406 research outputs found
Ixodes ricinus L.: mast cells, basophils and eosinophils in the sequence of cellular events in the skin of infested or re-infested rabbits
Some information on acquired resistance of rabbits against Ixodes ricinus ticks has been obtained by comparing tissue changes and cellular infiltration during 2 successive infestations, with particular emphasis on the cells involved in immediate type hypersensitivity reactions: mast cells, basophils and eosinophils. More degranulated mast cells were observed in tick lesions 2 h after the beginning of re-infestation than in the first infestation and more degranulated basophils were present on the 5th day of re-infestation. Numerous eosinophils infiltrated the dermis, especially on the 5th day of the second infestatio
Glassy freezing of orbital dynamics in FeCr2S4 and FeSc2S4
We report on a thorough dielectric investigation of the glass-like freezing
of the orbital reorientation-dynamics, recently found for the crystalline
sulpho-spinels FeCr2S4 and FeSc2S4. As the orbital reorientations are coupled
to a rearrangement of the surrounding ionic lattice via the Jahn-Teller effect,
the freezing of the orbital moments is revealed by a relaxational behaviour of
the complex dielectric permittivity. Additional conductivity (both dc and ac)
and contact contributions showing up in the spectra are taken into account by
an equivalent circuit description. The orbital relaxation dynamics continuously
slows down over six decades in time, before at the lowest temperatures the
glass transition becomes suppressed by quantum tunnelling.Comment: J. Non-Cryst. Solids, in press. 6 pages, 4 figure
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Assessing Models of Public Understanding In ELSI Outreach Materials
Advances in the science of genetics have implications for individuals and society, and have to be taken into account at the policy level. Studies of ethical, legal and social issues related to genomic research have therefore been integrated in the Human Genome Project (HGP) since the earliest days of the project. Since 1990, three to five percent of the HGP annual budget has been devoted to such studies, under the umbrella of the Ethical, Legal, and Social Implications (ELSI) Programs of the National Human Genome Research Institute of the National Institute of Health, and of the Office of Biological and Environmental Research of the U.S. Department of Energy (DOE). The DOE-ELSI budget has been used to fund a variety of projects that have aimed at ?promoting education and help guide the conduct of genetic research and the development of related medical and public policies? (HGP, 2003). As part of the educational component, a significant portion of DOE-ELSI funds have been dedicated to public outreach projects, with the underlying goal of promoting public awareness and ultimately public discussion of ethical, legal, and social issues surrounding availability of genetic information (Drell, 2002). The essential assumption behind these projects is that greater access to information will lead to more knowledge about ethical, legal and social issues, which in turn will lead to enhanced ability on the part of individuals and communities to deal with these issues when they encounter them. Over the same period of time, new concepts of ?public understanding of science? have emerged in the theoretical realm, moving from a ?deficit? or linear dissemination of popularization, to models stressing lay-knowledge, public engagement and public participation in science policy-making (Lewenstein, 2003). The present project uses the base of DOE-funded ELSI educational project to explore the ways that information about a new and emerging area of science that is intertwined with public issues has been used in educational public settings to affect public understanding of science. After a theoretical background discussion, our approach is three-fold. First, we will provide an overview, a ?map? of DOE-funded of outreach programs within the overall ELSI context to identify the importance of the educational component, and to present the criteria we used to select relevant and representative case studies. Second, we will document the history of the case studies. Finally, we will explore an intertwined set of research questions: (1) To identify what we can expect such projects to accomplish -in other words to determine the goals that can reasonably be achieved by different types of outreach, (2) To point out how the case study approach could be useful for DOE-ELSI outreach as a whole, and (3) To use the case study approach as a basis to test theoretical models of science outreach in order to assess to what extent those models accord with real world outreach activities. For this last goal, we aim at identifying what practices among ELSI outreach activities contribute most to dissemination, or to participation, in other words in which cases outreach materials spark action in terms of public participation in decisions about scientific issues
Spin and orbital frustration in MnSc_2S_4 and FeSc_2S_4
Crystal structure, magnetic susceptibility, and specific heat were measured
in the normal cubic spinel compounds MnSc_2S_4 and FeSc_2S_4. Down to the
lowest temperatures, both compounds remain cubic and reveal strong magnetic
frustration. Specifically the Fe compound is characterized by a Curie-Weiss
temperature \Theta_{CW}= -45 K and does not show any indications of order down
to 50 mK. In addition, the Jahn-Teller ion Fe^{2+} is orbitally frustrated.
Hence, FeSc_2S_4 belongs to the rare class of spin-orbital liquids. MnSc_2S_4
is a spin liquid for temperatures T > T_N \approx 2 K.Comment: 4 pages, to be published in Physical Review Letter
Field-induced spin density wave in (TMTSF)NO
Interlayer magnetoresistance of the Bechgaard salt (TMTSF)NO is
investigated up to 50 teslas under pressures of a few kilobars. This compound,
the Fermi surface of which is quasi two-dimensional at low temperature, is a
semi metal under pressure. Nevertheless, a field-induced spin density wave is
evidenced at 8.5 kbar above 20 T. This state is characterized by a
drastically different spectrum of the quantum oscillations compared to the low
pressure spin density wave state.Comment: to be published in Phys. Rev. B 71 (2005
Usability improvements of the Thermipig model for precision pig farming
Pig livestock farming systems encounter several economic and environmental
challenges, connected with meat price decrease, sanitary norms, emissions etc. To deal with these
issues, methods and models to assess the performance of a pig production system have been
developed. For instance, Thermipig model represents the pig fattening room and simulates
performances of pigs at the batch level, taking into account interactions between the individual
variability of pigs, farmer's practices, room characteristics and outdoor climate conditions. The
model requires some static basic inputs fulfilled in several spreadsheets (such as rooms, pigs, and
dietary characteristics) but also data files for voluminous variable inputs (such as outdoor
temperature or climate control box parameters) for further modelling and outcome producing.
This leads to challenges in data providing by the farmers and have to be improved. This paper
deals with the implementation of the separate modules of the developed data warehouse system
for usability improvements of the Thermipig model. The idea is to substitute input from the data
files with online data input and automated variable processing by the model using the python
script for connection to the remote data warehouse. The data warehouse system is extended with
‘Property Sets’ section dealing with all the operations that can be performed to a set of input
variables. This approach demonstrates the ability of the data warehouse to act as data supplier for
the remote model. As well the outcome of the model is also transferable back to the data
warehouse for evaluation. This work is done within the Era-Net SuSan PigSys project - Improving
pig system performance through a whole system approach
Superconductivity in an organic insulator at very high magnetic fields
We investigate by electrical transport the field-induced superconducting
state (FISC) in the organic conductor -(BETS)FeCl. Below 4 K,
antiferromagnetic-insulator, metallic, and eventually superconducting (FISC)
ground states are observed with increasing in-plane magnetic field. The FISC
state survives between 18 and 41 T, and can be interpreted in terms of the
Jaccarino-Peter effect, where the external magnetic field {\em compensates} the
exchange field of aligned Fe ions. We further argue that the Fe
moments are essential to stabilize the resulting singlet, two-dimensional
superconducting stateComment: 9 pages 3 figure
Superconducting pairing and density-wave instabilities in quasi-one-dimensional conductors
Using a renormalization group approach, we determine the phase diagram of an
extended quasi-one-dimensional electron gas model that includes interchain
hopping, nesting deviations and both intrachain and interchain repulsive
interactions. d-wave superconductivity, which dominates over the
spin-density-wave (SDW) phase at large nesting deviations, becomes unstable to
the benefit of a triplet -wave phase for a weak repulsive interchain
backscattering term , despite the persistence of dominant SDW
correlations in the normal state. Antiferromagnetism becomes unstable against
the formation of a charge-density-wave state when exceeds some
critical value. While these features persist when both Umklapp processes and
interchain forward scattering () are taken into account, the effect
of alone is found to frustrate nearest-neighbor interchain - and
-wave pairing and instead favor next-nearest-neighbor interchain singlet or
triplet pairing. We argue that the close proximity of SDW and
charge-density-wave phases, singlet d-wave and triplet -wave superconducting
phases in the theoretical phase diagram provides a possible explanation for
recent puzzling experimental findings in the Bechgaard salts, including the
coexistence of SDW and charge-density-wave phases and the possibility of a
triplet pairing in the superconducting phase.Comment: 19 pages, 13 figure
Magnetic-field-induced superconductivity in layered organic molecular crystals with localized magnetic moments
The synthetic organic compound lambda-(BETS)2FeCl4 undergoes successive
transitions from an antiferromagnetic insulator to a metal and then to a
superconductor as a magnetic field is increased. We use a Hubbard-Kondo model
to clarify the role of the Fe(3+) magnetic ions in these phase transitions. In
the high-field regime, the magnetic field acting on the electron spins is
compensated by the exchange field He due to the magnetic ions. This suggests
that the field-induced superconducting state is the same as the zero-field
superconducting state which occurs under pressure or when the Fe(3+) ions are
replaced by non-magnetic Ga(3+) ions. We show how He can be extracted from the
observed splitting of the Shubnikov-de Haas frequencies. Furthermore, we use
this method of extracting He to predict the field range for field-induced
superconductivity in other materials.Comment: 5 page
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