1,098 research outputs found
Transnational reflections on transnational research projects on men, boys and gender relations
This article reflects on the research project, ‘Engaging South African and Finnish youth towards new traditions of non-violence, equality and social well-being’, funded by the Finnish and South African national research councils, in the context of wider debates on research, projects and transnational processes. The project is located within a broader analysis of research projects and projectization (the reduction of research to separate projects), and the increasing tendencies for research to be framed within and as projects, with their own specific temporal and organizational characteristics. This approach is developed further in terms of different understandings of research across borders: international, comparative, multinational and transnational. Special attention is given to differences between research projects that are in the Europe and the EU, and projects that are between the global North and the global South. The theoretical, political and practical challenges of the North-South research project are discussed
Progressive Star Bursts and High Velocities in the Infrared Luminous, Colliding Galaxy Arp 118
In this paper we demonstrate for the first time the connection between the
spatial and temporal progression of star formation and the changing locations
of the very dense regions in the gas of a massive disk galaxy (NGC 1144) in the
aftermath of its collision with a massive elliptical (NGC 1143). These two
galaxies form the combined object Arp 118, a collisional ring galaxy system.
The results of 3D, time-dependent, numerical simulations of the behavior of the
gas, stars, and dark matter of a disk galaxy and the stars and dark matter in
an elliptical during a collision are compared with multiwavelength observations
of Arp 118. The collision that took place approximately 22 Myr ago generated a
strong, non-linear density wave in the stars and gas in the disk of NGC 1144,
causing the gas to became clumped on a large scale. This wave produced a series
of superstarclusters along arcs and rings that emanate from the central point
of impact in the disk. The locations of these star forming regions match those
of the regions of increased gas density predicted the time sequence of models.
The models also predict the large velocity gradients observed across the disk
of NGC 1144. These are due to the rapid radial outflow of gas coupled to large
azimuthal velocities in the expanding ring, caused by the impact of the massive
intruder.Comment: 12 pages in document, and 8 figures (figures are separate from the
document's file); Submitted to Astrophysical Journal Letter
Founder retention as CEO at IPO in emerging economies: The role of private equity owners and national institutions
YesWe integrate the institutional perspective with research on the governance role of private equity firms in an investigation of Founder-CEO successions in Initial Public Offerings (IPOs) in emerging markets. Using a unique, hand-collected and comprehensive sample of 191 firms having undertaken IPOs in 21 markets across the African continent between January 2000 and August 2016, we apply instrumental variable (IV) Probit methodology and find that higher levels of private equity ownership are positively associated with the probability of the founder's retention as CEO, especially in the context of low-quality formal institutions. Further, in societies with high tribalism, higher private equity ownership is associated with an increased likelihood of founder retention. Voids in the institutional architecture underscore the importance of the founder as a key organizational resource for the firm and a source of institutionalized legitimacy, which in turn confers on the firm an ability to access required resources
Identification of transcription-factor genes expressed in the Arabidopsis female gametophyte
Dongfang Wang, Changqing Zhang, David J. Hearn, Il-HO Kang, megan I. Skaggs, Karen S. Schumaker, and Ramin Yadegari are with the School of Plant Sciences, University of Arizona, Tucson, Arizona 85721-0036, USA -- Il-Ho Kang, Jayson A. Punwani, and Gary N. Drews are with the Department of Biology, University of Utah, Salt Lake City, Utah 84112-0840, USA -- Changqing Zhang is with The Section of Molecular, Cell and Developmental Biology, University of Texas at Austin, Austin, Texas 78712-0159, USA -- David J. Hearn is with the Department of Biological Sciences, Towson University, Towson, Maryland 21252-0001, USA -- Il-Ho Kang is with the Department of Horticulture, Iowa State University, Ames, Iowa 50011-1100, USA --Jayson A. Punwani is with the Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3280, USABackground
In flowering plants, the female gametophyte is typically a seven-celled structure with four cell types: the egg cell, the central cell, the synergid cells, and the antipodal cells. These cells perform essential functions required for double fertilization and early seed development. Differentiation of these distinct cell types likely involves coordinated changes in gene expression regulated by transcription factors. Therefore, understanding female gametophyte cell differentiation and function will require dissection of the gene regulatory networks operating in each of the cell types. These efforts have been hampered because few transcription factor genes expressed in the female gametophyte have been identified. To identify such genes, we undertook a large-scale differential expression screen followed by promoter-fusion analysis to detect transcription-factor genes transcribed in the Arabidopsis female gametophyte.
Results
Using quantitative reverse-transcriptase PCR, we analyzed 1,482 Arabidopsis transcription-factor genes and identified 26 genes exhibiting reduced mRNA levels in determinate infertile 1 mutant ovaries, which lack female gametophytes, relative to ovaries containing female gametophytes. Spatial patterns of gene transcription within the mature female gametophyte were identified for 17 transcription-factor genes using promoter-fusion analysis. Of these, ten genes were predominantly expressed in a single cell type of the female gametophyte including the egg cell, central cell and the antipodal cells whereas the remaining seven genes were expressed in two or more cell types. After fertilization, 12 genes were transcriptionally active in the developing embryo and/or endosperm.
Conclusions
We have shown that our quantitative reverse-transcriptase PCR differential-expression screen is sufficiently sensitive to detect transcription-factor genes transcribed in the female gametophyte. Most of the genes identified in this study have not been reported previously as being expressed in the female gametophyte. Therefore, they might represent novel regulators and provide entry points for reverse genetic and molecular approaches to uncover the gene regulatory networks underlying female gametophyte development.Cellular and Molecular [email protected]
New Complexity Results and Algorithms for the Minimum Tollbooth Problem
The inefficiency of the Wardrop equilibrium of nonatomic routing games can be
eliminated by placing tolls on the edges of a network so that the socially
optimal flow is induced as an equilibrium flow. A solution where the minimum
number of edges are tolled may be preferable over others due to its ease of
implementation in real networks. In this paper we consider the minimum
tollbooth (MINTB) problem, which seeks social optimum inducing tolls with
minimum support. We prove for single commodity networks with linear latencies
that the problem is NP-hard to approximate within a factor of through
a reduction from the minimum vertex cover problem. Insights from network design
motivate us to formulate a new variation of the problem where, in addition to
placing tolls, it is allowed to remove unused edges by the social optimum. We
prove that this new problem remains NP-hard even for single commodity networks
with linear latencies, using a reduction from the partition problem. On the
positive side, we give the first exact polynomial solution to the MINTB problem
in an important class of graphs---series-parallel graphs. Our algorithm solves
MINTB by first tabulating the candidate solutions for subgraphs of the
series-parallel network and then combining them optimally
One-loop counterterms for the dimensional regularization of arbitrary Lagrangians
We present master formulas for the divergent part of the one-loop effective
action for an arbitrary (both minimal and nonminimal) operators of any order in
the 4-dimensional curved space. They can be considered as computer algorithms,
because the one-loop calculations are then reduced to the simplest algebraic
operations. Some test applications are considered by REDUCE analytical
calculation system.Comment: 39 pages, Latex, 3 PS figures, replaced with published versio
Low-Energy Compton Scattering of Polarized Photons on Polarized Nucleons
The general structure of the cross section of scattering with
polarized photon and/or nucleon in initial and/or final state is systematically
described and exposed through invariant amplitudes. A low-energy expansion of
the cross section up to and including terms of order is given which
involves ten structure parameters of the nucleon (dipole, quadrupole,
dispersion, and spin polarizabilities). Their physical meaning is discussed in
detail. Using fixed-t dispersion relations, predictions for these parameters
are obtained and compared with results of chiral perturbation theory. It is
emphasized that Compton scattering experiments at large angles can fix the most
uncertain of these structure parameters. Predictions for the cross section and
double-polarization asymmetries are given and the convergence of the expansion
is investigated. The feasibility of the experimental determination of some of
the struture parameters is discussed.Comment: 41 pages of text, 9 figures; minor revisions prior to publication in
Phys. Rev.
Classification of bicovariant differential calculi on the Jordanian quantum groups GL_{g,h}(2) and SL_{h}(2) and quantum Lie algebras
We classify all 4-dimensional first order bicovariant calculi on the
Jordanian quantum group GL_{h,g}(2) and all 3-dimensional first order
bicovariant calculi on the Jordanian quantum group SL_{h}(2). In both cases we
assume that the bicovariant bimodules are generated as left modules by the
differentials of the quantum group generators. It is found that there are 3
1-parameter families of 4-dimensional bicovariant first order calculi on
GL_{h,g}(2) and that there is a single, unique, 3-dimensional bicovariant
calculus on SL_{h}(2). This 3-dimensional calculus may be obtained through a
classical-like reduction from any one of the three families of 4-dimensional
calculi on GL_{h,g}(2). Details of the higher order calculi and also the
quantum Lie algebras are presented for all calculi. The quantum Lie algebra
obtained from the bicovariant calculus on SL_{h}(2) is shown to be isomorphic
to the quantum Lie algebra we obtain as an ad-submodule within the Jordanian
universal enveloping algebra U_{h}(sl(2)) and also through a consideration of
the decomposition of the tensor product of two copies of the deformed adjoint
module. We also obtain the quantum Killing form for this quantum Lie algebra.Comment: 33 pages, AMSLaTeX, misleading remark remove
Sum rule for the backward spin polarizability of the nucleon from a backward dispersion relation
A new sum rule for , the backward spin polarizability of the
nucleon, is derived from a backward-angle dispersion relation. Taking into
account single- and multi-pion photoproduction in the s-channel up to the
energy 1.5 GeV and resonances in the t-channel with mass below 1.5 GeV, it is
found for the proton and neutron that = -39.5 +/- 2.4 and
= 52.5 +/- 2.4, respectively, in units of 10^{-4} fm^4.Comment: 10 pages, 1 figure, revtex. Submitted to Phys. Lett.
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