95 research outputs found
Arithmetic Spacetime Geometry from String Theory
An arithmetic framework to string compactification is described. The approach
is exemplified by formulating a strategy that allows to construct geometric
compactifications from exactly solvable theories at . It is shown that the
conformal field theoretic characters can be derived from the geometry of
spacetime, and that the geometry is uniquely determined by the two-dimensional
field theory on the world sheet. The modular forms that appear in these
constructions admit complex multiplication, and allow an interpretation as
generalized McKay-Thompson series associated to the Mathieu and Conway groups.
This leads to a string motivated notion of arithmetic moonshine.Comment: 36 page
Wave Number of Maximal Growth in Viscous Magnetic Fluids of Arbitrary Depth
An analytical method within the frame of linear stability theory is presented
for the normal field instability in magnetic fluids. It allows to calculate the
maximal growth rate and the corresponding wave number for any combination of
thickness and viscosity of the fluid. Applying this method to magnetic fluids
of finite depth, these results are quantitatively compared to the wave number
of the transient pattern observed experimentally after a jump--like increase of
the field. The wave number grows linearly with increasing induction where the
theoretical and the experimental data agree well. Thereby a long-standing
controversy about the behaviour of the wave number above the critical magnetic
field is tackled.Comment: 19 pages, 15 figures, RevTex; revised version with a new figure and
references added. submitted to Phys Rev
Tate Form and Weak Coupling Limits in F-theory
We consider the weak coupling limit of F-theory in the presence of
non-Abelian gauge groups implemented using the traditional ansatz coming from
Tate's algorithm. We classify the types of singularities that could appear in
the weak coupling limit and explain their resolution. In particular, the weak
coupling limit of SU(n) gauge groups leads to an orientifold theory which
suffers from conifold singulaties that do not admit a crepant resolution
compatible with the orientifold involution. We present a simple resolution to
this problem by introducing a new weak coupling regime that admits
singularities compatible with both a crepant resolution and an orientifold
symmetry. We also comment on possible applications of the new limit to model
building. We finally discuss other unexpected phenomena as for example the
existence of several non-equivalent directions to flow from strong to weak
coupling leading to different gauge groups.Comment: 34 page
A Digital Repository and Execution Platform for Interactive Scholarly Publications in Neuroscience
The CARMEN Virtual Laboratory (VL) is a cloud-based platform which allows neuroscientists to store, share, develop, execute, reproduce and publicise their work. This paper describes new functionality in the CARMEN VL: an interactive publications repository. This new facility allows users to link data and software to publications. This enables other users to examine data and software associated with the publication and execute the associated software within the VL using the same data as the authors used in the publication. The cloud-based architecture and SaaS (Software as a Service) framework allows vast data sets to be uploaded and analysed using software services. Thus, this new interactive publications facility allows others to build on research results through reuse. This aligns with recent developments by funding agencies, institutions, and publishers with a move to open access research. Open access provides reproducibility and verification of research resources and results. Publications and their associated data and software will be assured of long-term preservation and curation in the repository. Further, analysing research data and the evaluations described in publications frequently requires a number of execution stages many of which are iterative. The VL provides a scientific workflow environment to combine software services into a processing tree. These workflows can also be associated with publications and executed by users. The VL also provides a secure environment where users can decide the access rights for each resource to ensure copyright and privacy restrictions are met
Politicising government engagement with corporate social responsibility: âCSRâ as an empty signifier
Governments are widely viewed by academics and practitioners (and society more generally) as the key societal actors who are capable of compelling businesses to practice corporate social responsibility (CSR). Arguably, such government involvement could be seen as a technocratic device for encouraging ethical business behaviour. In this paper, we offer a more politicised interpretation of government engagement with CSR where âCSRâ is not a desired form of business conduct but an element of discourse that governments can deploy in structuring their relationships with other social actors. We build our argument through a historical analysis of government CSR discourse in the Russian Federation. Laclau and Mouffe's (Hegemony and socialist strategy: Towards a radical democratic politics,Verso Books, London, 1985) social theory of hegemony underpins our research. We find that âCSRâ in the Russian governmentâs discourse served to legitimise its power over large businesses. Using this case, we contribute to wider academic debates by providing fresh empirical evidence that allows the development of critical evaluation tools in relation to governmentsâ engagement with âCSRâ. We find that governments are capable of hijacking CSR for their own self-interested gain. We close the paper by reflecting on the merit of exploring the case of the Russian Federation. As a ânon-coreâ, non-western exemplar, it provides a useful âmirrorâ with which to reflect on the more widely used test-bed of Western industrial democracies when scrutinising CSR. Based on our findings, we invite other scholars to adopt a more critical, politicised stance when researching the role of governments in relation to CSR in other parts of the world
Justice and Corporate Governance: New Insights from Rawlsian Social Contract and Senâs Capabilities Approach
By considering what we identify as a problem inherent in the ânature of the firmââthe risk of abuse of authorityâwe propound the conception of a social contract theory of the firm which is truly Rawlsian in its inspiration. Hence, we link the social contract theory of the firm (justice at firmâs level) with the general theory of justice (justice at societyâs level). Through this path, we enter the debate about whether firms can be part of Rawlsian theory of justice showing that corporate governance principles enter the âbasic structure.â Finally, we concur with Senâs aim to broaden the realm of social justice beyond what he calls the âtranscendental institutional perfectionismâ of Rawlsâ theory. We maintain the contractarian approach to justice but introduce Senâs capability concept as an element of the constitutional and post-constitutional contract model of institutions with special reference to corporate governance. Accordingly, rights over primary goods and capabilities are (constitutionally) granted by the basic institutions of society, but many capabilities have to be turned into the functionings of many stakeholders through the operation of firms understood as post-constitutional institutional domains. The constitutional contract on the distribution of primary goods and capabilities should then shape the principles of corporate governance so that at post-constitutional level anyone may achieve her/his functionings in the corporate domain by exercising such capabilities. In the absence of such a condition, post-constitutional contracts would distort the process that descends from constitutional rights and capabilities toward social outcomes
Synthesising Corporate Responsibility on Organisational and Societal Levels of Analysis: An Integrative Perspective
This article develops an integrative perspective on corporate responsibility by synthesising competing perspectives on the responsibility of the corporation at the organisational and societal levels of analysis. We review three major corporate responsibility perspectives, which we refer to as economic, critical, and politico-ethical. We analyse the major potential uses and pitfalls of the perspectives, and integrate the debate on these two levels. Our synthesis concludes that when a society has a robust division of moral labour in place, the responsibility of a corporation may be economic (as suggested under the economic perspective) without jeopardising democracy and sustainability (as reported under the critical perspective). Moreover, the economic role of corporations neither signifies the absence of deliberative democratic mechanisms nor business practices extending beyond compliance (as called for under the politico-ethical perspective). The study underscores the value of integrating different perspectives and multiple levels of analysis to present comprehensive descriptions and prescriptions of the responsibility phenomenon
GJ 273: On the formation, dynamical evolution, and habitability of a planetary system hosted by an M dwarf at 3.75 parsec
Context. Planets orbiting low-mass stars such as M dwarfs are now considered a cornerstone in the search for life-harbouring planets.
GJ 273 is a planetary system orbiting an M dwarf only 3.75 pc away, composed of two confirmed planets, GJ 273b and GJ 273c, and
two promising candidates, GJ 273d and GJ 273e. Planet GJ 273b resides in the habitable zone. Currently, due to a lack of observed
planetary transits, only the minimum masses of the planets are known: Mb sin ib=2.89 Mâ, Mc sin ic=1.18 Mâ, Md sin id=10.80 Mâ,
and Me sin ie=9.30 Mâ. Despite being an interesting system, the GJ 273 planetary system is still poorly studied.
Aims. We aim at precisely determine the physical parameters of the individual planets, in particular to break the massâinclination
degeneracy to accurately determine the mass of the planets. Moreover, we present thorough characterisation of planet GJ 273b in
terms of its potential habitability.
Methods. First, we explored the planetary formation and hydration phases of GJ 273 during the first 100 Myr. Secondly, we analysed
the stability of the system by considering both the two- and four-planet configurations. We then performed a comparative analysis
between GJ 273 and the Solar System, and searched for regions in GJ 273 which may harbour minor bodies in stable orbits, i.e. main
asteroid belt and Kuiper belt analogues.
Results. From our set of dynamical studies, we obtain that the four-planet configuration of the system allows us to break the massâ
inclination degeneracy. From our modelling results, the masses of the planets are unveiled as: 2:89 †Mb †3:03 Mâ, 1:18 †Mc â€
1:24 Mâ, 10:80 †Md †11:35 Mâ and 9:30 †Me †9:70 Mâ. These results point to a system likely composed of an Earth-mass
planet, a super-Earth and two mini-Neptunes. From planetary formation models, we determine that GJ 273b was likely an efficient
water captor while GJ 273c is probably a dry planet. We found that the system may have several stable regions where minor bodies
might reside. Collectively, these results are used to comprehensively discuss the habitability of GJ 273bSpanish Ministry of Science and Education RamĂłn y Cajal programme
ESP2017-87676-2-2
RYC-2012-09913CONICYT- FONDECYT/Chile Postdoctorado 3180405MITâs Kavli Institut
Quantifying the Influence of Jupiter on the Earth's Orbital Cycles
A wealth of Earth-sized exoplanets will be discovered in the coming years,
proving a large pool of candidates from which the targets for the search for
life beyond the Solar system will be chosen. The target selection process will
require the leveraging of all available information in order to maximise the
robustness of the target list and make the most productive use of follow-up
resources. Here, we present the results of a suite of -body simulations that
demonstrate the degree to which the orbital architecture of the Solar system
impacts the variability of Earth's orbital elements. By varying the orbit of
Jupiter and keeping the initial orbits of the other planets constant, we
demonstrate how subtle changes in Solar system architecture could alter the
Earth's orbital evolution -- a key factor in the Milankovitch cycles that alter
the amount and distribution of solar insolation, thereby driving periodic
climate change on our planet. The amplitudes and frequencies of Earth's modern
orbital cycles fall in the middle of the range seen in our runs for all
parameters considered -- neither unusually fast nor slow, nor large nor small.
This finding runs counter to the `Rare Earth' hypothesis, which suggests that
conditions on Earth are so unusual that life elsewhere is essentially
impossible. Our results highlight how dynamical simulations of newly discovered
exoplanetary systems could be used as an additional means to assess the
potential targets of biosignature searches, and thereby help focus the search
for life to the most promising targets.Comment: 19 pages; 11 figures; accepted for publication in the Astronomical
Journal Version 2 - incorporates typo corrections and minor changes noted at
the proofing stage, after acceptanc
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