2,855 research outputs found
Nut & Natuur Overijssel: Meerwaarde, benutting en borging van groene grondstoffen uit natuurgebieden in Overijssel; praktische bijdragen aan een bio-based economy vanuit landbouw en natuurbeheer
In het project “Nut en Natuur Overijssel” zijn in opdracht van de provincie Overijssel innovatieve samenwerkingsverbanden opgezet tussen natuurbeherende organisaties en boeren om de groene grondstoffen uit natuurgebieden te waarborgen. In drie samenwerkingsverbanden is gezocht naar nieuwe vormen van natuurbeheer door boeren, zoals aangepaste voerwinning van schrale natuurgraslanden en -akkers en de verwerking van reststromen uit bijvoorbeeld rietlanden en heide
Generalized gaugings and the field-antifield formalism
We discuss the algebra of general gauge theories that are described by the
embedding tensor formalism. We compare the gauge transformations dependent and
independent of an invariant action, and argue that the generic transformations
lead to an infinitely reducible algebra. We connect the embedding tensor
formalism to the field-antifield (or Batalin-Vilkovisky) formalism, which is
the most general formulation known for general gauge theories and their
quantization. The structure equations of the embedding tensor formalism are
included in the master equation of the field-antifield formalism.Comment: 42 pages; v2: some clarifications and 1 reference added; version to
be published in JHE
The Auxological and Biochemical Continuum of Short Children Born Small for Gestational Age (SGA) or with Normal Birth Size (Idiopathic Short Stature)
Objective. Retrospective single-centre analysis of growth characteristics in 182 healthy short children born small for gestational age (SGA) or appropriate for gestational age (idiopathic short stature, ISS). Methods. Birth size references from the USA and Sweden were compared, and for the classification as SGA or ISS the Swedish reference was chosen. Height, target height (TH), bone age (BA), predicted adult height (PAH), IGF-I and IGFBP-3 values were compared between SGA and ISS. Results. In the combined group, birth weight and length showed a symmetric Gaussian distribution. The American reference overestimates the percentage of short birth length and underestimates that of low birth weight. In childhood, SGA children were shorter than ISS (−3.1 versus −2.6 SDS, P < .001), also in comparison to TH (−2.6 versus −1.9 SDS, P < .001). TH, height SDS change over time, BA delay, and PAH were similar. IGF-I and IGFBP-3 were lower in ISS (P = .03 and .09). Conclusions. SGA children represent the left tail of the Gaussian distribution of birth size in short children. The distinction between SGA and ISS depends on birth size reference. Childhood height of SGA is lower than of ISS, but the other auxological features are similar
The LBV HR Car has a partner: Discovery of a companion with the VLTI
Luminous Blue Variables (LBVs) are massive stars caught in a post-main
sequence phase, during which they are losing a significant amount of mass. As,
on one hand, it is thought that the majority of massive stars are close
binaries that will interact during their lifetime, and on the other, the most
dramatic example of an LBV, Eta Car, is a binary, it would be useful to find
other binary LBVs. We present here interferometric observations of the LBV HR
Car done with the AMBER and PIONIER instruments attached to ESO's Very Large
Telescope Interferometer (VLTI). Our observations, spanning two years, clearly
reveal that HR Car is a binary star. It is not yet possible to constrain fully
the orbit, and the orbital period may lie between a few years and several
hundred years. We derive a radius for the primary in the system and possibly
resolve as well the companion. The luminosity ratio in the H-band between the
two components is changing with time, going from about 6 to 9. We also
tentatively detect the presence of some background flux which remained at the
2% level until January 2016, but then increased to 6% in April 2016. Our AMBER
results show that the emission line forming region of Br gamma is more extended
than the continuum emitting region as seen by PIONIER and may indicate some
wind-wind interaction. Most importantly, we constrain the total masses of both
components, with the most likely range being 33.6 and 45 solar masses. Our
results show that the LBV HR Car is possibly an Eta Car analog binary system
with smaller masses, with variable components, and further monitoring of this
object is definitively called for.Comment: A&A, in pres
A link between the accumulation of DNA damage and loss of multi-potency of human mesenchymal stromal cells
Human mesenchymal stromal cells (hMSCs) represent an attractive cell source for clinic applications. Besides being multi-potent, recent clinical trials suggest that they secrete both trophic and immunomodulatory factors, allowing allogenic MSCs to be used in a wider variety of clinical situations. The yield of prospective isolation is however very low, making expansion a required step toward clinical applications. Unfortunately, this leads to a significant decrease in their stemness. To identify the mechanism behind loss of multi-potency, hMSCs were expanded until replicative senescence and the concomitant molecular changes were characterized at regular intervals. We observed that, with time of culture, loss of multi-potency was associated with both the accumulation of DNA damage and the respective activation of the DNA damage response pathway, suggesting a correlation between both phenomena. Indeed, exposing hMSCs to DNA damage agents led to a significant decrease in the differentiation potential. We also showed that hMSCs are susceptible to accumulate DNA damage upon in vitro expansion, and that although hMSCs maintained an effective nucleotide excision repair activity, there was a progressive accumulation of DNA damage. We propose a model in which DNA damage accumulation contributes to the loss of differentiation potential of hMSCs, which might not only compromise their potential for clinical applications but also contribute to the characteristics of tissue agein
Electric/magnetic duality for chiral gauge theories with anomaly cancellation
We show that 4D gauge theories with Green-Schwarz anomaly cancellation and
possible generalized Chern-Simons terms admit a formulation that is manifestly
covariant with respect to electric/magnetic duality transformations. This
generalizes previous work on the symplectically covariant formulation of
anomaly-free gauge theories as they typically occur in extended supergravity,
and now also includes general theories with (pseudo-)anomalous gauge
interactions as they may occur in global or local N=1 supersymmetry. This
generalization is achieved by relaxing the linear constraint on the embedding
tensor so as to allow for a symmetric 3-tensor related to electric and/or
magnetic quantum anomalies in these theories. Apart from electric and magnetic
gauge fields, the resulting Lagrangians also feature two-form fields and can
accommodate various unusual duality frames as they often appear, e.g., in
string compactifications with background fluxes.Comment: 37 pages; v2: typos corrected and 1 reference adde
The Matrix Theory S-Matrix
The technology required for eikonal scattering amplitude calculations in
Matrix theory is developed. Using the entire supersymmetric completion of the
v^4/r^7 Matrix theory potential we compute the graviton-graviton scattering
amplitude and find agreement with eleven dimensional supergravity at tree
level.Comment: 10 pages, RevTeX, no figure
Symplectic structure of N=1 supergravity with anomalies and Chern-Simons terms
The general actions of matter-coupled N=1 supergravity have Peccei-Quinn
terms that may violate gauge and supersymmetry invariance. In addition, N=1
supergravity with vector multiplets may also contain generalized Chern-Simons
terms. These have often been neglected in the literature despite their
importance for gauge and supersymmetry invariance. We clarify the interplay of
Peccei-Quinn terms, generalized Chern-Simons terms and quantum anomalies in the
context of N=1 supergravity and exhibit conditions that have to be satisfied
for their mutual consistency. This extension of the previously known N=1
matter-coupled supergravity actions follows naturally from the embedding of the
gauge group into the group of symplectic duality transformations. Our results
regarding this extension provide the supersymmetric framework for studies of
string compactifications with axionic shift symmetries, generalized
Chern-Simons terms and quantum anomalies.Comment: 27 pages; v2: typos corrected; version to be published in
Class.Quantum Gra
Співставлення чіткого та нечіткого підходів до розв’язку задач інформаційної безпеки
Проведено порівняння чіткого та нечіткого підходів із метою виявлення їх спільних рис та відмінностей. У задачі розподілу ресурсів захисту інформації проаналізовано принципи формування функцій належності до нечітких множин і їх вплив на кінцеві результати. Показано, що нечіткий підхід дає змогу оптимізувати показники системи захисту інформації за рахунок раціонального вибору функцій належності, які відображають основну характеристику об’єктів — їх динамічну вразливість. На прикладі системи з двох об’єктів із різними вразливостями встановлені умови, за яких досягається найвищий рівень співпадіння результатів у разі використання двох підходів. Методика може бути використана під час розрахунку допустимих витрат в інформаційних системах із довільною кількістю об’єктів, котрі відрізняються кількістю розміщеної інформації, вразливістю та рівнем допустимих втрат. Окреслені шляхи подальшого застосування приведеної методики в задачах інформаційної безпеки.Проведено сравнение четкого и нечеткого подходов с целью выявления их общих черт и различий. В задаче распределения ресурсов защиты информации проанализированы принципы формирования функций принадлежности к нечетким множествам и их влияние на конечные результаты. Показано, что нечеткий подход дает возможность оптимизировать показатели системы защиты информации за счет рационального выбора функций принадлежности, которые отражают основную характеристику объектов — их динамическую уязвимость. На примере системы из двух объектов с различными уязвимостями установлены условия, при которых достигается наивысший уровень совпадения результатов при использовании двух подходов. Методика может быть использована при расчете допустимых затрат в информационных системах с произвольным количеством объектов, которые отличаются объемом размещенной информации, уязвимостью и уровнем допустимых потерь. Обозначены пути дальнейшего применения приведенной методики в задачах информационной безопасности.A comparison of explicit and fuzzy approaches to identify their similarities and differences is carried out. In the problem of distribution of resources of information protection the principles of the formation of the membership functions to the fuzzy sets and their effect on the final results are analyzed. It is shown that the fuzzy approach gives the possibility to optimize the indicators of the system of information security through a rational choice of the membership functions, which reflect the basic characteristic of the objects - their dynamic vulnerability. Through the example of the system of two objects with different vulnerabilities the conditions under which the highest level of results coincidence is achieved using two approaches are established. The technique can be used when calculating the eligible costs of information systems with an arbitrary number of objects that have different volume of the placed information, vulnerability and level of acceptable losses. The ways of further application of the method in problems of information security are identified
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