 48.5% of the BLC. The positive predictive value of BLC and WLC were respectively 48% (95% CI: 0.447-0.523) and 79% (95% CI: 0.856-0.734). Our data confirm those reported in the literature: BLC increases the detection rate of NMIBC particularly in high risk patients (history of CIS or high grade). BLC is a powerful diagnostic tool in the diagnosis of bladder cancer if malignancy is suspected (positive urine cytology) and if conventional WLC is negative.
Volumetric wireless coil based on periodically coupled split-loop resonators for clinical wrist imaging.

PubMed

Shchelokova, Alena V; van den Berg, Cornelis A T; Dobrykh, Dmitry A; Glybovski, Stanislav B; Zubkov, Mikhail A; Brui, Ekaterina A; Dmitriev, Dmitry S; Kozachenko, Alexander V; Efimtcev, Alexander Y; Sokolov, Andrey V; Fokin, Vladimir A; Melchakova, Irina V; Belov, Pavel A

2018-02-09

Design and characterization of a new inductively driven wireless coil (WLC) for wrist imaging at 1.5 T with high homogeneity operating due to focusing the B 1 field of a birdcage body coil. The WLC design has been proposed based on a volumetric self-resonant periodic structure of inductively coupled split-loop resonators with structural capacitance. The WLC was optimized and studied regarding radiofrequency fields and interaction to the birdcage coil (BC) by electromagnetic simulations. The manufactured WLC was characterized by on-bench measurements and in vivo and phantom study in comparison to a standard cable-connected receive-only coil. The WLC placed into BC gave the measured B1+ increase of the latter by 8.6 times for the same accepted power. The phantom and in vivo wrist imaging showed that the BC in receiving with the WLC inside reached equal or higher signal-to-noise ratio than the conventional clinical setup comprising the transmit-only BC and a commercial receive-only flex-coil and created no artifacts. Simulations and on-bench measurements proved safety in terms of specific absorption rate and reflected transmit power. The results showed that the proposed WLC could be an alternative to standard cable-connected receive coils in clinical magnetic resonance imaging. As an example, with no cable connection, the WLC allowed wrist imaging on a 1.5 T clinical machine using a full-body BC for transmitting and receive with the desired signal-to-noise ratio, image quality, and safety. © 2018 International Society for Magnetic Resonance in Medicine.
Learning of Chunking Sequences in Cognition and Behavior

PubMed Central

Rabinovich, Mikhail

2015-01-01

We often learn and recall long sequences in smaller segments, such as a phone number 858 534 22 30 memorized as four segments. Behavioral experiments suggest that humans and some animals employ this strategy of breaking down cognitive or behavioral sequences into chunks in a wide variety of tasks, but the dynamical principles of how this is achieved remains unknown. Here, we study the temporal dynamics of chunking for learning cognitive sequences in a chunking representation using a dynamical model of competing modes arranged to evoke hierarchical Winnerless Competition (WLC) dynamics. Sequential memory is represented as trajectories along a chain of metastable fixed points at each level of the hierarchy, and bistable Hebbian dynamics enables the learning of such trajectories in an unsupervised fashion. Using computer simulations, we demonstrate the learning of a chunking representation of sequences and their robust recall. During learning, the dynamics associates a set of modes to each information-carrying item in the sequence and encodes their relative order. During recall, hierarchical WLC guarantees the robustness of the sequence order when the sequence is not too long. The resulting patterns of activities share several features observed in behavioral experiments, such as the pauses between boundaries of chunks, their size and their duration. Failures in learning chunking sequences provide new insights into the dynamical causes of neurological disorders such as Parkinson’s disease and Schizophrenia. PMID:26584306

Maier-Saupe model of polymer nematics: Comparing free energies calculated with Self Consistent Field theory and Monte Carlo simulations.

PubMed

Greco, Cristina; Jiang, Ying; Chen, Jeff Z Y; Kremer, Kurt; Daoulas, Kostas Ch

2016-11-14

Self Consistent Field (SCF) theory serves as an efficient tool for studying mesoscale structure and thermodynamics of polymeric liquid crystals (LC). We investigate how some of the intrinsic approximations of SCF affect the description of the thermodynamics of polymeric LC, using a coarse-grained model. Polymer nematics are represented as discrete worm-like chains (WLC) where non-bonded interactions are defined combining an isotropic repulsive and an anisotropic attractive Maier-Saupe (MS) potential. The range of the potentials, σ, controls the strength of correlations due to non-bonded interactions. Increasing σ (which can be seen as an increase of coarse-graining) while preserving the integrated strength of the potentials reduces correlations. The model is studied with particle-based Monte Carlo (MC) simulations and SCF theory which uses partial enumeration to describe discrete WLC. In MC simulations the Helmholtz free energy is calculated as a function of strength of MS interactions to obtain reference thermodynamic data. To calculate the free energy of the nematic branch with respect to the disordered melt, we employ a special thermodynamic integration (TI) scheme invoking an external field to bypass the first-order isotropic-nematic transition. Methodological aspects which have not been discussed in earlier implementations of the TI to LC are considered. Special attention is given to the rotational Goldstone mode. The free-energy landscape in MC and SCF is directly compared. For moderate σ the differences highlight the importance of local non-bonded orientation correlations between segments, which SCF neglects. Simple renormalization of parameters in SCF cannot compensate the missing correlations. Increasing σ reduces correlations and SCF reproduces well the free energy in MC simulations.
Prevalence and Health Correlates of Work-Life Conflict among Blue- and White-Collar Workers from Different Economic Sectors

PubMed Central

Hämmig, Oliver

2014-01-01

The research on work-life conflict (WLC) is largely neglected in occupational medicine and public health and typically limited to white-collar workers and public servants. This study therefore aims to explore possible differences in the prevalence of WLC and its association with health outcomes between white- and blue-collar workers from different work environments in Switzerland. Cross-sectional survey data collected in 2007 in the service sector and in 2010 in the industrial sector were used for statistical analyses. A subsample of university graduates employed by large service companies (N = 1,170) from the first survey’s population was taken and compared with a subsample of low or unskilled industrial and construction workers with no or only compulsory education (N = 489) from the second survey’s population. The results show almost consistently, and particularly in women, a lower prevalence of time- and strain-based forms and both causal directions of WLC in blue-collar workers. However, associations between different WLC measures and general, physical and mental health outcomes were found to be equally strong or even stronger among blue-collar workers compared to white-collar workers. Low or unskilled industrial and construction workers are less frequently affected by higher degrees of WLC but are then at no lower risk of suffering poor self-rated health or severe backaches and sleep disorders than university graduates working in the service sector with comparable exposure to WLC. In conclusion, it can be stated that WLC turned out to be much less prevalent but equally or even more detrimental to health in blue-collar workers, who therefore need to be considered in future studies. PMID:25426483
An effective model of DNA like helicoidal structure: with length fluctuation nonlinearity

NASA Astrophysics Data System (ADS)

Tseytlin, Y. M.

2011-03-01

One of the natural helicoidal nanostructure, which thermomechanical features are studied carefully with the help of different mechanical models, is a DNA cell / molecule. Our study proves that the experimentally determined nonlinear fluctuations of the molecular length of DNA can be better understood by modeling the molecule as a helicoidal pretwisted nanostrip sensor with nonlinear function. The calculations presented here are in good agreement with the experimental data within 10%. Other used by many researchers mechanical models such as an elastic rod, wormlike chain (WLC), accordion bellows, or an elastic core wrapped with rigid wires do not show the possible variance nonlinearity of thermomechanical DNA molecular length fluctuations. We have found that the nonlinear variance of the length fluctuations is an intrinsic property of the micro-nano-sensors with helicoidal shape. This model allows us to estimate the persistence length and twist-stretch coupling of a DNA molecule as well. It also shows the molecule's overwinding possibility at initial stretching with correct numerical representation.
The Long-Term Impact of Neurofeedback on Symptom Burden and Interference in Patients With Chronic Chemotherapy-Induced Neuropathy: Analysis of a Randomized Controlled Trial.

PubMed

Prinsloo, Sarah; Novy, Diane; Driver, Larry; Lyle, Randall; Ramondetta, Lois; Eng, Cathy; Lopez, Gabriel; Li, Yisheng; Cohen, Lorenzo

2018-05-01

Chemotherapy-induced peripheral neuropathy (CIPN) is a common side effect of cancer treatment and may adversely affect quality of life (QOL) for years. We explored the long-term effects of electroencephalographic neurofeedback (NFB) as a treatment for CIPN and other aspects of QOL. Seventy-one cancer survivors (mean age 62.5; 87% females) with CIPN were randomized to NFB or to a waitlist control (WLC) group. The NFB group underwent 20 sessions of NFB where rewards were given for voluntary changes in electroencephalography. Measurements of pain, cancer-related symptoms, QOL, sleep, and fatigue were obtained at baseline, end of treatment, and one and four months later. Seventy one participants enrolled in the study. At the end of treatment, 30 in the NFB group and 32 in the WLC group completed assessments; at four months, 23 in the NFB group and 28 in the WLC completed assessments. Linear mixed model analysis revealed significant group × time interaction for pain severity. A general linear model determined that the NFB group had greater improvements in worst pain (primary outcome) and other symptoms such as numbness, cancer-related symptom severity, symptom interference, physical functioning, general health, and fatigue compared with the WLC group at the end of treatment and four months (all P < 0.05). Effect sizes were moderate or large for most measures. NFB appears to result in long-term reduction in multiple CIPN symptoms and improved postchemotherapy QOL and fatigue. Copyright © 2018 American Academy of Hospice and Palliative Medicine. Published by Elsevier Inc. All rights reserved.
Virtual 3D bladder reconstruction for augmented medical records from white light cystoscopy (Conference Presentation)

NASA Astrophysics Data System (ADS)

Lurie, Kristen L.; Zlatev, Dimitar V.; Angst, Roland; Liao, Joseph C.; Ellerbee, Audrey K.

2016-02-01

Bladder cancer has a high recurrence rate that necessitates lifelong surveillance to detect mucosal lesions. Examination with white light cystoscopy (WLC), the standard of care, is inherently subjective and data storage limited to clinical notes, diagrams, and still images. A visual history of the bladder wall can enhance clinical and surgical management. To address this clinical need, we developed a tool to transform in vivo WLC videos into virtual 3-dimensional (3D) bladder models using advanced computer vision techniques. WLC videos from rigid cystoscopies (1280 x 720 pixels) were recorded at 30 Hz followed by immediate camera calibration to control for image distortions. Video data were fed into an automated structure-from-motion algorithm that generated a 3D point cloud followed by a 3D mesh to approximate the bladder surface. The highest quality cystoscopic images were projected onto the approximated bladder surface to generate a virtual 3D bladder reconstruction. In intraoperative WLC videos from 36 patients undergoing transurethral resection of suspected bladder tumors, optimal reconstruction was achieved from frames depicting well-focused vasculature, when the bladder was maintained at constant volume with minimal debris, and when regions of the bladder wall were imaged multiple times. A significant innovation of this work is the ability to perform the reconstruction using video from a clinical procedure collected with standard equipment, thereby facilitating rapid clinical translation, application to other forms of endoscopy and new opportunities for longitudinal studies of cancer recurrence.
Low-fat meat sausages with fish oil: optimization of milk proteins and carrageenan contents using response surface methodology.

PubMed

Marchetti, L; Andrés, S C; Califano, A N

2014-03-01

Response surface methodology was used to analyze the effect of milk proteins and 2:1 κ:ι-carrageenans on cooking loss (CL), weight lost by centrifugation (WLC) and texture attributes of low-fat meat sausages with pre-emulsified fish oil. A central-composite design was used to develop models for the objective responses. Changes in carrageenans affected more the responses than milk proteins levels. Convenience functions were calculated for CL, WLC, hardness, and springiness of the product. Responses were optimized simultaneously minimizing CL and WLC; ranges for hardness and springiness corresponded to commercial products (20 g of pork fat/100 g). The optimum corresponded to 0.593 g of carrageenans/100 g and 0.320 g of milk proteins and its total lipid content was 6.3 g/100 g. This formulation was prepared and evaluated showing a good agreement between predicted and experimental responses. These additives could produce low-fat meat sausages with pre-emulsified fish oil with good nutritional quality and similar characteristics than traditional ones. Copyright © 2013 Elsevier Ltd. All rights reserved.
Signatures of Nonlinear Waves in Coronal Plumes and Holes

NASA Technical Reports Server (NTRS)

Ofman, Leon

1999-01-01

In recent Ultraviolet Coronagraph Spectrometer/Solar and Heliospheric Observatory (UVCS/SOHO) White Light Channel (WLC) observations we found quasi-periodic variations in the polarized brightness (pB) in the polar coronal holes at heliocentric distances of 1.9-2.45 solar radii. The motivation for the observation is the 2.5D Magnetohydrodynamics (MHD) model of solar wind acceleration by nonlinear waves, that predicts compressive fluctuations in coronal holes. To help identify the waves observed with the UVCS/WLC we model the propagation and dissipation of slow magnetosonic waves in polar plumes using 1D MHD code in spherical geometry, We find that the slow waves nonlinearly steepen in the gravitationally stratified plumes. The nonlinear steepening of the waves leads to enhanced dissipation due to compressive viscosity at the wave-fronts.
Individual differences in working memory capacity and workload capacity.

PubMed

Yu, Ju-Chi; Chang, Ting-Yun; Yang, Cheng-Ta

2014-01-01

We investigated the relationship between working memory capacity (WMC) and workload capacity (WLC). Each participant performed an operation span (OSPAN) task to measure his/her WMC and three redundant-target detection tasks to measure his/her WLC. WLC was computed non-parametrically (Experiments 1 and 2) and parametrically (Experiment 2). Both levels of analyses showed that participants high in WMC had larger WLC than those low in WMC only when redundant information came from visual and auditory modalities, suggesting that high-WMC participants had superior processing capacity in dealing with redundant visual and auditory information. This difference was eliminated when multiple processes required processing for only a single working memory subsystem in a color-shape detection task and a double-dot detection task. These results highlighted the role of executive control in integrating and binding information from the two working memory subsystems for perceptual decision making.
Movement of liquid droplets containing polymers on substrate

NASA Astrophysics Data System (ADS)

Hu, Guohui; Wang, Heng

2016-11-01

It is of both fundamental and practical interests to study the flow physics in the manipulation of droplets. As a microreactor, the macromolecules or particles inside the droplets might have significant influences on their movement. In the present study, the many-body dissipative particle dynamics (MDPD) is utilized to investigate the translocation of droplets containing polymer on a substrate driven by the wettability gradient, where the polymer is modelled as worm-like chain (WLC). The internal flows of the droplets are analyzed, as well as the comparison to the polymer-free moving droplets. The effects of physical parameters, such as the interaction potential between liquid particle and polymer beads, the mass of the beads, on the translocation speed are also addressed in the present study. These results might be helpful to the optimization in design of the microfluidic systems.
Z-scan measurements using femtosecond continuum generation

NASA Astrophysics Data System (ADS)

de Boni, Leonardo; Andrade, Acácio A.; Misoguti, Lino; Mendonça, Cléber R.; Zilio, Sérgio Carlos

2004-08-01

We present a single beam Z-scan technique using an intense, broadband, white-light continuum (WLC) beam for the direct measurement of nonlinear absorption spectra. In order to demonstrate the validity of our technique, we compared the results of tetraaniline and Sudan 3 solutions obtained with WLC and conventional single wavelength light sources. Both approaches lead to the same nonlinear spectrum, indicating that the association of the Z-scan technique and the WLC source results in an useful method for the measurement of nonlinear spectra of both absorbing (saturable absorption or reverse saturable absorption) and transparent (two-photon absorption) samples.
WLC Preface

NASA Astrophysics Data System (ADS)

Miret, Josep M.; Sebé, Francesc

Low-cost devices are the key component of several applications: RFID tags permit an automated supply chain management while smart cards are a secure means of storing cryptographic keys required for remote and secure authentication in e-commerce and e-government applications. These devices must be cheap in order to permit their cost-effective massive manufacturing and deployment. Unfortunately, their low cost limits their computational power. Other devices such as nodes of sensor networks suffer from an additional constraint, namely, their limited battery life. Secure applications designed for these devices cannot make use of classical cryptographic primitives designed for full-fledged computers.
Electroacupuncture for fatigue, sleep, and psychological distress in breast cancer patients with aromatase inhibitor-related arthralgia: a randomized trial.

PubMed

Mao, Jun J; Farrar, John T; Bruner, Deborah; Zee, Jarcy; Bowman, Marjorie; Seluzicki, Christina; DeMichele, Angela; Xie, Sharon X

2014-12-01

Although fatigue, sleep disturbance, depression, and anxiety are associated with pain in breast cancer patients, it is unknown whether acupuncture can decrease these comorbid symptoms in cancer patients with pain. The objective of this study was to evaluate the effect of electroacupuncture (EA) on fatigue, sleep, and psychological distress in breast cancer survivors who experience joint pain related to aromatase inhibitors (AIs). The authors performed a randomized controlled trial of an 8-week course of EA compared with a waitlist control (WLC) group and a sham acupuncture (SA) group in postmenopausal women with breast cancer who self-reported joint pain attributable to AIs. Fatigue, sleep disturbance, anxiety, and depression were measured using the Brief Fatigue Inventory (BFI), the Pittsburgh Sleep Quality Index (PSQI), and the Hospital Anxiety and Depression Scale (HADS). The effects of EA and SA versus WLC on these outcomes were evaluated using mixed-effects models. Of the 67 randomly assigned patients, baseline pain interference was associated with fatigue (Pearson correlation coefficient [r]=0.75; P < .001), sleep disturbance (r=0.38; P=.0026), and depression (r=0.58; P < .001). Compared with the WLC condition, EA produced significant improvements in fatigue (P=.0095), anxiety (P=.044), and depression (P=.015) and a nonsignificant improvement in sleep disturbance (P=.058) during the 12-week intervention and follow-up period. In contrast, SA did not produce significant reductions in fatigue or anxiety symptoms but did produce a significant improvement in depression compared with the WLC condition (P=.0088). Compared with usual care, EA produced significant improvements in fatigue, anxiety, and depression; whereas SA improved only depression in women experiencing AI-related arthralgia. © 2014 American Cancer Society.
When Leadership Counts: Engaging Youth through the Washington Leadership Conference

ERIC Educational Resources Information Center

Stedman, Nicole L. P.; Rutherford, Tracy A.; Rosser, Manda H.; Elbert, Chanda

2009-01-01

The National FFA Organization continues to be a leader in the positive development of youth. Programs sponsored by the FFA provide youth with opportunities to develop their capacity for leadership and citizenship. The Washington Leadership Conference (WLC) is a weeklong conference during the summer that culminates the FFA experience. The WLC's…
Massage therapy decreases cancer-related fatigue: Results from a randomized early phase trial.

PubMed

Kinkead, Becky; Schettler, Pamela J; Larson, Erika R; Carroll, Dedric; Sharenko, Margaret; Nettles, James; Edwards, Sherry A; Miller, Andrew H; Torres, Mylin A; Dunlop, Boadie W; Rakofsky, Jeffrey J; Rapaport, Mark Hyman

2018-02-01

Cancer-related fatigue (CRF) is a prevalent and debilitating symptom experienced by cancer survivors, yet treatment options for CRF are limited. In this study, we evaluated the efficacy of weekly Swedish massage therapy (SMT) versus an active control condition (light touch [LT]) and waitlist control (WLC) on persistent CRF in breast cancer survivors. This early phase, randomized, single-masked, 6-week investigation of SMT, LT, and WLC enrolled 66 female stage 0-III breast cancer survivors (age range, 32-72 years) who had received surgery plus radiation and/or chemotherapy/chemoprevention with CRF (Brief Fatigue Inventory > 25). The primary outcome was the Multidimensional Fatigue Inventory (MFI), with the National Institutes of Health PROMIS Fatigue scale secondary. Mean baseline MFI scores for 57 evaluable subjects were 62.95 for SMT, 55.00 for LT, and 60.41 for WLC. SMT resulted in a mean (standard deviation) 6-week reduction in MFI total scores of -16.50 (6.37) (n = 20) versus -8.06 (6.50) for LT (n = 20) and an increase of 5.88 (6.48) points for WLC (n = 17) (treatment-by-time P < .0001). The mean baseline PROMIS Fatigue scores were SMT, 22.25; LT, 22.05; and WLC, 23.24. The mean (standard deviation) reduction in PROMIS Fatigue scores was -5.49 (2.53) points for SMT versus -3.24 (2.57) points for LT and -0.06 (1.88) points for WLC (treatment-by-time P = .0008). Higher credibility, expectancy, and preference for SMT than for LT did not account for these results. SMT produced clinically significant relief of CRF. This finding suggests that 6 weeks of a safe, widely accepted manual intervention causes a significant reduction in fatigue, a debilitating sequela for cancer survivors. Cancer 2018;124:546-54. © 2017 American Cancer Society. © 2017 American Cancer Society.
Work-life conflict and associations with work- and nonwork-related factors and with physical and mental health outcomes: a nationally representative cross-sectional study in Switzerland

PubMed Central

2009-01-01

Background The aim of the present cross-sectional study was to examine work- and nonwork- related factors and physical and mental health outcomes associated with combined time- and strain-based work-life conflict (WLC) among adult employees living and working in Switzerland as well as possible gender differences in this regard. Methods The data used for the study were taken from wave 6 of the nationally representative Swiss Household Panel (SHP) collected in 2004. The analysis was restricted to 4'371 employees aged 20 to 64 years. Trivariate crosstabulations and multivariate linear and logistic regression analyses stratified by gender were performed in order to calculate gender-specific prevalence rates (%), beta coefficients (β) and crude as well as multiple adjusted odds ratios (OR) as measures of association. Results Every eighth person (12.5%) within the study population has a high or very high WLC score. Prevalence rates are clearly above average in men and women with higher education, in executive positions or managerial functions, in full-time jobs, with variable work schedules, regular overtime, long commuting time to work and job insecurity. Working overtime regularly, having variable work schedules and being in a management position are most strongly associated with WLC in men, whereas in women the level of employment is the strongest explanatory variable by far, followed by variable work schedules and high job status (managerial position). In both men and women, WLC is associated with several physical and mental health problems. Employees with high or very high WLC show a comparatively high relative risk of self-reported poor health, anxiety and depression, lack of energy and optimism, serious backache, headaches, sleep disorders and fatigue. While overall prevalence rate of (very) high WLC is higher in men than in women, associations between degrees of WLC and most health outcomes are stronger in women than in men. Conclusion This important issue which up to now has been largely neglected in public health research needs to be addressed in future public health research and, if the findings are confirmed by subsequent (longitudinal) studies, to be considered in workplace health promotion and interventions in Switzerland as elsewhere. PMID:19943980
Experiences of Work-Life Conflict for the Athletic Trainer Employed Outside the National Collegiate Athletic Association Division I Clinical Setting.

PubMed

Mazerolle, Stephanie M; Pitney, William A; Eason, Christianne M

2015-07-01

The intercollegiate setting receives much of the scholarly attention related to work-life conflict (WLC). However research has been focused on the National Collegiate Athletic Association Division I setting. Multiple factors can lead to WLC for the athletic trainer (AT), including hours, travel, and lack of flexibility in work schedules. To investigate the experiences of WLC among ATs working in the non-Division I collegiate setting and to identify factors that contribute to fulfillment of work-life balance in this setting. Qualitative study. Institutions in the National Collegiate Athletic Association Divisions II and III, the National Association of Intercollegiate Athletics, and the National Junior College Athletic Association. A total of 244 ATs (128 women, 114 men; age = 37.5 ± 13.3 years, experience = 14 ± 12 years) completed phase I. Thirteen participants (8 women, 5 men; age = 38 ± 13 years, experience = 13.1 ± 11.4 years) completed phase II. For phase I, participants completed a previously validated and reliable (Cronbach α > .90) Web-based survey measuring their levels of WLC and work-family conflict (WFC). This phase included 2 WFC scales defining family; scale 1 defined family as having a partner or spouse with or without children, and scale 2 defined family as those individuals, including parents, siblings, grandparents, and any other close relatives, involved in one's life. Phase II consisted of an interview. Qualitative data were evaluated using content analysis. Data source and multiple-analyst triangulation secured credibility. The WFC scores were 26.33 ± 7.37 for scale 1 and 20.46 ± 10.14 for scale 2, indicating a moderate level of WFC for scale 1 and a low level of WFC for scale 2. Qualitative analyses revealed that organizational dimensions, such as job demands and staffing issues, can negatively affect WLC, whereas a combination of organizational and personal dimensions can positively affect WLC. Overload continues to be a prevalent factor in negatively influencing WLC and WFC. Supervisor and peer support, personal networks, and time away from the role positively influenced work-life balance and WFC. Athletic trainers are encouraged to support one another in the workplace, especially when providing flexibility in scheduling.
Work-life conflict and associations with work- and nonwork-related factors and with physical and mental health outcomes: a nationally representative cross-sectional study in Switzerland.

PubMed

Hämmig, Oliver; Gutzwiller, Felix; Bauer, Georg

2009-11-30

The aim of the present cross-sectional study was to examine work- and nonwork- related factors and physical and mental health outcomes associated with combined time- and strain-based work-life conflict (WLC) among adult employees living and working in Switzerland as well as possible gender differences in this regard. The data used for the study were taken from wave 6 of the nationally representative Swiss Household Panel (SHP) collected in 2004. The analysis was restricted to 4'371 employees aged 20 to 64 years. Trivariate crosstabulations and multivariate linear and logistic regression analyses stratified by gender were performed in order to calculate gender-specific prevalence rates (%), beta coefficients (beta) and crude as well as multiple adjusted odds ratios (OR) as measures of association. Every eighth person (12.5%) within the study population has a high or very high WLC score. Prevalence rates are clearly above average in men and women with higher education, in executive positions or managerial functions, in full-time jobs, with variable work schedules, regular overtime, long commuting time to work and job insecurity. Working overtime regularly, having variable work schedules and being in a management position are most strongly associated with WLC in men, whereas in women the level of employment is the strongest explanatory variable by far, followed by variable work schedules and high job status (managerial position). In both men and women, WLC is associated with several physical and mental health problems. Employees with high or very high WLC show a comparatively high relative risk of self-reported poor health, anxiety and depression, lack of energy and optimism, serious backache, headaches, sleep disorders and fatigue. While overall prevalence rate of (very) high WLC is higher in men than in women, associations between degrees of WLC and most health outcomes are stronger in women than in men. This important issue which up to now has been largely neglected in public health research needs to be addressed in future public health research and, if the findings are confirmed by subsequent (longitudinal) studies, to be considered in workplace health promotion and interventions in Switzerland as elsewhere.
Experiences of Work-Life Conflict for the Athletic Trainer Employed Outside the National Collegiate Athletic Association Division I Clinical Setting

PubMed Central

Mazerolle, Stephanie M.; Pitney, William A.; Eason, Christianne M.

2015-01-01

Context The intercollegiate setting receives much of the scholarly attention related to work-life conflict (WLC). However research has been focused on the National Collegiate Athletic Association Division I setting. Multiple factors can lead to WLC for the athletic trainer (AT), including hours, travel, and lack of flexibility in work schedules. Objective To investigate the experiences of WLC among ATs working in the non-Division I collegiate setting and to identify factors that contribute to fulfillment of work-life balance in this setting. Design Qualitative study. Setting Institutions in the National Collegiate Athletic Association Divisions II and III, the National Association of Intercollegiate Athletics, and the National Junior College Athletic Association. Patients or Other Participants A total of 244 ATs (128 women, 114 men; age = 37.5 ± 13.3 years, experience = 14 ± 12 years) completed phase I. Thirteen participants (8 women, 5 men; age = 38 ± 13 years, experience = 13.1 ± 11.4 years) completed phase II. Data Collection and Analysis For phase I, participants completed a previously validated and reliable (Cronbach α > .90) Web-based survey measuring their levels of WLC and work-family conflict (WFC). This phase included 2 WFC scales defining family; scale 1 defined family as having a partner or spouse with or without children, and scale 2 defined family as those individuals, including parents, siblings, grandparents, and any other close relatives, involved in one's life. Phase II consisted of an interview. Qualitative data were evaluated using content analysis. Data source and multiple-analyst triangulation secured credibility. Results The WFC scores were 26.33 ± 7.37 for scale 1 and 20.46 ± 10.14 for scale 2, indicating a moderate level of WFC for scale 1 and a low level of WFC for scale 2. Qualitative analyses revealed that organizational dimensions, such as job demands and staffing issues, can negatively affect WLC, whereas a combination of organizational and personal dimensions can positively affect WLC. Conclusions Overload continues to be a prevalent factor in negatively influencing WLC and WFC. Supervisor and peer support, personal networks, and time away from the role positively influenced work-life balance and WFC. Athletic trainers are encouraged to support one another in the workplace, especially when providing flexibility in scheduling. PMID:25879575
Tailored cognitive-behavioural therapy and exercise training improves the physical fitness of patients with fibromyalgia.

PubMed

van Koulil, S; van Lankveld, W; Kraaimaat, F W; van Helmond, T; Vedder, A; van Hoorn, H; Donders, A R T; Wirken, L; Cats, H; van Riel, P L C M; Evers, A W M

2011-12-01

Patients with fibromyalgia have diminished levels of physical fitness, which may lead to functional disability and exacerbating complaints. Multidisciplinary treatment comprising cognitive-behavioural therapy (CBT) and exercise training has been shown to be effective in improving physical fitness. However, due to the high drop-out rates and large variability in patients' functioning, it was proposed that a tailored treatment approach might yield more promising treatment outcomes. High-risk fibromyalgia patients were randomly assigned to a waiting list control group (WLC) or a treatment condition (TC), with the treatment consisting of 16 twice-weekly sessions of CBT and exercise training tailored to the patient's cognitive-behavioural pattern. Physical fitness was assessed with two physical tests before and 3 months after treatment and at corresponding intervals in the WLC. Treatment effects were evaluated using linear mixed models. The level of physical fitness had improved significantly in the TC compared with the WLC. Attrition rates were low, effect sizes large and reliable change indices indicated a clinically relevant improvement among the TC. A tailored multidisciplinary treatment approach for fibromyalgia consisting of CBT and exercise training is well tolerated, yields clinically relevant changes, and appears a promising approach to improve patients' physical fitness. ClinicalTrials.gov ID NCT00268606.
A neural coding scheme reproducing foraging trajectories

NASA Astrophysics Data System (ADS)

Gutiérrez, Esther D.; Cabrera, Juan Luis

2015-12-01

The movement of many animals may follow Lévy patterns. The underlying generating neuronal dynamics of such a behavior is unknown. In this paper we show that a novel discovery of multifractality in winnerless competition (WLC) systems reveals a potential encoding mechanism that is translatable into two dimensional superdiffusive Lévy movements. The validity of our approach is tested on a conductance based neuronal model showing WLC and through the extraction of Lévy flights inducing fractals from recordings of rat hippocampus during open field foraging. Further insights are gained analyzing mice motor cortex neurons and non motor cell signals. The proposed mechanism provides a plausible explanation for the neuro-dynamical fundamentals of spatial searching patterns observed in animals (including humans) and illustrates an until now unknown way to encode information in neuronal temporal series.

The 2003 Music in Our School's Month and World's Largest Concert Teacher's Guide.

ERIC Educational Resources Information Center

Music Educators National Conference, Reston, VA.

On March 13, 2003 millions of school children, teachers, and citizens from around the world participate simultaneously in the "World's Largest Concert" (WLC). This concert, a sing-along program, is broadcast on PBS and the Armed Forces Radio and Television Network overseas. Participating in the WLC is a way to celebrate Music in Our…
Work-life imbalance and mental health among male and female employees in Switzerland.

PubMed

Hämmig, Oliver; Bauer, Georg

2009-01-01

To investigate the prevalence and mental health effects of an unequal work-life balance (WLB) including potential gender differences. A cross-sectional study based on a representative sample of the Swiss employed population aged 20 to 64 (women: n = 1661; men: n = 1591). Based on a single-item measure, more than every seventh employee in Switzerland indicated major difficulties combining work and private life. In certain socio-demographic categories, up to 30% showed such work-life conflict (WLC). For both genders, work-life imbalance turned out to be a risk factor affecting mental health. Employees with self-reported WLC presented a significantly higher relative risk for poor self-rated health (women: aOR = 2.6/men: aOR = 2.0), negative emotions and depression (aOR = 3.0/3.1), low energy and optimism (aOR = 2.1/1.6), fatigue (aOR = 2.4/2.6), and sleep disorders (aOR = 1.8/1.5) compared to employees with no WLC. Internationally, few data on the prevalence of WLC exist. In Switzerland, work-life imbalance is not a marginal phenomenon among the workforce and needs to be addressed as a notable public and mental health issue.
A neural coding scheme reproducing foraging trajectories

PubMed Central

Gutiérrez, Esther D.; Cabrera, Juan Luis

2015-01-01

The movement of many animals may follow Lévy patterns. The underlying generating neuronal dynamics of such a behavior is unknown. In this paper we show that a novel discovery of multifractality in winnerless competition (WLC) systems reveals a potential encoding mechanism that is translatable into two dimensional superdiffusive Lévy movements. The validity of our approach is tested on a conductance based neuronal model showing WLC and through the extraction of Lévy flights inducing fractals from recordings of rat hippocampus during open field foraging. Further insights are gained analyzing mice motor cortex neurons and non motor cell signals. The proposed mechanism provides a plausible explanation for the neuro-dynamical fundamentals of spatial searching patterns observed in animals (including humans) and illustrates an until now unknown way to encode information in neuronal temporal series. PMID:26648311
Effect of water level changes in the middle reaches of the Yellow River in summer on CO2 emissions from wetlands dominated by Phragmites

NASA Astrophysics Data System (ADS)

Lv, Haibo; Zhang, Hong

2018-04-01

The purpose of this study was to investigate the effect of water level changes (WLC) in the middle reaches of the Yellow River in summer on CO2 emissions from wetlands dominated by Phragmites. The rate of CO2 emissions (RCE) from soil was measured in some Phragmites wetlands selected along the Yumenkou-Tongguan section in this river's middle reaches. An artificial recharge experiment was conducted and the data about this section's water levels for the past 15 years was analyzed. This study found that the water level of this river section changed frequently in the last 11 summers. The effect of WLC depended on air temperature. At low temperatures of between 18.0 and 28.0 °C, WLC contributed to a RCE change from 10.19 mmol.m-2.h-1 to 13.43 mmol.m-2.h-1. When the temperature fell within the normal range of 29.0-35.0 °C, the corresponding changes were from 4.07 mmol.m-2.h-1 to 7.35 mmol.m-2.h-1. When the temperature was higher than 35.0 °C, the corresponding changes increased slightly from 6.47 mmol.m-2.h-1 to 12.41 mmol.m-2.h-1. These suggest that WLC had a considerable effect on CO2 emissions at high and low temperatures. As the water level rose, the RCE increased and then decreased in both types of wetlands. At low temperatures, the most favorable water levels for CO2 emissions were -10 cm and 0 cm. At normal temperatures, the RCE from the two types of wetlands decreased with rising water level. At high temperatures, the most favorable water level was -60 cm for Phragmites wetlands. These results demonstrate that frequent WLC can slow CO2 release from Phragmites wetlands along the middle reaches of the Yellow River. Therefore, research on the effect of WLC on CO2 emissions has practical significance.
Determining an appropriate method for the purpose of land allocation for ecotourism development (case study: Taleghan County, Iran).

PubMed

Aliani, H; Kafaky, S Babaie; Saffari, A; Monavari, S M

2016-11-01

Appropriate management and planning of suitable areas for the development of ecotourism activities can play an important role in ensuring proper use of the environment. Due to the complexity of nature, applying different tools and models-particularly multi-criteria methods-can be useful in order to achieve these goals. In this study, to indicate suitable areas (land allocation) for ecotourism activities in Taleghan county, weighted linear combination (WLC) using geographical information system (GIS), fuzzy logic, and analytical network process (ANP) were used. To compare the applicability of each of these methods in achieving the goal, the results were compared with the previous model presented by Makhdoum. The results showed that the WLC and ANP methods are more efficient than the Makhdoum model in allocating lands for recreational areas and ecotourism purposes since concomitant use of fuzzy logic and ANP for ranking and weighing the criteria provides us with more flexible and logical conditions. Furthermore, the mentioned method makes it possible to involve ecological, economic, and social criteria simultaneously in the evaluation process in order to allocate land for ecotourism purposes.
Comparing Online with Face-to-Face HELPP Intervention in Women Experiencing Intimate Partner Violence.

PubMed

Constantino, Rose E; Braxter, Betty; Ren, Dianxu; Burroughs, Joseph David; Doswell, Willa Marlene; Wu, Linden; Hwang, Juhae Grace; Klem, Mary Lou; Joshi, James B D; Greene, W Brian

2015-06-01

Intimate partner violence (IPV) is a public health problem. The purpose of this study was to compare the effectiveness of the HELPP (Health, Education on Safety, and Legal Support and Resources in IPV Participant Preferred) intervention among IPV survivors. A sequential, transformative mixed-methods design was used. Participants were randomly assigned to one of three study groups: Online (ONL), Face-to-Face (FTF), and Waitlist Control (WLC). The HELPP intervention was offered to 32 adult female participants who were 45.2% Asian, 32.3% White, and 22.5% Black. Outcome measures were anxiety, depression, anger, personal, and social support. In total, 64% (n = 20) of the participants reported having experienced IPV before the age of 18. The anger mean score pre-test to post-test difference was significant for ONL (p < 0.001) and WLC (p = 0.01). The personal and social support pre-test to post-test mean score differences were significant for ONL (p < 0.001; p < 0.001) and WLC (p = 0.01; p = 0.006), respectively. The HELPP intervention (1) decreased anxiety, depression, anger, and (2) increased personal and social support in the ONL group. The HELPP information and intervention was shown to be feasible, acceptable, and effective among IPV survivors compared with participants in the WLC group. The WLC participants displayed (1) increased levels of anxiety, depression, and anger and (2) decreased levels of personal and social support, post-intervention. Further research could be conducted to determine if e-mail alone or e-mail plus mobile devices are more useful modes of delivering interventions.
Efficacy and safety of hexaminolevulinate fluorescence cystoscopy in the diagnosis of bladder cancer.

PubMed

Lee, Jae Seung; Lee, Seo Yeon; Kim, Woo Jung; Seo, Seong Il; Jeon, Seong Soo; Lee, Hyun Moo; Choi, Han Yong; Jeong, Byong Chang

2012-12-01

The aim of this study was to evaluate the efficacy and safety of hexaminolevulinate fluorescence cystoscopy in the diagnosis of bladder cancer. In a prospective design, we included patients who had a bladder lesion suggesting bladder cancer. Patients with massive hematuria, urethral Foley catheter insertion, chronic retention state, or urinary tract infection were excluded. After the bladder was emptied, hexaminolevulinate was gently administered into the bladder. One hour later, cystoscopy under white light and blue light was performed. After marking the lesions confirmed with white light or blue light, transurethral resection of the bladder lesion and pathologic confirmation were done. Transurethral resection of the lesions that were negative in both white and blue light was also performed. From April 2010 to September 2010, 30 patients were enrolled. From the total of 30 patients (25 men and 5 women; mean age, 60.4±9.22 years), 134 specimens were extracted. Among these, 101 specimens showed positive results by blue light cystoscopy (BLC). The sensitivity of BLC and white light cystoscopy (WLC) was 92.3% and 80.8%, respectively (p=0.021). The specificity of BLC and WLC was 48% and 49.1%, respectively (p>0.05). The positive and negative predictive values of BLC were 71.2% and 81.8%, respectively, whereas those of WLC were 72.0% and 68.6%, respectively. With WLC, 48 specimens showed negative findings, but of that group, 15 specimens (31.2%) were revealed to be malignant with BLC. There were no significant side effects in the 24 hours after the instillation of hexaminolevulinate. Photodynamic diagnosis with hexaminolevulinate helps to find tumors that could be missed by use of WLC only. Photodynamic diagnosis might be valuable in complete resection as well as for more accurate diagnosis of bladder tumor.
Role of moxibustion in inflammatory responses during treatment of rat ulcerative colitis

PubMed Central

Han, Yang; Ma, Tie-Ming; Lu, Mao-Lin; Ren, Lu; Ma, Xian-De; Bai, Zeng-Hua

2014-01-01

AIM: To investigate the efficacy of moxibustion in ulcerative colitis (UC) rats from morphological, immunological and molecular biological perspectives. METHODS: Thirty-two Sprague-Dawley rats were randomly assigned to a blank control group (normal rats, n = 6) and a model replication (MR) group (UC rats, n = 26). A UC model was established by 2,4,6-trinitrobenzenesulfonic acid/dextran sulfate sodium enema. Rats in the MR group were further randomly assigned to a 9-min moxibustion (9M) group (9 moxa-cone, n = 6), 6-min moxibustion (6M) group (6 moxa-cone, n = 6), 3-min moxibustion (3M) group (3 moxa-cone, n = 6), and a waiting list control (WLC) group (no moxibustion treatment, n = 6). Rats in the moxibustion treatment group were treated in 14 sessions over 28 d. Disease activity, local tissue morphology, serum level of interleukin (IL)-8 and IL-10, and expression of Toll-like receptor (TLR)9 as well as nuclear factor (NF)-κB p65 in colonic tissue were determined by disease activity index (DAI), hematoxylin and eosin staining, electron microscopy, enzyme-linked immunosorbent assay and Western blotting, respectively. RESULTS: DAI was lowest in the 9M group and highest in the WLC group. The differences in DAI between the moxibustion treatment (3M, 6M, 9M) and no treatment groups were significant for all one-to-one comparisons (0.60 ± 0.54 vs 1.20 ± 0.44, 0.60 ± 0.54 vs 1.80 ± 0.45, 0.60 ± 0.54 vs 3.0 ± 0.45, respectively, P < 0.05). Light and electron microscopy showed that the neatness of the glandular arrangement in colonic mucosal epithelia gradually increased in the WLC, 3M, 6M to 9M groups. IL-8 level successively decreased while IL-10 level increased from the WLC to 3M, 6M and 9M groups. The differences among these groups were significant for all comparisons (105.46 ± 8.75 vs 76.61 ± 3.58, 105.46 ± 8.75 vs 69.78 ± 1.87, 105.46 ± 8.75 vs 67.41 ± 1.84, respectively, P < 0.01 for IL-8; and 30.83 ± 1.29 vs 75.64 ± 1.90, 30.83 ± 1.29 vs 80.90 ± 3.16, 30.83 ± 1.29 vs 83.46 ± 2.37, respectively, P < 0.01 for IL-10), except comparison of 6M vs 9M. Expression of TLR9 and NF-κB p65 decreased in order: highest in the WLC group and lowest in the 9M group. In addition, the differences among the WLC, 3M, 6M and 9M groups were significant for all comparisons (0.492 ± 0.026 vs 0.380 ± 0.022, 0.492 ± 0.026 vs 0.355 ± 0.005, 0.492 ± 0.026 vs 0.327 ± 0.015, respectively, P < 0.05 for TLR9; and 0.436 ± 0.041 vs 0.326 ± 0.022, 0.436 ± 0.041 vs 0.293 ± 0.006, 0.436 ± 0.041 vs 0.265 ± 0.017, respectively, P < 0.05 for NF-κB p65). CONCLUSION: Moxibustion repairs damaged colonic mucosa, suppresses serum IL-8, activates serum IL-10 level, and decreases expression of TLR-9 and NF-κB p65 in UC rats. PMID:25170214
Role of moxibustion in inflammatory responses during treatment of rat ulcerative colitis.

PubMed

Han, Yang; Ma, Tie-Ming; Lu, Mao-Lin; Ren, Lu; Ma, Xian-De; Bai, Zeng-Hua

2014-08-28

To investigate the efficacy of moxibustion in ulcerative colitis (UC) rats from morphological, immunological and molecular biological perspectives. Thirty-two Sprague-Dawley rats were randomly assigned to a blank control group (normal rats, n = 6) and a model replication (MR) group (UC rats, n = 26). A UC model was established by 2,4,6-trinitrobenzenesulfonic acid/dextran sulfate sodium enema. Rats in the MR group were further randomly assigned to a 9-min moxibustion (9M) group (9 moxa-cone, n = 6), 6-min moxibustion (6M) group (6 moxa-cone, n = 6), 3-min moxibustion (3M) group (3 moxa-cone, n = 6), and a waiting list control (WLC) group (no moxibustion treatment, n = 6). Rats in the moxibustion treatment group were treated in 14 sessions over 28 d. Disease activity, local tissue morphology, serum level of interleukin (IL)-8 and IL-10, and expression of Toll-like receptor (TLR)9 as well as nuclear factor (NF)-κB p65 in colonic tissue were determined by disease activity index (DAI), hematoxylin and eosin staining, electron microscopy, enzyme-linked immunosorbent assay and Western blotting, respectively. DAI was lowest in the 9M group and highest in the WLC group. The differences in DAI between the moxibustion treatment (3M, 6M, 9M) and no treatment groups were significant for all one-to-one comparisons (0.60 ± 0.54 vs 1.20 ± 0.44, 0.60 ± 0.54 vs 1.80 ± 0.45, 0.60 ± 0.54 vs 3.0 ± 0.45, respectively, P < 0.05). Light and electron microscopy showed that the neatness of the glandular arrangement in colonic mucosal epithelia gradually increased in the WLC, 3M, 6M to 9M groups. IL-8 level successively decreased while IL-10 level increased from the WLC to 3M, 6M and 9M groups. The differences among these groups were significant for all comparisons (105.46 ± 8.75 vs 76.61 ± 3.58, 105.46 ± 8.75 vs 69.78 ± 1.87, 105.46 ± 8.75 vs 67.41 ± 1.84, respectively, P < 0.01 for IL-8; and 30.83 ± 1.29 vs 75.64 ± 1.90, 30.83 ± 1.29 vs 80.90 ± 3.16, 30.83 ± 1.29 vs 83.46 ± 2.37, respectively, P < 0.01 for IL-10), except comparison of 6M vs 9M. Expression of TLR9 and NF-κB p65 decreased in order: highest in the WLC group and lowest in the 9M group. In addition, the differences among the WLC, 3M, 6M and 9M groups were significant for all comparisons (0.492 ± 0.026 vs 0.380 ± 0.022, 0.492 ± 0.026 vs 0.355 ± 0.005, 0.492 ± 0.026 vs 0.327 ± 0.015, respectively, P < 0.05 for TLR9; and 0.436 ± 0.041 vs 0.326 ± 0.022, 0.436 ± 0.041 vs 0.293 ± 0.006, 0.436 ± 0.041 vs 0.265 ± 0.017, respectively, P < 0.05 for NF-κB p65). Moxibustion repairs damaged colonic mucosa, suppresses serum IL-8, activates serum IL-10 level, and decreases expression of TLR-9 and NF-κB p65 in UC rats.
Landslide susceptibility mapping using GIS-based statistical models and Remote sensing data in tropical environment

PubMed Central

Hashim, Mazlan

2015-01-01

This research presents the results of the GIS-based statistical models for generation of landslide susceptibility mapping using geographic information system (GIS) and remote-sensing data for Cameron Highlands area in Malaysia. Ten factors including slope, aspect, soil, lithology, NDVI, land cover, distance to drainage, precipitation, distance to fault, and distance to road were extracted from SAR data, SPOT 5 and WorldView-1 images. The relationships between the detected landslide locations and these ten related factors were identified by using GIS-based statistical models including analytical hierarchy process (AHP), weighted linear combination (WLC) and spatial multi-criteria evaluation (SMCE) models. The landslide inventory map which has a total of 92 landslide locations was created based on numerous resources such as digital aerial photographs, AIRSAR data, WorldView-1 images, and field surveys. Then, 80% of the landslide inventory was used for training the statistical models and the remaining 20% was used for validation purpose. The validation results using the Relative landslide density index (R-index) and Receiver operating characteristic (ROC) demonstrated that the SMCE model (accuracy is 96%) is better in prediction than AHP (accuracy is 91%) and WLC (accuracy is 89%) models. These landslide susceptibility maps would be useful for hazard mitigation purpose and regional planning. PMID:25898919
Landslide susceptibility mapping using GIS-based statistical models and Remote sensing data in tropical environment.

PubMed

Shahabi, Himan; Hashim, Mazlan

2015-04-22

This research presents the results of the GIS-based statistical models for generation of landslide susceptibility mapping using geographic information system (GIS) and remote-sensing data for Cameron Highlands area in Malaysia. Ten factors including slope, aspect, soil, lithology, NDVI, land cover, distance to drainage, precipitation, distance to fault, and distance to road were extracted from SAR data, SPOT 5 and WorldView-1 images. The relationships between the detected landslide locations and these ten related factors were identified by using GIS-based statistical models including analytical hierarchy process (AHP), weighted linear combination (WLC) and spatial multi-criteria evaluation (SMCE) models. The landslide inventory map which has a total of 92 landslide locations was created based on numerous resources such as digital aerial photographs, AIRSAR data, WorldView-1 images, and field surveys. Then, 80% of the landslide inventory was used for training the statistical models and the remaining 20% was used for validation purpose. The validation results using the Relative landslide density index (R-index) and Receiver operating characteristic (ROC) demonstrated that the SMCE model (accuracy is 96%) is better in prediction than AHP (accuracy is 91%) and WLC (accuracy is 89%) models. These landslide susceptibility maps would be useful for hazard mitigation purpose and regional planning.
Long-Term Impact of a Cell Phone-Enhanced Parenting Intervention.

PubMed

Lefever, Jennifer E Burke; Bigelow, Kathryn M; Carta, Judith J; Borkowski, John G; Grandfield, Elizabeth; McCune, Luke; Irvin, Dwight W; Warren, Steven F

2017-11-01

Home visiting programs support positive parenting in populations at-risk of child maltreatment, but their impact is often limited by poor retention and engagement. The current study assessed whether a cellular phone-supported version (PCI-C) of the Parent-Child Interactions (PCI) intervention improved long-term parenting practices, maternal depression, and children's aggression. Low-income mothers ( n = 371) of preschool-aged children were assigned to one of the three groups: PCI-C, PCI, and a wait-list control (WLC) group. Parenting improved in both intervention groups between baseline and 12-month follow-up compared to the WLC. Children in the PCI-C group were rated to be more cooperative and less aggressive than children in the WLC. The results offer evidence of the long-term effectiveness of PCI and the additional benefits of cellular phone supports for promoting intervention retention and improving children's behavior.
A symplectic integration method for elastic filaments

NASA Astrophysics Data System (ADS)

Ladd, Tony; Misra, Gaurav

2009-03-01

Elastic rods are a ubiquitous coarse-grained model of semi-flexible biopolymers such as DNA, actin, and microtubules. The Worm-Like Chain (WLC) is the standard numerical model for semi-flexible polymers, but it is only a linearized approximation to the dynamics of an elastic rod, valid for small deflections; typically the torsional motion is neglected as well. In the standard finite-difference and finite-element formulations of an elastic rod, the continuum equations of motion are discretized in space and time, but it is then difficult to ensure that the Hamiltonian structure of the exact equations is preserved. Here we discretize the Hamiltonian itself, expressed as a line integral over the contour of the filament. This discrete representation of the continuum filament can then be integrated by one of the explicit symplectic integrators frequently used in molecular dynamics. The model systematically approximates the continuum partial differential equations, but has the same level of computational complexity as molecular dynamics and is constraint free. Numerical tests show that the algorithm is much more stable than a finite-difference formulation and can be used for high aspect ratio filaments, such as actin. We present numerical results for the deterministic and stochastic motion of single filaments.
Treatment changes and long-term recurrence rates after hexaminolevulinate (HAL) fluorescence cystoscopy: does it really make a difference in patients with non-muscle-invasive bladder cancer (NMIBC)?

PubMed

Geavlete, Bogdan; Multescu, Razvan; Georgescu, Dragos; Jecu, Marian; Stanescu, Florin; Geavlete, Petrisor

2012-02-01

• To evaluate in a prospective, randomized study the impact of hexaminolevulinate blue-light cystoscopy (HAL-BLC) on the diagnostic accuracy and treatment changes in cases of non-muscle invasive bladder cancer (NMIBC) compared with standard white-light cystoscopy (WLC). • To compare the long-term recurrence rates in the two study arms. • In all, 362 patients suspected of NMIBC were included in the trial based on positive urinary cytology and/or ultrasonographic suspicion of bladder tumours and underwent transurethral resection of bladder tumours. • A single postoperative mytomicin-C instillation was performed in all cases, intravesical chemotherapy for intermediate-risk patients and BCG instillations for high-risk cases. • The follow-up protocol consisted of urinary cytology and WLC every 3 months for 2 years. • Only first-time recurrences after the initial diagnosis were considered. • In the 142 patients with NMIBC in the HAL-BLC series, tumour detection rates significantly improved for carcinoma in situ, pTa andoverall cases. • In 35.2% of the cases, additional malignant lesions were found by HAL-BLC and consequently, the recurrence- and progression-risk categories of patients and subsequent treatment improved in 19% of the cases due to fluorescence cystoscopy. • In all, 125 patients in the HAL-BLC group and 114 of the WLC group completed the follow-up. • The recurrence rate at 3 months was lower in the HAL-BLC series (7.2% vs 15.8%) due to fewer 'other site' recurrences when compared with the WLC series (0.8% vs 6.1%). • The 1 and 2 years recurrence rates were significantly decreased in the HAL-BLC group compared with the WLC group (21.6% vs 32.5% and 31.2% vs 45.6%, respectively). • HAL-BLC was better than WLC for detecting NMIBC cases and improved tumour detection rates. • HAL-BLC significantly modified the postoperative treatment of cases. • The 3 months, 1 and 2 years recurrence rates were significantly improved in the HAL-BLC arm. © 2011 THE AUTHORS. BJU INTERNATIONAL © 2011 BJU INTERNATIONAL.
Medium-term effectiveness of online behavioral training in migraine self-management: A randomized trial controlled over 10 months.

PubMed

Sorbi, M J; Kleiboer, A M; van Silfhout, H G; Vink, G; Passchier, J

2015-06-01

This randomized, controlled trial examined the medium-term effectiveness of online behavioral training in migraine self-management (oBT; N = 195) versus waitlist control (WLC; N = 173) on attack frequency, indicators of self-management (primary outcomes), headache top intensity, use of rescue medications, quality of life and disability (secondary outcomes). An online headache diary following the ICHD-II and questionnaires were completed at baseline (T0), post-training (T1) and six months later (T2). Missing data (T1: 24%; T2: 37%) were handled by multiple imputation. We established effect sizes (ES) and tested between-group differences over time with linear mixed modelling techniques based on the intention-to-treat principle. At T2, attack frequency had improved significantly in oBT (-23%, ES = 0.66) but also in WLC (-19%; ES = 0.52). Self-efficacy, internal and external control in migraine management--and triptan use--improved only in oBT, however. This indicates different processes in both groups and could signify (the start of) active self-management in oBT. Also, only oBT improved migraine-specific quality of life to a sizable extent. oBT produced self-management gains but could not account for improved attack frequency, because WLC improved as well. The perspective that BT effects develop gradually, and that online delivery will boost BT outreach, justifies further research. © International Headache Society 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.
Impact of multifamily psychoeducational psychotherapy in treating children aged 8 to 12 years with mood disorders.

PubMed

Fristad, Mary A; Verducci, Joseph S; Walters, Kimberly; Young, Matthew E

2009-09-01

Childhood mood disorders lack sufficient evidence-based treatments. While psychosocial treatments are recommended for both childhood depression and bipolar disorder, empirical support is scarce. To determine whether adjunctive multifamily psychoeducational psychotherapy would improve outcome for children aged 8 to 12 years with depression or bipolar disorder. One hundred sixty-five children were studied in a randomized controlled trial of multifamily psychoeducational psychotherapy plus treatment as usual (n = 78) compared with a wait-list control (WLC) condition plus treatment as usual (n = 87). Assessments occurred at baseline and at 6, 12, and 18 months. Intervention occurred between baseline and 6 months for the immediate treatment group and between 12 and 18 months for the WLC group. University medical center. Children were recruited from mental health and physical health care providers, media contacts, and word of mouth. All had a major mood disorder (major depressive disorder or dysthymic disorder, 30%; bipolar disorder type I, type II, or not otherwise specified, 70%). Intervention Children and 1 or more parents participated in eight 90-minute multifamily psychoeducational psychotherapy sessions. Parent and child groups met separately but began and ended sessions together. The Mood Severity Index (MSI) combines Mania Rating Scale and Children's Depression Rating Scale-Revised scores. Multifamily psychoeducational psychotherapy plus treatment as usual was associated with lower MSI scores at follow-up in intent-to-treat analyses compared with WLC plus treatment as usual (MSI: chi(2)(1) = 4.55; P = .03). The WLC group showed a similar decrease in MSI scores 1 year later, when also following their treatment (MSI decrease = 3.24 units per 6 months in the immediate treatment group and 3.50 units per 6 months in the WLC group). Brief, adjunctive psychoeducational group psychotherapy is associated with improved outcome for children aged 8 to 12 years with major mood disorders. Trial Registration clinicaltrials.gov Identifier: NCT00050557.
Evaluation of a specialized yoga program for persons with a spinal cord injury: a pilot randomized controlled trial

PubMed Central

Curtis, Kathryn; Hitzig, Sander L; Bechsgaard, Gitte; Stoliker, Candice; Alton, Charlene; Saunders, Nicole; Leong, Nicole; Katz, Joel

2017-01-01

Objectives The purpose of this randomized controlled trial was to evaluate the effects of a specialized yoga program for individuals with a spinal cord injury (SCI) on pain, psychological, and mindfulness variables. Materials and methods Participants with SCI (n=23) were outpatients or community members affiliated with a rehabilitation hospital. Participants were randomized to an Iyengar yoga (IY; n=11) group or to a 6-week wait-list control (WLC; n=12) group. The IY group participated in a twice-weekly 6-week seated IY program; the WLC group participated in the same yoga program, after the IY group’s yoga program had ended. Pain, psychological, and mindfulness measures were collected at two time points for both groups (within 1–2 weeks before and after program 1 and at a third time point for the WLC group (within 1 week after program 2). Results Linear mixed-effect growth models were conducted to evaluate the main effects of group at T2 (postintervention), controlling for T1 (preintervention) scores. T2 depression scores were lower (F1,18=6.1, P<0.05) and T2 self-compassion scores higher (F1,18=6.57, P< 0.05) in the IY group compared to the WLC group. To increase sample size and power, the two groups were combined and analyzed across time by comparing pre- and postintervention scores. Main effects of time were found for depression scores, (F1,14.83=6.62, P<0.05), self-compassion, (F1,16.6=4.49, P<0.05), mindfulness (F1,16.79=5.42, P<0.05), mindful observing (F1,19.82=5.06, P<0.05), and mindful nonreactivity, (F1,16.53=4.92, P<0.05), all showing improvement after the intervention. Discussion The results indicated that a specialized 6-week yoga intervention reduced depressive symptoms and increased self-compassion in individuals with SCI, and may also have fostered greater mindfulness. PMID:28496356
Persistence length changes dramatically as RNA folds.

PubMed

Caliskan, G; Hyeon, C; Perez-Salas, U; Briber, R M; Woodson, S A; Thirumalai, D

2005-12-31

We determine the persistence length l(p) for a bacterial group I ribozyme as a function of concentration of monovalent and divalent cations by fitting the distance distribution functions P(r) obtained from small angle x-ray scattering intensity data to the asymptotic form of the calculated P(WLC)(r) for a wormlike chain. The l(p) values change dramatically over a narrow range of Mg(2+) concentration from approximately 21 Angstroms in the unfolded state (U) to approximately 10 Angstroms in the compact (I(C)) and native states. Variations in l(p) with increasing Na(+) concentration are more gradual. In accord with the predictions of polyelectrolyte theory we find l(p) alpha 1/kappa(2) where kappa is the inverse Debye-screening length.
[Influence Additional Cognitive Tasks on EEG Beta Rhythm Parameters during Forming and Testing Set to Perception of the Facial Expression].

PubMed

Yakovenko, I A; Cheremushkin, E A; Kozlov, M K

2015-01-01

The research of changes of a beta rhythm parameters on condition of working memory loading by extension of a interstimuli interval between the target and triggering stimuli to 16 sec is investigated on 70 healthy adults in two series of experiments with set to a facial expression. In the second series at the middle of this interval for strengthening of the load was entered the additional cognitive task in the form of conditioning stimuli like Go/NoGo--circles of blue or green color. Data analysis of the research was carried out by means of continuous wavelet-transformation on the basis of "mather" complex Morlet-wavelet in the range of 1-35 Hz. Beta rhythm power was characterized by the mean level, maxima of wavelet-transformation coefficient (WLC) and latent periods of maxima. Introduction of additional cognitive task to pause between the target and triggering stimuli led to essential increase in absolute values of the mean level of beta rhythm WLC and relative sizes of maxima of beta rhythm WLC. In the series of experiments without conditioning stimulus subjects with large number of mistakes (from 6 to 40), i.e. rigid set, in comparison with subjects with small number of mistakes (to 5), i.e. plastic set, at the forming stage were characterized by higher values of the mean level of beta rhythm WLC. Introduction of the conditioning stimuli led to smoothing of intergroup distinctions throughout the experiment.
Influence of surface interactions on folding and forced unbinding of semiflexible chains.

PubMed

Barsegov, V; Thirumalai, D

2005-11-24

We have investigated the folding and forced unbinding transitions of adsorbed semiflexible polymer chains using theory and simulations. These processes describe, at an elementary level, a number of biologically relevant phenomena that include adhesive interactions between proteins and tethering of receptors to cell walls. The binding interface is modeled as a solid surface, and the wormlike chain (WLC) is used for the semiflexible chain (SC). Using Langevin simulations, in the overdamped limit we examine the ordering kinetics of racquet-like and toroidal structures in the presence of an attractive interaction between the surface and the polymer chain. For a range of interactions, temperature, and the persistence length, l(p), we obtained the monomer density distribution, n(x), (x is the perpendicular distance of a tagged chain end from the surface) for all of the relevant morphologies. There is a single peak in n(x) inside the range of attractive forces, b, for chains in the extended conformations, whereas in racquet and toroidal structures there is an additional peak at x approximately b. The simulated results for n(x) are in good agreement with theory. The formation of toroids on the surface appears to be a first-order transition as evidenced by the bimodal distribution in n(x). The theoretical result underestimates the simulated n(x) for x < b and follows n(x) closely for x >/= b; the calculated density agrees exactly with n(x) in the range x < b. The chain-surface interaction is probed by subjecting the surface structures to a pulling force, f. The average extension, x( f), as a function of f exhibits a sigmoidal profile with sharp all-or-none transition at the unfolding force threshold f = f(c) which increases for more structured states. Simulated x(f) compare well with the theoretical predictions. The critical force, f(c), is a function of l(s)/l(c) for a fixed temperature, where l(c) and l(s) are the length scales that express the strength of the intramolecular and SC-surface attraction, respectively. For a fixed l(s), f(c) increases as l(p) decreases.

Multimodal, 3D pathology-mimicking bladder phantom for evaluation of cystoscopic technologies (Conference Presentation)

NASA Astrophysics Data System (ADS)

Smith, Gennifer T.; Lurie, Kristen L.; Zlatev, Dimitar V.; Liao, Joseph C.; Ellerbee, Audrey K.

2016-02-01

Optical coherence tomography (OCT) and blue light cystoscopy (BLC) have shown significant potential as complementary technologies to traditional white light cystoscopy (WLC) for early bladder cancer detection. Three-dimensional (3D) organ-mimicking phantoms provide realistic imaging environments for testing new technology designs, the diagnostic potential of systems, and novel image processing algorithms prior to validation in real tissue. Importantly, the phantom should mimic features of healthy and diseased tissue as they appear under WLC, BLC, and OCT, which are sensitive to tissue color and structure, fluorescent contrast, and optical scattering of subsurface layers, respectively. We present a phantom posing the hollow shape of the bladder and fabricated using a combination of 3D-printing and spray-coating with Dragon Skin (DS) (Smooth-On Inc.), a highly elastic polymer to mimic the layered structure of the bladder. Optical scattering of DS was tuned by addition of titanium dioxide, resulting in scattering coefficients sufficient to cover the human bladder range (0.49 to 2.0 mm^-1). Mucosal vasculature and tissue coloration were mimicked with elastic cord and red dye, respectively. Urethral access was provided through a small hole excised from the base of the phantom. Inserted features of bladder pathology included altered tissue color (WLC), fluorescence emission (BLC), and variations in layered structure (OCT). The phantom surface and underlying material were assessed on the basis of elasticity, optical scattering, layer thicknesses, and qualitative image appearance. WLC, BLC, and OCT images of normal and cancerous features in the phantom qualitatively matched corresponding images from human bladders.
Real time diagnosis of bladder cancer with probe-based confocal laser endomicroscopy

NASA Astrophysics Data System (ADS)

Liu, Jen-Jane; Wu, Katherine; Adams, Winifred; Hsiao, Shelly T.; Mach, Kathleen E.; Beck, Andrew H.; Jensen, Kristin C.; Liao, Joseph C.

2011-02-01

Probe-based confocal laser endomicroscopy (pCLE) is an emerging technology for in vivo optical imaging of the urinary tract. Particularly for bladder cancer, real time optical biopsy of suspected lesions will likely lead to improved management of bladder cancer. With pCLE, micron scale resolution is achieved with sterilizable imaging probes (1.4 or 2.6 mm diameter), which are compatible with standard cystoscopes and resectoscopes. Based on our initial experience to date (n = 66 patients), we have demonstrated the safety profile of intravesical fluorescein administration and established objective diagnostic criteria to differentiate between normal, benign, and neoplastic urothelium. Confocal images of normal bladder showed organized layers of umbrella cells, intermediate cells, and lamina propria. Low grade bladder cancer is characterized by densely packed monomorphic cells with central fibrovascular cores, whereas high grade cancer consists of highly disorganized microarchitecture and pleomorphic cells with indistinct cell borders. Currently, we are conducting a diagnostic accuracy study of pCLE for bladder cancer diagnosis. Patients scheduled to undergo transurethral resection of bladder tumor are recruited. Patients undergo first white light cystocopy (WLC), followed by pCLE, and finally histologic confirmation of the resected tissues. The diagnostic accuracy is determined both in real time by the operative surgeon and offline after additional image processing. Using histology as the standard, the sensitivity, specificity, positive and negative predictive value of WLC and WLC + pCLE are calculated. With additional validation, pCLE may prove to be a valuable adjunct to WLC for real time diagnosis of bladder cancer.
Distribution of Native Lactic Acid Bacteria in Wineries of Queretaro, Mexico and Their Resistance to Wine-Like Conditions

PubMed Central

Miranda-Castilleja, Dalia E.; Martínez-Peniche, Ramón Álvar; Aldrete-Tapia, J. A.; Soto-Muñoz, Lourdes; Iturriaga, Montserrat H.; Pacheco-Aguilar, J. R.; Arvizu-Medrano, Sofía M.

2016-01-01

Native lactic acid bacteria (LAB) are capable of growing during winemaking, thereby strongly affecting wine quality. The species of LAB present in musts, wines during malolactic fermentation (MLF), and barrels/filters were investigated in wineries from the emerging wine region of Queretaro, México using multiplex PCR and culture. The resistance to wine-like conditions (WLC): ethanol (10, 12, and 13%), SO2 (30 mg⋅l-1), and low pH (3.5) of native LAB strains was also studied. Five species were detected within 61 samples obtained: Oenococcus oeni, Lactobacillus plantarum, Pediococcus parvulus, Lactobacillus hilgardi, and Lactobacillus brevis. Four species (excepting L. brevis) were found in must; O. oeni and P. parvulus were ubiquitous in wine and L. plantarum and L. brevis were mainly present at the initial stage of MLF, while L. hilgardii was mostly detected at the advanced stage. Furthermore, some species detected in barrel/filter, prove them to be hazardous reservoirs. From 822 LAB isolates, only 119 resisted WLC with 10% ethanol; the number of strains able to grow in WLC with 13% ethanol decreased approximately by 50%, O. oeni being the most versatile species with 65% of resistant isolates, while Lactobacillus spp. and P. parvulus were the most strongly affected, especially those recovered from barrel/filter, with less than 10% of resistant isolates. This study evidences the presence of local strains able to be used as starter cultures, and also enabled the assessment of the risks derived from the presence of spoilage LAB strains resistant to WLC. PMID:27877164
Multisite Randomized Controlled Trial to Compare Two Methods of Tinnitus Intervention to Two Control Conditions.

PubMed

Henry, James A; Stewart, Barbara J; Griest, Susan; Kaelin, Christine; Zaugg, Tara L; Carlson, Kathleen

In this four-site clinical trial, we evaluated whether tinnitus masking (TM) and tinnitus retraining therapy (TRT) decreased tinnitus severity more than the two control groups: an attention-control group that received tinnitus educational counseling (and hearing aids if needed; TED), and a 6-month-wait-list control (WLC) group. The authors hypothesized that, over the first 6 months of treatment, TM and TRT would decrease tinnitus severity in Veterans relative to TED and WLC, and that TED would decrease tinnitus severity relative to WLC. The authors also hypothesized that, over 18 months of treatment, TM and TRT would decrease tinnitus severity relative to TED. Treatment effectiveness was hypothesized not to be different across the four sites. Across four Veterans affairs medical center sites, N = 148 qualifying Veterans who experienced sufficiently bothersome tinnitus were randomized into one of the four groups. The 115 Veterans assigned to TM (n = 42), TRT (n = 34), and TED (n = 39) were considered immediate-treatment subjects; they received comparable time and attention from audiologists. The 33 Veterans assigned to WLC were, after 6 months, randomized to receive delayed treatment in TM, TRT, or TED. Assessment of outcomes took place using the Tinnitus Handicap Inventory (THI) at 0, 3, 6, 12, and 18 months. Results of a repeated measures analysis of variance using an intention-to-treat approach showed that the tinnitus severity of Veterans receiving TM, TRT, and TED significantly decreased (p < 0.05) relative to Veterans in the WLC group at 3 months (effect sizes = 0.44, 0.52, and 0.27, respectively) and at 6 months (effect sizes = 0.52, 0.56, and 0.40, respectively). Analyses comparing effectiveness of TM, TRT, and TED over 18 months revealed that the three conditions were not significantly different, but that tinnitus severity in the combined groups significantly decreased (p < 0.01) from baseline to 3 months (5.6 THI points) and from 3 to 6 months (3.7 THI points). With respect to clinically significant change, about half of Veterans who received TM (55%), TRT (59%), or TED (46%) showed strong or modest improvement on the THI by 18 months. Without treatment, the WLC group did not show significant change. Treatment effectiveness did not differ by study site. Audiologists who provided interventions to Veterans with bothersome tinnitus in the regular clinic setting were able to significantly reduce tinnitus severity over 18 months using TM, TRT, and TED approaches. These results suggest that TM, TRT, and TED, when implemented as in this trial, will provide effectiveness that is relatively similar by 6 months and beyond.
Cost-effectiveness of cognitive behavioral therapy and physical exercise for alleviating treatment-induced menopausal symptoms in breast cancer patients.

PubMed

Mewes, Janne C; Steuten, Lotte M G; Duijts, Saskia F A; Oldenburg, Hester S A; van Beurden, Marc; Stuiver, Martijn M; Hunter, Myra S; Kieffer, Jacobien M; van Harten, Wim H; Aaronson, Neil K

2015-03-01

Many breast cancer patients experience (severe) menopausal symptoms after an early onset of menopause caused by cancer treatment. The aim of this study was to assess the cost-effectiveness of cognitive behavioral therapy (CBT) and physical exercise (PE), compared to a waiting list control group (WLC). We performed a cost-effectiveness analysis from a healthcare system perspective, using a Markov model. Effectiveness data came from a recent randomized controlled trial that evaluated the efficacy of CBT and PE. Cost data were obtained from relevant Dutch sources. Outcome measures were incremental treatment costs (ITCs) per patient with a clinically relevant improvement on a measure of endocrine symptoms, the Functional Assessment of Cancer Therapy questionnaire (FACT-ES), and on a measure of hot flushes, the Hot Flush Rating Scale (HFRS), and costs per quality-adjusted life years (QALY) gained over a 5-year time period. ITCs for achieving a clinically relevant decline on the FACT-ES for one patient were €1,051 for CBT and €1,315 for PE, compared to the WLC. The corresponding value for the HFRS was €1,067 for CBT, while PE was not more effective than the WLC. Incremental cost-utility ratios were €22,502/QALY for CBT and €28,078/QALY for PE. CBT is likely the most cost-effective strategy for alleviating treatment-induced menopausal symptoms in this population, followed by PE. The outcomes are sensitive to a reduction of the assumed duration of the treatment effect from 5 to 3 and 1.5 years. Patients can be prescribed CBT or, based on individual preferences, PE.
Realization of a gain with electromagnetically induced transparency system using non-degenerate Zeeman sublevels in 87 Rb

NASA Astrophysics Data System (ADS)

Zhou, Minchuan; Zhou, Zifan; Shahriar, Selim M.

2017-11-01

Previously, we had proposed an optically-pumped five-level Gain EIT (GEIT) system, which has a transparency dip superimposed on a gain profile and exhibits a negative dispersion suitable for the white-light-cavity signal-recycling (WLC-SR) scheme of the interferometric gravitational wave detector (Zhou et al., 2015). Using this system as the negative dispersion medium (NDM) in the WLC-SR, we get an enhancement in the quantum noise (QN) limited sensitivity-bandwidth product by a factor of ∼ 18. Here, we show how to realize this GEIT system in a realistic platform, using non-degenerate Zeeman sublevels in cold Rb atoms, employing anomalous dispersion at 795 nm. Using the Caves model for a phase insensitive linear amplifier, we show that an enhancement of the sensitivity-bandwidth product by a factor of ∼ 17 is possible for potentially realizable experimental parameters. While the current LIGO apparatus uses light at 1064 nm, a future embodiment thereof may operate at a wavelength that is consistent with the wavelength considered here.
Semiflexible polymer dynamics with a bead-spring model

NASA Astrophysics Data System (ADS)

Barkema, Gerard T.; Panja, Debabrata; van Leeuwen, J. M. J.

2014-11-01

We study the dynamical properties of semiflexible polymers with a recently introduced bead-spring model. We focus on double-stranded DNA (dsDNA). The two parameters of the model, T* and ν, are chosen to match its experimental force-extension curve. In comparison to its groundstate value, the bead-spring Hamiltonian is approximated in the first order by the Hessian that is quadratic in the bead positions. The eigenmodes of the Hessian provide the longitudinal (stretching) and transverse (bending) eigenmodes of the polymer, and the corresponding eigenvalues match well with the established phenomenology of semiflexible polymers. At the Hessian approximation of the Hamiltonian, the polymer dynamics is linear. Using the longitudinal and transverse eigenmodes, for the linearized problem, we obtain analytical expressions of (i) the autocorrelation function of the end-to-end vector, (ii) the autocorrelation function of a bond (i.e. a spring, or a tangent) vector at the middle of the chain, and (iii) the mean-square displacement of a tagged bead in the middle of the chain, as the sum over the contributions from the modes—the so-called ‘mode sums’. We also perform simulations with the full dynamics of the model. The simulations yield numerical values of the correlations functions (i-iii) that agree very well with the analytical expressions for the linearized dynamics. This does not however mean that the nonlinearities are not present. In fact, we also study the mean-square displacement of the longitudinal component of the end-to-end vector that showcases strong nonlinear effects in the polymer dynamics, and we identify at least an effective t7/8 power-law regime in its time-dependence. Nevertheless, in comparison to the full mean-square displacement of the end-to-end vector the nonlinear effects remain small at all times—it is in this sense we state that our results demonstrate that the linearized dynamics suffices for dsDNA fragments that are shorter than or comparable to the persistence length. Our results are consistent with those of the wormlike chain (WLC) model, the commonly used descriptive tool of semiflexible polymers.
Synchronization of heteroclinic circuits through learning in coupled neural networks

NASA Astrophysics Data System (ADS)

Selskii, Anton; Makarov, Valeri A.

2016-01-01

The synchronization of oscillatory activity in neural networks is usually implemented by coupling the state variables describing neuronal dynamics. Here we study another, but complementary mechanism based on a learning process with memory. A driver network, acting as a teacher, exhibits winner-less competition (WLC) dynamics, while a driven network, a learner, tunes its internal couplings according to the oscillations observed in the teacher. We show that under appropriate training the learner can "copy" the coupling structure and thus synchronize oscillations with the teacher. The replication of the WLC dynamics occurs for intermediate memory lengths only, consequently, the learner network exhibits a phenomenon of learning resonance.
Siting MSW landfill using weighted linear combination and analytical hierarchy process (AHP) methodology in GIS environment (case study: Karaj).

PubMed

Moeinaddini, Mazaher; Khorasani, Nematollah; Danehkar, Afshin; Darvishsefat, Ali Asghar; Zienalyan, Mehdi

2010-05-01

Selection of landfill site is a complex process and needs many diverse criteria. The purpose of this paper is to evaluate the suitability of the studied site as landfill for MSW in Karaj. Using weighted linear combination (WLC) method and spatial cluster analysis (SCA), suitable sites for allocation of landfill for a 20-year period were identified. For analyzing spatial auto-correlation of the land suitability map layer (LSML), Maron's I was used. Finally, using the analytical hierarchy process (AHP), the most preferred alternative for the landfill siting was identified. Main advantages of AHP are: relative ease of handling multiple criteria, easy to understand and effective handling of both qualitative and quantitative data. As a result, 6% of the study area is suitable for landfill siting and third alternative was identified as the most preferred for siting MSW landfill by AHP. The ranking of alternatives were obtained only by applying the WLC approach showed different results from the AHP. The WLC should be used only for the identification of alternatives and the AHP is used for prioritization. We suggest the employed procedure for other similar regions. Copyright (c) 2010 Elsevier Ltd. All rights reserved.
Getting better byte by byte: a pilot randomised controlled trial of email therapy for bulimia nervosa and binge eating disorder.

PubMed

Robinson, Paul; Serfaty, Marc

2008-03-01

One hundred and ten people in an university population responded to emailed eating disorder questionnaires. Ninty-seven fulfilling criteria for eating disorders (bulimia nervosa (BN), binge eating disorder (BED), EDNOS) were randomised to therapist administered email bulimia therapy (eBT), unsupported Self directed writing (SDW) or Waiting list control (WLC). Measures were repeated at 3 months. Diagnosis, Beck depression inventory (BDI) and Bulimia investigatory test (BITE) scores were recorded. Follow-up rate was 63% and results must be interpreted cautiously. However significantly fewer participants who had received eBT or SDW fulfilled criteria for eating disorders at follow up compared to WLC. There was no significant difference between eBT and SDW in the analysis of variance (ANOVA), although in separate analyses, eBT was significantly superior to WLC (p < 0.02) and the difference for SDW approached significance (p = 0.06). BDI and BITE scores showed no significant change. For eBT participants there was a significant positive correlation between words written and improvement in BITE severity score. BN, BED and EDNOS can be treated via email. (c) 2007 John Wiley & Sons, Ltd and Eating Disorders Association
Use of the 'patient journey' model in the internet-based pre-fitting counseling of a person with hearing disability: study protocol for a randomized controlled trial.

PubMed

Manchaiah, Vinaya K C; Stephens, Dafydd; Andersson, Gerhard; Rönnberg, Jerker; Lunner, Thomas

2013-01-24

Hearing impairment is one of the most frequent chronic conditions. Persons with a hearing impairment (PHI) have various experiences during their 'journey' through hearing loss. In our previous studies we have developed a 'patient journey' model of PHI and their communication partners (CPs). We suggest this model could be useful in internet-based pre-fitting counseling of a person with hearing disability (PHD). A randomized controlled trial (RCT) with waiting list control (WLC) design will be used in this study. One hundred and fifty eight participants with self-reported hearing disability (that is, score > 20 in the Hearing Handicap Questionnaire (HHQ)) will be recruited to participate in this study. They will be assigned to one of two groups (79 participants in each group): (1) Information and counseling provision using the 'patient journey' model; and (2) WLC. They will participate in a 30 day (4 weeks) internet-based counseling program based on the 'patient journey' model. Various outcome measures which focuses on hearing disability, depression and anxiety, readiness to change and acceptance of hearing disability will be administered pre (one week before) and post (one week and six months after) intervention to evaluate the effectiveness of counseling. Internet-based counseling is being introduced as a viable option for audiological rehabilitation. We predict that the 'patient journey' model will have several advantages during counseling of a PHD. Such a program, if proven effective, could yield cost and time-efficient ways of managing hearing disability. ClinicalTrials.gov Protocol Registration System NCT01611129.
An elasto-viscoplastic interface model for investigating the constitutive behavior of nacre

NASA Astrophysics Data System (ADS)

Tang, H.; Barthelat, F.; Espinosa, H. D.

2007-07-01

In order to better understand the strengthening mechanism observed in nacre, we have developed an interface computational model to simulate the behavior of the organic present at the interface between aragonite tablets. In the model, the single polymer-chain behavior is characterized by the worm-like-chain (WLC) model, which is in turn incorporated into the eight-chain cell model developed by Arruda and Boyce [Arruda, E.M., Boyce, M.C., 1993a. A three-dimensional constitutive model for the large stretches, with application to polymeric glasses. Int. J. Solids Struct. 40, 389-412] to achieve a continuum interface constitutive description. The interface model is formulated within a finite-deformation framework. A fully implicit time-integration algorithm is used for solving the discretized governing equations. Finite element simulations were performed on a representative volume element (RVE) to investigate the tensile response of nacre. The staggered arrangement of tablets and interface waviness obtained experimentally by Barthelat et al. [Barthelat, F., Tang, H., Zavattieri, P.D., Li, C.-M., Espinosa, H.D., 2007. On the mechanics of mother-of-pearl: a key feature in the material hierarchical structure. J. Mech. Phys. Solids 55 (2), 306-337] was included in the RVE simulations. The simulations showed that both the rate-dependence of the tensile response and hysteresis loops during loading, unloading and reloading cycles were captured by the model. Through a parametric study, the effect of the polymer constitutive response during tablet-climbing and its relation to interface hardening was investigated. It is shown that stiffening of the organic material is not required to achieve the experimentally observed strain hardening of nacre during tension. In fact, when ratios of contour length/persistent length experimentally identified are employed in the simulations, the predicted stress-strain behavior exhibits a deformation hardening consistent with the one measured experimentally and also captured by the phenomenological cohesive model used in the study carried out by Barthelat et al. [Barthelat, F., Tang, H., Zavattieri, P.D., Li, C.-M., Espinosa, H.D., 2007. On the mechanics of mother-of-pearl: a key feature in the material hierarchical structure. J. Mech. Phys. Solids 55 (2), 306-337]. The simulation results also reveal that the bulk modulus of the polymer controls the rate of hardening, feature not captured by more simple cohesive laws.
Atomic force microscopy studies of human rhinovirus topology and molecular forces.

PubMed

Kienberger, Ferry; Zhu, Rong; Rankl, Christian; Gruber, Hermann J; Blaas, Dieter; Hinterdorfer, Peter

2010-01-01

Dynamic force microscopy (DFM) allows for imaging of the structure and assessment of the function of biological specimens in their physiological environment. In DFM, the cantilever is oscillated at a given frequency and touches the sample only at the end of its downward movement. Accordingly, the problem of lateral forces displacing or even destroying biomolecules is virtually inexistent as the contact time and friction forces are greatly reduced. Here, we describe the use of DFM in studies of human rhinovirus serotype 2 (HRV2). The capsid of HRV2 was reproducibly imaged without any displacement of the virus. Release of the genomic RNA from the virions was initiated by exposure to low-pH buffer and snapshots of the extrusion process were obtained. DFM of the single-stranded RNA genome of an HRV showed loops protruding from a condensed RNA core, 20-50 nm in height. The mechanical rigidity of the RNA was determined by single molecule pulling experiments. From fitting RNA stretching curves to the worm-like-chain (WLC) model a persistence length of 1.0+/-0.17 nm was obtained. Copyright (c) 2010 Elsevier Inc. All rights reserved.
Work–Life Imbalance and Musculoskeletal Disorders among South Korean Workers

PubMed Central

Kim, Young-Mee

2017-01-01

Employed workers often have family responsibilities such as childcare or homemaking. This dual burden may increase work-related health problems, particularly if there are conflicts between work and family responsibilities. This study assessed whether difficulty in work–life balance is associated with musculoskeletal disorders (MSD) among Korean employees. Data from the population-based Korean Working Conditions Survey of 2011, including 28,640 male and 21,392 female workers, were used. Men and women were analyzed separately to investigate gender differences. MSD were defined as pain in the back, neck, shoulder, or extremities during the past year. Self-assessed difficulty in work–life balance was defined as a work–life conflict (WLC). Adjustments for physical factors, as well as other occupational and socio-demographic variables, were made using multiple logistic regression analysis. Interaction terms including WLCs and key covariates were also incorporated. WLC was significantly associated with increased frequency of MSD in both men (OR: 1.49) and women (OR: 1.50). There were significant interaction effects between WLC and some key covariates (job stress for men and job stress, work hours, physical demand, and frequent overtime work for women). We suggest that having the flexibility to coordinate work and family life is important to prevent MSD among employees. PMID:29104228
Three RNases in Senescent and Nonsenescent Wheat Leaves 1

PubMed Central

Blank, A.; McKeon, Thomas A.

1991-01-01

We have described three RNases in wheat leaves (Triticum aestivum L. cv Chinese Spring) and developed assays for measuring each RNase individually in crude leaf extracts. We initially used activity staining in sodium dodecyl sulfate-polyacrylamide gels to characterize RNases in extracts of primary and flag leaves. We thus identified acid RNase (EC 3.1.27.1, here designated RNase WLA), and two apparently novel enzymes, designated RNases WLB and WLC. RNase WLB activity displays a distinctive isozyme pattern, a molecular mass of 26 kilodaltons (major species), a broad pH range with an optimum near neutrality, insensitivity to EDTA, and stimulation by moderate concentrations of KCl and by MgCl2. RNase WLC activity exhibits a molecular mass of 27 kilodaltons, a neutral pH optimum, insensitivity to EDTA, and inhibition by KCl, MgCl2, and tri-(hydroxymethyl)aminomethane. Based on distinctive catalytic properties established in gels, we designed conventional solution assays for selective quantitation of each RNase activity. We used the assays to monitor the individual RNases after gel filtration chromatography and native gel electrophoresis of extracts. In accompanying work, we used the assays to monitor RNases WLA, WLB, and WLC, which are present in senescent and nonsenescent leaves, during the course of leaf senescence. ImagesFigure 1Figure 3Figure 4 PMID:16668563
Work-Life Imbalance and Musculoskeletal Disorders among South Korean Workers.

PubMed

Kim, Young-Mee; Cho, Sung-Il

2017-11-01

Employed workers often have family responsibilities such as childcare or homemaking. This dual burden may increase work-related health problems, particularly if there are conflicts between work and family responsibilities. This study assessed whether difficulty in work-life balance is associated with musculoskeletal disorders (MSD) among Korean employees. Data from the population-based Korean Working Conditions Survey of 2011, including 28,640 male and 21,392 female workers, were used. Men and women were analyzed separately to investigate gender differences. MSD were defined as pain in the back, neck, shoulder, or extremities during the past year. Self-assessed difficulty in work-life balance was defined as a work-life conflict (WLC). Adjustments for physical factors, as well as other occupational and socio-demographic variables, were made using multiple logistic regression analysis. Interaction terms including WLCs and key covariates were also incorporated. WLC was significantly associated with increased frequency of MSD in both men (OR: 1.49) and women (OR: 1.50). There were significant interaction effects between WLC and some key covariates (job stress for men and job stress, work hours, physical demand, and frequent overtime work for women). We suggest that having the flexibility to coordinate work and family life is important to prevent MSD among employees.
Hexyl aminolevulinate-guided fluorescence cystoscopy in the diagnosis and follow-up of patients with non-muscle-invasive bladder cancer: a critical review of the current literature.

PubMed

Rink, Michael; Babjuk, Marko; Catto, James W F; Jichlinski, Patrice; Shariat, Shahrokh F; Stenzl, Arnulf; Stepp, Herbert; Zaak, Dirk; Witjes, J Alfred

2013-10-01

Controversy exists regarding the therapeutic benefit and cost effectiveness of photodynamic diagnosis (PDD) with 5-aminolevulinic acid (5-ALA) or hexyl aminolevulinate (HAL) in addition to white-light cystoscopy (WLC) in the management of non-muscle-invasive bladder cancer (NMIBC). To systematically evaluate evidence regarding the therapeutic benefits and economic considerations of PDD in NMIBC detection and treatment. We performed a critical review of PubMed/Medline, Embase, and the Cochrane Library in October 2012 according to the Preferred Reporting Items for Systematic Review and Meta-analysis (PRISMA) statement. Identified reports were reviewed according to the Consolidated Standards of Reporting Trials (CONSORT) and Standards for the Reporting of Diagnostic Accuracy Studies (STARD) criteria. Forty-four publications were selected for inclusion in this analysis. Included reports used 5-ALA (in 26 studies), HAL (15 studies), or both (three studies) as photosensitising agents. PDD increased the detection of both papillary tumours (by 7-29%) and flat carcinoma in situ (CIS; by 25-30%) and reduced the rate of residual tumours after transurethral resection of bladder tumour (TURBT; by an average of 20%) compared to WLC alone. Superior recurrence-free survival (RFS) rates and prolonged RFS intervals were reported for PDD, compared to WLC in most studies. PDD did not appear to reduce disease progression. Our findings are limited by tumour heterogeneity and a lack of NMIBC risk stratification in many reports or adjustment for intravesical therapy use in most studies. Although cost effectiveness has been demonstrated for 5-ALA, it has not been studied for HAL. Moderately strong evidence exists that PDD improves tumour detection and reduces residual disease after TURBT compared with WLC. This has been shown to improve RFS but not progression to more advanced disease. Further work to evaluate cost effectiveness of PDD is required. Copyright © 2013 European Association of Urology. Published by Elsevier B.V. All rights reserved.
Effects of a stress management intervention on absenteeism and return to work--results from a randomized wait-list controlled trial.

PubMed

Willert, Morten Vejs; Thulstrup, Ane Marie; Bonde, Jens Peter

2011-05-01

High levels of work-related stress are associated with increased absenteeism from work and reduced work ability. In this study, we investigated the effects of a stress management intervention on absenteeism and return to work. We randomized 102 participants into either the intervention or wait-list control (WLC) group. The intervention group received the intervention in weeks 1-16 from baseline, and the WLC group received the intervention in weeks 17-32. Self-reported data on absenteeism (number of days full- or part-time absent from work within the previous three months) were obtained at 16, 32, and 48 weeks follow-up. Register-based data on long-term absence from work were drawn from the Danish public transfer payments (DREAM) database from baseline and 48 weeks onwards. The DREAM database contains weekly information on long-term sickness absence compensation. The threshold to enter DREAM is sick leave for two consecutive weeks. At follow-up in week 16, self-reported absenteeism in the intervention group [median 11 days (range 3-25)] was lower (P=0.02) than in the WLC group [median 45 days (range 19-60)], corresponding to a 29% [95% confidence interval (95% CI) 5-52] reduction. On register-based data (cumulated weeks in DREAM, weeks 1-16), the intervention group median [6 weeks (range 0-11)] was lower than that of the WLC group [median 12 weeks (range 8-16)], though not significantly (P=0.06), corresponding to a 21% (95% CI 0-42) reduction. For return to work, a hazard ratio of 1.58 (95% CI 0.89-2.81) favoring the intervention group was found (P=0.12). The intervention reduces self-reported absenteeism from work. A similar trend was found from register-based records. No conclusive evidence was found for return to work.
Use of the ‘patient journey’ model in the internet-based pre-fitting counseling of a person with hearing disability: study protocol for a randomized controlled trial

PubMed Central

2013-01-01

Background Hearing impairment is one of the most frequent chronic conditions. Persons with a hearing impairment (PHI) have various experiences during their ‘journey’ through hearing loss. In our previous studies we have developed a ‘patient journey’ model of PHI and their communication partners (CPs). We suggest this model could be useful in internet-based pre-fitting counseling of a person with hearing disability (PHD). Methods/Design A randomized controlled trial (RCT) with waiting list control (WLC) design will be used in this study. One hundred and fifty eight participants with self-reported hearing disability (that is, score >20 in the Hearing Handicap Questionnaire (HHQ)) will be recruited to participate in this study. They will be assigned to one of two groups (79 participants in each group): (1) Information and counseling provision using the ‘patient journey’ model; and (2) WLC. They will participate in a 30 day (4 weeks) internet-based counseling program based on the ‘patient journey’ model. Various outcome measures which focuses on hearing disability, depression and anxiety, readiness to change and acceptance of hearing disability will be administered pre (one week before) and post (one week and six months after) intervention to evaluate the effectiveness of counseling. Discussion Internet-based counseling is being introduced as a viable option for audiological rehabilitation. We predict that the ‘patient journey’ model will have several advantages during counseling of a PHD. Such a program, if proven effective, could yield cost and time-efficient ways of managing hearing disability. Trial registration ClinicalTrials.gov Protocol Registration System NCT01611129. PMID:23347711
Coupled microrings data buffer using fast light

NASA Astrophysics Data System (ADS)

Scheuer, Jacob; Shahriar, Selim

2013-03-01

We present a theoretical study of a trap-door optical buffer based on a coupled microrings add/drop filter (ADF) utilizing the white light cavity (WLC). The buffer "trap-door" can be opened and closed by tuning the resonances of the microrings comprising the ADF and trap/release optical pulses. We show that the WLC based ADF yields a maximally flat filter which exhibits superior performances in terms of bandwidth and flatness compared to previous design approaches. We also present a realistic, Silicon-over-Insulator based, design and performance analysis taking into consideration the realistic properties and limitations of the materials and the fabrication process, leading to delays exceeding 850ps for 80GHz bandwidth, and a corresponding delay-bandwidth product of approximately 70.

White light Z-scan measurements of ultrafast optical nonlinearity in reduced graphene oxide nanosheets in the 400–700 nm region

DOE Office of Scientific and Technical Information (OSTI.GOV)

Perumbilavil, Sreekanth; Sankar, Pranitha; Priya Rose, T.

Wavelength dispersion of optical power limiting is an important factor to be considered while designing potential optical limiters for laser safety applications. We report the observation of broadband, ultrafast optical limiting in reduced graphene oxide (rGO), measured by a single open aperture Z-scan using a white light continuum (WLC) source. WLC Z-scan is fast when the nonlinearity is to be measured over broad wavelength ranges, and it obviates the need for an ultrafast tunable laser making it cost-economic compared to conventional Z-scan. The nonlinearity arises from nondegenerate two-photon absorption, owing mostly to the crystallinity and extended π conjugation of rGO.
Randomized controlled trial of the effects of high intensity and low-to-moderate intensity exercise on physical fitness and fatigue in cancer survivors: results of the Resistance and Endurance exercise After ChemoTherapy (REACT) study.

PubMed

Kampshoff, Caroline S; Chinapaw, Mai J M; Brug, Johannes; Twisk, Jos W R; Schep, Goof; Nijziel, Marten R; van Mechelen, Willem; Buffart, Laurien M

2015-10-29

International evidence-based guidelines recommend physical exercise to form part of standard care for all cancer survivors. However, at present, the optimum exercise intensity is unclear. Therefore, we aimed to evaluate the effectiveness of a high intensity (HI) and low-to-moderate intensity (LMI) resistance and endurance exercise program compared with a wait list control (WLC) group on physical fitness and fatigue in a mixed group of cancer survivors who completed primary cancer treatment, including chemotherapy. Overall, 277 cancer survivors were randomized to 12 weeks of HI exercise (n = 91), LMI exercise (n = 95), or WLC (n = 91). Both interventions were identical with respect to exercise type, duration and frequency, and only differed in intensity. Measurements were performed at baseline (4-6 weeks after primary treatment) and post-intervention. The primary outcomes were cardiorespiratory fitness (peakVO2), muscle strength (grip strength and 30-second chair-stand test), and self-reported fatigue (Multidimensional Fatigue Inventory; MFI). Secondary outcomes included health-related quality of life, physical activity, daily functioning, body composition, mood, and sleep disturbances. Multilevel linear regression analyses were performed to estimate intervention effects using an intention-to-treat principle. In the HI and LMI groups, 74 % and 70 % of the participants attended more than 80 % of the prescribed exercise sessions, respectively (P = 0.53). HI (β = 2.2; 95 % CI, 1.2-3.1) and LMI (β = 1.3; 95 % CI, 0.3-2.3) exercise showed significantly larger improvements in peakVO2 compared to WLC. Improvements in peakVO2 were larger for HI than LMI exercise (β = 0.9; 95 % CI, -0.1 to 1.9), but the difference was not statistically significant (P = 0.08). No intervention effects were found for grip strength and the 30-second chair-stand test. HI and LMI exercise significantly reduced general and physical fatigue and reduced activity (MFI subscales) compared to WLC, with no significant differences between both interventions. Finally, compared to WLC, we found benefits in global quality of life and anxiety after HI exercise, improved physical functioning after HI and LMI exercise, and less problems at work after LMI exercise. Shortly after completion of cancer treatment, both HI and LMI exercise were safe and effective. There may be a dose-response relationship between exercise intensity and peakVO2, favoring HI exercise. HI and LMI exercise were equally effective in reducing general and physical fatigue. This study was registered at the Netherlands Trial Register [ NTR2153 ] on the 5th of January 2010.
NBI - plasma vaporization hybrid approach in bladder cancer endoscopic management.

PubMed

Stănescu, F; Geavlete, B; Georgescu, D; Jecu, M; Moldoveanu, C; Adou, L; Bulai, C; Ene, C; Geavlete, P

2014-06-15

A prospective study was performed aiming to evaluate the surgical efficacy, perioperative safety profile, diagnostic accuracy and medium term results of a multi-modal approach consisting in narrow band imaging (NBI) cystoscopy and bipolar plasma vaporization (BPV) when compared to the standard protocol represented by white light cystoscopy (WLC) and transurethral resection of bladder tumors (TURBT). A total of 260 patients with apparently at least one bladder tumor over 3 cm were included in the trial. In the first group, 130 patients underwent conventional and NBI cystoscopy followed by BPV, while in a similar number of cases of the second arm, classical WLC and TURBT were applied. In all non-muscle invasive bladder tumors' (NMIBT) pathologically confirmed cases, standard monopolar Re-TUR was performed at 4-6 weeks after the initial intervention, followed by one year' BCG immunotherapy. The follow-up protocol included abdominal ultrasound, urinary cytology and WLC, performed every 3 months for a period of 2 years. The obturator nerve stimulation, bladder wall perforation, mean hemoglobin level drop, postoperative bleeding, catheterization period and hospital stay were significantly reduced for the plasma vaporization technique by comparison to conventional resection. Concerning tumoral detection, the present data confirmed the NBI superiority when compared to standard WLC regardless of tumor stage (95.3% vs. 65.1% for CIS, 93.3% vs. 82.2% for pTa, 97.4% vs. 94% for pT1, 95% vs. 84.2% overall). During standard Re-TUR the overall (6.3% versus 17.4%) and primary site (3.6% versus 12.8%) residual tumors' rates were significantly lower for the NBI-BPV group. The 1 (7.2% versus 18.3%) and 2 (11.5% versus 25.8%) years' recurrence rates were substantially lower for the combined approach. NBI cystoscopy significantly improved diagnostic accuracy, while bipolar technology showed a higher surgical efficiency, lower morbidity and faster postoperative recovery. The combined technique offered a reduced rate of residual tumors at Re-TUR, both globally as well as for orthotopic tumors. Substantially lower recurrence rates were found at 1 and 2 years among the NBI-BPV cases.
Corongraphic Observations and Analyses of The Ultraviolet Solar Corona

NASA Technical Reports Server (NTRS)

Kohl, John L.

2000-01-01

The activities supported under NASA Grant NAG5-613 included the following: 1) reduction and scientific analysis of data from three sounding rocket flights of the Rocket Ultraviolet Coronagraph Spectrometer, 2) development of ultraviolet spectroscopic diagnostic techniques to provide a detailed empirical description of the extended solar corona, 3) extensive upgrade of the rocket instrument to become the Ultraviolet Coronal Spectrometer (UVCS) for Spartan 201,4) instrument scientific calibration and characterization, 5) observation planning and mission support for a series of five Spartan 201 missions (fully successful except for STS 87 where the Spartan spacecraft was not successfully deployed and the instruments were not activated), and 6) reduction and scientific analysis of the UVCS/Spartan 201 observational data. The Ultraviolet Coronal Spectrometer for Spartan 201 was one unit of a joint payload and the other unit was a White Light Coronagraph (WLC) provided by the High Altitude Observatory and the Goddard Space Flight Center. The two instruments were used in concert to determine plasma parameters describing structures in the extended solar corona. They provided data that could be used individually or jointly in scientific analyses. The WLC provided electron column densities in high spatial resolution and high time resolution. UVCS/Spartan provided hydrogen velocity distributions, and line of sight hydrogen velocities. The hydrogen intensities from UVCS together with the electron densities from WLC were used to determine hydrogen outflow velocities. The UVCS also provided O VI intensities which were used to develop diagnostics for velocity distributions and outflow velocities of minor ions.
Reductions in negative repetitive thinking and metacognitive beliefs during transdiagnostic internet cognitive behavioural therapy (iCBT) for mixed anxiety and depression.

PubMed

Newby, Jill M; Williams, Alishia D; Andrews, Gavin

2014-08-01

We explored whether transdiagnostic internet-delivered cognitive behavioural therapy (iCBT) for mixed anxiety and depression effectively reduces repetitive negative thinking (RNT), and whether reductions in RNT and positive metacognitive beliefs mediate symptom improvement during iCBT. Participants with generalized anxiety disorder (GAD), major depressive disorder (MDD), or mixed GAD/MDD diagnoses were randomly allocated to a 6-lesson clinician-guided iCBT anxiety and depression program (n = 46) or wait-list control (WLC, n = 53). Depression (PHQ-9), generalized anxiety (GAD-7), RNT (Repetitive Thinking Questionnaire) and positive beliefs about RNT (Positive Beliefs about Rumination Scale) were assessed at pre-, mid-, and post-treatment or matched time points for WLC. Tests of serial indirect effects explored the potential meditating role of RNT and positive belief reductions on the impact of iCBT on depression and anxiety symptoms post-treatment. Results showed that both RNT frequency and positive beliefs about the value of RNT reduced significantly following iCBT compared to WLC, with gains maintained at 3-month follow-up. Reductions between pre- and mid-treatment in positive beliefs and RNT mediated improvements in depression symptoms post-iCBT, and reductions in positive beliefs mediated improvements in GAD symptoms. These findings indicate that iCBT is an effective treatment for RNT and positive metacognitive beliefs. Future dismantling studies are needed to assess the most effective treatment components. Copyright © 2014 Elsevier Ltd. All rights reserved.
A Randomized Controlled Trial Evaluating a Manualized TeleCoaching Protocol for Improving Adherence to a Web-Based Intervention for the Treatment of Depression

PubMed Central

Mohr, David C.; Duffecy, Jenna; Ho, Joyce; Kwasny, Mary; Cai, Xuan; Burns, Michelle Nicole; Begale, Mark

2013-01-01

Background Web-based interventions for depression that are supported by coaching have generally produced larger effect-sizes, relative to standalone web-based interventions. This is likely due to the effect of coaching on adherence. We evaluated the efficacy of a manualized telephone coaching intervention (TeleCoach) aimed at improving adherence to a web-based intervention (moodManager), as well as the relationship between adherence and depressive symptom outcomes. Methods 101 patients with MDD, recruited from primary care, were randomized to 12 weeks moodManager+TeleCoach, 12 weeks of self-directed moodManager, or 6 weeks of a waitlist control (WLC). Depressive symptom severity was measured using the PHQ-9. Results TeleCoach+moodManager, compared to self-directed moodManager, resulted in significantly greater numbers of login days (p = 0.01), greater time until last use (p = 0.007), greater use of lessons (p = 0.03), greater variety of interactive tools used (p = 0.02), but total instances of tool use did not reach statistical significance. (p = 0.07). TeleCoach+moodManager produced significantly lower PHQ-9 scores relative to WLC at week 6 (p = 0.04), but there were no other significant differences in PHQ-9 scores at weeks 6 or 12 (ps>0.20) across treatment arms. Baseline PHQ-9 scores were no significantly related to adherence to moodManager. Conclusions TeleCoach produced significantly greater adherence to moodManager, relative to self-directed moodManager. TeleCoached moodManager produced greater reductions in depressive symptoms relative to WLC, however, there were no statistically significant differences relative to self-directed moodManager. While greater use was associated with better outcomes, most users in both TeleCoach and self-directed moodManager had dropped out of treatment by week 12. Even with telephone coaching, adherence to web-based interventions for depression remains a challenge. Methods of improving coaching models are discussed. Trial Registration Clinicaltrials.gov NCT00719979 PMID:23990896
Virtual reality cognitive behavior therapy for public speaking anxiety: a randomized clinical trial.

PubMed

Wallach, Helene S; Safir, Marilyn P; Bar-Zvi, Margalit

2009-05-01

Public speaking anxiety (PSA) is a common phobia. Although cognitive behavior therapy (CBT) is preferred, difficulties arise with the exposure component (lack of therapist control, patient's inability to imagine, self-flooding, loss of confidentiality resulting from public exposure). Virtual reality CBT (VRCBT) enables a high degree of therapist control, thus overcoming these difficulties. This study examined whether VRCBT is an alternative to CBT. Participants with PSA were randomly assigned to VRCBT (28 participants), CBT (30 participants), and wait list control (WLC; 30 participants). VRCBT and CBT were significantly more effective than WLC in anxiety reduction on four of five anxiety measures, and on subject's self-rating of anxiety during a behavioral task. No significant differences were found on observer ratings of the behavioral task. However, twice as many participants dropped out from CBT than from VRCBT. Our results demonstrated that VRCBT is an effective and brief treatment regimen, equal to CBT.
Parent training for Attention Deficit/Hyperactivity Disorder: is it as effective when delivered as routine rather than as specialist care?

PubMed

Sonuga-Barke, Edmund J S; Thompson, Margaret; Daley, David; Laver-Bradbury, Cathy

2004-11-01

The effectiveness of parent training (PT) when delivered as part of specialist tier-two services for preschool AD/HD children has been recently demonstrated. To assess the effectiveness of the same PT programme when delivered as part of routine primary care by non-specialist nurses. A sample of 89 3-year-old children with preschool AD/HD took part in a controlled trial of an eight-week (one hour a week), health visitor delivered, PT package. Children, allocated randomly to PT (n = 59) and waiting list control (WLC; n = 30) groups, were compared. PT did not reduce AD/HD symptoms. Maternal well-being decreased in both PT and WLC groups. While PT is an effective intervention for preschool AD/HD when delivered in specialized settings, these benefits do not appear to generalize when programme are delivered as part of routine primary care by non-specialist nurses.
A health economic outcome evaluation of an internet-based mobile-supported stress management intervention for employees.

PubMed

Ebert, David Daniel; Kählke, Fanny; Buntrock, Claudia; Berking, Matthias; Smit, Filip; Heber, Elena; Baumeister, Harald; Funk, Burkhardt; Riper, Heleen; Lehr, Dirk

2018-03-01

Objective This study aimed to estimate and evaluate the cost-effectiveness and cost-benefit of a guided internet- and mobile-supported occupational stress-management intervention (iSMI) for employees from the employer's perspective alongside a randomized controlled trial. Methods A sample of 264 employees with elevated symptoms of perceived stress (Perceived Stress Scale, PSS-10 ≥22) was randomly assigned either to the iSMI or a waitlist control (WLC) group with unrestricted access to treatment as usual. The iSMI consisted of seven sessions of problem-solving and emotion-regulation techniques and one booster session. Self-report data on symptoms of perceived stress and economic data were assessed at baseline, and at six months following randomization. A cost-benefit analysis (CBA) and a cost-effectiveness analysis (CEA) with symptom-free status as the main outcome from the employer's perspective was carried out. Statistical uncertainty was estimated using bootstrapping (N=5000). Results The CBA yielded a net-benefit of EUR181 [95% confidence interval (CI) -6043-1042] per participant within the first six months following randomization. CEA showed that at a willingness-to-pay ceiling of EUR0, EUR1000, EUR2000 for one additional symptom free employee yielded a 67%, 90%, and 98% probability, respectively, of the intervention being cost-effective compared to the WLC. Conclusion The iSMI was cost-effective when compared to WLC and even lead to cost savings within the first six months after randomization. Offering stress-management interventions can present good value for money in occupational healthcare.
Next generation of optical diagnostics for bladder cancer using probe-based confocal laser endomicroscopy

NASA Astrophysics Data System (ADS)

Liu, Jen-Jane; Chang, Timothy C.; Pan, Ying; Hsiao, Shelly T.; Mach, Kathleen E.; Jensen, Kristin C.; Liao, Joseph C.

2012-02-01

Real-time imaging with confocal laser endomicroscopy (CLE) probes that fit in standard endoscopes has emerged as a clinically feasible technology for optical biopsy of bladder cancer. Confocal images of normal, inflammatory, and neoplastic urothelium obtained with intravesical fluorescein can be differentiated by morphologic characteristics. We compiled a confocal atlas of the urinary tract using these diagnostic criteria to be used in a prospective diagnostic accuracy study. Patients scheduled to undergo transurethral resection of bladder tumor underwent white light cystoscopy (WLC), followed by CLE, and histologic confirmation of resected tissue. Areas that appeared normal by WLC were imaged and biopsied as controls. We imaged and prospectively analyzed 135 areas in 57 patients. We show that CLE improves the diagnostic accuracy of WLC for diagnosing benign tissue, low and high grade cancer. Interobserver studies showed a moderate level of agreement by urologists and nonclinical researchers. Despite morphologic differences between inflammation and cancer, real-time differentiation can still be challenging. Identification of bladder cancer-specific contrast agents could provide molecular specificity to CLE. By using fluorescently-labeled antibodies or peptides that bind to proteins expressed in bladder cancer, we have identified putative molecular contrast agents for targeted imaging with CLE. We describe one candidate agent - anti-CD47 - that was instilled into bladder specimens. The tumor and normal urothelium were imaged with CLE, with increased fluorescent signal demonstrated in areas of tumor compared to normal areas. Thus, cancer-specificity can be achieved using molecular contrast agents ex vivo in conjunction with CLE.
Changes in intrinsic local connectivity after reading intervention in children with autism.

PubMed

Maximo, Jose O; Murdaugh, Donna L; O'Kelley, Sarah; Kana, Rajesh K

2017-12-01

Most of the existing behavioral and cognitive intervention programs in autism spectrum disorders (ASD) have not been tested at the neurobiological level, thus falling short of finding quantifiable neurobiological changes underlying behavioral improvement. The current study takes a translational neuroimaging approach to test the impact of a structured visual imagery-based reading intervention on improving reading comprehension and assessing its underlying local neural circuitry. Behavioral and resting state functional MRI (rs-fMRI) data were collected from children with ASD who were randomly assigned to an Experimental group (ASD-EXP; n=14) and a Wait-list control group (ASD-WLC; n=14). Participants went through an established reading intervention training program (Visualizing and Verbalizing for language comprehension and thinking or V/V; 4-h per day, 10-weeks, 200h of face-to-face instruction). Local functional connectivity was examined using a connection density approach from graph theory focusing on brain areas considered part of the Reading Network. The main results are as follows: (I) the ASD-EXP group showed significant improvement, compared to the ASD-WLC group, in their reading comprehension ability evidenced from change in comprehension scores; (II) the ASD-EXP group showed increased local brain connectivity in Reading Network regions compared to the ASD-WLC group post-intervention; (III) intervention-related changes in local brain connectivity were observed in the ASD-EXP from pre to post-intervention; and (IV) improvement in language comprehension significantly predicted changes in local connectivity. The findings of this study provide novel insights into brain plasticity in children with developmental disorders using targeted intervention programs. Published by Elsevier Inc.
Reducing shame in a game that predicts HIV risk reduction for young adult MSM: a randomized trial delivered nationally over the Web.

PubMed

Christensen, John L; Miller, Lynn Carol; Appleby, Paul Robert; Corsbie-Massay, Charisse; Godoy, Carlos Gustavo; Marsella, Stacy C; Read, Stephen J

2013-11-13

Men who have sex with men (MSM) often face socially sanctioned disapproval of sexual deviance from the heterosexual "normal." Such sexual stigma can be internalized producing a painful affective state (i.e., shame). Although shame (e.g., addiction) can predict risk-taking (e.g., alcohol abuse), sexual shame's link to sexual risk-taking is unclear. Socially Optimized Learning in Virtual Environments (SOLVE) was designed to reduce MSM's sexual shame, but whether it does so, and if that reduction predicts HIV risk reduction, is unclear. To test if at baseline, MSM's reported past unprotected anal intercourse (UAI) is related to shame; MSM's exposure to SOLVE compared to a wait-list control (WLC) condition reduces MSM's shame; and shame-reduction mediates the link between WLC condition and UAI risk reduction. HIV-negative, self-identified African American, Latino or White MSM, aged 18-24 years, who had had UAI with a non-primary/casual partner in the past three months were recruited for a national online study. Eligible MSM were computer randomized to either WLC or a web-delivered SOLVE. Retained MSM completed baseline measures (e.g., UAI in the past three months; current level of shame) and, in the SOLVE group, viewed at least one level of the game. At the end of the first session, shame was measured again. MSM completed follow-up UAI measures three months later. All data from 921 retained MSM (WLC condition, 484; SOLVE condition, 437) were analyzed, with missing data multiply imputed. At baseline, MSM reporting more risky sexual behaviour reported more shame (r s=0.21; p<0.001). MSM in the SOLVE intervention reported more shame reduction (M=-0.08) than MSM in the control condition (M=0.07; t(919)=4.24; p<0.001). As predicted, the indirect effect was significant (point estimate -0.10, 95% bias-corrected CI [-0.01 to -0.23] such that participants in the SOLVE treatment condition reported greater reductions in shame, which in turn predicted reductions in risky sexual behaviour at follow-up. The direct effect, however, was not significant. SOLVE is the first intervention to: (1) significantly reduce shame for MSM; and (2) demonstrate that shame-reduction, due to an intervention, is predictive of risk (UAI) reduction over time.
DOE Office of Scientific and Technical Information (OSTI.GOV)

Ratto, T V; Rudd, R E; Langry, K C

We present evidence of multivalent interactions between a single protein molecule and multiple carbohydrates at a pH where the protein can bind four ligands. The evidence is based not only on measurements of the force required to rupture the bonds formed between ConcanavalinA (ConA) and {alpha}-D-mannose, but also on an analysis of the polymer-extension force curves to infer the polymer architecture that binds the protein to the cantilever and the ligands to the substrate. We find that although the rupture forces for multiple carbohydrate connections to a single protein are larger than the rupture force for a single connection, theymore » do not scale additively with increasing number. Specifically, the most common rupture forces are approximately 46, 66, and 85 pN, which we argue corresponds to 1, 2, and 3 ligands being pulled simultaneously from a single protein as corroborated by an analysis of the linkage architecture. As in our previous work polymer tethers allow us to discriminate between specific and non-specific binding. We analyze the binding configuration (i.e. serial versus parallel connections) through fitting the polymer stretching data with modified Worm-Like Chain (WLC) models that predict how the effective stiffness of the tethers is affected by multiple connections. This analysis establishes that the forces we measure are due to single proteins interacting with multiple ligands, the first force spectroscopy study that establishes single-molecule multivalent binding unambiguously.« less
Predicting dynamics and rheology of blood flow: A comparative study of multiscale and low-dimensional models of red blood cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pan, Wenxiao; Fedosov, Dmitry A.; Caswell, Bruce

In this work we compare the predictive capability of two mathematical models for red blood cells (RBCs) focusing on blood flow in capillaries and arterioles. Both RBC models as well as their corresponding blood flows are based on the dissipative particle dynamics (DPD) method, a coarse-grained molecular dynamics approach. The first model employs a multiscale description of the RBC (MS-RBC), with its membrane represented by hundreds or even thousands of DPD-particles connected by springs into a triangular network in combination with out-of-plane elastic bending resistance. Extra dissipation within the network accounts for membrane viscosity, while the characteristic biconcave RBC shapemore » is achieved by imposition of constraints for constant membrane area and constant cell volume. The second model is based on a low-dimensional description (LD-RBC) constructed as a closed torus-like ring of only 10 large DPD colloidal particles. They are connected into a ring by worm-like chain (WLC) springs combined with bending resistance. The LD-RBC model can be fitted to represent the entire range of nonlinear elastic deformations as measured by optical-tweezers for healthy and for infected RBCs in malaria. MS-RBCs suspensions model the dynamics and rheology of blood flow accurately for any size vessel but this approach is computationally expensive above 100 microns. Surprisingly, the much more economical suspensions of LD-RBCs also capture the blood flow dynamics and rheology accurately except for vessels with sizes comparable to RBC diameter. In particular, the LD-RBC suspensions are shown to properly capture the experimental data for the apparent viscosity of blood and its cell-free layer (CFL) in tube flow. Taken together, these findings suggest a hierarchical approach in modeling blood flow in the arterial tree, whereby the MS-RBC model should be employed for capillaries and arterioles below 100 microns, the LD-RBC model for arterioles, and the continuum description for arteries.« less
Look for good and never give up: A novel attention training treatment for childhood anxiety disorders.

PubMed

Waters, Allison M; Zimmer-Gembeck, Melanie J; Craske, Michelle G; Pine, Daniel S; Bradley, Brendan P; Mogg, Karin

2015-10-01

Attention bias modification training (ABMT) is a promising treatment for anxiety disorders. Recent evidence suggests that attention training towards positive stimuli, using visual-search based ABMT, has beneficial effects on anxiety and attention biases in children. The present study extends this prior research using distinctive techniques designed to increase participant learning, memory consolidation, and treatment engagement. Fifty-nine clinically anxious children were randomly assigned to the active treatment condition (ATC) (N = 31) or waitlist control condition (WLC) (N = 28). In the ATC, children completed 12 treatment sessions at home on computer in which they searched matrices for a pleasant or calm target amongst unpleasant background pictures, while also engaging in techniques designed to consolidate learning and memory for these search strategies. No contact was made with children in the WLC during the wait period. Diagnostic, parent- and child-reports of anxiety and depressive symptoms, externalising behaviour problems and attention biases were assessed pre- and post-condition and six-months after treatment. Children in the ATC showed greater improvements on multiple clinical measures compared to children in the WLC. Post-treatment gains improved six-months after treatment. Attention biases for angry and happy faces did not change significantly from pre-to post-condition. However, larger pre-treatment attention bias towards threat was associated with greater reduction in anxiety at post-treatment. Also, children who showed greater consolidation of learning and memory strategies during treatment achieved greater improvement in global functioning at post-treatment. Attention training towards positive stimuli using enhanced visual-search procedures appears to be a promising treatment for childhood anxiety disorders. Copyright © 2015 Elsevier Ltd. All rights reserved.
A randomized, controlled trial of group cognitive-behavioral therapy for compulsive buying disorder: posttreatment and 6-month follow-up results.

PubMed

Mueller, Astrid; Mueller, Ulrike; Silbermann, Andrea; Reinecker, Hans; Bleich, Stefan; Mitchell, James E; de Zwaan, Martina

2008-07-01

The purpose of this study was to conduct a randomized trial comparing the efficacy of a group cognitive-behavioral therapy (CBT) intervention designed for the treatment of compulsive buying disorder to a waiting list control (WLC) group. Thirty-one patients with compulsive buying problems according to the criteria developed by McElroy et al. were assigned to receive active treatment (12 weekly sessions and 6-month follow-up) and 29 to the WLC group. The treatment was specifically aimed at interrupting and controlling the problematic buying behavior, establishing healthy purchasing patterns, restructuring maladaptive thoughts and negative feelings associated with shopping and buying, and developing healthy coping skills. Primary outcome measures were the Compulsive Buying Scale (CBS), the Yale-Brown Obsessive Compulsive Scale-Shopping Version (YBOCS-SV), and the German Compulsive Buying Scale (G-CBS). Secondary outcome measures were the Symptom Checklist-90-Revised (SCL-90-R), the Barratt Impulsiveness Scale (BIS-11), and the Saving Inventory-Revised (SI-R). The study was completed between November 2003 and May 2007 at the University Hospital of Erlangen, Bavaria, Germany. Multivariate analysis revealed significant differences between the CBT and the WLC groups on the primary outcome variables (outcome-by-time-by-group effect, Pillai's trace, F = 6.960, df = 1, p = .002). The improvement was maintained during the 6-month follow-up. The treatment did not affect other psychopathology, e.g., compulsive hoarding, impulsivity, or SCL-90-R scores. We found that lower numbers of visited group therapy sessions and higher pretreatment hoarding traits as measured with the SI-R total score were significant predictors for nonresponse. The results suggest that a disorder-specific cognitive-behavioral intervention can significantly impact compulsive buying behavior.
Thought Field Therapy Compared to Cognitive Behavioral Therapy and Wait-List for Agoraphobia: A Randomized, Controlled Study with a 12-Month Follow-up.

PubMed

Irgens, Audun C; Hoffart, Asle; Nysæter, Tor E; Haaland, Vegard Ø; Borge, Finn-Magnus; Pripp, Are H; Martinsen, Egil W; Dammen, Toril

2017-01-01

Background: Thought field therapy (TFT) is used for many psychiatric conditions, but its efficacy has not been sufficiently documented. Hence, there is a need for studies comparing TFT to well-established treatments. This study compares the efficacy of TFT and cognitive behavioral therapy (CBT) for patients with agoraphobia. Methods: Seventy-two patients were randomized to CBT ( N = 24), TFT ( N = 24) or a wait-list condition (WLC) ( N = 24) after a diagnostic procedure including the MINI PLUS that was performed before treatment or WLC. Following a 3 months waiting period, the WL patients were randomized to CBT ( n = 12) or TFT ( n = 12), and all patients were reassessed after treatment or waiting period and at 12 months follow-up. At first we compared the three groups CBT, TFT, and WL. After the post WL randomization, we compared CBT ( N = 12 + 24 = 36) to TFT ( N = 12 + 24 = 36), applying the pre-treatment scores as baseline for all patients. The primary outcome measure was a symptom score from the Anxiety Disorders Interview Scale that was performed by an interviewer blinded to the treatment condition. For statistical comparisons, we used the independent sample's t -test, the Fisher's exact test and the ANOVA and ANCOVA tests. Results: Both CBT and TFT showed better results than the WLC ( p < 0.001) at post-treatment. Post-treatment and at the 12-month follow-up, there were not significant differences between CBT and TFT ( p = 0.33 and p = 0.90, respectively). Conclusion: This paper reports the first study comparing TFT to CBT for any disorder. The study indicated that TFT may be an efficient treatment for patients with agoraphobia. Trial Registration: https://clinicaltrials.gov/, identifier NCT00932919.
Thought Field Therapy Compared to Cognitive Behavioral Therapy and Wait-List for Agoraphobia: A Randomized, Controlled Study with a 12-Month Follow-up

PubMed Central

Irgens, Audun C.; Hoffart, Asle; Nysæter, Tor E.; Haaland, Vegard Ø.; Borge, Finn-Magnus; Pripp, Are H.; Martinsen, Egil W.; Dammen, Toril

2017-01-01

Background: Thought field therapy (TFT) is used for many psychiatric conditions, but its efficacy has not been sufficiently documented. Hence, there is a need for studies comparing TFT to well-established treatments. This study compares the efficacy of TFT and cognitive behavioral therapy (CBT) for patients with agoraphobia. Methods: Seventy-two patients were randomized to CBT (N = 24), TFT (N = 24) or a wait-list condition (WLC) (N = 24) after a diagnostic procedure including the MINI PLUS that was performed before treatment or WLC. Following a 3 months waiting period, the WL patients were randomized to CBT (n = 12) or TFT (n = 12), and all patients were reassessed after treatment or waiting period and at 12 months follow-up. At first we compared the three groups CBT, TFT, and WL. After the post WL randomization, we compared CBT (N = 12 + 24 = 36) to TFT (N = 12 + 24 = 36), applying the pre-treatment scores as baseline for all patients. The primary outcome measure was a symptom score from the Anxiety Disorders Interview Scale that was performed by an interviewer blinded to the treatment condition. For statistical comparisons, we used the independent sample’s t-test, the Fisher’s exact test and the ANOVA and ANCOVA tests. Results: Both CBT and TFT showed better results than the WLC (p < 0.001) at post-treatment. Post-treatment and at the 12-month follow-up, there were not significant differences between CBT and TFT (p = 0.33 and p = 0.90, respectively). Conclusion: This paper reports the first study comparing TFT to CBT for any disorder. The study indicated that TFT may be an efficient treatment for patients with agoraphobia. Trial Registration: https://clinicaltrials.gov/, identifier NCT00932919. PMID:28676782
STRUCTURE AND DYNAMICS OF THE 2010 JULY 11 ECLIPSE WHITE-LIGHT CORONA

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pasachoff, J. M.; Rusin, V.; Saniga, M.

The white-light corona (WLC) during the total solar eclipse on 2010 July 11 was observed by several teams in the Moon's shadow stretching across the Pacific Ocean and a number of isolated islands. We present a comparison of the WLC as observed by eclipse teams located on the Tatakoto Atoll in French Polynesia and on Easter Island, 83 minutes later, combined with near-simultaneous space observations. The eclipse was observed at the beginning of the solar cycle, not long after solar minimum. Nevertheless, the solar corona shows a plethora of different features (coronal holes, helmet streamers, polar rays, very faint loopsmore » and radial-oriented thin streamers, a coronal mass ejection, and a puzzling 'curtain-like' object above the north pole). Comparing the observations from the two sites enables us to detect some dynamic phenomena. The eclipse observations are further compared with a hairy-ball model of the magnetic field and near-simultaneous images from the Atmospheric Imaging Assembly on NASA's Solar Dynamics Observatory, the Extreme Ultraviolet Imager on NASA's Solar Terrestrial Relations Observatory, the Sun Watcher, using Active Pixel System Detector and Image Processing on ESA's PRoject for Onboard Autonomy, and the Naval Research Laboratory's Large Angle and Spectrometric Coronagraph on ESA's Solar and Heliospheric Observatory. The Ludendorff flattening coefficient is 0.156, matching the expected ellipticity of coronal isophotes at 2 Rs{sub un}, for this rising phase of the solar-activity cycle.« less
Reducing shame in a game that predicts HIV risk reduction for young adult men who have sex with men: a randomized trial delivered nationally over the web

PubMed Central

Christensen, John L; Miller, Lynn Carol; Appleby, Paul Robert; Corsbie-Massay, Charisse; Godoy, Carlos Gustavo; Marsella, Stacy C; Read, Stephen J

2013-01-01

Introduction Men who have sex with men (MSM) often face socially sanctioned disapproval of sexual deviance from the heterosexual “normal.” Such sexual stigma can be internalized producing a painful affective state (i.e., shame). Although shame (e.g., addiction) can predict risk-taking (e.g., alcohol abuse), sexual shame's link to sexual risk-taking is unclear. Socially Optimized Learning in Virtual Environments (SOLVE) was designed to reduce MSM's sexual shame, but whether it does so, and if that reduction predicts HIV risk reduction, is unclear. To test if at baseline, MSM's reported past unprotected anal intercourse (UAI) is related to shame; MSM's exposure to SOLVE compared to a wait-list control (WLC) condition reduces MSM's shame; and shame-reduction mediates the link between WLC condition and UAI risk reduction. Methods HIV-negative, self-identified African American, Latino or White MSM, aged 18–24 years, who had had UAI with a non-primary/casual partner in the past three months were recruited for a national online study. Eligible MSM were computer randomized to either WLC or a web-delivered SOLVE. Retained MSM completed baseline measures (e.g., UAI in the past three months; current level of shame) and, in the SOLVE group, viewed at least one level of the game. At the end of the first session, shame was measured again. MSM completed follow-up UAI measures three months later. All data from 921 retained MSM (WLC condition, 484; SOLVE condition, 437) were analyzed, with missing data multiply imputed. Results At baseline, MSM reporting more risky sexual behaviour reported more shame (r s=0.21; p<0.001). MSM in the SOLVE intervention reported more shame reduction (M=−0.08) than MSM in the control condition (M=0.07; t(919)=4.24; p<0.001). As predicted, the indirect effect was significant (point estimate −0.10, 95% bias-corrected CI [−0.01 to −0.23] such that participants in the SOLVE treatment condition reported greater reductions in shame, which in turn predicted reductions in risky sexual behaviour at follow-up. The direct effect, however, was not significant. Conclusions SOLVE is the first intervention to: (1) significantly reduce shame for MSM; and (2) demonstrate that shame-reduction, due to an intervention, is predictive of risk (UAI) reduction over time. PMID:24242264

Rational-Emotive Therapy and the Reduction of Interpersonal Anxiety in Junior High School Students.

ERIC Educational Resources Information Center

Warren, Ricks; And Others

1984-01-01

Evaluated the effectiveness of rational-emotive therapy and rational-emotive imagery in 59 junior high school students assigned to rational-emotive therapy without imagery (RET), rational-emotive therapy with imagery (REI), relationship-oriented counseling (ROC), and control (WLC) groups. The RET and REI groups were rated on sociometric measures…
Structure and Dynamics of the 2009 July 22 Eclipse White-light Corona

NASA Astrophysics Data System (ADS)

Pasachoff, J. M.; Rušin, V.; Saniga, M.; Druckmüllerová, H.; Babcock, B. A.

2011-11-01

The white-light corona (WLC) during the total solar eclipse of 2009 July 22 was observed by several teams in the Moon's shadow stretching from India and China across the Pacific Ocean with its many isolated islands. We present a comparison of the WLC as observed by eclipse teams located in China (Shanghai region) and on the Enewetak Atoll in the Marshall Islands, with observations taken 112 minutes apart, combined with near-simultaneous space observations. The eclipse was observed at the beginning of solar cycle 24, during a deep solar minimum (officially estimated as 2008 December according to the smoothed sunspot number, but very extended). The solar corona shows several different types of features (coronal holes, polar rays, helmet streamers, faint loops, voids, etc.), though it was extremely sparse in streamers as shown from Large-Angle Spectroscopic Coronagraph data. No large-scale dynamical phenomena were seen when comparing the observations from the two sites, confirming that the corona was quiescent. We measure a Ludendorff flattening coefficient of 0.238, typical of solar minimum.
Filling the glass: Effects of a positive psychology intervention on executive task performance in chronic pain patients.

PubMed

Boselie, J J L M; Vancleef, L M G; Peters, M L

2018-03-24

Chronic pain is associated with emotional problems as well as difficulties in cognitive functioning. Prior experimental studies have shown that optimism, the tendency to expect that good things happen in the future, and positive emotions can counteract pain-induced task performance deficits in healthy participants. More specifically, induced optimism was found to buffer against the negative effects of experimental pain on executive functioning. This clinical experiment examined whether this beneficial effect can be extended to a chronic pain population. Patients (N = 122) were randomized to a positive psychology Internet-based intervention (PPI; n = 74) or a waiting list control condition (WLC; n = 48). The PPI consisted of positive psychology exercises that particularly target optimism, positive emotions and self-compassion. Results demonstrated that patients in the PPI condition scored higher on happiness, optimism, positive future expectancies, positive affect, self-compassion and ability to live a desired life despite pain, and scored lower on pain catastrophizing, depression and anxiety compared to patients in the WLC condition. However, executive task performance did not improve following completion of the PPI, compared to the WLC condition. Despite the lack of evidence that positive emotions and optimism can improve executive task performance in chronic pain patients, this study did convincingly demonstrate that it is possible to increase positive emotions and optimism in chronic pain patients with an online positive psychology intervention. It is imperative to further explore amendable psychological factors that may reduce the negative impact of pain on executive functioning. We demonstrated that an Internet-based positive psychology intervention strengthens optimism and positive emotions in chronic pain patients. These emotional improvements are not associated with improved executive task performance. As pain itself often cannot be relieved, it is imperative to have techniques to reduce the burden of living with chronic pain. © 2018 The Authors. European Journal of Pain published by John Wiley & Sons Ltd on behalf of European Pain Federation -EFIC®.
Randomized Controlled Trial of Neurofeedback on Chemotherapy-Induced Peripheral Neuropathy: A Pilot Study

PubMed Central

Prinsloo, Sarah; Novy, Diane; Driver, Larry; Lyle, Randall; Ramondetta, Lois; Eng, Cathy; McQuade, Jennifer; Lopez, Gabriel; Cohen, Lorenzo

2017-01-01

BACKGROUND Chemotherapy-induced peripheral neuropathy (CIPN) is a significant problem for cancer patients, and there are limited treatment options for this often debilitating condition. Neuromodulatory interventions could be a novel modality for patients trying to manage CIPN symptoms; however, they are not yet the standard of care. This study examined whether electroencephalogram (EEG) neurofeedback (NFB) could alleviate CIPN symptoms in survivors. METHODS This was a randomized controlled trial with survivors assigned to an NFB group or a wait-list control (WLC) group. The NFB group underwent 20 sessions of NFB, in which visual and auditory rewards were given for voluntary changes in EEGs. The Brief Pain Inventory (BPI) worst-pain item was the primary outcome. The BPI, the Pain Quality Assessment Scale, and EEGs were collected before NFB and again after treatment. Outcomes were assessed with general linear modeling. RESULTS Cancer survivors with CIPN (average duration of symptoms, 25.3 mo), who were mostly female and had a mean age of 62.5 years, were recruited between April 2011 and September 2014. One hundred percent of the participants starting the NFB program completed it (30 in the NFB group and 32 in the WLC group). The NFB group demonstrated greater improvement than the controls on the BPI worst-pain item (mean change score, −2.43 [95% confidence interval, −3.58 to −1.28] vs 0.09 [95% confidence interval, −0.72 to −0.90]; P 5 .001; effect size, 0.83). CONCLUSIONS NFB appears to be effective at reducing CIPN symptoms. There was evidence of neurological changes in the cortical location and in the bandwidth targeted by the intervention, and changes in EEG activity were predictive of symptom reduction. PMID:28257146
An uncertainty and sensitivity analysis approach for GIS-based multicriteria landslide susceptibility mapping.

PubMed

Feizizadeh, Bakhtiar; Blaschke, Thomas

2014-03-04

GIS-based multicriteria decision analysis (MCDA) methods are increasingly being used in landslide susceptibility mapping. However, the uncertainties that are associated with MCDA techniques may significantly impact the results. This may sometimes lead to inaccurate outcomes and undesirable consequences. This article introduces a new GIS-based MCDA approach. We illustrate the consequences of applying different MCDA methods within a decision-making process through uncertainty analysis. Three GIS-MCDA methods in conjunction with Monte Carlo simulation (MCS) and Dempster-Shafer theory are analyzed for landslide susceptibility mapping (LSM) in the Urmia lake basin in Iran, which is highly susceptible to landslide hazards. The methodology comprises three stages. First, the LSM criteria are ranked and a sensitivity analysis is implemented to simulate error propagation based on the MCS. The resulting weights are expressed through probability density functions. Accordingly, within the second stage, three MCDA methods, namely analytical hierarchy process (AHP), weighted linear combination (WLC) and ordered weighted average (OWA), are used to produce the landslide susceptibility maps. In the third stage, accuracy assessments are carried out and the uncertainties of the different results are measured. We compare the accuracies of the three MCDA methods based on (1) the Dempster-Shafer theory and (2) a validation of the results using an inventory of known landslides and their respective coverage based on object-based image analysis of IRS-ID satellite images. The results of this study reveal that through the integration of GIS and MCDA models, it is possible to identify strategies for choosing an appropriate method for LSM. Furthermore, our findings indicate that the integration of MCDA and MCS can significantly improve the accuracy of the results. In LSM, the AHP method performed best, while the OWA reveals better performance in the reliability assessment. The WLC operation yielded poor results.
Randomized controlled trial of neurofeedback on chemotherapy-induced peripheral neuropathy: A pilot study.

PubMed

Prinsloo, Sarah; Novy, Diane; Driver, Larry; Lyle, Randall; Ramondetta, Lois; Eng, Cathy; McQuade, Jennifer; Lopez, Gabriel; Cohen, Lorenzo

2017-06-01

Chemotherapy-induced peripheral neuropathy (CIPN) is a significant problem for cancer patients, and there are limited treatment options for this often debilitating condition. Neuromodulatory interventions could be a novel modality for patients trying to manage CIPN symptoms; however, they are not yet the standard of care. This study examined whether electroencephalogram (EEG) neurofeedback (NFB) could alleviate CIPN symptoms in survivors. This was a randomized controlled trial with survivors assigned to an NFB group or a wait-list control (WLC) group. The NFB group underwent 20 sessions of NFB, in which visual and auditory rewards were given for voluntary changes in EEGs. The Brief Pain Inventory (BPI) worst-pain item was the primary outcome. The BPI, the Pain Quality Assessment Scale, and EEGs were collected before NFB and again after treatment. Outcomes were assessed with general linear modeling. Cancer survivors with CIPN (average duration of symptoms, 25.3 mo), who were mostly female and had a mean age of 62.5 years, were recruited between April 2011 and September 2014. One hundred percent of the participants starting the NFB program completed it (30 in the NFB group and 32 in the WLC group). The NFB group demonstrated greater improvement than the controls on the BPI worst-pain item (mean change score, -2.43 [95% confidence interval, -3.58 to -1.28] vs 0.09 [95% confidence interval, -0.72 to -0.90]; P =·.001; effect size, 0.83). NFB appears to be effective at reducing CIPN symptoms. There was evidence of neurological changes in the cortical location and in the bandwidth targeted by the intervention, and changes in EEG activity were predictive of symptom reduction. Cancer 2017;123:1989-1997. © 2017 American Cancer Society. © 2017 American Cancer Society.
Evaluation of the dating skills program for improving heterosocial interactions in people with mental retardation.

PubMed

Valenti-Hein, D C; Yarnold, P R; Mueser, K T

1994-01-01

The effectiveness of a social skills training program for improving heterosocial interactions in persons with mental retardation was examined. Moderate to borderline mentally retarded subjects were selected based on problems with social anxiety and social skill deficits. Subjects were then randomly assigned to either a 12-session Dating Skills Program (DSP) or a wait list control (WLC) group. Assessments of social skills in a role-play test, knowledge about social/sexual situations, and social anxiety were obtained for all subjects at baseline, posttreatment, and at an 8-week follow-up. In addition, naturalistic observations were made of interactions of subjects in the DSP group. Subjects who participated in the DSP showed improvements in social skill and social/sexual knowledge at posttest and at follow-up compared to subjects in the WLC group. Social anxiety did not change over time for either group of subjects. Subjects who received the DSP increased interactions with persons of the opposite gender over time, while same-gender interactions decreased. The results replicate and extend previous research on the Dating Skills Program, and suggest that social skills training interventions may improve the heterosocial interactions of adults with mental retardation.
Suitability assessment and mapping of Oyo State, Nigeria, for rice cultivation using GIS

NASA Astrophysics Data System (ADS)

Ayoade, Modupe Alake

2017-08-01

Rice is one of the most preferred food crops in Nigeria. However, local rice production has declined with the oil boom of the 1970s causing demand to outstrip supply. Rice production can be increased through the integration of Geographic Information Systems (GIS) and crop-land suitability analysis and mapping. Based on the key predictor variables that determine rice yield mentioned in relevant literature, data on rainfall, temperature, relative humidity, slope, and soil of Oyo state were obtained. To develop rice suitability maps for the state, two MCE-GIS techniques, namely the Overlay approach and weighted linear combination (WLC), using fuzzy AHP were used and compared. A Boolean land use map derived from a landsat imagery was used in masking out areas currently unavailable for rice production. Both suitability maps were classified into four categories of very suitable, suitable, moderate, and fairly moderate. Although the maps differ slightly, the overlay and WLC (AHP) approach found most parts of Oyo state (51.79 and 82.9 % respectively) to be moderately suitable for rice production. However, in areas like Eruwa, Oyo, and Shaki, rainfall amount received needs to be supplemented by irrigation for increased rice yield.
Multimodal 3D cancer-mimicking optical phantom

PubMed Central

Smith, Gennifer T.; Lurie, Kristen L.; Zlatev, Dimitar V.; Liao, Joseph C.; Ellerbee Bowden, Audrey K.

2016-01-01

Three-dimensional (3D) organ-mimicking phantoms provide realistic imaging environments for testing various aspects of optical systems, including for evaluating new probe designs, characterizing the diagnostic potential of new technologies, and assessing novel image processing algorithms prior to validation in real tissue. We introduce and characterize the use of a new material, Dragon Skin (Smooth-On Inc.), and fabrication technique, air-brushing, for fabrication of a 3D phantom that mimics the appearance of a real organ under multiple imaging modalities. We demonstrate the utility of the material and technique by fabricating the first 3D, hollow bladder phantom with realistic normal and multi-stage pathology features suitable for endoscopic detection using the gold standard imaging technique, white light cystoscopy (WLC), as well as the complementary imaging modalities of optical coherence tomography and blue light cystoscopy, which are aimed at improving the sensitivity and specificity of WLC to bladder cancer detection. The flexibility of the material and technique used for phantom construction allowed for the representation of a wide range of diseased tissue states, ranging from inflammation (benign) to high-grade cancerous lesions. Such phantoms can serve as important tools for trainee education and evaluation of new endoscopic instrumentation. PMID:26977369
Higher-order cognitive training effects on processing speed-related neural activity: a randomized trial.

PubMed

Motes, Michael A; Yezhuvath, Uma S; Aslan, Sina; Spence, Jeffrey S; Rypma, Bart; Chapman, Sandra B

2018-02-01

Higher-order cognitive training has shown to enhance performance in older adults, but the neural mechanisms underlying performance enhancement have yet to be fully disambiguated. This randomized trial examined changes in processing speed and processing speed-related neural activity in older participants (57-71 years of age) who underwent cognitive training (CT, N = 12) compared with wait-listed (WLC, N = 15) or exercise-training active (AC, N = 14) controls. The cognitive training taught cognitive control functions of strategic attention, integrative reasoning, and innovation over 12 weeks. All 3 groups worked through a functional magnetic resonance imaging processing speed task during 3 sessions (baseline, mid-training, and post-training). Although all groups showed faster reaction times (RTs) across sessions, the CT group showed a significant increase, and the WLC and AC groups showed significant decreases across sessions in the association between RT and BOLD signal change within the left prefrontal cortex (PFC). Thus, cognitive training led to a change in processing speed-related neural activity where faster processing speed was associated with reduced PFC activation, fitting previously identified neural efficiency profiles. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.
Criteria for robustness of heteroclinic cycles in neural microcircuits

PubMed Central

2011-01-01

We introduce a test for robustness of heteroclinic cycles that appear in neural microcircuits modeled as coupled dynamical cells. Robust heteroclinic cycles (RHCs) can appear as robust attractors in Lotka-Volterra-type winnerless competition (WLC) models as well as in more general coupled and/or symmetric systems. It has been previously suggested that RHCs may be relevant to a range of neural activities, from encoding and binding to spatio-temporal sequence generation. The robustness or otherwise of such cycles depends both on the coupling structure and the internal structure of the neurons. We verify that robust heteroclinic cycles can appear in systems of three identical cells, but only if we require perturbations to preserve some invariant subspaces for the individual cells. On the other hand, heteroclinic attractors can appear robustly in systems of four or more identical cells for some symmetric coupling patterns, without restriction on the internal dynamics of the cells. PMID:22656192
Effects of a Cognitive Behavioral Self-Help Program on Emotional Problems for People with Acquired Hearing Loss: A Randomized Controlled Trial

ERIC Educational Resources Information Center

Garnefski, Nadia; Kraaij, Vivian

2012-01-01

The aim of the study was to examine whether a cognitive-behavioral self-help program was effective in improving depressed mood and anxiety in people with acquired deafness. Participants were 45 persons with acquired deafness, randomly allocated to the Cognitive-Behavioral Self-help (CBS) group or the Waiting List Control (WLC) group. Depression…
The Prevalence of Stress-Related Disorders in BC School Districts. BCTF Research Report: Part of the BCTF Information Handbook. Section XII. 2009-WLC-01

ERIC Educational Resources Information Center

Naylor, Charlie; Vint, Amber

2009-01-01

This paper presents British Columbia Teachers' Federation's (BCTF) research report that has produced tables which allow the BCTF and its locals to consider the prevalence of Salary Indemnity Plan (SIP) claims by school district. While the data shown in this report indicate high prevalence of stress in some school districts, they actually…
Randomized Trial of a Family-based, Automated, Conversational Obesity Treatment Program for Underserved Populations

PubMed Central

Wright, J. A.; Phillips, B.D.; Watson, B.L.; Newby, P.K.; Norman, G. J.; Adams, W.G.

2013-01-01

Objective To evaluate the acceptability and feasibility of a scalable obesity treatment program integrated with pediatric primary care and delivered using interactive voice technology (IVR) to families from underserved populations. Design and Methods Fifty parent-child dyads (child 9–12 yrs, BMI >95th percentile) were recruited from a pediatric primary care clinic and randomized to either an IVR or a wait-list control (WLC) group. The majority were lower-income, African-American (72%) families. Dyads received IVR calls for 12 weeks. Call content was informed by two evidenced-based interventions. Anthropometric and behavioral variables were assessed at baseline and 3 mo follow-up. Results Forty-three dyads completed the study. IVR parents ate 1 cup more fruit than WLC (p < .05). No other groups differences were found. Children classified as high users of the IVR decreased weight, BMI and BMI z-score compared to low users (p<.05). Mean number of calls for parents and children were 9.1 (5.2 SD) and 9.0 (5.7 SD), respectively. Of those who made calls, >75% agreed that the calls were useful, made for people like them, credible, and helped them eat healthy foods. Conclusion An obesity treatment program delivered via IVR may be an acceptable and feasible resource for families from underserved populations. PMID:23512915
Realize multiple hermetic chamber pressures for system-on-chip process by using the capping wafer with diverse cavity depths

NASA Astrophysics Data System (ADS)

Cheng, Shyh-Wei; Weng, Jui-Chun; Liang, Kai-Chih; Sun, Yi-Chiang; Fang, Weileun

2018-04-01

Many mechanical and thermal characteristics, for example the air damping, of suspended micromachined structures are sensitive to the ambient pressure. Thus, micromachined devices such as the gyroscope and accelerometer have different ambient pressure requirements. Commercially available process platforms could be used to fabricate and integrate devices of various functions to reduce the chip size. However, it remains a challenge to offer different ambient pressures for micromachined devices after sealing them by wafer level capping (WLC). This study exploits the outgassing characteristics of the CMOS chip to fabricate chambers of various pressures after the WLC of the Si-above-CMOS (TSMC 0.18 µm 1P5M CMOS process) MEMS process platform. The pressure of the sealed chamber can be modulated by the chamber volume after the outgassing. In other words, the pressure of hermetic sealed chambers can be easily and properly defined by the etching depth of the cavity on an Si capping wafer. In applications, devices sealed with different cavity depths are implemented using the Si-above-CMOS (TSMC 0.18 µm 1P5M CMOS process) MEMS process platform to demonstrate the present approach. Measurements show the feasibility of this simple chamber pressure modulation approach on eight-inch wafers.
Evaluation of a cognitive-behavioral pain management program for children with chronic abdominal pain: a randomized controlled study.

PubMed

Groß, Martina; Warschburger, Petra

2013-09-01

Chronic abdominal pain (CAP) in childhood is widely prevalent and has adverse effects on mental health and quality of life. Earlier research emphasized the positive effects of psychological intervention on pain symptoms. This study describes the results of a cognitive-behavioral pain management program for children with CAP. The newly developed cognitive-behavioral group program, "Stop the pain with Happy-Pingu," includes six sessions for the children and one meeting for the parents. We hypothesized that the training would significantly reduce pain symptoms (frequency, duration, intensity, and pain-related impairment) and increase health-related quality of life compared to wait-list controls, with improvement seen both at the end of treatment and at a 3-month follow-up. In all, 29 children were randomized into two groups: 15 in the intervention group (IG) and 14 as the wait-list controls (WLC). An intent-to-treat analysis was performed using two-factorial multivariate analyses of variance with repeated measures. Children in the IG experienced both a reduction in pain (primary outcome) and an improvement in health-related quality of life (secondary outcome) as compared to the WLC. The effect sizes ranged from medium to high. Cognitive-behavioral methods seem to be appropriate for treating children with CAP.
An uncertainty and sensitivity analysis approach for GIS-based multicriteria landslide susceptibility mapping

PubMed Central

Feizizadeh, Bakhtiar; Blaschke, Thomas

2014-01-01

GIS-based multicriteria decision analysis (MCDA) methods are increasingly being used in landslide susceptibility mapping. However, the uncertainties that are associated with MCDA techniques may significantly impact the results. This may sometimes lead to inaccurate outcomes and undesirable consequences. This article introduces a new GIS-based MCDA approach. We illustrate the consequences of applying different MCDA methods within a decision-making process through uncertainty analysis. Three GIS-MCDA methods in conjunction with Monte Carlo simulation (MCS) and Dempster–Shafer theory are analyzed for landslide susceptibility mapping (LSM) in the Urmia lake basin in Iran, which is highly susceptible to landslide hazards. The methodology comprises three stages. First, the LSM criteria are ranked and a sensitivity analysis is implemented to simulate error propagation based on the MCS. The resulting weights are expressed through probability density functions. Accordingly, within the second stage, three MCDA methods, namely analytical hierarchy process (AHP), weighted linear combination (WLC) and ordered weighted average (OWA), are used to produce the landslide susceptibility maps. In the third stage, accuracy assessments are carried out and the uncertainties of the different results are measured. We compare the accuracies of the three MCDA methods based on (1) the Dempster–Shafer theory and (2) a validation of the results using an inventory of known landslides and their respective coverage based on object-based image analysis of IRS-ID satellite images. The results of this study reveal that through the integration of GIS and MCDA models, it is possible to identify strategies for choosing an appropriate method for LSM. Furthermore, our findings indicate that the integration of MCDA and MCS can significantly improve the accuracy of the results. In LSM, the AHP method performed best, while the OWA reveals better performance in the reliability assessment. The WLC operation yielded poor results. PMID:27019609
Internet-Delivered Exposure Therapy for Fibromyalgia: A Randomized Controlled Trial.

PubMed

Hedman-Lagerlöf, Maria; Hedman-Lagerlöf, Erik; Axelsson, Erland; Ljótsson, Brjánn; Engelbrektsson, Johanna; Hultkrantz, Sofia; Lundbäck, Karolina; Björkander, Daniel; Wicksell, Rikard K; Flink, Ida; Andersson, Erik

2018-06-01

Fibromyalgia (FM) is a common and disabling chronic pain disorder, for which existing pharmacological and psychological treatments have yet yielded insufficient effects. Previous literature has shown that exposure therapy may be an effective treatment for chronic pain. This study constitutes the first randomized controlled trial evaluating exposure therapy for FM. A total of 140 participants with diagnosed FM were randomized to a 10-week Internet-delivered exposure treatment (iExp; n=70) or a waitlist control condition (WLC; n=70). Primary outcome measure were FM symptoms and impact, and secondary outcome measures were fatigue, disability, quality of life, pain-related distress and avoidance behaviors, insomnia, depression, and anxiety. Data retention was high (100% data completion at posttreatment for primary outcome, 96% at 6-month follow-up and 94% at 12-month follow-up). Results showed that participants in the iExp group made large and superior improvements compared with WLC on FM symptoms and impact (B, -1.93; z, -10.14; P<0.001, between-group Cohen d=0.90), as well as all secondary outcomes (between-group Cohen d ranging from 0.44 to 1.38) with sustained results. We conclude that iExp seems to be an efficacious treatment for FM compared with no treatment, and the results also highlight the potential increase of accessibility by using the Internet format to deliver psychological treatments for these patients. Future trials with active control conditions are warranted.
Generic versus disorder specific cognitive behavior therapy for social anxiety disorder in youth: A randomized controlled trial using internet delivery.

PubMed

Spence, Susan H; Donovan, Caroline L; March, Sonja; Kenardy, Justin A; Hearn, Cate S

2017-03-01

The study examined whether the efficacy of cognitive behavioral treatment for Social Anxiety Disorder for children and adolescents is increased if intervention addresses specific cognitive and behavioral factors linked to the development and maintenance of SAD in young people, over and above the traditional generic CBT approach. Participants were 125 youth, aged 8-17 years, with a primary diagnosis of SAD, who were randomly assigned to generic CBT (CBT-GEN), social anxiety specific CBT (CBT-SAD) or a wait list control (WLC). Intervention was delivered using a therapist-supported online program. After 12-weeks, participants who received treatment (CBT-SAD or CBT-GEN) showed significantly greater reduction in social anxiety and post-event processing, and greater improvement in global functioning than the WLC but there was no significant difference between CBT-SAD and CBT-GEN on any outcome variable at 12-weeks or 6-month follow-up. Despite significant reductions in anxiety, the majority in both treatment conditions continued to meet diagnostic criteria for SAD at 6-month follow-up. Decreases in social anxiety were associated with decreases in post-event processing. Future research should continue to investigate disorder-specific interventions for SAD in young people, drawing on evidence regarding causal or maintaining factors, in order to enhance treatment outcomes for this debilitating condition. Copyright © 2016 Elsevier Ltd. All rights reserved.
A four-session acceptance and commitment therapy based intervention for depressive symptoms delivered by masters degree level psychology students: a preliminary study.

PubMed

Kohtala, Aino; Lappalainen, Raimo; Savonen, Laura; Timo, Elina; Tolvanen, Asko

2015-05-01

Depressive symptoms are one of the main reasons for seeking psychological help. Shorter interventions using briefly trained therapists could offer a solution to the ever-rising need for early and easily applicable psychological treatments. The current study examines the effectiveness of a four-session Acceptance and Commitment Therapy (ACT) based treatment for self-reported depressive symptoms administered by Masters level psychology students. This paper reports the effectiveness of a brief intervention compared to a waiting list control (WLC) group. Participants were randomized into two groups: ACT (n = 28) and waiting list (n = 29). Long-term effects were examined using a 6-month follow-up. The treatment group's level of depressive symptoms (Beck Depression Inventory) decreased by an average of 47%, compared to an average decrease of 4% in the WLC group. Changes in psychological well-being in the ACT group were better throughout, and treatment outcomes were maintained after 6 months. The posttreatment "between-group" and follow-up "with-in group" effect sizes (Cohen's d) were large to medium for depressive symptoms and psychological flexibility. The results support the brief ACT-based intervention for sub-clinical depressive symptoms when treatment was conducted by briefly trained psychology students. It also contributes to the growing body of evidence on brief ACT-based treatments and inexperienced therapists.

Review of Theoretical Approaches to Nonlinear Supercavitating Flows

DTIC Science & Technology

2001-02-01

hodograph) method to flow past a body with a curved topography was considered iy Levi - Civita [15] and Villat [24]. 2.3. Mixed boundary value problem...streamline flow around a body with a curved boundary 5.1. Levi - Civita approach Levi - Civita [15] was the first to propose an approach to solution of the plane...enotes a real parameter to 1)e determfineid. The second step is formulation of a imiixed bounidary value problem for Levi - Civita [15] function dw v WLC
An Investigation into Current Construction Engineering and Management Programs and Curricula and Their Applicability to the U.S. Armed Forces

DTIC Science & Technology

1988-06-01

34Fioneer :. ConsruLtiCn EnIineeri Edcatio .’ JUrnalE 1WLC trutior, Enqineeri") anJ lar,-emert. AEt. c. 111. N1 :. 1. Mar.. 1985. 1-z.evis. A.C.. Fros and...34 Scciet y_fr Fronctg EnA Lneerinq Edution Civil EnoineerinQ Division Fk -1-1e t!in . ’J I . 7, ND. 1 . DEec .. I19i4 1 pp .6. Rainer, R.P., "Civil
Rationale and Design of the Feeding Dynamic Intervention (FDI) Study for Self-Regulation of Energy Intake in Preschoolers

PubMed Central

Eneli, Ihuoma U.; Tylka, Tracy L.; Hummel, Jessica; Watowicz, Rosanna P.; Perez, Susana A.; Kaciroti, Niko; Lumeng, Julie C.

2015-01-01

In 2011, the Institute of Medicine Early Childhood Prevention Policies Report identified feeding dynamics as an important focus area for childhood obesity prevention and treatment. Feeding dynamics include two central components: (1) caregiver feeding practices (i.e., determining how, when, where, and what they feed their children) and (2) child eating behaviors (i.e., determining how much and what to eat from what food caregivers have provided). Although there has been great interest in overweight and obesity prevention and treatment in young children, they have not focused comprehensively on feeding dynamics. Interventions on feeding dynamics that reduce caregivers’ excessive controlling and restrictive feeding practices and encourage the development of children’s self-regulation of energy intake may hold promise for tackling childhood obesity especially in the young child but currently lack an evidence base. This manuscript describes the rationale and design for a randomized controlled trial designed to compare a group of mothers and their 3-to 5-year old children who received an intervention focused primarily on feeding dynamics called the Feeding Dynamic Intervention (FDI) with a Wait-list Control Group (WLC). The primary aim of the study will be to investigate the efficacy of the FDI for decreasing Eating in the Absence of Hunger (EAH) and improving energy compensation (COMPX). The secondary aim will be to examine the effect of the FDI in comparison to the WLC on maternal self-reported feeding practices and child satiety responsiveness. PMID:25616192
Dynamic Real-time Microscopy of the Urinary Tract Using Confocal Laser Endomicroscopy

PubMed Central

Wu, Katherine; Liu, Jen-Jane; Adams, Winifred; Sonn, Geoffrey A.; Mach, Kathleen E.; Pan, Ying; Beck, Andrew H.; Jensen, Kristin C.; Liao, Joseph C.

2014-01-01

OBJECTIVES To develop the diagnostic criteria for benign and neoplastic conditions of the urinary tract using probe-based confocal laser endomicroscopy (pCLE), a new technology for dynamic, in vivo imaging with micron-scale resolution. The suggested diagnostic criteria will formulate a guide for pCLE image interpretation in urology. METHODS Patients scheduled for transurethral resection of bladder tumor (TURBT) or nephrectomy were recruited. After white-light cystoscopy (WLC), fluorescein was administered as contrast. Different areas of the urinary tract were imaged with pCLE via direct contact between the confocal probe and the area of interest. Confocal images were subsequently compared with standard hematoxylin and eosin analysis. RESULTS pCLE images were collected from 66 participants, including 2 patients who underwent nephrectomy. We identified key features associated with different anatomic landmarks of the urinary tract, including the kidney, ureter, bladder, prostate, and urethra. In vivo pCLE of the bladder demonstrated distinct differences between normal mucosa and neoplastic tissue. Using mosaicing, a post hoc image-processing algorithm, individual image frames were juxtaposed to form wideangle views to better evaluate tissue microarchitecture. CONCLUSIONS In contrast to standard pathologic analysis of fixed tissue with hematoxylin and eosin, pCLE provides real time microscopy of the urinary tract to enable dynamic interrogation of benign and neoplastic tissues in vivo. The diagnostic criteria developed in this study will facilitate adaptation of pCLE for use in conjunction with WLC to expedite diagnosis of urinary tract pathology, particularly bladder cancer. PMID:21601243
Comparing two books and establishing probably efficacious treatment for low sexual desire.

PubMed

Balzer, Alexandra M; Mintz, Laurie B

2015-04-01

Using a sample of 45 women, this study compared the effectiveness of a previously studied (Mintz, Balzer, Zhao, & Bush, 2012) bibliotherapy intervention (Mintz, 2009), a similar self-help book (Hall, 2004), and a wait-list control (WLC) group. To examine intervention effectiveness, between and within group standardized effect sizes (interpreted with Cohen's, 1988 benchmarks .20 = small, .50 = medium, .80+ = large) and their confidence limits are used. In comparison to the WLC group, both interventions yielded large between-group posttest effect sizes on a measure of sexual desire. Additionally, large between-group posttest effect sizes were found for sexual satisfaction and lubrication among those reading the Mintz book. When examining within-group pretest to posttest effect sizes, medium to large effects were found for desire, lubrication, and orgasm for both books and for satisfaction and arousal for those reading the Mintz book. When directly comparing the books, all between-group posttest effect sizes were likely obtained by chance. It is concluded that both books are equally effective in terms of the outcome of desire, but whether or not there is differential efficacy in terms of other domains of sexual functioning is equivocal. Tentative evidence is provided for the longer term effectiveness of both books in enhancing desire. Arguing for applying criteria for empirically supported treatments to self-help, results are purported to establish the Mintz book as probably efficacious and to comprise a first step in this designation for the Hall book. (c) 2015 APA, all rights reserved).
Efficacy of the resilience and adjustment intervention after traumatic brain injury: a randomized controlled trial.

PubMed

Kreutzer, Jeffrey S; Marwitz, Jennifer H; Sima, Adam P; Mills, Ana; Hsu, Nancy H; Lukow, Herman R

2018-05-24

Examine a psychoeducational and skill-building intervention's effectiveness for individuals after traumatic brain injury (TBI), using a two-arm, parallel, randomized, controlled trial with wait-listed control. The Resilience and Adjustment Intervention (RAI) targets adjustment challenges and emphasizes education, skill-building and psychological support. Overall, 160 outpatients were randomly assigned to a treatment or wait-list control (WLC) group. The manualized treatment was delivered in seven 1-h sessions. The Connor-Davidson Resilience Scale (CD-RISC) was the primary outcome measure. Secondary measures included the Mayo Portland Adaptability Inventory-4 (MPAI-4), Brief Symptom Inventory-18 (BSI-18) and 13-Item Stress Test. After adjusting for injury severity, education and time postinjury, the RAI group (N = 75) demonstrated a significantly greater increase in resilience (effect size = 1.03) compared to the WLC group (N = 73). Participants in the RAI group demonstrated more favourable scores on the MPAI-4 Adjustment and Ability Indices, BSI-18 and the 13-item Stress Test. However, only the CD-RISC and BSI-18 demonstrated a clinically significant difference. In addition, RAI participants demonstrated maintenance of gains from pre-treatment to 3-month follow-up; however, only the BSI-18 maintained a clinically significant difference. Investigation provided evidence that a resilience-focused intervention can improve psychological health and adjustment after TBI. Additional research is needed to ascertain the longer term benefits of intervention and the efficacy of alternative delivery methods (e.g., via telephone, Internet).
Randomized Controlled Trial of a Home‐Based Walking Program to Reduce Moderate to Severe Aromatase Inhibitor‐Associated Arthralgia in Breast Cancer Survivors

PubMed Central

Callahan, Leigh F.; Cleveland, Rebecca J.; Arbeeva, Liubov L.; Hackney, Betsy S.; Muss, Hyman B.

2017-01-01

Abstract Background. In postmenopausal women diagnosed with breast cancer (BC), most BC tumors are hormone receptor positive and guidelines recommend adjuvant endocrine therapy that includes an aromatase inhibitor (AI). This study investigates the impact of a 6‐week, home‐based, self‐directed walking program on the commonly reported side effect of AI‐associated arthralgia (AIAA). Materials and Methods. In this phase II trial, consented BC patients were randomized to walking Intervention (n = 31) or Wait List Control (WLC; n = 31). Eligibility criteria included: stage 0–III BC, on AI for at least 4 weeks, ≥3 on a 5‐point scale inquiring about joint symptom intensity “at its worst,” and exercising ≤150 minutes per week. Outcomes were self‐reported joint symptoms and psychosocial measures. Analyses comparing Intervention and WLC groups were conducted on an intention‐to‐treat basis to assess intervention impact at 6 weeks (postintervention) and at 6‐months follow‐up. Adjusted means were calculated to assess differences in two groups. Results. In our final sample (n = 62), mean age was 64 years, 74% were white, and 63% had a body mass index of 30 or higher. At postintervention, Intervention group participants reported significantly increased walking minutes per week, reduced stiffness, less difficulty with activities of daily living (ADL), and less perceived helplessness in managing joint symptoms. At 6‐months follow‐up (postwalking period in both Intervention and WLC), walking minutes per week had decreased significantly; however, improvements in stiffness and difficulty with ADLs were maintained. Conclusion. This study adds to the growing evidence base suggesting exercise as a safe alternative or adjunct to medications for the management of AIAA. Implications for Practice. Breast cancer survivors whose adjuvant endocrine treatment includes an aromatase inhibitor (AI) often experience the side effect of AI‐associated arthralgia (AIAA). This study investigates the impact of a 6‐week, home‐based, self‐directed walking program in the management of AIAA. Compared with Wait List Control, women in the Intervention group reported significantly increased walking minutes per week, reduced stiffness, less difficulty with activities of daily living, and less perceived helplessness in managing joint symptoms. This study adds to the growing evidence base suggesting exercise as a safe alternative or adjunct to medications for the management of AIAA. PMID:28698390
Ultrafast nonlinear spectrometer for material characterization

NASA Astrophysics Data System (ADS)

Negres, Raluca Aurelia

2001-11-01

This work describes the use of a broadband spectral source for nonlinear spectroscopy to characterize various materials with potential applications in confocal microscopy, biological sample markers, optical limiting devices and optical switches. The goal is to study the spectrum of nonlinear absorption and the dispersion of nonlinear refraction as well as the dynamics of the nonlinearities by means of femtosecond excite-probe experiments. The principle is quite simple: if a sample is under the influence of a strong fs excitation pulse and a probe pulse beam is incident at the same time, or shortly after (within the decay time of the nonlinearity), then the probe pulse will sense the nonlinearity induced by the excitation. If the probe pulse is broadband, a femtosecond white-light continuum (WLC) in our case, we can monitor the nonlinearity induced over the entire continuum spectrum in one laser ``shot''. The use of femtosecond laser pulses to generate WLC will provide femtosecond time resolution for time-resolved spectroscopy. We built the nonlinear spectrometer and allowed for many degrees of flexibility in terms of choice of wavelengths for pump and probe beams and a dual detection system to cover both visible and infrared spectral ranges. We have the possibility of performing broad band spectral measurements using a spectrometer or selected narrow bandwidth probes incident on Si or Ge photodiodes, for improved S/N ratios. The intrinsic properties of the continuum probe demand a careful characterization of its spatial and temporal profile. Knowledge of the dispersion of the index of refraction in various optical elements, including the sample itself, is also required for a correct analysis of the transient absorption raw data, especially for short time-scale dynamics of nonlinear processes. We tested the system using well-characterized semiconductor samples, and the results came out in excellent agreement with those from previous picosecond Z-scan measurements and theoretical modeling. With confidence, we can now measure various organic dyes with enhanced two-photon and excited-state absorption. Our setup is used to conduct a systematic study on similar compounds with modified molecular structures in order to learn about structure-property relations and draw guidelines for future design work.
A randomized controlled trial of combined exercise and psycho-education for low-SES women: short- and long-term outcomes in the reduction of stress and depressive symptoms.

PubMed

van der Waerden, Judith E B; Hoefnagels, Cees; Hosman, Clemens M H; Souren, Pierre M; Jansen, Maria W J

2013-08-01

Exercise may have both a preventive and a therapeutic impact on mental health problems. The Exercise without Worries intervention aims to reduce stress and depressive symptoms in low-SES women by means of a group-based program combining physical exercise and psycho-education. Between September 2005 and May 2008, 161 Dutch low-SES women with elevated stress or depressive symptom levels were randomly assigned to the combined exercise/psycho-education intervention (EP), exercise only (E) or a waiting list control condition (WLC). The E condition provided low to moderate intensity stretching, strength, flexibility, and body focused training as well as relaxation, while the EP program integrated the exercise with cognitive-behavioral techniques. Depressive symptoms (CES-D) and perceived stress (PSS) were measured before and immediately after the intervention and at 2, 6 and 12 month follow-up. Multilevel linear mixed-effects models revealed no differential patterns in reduction of CES-D or PSS scores between the EP, E and WLC groups on the short (post-test and 2 month follow-up) or long term (6 and 12 months follow-up). Depressive symptom outcomes were moderated by initial depressive symptom scores: women from the EP and E groups with fewer initial symptoms benefited from participation on the short term. Further, women in the EP and E groups with the lowest educational level reported more stress reduction at post-test than women with higher educational levels. In the overall target population of low-SES women, no indications were found that the Exercise without Worries course reduced depressive symptom and stress levels on the short or long term. The findings do suggest, however, that exercise alone or in combination with psycho-education may be a viable prevention option for certain groups of disadvantaged women. Especially those low-SES women with less severe initial problems or those with low educational attainment should be targeted for future depression prevention practice. Copyright © 2013 Elsevier Ltd. All rights reserved.
Enhanced Fuzzy-OWA model for municipal solid waste landfill site selection

NASA Astrophysics Data System (ADS)

Ahmad, Siti Zubaidah; Ahamad, Mohd Sanusi S.; Yusoff, Mohd Suffian; Abujayyab, Sohaib K. M.

2017-10-01

In Malaysia, the municipal solid waste landfill site is an essential facility that needs to be evaluated as its demand is infrequently getting higher. The increment of waste generation forces the government to cater the appropriate site for waste disposal. However, the selection process for new landfill sites is a difficult task with regard to land scarcity and time consumption. In addition, the complication will proliferate when there are various criteria to be considered. Therefore, this paper intends to show the significance of the fuzzy logic-ordered weighted average (Fuzzy-OWA) model for the landfill site suitability analysis. The model was developed to generalize the multi-criteria combination that was extended to the GIS applications as part of the decision support module. OWA has the capability to implement different combination operators through the selection of appropriate order weight that is possible in changing the form of aggregation such as minimum, intermediate and maximum types of combination. OWA give six forms of aggregation results that have their specific significance that indirectly evaluates the environmental, physical and socio-economic (EPSE) criteria respectively. Nevertheless, one of the aggregated results has shown similarity with the weighted linear combination (WLC) method.
Efficacy of an internet-based problem-solving training for teachers: results of a randomized controlled trial.

PubMed

Ebert, David Daniel; Lehr, Dirk; Boß, Leif; Riper, Heleen; Cuijpers, Pim; Andersson, Gerhard; Thiart, Hanne; Heber, Elena; Berking, Matthias

2014-11-01

The primary purpose of this randomized controlled trial (RCT) was to evaluate the efficacy of internet-based problem-solving training (iPST) for employees in the educational sector (teachers) with depressive symptoms. The results of training were compared to those of a waitlist control group (WLC). One-hundred and fifty teachers with elevated depressive symptoms (Center for Epidemiologic Studies Depression Scale, CES-D ≥16) were assigned to either the iPST or WLC group. The iPST consisted of five lessons, including problem-solving and rumination techniques. Symptoms were assessed before the intervention began and in follow-up assessments after seven weeks, three months, and six months. The primary outcome was depressive symptom severity (CES-D). Secondary outcomes included general and work-specific self-efficacy, perceived stress, pathological worries, burnout symptoms, general physical and mental health, and absenteeism. iPST participants displayed a significantly greater reduction in depressive symptoms after the intervention (d=0.59, 95% CI 0.26-0.92), after three months (d=0.37, 95% CI 0.05-0.70) and after six months (d=0.38, 95% CI 0.05-0.70) compared to the control group. The iPST participants also displayed significantly higher improvements in secondary outcomes. However, workplace absenteeism was not significantly affected. iPST is effective in reducing symptoms of depression among teachers. Disseminated on a large scale, iPST could contribute to reducing the burden of stress-related mental health problems among teachers. Future studies should evaluate iPST approaches for use in other working populations.
Multilayered disease-mimicking bladder phantom with realistic surface topology for optical coherence tomography

NASA Astrophysics Data System (ADS)

Smith, Gennifer T.; Lurie, Kristen L.; Khan, Saara A.; Liao, Joseph C.; Ellerbee, Audrey K.

2014-03-01

Optical coherence tomography (OCT) has shown potential as a complementary modality to white light cystoscopy (WLC), the gold standard for imaging bladder cancer. OCT can visualize sub-surface details of the bladder wall, which enables it to stage cancers and detect tumors that are otherwise invisible to WLC. Currently, OCT systems have too slow a speed and too small a field of view for comprehensive bladder imaging, which limits its clinical utility. Validation and feasibility testing of technological refinements aimed to provide faster imaging and wider fields of view necessitates a realistic bladder phantom. We present a novel process to fabricate the first such phantom that mimics both the optical and morphological properties of layers of the healthy and pathologic bladder wall as they characteristically appear with OCT. The healthy regions of the silicone-based phantom comprises three layers: the urothelium, lamina propria and muscularis propria, each containing an appropriate concentration of titanium dioxide to mimic its distinct scattering properties. As well, the layers each possess a unique surface appearance imposed by a textured mold. Within this phantom, pathologic tissue-mimicking regions are created by thickening specific layers or creating inclusions that disrupt the layered appearance of the bladder wall, as is characteristic of bladder carcinomas. This phantom can help to evaluate the efficacy of new OCT systems and software for tumor localization. Moreover, the procedure we have developed is highly generalizable for the creation of OCT-relevant, multi-layer phantoms for tissues that incorporate diseased states characterized by the loss of layered structures.
Intensity and temporal noise characteristics in femtosecond optical parametric amplifiers.

PubMed

Chen, Wei; Fan, Jintao; Ge, Aichen; Song, Huanyu; Song, Youjian; Liu, Bowen; Chai, Lu; Wang, Chingyue; Hu, Minglie

2017-12-11

We characterize the relative intensity noise (RIN) and relative timing jitter (RTJ) between the signal and pump pulses of optical parametric amplifiers (OPAs) seeded by three different seed sources. Compared to a white-light continuum (WLC) seeded- and an optical parametric generator (OPG) seeded OPA, the narrowband CW seeded OPA exhibits the lowest root-mean-square (RMS) RIN and RTJ of 0.79% and 0.32 fs, respectively, integrated from 1 kHz to the Nyquist frequency of 1.25 MHz. An improved numerical model based on a forward Maxwell equation (FME) is built to investigate the transfers of the pump and seed's noise to the resulting OPAs' intensity and temporal fluctuation. Both the experimental and numerical study indicate that the low level of noise from the narrowband CW seeded OPA is attributed to the elimination of the RIN and RTJ coupled from the noise of seed source, being one of the important contributions to RIN and timing jitter in the other two OPAs. The approach to achieve lower level of noise from this CW seeded OPA by driving it close to saturation is also discussed with the same numerical model.
Exploring the Feasibility and Efficacy of a Telehealth Stroke Self-Management Programme: A Pilot Study

PubMed Central

McEwen, Sara; Taylor, Denise

2009-01-01

ABSTRACT Purpose: Moving On after STroke (MOST) is an established self-management programme for persons with stroke and their care partners. Through 18 sessions over 9 weeks, each including discussion and exercise, participants learn about goal-setting, problem-solving, exercise, and community-reintegration skills. This study was undertaken to evaluate the feasibility and efficacy of telehealth delivery of MOST. Method: Efficacy was evaluated using an experimental non-randomized trial comparing a telehealth MOST intervention group (T-MOST) (n = 10) with a waiting list control group (WLC) (n = 8). Outcome measures included the Berg Balance Scale (BBS), the Reintegration to Normal Living Index, the Stroke-Adapted Sickness Impact Profile, Goal Attainment Scaling, and the Geriatric Depression Scale. The feasibility evaluation included attendance rates, focus groups, and facilitator logs. In MOST Telehealth, one co-facilitator was local and the other was connected by videoconference. Results: Attendance rates for persons with stroke (83.9%, SD = 2.6) and care partners (76.7%, SD = 2.9) and participant and facilitator experiences indicated feasibility of this mode of programme delivery. There was a significant difference in BBS scores between the T-MOST group and the WLC group (mean difference −4.27, 95%CI: −6.66 to −1.87). Participants reported additional benefits, including increased motivation and awareness of partners' needs. Videoconferencing was reported to decrease their sense of isolation. Conclusion: It appears feasible to deliver the MOST programme with two facilitators, one connected by videoconference and one in person. In addition, preliminary evidence suggests that the programme is associated with improved well-being in persons with stroke and their care partners. Practitioners delivering self-management programmes may consider wider dissemination using videoconferencing. PMID:20808482
The effect of trauma-focused therapy on the altered T cell distribution in individuals with PTSD: evidence from a randomized controlled trial.

PubMed

Morath, Julia; Gola, Hannah; Sommershof, Annette; Hamuni, Gilava; Kolassa, Stephan; Catani, Claudia; Adenauer, Hannah; Ruf-Leuschner, Martina; Schauer, Maggie; Elbert, Thomas; Groettrup, Marcus; Kolassa, Iris-Tatjana

2014-07-01

Posttraumatic stress disorder (PTSD) is associated with a reduced ratio of naïve cytotoxic T lymphocytes, an increased ratio of memory cytotoxic T lymphocytes, and a reduced proportion of FoxP3(+) regulatory T lymphocytes. This study investigated whether these immunological alterations are reversible through an evidence-based psychotherapeutic treatment. Therefore, 34 individuals with PTSD were randomly assigned to either a treatment condition of 12 sessions narrative exposure therapy (NET) or a waitlist control (WLC) group. PTSD symptoms were significantly reduced in the NET group, but not in the WLC group, four months post-therapy (effect size: Hedges' g = -1.61). One year after therapy, PTSD symptoms were improved even further in the NET group compared to baseline (Hedges' g = -1.96). This symptom improvement was mirrored in an increase in the originally reduced proportion of regulatory T cells (Tregs) in the NET group at the one-year follow-up, when comparing subgroups matched for baseline Treg numbers. However, no changes were found for the initially reduced proportion of CD45RA(+)CCR7(+) naïve T lymphocytes. In conclusion, NET was effective in reducing trauma-related PTSD symptoms and had a positive effect on the proportion of Tregs cells, thus demonstrating an effect of psychotherapy on an immunological level. Yet, the shift in the proportion of naïve and memory T lymphocytes in individuals with PTSD, discussed in the literature as a correlate of premature immunosenescence, was not reversible and thus might render these patients permanently more susceptible to infectious diseases. Copyright © 2014 Elsevier Ltd. All rights reserved.
Internet cognitive behavioural therapy for mixed anxiety and depression: a randomized controlled trial and evidence of effectiveness in primary care.

PubMed

Newby, J M; Mackenzie, A; Williams, A D; McIntyre, K; Watts, S; Wong, N; Andrews, G

2013-12-01

Major depressive disorder (MDD) and generalized anxiety disorder (GAD) have the highest co-morbidity rates within the internalizing disorders cluster, yet no Internet-based cognitive behavioural therapy (iCBT) programme exists for their combined treatment. We designed a six-lesson therapist-assisted iCBT programme for mixed anxiety and depression. Study 1 was a randomized controlled trial (RCT) comparing the iCBT programme (n = 46) versus wait-list control (WLC; n = 53) for patients diagnosed by structured clinical interview with MDD, GAD or co-morbid GAD/MDD. Primary outcome measures were the Patient Health Questionnaire nine-item scale (depression), Generalized Anxiety Disorder seven-item scale (generalized anxiety), Kessler 10-item Psychological Distress scale (distress) and 12-item World Health Organization Disability Assessment Schedule II (disability). The iCBT group was followed up at 3 months post-treatment. In study 2, we investigated the adherence to, and efficacy of the same programme in a primary care setting, where patients (n = 136) completed the programme under the supervision of primary care clinicians. The RCT showed that the iCBT programme was more effective than WLC, with large within- and between-groups effect sizes found (>0.8). Adherence was also high (89%), and gains were maintained at 3-month follow-up. In study 2 in primary care, adherence to the iCBT programme was low (41%), yet effect sizes were large (>0.8). Of the non-completers, 30% experienced benefit. Together, the results show that iCBT is effective and adherence is high in research settings, but there is a problem of adherence when translated into the 'real world'. Future efforts need to be placed on developing improved adherence to iCBT in primary care settings.
Transport spatial model for the definition of green routes for city logistics centers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pamučar, Dragan, E-mail: dpamucar@gmail.com; Gigović, Ljubomir, E-mail: gigoviclj@gmail.com; Ćirović, Goran, E-mail: cirovic@sezampro.rs

This paper presents a transport spatial decision support model (TSDSM) for carrying out the optimization of green routes for city logistics centers. The TSDSM model is based on the integration of the multi-criteria method of Weighted Linear Combination (WLC) and the modified Dijkstra algorithm within a geographic information system (GIS). The GIS is used for processing spatial data. The proposed model makes it possible to plan routes for green vehicles and maximize the positive effects on the environment, which can be seen in the reduction of harmful gas emissions and an increase in the air quality in highly populated areas.more » The scheduling of delivery vehicles is given as a problem of optimization in terms of the parameters of: the environment, health, use of space and logistics operating costs. Each of these input parameters was thoroughly examined and broken down in the GIS into criteria which further describe them. The model presented here takes into account the fact that logistics operators have a limited number of environmentally friendly (green) vehicles available. The TSDSM was tested on a network of roads with 127 links for the delivery of goods from the city logistics center to the user. The model supports any number of available environmentally friendly or environmentally unfriendly vehicles consistent with the size of the network and the transportation requirements. - Highlights: • Model for routing light delivery vehicles in urban areas. • Optimization of green routes for city logistics centers. • The proposed model maximizes the positive effects on the environment. • The model was tested on a real network.« less
Cognitive behavioural group treatment for social anxiety in schizophrenia.

PubMed

Kingsep, Patrick; Nathan, Paula; Castle, David

2003-09-01

Anxiety symptoms reported by individuals with schizophrenia have been traditionally seen as symptoms associated with the principal disorder and therefore not requiring special attention. The primary aim of this paper is to therapeutically target social anxiety symptoms in individuals with schizophrenia in order to determine the effectiveness of the cognitive behavioural group treatment model as an intervention for social anxiety in this participant group. Thirty-three individuals with schizophrenia and co-morbid social anxiety were allocated to a group-based cognitive behaviour (CBGT) intervention or waitlist control (WLC). Baseline, completion and follow-up ratings consist of measures of social anxiety: the Brief Social Phobia Scale (BSPS), Brief Fear of Negative Evaluation scale (BFNE) and the Social Interaction Anxiety Scale (SIAS); measures of general psychopathology: the Calgary Depression Scale for Schizophrenia (CDSS) and Global Severity Index (GSI) from the Brief Symptom Inventory (BSI); and the Quality of Life, Enjoyment and Satisfaction Questionnaire (QLESQ). Pre- and post-treatment measures were subjected to statistical evaluation. All outcome measures displayed statistical improvement in the intervention group compared with no change in the control group. These treatment gains were maintained at follow-up. CBGT for social anxiety in schizophrenia was demonstrated to be effective as an adjunctive treatment for this population.
Analysis of supply chain management of shallots in Medan

NASA Astrophysics Data System (ADS)

Alam, M. C.; Supriana, T.

2018-02-01

Supply chain is important for business. One of supply chain that needs to be studied is the shallots supply chain. Medan have high demand while the supply of shallots is limited. This study aims to analyze the flow of shallots supply chain distribution in Medan. The method used was survey by using questionnaires to shallots producers, collecting traders, distributors, traders as well as government involved in shallots supply chain. Descriptive analysis was used to explain the shallots supply chain distribution flow. The results showed that there are two shallots supply chain model in Medan that was local shallots model and imported shallots model. Local shallots model could be distinguished based on three producer area, those were models of Medan Marelan, Samosir, and Simalungun. Medan Marelan and Simalungun models have seven supply chains, while the Samosir Model has eight supply chains. This condition indicates that the local shallots supply chain management in Medan was not efficient because of the length of the distribution channel. Supply chain imported shallots was more efficient because it had a shorter distribution flow with five supply chains.
A responder analysis of the effects of yoga for individuals with COPD: who benefits and how?

PubMed

Donesky, DorAnne; Melendez, Michelle; Nguyen, Huong Q; Carrieri-Kohlman, Virginia

2012-01-01

We previously reported that a twice-weekly, modified Iyengar yoga program was a safe and viable self-management strategy for patients with chronic obstructive pulmonary disease (COPD). 1 The primary purpose of this exploratory analysis was to classify yoga participants into 1 of 3 responder categories by using minimum clinically important difference (MCID) criteria for each of 3 variables: 6-minute walk distance (6MW), distress related to dyspnea (shortness of breath; DD), and functional performance (FPI). Changes in health-related quality of life (HRQL) and in psychological well-being (anxiety and depression), and participants' self-reported improvements by responder category were also examined. A secondary goal was to identify baseline participant characteristics, including initial randomization assignment that might predict response to treatment. Participants were randomly assigned to either an initial yoga (IY) or an enhanced wait-list control (WLC) group. Those in the WLC group were offered the yoga program immediately following the IY group's participation. Individuals from both groups who completed at least 18 of 24 yoga classes were categorized as responders, partial responders, or non-responders for each of the 3 outcome variables (6MW, DD, FPI) on the basis of MCID criteria. Baseline characteristics and changes in HRQL and psychological well-being were also analyzed. None of the participants demonstrated MCIDs for all 3 outcomes; however, 6 were classified as responders for 2 out-come variables and 4 were classified as non-responders for all 3 outcome variables. Two-thirds of the female participant group and one-third of the male participant group completed the yoga program. DD responders showed increased anxiety levels, whereas anxiety levels of the DD non-responders remained unchanged. FPI responders reported significant improvements in physical function, whereas partial and non-FPI responders noted declined function. Participants assigned to the IY group demonstrated greater benefit from yoga than did those in the W LC group. Although this modified Iyengar yoga program appears to have benefited some individuals with COPD, further studies are required to assess who the intervention works for and under what conditions.

Remarks towards the spectrum of the Heisenberg spin chain type models

NASA Astrophysics Data System (ADS)

Burdík, Č.; Fuksa, J.; Isaev, A. P.; Krivonos, S. O.; Navrátil, O.

2015-05-01

The integrable close and open chain models can be formulated in terms of generators of the Hecke algebras. In this review paper, we describe in detail the Bethe ansatz for the XXX and the XXZ integrable close chain models. We find the Bethe vectors for two-component and inhomogeneous models. We also find the Bethe vectors for the fermionic realization of the integrable XXX and XXZ close chain models by means of the algebraic and coordinate Bethe ansatz. Special modification of the XXZ closed spin chain model ("small polaron model") is considered. Finally, we discuss some questions relating to the general open Hecke chain models.
Workplace Triple P: A controlled evaluation of a parenting intervention for working parents.

PubMed

Sanders, Matthew R; Stallman, Helen M; McHale, Mala

2011-08-01

This paper examined the effects of a parenting intervention targeting working parents called Workplace Triple P. The intervention targeted both parenting and work factors, focusing on key transition times (e.g., from home to work) and trained parents to more effectively manage these transitions. One-hundred-and-twenty-one working parents with children ranging in age from 1-16 years were randomly assigned to either a Workplace Triple P condition (WPTP) or to a waitlist control condition (WLC). Results showed that parents who had received the intervention reported significantly lower levels on measures of personal distress and dysfunctional parenting; and higher levels of work commitment, work satisfaction, and self-efficacy. Implications for the delivery of parenting interventions as employee assistance programs are discussed along with how such interventions can enhance work and family life.
Multi-chain Markov chain Monte Carlo methods for computationally expensive models

NASA Astrophysics Data System (ADS)

Huang, M.; Ray, J.; Ren, H.; Hou, Z.; Bao, J.

2017-12-01

Markov chain Monte Carlo (MCMC) methods are used to infer model parameters from observational data. The parameters are inferred as probability densities, thus capturing estimation error due to sparsity of the data, and the shortcomings of the model. Multiple communicating chains executing the MCMC method have the potential to explore the parameter space better, and conceivably accelerate the convergence to the final distribution. We present results from tests conducted with the multi-chain method to show how the acceleration occurs i.e., for loose convergence tolerances, the multiple chains do not make much of a difference. The ensemble of chains also seems to have the ability to accelerate the convergence of a few chains that might start from suboptimal starting points. Finally, we show the performance of the chains in the estimation of O(10) parameters using computationally expensive forward models such as the Community Land Model, where the sampling burden is distributed over multiple chains.
System Dynamics Modeling for Supply Chain Information Sharing

NASA Astrophysics Data System (ADS)

Feng, Yang

In this paper, we try to use the method of system dynamics to model supply chain information sharing. Firstly, we determine the model boundaries, establish system dynamics model of supply chain before information sharing, analyze the model's simulation results under different changed parameters and suggest improvement proposal. Then, we establish system dynamics model of supply chain information sharing and make comparison and analysis on the two model's simulation results, to show the importance of information sharing in supply chain management. We wish that all these simulations would provide scientific supports for enterprise decision-making.
Proactive Supply Chain Performance Management with Predictive Analytics

PubMed Central

Stefanovic, Nenad

2014-01-01

Today's business climate requires supply chains to be proactive rather than reactive, which demands a new approach that incorporates data mining predictive analytics. This paper introduces a predictive supply chain performance management model which combines process modelling, performance measurement, data mining models, and web portal technologies into a unique model. It presents the supply chain modelling approach based on the specialized metamodel which allows modelling of any supply chain configuration and at different level of details. The paper also presents the supply chain semantic business intelligence (BI) model which encapsulates data sources and business rules and includes the data warehouse model with specific supply chain dimensions, measures, and KPIs (key performance indicators). Next, the paper describes two generic approaches for designing the KPI predictive data mining models based on the BI semantic model. KPI predictive models were trained and tested with a real-world data set. Finally, a specialized analytical web portal which offers collaborative performance monitoring and decision making is presented. The results show that these models give very accurate KPI projections and provide valuable insights into newly emerging trends, opportunities, and problems. This should lead to more intelligent, predictive, and responsive supply chains capable of adapting to future business environment. PMID:25386605
Proactive supply chain performance management with predictive analytics.

PubMed

Stefanovic, Nenad

2014-01-01

Today's business climate requires supply chains to be proactive rather than reactive, which demands a new approach that incorporates data mining predictive analytics. This paper introduces a predictive supply chain performance management model which combines process modelling, performance measurement, data mining models, and web portal technologies into a unique model. It presents the supply chain modelling approach based on the specialized metamodel which allows modelling of any supply chain configuration and at different level of details. The paper also presents the supply chain semantic business intelligence (BI) model which encapsulates data sources and business rules and includes the data warehouse model with specific supply chain dimensions, measures, and KPIs (key performance indicators). Next, the paper describes two generic approaches for designing the KPI predictive data mining models based on the BI semantic model. KPI predictive models were trained and tested with a real-world data set. Finally, a specialized analytical web portal which offers collaborative performance monitoring and decision making is presented. The results show that these models give very accurate KPI projections and provide valuable insights into newly emerging trends, opportunities, and problems. This should lead to more intelligent, predictive, and responsive supply chains capable of adapting to future business environment.
Automated side-chain model building and sequence assignment by template matching.

PubMed

Terwilliger, Thomas C

2003-01-01

An algorithm is described for automated building of side chains in an electron-density map once a main-chain model is built and for alignment of the protein sequence to the map. The procedure is based on a comparison of electron density at the expected side-chain positions with electron-density templates. The templates are constructed from average amino-acid side-chain densities in 574 refined protein structures. For each contiguous segment of main chain, a matrix with entries corresponding to an estimate of the probability that each of the 20 amino acids is located at each position of the main-chain model is obtained. The probability that this segment corresponds to each possible alignment with the sequence of the protein is estimated using a Bayesian approach and high-confidence matches are kept. Once side-chain identities are determined, the most probable rotamer for each side chain is built into the model. The automated procedure has been implemented in the RESOLVE software. Combined with automated main-chain model building, the procedure produces a preliminary model suitable for refinement and extension by an experienced crystallographer.
Network evolution model for supply chain with manufactures as the core.

PubMed

Fang, Haiyang; Jiang, Dali; Yang, Tinghong; Fang, Ling; Yang, Jian; Li, Wu; Zhao, Jing

2018-01-01

Building evolution model of supply chain networks could be helpful to understand its development law. However, specific characteristics and attributes of real supply chains are often neglected in existing evolution models. This work proposes a new evolution model of supply chain with manufactures as the core, based on external market demand and internal competition-cooperation. The evolution model assumes the external market environment is relatively stable, considers several factors, including specific topology of supply chain, external market demand, ecological growth and flow conservation. The simulation results suggest that the networks evolved by our model have similar structures as real supply chains. Meanwhile, the influences of external market demand and internal competition-cooperation to network evolution are analyzed. Additionally, 38 benchmark data sets are applied to validate the rationality of our evolution model, in which, nine manufacturing supply chains match the features of the networks constructed by our model.
Network evolution model for supply chain with manufactures as the core

PubMed Central

Jiang, Dali; Fang, Ling; Yang, Jian; Li, Wu; Zhao, Jing

2018-01-01

Building evolution model of supply chain networks could be helpful to understand its development law. However, specific characteristics and attributes of real supply chains are often neglected in existing evolution models. This work proposes a new evolution model of supply chain with manufactures as the core, based on external market demand and internal competition-cooperation. The evolution model assumes the external market environment is relatively stable, considers several factors, including specific topology of supply chain, external market demand, ecological growth and flow conservation. The simulation results suggest that the networks evolved by our model have similar structures as real supply chains. Meanwhile, the influences of external market demand and internal competition-cooperation to network evolution are analyzed. Additionally, 38 benchmark data sets are applied to validate the rationality of our evolution model, in which, nine manufacturing supply chains match the features of the networks constructed by our model. PMID:29370201
Chains are more flexible under tension

PubMed Central

Carrillo, Jan-Michael Y.; Rubinstein, Michael

2010-01-01

The mechanical response of networks, gels, and brush layers is a manifestation of the elastic properties of the individual macromolecules. Furthermore, the elastic response of macromolecules to an applied force is the foundation of the single-molecule force spectroscopy techniques. The two main classes of models describing chain elasticity include the worm-like and freely-jointed chain models. The selection between these two classes of models is based on the assumptions about chain flexibility. In many experimental situations the choice is not clear and a model describing the crossover between these two limiting classes is therefore in high demand. We are proposing a unified chain deformation model which describes the force-deformation curve in terms of the chain bending constant K and bond length b. This model demonstrates that the worm-like and freely-jointed chain models correspond to two different regimes of polymer deformation and the crossover between these two regimes depends on the chain bending rigidity and the magnitude of the applied force. Polymer chains with bending constant K>1 behave as a worm-like chain under tension in the interval of the applied forces f ≤ KkBT/b and as a freely-jointed chain for f ≥ KkBT/b (kB is the Boltzmann constant and T is the absolute temperature). The proposed crossover expression for chain deformation is in excellent agreement with the results of the molecular dynamics simulations of chain deformation and single-molecule deformation experiments of biological and synthetic macromolecules. PMID:21415940
Mathematical supply-chain modelling: Product analysis of cost and time

NASA Astrophysics Data System (ADS)

Easters, D. J.

2014-03-01

Establishing a mathematical supply-chain model is a proposition that has received attention due to its inherent benefits of evolving global supply-chain efficiencies. This paper discusses the prevailing relationships found within apparel supply-chain environments, and contemplates the complex issues indicated for constituting a mathematical model. Principal results identified within the data suggest, that the multifarious nature of global supply-chain activities require a degree of simplification in order to fully dilate the necessary factors which affect, each sub-section of the chain. Subsequently, the research findings allowed the division of supply-chain components into sub-sections, which amassed a coherent method of product development activity. Concurrently, the supply-chain model was found to allow systematic mathematical formulae analysis, of cost and time, within the multiple contexts of each subsection encountered. The paper indicates the supply-chain model structure, the mathematics, and considers how product analysis of cost and time can improve the comprehension of product lifecycle management.
Spacelab Lyman Alpha-White Light Coronagraph Program

NASA Technical Reports Server (NTRS)

Kohl, J. L.

1986-01-01

The Spacelab Lyman Alpha Coronagraph (SLAC) of the Smithsonian Astrophysical Observatory (SAO) and the White Light Coronagraph (WLC) to be provided by the High Altitude Observatory (HAO) are two separate coronagraphs which would be operated in a joint fashion during Spacelab missions to be flown by the Space Shuttle. The two instruments would be used to perform joint observations of solar coronal structures from 1.2 to 8.0 solar radii from sun-center in vacuum ultraviolet and visible radiations. Temperatures, densities, and flow velocities throughout the solar wing acceleration region of the inner solar corona were measured. The Phase I Definition activity resulted in the successful definition and preliminary design of the experiment/instrumentation subsystem and associated software, ground support equipment and interfaces to the extended required to accurately estimate the scope of the investigation and prepare an Investigational Development Plan; the performance of the necessary functional, operations, and safety analyses necessary to complete the Experiment Requirements document.
Analysis of land suitability for urban development in Ahwaz County in southwestern Iran using fuzzy logic and analytic network process (ANP).

PubMed

Malmir, Maryam; Zarkesh, Mir Masoud Kheirkhah; Monavari, Seyed Masoud; Jozi, Seyed Ali; Sharifi, Esmail

2016-08-01

The ever-increasing development of cities due to population growth and migration has led to unplanned constructions and great changes in urban spatial structure, especially the physical development of cities in unsuitable places, which requires conscious guidance and fundamental organization. It is therefore necessary to identify suitable sites for future development of cities and prevent urban sprawl as one of the main concerns of urban managers and planners. In this study, to determine the suitable sites for urban development in the county of Ahwaz, the effective biophysical and socioeconomic criteria (including 27 sub-criteria) were initially determined based on literature review and interviews with certified experts. In the next step, a database of criteria and sub-criteria was prepared. Standardization of values and unification of scales in map layers were done using fuzzy logic. The criteria and sub-criteria were weighted by analytic network process (ANP) in the Super Decision software. Next, the map layers were overlaid using weighted linear combination (WLC) in the GIS software. According to the research findings, the final land suitability map was prepared with five suitability classes of very high (5.86 %), high (31.93 %), medium (38.61 %), low (17.65 %), and very low (5.95 %). Also, in terms of spatial distribution, suitable lands for urban development are mainly located in the central and southern parts of the Ahwaz County. It is expected that integration of fuzzy logic and ANP model will provide a better decision support tool compared with other models. The developed model can also be used in the land suitability analysis of other cities.
Snap-through instability analysis of dielectric elastomers with consideration of chain entanglements

NASA Astrophysics Data System (ADS)

Zhu, Jiakun; Luo, Jun; Xiao, Zhongmin

2018-06-01

It is widely recognized that the extension limit of polymer chains has a significant effect on the snap-through instability of dielectric elastomers (DEs). The snap-through instability performance of DEs has been extensively studied by two limited-stretch models, i.e., the eight-chain model and Gent model. However, the real polymer networks usually have many entanglements due to the impenetrability of the network chains as well as a finite extensibility resulting from the full stretching of the polymer chains. The effects of entanglements on the snap-through instability of DEs cannot be captured by the previous two limited-stretch models. In this paper, the nonaffine model proposed by Davidson and Goulbourne is adopted to characterize the influence of entanglements and extension limit of the polymer chains. It is demonstrated that the nonaffine model is almost identical to the eight-chain model and is close to the Gent model if we ignore the effects of chain entanglements and adopt the affine assumption. The suitability of the nonaffine model to characterize the mechanical behavior of elastomers is validated by fitting the experimental results reported in the open literature. After that, the snap-through stability performance of an ideal DE membrane under equal-biaxial prestretches is studied with the nonaffine model. It is revealed that besides the prestretch and chain extension limit, the chain entanglements can markedly influence the snap-through instability and the path to failure of DEs. These results provide a more comprehensive understanding on the snap-through instability of a DE and may be helpful to guide the design of DE devices.
Long-distance entanglement and quantum teleportation in XX spin chains

DOE Office of Scientific and Technical Information (OSTI.GOV)

Campos Venuti, L.; Giampaolo, S. M.; CNR-INFM Coherentia, Napoli

2007-11-15

Isotropic XX models of one-dimensional spin-1/2 chains are investigated with the aim to elucidate the formal structure and the physical properties that allow these systems to act as channels for long-distance, high-fidelity quantum teleportation. We introduce two types of models: (i) open, dimerized XX chains, and (ii) open XX chains with small end bonds. For both models we obtain the exact expressions for the end-to-end correlations and the scaling of the energy gap with the length of the chain. We determine the end-to-end concurrence and show that model (i) supports true long-distance entanglement at zero temperature, while model (ii) supportsmore » 'quasi-long-distance' entanglement that slowly falls off with the size of the chain. Due to the different scalings of the gaps, respectively exponential for model (i) and algebraic in model (ii), we demonstrate that the latter allows for efficient qubit teleportation with high fidelity in sufficiently long chains even at moderately low temperatures.« less
A research protocol for a pilot randomized controlled trial designed to examine the feasibility of a couple-based mind-body intervention for patients with metastatic lung cancer and their partners.

PubMed

Milbury, Kathrin; Tsao, Anne S; Liao, Zhongxing; Owns, April; Engle, Rosalinda; Gonzalez, Edrea A; Bruera, Eduardo; Cohen, Lorenzo

2018-01-01

Given the generally incurable nature of metastatic non-small cell lung cancer (mNSCLC), patients and their romantic partners are at risk for existential/spiritual distress. Although a handful of dyadic psychosocial interventions for lung cancer patients and their caregivers exist, none of them target spiritual well-being. Informed by the mindfulness-based intervention literature and our pilot work in couples affected by lung cancer, we developed a brief couple-based mind-body (CBMB) intervention. The primary aim of this research protocol is to determine the feasibility of implementing the CBMB intervention versus an active control (AC) or wait list control (WLC) group in patients with mNSCLC and their partners using a randomized controlled trial design. Seventy-five patients with mNSCLC receiving treatment and their partners are randomized to the CBMB intervention, an AC or a WLC group. Those in the CBMB intervention and AC groups receive four intervention sessions of 60 min each over 4 weeks and complete weekly homework assignments. The first session is delivered in person, and the remaining sessions are delivered via videoconference. The dyads in the AC group discuss cancer-related and personal growth concerns with the interventionist but are not taught coping skills. Patients and partners in all groups complete baseline assessments of quality of life (QOL) prior to randomization. Follow-up assessments are performed 4 weeks and then again 3 months later. The primary outcome is feasibility (i.e., ≥ 30% of eligible couples consent, ≥ 70% of enrolled couples are retained, and ≥ 50% of all CBMB and AC sessions are attended). We will also perform primarily descriptive analyses of the self-reported outcomes (e.g., spiritual well-being and psychological distress) and explore potential intervention mediators (i.e., compassion, communication, mindfulness, and closeness) to inform a larger, future trial. This trial will provide important information regarding the feasibility of a behavioral intervention in a vulnerable yet understudied population using videoconferencing and descriptive data regarding spiritual well-being and other indices of QOL in both mNSCLC patients and their partners. ClinicalTrials.gov NCT02596490.
Assessment of ecological passages along road networks within the Mediterranean forest using GIS-based multi criteria evaluation approach.

PubMed

Gülci, Sercan; Akay, Abdullah Emin

2015-12-01

Major roads cause barrier effect and fragmentation on wildlife habitats that are suitable places for feeding, mating, socializing, and hiding. Due to wildlife collisions (Wc), human-wildlife conflicts result in lost lives and loss of biodiversity. Geographical information system (GIS)-based multi criteria evaluation (MCE) methods have been successfully used in short-term planning of road networks considering wild animals. Recently, wildlife passages have been effectively utilized as road engineering structures provide quick and certain solutions for traffic safety and wildlife conservation problems. GIS-based MCE methods provide decision makers with optimum location for ecological passages based on habitat suitability models (HSMs) that classify the areas based on ecological requirements of target species. In this study, ecological passages along Motorway 52 within forested areas in Mediterranean city of Osmaniye in Turkey were evaluated. Firstly, HSM coupled with nine eco-geographic decision variables were developed based on ecological requirements of roe deer (Capreolus capreolus) that were chosen as target species. Then specified decision variables were evaluated using GIS-based weighted linear combination (WLC) method to estimate movement corridors and mitigation points along the motorway. In the solution process, two linkage nodes were evaluated for eco-passages which were determined based on the least-cost movement corridor intersecting with the motorway. One of the passages was identified as a natural wildlife overpass while the other was suggested as underpass construction. The results indicated that computer-based models provide accurate and quick solutions for positioning ecological passages to reduce environmental effects of road networks on wild animals.
Simple model of inhibition of chain-branching combustion processes

NASA Astrophysics Data System (ADS)

Babushok, Valeri I.; Gubernov, Vladimir V.; Minaev, Sergei S.; Miroshnichenko, Taisia P.

2017-11-01

A simple kinetic model has been suggested to describe the inhibition and extinction of flame propagation in reaction systems with chain-branching reactions typical for hydrocarbon systems. The model is based on the generalised model of the combustion process with chain-branching reaction combined with the one-stage reaction describing the thermal mode of flame propagation with the addition of inhibition reaction steps. Inhibitor addition suppresses the radical overshoot in flame and leads to the change of reaction mode from the chain-branching reaction to a thermal mode of flame propagation. With the increase of inhibitor the transition of chain-branching mode of reaction to the reaction with straight-chains (non-branching chain reaction) is observed. The inhibition part of the model includes a block of three reactions to describe the influence of the inhibitor. The heat losses are incorporated into the model via Newton cooling. The flame extinction is the result of the decreased heat release of inhibited reaction processes and the suppression of radical overshoot with the further decrease of the reaction rate due to the temperature decrease and mixture dilution. A comparison of the results of modelling laminar premixed methane/air flames inhibited by potassium bicarbonate (gas phase model, detailed kinetic model) with the results obtained using the suggested simple model is presented. The calculations with the detailed kinetic model demonstrate the following modes of combustion process: (1) flame propagation with chain-branching reaction (with radical overshoot, inhibitor addition decreases the radical overshoot down to the equilibrium level); (2) saturation of chemical influence of inhibitor, and (3) transition to thermal mode of flame propagation (non-branching chain mode of reaction). The suggested simple kinetic model qualitatively reproduces the modes of flame propagation with the addition of the inhibitor observed using detailed kinetic models.
Teaching Supply Chain Management Complexities: A SCOR Model Based Classroom Simulation

ERIC Educational Resources Information Center

Webb, G. Scott; Thomas, Stephanie P.; Liao-Troth, Sara

2014-01-01

The SCOR (Supply Chain Operations Reference) Model Supply Chain Classroom Simulation is an in-class experiential learning activity that helps students develop a holistic understanding of the processes and challenges of supply chain management. The simulation has broader learning objectives than other supply chain related activities such as the…
A BENCHMARKING ANALYSIS FOR FIVE RADIONUCLIDE VADOSE ZONE MODELS (CHAIN, MULTIMED_DP, FECTUZ, HYDRUS, AND CHAIN 2D) IN SOIL SCREENING LEVEL CALCULATIONS

EPA Science Inventory

Five radionuclide vadose zone models with different degrees of complexity (CHAIN, MULTIMED_DP, FECTUZ, HYDRUS, and CHAIN 2D) were selected for use in soil screening level (SSL) calculations. A benchmarking analysis between the models was conducted for a radionuclide (99Tc) rele...

Thermodynamic perturbation theory for fused sphere hard chain fluids using nonadditive interactions

NASA Astrophysics Data System (ADS)

Abu-Sharkh, Basel F.; Sunaidi, Abdallah; Hamad, Esam Z.

2004-03-01

A model is developed for the equation of state of fused chains based on Wertheim thermodynamic perturbation theory and nonadditive size interactions. The model also assumes that the structure (represented by the radial distribution function) of the fused chain fluid is the same as that of the touching hard sphere chain fluid. The model is completely based on spherical additive and nonadditive size interactions. The model has the advantage of offering good agreement with simulation data while at the same time being independent of fitted parameters. The model is most accurate for short chains, small values of Δ (slightly fused spheres) and at intermediate (liquidlike) densities.
Modelling a suitable location for Urban Solid Waste Management using AHP method and GIS -A geospatial approach and MCDM Model

NASA Astrophysics Data System (ADS)

Iqbal, M.; Islam, A.; Hossain, A.; Mustaque, S.

2016-12-01

Multi-Criteria Decision Making(MCDM) is advanced analytical method to evaluate appropriate result or decision from multiple criterion environment. Present time in advanced research, MCDM technique is progressive analytical process to evaluate a logical decision from various conflict. In addition, Present day Geospatial approach (e.g. Remote sensing and GIS) also another advanced technical approach in a research to collect, process and analyze various spatial data at a time. GIS and Remote sensing together with the MCDM technique could be the best platform to solve a complex decision making process. These two latest process combined very effectively used in site selection for solid waste management in urban policy. The most popular MCDM technique is Weighted Linear Method (WLC) where Analytical Hierarchy Process (AHP) is another popular and consistent techniques used in worldwide as dependable decision making. Consequently, the main objective of this study is improving a AHP model as MCDM technique with Geographic Information System (GIS) to select a suitable landfill site for urban solid waste management. Here AHP technique used as a MCDM tool to select the best suitable landfill location for urban solid waste management. To protect the urban environment in a sustainable way municipal waste needs an appropriate landfill site considering environmental, geological, social and technical aspect of the region. A MCDM model generate from five class related which related to environmental, geological, social and technical using AHP method and input the result set in GIS for final model location for urban solid waste management. The final suitable location comes out that 12.2% of the area corresponds to 22.89 km2 considering the total study area. In this study, Keraniganj sub-district of Dhaka district in Bangladesh is consider as study area which is densely populated city currently undergoes an unmanaged waste management system especially the suitable landfill sites for waste dumping site.
Computational modelling of cell chain migration reveals mechanisms that sustain follow-the-leader behaviour

PubMed Central

Wynn, Michelle L.; Kulesa, Paul M.; Schnell, Santiago

2012-01-01

Follow-the-leader chain migration is a striking cell migratory behaviour observed during vertebrate development, adult neurogenesis and cancer metastasis. Although cell–cell contact and extracellular matrix (ECM) cues have been proposed to promote this phenomenon, mechanisms that underlie chain migration persistence remain unclear. Here, we developed a quantitative agent-based modelling framework to test mechanistic hypotheses of chain migration persistence. We defined chain migration and its persistence based on evidence from the highly migratory neural crest model system, where cells within a chain extend and retract filopodia in short-lived cell contacts and move together as a collective. In our agent-based simulations, we began with a set of agents arranged as a chain and systematically probed the influence of model parameters to identify factors critical to the maintenance of the chain migration pattern. We discovered that chain migration persistence requires a high degree of directional bias in both lead and follower cells towards the target. Chain migration persistence was also promoted when lead cells maintained cell contact with followers, but not vice-versa. Finally, providing a path of least resistance in the ECM was not sufficient alone to drive chain persistence. Our results indicate that chain migration persistence depends on the interplay of directional cell movement and biased cell–cell contact. PMID:22219399
How to fold a spin chain: Integrable boundaries of the Heisenberg XXX and Inozemtsev hyperbolic models

NASA Astrophysics Data System (ADS)

De La Rosa Gomez, Alejandro; MacKay, Niall; Regelskis, Vidas

2017-04-01

We present a general method of folding an integrable spin chain, defined on a line, to obtain an integrable open spin chain, defined on a half-line. We illustrate our method through two fundamental models with sl2 Lie algebra symmetry: the Heisenberg XXX and the Inozemtsev hyperbolic spin chains. We obtain new long-range boundary Hamiltonians and demonstrate that they exhibit Yangian symmetries, thus ensuring integrability of the models we obtain. The method presented provides a ;bottom-up; approach for constructing integrable boundaries and can be applied to any spin chain model.
Molecular modeling of calmodulin: a comparison with crystallographic data

NASA Technical Reports Server (NTRS)

McDonald, J. J.; Rein, R.

1989-01-01

Two methods of side-chain placement on a modeled protein have been examined. Two molecular models of calmodulin were constructed that differ in the treatment of side chains prior to optimization of the molecule. A virtual bond analysis program developed by Purisima and Scheraga was used to determine the backbone conformation based on 2.2 angstroms resolution C alpha coordinates for the molecules. In the first model, side chains were initially constructed in an extended conformation. In the second model, a conformational grid search technique was employed. Calcium ions were treated explicitly during energy optimization using CHARMM. The models are compared to a recently published refined crystal structure of calmodulin. The results indicate that the initial choices for side-chains, but also significant effects on the main-chain conformation and supersecondary structure. The conformational differences are discussed. Analysis of these and other methods makes possible the formulation of a methodology for more appropriate side-chain placement in modeled proteins.
Modeling methodology for supply chain synthesis and disruption analysis

NASA Astrophysics Data System (ADS)

Wu, Teresa; Blackhurst, Jennifer

2004-11-01

The concept of an integrated or synthesized supply chain is a strategy for managing today's globalized and customer driven supply chains in order to better meet customer demands. Synthesizing individual entities into an integrated supply chain can be a challenging task due to a variety of factors including conflicting objectives, mismatched incentives and constraints of the individual entities. Furthermore, understanding the effects of disruptions occurring at any point in the system is difficult when working toward synthesizing supply chain operations. Therefore, the goal of this research is to present a modeling methodology to manage the synthesis of a supply chain by linking hierarchical levels of the system and to model and analyze disruptions in the integrated supply chain. The contribution of this research is threefold: (1) supply chain systems can be modeled hierarchically (2) the performance of synthesized supply chain system can be evaluated quantitatively (3) reachability analysis is used to evaluate the system performance and verify whether a specific state is reachable, allowing the user to understand the extent of effects of a disruption.
DOE Office of Scientific and Technical Information (OSTI.GOV)

Sun, Amy Cha-Tien; Downes, Paula Sue; Heinen, Russell

Analysis of chemical supply chains is an inherently complex task, given the dependence of these supply chains on multiple infrastructure systems (e.g., the petroleum sector, transportation, etc.). This effort requires data and information at various levels of resolution, ranging from network-level distribution systems to individual chemical reactions. Sandia National Laboratories (Sandia) has integrated its existing simulation and infrastructure analysis capabilities with chemical data models to analyze the chemical supply chains of several nationally critical chemical commodities. This paper describes how Sandia models the ethylene supply chain; that is, the supply chain for the most widely used raw material for plasticsmore » production including a description of the types of data and modeling capabilities that are required to represent the ethylene supply chain. The paper concludes with a description of Sandia's use the model to project how the supply chain would be affected by and adapt to a disruptive scenario hurricane.« less
Research on BIM-based building information value chain reengineering

NASA Astrophysics Data System (ADS)

Hui, Zhao; Weishuang, Xie

2017-04-01

The achievement of value and value-added factor to the building engineering information is accomplished through a chain-flow, that is, building the information value chain. Based on the deconstruction of the information chain on the construction information in the traditional information mode, this paper clarifies the value characteristics and requirements of each stage of the construction project. In order to achieve building information value-added, the paper deconstructs the traditional building information value chain, reengineer the information value chain model on the basis of the theory and techniques of BIM, to build value-added management model and analyse the value of the model.
Flexibility evaluation of multiechelon supply chains.

PubMed

Almeida, João Flávio de Freitas; Conceição, Samuel Vieira; Pinto, Luiz Ricardo; de Camargo, Ricardo Saraiva; Júnior, Gilberto de Miranda

2018-01-01

Multiechelon supply chains are complex logistics systems that require flexibility and coordination at a tactical level to cope with environmental uncertainties in an efficient and effective manner. To cope with these challenges, mathematical programming models are developed to evaluate supply chain flexibility. However, under uncertainty, supply chain models become complex and the scope of flexibility analysis is generally reduced. This paper presents a unified approach that can evaluate the flexibility of a four-echelon supply chain via a robust stochastic programming model. The model simultaneously considers the plans of multiple business divisions such as marketing, logistics, manufacturing, and procurement, whose goals are often conflicting. A numerical example with deterministic parameters is presented to introduce the analysis, and then, the model stochastic parameters are considered to evaluate flexibility. The results of the analysis on supply, manufacturing, and distribution flexibility are presented. Tradeoff analysis of demand variability and service levels is also carried out. The proposed approach facilitates the adoption of different management styles, thus improving supply chain resilience. The model can be extended to contexts pertaining to supply chain disruptions; for example, the model can be used to explore operation strategies when subtle events disrupt supply, manufacturing, or distribution.
Flexibility evaluation of multiechelon supply chains

PubMed Central

Conceição, Samuel Vieira; Pinto, Luiz Ricardo; de Camargo, Ricardo Saraiva; Júnior, Gilberto de Miranda

2018-01-01

Multiechelon supply chains are complex logistics systems that require flexibility and coordination at a tactical level to cope with environmental uncertainties in an efficient and effective manner. To cope with these challenges, mathematical programming models are developed to evaluate supply chain flexibility. However, under uncertainty, supply chain models become complex and the scope of flexibility analysis is generally reduced. This paper presents a unified approach that can evaluate the flexibility of a four-echelon supply chain via a robust stochastic programming model. The model simultaneously considers the plans of multiple business divisions such as marketing, logistics, manufacturing, and procurement, whose goals are often conflicting. A numerical example with deterministic parameters is presented to introduce the analysis, and then, the model stochastic parameters are considered to evaluate flexibility. The results of the analysis on supply, manufacturing, and distribution flexibility are presented. Tradeoff analysis of demand variability and service levels is also carried out. The proposed approach facilitates the adoption of different management styles, thus improving supply chain resilience. The model can be extended to contexts pertaining to supply chain disruptions; for example, the model can be used to explore operation strategies when subtle events disrupt supply, manufacturing, or distribution. PMID:29584755
Primitive-path statistics of entangled polymers: mapping multi-chain simulations onto single-chain mean-field models

NASA Astrophysics Data System (ADS)

Steenbakkers, Rudi J. A.; Tzoumanekas, Christos; Li, Ying; Liu, Wing Kam; Kröger, Martin; Schieber, Jay D.

2014-01-01

We present a method to map the full equilibrium distribution of the primitive-path (PP) length, obtained from multi-chain simulations of polymer melts, onto a single-chain mean-field ‘target’ model. Most previous works used the Doi-Edwards tube model as a target. However, the average number of monomers per PP segment, obtained from multi-chain PP networks, has consistently shown a discrepancy of a factor of two with respect to tube-model estimates. Part of the problem is that the tube model neglects fluctuations in the lengths of PP segments, the number of entanglements per chain and the distribution of monomers among PP segments, while all these fluctuations are observed in multi-chain simulations. Here we use a recently proposed slip-link model, which includes fluctuations in all these variables as well as in the spatial positions of the entanglements. This turns out to be essential to obtain qualitative and quantitative agreement with the equilibrium PP-length distribution obtained from multi-chain simulations. By fitting this distribution, we are able to determine two of the three parameters of the model, which govern its equilibrium properties. This mapping is executed for four different linear polymers and for different molecular weights. The two parameters are found to depend on chemistry, but not on molecular weight. The model predicts a constant plateau modulus minus a correction inversely proportional to molecular weight. The value for well-entangled chains, with the parameters determined ab initio, lies in the range of experimental data for the materials investigated.
Steric interactions determine side-chain conformations in protein cores.

PubMed

Caballero, D; Virrueta, A; O'Hern, C S; Regan, L

2016-09-01

We investigate the role of steric interactions in defining side-chain conformations in protein cores. Previously, we explored the strengths and limitations of hard-sphere dipeptide models in defining sterically allowed side-chain conformations and recapitulating key features of the side-chain dihedral angle distributions observed in high-resolution protein structures. Here, we show that modeling residues in the context of a particular protein environment, with both intra- and inter-residue steric interactions, is sufficient to specify which of the allowed side-chain conformations is adopted. This model predicts 97% of the side-chain conformations of Leu, Ile, Val, Phe, Tyr, Trp and Thr core residues to within 20°. Although the hard-sphere dipeptide model predicts the observed side-chain dihedral angle distributions for both Thr and Ser, the model including the protein environment predicts side-chain conformations to within 20° for only 60% of core Ser residues. Thus, this approach can identify the amino acids for which hard-sphere interactions alone are sufficient and those for which additional interactions are necessary to accurately predict side-chain conformations in protein cores. We also show that our approach can predict alternate side-chain conformations of core residues, which are supported by the observed electron density. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.
Modeling sustainability in renewable energy supply chain systems

NASA Astrophysics Data System (ADS)

Xie, Fei

This dissertation aims at modeling sustainability of renewable fuel supply chain systems against emerging challenges. In particular, the dissertation focuses on the biofuel supply chain system design, and manages to develop advanced modeling framework and corresponding solution methods in tackling challenges in sustaining biofuel supply chain systems. These challenges include: (1) to integrate "environmental thinking" into the long-term biofuel supply chain planning; (2) to adopt multimodal transportation to mitigate seasonality in biofuel supply chain operations; (3) to provide strategies in hedging against uncertainty from conversion technology; and (4) to develop methodologies in long-term sequential planning of the biofuel supply chain under uncertainties. All models are mixed integer programs, which also involves multi-objective programming method and two-stage/multistage stochastic programming methods. In particular for the long-term sequential planning under uncertainties, to reduce the computational challenges due to the exponential expansion of the scenario tree, I also developed efficient ND-Max method which is more efficient than CPLEX and Nested Decomposition method. Through result analysis of four independent studies, it is found that the proposed modeling frameworks can effectively improve the economic performance, enhance environmental benefits and reduce risks due to systems uncertainties for the biofuel supply chain systems.
Chemically Realistic Tetrahedral Lattice Models for Polymer Chains: Application to Polyethylene Oxide.

PubMed

Dietschreit, Johannes C B; Diestler, Dennis J; Knapp, Ernst W

2016-05-10

To speed up the generation of an ensemble of poly(ethylene oxide) (PEO) polymer chains in solution, a tetrahedral lattice model possessing the appropriate bond angles is used. The distance between noncovalently bonded atoms is maintained at realistic values by generating chains with an enhanced degree of self-avoidance by a very efficient Monte Carlo (MC) algorithm. Potential energy parameters characterizing this lattice model are adjusted so as to mimic realistic PEO polymer chains in water simulated by molecular dynamics (MD), which serves as a benchmark. The MD data show that PEO chains have a fractal dimension of about two, in contrast to self-avoiding walk lattice models, which exhibit the fractal dimension of 1.7. The potential energy accounts for a mild hydrophobic effect (HYEF) of PEO and for a proper setting of the distribution between trans and gauche conformers. The potential energy parameters are determined by matching the Flory radius, the radius of gyration, and the fraction of trans torsion angles in the chain. A gratifying result is the excellent agreement of the pair distribution function and the angular correlation for the lattice model with the benchmark distribution. The lattice model allows for the precise computation of the torsional entropy of the chain. The generation of polymer conformations of the adjusted lattice model is at least 2 orders of magnitude more efficient than MD simulations of the PEO chain in explicit water. This method of generating chain conformations on a tetrahedral lattice can also be applied to other types of polymers with appropriate adjustment of the potential energy function. The efficient MC algorithm for generating chain conformations on a tetrahedral lattice is available for download at https://github.com/Roulattice/Roulattice .
Calculation of single chain cellulose elasticity using fully atomistic modeling

Treesearch

Xiawa Wu; Robert J. Moon; Ashlie Martini

2011-01-01

Cellulose nanocrystals, a potential base material for green nanocomposites, are ordered bundles of cellulose chains. The properties of these chains have been studied for many years using atomic-scale modeling. However, model predictions are difficult to interpret because of the significant dependence of predicted properties on model details. The goal of this study is...
A Simulation Model Articulation of the REA Ontology

NASA Astrophysics Data System (ADS)

Laurier, Wim; Poels, Geert

This paper demonstrates how the REA enterprise ontology can be used to construct simulation models for business processes, value chains and collaboration spaces in supply chains. These models support various high-level and operational management simulation applications, e.g. the analysis of enterprise sustainability and day-to-day planning. First, the basic constructs of the REA ontology and the ExSpect modelling language for simulation are introduced. Second, collaboration space, value chain and business process models and their conceptual dependencies are shown, using the ExSpect language. Third, an exhibit demonstrates the use of value chain models in predicting the financial performance of an enterprise.
Modelling a flows in supply chain with analytical models: Case of a chemical industry

NASA Astrophysics Data System (ADS)

Benhida, Khalid; Azougagh, Yassine; Elfezazi, Said

2016-02-01

This study is interested on the modelling of the logistics flows in a supply chain composed on a production sites and a logistics platform. The contribution of this research is to develop an analytical model (integrated linear programming model), based on a case study of a real company operating in the phosphate field, considering a various constraints in this supply chain to resolve the planning problems for a better decision-making. The objectives of this model is to determine and define the optimal quantities of different products to route, to and from the various entities in the supply chain studied.
Analytical model of multi-planetary resonant chains and constraints on migration scenarios

NASA Astrophysics Data System (ADS)

Delisle, J.-B.

2017-09-01

Resonant chains are groups of planets for which each pair is in resonance, with an orbital period ratio locked at a rational value (2/1, 3/2, etc.). Such chains naturally form as a result of convergent migration of the planets in the proto-planetary disk. In this article, I present an analytical model of resonant chains of any number of planets. Using this model, I show that a system captured in a resonant chain can librate around several possible equilibrium configurations. The probability of capture around each equilibrium depends on how the chain formed, and especially on the order in which the planets have been captured in the chain. Therefore, for an observed resonant chain, knowing around which equilibrium the chain is librating allows for constraints to be put on the formation and migration scenario of the system. I apply this reasoning to the four planets orbiting Kepler-223 in a 3:4:6:8 resonant chain. I show that the system is observed around one of the six equilibria predicted by the analytical model. Using N-body integrations, I show that the most favorable scenario to reproduce the observed configuration is to first capture the two intermediate planets, then the outermost, and finally the innermost.
Using SCOR as a Supply Chain Management Framework for Government Agency Contract Requirements

NASA Technical Reports Server (NTRS)

Paxton, Joseph; Tucker, Brian

2010-01-01

This paper will present a model that uses the Supply-Chain Operations Reference (SCOR) model as a foundation for a framework to illustrate the information needed throughout a product lifecycle to support a healthy supply chain management function and the subsequent contract requirements to enable it. It will also show where in the supply chain the information must be extracted. The ongoing case study used to exemplify the model is NASA's (National Aeronautics and Space Administration) Ares I program for human spaceflight. Effective supply chain management and contract requirements are ongoing opportunities for continuous improvement within government agencies, specifically development of systems for human spaceflight operations. Multiple reports from the Government Accountability Office (GAO) reinforce this importance. The SCOR model is a framework for describing a supply chain with process building blocks and business activities. It provides a set of metrics for measuring supply chain performance and best practices for continuously improving. This paper expands the application of the SCOR to also provide the framework for defining information needed from different levels of the supply chain and at different phases of the lifecycle. These needs can be incorporated into contracts to enable more effective supply chain management. Depending on the phase of the lifecycle, effective supply chain management will require involvement from different levels of the organization and different levels of the supply chain.
Diy Geospatial Web Service Chains: Geochaining Make it Easy

NASA Astrophysics Data System (ADS)

Wu, H.; You, L.; Gui, Z.

2011-08-01

It is a great challenge for beginners to create, deploy and utilize a Geospatial Web Service Chain (GWSC). People in Computer Science are usually not familiar with geospatial domain knowledge. Geospatial practitioners may lack the knowledge about web services and service chains. The end users may lack both. However, integrated visual editing interfaces, validation tools, and oneclick deployment wizards may help to lower the learning curve and improve modelling skills so beginners will have a better experience. GeoChaining is a GWSC modelling tool designed and developed based on these ideas. GeoChaining integrates visual editing, validation, deployment, execution etc. into a unified platform. By employing a Virtual Globe, users can intuitively visualize raw data and results produced by GeoChaining. All of these features allow users to easily start using GWSC, regardless of their professional background and computer skills. Further, GeoChaining supports GWSC model reuse, meaning that an entire GWSC model created or even a specific part can be directly reused in a new model. This greatly improves the efficiency of creating a new GWSC, and also contributes to the sharing and interoperability of GWSC.

Influence of chain rigidity on the conformation of model lipid membranes in the presence of cylindrical nanoparticle inclusions

NASA Astrophysics Data System (ADS)

Diloreto, Chris; Wickham, Robert

2012-02-01

We employ real-space self-consistent field theory to study the conformation of model lipid membranes in the presence of solvent and cylindrical nanoparticle inclusions (''peptides''). Whereas it is common to employ a polymeric Gaussian chain model for the lipids, here we model the lipids as persistent, worm-like chains. Our motivation is to develop a more realistic field theory to describe the action of pore-forming anti-microbial peptides that disrupt the bacterial cell membrane. We employ operator-splitting and a pseudo-spectral algorithm, using SpharmonicKit for the chain tangent degrees of freedom, to solve for the worm-like chain propagator. The peptides, modelled using a mask function, have a surface patterned with hydrophobic and hydrophillic patches, but no charge. We examine the role chain rigidity plays in the hydrophobic mismatch, the membrane-mediated interaction between two peptides, the size and structure of pores formed by peptide aggregates, and the free-energy barrier for peptide insertion into the membrane. Our results suggest that chain rigidity influences both the pore structure and the mechanism of pore formation.
Stochastic entangled chain dynamics of dense polymer solutions.

PubMed

Kivotides, Demosthenes; Wilkin, S Louise; Theofanous, Theo G

2010-10-14

We propose an adjustable-parameter-free, entangled chain dynamics model of dense polymer solutions. The model includes the self-consistent dynamics of molecular chains and solvent by describing the former via coarse-grained polymer dynamics that incorporate hydrodynamic interaction effects, and the latter via the forced Stokes equation. Real chain elasticity is modeled via the inclusion of a Pincus regime in the polymer's force-extension curve. Excluded volume effects are taken into account via the combined action of coarse-grained intermolecular potentials and explicit geometric tracking of chain entanglements. We demonstrate that entanglements are responsible for a new (compared to phantom chain dynamics), slow relaxation mode whose characteristic time scale agrees very well with experiment. Similarly good agreement between theory and experiment is also obtained for the equilibrium chain size. We develop methods for the solution of the model in periodic flow domains and apply them to the computation of entangled polymer solutions in equilibrium. We show that the number of entanglements Π agrees well with the number of entanglements expected on the basis of tube theory, satisfactorily reproducing the latter's scaling of Π with the polymer volume fraction φ. Our model predicts diminishing chain size with concentration, thus vindicating Flory's suggestion of excluded volume effects screening in dense solutions. The predicted scaling of chain size with φ is consistent with the heuristic, Flory theory based value.
A chain-retrieval model for voluntary task switching.

PubMed

Vandierendonck, André; Demanet, Jelle; Liefooghe, Baptist; Verbruggen, Frederick

2012-09-01

To account for the findings obtained in voluntary task switching, this article describes and tests the chain-retrieval model. This model postulates that voluntary task selection involves retrieval of task information from long-term memory, which is then used to guide task selection and task execution. The model assumes that the retrieved information consists of acquired sequences (or chains) of tasks, that selection may be biased towards chains containing more task repetitions and that bottom-up triggered repetitions may overrule the intended task. To test this model, four experiments are reported. In Studies 1 and 2, sequences of task choices and the corresponding transition sequences (task repetitions or switches) were analyzed with the help of dependency statistics. The free parameters of the chain-retrieval model were estimated on the observed task sequences and these estimates were used to predict autocorrelations of tasks and transitions. In Studies 3 and 4, sequences of hand choices and their transitions were analyzed similarly. In all studies, the chain-retrieval model yielded better fits and predictions than statistical models of event choice. In applications to voluntary task switching (Studies 1 and 2), all three parameters of the model were needed to account for the data. When no task switching was required (Studies 3 and 4), the chain-retrieval model could account for the data with one or two parameters clamped to a neutral value. Implications for our understanding of voluntary task selection and broader theoretical implications are discussed. Copyright © 2012 Elsevier Inc. All rights reserved.
How Can Students Generalize the Chain Rule? The Roles of Abduction in Mathematical Modeling

ERIC Educational Resources Information Center

Park, Jin Hyeong; Lee, Kyeong-Hwa

2016-01-01

The purpose of this study is to design a modeling task to facilitate students' inquiries into the chain rule in calculus and to analyze the results after implementation of the task. In this study, we take a modeling approach to the teaching and learning of the chain rule by facilitating the generalization of students' models and modeling…
Demand Activated Manufacturing Architecture (DAMA) model for supply chain collaboration

DOE Office of Scientific and Technical Information (OSTI.GOV)

CHAPMAN,LEON D.; PETERSEN,MARJORIE B.

The Demand Activated Manufacturing Architecture (DAMA) project during the last five years of work with the U.S. Integrated Textile Complex (retail, apparel, textile, and fiber sectors) has developed an inter-enterprise architecture and collaborative model for supply chains. This model will enable improved collaborative business across any supply chain. The DAMA Model for Supply Chain Collaboration is a high-level model for collaboration to achieve Demand Activated Manufacturing. The five major elements of the architecture to support collaboration are (1) activity or process, (2) information, (3) application, (4) data, and (5) infrastructure. These five elements are tied to the application of themore » DAMA architecture to three phases of collaboration - prepare, pilot, and scale. There are six collaborative activities that may be employed in this model: (1) Develop Business Planning Agreements, (2) Define Products, (3) Forecast and Plan Capacity Commitments, (4) Schedule Product and Product Delivery, (5) Expedite Production and Delivery Exceptions, and (6) Populate Supply Chain Utility. The Supply Chain Utility is a set of applications implemented to support collaborative product definition, forecast visibility, planning, scheduling, and execution. The DAMA architecture and model will be presented along with the process for implementing this DAMA model.« less
Simulating the Afghanistan-Pakistan opium supply chain

DOE Office of Scientific and Technical Information (OSTI.GOV)

Watkins, Jennifer H; MacKerrow, Edward P; Merritt, Terence M

2010-04-08

This paper outlines an opium supply chain using the Hilmand province of Afghanistan as exemplar. The opium supply chain model follows the transformation of opium poppy seed through cultivation and chemical alteration to brown heroin base. The purpose of modeling and simulating the Afghanistan-Pakistan opium supply chain is to discover and test strategies that will disrupt this criminal enterprise.
A coupled two-dimensional main chain torsional potential for protein dynamics: generation and implementation.

PubMed

Li, Yongxiu; Gao, Ya; Zhang, Xuqiang; Wang, Xingyu; Mou, Lirong; Duan, Lili; He, Xiao; Mei, Ye; Zhang, John Z H

2013-09-01

Main chain torsions of alanine dipeptide are parameterized into coupled 2-dimensional Fourier expansions based on quantum mechanical (QM) calculations at M06 2X/aug-cc-pvtz//HF/6-31G** level. Solvation effect is considered by employing polarizable continuum model. Utilization of the M06 2X functional leads to precise potential energy surface that is comparable to or even better than MP2 level, but with much less computational demand. Parameterization of the 2D expansions is against the full main chain torsion space instead of just a few low energy conformations. This procedure is similar to that for the development of AMBER03 force field, except unique weighting factor was assigned to all the grid points. To avoid inconsistency between quantum mechanical calculations and molecular modeling, the model peptide is further optimized at molecular mechanics level with main chain dihedral angles fixed before the calculation of the conformational energy on molecular mechanical level at each grid point, during which generalized Born model is employed. Difference in solvation models at quantum mechanics and molecular mechanics levels makes this parameterization procedure less straightforward. All force field parameters other than main chain torsions are taken from existing AMBER force field. With this new main chain torsion terms, we have studied the main chain dihedral distributions of ALA dipeptide and pentapeptide in aqueous solution. The results demonstrate that 2D main chain torsion is effective in delineating the energy variation associated with rotations along main chain dihedrals. This work is an implication for the necessity of more accurate description of main chain torsions in the future development of ab initio force field and it also raises a challenge to the development of quantum mechanical methods, especially the quantum mechanical solvation models.
Phasic Triplet Markov Chains.

PubMed

El Yazid Boudaren, Mohamed; Monfrini, Emmanuel; Pieczynski, Wojciech; Aïssani, Amar

2014-11-01

Hidden Markov chains have been shown to be inadequate for data modeling under some complex conditions. In this work, we address the problem of statistical modeling of phenomena involving two heterogeneous system states. Such phenomena may arise in biology or communications, among other fields. Namely, we consider that a sequence of meaningful words is to be searched within a whole observation that also contains arbitrary one-by-one symbols. Moreover, a word may be interrupted at some site to be carried on later. Applying plain hidden Markov chains to such data, while ignoring their specificity, yields unsatisfactory results. The Phasic triplet Markov chain, proposed in this paper, overcomes this difficulty by means of an auxiliary underlying process in accordance with the triplet Markov chains theory. Related Bayesian restoration techniques and parameters estimation procedures according to the new model are then described. Finally, to assess the performance of the proposed model against the conventional hidden Markov chain model, experiments are conducted on synthetic and real data.
The development of a green supply chain dual-objective facility by considering different levels of uncertainty

NASA Astrophysics Data System (ADS)

Khorasani, Sasan Torabzadeh; Almasifard, Maryam

2017-11-01

This paper presents a dual-objective facility programming model for a green supply chain network. The main objectives of the presented model are minimizing overall expenditure and negative environmental impacts of the supply chain. This study contributes to the existing literature by incorporating uncertainty in customer demand, suppliers, production, and casting capacity. An industrial case study is also analyzed to reveal the feasibility of the proposed model and its application. A fuzzy approach which is known as TH is used to solve the suggested dual-objective model. TH approach is integration of a max-min method (LH) and modified version of Werners' approach (MW). The outcome of this study reveals that the presented model can support green supply chain network in different levels of uncertainty. In presented model, cost and negative environmental impacts derived from the supply chain network will increase of higher levels of uncertainty.
Simulating the dynamic behavior of chain drive systems by advanced CAE programs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ross, J.; Meyer, J.

1996-09-01

Due to the increased requirements for chain drive systems of 4-stroke internal combustion engines CAE-tools are necessary to design the optimum dynamic system. In comparison to models used din the past the advantage of the new model CDD (Chain Drive Dynamics) is the capability of simulating the trajectory of each chain link around the drive system. Each chain link is represented by a mass with two degrees of freedom and is coupled to the next by a spring-damper element. The drive sprocket can be moved with a constant or non-constant speed. As in reality the other sprockets are driven bymore » the running chain and can be excited by torques. Due to these unique model features it is possible to calculate all vibration types of the chain, polygon effects and radial or angular vibrations of the sprockets very accurately. The model includes the detailed simulation of a mechanical or a hydraulic tensioner as well. The method is ready to be coupled to other detailed calculation models (e.g. valve train systems, crankshaft, etc.). The high efficiency of the tool predicting the dynamic and acoustic behavior of a chain drive system will be demonstrated in comparison to measurements.« less
Stability of lamb loin stored under refrigeration and packed in different modified atmosphere packaging systems.

PubMed

Fernandes, Rafaella de Paula Paseto; Freire, Maria Teresa de Alvarenga; de Paula, Elisa Silva Maluf; Kanashiro, Ana Livea Sayuri; Catunda, Fernanda Antunes Pinto; Rosa, Alessandra Fernandes; Balieiro, Júlio Cesar de Carvalho; Trindade, Marco Antonio

2014-01-01

The aim of the present study was to evaluate the effect of different modified atmosphere packaging (MAP) systems (vacuum, 75% O2+25% CO2 and 100% CO2) on the stability of lamb loins stored at 1±1°C for 28 days. Microbiological (counts of aerobic and anaerobic psychrotrophic microorganisms, coliform at 45°C, coagulase-positive staphylococci and lactic acid bacteria and presence of Salmonella), physical and chemical (thiobarbituric acid reactive substances [TBARS], objective color, pH, water loss from cooking [WLC] and shear force), sensory (acceptance testing using a 9-point hedonic scale) and gas composition analyses were performed. Lamb meat remained stable with respect to the majority of the evaluated physical and chemical indexes and within the standards established by Brazilian legislation for pathogenic microorganisms throughout the storage period in all three packaging systems. However, with respect to psychrotrophic microorganisms, 100% CO2 packaging system provided increased stability despite presenting lower appearance preference. © 2013.
Ising Model on Tangled Chain, Some Thermodynamic Properties

NASA Astrophysics Data System (ADS)

Mejdani, R.

1996-09-01

In this paper we consider an Ising model on tangled chain, where some additional bonds compared to a pure Ising chain are presented. To understand the behavior of this system and the competition between ferromagnetic bonds J along the chain and antiferromagnetic bonds J' across the chain, we have studied in detail analytically and iteratively some of the thermodynamic quantities. Particularly interesting is, in the zero-field and zero-temperature limit, the behavior of the magnetization and the susceptibility closely related to the ground-state configurations and their degeneracies. This degeneracy, presented at the condition J' ≤ -J between J and J', explains, also, the existence of nonzero entropy at zero temperature. This model applied as a lattice gas model defined on a tangled chain could be also useful for the experimental investigations in studying the saturation curves for the enzyme kinetics or the melting curves for DNA-denaturation.
Learning In networks

NASA Technical Reports Server (NTRS)

Buntine, Wray L.

1995-01-01

Intelligent systems require software incorporating probabilistic reasoning, and often times learning. Networks provide a framework and methodology for creating this kind of software. This paper introduces network models based on chain graphs with deterministic nodes. Chain graphs are defined as a hierarchical combination of Bayesian and Markov networks. To model learning, plates on chain graphs are introduced to model independent samples. The paper concludes by discussing various operations that can be performed on chain graphs with plates as a simplification process or to generate learning algorithms.
Hybrid modeling and empirical analysis of automobile supply chain network

NASA Astrophysics Data System (ADS)

Sun, Jun-yan; Tang, Jian-ming; Fu, Wei-ping; Wu, Bing-ying

2017-05-01

Based on the connection mechanism of nodes which automatically select upstream and downstream agents, a simulation model for dynamic evolutionary process of consumer-driven automobile supply chain is established by integrating ABM and discrete modeling in the GIS-based map. Firstly, the rationality is proved by analyzing the consistency of sales and changes in various agent parameters between the simulation model and a real automobile supply chain. Second, through complex network theory, hierarchical structures of the model and relationships of networks at different levels are analyzed to calculate various characteristic parameters such as mean distance, mean clustering coefficients, and degree distributions. By doing so, it verifies that the model is a typical scale-free network and small-world network. Finally, the motion law of this model is analyzed from the perspective of complex self-adaptive systems. The chaotic state of the simulation system is verified, which suggests that this system has typical nonlinear characteristics. This model not only macroscopically illustrates the dynamic evolution of complex networks of automobile supply chain but also microcosmically reflects the business process of each agent. Moreover, the model construction and simulation of the system by means of combining CAS theory and complex networks supplies a novel method for supply chain analysis, as well as theory bases and experience for supply chain analysis of auto companies.
Equilibriumizing all food chain chaos through reproductive efficiency.

PubMed

Deng, Bo

2006-12-01

The intraspecific interference of a top-predator is incorporated into a classical mathematical model for three-trophic food chains. All chaos types known to the classical model are shown to exist for this comprehensive model. It is further demonstrated that if the top-predator reproduces at high efficiency, then all chaotic dynamics will change to a stable coexisting equilibrium, a novel property not found in the classical model. This finding gives a mechanistic explanation to the question of why food chain chaos is rare in the field. It also suggests that high reproductive efficiency of top-predators tends to stabilize food chains.
Model systems for single molecule polymer dynamics

PubMed Central

Latinwo, Folarin

2012-01-01

Double stranded DNA (dsDNA) has long served as a model system for single molecule polymer dynamics. However, dsDNA is a semiflexible polymer, and the structural rigidity of the DNA double helix gives rise to local molecular properties and chain dynamics that differ from flexible chains, including synthetic organic polymers. Recently, we developed single stranded DNA (ssDNA) as a new model system for single molecule studies of flexible polymer chains. In this work, we discuss model polymer systems in the context of “ideal” and “real” chain behavior considering thermal blobs, tension blobs, hydrodynamic drag and force–extension relations. In addition, we present monomer aspect ratio as a key parameter describing chain conformation and dynamics, and we derive dynamical scaling relations in terms of this molecular-level parameter. We show that asymmetric Kuhn segments can suppress monomer–monomer interactions, thereby altering global chain dynamics. Finally, we discuss ssDNA in the context of a new model system for single molecule polymer dynamics. Overall, we anticipate that future single polymer studies of flexible chains will reveal new insight into the dynamic behavior of “real” polymers, which will highlight the importance of molecular individualism and the prevalence of non-linear phenomena. PMID:22956980
Effect of chain stiffness on the competition between crystallization and glass-formation in model unentangled polymers

NASA Astrophysics Data System (ADS)

Nguyen, Hong T.; Smith, Tyler B.; Hoy, Robert S.; Karayiannis, Nikos Ch.

2015-10-01

We map out the solid-state morphologies formed by model soft-pearl-necklace polymers as a function of chain stiffness, spanning the range from fully flexible to rodlike chains. The ratio of Kuhn length to bead diameter (lK/r0) increases monotonically with increasing bending stiffness kb and yields a one-parameter model that relates chain shape to bulk morphology. In the flexible limit, monomers occupy the sites of close-packed crystallites while chains retain random-walk-like order. In the rodlike limit, nematic chain ordering typical of lamellar precursors coexists with close-packing. At intermediate values of bending stiffness, the competition between random-walk-like and nematic chain ordering produces glass-formation; the range of kb over which this occurs increases with the thermal cooling rate | T ˙ | implemented in our molecular dynamics simulations. Finally, values of kb between the glass-forming and rodlike ranges produce complex ordered phases such as close-packed spirals. Our results should provide a useful initial step in a coarse-grained modeling approach to systematically determining the effect of chain stiffness on the crystallization-vs-glass-formation competition in both synthetic and colloidal polymers.
Depression treatment for impoverished mothers by point-of-care providers: A randomized controlled trial.

PubMed

Segre, Lisa S; Brock, Rebecca L; O'Hara, Michael W

2015-04-01

Depression in low-income, ethnic-minority women of childbearing age is prevalent and compromises infant and child development. Yet numerous barriers prevent treatment delivery. Listening Visits (LV), an empirically supported intervention developed for delivery by British home-visiting nurses, could address this unmet mental health need. This randomized controlled trial (RCT) evaluated the effectiveness of LV delivered at a woman's usual point-of-care, including home visits or an ob-gyn office. Listening Visits were delivered to depressed pregnant women or mothers of young children by their point-of-care provider (e.g., home visitor or physician's assistant), all of whom had low levels of prior counseling experience. Three quarters of the study's participants were low-income. Of those who reported ethnicity, all identified themselves as minorities. Participants from 4 study sites (N = 66) were randomized in a 2:1 ratio, to LV or a wait-list control group (WLC). Assessments, conducted at baseline and 8 weeks, evaluated depression, quality of life, and treatment satisfaction. Depressive severity, depressive symptoms, and quality of life significantly improved among LV recipients as compared with women receiving standard social/health services. Women valued LV as evidenced by their high attendance rates and treatment satisfaction ratings. In a stepped model of depression care, LV can provide an accessible, acceptable, and effective first-line treatment option for at-risk women who otherwise are unlikely to receive treatment. (PsycINFO Database Record (c) 2015 APA, all rights reserved).
Fast-slow asymptotics for a Markov chain model of fast sodium current

NASA Astrophysics Data System (ADS)

Starý, Tomáš; Biktashev, Vadim N.

2017-09-01

We explore the feasibility of using fast-slow asymptotics to eliminate the computational stiffness of discrete-state, continuous-time deterministic Markov chain models of ionic channels underlying cardiac excitability. We focus on a Markov chain model of fast sodium current, and investigate its asymptotic behaviour with respect to small parameters identified in different ways.
Polymer models of interphase chromosomes

PubMed Central

Vasquez, Paula A; Bloom, Kerry

2014-01-01

Clear organizational patterns on the genome have emerged from the statistics of population studies of fixed cells. However, how these results translate into the dynamics of individual living cells remains unexplored. We use statistical mechanics models derived from polymer physics to inquire into the effects that chromosome properties and dynamics have in the temporal and spatial behavior of the genome. Overall, changes in the properties of individual chains affect the behavior of all other chains in the domain. We explore two modifications of chain behavior: single chain motion and chain-chain interactions. We show that there is not a direct relation between these effects, as increase in motion, doesn’t necessarily translate into an increase on chain interaction. PMID:25482191

A novel approach for inventory problem in the pharmaceutical supply chain.

PubMed

Candan, Gökçe; Yazgan, Harun Reşit

2016-02-24

In pharmaceutical enterprises, keeping up with global market conditions is possible with properly selected supply chain management policies. Generally; demand-driven classical supply chain model is used in the pharmaceutical industry. In this study, a new mathematical model is developed to solve an inventory problem in the pharmaceutical supply chain. Unlike the studies in literature, the "shelf life and product transition times" constraints are considered, simultaneously, first time in the pharmaceutical production inventory problem. The problem is formulated as a mixed-integer linear programming (MILP) model with a hybrid time representation. The objective is to maximize total net profit. Effectiveness of the proposed model is illustrated considering a classical and a vendor managed inventory (VMI) supply chain on an experimental study. To show the effectiveness of the model, an experimental study is performed; which contains 2 different supply chain policy (Classical and VMI), 24 and 30 months planning horizon, 10 and 15 different cephalosporin products. Finally the mathematical model is compared to another model in literature and the results show that proposed model is superior. This study suggest a novel approach for solving pharmaceutical inventory problem. The developed model is maximizing total net profit while determining optimal production plan under shelf life and product transition constraints in the pharmaceutical industry. And we believe that the proposed model is much more closed to real life unlike the other studies in literature.
A mixed integer linear programming model for operational planning of a biodiesel supply chain network from used cooking oil

NASA Astrophysics Data System (ADS)

Jonrinaldi, Hadiguna, Rika Ampuh; Salastino, Rades

2017-11-01

Environmental consciousness has paid many attention nowadays. It is not only about how to recycle, remanufacture or reuse used end products but it is also how to optimize the operations of the reverse system. A previous research has proposed a design of reverse supply chain of biodiesel network from used cooking oil. However, the research focused on the design of the supply chain strategy not the operations of the supply chain. It only decided how to design the structure of the supply chain in the next few years, and the process of each stage will be conducted in the supply chain system in general. The supply chain system has not considered operational policies to be conducted by the companies in the supply chain. Companies need a policy for each stage of the supply chain operations to be conducted so as to produce the optimal supply chain system, including how to use all the resources that have been designed in order to achieve the objectives of the supply chain system. Therefore, this paper proposes a model to optimize the operational planning of a biodiesel supply chain network from used cooking oil. A mixed integer linear programming is developed to model the operational planning of biodiesel supply chain in order to minimize the total operational cost of the supply chain. Based on the implementation of the model developed, the total operational cost of the biodiesel supply chain incurred by the system is less than the total operational cost of supply chain based on the previous research during seven days of operational planning about amount of 2,743,470.00 or 0.186%. Production costs contributed to 74.6 % of total operational cost and the cost of purchasing the used cooking oil contributed to 24.1 % of total operational cost. So, the system should pay more attention to these two aspects as changes in the value of these aspects will cause significant effects to the change in the total operational cost of the supply chain.
Semiflexible macromolecules in quasi-one-dimensional confinement: Discrete versus continuous bond angles.

PubMed

Huang, Aiqun; Hsu, Hsiao-Ping; Bhattacharya, Aniket; Binder, Kurt

2015-12-28

The conformations of semiflexible polymers in two dimensions confined in a strip of width D are studied by computer simulations, investigating two different models for the mechanism by which chain stiffness is realized. One model (studied by molecular dynamics) is a bead-spring model in the continuum, where stiffness is controlled by a bond angle potential allowing for arbitrary bond angles. The other model (studied by Monte Carlo) is a self-avoiding walk chain on the square lattice, where only discrete bond angles (0° and ±90°) are possible, and the bond angle potential then controls the density of kinks along the chain contour. The first model is a crude description of DNA-like biopolymers, while the second model (roughly) describes synthetic polymers like alkane chains. It is first demonstrated that in the bulk the crossover from rods to self-avoiding walks for both models is very similar, when one studies average chain linear dimensions, transverse fluctuations, etc., despite their differences in local conformations. However, in quasi-one-dimensional confinement two significant differences between both models occur: (i) The persistence length (extracted from the average cosine of the bond angle) gets renormalized for the lattice model when D gets less than the bulk persistence length, while in the continuum model it stays unchanged. (ii) The monomer density near the repulsive walls for semiflexible polymers is compatible with a power law predicted for the Kratky-Porod model in the case of the bead-spring model, while for the lattice case it tends to a nonzero constant across the strip. However, for the density of chain ends, such a constant behavior seems to occur for both models, unlike the power law observed for flexible polymers. In the regime where the bulk persistence length ℓp is comparable to D, hairpin conformations are detected, and the chain linear dimensions are discussed in terms of a crossover from the Daoud/De Gennes "string of blobs"-picture to the flexible rod picture when D decreases and/or the chain stiffness increases. Introducing a suitable further coarse-graining of the chain contours of the continuum model, direct estimates for the deflection length and its distribution could be obtained.
Dynamics of global supply chain and electric power networks: Models, pricing analysis, and computations

NASA Astrophysics Data System (ADS)

Matsypura, Dmytro

In this dissertation, I develop a new theoretical framework for the modeling, pricing analysis, and computation of solutions to electric power supply chains with power generators, suppliers, transmission service providers, and the inclusion of consumer demands. In particular, I advocate the application of finite-dimensional variational inequality theory, projected dynamical systems theory, game theory, network theory, and other tools that have been recently proposed for the modeling and analysis of supply chain networks (cf. Nagurney (2006)) to electric power markets. This dissertation contributes to the extant literature on the modeling, analysis, and solution of supply chain networks, including global supply chains, in general, and electric power supply chains, in particular, in the following ways. It develops a theoretical framework for modeling, pricing analysis, and computation of electric power flows/transactions in electric power systems using the rationale for supply chain analysis. The models developed include both static and dynamic ones. The dissertation also adds a new dimension to the methodology of the theory of projected dynamical systems by proving that, irrespective of the speeds of adjustment, the equilibrium of the system remains the same. Finally, I include alternative fuel suppliers, along with their behavior into the supply chain modeling and analysis framework. This dissertation has strong practical implications. In an era in which technology and globalization, coupled with increasing risk and uncertainty, complicate electricity demand and supply within and between nations, the successful management of electric power systems and pricing become increasingly pressing topics with relevance not only for economic prosperity but also national security. This dissertation addresses such related topics by providing models, pricing tools, and algorithms for decentralized electric power supply chains. This dissertation is based heavily on the following coauthored papers: Nagurney, Cruz, and Matsypura (2003), Nagurney and Matsypura (2004, 2005, 2006), Matsypura and Nagurney (2005), Matsypura, Nagurney, and Liu (2006).
Modeling competitive substitution in a polyelectrolyte complex

DOE Office of Scientific and Technical Information (OSTI.GOV)

Peng, B.; Muthukumar, M., E-mail: muthu@polysci.umass.edu

2015-12-28

We have simulated the invasion of a polyelectrolyte complex made of a polycation chain and a polyanion chain, by another longer polyanion chain, using the coarse-grained united atom model for the chains and the Langevin dynamics methodology. Our simulations reveal many intricate details of the substitution reaction in terms of conformational changes of the chains and competition between the invading chain and the chain being displaced for the common complementary chain. We show that the invading chain is required to be sufficiently longer than the chain being displaced for effecting the substitution. Yet, having the invading chain to be longermore » than a certain threshold value does not reduce the substitution time much further. While most of the simulations were carried out in salt-free conditions, we show that presence of salt facilitates the substitution reaction and reduces the substitution time. Analysis of our data shows that the dominant driving force for the substitution process involving polyelectrolytes lies in the release of counterions during the substitution.« less
A Case Study Using Modeling and Simulation to Predict Logistics Supply Chain Issues

NASA Technical Reports Server (NTRS)

Tucker, David A.

2007-01-01

Optimization of critical supply chains to deliver thousands of parts, materials, sub-assemblies, and vehicle structures as needed is vital to the success of the Constellation Program. Thorough analysis needs to be performed on the integrated supply chain processes to plan, source, make, deliver, and return critical items efficiently. Process modeling provides simulation technology-based, predictive solutions for supply chain problems which enable decision makers to reduce costs, accelerate cycle time and improve business performance. For example, United Space Alliance, LLC utilized this approach in late 2006 to build simulation models that recreated shuttle orbiter thruster failures and predicted the potential impact of thruster removals on logistics spare assets. The main objective was the early identification of possible problems in providing thruster spares for the remainder of the Shuttle Flight Manifest. After extensive analysis the model results were used to quantify potential problems and led to improvement actions in the supply chain. Similarly the proper modeling and analysis of Constellation parts, materials, operations, and information flows will help ensure the efficiency of the critical logistics supply chains and the overall success of the program.
Future supply chains enabled by continuous processing--opportunities and challenges. May 20-21, 2014 Continuous Manufacturing Symposium.

PubMed

Srai, Jagjit Singh; Badman, Clive; Krumme, Markus; Futran, Mauricio; Johnston, Craig

2015-03-01

This paper examines the opportunities and challenges facing the pharmaceutical industry in moving to a primarily "continuous processing"-based supply chain. The current predominantly "large batch" and centralized manufacturing system designed for the "blockbuster" drug has driven a slow-paced, inventory heavy operating model that is increasingly regarded as inflexible and unsustainable. Indeed, new markets and the rapidly evolving technology landscape will drive more product variety, shorter product life-cycles, and smaller drug volumes, which will exacerbate an already unsustainable economic model. Future supply chains will be required to enhance affordability and availability for patients and healthcare providers alike despite the increased product complexity. In this more challenging supply scenario, we examine the potential for a more pull driven, near real-time demand-based supply chain, utilizing continuous processing where appropriate as a key element of a more "flow-through" operating model. In this discussion paper on future supply chain models underpinned by developments in the continuous manufacture of pharmaceuticals, we have set out; The significant opportunities to moving to a supply chain flow-through operating model, with substantial opportunities in inventory reduction, lead-time to patient, and radically different product assurance/stability regimes. Scenarios for decentralized production models producing a greater variety of products with enhanced volume flexibility. Production, supply, and value chain footprints that are radically different from today's monolithic and centralized batch manufacturing operations. Clinical trial and drug product development cost savings that support more rapid scale-up and market entry models with early involvement of SC designers within New Product Development. The major supply chain and industrial transformational challenges that need to be addressed. The paper recognizes that although current batch operational performance in pharma is far from optimal and not necessarily an appropriate end-state benchmark for batch technology, the adoption of continuous supply chain operating models underpinned by continuous production processing, as full or hybrid solutions in selected product supply chains, can support industry transformations to deliver right-first-time quality at substantially lower inventory profiles. © 2015 Wiley Periodicals, Inc. and the American Pharmacists Association.
Comparison of Video and Live Modeling in Teaching Response Chains to Children with Autism

ERIC Educational Resources Information Center

Ergenekon, Yasemin; Tekin-Iftar, Elif; Kapan, Alper; Akmanoglu, Nurgul

2014-01-01

Research has shown that video and live modeling are both effective in teaching new skills to children with autism. An adapted alternating treatments design was used to compare the effectiveness and efficiency of video and live modeling in teaching response chains to three children with autism. Each child was taught two chained skills; one skill…
Wide-angle x-ray scattering and solid-state nuclear magnetic resonance data combined to test models for cellulose microfibrils in mung bean cell walls.

PubMed

Newman, Roger H; Hill, Stefan J; Harris, Philip J

2013-12-01

A synchrotron wide-angle x-ray scattering study of mung bean (Vigna radiata) primary cell walls was combined with published solid-state nuclear magnetic resonance data to test models for packing of (1→4)-β-glucan chains in cellulose microfibrils. Computer-simulated peak shapes, calculated for 36-chain microfibrils with perfect order or uncorrelated disorder, were sharper than those in the experimental diffractogram. Introducing correlated disorder into the models broaden the simulated peaks but only when the disorder was increased to unrealistic magnitudes. Computer-simulated diffractograms, calculated for 24- and 18-chain models, showed good fits to experimental data. Particularly good fits to both x-ray and nuclear magnetic resonance data were obtained for collections of 18-chain models with mixed cross-sectional shapes and occasional twinning. Synthesis of 18-chain microfibrils is consistent with a model for cellulose-synthesizing complexes in which three cellulose synthase polypeptides form a particle and six particles form a rosette.
Managing risks in the fisheries supply chain using House of Risk Framework (HOR) and Interpretive Structural Modeling (ISM)

NASA Astrophysics Data System (ADS)

Nguyen, T. L. T.; Tran, T. T.; Huynh, T. P.; Ho, T. K. D.; Le, A. T.; Do, T. K. H.

2018-04-01

One of the sectors which contributes importantly to the development of Vietnam economy is fishery industry. However, during recent year, it has been witnessed many difficulties on managing the performance of the fishery supply chain operations as a whole. In this paper, a framework for supply chain risk management (SCRM) is proposed. Initially, all the activities are mapped by using Supply Chain Operations Reference (SCOR) model. Next, the risk ranking is analyzed in House of Risk. Furthermore, interpretive structural modeling (ISM) is used to identify inter-relationships among supply chain risks and to visualize the risks according to their levels. For illustration, the model has been tested in several case studies with fishery companies in Can Tho, Mekong Delta. This study identifies 22 risk events and 20 risk agents through the supply chain. Also, the risk priority could be used for further House of Risk with proactive actions in future studies.
A review of agent-based modeling approach in the supply chain collaboration context

NASA Astrophysics Data System (ADS)

Arvitrida, N. I.

2018-04-01

Collaboration is considered as the key aspect of supply chain management (SCM) success. This issue has been addressed by many studies in recent years, but there are still few research employs agent-based modeling (ABM) approach to study business partnerships in SCM. This paper reviews the use of ABM in modeling collaboration in supply chains and inform the scope of ABM application in the existing literature. The review reveals that ABM can be an effective tool to address various aspects in supply chain relationships, but its applications in SCM studies are still limited. Moreover, where ABM is applied in the SCM context, most of the studies focus on software architecture rather than analyzing the supply chain issues. This paper also provides insights to SCM researchers about the opportunity uses of ABM in studying complexity in supply chain collaboration.
Stability of ecological industry chain: an entropy model approach.

PubMed

Wang, Qingsong; Qiu, Shishou; Yuan, Xueliang; Zuo, Jian; Cao, Dayong; Hong, Jinglan; Zhang, Jian; Dong, Yong; Zheng, Ying

2016-07-01

A novel methodology is proposed in this study to examine the stability of ecological industry chain network based on entropy theory. This methodology is developed according to the associated dissipative structure characteristics, i.e., complexity, openness, and nonlinear. As defined in the methodology, network organization is the object while the main focus is the identification of core enterprises and core industry chains. It is proposed that the chain network should be established around the core enterprise while supplementation to the core industry chain helps to improve system stability, which is verified quantitatively. Relational entropy model can be used to identify core enterprise and core eco-industry chain. It could determine the core of the network organization and core eco-industry chain through the link form and direction of node enterprises. Similarly, the conductive mechanism of different node enterprises can be examined quantitatively despite the absence of key data. Structural entropy model can be employed to solve the problem of order degree for network organization. Results showed that the stability of the entire system could be enhanced by the supplemented chain around the core enterprise in eco-industry chain network organization. As a result, the sustainability of the entire system could be further improved.
An integrated supply chain model for new products with imprecise production and supply under scenario dependent fuzzy random demand

NASA Astrophysics Data System (ADS)

Nagar, Lokesh; Dutta, Pankaj; Jain, Karuna

2014-05-01

In the present day business scenario, instant changes in market demand, different source of materials and manufacturing technologies force many companies to change their supply chain planning in order to tackle the real-world uncertainty. The purpose of this paper is to develop a multi-objective two-stage stochastic programming supply chain model that incorporates imprecise production rate and supplier capacity under scenario dependent fuzzy random demand associated with new product supply chains. The objectives are to maximise the supply chain profit, achieve desired service level and minimise financial risk. The proposed model allows simultaneous determination of optimum supply chain design, procurement and production quantities across the different plants, and trade-offs between inventory and transportation modes for both inbound and outbound logistics. Analogous to chance constraints, we have used the possibility measure to quantify the demand uncertainties and the model is solved using fuzzy linear programming approach. An illustration is presented to demonstrate the effectiveness of the proposed model. Sensitivity analysis is performed for maximisation of the supply chain profit with respect to different confidence level of service, risk and possibility measure. It is found that when one considers the service level and risk as robustness measure the variability in profit reduces.
Monte Carlo simulations of lattice models for single polymer systems

NASA Astrophysics Data System (ADS)

Hsu, Hsiao-Ping

2014-10-01

Single linear polymer chains in dilute solutions under good solvent conditions are studied by Monte Carlo simulations with the pruned-enriched Rosenbluth method up to the chain length N ˜ O(10^4). Based on the standard simple cubic lattice model (SCLM) with fixed bond length and the bond fluctuation model (BFM) with bond lengths in a range between 2 and sqrt{10}, we investigate the conformations of polymer chains described by self-avoiding walks on the simple cubic lattice, and by random walks and non-reversible random walks in the absence of excluded volume interactions. In addition to flexible chains, we also extend our study to semiflexible chains for different stiffness controlled by a bending potential. The persistence lengths of chains extracted from the orientational correlations are estimated for all cases. We show that chains based on the BFM are more flexible than those based on the SCLM for a fixed bending energy. The microscopic differences between these two lattice models are discussed and the theoretical predictions of scaling laws given in the literature are checked and verified. Our simulations clarify that a different mapping ratio between the coarse-grained models and the atomistically realistic description of polymers is required in a coarse-graining approach due to the different crossovers to the asymptotic behavior.
[Healthcare value chain: a model for the Brazilian healthcare system].

PubMed

Pedroso, Marcelo Caldeira; Malik, Ana Maria

2012-10-01

This article presents a model of the healthcare value chain which consists of a schematic representation of the Brazilian healthcare system. The proposed model is adapted for the Brazilian reality and has the scope and flexibility for use in academic activities and analysis of the healthcare sector in Brazil. It places emphasis on three components: the main activities of the value chain, grouped in vertical and horizontal links; the mission of each link and the main value chain flows. The proposed model consists of six vertical and three horizontal links, amounting to nine. These are: knowledge development; supply of products and technologies; healthcare services; financial intermediation; healthcare financing; healthcare consumption; regulation; distribution of healthcare products; and complementary and support services. Four flows can be used to analyze the value chain: knowledge and innovation; products and services; financial; and information.
Thermal conductivity of the Lennard-Jones chain fluid model.

PubMed

Galliero, Guillaume; Boned, Christian

2009-12-01

Nonequilibrium molecular dynamics simulations have been performed to estimate, analyze, and correlate the thermal conductivity of a fluid composed of short Lennard-Jones chains (up to 16 segments) over a large range of thermodynamic conditions. It is shown that the dilute gas contribution to the thermal conductivity decreases when the chain length increases for a given temperature. In dense states, simulation results indicate that the residual thermal conductivity of the monomer increases strongly with density, but is weakly dependent on the temperature. Compared to the monomer value, it has been noted that the residual thermal conductivity of the chain was slightly decreasing with its length. Using these results, an empirical relation, including a contribution due to the critical enhancement, is proposed to provide an accurate estimation of the thermal conductivity of the Lennard-Jones chain fluid model (up to 16 segments) over the domain 0.8
Optimizing bi-objective, multi-echelon supply chain model using particle swarm intelligence algorithm

NASA Astrophysics Data System (ADS)

Sathish Kumar, V. R.; Anbuudayasankar, S. P.; Rameshkumar, K.

2018-02-01

In the current globalized scenario, business organizations are more dependent on cost effective supply chain to enhance profitability and better handle competition. Demand uncertainty is an important factor in success or failure of a supply chain. An efficient supply chain limits the stock held at all echelons to the extent of avoiding a stock-out situation. In this paper, a three echelon supply chain model consisting of supplier, manufacturing plant and market is developed and the same is optimized using particle swarm intelligence algorithm.
Parallel Markov chain Monte Carlo - bridging the gap to high-performance Bayesian computation in animal breeding and genetics.

PubMed

Wu, Xiao-Lin; Sun, Chuanyu; Beissinger, Timothy M; Rosa, Guilherme Jm; Weigel, Kent A; Gatti, Natalia de Leon; Gianola, Daniel

2012-09-25

Most Bayesian models for the analysis of complex traits are not analytically tractable and inferences are based on computationally intensive techniques. This is true of Bayesian models for genome-enabled selection, which uses whole-genome molecular data to predict the genetic merit of candidate animals for breeding purposes. In this regard, parallel computing can overcome the bottlenecks that can arise from series computing. Hence, a major goal of the present study is to bridge the gap to high-performance Bayesian computation in the context of animal breeding and genetics. Parallel Monte Carlo Markov chain algorithms and strategies are described in the context of animal breeding and genetics. Parallel Monte Carlo algorithms are introduced as a starting point including their applications to computing single-parameter and certain multiple-parameter models. Then, two basic approaches for parallel Markov chain Monte Carlo are described: one aims at parallelization within a single chain; the other is based on running multiple chains, yet some variants are discussed as well. Features and strategies of the parallel Markov chain Monte Carlo are illustrated using real data, including a large beef cattle dataset with 50K SNP genotypes. Parallel Markov chain Monte Carlo algorithms are useful for computing complex Bayesian models, which does not only lead to a dramatic speedup in computing but can also be used to optimize model parameters in complex Bayesian models. Hence, we anticipate that use of parallel Markov chain Monte Carlo will have a profound impact on revolutionizing the computational tools for genomic selection programs.
Parallel Markov chain Monte Carlo - bridging the gap to high-performance Bayesian computation in animal breeding and genetics

PubMed Central

2012-01-01

Background Most Bayesian models for the analysis of complex traits are not analytically tractable and inferences are based on computationally intensive techniques. This is true of Bayesian models for genome-enabled selection, which uses whole-genome molecular data to predict the genetic merit of candidate animals for breeding purposes. In this regard, parallel computing can overcome the bottlenecks that can arise from series computing. Hence, a major goal of the present study is to bridge the gap to high-performance Bayesian computation in the context of animal breeding and genetics. Results Parallel Monte Carlo Markov chain algorithms and strategies are described in the context of animal breeding and genetics. Parallel Monte Carlo algorithms are introduced as a starting point including their applications to computing single-parameter and certain multiple-parameter models. Then, two basic approaches for parallel Markov chain Monte Carlo are described: one aims at parallelization within a single chain; the other is based on running multiple chains, yet some variants are discussed as well. Features and strategies of the parallel Markov chain Monte Carlo are illustrated using real data, including a large beef cattle dataset with 50K SNP genotypes. Conclusions Parallel Markov chain Monte Carlo algorithms are useful for computing complex Bayesian models, which does not only lead to a dramatic speedup in computing but can also be used to optimize model parameters in complex Bayesian models. Hence, we anticipate that use of parallel Markov chain Monte Carlo will have a profound impact on revolutionizing the computational tools for genomic selection programs. PMID:23009363
Statistical Analysis of Notational AFL Data Using Continuous Time Markov Chains

PubMed Central

Meyer, Denny; Forbes, Don; Clarke, Stephen R.

2006-01-01

Animal biologists commonly use continuous time Markov chain models to describe patterns of animal behaviour. In this paper we consider the use of these models for describing AFL football. In particular we test the assumptions for continuous time Markov chain models (CTMCs), with time, distance and speed values associated with each transition. Using a simple event categorisation it is found that a semi-Markov chain model is appropriate for this data. This validates the use of Markov Chains for future studies in which the outcomes of AFL matches are simulated. Key Points A comparison of four AFL matches suggests similarity in terms of transition probabilities for events and the mean times, distances and speeds associated with each transition. The Markov assumption appears to be valid. However, the speed, time and distance distributions associated with each transition are not exponential suggesting that semi-Markov model can be used to model and simulate play. Team identified events and directions associated with transitions are required to develop the model into a tool for the prediction of match outcomes. PMID:24357946

Statistical Analysis of Notational AFL Data Using Continuous Time Markov Chains.

PubMed

Meyer, Denny; Forbes, Don; Clarke, Stephen R

2006-01-01

Animal biologists commonly use continuous time Markov chain models to describe patterns of animal behaviour. In this paper we consider the use of these models for describing AFL football. In particular we test the assumptions for continuous time Markov chain models (CTMCs), with time, distance and speed values associated with each transition. Using a simple event categorisation it is found that a semi-Markov chain model is appropriate for this data. This validates the use of Markov Chains for future studies in which the outcomes of AFL matches are simulated. Key PointsA comparison of four AFL matches suggests similarity in terms of transition probabilities for events and the mean times, distances and speeds associated with each transition.The Markov assumption appears to be valid.However, the speed, time and distance distributions associated with each transition are not exponential suggesting that semi-Markov model can be used to model and simulate play.Team identified events and directions associated with transitions are required to develop the model into a tool for the prediction of match outcomes.
Ground-state energies of the nonlinear sigma model and the Heisenberg spin chains

NASA Technical Reports Server (NTRS)

Zhang, Shoucheng; Schulz, H. J.; Ziman, Timothy

1989-01-01

A theorem on the O(3) nonlinear sigma model with the topological theta term is proved, which states that the ground-state energy at theta = pi is always higher than the ground-state energy at theta = 0, for the same value of the coupling constant g. Provided that the nonlinear sigma model gives the correct description for the Heisenberg spin chains in the large-s limit, this theorem makes a definite prediction relating the ground-state energies of the half-integer and the integer spin chains. The ground-state energies obtained from the exact Bethe ansatz solution for the spin-1/2 chain and the numerical diagonalization on the spin-1, spin-3/2, and spin-2 chains support this prediction.
Profit Analysis Model of Smart Item Implementation in Integrated Supply Chain Process

NASA Astrophysics Data System (ADS)

Tritularsih, Yustina; Rinanto, Andhy; Prasetyo, Hoedi; Nur Rosyidi, Cucuk

2018-03-01

Nowadays all links of the entire supply chain need to integrate their different infrastructures and they have better control of them to drive better profits. This integration should offer the ability for companies in order to have an overall and transparent insight to its supply chain activities. An intelligent supply chain which is mainly supported by Smart Items technology can satisfy the need of those integration. By means of Smart Items, a company can benefit some advantages. Those are cost reduction and value creation. However, currently there is no comprehensive Smart Item infrastructure exists yet so it is difficult to calculate the true benefit information. This paper attempts to recommend a model for estimating the benefits of implementing Smart Items in a company which has an integrated supply chain process. The integrated supply chain means that three echelons (supplier, shipper and retailer) of supply chain are belonged to a company. The proposed model was used to determine the shrinkage value and RFID tag price which can give the maximum benefit of Smart Items implementation. A numerical example is also provided to give a better comprehension on model calculation.
Flory-type theories of polymer chains under different external stimuli

NASA Astrophysics Data System (ADS)

Budkov, Yu A.; Kiselev, M. G.

2018-01-01

In this Review, we present a critical analysis of various applications of the Flory-type theories to a theoretical description of the conformational behavior of single polymer chains in dilute polymer solutions under a few external stimuli. Different theoretical models of flexible polymer chains in the supercritical fluid are discussed and analysed. Different points of view on the conformational behavior of the polymer chain near the liquid-gas transition critical point of the solvent are presented. A theoretical description of the co-solvent-induced coil-globule transitions within the implicit-solvent-explicit-co-solvent models is discussed. Several explicit-solvent-explicit-co-solvent theoretical models of the coil-to-globule-to-coil transition of the polymer chain in a mixture of good solvents (co-nonsolvency) are analysed and compared with each other. Finally, a new theoretical model of the conformational behavior of the dielectric polymer chain under the external constant electric field in the dilute polymer solution with an explicit account for the many-body dipole correlations is discussed. The polymer chain collapse induced by many-body dipole correlations of monomers in the context of statistical thermodynamics of dielectric polymers is analysed.
Integrating biomass quality variability in stochastic supply chain modeling and optimization for large-scale biofuel production

DOE Office of Scientific and Technical Information (OSTI.GOV)

Castillo-Villar, Krystel K.; Eksioglu, Sandra; Taherkhorsandi, Milad

The production of biofuels using second-generation feedstocks has been recognized as an important alternative source of sustainable energy and its demand is expected to increase due to regulations such as the Renewable Fuel Standard. However, the pathway to biofuel industry maturity faces unique, unaddressed challenges. Here, to address this challenges, this article presents an optimization model which quantifies and controls the impact of biomass quality variability on supply chain related decisions and technology selection. We propose a two-stage stochastic programming model and associated efficient solution procedures for solving large-scale problems to (1) better represent the random nature of the biomassmore » quality (defined by moisture and ash contents) in supply chain modeling, and (2) assess the impact of these uncertainties on the supply chain design and planning. The proposed model is then applied to a case study in the state of Tennessee. Results show that high moisture and ash contents negatively impact the unit delivery cost since poor biomass quality requires the addition of quality control activities. Experimental results indicate that supply chain cost could increase as much as 27%–31% when biomass quality is poor. We assess the impact of the biomass quality on the topological supply chain. Our case study indicates that biomass quality impacts supply chain costs; thus, it is important to consider the impact of biomass quality in supply chain design and management decisions.« less
Integrating biomass quality variability in stochastic supply chain modeling and optimization for large-scale biofuel production

DOE PAGES

Castillo-Villar, Krystel K.; Eksioglu, Sandra; Taherkhorsandi, Milad

2017-02-20

The production of biofuels using second-generation feedstocks has been recognized as an important alternative source of sustainable energy and its demand is expected to increase due to regulations such as the Renewable Fuel Standard. However, the pathway to biofuel industry maturity faces unique, unaddressed challenges. Here, to address this challenges, this article presents an optimization model which quantifies and controls the impact of biomass quality variability on supply chain related decisions and technology selection. We propose a two-stage stochastic programming model and associated efficient solution procedures for solving large-scale problems to (1) better represent the random nature of the biomassmore » quality (defined by moisture and ash contents) in supply chain modeling, and (2) assess the impact of these uncertainties on the supply chain design and planning. The proposed model is then applied to a case study in the state of Tennessee. Results show that high moisture and ash contents negatively impact the unit delivery cost since poor biomass quality requires the addition of quality control activities. Experimental results indicate that supply chain cost could increase as much as 27%–31% when biomass quality is poor. We assess the impact of the biomass quality on the topological supply chain. Our case study indicates that biomass quality impacts supply chain costs; thus, it is important to consider the impact of biomass quality in supply chain design and management decisions.« less
Respiratory chain inhibition: one more feature to propose MPTP intoxication as a Leigh syndrome model.

PubMed

Da Costa, Barbara; Dumon, Elodie; Le Moigno, Laurence; Bodard, Sylvie; Castelnau, Pierre; Letellier, Thierry; Rocher, Christophe

2016-10-01

1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) intoxicated mice have been widely used to model the loss of dopaminergic neurons. As this treatment leads to basal ganglia degeneration, it was proposed that MPTP mice could be used as a model of Leigh syndrome. However, this mitochondrial pathology is biochemically characterized by a respiratory chain dysfunction. To determine if MPTP can affect in vivo mitochondria function, we measured the activities of mitochondrial respiratory chain complexes in several tissues. Our results show that MPTP affects mainly mitochondrial respiratory chain complex IV, as found in Leigh Syndrome, confirming that acute MPTP intoxicated mice are a good model of Leigh Syndrome.
On the dynamics of chain systems. [applications in manipulator and human body models

NASA Technical Reports Server (NTRS)

Huston, R. L.; Passerello, C. E.

1974-01-01

A computer-oriented method for obtaining dynamical equations of motion for chain systems is presented. A chain system is defined as an arbitrarily assembled set of rigid bodies such that adjoining bodies have at least one common point and such that closed loops are not formed. The equations of motion are developed through the use of Lagrange's form of d'Alembert's principle. The method and procedure is illustrated with an elementary study of a tripod space manipulator. The method is designed for application with systems such as human body models, chains and cables, and dynamic finite-segment models.
Development of S-ARIMA Model for Forecasting Demand in a Beverage Supply Chain

NASA Astrophysics Data System (ADS)

Mircetic, Dejan; Nikolicic, Svetlana; Maslaric, Marinko; Ralevic, Nebojsa; Debelic, Borna

2016-11-01

Demand forecasting is one of the key activities in planning the freight flows in supply chains, and accordingly it is essential for planning and scheduling of logistic activities within observed supply chain. Accurate demand forecasting models directly influence the decrease of logistics costs, since they provide an assessment of customer demand. Customer demand is a key component for planning all logistic processes in supply chain, and therefore determining levels of customer demand is of great interest for supply chain managers. In this paper we deal with exactly this kind of problem, and we develop the seasonal Autoregressive IntegratedMoving Average (SARIMA) model for forecasting demand patterns of a major product of an observed beverage company. The model is easy to understand, flexible to use and appropriate for assisting the expert in decision making process about consumer demand in particular periods.
A Looping-Based Model for Quenching Repression

PubMed Central

Pollak, Yaroslav; Goldberg, Sarah; Amit, Roee

2017-01-01

We model the regulatory role of proteins bound to looped DNA using a simulation in which dsDNA is represented as a self-avoiding chain, and proteins as spherical protrusions. We simulate long self-avoiding chains using a sequential importance sampling Monte-Carlo algorithm, and compute the probabilities for chain looping with and without a protrusion. We find that a protrusion near one of the chain’s termini reduces the probability of looping, even for chains much longer than the protrusion–chain-terminus distance. This effect increases with protrusion size, and decreases with protrusion-terminus distance. The reduced probability of looping can be explained via an eclipse-like model, which provides a novel inhibitory mechanism. We test the eclipse model on two possible transcription-factor occupancy states of the D. melanogaster eve 3/7 enhancer, and show that it provides a possible explanation for the experimentally-observed eve stripe 3 and 7 expression patterns. PMID:28085884
Internal friction and mode relaxation in a simple chain model.

PubMed

Fugmann, S; Sokolov, I M

2009-12-21

We consider the equilibrium relaxation properties of the end-to-end distance and of the principal components in a one-dimensional polymer chain model with nonlinear interaction between the beads. While for the single-well potentials these properties are similar to the ones of a Rouse chain, for the double-well interaction potentials, modeling internal friction, they differ vastly from the ones of the harmonic chain at intermediate times and intermediate temperatures. This minimal description within a one-dimensional model mimics the relaxation properties found in much more complex polymer systems. Thus, the relaxation time of the end-to-end distance may grow by orders of magnitude at intermediate temperatures. The principal components (whose directions are shown to coincide with the normal modes of the harmonic chain, whatever interaction potential is assumed) not only display larger relaxation times but also subdiffusive scaling.
An equal force theory for network models of soft materials with arbitrary molecular weight distribution

NASA Astrophysics Data System (ADS)

Verron, E.; Gros, A.

2017-09-01

Most network models for soft materials, e.g. elastomers and gels, are dedicated to idealized materials: all chains admit the same number of Kuhn segments. Nevertheless, such standard models are not appropriate for materials involving multiple networks, and some specific constitutive equations devoted to these materials have been derived in the last few years. In nearly all cases, idealized networks of different chain lengths are assembled following an equal strain assumption; only few papers adopt an equal stress assumption, although some authors argue that such hypothesis would reflect the equilibrium of the different networks in contact. In this work, a full-network model with an arbitrary chain length distribution is derived by considering that chains of different lengths satisfy the equal force assumption in each direction of the unit sphere. The derivation is restricted to non-Gaussian freely jointed chains and to affine deformation of the sphere. Firstly, after a proper definition of the undeformed configuration of the network, we demonstrate that the equal force assumption leads to the equality of a normalized stretch in chains of different lengths. Secondly, we establish that the network with chain length distribution behaves as an idealized full-network of which both chain length and density of are provided by the chain length distribution. This approach is finally illustrated with two examples: the derivation of a new expression for the Young modulus of bimodal interpenetrated polymer networks, and the prediction of the change in fluorescence during deformation of mechanochemically responsive elastomers.
Optimal design of supply chain network under uncertainty environment using hybrid analytical and simulation modeling approach

NASA Astrophysics Data System (ADS)

Chiadamrong, N.; Piyathanavong, V.

2017-12-01

Models that aim to optimize the design of supply chain networks have gained more interest in the supply chain literature. Mixed-integer linear programming and discrete-event simulation are widely used for such an optimization problem. We present a hybrid approach to support decisions for supply chain network design using a combination of analytical and discrete-event simulation models. The proposed approach is based on iterative procedures until the difference between subsequent solutions satisfies the pre-determined termination criteria. The effectiveness of proposed approach is illustrated by an example, which shows closer to optimal results with much faster solving time than the results obtained from the conventional simulation-based optimization model. The efficacy of this proposed hybrid approach is promising and can be applied as a powerful tool in designing a real supply chain network. It also provides the possibility to model and solve more realistic problems, which incorporate dynamism and uncertainty.
The Analysis of Rush Orders Risk in Supply Chain: A Simulation Approach

NASA Technical Reports Server (NTRS)

Mahfouz, Amr; Arisha, Amr

2011-01-01

Satisfying customers by delivering demands at agreed time, with competitive prices, and in satisfactory quality level are crucial requirements for supply chain survival. Incidence of risks in supply chain often causes sudden disruptions in the processes and consequently leads to customers losing their trust in a company's competence. Rush orders are considered to be one of the main types of supply chain risks due to their negative impact on the overall performance, Using integrated definition modeling approaches (i.e. IDEF0 & IDEF3) and simulation modeling technique, a comprehensive integrated model has been developed to assess rush order risks and examine two risk mitigation strategies. Detailed functions sequence and objects flow were conceptually modeled to reflect on macro and micro levels of the studied supply chain. Discrete event simulation models were then developed to assess and investigate the mitigation strategies of rush order risks, the objective of this is to minimize order cycle time and cost.
Irreversible Markov chains in spin models: Topological excitations

NASA Astrophysics Data System (ADS)

Lei, Ze; Krauth, Werner

2018-01-01

We analyze the convergence of the irreversible event-chain Monte Carlo algorithm for continuous spin models in the presence of topological excitations. In the two-dimensional XY model, we show that the local nature of the Markov-chain dynamics leads to slow decay of vortex-antivortex correlations while spin waves decorrelate very quickly. Using a Fréchet description of the maximum vortex-antivortex distance, we quantify the contributions of topological excitations to the equilibrium correlations, and show that they vary from a dynamical critical exponent z∼ 2 at the critical temperature to z∼ 0 in the limit of zero temperature. We confirm the event-chain algorithm's fast relaxation (corresponding to z = 0) of spin waves in the harmonic approximation to the XY model. Mixing times (describing the approach towards equilibrium from the least favorable initial state) however remain much larger than equilibrium correlation times at low temperatures. We also describe the respective influence of topological monopole-antimonopole excitations and of spin waves on the event-chain dynamics in the three-dimensional Heisenberg model.
Developing a model for agile supply: an empirical study from Iranian pharmaceutical supply chain.

PubMed

Rajabzadeh Ghatari, Ali; Mehralian, Gholamhossein; Zarenezhad, Forouzandeh; Rasekh, Hamid Reza

2013-01-01

Agility is the fundamental characteristic of a supply chain needed for survival in turbulent markets, where environmental forces create additional uncertainty resulting in higher risk in the supply chain management. In addition, agility helps providing the right product, at the right time to the consumer. The main goal of this research is therefore to promote supplier selection in pharmaceutical industry according to the formative basic factors. Moreover, this paper can configure its supply network to achieve the agile supply chain. The present article analyzes the supply part of supply chain based on SCOR model, used to assess agile supply chains by highlighting their specific characteristics and applicability in providing the active pharmaceutical ingredient (API). This methodology provides an analytical modeling; the model enables potential suppliers to be assessed against the multiple criteria using both quantitative and qualitative measures. In addition, for making priority of critical factors, TOPSIS algorithm has been used as a common technique of MADM model. Finally, several factors such as delivery speed, planning and reorder segmentation, trust development and material quantity adjustment are identified and prioritized as critical factors for being agile in supply of API.
Developing a Model for Agile Supply: an Empirical Study from Iranian Pharmaceutical Supply Chain

PubMed Central

Rajabzadeh Ghatari, Ali; Mehralian, Gholamhossein; Zarenezhad, Forouzandeh; Rasekh, Hamid Reza

2013-01-01

Agility is the fundamental characteristic of a supply chain needed for survival in turbulent markets, where environmental forces create additional uncertainty resulting in higher risk in the supply chain management. In addition, agility helps providing the right product, at the right time to the consumer. The main goal of this research is therefore to promote supplier selection in pharmaceutical industry according to the formative basic factors. Moreover, this paper can configure its supply network to achieve the agile supply chain. The present article analyzes the supply part of supply chain based on SCOR model, used to assess agile supply chains by highlighting their specific characteristics and applicability in providing the active pharmaceutical ingredient (API). This methodology provides an analytical modeling; the model enables potential suppliers to be assessed against the multiple criteria using both quantitative and qualitative measures. In addition, for making priority of critical factors, TOPSIS algorithm has been used as a common technique of MADM model. Finally, several factors such as delivery speed, planning and reorder segmentation, trust development and material quantity adjustment are identified and prioritized as critical factors for being agile in supply of API. PMID:24250689
Twist-writhe partitioning in a coarse-grained DNA minicircle model

NASA Astrophysics Data System (ADS)

Sayar, Mehmet; Avşaroǧlu, Barış; Kabakçıoǧlu, Alkan

2010-04-01

Here we present a systematic study of supercoil formation in DNA minicircles under varying linking number by using molecular-dynamics simulations of a two-bead coarse-grained model. Our model is designed with the purpose of simulating long chains without sacrificing the characteristic structural properties of the DNA molecule, such as its helicity, backbone directionality, and the presence of major and minor grooves. The model parameters are extracted directly from full-atomistic simulations of DNA oligomers via Boltzmann inversion; therefore, our results can be interpreted as an extrapolation of those simulations to presently inaccessible chain lengths and simulation times. Using this model, we measure the twist/writhe partitioning in DNA minicircles, in particular its dependence on the chain length and excess linking number. We observe an asymmetric supercoiling transition consistent with experiments. Our results suggest that the fraction of the linking number absorbed as twist and writhe is nontrivially dependent on chain length and excess linking number. Beyond the supercoiling transition, chains of the order of one persistence length carry equal amounts of twist and writhe. For longer chains, an increasing fraction of the linking number is absorbed by the writhe.
Supply-Chain Optimization Template

NASA Technical Reports Server (NTRS)

Quiett, William F.; Sealing, Scott L.

2009-01-01

The Supply-Chain Optimization Template (SCOT) is an instructional guide for identifying, evaluating, and optimizing (including re-engineering) aerospace- oriented supply chains. The SCOT was derived from the Supply Chain Council s Supply-Chain Operations Reference (SCC SCOR) Model, which is more generic and more oriented toward achieving a competitive advantage in business.
Markov Chain Estimation of Avian Seasonal Fecundity

EPA Science Inventory

To explore the consequences of modeling decisions on inference about avian seasonal fecundity we generalize previous Markov chain (MC) models of avian nest success to formulate two different MC models of avian seasonal fecundity that represent two different ways to model renestin...

Quantum criticality and duality in the Sachdev-Ye-Kitaev/AdS2 chain

NASA Astrophysics Data System (ADS)

Jian, Shao-Kai; Xian, Zhuo-Yu; Yao, Hong

2018-05-01

We show that the quantum critical point (QCP) between a diffusive metal and ferromagnetic (or antiferromagnetic) phases in the SYK chain has a gravitational description corresponding to the double-trace deformation in an AdS2 chain. Specifically, by studying a double-trace deformation of a Z2 scalar in an AdS2 chain where the Z2 scalar is dual to the order parameter in the SYK chain, we find that the susceptibility and renormalization group equation describing the QCP in the SYK chain can be exactly reproduced in the holographic model. Our results suggest that the infrared geometry in the gravity theory dual to the diffusive metal of the SYK chain is also an AdS2 chain. We further show that the transition in SYK model captures universal information about double-trace deformation in generic black holes with near horizon AdS2 space-time.
A systems-based approach for integrated design of materials, products and design process chains

NASA Astrophysics Data System (ADS)

Panchal, Jitesh H.; Choi, Hae-Jin; Allen, Janet K.; McDowell, David L.; Mistree, Farrokh

2007-12-01

The concurrent design of materials and products provides designers with flexibility to achieve design objectives that were not previously accessible. However, the improved flexibility comes at a cost of increased complexity of the design process chains and the materials simulation models used for executing the design chains. Efforts to reduce the complexity generally result in increased uncertainty. We contend that a systems based approach is essential for managing both the complexity and the uncertainty in design process chains and simulation models in concurrent material and product design. Our approach is based on simplifying the design process chains systematically such that the resulting uncertainty does not significantly affect the overall system performance. Similarly, instead of striving for accurate models for multiscale systems (that are inherently complex), we rely on making design decisions that are robust to uncertainties in the models. Accordingly, we pursue hierarchical modeling in the context of design of multiscale systems. In this paper our focus is on design process chains. We present a systems based approach, premised on the assumption that complex systems can be designed efficiently by managing the complexity of design process chains. The approach relies on (a) the use of reusable interaction patterns to model design process chains, and (b) consideration of design process decisions using value-of-information based metrics. The approach is illustrated using a Multifunctional Energetic Structural Material (MESM) design example. Energetic materials store considerable energy which can be released through shock-induced detonation; conventionally, they are not engineered for strength properties. The design objectives for the MESM in this paper include both sufficient strength and energy release characteristics. The design is carried out by using models at different length and time scales that simulate different aspects of the system. Finally, by applying the method to the MESM design problem, we show that the integrated design of materials and products can be carried out more efficiently by explicitly accounting for design process decisions with the hierarchy of models.
Wide-Angle X-Ray Scattering and Solid-State Nuclear Magnetic Resonance Data Combined to Test Models for Cellulose Microfibrils in Mung Bean Cell Walls1

PubMed Central

Newman, Roger H.; Hill, Stefan J.; Harris, Philip J.

2013-01-01

A synchrotron wide-angle x-ray scattering study of mung bean (Vigna radiata) primary cell walls was combined with published solid-state nuclear magnetic resonance data to test models for packing of (1→4)-β-glucan chains in cellulose microfibrils. Computer-simulated peak shapes, calculated for 36-chain microfibrils with perfect order or uncorrelated disorder, were sharper than those in the experimental diffractogram. Introducing correlated disorder into the models broaden the simulated peaks but only when the disorder was increased to unrealistic magnitudes. Computer-simulated diffractograms, calculated for 24- and 18-chain models, showed good fits to experimental data. Particularly good fits to both x-ray and nuclear magnetic resonance data were obtained for collections of 18-chain models with mixed cross-sectional shapes and occasional twinning. Synthesis of 18-chain microfibrils is consistent with a model for cellulose-synthesizing complexes in which three cellulose synthase polypeptides form a particle and six particles form a rosette. PMID:24154621
Modelling inter-supply chain competition with resource limitation and demand disruption

NASA Astrophysics Data System (ADS)

Chen, Zhaobo; Teng, Chunxian; Zhang, Ding; Sun, Jiayi

2016-05-01

This paper proposes a comprehensive model for studying supply chain versus supply chain competition with resource limitation and demand disruption. We assume that there are supply chains with heterogeneous supply network structures that compete at multiple demand markets. Each supply chain is comprised of internal and external firms. The internal firms are coordinated in production and distribution and share some common but limited resources within the supply chain, whereas the external firms are independent and do not share the internal resources. The supply chain managers strive to develop optimal strategies in terms of production level and resource allocation in maximising their profit while facing competition at the end market. The Cournot-Nash equilibrium of this inter-supply chain competition is formulated as a variational inequality problem. We further study the case when there is demand disruption in the plan-execution phase. In such a case, the managers need to revise their planned strategy in order to maximise their profit with the new demand under disruption and minimise the cost of change. We present a bi-criteria decision-making model for supply chain managers and develop the optimal conditions in equilibrium, which again can be formulated by another variational inequality problem. Numerical examples are presented for illustrative purpose.
Propagation of the Hawaiian-Emperor volcano chain by Pacific plate cooling stress

USGS Publications Warehouse

Stuart, W.D.; Foulger, G.R.; Barall, M.

2007-01-01

The lithosphere crack model, the main alternative to the mantle plume model for age-progressive magma emplacement along the Hawaiian-Emperor volcano chain, requires the maximum horizontal tensile stress to be normal to the volcano chain. However, published stress fields calculated from Pacific lithosphere tractions and body forces (e.g., subduction pull, basal drag, lithosphere density) are not optimal for southeast propagation of a stress-free, vertical tensile crack coincident with the Hawaiian segment of the Hawaiian-Emperor chain. Here we calculate the thermoelastic stress rate for present-day cooling of the Pacific plate using a spherical shell finite element representation of the plate geometry. We use observed seafloor isochrons and a standard model for lithosphere cooling to specify the time dependence of vertical temperature profiles. The calculated stress rate multiplied by a time increment (e.g., 1 m.y.) then gives a thermoelastic stress increment for the evolving Pacific plate. Near the Hawaiian chain position, the calculated stress increment in the lower part of the shell is tensional, with maximum tension normal to the chain direction. Near the projection of the chain trend to the southeast beyond Hawaii, the stress increment is compressive. This incremental stress field has the form necessary to maintain and propagate a tensile crack or similar lithosphere flaw and is thus consistent with the crack model for the Hawaiian volcano chain.?? 2007 The Geological Society of America.
Future Supply Chains Enabled by Continuous Processing—Opportunities and Challenges. May 20–21, 2014 Continuous Manufacturing Symposium

PubMed Central

Srai, Jagjit Singh; Badman, Clive; Krumme, Markus; Futran, Mauricio; Johnston, Craig

2015-01-01

This paper examines the opportunities and challenges facing the pharmaceutical industry in moving to a primarily “continuous processing”-based supply chain. The current predominantly “large batch” and centralized manufacturing system designed for the “blockbuster” drug has driven a slow-paced, inventory heavy operating model that is increasingly regarded as inflexible and unsustainable. Indeed, new markets and the rapidly evolving technology landscape will drive more product variety, shorter product life-cycles, and smaller drug volumes, which will exacerbate an already unsustainable economic model. Future supply chains will be required to enhance affordability and availability for patients and healthcare providers alike despite the increased product complexity. In this more challenging supply scenario, we examine the potential for a more pull driven, near real-time demand-based supply chain, utilizing continuous processing where appropriate as a key element of a more “flow-through” operating model. In this discussion paper on future supply chain models underpinned by developments in the continuous manufacture of pharmaceuticals, we have set out; The significant opportunities to moving to a supply chain flow-through operating model, with substantial opportunities in inventory reduction, lead-time to patient, and radically different product assurance/stability regimes. Scenarios for decentralized production models producing a greater variety of products with enhanced volume flexibility. Production, supply, and value chain footprints that are radically different from today's monolithic and centralized batch manufacturing operations. Clinical trial and drug product development cost savings that support more rapid scale-up and market entry models with early involvement of SC designers within New Product Development. The major supply chain and industrial transformational challenges that need to be addressed. The paper recognizes that although current batch operational performance in pharma is far from optimal and not necessarily an appropriate end-state benchmark for batch technology, the adoption of continuous supply chain operating models underpinned by continuous production processing, as full or hybrid solutions in selected product supply chains, can support industry transformations to deliver right-first-time quality at substantially lower inventory profiles. © 2015 The Authors. Journal of Pharmaceutical Sciences published by Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci 104:840–849, 2015 PMID:25631279
Coopetitive Supply Chain Relationship Model: Application to the Smartphone Manufacturing Network.

PubMed

Kwok, Jeremy Jie Ming; Lee, Dong-Yup

2015-01-01

Previous researches for understanding supply chain relationship have mostly focused on its vertical collaboration between buyers and suppliers. However, there have been some instances of volatile and stable collaborative relationships amongst competitors such as Apple-Samsung product manufacturer-component supplier relationship and airline alliances, respectively, which is recognized as coopetition. Even though there have been several qualitative studies and a number of game theory models on coopetition, it is rare to find any attempts on quantitative characterization of such coopetitive dynamic behavior in supply chain relationship. Hence, in this work, we formulated a MINLP model mathematically representing coopetitive relationships in a cost efficient supply chain network. In particular, the coopetition factor was newly introduced to measure the degree of coopetition among supply chain players and determine the optimal level of coopetition to engage in. The utility and practicality of the model were strongly demonstrated using a case study of a hypothetical smartphone supply chain network under different scenarios, thus proposing their strategically viable optimal interactions. Therefore, this exploratory study can herald a new era of global coopetitive business.
Coopetitive Supply Chain Relationship Model: Application to the Smartphone Manufacturing Network

PubMed Central

Kwok, Jeremy Jie Ming; Lee, Dong-Yup

2015-01-01

Previous researches for understanding supply chain relationship have mostly focused on its vertical collaboration between buyers and suppliers. However, there have been some instances of volatile and stable collaborative relationships amongst competitors such as Apple-Samsung product manufacturer-component supplier relationship and airline alliances, respectively, which is recognized as coopetition. Even though there have been several qualitative studies and a number of game theory models on coopetition, it is rare to find any attempts on quantitative characterization of such coopetitive dynamic behavior in supply chain relationship. Hence, in this work, we formulated a MINLP model mathematically representing coopetitive relationships in a cost efficient supply chain network. In particular, the coopetition factor was newly introduced to measure the degree of coopetition among supply chain players and determine the optimal level of coopetition to engage in. The utility and practicality of the model were strongly demonstrated using a case study of a hypothetical smartphone supply chain network under different scenarios, thus proposing their strategically viable optimal interactions. Therefore, this exploratory study can herald a new era of global coopetitive business. PMID:26186227
Irreversible Local Markov Chains with Rapid Convergence towards Equilibrium.

PubMed

Kapfer, Sebastian C; Krauth, Werner

2017-12-15

We study the continuous one-dimensional hard-sphere model and present irreversible local Markov chains that mix on faster time scales than the reversible heat bath or Metropolis algorithms. The mixing time scales appear to fall into two distinct universality classes, both faster than for reversible local Markov chains. The event-chain algorithm, the infinitesimal limit of one of these Markov chains, belongs to the class presenting the fastest decay. For the lattice-gas limit of the hard-sphere model, reversible local Markov chains correspond to the symmetric simple exclusion process (SEP) with periodic boundary conditions. The two universality classes for irreversible Markov chains are realized by the totally asymmetric SEP (TASEP), and by a faster variant (lifted TASEP) that we propose here. We discuss how our irreversible hard-sphere Markov chains generalize to arbitrary repulsive pair interactions and carry over to higher dimensions through the concept of lifted Markov chains and the recently introduced factorized Metropolis acceptance rule.
Irreversible Local Markov Chains with Rapid Convergence towards Equilibrium

NASA Astrophysics Data System (ADS)

Kapfer, Sebastian C.; Krauth, Werner

2017-12-01

We study the continuous one-dimensional hard-sphere model and present irreversible local Markov chains that mix on faster time scales than the reversible heat bath or Metropolis algorithms. The mixing time scales appear to fall into two distinct universality classes, both faster than for reversible local Markov chains. The event-chain algorithm, the infinitesimal limit of one of these Markov chains, belongs to the class presenting the fastest decay. For the lattice-gas limit of the hard-sphere model, reversible local Markov chains correspond to the symmetric simple exclusion process (SEP) with periodic boundary conditions. The two universality classes for irreversible Markov chains are realized by the totally asymmetric SEP (TASEP), and by a faster variant (lifted TASEP) that we propose here. We discuss how our irreversible hard-sphere Markov chains generalize to arbitrary repulsive pair interactions and carry over to higher dimensions through the concept of lifted Markov chains and the recently introduced factorized Metropolis acceptance rule.
Production and characterization of murine models of classic and intermediate maple syrup urine disease

PubMed Central

Homanics, Gregg E; Skvorak, Kristen; Ferguson, Carolyn; Watkins, Simon; Paul, Harbhajan S

2006-01-01

Background Maple Syrup Urine Disease (MSUD) is an inborn error of metabolism caused by a deficiency of branched-chain keto acid dehydrogenase. MSUD has several clinical phenotypes depending on the degree of enzyme deficiency. Current treatments are not satisfactory and require new approaches to combat this disease. A major hurdle in developing new treatments has been the lack of a suitable animal model. Methods To create a murine model of classic MSUD, we used gene targeting and embryonic stem cell technologies to create a mouse line that lacked a functional E2 subunit gene of branched-chain keto acid dehydrogenase. To create a murine model of intermediate MSUD, we used transgenic technology to express a human E2 cDNA on the knockout background. Mice of both models were characterized at the molecular, biochemical, and whole animal levels. Results By disrupting the E2 subunit gene of branched-chain keto acid dehydrogenase, we created a gene knockout mouse model of classic MSUD. The homozygous knockout mice lacked branched-chain keto acid dehydrogenase activity, E2 immunoreactivity, and had a 3-fold increase in circulating branched-chain amino acids. These metabolic derangements resulted in neonatal lethality. Transgenic expression of a human E2 cDNA in the liver of the E2 knockout animals produced a model of intermediate MSUD. Branched-chain keto acid dehydrogenase activity was 5–6% of normal and was sufficient to allow survival, but was insufficient to normalize circulating branched-chain amino acids levels, which were intermediate between wildtype and the classic MSUD mouse model. Conclusion These mice represent important animal models that closely approximate the phenotype of humans with the classic and intermediate forms of MSUD. These animals provide useful models to further characterize the pathogenesis of MSUD, as well as models to test novel therapeutic strategies, such as gene and cellular therapies, to treat this devastating metabolic disease. PMID:16579849
Population pharmacokinetics of recombinant coagulation factor VIII-SingleChain in patients with severe hemophilia A.

PubMed

Zhang, Y; Roberts, J; Tortorici, M; Veldman, A; St Ledger, K; Feussner, A; Sidhu, J

2017-06-01

Essentials rVIII-SingleChain is a unique recombinant factor VIII (FVIII) molecule. A population pharmacokinetic model was based on FVIII activity of severe hemophilia A patients. The model was used to simulate factor VIII activity-time profiles for various dosing scenarios. The model supports prolonged dosing of rVIII-SingleChain with intervals of up to twice per week. Background Single-chain recombinant coagulation factor VIII (rVIII-SingleChain) is a unique recombinant coagulation factor VIII molecule. Objectives To: (i) characterize the population pharmacokinetics (PK) of rVIII-SingleChain in patients with severe hemophilia A; (ii) identify correlates of variability in rVIII-SingleChain PK; and (iii) simulate various dosing scenarios of rVIII-SingleChain. Patients/Methods A population PK model was developed, based on FVIII activity levels of 130 patients with severe hemophilia A (n = 91 for ≥ 12-65 years; n = 39 for < 12 years) who had participated in a single-dose PK investigation with rVIII-SingleChain 50 IU kg -1 . PK sampling was performed for up to 96 h. Results A two-compartment population PK model with first-order elimination adequately described FVIII activity. Body weight and predose level of von Willebrand factor were significant covariates on clearance, and body weight was a significant covariate on the central distribution volume. Simulations using the model with various dosing scenarios estimated that > 85% and > 93% of patients were predicted to maintain FVIII activity level above 1 IU dL -1 , at all times with three-times-weekly dosing (given on days 0, 2, and 4.5) at the lowest (20 IU kg -1 ) and highest (50 IU kg -1 ) doses, respectively. For twice weekly dosing (days 0 and 3.5) of 50 IU kg -1 rVIII-SingleChain, 62-80% of patients across all ages were predicted to maintain a FVIII activity level above 1 IU dL -1 at day 7. Conclusions The population PK model adequately characterized rVIII-SingleChain PK, and the model can be utilized to simulate FVIII activity-time profiles for various dosing scenarios. © 2017 The Authors. Journal of Thrombosis and Haemostasis published by Wiley Periodicals, Inc. on behalf of International Society on Thrombosis and Haemostasis.
SCRL-Model for Human Space Flight Operations Enterprise Supply Chain

NASA Technical Reports Server (NTRS)

Tucker, Brian

2010-01-01

Standard approach to evaluate and configure adaptable and sustainable program and mission supply chains at an enterprise level. End-to-end view. Total Lifecycle. Evaluate the readiness of the supply chain during the supply chain development phase.
Markov chains for testing redundant software

NASA Technical Reports Server (NTRS)

White, Allan L.; Sjogren, Jon A.

1988-01-01

A preliminary design for a validation experiment has been developed that addresses several problems unique to assuring the extremely high quality of multiple-version programs in process-control software. The procedure uses Markov chains to model the error states of the multiple version programs. The programs are observed during simulated process-control testing, and estimates are obtained for the transition probabilities between the states of the Markov chain. The experimental Markov chain model is then expanded into a reliability model that takes into account the inertia of the system being controlled. The reliability of the multiple version software is computed from this reliability model at a given confidence level using confidence intervals obtained for the transition probabilities during the experiment. An example demonstrating the method is provided.
Unique Aspects of the Structure and Dynamics of Elementary Iβ Cellulose Microfibrils Revealed by Computational Simulations1[OPEN

PubMed Central

Oehme, Daniel P.; Downton, Matthew T.; Doblin, Monika S.; Wagner, John; Gidley, Michael J.; Bacic, Antony

2015-01-01

The question of how many chains an elementary cellulose microfibril contains is critical to understanding the molecular mechanism(s) of cellulose biosynthesis and regulation. Given the hexagonal nature of the cellulose synthase rosette, it is assumed that the number of chains must be a multiple of six. We present molecular dynamics simulations on three different models of Iβ cellulose microfibrils, 18, 24, and 36 chains, to investigate their structure and dynamics in a hydrated environment. The 36-chain model stays in a conformational space that is very similar to the initial crystalline phase, while the 18- and 24-chain models sample a conformational space different from the crystalline structure yet similar to conformations observed in recent high-temperature molecular dynamics simulations. Major differences in the conformations sampled between the different models result from changes to the tilt of chains in different layers, specifically a second stage of tilt, increased rotation about the O2-C2 dihedral, and a greater sampling of non-TG exocyclic conformations, particularly the GG conformation in center layers and GT conformation in solvent-exposed exocyclic groups. With a reinterpretation of nuclear magnetic resonance data, specifically for contributions made to the C6 peak, data from the simulations suggest that the 18- and 24-chain structures are more viable models for an elementary cellulose microfibril, which also correlates with recent scattering and diffraction experimental data. These data inform biochemical and molecular studies that must explain how a six-particle cellulose synthase complex rosette synthesizes microfibrils likely comprised of either 18 or 24 chains. PMID:25786828
Modeling logistic performance in quantitative microbial risk assessment.

PubMed

Rijgersberg, Hajo; Tromp, Seth; Jacxsens, Liesbeth; Uyttendaele, Mieke

2010-01-01

In quantitative microbial risk assessment (QMRA), food safety in the food chain is modeled and simulated. In general, prevalences, concentrations, and numbers of microorganisms in media are investigated in the different steps from farm to fork. The underlying rates and conditions (such as storage times, temperatures, gas conditions, and their distributions) are determined. However, the logistic chain with its queues (storages, shelves) and mechanisms for ordering products is usually not taken into account. As a consequence, storage times-mutually dependent in successive steps in the chain-cannot be described adequately. This may have a great impact on the tails of risk distributions. Because food safety risks are generally very small, it is crucial to model the tails of (underlying) distributions as accurately as possible. Logistic performance can be modeled by describing the underlying planning and scheduling mechanisms in discrete-event modeling. This is common practice in operations research, specifically in supply chain management. In this article, we present the application of discrete-event modeling in the context of a QMRA for Listeria monocytogenes in fresh-cut iceberg lettuce. We show the potential value of discrete-event modeling in QMRA by calculating logistic interventions (modifications in the logistic chain) and determining their significance with respect to food safety.
Closed loop supply chain network design with fuzzy tactical decisions

NASA Astrophysics Data System (ADS)

Sherafati, Mahtab; Bashiri, Mahdi

2016-09-01

One of the most strategic and the most significant decisions in supply chain management is reconfiguration of the structure and design of the supply chain network. In this paper, a closed loop supply chain network design model is presented to select the best tactical and strategic decision levels simultaneously considering the appropriate transportation mode in activated links. The strategic decisions are made for a long term; thus, it is more satisfactory and more appropriate when the decision variables are considered uncertain and fuzzy, because it is more flexible and near to the real world. This paper is the first research which considers fuzzy decision variables in the supply chain network design model. Moreover, in this study a new fuzzy optimization approach is proposed to solve a supply chain network design problem with fuzzy tactical decision variables. Finally, the proposed approach and model are verified using several numerical examples. The comparison of the results with other existing approaches confirms efficiency of the proposed approach. Moreover the results confirms that by considering the vagueness of tactical decisions some properties of the supply chain network will be improved.
Rouse mode analysis of chain relaxation in homopolymer melts

DOE PAGES

Kalathi, Jagannathan T.; Kumar, Sanat K.; Rubinstein, Michael; ...

2014-09-15

We use molecular dynamics simulations of the Kremer–Grest (KG) bead–spring model of polymer chains of length between 10 and 500, and a closely related analogue that allows for chain crossing, to clearly delineate the effects of entanglements on the length-scale-dependent chain relaxation in polymer melts. We analyze the resulting trajectories using the Rouse modes of the chains and find that entanglements strongly affect these modes. The relaxation rates of the chains show two limiting effective monomeric frictions, with the local modes experiencing much lower effective friction than the longer modes. The monomeric relaxation rates of longer modes vary approximately inverselymore » with chain length due to kinetic confinement effects. The time-dependent relaxation of Rouse modes has a stretched exponential character with a minimum of stretching exponent in the vicinity of the entanglement chain length. None of these trends are found in models that allow for chain crossing. As a result, these facts, in combination, argue for the confined motion of chains for time scales between the entanglement time and their ultimate free diffusion.« less
Nonmetallic electronegativity equalization and point-dipole interaction model including exchange interactions for molecular dipole moments and polarizabilities.

PubMed

Smalø, Hans S; Astrand, Per-Olof; Jensen, Lasse

2009-07-28

The electronegativity equalization model (EEM) has been combined with a point-dipole interaction model to obtain a molecular mechanics model consisting of atomic charges, atomic dipole moments, and two-atom relay tensors to describe molecular dipole moments and molecular dipole-dipole polarizabilities. The EEM has been phrased as an atom-atom charge-transfer model allowing for a modification of the charge-transfer terms to avoid that the polarizability approaches infinity for two particles at infinite distance and for long chains. In the present work, these shortcomings have been resolved by adding an energy term for transporting charges through individual atoms. A Gaussian distribution is adopted for the atomic charge distributions, resulting in a damping of the electrostatic interactions at short distances. Assuming that an interatomic exchange term may be described as the overlap between two electronic charge distributions, the EEM has also been extended by a short-range exchange term. The result is a molecular mechanics model where the difference of charge transfer in insulating and metallic systems is modeled regarding the difference in bond length between different types of system. For example, the model is capable of modeling charge transfer in both alkanes and alkenes with alternating double bonds with the same set of carbon parameters only relying on the difference in bond length between carbon sigma- and pi-bonds. Analytical results have been obtained for the polarizability of a long linear chain. These results show that the model is capable of describing the polarizability scaling both linearly and nonlinearly with the size of the system. Similarly, a linear chain with an end atom with a high electronegativity has been analyzed analytically. The dipole moment of this model system can either be independent of the length or increase linearly with the length of the chain. In addition, the model has been parametrized for alkane and alkene chains with data from density functional theory calculations, where the polarizability behaves differently with the chain length. For the molecular dipole moment, the same two systems have been studied with an aldehyde end group. Both the molecular polarizability and the dipole moment are well described as a function of the chain length for both alkane and alkene chains demonstrating the power of the presented model.
Evolutionary Game Model Study of Construction Green Supply Chain Management under the Government Intervention

NASA Astrophysics Data System (ADS)

Xing, Yuanzhi; Deng, Xiaoyi

2017-11-01

The paper first has defined the concepts of green supply chain management and evolution game theory, and pointed out the characteristics of green supply chain management in construction. The main participants and key links of the construction green supply chain management are determined by constructing the organization framework. This paper established the evolutionary game model between construction enterprises and recycling enterprises for the green supply chain closed-loop structure. The waste recycling evolutionary stability equilibrium solution is obtained to explore the principle and effective scope of government policy intervention. This paper put forward the relevant countermeasures to the green supply chain management in construction recycling stage from the government point of view. The conclusion has reference value and guidance to the final product construction enterprises, recycling enterprises and the government during green supply chain.

Scale-Dependent Stiffness and Internal Tension of a Model Brush Polymer

NASA Astrophysics Data System (ADS)

Berezney, John P.; Marciel, Amanda B.; Schroeder, Charles M.; Saleh, Omar A.

2017-09-01

Bottle-brush polymers exhibit closely grafted side chains that interact by steric repulsion, thereby causing stiffening of the main polymer chain. We use single-molecule elasticity measurements of model brush polymers to quantify this effect. We find that stiffening is only significant on long length scales, with the main chain retaining flexibility on short scales. From the elasticity data, we extract an estimate of the internal tension generated by side-chain repulsion; this estimate is consistent with the predictions of blob-based scaling theories.
Biodiversity on island chains: Neutral model simulations

NASA Astrophysics Data System (ADS)

Warren, Patrick B.

2010-11-01

A neutral ecology model is simulated on an island chain, in which neighboring islands can exchange individuals but only the first island is able to receive immigrants from a metacommunity. It is found by several measures that α -diversity decreases along the chain. Subtle changes in taxon abundance distributions can be detected when islands in the chain are compared to diversity-matched single islands. The island chain is found to have unexpectedly rich dynamics. Significant β -diversity correlations are found between islands in the chain, which are absent between diversity-matched single islands. The results potentially apply to human microbial biodiversity and biogeography and suggest that measurements of interindividual and intraindividual β -diversity may give insights into microbial community assembly mechanisms.
Simplification of irreversible Markov chains by removal of states with fast leaving rates.

PubMed

Jia, Chen

2016-07-07

In the recent work of Ullah et al. (2012a), the authors developed an effective method to simplify reversible Markov chains by removal of states with low equilibrium occupancies. In this paper, we extend this result to irreversible Markov chains. We show that an irreversible chain can be simplified by removal of states with fast leaving rates. Moreover, we reveal that the irreversibility of the chain will always decrease after model simplification. This suggests that although model simplification can retain almost all the dynamic information of the chain, it will lose some thermodynamic information as a trade-off. Examples from biology are also given to illustrate the main results of this paper. Copyright © 2016 Elsevier Ltd. All rights reserved.
An Interval Type-2 Fuzzy Multiple Echelon Supply Chain Model

NASA Astrophysics Data System (ADS)

Miller, Simon; John, Robert

Planning resources for a supply chain is a major factor determining its success or failure. In this paper we build on previous work introducing an Interval Type-2 Fuzzy Logic model of a multiple echelon supply chain. It is believed that the additional degree of uncertainty provided by Interval Type-2 Fuzzy Logic will allow for better representation of the uncertainty and vagueness present in resource planning models. First, the subject of Supply Chain Management is introduced, then some background is given on related work using Type-1 Fuzzy Logic. A description of the Interval Type-2 Fuzzy model is given, and a test scenario detailed. A Genetic Algorithm uses the model to search for a near-optimal plan for the scenario. A discussion of the results follows, along with conclusions and details of intended further work.
78 FR 24368 - Airworthiness Directives; Bell Helicopter Textron, Inc. (Bell) Model Helicopters

Federal Register 2010, 2011, 2012, 2013, 2014

2013-04-25

... chain and cable control system with a push-pull control system. Since we issued that AD, we have... requires replacing the existing chain and cable control system with a push-pull control system. Both... Model 205A-1 to replace the tail rotor chain and cable control system with a push-pull control system...
Peppytides: Interactive Models of Polypeptide Chains

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zuckermann, Ron; Chakraborty, Promita; Derisi, Joe

2014-01-21

Peppytides are scaled, 3D-printed models of polypeptide chains that can be folded into accurate protein structures. Designed and created by Berkeley Lab Researcher, Promita Chakraborty, and Berkeley Lab Senior Scientist, Dr. Ron Zuckermann, Peppytides are accurate physical models of polypeptide chains that anyone can interact with and fold intro various protein structures - proving to be a great educational tool, resulting in a deeper understanding of these fascinating structures and how they function. Build your own Peppytide model and learn about how nature's machines fold into their intricate architectures!
Peppytides: Interactive Models of Polypeptide Chains

ScienceCinema

Zuckermann, Ron; Chakraborty, Promita; Derisi, Joe

2018-06-08

Peppytides are scaled, 3D-printed models of polypeptide chains that can be folded into accurate protein structures. Designed and created by Berkeley Lab Researcher, Promita Chakraborty, and Berkeley Lab Senior Scientist, Dr. Ron Zuckermann, Peppytides are accurate physical models of polypeptide chains that anyone can interact with and fold intro various protein structures - proving to be a great educational tool, resulting in a deeper understanding of these fascinating structures and how they function. Build your own Peppytide model and learn about how nature's machines fold into their intricate architectures!
Survival condition for low-frequency quasi-one-dimensional breathers in a two-dimensional strongly anisotropic crystal

NASA Astrophysics Data System (ADS)

Savin, A. V.; Zubova, E. A.; Manevitch, L. I.

2005-06-01

We investigate a two-dimensional (2D) strongly anisotropic crystal (2D SAC) on substrate: 2D system of coupled linear chains of particles with strong intrachain and weak interchain interactions, each chain being subjected to the sine background potential. Nonlinear dynamics of one of these chains when the rest of them are fixed is reduced to the well known Frenkel-Kontorova (FK) model. Depending on strengh of the substrate, the 2D SAC models a variety of physical systems: polymer crystals with identical chains having light side groups, an array of inductively coupled long Josephson junctions, anisotropic crystals having light and heavy sublattices. Continuum limit of the FK model, the sine-Gordon (sG) equation, allows two types of soliton solutions: topological solitons and breathers. It is known that the quasi-one-dimensional topological solitons can propagate also in a chain of 2D system of coupled chains and even in a helix chain in a three-dimensional model of polymer crystal. In contrast to this, numerical simulation shows that the long-living breathers inherent to the FK model do not exist in the 2D SAC with weak background potential. The effect changes scenario of kink-antikink collision with small relative velocity: at weak background potential the collision always results only in intensive phonon radiation while kink-antikink recombination in the FK model results in long-living low-frequency sG breather creation. We found the survival condition for breathers in the 2D SAC on substrate depending on breather frequency and strength of the background potential. The survival condition bears no relation to resonances between breather frequency and frequencies of phonon band—contrary to the case of the FK model.
Peroxy radical detection by chemical amplification (PERCA)

NASA Technical Reports Server (NTRS)

Stedman, D. H.

1986-01-01

Important reactions of atmospheric free radicals are the chain oxidation of NO and CO. Thus: H2O + NO yields OH + NO2; OH + CO yields H + CO2; H + O2 + M yields HO2 + M. In most models, the need to know the free radical concentration could also be described as the need to know the rate of the above oxidation chain in the atmosphere. It is the total rate of this chain (also carried by RO2 and RO) which was measured using the PERCA. The PERCA is thus essentially a RO sub X meter. The PERCA works by adding excess CO (10%) and NO (5ppm) to a stream of air and measuring the NO2 produced after 3s of reaction time. Since other processes produce NO2, the chain reaction is modulated by switching the CO for N2. The chain length is limited by the reaction OH + NO yields HONO and is modeled to be somewhat over 1000. Measured chain lengths agree with the modeled numbers.
Orientation of chain molecules in ionotropic gels: a Brownian dynamics model

NASA Astrophysics Data System (ADS)

Woelki, Stefan; Kohler, Hans-Helmut

2003-09-01

As is known from birefringence measurements, polysaccharide molecules of ionotropic gels are preferentially orientated normal to the direction of gel growth. In this paper the orientation effect is investigated by means of an off-lattice Brownian dynamics model simulating the gel formation process. The model describes the integration of a single coarse grained phantom chain into the growing gel. The equations of motion of the chain are derived. The computer simulations show that, during the process of integration, the chain is contracting normal to the direction of gel growth. A scaling relation is obtained for the degree of contraction as a function of the length parameters of the chain, the velocity of the gel formation front and the rate constant of the crosslinking reaction. It is shown that the scaling relation, if applied to the example of ionotropic copper alginate gel, leads to reasonable predictions of the time course of the degree of contraction of the alginate chains.
Assessment of Protein Side-Chain Conformation Prediction Methods in Different Residue Environments

PubMed Central

Peterson, Lenna X.; Kang, Xuejiao; Kihara, Daisuke

2016-01-01

Computational prediction of side-chain conformation is an important component of protein structure prediction. Accurate side-chain prediction is crucial for practical applications of protein structure models that need atomic detailed resolution such as protein and ligand design. We evaluated the accuracy of eight side-chain prediction methods in reproducing the side-chain conformations of experimentally solved structures deposited to the Protein Data Bank. Prediction accuracy was evaluated for a total of four different structural environments (buried, surface, interface, and membrane-spanning) in three different protein types (monomeric, multimeric, and membrane). Overall, the highest accuracy was observed for buried residues in monomeric and multimeric proteins. Notably, side-chains at protein interfaces and membrane-spanning regions were better predicted than surface residues even though the methods did not all use multimeric and membrane proteins for training. Thus, we conclude that the current methods are as practically useful for modeling protein docking interfaces and membrane-spanning regions as for modeling monomers. PMID:24619909
SCRL-Model for Human Space Flight Operations Enterprise Supply Chain

NASA Technical Reports Server (NTRS)

Tucker, Brian; Paxton, Joseph

2010-01-01

This paper will present a Supply Chain Readiness Level (SCRL) model that can be used to evaluate and configure adaptable and sustainable program and mission supply chains at an enterprise level. It will also show that using SCRL in conjunction with Technology Readiness Levels (TRLs), Manufacturing Readiness Levels (MRLs) and National Aeronautics Space Administrations (NASA s) Project Lifecycle Process will provide a more complete means of developing and evaluating a robust sustainable supply chain that encompasses the entire product, system and mission lifecycle. In addition, it will be shown that by implementing the SCRL model, NASA can additionally define supplier requirements to enable effective supply chain management (SCM). Developing and evaluating overall supply chain readiness for any product, system and mission lifecycle is critical for mission success. Readiness levels are presently being used to evaluate the maturity of technology and manufacturing capability during development and deployment phases of products and systems. For example, TRLs are used to support the assessment of the maturity of a particular technology and compare maturity of different types of technologies. MRLs are designed to assess the maturity and risk of a given technology from a manufacturing perspective. In addition, when these measurement systems are used collectively they can offer a more comprehensive view of the maturity of the system. While some aspects of the supply chain and supply chain planning are considered in these familiar metric systems, certain characteristics of an effective supply chain, when evaluated in more detail, will provide an improved insight into the readiness and risk throughout the supply chain. Therefore, a system that concentrates particularly on supply chain attributes is required to better assess enterprise supply chain readiness.
An investigation into UV light exposure as an experimental model for artificial aging on tensile strength and force delivery of elastomeric chain.

PubMed

Wahab, Siti Waznah; Bister, Dirk; Sherriff, Martyn

2014-02-01

This study investigated the effect of ultraviolet type A light (UVA) exposure on the tensile properties of elastomeric chain. UVA light exposure was used as model for artificial aging, simulating prolonged storage of elastomeric chain. Tensile strength (n = 60) was measured after exposing Ormco, Forestadent and 3M chains to UVA light for 0, 2, 3, and 4 weeks. Force decay was measured (n = 60) using chain exposed for 5, 10, and 14 days. The chains were subsequently stretched at a constant distance and the resulting forces measured at 0, 1, 24 hours and 7, 14, 21, and 28 days. This test simulated a clinical scenario of pre-stretching and subsequent shortening of elastomeric chain. Tensile strength had statistically significant difference and was directly related to the duration of ultraviolet (UV) light exposure. Forestadent chain, which had the second highest value for the 'as received' product, showed the most consistent values over time with the lowest degradation. Ormco showed the lowest values for 'as received' as well as after UV exposure; 3M chain had the highest loss of tensile strength. Force decay was also significantly different. UV light exposure of 10 days or more appears to mark a 'watershed' between products: 3M had most survivors, Forestadent chain had some survivors, depending on the time the chain was stretched for. None of the Ormco product survived UV light exposure for more than 5 days. UVA light exposure may be used as a model for artificial aging as it reduces force delivery and tensile strength of exposed chains.
Conditional solvation thermodynamics of isoleucine in model peptides and the limitations of the group-transfer model.

PubMed

Tomar, Dheeraj S; Weber, Valéry; Pettitt, B Montgomery; Asthagiri, D

2014-04-17

The hydration thermodynamics of the amino acid X relative to the reference G (glycine) or the hydration thermodynamics of a small-molecule analog of the side chain of X is often used to model the contribution of X to protein stability and solution thermodynamics. We consider the reasons for successes and limitations of this approach by calculating and comparing the conditional excess free energy, enthalpy, and entropy of hydration of the isoleucine side chain in zwitterionic isoleucine, in extended penta-peptides, and in helical deca-peptides. Butane in gauche conformation serves as a small-molecule analog for the isoleucine side chain. Parsing the hydrophobic and hydrophilic contributions to hydration for the side chain shows that both of these aspects of hydration are context-sensitive. Furthermore, analyzing the solute-solvent interaction contribution to the conditional excess enthalpy of the side chain shows that what is nominally considered a property of the side chain includes entirely nonobvious contributions of the background. The context-sensitivity of hydrophobic and hydrophilic hydration and the conflation of background contributions with energetics attributed to the side chain limit the ability of a single scaling factor, such as the fractional solvent exposure of the group in the protein, to map the component energetic contributions of the model-compound data to their value in the protein. But ignoring the origin of cancellations in the underlying components the group-transfer model may appear to provide a reasonable estimate of the free energy for a given error tolerance.
Selective and directional actuation of elastomer films using chained magnetic nanoparticles

NASA Astrophysics Data System (ADS)

Mishra, Sumeet R.; Dickey, Michael D.; Velev, Orlin D.; Tracy, Joseph B.

2016-01-01

We report selective and directional actuation of elastomer films utilizing magnetic anisotropy introduced by chains of Fe3O4 magnetic nanoparticles (MNPs). Under uniform magnetic fields or field gradients, dipolar interactions between the MNPs favor magnetization along the chain direction and cause selective lifting. This mechanism is described using a simple model.We report selective and directional actuation of elastomer films utilizing magnetic anisotropy introduced by chains of Fe3O4 magnetic nanoparticles (MNPs). Under uniform magnetic fields or field gradients, dipolar interactions between the MNPs favor magnetization along the chain direction and cause selective lifting. This mechanism is described using a simple model. Electronic supplementary information (ESI) available: Two videos for actuation while rotating the sample, experimental details of nanoparticle synthesis, polymer composite preparation, and alignment and bending studies, details of the theoretical model of actuation, and supplemental figures for understanding the behavior of rotating samples and results from modelling. See DOI: 10.1039/c5nr07410j
Directed Bak-Sneppen Model for Food Chains

NASA Astrophysics Data System (ADS)

Stauffer, D.; Jan, N.

A modification of the Bak-Sneppen model to include simple elements of Darwinian evolution is used to check the survival of prey and predators in long food chains. Mutations, selection, and starvation resulting from depleted prey are incorporated in this model.
Residue-Specific Side-Chain Polymorphisms via Particle Belief Propagation.

PubMed

Ghoraie, Laleh Soltan; Burkowski, Forbes; Li, Shuai Cheng; Zhu, Mu

2014-01-01

Protein side chains populate diverse conformational ensembles in crystals. Despite much evidence that there is widespread conformational polymorphism in protein side chains, most of the X-ray crystallography data are modeled by single conformations in the Protein Data Bank. The ability to extract or to predict these conformational polymorphisms is of crucial importance, as it facilitates deeper understanding of protein dynamics and functionality. In this paper, we describe a computational strategy capable of predicting side-chain polymorphisms. Our approach extends a particular class of algorithms for side-chain prediction by modeling the side-chain dihedral angles more appropriately as continuous rather than discrete variables. Employing a new inferential technique known as particle belief propagation, we predict residue-specific distributions that encode information about side-chain polymorphisms. Our predicted polymorphisms are in relatively close agreement with results from a state-of-the-art approach based on X-ray crystallography data, which characterizes the conformational polymorphisms of side chains using electron density information, and has successfully discovered previously unmodeled conformations.
Side-chain mobility in the folded state of Myoglobin

NASA Astrophysics Data System (ADS)

Lammert, Heiko; Onuchic, Jose

We study the accessibility of alternative side-chain rotamer configurations in the native state of Myoglobin, using an all-atom structure-based model. From long, unbiased simulation trajectories we determine occupancies of rotameric states and also estimate configurational and vibrational entropies. Direct sampling of the full native-state dynamics, enabled by the simple model, reveals facilitation of side-chain motions by backbone dynamics. Correlations between different dihedral angles are quantified and prove to be weak. We confirm global trends in the mobilities of side-chains, following burial and also the chemical character of residues. Surface residues loose little configurational entropy upon folding; side-chains contribute significantly to the entropy of the folded state. Mobilities of buried side-chains vary strongly with temperature. At ambient temperature, individual side-chains in the core of the protein gain substantial access to alternative rotamers, with occupancies that are likely observable experimentally. Finally, the dynamics of buried side-chains may be linked to the internal pockets, available to ligand gas molecules in Myoglobin.
Modeling and Implementation of Cattle/Beef Supply Chain Traceability Using a Distributed RFID-Based Framework in China.

PubMed

Liang, Wanjie; Cao, Jing; Fan, Yan; Zhu, Kefeng; Dai, Qiwei

2015-01-01

In recent years, traceability systems have been developed as effective tools for improving the transparency of supply chains, thereby guaranteeing the quality and safety of food products. In this study, we proposed a cattle/beef supply chain traceability model and a traceability system based on radio frequency identification (RFID) technology and the EPCglobal network. First of all, the transformations of traceability units were defined and analyzed throughout the cattle/beef chain. Secondly, we described the internal and external traceability information acquisition, transformation, and transmission processes throughout the beef supply chain in detail, and explained a methodology for modeling traceability information using the electronic product code information service (EPCIS) framework. Then, the traceability system was implemented based on Fosstrak and FreePastry software packages, and animal ear tag code and electronic product code (EPC) were employed to identify traceability units. Finally, a cattle/beef supply chain included breeding business, slaughter and processing business, distribution business and sales outlet was used as a case study to evaluate the beef supply chain traceability system. The results demonstrated that the major advantages of the traceability system are the effective sharing of information among business and the gapless traceability of the cattle/beef supply chain.
Modeling and Implementation of Cattle/Beef Supply Chain Traceability Using a Distributed RFID-Based Framework in China

PubMed Central

Liang, Wanjie; Cao, Jing; Fan, Yan; Zhu, Kefeng; Dai, Qiwei

2015-01-01

In recent years, traceability systems have been developed as effective tools for improving the transparency of supply chains, thereby guaranteeing the quality and safety of food products. In this study, we proposed a cattle/beef supply chain traceability model and a traceability system based on radio frequency identification (RFID) technology and the EPCglobal network. First of all, the transformations of traceability units were defined and analyzed throughout the cattle/beef chain. Secondly, we described the internal and external traceability information acquisition, transformation, and transmission processes throughout the beef supply chain in detail, and explained a methodology for modeling traceability information using the electronic product code information service (EPCIS) framework. Then, the traceability system was implemented based on Fosstrak and FreePastry software packages, and animal ear tag code and electronic product code (EPC) were employed to identify traceability units. Finally, a cattle/beef supply chain included breeding business, slaughter and processing business, distribution business and sales outlet was used as a case study to evaluate the beef supply chain traceability system. The results demonstrated that the major advantages of the traceability system are the effective sharing of information among business and the gapless traceability of the cattle/beef supply chain. PMID:26431340

Prime Contract Awards Alphabetically by Contractor, By State or Country, and Place, FY 84. Part 4. (Eastern Car Construction Company - General Displays Company).

DTIC Science & Technology

1984-01-01

8217(-O0I0D 0 <C 4 4 00 0i)-0 N Z ( N- 10 00 *- ZO I o Q) <C W0Z -001 - 00 -0001- o j -ZO 0O0O- F- z0 CCi)00 4 - i co0 0: O (1) CL C00I De ) 0 I) -WL)C 0 0m 0...000 04440000 Iu.0 -, 0 0 0 DZIL DE CD LbLL Z D Z Z DI z 00 U IQC )()M-r q- Ml P, - (1 A -Nv -NvN 0.4 N. 0 0 )o C0nNO0n 00 L0 0-V o D-000-00ON -’ . 0 In...00000 00 NO ... OO 000 40 KO < DE ~ - -# 4c M Wi) wC - V0 00) 0)Ci) 0 0 ( 0N 0 )0)0I i N If N C) W _j O~D 10 0 x JN00 00 0-1 40 0 0 4- j <iWi- -O woo
Falling Chains as Variable-Mass Systems: Theoretical Model and Experimental Analysis

ERIC Educational Resources Information Center

de Sousa, Celia A.; Gordo, Paulo M.; Costa, Pedro

2012-01-01

In this paper, we revisit, theoretically and experimentally, the fall of a folded U-chain and of a pile-chain. The model calculation implies the division of the whole system into two subsystems of variable mass, allowing us to explore the role of tensional contact forces at the boundary of the subsystems. This justifies, for instance, that the…
Simulation modelling of central order processing system under resource sharing strategy in demand-driven garment supply chains

NASA Astrophysics Data System (ADS)

Ma, K.; Thomassey, S.; Zeng, X.

2017-10-01

In this paper we proposed a central order processing system under resource sharing strategy for demand-driven garment supply chains to increase supply chain performances. We examined this system by using simulation technology. Simulation results showed that significant improvement in various performance indicators was obtained in new collaborative model with proposed system.
Assessment of land suitability for olive mill wastewater disposal site selection by integrating fuzzy logic, AHP, and WLC in a GIS.

PubMed

Aydi, Abdelwaheb; Abichou, Tarek; Nasr, Imen Hamdi; Louati, Mourad; Zairi, Moncef

2016-01-01

This paper presents a geographic information system-based multi-criteria site selection tool of an olive mill wastewater (OMW) disposal site in Sidi Bouzid Region, Tunisia. The multi-criteria decision framework integrates ten constraints and six factors that relate to environmental and economic concerns, and builds a hierarchy model for OMW disposal site suitability. The methodology is used for preliminary assessment of the most suitable OMW disposal sites by combining fuzzy set theory and analytic hierarchy process (AHP). The fuzzy set theory is used to standardize factors using different fuzzy membership functions while the AHP is used to establish the relative importance of the criteria. The AHP makes pairwise comparisons of relative importance between hierarchy elements grouped by both environmental and economic decision criteria. The OMW disposal site suitability is achieved by applying a weighted linear combination that uses a comparison matrix to aggregate different importance scenarios associated with environmental and economic objectives. Three different scenarios generated by different weights applied to the two objectives. The scenario (a) assigns a weight of 0.75 to the environmental and 0.25 to the economic objective, scenario (b) has equal weights, and scenario (c) features weights of 0.25 and 0.75 for environmental and economic objectives, respectively. The results from this study assign the least suitable OMW disposal site of 2.5 % when environmental and economic objectives are rated equally, while a more suitable OMW disposal site of 1.0 % is generated when the economic objective is rated higher.
Multi-Criteria Analysis for Solar Farm Location Suitability

NASA Astrophysics Data System (ADS)

Mierzwiak, Michal; Calka, Beata

2017-12-01

Currently the number of solar farms, as a type of renewable sources of energy, is growing rapidly. Photovoltaic power stations have many advantages, which is an incentive for their building and development. Solar energy is readily available and inexhaustible, and its production is environmentally friendly. In the present study multiple environmental and economic criteria were taken into account to select a potential photovoltaic farm location, with particular emphasis on: protected areas, land cover, solar radiation, slope angle, proximity to roads, built-up areas, and power lines. Advanced data analysis were used because of the multiplicity of criteria and their diverse influence on the choice of a potential location. They included the spatial analysis, the Weighted Linear Combination Technique (WLC), and the Analytic Hierarchy Process (AHP) as a decisionmaking method. The analysis was divided into two stages. In the first one, the areas where the location of solar farms was not possible were excluded. In the second one, the best locations meeting all environmental and economic criteria were selected. The research was conducted for the Legionowo District, using data from national surveying and mapping resources such as: BDOT10k (Database of Topographic Objects), NMT (Numerical Terrain Model), and lands and buildings register. Finally, several areas meeting the criteria were chosen. The research deals with solar farms with up to 40 kW power. The results of the study are presented as thematic maps. The advantage of the method is its versatility. It can be used not only for any area, but with little modification of the criteria, it can also be applied to choose a location for wind farms.
Modelisation de l'historique d'operation de groupes turbine-alternateur

NASA Astrophysics Data System (ADS)

Szczota, Mickael

Because of their ageing fleet, the utility managers are increasingly in needs of tools that can help them to plan efficiently maintenance operations. Hydro-Quebec started a project that aim to foresee the degradation of their hydroelectric runner, and use that information to classify the generating unit. That classification will help to know which generating unit is more at risk to undergo a major failure. Cracks linked to the fatigue phenomenon are a predominant degradation mode and the loading sequences applied to the runner is a parameter impacting the crack growth. So, the aim of this memoir is to create a generator able to generate synthetic loading sequences that are statistically equivalent to the observed history. Those simulated sequences will be used as input in a life assessment model. At first, we describe how the generating units are operated by Hydro-Quebec and analyse the available data, the analysis shows that the data are non-stationnary. Then, we review modelisation and validation methods. In the following chapter a particular attention is given to a precise description of the validation and comparison procedure. Then, we present the comparison of three kind of model : Discrete Time Markov Chains, Discrete Time Semi-Markov Chains and the Moving Block Bootstrap. For the first two models, we describe how to take account for the non-stationnarity. Finally, we show that the Markov Chain is not adapted for our case, and that the Semi-Markov chains are better when they include the non-stationnarity. The final choice between Semi-Markov Chains and the Moving Block Bootstrap depends of the user. But, with a long term vision we recommend the use of Semi-Markov chains for their flexibility. Keywords: Stochastic models, Models validation, Reliability, Semi-Markov Chains, Markov Chains, Bootstrap
Unique aspects of the structure and dynamics of elementary Iβ cellulose microfibrils revealed by computational simulations.

PubMed

Oehme, Daniel P; Downton, Matthew T; Doblin, Monika S; Wagner, John; Gidley, Michael J; Bacic, Antony

2015-05-01

The question of how many chains an elementary cellulose microfibril contains is critical to understanding the molecular mechanism(s) of cellulose biosynthesis and regulation. Given the hexagonal nature of the cellulose synthase rosette, it is assumed that the number of chains must be a multiple of six. We present molecular dynamics simulations on three different models of Iβ cellulose microfibrils, 18, 24, and 36 chains, to investigate their structure and dynamics in a hydrated environment. The 36-chain model stays in a conformational space that is very similar to the initial crystalline phase, while the 18- and 24-chain models sample a conformational space different from the crystalline structure yet similar to conformations observed in recent high-temperature molecular dynamics simulations. Major differences in the conformations sampled between the different models result from changes to the tilt of chains in different layers, specifically a second stage of tilt, increased rotation about the O2-C2 dihedral, and a greater sampling of non-TG exocyclic conformations, particularly the GG conformation in center layers and GT conformation in solvent-exposed exocyclic groups. With a reinterpretation of nuclear magnetic resonance data, specifically for contributions made to the C6 peak, data from the simulations suggest that the 18- and 24-chain structures are more viable models for an elementary cellulose microfibril, which also correlates with recent scattering and diffraction experimental data. These data inform biochemical and molecular studies that must explain how a six-particle cellulose synthase complex rosette synthesizes microfibrils likely comprised of either 18 or 24 chains. © 2015 American Society of Plant Biologists. All Rights Reserved.
A Framework of Multi Objectives Negotiation for Dynamic Supply Chain Model

NASA Astrophysics Data System (ADS)

Chai, Jia Yee; Sakaguchi, Tatsuhiko; Shirase, Keiichi

Trends of globalization and advances in Information Technology (IT) have created opportunity in collaborative manufacturing across national borders. A dynamic supply chain utilizes these advances to enable more flexibility in business cooperation. This research proposes a concurrent decision making framework for a three echelons dynamic supply chain model. The dynamic supply chain is formed by autonomous negotiation among agents based on multi agents approach. Instead of generating negotiation aspects (such as amount, price and due date) arbitrary, this framework proposes to utilize the information available at operational level of an organization in order to generate realistic negotiation aspect. The effectiveness of the proposed model is demonstrated by various case studies.
Thermodynamic limit and boundary energy of the su(3) spin chain with non-diagonal boundary fields

NASA Astrophysics Data System (ADS)

Wen, Fakai; Yang, Tao; Yang, Zhanying; Cao, Junpeng; Hao, Kun; Yang, Wen-Li

2017-02-01

We investigate the thermodynamic limit of the su (n)-invariant spin chain models with unparallel boundary fields. It is found that the contribution of the inhomogeneous term in the associated T-Q relation to the ground state energy does vanish in the thermodynamic limit. This fact allows us to calculate the boundary energy of the system. Taking the su (2) (or the XXX) spin chain and the su (3) spin chain as concrete examples, we have studied the corresponding boundary energies of the models. The method used in this paper can be generalized to study the thermodynamic properties and boundary energy of other high rank models with non-diagonal boundary fields.
SAChES: Scalable Adaptive Chain-Ensemble Sampling.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Swiler, Laura Painton; Ray, Jaideep; Ebeida, Mohamed Salah

We present the development of a parallel Markov Chain Monte Carlo (MCMC) method called SAChES, Scalable Adaptive Chain-Ensemble Sampling. This capability is targed to Bayesian calibration of com- putationally expensive simulation models. SAChES involves a hybrid of two methods: Differential Evo- lution Monte Carlo followed by Adaptive Metropolis. Both methods involve parallel chains. Differential evolution allows one to explore high-dimensional parameter spaces using loosely coupled (i.e., largely asynchronous) chains. Loose coupling allows the use of large chain ensembles, with far more chains than the number of parameters to explore. This reduces per-chain sampling burden, enables high-dimensional inversions and the usemore » of computationally expensive forward models. The large number of chains can also ameliorate the impact of silent-errors, which may affect only a few chains. The chain ensemble can also be sampled to provide an initial condition when an aberrant chain is re-spawned. Adaptive Metropolis takes the best points from the differential evolution and efficiently hones in on the poste- rior density. The multitude of chains in SAChES is leveraged to (1) enable efficient exploration of the parameter space; and (2) ensure robustness to silent errors which may be unavoidable in extreme-scale computational platforms of the future. This report outlines SAChES, describes four papers that are the result of the project, and discusses some additional results.« less
Designing Performance Measurement For Supply Chain's Actors And Regulator Using Scale Balanced Scorecard And Data Envelopment Analysis

NASA Astrophysics Data System (ADS)

Kusrini, Elisa; Subagyo; Aini Masruroh, Nur

2016-01-01

This research is a sequel of the author's earlier conducted researches in the fields of designing of integrated performance measurement between supply chain's actors and regulator. In the previous paper, the design of performance measurement is done by combining Balanced Scorecard - Supply Chain Operation Reference - Regulator Contribution model and Data Envelopment Analysis. This model referred as B-S-Rc-DEA model. The combination has the disadvantage that all the performance variables have the same weight. This paper investigates whether by giving weight to performance variables will produce more sensitive performance measurement in detecting performance improvement. Therefore, this paper discusses the development of the model B-S-Rc-DEA by giving weight to its performance'variables. This model referred as Scale B-S-Rc-DEA model. To illustrate the model of development, some samples from small medium enterprises of leather craft industry supply chain in province of Yogyakarta, Indonesia are used in this research. It is found that Scale B-S-Rc-DEA model is more sensitive to detecting performance improvement than B-S- Rc-DEA model.
Molecular weight kinetics and chain scission models for dextran polymers during ultrasonic degradation.

PubMed

Pu, Yuanyuan; Zou, Qingsong; Hou, Dianzhi; Zhang, Yiping; Chen, Shan

2017-01-20

Ultrasonic degradation of six dextran samples with different initial molecular weights (IMW) has been performed to investigate the degradation behavior and chain scission mechanism of dextrans. The weight-average molecular weight (Mw) and polydispersity index (D value) were monitored by High Performance Gel Permeation Chromatography (HPGPC). Results showed that Mw and D value decreased with increasing ultrasonic time, resulting in a more homologous dextran solution with lower molecular weight. A significant degradation occurred in dextrans with higher IMW, particularly at the initial stage of the ultrasonic treatment. The Malhotra model was found to well describe the molecular weight kinetics for all dextran samples. Experimental data was fitted into two chain scission models to study dextran chain scission mechanism and the model performance was compared. Results indicated that the midpoint scission model agreed well with experimental results, with a linear regression factor of R 2 >0.99. Copyright © 2016 Elsevier Ltd. All rights reserved.
Protein structure modeling for CASP10 by multiple layers of global optimization.

PubMed

Joo, Keehyoung; Lee, Juyong; Sim, Sangjin; Lee, Sun Young; Lee, Kiho; Heo, Seungryong; Lee, In-Ho; Lee, Sung Jong; Lee, Jooyoung

2014-02-01

In the template-based modeling (TBM) category of CASP10 experiment, we introduced a new protocol called protein modeling system (PMS) to generate accurate protein structures in terms of side-chains as well as backbone trace. In the new protocol, a global optimization algorithm, called conformational space annealing (CSA), is applied to the three layers of TBM procedure: multiple sequence-structure alignment, 3D chain building, and side-chain re-modeling. For 3D chain building, we developed a new energy function which includes new distance restraint terms of Lorentzian type (derived from multiple templates), and new energy terms that combine (physical) energy terms such as dynamic fragment assembly (DFA) energy, DFIRE statistical potential energy, hydrogen bonding term, etc. These physical energy terms are expected to guide the structure modeling especially for loop regions where no template structures are available. In addition, we developed a new quality assessment method based on random forest machine learning algorithm to screen templates, multiple alignments, and final models. For TBM targets of CASP10, we find that, due to the combination of three stages of CSA global optimizations and quality assessment, the modeling accuracy of PMS improves at each additional stage of the protocol. It is especially noteworthy that the side-chains of the final PMS models are far more accurate than the models in the intermediate steps. Copyright © 2013 Wiley Periodicals, Inc.
Event-chain algorithm for the Heisenberg model: Evidence for z≃1 dynamic scaling.

PubMed

Nishikawa, Yoshihiko; Michel, Manon; Krauth, Werner; Hukushima, Koji

2015-12-01

We apply the event-chain Monte Carlo algorithm to the three-dimensional ferromagnetic Heisenberg model. The algorithm is rejection-free and also realizes an irreversible Markov chain that satisfies global balance. The autocorrelation functions of the magnetic susceptibility and the energy indicate a dynamical critical exponent z≈1 at the critical temperature, while that of the magnetization does not measure the performance of the algorithm. We show that the event-chain Monte Carlo algorithm substantially reduces the dynamical critical exponent from the conventional value of z≃2.
Distribution Free Approach for Coordination of a Supply Chain with Consumer Return

NASA Astrophysics Data System (ADS)

Hu, Jinsong; Xu, Yuanji

Consumer return is considered in a coordination of a supply chain consisting of one manufacturer and one retailer. A distribution free approach is employed to deal with a centralized decision model and a decentralized model which are constructed under the situation with only knowing the demand function's mean and variance, respectively. A markdown money contract is designed to coordinate the supply chain, and it is also proved that the contract can make the supply chain perfectly coordinated. Several numerical examples are given at the end of this paper.
Single-chain behavior of poly(3-hexylthiophene)

NASA Astrophysics Data System (ADS)

Ivanov, Momchil; Gross, Jonathan; Janke, Wolfhard

2017-03-01

Poly(3-hexylthiophene) (P3HT) has been in the focus of recent studies due to its promising future use in organic photovoltaics, electronics and photonics. Recent publications investigate the melt behavior of P3HT, its interaction with other molecules, mainly various fullerene derivates, and isolated chains interacting with substrates. In this work we lay the focus on the single-chain properties of P3HT in vacuum. We compare structural properties obtained from simulations using two coarse-grained models and an atomistic model of the polymer for various chain lengths and temperatures.
Enhancement of Markov chain model by integrating exponential smoothing: A case study on Muslims marriage and divorce

NASA Astrophysics Data System (ADS)

Jamaluddin, Fadhilah; Rahim, Rahela Abdul

2015-12-01

Markov Chain has been introduced since the 1913 for the purpose of studying the flow of data for a consecutive number of years of the data and also forecasting. The important feature in Markov Chain is obtaining the accurate Transition Probability Matrix (TPM). However to obtain the suitable TPM is hard especially in involving long-term modeling due to unavailability of data. This paper aims to enhance the classical Markov Chain by introducing Exponential Smoothing technique in developing the appropriate TPM.
Invited commentary: Lost in estimation--searching for alternatives to markov chains to fit complex Bayesian models.

PubMed

Molitor, John

2012-03-01

Bayesian methods have seen an increase in popularity in a wide variety of scientific fields, including epidemiology. One of the main reasons for their widespread application is the power of the Markov chain Monte Carlo (MCMC) techniques generally used to fit these models. As a result, researchers often implicitly associate Bayesian models with MCMC estimation procedures. However, Bayesian models do not always require Markov-chain-based methods for parameter estimation. This is important, as MCMC estimation methods, while generally quite powerful, are complex and computationally expensive and suffer from convergence problems related to the manner in which they generate correlated samples used to estimate probability distributions for parameters of interest. In this issue of the Journal, Cole et al. (Am J Epidemiol. 2012;175(5):368-375) present an interesting paper that discusses non-Markov-chain-based approaches to fitting Bayesian models. These methods, though limited, can overcome some of the problems associated with MCMC techniques and promise to provide simpler approaches to fitting Bayesian models. Applied researchers will find these estimation approaches intuitively appealing and will gain a deeper understanding of Bayesian models through their use. However, readers should be aware that other non-Markov-chain-based methods are currently in active development and have been widely published in other fields.
Antibody side chain conformations are position-dependent.

PubMed

Leem, Jinwoo; Georges, Guy; Shi, Jiye; Deane, Charlotte M

2018-04-01

Side chain prediction is an integral component of computational antibody design and structure prediction. Current antibody modelling tools use backbone-dependent rotamer libraries with conformations taken from general proteins. Here we present our antibody-specific rotamer library, where rotamers are binned according to their immunogenetics (IMGT) position, rather than their local backbone geometry. We find that for some amino acid types at certain positions, only a restricted number of side chain conformations are ever observed. Using this information, we are able to reduce the breadth of the rotamer sampling space. Based on our rotamer library, we built a side chain predictor, position-dependent antibody rotamer swapper (PEARS). On a blind test set of 95 antibody model structures, PEARS had the highest average χ 1 and χ1+2 accuracy (78.7% and 64.8%) compared to three leading backbone-dependent side chain predictors. Our use of IMGT position, rather than backbone ϕ/ψ, meant that PEARS was more robust to errors in the backbone of the model structure. PEARS also achieved the lowest number of side chain-side chain clashes. PEARS is freely available as a web application at http://opig.stats.ox.ac.uk/webapps/pears. © 2018 Wiley Periodicals, Inc.
Antiretroviral procurement and supply chain management.

PubMed

Ripin, David J; Jamieson, David; Meyers, Amy; Warty, Umesh; Dain, Mary; Khamsi, Cyril

2014-01-01

Procurement, the country-level process of ordering antiretrovirals (ARVs), and supply chain management, the mechanism by which they are delivered to health-care facilities, are critical processes required to move ARVs from manufacturers to patients. To provide a glimpse into the ARV procurement and supply chain, the following pages provide an overview of the primary stakeholders, principal operating models, and policies and regulations involved in ARV procurement. Also presented are key challenges that need to be addressed to ensure that the supply chain is not a barrier to the goal of universal coverage. This article will cover the steps necessary to order and distribute ARVs, including different models of delivery, key stakeholders involved, strategic considerations that vary depending on context and policies affecting them. The single drug examples given illustrate the complications inherent in fragmented supply and demand-driven models of procurement and supply chain management, and suggest tools for navigating these hurdles that will ultimately result in more secure and reliable ARV provision. Understanding the dynamics of ARV supply chain is important for the global health community, both to ensure full and efficient treatment of persons living with HIV as well as to inform the supply chain decisions for other public health products.

Supply chain analysis of e-tailing versus retailing operation - a case study

NASA Astrophysics Data System (ADS)

Kumar, Sameer; Tiffany, Maryellen; Vaidya, Salil

2016-07-01

The swift growth of e-commerce or e-tailing as a consumer retail channel has made it a serious competitor to traditional retail channels and is changing consumers' purchasing behaviour. The purpose of this case study, based on Target and Amazon.com, is to analyse the attributes of traditional retailing, e-tailing, and hybrid supply chain models to form conclusions about the feasibility of an idealised supply chain model for the future. An integrated and generalised modelling framework is used that incorporates Six Sigma - define, measure, analyse, improve, control methodology leveraging various tools, including process flow maps, cause and effect diagram, performance efficiency metrics, failure mode and effects analysis (FMEA), and Monte Carlo simulation. Based on this analysis and research, the conclusion is that the idealised supply chain of the future may evolve into a hybrid supply chain, which includes both e-tail and retail channels. The main recommendations from this study include assessing the risks of migrating to such a hybrid supply chain and to leverage the recommended actions provided in the hybrid FMEA. To facilitate more effective and mature processes, this study can guide researchers in exhaustive empirical evaluations of hybrid supply chains, gather experiences and lessons learned for practitioners.
Polymerization as a Model Chain Reaction

ERIC Educational Resources Information Center

Morton, Maurice

1973-01-01

Describes the features of the free radical, anionic, and cationic mechanisms of chain addition polymerization. Indicates that the nature of chain reactions can be best taught through the study of macromolecules. (CC)
A strategic decision-making model considering the social costs of carbon dioxide emissions for sustainable supply chain management.

PubMed

Tseng, Shih-Chang; Hung, Shiu-Wan

2014-01-15

Incorporating sustainability into supply chain management has become a critical issue driven by pressures from governments, customers, and various stakeholder groups over the past decade. This study proposes a strategic decision-making model considering both the operational costs and social costs caused by the carbon dioxide emissions from operating such a supply chain network for sustainable supply chain management. This model was used to evaluate carbon dioxide emissions and operational costs under different scenarios in an apparel manufacturing supply chain network. The results showed that the higher the social cost rate of carbon dioxide emissions, the lower the amount of the emission of carbon dioxide. The results also suggested that a legislation that forces the enterprises to bear the social costs of carbon dioxide emissions resulting from their economic activities is an effective approach to reducing carbon dioxide emissions. Copyright © 2013 Elsevier Ltd. All rights reserved.
Negativity as the entanglement measure to probe the Kondo regime in the spin-chain Kondo model

NASA Astrophysics Data System (ADS)

Bayat, Abolfazl; Sodano, Pasquale; Bose, Sougato

2010-02-01

We study the entanglement of an impurity at one end of a spin chain with a block of spins using negativity as a true measure of entanglement to characterize the unique features of the gapless Kondo regime in the spin-chain Kondo model. For this spin chain in the Kondo regime we determine—with a true entanglement measure—the spatial extent of the Kondo screening cloud, we propose an ansatz for its ground state and demonstrate that the impurity spin is indeed maximally entangled with the cloud. To better evidence the peculiarities of the Kondo regime, we carry a parallel analysis of the entanglement properties of the Kondo spin-chain model in the gapped dimerized regime. Our study shows how a genuine entanglement measure stemming from quantum information theory can fully characterize also nonperturbative regimes accessible to certain condensed matter systems.
A quantile-based scenario analysis approach to biomass supply chain optimization under uncertainty

DOE PAGES

Zamar, David S.; Gopaluni, Bhushan; Sokhansanj, Shahab; ...

2016-11-21

Supply chain optimization for biomass-based power plants is an important research area due to greater emphasis on renewable power energy sources. Biomass supply chain design and operational planning models are often formulated and studied using deterministic mathematical models. While these models are beneficial for making decisions, their applicability to real world problems may be limited because they do not capture all the complexities in the supply chain, including uncertainties in the parameters. This study develops a statistically robust quantile-based approach for stochastic optimization under uncertainty, which builds upon scenario analysis. We apply and evaluate the performance of our approach tomore » address the problem of analyzing competing biomass supply chains subject to stochastic demand and supply. Finally, the proposed approach was found to outperform alternative methods in terms of computational efficiency and ability to meet the stochastic problem requirements.« less
A quantile-based scenario analysis approach to biomass supply chain optimization under uncertainty

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zamar, David S.; Gopaluni, Bhushan; Sokhansanj, Shahab

Supply chain optimization for biomass-based power plants is an important research area due to greater emphasis on renewable power energy sources. Biomass supply chain design and operational planning models are often formulated and studied using deterministic mathematical models. While these models are beneficial for making decisions, their applicability to real world problems may be limited because they do not capture all the complexities in the supply chain, including uncertainties in the parameters. This study develops a statistically robust quantile-based approach for stochastic optimization under uncertainty, which builds upon scenario analysis. We apply and evaluate the performance of our approach tomore » address the problem of analyzing competing biomass supply chains subject to stochastic demand and supply. Finally, the proposed approach was found to outperform alternative methods in terms of computational efficiency and ability to meet the stochastic problem requirements.« less
A stochastic inventory management model for a dual sourcing supply chain with disruptions

NASA Astrophysics Data System (ADS)

Iakovou, Eleftherios; Vlachos, Dimitrios; Xanthopoulos, Anastasios

2010-03-01

As companies continue to globalise their operations and outsource significant portion of their value chain activities, they often end up relying heavily on order replenishments from distant suppliers. The explosion in long-distance sourcing is exposing supply chains and shareholder value at ever increasing operational and disruption risks. It is well established, both in academia and in real-world business environments, that resource flexibility is an effective method for hedging against supply chain disruption risks. In this contextual framework, we propose a single period stochastic inventory decision-making model that could be employed for capturing the trade-off between inventory policies and disruption risks for an unreliable dual sourcing supply network for both the capacitated and uncapacitated cases. Through the developed model, we obtain some important managerial insights and evaluate the merit of contingency strategies in managing uncertain supply chains.
A simplified parsimonious higher order multivariate Markov chain model

NASA Astrophysics Data System (ADS)

Wang, Chao; Yang, Chuan-sheng

2017-09-01

In this paper, a simplified parsimonious higher-order multivariate Markov chain model (SPHOMMCM) is presented. Moreover, parameter estimation method of TPHOMMCM is give. Numerical experiments shows the effectiveness of TPHOMMCM.
An ellipsoid-chain model for conjugated polymer solutions

NASA Astrophysics Data System (ADS)

Lee, Cheng K.; Hua, Chi C.; Chen, Show A.

2012-02-01

We propose an ellipsoid-chain model which may be routinely parameterized to capture large-scale properties of semiflexible, amphiphilic conjugated polymers in various solvent media. The model naturally utilizes the defect locations as pivotal centers connecting adjacent ellipsoids (each currently representing ten monomer units), and a variant umbrella-sampling scheme is employed to construct the potentials of mean force (PMF) for specific solvent media using atomistic dynamics data and simplex optimization. The performances, both efficacy and efficiency, of the model are thoroughly evaluated by comparing the simulation results on long, single-chain (i.e., 300-mer) structures with those from two existing, finer-grained models for a standard conjugated polymer (i.e., poly(2-methoxy-5-(2'-ethylhexyloxy)-1,4-phenylenevinylene) or MEH-PPV) in two distinct solvents (i.e., chloroform or toluene) as well as a hybrid, binary-solvent medium (i.e., chloroform/toluene = 1:1 in number density). The coarse-grained Monte Carlo (CGMC) simulation of the ellipsoid-chain model is shown to be the most efficient—about 300 times faster than the coarse-grained molecular dynamics (CGMD) simulation of the finest CG model that employs explicit solvents—in capturing elementary single-chain structures for both single-solvent media, and is a few times faster than the coarse-grained Langevin dynamics (CGLD) simulation of another implicit-solvent polymer model with a slightly greater coarse-graining level than in the CGMD simulation. For the binary-solvent system considered, however, both of the two implicit-solvent schemes (i.e., CGMC and CGLD) fail to capture the effects of conspicuous concentration fluctuations near the polymer-solvent interface, arising from a pronounced coupling between the solvent molecules and different parts of the polymer. Essential physical implications are elaborated on the success as well as the failure of the two implicit-solvent CG schemes under varying solvent conditions. Within the ellipsoid-chain model, the impact of synthesized defects on local segmental ordering as well as bulk chain conformation is also scrutinized, and essential consequences in practical applications discussed. In future perspectives, we remark on strategy that takes advantage of the coordination among various CG models and simulation schemes to warrant computational efficiency and accuracy, with the anticipated capability of simulating larger-scale, many-chain aggregate systems.
Accessing the dynamics of end-grafted flexible polymer chains by atomic force-electrochemical microscopy. Theoretical modeling of the approach curves by the elastic bounded diffusion model and Monte Carlo simulations. Evidence for compression-induced lateral chain escape.

PubMed

Abbou, Jeremy; Anne, Agnès; Demaille, Christophe

2006-11-16

The dynamics of a molecular layer of linear poly(ethylene glycol) (PEG) chains of molecular weight 3400, bearing at one end a ferrocene (Fc) label and thiol end-grafted at a low surface coverage onto a gold substrate, is probed using combined atomic force-electrochemical microscopy (AFM-SECM), at the scale of approximately 100 molecules. Force and current approach curves are simultaneously recorded as a force-sensing microelectrode (tip) is inserted within the approximately 10 nm thick, redox labeled, PEG chain layer. Whereas the force approach curve gives access to the structure of the compressed PEG layer, the tip-current, resulting from tip-to-substrate redox cycling of the Fc head of the chain, is controlled by chain dynamics. The elastic bounded diffusion model, which considers the motion of the Fc head as diffusion in a conformational field, complemented by Monte Carlo (MC) simulations, from which the chain conformation can be derived for any degree of confinement, allows the theoretical tip-current approach curve to be calculated. The experimental current approach curve can then be very satisfyingly reproduced by theory, down to a tip-substrate separation of approximately 2 nm, using only one adjustable parameter characterizing the chain dynamics: the effective diffusion coefficient of the chain head. At closer tip-substrate separations, an unpredicted peak is observed in the experimental current approach curve, which is shown to find its origin in a compression-induced escape of the chain from within the narrowing tip-substrate gap. MC simulations provide quantitative support for lateral chain elongation as the escape mechanism.
Protein side chain conformation predictions with an MMGBSA energy function.

PubMed

Gaillard, Thomas; Panel, Nicolas; Simonson, Thomas

2016-06-01

The prediction of protein side chain conformations from backbone coordinates is an important task in structural biology, with applications in structure prediction and protein design. It is a difficult problem due to its combinatorial nature. We study the performance of an "MMGBSA" energy function, implemented in our protein design program Proteus, which combines molecular mechanics terms, a Generalized Born and Surface Area (GBSA) solvent model, with approximations that make the model pairwise additive. Proteus is not a competitor to specialized side chain prediction programs due to its cost, but it allows protein design applications, where side chain prediction is an important step and MMGBSA an effective energy model. We predict the side chain conformations for 18 proteins. The side chains are first predicted individually, with the rest of the protein in its crystallographic conformation. Next, all side chains are predicted together. The contributions of individual energy terms are evaluated and various parameterizations are compared. We find that the GB and SA terms, with an appropriate choice of the dielectric constant and surface energy coefficients, are beneficial for single side chain predictions. For the prediction of all side chains, however, errors due to the pairwise additive approximation overcome the improvement brought by these terms. We also show the crucial contribution of side chain minimization to alleviate the rigid rotamer approximation. Even without GB and SA terms, we obtain accuracies comparable to SCWRL4, a specialized side chain prediction program. In particular, we obtain a better RMSD than SCWRL4 for core residues (at a higher cost), despite our simpler rotamer library. Proteins 2016; 84:803-819. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.
Characterization of Hydrophobic Interactions of Polymers with Water and Phospholipid Membranes Using Molecular Dynamics Simulations

NASA Astrophysics Data System (ADS)

Drenscko, Mihaela

Polymers and lipid membranes are both essential soft materials. The structure and hydrophobicity/hydrophilicity of polymers, as well as the solvent they are embedded in, ultimately determines their size and shape. Understating the variation of shape of the polymer as well as its interactions with model biological membranes can assist in understanding the biocompatibility of the polymer itself. Computer simulations, in particular molecular dynamics, can aid in characterization of the interaction of polymers with solvent, as well as polymers with model membranes. In this thesis, molecular dynamics serve to describe polymer interactions with a solvent (water) and with a lipid membrane. To begin with, we characterize the hydrophobic collapse of single polystyrene chains in water using molecular dynamics simulations. Specifically, we calculate the potential of mean force for the collapse of a single polystyrene chain in water using metadynamics, comparing the results between all atomistic with coarse-grained molecular simulation. We next explore the scaling behavior of the collapsed globular shape at the minimum energy configuration, characterized by the radius of gyration, as a function of chain length. The exponent is close to one third, consistent with that predicted for a polymer chain in bad solvent. We also explore the scaling behavior of the Solvent Accessible Surface Area (SASA) as a function of chain length, finding a similar exponent for both all-atomistic and coarse-grained simulations. Furthermore, calculation of the local water density as a function of chain length near the minimum energy configuration suggests that intermediate chain lengths are more likely to form dewetted states, as compared to shorter or longer chain lengths. Next, in order to investigate the molecular interactions between single hydrophobic polymer chains and lipids in biological membranes and at lipid membrane/solvent interface, we perform a series of molecular dynamics simulations of small membranes using all atomistic and coarse-grained methods. The molecular interaction between common polymer chains used in biomedical applications and the cell membrane is unknown. This interaction may affect the biocompatibility of the polymer chains. Molecular dynamics simulations offer an emerging tool to characterize the interaction between common degradable polymer chains used in biomedical applications, such as polycaprolactone, and model cell membranes. We systematically characterize with long-time all-atomistic molecular dynamics simulations the interaction between single polycaprolactone chains of varying chain lengths with a model phospholipid membrane. We find that the length of polymer chain greatly affects the nature of interaction with the membrane, as well as the membrane properties. Furthermore, we next utilize advanced sampling techniques in molecular dynamics to characterize the two-dimensional free energy surface for the interaction of varying polymer chain lengths (short, intermediate, and long) with model cell membranes. We find that the free energy minimum shifts from the membrane-water interface to the hydrophobic core of the phospholipid membrane as a function of chain length. These results can be used to design polymer chain lengths and chemistries to optimize their interaction with cell membranes at the molecular level.
A Chain-Retrieval Model for Voluntary Task Switching

ERIC Educational Resources Information Center

Vandierendonck, Andre; Demanet, Jelle; Liefooghe, Baptist; Verbruggen, Frederick

2012-01-01

To account for the findings obtained in voluntary task switching, this article describes and tests the chain-retrieval model. This model postulates that voluntary task selection involves retrieval of task information from long-term memory, which is then used to guide task selection and task execution. The model assumes that the retrieved…
Building Higher-Order Markov Chain Models with EXCEL

ERIC Educational Resources Information Center

Ching, Wai-Ki; Fung, Eric S.; Ng, Michael K.

2004-01-01

Categorical data sequences occur in many applications such as forecasting, data mining and bioinformatics. In this note, we present higher-order Markov chain models for modelling categorical data sequences with an efficient algorithm for solving the model parameters. The algorithm can be implemented easily in a Microsoft EXCEL worksheet. We give a…
Exact solution of the relativistic quantum Toda chain

NASA Astrophysics Data System (ADS)

Zhang, Xin; Cao, Junpeng; Yang, Wen-Li; Shi, Kangjie; Wang, Yupeng

2017-03-01

The relativistic quantum Toda chain model is studied with the generalized algebraic Bethe Ansatz method. By employing a set of local gauge transformations, proper local vacuum states can be obtained for this model. The exact spectrum and eigenstates of the model are thus constructed simultaneously.
All-atom ensemble modeling to analyze small angle X-ray scattering of glycosylated proteins

PubMed Central

Guttman, Miklos; Weinkam, Patrick; Sali, Andrej; Lee, Kelly K.

2013-01-01

Summary The flexible and heterogeneous nature of carbohydrate chains often renders glycoproteins refractory to traditional structure determination methods. Small Angle X-ray scattering (SAXS) can be a useful tool for obtaining structural information of these systems. All-atom modeling of glycoproteins with flexible glycan chains was applied to interpret the solution SAXS data for a set of glycoproteins. For simpler systems (single glycan, with a well defined protein structure), all-atom modeling generates models in excellent agreement with the scattering pattern, and reveals the approximate spatial occupancy of the glycan chain in solution. For more complex systems (several glycan chains, or unknown protein substructure), the approach can still provide insightful models, though the orientations of glycans become poorly determined. Ab initio shape reconstructions appear to capture the global morphology of glycoproteins, but in most cases offer little information about glycan spatial occupancy. The all-atom modeling methodology is available as a webserver at http://modbase.compbio.ucsf.edu/allosmod-foxs. PMID:23473666
Cloud Computing Value Chains: Understanding Businesses and Value Creation in the Cloud

NASA Astrophysics Data System (ADS)

Mohammed, Ashraf Bany; Altmann, Jörn; Hwang, Junseok

Based on the promising developments in Cloud Computing technologies in recent years, commercial computing resource services (e.g. Amazon EC2) or software-as-a-service offerings (e.g. Salesforce. com) came into existence. However, the relatively weak business exploitation, participation, and adoption of other Cloud Computing services remain the main challenges. The vague value structures seem to be hindering business adoption and the creation of sustainable business models around its technology. Using an extensive analyze of existing Cloud business models, Cloud services, stakeholder relations, market configurations and value structures, this Chapter develops a reference model for value chains in the Cloud. Although this model is theoretically based on porter's value chain theory, the proposed Cloud value chain model is upgraded to fit the diversity of business service scenarios in the Cloud computing markets. Using this model, different service scenarios are explained. Our findings suggest new services, business opportunities, and policy practices for realizing more adoption and value creation paths in the Cloud.
A tridiagonal parsimonious higher order multivariate Markov chain model

NASA Astrophysics Data System (ADS)

Wang, Chao; Yang, Chuan-sheng

2017-09-01

In this paper, we present a tridiagonal parsimonious higher-order multivariate Markov chain model (TPHOMMCM). Moreover, estimation method of the parameters in TPHOMMCM is give. Numerical experiments illustrate the effectiveness of TPHOMMCM.
Characterizing Oregon's supply chains.

DOT National Transportation Integrated Search

2013-03-01

In many regions throughout the world, freight models are used to aid infrastructure investment and : policy decisions. Since freight is such an integral part of efficient supply chains, more realistic : transportation models can be of greater assista...
A decision model for cost effective design of biomass based green energy supply chains.

PubMed

Yılmaz Balaman, Şebnem; Selim, Hasan

2015-09-01

The core driver of this study is to deal with the design of anaerobic digestion based biomass to energy supply chains in a cost effective manner. In this concern, a decision model is developed. The model is based on fuzzy multi objective decision making in order to simultaneously optimize multiple economic objectives and tackle the inherent uncertainties in the parameters and decision makers' aspiration levels for the goals. The viability of the decision model is explored with computational experiments on a real-world biomass to energy supply chain and further analyses are performed to observe the effects of different conditions. To this aim, scenario analyses are conducted to investigate the effects of energy crop utilization and operational costs on supply chain structure and performance measures. Copyright © 2015 Elsevier Ltd. All rights reserved.

Modeling qRT-PCR dynamics with application to cancer biomarker quantification.

PubMed

Chervoneva, Inna; Freydin, Boris; Hyslop, Terry; Waldman, Scott A

2017-01-01

Quantitative reverse transcription polymerase chain reaction (qRT-PCR) is widely used for molecular diagnostics and evaluating prognosis in cancer. The utility of mRNA expression biomarkers relies heavily on the accuracy and precision of quantification, which is still challenging for low abundance transcripts. The critical step for quantification is accurate estimation of efficiency needed for computing a relative qRT-PCR expression. We propose a new approach to estimating qRT-PCR efficiency based on modeling dynamics of polymerase chain reaction amplification. In contrast, only models for fluorescence intensity as a function of polymerase chain reaction cycle have been used so far for quantification. The dynamics of qRT-PCR efficiency is modeled using an ordinary differential equation model, and the fitted ordinary differential equation model is used to obtain effective polymerase chain reaction efficiency estimates needed for efficiency-adjusted quantification. The proposed new qRT-PCR efficiency estimates were used to quantify GUCY2C (Guanylate Cyclase 2C) mRNA expression in the blood of colorectal cancer patients. Time to recurrence and GUCY2C expression ratios were analyzed in a joint model for survival and longitudinal outcomes. The joint model with GUCY2C quantified using the proposed polymerase chain reaction efficiency estimates provided clinically meaningful results for association between time to recurrence and longitudinal trends in GUCY2C expression.
A Coarse Grained Model for Methylcellulose: Spontaneous Ring Formation at Elevated Temperature

NASA Astrophysics Data System (ADS)

Huang, Wenjun; Larson, Ronald

Methylcellulose (MC) is widely used as food additives and pharma applications, where its thermo-reversible gelation behavior plays an important role. To date the gelation mechanism is not well understood, and therefore attracts great research interest. In this study, we adopted coarse-grained (CG) molecular dynamics simulations to model the MC chains, including the homopolymers and random copolymers that models commercial METHOCEL A, in an implicit water environment, where each MC monomer modeled with a single bead. The simulations are carried using a LAMMPS program. We parameterized our CG model using the radial distribution functions from atomistic simulations of short MC oligomers, extrapolating the results to long chains. We used dissociation free energy to validate our CG model against the atomistic model. The CG model captured the effects of monomer substitution type and temperature from the atomistic simulations. We applied this CG model to simulate single chains up to 1000 monomers long and obtained persistence lengths that are close to those determined from experiment. We observed the chain collapse transition for random copolymer at 600 monomers long at 50C. The chain collapsed into a stable ring structure with outer diameter around 14nm, which appears to be a precursor to the fibril structure observed in the methylcellulose gel observed by Lodge et al. in the recent studies. Our CG model can be extended to other MC derivatives for studying the interaction between these polymers and small molecules, such as hydrophobic drugs.
Research of Trust Chain of Operating System

NASA Astrophysics Data System (ADS)

Li, Hongjiao; Tian, Xiuxia

Trust chain is one of the key technologies in designing secure operating system based on TC technology. Constructions of trust chain and trust models are analyzed. Future works in these directions are discussed.
Joint modelling rationale for chained equations

PubMed Central

2014-01-01

Background Chained equations imputation is widely used in medical research. It uses a set of conditional models, so is more flexible than joint modelling imputation for the imputation of different types of variables (e.g. binary, ordinal or unordered categorical). However, chained equations imputation does not correspond to drawing from a joint distribution when the conditional models are incompatible. Concurrently with our work, other authors have shown the equivalence of the two imputation methods in finite samples. Methods Taking a different approach, we prove, in finite samples, sufficient conditions for chained equations and joint modelling to yield imputations from the same predictive distribution. Further, we apply this proof in four specific cases and conduct a simulation study which explores the consequences when the conditional models are compatible but the conditions otherwise are not satisfied. Results We provide an additional “non-informative margins” condition which, together with compatibility, is sufficient. We show that the non-informative margins condition is not satisfied, despite compatible conditional models, in a situation as simple as two continuous variables and one binary variable. Our simulation study demonstrates that as a consequence of this violation order effects can occur; that is, systematic differences depending upon the ordering of the variables in the chained equations algorithm. However, the order effects appear to be small, especially when associations between variables are weak. Conclusions Since chained equations is typically used in medical research for datasets with different types of variables, researchers must be aware that order effects are likely to be ubiquitous, but our results suggest they may be small enough to be negligible. PMID:24559129
Decentralized supply chain network design: monopoly, duopoly and oligopoly competitions under uncertainty

NASA Astrophysics Data System (ADS)

Seyedhosseini, Seyed Mohammad; Fahimi, Kaveh; Makui, Ahmad

2017-12-01

This paper presents the competitive supply chain network design problem in which n decentralized supply chains simultaneously enter the market with no existing rival chain, shape their networks and set wholesale and retail prices in competitive mode. The customer demand is elastic and price dependent, customer utility function is based on the Hoteling model and the chains produce identical or highly substitutable products. We construct a solution algorithm based on bi-level programming and possibility theory. In the proposed bi-level model, the inner part sets the prices based on simultaneous extra- and Stackleberg intra- chains competitions, and the outer part shapes the networks in cooperative competitions. Finally, we use a real-word study to discuss the effect of the different structures of the competitors on the equilibrium solution. Moreover, sensitivity analyses are conducted and managerial insights are offered.
Conditional Solvation Thermodynamics of Isoleucine in Model Peptides and the Limitations of the Group-Transfer Model

PubMed Central

2015-01-01

The hydration thermodynamics of the amino acid X relative to the reference G (glycine) or the hydration thermodynamics of a small-molecule analog of the side chain of X is often used to model the contribution of X to protein stability and solution thermodynamics. We consider the reasons for successes and limitations of this approach by calculating and comparing the conditional excess free energy, enthalpy, and entropy of hydration of the isoleucine side chain in zwitterionic isoleucine, in extended penta-peptides, and in helical deca-peptides. Butane in gauche conformation serves as a small-molecule analog for the isoleucine side chain. Parsing the hydrophobic and hydrophilic contributions to hydration for the side chain shows that both of these aspects of hydration are context-sensitive. Furthermore, analyzing the solute–solvent interaction contribution to the conditional excess enthalpy of the side chain shows that what is nominally considered a property of the side chain includes entirely nonobvious contributions of the background. The context-sensitivity of hydrophobic and hydrophilic hydration and the conflation of background contributions with energetics attributed to the side chain limit the ability of a single scaling factor, such as the fractional solvent exposure of the group in the protein, to map the component energetic contributions of the model-compound data to their value in the protein. But ignoring the origin of cancellations in the underlying components the group-transfer model may appear to provide a reasonable estimate of the free energy for a given error tolerance. PMID:24650057
Application of a transmission model to estimate performance objectives for Salmonella in the broiler supply chain.

PubMed

van der Fels-Klerx, H J; Tromp, S; Rijgersberg, H; van Asselt, E D

2008-11-30

The aim of the present study was to demonstrate how Performance Objectives (POs) for Salmonella at various points in the broiler supply chain can be estimated, starting from pre-set levels of the PO in finished products. The estimations were performed using an analytical transmission model, based on prevalence data collected throughout the chain in The Netherlands. In the baseline (current) situation, the end PO was set at 2.5% of the finished products (at end of processing) being contaminated with Salmonella. Scenario analyses were performed by reducing this baseline end PO to 1.5% and 0.5%. The results showed the end PO could be reduced by spreading the POs over the various stages of the broiler supply chain. Sensitivity analyses were performed by changing the values of the model parameters. Results indicated that, in general, decreasing Salmonella contamination between points in the chain is more effective in reducing the baseline PO than increasing the reduction of the pathogen, implying contamination should be prevented rather than treated. Application of both approaches at the same time showed to be most effective in reducing the end PO, especially at the abattoir and during processing. The modelling approach of this study proved to be useful to estimate the implications for preceding stages of the chain by setting a PO at the end of the chain as well as to evaluate the effectiveness of potential interventions in reducing the end PO. The model estimations may support policy-makers in their decision-making process with regard to microbiological food safety.
Future Supply Chains Enabled by Continuous Processing-Opportunities Challenges May 20-21 2014 Continuous Manufacturing Symposium.

PubMed

Srai, Jagjit Singh; Badman, Clive; Krumme, Markus; Futran, Mauricio; Johnston, Craig

2015-03-01

This paper examines the opportunities and challenges facing the pharmaceutical industry in moving to a primarily "continuous processing"-based supply chain. The current predominantly "large batch" and centralized manufacturing system designed for the "blockbuster" drug has driven a slow-paced, inventory heavy operating model that is increasingly regarded as inflexible and unsustainable. Indeed, new markets and the rapidly evolving technology landscape will drive more product variety, shorter product life-cycles, and smaller drug volumes, which will exacerbate an already unsustainable economic model. Future supply chains will be required to enhance affordability and availability for patients and healthcare providers alike despite the increased product complexity. In this more challenging supply scenario, we examine the potential for a more pull driven, near real-time demand-based supply chain, utilizing continuous processing where appropriate as a key element of a more "flow-through" operating model. In this discussion paper on future supply chain models underpinned by developments in the continuous manufacture of pharmaceuticals, we have set out; The paper recognizes that although current batch operational performance in pharma is far from optimal and not necessarily an appropriate end-state benchmark for batch technology, the adoption of continuous supply chain operating models underpinned by continuous production processing, as full or hybrid solutions in selected product supply chains, can support industry transformations to deliver right-first-time quality at substantially lower inventory profiles. © 2015 The Authors. Journal of Pharmaceutical Sciences published by Wiley Periodicals, Inc. and the American Pharmacists Association. © 2014 Wiley Periodicals, Inc. and the American Pharmacists Association.
DOE Office of Scientific and Technical Information (OSTI.GOV)

Nekrasov, Nikita; ITEP, Moscow; Shatashvili, Samson

Supersymmetric vacua of two dimensional N = 4 gauge theories with matter, softly broken by the twisted masses down to N = 2, are shown to be in one-to-one correspondence with the eigenstates of integrable spin chain Hamiltonians. Examples include: the Heisenberg SU(2)XXX spin chain which is mapped to the two dimensional U(N) theory with fundamental hypermultiplets, the XXZ spin chain which is mapped to the analogous three dimensional super-Yang-Mills theory compactified on a circle, the XYZ spin chain and eight-vertex model which are related to the four dimensional theory compactified on T{sup 2}. A consequence of our correspondence ismore » the isomorphism of the quantum cohomology ring of various quiver varieties, such as cotangent bundles to (partial) flag varieties and the ring of quantum integrals of motion of various spin chains. The correspondence extends to any spin group, representations, boundary conditions, and inhomogeneity, it includes Sinh-Gordon and non-linear Schroedinger models as well as the dynamical spin chains like Hubbard model. Compactifications of four dimensional N = 2 theories on a two-sphere lead to the instanton-corrected Bethe equations.« less
The Determination of Production and Distribution Policy in Push-Pull Production Chain with Supply Hub as the Junction Point

NASA Astrophysics Data System (ADS)

Sinaga, A. T.; Wangsaputra, R.

2018-03-01

The development of technology causes the needs of products and services become increasingly complex, diverse, and fluctuating. This causes the level of inter-company dependencies within a production chains increased. To be able to compete, efficiency improvements need to be done collaboratively in the production chain network. One of the efforts to increase efficiency is to harmonize production and distribution activities in the production chain network. This paper describes the harmonization of production and distribution activities by applying the use of push-pull system and supply hub in the production chain between two companies. The research methodology begins with conducting empirical and literature studies, formulating research questions, developing mathematical models, conducting trials and analyses, and taking conclusions. The relationship between the two companies is described in the MINLP mathematical model with the total cost of production chain as the objective function. Decisions generated by the mathematical models are the size of production lot, size of delivery lot, number of kanban, frequency of delivery, and the number of understock and overstock lot.
Bayesian analysis of non-homogeneous Markov chains: application to mental health data.

PubMed

Sung, Minje; Soyer, Refik; Nhan, Nguyen

2007-07-10

In this paper we present a formal treatment of non-homogeneous Markov chains by introducing a hierarchical Bayesian framework. Our work is motivated by the analysis of correlated categorical data which arise in assessment of psychiatric treatment programs. In our development, we introduce a Markovian structure to describe the non-homogeneity of transition patterns. In doing so, we introduce a logistic regression set-up for Markov chains and incorporate covariates in our model. We present a Bayesian model using Markov chain Monte Carlo methods and develop inference procedures to address issues encountered in the analyses of data from psychiatric treatment programs. Our model and inference procedures are implemented to some real data from a psychiatric treatment study. Copyright 2006 John Wiley & Sons, Ltd.
Entanglement Theories: Packing vs. Percolation

NASA Astrophysics Data System (ADS)

Wool, Richard

2007-03-01

There are two emergent theories of polymer entanglements, the Packing Model (Fetters, Lohse, Graessley, Milner, Whitten, ˜'98) and the Percolation Model (Wool ˜'93). The Packing model suggests that the entanglement molecular weight Me is determined by Me = K p^3, where the packing length parameter p = V/R^2 in which V is the volume of the chain (V=M/ρNa), R is the end-to end vector of the chain, and K 357 ρNa, is an empirical constant. The Percolation model states that an entanglement network develops when the number of chains per unit area σ, intersecting any load bearing plane, is equal to 3 times the number of chain segments (1/a cross-section), such that when 3aσ =1 at the percolation threshold, Me 31 MjC∞, in which Mj is the step molecular weight and C∞ is the characteristic ratio. There are no fitting parameters in the Percolation model. The Packing model predicts that Me decreases rapidly with chain stiffness, as Me˜1/C∞^3, while the Percolation model predicts that Me increases with C∞, as Me˜C∞. The Percolation model was found to be the correct model based on computer simulations (M. Bulacu et al) and a re-analysis of the Packing model experimental data. The Packing model can be derived from the Percolation model, but not visa versa, and reveals a surprising accidental relation between C∞ and Mj in the front factor K. This result significantly impacts the interpretation of the dynamics of rheology and fracture of entangled polymers.
Room temperature ionic liquids: A simple model. Effect of chain length and size of intermolecular potential on critical temperature.

PubMed

Chapela, Gustavo A; Guzmán, Orlando; Díaz-Herrera, Enrique; del Río, Fernando

2015-04-21

A model of a room temperature ionic liquid can be represented as an ion attached to an aliphatic chain mixed with a counter ion. The simple model used in this work is based on a short rigid tangent square well chain with an ion, represented by a hard sphere interacting with a Yukawa potential at the head of the chain, mixed with a counter ion represented as well by a hard sphere interacting with a Yukawa potential of the opposite sign. The length of the chain and the depth of the intermolecular forces are investigated in order to understand which of these factors are responsible for the lowering of the critical temperature. It is the large difference between the ionic and the dispersion potentials which explains this lowering of the critical temperature. Calculation of liquid-vapor equilibrium orthobaric curves is used to estimate the critical points of the model. Vapor pressures are used to obtain an estimate of the triple point of the different models in order to calculate the span of temperatures where they remain a liquid. Surface tensions and interfacial thicknesses are also reported.
Markov chain model for demersal fish catch analysis in Indonesia

NASA Astrophysics Data System (ADS)

Firdaniza; Gusriani, N.

2018-03-01

As an archipelagic country, Indonesia has considerable potential fishery resources. One of the fish resources that has high economic value is demersal fish. Demersal fish is a fish with a habitat in the muddy seabed. Demersal fish scattered throughout the Indonesian seas. Demersal fish production in each Indonesia’s Fisheries Management Area (FMA) varies each year. In this paper we have discussed the Markov chain model for demersal fish yield analysis throughout all Indonesia’s Fisheries Management Area. Data of demersal fish catch in every FMA in 2005-2014 was obtained from Directorate of Capture Fisheries. From this data a transition probability matrix is determined by the number of transitions from the catch that lie below the median or above the median. The Markov chain model of demersal fish catch data was an ergodic Markov chain model, so that the limiting probability of the Markov chain model can be determined. The predictive value of demersal fishing yields was obtained by calculating the combination of limiting probability with average catch results below the median and above the median. The results showed that for 2018 and long-term demersal fishing results in most of FMA were below the median value.
Development of coordination system model on single-supplier multi-buyer for multi-item supply chain with probabilistic demand

NASA Astrophysics Data System (ADS)

Olivia, G.; Santoso, A.; Prayogo, D. N.

2017-11-01

Nowadays, the level of competition between supply chains is getting tighter and a good coordination system between supply chains members is very crucial in solving the issue. This paper focused on a model development of coordination system between single supplier and buyers in a supply chain as a solution. Proposed optimization model was designed to determine the optimal number of deliveries from a supplier to buyers in order to minimize the total cost over a planning horizon. Components of the total supply chain cost consist of transportation costs, handling costs of supplier and buyers and also stock out costs. In the proposed optimization model, the supplier can supply various types of items to retailers whose item demand patterns are probabilistic. Sensitivity analysis of the proposed model was conducted to test the effect of changes in transport costs, handling costs and production capacities of the supplier. The results of the sensitivity analysis showed a significant influence on the changes in the transportation cost, handling costs and production capacity to the decisions of the optimal numbers of product delivery for each item to the buyers.
Critical role of FcR gamma-chain, LAT, PLCgamma2 and thrombin in arteriolar thrombus formation upon mild, laser-induced endothelial injury in vivo.

PubMed

Kalia, Neena; Auger, Jocelyn M; Atkinson, Ben; Watson, Steve P

2008-05-01

The role of collagen receptor complex GPVI-FcR gamma-chain, PLCgamma2 and LAT in laser-induced thrombosis is unclear. Controversy surrounds whether collagen is exposed in this model or whether thrombosis is dependent on thrombin. This study hypothesized that collagen exposure plays a critical role in thrombus formation in this model, which was tested by investigating contributions of FcR gamma-chain, LAT, PLCgamma2 and thrombin. Thrombi were monitored using intravital microscopy in anesthetized wild-type and FcR gamma-chain, LAT and PLCgamma2 knockout mice. Hirudin (thrombin inhibitor) was administered to wild-type and FcR gamma-chain knockout mice. Significantly reduced thrombus formation was observed in FcR gamma-chain and PLCgamma2 knockouts with a greater decrease observed in LAT knockouts. Dramatic reduction was observed in wild-types treated with hirudin, with abolished thrombus formation only observed in FcR gamma-chain knockouts treated with hirudin. GPVI-FcR gamma-chain, LAT and PLCgamma2 are essential for thrombus generation and stability in this laser-induced model of injury. More importantly, a greater role for LAT was identified, which may reflect a role for it downstream of a second matrix protein receptor. However, inhibition of platelet activation by matrix proteins and thrombin generation are both required to maximally prevent thrombus formation.
Evaluating approaches to find exon chains based on long reads.

PubMed

Kuosmanen, Anna; Norri, Tuukka; Mäkinen, Veli

2018-05-01

Transcript prediction can be modeled as a graph problem where exons are modeled as nodes and reads spanning two or more exons are modeled as exon chains. Pacific Biosciences third-generation sequencing technology produces significantly longer reads than earlier second-generation sequencing technologies, which gives valuable information about longer exon chains in a graph. However, with the high error rates of third-generation sequencing, aligning long reads correctly around the splice sites is a challenging task. Incorrect alignments lead to spurious nodes and arcs in the graph, which in turn lead to incorrect transcript predictions. We survey several approaches to find the exon chains corresponding to long reads in a splicing graph, and experimentally study the performance of these methods using simulated data to allow for sensitivity/precision analysis. Our experiments show that short reads from second-generation sequencing can be used to significantly improve exon chain correctness either by error-correcting the long reads before splicing graph creation, or by using them to create a splicing graph on which the long-read alignments are then projected. We also study the memory and time consumption of various modules, and show that accurate exon chains lead to significantly increased transcript prediction accuracy. The simulated data and in-house scripts used for this article are available at http://www.cs.helsinki.fi/group/gsa/exon-chains/exon-chains-bib.tar.bz2.
Dissolution of covalent adaptable network polymers in organic solvent

NASA Astrophysics Data System (ADS)

Yu, Kai; Yang, Hua; Dao, Binh H.; Shi, Qian; Yakacki, Christopher M.

2017-12-01

It was recently reported that thermosetting polymers can be fully dissolved in a proper organic solvent utilizing a bond-exchange reaction (BER), where small molecules diffuse into the polymer, break the long polymer chains into short segments, and eventually dissolve the network when sufficient solvent is provided. The solvent-assisted dissolution approach was applied to fully recycle thermosets and their fiber composites. This paper presents the first multi-scale modeling framework to predict the dissolution kinetics and mechanics of thermosets in organic solvent. The model connects the micro-scale network dynamics with macro-scale material properties: in the micro-scale, a model is developed based on the kinetics of BERs to describe the cleavage rate of polymer chains and evolution of chain segment length during the dissolution. The micro-scale model is then fed into a continuum-level model with considerations of the transportation of solvent molecules and chain segments in the system. The model shows good prediction on conversion rate of functional groups, degradation of network mechanical properties, and dissolution rate of thermosets during the dissolution. It identifies the underlying kinetic factors governing the dissolution process, and reveals the influence of different material and processing variables on the dissolution process, such as time, temperature, catalyst concentration, and chain length between cross-links.
Source term evaluation model for high-level radioactive waste repository with decay chain build-up.

PubMed

Chopra, Manish; Sunny, Faby; Oza, R B

2016-09-18

A source term model based on two-component leach flux concept is developed for a high-level radioactive waste repository. The long-lived radionuclides associated with high-level waste may give rise to the build-up of activity because of radioactive decay chains. The ingrowths of progeny are incorporated in the model using Bateman decay chain build-up equations. The model is applied to different radionuclides present in the high-level radioactive waste, which form a part of decay chains (4n to 4n + 3 series), and the activity of the parent and daughter radionuclides leaching out of the waste matrix is estimated. Two cases are considered: one when only parent is present initially in the waste and another where daughters are also initially present in the waste matrix. The incorporation of in situ production of daughter radionuclides in the source is important to carry out realistic estimates. It is shown that the inclusion of decay chain build-up is essential to avoid underestimation of the radiological impact assessment of the repository. The model can be a useful tool for evaluating the source term of the radionuclide transport models used for the radiological impact assessment of high-level radioactive waste repositories.
Materials Flow through Industry Supply Chain Modeling Tool | Advanced

Science.gov Websites

efficiency. It also performs supply chain scale analyses to quantify the impacts and benefits of next , read Evaluating opportunities to improve material and energy impacts in commodity supply chains

Application of a food chain model to polychlorinated biphenyl contamination of the lobster and winter flounder food chains in New Bedford Harbor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Connolly, J.P.

As part of a Remedial Investigation/Feasibility Study for the New Bedford Harbor Superfund site a model of polychlorinated biphenyls (PCBs) in the lobster and winter flounder food chains was developed. This model successfully reproduces tri-, tetra-, penta-, and hexachlorobiphenyl concentrations observed at all levels of the food chain and across the 2 order of magnitude concentration gradient in the system. The model indicated that PCB concentrations in the flounder and, to a lesser extent, in the lobster are derived from the sediment. Dietary uptake exceeds uptake across the gill for all four homologues and becomes the dominant route at themore » higher chlorinated homologues. The assimilation efficiency of ingested PCB apparently declines from relatively high values for tri-chlorobiphenyl to relatively low values for hexachlorobiphenyl. Differences in observed lobster and flounder PCB concentrations appear to be due to differences in the importance of the benthic component of the food chains of these animals and differences in whole body lipid content.« less
3D finite element modelling of force transmission and particle fracture of sand

DOE Office of Scientific and Technical Information (OSTI.GOV)

Imseeh, Wadi H.; Alshibli, Khalid A.

Global compressive loading of granular media causes rearrangements of particles into a denser configuration. Under 1D compression, researchers observed that particles initially translate and rotate which lead to more contacts between particles and the development of force chains to resist applied loads. Particles within force chains resist most of the applied loads while neighbor particles provide lateral support to prevent particles within force chains from buckling. Several experimental and numerical models have been proposed in the literature to characterize force chains within granular materials. This paper presents a 3D finite element (FE) model that simulates 1D compression experiment on F-75more » Ottawa sand. The FE mesh of particles closely matched 3D physical shape of sand particles that were acquired using 3D synchrotron micro-computed tomography (SMT) technique. The paper presents a quantitative assessment of the model, in which evolution of force chains, fracture modes, and stress-strain relationships showed an excellent agreement with experimental measurements reported by Cil et al. Alshibli (2017).« less
The Advancement Value Chain: An Exploratory Model

ERIC Educational Resources Information Center

Leonard, Edward F., III

2005-01-01

Since the introduction of the value chain concept in 1985, several varying, yet virtually similar, value chains have been developed for the business enterprise. Shifting to higher education, can a value chain be found that links together the various activities of advancement so that an institution's leaders can actually look at the philanthropic…
Reasons for Staying: A Test of the Chain of Response Model among Community-College Students. AIR 2001 Annual Forum Paper.

ERIC Educational Resources Information Center

Salomonson, Kristen; Moss, Brian G.; Hill, H. Leon

This paper uses the Chain of Response Model (CRM) to help explain retention in the community college population. In the CRM, the student's decision to remain at an educational institution is not an isolated act, but rather the result of a complex chain of responses based on her/his cognitive evaluation of the present situation. The authors applied…
Asymptotic study of pulsating evolution of overdriven and CJ detonation with a chain-branching kinetics model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Short, Mark; Chliquete, Carlos

2011-01-20

The pulsating dynamics of gaseous detonations with a model two-step chain-branching kinetic mechanism are studied both numerically and asymptotically. The model studied here was also used in [4], [3] and [2] and mimics the attributes of some chain-branching reaction mechanisms. Specifically, the model comprises a chain-initiationlbranching zone with an Arrhenius temperature-sensitive rate behind the detonation shock where fuel is converted into chain-radical with no heat release. This is followed by a chain-termination zone having a temperature insensitive rate where the exothermic heat of reaction is released. The lengths of these two zones depend on the relative rates of each stage.more » It was determined in [4] and [3] via asymptotic and numerical analysis that the ratio of the length of the chain-branching zone to that of the chain-initation zone relative to the size of the von Neumann state scaled activation energy in the chain initiation/branching zone has a primary influence of the stability of one-dimensional pulsating instability behavior for this model. In [2], the notion of a specific stability parameter related to this ratio was proposed that determines the boundary between stable and unstable waves. In [4], a slow-time varying asymptotic study was conducted of pulsating instability of Chapman-Jouguet (CJ) detonations with the above two-step rate model, assuming a large activation energy for the chain-initiation zone and a chain-termination zone longer than the chain-initiation zone. Deviations D{sub n}{sup (1)} ({tau}) of the detonation velocity from Chapman-Jouguet were of the order of the non-dimensional activation energy. Solutions were sought for a pulsation timescale of the order of the non-dimensional activation energy times the particle transit time through the induction zone. On this time-scale, the evolution of the chain-initation zone is quasi-steady. In [4], a time-dependent non-linear evolution equation for D{sub n}{sup (1)} ({tau}) was then constructed via a perturbation procedure for cases where the ratio of the length of the chain-termination zone to chain-initiation zone was less than the non-dimensional activation energy. To leading order, the steady CJ detonation was found to be unstable; higher-order corrections lead to the construction of a stability limit between stable and unsteady pulsating solutions. One conclusion from this study is that for a stability limit to occur at leading order, the period of pulsation of the detonation must occur on the time scale of particle passage through the longer chain-termination zone, while the length of the chain-termination zone must be of order of the non-dimensional activation energy longer than the chain-initiation zone. The relevance of these suggested scalings was verified via numerical solutions of the full Euler system in [3], and formed the basis of the stability parameter criteria suggested in [2]. In the following, we formulate an asymptotic study based on these new suggested scales, studying the implications for describing pulsating behavior in gaseous chain-branching detonations. Specifically, we find that the chain-induction zone structure is the same as that studied in [4]. However, the study of unsteady evolution in the chain-termination region is now governed by a set of asymptotically derived nonlinear POEs. Equations for the linear stablity behavior of this set of POE's is obtained, while the nonlinear POEs are solved numerically using a shock-attached, shock-fitting method developed by Henrick et aJ. [1]. The results thus far show that the stability threshold calculated using the new ratio of the chain-termination zone length to that of the chain-initiation zone yields a marked improvement over [2]. Additionally, solutions will be compared with predictions obtained from the solution of the full Euler system. Finally, the evolution equation previously derived in [4] has been generalized to consider both arbitrary reaction orders and any degree of overdrive.« less
An Overview of Markov Chain Methods for the Study of Stage-Sequential Developmental Processes

ERIC Educational Resources Information Center

Kapland, David

2008-01-01

This article presents an overview of quantitative methodologies for the study of stage-sequential development based on extensions of Markov chain modeling. Four methods are presented that exemplify the flexibility of this approach: the manifest Markov model, the latent Markov model, latent transition analysis, and the mixture latent Markov model.…
Toward tailoring Majorana bound states in artificially constructed magnetic atom chains on elemental superconductors

PubMed Central

Thorwart, Michael

2018-01-01

Realizing Majorana bound states (MBS) in condensed matter systems is a key challenge on the way toward topological quantum computing. As a promising platform, one-dimensional magnetic chains on conventional superconductors were theoretically predicted to host MBS at the chain ends. We demonstrate a novel approach to design of model-type atomic-scale systems for studying MBS using single-atom manipulation techniques. Our artificially constructed atomic Fe chains on a Re surface exhibit spin spiral states and a remarkable enhancement of the local density of states at zero energy being strongly localized at the chain ends. Moreover, the zero-energy modes at the chain ends are shown to emerge and become stabilized with increasing chain length. Tight-binding model calculations based on parameters obtained from ab initio calculations corroborate that the system resides in the topological phase. Our work opens new pathways to design MBS in atomic-scale hybrid structures as a basis for fault-tolerant topological quantum computing. PMID:29756034
Toward tailoring Majorana bound states in artificially constructed magnetic atom chains on elemental superconductors.

PubMed

Kim, Howon; Palacio-Morales, Alexandra; Posske, Thore; Rózsa, Levente; Palotás, Krisztián; Szunyogh, László; Thorwart, Michael; Wiesendanger, Roland

2018-05-01

Realizing Majorana bound states (MBS) in condensed matter systems is a key challenge on the way toward topological quantum computing. As a promising platform, one-dimensional magnetic chains on conventional superconductors were theoretically predicted to host MBS at the chain ends. We demonstrate a novel approach to design of model-type atomic-scale systems for studying MBS using single-atom manipulation techniques. Our artificially constructed atomic Fe chains on a Re surface exhibit spin spiral states and a remarkable enhancement of the local density of states at zero energy being strongly localized at the chain ends. Moreover, the zero-energy modes at the chain ends are shown to emerge and become stabilized with increasing chain length. Tight-binding model calculations based on parameters obtained from ab initio calculations corroborate that the system resides in the topological phase. Our work opens new pathways to design MBS in atomic-scale hybrid structures as a basis for fault-tolerant topological quantum computing.
Modified allocation capacitated planning model in blood supply chain management

NASA Astrophysics Data System (ADS)

Mansur, A.; Vanany, I.; Arvitrida, N. I.

2018-04-01

Blood supply chain management (BSCM) is a complex process management that involves many cooperating stakeholders. BSCM involves four echelon processes, which are blood collection or procurement, production, inventory, and distribution. This research develops an optimization model of blood distribution planning. The efficiency of decentralization and centralization policies in a blood distribution chain are compared, by optimizing the amount of blood delivered from a blood center to a blood bank. This model is developed based on allocation problem of capacitated planning model. At the first stage, the capacity and the cost of transportation are considered to create an initial capacitated planning model. Then, the inventory holding and shortage costs are added to the model. These additional parameters of inventory costs lead the model to be more realistic and accurate.
Characterizing the tradeoffs and costs associated with transportation congestion in supply chains.

DOT National Transportation Integrated Search

2010-01-21

We consider distribution and location-planning models for supply chains that explicitly : account for traffic congestion effects. The majority of facility location and transportation : planning models in the operations research literature consider fa...
Integrated forward and reverse supply chain: A tire case study.

PubMed

Pedram, Ali; Yusoff, Nukman Bin; Udoncy, Olugu Ezutah; Mahat, Abu Bakar; Pedram, Payam; Babalola, Ayo

2017-02-01

This paper attempts to integrate both a forward and reverse supply chain to design a closed-loop supply chain network (CLSC). The problem in the design of a CLSC network is uncertainty in demand, return products and the quality of return products. Scenario analyses are generated to overcome this uncertainty. In contrast to the existing supply chain network design models, a new application of a CLSC network was studied in this paper to reduce waste. A multi-product, multi-tier mixed integer linear model is developed for a CLSC network design. The main objective is to maximize profit and provide waste management decision support in order to minimize pollution. The result shows applicability of the model in the tire industry. The model determines the number and the locations of facilities and the material flows between these facilities. Copyright © 2016 Elsevier Ltd. All rights reserved.
Chemical supply chain modeling for analysis of homeland security events

DOE PAGES

Ehlen, Mark A.; Sun, Amy C.; Pepple, Mark A.; ...

2013-09-06

The potential impacts of man-made and natural disasters on chemical plants, complexes, and supply chains are of great importance to homeland security. To be able to estimate these impacts, we developed an agent-based chemical supply chain model that includes: chemical plants with enterprise operations such as purchasing, production scheduling, and inventories; merchant chemical markets, and multi-modal chemical shipments. Large-scale simulations of chemical-plant activities and supply chain interactions, running on desktop computers, are used to estimate the scope and duration of disruptive-event impacts, and overall system resilience, based on the extent to which individual chemical plants can adjust their internal operationsmore » (e.g., production mixes and levels) versus their external interactions (market sales and purchases, and transportation routes and modes). As a result, to illustrate how the model estimates the impacts of a hurricane disruption, a simple example model centered on 1,4-butanediol is presented.« less
Predicting the stability of nanodevices

NASA Astrophysics Data System (ADS)

Lin, Z. Z.; Yu, W. F.; Wang, Y.; Ning, X. J.

2011-05-01

A simple model based on the statistics of single atoms is developed to predict the stability or lifetime of nanodevices without empirical parameters. Under certain conditions, the model produces the Arrhenius law and the Meyer-Neldel compensation rule. Compared with the classical molecular-dynamics simulations for predicting the stability of monatomic carbon chain at high temperature, the model is proved to be much more accurate than the transition state theory. Based on the ab initio calculation of the static potential, the model can give out a corrected lifetime of monatomic carbon and gold chains at higher temperature, and predict that the monatomic chains are very stable at room temperature.
Molecular dynamics modeling of PPTA crystallite mechanical properties in the presence of defects

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mercer, Brian; Zywicz, Edward; Papadopoulos, Panayiotis

Here, the mechanical properties of PPTA crystallites, the fundamental building blocks of aramid polymer fibers such as Kevlar® and Twaron®, are studied here using molecular dynamics simulations. The ReaxFF interatomic potential is employed to study crystallite failure via covalent and hydrogen bond rupture in constant strain-rate tensile loading simulations. Emphasis is placed on analyzing how chain-end defects in the crystallite influence its mechanical response and fracture strength. Chain-end defects are found to affect the behavior of nearby chains in a region of the PPTA crystallite that is small relative to the typical crystallite size in manufactured aramid fibers. The centralmore » Csingle bondN bond along the backbone chain is identified as the weakest in the PPTA polymer chain backbone in dynamic strain-to-failure simulations of the crystallite. It is found that clustering of chain-ends leads to reduced crystallite strength and crystallite failure via hydrogen bond rupture and chain sliding, whereas randomly scattered defects impact the strength less and failure is by covalent bond rupture and chain scission. The axial crystallite modulus increases with increasing chain length and is independent of chain-end defect locations. On the basis of these findings, a theoretical model is proposed to predict the axial modulus as a function of chain length.« less
Molecular dynamics modeling of PPTA crystallite mechanical properties in the presence of defects

DOE PAGES

Mercer, Brian; Zywicz, Edward; Papadopoulos, Panayiotis

2017-03-11

Here, the mechanical properties of PPTA crystallites, the fundamental building blocks of aramid polymer fibers such as Kevlar® and Twaron®, are studied here using molecular dynamics simulations. The ReaxFF interatomic potential is employed to study crystallite failure via covalent and hydrogen bond rupture in constant strain-rate tensile loading simulations. Emphasis is placed on analyzing how chain-end defects in the crystallite influence its mechanical response and fracture strength. Chain-end defects are found to affect the behavior of nearby chains in a region of the PPTA crystallite that is small relative to the typical crystallite size in manufactured aramid fibers. The centralmore » Csingle bondN bond along the backbone chain is identified as the weakest in the PPTA polymer chain backbone in dynamic strain-to-failure simulations of the crystallite. It is found that clustering of chain-ends leads to reduced crystallite strength and crystallite failure via hydrogen bond rupture and chain sliding, whereas randomly scattered defects impact the strength less and failure is by covalent bond rupture and chain scission. The axial crystallite modulus increases with increasing chain length and is independent of chain-end defect locations. On the basis of these findings, a theoretical model is proposed to predict the axial modulus as a function of chain length.« less
Buckling of paramagnetic chains in soft gels

NASA Astrophysics Data System (ADS)

Huang, Shilin; Pessot, Giorgio; Cremer, Peet; Weeber, Rudolf; Holm, Christian; Nowak, Johannes; Odenbach, Stefan; Menzel, Andreas M.; Auernhammer, Günter K.

We study the magneto-elastic coupling behavior of paramagnetic chains in soft polymer gels exposed to external magnetic fields. To this end, a laser scanning confocal microscope is used to observe the morphology of the paramagnetic chains together with the deformation field of the surrounding gel network. The paramagnetic chains in soft polymer gels show rich morphological shape changes under oblique magnetic fields, in particular a pronounced buckling deformation. The details of the resulting morphological shapes depend on the length of the chain, the strength of the external magnetic field, and the modulus of the gel. Based on the observation that the magnetic chains are strongly coupled to the surrounding polymer network, a simplified model is developed to describe their buckling behavior. A coarse-grained molecular dynamics simulation model featuring an increased matrix stiffness on the surfaces of the particles leads to morphologies in agreement with the experimentally observed buckling effects.
R-matrix-valued Lax pairs and long-range spin chains

NASA Astrophysics Data System (ADS)

Sechin, I.; Zotov, A.

2018-06-01

In this paper we discuss R-matrix-valued Lax pairs for slN Calogero-Moser model and their relation to integrable quantum long-range spin chains of the Haldane-Shastry-Inozemtsev type. First, we construct the R-matrix-valued Lax pairs for the third flow of the classical Calogero-Moser model. Then we notice that the scalar parts (in the auxiliary space) of the M-matrices corresponding to the second and third flows have form of special spin exchange operators. The freezing trick restricts them to quantum Hamiltonians of long-range spin chains. We show that for a special choice of the R-matrix these Hamiltonians reproduce those for the Inozemtsev chain. In the general case related to the Baxter's elliptic R-matrix we obtain a natural anisotropic extension of the Inozemtsev chain. Commutativity of the Hamiltonians is verified numerically. Trigonometric limits lead to the Haldane-Shastry chains and their anisotropic generalizations.
Theory and simulation of the dynamics, deformation, and breakup of a chain of superparamagnetic beads under a rotating magnetic field

NASA Astrophysics Data System (ADS)

Vázquez-Quesada, A.; Franke, T.; Ellero, M.

2017-03-01

In this work, an analytical model for the behavior of superparamagnetic chains under the effect of a rotating magnetic field is presented. It is postulated that the relevant mechanisms for describing the shape and breakup of the chains into smaller fragments are the induced dipole-dipole magnetic force on the external beads, their translational and rotational drag forces, and the tangential lubrication between particles. Under this assumption, the characteristic S-shape of the chain can be qualitatively understood. Furthermore, based on a straight chain approximation, a novel analytical expression for the critical frequency for the chain breakup is obtained. In order to validate the model, the analytical expressions are compared with full three-dimensional smoothed particle hydrodynamics simulations of magnetic beads showing excellent agreement. Comparison with previous theoretical results and experimental data is also reported.
Design and analysis of the Gemini chain system in dual clutch transmission of automobile

NASA Astrophysics Data System (ADS)

Cheng, Yabing; Guo, Haitao; Fu, Zhenming; Wan, Nen; Li, Lei; Wang, Yang

2015-01-01

Chain drive system is widely used in the conditions of high-speed, overload, variable speed and load. Many studies are focused on the meshing theory and wear characteristics of chain drive system, but system design, analysis, and noise characteristics of the chain drive system are weak. System design and noise characteristic are studied for a new type Gemini chain of dual-clutch automatic transmission. Based on the meshing theory of silent chain, the design parameters of the Gemini chain system are calculated and the mathematical models and dynamic analysis models of the Gemini chain system are established. Dynamic characteristics of the Gemini chain system is simulated and the contact force of plate and pin, plate and sprockets, the chain tension forces, the transmission error and the stress of plates and pins are analyzed. According to the simulation results of the Gemini chain system, the noise experiment about system is carried out. The noise values are tested at different speed and load and spectral characteristics are analyzed. The results of simulation and experimental show that the contact forces of plate and pin, plate and sprockets are smaller than the allowable stress values, the chain tension force is less than ultimate tension and transmission error is limited in 1.2%. The noise values can meet the requirements of industrial design, and it is proved that the design and analysis method of the Gemini chain system is scientific and feasible. The design and test system is built from analysis to test of Gemini chain system. This research presented will provide a corresponding theoretical guidance for the design and dynamic characteristics and noise characteristics of chain drive system.
Modeling relief demands in an emergency supply chain system under large-scale disasters based on a queuing network.

PubMed

He, Xinhua; Hu, Wenfa

2014-01-01

This paper presents a multiple-rescue model for an emergency supply chain system under uncertainties in large-scale affected area of disasters. The proposed methodology takes into consideration that the rescue demands caused by a large-scale disaster are scattered in several locations; the servers are arranged in multiple echelons (resource depots, distribution centers, and rescue center sites) located in different places but are coordinated within one emergency supply chain system; depending on the types of rescue demands, one or more distinct servers dispatch emergency resources in different vehicle routes, and emergency rescue services queue in multiple rescue-demand locations. This emergency system is modeled as a minimal queuing response time model of location and allocation. A solution to this complex mathematical problem is developed based on genetic algorithm. Finally, a case study of an emergency supply chain system operating in Shanghai is discussed. The results demonstrate the robustness and applicability of the proposed model.

Modeling Relief Demands in an Emergency Supply Chain System under Large-Scale Disasters Based on a Queuing Network

PubMed Central

He, Xinhua

2014-01-01

This paper presents a multiple-rescue model for an emergency supply chain system under uncertainties in large-scale affected area of disasters. The proposed methodology takes into consideration that the rescue demands caused by a large-scale disaster are scattered in several locations; the servers are arranged in multiple echelons (resource depots, distribution centers, and rescue center sites) located in different places but are coordinated within one emergency supply chain system; depending on the types of rescue demands, one or more distinct servers dispatch emergency resources in different vehicle routes, and emergency rescue services queue in multiple rescue-demand locations. This emergency system is modeled as a minimal queuing response time model of location and allocation. A solution to this complex mathematical problem is developed based on genetic algorithm. Finally, a case study of an emergency supply chain system operating in Shanghai is discussed. The results demonstrate the robustness and applicability of the proposed model. PMID:24688367
Model Development of Cold Chains for Fresh Fruits and Vegetables Distribution: A Case Study in Bali Province

NASA Astrophysics Data System (ADS)

Waisnawa, I. N. G. S.; Santosa, I. D. M. C.; Sunu, I. P. W.; Wirajati, IGAB

2018-01-01

In developing countries such as Indonesia, as much as 40% of total vegetables and fruits production becomes waste because of lack refrigeration. This condition also contributes a food crisis problem besides other factor such as, climate change and number of population. Cold chain system that will be modelled in this study is for vegetables and fruits and refrigeration system as the main devices. In future, this system will play an important role for the food crisis solution where fresh food can be distributed very well with significant low waste. The fresh food also can be kept with good quality and hygienist (bacteria contaminated). Cold Chain model will be designed using refrigeration components including, pre cooling chiller, cold room, and truck refrigeration. This study will be conducted by survey and observation di around Bali Province focus on vegetables and fruits production center. Interviews and questionnaire will be also done to get some information about the conventional distribution obstacles and problem. Distribution mapping will be developed and created. The data base of the storage characteristic of the fruits and vegetable also collected through experiment and secondary data. Depend on the mapping and data base can be developed a cold chain model that has the best performance application. The model will be can directly apply in Bali to get eligible cold chain in Bali. The cold chain model will be compared with the conventional distribution system using ALCC/LCC method and also others factor and will be weighted to get better results.
Structure of flexible and semiflexible polyelectrolyte chains in confined spaces of slit micro/nanochannels.

PubMed

Jeon, Jonggu; Chun, Myung-Suk

2007-04-21

Understanding the behavior of a polyelectrolyte in confined spaces has direct relevance in design and manipulation of microfluidic devices, as well as transport in living organisms. In this paper, a coarse-grained model of anionic semiflexible polyelectrolyte is applied, and its structure and dynamics are fully examined with Brownian dynamics (BD) simulations both in bulk solution and under confinement between two negatively charged parallel plates. The modeling is based on the nonlinear bead-spring discretization of a continuous chain with additional long-range electrostatic, Lennard-Jones, and hydrodynamic interactions between pairs of beads. The authors also consider the steric and electrostatic interactions between the bead and the confining wall. Relevant model parameters are determined from experimental rheology data on the anionic polysaccharide xanthan reported previously. For comparison, both flexible and semiflexible models are developed accompanying zero and finite intrinsic persistence lengths, respectively. The conformational changes of the polyelectrolyte chain induced by confinements and their dependence on the screening effect of the electrolyte solution are faithfully characterized with BD simulations. Depending on the intrinsic rigidity and the medium ionic strength, the polyelectrolyte can be classified as flexible, semiflexible, or rigid. Confined flexible and semiflexible chains exhibit a nonmonotonic variation in size, as measured by the radius of gyration and end-to-end distance, with changing slit width. For the semiflexible chain, this is coupled to the variations in long-range bond vector correlation. The rigid chain, realized at low ionic strength, does not have minima in size but exhibits a sigmoidal transition. The size of confined semiflexible and rigid polyelectrolytes can be well described by the wormlike chain model once the electrostatic effects are taken into account by the persistence length measured at long length scale.
Traveling-wave solutions in continuous chains of unidirectionally coupled oscillators

NASA Astrophysics Data System (ADS)

Glyzin, S. D.; Kolesov, A. Yu; Rozov, N. Kh

2017-12-01

Proposed is a mathematical model of a continuous annular chain of unidirectionally coupled generators given by certain nonlinear advection-type hyperbolic boundary value problem. Such problems are constructed by a limit transition from annular chains of unidirectionally coupled ordinary differential equations with an unbounded increase in the number of links. It is shown that any preassigned finite number of stable periodic motions of the traveling-wave type can coexist in the model.
Optimizing decentralized production-distribution planning problem in a multi-period supply chain network under uncertainty

NASA Astrophysics Data System (ADS)

Nourifar, Raheleh; Mahdavi, Iraj; Mahdavi-Amiri, Nezam; Paydar, Mohammad Mahdi

2017-09-01

Decentralized supply chain management is found to be significantly relevant in today's competitive markets. Production and distribution planning is posed as an important optimization problem in supply chain networks. Here, we propose a multi-period decentralized supply chain network model with uncertainty. The imprecision related to uncertain parameters like demand and price of the final product is appropriated with stochastic and fuzzy numbers. We provide mathematical formulation of the problem as a bi-level mixed integer linear programming model. Due to problem's convolution, a structure to solve is developed that incorporates a novel heuristic algorithm based on Kth-best algorithm, fuzzy approach and chance constraint approach. Ultimately, a numerical example is constructed and worked through to demonstrate applicability of the optimization model. A sensitivity analysis is also made.
Predicting the chemical stability of monatomic chains

NASA Astrophysics Data System (ADS)

Lin, Zheng-Zhe; Chen, Xi

2013-02-01

A simple model for evaluating the thermal atomic transfer rates in nanosystems (Lin Z.-Z. et al., EPL, 94 (2011) 40002) was developed to predict the chemical reaction rates of nanosystems with small gas molecules. The accuracy of the model was verified by MD simulations for molecular adsorption and desorption on a monatomic chain. By the prediction, a monatomic carbon chain should survive for 1.2 × 102 years in the ambient of 1 atm O2 at room temperature, and it is very invulnerable to N2, H2O, NO2, CO and CO2, while a monatomic gold chain quickly ruptures in vacuum. It is worth noting that since the model can be easily applied via common ab initio calculations, it could be widely used in the prediction of chemical stability of nanosystems.
Critical appraisal of assumptions in chains of model calculations used to project local climate impacts for adaptation decision support—the case of Baakse Beek

NASA Astrophysics Data System (ADS)

van der Sluijs, Jeroen P.; Arjan Wardekker, J.

2015-04-01

In order to enable anticipation and proactive adaptation, local decision makers increasingly seek detailed foresight about regional and local impacts of climate change. To this end, the Netherlands Models and Data-Centre implemented a pilot chain of sequentially linked models to project local climate impacts on hydrology, agriculture and nature under different national climate scenarios for a small region in the east of the Netherlands named Baakse Beek. The chain of models sequentially linked in that pilot includes a (future) weather generator and models of respectively subsurface hydrogeology, ground water stocks and flows, soil chemistry, vegetation development, crop yield and nature quality. These models typically have mismatching time step sizes and grid cell sizes. The linking of these models unavoidably involves the making of model assumptions that can hardly be validated, such as those needed to bridge the mismatches in spatial and temporal scales. Here we present and apply a method for the systematic critical appraisal of model assumptions that seeks to identify and characterize the weakest assumptions in a model chain. The critical appraisal of assumptions presented in this paper has been carried out ex-post. For the case of the climate impact model chain for Baakse Beek, the three most problematic assumptions were found to be: land use and land management kept constant over time; model linking of (daily) ground water model output to the (yearly) vegetation model around the root zone; and aggregation of daily output of the soil hydrology model into yearly input of a so called ‘mineralization reduction factor’ (calculated from annual average soil pH and daily soil hydrology) in the soil chemistry model. Overall, the method for critical appraisal of model assumptions presented and tested in this paper yields a rich qualitative insight in model uncertainty and model quality. It promotes reflectivity and learning in the modelling community, and leads to well informed recommendations for model improvement.
Educational Aspirations: Markov and Poisson Models. Rural Industrial Development Project Working Paper Number 14, August 1971.

ERIC Educational Resources Information Center

Kayser, Brian D.

The fit of educational aspirations of Illinois rural high school youths to 3 related one-parameter mathematical models was investigated. The models used were the continuous-time Markov chain model, the discrete-time Markov chain, and the Poisson distribution. The sample of 635 students responded to questionnaires from 1966 to 1969 as part of an…
Housing Value Projection Model Related to Educational Planning: The Feasibility of a New Methodology. Final Report.

ERIC Educational Resources Information Center

Helbock, Richard W.; Marker, Gordon

This study concerns the feasibility of a Markov chain model for projecting housing values and racial mixes. Such projections could be used in planning the layout of school districts to achieve desired levels of socioeconomic heterogeneity. Based upon the concepts and assumptions underlying a Markov chain model, it is concluded that such a model is…
Sustainable Supplier Performance Evaluation and Selection with Neofuzzy TOPSIS Method

PubMed Central

Chaharsooghi, S. K.; Ashrafi, Mehdi

2014-01-01

Supplier selection plays an important role in the supply chain management and traditional criteria such as price, quality, and flexibility are considered for supplier performance evaluation in researches. In recent years sustainability has received more attention in the supply chain management literature with triple bottom line (TBL) describing the sustainability in supply chain management with social, environmental, and economic initiatives. This paper explores sustainability in supply chain management and examines the problem of identifying a new model for supplier selection based on extended model of TBL approach in supply chain by presenting fuzzy multicriteria method. Linguistic values of experts' subjective preferences are expressed with fuzzy numbers and Neofuzzy TOPSIS is proposed for finding the best solution of supplier selection problem. Numerical results show that the proposed model is efficient for integrating sustainability in supplier selection problem. The importance of using complimentary aspects of sustainability and Neofuzzy TOPSIS concept in sustainable supplier selection process is shown with sensitivity analysis. PMID:27379267
Optimization of Location-Routing Problem for Cold Chain Logistics Considering Carbon Footprint.

PubMed

Wang, Songyi; Tao, Fengming; Shi, Yuhe

2018-01-06

In order to solve the optimization problem of logistics distribution system for fresh food, this paper provides a low-carbon and environmental protection point of view, based on the characteristics of perishable products, and combines with the overall optimization idea of cold chain logistics distribution network, where the green and low-carbon location-routing problem (LRP) model in cold chain logistics is developed with the minimum total costs as the objective function, which includes carbon emission costs. A hybrid genetic algorithm with heuristic rules is designed to solve the model, and an example is used to verify the effectiveness of the algorithm. Furthermore, the simulation results obtained by a practical numerical example show the applicability of the model while provide green and environmentally friendly location-distribution schemes for the cold chain logistics enterprise. Finally, carbon tax policies are introduced to analyze the impact of carbon tax on the total costs and carbon emissions, which proves that carbon tax policy can effectively reduce carbon dioxide emissions in cold chain logistics network.
Sustainable Supplier Performance Evaluation and Selection with Neofuzzy TOPSIS Method.

PubMed

Chaharsooghi, S K; Ashrafi, Mehdi

2014-01-01

Supplier selection plays an important role in the supply chain management and traditional criteria such as price, quality, and flexibility are considered for supplier performance evaluation in researches. In recent years sustainability has received more attention in the supply chain management literature with triple bottom line (TBL) describing the sustainability in supply chain management with social, environmental, and economic initiatives. This paper explores sustainability in supply chain management and examines the problem of identifying a new model for supplier selection based on extended model of TBL approach in supply chain by presenting fuzzy multicriteria method. Linguistic values of experts' subjective preferences are expressed with fuzzy numbers and Neofuzzy TOPSIS is proposed for finding the best solution of supplier selection problem. Numerical results show that the proposed model is efficient for integrating sustainability in supplier selection problem. The importance of using complimentary aspects of sustainability and Neofuzzy TOPSIS concept in sustainable supplier selection process is shown with sensitivity analysis.
An approach for formalising the supply chain operations

NASA Astrophysics Data System (ADS)

Zdravković, Milan; Panetto, Hervé; Trajanović, Miroslav; Aubry, Alexis

2011-11-01

Reference models play an important role in the knowledge management of the various complex collaboration domains (such as supply chain networks). However, they often show a lack of semantic precision and, they are sometimes incomplete. In this article, we present an approach to overcome semantic inconsistencies and incompleteness of the Supply Chain Operations Reference (SCOR) model and hence improve its usefulness and expand the application domain. First, we describe a literal web ontology language (OWL) specification of SCOR concepts (and related tools) built with the intention to preserve the original approach in the classification of process reference model entities, and hence enable the effectiveness of usage in original contexts. Next, we demonstrate the system for its exploitation, in specific - tools for SCOR framework browsing and rapid supply chain process configuration. Then, we describe the SCOR-Full ontology, its relations with relevant domain ontology and show how it can be exploited for improvement of SCOR ontological framework competence. Finally, we elaborate the potential impact of the presented approach, to interoperability of systems in supply chain networks.
Coarse-grained, foldable, physical model of the polypeptide chain.

PubMed

Chakraborty, Promita; Zuckermann, Ronald N

2013-08-13

Although nonflexible, scaled molecular models like Pauling-Corey's and its descendants have made significant contributions in structural biology research and pedagogy, recent technical advances in 3D printing and electronics make it possible to go one step further in designing physical models of biomacromolecules: to make them conformationally dynamic. We report here the design, construction, and validation of a flexible, scaled, physical model of the polypeptide chain, which accurately reproduces the bond rotational degrees of freedom in the peptide backbone. The coarse-grained backbone model consists of repeating amide and α-carbon units, connected by mechanical bonds (corresponding to ϕ and ψ) that include realistic barriers to rotation that closely approximate those found at the molecular scale. Longer-range hydrogen-bonding interactions are also incorporated, allowing the chain to readily fold into stable secondary structures. The model is easily constructed with readily obtainable parts and promises to be a tremendous educational aid to the intuitive understanding of chain folding as the basis for macromolecular structure. Furthermore, this physical model can serve as the basis for linking tangible biomacromolecular models directly to the vast array of existing computational tools to provide an enhanced and interactive human-computer interface.
Human disease mortality kinetics are explored through a chain model embodying principles of extreme value theory and competing risks.

PubMed

Juckett, D A; Rosenberg, B

1992-04-21

The distributions for human disease-specific mortality exhibit two striking characteristics: survivorship curves that intersect near the longevity limit; and, the clustering of best-fitting Weibull shape parameter values into groups centered on integers. Correspondingly, we have hypothesized that the distribution intersections result from either competitive processes or population partitioning and the integral clustering in the shape parameter results from the occurrence of a small number of rare, rate-limiting events in disease progression. In this report we initiate a theoretical examination of these questions by exploring serial chain model dynamics and parameteric competing risks theory. The links in our chain models are composed of more than one bond, where the number of bonds in a link are denoted the link size and are the number of events necessary to break the link and, hence, the chain. We explored chains with all links of the same size or with segments of the chain composed of different size links (competition). Simulations showed that chain breakage dynamics depended on the weakest-link principle and followed kinetics of extreme-values which were very similar to human mortality kinetics. In particular, failure distributions for simple chains were Weibull-type extreme-value distributions with shape parameter values that were identifiable with the integral link size in the limit of infinite chain length. Furthermore, for chains composed of several segments of differing link size, the survival distributions for the various segments converged at a point in the S(t) tails indistinguishable from human data. This was also predicted by parameteric competing risks theory using Weibull underlying distributions. In both the competitive chain simulations and the parametric competing risks theory, however, the shape values for the intersecting distributions deviated from the integer values typical of human data. We conclude that rare events can be the source of integral shapes in human mortality, that convergence is a salient feature of multiple endpoints, but that pure competition may not be the best explanation for the exact type of convergence observable in human mortality. Finally, while the chain models were not motivated by any specific biological structures, interesting biological correlates to them may be useful in gerontological research.
Analog modeling of Worm-Like Chain molecules using macroscopic beads-on-a-string.

PubMed

Tricard, Simon; Feinstein, Efraim; Shepherd, Robert F; Reches, Meital; Snyder, Phillip W; Bandarage, Dileni C; Prentiss, Mara; Whitesides, George M

2012-07-07

This paper describes an empirical model of polymer dynamics, based on the agitation of millimeter-sized polymeric beads. Although the interactions between the particles in the macroscopic model and those between the monomers of molecular-scale polymers are fundamentally different, both systems follow the Worm-Like Chain theory.
Modelling Faculty Replacement Strategies Using a Time-Dependent Finite Markov-Chain Process.

ERIC Educational Resources Information Center

Hackett, E. Raymond; Magg, Alexander A.; Carrigan, Sarah D.

1999-01-01

Describes the use of a time-dependent Markov-chain model to develop faculty-replacement strategies within a college at a research university. The study suggests that a stochastic modelling approach can provide valuable insight when planning for personnel needs in the immediate (five-to-ten year) future. (MSE)
A discrete scattering series representation for lattice embedded models of chain cyclization

NASA Astrophysics Data System (ADS)

Fraser, Simon J.; Winnik, Mitchell A.

1980-01-01

In this paper we develop a lattice based model of chain cyclization in the presence of a set of occupied sites V in the lattice. We show that within the approximation of a Markovian chain propagator the effect of V on the partition function for the system can be written as a time-ordered exponential series in which V behaves like a scattering potential and chainlength is the timelike parameter. The discrete and finite nature of this model allows us to obtain rigorous upper and lower bounds to the series limit. We adapt these formulas to calculation of the partition functions and cyclization probabilities of terminally and globally cyclizing chains. Two classes of cyclization are considered: in the first model the target set H may be visited repeatedly (the Markovian model); in the second case vertices in H may be visited at most once(the non-Markovian or taboo model). This formulation depends on two fundamental combinatorial structures, namely the inclusion-exclusion principle and the set of subsets of a set. We have tried to interpret these abstract structures with physical analogies throughout the paper.
An affine microsphere approach to modeling strain-induced crystallization in rubbery polymers

NASA Astrophysics Data System (ADS)

Nateghi, A.; Dal, H.; Keip, M.-A.; Miehe, C.

2018-01-01

Upon stretching a natural rubber sample, polymer chains orient themselves in the direction of the applied load and form crystalline regions. When the sample is retracted, the original amorphous state of the network is restored. Due to crystallization, properties of rubber change considerably. The reinforcing effect of the crystallites stiffens the rubber and increases the crack growth resistance. It is of great importance to understand the mechanism leading to strain-induced crystallization. However, limited theoretical work has been done on the investigation of the associated kinetics. A key characteristic observed in the stress-strain diagram of crystallizing rubber is the hysteresis, which is entirely attributed to strain-induced crystallization. In this work, we propose a micromechanically motivated material model for strain-induced crystallization in rubbers. Our point of departure is constructing a micromechanical model for a single crystallizing polymer chain. Subsequently, a thermodynamically consistent evolution law describing the kinetics of crystallization on the chain level is proposed. This chain model is then incorporated into the affine microsphere model. Finally, the model is numerically implemented and its performance is compared to experimental data.
Fuzzy Markov random fields versus chains for multispectral image segmentation.

PubMed

Salzenstein, Fabien; Collet, Christophe

2006-11-01

This paper deals with a comparison of recent statistical models based on fuzzy Markov random fields and chains for multispectral image segmentation. The fuzzy scheme takes into account discrete and continuous classes which model the imprecision of the hidden data. In this framework, we assume the dependence between bands and we express the general model for the covariance matrix. A fuzzy Markov chain model is developed in an unsupervised way. This method is compared with the fuzzy Markovian field model previously proposed by one of the authors. The segmentation task is processed with Bayesian tools, such as the well-known MPM (Mode of Posterior Marginals) criterion. Our goal is to compare the robustness and rapidity for both methods (fuzzy Markov fields versus fuzzy Markov chains). Indeed, such fuzzy-based procedures seem to be a good answer, e.g., for astronomical observations when the patterns present diffuse structures. Moreover, these approaches allow us to process missing data in one or several spectral bands which correspond to specific situations in astronomy. To validate both models, we perform and compare the segmentation on synthetic images and raw multispectral astronomical data.

Multi-scale modeling of diffusion-controlled reactions in polymers: renormalisation of reactivity parameters.

PubMed

Everaers, Ralf; Rosa, Angelo

2012-01-07

The quantitative description of polymeric systems requires hierarchical modeling schemes, which bridge the gap between the atomic scale, relevant to chemical or biomolecular reactions, and the macromolecular scale, where the longest relaxation modes occur. Here, we use the formalism for diffusion-controlled reactions in polymers developed by Wilemski, Fixman, and Doi to discuss the renormalisation of the reactivity parameters in polymer models with varying spatial resolution. In particular, we show that the adjustments are independent of chain length. As a consequence, it is possible to match reactions times between descriptions with different resolution for relatively short reference chains and to use the coarse-grained model to make quantitative predictions for longer chains. We illustrate our results by a detailed discussion of the classical problem of chain cyclization in the Rouse model, which offers the simplest example of a multi-scale descriptions, if we consider differently discretized Rouse models for the same physical system. Moreover, we are able to explore different combinations of compact and non-compact diffusion in the local and large-scale dynamics by varying the embedding dimension.
The distribution of conformational disorder in the high-temperature phases of the crystalline n-alkanes

NASA Astrophysics Data System (ADS)

Maroncelli, M.; Strauss, H. L.; Snyder, R. G.

1985-03-01

The distributions of conformational defects that exist in the high-temperature phase II (also referred to as the hexagonal or rotator phase) of the crystalline n-alkanes C21 and C29 have been measured by an infrared CD2-substitution technique and have been accounted for in terms of a lattice model that provides freedom for longitudinal displacement of the chains. The defects consist almost entirely of gtg' kinks distributed nonuniformly along the chain. The uneven distribution is indicated in the variation in the concentration of gauche bonds measured at various sites along the chain. The highest concentration is at the chain ends, and the concentrations at interior sites decrease exponentially in going toward the middle. To explain the distribution we used a modification of a lattice model that had been successfully applied to the lipid bilayer. Comparison of observed distributions with those computed from the model indicates that the factors that determine the shape of the distribution are quite different in the n-alkane and bilayer cases. For the bilayer, the dominant factor is the variation in the lateral density of chains; for the n-alkane, the dominant factor is associated with longitudinal displacement of the chains.
Markov Chain Model with Catastrophe to Determine Mean Time to Default of Credit Risky Assets

NASA Astrophysics Data System (ADS)

Dharmaraja, Selvamuthu; Pasricha, Puneet; Tardelli, Paola

2017-11-01

This article deals with the problem of probabilistic prediction of the time distance to default for a firm. To model the credit risk, the dynamics of an asset is described as a function of a homogeneous discrete time Markov chain subject to a catastrophe, the default. The behaviour of the Markov chain is investigated and the mean time to the default is expressed in a closed form. The methodology to estimate the parameters is given. Numerical results are provided to illustrate the applicability of the proposed model on real data and their analysis is discussed.
On extinction time of a generalized endemic chain-binomial model.

PubMed

Aydogmus, Ozgur

2016-09-01

We considered a chain-binomial epidemic model not conferring immunity after infection. Mean field dynamics of the model has been analyzed and conditions for the existence of a stable endemic equilibrium are determined. The behavior of the chain-binomial process is probabilistically linked to the mean field equation. As a result of this link, we were able to show that the mean extinction time of the epidemic increases at least exponentially as the population size grows. We also present simulation results for the process to validate our analytical findings. Copyright © 2016 Elsevier Inc. All rights reserved.
Z n clock models and chains of so(n)2 non-Abelian anyons: symmetries, integrable points and low energy properties

NASA Astrophysics Data System (ADS)

Finch, Peter E.; Flohr, Michael; Frahm, Holger

2018-02-01

We study two families of quantum models which have been used previously to investigate the effect of topological symmetries in one-dimensional correlated matter. Various striking similarities are observed between certain {Z}n quantum clock models, spin chains generalizing the Ising model, and chains of non-Abelian anyons constructed from the so(n)2 fusion category for odd n, both subject to periodic boundary conditions. In spite of the differences between these two types of quantum chains, e.g. their Hilbert spaces being spanned by tensor products of local spin states or fusion paths of anyons, the symmetries of the lattice models are shown to be closely related. Furthermore, under a suitable mapping between the parameters describing the interaction between spins and anyons the respective Hamiltonians share part of their energy spectrum (although their degeneracies may differ). This spin-anyon correspondence can be extended by fine-tuning of the coupling constants leading to exactly solvable models. We show that the algebraic structures underlying the integrability of the clock models and the anyon chain are the same. For n = 3,5,7 we perform an extensive finite size study—both numerical and based on the exact solution—of these models to map out their ground state phase diagram and to identify the effective field theories describing their low energy behaviour. We observe that the continuum limit at the integrable points can be described by rational conformal field theories with extended symmetry algebras which can be related to the discrete ones of the lattice models.
Study of a tri-trophic prey-dependent food chain model of interacting populations.

PubMed

Haque, Mainul; Ali, Nijamuddin; Chakravarty, Santabrata

2013-11-01

The current paper accounts for the influence of intra-specific competition among predators in a prey dependent tri-trophic food chain model of interacting populations. We offer a detailed mathematical analysis of the proposed food chain model to illustrate some of the significant results that has arisen from the interplay of deterministic ecological phenomena and processes. Biologically feasible equilibria of the system are observed and the behaviours of the system around each of them are described. In particular, persistence, stability (local and global) and bifurcation (saddle-node, transcritical, Hopf-Andronov) analysis of this model are obtained. Relevant results from previous well known food chain models are compared with the current findings. Global stability analysis is also carried out by constructing appropriate Lyapunov functions. Numerical simulations show that the present system is capable enough to produce chaotic dynamics when the rate of self-interaction is very low. On the other hand such chaotic behaviour disappears for a certain value of the rate of self interaction. In addition, numerical simulations with experimented parameters values confirm the analytical results and shows that intra-specific competitions bears a potential role in controlling the chaotic dynamics of the system; and thus the role of self interactions in food chain model is illustrated first time. Finally, a discussion of the ecological applications of the analytical and numerical findings concludes the paper. Copyright © 2013 Elsevier Inc. All rights reserved.
A semiflexible alternating copolymer chain adsorption on a flat and a fluctuating surface.

PubMed

Mishra, Pramod Kumar

2010-04-21

A lattice model of a directed self-avoiding walk is used to investigate adsorption properties of a semiflexible alternating copolymer chain on an impenetrable flat and fluctuating surface in two (square, hexagonal and rectangular lattice) and three dimensions (cubic lattice). In the cubic lattice case the surface is two-dimensional impenetrable flat and in two dimensions the surface is a fluctuating impenetrable line (hexagonal lattice) and also flat impenetrable line (square and rectangular lattice). Walks of the copolymer chains are directed perpendicular to the plane of the surface and at a suitable value of monomer surface attraction, the copolymer chain gets adsorbed on the surface. To calculate the exact value of the monomer surface attraction, the directed walk model has been solved analytically using the generating function method to discuss results when one type of monomer of the copolymer chain has attractive, repulsive or no interaction with the surface. Results obtained in the flat surface case show that, for a stiffer copolymer chain, adsorption transition occurs at a smaller value of monomer surface attraction than a flexible copolymer chain while in the case of a fluctuating surface, the adsorption transition point is independent of bending energy of the copolymer chain. These features are similar to that of a semiflexible homopolymer chain adsorption.
Developing a suitable model for supplier selection based on supply chain risks: an empirical study from Iranian pharmaceutical companies.

PubMed

Mehralian, Gholamhossein; Rajabzadeh Gatari, Ali; Morakabati, Mohadese; Vatanpour, Hossein

2012-01-01

The supply chain represents the critical link between the development of new product and the market in pharmaceutical industry. Over the years, improvements made in supply chain operations have focused largely on ways to reduce cost and gain efficiencies in scale. In addition, powerful regulatory and market forces have provided new incentives for pharmaceutical firms to basically rethink the way they produce and distribute products, and also to re-imagine the role of the supply chain in driving strategic growth, brand differentiation and economic value in the health continuum. The purpose of this paper is to formulate basic factors involved in risk analysis of pharmaceutical industry, and also determine the effective factors involved in suppliers selection and their priorities. This paper is based on the results of literature review, experts' opinion acquisition, statistical analysis and also using MADM models on data gathered from distributed questionnaires. The model consists of the following steps and components: first factors involved in to supply chain risks are determined. Based on them a framework is considered. According the result of statistical analysis and MADM models the risk factors are formulated. The paper determines the main components and influenceial factors involving in the supply chain risks. Results showed that delivery risk can make an important contribution to mitigate the risk of pharmaceutical industry.
Developing a Suitable Model for Supplier Selection Based on Supply Chain Risks: An Empirical Study from Iranian Pharmaceutical Companies

PubMed Central

Mehralian, Gholamhossein; Rajabzadeh Gatari, Ali; Morakabati, Mohadese; Vatanpour, Hossein

2012-01-01

The supply chain represents the critical link between the development of new product and the market in pharmaceutical industry. Over the years, improvements made in supply chain operations have focused largely on ways to reduce cost and gain efficiencies in scale. In addition, powerful regulatory and market forces have provided new incentives for pharmaceutical firms to basically rethink the way they produce and distribute products, and also to re-imagine the role of the supply chain in driving strategic growth, brand differentiation and economic value in the health continuum. The purpose of this paper is to formulate basic factors involved in risk analysis of pharmaceutical industry, and also determine the effective factors involved in suppliers selection and their priorities. This paper is based on the results of literature review, experts’ opinion acquisition, statistical analysis and also using MADM models on data gathered from distributed questionnaires. The model consists of the following steps and components: first factors involved in to supply chain risks are determined. Based on them a framework is considered. According the result of statistical analysis and MADM models the risk factors are formulated. The paper determines the main components and influenceial factors involving in the supply chain risks. Results showed that delivery risk can make an important contribution to mitigate the risk of pharmaceutical industry. PMID:24250442
Equivalence of chain conformations in the surface region of a polymer melt and a single Gaussian chain under critical conditions.

PubMed

Skvortsov, A M; Leermakers, F A M; Fleer, G J

2013-08-07

In the melt polymer conformations are nearly ideal according to Flory's ideality hypothesis. Silberberg generalized this statement for chains in the interfacial region. We check the Silberberg argument by analyzing the conformations of a probe chain end-grafted at a solid surface in a sea of floating free chains of concentration φ by the self-consistent field (SCF) method. Apart from the grafting, probe chain and floating chains are identical. Most of the results were obtained for a standard SCF model with freely jointed chains on a six-choice lattice, where immediate step reversals are allowed. A few data were generated for a five-choice lattice, where such step reversals are forbidden. These coarse-grained models describe the equilibrium properties of flexible atactic polymer chains at the scale of the segment length. The concentration was varied over the whole range from φ = 0 (single grafted chain) to φ = 1 (probe chain in the melt). The number of contacts with the surface, average height of the free end and its dispersion, average loop and train length, tail size distribution, end-point and overall segment distributions were calculated for a grafted probe chain as a function of φ, for several chain lengths and substrate∕polymer interactions, which were varied from strong repulsion to strong adsorption. The computations show that the conformations of the probe chain in the melt do not depend on substrate∕polymer interactions and are very similar to the conformations of a single end-grafted chain under critical conditions, and can thus be described analytically. When the substrate∕polymer interaction is fixed at the value corresponding to critical conditions, all equilibrium properties of a probe chain are independent of φ, over the whole range from a dilute solution to the melt. We believe that the conformations of all flexible chains in the surface region of the melt are close to those of an appropriate single chain in critical conditions, provided that one end of the single chain is fixed at the same point as a chain in the melt.
Performance analysis of Supply Chain Management with Supply Chain Operation reference model

NASA Astrophysics Data System (ADS)

Hasibuan, Abdurrozzaq; Arfah, Mahrani; Parinduri, Luthfi; Hernawati, Tri; Suliawati; Harahap, Bonar; Rahmah Sibuea, Siti; Krianto Sulaiman, Oris; purwadi, Adi

2018-04-01

This research was conducted at PT. Shamrock Manufacturing Corpora, the company is required to think creatively to implement competition strategy by producing goods/services that are more qualified, cheaper. Therefore, it is necessary to measure the performance of Supply Chain Management in order to improve the competitiveness. Therefore, the company is required to optimize its production output to meet the export quality standard. This research begins with the creation of initial dimensions based on Supply Chain Management process, ie Plan, Source, Make, Delivery, and Return with hierarchy based on Supply Chain Reference Operation that is Reliability, Responsiveness, Agility, Cost, and Asset. Key Performance Indicator identification becomes a benchmark in performance measurement whereas Snorm De Boer normalization serves to equalize Key Performance Indicator value. Analiytical Hierarchy Process is done to assist in determining priority criteria. Measurement of Supply Chain Management performance at PT. Shamrock Manufacturing Corpora produces SC. Responsiveness (0.649) has higher weight (priority) than other alternatives. The result of performance analysis using Supply Chain Reference Operation model of Supply Chain Management performance at PT. Shamrock Manufacturing Corpora looks good because its monitoring system between 50-100 is good.
Development of an Assessment Model for Sustainable Supply Chain Management in Batik Industry

NASA Astrophysics Data System (ADS)

Mubiena, G. F.; Ma’ruf, A.

2018-03-01

This research proposes a dynamic assessment model for sustainable supply chain management in batik industry. The proposed model identifies the dynamic relationship between economic aspect, environment aspect and social aspect. The economic aspect refers to the supply chain operation reference model. The environment aspect uses carbon emissions and liquid waste as the attribute assessment, while the social aspect focus on employee’s welfare. Lean manufacturing concept was implemented as an alternative approach to sustainability. The simulation result shows that the average of sustainability score for 5 years increased from 65,3% to 70%. Future experiments will be conducted on design improvements to reach the company target on sustainability score.
An Integer Programming Model for Multi-Echelon Supply Chain Decision Problem Considering Inventories

NASA Astrophysics Data System (ADS)

Harahap, Amin; Mawengkang, Herman; Siswadi; Effendi, Syahril

2018-01-01

In this paper we address a problem that is of significance to the industry, namely the optimal decision of a multi-echelon supply chain and the associated inventory systems. By using the guaranteed service approach to model the multi-echelon inventory system, we develop a mixed integer; programming model to simultaneously optimize the transportation, inventory and network structure of a multi-echelon supply chain. To solve the model we develop a direct search approach using a strategy of releasing nonbasic variables from their bounds, combined with the “active constraint” method. This strategy is used to force the appropriate non-integer basic variables to move to their neighbourhood integer points.
Quality tracing in meat supply chains

PubMed Central

Mack, Miriam; Dittmer, Patrick; Veigt, Marius; Kus, Mehmet; Nehmiz, Ulfert; Kreyenschmidt, Judith

2014-01-01

The aim of this study was the development of a quality tracing model for vacuum-packed lamb that is applicable in different meat supply chains. Based on the development of relevant sensory parameters, the predictive model was developed by combining a linear primary model and the Arrhenius model as the secondary model. Then a process analysis was conducted to define general requirements for the implementation of the temperature-based model into a meat supply chain. The required hardware and software for continuous temperature monitoring were developed in order to use the model under practical conditions. Further on a decision support tool was elaborated in order to use the model as an effective tool in combination with the temperature monitoring equipment for the improvement of quality and storage management within the meat logistics network. Over the long term, this overall procedure will support the reduction of food waste and will improve the resources efficiency of food production. PMID:24797136
Quality tracing in meat supply chains.

PubMed

Mack, Miriam; Dittmer, Patrick; Veigt, Marius; Kus, Mehmet; Nehmiz, Ulfert; Kreyenschmidt, Judith

2014-06-13

The aim of this study was the development of a quality tracing model for vacuum-packed lamb that is applicable in different meat supply chains. Based on the development of relevant sensory parameters, the predictive model was developed by combining a linear primary model and the Arrhenius model as the secondary model. Then a process analysis was conducted to define general requirements for the implementation of the temperature-based model into a meat supply chain. The required hardware and software for continuous temperature monitoring were developed in order to use the model under practical conditions. Further on a decision support tool was elaborated in order to use the model as an effective tool in combination with the temperature monitoring equipment for the improvement of quality and storage management within the meat logistics network. Over the long term, this overall procedure will support the reduction of food waste and will improve the resources efficiency of food production.
Food-chain contamination evaluations in ecological risk assessments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Linder, G.

Food-chain models have become increasingly important within the ecological risk assessment process. This is the case particularly when acute effects are not readily apparent, or the contaminants of concern are not readily detoxified, have a high likelihood for partitioning into lipids, or have specific target organs or tissues that may increase their significance in evaluating their potential adverse effects. An overview of food-chain models -- conceptual, theoretical, and empirical -- will be considered through a series of papers that will focus on their application within the ecological risk assessment process. Whether a food-chain evaluation is being developed to address relativelymore » simple questions related to chronic effects of toxicants on target populations, or whether a more complex food-web model is being developed to address questions related to multiple-trophic level transfers of toxicants, the elements within the food chain contamination evaluation can be generalized to address the mechanisms of toxicant accumulation in individual organisms. This can then be incorporated into more elaborate models that consider these organismal-level processes within the context of a species life-history or community-level responses that may be associated with long-term exposures.« less
Study on the photo-induced oxygen reordering in YBa2Cu3O6+x

NASA Astrophysics Data System (ADS)

Milić, M. M.; Lazarov, N. Dj.; Cucić, D. A.

2012-05-01

Effect of the long term illumination of the YBa2Cu3O6+x with visible light or ultraviolet irradiation on its superconducting properties was studied in the frame of a simple theoretical model, which assumes that photodoping triggers rearrangement of oxygen monomers in the chain layers thus causing the enhancement of the average chain length, lav. Since, according to the model of charge transfer mechanism, long CuO chains are better electronic hole donors than the short ones, increase of the average chain length induces additional holes transfer from chain layers to the superconducting CuO2 planes which in turn leads to the increase of the superconducting transition temperature Tc. By the use of the expression for the chain length probability distribution and numerically calculated values for the average chain length in the non-excited system, we were able to estimate the doping p (number of holes per one Cu atom in the superconducting CuO2 planes) and Tc enhancement due to photo-induced oxygen reordering. The theoretical results are compared with available experimental data.
A Bullet-Block Experiment that Explains the Chain Fountain

NASA Astrophysics Data System (ADS)

Pantaleone, J.; Smith, R.

2018-05-01

It is common in science for two phenomena to appear to be very different, but in fact follow from the same basic principles. Here we consider such a case, the connection between the chain fountain and a bullet-block collision experiment. When an upward moving bullet strikes a wooden block resting on a horizontal table, the block will rise to a higher height when the bullet strikes near the end of the block. This is because the quickly rotating block experiences an additional upward "reaction" force from its contact with the table. Such a reaction force also explains the chain fountain. When a chain falls from a pile in a container to the floor below, the chain rises up above the container. This rise occurs because the quickly rotating links in the container push off of the surface beneath them. We derive a model that accurately describes our measurements in the bullet-block experiment, and then use this same model to calculate an approximate expression for the distance the chain rises above the container. More extensive discussions of the chain fountain are available elsewhere.
Implementation of system dynamic simulation method to optimize profit in supply chain network of vegetable product

NASA Astrophysics Data System (ADS)

Tama, I. P.; Akbar, Z.; Eunike, A.

2018-04-01

Vegetables are categorized as a perishable product, which is a product with short lifespan thus requires proper handling and planning to reduce losses caused by the short lifespan. In order to reduce the losses, coordination among the players in the supply chain is required. On the other hand, the decision in the supply chain of vegetables and other farming products in the traditional market of developing country is independent among the players. This research is conducted by using System Dynamic Simulation method to develop model and scenario by coordinating the supply quantity amongst players in the supply chain. The scenarios are developed based on newsboy inventory model. This study aims to compare scenarios combining tiers involved in coordination program. The result shows that coordination in supply chain increases total supply chain profit, although there will always be players who experienced decrements in profit. The scenario of coordination among the farmer, the distributor, and the wholesaler resulted in the highest increase in total supply chain profit compared to other coordination scenarios, with an increased value of 10.49%.
Cloud point phenomena for POE-type nonionic surfactants in a model room temperature ionic liquid.

PubMed

Inoue, Tohru; Misono, Takeshi

2008-10-15

The cloud point phenomenon has been investigated for the solutions of polyoxyethylene (POE)-type nonionic surfactants (C(12)E(5), C(12)E(6), C(12)E(7), C(10)E(6), and C(14)E(6)) in 1-butyl-3-methylimidazolium tetrafluoroborate (bmimBF(4)), a typical room temperature ionic liquid (RTIL). The cloud point, T(c), increases with the elongation of the POE chain, while decreases with the increase in the hydrocarbon chain length. This demonstrates that the solvophilicity/solvophobicity of the surfactants in RTIL comes from POE chain/hydrocarbon chain. When compared with an aqueous system, the chain length dependence of T(c) is larger for the RTIL system regarding both POE and hydrocarbon chains; in particular, hydrocarbon chain length affects T(c) much more strongly in the RTIL system than in equivalent aqueous systems. In a similar fashion to the much-studied aqueous systems, the micellar growth is also observed in this RTIL solvent as the temperature approaches T(c). The cloud point curves have been analyzed using a Flory-Huggins-type model based on phase separation in polymer solutions.

Electric vehicle (EV) storage supply chain risk and the energy market: A micro and macroeconomic risk management approach

NASA Astrophysics Data System (ADS)

Aguilar, Susanna D.

As a cost effective storage technology for renewable energy sources, Electric Vehicles can be integrated into energy grids. Integration must be optimized to ascertain that renewable energy is available through storage when demand exists so that cost of electricity is minimized. Optimization models can address economic risks associated with the EV supply chain- particularly the volatility in availability and cost of critical materials used in the manufacturing of EV motors and batteries. Supply chain risk can reflect itself in a shortage of storage, which can increase the price of electricity. We propose a micro-and macroeconomic framework for managing supply chain risk through utilization of a cost optimization model in combination with risk management strategies at the microeconomic and macroeconomic level. The study demonstrates how risk from the EVs vehicle critical material supply chain affects manufacturers, smart grid performance, and energy markets qualitatively and quantitatively. Our results illustrate how risk in the EV supply chain affects EV availability and the cost of ancillary services, and how EV critical material supply chain risk can be mitigated through managerial strategies and policy.
A decision support system for transportation infrastructure and supply chain system planning.

DOT National Transportation Integrated Search

2013-07-01

This project makes the results (models and methodology) of the research and development efforts on freight movement modeling (FMM) and supply chain design carried out by faculty at OSU and OU available to transportation and logistics professionals. A...
Cost-effectiveness analysis of an early-initiated, continuous chain of rehabilitation after severe traumatic brain injury.

PubMed

Andelic, Nada; Ye, Jiajia; Tornas, Sveinung; Roe, Cecilie; Lu, Juan; Bautz-Holter, Erik; Moger, Tron; Sigurdardottir, Solrun; Schanke, Anne-Kristine; Aas, Eline

2014-07-15

The aim of this study is to estimate the long-term cost-effectiveness of two different rehabilitation trajectories after severe traumatic brain injury (sTBI). A decision tree model compared hospitalization costs, health effects, and incremental cost-effectiveness ratios (ICER) of a continuous chain versus a broken chain of rehabilitation. The expected costs were estimated by the reimbursement system using diagnosis-related group and based on point estimates of the Disability Rating Scale (DRS); the health effects were measured by means of area under the curve (AUC). The incremental health benefit was estimated as the difference in the AUCs between the chains. Lower values on the DRS scale indicate better health; thus, smaller AUCs were preferred. The modeled population was a cohort of 59 patients with sTBI (30 in continuous chain; 29 in broken chain) with 6-weeks, 1-year, and 5-year post-injury follow-ups. Regarding the DRS estimates, 5-year AUCs were 19.40 (continuous chain) and 23.46 (broken chain). Across 5 years, the continuous chain of rehabilitation had lower costs and better health effects. By replacing the broken chain with the continuous chain, NOK 37.000 could be saved and 4.06 DRS points gained. By means of probabilistic sensitivity analysis, the majority of ICER estimates (67% of the Monte Carlo simulations) indicated that a continuous chain of rehabilitation was less costly and more effective. These findings indicate that the trajectory of continuous rehabilitation represents a dominant strategy in that it reduces costs and improves outcomes after sTBI under reasonable assumptions.
Doubly self-consistent field theory of grafted polymers under simple shear in steady state.

PubMed

Suo, Tongchuan; Whitmore, Mark D

2014-03-21

We present a generalization of the numerical self-consistent mean-field theory of polymers to the case of grafted polymers under simple shear. The general theoretical framework is presented, and then applied to three different chain models: rods, Gaussian chains, and finitely extensible nonlinear elastic (FENE) chains. The approach is self-consistent at two levels. First, for any flow field, the polymer density profile and effective potential are calculated self-consistently in a manner similar to the usual self-consistent field theory of polymers, except that the calculation is inherently two-dimensional even for a laterally homogeneous system. Second, through the use of a modified Brinkman equation, the flow field and the polymer profile are made self-consistent with respect to each other. For all chain models, we find that reasonable levels of shear cause the chains to tilt, but it has very little effect on the overall thickness of the polymer layer, causing a small decrease for rods, and an increase of no more than a few percent for the Gaussian and FENE chains. Using the FENE model, we also probe the individual bond lengths, bond correlations, and bond angles along the chains, the effects of the shear on them, and the solvent and bonded stress profiles. We find that the approximations needed within the theory for the Brinkman equation affect the bonded stress, but none of the other quantities.
Coupled ecosystem/supply chain modelling of fish products from sea to shelf: the Peruvian anchoveta case.

PubMed

Avadí, Angel; Fréon, Pierre; Tam, Jorge

2014-01-01

Sustainability assessment of food supply chains is relevant for global sustainable development. A framework is proposed for analysing fishfood (fish products for direct human consumption) supply chains with local or international scopes. It combines a material flow model (including an ecosystem dimension) of the supply chains, calculation of sustainability indicators (environmental, socio-economic, nutritional), and finally multi-criteria comparison of alternative supply chains (e.g. fates of landed fish) and future exploitation scenarios. The Peruvian anchoveta fishery is the starting point for various local and global supply chains, especially via reduction of anchoveta into fishmeal and oil, used worldwide as a key input in livestock and fish feeds. The Peruvian anchoveta supply chains are described, and the proposed methodology is used to model them. Three scenarios were explored: status quo of fish exploitation (Scenario 1), increase in anchoveta landings for food (Scenario 2), and radical decrease in total anchoveta landings to allow other fish stocks to prosper (Scenario 3). It was found that Scenario 2 provided the best balance of sustainability improvements among the three scenarios, but further refinement of the assessment is recommended. In the long term, the best opportunities for improving the environmental and socio-economic performance of Peruvian fisheries are related to sustainability-improving management and policy changes affecting the reduction industry. Our approach provides the tools and quantitative results to identify these best improvement opportunities.
Coupled Ecosystem/Supply Chain Modelling of Fish Products from Sea to Shelf: The Peruvian Anchoveta Case

PubMed Central

Avadí, Angel; Fréon, Pierre; Tam, Jorge

2014-01-01

Sustainability assessment of food supply chains is relevant for global sustainable development. A framework is proposed for analysing fishfood (fish products for direct human consumption) supply chains with local or international scopes. It combines a material flow model (including an ecosystem dimension) of the supply chains, calculation of sustainability indicators (environmental, socio-economic, nutritional), and finally multi-criteria comparison of alternative supply chains (e.g. fates of landed fish) and future exploitation scenarios. The Peruvian anchoveta fishery is the starting point for various local and global supply chains, especially via reduction of anchoveta into fishmeal and oil, used worldwide as a key input in livestock and fish feeds. The Peruvian anchoveta supply chains are described, and the proposed methodology is used to model them. Three scenarios were explored: status quo of fish exploitation (Scenario 1), increase in anchoveta landings for food (Scenario 2), and radical decrease in total anchoveta landings to allow other fish stocks to prosper (Scenario 3). It was found that Scenario 2 provided the best balance of sustainability improvements among the three scenarios, but further refinement of the assessment is recommended. In the long term, the best opportunities for improving the environmental and socio-economic performance of Peruvian fisheries are related to sustainability-improving management and policy changes affecting the reduction industry. Our approach provides the tools and quantitative results to identify these best improvement opportunities. PMID:25003196
A Decision Model for Steady-State Choice in Concurrent Chains

ERIC Educational Resources Information Center

Christensen, Darren R.; Grace, Randolph C.

2010-01-01

Grace and McLean (2006) proposed a decision model for acquisition of choice in concurrent chains which assumes that after reinforcement in a terminal link, subjects make a discrimination whether the preceding reinforcer delay was short or long relative to a criterion. Their model was subsequently extended by Christensen and Grace (2008, 2009a,…
Recovery of Graded Response Model Parameters: A Comparison of Marginal Maximum Likelihood and Markov Chain Monte Carlo Estimation

ERIC Educational Resources Information Center

Kieftenbeld, Vincent; Natesan, Prathiba

2012-01-01

Markov chain Monte Carlo (MCMC) methods enable a fully Bayesian approach to parameter estimation of item response models. In this simulation study, the authors compared the recovery of graded response model parameters using marginal maximum likelihood (MML) and Gibbs sampling (MCMC) under various latent trait distributions, test lengths, and…
Chain Assembly and Disassembly Processes Differently Affect the Conformational Space of Ubiquitin Chains.

PubMed

Kniss, Andreas; Schuetz, Denise; Kazemi, Sina; Pluska, Lukas; Spindler, Philipp E; Rogov, Vladimir V; Husnjak, Koraljka; Dikic, Ivan; Güntert, Peter; Sommer, Thomas; Prisner, Thomas F; Dötsch, Volker

2018-02-06

Ubiquitination is the most versatile posttranslational modification. The information is encoded by linkage type as well as chain length, which are translated by ubiquitin binding domains into specific signaling events. Chain topology determines the conformational space of a ubiquitin chain and adds an additional regulatory layer to this ubiquitin code. In particular, processes that modify chain length will be affected by chain conformations as they require access to the elongation or cleavage sites. We investigated conformational distributions in the context of chain elongation and disassembly using pulsed electron-electron double resonance spectroscopy in combination with molecular modeling. Analysis of the conformational space of diubiquitin revealed conformational selection or remodeling as mechanisms for chain recognition during elongation or hydrolysis, respectively. Chain elongation to tetraubiquitin increases the sampled conformational space, suggesting that a high intrinsic flexibility of K48-linked chains may contribute to efficient proteasomal degradation. Copyright © 2017 Elsevier Ltd. All rights reserved.
The neural dynamics of song syntax in songbirds

NASA Astrophysics Data System (ADS)

Jin, Dezhe

2010-03-01

Songbird is ``the hydrogen atom'' of the neuroscience of complex, learned vocalizations such as human speech. Songs of Bengalese finch consist of sequences of syllables. While syllables are temporally stereotypical, syllable sequences can vary and follow complex, probabilistic syntactic rules, which are rudimentarily similar to grammars in human language. Songbird brain is accessible to experimental probes, and is understood well enough to construct biologically constrained, predictive computational models. In this talk, I will discuss the structure and dynamics of neural networks underlying the stereotypy of the birdsong syllables and the flexibility of syllable sequences. Recent experiments and computational models suggest that a syllable is encoded in a chain network of projection neurons in premotor nucleus HVC (proper name). Precisely timed spikes propagate along the chain, driving vocalization of the syllable through downstream nuclei. Through a computational model, I show that that variable syllable sequences can be generated through spike propagations in a network in HVC in which the syllable-encoding chain networks are connected into a branching chain pattern. The neurons mutually inhibit each other through the inhibitory HVC interneurons, and are driven by external inputs from nuclei upstream of HVC. At a branching point that connects the final group of a chain to the first groups of several chains, the spike activity selects one branch to continue the propagation. The selection is probabilistic, and is due to the winner-take-all mechanism mediated by the inhibition and noise. The model predicts that the syllable sequences statistically follow partially observable Markov models. Experimental results supporting this and other predictions of the model will be presented. We suggest that the syntax of birdsong syllable sequences is embedded in the connection patterns of HVC projection neurons.
Transitions of tethered chain molecules under tension.

PubMed

Luettmer-Strathmann, Jutta; Binder, Kurt

2014-09-21

An applied tension force changes the equilibrium conformations of a polymer chain tethered to a planar substrate and thus affects the adsorption transition as well as the coil-globule and crystallization transitions. Conversely, solvent quality and surface attraction are reflected in equilibrium force-extension curves that can be measured in experiments. To investigate these effects theoretically, we study tethered chains under tension with Wang-Landau simulations of a bond-fluctuation lattice model. Applying our model to pulling experiments on biological molecules we obtain a good description of experimental data in the intermediate force range, where universal features dominate and finite size effects are small. For tethered chains in poor solvent, we observe the predicted two-phase coexistence at transitions from the globule to stretched conformations and also discover direct transitions from crystalline to stretched conformations. A phase portrait for finite chains constructed by evaluating the density of states for a broad range of solvent conditions and tensions shows how increasing tension leads to a disappearance of the globular phase. For chains in good solvents tethered to hard and attractive surfaces we find the predicted scaling with the chain length in the low-force regime and show that our results are well described by an analytical, independent-bond approximation for the bond-fluctuation model for the highest tensions. Finally, for a hard or slightly attractive surface the stretching of a tethered chain is a conformational change that does not correspond to a phase transition. However, when the surface attraction is sufficient to adsorb a chain it will undergo a desorption transition at a critical value of the applied force. Our results for force-induced desorption show the transition to be discontinuous with partially desorbed conformations in the coexistence region.
Fitmunk: improving protein structures by accurate, automatic modeling of side-chain conformations.

PubMed

Porebski, Przemyslaw Jerzy; Cymborowski, Marcin; Pasenkiewicz-Gierula, Marta; Minor, Wladek

2016-02-01

Improvements in crystallographic hardware and software have allowed automated structure-solution pipelines to approach a near-`one-click' experience for the initial determination of macromolecular structures. However, in many cases the resulting initial model requires a laborious, iterative process of refinement and validation. A new method has been developed for the automatic modeling of side-chain conformations that takes advantage of rotamer-prediction methods in a crystallographic context. The algorithm, which is based on deterministic dead-end elimination (DEE) theory, uses new dense conformer libraries and a hybrid energy function derived from experimental data and prior information about rotamer frequencies to find the optimal conformation of each side chain. In contrast to existing methods, which incorporate the electron-density term into protein-modeling frameworks, the proposed algorithm is designed to take advantage of the highly discriminatory nature of electron-density maps. This method has been implemented in the program Fitmunk, which uses extensive conformational sampling. This improves the accuracy of the modeling and makes it a versatile tool for crystallographic model building, refinement and validation. Fitmunk was extensively tested on over 115 new structures, as well as a subset of 1100 structures from the PDB. It is demonstrated that the ability of Fitmunk to model more than 95% of side chains accurately is beneficial for improving the quality of crystallographic protein models, especially at medium and low resolutions. Fitmunk can be used for model validation of existing structures and as a tool to assess whether side chains are modeled optimally or could be better fitted into electron density. Fitmunk is available as a web service at http://kniahini.med.virginia.edu/fitmunk/server/ or at http://fitmunk.bitbucket.org/.
Template based protein structure modeling by global optimization in CASP11.

PubMed

Joo, Keehyoung; Joung, InSuk; Lee, Sun Young; Kim, Jong Yun; Cheng, Qianyi; Manavalan, Balachandran; Joung, Jong Young; Heo, Seungryong; Lee, Juyong; Nam, Mikyung; Lee, In-Ho; Lee, Sung Jong; Lee, Jooyoung

2016-09-01

For the template-based modeling (TBM) of CASP11 targets, we have developed three new protein modeling protocols (nns for server prediction and LEE and LEER for human prediction) by improving upon our previous CASP protocols (CASP7 through CASP10). We applied the powerful global optimization method of conformational space annealing to three stages of optimization, including multiple sequence-structure alignment, three-dimensional (3D) chain building, and side-chain remodeling. For more successful fold recognition, a new alignment method called CRFalign was developed. It can incorporate sensitive positional and environmental dependence in alignment scores as well as strong nonlinear correlations among various features. Modifications and adjustments were made to the form of the energy function and weight parameters pertaining to the chain building procedure. For the side-chain remodeling step, residue-type dependence was introduced to the cutoff value that determines the entry of a rotamer to the side-chain modeling library. The improved performance of the nns server method is attributed to successful fold recognition achieved by combining several methods including CRFalign and to the current modeling formulation that can incorporate native-like structural aspects present in multiple templates. The LEE protocol is identical to the nns one except that CASP11-released server models are used as templates. The success of LEE in utilizing CASP11 server models indicates that proper template screening and template clustering assisted by appropriate cluster ranking promises a new direction to enhance protein 3D modeling. Proteins 2016; 84(Suppl 1):221-232. © 2015 Wiley Periodicals, Inc. © 2015 Wiley Periodicals, Inc.
The Buccaneer software for automated model building. 1. Tracing protein chains.

PubMed

Cowtan, Kevin

2006-09-01

A new technique for the automated tracing of protein chains in experimental electron-density maps is described. The technique relies on the repeated application of an oriented electron-density likelihood target function to identify likely C(alpha) positions. This function is applied both in the location of a few promising ;seed' positions in the map and to grow those initial C(alpha) positions into extended chain fragments. Techniques for assembling the chain fragments into an initial chain trace are discussed.
Metastates in Mean-Field Models with Random External Fields Generated by Markov Chains

NASA Astrophysics Data System (ADS)

Formentin, M.; Külske, C.; Reichenbachs, A.

2012-01-01

We extend the construction by Külske and Iacobelli of metastates in finite-state mean-field models in independent disorder to situations where the local disorder terms are a sample of an external ergodic Markov chain in equilibrium. We show that for non-degenerate Markov chains, the structure of the theorems is analogous to the case of i.i.d. variables when the limiting weights in the metastate are expressed with the aid of a CLT for the occupation time measure of the chain. As a new phenomenon we also show in a Potts example that for a degenerate non-reversible chain this CLT approximation is not enough, and that the metastate can have less symmetry than the symmetry of the interaction and a Gaussian approximation of disorder fluctuations would suggest.
Buffering effect in continuous chains of unidirectionally coupled generators

NASA Astrophysics Data System (ADS)

Glyzin, S. D.; Kolesov, A. Yu.; Rozov, N. Kh.

2014-11-01

We propose a mathematical model of a continuous annular chain of unidirectionally coupled generators given by some nonlinear advection-type hyperbolic boundary value problem. Such problems are constructed by a limit transition from annular chains of unidirectionally coupled ordinary differential equations with an unbounded increase in the number of links. We find that a certain buffering phenomenon is realized in our boundary value problem. Namely, we show that any preassigned finite number of stable periodic motions of the traveling-wave type can coexist in the model.
Technical manual for basic version of the Markov chain nest productivity model (MCnest)

EPA Science Inventory

The Markov Chain Nest Productivity Model (or MCnest) integrates existing toxicity information from three standardized avian toxicity tests with information on species life history and the timing of pesticide applications relative to the timing of avian breeding seasons to quantit...
User’s manual for basic version of MCnest Markov chain nest productivity model

EPA Science Inventory

The Markov Chain Nest Productivity Model (or MCnest) integrates existing toxicity information from three standardized avian toxicity tests with information on species life history and the timing of pesticide applications relative to the timing of avian breeding seasons to quantit...
A simplified parsimonious higher order multivariate Markov chain model with new convergence condition

NASA Astrophysics Data System (ADS)

Wang, Chao; Yang, Chuan-sheng

2017-09-01

In this paper, we present a simplified parsimonious higher-order multivariate Markov chain model with new convergence condition. (TPHOMMCM-NCC). Moreover, estimation method of the parameters in TPHOMMCM-NCC is give. Numerical experiments illustrate the effectiveness of TPHOMMCM-NCC.
Decision on risk-averse dual-channel supply chain under demand disruption

NASA Astrophysics Data System (ADS)

Yan, Bo; Jin, Zijie; Liu, Yanping; Yang, Jianbo

2018-02-01

We studied dual-channel supply chains using centralized and decentralized decision-making models. We also conducted a comparative analysis of the decisions before and after demand disruption. The study shows that the amount of change in decision-making is a linear function of the amount of demand disruption, and it is independent of the risk-averse coefficient. The optimal sales volume decision of the disturbing supply chain is related to market share and demand disruption in the decentralized decision-making model. The optimal decision is only influenced by demand disruption in the centralized decision-making model. The stability of the sales volume of the two models is related to market share and demand disruption. The optimal system production of the two models shows robustness, but their stable internals are different.

Inferring Markov chains: Bayesian estimation, model comparison, entropy rate, and out-of-class modeling.

PubMed

Strelioff, Christopher C; Crutchfield, James P; Hübler, Alfred W

2007-07-01

Markov chains are a natural and well understood tool for describing one-dimensional patterns in time or space. We show how to infer kth order Markov chains, for arbitrary k , from finite data by applying Bayesian methods to both parameter estimation and model-order selection. Extending existing results for multinomial models of discrete data, we connect inference to statistical mechanics through information-theoretic (type theory) techniques. We establish a direct relationship between Bayesian evidence and the partition function which allows for straightforward calculation of the expectation and variance of the conditional relative entropy and the source entropy rate. Finally, we introduce a method that uses finite data-size scaling with model-order comparison to infer the structure of out-of-class processes.
Comparing the locking threshold for rings and chains of oscillators.

PubMed

Ottino-Löffler, Bertrand; Strogatz, Steven H

2016-12-01

We present a case study of how topology can affect synchronization. Specifically, we consider arrays of phase oscillators coupled in a ring or a chain topology. Each ring is perfectly matched to a chain with the same initial conditions and the same random natural frequencies. The only difference is their boundary conditions: periodic for a ring and open for a chain. For both topologies, stable phase-locked states exist if and only if the spread or "width" of the natural frequencies is smaller than a critical value called the locking threshold (which depends on the boundary conditions and the particular realization of the frequencies). The central question is whether a ring synchronizes more readily than a chain. We show that it usually does, but not always. Rigorous bounds are derived for the ratio between the locking thresholds of a ring and its matched chain, for a variant of the Kuramoto model that also includes a wider family of models.
Comparing the locking threshold for rings and chains of oscillators

NASA Astrophysics Data System (ADS)

Ottino-Löffler, Bertrand; Strogatz, Steven H.

2016-12-01

We present a case study of how topology can affect synchronization. Specifically, we consider arrays of phase oscillators coupled in a ring or a chain topology. Each ring is perfectly matched to a chain with the same initial conditions and the same random natural frequencies. The only difference is their boundary conditions: periodic for a ring and open for a chain. For both topologies, stable phase-locked states exist if and only if the spread or "width" of the natural frequencies is smaller than a critical value called the locking threshold (which depends on the boundary conditions and the particular realization of the frequencies). The central question is whether a ring synchronizes more readily than a chain. We show that it usually does, but not always. Rigorous bounds are derived for the ratio between the locking thresholds of a ring and its matched chain, for a variant of the Kuramoto model that also includes a wider family of models.
ChainMail based neural dynamics modeling of soft tissue deformation for surgical simulation.

PubMed

Zhang, Jinao; Zhong, Yongmin; Smith, Julian; Gu, Chengfan

2017-07-20

Realistic and real-time modeling and simulation of soft tissue deformation is a fundamental research issue in the field of surgical simulation. In this paper, a novel cellular neural network approach is presented for modeling and simulation of soft tissue deformation by combining neural dynamics of cellular neural network with ChainMail mechanism. The proposed method formulates the problem of elastic deformation into cellular neural network activities to avoid the complex computation of elasticity. The local position adjustments of ChainMail are incorporated into the cellular neural network as the local connectivity of cells, through which the dynamic behaviors of soft tissue deformation are transformed into the neural dynamics of cellular neural network. Experiments demonstrate that the proposed neural network approach is capable of modeling the soft tissues' nonlinear deformation and typical mechanical behaviors. The proposed method not only improves ChainMail's linear deformation with the nonlinear characteristics of neural dynamics but also enables the cellular neural network to follow the principle of continuum mechanics to simulate soft tissue deformation.
Dynamic modeling and optimal joint torque coordination of advanced robotic systems

NASA Astrophysics Data System (ADS)

Kang, Hee-Jun

The development is documented of an efficient dynamic modeling algorithm and the subsequent optimal joint input load coordination of advanced robotic systems for industrial application. A closed-form dynamic modeling algorithm for the general closed-chain robotic linkage systems is presented. The algorithm is based on the transfer of system dependence from a set of open chain Lagrangian coordinates to any desired system generalized coordinate set of the closed-chain. Three different techniques for evaluation of the kinematic closed chain constraints allow the representation of the dynamic modeling parameters in terms of system generalized coordinates and have no restriction with regard to kinematic redundancy. The total computational requirement of the closed-chain system model is largely dependent on the computation required for the dynamic model of an open kinematic chain. In order to improve computational efficiency, modification of an existing open-chain KIC based dynamic formulation is made by the introduction of the generalized augmented body concept. This algorithm allows a 44 pct. computational saving over the current optimized one (O(N4), 5995 when N = 6). As means of resolving redundancies in advanced robotic systems, local joint torque optimization is applied for effectively using actuator power while avoiding joint torque limits. The stability problem in local joint torque optimization schemes is eliminated by using fictitious dissipating forces which act in the necessary null space. The performance index representing the global torque norm is shown to be satisfactory. In addition, the resulting joint motion trajectory becomes conservative, after a transient stage, for repetitive cyclic end-effector trajectories. The effectiveness of the null space damping method is shown. The modular robot, which is built of well defined structural modules from a finite-size inventory and is controlled by one general computer system, is another class of evolving, highly versatile, advanced robotic systems. Therefore, finally, a module based dynamic modeling algorithm is presented for the dynamic coordination of such reconfigurable modular robotic systems. A user interactive module based manipulator analysis program (MBMAP) has been coded in C language running on 4D/70 Silicon Graphics.
Transportation and dynamic networks: Models, theory, and applications to supply chains, electric power, and financial networks

NASA Astrophysics Data System (ADS)

Liu, Zugang

Network systems, including transportation and logistic systems, electric power generation and distribution networks as well as financial networks, provide the critical infrastructure for the functioning of our societies and economies. The understanding of the dynamic behavior of such systems is also crucial to national security and prosperity. The identification of new connections between distinct network systems is the inspiration for the research in this dissertation. In particular, I answer two questions raised by Beckmann, McGuire, and Winsten (1956) and Copeland (1952) over half a century ago, which are, respectively, how are electric power flows related to transportation flows and does money flow like water or electricity? In addition, in this dissertation, I achieve the following: (1) I establish the relationships between transportation networks and three other classes of complex network systems: supply chain networks, electric power generation and transmission networks, and financial networks with intermediation. The establishment of such connections provides novel theoretical insights as well as new pricing mechanisms, and efficient computational methods. (2) I develop new modeling frameworks based on evolutionary variational inequality theory that capture the dynamics of such network systems in terms of the time-varying flows and incurred costs, prices, and, where applicable, profits. This dissertation studies the dynamics of such network systems by addressing both internal competition and/or cooperation, and external changes, such as varying costs and demands. (3) I focus, in depth, on electric power supply chains. By exploiting the relationships between transportation networks and electric power supply chains, I develop a large-scale network model that integrates electric power supply chains and fuel supply markets. The model captures both the economic transactions as well as the physical transmission constraints. The model is then applied to the New England electric power supply chain consisting of 6 states, 5 fuel types, 82 power generators, with a total of 573 generating units, and 10 demand markets. The empirical case study demonstrates that the regional electricity prices simulated by the model match very well the actual electricity prices in New England. I also utilize the model to study interactions between electric power supply chains and energy fuel markets.
Markov Chain Models for Stochastic Behavior in Resonance Overlap Regions

NASA Astrophysics Data System (ADS)

McCarthy, Morgan; Quillen, Alice

2018-01-01

We aim to predict lifetimes of particles in chaotic zoneswhere resonances overlap. A continuous-time Markov chain model isconstructed using mean motion resonance libration timescales toestimate transition times between resonances. The model is applied todiffusion in the co-rotation region of a planet. For particles begunat low eccentricity, the model is effective for early diffusion, butnot at later time when particles experience close encounters to the planet.
Estimating the Fully Burdened Cost of Fuel Using an Input-Output Model - A Micro-Level Analysis

DTIC Science & Technology

2011-09-01

The multilocation distribution model used by Lu and Rencheng to evaluate an international supply chain (From: Lu & Rencheng, 2007...IO model to evaluate an international supply chain specifically for a multilocation production system. Figure 2 illustrates such a system. vendor...vendor vendor Target markets Production plants Material vendor Figure 2. The multilocation distribution model used by Lu and Rencheng to
Dynamic Models and Coordination Analysis of Reverse Supply Chain with Remanufacturing

NASA Astrophysics Data System (ADS)

Yan, Nina

In this paper, we establish a reverse chain system with one manufacturer and one retailer under demand uncertainties. Distinguishing between the recycling process of the retailer and the remanufacturing process of the manufacturer, we formulate a two-stage dynamic model for reverse supply chain based on remanufacturing. Using buyback contract as coordination mechanism and applying dynamic programming the optimal decision problems for each stage are analyzed. It concluded that the reverse supply chain system could be coordinated under the given condition. Finally, we carry out numerical calculations to analyze the expected profits for the manufacturer and the retailer under different recovery rates and recovery prices and the outcomes validate the theoretical analyses.
FAST TRACK COMMUNICATION: Exact and simple results for the XYZ and strongly interacting fermion chains

NASA Astrophysics Data System (ADS)

Fendley, Paul; Hagendorf, Christian

2010-10-01

We conjecture exact and simple formulas for some physical quantities in two quantum chains. A classic result of this type is Onsager, Kaufman and Yang's formula for the spontaneous magnetization in the Ising model, subsequently generalized to the chiral Potts models. We conjecture that analogous results occur in the XYZ chain when the couplings obey JxJy + JyJz + JxJz = 0, and in a related fermion chain with strong interactions and supersymmetry. We find exact formulas for the magnetization and gap in the former, and the staggered density in the latter, by exploiting the fact that certain quantities are independent of finite-size effects.
Folding and trimerization of clathrin subunits at the triskelion hub.

PubMed

Näthke, I S; Heuser, J; Lupas, A; Stock, J; Turck, C W; Brodsky, F M

1992-03-06

The triskelion shape of the clathrin molecule enables it to form the polyhedral protein network that covers clathrin-coated pits and vesicles. Domains within the clathrin heavy chain that are responsible for maintaining triskelion shape and function were identified and localized. Sequences that mediate trimerization are distal to the carboxyl terminus and are adjacent to a domain that mediates both light chain binding and clathrin assembly. Structural modeling predicts that within this domain, the region of heavy chain-light chain interaction is a bundle of three or four alpha helices. These studies establish a low resolution model of clathrin subunit folding in the central portion (hub) of the triskelion, thus providing a basis for future mutagenesis experiments.
Evaluating opportunities to improve material and energy impacts in commodity supply chains

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hanes, Rebecca J.; Carpenter, Alberta

When evaluated at the scale of individual processes, next-generation technologies may be more energy and emissions intensive than current technology. Furthermore, many advanced technologies have the potential to reduce material and energy consumption in upstream or downstream processing stages. In order to fully understand the benefits and consequences of technology deployment, next-generation technologies should be evaluated in context, as part of a supply chain. This work presents the Materials Flow through Industry (MFI) supply chain modeling tool. The MFI tool is a cradle-to-gate linear network model of the US industrial sector that can model a wide range of manufacturing scenarios,more » including changes in production technology and increases in industrial energy efficiency. The MFI tool was developed to perform supply chain scale analyses in order to quantify the impacts and benefits of next-generation technologies and materials at that scale. For the analysis presented in this paper, the MFI tool is utilized to explore a case study comparing three lightweight vehicle supply chains to the supply chain of a conventional, standard weight vehicle. Several of the lightweight vehicle supply chains are evaluated under manufacturing scenarios that include next-generation production technologies and next-generation materials. Results indicate that producing lightweight vehicles is more energy and emission intensive than producing the non-lightweight vehicle, but the fuel saved during vehicle use offsets this increase. In this case study, greater reductions in supply chain energy and emissions were achieved through the application of the next-generation technologies than from application of energy efficiency increases.« less
Time Evolving Fission Chain Theory and Fast Neutron and Gamma-Ray Counting Distributions

DOE PAGES

Kim, K. S.; Nakae, L. F.; Prasad, M. K.; ...

2015-11-01

Here, we solve a simple theoretical model of time evolving fission chains due to Feynman that generalizes and asymptotically approaches the point model theory. The point model theory has been used to analyze thermal neutron counting data. This extension of the theory underlies fast counting data for both neutrons and gamma rays from metal systems. Fast neutron and gamma-ray counting is now possible using liquid scintillator arrays with nanosecond time resolution. For individual fission chains, the differential equations describing three correlated probability distributions are solved: the time-dependent internal neutron population, accumulation of fissions in time, and accumulation of leaked neutronsmore » in time. Explicit analytic formulas are given for correlated moments of the time evolving chain populations. The equations for random time gate fast neutron and gamma-ray counting distributions, due to randomly initiated chains, are presented. Correlated moment equations are given for both random time gate and triggered time gate counting. There are explicit formulas for all correlated moments are given up to triple order, for all combinations of correlated fast neutrons and gamma rays. The nonlinear differential equations for probabilities for time dependent fission chain populations have a remarkably simple Monte Carlo realization. A Monte Carlo code was developed for this theory and is shown to statistically realize the solutions to the fission chain theory probability distributions. Combined with random initiation of chains and detection of external quanta, the Monte Carlo code generates time tagged data for neutron and gamma-ray counting and from these data the counting distributions.« less
Evaluating opportunities to improve material and energy impacts in commodity supply chains

DOE PAGES

Hanes, Rebecca J.; Carpenter, Alberta

2017-01-10

When evaluated at the scale of individual processes, next-generation technologies may be more energy and emissions intensive than current technology. Furthermore, many advanced technologies have the potential to reduce material and energy consumption in upstream or downstream processing stages. In order to fully understand the benefits and consequences of technology deployment, next-generation technologies should be evaluated in context, as part of a supply chain. This work presents the Materials Flow through Industry (MFI) supply chain modeling tool. The MFI tool is a cradle-to-gate linear network model of the US industrial sector that can model a wide range of manufacturing scenarios,more » including changes in production technology and increases in industrial energy efficiency. The MFI tool was developed to perform supply chain scale analyses in order to quantify the impacts and benefits of next-generation technologies and materials at that scale. For the analysis presented in this paper, the MFI tool is utilized to explore a case study comparing three lightweight vehicle supply chains to the supply chain of a conventional, standard weight vehicle. Several of the lightweight vehicle supply chains are evaluated under manufacturing scenarios that include next-generation production technologies and next-generation materials. Results indicate that producing lightweight vehicles is more energy and emission intensive than producing the non-lightweight vehicle, but the fuel saved during vehicle use offsets this increase. In this case study, greater reductions in supply chain energy and emissions were achieved through the application of the next-generation technologies than from application of energy efficiency increases.« less
Building Quantitative Hydrologic Storylines from Process-based Models for Managing Water Resources in the U.S. Under Climate-changed Futures

NASA Astrophysics Data System (ADS)

Arnold, J.; Gutmann, E. D.; Clark, M. P.; Nijssen, B.; Vano, J. A.; Addor, N.; Wood, A.; Newman, A. J.; Mizukami, N.; Brekke, L. D.; Rasmussen, R.; Mendoza, P. A.

2016-12-01

Climate change narratives for water-resource applications must represent the change signals contextualized by hydroclimatic process variability and uncertainty at multiple scales. Building narratives of plausible change includes assessing uncertainties across GCM structure, internal climate variability, climate downscaling methods, and hydrologic models. Work with this linked modeling chain has dealt mostly with GCM sampling directed separately to either model fidelity (does the model correctly reproduce the physical processes in the world?) or sensitivity (of different model responses to CO2 forcings) or diversity (of model type, structure, and complexity). This leaves unaddressed any interactions among those measures and with other components in the modeling chain used to identify water-resource vulnerabilities to specific climate threats. However, time-sensitive, real-world vulnerability studies typically cannot accommodate a full uncertainty ensemble across the whole modeling chain, so a gap has opened between current scientific knowledge and most routine applications for climate-changed hydrology. To close that gap, the US Army Corps of Engineers, the Bureau of Reclamation, and the National Center for Atmospheric Research are working on techniques to subsample uncertainties objectively across modeling chain components and to integrate results into quantitative hydrologic storylines of climate-changed futures. Importantly, these quantitative storylines are not drawn from a small sample of models or components. Rather, they stem from the more comprehensive characterization of the full uncertainty space for each component. Equally important from the perspective of water-resource practitioners, these quantitative hydrologic storylines are anchored in actual design and operations decisions potentially affected by climate change. This talk will describe part of our work characterizing variability and uncertainty across modeling chain components and their interactions using newly developed observational data, models and model outputs, and post-processing tools for making the resulting quantitative storylines most useful in practical hydrology applications.
Markov chains and semi-Markov models in time-to-event analysis.

PubMed

Abner, Erin L; Charnigo, Richard J; Kryscio, Richard J

2013-10-25

A variety of statistical methods are available to investigators for analysis of time-to-event data, often referred to as survival analysis. Kaplan-Meier estimation and Cox proportional hazards regression are commonly employed tools but are not appropriate for all studies, particularly in the presence of competing risks and when multiple or recurrent outcomes are of interest. Markov chain models can accommodate censored data, competing risks (informative censoring), multiple outcomes, recurrent outcomes, frailty, and non-constant survival probabilities. Markov chain models, though often overlooked by investigators in time-to-event analysis, have long been used in clinical studies and have widespread application in other fields.
Markov chains and semi-Markov models in time-to-event analysis

PubMed Central

Abner, Erin L.; Charnigo, Richard J.; Kryscio, Richard J.

2014-01-01

A variety of statistical methods are available to investigators for analysis of time-to-event data, often referred to as survival analysis. Kaplan-Meier estimation and Cox proportional hazards regression are commonly employed tools but are not appropriate for all studies, particularly in the presence of competing risks and when multiple or recurrent outcomes are of interest. Markov chain models can accommodate censored data, competing risks (informative censoring), multiple outcomes, recurrent outcomes, frailty, and non-constant survival probabilities. Markov chain models, though often overlooked by investigators in time-to-event analysis, have long been used in clinical studies and have widespread application in other fields. PMID:24818062
Quantitative microbial risk assessment for Escherichia coli O157:H7, Salmonella enterica, and Listeria monocytogenes in leafy green vegetables consumed at salad bars, based on modeling supply chain logistics.

PubMed

Tromp, S O; Rijgersberg, H; Franz, E

2010-10-01

Quantitative microbial risk assessments do not usually account for the planning and ordering mechanisms (logistics) of a food supply chain. These mechanisms and consumer demand determine the storage and delay times of products. The aim of this study was to quantitatively assess the difference between simulating supply chain logistics (MOD) and assuming fixed storage times (FIX) in microbial risk estimation for the supply chain of fresh-cut leafy green vegetables destined for working-canteen salad bars. The results of the FIX model were previously published (E. Franz, S. O. Tromp, H. Rijgersberg, and H. J. van der Fels-Klerx, J. Food Prot. 73:274-285, 2010). Pathogen growth was modeled using stochastic discrete-event simulation of the applied logistics concept. The public health effects were assessed by conducting an exposure assessment and risk characterization. The relative growths of Escherichia coli O157 (17%) and Salmonella enterica (15%) were identical in the MOD and FIX models. In contrast, the relative growth of Listeria monocytogenes was considerably higher in the MOD model (1,156%) than in the FIX model (194%). The probability of L. monocytogenes infection in The Netherlands was higher in the MOD model (5.18×10(-8)) than in the FIX model (1.23×10(-8)). The risk of listeriosis-induced fetal mortality in the perinatal population increased from 1.24×10(-4) (FIX) to 1.66×10(-4) (MOD). Modeling the probabilistic nature of supply chain logistics is of additional value for microbial risk assessments regarding psychrotrophic pathogens in food products for which time and temperature are the postharvest preventive measures in guaranteeing food safety.
Optimization of Location–Routing Problem for Cold Chain Logistics Considering Carbon Footprint

PubMed Central

Wang, Songyi; Tao, Fengming; Shi, Yuhe

2018-01-01

In order to solve the optimization problem of logistics distribution system for fresh food, this paper provides a low-carbon and environmental protection point of view, based on the characteristics of perishable products, and combines with the overall optimization idea of cold chain logistics distribution network, where the green and low-carbon location–routing problem (LRP) model in cold chain logistics is developed with the minimum total costs as the objective function, which includes carbon emission costs. A hybrid genetic algorithm with heuristic rules is designed to solve the model, and an example is used to verify the effectiveness of the algorithm. Furthermore, the simulation results obtained by a practical numerical example show the applicability of the model while provide green and environmentally friendly location-distribution schemes for the cold chain logistics enterprise. Finally, carbon tax policies are introduced to analyze the impact of carbon tax on the total costs and carbon emissions, which proves that carbon tax policy can effectively reduce carbon dioxide emissions in cold chain logistics network. PMID:29316639
Triphasic spike-timing-dependent plasticity organizes networks to produce robust sequences of neural activity

PubMed Central

Waddington, Amelia; Appleby, Peter A.; De Kamps, Marc; Cohen, Netta

2012-01-01

Synfire chains have long been proposed to generate precisely timed sequences of neural activity. Such activity has been linked to numerous neural functions including sensory encoding, cognitive and motor responses. In particular, it has been argued that synfire chains underlie the precise spatiotemporal firing patterns that control song production in a variety of songbirds. Previous studies have suggested that the development of synfire chains requires either initial sparse connectivity or strong topological constraints, in addition to any synaptic learning rules. Here, we show that this necessity can be removed by using a previously reported but hitherto unconsidered spike-timing-dependent plasticity (STDP) rule and activity-dependent excitability. Under this rule the network develops stable synfire chains that possess a non-trivial, scalable multi-layer structure, in which relative layer sizes appear to follow a universal function. Using computational modeling and a coarse grained random walk model, we demonstrate the role of the STDP rule in growing, molding and stabilizing the chain, and link model parameters to the resulting structure. PMID:23162457

Life cycle cost optimization of biofuel supply chains under uncertainties based on interval linear programming.

PubMed

Ren, Jingzheng; Dong, Liang; Sun, Lu; Goodsite, Michael Evan; Tan, Shiyu; Dong, Lichun

2015-01-01

The aim of this work was to develop a model for optimizing the life cycle cost of biofuel supply chain under uncertainties. Multiple agriculture zones, multiple transportation modes for the transport of grain and biofuel, multiple biofuel plants, and multiple market centers were considered in this model, and the price of the resources, the yield of grain and the market demands were regarded as interval numbers instead of constants. An interval linear programming was developed, and a method for solving interval linear programming was presented. An illustrative case was studied by the proposed model, and the results showed that the proposed model is feasible for designing biofuel supply chain under uncertainties. Copyright © 2015 Elsevier Ltd. All rights reserved.
Translational Dielectric Friction on a Chain of Charged Spheres

PubMed Central

Boughammoura, Sondès; M'halla, Jalel

2014-01-01

We have proved in details that the dielectric friction remains the principal frictional effect for a stretched polyion modeled as a chain of charged spheres, whereas, in the case of Manning's model (infinite thread with a continuous distribution of charge), this friction effect is nonexistent. According to this chain model, it is therefore possible to detect by conductivity measurements any transition from a coiled configuration (ellipsoidal model) to a stretched configuration during dilution process. We have also underlined the important interdependence between the dielectric friction and the ionic condensation of the counterions, in order to distinguish between the Ostwald regime and the Manning regime for which the degree of condensation is practically constant in a large range of concentrations. PMID:24672333
A big-data model for multi-modal public transportation with application to macroscopic control and optimisation

NASA Astrophysics Data System (ADS)

Faizrahnemoon, Mahsa; Schlote, Arieh; Maggi, Lorenzo; Crisostomi, Emanuele; Shorten, Robert

2015-11-01

This paper describes a Markov-chain-based approach to modelling multi-modal transportation networks. An advantage of the model is the ability to accommodate complex dynamics and handle huge amounts of data. The transition matrix of the Markov chain is built and the model is validated using the data extracted from a traffic simulator. A realistic test-case using multi-modal data from the city of London is given to further support the ability of the proposed methodology to handle big quantities of data. Then, we use the Markov chain as a control tool to improve the overall efficiency of a transportation network, and some practical examples are described to illustrate the potentials of the approach.
A Multi-Objective, Hub-and-Spoke Supply Chain Design Model For Densified Biomass

DOE Office of Scientific and Technical Information (OSTI.GOV)

Md S. Roni; Sandra Eksioglu; Kara G. Cafferty

In this paper we propose a model to design the supply chain for densified biomass. Rail is typically used for long-haul, high-volume shipment of densified biomass. This is the reason why a hub-and-spoke network structure is used to model this supply chain. The model is formulated as a multi-objective, mixed-integer programing problem under economic, environmental, and social criteria. The goal is to identify the feasibility of meeting the Renewable Fuel Standard (RFS) by using biomass for production of cellulosic ethanol. The focus in not just on the costs associated with meeting these standards, but also exploring the social and environmentalmore » benefits that biomass production and processing offers by creating new jobs and reducing greenhouse gas (GHG) emissions. We develop an augmented ?-constraint method to find the exact Pareto solution to this optimization problem. We develop a case study using data from the Mid-West. The model identifies the number, capacity and location of biorefineries needed to make use of the biomass available in the region. The model estimates the delivery cost of cellulosic ethanol under different scenario, the number new jobs created and the GHG emission reductions in the supply chain.« less
A Multi-Objective, Hub-and-Spoke Supply Chain Design Model for Densified Biomass

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jacob J. Jacobson; Md. S. Roni; Kara G. Cafferty

In this paper we propose a model to design the supply chain for densified biomass. Rail is typically used for longhaul, high-volume shipment of densified biomass. This is the reason why a hub-and-spoke network structure is used to model this supply chain. The model is formulated as a multi-objective, mixed-integer programing problem under economic, environmental, and social criteria. The goal is to identify the feasibility of meeting the Renewable Fuel Standard (RFS) by using biomass for production of cellulosic ethanol. The focus is not just on the costs associated with meeting these standards, but also exploring the social and environmentalmore » benefits that biomass production and processing offers by creating new jobs and reducing greenhouse gas (GHG) emissions. We develop an augmented ?-constraint method to find the exact Pareto solution to this optimization problem. We develop a case study using data from the Mid-West. The model identifies the number, capacity and location of biorefineries needed to make use of the biomass available in the region. The model estimates the delivery cost of cellulosic ethanol under different scenario, the number new jobs created and the GHG emission reductions in the supply chain.« less
User's Manual MCnest - Markov Chain Nest Productivity Model Version 2.0

EPA Science Inventory

The Markov chain nest productivity model, or MCnest, is a set of algorithms for integrating the results of avian toxicity tests with reproductive life-history data to project the relative magnitude of chemical effects on avian reproduction. The mathematical foundation of MCnest i...
A new paradigm for the molecular basis of rubber elasticity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hanson, David E.; Barber, John L.

The molecular basis for rubber elasticity is arguably the oldest and one of the most important questions in the field of polymer physics. The theoretical investigation of rubber elasticity began in earnest almost a century ago with the development of analytic thermodynamic models, based on simple, highly-symmetric configurations of so-called Gaussian chains, i.e. polymer chains that obey Markov statistics. Numerous theories have been proposed over the past 90 years based on the ansatz that the elastic force for individual network chains arises from the entropy change associated with the distribution of end-to-end distances of a free polymer chain. There aremore » serious philosophical objections to this assumption and others, such as the assumption that all network nodes undergo affine motion and that all of the network chains have the same length. Recently, a new paradigm for elasticity in rubber networks has been proposed that is based on mechanisms that originate at the molecular level. Using conventional statistical mechanics analyses, quantum chemistry, and molecular dynamics simulations, the fundamental entropic and enthalpic chain extension forces for polyisoprene (natural rubber) have been determined, along with estimates for the basic force constants. Concurrently, the complex morphology of natural rubber networks (the joint probability density distributions that relate the chain end-to-end distance to its contour length) has also been captured in a numerical model. When molecular chain forces are merged with the network structure in this model, it is possible to study the mechanical response to tensile and compressive strains of a representative volume element of a polymer network. As strain is imposed on a network, pathways of connected taut chains, that completely span the network along strain axis, emerge. Although these chains represent only a few percent of the total, they account for nearly all of the elastic stress at high strain. Here we provide a brief review of previous elasticity theories and their deficiencies, and present a new paradigm with an emphasis on experimental comparisons.« less
A new paradigm for the molecular basis of rubber elasticity

DOE PAGES

Hanson, David E.; Barber, John L.

2015-02-19

The molecular basis for rubber elasticity is arguably the oldest and one of the most important questions in the field of polymer physics. The theoretical investigation of rubber elasticity began in earnest almost a century ago with the development of analytic thermodynamic models, based on simple, highly-symmetric configurations of so-called Gaussian chains, i.e. polymer chains that obey Markov statistics. Numerous theories have been proposed over the past 90 years based on the ansatz that the elastic force for individual network chains arises from the entropy change associated with the distribution of end-to-end distances of a free polymer chain. There aremore » serious philosophical objections to this assumption and others, such as the assumption that all network nodes undergo affine motion and that all of the network chains have the same length. Recently, a new paradigm for elasticity in rubber networks has been proposed that is based on mechanisms that originate at the molecular level. Using conventional statistical mechanics analyses, quantum chemistry, and molecular dynamics simulations, the fundamental entropic and enthalpic chain extension forces for polyisoprene (natural rubber) have been determined, along with estimates for the basic force constants. Concurrently, the complex morphology of natural rubber networks (the joint probability density distributions that relate the chain end-to-end distance to its contour length) has also been captured in a numerical model. When molecular chain forces are merged with the network structure in this model, it is possible to study the mechanical response to tensile and compressive strains of a representative volume element of a polymer network. As strain is imposed on a network, pathways of connected taut chains, that completely span the network along strain axis, emerge. Although these chains represent only a few percent of the total, they account for nearly all of the elastic stress at high strain. Here we provide a brief review of previous elasticity theories and their deficiencies, and present a new paradigm with an emphasis on experimental comparisons.« less
Relating MBSE to Spacecraft Development: A NASA Pathfinder

NASA Technical Reports Server (NTRS)

Othon, Bill

2016-01-01

The NASA Engineering and Safety Center (NESC) has sponsored a Pathfinder Study to investigate how Model Based Systems Engineering (MBSE) and Model Based Engineering (MBE) techniques can be applied by NASA spacecraft development projects. The objectives of this Pathfinder Study included analyzing both the products of the modeling activity, as well as the process and tool chain through which the spacecraft design activities are executed. Several aspects of MBSE methodology and process were explored. Adoption and consistent use of the MBSE methodology within an existing development environment can be difficult. The Pathfinder Team evaluated the possibility that an "MBSE Template" could be developed as both a teaching tool as well as a baseline from which future NASA projects could leverage. Elements of this template include spacecraft system component libraries, data dictionaries and ontology specifications, as well as software services that do work on the models themselves. The Pathfinder Study also evaluated the tool chain aspects of development. Two chains were considered: 1. The Development tool chain, through which SysML model development was performed and controlled, and 2. The Analysis tool chain, through which both static and dynamic system analysis is performed. Of particular interest was the ability to exchange data between SysML and other engineering tools such as CAD and Dynamic Simulation tools. For this study, the team selected a Mars Lander vehicle as the element to be designed. The paper will discuss what system models were developed, how data was captured and exchanged, and what analyses were conducted.
Real-Time Optimal Flood Control Decision Making and Risk Propagation Under Multiple Uncertainties

NASA Astrophysics Data System (ADS)

Zhu, Feilin; Zhong, Ping-An; Sun, Yimeng; Yeh, William W.-G.

2017-12-01

Multiple uncertainties exist in the optimal flood control decision-making process, presenting risks involving flood control decisions. This paper defines the main steps in optimal flood control decision making that constitute the Forecast-Optimization-Decision Making (FODM) chain. We propose a framework for supporting optimal flood control decision making under multiple uncertainties and evaluate risk propagation along the FODM chain from a holistic perspective. To deal with uncertainties, we employ stochastic models at each link of the FODM chain. We generate synthetic ensemble flood forecasts via the martingale model of forecast evolution. We then establish a multiobjective stochastic programming with recourse model for optimal flood control operation. The Pareto front under uncertainty is derived via the constraint method coupled with a two-step process. We propose a novel SMAA-TOPSIS model for stochastic multicriteria decision making. Then we propose the risk assessment model, the risk of decision-making errors and rank uncertainty degree to quantify the risk propagation process along the FODM chain. We conduct numerical experiments to investigate the effects of flood forecast uncertainty on optimal flood control decision making and risk propagation. We apply the proposed methodology to a flood control system in the Daduhe River basin in China. The results indicate that the proposed method can provide valuable risk information in each link of the FODM chain and enable risk-informed decisions with higher reliability.
First and second order semi-Markov chains for wind speed modeling

NASA Astrophysics Data System (ADS)

Prattico, F.; Petroni, F.; D'Amico, G.

2012-04-01

The increasing interest in renewable energy leads scientific research to find a better way to recover most of the available energy. Particularly, the maximum energy recoverable from wind is equal to 59.3% of that available (Betz law) at a specific pitch angle and when the ratio between the wind speed in output and in input is equal to 1/3. The pitch angle is the angle formed between the airfoil of the blade of the wind turbine and the wind direction. Old turbine and a lot of that actually marketed, in fact, have always the same invariant geometry of the airfoil. This causes that wind turbines will work with an efficiency that is lower than 59.3%. New generation wind turbines, instead, have a system to variate the pitch angle by rotating the blades. This system able the wind turbines to recover, at different wind speed, always the maximum energy, working in Betz limit at different speed ratios. A powerful system control of the pitch angle allows the wind turbine to recover better the energy in transient regime. A good stochastic model for wind speed is then needed to help both the optimization of turbine design and to assist the system control to predict the value of the wind speed to positioning the blades quickly and correctly. The possibility to have synthetic data of wind speed is a powerful instrument to assist designer to verify the structures of the wind turbines or to estimate the energy recoverable from a specific site. To generate synthetic data, Markov chains of first or higher order are often used [1,2,3]. In particular in [3] is presented a comparison between a first-order Markov chain and a second-order Markov chain. A similar work, but only for the first-order Markov chain, is conduced by [2], presenting the probability transition matrix and comparing the energy spectral density and autocorrelation of real and synthetic wind speed data. A tentative to modeling and to join speed and direction of wind is presented in [1], by using two models, first-order Markov chain with different number of states, and Weibull distribution. All this model use Markov chains to generate synthetic wind speed time series but the search for a better model is still open. Approaching this issue, we applied new models which are generalization of Markov models. More precisely we applied semi-Markov models to generate synthetic wind speed time series. Semi-Markov processes (SMP) are a wide class of stochastic processes which generalize at the same time both Markov chains and renewal processes. Their main advantage is that of using whatever type of waiting time distribution for modeling the time to have a transition from one state to another one. This major flexibility has a price to pay: availability of data to estimate the parameters of the model which are more numerous. Data availability is not an issue in wind speed studies, therefore, semi-Markov models can be used in a statistical efficient way. In this work we present three different semi-Markov chain models: the first one is a first-order SMP where the transition probabilities from two speed states (at time Tn and Tn-1) depend on the initial state (the state at Tn-1), final state (the state at Tn) and on the waiting time (given by t=Tn-Tn-1), the second model is a second order SMP where we consider the transition probabilities as depending also on the state the wind speed was before the initial state (which is the state at Tn-2) and the last one is still a second order SMP where the transition probabilities depends on the three states at Tn-2,Tn-1 and Tn and on the waiting times t_1=Tn-1-Tn-2 and t_2=Tn-Tn-1. The three models are used to generate synthetic time series for wind speed by means of Monte Carlo simulations and the time lagged autocorrelation is used to compare statistical properties of the proposed models with those of real data and also with a time series generated though a simple Markov chain. [1] F. Youcef Ettoumi, H. Sauvageot, A.-E.-H. Adane, Statistical bivariate modeling of wind using first-order Markov chain and Weibull distribution, Renewable Energy, 28/2003 1787-1802. [2] A. Shamshad, M.A. Bawadi, W.M.W. Wan Hussin, T.A. Majid, S.A.M. Sanusi, First and second order Markov chain models for synthetic generation of wind speed time series, Energy 30/2005 693-708. [3] H. Nfaoui, H. Essiarab, A.A.M. Sayigh, A stochastic Markov chain model for simulating wind speed time series at Tangiers, Morocco, Renewable Energy 29/2004, 1407-1418.
Rapid Configurational Fluctuations in a Model of Methylcellulose

NASA Astrophysics Data System (ADS)

Li, Xiaolan; Dorfman, Kevin

Methylcellulose is a thermoresponsive polymer that undergoes a phase transition at elevated temperature, forming fibrils of a uniform diameter. However, the gelation mechanism is still unclear, in particular at higher polymer concentrations. We have investigated a coarse-grained model for methylcellulose, proposed by Larson and coworkers, that produces collapsed toroids in dilute solution with a radius close to that in experiments. Using Brownian Dynamics simulations, we demonstrate that this model's dihedral potential generates ``flipping events'', which helps the chain to avoid kinetic traps by undergoing a sudden transition between a coiled and a collapsed state. If the dihedral potential is removed, the chains cannot escape from their collapsed configuration, whereas at high dihedral potentials, the chains cannot stabilize the collapsed state. We will present quantitative results on the effect of the dihedral potential on both chain statistics and dynamic behavior, and discuss the implication of our results on the spontaneous formation of high-aspect ratio fibrils in experiments.
Supply chain model with price- and trade credit-sensitive demand under two-level permissible delay in payments

NASA Astrophysics Data System (ADS)

Giri, B. C.; Maiti, T.

2013-05-01

This article develops a single-manufacturer and single-retailer supply chain model under two-level permissible delay in payments when the manufacturer follows a lot-for-lot policy in response to the retailer's demand. The manufacturer offers a trade credit period to the retailer with the contract that the retailer must share a fraction of the profit earned during the trade credit period. On the other hand, the retailer provides his customer a partial trade credit which is less than that of the manufacturer. The demand at the retailer is assumed to be dependent on the selling price and the trade credit period offered to the customers. The average net profit of the supply chain is derived and an algorithm for finding the optimal solution is developed. Numerical examples are given to demonstrate the coordination policy of the supply chain and examine the sensitivity of key model-parameters.
Simple Physics-Based Analytical Formulas for the Potentials of Mean Force of the Interaction of Amino Acid Side Chains in Water. VII. Charged-Hydrophobic/Polar and Polar-Hydrophobic/Polar Side Chains.

PubMed

Makowski, Mariusz; Liwo, Adam; Scheraga, Harold A

2017-01-19

The physics-based potentials of side-chain-side-chain interactions corresponding to pairs composed of charged and polar, polar and polar, charged and hydrophobic, and hydrophobic and hydrophobic side chains have been determined. A total of 144 four-dimensional potentials of mean force (PMFs) of all possible pairs of molecules modeling these pairs were determined by umbrella-sampling molecular dynamics simulations in explicit water as functions of distance and orientation, and the analytical expressions were then fitted to the PMFs. Depending on the type of interacting sites, the analytical approximation to the PMF is a sum of terms corresponding to van der Waals interactions and cavity-creation involving the nonpolar sections of the side chains and van der Waals, cavity-creation, and electrostatic (charge-dipole or dipole-dipole) interaction energies and polarization energies involving the charged or polar sections of the side chains. The model used in this work reproduces all features of the interacting pairs. The UNited RESidue force field with the new side-chain-side-chain interaction potentials was preliminarily tested with the N-terminal part of the B-domain of staphylococcal protein A (PDBL 1BDD ; a three-α-helix bundle) and UPF0291 protein YnzC from Bacillus subtilis (PDB: 2HEP ; an α-helical hairpin).
How did the platypus get its sex chromosome chain? A comparison of meiotic multiples and sex chromosomes in plants and animals.

PubMed

Gruetzner, Frank; Ashley, Terry; Rowell, David M; Marshall Graves, Jennifer A

2006-04-01

The duck-billed platypus is an extraordinary mammal. Its chromosome complement is no less extraordinary, for it includes a system in which ten sex chromosomes form an extensive meiotic chain in males. Such meiotic multiples are unprecedented in vertebrates but occur sporadically in plant and invertebrate species. In this paper, we review the evolution and formation of meiotic multiples in plants and invertebrates to try to gain insights into the origin of the platypus meiotic multiple. We describe the meiotic hurdles that translocated mammalian chromosomes face, which make longer chains disadvantageous in mammals, and we discuss how sex chromosomes and dosage compensation might have affected the evolution of sex-linked meiotic multiples. We conclude that the evolutionary conservation of the chain in monotremes, the structural properties of the translocated chromosomes and the highly accurate segregation at meiosis make the platypus system remarkably different from meiotic multiples in other species. We discuss alternative evolutionary models, which fall broadly into two categories: either the chain is the result of a sequence of translocation events from an ancestral pair of sex chromosomes (Model I) or the entire chain came into being at once by hybridization of two populations with different chromosomal rearrangements sharing monobrachial homology (Model II).
Precise side-chain conformation analysis of L-phenylalanine in α-helical polypeptide by quantum-chemical calculation and 13C CP-MAS NMR measurement

NASA Astrophysics Data System (ADS)

Niimura, Subaru; Suzuki, Junya; Kurosu, Hiromichi; Yamanobe, Takeshi; Shoji, Akira

2010-04-01

To clarify the positive role of side-chain conformation in the stability of protein secondary structure (main-chain conformation), we successfully calculated the optimization structure of a well-defined α-helical octadecapeptide composed of L-alanine (Ala) and L-phenylalanine (Phe) residues, H-(Ala) 8-Phe-(Ala) 9-OH, based on the molecular orbital calculation with density functional theory (DFT/B3LYP/6-31G(d)). From the total energy and the precise secondary structural parameters such as main-chain dihedral angles and hydrogen-bond parameters of the optimized structure, we confirmed that the conformational stability of an α-helix is affected dominantly by the side-chain conformation ( χ1) of the Phe residue in this system: model A ( T form: around 180° of χ1) is most stable in α-helix and model B ( G + form: around -60° of χ1) is next stable, but model C ( G - form: around 60° of χ1) is less stable. In addition, we demonstrate that the stable conformation of poly( L-phenylalanine) is an α-helix with the side-chain T form, by comparison of the carbonyl 13C chemical shift measured by 13C CP-MAS NMR and the calculated one.
Surface vibrational structure at alkane liquid/vapor interfaces

NASA Astrophysics Data System (ADS)

Esenturk, Okan; Walker, Robert A.

2006-11-01

Broadband vibrational sum frequency spectroscopy (VSFS) has been used to examine the surface structure of alkane liquid/vapor interfaces. The alkanes range in length from n-nonane (C9H20) to n-heptadecane (C17H36), and all liquids except heptadecane are studied at temperatures well above their bulk (and surface) freezing temperatures. Intensities of vibrational bands in the CH stretching region acquired under different polarization conditions show systematic, chain length dependent changes. Data provide clear evidence of methyl group segregation at the liquid/vapor interface, but two different models of alkane chain structure can predict chain length dependent changes in band intensities. Each model leads to a different interpretation of the extent to which different chain segments contribute to the anisotropic interfacial region. One model postulates that changes in vibrational band intensities arise solely from a reduced surface coverage of methyl groups as alkane chain length increases. The additional methylene groups at the surface must be randomly distributed and make no net contribution to the observed VSF spectra. The second model considers a simple statistical distribution of methyl and methylene groups populating a three dimensional, interfacial lattice. This statistical picture implies that the VSF signal arises from a region extending several functional groups into the bulk liquid, and that the growing fraction of methylene groups in longer chain alkanes bears responsibility for the observed spectral changes. The data and resulting interpretations provide clear benchmarks for emerging theories of molecular structure and organization at liquid surfaces, especially for liquids lacking strong polar ordering.
Testing for context-dependence in a processing chain interaction among detritus-feeding aquatic insects

PubMed Central

DAUGHERTY, MATTHEW P.; JULIANO, STEVEN A.

2008-01-01

Scirtid beetles may benefit mosquitoes Ochlerotatus triseriatus (Say) by consuming whole leaves and leaving behind fine particles required by mosquito larvae. Such interactions based on the sequential use of a resource that occurs in multiple forms are known as processing chains.Models of processing chains predict that interactions can vary from commensal (0, +) to amensal (0, −), depending on how quickly resource is processed in the absence of consumers.The scirtid-O. triseriatus system was used to test the prediction derived from processing chain models that, as consumer-independent processing increases, scirtids benefit mosquitoes less. Consumer-independent processing rate was manipulated by using different leaf species that vary in decay rate, or by physically crushing a single leaf type to different degrees.Although scirtids increased the production of fine particles, the effects of scirtids on mosquitoes were weak and were not dependent on consumer-independent processing rate.In the leaf manipulation experiment, a correlation between scirtid feeding and consumer-independent processing was detected. Numerical simulations suggest that such a correlation may eliminate shifts from commensal to amensal at equilibrium; because mosquito populations are typically not at equilibrium, however, this correlation may not be important.There was evidence that mosquitoes affected scirtids negatively, which is inconsistent with the structure of processing chain interactions in models. Processing chain models need to incorporate more detail on the biology of scirtids and O. triseriatus, especially alternative mechanisms of interaction, if they are to describe scirtid-O. triseriatus dynamics accurately. PMID:19060960
Free fatty acids chain length distribution affects the permeability of skin lipid model membranes.

PubMed

Uchiyama, Masayuki; Oguri, Masashi; Mojumdar, Enamul H; Gooris, Gert S; Bouwstra, Joke A

2016-09-01

The lipid matrix in the stratum corneum (SC) plays an important role in the barrier function of the skin. The main lipid classes in this lipid matrix are ceramides (CERs), cholesterol (CHOL) and free fatty acids (FFAs). The aim of this study was to determine whether a variation in CER subclass composition and chain length distribution of FFAs affect the permeability of this matrix. To examine this, we make use of lipid model membranes, referred to as stratum corneum substitute (SCS). We prepared SCS containing i) single CER subclass with either a single FFA or a mixture of FFAs and CHOL, or ii) a mixture of various CER subclasses with either a single FFA or a mixture of FFAs and CHOL. In vitro permeation studies were performed using ethyl-p-aminobenzoic acid (E-PABA) as a model drug. The flux of E-PABA across the SCS containing the mixture of FFAs was higher than that across the SCS containing a single FA with a chain length of 24 C atoms (FA C24), while the E-PABA flux was not effected by the CER composition. To select the underlying factors for the changes in permeability, the SCSs were examined by Fourier transform infrared spectroscopy (FTIR) and Small angle X-ray scattering (SAXS). All lipid models demonstrated a similar phase behavior. However, when focusing on the conformational ordering of the individual FFA chains, the shorter chain FFA (with a chain length of 16, 18 or 20 C atoms forming only 11m/m% of the total FFA level) had a higher conformational disordering, while the conformational ordering of the chains of the CER and FA C24 and FA C22 hardly did not change irrespective of the composition of the SCS. In conclusion, the conformational mobility of the short chain FFAs present only at low levels in the model SC lipid membranes has a great impact on the permeability of E-PABA. Copyright © 2016 Elsevier B.V. All rights reserved.
Computational Modeling of Hydroxypropyl-Methylcellulose Acetate Succinate (HPMCAS) and Phenytoin Interactions: A Systematic Coarse-Graining Approach.

PubMed

Huang, Wenjun; Mandal, Taraknath; Larson, Ronald G

2017-03-06

We present coarse-grained (CG) force fields for hydroxypropyl-methylcellulose acetate succinate (HPMCAS) polymers and the drug molecule phenytoin using a bead/stiff spring model, with each bead representing a HPMCAS monomer or monomer side group (hydroxypropyl acetyl, acetyl, or succinyl) or a single phenytoin ring. We obtain the bonded and nonbonded interaction parameters in our CG model using the RDFs from atomistic simulations of short HPMCAS model oligomers (20-mer) and atomistic simulations of phenytoin molecules. The nonbonded interactions are modeled using a LJ 12-6 potential, with separate parameters for each monomer substitution type, which allows heterogeneous polymer chains to be modeled. The cross interaction terms between the polymer and phenytoin CG beads are obtained explicitly from atomistic level polymer-phenytoin simulations, rather than from mixing rules. We study the solvation behavior of 50-mer and 100-mer polymer chains and find chain-length-dependent aggregation. We also compare the phenytoin CG force field developed in this work with that in Mandal et al. (Soft Matter, 2016, 12, 8246-8255) and conclude both are suitable for studying the interaction between polymer and drug in solvated solid dispersion formulation, in the absence of drug crystallization. Finally, we present simulations of heterogeneous HPMCAS model polymer chains and phenytoin molecules. Polymer and drug form a complex in a short period of simulation time due to strong intermolecular interactions. Moreover, the protonated polymer chains are more effective than deprotonated ones in inhibiting the drug aggregation in the polymer-drug complex.

Molecular Dynamics Modeling of PPTA Crystals in Aramid Fibers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mercer, Brian Scott

2016-05-19

In this work, molecular dynamics modeling is used to study the mechanical properties of PPTA crystallites, which are the fundamental microstructural building blocks of polymer aramid bers such as Kevlar. Particular focus is given to constant strain rate axial loading simulations of PPTA crystallites, which is motivated by the rate-dependent mechanical properties observed in some experiments with aramid bers. In order to accommodate the covalent bond rupture that occurs in loading a crystallite to failure, the reactive bond order force eld ReaxFF is employed to conduct the simulations. Two major topics are addressed: The rst is the general behavior ofmore » PPTA crystallites under strain rate loading. Constant strain rate loading simulations of crystalline PPTA reveal that the crystal failure strain increases with increasing strain rate, while the modulus is not a ected by the strain rate. Increasing temperature lowers both the modulus and the failure strain. The simulations also identify the C N bond connecting the aromatic rings as weakest primary bond along the backbone of the PPTA chain. The e ect of chain-end defects on PPTA micromechanics is explored, and it is found that the presence of a chain-end defect transfers load to the adjacent chains in the hydrogen-bonded sheet in which the defect resides, but does not in uence the behavior of any other chains in the crystal. Chain-end defects are found to lower the strength of the crystal when clustered together, inducing bond failure via stress concentrations arising from the load transfer to bonds in adjacent chains near the defect site. The second topic addressed is the nature of primary and secondary bond failure in crystalline PPTA. Failure of both types of bonds is found to be stochastic in nature and driven by thermal uctuations of the bonds within the crystal. A model is proposed which uses reliability theory to model bonds under constant strain rate loading as components with time-dependent failure rate functions. The model is shown to work well for predicting the onset of primary backbone bond failure, as well as the onset of secondary bond failure via chain slippage for the case of isolated non-interacting chain-end defects.« less
Forecasting jobs in the supply chain for investments in residential energy efficiency retrofits in Florida

NASA Astrophysics Data System (ADS)

Fobair, Richard C., II

This research presents a model for forecasting the numbers of jobs created in the energy efficiency retrofit (EER) supply chain resulting from an investment in upgrading residential buildings in Florida. This investigation examined material supply chains stretching from mining to project installation for three product types: insulation, windows/doors, and heating, ventilating, and air conditioning (HVAC) systems. Outputs from the model are provided for the project, sales, manufacturing, and mining level. The model utilizes reverse-estimation to forecast the numbers of jobs that result from an investment. Reverse-estimation is a process that deconstructs a total investment into its constituent parts. In this research, an investment is deconstructed into profit, overhead, and hard costs for each level of the supply chain and over multiple iterations of inter-industry exchanges. The model processes an investment amount, the type of work and method of contracting into a prediction of the number of jobs created. The deconstruction process utilizes data from the U.S. Economic Census. At each supply chain level, the cost of labor is reconfigured into full-time equivalent (FTE) jobs (i.e. equivalent to 40 hours per week for 52 weeks) utilizing loaded labor rates and a typical employee mix. The model is sensitive to adjustable variables, such as percentage of work performed per type of product, allocation of worker time per skill level, annual hours for FTE calculations, wage rate, and benefits. This research provides several new insights into job creation. First, it provides definitions that can be used for future research on jobs in supply chains related to energy efficiency. Second, it provides a methodology for future investigators to calculate jobs in a supply chain resulting from an investment in energy efficiency upgrades to a building. The methodology used in this research is unique because it examines gross employment at the sub-industry level for specific commodities. Most research on employment examines the net employment change (job creation less job destruction) at levels for regions, industries, and the aggregate economy. Third, it provides a forecast of the numbers of jobs for an investment in energy efficiency over the entire supply chain for the selected industries and the job factors for major levels of the supply chain.
DNA compaction by poly (amido amine) dendrimers of ammonia cored and ethylene diamine cored

NASA Astrophysics Data System (ADS)

Qamhieh, K.; Al-Shawwa, J.

2017-06-01

The complexes build-up of DNA and soft particles poly amidoamine (PAMAM) dendrimers of ammonia cored of generations (G1-G6) and ethylenediamine cored of generations (G1-G10) have been studied, using a new theoretical model developed by Qamhieh and coworkers. The model describes the interaction between linear polyelectrolyte (LPE) chain and ion-penetrable spheres. Many factors affecting LPE/dendrimer complex have been investigated such as dendrimer generation, the Bjerrum length, salt concentration, and rigidity of the LPE chain represented by the persistence length. It is found that the wrapping chain length around dendrimer increases by increasing dendrimer`s generation, Bjerrum length, and salt concentration, while decreases by increasing the persistence length of the LPE chain. Also we can conclude that the wrapping length of LPE chain around ethylenediamine cored dendrimers is larger than its length around ammonia cored dendrimers.
Optimizing pricing and ordering strategies in a three-level supply chain under return policy

NASA Astrophysics Data System (ADS)

Noori-daryan, Mahsa; Taleizadeh, Ata Allah

2018-03-01

This paper develops an economic production quantity model in a three-echelon supply chain composing of a supplier, a manufacturer and a wholesaler under two scenarios. As the first scenario, we consider a return contract between the outside supplier and the supplier and also between the manufacturer and the wholesaler, but in the second one, the return policy between the manufacturer and the wholesaler is not applied. Here, it is assumed that shortage is permitted and demand is price-sensitive. The principal goal of the research is to maximize the total profit of the chain by optimizing the order quantity of the supplier and the selling prices of the manufacturer and the wholesaler. Nash-equilibrium approach is considered between the chain members. In the end, a numerical example is presented to clarify the applicability of the introduced model and compare the profit of the chain under two scenarios.
Monte Carlo estimation of total variation distance of Markov chains on large spaces, with application to phylogenetics.

PubMed

Herbei, Radu; Kubatko, Laura

2013-03-26

Markov chains are widely used for modeling in many areas of molecular biology and genetics. As the complexity of such models advances, it becomes increasingly important to assess the rate at which a Markov chain converges to its stationary distribution in order to carry out accurate inference. A common measure of convergence to the stationary distribution is the total variation distance, but this measure can be difficult to compute when the state space of the chain is large. We propose a Monte Carlo method to estimate the total variation distance that can be applied in this situation, and we demonstrate how the method can be efficiently implemented by taking advantage of GPU computing techniques. We apply the method to two Markov chains on the space of phylogenetic trees, and discuss the implications of our findings for the development of algorithms for phylogenetic inference.
DOE Office of Scientific and Technical Information (OSTI.GOV)

Suhara, Tadahiro; Kanada-En'yo, Yoshiko

We investigate the linear-chain structures in highly excited states of {sup 14}C using a generalized molecular-orbital model, by which we incorporate an asymmetric configuration of three {alpha} clusters in the linear-chain states. By applying this model to the {sup 14}C system, we study the {sup 10}Be+{alpha} correlation in the linear-chain state of {sup 14}C. To clarify the origin of the {sup 10}Be+{alpha} correlation in the {sup 14}C linear-chain state, we analyze linear 3 {alpha} and 3{alpha} + n systems in a similar way. We find that a linear 3{alpha} system prefers the asymmetric 2{alpha} + {alpha} configuration, whose origin ismore » the many-body correlation incorporated by the parity projection. This configuration causes an asymmetric mean field for two valence neutrons, which induces the concentration of valence neutron wave functions around the correlating 2{alpha}. A linear-chain structure of {sup 16}C is also discussed.« less
Avian life history profiles for use in the Markov chain nest productivity model (MCnest)

EPA Science Inventory

The Markov Chain nest productivity model, or MCnest, quantitatively estimates the effects of pesticides or other toxic chemicals on annual reproductive success of avian species (Bennett and Etterson 2013, Etterson and Bennett 2013). The Basic Version of MCnest was developed as a...
Doubly self-consistent field theory of grafted polymers under simple shear in steady state

DOE Office of Scientific and Technical Information (OSTI.GOV)

Suo, Tongchuan; Whitmore, Mark D., E-mail: mark-whitmore@umanitoba.ca

2014-03-21

We present a generalization of the numerical self-consistent mean-field theory of polymers to the case of grafted polymers under simple shear. The general theoretical framework is presented, and then applied to three different chain models: rods, Gaussian chains, and finitely extensible nonlinear elastic (FENE) chains. The approach is self-consistent at two levels. First, for any flow field, the polymer density profile and effective potential are calculated self-consistently in a manner similar to the usual self-consistent field theory of polymers, except that the calculation is inherently two-dimensional even for a laterally homogeneous system. Second, through the use of a modified Brinkmanmore » equation, the flow field and the polymer profile are made self-consistent with respect to each other. For all chain models, we find that reasonable levels of shear cause the chains to tilt, but it has very little effect on the overall thickness of the polymer layer, causing a small decrease for rods, and an increase of no more than a few percent for the Gaussian and FENE chains. Using the FENE model, we also probe the individual bond lengths, bond correlations, and bond angles along the chains, the effects of the shear on them, and the solvent and bonded stress profiles. We find that the approximations needed within the theory for the Brinkman equation affect the bonded stress, but none of the other quantities.« less
DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, K. S.; Nakae, L. F.; Prasad, M. K.

Here, we solve a simple theoretical model of time evolving fission chains due to Feynman that generalizes and asymptotically approaches the point model theory. The point model theory has been used to analyze thermal neutron counting data. This extension of the theory underlies fast counting data for both neutrons and gamma rays from metal systems. Fast neutron and gamma-ray counting is now possible using liquid scintillator arrays with nanosecond time resolution. For individual fission chains, the differential equations describing three correlated probability distributions are solved: the time-dependent internal neutron population, accumulation of fissions in time, and accumulation of leaked neutronsmore » in time. Explicit analytic formulas are given for correlated moments of the time evolving chain populations. The equations for random time gate fast neutron and gamma-ray counting distributions, due to randomly initiated chains, are presented. Correlated moment equations are given for both random time gate and triggered time gate counting. There are explicit formulas for all correlated moments are given up to triple order, for all combinations of correlated fast neutrons and gamma rays. The nonlinear differential equations for probabilities for time dependent fission chain populations have a remarkably simple Monte Carlo realization. A Monte Carlo code was developed for this theory and is shown to statistically realize the solutions to the fission chain theory probability distributions. Combined with random initiation of chains and detection of external quanta, the Monte Carlo code generates time tagged data for neutron and gamma-ray counting and from these data the counting distributions.« less
Comparative cost models of a liquid nitrogen vapor phase (LNVP) cold chain-distributed cryopreserved malaria vaccine vs. a conventional vaccine

PubMed Central

Garcia, Cristina Reyes; Manzi, Fatuma; Tediosi, Fabrizio; Hoffman, Stephen L.; James, Eric R.

2013-01-01

Typically, vaccines distributed through the Expanded Program on Immunization (EPI) use a 2–8 °C cold chain with 4–5 stops. The PfSPZ Vaccine comprises whole live-attenuated cryopreserved sporozoites stored in liquid nitrogen (LN2) vapor phase (LNVP) below −140 °C and would be distributed through a LNVP cold chain. The purpose of this study was to model LNVP cold chain distribution for the cryopreserved PfSPZ Vaccine in Tanzania, estimate the costs and compare these costs to those that would be incurred in distributing a ‘conventional’ malaria vaccine through the EPI. Capital and recurrent costs for storage, transportation, labor, energy usage and facilities were determined for the birth cohort in Tanzania over five years. Costs were calculated using WHO/UNESCO calculators. These were applied to a 2–8 °C distribution model with national, regional, district, and health facility levels, and for the cryopreserved vaccine using a ‘modified hub-and-spoke’ (MH-S) LNVP distribution system comprising a central national store, peripheral health facilities and an intermediate district-level transhipment stop. Estimated costs per fully immunized child (FIC) were $ 6.11 for the LNVP-distributed cryopreserved vaccine where the LN2 is generated, and $ 6.04 with purchased LN2 (assuming US $ 1.00/L). The FIC costs for distributing a conventional vaccine using the four level 2–8 °C cold chain were $ 6.10, and with a tariff distribution system as occurs in Tanzania the FIC cost was $ 5.53. The models, therefore, predicted little difference in 5-year distribution costs between the PfSPZ Vaccine distributed through a MH-S LNVP cold chain and a conventional vaccine distributed through the more traditional EPI system. A LNVP cold chain provides additional benefits through the use of durable dry shippers because no refrigerators, freezers or refrigerated trucks are required. Thus strain at the cold chain periphery, vaccine wastage from cold chain failures and the environmental impact of distribution would all be reduced. PMID:23146676
Comparative cost models of a liquid nitrogen vapor phase (LNVP) cold chain-distributed cryopreserved malaria vaccine vs. a conventional vaccine.

PubMed

Garcia, Cristina Reyes; Manzi, Fatuma; Tediosi, Fabrizio; Hoffman, Stephen L; James, Eric R

2013-01-02

Typically, vaccines distributed through the Expanded Program on Immunization (EPI) use a 2-8°C cold chain with 4-5 stops. The PfSPZ Vaccine comprises whole live-attenuated cryopreserved sporozoites stored in liquid nitrogen (LN(2)) vapor phase (LNVP) below -140°C and would be distributed through a LNVP cold chain. The purpose of this study was to model LNVP cold chain distribution for the cryopreserved PfSPZ Vaccine in Tanzania, estimate the costs and compare these costs to those that would be incurred in distributing a 'conventional' malaria vaccine through the EPI. Capital and recurrent costs for storage, transportation, labor, energy usage and facilities were determined for the birth cohort in Tanzania over five years. Costs were calculated using WHO/UNESCO calculators. These were applied to a 2-8°C distribution model with national, regional, district, and health facility levels, and for the cryopreserved vaccine using a 'modified hub-and-spoke' (MH-S) LNVP distribution system comprising a central national store, peripheral health facilities and an intermediate district-level transhipment stop. Estimated costs per fully immunized child (FIC) were $ 6.11 for the LNVP-distributed cryopreserved vaccine where the LN(2) is generated, and $ 6.04 with purchased LN(2) (assuming US $ 1.00/L). The FIC costs for distributing a conventional vaccine using the four level 2-8°C cold chain were $ 6.10, and with a tariff distribution system as occurs in Tanzania the FIC cost was $ 5.53. The models, therefore, predicted little difference in 5-year distribution costs between the PfSPZ Vaccine distributed through a MH-S LNVP cold chain and a conventional vaccine distributed through the more traditional EPI system. A LNVP cold chain provides additional benefits through the use of durable dry shippers because no refrigerators, freezers or refrigerated trucks are required. Thus strain at the cold chain periphery, vaccine wastage from cold chain failures and the environmental impact of distribution would all be reduced. Copyright © 2012 Elsevier Ltd. All rights reserved.
Validation of the MIMOSA-AURORA-IFDM model chain for policy support: Modeling concentrations of elemental carbon in Flanders

NASA Astrophysics Data System (ADS)

Lefebvre, Wouter; Vercauteren, Jordy; Schrooten, Liesbeth; Janssen, Stijn; Degraeuwe, Bart; Maenhaut, Willy; de Vlieger, Ina; Vankerkom, Jean; Cosemans, Guido; Mensink, Clemens; Veldeman, Nele; Deutsch, Felix; Van Looy, Stijn; Peelaerts, Wim; Lefebre, Filip

2011-12-01

The ability of a complex model chain to simulate elemental carbon (EC) concentrations was examined. The results of the model chain were compared to EC concentration measurements made at several locations, every sixth day. Two measurement campaigns were taken into account, one in 2006-2007 and one in 2008-2009. The model results compare very well for both periods, with an R2 of 0.74, a bias of 0.02 μg m -3 and a RMSE of 0.32 μg m -3. Sensitivity analyses to different meteorology inputs and changing emissions from year to year were performed. The differences between the two measurement periods were also investigated. It is shown that somewhat more than half of these differences is due to meteorology. However, emission changes also play an important role.
Global dynamics in a stoichiometric food chain model with two limiting nutrients.

PubMed

Chen, Ming; Fan, Meng; Kuang, Yang

2017-07-01

Ecological stoichiometry studies the balance of energy and multiple chemical elements in ecological interactions to establish how the nutrient content affect food-web dynamics and nutrient cycling in ecosystems. In this study, we formulate a food chain with two limiting nutrients in the form of a stoichiometric population model. A comprehensive global analysis of the rich dynamics of the targeted model is explored both analytically and numerically. Chaotic dynamic is observed in this simple stoichiometric food chain model and is compared with traditional model without stoichiometry. The detailed comparison reveals that stoichiometry can reduce the parameter space for chaotic dynamics. Our findings also show that decreasing producer production efficiency may have only a small effect on the consumer growth but a more profound impact on the top predator growth. Copyright © 2017 Elsevier Inc. All rights reserved.
A molecular modeling approach to understand the structure and conformation relationship of (GlcpA)Xylan.

PubMed

Guo, Qingbin; Kang, Ji; Wu, Yan; Cui, Steve W; Hu, Xinzhong; Yada, Rickey Y

2015-12-10

The structure and conformation relationships of a heteropolysaccharide (GlcpA)Xylan in terms of various molecular weights, Xylp/GlcpA ratio and the distribution of GlcpA along xylan chain were investigated using computer modeling. The adiabatic contour maps of xylobiose, XylpXylp(GlcpA) and (GlcpA)XylpXylp(GlcpA) indicated that the insertion of the side group (GlcpA) influenced the accessible conformational space of xylobiose molecule. RIS-Metropolis Monte Carlo method indicated that insertion of GlcpA side chain induced a lowering effect of the calculated chain extension at low GlcpA:Xylp ratio (GlcpA:Xylp = 1:3). The chain, however, became extended when the ratio of GlcpA:Xylp above 2/3. It was also shown that the spatial extension of the polymer chains was dependent on the distribution of side chain: the random distribution demonstrated the most flexible structure compared to block and alternative distribution. The present studies provide a unique insight into the dependence of both side chain ratio and distribution on the stiffness and flexibility of various (GlcpA)Xylan molecules. Copyright © 2015. Published by Elsevier Ltd.
SpaceNet: Modeling and Simulating Space Logistics

NASA Technical Reports Server (NTRS)

Lee, Gene; Jordan, Elizabeth; Shishko, Robert; de Weck, Olivier; Armar, Nii; Siddiqi, Afreen

2008-01-01

This paper summarizes the current state of the art in interplanetary supply chain modeling and discusses SpaceNet as one particular method and tool to address space logistics modeling and simulation challenges. Fundamental upgrades to the interplanetary supply chain framework such as process groups, nested elements, and cargo sharing, enabled SpaceNet to model an integrated set of missions as a campaign. The capabilities and uses of SpaceNet are demonstrated by a step-by-step modeling and simulation of a lunar campaign.
Antioxidant potential of curcumin-related compounds studied by chemiluminescence kinetics, chain-breaking efficiencies, scavenging activity (ORAC) and DFT calculations.

PubMed

Slavova-Kazakova, Adriana K; Angelova, Silvia E; Veprintsev, Timur L; Denev, Petko; Fabbri, Davide; Dettori, Maria Antonietta; Kratchanova, Maria; Naumov, Vladimir V; Trofimov, Aleksei V; Vasil'ev, Rostislav F; Delogu, Giovanna; Kancheva, Vessela D

2015-01-01

This study compares the ability to scavenge different peroxyl radicals and to act as chain-breaking antioxidants of monomers related to curcumin (1): dehydrozingerone (2), zingerone (3), (2Z,5E)-ethyl 2-hydroxy-6-(4-hydroxy-3-methoxyphenyl)-4-oxohexa-2,5-dienoate (4), ferulic acid (5) and their corresponding C 2-symmetric dimers 6-9. Four models were applied: model 1 - chemiluminescence (CL) of a hydrocarbon substrate used for determination of the rate constants (k A) of the reactions of the antioxidants with peroxyl radicals; model 2 - lipid autoxidation (lipidAO) used for assessing the chain-breaking antioxidant efficiency and reactivity; model 3 - oxygen radical absorbance capacity (ORAC), which yields the activity against peroxyl radicals generated by an azoinitiator; model 4 - density functional theory (DFT) calculations at UB3LYP/6-31+G(d,p) level, applied to explain the structure-activity relationship. Dimers showed 2-2.5-fold higher values of k A than their monomers. Model 2 gives information about the effects of the side chains and revealed much higher antioxidant activity for monomers and dimers with α,β-unsaturated side chains. Curcumin and 6 in fact are dimers of the same monomer 2. We conclude that the type of linkage between the two "halves" by which the molecule is made up does not exert influence on the antioxidant efficiency and reactivity of these two dimers. The dimers and the monomers demonstrated higher activity than Trolox (10) in aqueous medium (model 3). A comparison of the studied compounds with DL-α-tocopherol (11), Trolox and curcumin is made. All dimers are characterized through lower bond dissociation enthalpies (BDEs) than their monomers (model 4), which qualitatively supports the experimental results.
Large scale shell model study of the evolution of mixed-symmetry states in chains of nuclei around 132Sn

NASA Astrophysics Data System (ADS)

Lo Iudice, N.; Bianco, D.; Andreozzi, F.; Porrino, A.; Knapp, F.

2012-10-01

Large scale shell model calculations based on a new diagonalization algorithm are performed in order to investigate the mixed symmetry states in chains of nuclei in the proximity of N=82. The resulting spectra and transitions are in agreement with the experiments and consistent with the scheme provided by the interacting boson model.
Identification of the significant factors in food safety using global sensitivity analysis and the accept-and-reject algorithm: application to the cold chain of ham.

PubMed

Duret, Steven; Guillier, Laurent; Hoang, Hong-Minh; Flick, Denis; Laguerre, Onrawee

2014-06-16

Deterministic models describing heat transfer and microbial growth in the cold chain are widely studied. However, it is difficult to apply them in practice because of several variable parameters in the logistic supply chain (e.g., ambient temperature varying due to season and product residence time in refrigeration equipment), the product's characteristics (e.g., pH and water activity) and the microbial characteristics (e.g., initial microbial load and lag time). This variability can lead to different bacterial growth rates in food products and has to be considered to properly predict the consumer's exposure and identify the key parameters of the cold chain. This study proposes a new approach that combines deterministic (heat transfer) and stochastic (Monte Carlo) modeling to account for the variability in the logistic supply chain and the product's characteristics. The model generates a realistic time-temperature product history , contrary to existing modeling whose describe time-temperature profile Contrary to existing approaches that use directly a time-temperature profile, the proposed model predicts product temperature evolution from the thermostat setting and the ambient temperature. The developed methodology was applied to the cold chain of cooked ham including, the display cabinet, transport by the consumer and the domestic refrigerator, to predict the evolution of state variables, such as the temperature and the growth of Listeria monocytogenes. The impacts of the input factors were calculated and ranked. It was found that the product's time-temperature history and the initial contamination level are the main causes of consumers' exposure. Then, a refined analysis was applied, revealing the importance of consumer behaviors on Listeria monocytogenes exposure. Copyright © 2014. Published by Elsevier B.V.
Gas-Grain Models for Interstellar Anion Chemistry

NASA Technical Reports Server (NTRS)

Cordiner, M. A.; Charnely, S. B.

2012-01-01

Long-chain hydrocarbon anions C(sub n) H(-) (n = 4, 6, 8) have recently been found to be abundant in a variety of interstellar clouds. In order to explain their large abundances in the denser (prestellar/protostellar) environments, new chemical models are constructed that include gas-grain interactions. Models including accretion of gas-phase species onto dust grains and cosmic-ray-induced desorption of atoms are able to reproduce the observed anion-to-neutral ratios, as well as the absolute abundances of anionic and neutral carbon chains, with a reasonable degree of accuracy. Due to their destructive effects, the depletion of oxygen atoms onto dust results in substantially greater polyyne and anion abundances in high-density gas (with n(sub H2) approx > / cubic cm). The large abundances of carbon-chain-bearing species observed in the envelopes of protostars such as L1527 can thus be explained without the need for warm carbon-chain chemistry. The C6H(-) anion-to-neutral ratio is found to be most sensitive to the atomic O and H abundances and the electron density. Therefore, as a core evolves, falling atomic abundances and rising electron densities are found to result in increasing anion-to-neutral ratios. Inclusion of cosmic-ray desorption of atoms in high-density models delays freeze-out, which results in a more temporally stable anion-to-neutral ratio, in better agreement with observations. Our models include reactions between oxygen atoms and carbon-chain anions to produce carbon-chain-oxide species C6O, C7O, HC6O, and HC7O, the abundances of which depend on the assumed branching ratios for associative electron detachment
Analysis and design of a second-order digital phase-locked loop

NASA Technical Reports Server (NTRS)

Blasche, P. R.

1979-01-01

A specific second-order digital phase-locked loop (DPLL) was modeled as a first-order Markov chain with alternatives. From the matrix of transition probabilities of the Markov chain, the steady-state phase error of the DPLL was determined. In a similar manner the loop's response was calculated for a fading input. Additionally, a hardware DPLL was constructed and tested to provide a comparison to the results obtained from the Markov chain model. In all cases tested, good agreement was found between the theoretical predictions and the experimental data.

Information Entropy Production of Maximum Entropy Markov Chains from Spike Trains

NASA Astrophysics Data System (ADS)

Cofré, Rodrigo; Maldonado, Cesar

2018-01-01

We consider the maximum entropy Markov chain inference approach to characterize the collective statistics of neuronal spike trains, focusing on the statistical properties of the inferred model. We review large deviations techniques useful in this context to describe properties of accuracy and convergence in terms of sampling size. We use these results to study the statistical fluctuation of correlations, distinguishability and irreversibility of maximum entropy Markov chains. We illustrate these applications using simple examples where the large deviation rate function is explicitly obtained for maximum entropy models of relevance in this field.
Research on the performance evaluation of agricultural products supply chain integrated operation

NASA Astrophysics Data System (ADS)

Jiang, Jiake; Wang, Xifu; Liu, Yang

2017-04-01

The agricultural product supply chain integrated operation can ensure the quality and efficiency of agricultural products, and achieve the optimal goal of low cost and high service. This paper establishes a performance evaluation index system of agricultural products supply chain integration operation based on the development status of agricultural products and SCOR, BSC and KPI model. And then, we constructing rough set theory and BP neural network comprehensive evaluation model with the aid of Rosetta and MATLAB tools and the case study is about the development of agricultural products integrated supply chain in Jing-Jin-Ji region. And finally, we obtain the corresponding performance results, and give some improvement measures and management recommendations to the managers.
Flexible histone tails in a new mesoscopic oligonucleosome model.

PubMed

Arya, Gaurav; Zhang, Qing; Schlick, Tamar

2006-07-01

We describe a new mesoscopic model of oligonucleosomes that incorporates flexible histone tails. The nucleosome cores are modeled using the discrete surface-charge optimization model, which treats the nucleosome as an electrostatic surface represented by hundreds of point charges; the linker DNAs are treated using a discrete elastic chain model; and the histone tails are modeled using a bead/chain hydrodynamic approach as chains of connected beads where each bead represents five protein residues. Appropriate charges and force fields are assigned to each histone chain so as to reproduce the electrostatic potential, structure, and dynamics of the corresponding atomistic histone tails at different salt conditions. The dynamics of resulting oligonucleosomes at different sizes and varying salt concentrations are simulated by Brownian dynamics with complete hydrodynamic interactions. The analyses demonstrate that the new mesoscopic model reproduces experimental results better than its predecessors, which modeled histone tails as rigid entities. In particular, our model with flexible histone tails: correctly accounts for salt-dependent conformational changes in the histone tails; yields the experimentally obtained values of histone-tail mediated core/core attraction energies; and considers the partial shielding of electrostatic repulsion between DNA linkers as a result of the spatial distribution of histone tails. These effects are crucial for regulating chromatin structure but are absent or improperly treated in models with rigid histone tails. The development of this model of oligonucleosomes thus opens new avenues for studying the role of histone tails and their variants in mediating gene expression through modulation of chromatin structure.
Chain Dynamics in Magnetorheological Suspensions

NASA Technical Reports Server (NTRS)

Gast, A. P.; Furst, E. M.

1999-01-01

Magnetorheological (MR) suspensions are composed of colloidal particles which acquire dipole moments when subjected to an external magnetic field. At sufficient field strengths and concentrations, the dipolar particles rapidly aggregate to form long chains. Subsequent lateral cross-linking of the dipolar chains is responsible for a rapid liquid-to-solid-like rheological transition. The unique, magnetically-activated rheological properties of MR suspensions make them ideal for interfacing mechanical systems to electronic controls. Additionally, the ability to experimentally probe colloidal suspensions interacting through tunable anisotropic potentials is of fundamental interest. Our current experimental work has focused on understanding the fluctuations of dipolar chains. It has been proposed by Halsey and Toor (HT) that the strong Landau-Peierls thermal fluctuations of dipolar chains could be responsible for long-range attractions between chains. Such interactions will govern the long-time relaxation of MR suspensions. We have synthesized monodisperse neutrally buoyant MR suspensions by density matching stabilized ferrofluid emulsion droplets with D2O. This allows us to probe the dynamics of the dipolar chains using light scattering without gravitational, interfacial, and polydispersity effects to resolve the short-wavelength dynamics of the dipolar chains. We used diffusing wave spectroscopy to measure these dynamics. The particle displacements at short times that show an independence to the field strength, but at long times exhibit a constrained, sub-diffusive motion that slows as the dipole strength is increased. The experiments are in good qualitative agreement with Brownian dynamics simulations of dipolar chains. Although there have been several important and detailed studies of the structure and interactions in MR suspensions, there has not been conclusive evidence that supports or contradicts the HT model prediction that long-range interactions exist between fluctuating chains of dipolar particles. Resolving this issue would contribute greatly to the understanding of these interesting and important materials. We have begun to test the predictions of the HT model by both examining the dynamics of individual chains and by measuring the forces between dipolar chains directly to accurately and quantitatively assess the interactions that they experience. To do so, we employ optical trapping techniques and video-microscopy to manipulate and observe our samples on the microscopic level. With these techniques, it is possible to observe chains that are fluctuating freely in three-dimensions, independent of interfacial effects. More importantly, we are able to controllably observe the interactions of two chains at various separations to measure the force-distance profile. The techniques also allow us to study the mechanical properties of individual chains and chain clusters. Our work to this point has focused on reversibly-formed dipolar chains due to field induced dipoles where the combination of this chaining, the dipolar forces, and the hydrodynamic interactions that dictate the rheology of the suspensions. One can envision, however, many situations where optical, electronic, or rheological behavior may be optimized with magneto-responsive anisotropic particles. Chains of polarizable particles may have the best properties as they can coil and flex in the absence of a field and stiffen and orient when a field is applied. We have recently demonstrated a synthesis of stable, permanent paramagnetic chains by both covalently and physically linking paramagnetic colloidal particles. The method employed allows us to create monodisperse chains of controlled length. We observed the stability, field-alignment, and rigidity of this new class of materials. The chains may exhibit unique rheological properties in an applied magnetic field over isotropic suspensions of paramagnetic particles. They are also useful rheological models as bead-spring systems. These chains form the basis for our current experiments with optical traps.
Evaluating Opportunities to Improve Material and Energy Impacts in Commodity Supply Chains.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hanes, Rebecca J.; Carpenter, Alberta

When evaluated at the process level, next-generation technologies may be more energy and emissions intensive than current technology. However, many advanced technologies have the potential to reduce material and energy consumption in upstream or downstream processing stages. In order to fully understand the benefits and consequences of technology deployment, next-generation technologies should be evaluated in context, as part of a supply chain. This work presents the Material Flows through Industry (MFI) scenario modeling tool. The MFI tool is a cradle-to-gate linear network model of the U.S. industrial sector that can model a wide range of manufacturing scenarios, including changes inmore » production technology, increases in industrial energy efficiency, and substitution between functionally equivalent materials. The MFI tool was developed to perform supply chain scale analyses in order to quantify the impacts and benefits of next-generation technologies and materials at that scale. For the analysis presented in this paper, the MFI tool is utilized to explore a case study comparing a steel supply chain to the supply chains of several functionally equivalent materials. Several of the alternatives to the baseline steel supply chain include next-generation production technologies and materials. Results of the case study show that aluminum production scenarios can out-perform the steel supply chain by using either an advanced smelting technology or an increased aluminum recycling rate. The next-generation material supply chains do not perform as well as either aluminum or steel, but may offer additional use phase reductions in energy and emissions that are outside the scope of the MFI tool. Future work will combine results from the MFI tool with a use phase analysis.« less
Tunable evolutions of shock absorption and energy partitioning in magnetic granular chains

NASA Astrophysics Data System (ADS)

Leng, Dingxin; Liu, Guijie; Sun, Lingyu

2018-01-01

In this paper, we investigate the tunable characteristics of shock waves propagating in one-dimensional magnetic granular chains at various chain lengths and magnetic flux densities. According to the Hertz contact theory and Maxwell principle, a discrete element model with coupling elastic and field-induced interaction potentials of adjacent magnetic grains is proposed. We also present hard-sphere approximation analysis to describe the energy partitioning features of magnetic granular chains. The results demonstrate that, for a fixed magnetic field strength, when the chain length is greater than two times of the wave width of the solitary wave, the chain length has little effect on the output energy of the system; for a fixed chain length, the shock absorption and energy partitioning features of magnetic granular chains are remarkably influenced by varying magnetic flux densities. This study implies that the magnetic granular chain is potential to construct adaptive shock absorption components for impulse mitigation.
Critical excitation spectrum of a quantum chain with a local three-spin coupling.

PubMed

McCabe, John F; Wydro, Tomasz

2011-09-01

Using the phenomenological renormalization group (PRG), we evaluate the low-energy excitation spectrum along the critical line of a quantum spin chain having a local interaction between three Ising spins and longitudinal and transverse magnetic fields, i.e., a Turban model. The low-energy excitation spectrum found with the PRG agrees with the spectrum predicted for the (D(4),A(4)) conformal minimal model under a nontrivial correspondence between translations at the critical line and discrete lattice translations. Under this correspondence, the measurements confirm a prediction that the critical line of this quantum spin chain and the critical point of the two-dimensional three-state Potts model are in the same universality class.
The P-chain: relating sentence production and its disorders to comprehension and acquisition

PubMed Central

Dell, Gary S.; Chang, Franklin

2014-01-01

This article introduces the P-chain, an emerging framework for theory in psycholinguistics that unifies research on comprehension, production and acquisition. The framework proposes that language processing involves incremental prediction, which is carried out by the production system. Prediction necessarily leads to prediction error, which drives learning, including both adaptive adjustment to the mature language processing system as well as language acquisition. To illustrate the P-chain, we review the Dual-path model of sentence production, a connectionist model that explains structural priming in production and a number of facts about language acquisition. The potential of this and related models for explaining acquired and developmental disorders of sentence production is discussed. PMID:24324238
The P-chain: relating sentence production and its disorders to comprehension and acquisition.

PubMed

Dell, Gary S; Chang, Franklin

2014-01-01

This article introduces the P-chain, an emerging framework for theory in psycholinguistics that unifies research on comprehension, production and acquisition. The framework proposes that language processing involves incremental prediction, which is carried out by the production system. Prediction necessarily leads to prediction error, which drives learning, including both adaptive adjustment to the mature language processing system as well as language acquisition. To illustrate the P-chain, we review the Dual-path model of sentence production, a connectionist model that explains structural priming in production and a number of facts about language acquisition. The potential of this and related models for explaining acquired and developmental disorders of sentence production is discussed.
Governance on the Drug Supply Chain via Gcoin Blockchain.

PubMed

Tseng, Jen-Hung; Liao, Yen-Chih; Chong, Bin; Liao, Shih-Wei

2018-05-23

As a trust machine, blockchain was recently introduced to the public to provide an immutable, consensus based and transparent system in the Fintech field. However, there are ongoing efforts to apply blockchain to other fields where trust and value are essential. In this paper, we suggest Gcoin blockchain as the base of the data flow of drugs to create transparent drug transaction data. Additionally, the regulation model of the drug supply chain could be altered from the inspection and examination only model to the surveillance net model, and every unit that is involved in the drug supply chain would be able to participate simultaneously to prevent counterfeit drugs and to protect public health, including patients.
Antiresonance induced spin-polarized current generation

NASA Astrophysics Data System (ADS)

Yin, Sun; Min, Wen-Jing; Gao, Kun; Xie, Shi-Jie; Liu, De-Sheng

2011-12-01

According to the one-dimensional antiresonance effect (Wang X R, Wang Y and Sun Z Z 2003 Phys. Rev. B 65 193402), we propose a possible spin-polarized current generation device. Our proposed model consists of one chain and an impurity coupling to the chain. The energy level of the impurity can be occupied by an electron with a specific spin, and the electron with such a spin is blocked because of the antiresonance effect. Based on this phenomenon our model can generate the spin-polarized current flowing through the chain due to different polarization rates. On the other hand, the device can also be used to measure the generated spin accumulation. Our model is feasible with today's technology.
Research on manufacturing service behavior modeling based on block chain theory

NASA Astrophysics Data System (ADS)

Zhao, Gang; Zhang, Guangli; Liu, Ming; Yu, Shuqin; Liu, Yali; Zhang, Xu

2018-04-01

According to the attribute characteristics of processing craft, the manufacturing service behavior is divided into service attribute, basic attribute, process attribute, resource attribute. The attribute information model of manufacturing service is established. The manufacturing service behavior information is successfully divided into public and private domain. Additionally, the block chain technology is introduced, and the information model of manufacturing service based on block chain principle is established, which solves the problem of sharing and secreting information of processing behavior, and ensures that data is not tampered with. Based on the key pairing verification relationship, the selective publishing mechanism for manufacturing information is established, achieving the traceability of product data, guarantying the quality of processing quality.
Indexed semi-Markov process for wind speed modeling.

NASA Astrophysics Data System (ADS)

Petroni, F.; D'Amico, G.; Prattico, F.

2012-04-01

The increasing interest in renewable energy leads scientific research to find a better way to recover most of the available energy. Particularly, the maximum energy recoverable from wind is equal to 59.3% of that available (Betz law) at a specific pitch angle and when the ratio between the wind speed in output and in input is equal to 1/3. The pitch angle is the angle formed between the airfoil of the blade of the wind turbine and the wind direction. Old turbine and a lot of that actually marketed, in fact, have always the same invariant geometry of the airfoil. This causes that wind turbines will work with an efficiency that is lower than 59.3%. New generation wind turbines, instead, have a system to variate the pitch angle by rotating the blades. This system able the wind turbines to recover, at different wind speed, always the maximum energy, working in Betz limit at different speed ratios. A powerful system control of the pitch angle allows the wind turbine to recover better the energy in transient regime. A good stochastic model for wind speed is then needed to help both the optimization of turbine design and to assist the system control to predict the value of the wind speed to positioning the blades quickly and correctly. The possibility to have synthetic data of wind speed is a powerful instrument to assist designer to verify the structures of the wind turbines or to estimate the energy recoverable from a specific site. To generate synthetic data, Markov chains of first or higher order are often used [1,2,3]. In particular in [1] is presented a comparison between a first-order Markov chain and a second-order Markov chain. A similar work, but only for the first-order Markov chain, is conduced by [2], presenting the probability transition matrix and comparing the energy spectral density and autocorrelation of real and synthetic wind speed data. A tentative to modeling and to join speed and direction of wind is presented in [3], by using two models, first-order Markov chain with different number of states, and Weibull distribution. All this model use Markov chains to generate synthetic wind speed time series but the search for a better model is still open. Approaching this issue, we applied new models which are generalization of Markov models. More precisely we applied semi-Markov models to generate synthetic wind speed time series. In a previous work we proposed different semi-Markov models, showing their ability to reproduce the autocorrelation structures of wind speed data. In that paper we showed also that the autocorrelation is higher with respect to the Markov model. Unfortunately this autocorrelation was still too small compared to the empirical one. In order to overcome the problem of low autocorrelation, in this paper we propose an indexed semi-Markov model. More precisely we assume that wind speed is described by a discrete time homogeneous semi-Markov process. We introduce a memory index which takes into account the periods of different wind activities. With this model the statistical characteristics of wind speed are faithfully reproduced. The wind is a very unstable phenomenon characterized by a sequence of lulls and sustained speeds, and a good wind generator must be able to reproduce such sequences. To check the validity of the predictive semi-Markovian model, the persistence of synthetic winds were calculated, then averaged and computed. The model is used to generate synthetic time series for wind speed by means of Monte Carlo simulations and the time lagged autocorrelation is used to compare statistical properties of the proposed models with those of real data and also with a time series generated though a simple Markov chain. [1] A. Shamshad, M.A. Bawadi, W.M.W. Wan Hussin, T.A. Majid, S.A.M. Sanusi, First and second order Markov chain models for synthetic generation of wind speed time series, Energy 30 (2005) 693-708. [2] H. Nfaoui, H. Essiarab, A.A.M. Sayigh, A stochastic Markov chain model for simulating wind speed time series at Tangiers, Morocco, Renewable Energy 29 (2004) 1407-1418. [3] F. Youcef Ettoumi, H. Sauvageot, A.-E.-H. Adane, Statistical bivariate modeling of wind using first-order Markov chain and Weibull distribution, Renewable Energy 28 (2003) 1787-1802.
A new bead-spring model for simulation of semi-flexible macromolecules

NASA Astrophysics Data System (ADS)

Saadat, Amir; Khomami, Bamin

2016-11-01

A bead-spring model for semi-flexible macromolecules is developed to overcome the deficiencies of the current coarse-grained bead-spring models. Specifically, model improvements are achieved through incorporation of a bending potential. The new model is designed to accurately describe the correlation along the backbone of the chain, segmental length, and force-extension behavior of the macromolecule even at the limit of 1 Kuhn step per spring. The relaxation time of different Rouse modes is used to demonstrate the capabilities of the new model in predicting chain dynamics.
The use of simple reparameterizations to improve the efficiency of Markov chain Monte Carlo estimation for multilevel models with applications to discrete time survival models.

PubMed

Browne, William J; Steele, Fiona; Golalizadeh, Mousa; Green, Martin J

2009-06-01

We consider the application of Markov chain Monte Carlo (MCMC) estimation methods to random-effects models and in particular the family of discrete time survival models. Survival models can be used in many situations in the medical and social sciences and we illustrate their use through two examples that differ in terms of both substantive area and data structure. A multilevel discrete time survival analysis involves expanding the data set so that the model can be cast as a standard multilevel binary response model. For such models it has been shown that MCMC methods have advantages in terms of reducing estimate bias. However, the data expansion results in very large data sets for which MCMC estimation is often slow and can produce chains that exhibit poor mixing. Any way of improving the mixing will result in both speeding up the methods and more confidence in the estimates that are produced. The MCMC methodological literature is full of alternative algorithms designed to improve mixing of chains and we describe three reparameterization techniques that are easy to implement in available software. We consider two examples of multilevel survival analysis: incidence of mastitis in dairy cattle and contraceptive use dynamics in Indonesia. For each application we show where the reparameterization techniques can be used and assess their performance.
Predictors of chain acquisition among independent dialysis facilities.

PubMed

Pozniak, Alyssa S; Hirth, Richard A; Banaszak-Holl, Jane; Wheeler, John R C

2010-04-01

To determine the predictors of chain acquisition among independent dialysis providers. Retrospective facility-level data combined from CMS Cost Reports, Medical Evidence Forms, Annual Facility Surveys, and claims for 1996-2003. Independent dialysis facilities' probability of acquisition by a dialysis chain (overall and by chain size) was estimated using a discrete time hazard rate model, controlling for financial and clinical performance, practice patterns, market factors, and other facility characteristics. The sample includes all U.S. freestanding dialysis facilities that report not being chain affiliated for at least 1 year between 1997 and 2003. Above-average costs and better quality outcomes are significant determinants of dialysis chain acquisition. Facilities in larger markets were more likely to be acquired by a chain. Furthermore, small dialysis chains have different acquisition strategies than large chains. Dialysis chains appear to employ a mix of turn-around and cream-skimming strategies. Poor financial health is a predictor of chain acquisition as in other health care sectors, but the increased likelihood of chain acquisition among higher quality facilities is unique to the dialysis industry. Significant differences among predictors of acquisition by small and large chains reinforce the importance of using a richer classification for chain status.
Compression induced phase transition of nematic brush: A mean-field theory study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tang, Jiuzhou; Zhang, Xinghua, E-mail: zhangxh@bjtu.edu.cn; Yan, Dadong, E-mail: yandd@bnu.edu.cn

2015-11-28

Responsive behavior of polymer brush to the external compression is one of the most important characters for its application. For the flexible polymer brush, in the case of low grafting density, which is widely studied by the Gaussian chain model based theory, the compression leads to a uniform deformation of the chain. However, in the case of high grafting density, the brush becomes anisotropic and the nematic phase will be formed. The normal compression tends to destroy the nematic order, which leads to a complex responsive behaviors. Under weak compression, chains in the nematic brush are buckled, and the bendingmore » energy and Onsager interaction give rise to the elasticity. Under deep compression, the responsive behaviors of the nematic polymer brush depend on the chain rigidity. For the compressed rigid polymer brush, the chains incline to re-orientate randomly to maximize the orientational entropy and its nematic order is destroyed. For the compressed flexible polymer brush, the chains incline to fold back to keep the nematic order. A buckling-folding transition takes place during the compressing process. For the compressed semiflexible brush, the chains are collectively tilted to a certain direction, which leads to the breaking of the rotational symmetry in the lateral plane. These responsive behaviors of nematic brush relate to the properties of highly frustrated worm-like chain, which is hard to be studied by the traditional self-consistent field theory due to the difficulty to solve the modified diffusion equation. To overcome this difficulty, a single chain in mean-field theory incorporating Monte Carlo simulation and mean-field theory for the worm-like chain model is developed in present work. This method shows high performance for entire region of chain rigidity in the confined condition.« less
A supply chain approach to biochar systems [Chapter 2

Treesearch

Nathaniel M. Anderson; Richard D. Bergman; Deborah S. Page-Dumroese

2017-01-01

Biochar systems are designed to meet four related primary objectives: improve soils, manage waste, generate renewable energy, and mitigate climate change. Supply chain models provide a holistic framework for examining biochar systems with an emphasis on product life cycle and end use. Drawing on concepts in supply chain management and engineering, this chapter presents...
Prediction of Solution Properties of Flexible-Chain Polymers: A Computer Simulation Undergraduate Experiment

ERIC Educational Resources Information Center

de la Torre, Jose Garcia; Cifre, Jose G. Hernandez; Martinez, M. Carmen Lopez

2008-01-01

This paper describes a computational exercise at undergraduate level that demonstrates the employment of Monte Carlo simulation to study the conformational statistics of flexible polymer chains, and to predict solution properties. Three simple chain models, including excluded volume interactions, have been implemented in a public-domain computer…
Verifying the Hanging Chain Model

ERIC Educational Resources Information Center

Karls, Michael A.

2013-01-01

The wave equation with variable tension is a classic partial differential equation that can be used to describe the horizontal displacements of a vertical hanging chain with one end fixed and the other end free to move. Using a web camera and TRACKER software to record displacement data from a vibrating hanging chain, we verify a modified version…

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