Phase Separation and the Dual Nature of the Electronic Structure in Cuprates

The dual nature of the electronic structure of stripes in $La_{2-x}Sr_xCuO_4$ was characterized by experimental observations, mainly by ARPES, of nodal spectral weight together with the straight segments near antinodal regions. We present here an attempt to understand this dual behavior in terms of the competition of order and disorder, by applying the phase separation theory of Cahn-Hilliard (CH) to the high pseudogap temperature, which is very large in the far underdoping region and vanishs near the doping level p=0.2. The spinodal phase separation predictions together with the Bogoliubov-deGennes (BdG) superconducting theory provides several interesting insights. For instance, we find that the disorder enhances the local superconducting gap which scales with the leading edge shift and that, upon doping, the size of the hole-rich stripes increases, yielding to the system their metallic properties.Comment: revised version, 4 pages and 3 fig

Abundance, Diversity, and Distribution of Potential Mosquito Vector Fauna in the Wellamadama Premises of the University of Ruhuna, Southern Sri Lanka

  Mosquitoes play a significant role in causing disease outbreaks among humans and animals in many parts of the world. Assessing the risk of disease outbreaks related to vector-borne diseases requires a thorough understanding of the population dynamics of vectors in a specific area. The present study was conducted weekly from August 2023 to October 2023 at the Wellamadama premises of the University of Ruhuna, Sri Lanka. Mosquitoes were collected in two major habitat types, i.e., areas with high anthropogenic activities (HAA) and low anthropogenic activities (LAA), to assess the population structure of potential vector mosquito fauna. Bird-baited traps, mammal-baited traps, CO2 traps, and light traps were used for mosquito surveillance. All traps were placed at the ground level (1.5-3.0 m), except the bird-bated traps, which were placed 6 m above the ground level. An equal number of traps from each trap type were placed in both HAA and LAA on each sampling date. Collected mosquitoes were identified using standard taxonomic keys. Environmental factors with species abundance and diversity were assessed with canonical correspondence analysis from PAST 4.13. Shannon's diversity index (H’) (HAA:1.767, LAA:2.064) and Margalef’s index (Mg’) (HAA:1.486, LAA:3.194) were used to compare the abundance and diversity of selected habitat types. A total of 423 mosquitoes that belong to 18 species and eight genera (i.e., Anopheles, Aedeomyia, Aedes, Armigeres, Culex, Lutzia, Coquillettidia, and Mansonia) were identified. Even though the diversity was higher in the LAA (18 species) than in the HAA (9 species), the abundance of mosquitoes in the HAA (n=218) is not significantly different from LAA (n=205) (t=0.09, p=0.932). The Lutzia halifaxii, Ad. catasticta, Ma. unifromis, Cx. sinensis, Cx. pluvialis, Cx. malayi, Cx. gelidus, Ae. vexans, and An. jamesii were only found in LAA, while An. culicifacies, An. subpictus, An. varuna, Aedes aegypti, Ae. albopictus, Ar. subalbatus, Cx. tritaentorhynchus, Cx. quinquefasciatus, and Cq. crassipes were common to both study sites. With the environmental parameters except for Coquillettidia and Culex, the rest of the genera were positively correlated with the temperature (r=0.209) and negatively correlated with RH (r=-0.480). The study identified a total of 11 human vector species and 7 non-human vector mosquito species. The high abundance and widespread distribution of vector mosquitoes underscores the potential for mosquito-borne diseases to spread within the university premises.   Keywords: Mosquito taxonomy, Environmental factors, Disease outbreaks, Traps, Risk assessment   Financial assistance from the University Research Grant (Grant No: RU/SF/RP/2022/21) is acknowledged. &nbsp

Specific heat and magnetic order in LaMnO_{3+\delta}

Magnetic and specific-heat measurements are performed in three different samples of LaMnO_{3+\delta}, with \delta=0.11, 0.15 and 0.26, presenting important disorder effects, such as carrier localization, due to high amounts of La and Mn vacancies. For the samples with \delta =0.11 and 0.15, magnetic measurements show signatures of a two-step transition: as the temperature is lowered, the system enters a ferromagnetic phase followed by a disorder-induced cluster-glass state. Spin-wave-like contributions and an unexpected large linear term are observed in the specific heat as a function of temperature. In the sample with the highest vacancy content, \delta=0.26, the disorder is sufficient to suppress even short-range ferromagnetic order and yield a spin-glass-like state.Comment: RevTeX 2-col, 8 pages, 5 ps figures included, submitted to PR

The distribution and production of submerged macrophytes in Loch Leven, Kinross

SynopsisThe distribution and production of submerged macrophytes in Loch Leven has been investigated using drag-rake surveys and biomass measurements. Survey data suggest that changes in the species diversity of the loch have occurred since the earlier records. There appears to have been a decline in some species with an increase in others.In general there has been an overall loss in species diversity which may be correlated with the increasingly eutrophic status of Loch Leven. At present the macrophyte flora is dominated by a few species, notably Potamogeton filiformis, Zannichellia palustris, Nitella opaca and algal periphyton, with declining, though still significant amounts of Chora aspera. It is probable that the species diversity is in the process of adjusting to the eutrophic status of the loch and that P. filiformis in particular is in an expanding condition.</jats:p