Voltage-current and voltage-flux characteristics of asymmetric high TC DC SQUIDs

We report measurements of transfer functions and flux shifts of 20 on-chip high T$_C$ DC SQUIDs half of which were made purposely geometrically asymmetric. All of these SQUIDs were fabricated using standard high T$_C$ thin film technology and they were single layer ones, having 140 nm thickness of YBa$_2$Cu$_3$O$_{7-x}$ film deposited by laser ablation onto MgO bicrystal substrates with 24$^0$ misorientation angle. For every SQUID the parameters of its intrinsic asymmetry, i. e., the density of critical current and resistivity of every junction, were measured directly and independently. We showed that the main reason for the on-chip spreading of SQUIDs' voltage-current and voltage-flux characteristics was the intrinsic asymmetry. We found that for SQUIDs with a relative large inductance ($L>120$ pH) both the voltage modulation and the transfer function were not very sensitive to the junctions asymmetry, whereas SQUIDs with smaller inductance ($L\simeq 65-75$ pH) were more sensitive. The results obtained in the paper are important for the implementation in the sensitive instruments based on high T$_C$ SQUID arrays and gratings.Comment: 11 pages, 4 tables, 17 figures This version is substantially modified. The Introduction and Section 2 are completely rewritten, while experimental part is mainly the same as in previous versio

Core Collection Approaches and Genetic Diversity in \u3ci\u3eFlemingia macrophylla\u3c/i\u3e

Core collections are a useful means to optimise the management, including conservation, of forage germplasm collections. Such optimisation is warranted in view of increasingly limited research resources. As there are several potential options to create core collections, a project is presented in which three approaches are compared: (i) based on germplasm origin information; (ii) genetic diversity assessment by agronomic characterisation/evaluation; and (iii) DNA markers. As example-species for the project, the tropical legume shrub Flemingia macrophylla is selected because of its particular multiple-use potential in smallholder production systems. An important diversity descriptor is the content of tannins influencing feed and litter quality of this species. Data will be analysed using multivariate statistics and GIS tools. The results from the core collection approach comparison are expected to be applicable also to other wild legumes

Potential Role of Native Bush in the Chaco for Mitigation of Dryland Salinity in Grassland

There is a zone of some 3.000.000 ha with an elevated dryland salinity risk in the Paraguayan Chaco due to a shallow saline ground water table. Evidence is shown of the crucial role native bush seems to play in keeping the water table at a low level and reducing therefore the risk of soil salinisation. In this paper a planned field experiment is outlined to define the tolerable level of deforestation and pasture establishment for a sylvopastoral production system in the Chacoan zone prone to dryland salinity

Amphicarpy in the Tropical Legume \u3ci\u3eCentrosema rotundifolium\u3c/i\u3e: A Research Project in Eastern Venezuela

Amphicarpy is a particular reproduction mechanism by which a plant can produce both above-ground and below-ground seeds and thus has the potential to contribute to an enhanced persistence of a plant population. It can be found in a range of tropical legumes, e.g. in several Centrosema species. The balance between above- and below-ground seed production is evidently influenced by environment and management factors but these influences are not well known. In the case of perennial tropical legumes, in addition to seed production shifts the allocation of resources affects also the production of tuberous roots as storage organs. A research project in El Tigre, Eastern Venezuela, investigates the extent to which resource allocation is influenced by five management (= environmental stress) factors: plant density, associated grass, fertilization, cutting intensity, and fire. The species chosen for this research is Centrosema rotundifolium, a perennial, moderately productive legume which because of its amphicarpy-based persistence and its adaptation to sandy and acid, low-fertility soils has a potential as pasture plant and for soil conservation on sandy savanna soils of the dry-subhumid tropic

In vivo cell synchrony in the L1210 mouse leukaemia studied with 5-fluorouracil or 5-fluorouracil followed by cold thymidine infusion.

[3H]-TdR and [3]-udR labelling indices and mitotic indices were followed in tumour-bearing mice after application of either 5-fluorouracil (FU) alone or of FU followed by cold TdR infusion. With FU alone, accumulation of cells at the beginning of S was found, but there was no indication of a synchronous passage of the accumulated cells further round the cycle. When FU injection was followed by cold TdR infusion, a synchronous passage of the accumulated cells through the cycle was observed. However, there was a large variation in the response of individual mice to this treatment

Amphicarpic Legumes for Tropical Pasture Persistence

Amphicarpy, by which a plant produces underground seeds in addition to aerial fruits, is found in many plant families and in species of at least 15 legume genera. First studies on the tropical Centrosema rotundifolium and subtropical Macroptilium panduratum revealed for both species, besides their stoloniferous growth habit, two important mechanisms for survival under unfavorable conditions: (1) Underground meristems and reserve organs, and (2) regeneration from a soil seed reserve based on underground, aerial-flowering independent, seed production. Underground seed production was for both species particularly high on very sandy soils, but amphicarpy enables the plants to exhibit a plasticity response to unfavourable soil conditions by changing resource allocation from underground to above-ground reproduction. The latter, which seems to be influenced by cross-pollination and thus aids gene-recombination, favours spreading of plant populations whereas underground reproduction ensures population survival on-site. Preliminary information on the agronomic potential of both species is given and several research needs are highlighted

Evaluation of \u3ci\u3eCentrosema rotundifolium\u3c/i\u3e for Sand-Soil Savannas in Eastern Venezuela

An evaluation of a collection of amphicarpic Centrosema rotundifolium showed considerable variability among the six accessions tested, regarding above- and below-ground seed production. Dry-season forage yields were very low but rainy-season yields reached acceptable levels. Contents of crude protein, P and Ca were intermediate to high (CP and P) or low (Ca). Three accessions are suggested for on-farm testing in association with grasses in order to explore the plant persistence implications of belowground seed production under practical conditions. Furthermore, the potential of this amphicarpic species for the conservation of sandy soils deserves attention

Fauna, Flora, and Land Cover Changes Over the Last Two Decades in the Mobile-Tensaw River Delta

A technical report documenting ecosystem changes to the Mobile-Tensaw River Delta region due to urban expansion over approximately two decades (2001-2019)