Aggregation Points Research Articles

Rooted in Regional Culture, Creating Urban Characteristics — A Case Study of Dukang Road Landscape Design in Baishui County

Urban road, as the most important aggregation point and generator of the urban life, is an important space for people to experience the city culture and awareness of city character. This paper takes the phenomenon of city character crisis that the city lacks local culture characteristics as the starting point. Through the analysis of landscape design of Dukang Road (E), which is in Baishui county, discusses how to reasonable use local culture in urban road landscape design. With the regional culture as an important creating source, absorb its beneficial "gene," so as to create urban road landscape with regional culture characteristics, thus to better showing the distinct personality and character of the city.

Modeling of interactions between market regulations and behavior of plug-in electric vehicle aggregators in a virtual power market environment

A market regulator is considered to increase the market efficiency and hence several regulations are tried to achieve this target. In many of such regulations, special conditions of renewable energies have been introduced. Accordingly, it is observed that some changes in regulations may have indirect undesirable effects on involved companies. In this paper, effects of the changes in market regulations on the behavior of both plug-in electric vehicle owners and their aggregators have been studied. A hybrid method is proposed to simulate the behavior of the market players from both regulator and aggregator's point of views. In addition, behavior of electric vehicle owners has been modeled considering type of the contract with aggregator. The result shows that a clever aggregator can convert some threats to changes in market regulations and there have been opportunities to increase the profit, enhanced the costumers and even the market efficiency.

Impact of Anemia on Platelet Response to Clopidogrel in Patients Undergoing Percutaneous Coronary Stenting

High residual platelet reactivity (HRPR) on clopidogrel is a predictor of recurrent ischemic events in patients undergoing percutaneous coronary interventions (PCI). Significant intraindividual variability in platelet aggregation on repeat testing has been reported. To understand factors contributing to the variability in platelet aggregation testing, we examined clinical and laboratory elements linked to HRPR in 255 consecutive patients tested ≥12 hours after PCI using light transmission aggregometry (LTA) in response to adenosine diphosphate 5 μmol/L and VerifyNow P2Y12 assay (VNP2Y12; Accumetrics). HRPR was defined as >46% residual aggregation for LTA and >236 P2Y12 response units (PRUs) for VNP2Y12. On multivariate analysis the only variable independently associated with HRPR with both LTA and VNP2Y12 was laboratory-defined anemia. Prevalences of HRPR by LTA were 34.3% in anemic patients, 15.6% in patients with normal hemoglobin levels, and 59.8% versus 25.9% by VNP2Y12 (p <0.005 for the 2 comparisons). In a subgroup of 50 patients, testing was done before and after the clopidogrel loading dose. At baseline there were no differences in platelet aggregation with either assay; however, absolute decrease in reactivity after the clopidogrel load was significantly less in anemic patients compared to patients with normal hemoglobin (change in residual aggregation by LTA 15.8 ± 5.8% vs 28.8 ± 3.2%, p <0.05; change in PRU by VNP2Y12 56.5 ± 35.5 vs 145.0 ± 14.2 PRUs, p <0.05, respectively). In conclusion, anemia is an important contributor to apparent HRPR on clopidogrel and may explain some of the intraindividual variability of platelet aggregation testing.

Manipulation of Concentration-Conductivity Data of Sodium Dodecyl Sulphate and Sodium Dodecylbenzene Sulphonate in KCl Solution in Relation to Micellisation Parameters

The conductivity of sodium dodecyl sulphate (SDS) and sodium dodecylbenzenesulphonate (SDBS) has been studied in varying concentrations (0-5 mM) of aqueous KCl solution at 25oC. Data analysis was based on the conventional treatment of conductivity-concentration data, differential, and integration methods with the aim of knowing the best method. As expected, the conductivity increased with an increase in surfactant concentration; the plot of which showed a kink at critical micelle concentration, cmc (i.e. point of aggregation). The results showed no apparent relationship between the degree of counterion binding, β and [KCl]; and an inverse relationship between the cmc values and [KCl]. β was within 0.4-0.6 for SDS and 0.1-0.3 for SDBS. The cmc of SDS decreased from ca. 8 to 6 mM and that of SDBS from ca. 2 to 1 mM as the [KCl] increased from 0-5 mM. These values are in mutual agreement irrespective of the method used. It was confirmed that in the absence of KCl, values obtained from the integration method were more consistent with those reported in the literature; therefore this method is recommended as the best method for determination of micellisation parameters provided the process is followed by conductivity measurements.

Surfactantion-selective electrodes: A promising approach to the study of the aggregation of ionic surfactants in solution

The potentiometric method based on surfactant ion-selective electrodes (SISEs) was broadly applied to ionic surfactants in solution due to the change in their activities, i.e., concentration in dilute solution, of both the counterions and ionic surfactants at the point of aggregation. The monomeric surfactant concentration can be determined by SISEs with almost no pretreatment, even if the sample solutions were colored or viscous. Ion-sensitive electrodes are usually used to investigate the dimerization, aggregation, and micelle formation of ionic surfactants in aqueous solution. By using SISEs, the binding isotherm of ionic surfactants bound to other materials such as polymers and biomolecules (DNA and proteins) can be calculated easily. According to the binding isotherms, the different binding and aggregation processes between ionic surfactants and other materials can be identified and characterized, which is important for understanding the interaction between ionic surfactants and polymers and/or biomolecules. Herein we present a comprehensive review of the literature devoted to SISEs used in the aggregation of surfactants in solution over the last two decades, looking back the developmental history of SISEs, reviewing the applications of SISEs in the studies of surfactant/surfactant mixtures, the adsorption of surfactants on polymers, including neutral polymers, polyelectrolytes, and biopolymers and the interactions between surfactants and lipid vesicles, etc., prospecting the new wave of SISEs.

Investigating How Peptide Length and a Pathogenic Mutation Modify the Structural Ensemble of Amyloid Beta Monomer

The aggregation of amyloid beta (Aβ) peptides plays an important role in the development of Alzheimer's disease. Despite extensive effort, it has been difficult to characterize the secondary and tertiary structure of the Aβ monomer, the starting point for aggregation, due to its hydrophobicity and high aggregation propensity. Here, we employ extensive molecular dynamics simulations with atomistic protein and water models to determine structural ensembles for Aβ42, Aβ40, and Aβ42-E22K (the Italian mutant) monomers in solution. Sampling of a total of >700 microseconds in all-atom detail with explicit solvent enables us to observe the effects of peptide length and a pathogenic mutation on the disordered Aβ monomer structural ensemble. Aβ42 and Aβ40 have crudely similar characteristics but reducing the peptide length from 42 to 40 residues reduces β-hairpin formation near the C-terminus. The pathogenic Italian E22K mutation induces helix formation in the region of residues 20–24. This structural alteration may increase helix-helix interactions between monomers, resulting in altered mechanism and kinetics of Aβ oligomerization.

Efficient Shape Recognition of Dynamic Event Regions Using Wireless Sensor Networks

In this paper, we consider the problem of recognizing the shape of dynamic event regions in wireless sensor networks (WSNs). A key idea of our proposed algorithm is to use the notion of distance fielddefined by the hop count from the boundary of event regions. By constructing such a field, we can easily identify several critical points in each event region (e.g., local maximum and saddle point) which could be effectively used to characterize the shape and the movement of such event regions. The communication cost required for the shape recognition of dynamic event regions significantly decreases compared with a naive centralized scheme by selectively allowing those critical points to send a certification message to the boundary of the event region and a notification message to the data aggregation points. The performance of the proposed scheme is evaluated by simulations. The simulation results indicate that: 1) the number of messages transmissions during a shape recognition significantly decreases compared with a naive centralized scheme; 2) the accuracy of shape recognition depends on the density of the underlying WSN, while it is robust against the lack of sensors in a particular region in the field, and 3) the proposed event tracking scheme correctly recognizes the movement of an event region with small number of message transmissions compared to a centralized scheme.

Em-Powering Economics: Some Thoughts on Policy and Financial Markets

This paper addresses the discussion between economic power and the power of politics with particular focus on financial markets. After general reflections about the economic basis of power, the paper discusses in a general equilibrium framework how financial innovations can lead to risk creation and an inflation of financial products. This creates a fundamental disorder in the financial system which from an aggregate point of view can be described in a standard portfolio framework, in which higher rates of return go hand in hand with higher private risks but also with increasing externalized (social) risk and insurance illusion. Rate of return regulation is proposed as an appropriate regulatory measure. Alternatively the deficiency could be cured by admission regulations for financial products which put the burden of proof for no external (systemic) damages of a financial instrument to the issuer.

Mechanisms for centralized flow rate control in 802.11-based wireless mesh networks

Cross-layer interaction between TCP and CSMA/CA-based MAC in multihop wireless networks produces suboptimal network performance, including flow rate unfairness and starvation. Rate control mechanisms can mitigate this behavior. Of particular interest are centralized mechanisms that enforce rate limits at traffic aggregation points, without modifying individual mesh routers or client devices. In this paper, we propose, design, and evaluate a framework of zero-overhead, feedback-driven centralized rate controllers. These controllers are implemented at gateway mesh routers. We use existing data traffic as capacity probes with a feedback-driven response to adapt to changes in network and traffic conditions. Using simulations and experiments on a testbed, we show an improvement in fairness by a factor of 2–3 over networks without any rate control. Further, our fairness metrics are within 2% of those achieved by a centralized controller with an omniscient knowledge of network conditions.

The Sovereign Credit Default Swap Market: Price Discovery, Volumes and Links with Banks' Risk Premia

This paper looks into the sovereign credit default swap (CDS) market from two perspectives. First, it analyses the relation between CDS and bond spreads. The results on a single-entity basis suggest that the CDS market leads the bond market in price discovery, especially during 2010, while both markets contribute during the pre-Lehman period and in 2009. Moreover, the inclusion of the EURIBOR-EUREPO 3-month spread helps to restore the long-run relation after the Lehman bailout. An event-study, which compares the reaction of sovereign CDS and bond markets to policy announcements in Europe, suggests that both markets react in the same way, especially after the release of bad news. As for the relation between prices and volumes of sovereign CDSs, estimates do not point to any stable relation. The second perspective is the relation between CDS spreads for sovereign and corporate entities. Our estimates on an aggregate and sector-wide basis point to a leading property of the former sector, even in 2009, while the banking sector increases its leading power during 2010.

Credit market dynamics: a cobweb model

Starting from a recent model developed by Dieci and Westerhoff (Appl Math Comput 215:2011---2023, 2009; J Econ Behav Organ 75(3):461---481, 2010) enriching the classic cobweb framework based on the findings of Brock and Hommes (Econometrica 65:1059---1095, 1997; J Econ Dynam Control 22:1235---1274, 1998), an original model is set up to analyse the interactions among two types of credit markets considered from the aggregate demand side view point. The proposed model is an aggregate model for unobserved Financial Institutions which are assumed to supply credit on competitive markets and competition is due to the interest rates (i.e. prices) with respect to the corresponding contracts' demand. Moreover these Financial Institutions can put contracts on the credit market switching over time on different types of contracts depending on expected profit differentials. Among the main characteristics of this model, the number of clients involved in the two credit markets changes over time. At any time, the density of contracts is assumed to maximize the entropy of the economic system under some constraints concerning aggregate profits where the contract profitability is defined as a function of the spread between the average price of the contracts and a measure of production costs. With reference to some model calibrations, the dynamic behaviours and the reactions of the model are investigated through the study of three shock scenarios. The promising obtained results will address further investigations to apply the proposed model to a real data base of information on Financial Institutions in Italy since 1997 to catch the dynamics of fixed and adjustable interest rate mortgages markets.

Efficient data aggregation and transport in wireless sensor networks

AbstractWe consider the problem of reporting events using wireless sensor networks. To reduce the data volume generated by each event, the correlated data from the (neighboring) nodes that detect the event must be brought together to be processed and compressed before relaying the result across several hops to the data sink. This process is supported by an aggregation tree, which specifies the flow of information towards the sink. For efficiency, aggregation trees should compress the data close to their sources. We propose two solutions to the event‐triggered reporting problem. Firstly, we propose the first protocol to use a staggered schedule in the construction of the aggregation tree. Due to the use of such a schedule, our protocol divides the tree‐construction time by roughly the number of hops in the network, and this advantage comes only at the expense of a small degradation of the quality of the obtained aggregation tree. Secondly, we consider a multi‐hop cluster‐based topology with fixed aggregation points. This topology is appropriate for large networks with unreliable radio links. We approximate the optimal cluster size distribution and evaluate the improvement over a uniform cluster size distribution. Copyright © 2009 John Wiley &amp; Sons, Ltd.

Blocking Wythoff Nim

The 2-player impartial game of Wythoff Nim is played on two piles of tokens. A move consists in removing any number of tokens from precisely one of the piles or the same number of tokens from both piles. The winner is the player who removes the last token. We study this game with a blocking maneuver, that is, for each move, before the next player moves the previous player may declare at most a predetermined number, $k - 1 \ge 0$, of the options as forbidden. When the next player has moved, any blocking maneuver is forgotten and does not have any further impact on the game. We resolve the winning strategy of this game for $k = 2$ and $k = 3$ and, supported by computer simulations, state conjectures of 'sets of aggregation points' for the $P$-positions whenever $4 \le k \le 20$. Certain comply variations of impartial games are also discussed.

Up-dating the Cholodny method using PET films to sample microbial communities in soil

The aim of this work was to investigate the use of PET (polyethylene terephtalate) films as a modern development of Cholodny’s glass slides, to enable microscopy and molecular-based analysis of soil communities where spatial detail at the scale of microbial habitats is essential to understand microbial associations and interactions in this complex environment. Methods. Classical microbiological methods; attachment assay; surface tension measurements; molecular techniques: DNA extraction, PCR; confocal laser scanning microscopy (CLSM); micro-focus X-ray computed tomography (µCT). Results. We first show, using the model soil and rhizosphere bacteria Pseudomonas fluorescens SBW25 and P. putida KT2440, that bacteria are able to attach and detach from PET films, and that pre-conditioning with a filtered soil suspension improved the levels of attachment. Bacteria attached to the films were viable and could develop substantial biofilms. PET films buried in soil were rapidly colonised by microorganisms which could be investigated by CLSM and recovered onto agar plates. Secondly, we demonstrate that µCT can be used to non-destructively visualise soil aggregate contact points and pore spaces across the surface of PET films buried in soil. Conclusions. PET films are a successful development of Cholodny’s glass slides and can be used to sample soil communities in which bacterial adherence, growth, biofilm and community development can be investigated. The use of these films with µCT imaging in soil will enable a better understanding of soil micro-habitats and the spatially-explicit nature of microbial interactions in this complex environment.

Automated Near-Continuous Glucose Monitoring Measured in Plasma Using Mid-Infrared Spectroscopy

There are increasing calls for a precise, automated system to enable tight glycemic control and to avoid hypoglycemia in an intensive care unit setting. OptiScan Biomedical has developed a glucose monitor based on mid-infrared spectroscopy that withdraws blood samples (120 µl) and measures plasma glucose. The goal of this study was to validate the performance of the OptiScan Model 5000 over a wide range of glycemic levels in patients. Sixty people with type 1 (n = 18) or type 2 (n = 42) diabetes who were otherwise healthy were connected to OptiScanners. Their blood glucose concentrations were kept in a euglycemic, hypoglycemic (<75 mg/dl), and hyperglycemic (>180 mg/dl) range by intravenous administrations of insulin and glucose. OptiScanner venous blood samples were automatically withdrawn every 15 minutes. Reference measurements were done using the YSI 2300 glucose analyzer. The aggregate data points (1155 paired readings) were within International Organization for Standardization standards, with 98.6% of the glucose values within ±20% above 75 mg/dl and ±15 mg/dl below this value. A Clarke error grid analysis showed a total of 1139 points (98.6%) in zone A. Points outside of A exceeded the A zone boundary by an average of 4.3%. The r(2) was 0.99. The total coefficient for variance was 6.4%. These results show that the OptiScanner is highly accurate in healthy patients with diabetes across a wide range of glucose values. Mid-infrared spectroscopy may become the method of choice for highly accurate, high frequency, automated glucose measurements and may thus enable better glycemic control in critically ill patients.

Advances in Vascular Neurosurgery 2010

Surgery continues to play a major role in the treatment of intra- and extracranial cerebrovascular disorders. Refinements in endovascular techniques have resulted in a reappraisal of their role vis-a-vis surgery. ### Carotid Stenosis Carotid endarterectomy (CEA) is the gold standard for the treatment of carotid stenosis in both symptomatic patients and in appropriately selected patients who are asymptomatic. In the past decade, carotid angioplasty and stenting (CAS) has been proposed as a possible alternative to CEA. Landmark studies have addressed this issue in the past year. The International Carotid Stenting Study (ICSS) randomized 1713 symptomatic patients with carotid stenosis of >50% to either CEA or CAS. The end point of stroke and death within 30 days was significantly higher in the CAS group (7.4% versus 4.0%; P =0.003).1 In a subgroup analysis, silent brain infarcts were significantly more common in patients undergoing CAS than in patients treated with CEA.2 The Carotid Revascularization Endarterectomy Versus Stenting Trial (CREST) study randomized patients with symptomatic and asymptomatic carotid stenosis to either CAS or CEA. Unlike other studies, CREST included myocardial infarction in the aggregate end point analysis. Importantly, serum troponin levels and electrocardiograms were mandated per protocol and myocardial infarction was defined as based on serum troponin elevation and electrocardiographic changes even in the absence of clinical symptoms. The aggregate end points were not statistically different between CAS and CEA (7.2% and 6.8%, respectively; P =0.51). However, perioperative strokes were more common in the CAS group (4.1% versus 2.3%, P =0.01), whereas myocardial infarction was more common in patients undergoing CEA (1.1% versus 2.3%; P =0.03). When only symptomatic patients are considered, the incidence of perioperative stroke was 6.0% in the CAS group and 3.2% in the CEA group.3 A debate continues as to whether the composite outcome of stroke and myocardial infarction, …

Multi factorial interactions in the pathogenesis pathway of Alzheimer’s disease: a new risk charts for prevention of dementia

BackgroundThe population longitudinal study named “The Conselice Study” has been the focus of the present investigation. 65 years old or older participants of this population study on brain aging were followed up for 5 years: 937 subjects completed the follow-up. Relationships of 46 genetic, phenotypic, clinical and nutritional factors on incident cognitive decline and incident dementia cases were investigated.ResultsA new statistical approach, called the Auto Contractive Map (AutoCM) was applied to find relationship between variables and a possible hierarchy in the relevance of each variable with incident dementia. This method, based on an artificial adaptive system, was able to define the association strength of each variable with all the others. Moreover, few variables resulted to be aggregation points in the variable connectivity map related to cognitive decline and dementia. Gene variants and cognate phenotypic variables showed differential degrees of relevance to brain aging and dementia. A risk map for age associated cognitive decline and dementia has been constructed and will be presented and discussed.ConclusionThis map of variables may be use to identify subjects with increased risk of developing cognitive decline end/or dementia and provide pivotal information for early intervention protocols for prevention of dementia.

Temperature induced phase separation of luminescent silica nanoparticles in Triton X-100 solutions

The aggregation and cloud point behavior of Tb(III)-doped silica nanoparticles has been studied in Triton X-100 (TX-100) solutions at various concentration conditions by fluorimetry, dynamic light scattering, electrophoresis and transmission electron microscopy methods. The temperature responsive behavior of nanoparticles is observed at definite concentration of TX-100, where the aggregation of TX-100 at the silica/water interface is evident from the increased size of the silica nanoparticles. The reversible dehydration of TX-100 aggregates at the silica/water interface should be assumed as the main reason of the temperature induced phase separation of silica nanoparticles. The distribution of nanoparticles between aqueous and surfactant rich phases at the phase separation conditions can be modified by the effect of additives.

Point of Zero Charge, Isoelectric Point and Aggregation of Phyllosilicate Minerals

Point of zero charge (p.z.c.) and isoelectric point (i.e.p.) values for chlorite (clinochlore) and serpentine (lizardite), i.e., electrokinetically anisotropic minerals, were measured using the Mular-Roberts (M-R) titration technique and electrophoretic mobility, respectively. For chlorite and serpentine, respectively, the p.z.c. was pH 4.6 and 4.3, and the i.e.p. was at pH <3 and 3.3. Aggregation was gauged from settling tests adapted to small samples. This showed maximum aggregation for chlorite was around pH 3, i.e., close to the i.e.p., while serpentine did not show a conclusive maximum. Some implications in flotation are discussed. Résumé On a mesurè les valeurs du point de charge nulle (p.z.c.) et du point isoèlectrique (i.e.p.) pour le chlorite (clinochlore) et la serpentine (lizardite), i.e. des minèraux èlectrocinètiquement anisotropes, en utilisant la technique de titrage de Mular-Roberts (M-R) et la mobilitè èlectrophorètique, respectivement. Le p.z.c. se trouvait au pH 4.6 et 4.3 respectivement, pour le chlorite et la serpentine et le i.e.p. ètait au pH <3 et 3.3. On a calibrè l'agrègation à partir d'essais de sèdimentation adaptès à de petits èchantillons. Ceci a montrè que l'agrègation maximale pour le chlorite ètait autour du pH 3, près du i.e.p., alors que la serpentine n'a pas montrè de maximum conclusif. On discute de certaines implications pour la flottation.

Point of Zero Charge, Isoelectric Point and Aggregation of Phyllosilicate Minerals

Point of zero charge (p.z.c.) and isoelectric point (i.e.p.) values for chlorite (clinochlore) and serpentine (lizardite), i.e., electrokinetically anisotropic minerals, were measured using the Mular-Roberts (M-R) titration technique and electrophoretic mobility, respectively. For chlorite and serpentine, respectively, the p.z.c. was pH 4.6 and 4.3, and the i.e.p. was at pH <3 and 3.3. Aggregation was gauged from settling tests adapted to small samples. This showed maximum aggregation for chlorite was around pH 3, i.e., close to the i.e.p., while serpentine did not show a conclusive maximum. Some implications in flotation are discussed.RésuméOn a mesurè les valeurs du point de charge nulle (p.z.c.) et du point isoèlectrique (i.e.p.) pour le chlorite (clinochlore) et la serpentine (lizardite), i.e. des minèraux èlectrocinètiquement anisotropes, en utilisant la technique de titrage de Mular-Roberts (M-R) et la mobilitè èlectrophorètique, respectivement. Le p.z.c. se trouvait au pH 4.6 et 4.3 respectivement, pour le chlorite et la serpentine et le i.e.p. ètait au pH <3 et 3.3. On a calibrè l'agrègation à partir d'essais de sèdimentation adaptès à de petits èchantillons. Ceci a montrè que l'agrègation maximale pour le chlorite ètait autour du pH 3, près du i.e.p., alors que la serpentine n'a pas montrè de maximum conclusif. On discute de certaines implications pour la flottation.