Seminal Model Research Articles

A novel rat model of seminal vesiculitis.

We aimed to establish a novel rat model of seminal vesiculitis that would provide an effective approach to investigate the pathogenesis of this disease in the future. Eight male rats received the same operation, during which the root of one of the two seminal vesicles was partly ligatured with sutures and the other vesicle was left intact. The samples of seminal vesicles were harvested on the 8th day following the operation. Hematoxylin and eosin and Masson's trichrome stains were used to observe the histopathology and the presence of fibrous tissue in seminal vesicles, respectively. Immunoblotting and immunohistochemistry were applied to determine the tumor necrosis factor-alpha and cyclooxygenase-2 levels in seminal vesicle tissues. Real-time fluorescence quantitative polymerase chain reaction was performed to measure the gene expression levels of proinflammatory cytokines. H2O2 levels in the seminal plasma from the seminal vesicle were also measured. Hematoxylin and eosin staining suggested that there was inflammatory cell infiltration into the seminal vesicles treated by partial root ligation. The tumor necrosis factor-alpha and cyclooxygenase-2 proteins were significantly upregulated in the treated seminal vesicles. The tumor necrosis factor-alpha, cyclooxygenase, interleukin 6, and inducible nitric oxide synthase mRNA expression levels were also upregulated in the treated seminal vesicles. The H2O2 levels in the seminal plasma from seminal vesicles with partial root ligation were significantly elevated compared with those from vesicle left intact. In conclusion, partially ligating the root of the seminal vesicle via sutures in rats is an effective method to establish a seminal vesiculitis rat model.

WORLD INTEREST RATES AND INEQUALITY: INSIGHT FROM THE GALOR–ZEIRA MODEL

In this paper, we study the relationship between changes in the world interest rate and within-country inequality during the 1985–2005 period in which the world interest rate sharply declined. In line with the predictions of the seminal model of Galor and Zeira [Income distribution and macroeconomics. Review of Economic Studies 60, 35–52], the analysis suggests that the decrease in the world interest rate is associated with a decrease in inequality in poor countries and an increase in inequality in rich ones.

Asymptotic properties of the maximum likelihood estimator in regime switching econometric models

Markov regime switching models have been widely used in numerous empirical applications in economics and finance. However, the asymptotic distribution of the maximum likelihood estimator (MLE) has not been proven for some empirically popular Markov regime switching models. In particular, the asymptotic distribution of the MLE has been unknown for models in which some elements of the transition probability matrix have the value of zero, as is commonly assumed in empirical applications with models with more than two regimes. This also includes models in which the regime-specific density depends on both the current and the lagged regimes such as the seminal model of Hamilton (1989) and switching ARCH model of Hamilton and Susmel (1994). This paper shows the asymptotic normality of the MLE and consistency of the asymptotic covariance matrix estimate of these models.

Disentangling phonological and articulatory processing: A neuroanatomical study in aphasia

Phonological and articulatory programming impairments may co-occur in aphasic patients and previous research does not offer a clear-cut picture of their anatomical counterparts. Hickok and Poeppel (2007) put forward a seminal model of speech processes. The ventral stream (mostly bilateral) would be involved in speech recognition and phonological-lexical processing, whereas the dorsal stream (largely lateralized to the left hemisphere) would map phonological representations onto articulatory motor patterns. In this study we analyzed repetition errors for single words and spontaneous speech ratings on the Italian version of the Aachen Aphasia Test. Through a VLSM procedure we aimed at discriminating the neuroanatomical substrates of the phonological and articulatory impairment (and of their normal functional processing). We also estimated functional connectivity networks related to articulation and phonology using seed-to-voxel connectivity analysis with resting state fMRI data. Results indicate that repetition deficit of single words is associated with lesions in a network of left perisylvian areas including the central operculum, the Heschl's gyrus, the angular gyrus, and the supramarginal gyrus (posterior part). Articulatory impairment is associated with lesions in a number of areas in the left dorsal stream, such as the insula (anterior portion), the pars opercularis of the inferior frontal gyrus, the central operculum and the precentral gyrus. On the contrary, phonological impairment is underpinned by lesions of the Heschl's gyrus, and of the posterior portion of the superior temporal and supramarginal gyri. Anatomo-clinical correlative results partly support Hickok and Poeppel's functional model of phonological and articulatory processing.

Towards the validation of a new, blended theoretical model of fear of cancer recurrence.

Fear of cancer recurrence (FCR) is defined as "fear, worry, or concern about cancer returning or progressing". To date, only the seminal model proposed by Lee-Jones and colleagues has been partially validated, so additional model testing is critical to inform intervention efforts. The purpose of this study is to examine the validity of a blended model of FCR that integrates Leventhal's Common Sense Model, Mishel's Uncertainty in Illness Theory, and cognitive theories of worry. Participants (n=106) were women diagnosed with stage I to III breast or gynecological cancer who were enrolled in a Randomized Controlled Trial of a group cognitive-existential intervention for FCR. We report data from standardized questionnaires (Fear of Cancer Recurrence Inventory-Severity and Triggers subscales; Illness Uncertainty Scale; perceived risk of recurrence; Intolerance of Uncertainty Scale; Why do people Worry about Health questionnaire; Reassurance-seeking Behaviors subscale of the Health Anxiety Questionnaire, and the Reassurance Questionnaire) that participants completed before randomization. Path analyses were used to test the model. Following the addition of four paths, the model showed an excellent fit (χ2=13.39, P=0.20; comparative fit index=0.99; root mean square error of approximation=0.06). Triggers, perceived risk of recurrence, and illness uncertainty predicted FCR. FCR was associated with maladaptive coping. Positive beliefs about worrying and intolerance of uncertainty did not predict FCR but led to more maladaptive coping. These results provide support for a blended FCR model.

On the treatment of persons with disabilities in organizations: A review and research agenda

Human resource practitioners play a crucial role in promoting equitable treatment of persons with disabilities, and practitioner's decisions should be guided by solid evidence‐based research. We offer a systematic review of the empirical research on the treatment of persons with disabilities in organizations, using Stone and Colella's seminal theoretical model of the factors influencing the treatment of persons with disabilities in work organizations, to ask: What does the available research reveal about workplace treatment of persons with disabilities, and what remains understudied? Our review of 88 empirical studies from management, rehabilitation, psychology, and sociology research highlights seven gaps and limitations in extant research: (a) implicit definitions of workplace treatment; (b) neglect of national context variation; (c) missing differentiation between disability populations; (d) overreliance on available data sets; (e) predominance of single‐source, cross‐sectional data; (f) neglect of individual differences and identities in the presence of disability; and (g) lack of specificity on underlying stigma processes. To support the development of more inclusive workplaces, we recommend increased research collaborations between human resource researchers and practitioners on the study of specific disabilities and contexts, and efforts to define and expand notions of treatment to capture more nuanced outcomes.

Testing Factor Models in Indonesia

Fama and French (2015) recently proposed a five-factor model which adds investment and profitability terms to their seminal three-factor model. Motivated by the accounting-based nature of the new factors, we conduct a comprehensive test of variants of the models in Indonesia – a country which previous researchers have characterized by an idiosyncratic financial reporting environment and low earnings quality. We show that the traditional three-factor model works poorly in Indonesia. However, despite large and significant profitability and investment premiums, the five-factor model offers at best only a trivial improvement to the description of average returns.

Trade Liberalization and Constraints on Moves to Protectionism: Multilateralism vs. Regionalism

AbstractIn this article, two key questions are asked: why has the General Agreement on Tariffs and Trade (GATT) and its predecessor the World Trade Organization (WTO) worked in terms of multilateral tariff reduction and promotion of global trade, and to what extent will it act as a constraint on economic nationalism? To answer these two questions, three themes are laid out in the article: first, the seminal economic model rationalizing the economic logic of the GATT/WTO is assessed; second, the perceived relevance of the GATT/WTO in a world of increasing regionalism is discussed; and third, the robustness of the GATT/WTO legal framework and dispute resolution mechanism is evaluated. The key conclusion is that the underlying economic logic of the GATT/WTO is still relevant, but that enforcement of the cooperative agreement will likely be placed under significant strain with the threat of increased protection, and even a potential trade war.

Chargeability of Porous Rocks With or Without Metallic Particles

The chargeability of rocks de nes their ability to reversibly store electrical charges at low frequency (typically below a few kHz). We consider the case of an isotropic mixture of metallic particles embedded into a polarizable porous background composed of mineral grains and pore water. The term metallic is here used in a broad sense involving semiconductors (for instance disseminated pyrite or magnetite), semimetals (e.g., graphite), and metals (copper, steel). The chargeability of such a mixture depends on the chargeability of the background material and the volumetric amount of metallic particles. The chargeability of the background material is in turn salinity dependent and is equal to a universal dimensionless number R = 0.08 (ratio between the normalized chargeability and the surface conductivity) at low salinities. It is given by the ratio of two apparent mobilities, which are actually related to the mobility of the Stern and diffuse layers forming the so-called electrical double layer around the mineral grains. This universal number is saturation and temperature independent. The predictive model for the chargeability of the mixture is compared successfully to variety of experimental and eld data. We show that the polarization of dispersed metallic particles is due to the electrodiffusion of the charge carriers inside these particles. This work can be applied to conventional well-log analysis using the dispersion of the electrical conductivity with the frequency in order to determine the formation properties and accounting for the presence of pyrite in some formations. Our conductivity model appears as an extension of the Waxman and Smits seminal model of shaly sands extending this model to determine the chargeability and the effect of pyrite on both the electrical conductivity and the chargeability.

Sustainable supply chain management: Decision models for transformation and maturity

Academics and practitioners have realized that supply chains with their many interactions and impacts have to be investigated in order to meet corporate sustainability imperatives. Research has thus far offered only limited theoretical guidance while practical applications often lack a systematic approach. The realization of sustainability goals is impeded by disconnects between supply chain vision, strategy, and execution. This research bridges this gap and offers guidance through the identification and description of influential factors and decision models.An exploratory Delphi study involved supply chain and sustainability experts with the goal to explore and propose factors and decision processes for sustainable supply chain management. This study builds upon the insights offered by seminal models and leverages the Delphi mechanisms of exploration and controlled feedback in order to design, refine, and validate decision models through three consecutive rounds. This Delphi facilitated the identification and assessment of vital relationships and influential factors for sustainable supply chain management. The study culminates in the design and validation of models specifically targeted at the transformation and on-going maturity development of sustainable supply chains. The combination of research outcomes provides targeted decision support to supply chain managers which is desperately needed in order to drive sustainability development and implementation. The main contributions of the study thus are (1) the design of prescriptive artefacts that describe relationships in SSCM, (2) to offer targeted and evaluated decision support functionalities for sustainable supply chains, and (3) to provide fertile ground for future research enquiries.

O cuidado das condições crônicas na atenção primária à saúde

O cuidado das condições crônicas na atenção primária à saúde

Replication Fork Breakage and Restart in Escherichia coli

In all organisms, replication impairments are an important source of genome rearrangements, mainly because of the formation of double-stranded DNA (dsDNA) ends at inactivated replication forks. Three reactions for the formation of dsDNA ends at replication forks were originally described for Escherichia coli and became seminal models for all organisms: the encounter of replication forks with preexisting single-stranded DNA (ssDNA) interruptions, replication fork reversal, and head-to-tail collisions of successive replication rounds. Here, we first review the experimental evidence that now allows us to know when, where, and how these three different reactions occur in E. coli. Next, we recall our recent studies showing that in wild-type E. coli, spontaneous replication fork breakage occurs in 18% of cells at each generation. We propose that it results from the replication of preexisting nicks or gaps, since it does not involve replication fork reversal or head-to-tail fork collisions. In the recB mutant, deficient for double-strand break (DSB) repair, fork breakage triggers DSBs in the chromosome terminus during cell division, a reaction that is heritable for several generations. Finally, we recapitulate several observations suggesting that restart from intact inactivated replication forks and restart from recombination intermediates require different sets of enzymatic activities. The finding that 18% of cells suffer replication fork breakage suggests that DNA remains intact at most inactivated forks. Similarly, only 18% of cells need the helicase loader for replication restart, which leads us to speculate that the replicative helicase remains on DNA at intact inactivated replication forks and is reactivated by the replication restart proteins.

Electron correlations and pre-collision in the re-collision picture of high harmonic generation

We discuss the seminal three-step model and the re-collision picture in the context of high harmonic generation in molecules. In particular, we stress the importance of multi-electron correlation during the first and the third of the three steps of the process: (1) the strong-field ionization and (3) the recombination. We point out how an accurate account of multi-electron correlations during the third recombination step allows one to gauge the importance of pre-collision: the term coined by Eberly ( private communication) to describe unusual pathways during the first, ionization, step.

The benefits of combining early aspecific vaccination with later specific vaccination

Timing is of crucial importance for successful vaccination. To avoid a large outbreak, vaccines should be administered as quickly as possible. However, during early stages of an outbreak the information on the disease is limited and delaying the intervention enables the design of a more tailored vaccination strategy. In this paper, we study the resulting trade-off between vaccination timing and an effective response strategy.We model disease progression using the seminal SIR model, and consider a decision maker who allocates her budget over two vaccine types: an early aspecific vaccine and a later specific vaccine. We analytically characterize the switching curve separating the parameter space region where the late specific vaccine is preferred from the region where the early aspecific type is preferred. More importantly, we show that the decision maker should not only consider pure strategies, i.e., strategies which spend the entire budget on one of the types. Instead, she should invest in both vaccine types to benefit both from an early response and from an effective vaccine. We prove that at the switching curve, such a hybrid strategy is strictly better than either of the pure strategies due to the non-linear dynamics of epidemics. Our numerical experiments show that a hybrid strategy can reduce the number of infections by more than 50% compared to the best pure strategy. Such experiments also substantiate our restriction to two vaccine types.

A laboratory experiment on the heuristic switching model

We present results from the first laboratory experiment on the seminal heuristic switching model introduced by Brock and Hommes (1997, 1998). Subjects choose between two alternatives, a sophisticated and stabilizing, but costly, heuristic, and a destabilizing, but cheap, heuristic, and are paid according to the performance of the chosen heuristic. Aggregate choices determine the evolution of a state variable and, consequently, the performance of both heuristics. Theoretically, an increase in the costs for the stabilizing heuristic generates instability and leads to endogenous fluctuations in both the state variable and the fraction of agents using that heuristic.We vary the costs of the stabilizing heuristic in the experiment and find that the predictions of the heuristic switching model are partially confirmed. For low costs the dynamics are stable. For high costs, the dynamics initially are unstable and exhibit the type of bubbles and crashes emblematic for the heuristic switching model. However, over time the pattern of bubbles and crashes disappears and the dynamics become more stable. We estimate a standard discrete choice model on aggregate choice data and observe that subjects have a tendency to become less sensitive to payoff differences when the environment is less stable, which has important implications for the application of heuristic switching models.

Law and Macroeconomics as Aggregate Demand Externalities: An Application to Optimal Tort Law

This paper presents one method for introducing macroeconomic concerns into the standard microeconomic models of law, using the canonical economic model of tort law as an example. When an economy suffers from inadequate aggregate demand, expendi-tures on precautions to avoid injuries have aggregate demand externalities. In addition to reducing damages from injury, expenditures on precautions raise incomes for the sellers of precautions (e.g., car brake mechanics). With higher incomes, the sellers, in turn, con-sume and invest more. This multiplier effect of the original expenditure on total spending and output can be modelled as an aggregate demand externality and incorporated into the standard economic models of law. When I introduce aggregate demand externalities into the seminal economic model of tort law, we come to very different conclusions than is standard. Specifically, the strict liability rule and the Hand Rule for negligence both pro-duce inefficient outcomes with respect to expenditures on precaution and activity levels. Instead, negligence rules with more stringent standards of care than the Hand Rule be-come more efficient. If standards of care get too high, however, then an enhanced negligence rule no longer yields a better outcome than strict liability or the Hand Rule. Optimal tort law therefore looks very different when we introduce aggregate demand ex-ternalities. If efficient tort law changes when we introduce macroeconomic effects, then we can presume that our law and microeconomic conclusions regarding other areas of law will change as well.

Financially-constrained lawyers: An economic theory of legal disputes

Financial constraints reduce the lawyer's ability to file lawsuits and bring cases to trial. As a result, access to justice for victims, pretrial bargaining, and potential injurers' precaution might be affected. We study civil litigation using a model that allows for asymmetric information, financially-constrained lawyers, third-party lawyer lending, and a continuum of plaintiff's types. We contribute to the economic analysis of law by generalizing seminal models of litigation (Bebchuk, 1984, 1988; Katz, 1990), offering the first formal definition of access to justice, and presenting comprehensive social welfare analysis of relevant public policy. We provide complete equilibrium characterization and identify necessary conditions for the existence of the mixed- and pure-strategy PBE. Access to justice is denied to some victims under the mixed-strategy equilibrium. We then study the social welfare effects of policies aimed at relaxing lawyers' financial constraints, and identify a necessary and sufficient condition for a welfare-enhancing effect.

Single-target regulators form a minor group of transcription factors in Escherichia coli K-12.

The identification of regulatory targets of all TFs is critical for understanding the entire network of the genome regulation. The lac regulon of Escherichia coli K-12 W3110 is composed of the lacZYA operon and its repressor lacI gene, and has long been recognized as the seminal model of transcription regulation in bacteria with only one highly preferred target. After the Genomic SELEX screening in vitro of more than 200 transcription factors (TFs) from E. coli K-12, however, we found that most TFs regulate multiple target genes. With respect to the number of regulatory targets, a total of these 200 E. coli TFs form a hierarchy ranging from a single target to as many as 1000 targets. Here we focus a total of 13 single-target TFs, 9 known TFs (BetI, KdpE, LacI, MarR, NanR, RpiR, TorR, UlaR and UxuR) and 4 uncharacterized TFs (YagI, YbaO, YbiH and YeaM), altogether forming only a minor group of TFs in E. coli. These single-target TFs were classified into three groups based on their functional regulation.

Mean growth and stochastic stability in endogenous growth models

Under uncertainty, mean growth of, say, wealth is often defined as the growth rate of average wealth, but it can alternatively be defined as the average growth rate of wealth. We argue that stochastic stability points to the latter notion of mean growth as the theoretically relevant one. Our discussion is cast within the class of continuous-time AK-type models subject to geometric Brownian motions. First, stability concepts related to stochastic linear homogeneous differential equations are introduced and applied to the canonical AK model. It is readily shown that exponential balanced-growth paths are not robust to uncertainty. In a second application, we evaluate the quantitative implications of adopting the stochastic-stability-related concept of mean growth for the comparative statics of global diversification in the seminal model due to Obstfeld (1994).

Social commerce: a taxonomy and cross-component investigation of business practices and technological choices

Social commerce (SC) is a form of e-commerce (EC) that involves social media, online media that support social interaction and user contributions to assist the online buying and selling of products and services. Although SC has a straightforward definition, it is difficult to circumscribe SC firms' practices because of rapidly changing trends in digital markets, business strategies and new technological solutions. Collecting data concerning firms active in the EC sector, this paper provides an updated and extensive taxonomy of SC firms' business strategies and technological choices based on the seminal model developed by Wang and Zhang (2012) and, by means of a network analysis, proposes an original investigation of SC practices across the components of the model. Identifying preferred social channels, common technological requirements, payment systems, forefront marketing tools and so on, and realising the way each component interrelates with the others, has interesting implications for professionals, researchers and practitioners. Highlights of this paper are: large-scale business study on seven thousands e-commerce firms; extensive collection and organisation of metadata to describe firms' strategies and choices; updated taxonomy of social commerce based on Wang and Zhang (2012) seminal model; cross-component investigation to capture business and technological patterns.