Dissimilar Systems Research Articles

Theory of gastric CO2 ventilation and its control during respiratory acidosis: Implications for central chemosensitivity, pH regulation, and diseases causing chronic CO2 retention

The theory of gastric CO(2) ventilation describes a previously unrecognized reflex mechanism controlled by neurons in the caudal solitary complex (cSC) for non-alveolar elimination of systemic CO(2) during respiratory acidosis. Neurons in the cSC, which is a site of CO(2) chemosensitivity for cardiorespiratory control, also control various gastroesophageal reflexes that remove CO(2) from blood. CO(2) is consumed in the production of gastric acid and bicarbonate in the gastric epithelium and then reconstituted as CO(2) in the stomach lumen from the reaction between H(+) and HCO(3)(-). Respiratory acidosis and gastric CO(2) distension induce cSC/vagovagal mediated transient relaxations of the lower esophageal sphincter to vent gastric CO(2) upwards by bulk flow along an abdominal-to-esophageal (=intrapleural) pressure gradient the magnitude of which increases during abdominal (gastric) compression caused by increased contractions of respiratory muscles. Esophageal distension induces cSC/nucleus ambiguus/vagovagal reflex relaxation of the upper esophageal sphincter and CO(2) is vented into the pharynx and mixed with pulmonary gas during expiration or, alternatively, during eructation. It is proposed that gastric CO(2) ventilation provides explanations for (1) the postprandial increase in expired CO(2) and (2) the negative P(blood - expired)CO₂difference that occurs with increased inspired CO(2). Furthermore, it is postulated that gastric CO(2) ventilation and alveolar CO(2) ventilation are coordinated under dual control by CO(2) chemosensitive neurons in the cSC. This new theory, therefore, presupposes a level of neural control and coordination between two previously presumed dissimilar organ systems and supports the notion that different sites of CO(2) chemosensitivity address different aspects of whole body pH regulation. Consequently, not all sites of central chemosensitivity are equal regarding the mechanism(s) activated for CO(2) elimination. A distributed CO(2) chemosensitive network-at least nine different areas in the CNS, including the cSC, have been reported to date-may reflect the complexity and dynamic nature of the fundamental neural circuitry required to achieve CO(2)/pH regulation across multiple organ systems under various states of arousal, oxygenation, pH status, and redox state. Moreover, coordination of respiratory and digestive control networks through the cSC could also account for the frequent co-expression of pulmonary diseases that cause chronic respiratory acidosis (and overstimulation of cSC neurons) with peptic ulcer disease or gastroesophageal reflux disease.

Dissimilar chromatographic systems to indicate and identify antioxidants from Mallotus species

The genus of Mallotus contains several species commonly used as traditional medicines in oriental countries. A data set containing 39 Mallotus samples, differing in species, cultivation conditions, harvest season and/or part of the plant was used to develop fingerprints on two dissimilar chromatographic systems. An exploratory analysis with principal component analysis (PCA) was performed on both data sets individually. The results were also combined to obtain additional information on the unknown samples included in the data set. Furthermore, the antioxidant activity of the samples was measured and modelled as a function of the fingerprints using the orthogonal projections to latent structures (O-PLS) technique. The regression coefficients of the models were studied to indicate the peaks potentially responsible for the antioxidant activity. The indicated peaks were analyzed and identified by HPLC coupled to mass spectrometry (HPLC–MS). Because of the complexity of biological samples, it was aspired to separate co-eluting components based on the significant difference in chromatographic selectivity on the dissimilar systems and consequently obtain additional, complementary information on the contribution of the individual components to the antioxidant activity. The results illustrate the potential use of dissimilar chromatographic systems. Several initially co-eluting compounds could be separated on the dissimilar system. The corresponding regression coefficients provided complementary information on the potential antioxidant activity of the separated compounds.

An alternative frame‐shear wall model: continuum formulation

SUMMARYThe basic assumption of the analysis of wall‐frame structures is that two dissimilar structural systems, deforming in shear and flexural modes, are constrained to act together. The same set of boundary conditions is also assumed to be applicable to both types of components. An inconsistency arises when the rotation at the lower end of the combined beam is assumed to be zero because this boundary condition is applicable only to the flexural component of deformation. For the shear component that is related to the slope of the elastic curve to calculate the force, this assumption results in zero base shear force. In this study, a modified theory is developed on the premise that a frame‐wall system can be separated into two substructures that lie above and below the point of counter‐flexure in the base story columns. Except for a modification to include the effects of link beams, the generalized continuum approach is employed to derive the governing differential equation of the upper substructure. The bottom substructure is used to transmit the applied base boundary conditions to the continuum model, thus allowing a more accurate shear force calculation for each of the components. Comparisons of results calculated from this artifice with other formulations prove the superiority of the proposed improvement. Copyright © 2010 John Wiley & Sons, Ltd.

Prediction and interpretation of the antioxidant capacity of green tea from dissimilar chromatographic fingerprints

Previously, multivariate calibration techniques have been successfully applied to model and predict the antioxidant activity of green tea from its chromatographic fingerprint. Since the selectivity differences between dissimilar chromatographic systems have already been valuably used in several applications, in this paper it is studied whether combining the complementary information contained in two dissimilar fingerprints can improve the predictive capacity of the multivariate calibration model. The simplest way of combining the data is concatenating both fingerprints for each sample. The resulting matrix can then be subjected to Orthogonal Projections to Latent Structures (O-PLS). Unfortunately, this approach resulted in a more complex model with a prediction error of about the average of the errors obtained with the individual fingerprints. Secondly, only the peaks with high loading and low orthogonal loading from both chromatograms were included in the O-PLS model. This resulted in a reduced complexity, but not in better predictions, probably due to a lack of complementarity of the information concerning the antioxidant capacity. Finally, the concatenated fingerprints were subjected to stepwise multiple linear regression (MLR) in order to build a model based on the variables most correlated with the antioxidant capacity. The obtained prediction error was lower than those of both previous approaches, but still higher than the error of the model based on a single analysis. This is probably again caused by a lack of complementarity in the variables. Nevertheless, it was advantageous to develop fingerprints on dissimilar system, because it enables to choose the most suited chromatographic profile to build a multivariate calibration model for the considered purpose. In contrast to what was expected, the study showed that the most simple (so the worst separated) fingerprints resulted in the best predictions. On the other hand, a more complex fingerprint in which more compounds are separated is still important to improve the interpretability of the model.

Service users' views of eating disorder services: An international comparison

To perform a United States-United Kingdom cross-national comparison of service users' perspectives on eating disorder (ED) treatments and services. Qualitative, exploratory study. One hundred forty-four US and 150 UK ED service users completed a questionnaire developed by the Academy for Eating Disorders. Data were analyzed using conventional content analysis. Both samples identified the following as essential aspects of care: good therapeutic relationship, holistic approach, individual psychotherapy/counseling, specialized treatment, client-centered care, and support. In the US sample, the main concerns involved lack of financial accessibility to services and problems with insurance coverage. In the UK sample, lack of and inequity of availability of services were highlighted and three main barriers to accessing care were identified. US and UK service users' views suggest that neither country provides early intervention and comprehensive care for EDs at present, although due to dissimilar health care systems the barriers to care differ.

A multi-scale approach for investigation of interfacial delamination in electronic packages

Interfacial delamination, due to the presence of dissimilar material systems, is one of the primary concerns in electronic package design. Continuum models such as J-integral have been developed to evaluate potential delamination by defining a pre-defined crack at selected interface in the package. The interface is modeled as a discontinuity across the mating material layer. However, at molecular level, the mating materials are held together by a force field which is prescribed by their chemical structures. Molecular dynamics (MD) simulation is an effective tool used to model such force fields. The MD model can be used to simulate the reaction of the interfacial force field under external loading and the result can be utilized to characterize the material properties at the interface. The material properties at the interface are not necessarily consistent with those of the bulk materials forming the interface. The present study is focused on incorporating material behavior at the interface derived from MD simulations into the continuum model. The MD simulations were conducted to construct the constitutive relation of interface under the external loading. The constitutive relations from MD simulations in the form of a traction–displacement plot were introduced into the cohesive zone model to study the constitutive response of interface under the external loading, which is traversed across the length scale from nanoscale to macroscale.

Practice research

Measles mumps and rubella (MMR) are serious infectiousdiseases, which can be prevented by effective immunisation(MMR vaccine) of the young population. However, if immu-nisation coverage against MMR is less than the 95% recom- mended by World Health Organization, measles could become an epidemic, resulting in a high number of suscepti- ble children getting the disease.1In 2005, vaccine uptake in UK was 82%, 2 but in Libya, where the Wakefield study had not been publicised widely,3 the uptake was 97%.2 The aim of this research was to explore the factors that influenced the Libyan and the British parents’ decision to vaccinate their children with MMR, how they determined risk-taking and decision-making processes, and how these were shaped by different sociocultural context (having very dissimilar health systems, educational systems and socialstructure).

A Review of FSW Research on Dissimilar Metal and Alloy Systems

This review summarizes friction-stir welding (FSW) research over a period of a decade and a half, involving 18 different same materials FSW reference systems, and the FSW of 25 different, dissimilar materials systems. These are summarized in tables. The FSW of dissimilar materials systems is distinguished from same materials systems FSW by the formation of complex, intercalated vortex, and related flow patterns. These intercalated, lamellar-like patterns represent solid-state flow by dynamic recrystallization (DRX) which facilitates unrecrystallized, block flow in the DRX regime. A detailed characterization of representative systems involving optical and transmission electron microscopy is also presented. Residual microindentation hardness or other hardness measured across the weld face provides comparative performance signatures for the same material FSW systems in contrast to the dissimilar FSW systems. Hardness fluctuations or complex spikes occurring in the dissimilar systems are skewed from the weld centerline and are shifted when the tool rotation direction changes or the advancing side is reversed.

Software Reuse in the Evolution of an E-Commerce System: A Case Study

The engineering and reengineering of software interfaces between dissimilar systems is a process that is constantly evolving with respect to the techniques applied and the lessons learned from their use. While many strategies and models for such development exist today, there are times that no single defined approach appropriately fits the requirement for all real-world situations. This is particularly true of the integration and sharing of data among modern e-commerce software systems and large, mature multi-channel legacy systems. This paper details the initial and subsequent evolutions of one such e-commerce software interface. Lessons learned from each evolution were used to improve upon the next, ultimately resulting in a highly maintainable and scalable product.

Study of rheological behaviours of electrostatic thermoset powder coatings

AbstractThe use of dynamic viscosity/time (temperature) cure curves is seen as a powerful technique to quantify formulation and resin design parameters. The behaviour of different thermoset powder coating systems, epoxy/polyester (50/50, 40/60 and 30/70) as well as the impact of the filler, the curing temperature and the frequency upon gel-time have been examined based upon the rheological measurements and compared with PE/TGIC systems. Two disparate methodologies have been utilized to determine gel-time. The behaviour of dissimilar systems bearing different formulations has been compared by means of the non-isothermal DSC test. The effects of resin percentage and the formulation on physical and mechanical properties of coating have been studied.

Drug impurity profiling: Method optimization on dissimilar chromatographic systems: Part I: pH optimization of the aqueous phase

The use of dissimilar chromatographic systems in drug impurity profiling can be very advantageous. Screening a new-drug impurity mixture on those systems not only enhances the chance that all impurities are revealed, but also allows choosing a suited system for further method development. In this paper several strategies were evaluated to predict the optimal pH (of the buffer used in the mobile phase) from the screening results. Four or five dissimilar stationary phases were screened at four pH values (between 2.5 and 9.4), in order to obtain maximal information about the composition of the sample and to select one column for the subsequent optimization. Different linear models (straight lines, 2nd and 3rd degree polynomials) based on these experiments were tested for their ability to predict the retention times ( t R ) of the impurities at intermediate pH values. The predicted t R values were then used to calculate minimal resolutions and eventually to select an optimal pH at which the highest minimal resolution is predicted. None of the applied models is accurate enough to predict correctly which peaks are worst separated at the indicated optimal pH. However, the best strategy (applying a second degree polynomial describing the t R measured at 3 consecutive screening pH values) did succeed in indicating an optimal pH at which a good separation of the impurities is obtained. Unfortunately, the resulting separation quality is not or only slightly better than the best separation obtained during screening. Therefore, it can be concluded that the most (time-) efficient approach to develop an impurity profile of a new drug is to screen it on four or five dissimilar columns at four different pH values and to retain the best screening conditions (without making predictions for intermediate conditions) for further optimization of the organic modifier composition of the mobile phase, and occasionally the temperature and the gradient. This is at least the case when the profiles have a complexity similar to those studied.

Accommodation at the interface of highly dissimilar semiconductor/oxide epitaxial systems

An equilibrium model describing accommodation at epitaxial interfaces of highly dissimilar material systems is presented. For large lattice mismatches and large interface energies, the material nucleates with its bulk lattice parameter, mismatch being accommodated by interface dislocations. No threading defects are formed, contrasting with standard plastic relaxation mechanisms. It is shown that good quality InP can be grown on ${\text{SrTiO}}_{3}$ (STO) despite the large mismatch. This opens perspectives for the monolithic integration of InP on STO/Si templates and for the widening of the application spectrum of heteroepitaxy.

Evaluation of a generalized use of the log Sum(k+1)AA descriptor in a QSRR model to predict peptide retention on RPLC systems

At the current state of knowledge, the rational optimization of the chromatographic separation of peptides, as well as the identification of proteins in proteomics are challenges for analytical chemists. In this paper the generalized applicability of a recently derived descriptor log Sum(k+1)AA in a QSRR equation to model peptide retention in RP-LC systems was evaluated. For that purpose, two sets of peptides analyzed on dissimilar RP-LC systems were considered. A first set of 28 peptides was measured on 17 columns/systems, while a second of 70 peptides was eluted on four. The aim of this work was to confirm the usefulness of the partly experimental log Sum(k+1)AA descriptor for the prediction of peptides retention compared to the initially applied, fully experimental log SumAA descriptor. The verification of the predictive abilities of both QSRR models, applying either the initial or the alternative descriptor, was done by using the leave-one-out and leave-three-out cross-validation procedures. The results seem to demonstrate that the QSRR model with log Sum(k+1)AA, for which the retention measurement of only seven out of 20 existing amino acids is necessary, possesses similar or in some cases even better predictive abilities than that containing log SumAA.

Funny guy or village fool? Social factors of the evaluation of humour and jokes among Evenkis and Sakhas

The article demonstrates that similar actions and lifestyles of two individuals living in two villages of Yakutia (in Northeastern Siberia) evoke different attitudes in their own communities in accordance with the dissimilar social structures and communicative systems of the villages. The article focuses on the different ways the register of humour is activated and on the dissimilar assessments of extraordinary patterns of behaviour resulting in social embarrassment within the two communities. The case studies show that one of the protagonists of the paper, Konoohoi, is referred to as a funny guy about whom funny stories are circulated, whereas Logontoi is much more regarded as a strange person by his fellow villagers. The difference between the integrity of the communities (providing evaluative social talks of different characters in the settlements concerned) results in two different ways of dealing with the social embarrassment caused by extraordinary behaviours. In one of the villages the funny but di...

Use of Dissimilar Walling Systems on Residential Building Envelopes for Improving Their Thermal Performance

This paper summarises the results of a combined numerical, statistical and experimental study concerned with the use of dissimilar walling systems on the external parts of a given building envelope. The rational behind this “hybrid wall” concept, as opposed to conventional approaches where identical walls are used in a building envelope, is to achieve a more effective distribution of thermal mass across the envelope and, hence, improve the overall thermal performance of the building. The effectiveness of the “hybrid wall” concept was investigated using a series of hypothetical building modules of common Australian residential constructions, namely Light Weight (LW), Brick Veneer (BV), Reverse Brick Veneer (RBV) and Cavity Brick (CB). These designs were examined numerically using a commercial energy rating tool known as “AccuRate”, statistically using JMP software and experimentally using a novel bench-scale setup developed as part of this study. The performance of each design was evaluated by its energy consumption. The numerical predictions and experimental data highlighted that the east and west walls have the most impact on the energy consumption under Australian climatic conditions. It was found that considerable reductions in the energy consumption could be achieved in cases where the hybrid wall concept was implemented through the use of high thermal mass insulated walls on the east and west sides of the building envelope.

Interdimensional universality of dynamic interfaces

Despite the complexity and diversity of nature, there exists universality in the form of critical scaling laws among various dissimilar systems and processes such as stock markets, earthquakes, crackling noise, lung inflation and vortices in superconductors. This universality is mainly independent of the microscopic details, depending only on the symmetry and dimension of the system. Exploring how universality is affected by the system dimensions is an important unresolved problem. Here we demonstrate experimentally that universality persists even at a dimensionality crossover in ferromagnetic nanowires. As the wire width decreases, the magnetic domain wall dynamics changes from elastic creep in two dimensions to a particle-like stochastic behaviour in one dimension. Applying finite-size scaling, we find that all our experimental data in one and two dimensions (including the crossover regime) collapse onto a single curve, signalling universality at the criticality transition. The crossover to the one-dimensional regime occurs at a few hundred nanometres, corresponding to the integration scale for modern nanodevices.

Management Policy in and Typology of State Park Systems

Problem statement: Parks, with particular emphasis on national and state parks, host varied interactions between human and natural systems. In particular, state park systems manage important resources related to quality of life and also are mainstays in tourism, economic development and preservation of heritage and conservation of ecosystems. Management of these parks and the human activity occurring in them is an integral component of environmental science. Approach: This research focused on identifying the legal mandates, management policies and practices that define park operations in various states within the United States. This research was a precursor to benchmarking state park systems, essential to identifying similar and dissimilar systems for the purpose of identifying benchmarking partners. Utilizing the annual information exchange of the National Association of State Park Directors, the researchers conducted a K-means cluster analysis of state park systems across the United States. Results: A seven-cluster solution was found to be the best description of the fifty state park systems. Twenty five of thirty characteristics were identified as being significant factors in defining clusters of state parks. These significant factors included: (1) number of properties, (2) number of designated state parks, (3) number of recreation areas, (4) number of environmental areas, (5) number of scientific areas, (6) number of forests, (7) number of trails and (8) miles of trails. Interestingly, mission statements and types of oversight governmental agency were not defining factors in determining clusters of state parks. Conclusion/Recommendations: This cluster analysis of state parks is important as a foundation for benchmarking state park systems, permitting comparison with similar and dissimilar systems. It is also important for consideration of marketing state parks to visitors who desire particular experiences in specific environments. This analysis provided a better understanding of interactions between human activity and natural systems, offering management insight for improved practices.

Cluster-algorithm renormalization-group study of universal fluctuations in the two-dimensional Ising model

In this paper we propose a method to study critical systems numerically, which combines collective-mode algorithms and renormalization group on the lattice. This method is an improved version of the Monte Carlo renormalization group in the sense that it has all the advantages of cluster algorithms. As an application we considered the 2D Ising model and studied whether scale invariance or universality are possible underlying mechanisms responsible for the approximate "universal fluctuations" close to a so-called bulk temperature T(L) . "Universal fluctuations" were first proposed in the work of Bramwell, Holdsworth, and Pinton [Nature (London) 396, 552 (1998)] and stated that the probability density function of a global quantity for very dissimilar systems, such as a confined turbulent flow and a two-dimensional (2D) magnetic system, properly normalized to the first two moments, becomes similar to the "universal distribution," originally obtained for magnetization in the 2D XY model in the low-temperature region. The results for the critical exponents and the renormalization-group flow of the probability density function are very accurate and show no evidence to support that the approximate common shape of the PDF should be related to both scale invariance or universal behavior.

Semiconductor thermochemistry in density functional calculations

The local-density and generalized gradient approximations (LDA and GGA) to density functional theory (DFT) exhibit incomplete error cancellation when energy differences are taken between chemically dissimilar systems. This energy inconsistency is manifested, e.g., in the tendency to underestimate the heat (enthalpy) of formation of semiconducting and insulating compounds in LDA and, even more so, in GGA. Considering a set of 61 compounds that can be formed from 14 elements (cations: Cu, Mg, Ca, Zn, Cd, Al, Ga, and In; anions: N, P, As, O, S, and Se), optimized elemental reference energies are determined by least-squares error minimization of an overdetermined set of linear equations. These elemental energies are ``optimally consistent'' with the DFT energies of the semiconductor compounds and imply corrections of up to 1 eV compared to the respective LDA or GGA energies. While these ``corrections'' are not to be understood to yield the correct absolute total energies of the elements, they are proposed to give appropriate bounds for the chemical potentials for thermodynamic processes in semiconductors and insulators, such as, e.g., defect formation, surface reconstruction, or catalytic processes. The present model allows to evaluate thermodynamic processes using DFT energy differences taken only between systems that are expected to show good error cancellation.

Evaluation of Orthogonal/Dissimilar RP-HPLC Systems Sets for Their Suitability as Method-Development Starting Points for Drug Impurity Profiles

Orthogonal or dissimilar separation systems provide different selectivities and their application can facilitate the development of methods to identify and quantify impurities in a drug substance. Two sets of chromatographic systems potentially applicable for method development were evaluated using four drug/impurity profiles. The sets consist of orthogonal or dissimilar systems and systems with good overall separation properties, selected in earlier studies. The aim of this study is to evaluate these systems for selectivity differences in the impurity profiles. These differences should allow determining the number of compounds occurring in an impurity profile. Then, one or a very limited number of systems is to be proposed for further method development. To examine the selectivity changes and separation quality for each impurity profile, both the normalized retention times tau and the resolutions between pairs of consecutively eluting peaks were plotted on parallel axes, representing the systems. For each profile, several systems of the studied sets can serve as potential starting points for further method development. All impurities could be separated from the active substance and from each other on at least one system. However, for the different profiles, different systems were selected as best, which makes that each system in a given set has its importance, depending on the properties of the profile.