Miracle-dz/UniFAR-FTUs huggingface dataset:
Chemical characterization of silicon-substituted hydroxyapatite.

Bioceramic specimens have been prepared by incorporating a small amount of silicon (0.4 wt %) into the structure of hydroxyapatite [Ca10(PO4)6(OH)2, HA] via an aqueous precipitation reaction to produce a silicon-substituted hydroxyapatite (Si-HA). The results of chemical analysis confirmed the proposed substitution of the silicon (or silicate) ion for the phosphorus (or phosphate) ion in hydroxyapatite. The Si-HA was produced by first preparing a silicon-substituted apatite (Si-Ap) by a precipitation process. A single-phase Si-HA was obtained by heating/calcining the as-prepared Si-Ap to temperatures above 700 degrees C; no secondary phases, such as tricalcium phosphate (TCP), tetracalcium phosphate (TeCP), or calcium oxide (CaO), were observed by X-ray diffraction analysis. Although the X-ray diffraction patterns of Si-HA and stoichiometric HA appeared to be identical, refinement of the diffraction data revealed some small structural differences between the two materials. The silicon substitution in the HA lattice resulted in a small decrease in the a axis and an increase in the c axis of the unit cell. This substitution also caused a decrease in the number of hydroxyl (OH) groups in the unit cell, which was expected from the proposed substitution mechanism. The incorporation of silicon in the HA lattice resulted in an increase in the distortion of the PO4 tetrahedra, indicated by an increase in the distortion index. Analysis of the Si-HA by Fourier transform infrared (FTIR) spectroscopy indicated that although the amount of silicon incorporated into the HA lattice was small, silicon substitution appeared to affect the FTIR spectra of HA, in particular the P-O vibrational bands. The results demonstrate that phase-pure silicon-substituted hydroxyapatite may be prepared using a simple precipitation technique.
THE EFFECT OF UNIVALENT CATIONS ON THE BINDING OF SRNA TO THE TEMPLATE-RIBOSOME COMPLEX.

Synthetic polynucleotides such as polyuridylic acid (poly U) ' have been shown to bind to ribosome complexes by connecting them into more or less organized units. Such assemblies of ribosomes, the so-called polyribosomes, have now frequently been identified as units on which the synthesis of polypeptides proceeds.2-4 Wewish to report here on a template-requiring reaction between amino acyl sRNA and ribosomes that appears to precede amino acid polymerization. Ammonium or potassium ions are essential for this reaction. -7 It has been observed, furthermore, that the polynucleotide templates must be specific for the particular amino acid to attach firmly amino acy-l sRNA's to ribosomes.48 Similar observations have recently been made by Kaji and Kaji.9 This effect of potassium and ammonium ions appears to furnish an explanation for the requirement of these ions in polypeptide synthesis. Materials and Methods. -Sucrose gradientfractionation: The exponential density gradients were prepared essentially as described in an earlier communication. ' The mixing flask contained 2.3 ml of 5% sucrose and the reservoir 4. $ ml of 22% sucrose. Both solutions contained 0.01 M Tris buffer pH 7.4, and 0.017 M magnesium acetate. The sample to be fractionated was applied to the top of the sucrose gradients in 4 volume of 0.25 ml. It was centrifuged in a Spinco Model L ultracentrifuge as described below, and, generally two-drop fractions were collected after piercing the bottom of the cello tube with a needle. Conditions for the bindingof eRNA: The standard incubation mixture was composed of 0.015 M Tria-H1 buffer p11 7.4, 0.Q3 At magnesium acetate, 0.5 mg of washed ribosomes, 0.25 mg of C'4-L-phenylalanyl-sRNA containing 13,500 cpm, and additions made up to a final volume of 0.25 ml. The specific activity of the amino acid was 45.3 ,AC/,gmole. The sRNA was prepared by phenol treatment of frozen E. coli cells; it was stripped of amino acids and charged with C14pkenylalanine.5 The reagents were mixed at 0° and generally incubated for 5 min at either 250 or 37°. The incubation was terminated by chilling the mixture in an ice bath; the contents were then layered on top of sucrose gradients and centrifuged in the SW39 rotor of the, Spinco ultracentrifuge. The centrifugation was carried out for 1 hr at 37,000 rpm unless otherwise indicated. In most cases, 3 gradient tubes were centrifuged simultaneously. Approximately 5 min elapsed from the end of the incubation to the time centrifugation was begun. The amount of sRNA associated with the ribosomes was assayed by collecting alternate twodrop fractions on 1'/4-in. stainless steel planchets, and measuring their radioactivity after addition of acetone and drying in an oven. The counts obtained were corrected for self-absorption due to the presence of sucrose. A windowless counter with an efficiency of 35% was used. Preparation of ribosomes: Ribosomes from a frozen paste of E. coli cells were prepared and washed three times according to a procedure described previously.7
Book Review: The Structure and Growth of Residential Neighbourhoods in American Cities

function of obsolescence brought about by major changes in the logic of urban organisation and the changing specifications for land use and building design associated with technological change. Thus, the Forrester model may miss what is conceivably the most important determinant of urban decay or stagnation. It may also ignore some of the most important areas of policy leverage that may be applied to urban renewal. Is it not possible that, if we want to use simulation technology to examine policy options, we may need to examine not only those options associated with variations in the values of model parameters or independent variables associated with a given model structure, but also the policy options and modifications that may arise out of a consideration of several optional models? ' All of this is my way of saying that the Forrester book does not adequately examine and justify the assumptions that define the model structure. There exists a substantial literature on location analysis, migration factors, and urban structure and change that could support more realistic model construction. These sources were not utilised. Forrester offers only six references at the end of his volume and five of them are to other publications of his own. In the absence of this, and given the emphasis the author himself gives to the 'counter-intuitive' policy conclusions, there is the double danger that the general ity of the policy conclusions will be over credited or that the validity and utility of simulation modelling in urban analysis will become discredited. For, in spite of all of this, I would like to emphasise that simulation modelling may have the potential of becoming an important methodology for urban analysis and planning. Forrester's book deserves serious attention as a pioneering effort in this direction. We have much to learn from it. We need to devote more attention to experimenting with such methods. However, I believe that much more attention will have to be given to more realistic modelling and to understanding the legitimate role of simulation methods in supporting the evolutionary experimentation of problem solving social systems. Also implicit in the critical observations presented above is the belief that these models will need to take the form of open systems dealing explicitly with the interface of organisation (in this case the urban system) and environment. Dynamic systems that internalise all feedback loops tend to foreclose realistic modelling in those problem areas of greatest concern to us. EDGAR S. DUNN, JR Resources for the Future, Inc. Washington, D.C.
Can Audit Reforms Affect the Information Role of Audits? Evidence from the German Market

We investigate whether audit reforms affect the information role of audits in a country where the audit traditionally serves a statutory reporting function. Specifically, we investigate the audit market effects of audit reforms mandated by the German government in the Act on Control and Transparency of Enterprises. We test for differences in the types of audit reports issued, the information content of first time going-concern audit opinions, and the demand for dominant audit suppliers pre and post the implementation of the Act to draw inferences on whether the audit reforms enhanced the information role of German audits. We find an increase in the frequency of modified audit opinions after the audit objective changed from verifying assets in place to identifying and reporting concern uncertainties and non-compliant financial reporting practices. We also find an increase in the information content of first time going-concern audit reports issued after the audit reforms are implemented. In addition, the results also indicate an increase in the demand for dominant audit suppliers in the post-reform years. Moreover, we document a significant increase in the number of auditor lawsuits after the audit reforms went into effect. Collectively, our results suggest that the audit reforms improved the information role of German audits and that German firms responded to the improvement in audit reporting by increasing their demand for dominant audit suppliers.
Hemodynamic assessment of acute stroke using dynamic single-slice computed tomographic perfusion imaging.

BACKGROUND Stroke management would benefit from a broadly available imaging tool that detects perfusion deficits in patients with acute stroke. OBJECTIVE To determine the role of dynamic, single-slice computed tomographic (CT) perfusion imaging (CTP) in the assessment of acute middle cerebral artery stroke. DESIGN AND PATIENTS Imaging with CTP and CT within the first 6 hours of symptom onset and before the start of treatment in a consecutive clinical series of 22 patients (mean age, 68.3 years; 14 women; studied within 143 +/- 96 minutes of stroke onset). SETTING A stroke unit in a university hospital. MAIN OUTCOME MEASURES Area of the perfusion deficit (nAP(0)) from time-to-peak maps, hemispheric lesion area from follow-up CT (HLA(F)), final infarct volume, and stroke recovery (National Institutes of Health Stroke Scale scores). RESULTS Eighteen patients had perfusion deficits in the middle cerebral artery territory and corresponding hypoattenuation in follow-up CT. Three patients with normal CTP findings showed lacunar infarctions or normal findings on follow-up CT. In 1 patient, CTP did not reveal a territorial deficit above the imaging slice. The overall sensitivity and specificity of CTP for the detection of perfusion deficits in patients with proven territorial infarction (n = 18) on follow-up CT were 95% and 100%, respectively. The nAP(0) was significantly correlated with the National Institutes of Health Stroke Scale score at admission (P<.003) and the HLA(F) (P<.001). Different stroke patterns were identified in patients with follow-up CTP (n = 10): (1) initial perfusion deficit and partial nutritional reperfusion (nAP(0)>HLA(F); n = 6), (2) initial perfusion deficit and nonnutritional reperfusion (nAP( 0)>/=HLA(F); n = 2), and (3) initial perfusion deficit without reperfusion (nAP(0)>/=HLA(F); n = 2). CONCLUSIONS Computed tomographic perfusion imaging detects major perfusion deficits in the middle cerebral artery territory. Because CTP is broadly available, it may play a role in acute stroke management. Arch Neurol. 2000;57:1161-1166
Union contracts and the life-cycle/permanent-income hypothesis

This paper isolates households in the PSID whose heads can be matched to particular long-term union contracts with high confidence. The author uses use published information on these contracts to construct a household-specific measure of expected wage growth. He finds that predictable wage movements are significantly correlated with consumption changes, contrary to neoclassical consumption theory. The author finds that consumption responds more strongly to predictable income declines than to predictable income increases. This asymmetry is inconsistent with liquidity constraints and myopia but is qualitatively consistent with models in which preferences exhibit loss aversion. Copyright 1995 by American Economic Association.
Quantifying Central Hypotheses on Environmental Kuznets Curves for a Rich Economy: A Computable General Equilibrium Study

We investigate whether the future relationships between several pollutants and per capita income in rich countries may assume the inverted U-forms of Environmental Kuznets Curves (EKC). The emission-augmenting effect of scaling up aggregate economic activity can be counteracted by greener composition of production and consumption, technological progress, and increased demand for environmental quality and policy. To quantify the importance of these central hypotheses, we use a CGE model with endogenous policy for Norway. Our results suggest significant future effects of all these three counteracting mechanisms. For most local and regional pollutants, they may be strong enough to prolong the falling emission trends. However, we cannot rely on reductions in emissions of climate gases and some transport-related local pollutants. Our results also indicate that pollution leakages abroad are likely to take place. Copyright (c) Scottish Economic Society 2003.
The Welfare Cost of Higher Unemployment

THE BASIC PROBLEM OF AGGREGATE economic policy is often posed as "the cruel choice between two evils, unemployment and inflation. "' Although informed policy decisions depend on an accurate assessment of the relative social costs of the two evils in the short run and long run, the welfare economics of inflation has received far more attention in economic analysis than the welfare economics of unemployment.2 Most previous discussions of the latter have been partial and impressionistic catalogues of the economic and psychological effects of unemployment which make no attempt to analyze cyclical unemployment within the conceptual framework of labor supply theory or to provide quantitative estimates of its welfare cost.3 And yet any policy decision to induce a temporary recession by
Competition and Coexistence in Regional Habitats

Habitat heterogeneity plays a key role in the dynamics and structures of communities. In this article, a two‐species metapopulation model that includes local competitive dynamics is analyzed to study the population dynamics of two competing species in spatially structured habitats. When local stochastic extinction can be ignored, there are, as in Lotka‐Volterra equations, four outcomes of interspecific competition in this model. The outcomes of competition depend on the competitive intensity between the competing pairs. An inferior competitor and a superior competitor, or two strongly competing species, can never stably coexist, whereas two weak competitors (even if they are very similar species) may coexist over the long term in such environments. Local stochastic extinction may greatly affect the outcomes of interspecific competition. Two competing species can or cannot stably coexist depending not only on the competitive intensity between the competing pairs but also on their precompetitive distributions. Two weak competitors that have similar precompetitive distributions can always regionally coexist. Two strongly competing species that competitively exclude each other in more stable habitats may be able to stably coexist in highly heterogenous environments if they have similar precompetitive distributions. There is also a chance for an inferior competitor to coexist regionally or even to exclude a superior competitor when the superior competitor has a narrow precompetitive distribution and the inferior competitor has a wide precompetitive distribution.
An essential role for platelet‐activating factor in activating mast cell migration following ultraviolet irradiation

The UVB (290–320 nm) radiation in sunlight is responsible for inducing skin cancer. Exposure to UV radiation is also immunosuppressive, and the systemic immune suppression induced by UV is a well‐recognized risk factor for cancer induction. As UVB radiation is absorbed within the upper layers of the skin, indirect mechanisms must play a role in activating systemic immune suppression. One prominent example is mast cell migration, which from the skin to the draining LN is an essential step in the cascade of events leading to immune suppression. What triggers mast cell migration is not entirely clear. Here, we tested the hypothesis that PAF, a lipid mediator of inflammation produced by the skin in response to UV exposure, is involved. Mast cell‐deficient mice (KitW‐sh/W‐sh) are resistant to the suppressive effect of UV radiation, and reconstituting mast cell‐deficient mice with normal bone marrow‐derived mast cells restores susceptibility to immunosuppression. However, when mast cells from PAFR−/− mice were used, the reconstituted mice were not susceptible to the suppressive effects of UV. Furthermore, PAFR−/− mice showed impaired UV‐induced mast cell migration when compared with WT mice. Finally, injecting PAF into WT mice mimicked the effect of UV irradiation and induced mast cell migration but not in PAFR−/− mice. Our findings indicate that PAFR binding induces mast cells to migrate from the skin to the LNs, where they mediate immune suppression.
Public Information, Public Learning, and Public Opinion: Democratic Accountability in Education Policy

Theories of political accountability assume citizens use information about the performance of government to hold public officials accountable, but whether citizens actually use information is difficult to directly examine. We take advantage of the importance of citizen-driven, performance-based accountability for education policy in Tennessee to conduct a survey experiment that identifies the effect of new information, mistaken beliefs and differing considerations on the evaluation of public officials and policy reforms using 1,500 Tennesseans. Despite an emphasis on reporting outcomes for school accountability policies in the state, mistaken beliefs are prevalent and produce overly optimistic assessments of the institutions responsible for statewide education policy. Moreover, individuals update their assessments of these institutions in an unbiased way when provided with objective performance data about overall student performance. Providing additional information about race-related performance differences does not alter this relationship, however. Finally, support for specific policies that are intended to improve student performance is unchanged by either type of performance information; opinions about policy reforms are instead most related to race and existing partisan commitments.
Leadership skills and competencies for cross-cultural construction projects

Cross-cultural projects are increasingly common in construction. Project leaders need to develop skills and competencies that can help them to effectively perform their leadership roles in such projects. In order to examine the leadership competencies and skills required to lead projects in a multicultural environment, questionnaire surveys and interviews were conducted with project leaders on a mega construction project in Thailand. A total of 78 respondents from ten different nationalities participated in the study. They belonged to various construction stakeholders such as clients, consultants, designers and contractors. Leadership competencies such as communication, teamwork, and personal and interpersonal skills were perceived to be vital for project leaders in a multicultural environment. Flexibility in decision making, persistent performance, good listening skills and problem-solving style were also highlighted among the top-rated competencies of cross-cultural leaders. In order to develop cross-cultural leadership competencies, the respondents emphasised comprehensive training and orientation as well as inclusion of cross-cultural leadership courses at graduate-level programmes in universities.
Learning model-based planning from scratch

Conventional wisdom holds that model-based planning is a powerful approach to sequential decision-making. It is often very challenging in practice, however, because while a model can be used to evaluate a plan, it does not prescribe how to construct a plan. Here we introduce the "Imagination-based Planner", the first model-based, sequential decision-making agent that can learn to construct, evaluate, and execute plans. Before any action, it can perform a variable number of imagination steps, which involve proposing an imagined action and evaluating it with its model-based imagination. All imagined actions and outcomes are aggregated, iteratively, into a "plan context" which conditions future real and imagined actions. The agent can even decide how to imagine: testing out alternative imagined actions, chaining sequences of actions together, or building a more complex "imagination tree" by navigating flexibly among the previously imagined states using a learned policy. And our agent can learn to plan economically, jointly optimizing for external rewards and computational costs associated with using its imagination. We show that our architecture can learn to solve a challenging continuous control problem, and also learn elaborate planning strategies in a discrete maze-solving task. Our work opens a new direction toward learning the components of a model-based planning system and how to use them.
The impact of daily text message reminders on medication adherence in healthy volunteers and patients with coronary artery disease

Background: Rates of medication nonadherence are high, which can lead to disease progression, disability and death. objective: To test a potential solution to improve adherence to medications using a novel computer-based text message reminder system. Methods: An automated computer program to send text messages to cell phones was developed. In phase 1, the reliability of the system was tested by sending text messages four times daily for two months to four volunteers. In phase 2, 20 healthy volunteers were asked to take a placebo at four prespecified times per day for one week with text message reminders and one week without. In Phase 3, 30 random, stable cardiac patients were recruited and instructed to take and record medications according to their own regimen for one month with text message reminders and one month without. Results: In phase 1, the system accurately delivered 100% of reminder messages. In phase 2, the adherence to placebos improved with text message reminders in 88% of healthy volunteers, with a 65% relative risk reduction for nonadherence (P<0.01). In phase 3, adherence to medication with text message reminder improved in 100% of cardiac patients, with a 64% relative risk reduction for nonadherence (P<0.01). In all subgroups analyzed, text message reminders significantly improved medication adherence. Conclusions: The system proved to be effective in improving adherence to placebo in healthy volunteers and to medications in cardiac patients over a two-month period. Further research is required to assess the effects of this system over longer periods of time and in more diverse populations.
Government Spending, Local Indeterminacy and Tax Structure

This paper develops an endogenous growth model where sustained growth is due to the introduction of a public input. Consumers derive utility from consumption, leisure and a public good. The public input and the public good are the flow of government expenditures. These expenditures are financed by means of income taxes. With these assumptions, it is shown that the dynamic equilibrium may exhibit local indeterminacy when the tax rate on the labour income is large. The tax structure that maximizes growth and the optimal tax structure are characterized and compared.