27,413 research outputs found
Unconventional carrier-mediated ferromagnetism above room temperature in ion-implanted (Ga, Mn)P:C
Ion implantation of Mn ions into hole-doped GaP has been used to induce
ferromagnetic behavior above room temperature for optimized Mn concentrations
near 3 at.%. The magnetism is suppressed when the Mn dose is increased or
decreased away from the 3 at.% value, or when n-type GaP substrates are used.
At low temperatures the saturated moment is on the order of one Bohr magneton,
and the spin wave stiffness inferred from the Bloch-law T^3/2 dependence of the
magnetization provides an estimate Tc = 385K of the Curie temperature that
exceeds the experimental value, Tc = 270K. The presence of ferromagnetic
clusters and hysteresis to temperatures of at least 330K is attributed to
disorder and proximity to a metal-insulating transition.Comment: 4 pages, 4 figures (RevTex4
On the expressiveness of mixed choice sessions
Session types provide a flexible programming style for structuring interaction, and are used to guarantee a safe and consistent composition of distributed processes. Traditional session types include only one-directional input (external) and output (internal) guarded choices. This prevents the session-processes to explore the full expressive power of the pi-calculus where the mixed choices are proved more expressive than the (non-mixed) guarded choices. To account this issue, recently Casal, Mordido, and Vasconcelos proposed the binary session types with mixed choices (CMV+). This paper carries a surprising, unfortunate result on CMV+: in spite of an inclusion of unrestricted channels with mixed choice, CMV+'s mixed choice is rather separate and not mixed. We prove this negative result using two methodologies (using either the leader election problem or a synchronisation pattern as distinguishing feature), showing that there exists no good encoding from the pi-calculus into CMV+, preserving distribution. We then close their open problem on the encoding from CMV+ into CMV (without mixed choice), proving its soundness and thereby that the encoding is good up to coupled similarity
Magnetic phases in the correlated Kondo-lattice model
We study magnetic ordering of an extended Kondo-lattice model including an
additional on-site Coulomb interaction between the itinerant states. The model
is solved in the dynamical mean-field theory using Wilson's numerical
renormalization group approach as impurity solver. For a bipartite lattice we
find at half filling the expected antiferromagnetic phase. Upon doping this
phase is gradually suppressed and hints towards phase separation are observed.
For large doping the model exhibits ferromagnetism, the appearance of which can
at first sight be explained by Rudermann-Kittel-Kasuya-Yosida interaction.
However, for large values of the Kondo coupling significant differences to
a simple Rudermann-Kittel-Kasuya-Yosida picture can be found. We furthermore
observe signs of quantum critical points for antiferromagnetic Kondo coupling
between the local spins and band states
Inhibition of \u3cem\u3eRhizobium etli\u3c/em\u3e Polysaccharide Mutants by \u3cem\u3ePhaseolus vulgaris\u3c/em\u3e Root Compounds
Crude bean root extracts of Phaseolus vulgaris were tested for inhibition of the growth of several polysaccharide mutants of Rhizobium etli biovar phaseoli CE3. Mutants deficient only in exopolysaccharide and some mutants deficient only in the O-antigen of the lipopolysaccharide were no more sensitive than the wild-type strain to the extracts, whereas mutants defective in both lipopolysaccharide and exopolysaccharide were much more sensitive. The inhibitory activity was found at much higher levels in roots and nodules than in stems or leaves. Inoculation with either wild-type or polysaccharide-deficient R. etli did not appear to affect the level of activity. Sequential extractions of the crude root material with petroleum ether, ethyl acetate, methanol, and water partitioned inhibitory activity into each solvent except methanol. The major inhibitors in the petroleum ether and ethyl acetate extracts were purified by C18 high-performance liquid chromatography. These compounds all migrated very similarly in both liquid and thin-layer chromatography but were distinguished by their mass spectra. Absorbance spectra and fluorescence properties suggested that they were coumestans, one of which had the mass spectrum and nuclear magnetic resonances of coumestrol. These results are discussed with regard to the hypothesis that one role of rhizobial polysaccharides is to protect against plant toxins encountered during nodule development
Механические свойства композита на основе Al[2]O[3], армированного одностенными углеродными нанотрубками
Subject of this work is a dynamic simulation strategy for PCCI combustion that can be
used in closed-loop control development. A detailed multi-zone chemistry model for the
high-pressure part of the engine cycle is extended by a mean value model accounting for
the gas exchange losses. The resulting stationary model is capable of describing PCCI
combustion sufficiently well. It is at the same time very economic with respect to
computational costs. The model is further extended by identified system dynamics
influencing the stationary inputs. For this, a Wiener model is set up that uses the
stationary model as a nonlinear system representation. In this way, a dynamic nonlinear
model for the representation of the controlled plant Diesel engine is created. This paper
summarizes an important outcome of the the Collaborative Research Centre "SFB 686 -
Modellbasierte Regelung der homogenisierten Niedertemperatur-Verbrennung" at RWTH Aachen
University and Bielefeld University, Germany
Intestinal transplantation under tacrolimus monotherapy after perioperative lymphoid depletion with rabbit anti-thymocyte globulin (thymoglobulin®)
Modifications in the timing and dosage of immunosuppression can ameliorate the morbidity and mortality that has prevented widespread use of intestinal transplantation (ITx) in children. Thirty-six patients receiving ITx, aged 5 months to 20 years were given 2-3 mg(kg of rabbit anti-thymocyte globulin (rATG, thymoglobulin®) just before ITx, and 2-3 mg(kg post-operatively (total 5 mg(kg). Twice daily doses of tacrolimus (TAC) were begun enterally within 24 h after graft reperfusion with reduction of dose quantity or frequency after 3 months. Prednisone or other agents were given to treat breakthrough rejection. After 8-28 months follow-up (mean 15.8 ± 5.3), 1- and 2-year patient and graft survival is 100% and 94%, respectively. Despite a 44% incidence of acute rejection in the first month, 16 of the 34 (47%) survivors are on TAC (n = 14) or sirolimus (n = 2) monotherapy; 15 receive TAC plus low dose prednisone; one each receive TAC plus sirolimus, TAC plus azathioprine and TAC plus sirolimus and prednisone. There was a low incidence of immunosuppression-related complications. This strategy of immunosuppression minimized maintenance TAC exposure, facilitated the long-term control of rejection, decreased the incidence of opportunistic infections, and resulted in a high rate of patient and graft survival. Copyright © Blackwell Munksgaard 2005
Leveraging palaeoproteomics to address conservation and restoration agendas
Summary Archaeological and paleontological records offer tremendous yet often untapped potential for examining long-term biodiversity trends and the impact of climate change and human activity on ecosystems. Yet, zooarchaeological and fossil remains suffer various limitations, including that they are often highly fragmented and morphologically unidentifiable, preventing them from being optimally leveraged for addressing fundamental research questions in archaeology, paleontology, and conservation paleobiology. Here, we explore the potential of palaeoproteomics—the study of ancient proteins—to serve as a critical tool for creating richer, more informative datasets about biodiversity change that can be leveraged to generate more realistic, constructive, and effective conservation and restoration strategies into the future.What is the scope for conservation palaeoproteomics? Assessing species richness Establishing ecological baselines Detecting shifts in species abundance and geographic range Disentangling human-environment interactions Tracking the introduction of non-native species Identifying illicitly traded material Prioritizing species for conservation The future of conservation palaeoproteomics Limitations of the stud
Model projects as tools for cooperative urban development: The case of Haus der Statistik in Berlin
According to the New Leipzig Charter, urban development processes should be ‘a matter of all’ – the common good, climate protection and environmental justice, to name but a few aspects. Currently, new forms of innovation seeking models emerge within this context of sustainable urban planning practice - for example, real-world field laboratories and model projects. Haus der Statistik in Berlin is one such ‘model project for cooperative and common-good-oriented urban development’. It is widely recognized for its demand- and process-driven approach, as well as its project development being based on public-civic partnership. As anthropological and urbanist researchers and practitioners involved in the project, we give a situated account on the socio-political elements of the Haus der Statistik’s public-civic partnership and investigate the potentials of this model for a more sustainable urban development. The structure of the paper is threefold: Firstly, we introduce the so-called model project Haus der Statistik and its common-good orientated agenda and relate it to sustainability goals of the New Leipzig Charter. Secondly, we introduce the specific public-civic-framework in regard to its methodological framing within the context of model projects and comparable approaches that focus on collaborative, transdisciplinary and innovative methods, such as real-world field laboratories. Thirdly, we reflect on the elements of the public-civic-partnership framework that have been explored and developed at the ‘model project’ Haus der Statistik since 2015 and its implications for a more sustainable urban development.Peer Reviewe
Vegetation composition and soil microbial community structural changes along a wetland hydrological gradient
Fluctuations in wetland hydrology create an interplay between aerobic and anaerobic conditions, controlling vegetation composition and microbial community structure and activity in wetland soils. In this study, we investigated the vegetation composition and microbial community structural and functional changes along a wetland hydrological gradient. Two different vegetation communities were distinguished along the hydrological gradient; <i>Caricetum gracilis</i> at the wet depression and <i>Arrhenatheretum elatioris</i> at the drier upper site. Microbial community structural changes were studied by a combined in situ <sup>13</sup>CO<sub>2</sub> pulse labeling and phospholipid fatty acid (PLFA) based stable isotope probing approach, which identifies the microbial groups actively involved in assimilation of newly photosynthesized, root-derived C in the rhizosphere soils. Gram negative bacterial communities were relatively more abundant in the surface soils of the drier upper site than in the surface soils of the wetter lower site, while the lower site and the deeper soil layers were relatively more inhabited by gram positive bacterial communities. Despite their large abundance, the metabolically active proportion of gram positive bacterial and actinomycetes communities was much smaller at both sites, compared to that of the gram negative bacterial and fungal communities. This suggests much slower assimilation of root-derived C by gram positive and actinomycetes communities than by gram negative bacteria and fungi at both sites. Ground water depth showed a significant effect on the relative abundance of several microbial communities. Relative abundance of gram negative bacteria significantly decreased with increasing ground water depth while the relative abundance of gram positive bacteria and actinomycetes at the surface layer increased with increasing ground water depth
Scaling in the Bombay Stock Exchange Index
In this paper we study BSE Index financial time series for fractal and
multifractal behaviour. We show that Bombay stock Exchange (BSE)Index time
series is mono-fractal and can be represented by a fractional Brownian motion.Comment: 11 pages,3 figure
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