Search results for "aggregate"

Increasing the elastic modulus of polyamides

1977

Entrapment of amino acids in gas phase surfactant assemblies: The case of tryptophan confined in positively charged (1R,2S)-dodecyl (2-hydroxy-1-meth…

2017

The ability of positively charged aggregates of the surfactant (1R,2S)‐dodecyl (2‐hydroxy‐1‐methyl‐2‐phenylethyl))dimethylammonium bromide (DMEB) to incorporate D-tryptophan or L-tryptophan in the gas phase has been investigated by electrospray ion mobility mass spectrometry (ESI‐IM‐MS). Strongly impacted by the pH of the electrosprayed solutions, both protonated (T+) and deprotonated (T-) tryptophan are effectively included into the aggregates, whereas, tryptophan in zwitterionic (T0) form is practically absent in singly charged DMEB aggregates but can be found in multiply charged ones. The ability to incorporate tryptophan increases with the aggregation number and charge state of aggr…

ei.Datasets: Real Data Sets for Assessing Ecological Inference Algorithms

2021

Ecological inference models aim to infer individual-level relationships using aggregate data. They are routinely used to estimate voter transitions between elections, disclose split-ticket voting behaviors, or infer racial voting patterns in U.S. elections. A large number of procedures have been proposed in the literature to solve these problems; therefore, an assessment and comparison of them are overdue. The secret ballot however makes this a difficult endeavor since real individual data are usually not accessible. The most recent work on ecological inference has assessed methods using a very small number of data sets with ground truth, combined with artificial, simulated data. This arti…

Spatial Vote Redistribution in Redrawn Polling Units

2012

Summary A large proportion of electoral analyses using geography are performed on a small area basis. In each new election there are always modifications to the previously existing polling units. The use of past voting results in small area aggregate data electoral forecasting models and political analyses therefore requires establishing a correspondence between old and new polling units. Traditionally, the task of tracking changes to assign an electoral history to the new units properly has been carried out by hand, comparing unit codes and census figures. This is an extremely cumbersome task that cannot always be performed, as when a massive (geographically intense) reorganization of poll…

Macroscopic Dynamic Effects of Migrations in Patchy Predator-prey Systems

1997

Abstract Different mechanisms at the behaviourial or physiological levels determine many properties of predator-prey systems at the population level. In this paper, we present a method of obtaining complex predator-prey dynamic models from models at a detailed, behaviourial level of description. We consider a multi-patch predator-prey model, the dynamics of which contains two time-scales: a fast one, associated with migrations between patches, and a slow one, on which interactions, reproduction and mortality occur. We use methods of perturbation theory in order to aggregate the multi-patch system into a reduced system of two differential equations for the total prey and predator populations…

Government Size, the Role of Commitments*

2011

We explore the hypothesis that long-term commitments affect the dynamics of government expenditure. With the aid of a simple median-voter model we interpret the pattern of increasing-then-constant tax rates observed in OECD countries in the second half of the last century: persistence of public expenditure and a lower bound on new interventions will push government size upward, and preferences of the electorate put a halt to this growth at some point. In this view, the fiscal policy variable is seen to consist of only a part of the total expenditure, the rest being predetermined by its past level.

Market efficiency and the long-memory of supply and demand: is price impact variable and permanent or fixed and temporary?

2016

In this comment we discuss the problem of reconciling the linear efficiency of price returns with the long-memory of supply and demand. We present new evidence that shows that efficiency is maintained by a liquidity imbalance that co-moves with the imbalance of buyer vs. seller initiated transactions. For example, during a period where there is an excess of buyer initiated transactions, there is also more liquidity for buy orders than sell orders, so that buy orders generate smaller and less frequent price responses than sell orders. At the moment a buy order is placed the transaction sign imbalance tends to dominate, generating a price impact. However, the liquidity imbalance rapidly incre…

Top-k String Similarity Joins

2020

Top-k joins have been extensively studied in relational databases as ranking operations when every object has, among others, at least one ranking attribute. However, the focus has mostly been the case when the join attributes are of primitive data types (e.g., numerical values) and the join predicate is equality. In this work, we consider string objects assigned such ranking attributes or simply scores. Given two collection of string objects and a string similarity measure (e.g., the Edit distance), we introduce the top-k string similarity join () which returns k sufficiently similar pairs of objects with respect to a similarity threshold ϵ, which have the highest combined score computed by…

Organic carbon, water repellency and soil stability to slaking under different crops and managements: a case study at aggregate and intra-aggregate s…

2014

This research studies the distribution of organic C and intensity of water repellency in soil aggregates with different size and in the interior of aggregates from Mediterranean soils under different crops (apricot, citrus and wheat) and management (con- 5 ventional tilling and no tilling/mulching). For this, undisturbed aggregates were sampled and carefully divided in size fractions (0.25–0.5, 0.5–1, 1–2, 2–5, 5–10 and 10–15 mm) or peeled to obtain separated aggregate layers (exterior, transitional and interior). Organic C content in the fine earth fraction of soils under different crops did not show important variations, although it increased significantly from conventionally tilled to 10…

Theoretical study of the interaction between sodium ion and a cyclopeptidic tubular structure.

2007

DFT calculations have been carried out to describe the pathway of a sodium ion along the stacking direction of a tubular structure set up by five cyclopeptidic units, which can be considered a suitable model of a hollow tubular structure of indefinite length. A lattice of points inside the tubular structure is defined and the DFT interaction energy values with a sodium ion are obtained. The data allow predicting a zigzag path of the ion inside the hosting structure. © 2007 Wiley Periodicals, Inc. J Comput Chem, 2007