5,497 research outputs found
Complex maps without invariant densities
We consider complex polynomials for and
, and find some combinatorial types and values of such that
there is no invariant probability measure equivalent to conformal measure on
the Julia set. This holds for particular Fibonacci-like and Feigenbaum
combinatorial types when sufficiently large and also for a class of
`long-branched' maps of any critical order.Comment: Typos corrected, minor changes, principally to Section
Volatile aldehydes in libraries and archives
Volatile aldehydes are produced during degradation of paper-based materials. This may result in their accumulation in archival and library repositories. However, no systematic study has been performed so far. In the frame of this study, passive sampling was carried out at ten locations in four libraries and archives. Despite the very variable sampling locations, no major differences were found, although air-filtered repositories were found to have lower concentrations while a non-ventilated newspaper repository exhibited the highest concentrations of volatile aldehydes (formaldehyde, acetaldehyde, furfural and hexanal). Five employees in one institution were also provided with personal passive samplers to investigate employeesâ exposure to volatile aldehydes. All values were lower than the presently valid exposure limits.
The concentration of volatile aldehydes, acetic acid, and volatile organic compounds (VOCs) in general was also compared with that of outdoor-generated pollutants. It was evident that inside the repository and particularly inside archival boxes, the concentration of VOCs and acetic acid was much higher than the concentration of outdoor-generated pollutants, which are otherwise more routinely studied in connection with heritage materials. This indicates that further work on the pro-degradative effect of VOCs on heritage materials is necessary and that monitoring of VOCs in heritage institutions should become more widespread
The multipliers of periodic points in one-dimensional dynamics
It will be shown that the smooth conjugacy class of an unimodal map which
does not have a periodic attractor neither a Cantor attractor is determined by
the multipliers of the periodic orbits. This generalizes a result by M.Shub and
D.Sullivan for smooth expanding maps of the circle
Creating space for biodiversity by planning swath patterns and field marging using accurate geometry
Potential benefits of field margins or boundary strips include promotion of biodiversity and farm wildlife, maintaining landscape diversity, exploiting pest predators and parasites and enhancing crop pollinator populations. In this paper we propose and demonstrate a method to relocate areas of sub-efficient machine manoeuvring to boundary strips so as to optimise the use of available space. Accordingly, the boundary strips will have variable rather than fixed widths. The method is being tested in co-operation with seven farmers in the Hoeksche Waard within the province of Zuid Holland, The Netherlands. In a preliminary stage of the project, tests were performed to determine the required accuracy of field geometry. The results confirmed that additional data acquisition using accurate measuring devices is required. In response, a local contracting firm equipped a small all-terrain vehicle (quad) with an RTK-GPS receiver and set up a service for field measurement. Protocols were developed for requesting a field measurement and for the measurement procedure itself. Co-ordinate transformation to a metric system and brute force optimization of swath patterns are achieved using an open source geospatial library (osgeo.ogr) and Python scripting. The optimizer basically tests all orientations and relevant intermediate angles of input field boundaries and tries incremental positional shifts until the most efficient swath pattern is found. Inefficient swaths intersecting boundary areas are deleted to create space for field margins. The optimised pattern can be forwarded to an agricultural navigation system. At the time of the conference, the approach will have been tested on several farm fields
A structured design technique for distributed programs
This report contains a non-formal motivation and description of ADL-d, a graphical design technique for parallel and distributed software. ADL-d allows a developer to construct an application in terms of communicating processes. The technique distinguishes itself from others by its use of highly orthogonal concepts, and support for automated code generation. Without being committed to one particular design method, ADL-d as a technique can be used from the early phases of application design through phases that concentrate on algorithmic design, and final implementation on some target platform. In this report, we discuss and motivate all ADL-d components, including recently incorporated features such as support for connection-oriented communication, support for modeling dynamically changing communication structures, and a formal semantical basis for each ADL-d component. Also, we discuss our ADL-d implementation, and place ADL-d in context by discussing some related work
Performance of HIRLAM in a semiarid heterogeneous region: evaluation of the land surface and boundary layer description using EFEDA observations
Observations from the European Field Experiment in a Desertification-threatened Area (EFEDA) are used to evaluate the performance of the radiation, land surface, and boundary layer description of the numerical weather prediction (NWP) system High-Resolution Limited Area Model (HIRLAM) in semiarid conditions. Model analysis and 6-h forecast data of the fully coupled three-dimensional model are compared with the comprehensive dataset of a case study representing a sample of 22 days of anticyclonic conditions. Distributed micrometeorological surface stations, radiosondes, flux aircraft, and airborne lidar provide a unique validation dataset of the diurnal cycle of surface and boundary layer processes. The model surface, soil, and boundary layer are found to be too moist and slightly too cold during most of the diurnal cycle. The model radiation and surface energy budgets are biased toward more humid conditions. Model shortcomings are identified essentially in four areas. These are the moisture data assimilation, the land-use and soil classification with its associated physiographic database, the aerosol parameterization in the radiation code, and the boundary layer vertical resolution and entrainment description. Practical steps for immediate improvement of the model performance are proposed. They focus on the use of a land-use and soil classification and physiographic database adapted to Mediterranean landscapes, in combination with the inclusion of aerosol parameters in the radiation scheme, that account for the typically higher aerosol load of arid and semiarid environments.The EFEDA 1991 field phase was cofunded by the European Commission under its Environment Program (Grant EV5VCT93-
0271)
Is bilingualism associated with enhanced executive functioning in adults? A meta-analytic review.
This article was published Online First March 1, 2018.
Supplemental materials: http://dx.doi.org/10.1037/bul0000142.suppBecause of enduring experience of managing two languages, bilinguals have been argued to develop superior executive functioning compared with monolinguals. Despite extensive investigation, there is, however, no consensus regarding the existence of such a bilingual advantage. Here we synthesized comparisons of bilingualsâ and monolingualsâ performance in six executive domains using 891 effect sizes from 152 studies on adults. We also included unpublished data, and considered the potential influence of a number of study-, task-, and participant-related variables. Before correcting estimates for observed publication bias, our analyses revealed a very small bilingual advantage for inhibition, shifting, and working memory, but not for monitoring or attention. No evidence for a bilingual advantage remained after correcting for bias. For verbal fluency, our analyses indicated a small bilingual disadvantage, possibly reflecting less exposure for each individual language when using two languages in a balanced manner. Moreover, moderator analyses did not support theoretical presuppositions concerning the bilingual advantage. We conclude that the available evidence does not provide systematic support for the widely held notion that bilingualism is associated with benefits in cognitive control functions in adults.The study was financially supported by Academy of Finland (grant 288880),
Emil Aaltonen Foundation project grant, and University of Helsinki 3-year grants
to Minna Lehtonen. We thank Benny Salo for statistical consultation, and Matti
Laine, Jussi JylkkÀ, and the rest of the BrainTrain research group for valuable
discussions
Oncogenic RAS sensitizes cells to drug-induced replication stress via transcriptional silencing of P53
Cancer cells often experience high basal levels of DNA replication stress (RS), for example due to hyperactivation of oncoproteins like MYC or RAS. Therefore, cancer cells are considered to be sensitive to drugs that exacerbate the level of RS or block the intra S-phase checkpoint. Consequently, RS-inducing drugs including ATR and CHK1 inhibitors are used or evaluated as anti-cancer therapies. However, drug resistance and lack of biomarkers predicting therapeutic efficacy limit efficient use. This raises the question what determines sensitivity of individual cancer cells to RS. Here, we report that oncogenic RAS does not only enhance the sensitivity to ATR/CHK1 inhibitors by directly causing RS. Instead, we observed that HRAS(G12V) dampens the activation of the P53-dependent transcriptional response to drug-induced RS, which in turn confers sensitivity to RS. We demonstrate that inducible expression of HRAS(G12V) sensitized cells to ATR and CHK1 inhibitors. Using RNA-sequencing of FACS-sorted cells we discovered that P53 signaling is the sole transcriptional response to RS. However, oncogenic RAS attenuates the transcription of P53 and TGF-beta pathway components which consequently dampens P53 target gene expression. Accordingly, live cell imaging showed that HRAS(G12V) exacerbates RS in S/G2-phase, which could be rescued by stabilization of P53. Thus, our results demonstrate that transcriptional control of P53 target genes is the prime determinant in the response to ATR/CHK1 inhibitors and show that hyperactivation of the MAPK pathway impedes this response. Our findings suggest that the level of oncogenic MAPK signaling could predict sensitivity to intra-S-phase checkpoint inhibition in cancers with intact P53
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