1,960 research outputs found

    Reactive precursor particles as synthetic platform for the generation of functional nanoparticles, nanogels, and microgels

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    Precise control of the chemical functionality of polymer nanoparticles is a key requirement in tailoring their (dynamic) colloidal properties toward advanced applications. However, current synthetic techniques are still limited in the versatility of chemical design and preparation of such functional colloidal nanomaterials. Two major challenges remain: First, various particle preparation methods are restricted in their functional group tolerance, thus hindering certain combinations of polymer backbones with specific functional groups. Second, the preparation of particles with different functionalities requires the synthesis of different particle batches. But this often results in a simultaneous variation of colloidal features. As a result, the accurate determination of important structure–property relations is still hindered. To address these restrictions, postmodification of preformed reactive particles is gaining more attention. This technique has evolved from polymer synthesis, where postpolymerization functionalization enables the introduction of a plethora of functional groups without changing the degree of polymerization and the molecular weight distribution. Similarly, modifying precursor particles enables the introduction of functional groups into particles while reducing variations in colloidal features, e.g., particle size and size distribution. This powerful synthetic method complements established procedures for functionalization of particle surfaces, thereby enabling the facile preparation of (multi‐)functional particle libraries, which will allow precise investigations of structure–property relations

    The Church vs the Mall: What Happens When Religion Faces Increased Secular Competition?

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    Recently economists have begun to consider the causes and consequences of religious participation. An unanswered question in this literature is the effect upon individuals of changes in the opportunity cost of religious participation. In this paper we identify a policy-driven change in the opportunity cost of religious participation based on state laws that prohibit retail activity on Sunday, known as %u201Cblue laws.%u201D Many states have repealed these laws in recent years, raising the opportunity cost of religious participation. We construct a model which predicts, under fairly general conditions, that allowing retail activity on Sundays will lower attendance levels but may increase or decrease religious donations. We then use a variety of datasets to show that when a state repeals its blue laws religious attendance falls, and that church donations and spending fall as well. These results do not seem to be driven by declines in religiosity prior to the law change, nor do we see comparable declines in membership or giving to nonreligious organizations after a state repeals its laws. We then assess the effects of changes in these laws on drinking and drug use behavior in the NLSY. We find that repealing blue laws leads to an increase in drinking and drug use, and that this increase is found only among the initially religious individuals who were affected by the blue laws. The effect is economically significant; for example, the gap in heavy drinking between religious and non religious individuals falls by about half after the laws are repealed.

    Faith-Based Charity and Crowd Out during the Great Depression

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    Interest in religious organizations as providers of social services has increased dramatically in recent years. Churches in the U.S. were a crucial provider of social services through the early part of the twentieth century, but their role shrank dramatically with the expansion in government spending under the New Deal. In this paper, we investigate the extent to which the New Deal crowded out church charitable spending in the 1930s. We do so using a new nationwide data set of charitable spending for six large Christian denominations, matched to data on local New Deal spending. We instrument for New Deal spending using measures of the political strength of a state's congressional delegation, and confirm our findings using a different instrument based on institutional constraints on state relief spending. With both instruments we find that higher government spending leads to lower church charitable activity. Crowd-out was small as a share of total New Deal spending (3%), but large as a share of church spending: our estimates suggest that church spending fell by 30% in response to the New Deal, and that government relief spending can explain virtually all of the decline in charitable church activity observed between 1933 and 1939.

    Force monitor for training manual skills in the training of chiropractors

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    As part of their training, students of Chiropractic Medicine at ZĂŒrich are trained to acquire and then improve their manual and manipulative skills, especially their ability to deliver manipulative thrusts with a defined preloading force, an impulse that is delivered with an adequate and reproducible force within a defined time without letting up on the preload-pressure. In order to facilitate this process, objective feedback is paramount. This led to the idea of developing a force-measurement and -monitoring system. The newly developed system consists of a wireless device with a force sensor and an app that is running on standard smartphones. The device records the force applied to the sensor and transmits it via Bluetooth Low Energy (BLE) to the app. There it is visualised as a graph and can be evaluated. The system allows us to provide all students with a tool to develop their manual skills, and especially their thrusting technique. As the feedback given by the system can be record ed, progress can be monitored and students can be mentored accurately according to their strengths and weaknesses

    Min-Max Predictive Control of a Pilot Plant using a QP Approach

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    47th IEEE Conference on Decision and Control 9-11 Dec. 2008The practical implementation of min-max MPC (MMMPC) controllers is limited by the computational burden required to compute the control law. This problem can be circumvented by using approximate solutions or upper bounds of the worst possible case of the performance index. In a previous work, the authors presented a computationally efficient MMMPC control strategy in which a close approximation of the solution of the min-max problem is computed using a quadratic programming problem. In this paper, this approach is validated through its application to a pilot plant in which the temperature of a reactor is controlled. The behavior of the system and the controller are illustrated by means of experimental results

    LpL^p-approximation of the integrated density of states for Schr\"odinger operators with finite local complexity

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    We study spectral properties of Schr\"odinger operators on \RR^d. The electromagnetic potential is assumed to be determined locally by a colouring of the lattice points in \ZZ^d, with the property that frequencies of finite patterns are well defined. We prove that the integrated density of states (spectral distribution function) is approximated by its finite volume analogues, i.e.the normalised eigenvalue counting functions. The convergence holds in the space Lp(I)L^p(I) where II is any finite energy interval and 1≀p<∞1\leq p< \infty is arbitrary.Comment: 15 pages; v2 has minor fixe
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