130,775 research outputs found
Observationes Qvasdam Et Conclvsiones Circa Calorem Et Frigvs Maxime Hiemis M D CC. XL. Praeside Ioan. Andrea Segnero ... Pvblice Proponet Atqve Defendet Frider. Lvdov. Christ. Cropp ...
No full textOBSERVATIONES QVASDAM ET CONCLVSIONES CIRCA CALOREM ET FRIGVS MAXIME HIEMIS M D CC. XL. PRAESIDE IOAN. ANDREA SEGNERO ... PVBLICE PROPONET ATQVE DEFENDET FRIDER. LVDOV. CHRIST. CROPP ...
Observationes Qvasdam Et Conclvsiones Circa Calorem Et Frigvs Maxime Hiemis M D CC. XL. Praeside Ioan. Andrea Segnero ... Pvblice Proponet Atqve Defendet Frider. Lvdov. Christ. Cropp ... (1)
Cover (1)
Titelblatt (3)
Widmung (5)
Dedicatio. (6)
Sectio I. (9)
Sectio II. (32)
Epistola. (45)
Fotodokumentation (51
Analogue black holes in relativistic BECs: Mimicking Killing and universal horizons
No full textRelativistic Bose-Einstein condensates (rBECs) have recently become a
well-established system for analogue gravity. Indeed, while such
relativistic systems cannot be yet realized experimentally, they provide
an interesting framework for mimicking metrics for which no analogue is
yet available, thus paving the way for further theoretical and numerical
explorations. In this vein, we here discuss black holes in rBECs and
explore how their features relate to the bulk properties of the system.
We then propose the coupling of external fields to the rBEC as a way to
mimic nonmetric features. In particular, we use a Proca field to
simulate an aether field, as found in Einstein-aether or Ho.
rava-Lifshitz gravity. This allows us to mimic a universal horizon, the
causal barrier relevant for superluminal modes in these modified
gravitational theories
MeSH term explosion and author rank improve expert recommendations
No full textInformation overload is an often-cited phenomenon that reduces the productivity, efficiency and efficacy of scientists. One challenge for scientists is to find appropriate collaborators in their research. The literature describes various solutions to the problem of expertise location, but most current approaches do not appear to be very suitable for expert recommendations in biomedical research. In this study, we present the development and initial evaluation of a vector space model-based algorithm to calculate researcher similarity using four inputs: 1) MeSH terms of publications; 2) MeSH terms and author rank; 3) exploded MeSH terms; and 4) exploded MeSH terms and author rank. We developed and evaluated the algorithm using a data set of 17,525 authors and their 22,542 papers. On average, our algorithms correctly predicted 2.5 of the top 5/10 coauthors of individual scientists. Exploded MeSH and author rank outperformed all other algorithms in accuracy, followed closely by MeSH and author rank. Our results show that the accuracy of MeSH term-based matching can be enhanced with other metadata such as author rank
The Role of Contracts in the Organic Supply Chain: 2004 and 2007
No full textOrganic food products are excellent candidates for contract production and marketing because they are produced using a distinct process and are in high demand. This report summarizes survey data on contracting in the organic sector, addressing the extent of contracting, the rationale for using contracts, and contract design for select commodities. The central survey data were collected from certified organic handlers (intermediaries)in the United States who marketed and procured organic products in 2004 and 2007. Contracting is widespread in the organic sector, and, in 2007, firms used contracts most frequently to secure organic products essential to their business and to source products in short supply. Large firms were more likely to use contracts for procurement, and these firms contracted for a larger share of their procurement needs. Nearly all contracts required suppliers to provide evidence of organic certification. Firms using contracts rarely assisted suppliers with obtaining organic certification or the transition to organic. Most contracts include provisions regarding quality, and quality verification was an essential component of these contracts. Prices were determined in a variety of ways and, in some cases, depended on delivered quality.Organic supply chain, contracts, organic marketing, organic procurement, intermediaries, certified organic handlers, contract design, certified organic, Agribusiness, Marketing,
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
"Closing the R&D Gap, Evaluating the Sources of R&D Spending"
No full textBoth spending and tax policies have been implemented in the United States with the goal of stimulating private sector research and development (R&D). Karier questions whether current R&D policy, especially the research and experimentation tax credit, can contribute to closing the gap between nondefense expenditures on R&D in the United States and such expenditures in other countries, such as Japan and Germany. He also explores possible changes to our current R&D policy to make it more effective.
Ray tracing Einstein-Aether black holes: Universal versus Killing horizons
No full textViolating Lorentz invariance, and so implicitly permitting some form of super-luminal communication, necessarily alters the notion of a black hole. Nevertheless, in both Einstein-æther gravity and Hořava-Lifshitz gravity, there is still a causally disconnected region in black-hole solutions, now being bounded by a “universal horizon,” which traps excitations of arbitrarily high velocities. To better understand the nature of these black holes, and their universal horizons, we study ray trajectories in these spacetimes. We find evidence that Hawking radiation is associated with the universal horizon, while the “lingering” of ray trajectories near the Killing horizon hints at reprocessing there. In doing this we solve an apparent discrepancy between the surface gravity of the universal horizon and the associated temperature derived by the tunneling method. These results advance the understanding of these exotic horizons and provide hints for a full understanding of black-hole thermodynamics in Lorentz-violating theories
Process-dependence of biogenic feedback effects in models of plankton dynamics.
No full textThe prospect of human-induced climate change has stimulated research into several biological processes that might affect climate. One such process that has attracted a substantial research effort is the so-called CLAW hypothesis (Charlson et al. 1987). This hypothesis suggests that marine plankton ecosystems may effectively regulate climate by a feedback associated with the production of dimethylsulphide (DMS). Charlson et al. (1987) observed that some of the DMS produced by marine ecosystems is transferred from the ocean to the atmosphere where it is the major source of cloud condensing nuclei (CCN) over the remote oceans. The aerosols resulting from biogenic DMS emissions can have a direct effect on the solar radiative forcing experienced by the Earth through scattering, absorption and reflection and can also lead to increased cloud formation; the CLAW hypothesis proposes that these mechanisms could regulate climate. Charlson et al (1987) argued that an increase in global temperature would lead to increased biogenic DMS emissions from the ocean and result in an increase in scattering, cloud cover and cloud albedo that would increase the proportion of the incoming solar radiation reflected back into space (thus changing the global albedo), and thereby cooling the planet. The objective of this paper is to examine the implications of the climate regulation process proposed by Charlson et al. (1987) for the dynamics of the ecosystems that produce it. Cropp et al. (2007) developed a simple plankton model that incorporated the DMS feedback mechanism and compared its dynamics to the same ecosystem model without the feedback. These simulations revealed that the presence of the feedback generally enhanced the stability of the ecosystem by making it more resilient to perturbation. In this research, we compare the effect of the feedbacks on a similar NPZ ecosystem model that has a greater range of dynamical behaviour than the model used by Cropp et al. (2007). The results of simulations with the new feedback model are compared to the results of Cropp et al. (2007) to elucidate the influence of the model formulation on the effects of the feedback
Correction to: An eco-evolutionary system with naturally bounded traits
No full textCorrection to: Theoretical Ecology
https://doi.org/10.1007/s12080-019-0407-6
The original version of this article unfortunately contains an incorrect panel (b) in Fig. 1 introduced during the production process. The correct Fig. 1 is shown next page:
Ecospace diagrams illustrating the initial conditions (blue dots) and stable invasion outcomes (black dots) under ecological theory used for the four scenarios: a competitive exclusion—either x1 or x2 could survive depending on initial conditions, but for this initial condition x1 will survive and x2 will fail to invade; b competitive exclusion—R∗ theory predicts that x1 will win and x2 will go extinct; c competitive exclusion—R∗ theory predicts that x2 will win and x1 will go extinct; d competitive coexistence—both populations survive but x1 will dominate in non-adaptive scenarios. The lines are zero isoclines, the dots are stable (black) or unstable (white) equilibriums or initial conditions (blue). The vector field (blue arrows) show how the system changes in time. The initial population values have x1 set to its carrying capacity (i.e. x∗1=K1=r1/a11) and x∗2=0.05. Technically, R∗ is only relevant to panels b and c, but we will use the term generically to mean the outcome of non-evolutionary competition. (See Table 1 for parameter values)No Full Tex
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