1,442 research outputs found
Were Trade and Factor Mobility Substitutes in History?
Trade theorists have come to understand that their theory is ambiguous on the question: Are trade and factor flows substitutes? While this sounds like an open invitation for empirical research, hardly any serious econometric work has appeared in the literature. This paper uses history to fill the gap. It treats the experience of the Atlantic economy between 1870 and 1940 as panel data with almost seven hundred observations. When shorter run business cycles and long swings' are extracted from the panel data, substitutability is soundly rejected. When secular relationships are extracted over longer time periods and across trading partners, once again substitutability is soundly rejected. Finally, the paper explores immigration policy and finds that policy makers never behaved as if they viewed trade and immigration as substitutes.
Strategic Decision-Making in High Velocity Environments: A Theory Revisited and a Test
[Excerpt] A decade ago, Eisenhardt (1989) proposed a model of strategic decision-making speed for firms facing high-velocity environments. This theory, while important at the time, has become even more relevant to the strategy-making bodies of firms in the entrepreneurial millennium. The model differed in important ways from much of the existing literature on decision-making speed (Frederickson and Mitchell, 1984; Janis, 1982; Mintzberg, et al., 1976; Nutt, 1976). Eisenhardt\u27s ideas were based on a series of inductive case studies of eight firms competing in the fast-paced micro-chip industry. As such, it was an important theory-building effort in a central area of strategy process, strategic decision-making. To date, however, there have been no attempts to comprehensively test the model with a larger sample of firms.
The changes the economy is experiencing in this new millennium are astounding. In short, the hyper-competitive forces faced a decade ago by micro-chip makers have become pervasive throughout many of our top industries (D\u27Aveni, 1994; Grimm and Smith, 1997). Thus, the prescriptions of Eisenhardt\u27s model would appear to be critical for today\u27s firms as they seek entrepreneurial approaches to gaining competitive advantage. Top management teams (TMTs) capable of making rapid decisions can enable their firms to be the entrepreneurial first movers in their respective segments. To our knowledge, however, there has been only one attempt to replicate Eisenhardt\u27s preliminary findings. Judge and Miller (1991) tested a portion of the model on a small sample (n = 32) of firms in three industries. The research tested two of the five tactics mentioned by Eisenhardt, did not incorporate the intervening processes, and produced mixed results. Thus, there have been no successful attempts to test the entire model on a large cross-section of firms. This is due in part to the difficulty researchers face in gaining access to a large sample of top executives, especially those facing fast-paced environments. This research tests Eisenhardt\u27s model on a sample of 66 high technology firms competing in the IT, telecommunications, and engineering services industries
In situ propellant production: Alternatives for Mars exploration
Current planning for the Space Exploration Initiative (SEI) recognizes the need for extraterrestrial resources to sustain long-term human presence and to attain some degree of self-sufficiency. As a practical matter, reducing the need to carry large supplies of propellant from Earth will make space exploration more economical. For nearly every round trip planned with conventional propulsion, the actual payload is only a small fraction - perhaps 10-15 percent - of the mass launched from Earth. The objective of this study was to analyze the potential application for SEI missions of propellants made exclusively from lunar or martian resources. Using such propellants could minimize or eliminate the cost of carrying propellant for surface excursion vehicles and return transfers through two high-energy maneuvers: Earth launch and trans-Mars injection. Certain chemical mono- and bipropellants are candidates for this approach; they could be recovered entirely from in situ resources on the Moon and Mars, without requiring a continuing Earth-based resupply of propellant constituents (e.g., fuel to mix with a locally obtained oxidizer) and, perhaps, with minimal need to resupply consumables (e.g., reagents or catalyst for process reactions). A complete assessment of the performance potential of these propellants must include the requirements for installation, operations, maintenance, and resupply of the chemical processing facility
Hierarchy of Protein Assembly at the Vertex Ring Domain for Yeast Vacuole Docking and Fusion
Vacuole tethering, docking, and fusion proteins assemble into a “vertex ring” around the apposed membranes of tethered vacuoles before catalyzing fusion. Inhibitors of the fusion reaction selectively interrupt protein assembly into the vertex ring, establishing a causal assembly hierarchy: (a) The Rab GTPase Ypt7p mediates vacuole tethering and forms the initial vertex ring, independent of t-SNAREs or actin; (b) F-actin disassembly and GTP-bound Ypt7p direct the localization of other fusion factors; (c) The t-SNAREs Vam3p and Vam7p regulate each other’s vertex enrichment, but do not affect Ypt7p localization. The v-SNARE Vti1p is enriched at vertices by a distinct pathway that is independent of the t-SNAREs, whereas both t-SNAREs will localize to vertices when trans-pairing of SNAREs is blocked. Thus, trans-SNARE pairing is not required for SNARE vertex enrichment; and (d) The t-SNAREs regulate the vertex enrichment of both G-actin and the Ypt7p effector complex for homotypic fusion and vacuole protein sorting (HOPS). In accord with this hierarchy concept, the HOPS complex, at the end of the vertex assembly hierarchy, is most enriched at those vertices with abundant Ypt7p, which is at the start of the hierarchy. Our findings provide a unique view of the functional relationships between GTPases, SNAREs, and actin in membrane fusion
Tuning and controlling gene expression noise in synthetic gene networks
Synthetic gene networks can be used to control gene expression and cellular phenotypes in a variety of applications. In many instances, however, such networks can behave unreliably due to gene expression noise. Accordingly, there is a need to develop systematic means to tune gene expression noise, so that it can be suppressed in some cases and harnessed in others, e.g. in cellular differentiation to create population-wide heterogeneity. Here, we present a method for controlling noise in synthetic eukaryotic gene expression systems, utilizing reduction of noise levels by TATA box mutations and noise propagation in transcriptional cascades. Specifically, we introduce TATA box mutations into promoters driving TetR expression and show that these mutations can be used to effectively tune the noise of a target gene while decoupling it from the mean, with negligible effects on the dynamic range and basal expression. We apply mathematical and computational modeling to explain the experimentally observed effects of TATA box mutations. This work, which highlights some important aspects of noise propagation in gene regulatory cascades, has practical implications for implementing gene expression control in synthetic gene networks
A Qualitative Analysis of Student Understanding of Team Function Through the use of the Jefferson Teamwork Observation Guide (JTOG)
Background:
Several early IOM reports identified the need to educate medical and health professions students in delivering patient-centered care as members of interprofessional teams (IOM, 2001; IOM, 2003). Evidence shows that conducting interprofessional education during education and training prepares student learners for collaborative practice when they enter the workplace, which in turn helps to achieve the Triple Aim of 1) enhancing the patient experience; 2) improving the health of populations; and 3) decreasing costs (WHO, 2010; Berwick, et al., 2008). One way to prepare students for collaborative practice is to have them observe real teams in action. Thus, the Jefferson Teamwork Observation Guide (JTOG) was created to serve as an educational tool in aiding students to better recognize the characteristics of effective teams. It has since been used to assess teams in the majority of clinical observation, simulation and collaborative practice activities offered by Jefferson Center for Interprofessional Education (JCIPE).
The JTOG is a two-part assessment comprised of identifiable characteristics of well-functioning teams drawn from the literature about teamwork. The first part consists of Likert Scale questions (strongly disagree to strongly agree) regarding the behavior of the interprofessional team observed in the domains of Values/Ethics in Interprofessional Practice, Roles/Responsibilities, Interprofessional Communication, Teams and Teamwork, and Leadership (IPEC, 2011; IPEC 2016). The second part includes qualitative questions relating to team-based care, patient-centered care, and teamwork
Collagen gene sequence variants in exercise-related traits
Collagens are major structural proteins of tendons, ligaments and other components of musculoskeletal tissues. Rare mutations in many of the genes, which encode for the collagen α-chains, result in serious musculoskeletal disorders, highlighting the importance of this protein family in the normal structure an d function of musculoskeletal tissues. Since these rare mutations cause severe disorders, it has been proposed that a lack of biological redundancy exists within the collagen fibril, and that collagen-encoding genes are therefore ideal candidates for association with less severe exercise-related traits. This review identifies a number of collagen gene variants which are associated with various exercise-related traits. Based on the evidence outlined in this review, we propose that a general genetic continuum exists for collagen genes and their associated traits. At one end of this general continuum model, a single mutation within one or more collagen genes will result in severe Mendelian disorders. At the other end of the continuum, functional variants within these collagen genes collectively contribute to the aetiology of anomalous multifactorial connective tissue traits, which arise as a result of the interaction of genetic and non-genetic factors which modulate physiological responses to environmental stimuli
Assessing the effectiveness and cost-effectiveness of drug intervention programs: UK case study
The effectiveness and cost-effectiveness of the UK Drug Interventions Program which directs adult drug-misusing offenders out of crime and into treatment programs was established. Quality-adjusted life year estimates from the UK Drug Treatment Outcomes Research Study were collected and a cost-utility assessment of the Drug Interventions Program was conducted. Cost-utility assessment confirmed that the Drug Interventions Program is both effective and cost-effective with an average net cost saving of £668 (£6,207 including one case of homicide). This study provides evidence that drug intervention programs are cost-effective as they reduce crime, improve quality-of-life and reduce subsequent drug use
The XMM Cluster Survey: a massive galaxy cluster at z = 1.45
We report the discovery of XMMXCS J2215.9-1738, a massive galaxy cluster at z=1.45, which was found in the XMM Cluster Survey. The cluster candidate was initially identified as an extended X-ray source in archival XMM data. Optical spectroscopy shows that six galaxies within a ~60" diameter region lie at z=1.45+/-0.01. Model fits to the X-ray spectra of the extended emission yield kT=7.4+2.7-1.8 keV (90% confidence); if there is an undetected central X-ray point source, then kT=6.5+2.6-1.8 keV. The bolometric X-ray luminosity is LX=4.4+0.8-0.6C 1044 ergs s-1 over a 2 Mpc radial region. The measured TX, which is the highest for any known cluster at z>1, suggests that this cluster is relatively massive for such a high redshift. The redshift of XMMXCS J2215.9-1738 is the highest currently known for a spectroscopically confirmed cluster of galaxies
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