83 research outputs found
The Presence of Lampreys in the Tyrrhenian Rivers of the Campania Region (Southern Italy): A New Record of the Sea Lamprey Petromyzon marinus (Linnaeus 1758).
The southern Italian peninsula has been suggested to be an important European district for lampreysâ genetic diversity. All lamprey species ever described throughout the Italian peninsula are protected within European legislation and listed in Annex II of the EU Habitats Directive (92/43/EEC)and Annex III of the Bern Convention (82/72/CEE) as species of conservation concern, and the Habitats Directive ensures the designation of âsites of community interestâ (SICs) for threatened species. During a survey to collect preliminary data on lampreysâ presence in the Cilento, Vallo di Daino, and Alburni National Park (PNCV) located in the Campania region, where 28 sites of community interest (SICs) have been established by the EU Habitats Directive (92/43/EEC), two
specimens of sea lamprey (Petromyzon marinus, Linnaeus, 1758) were detected for the first time. The specimens were genetically characterized through the sequencing of the mtDNA control region locus. The study highlighted the significant importance of the Campania region for lampreys, which,concerning Lampetra sp., was found to have peculiar genetic characteristics and unique alleles that have not been described elsewhere. Furthermore, the recognition of the sea lamprey, P. marinus, emphasized the value of this area, especially in terms of laying the groundwork for future habitat protection strategies
Mapping Orientational Order of Charge-Probed Domains in a Semiconducting Polymer
Structureâproperty relationships are of fundamental importance to develop quantitative models describing charge transport in organic semiconductor based electronic devices, which are among the best candidates for future portable and lightweight electronic applications. While microstructural investigations, such as those based on X-rays, electron microscopy, or polarized optical probes, provide necessary information for the rationalization of transport in macromolecular solids, a general model predicting how charge accommodates within structural maps is not yet available. Therefore, techniques capable of directly monitoring how charge is distributed when injected into a polymer film and how it correlates to structural domains can help fill this gap. Supported by density functional theory calculations, here we show that polarized charge modulation microscopy (p-CMM) can unambiguously and selectively map the orientational order of the only conjugated segments that are probed by mobile charge in the few nanometer thick accumulation layer of a high-mobility polymer-based field-effect transistor . Depending on the specific solvent-induced microstructure within the accumulation layer, we show that p-CMM can image charge-probed domains that extend from submicrometer to tens of micrometers size, with markedly different degrees of alignment. Wider and more ordered p-CMM domains are associated with improved carrier mobility, as extracted from device characteristics. This observation evidences the unprecedented opportunity to correlate, directly in a working device, electronic properties with structural information on those conjugated segments involved in charge transport at the buried semiconductorâdielectric interface of a field-effect device
Current and historical genetic variability of native brown trout populations in a southern alpine ecosystem: implications for future management
The highly polymorphic taxon European brown trout (genus Salmo) has high phenotypic plasticity, displaying a complex pattern of morphological and life-history variation, contributing to taxonomic confusion. Three main mitochondrial lineages (Adriatic, Mediterranean, and marmoratus) developed during the Pleistocene climatic events in the southern Alpine ecosystem. Here, the natural distribution of native brown trout S. trutta is controversial, complicated by introductions of the Atlantic strain. By investigating museum vouchers, this study aimed to retrace the historical presence of brown trout in the southern Alpine ecosystem before the beginning of mass introductions, which occurred since the middle of the 19th century. By examining the combination of historical and current genetic variability, this study aims to depict the actual impact of introductions of the introduced strain, increasing knowledge and informing conservation strategies and future management plans. The molecular approaches selected were: (i) sequencing of the mitochondrial control region and (ii) genotyping of the nuclear gene LDH-C1*. Vouchers dated the presence of the native Adriatic strain since 1821, while current genetic variability showed the widespread signature of introgression, a consequence of several decades of introductions. Focused plans to preserve local lineages are urgently needed, including short-term solution to avoid complete pauperization of this ecosystem
Patterning of ultrathin YBCO nanowires using a new focused-ion-beam process
Manufacturing superconducting circuits out of ultrathin films is a
challenging task when it comes to patterning complex compounds, which are
likely to be deteriorated by the patterning process. With the purpose of
developing high-T superconducting photon detectors, we designed a novel
route to pattern ultrathin YBCO films down to the nanometric scale. We believe
that our method, based on a specific use of a focused-ion beam, consists in
locally implanting Ga^{3+} ions and/or defects instead of etching the film.
This protocol could be of interest to engineer high-T superconducting
devices (SQUIDS, SIS/SIN junctions and Josephson junctions), as well as to
treat other sensitive compounds.Comment: 13 pages, 7 figure
Micro- and Nanopatterned Silk Substrates for Antifouling Applications
A major problem of current biomedical implants is the bacterial colonization and subsequent biofilm formation, which seriously affects their functioning and can lead to serious post-surgical complications. Intensive efforts have been directed toward the development of novel technologies that can prevent bacterial colonization while requiring minimal antibiotics doses. To this end, biocompatible materials with intrinsic antifouling capabilities are in high demand. Silk fibroin, widely employed in biotechnology, represents an interesting candidate. Here, we employ a soft-lithography approach to realize micro- and nanostructured silk fibroin substrates, with different geometries. We show that patterned silk film substrates support mammal cells (HEK-293) adhesion and proliferation, and at the same time, they intrinsically display remarkable antifouling properties. We employ Escherichia coli as representative Gram-negative bacteria, and we observe an up to 66% decrease in the number of bacteria that adhere to patterned silk surfaces as compared to control, flat silk samples. The mechanism leading to the inhibition of biofilm formation critically depends on the microstructure geometry, involving both a steric and a hydrophobic effect. We also couple silk fibroin patterned films to a biocompatible, optically responsive organic semiconductor, and we verify that the antifouling properties are very well preserved. The technology described here is of interest for the next generation of biomedical implants, involving the use of materials with enhanced antibacterial capability, easy processability, high biocompatibility, and prompt availability for coupling with photoimaging and photodetection techniques
Role of Interfaces in the Proximity Effect in Anisotropic Superconductors
We report measurements of the critical temperature of YBCO-Co doped YBCO
Superconductor-Normal bilayer films. Depending on the morphology of the S-N
interface, the coupling between S and N layers can be turned on to depress the
critical temperature of S by tens of degrees, or turned down so the layers
appear almost totally decoupled. This novel effect can be explained by the
mechanism of quasiparticle transmission into an anisotropic superconductor.Comment: 13 pages, 3 figure
Vicariance in a generalist fish parasite driven by climate and salinity tolerance of hosts
Acanthocephalans are parasites with complex lifecycles that are important components of
aquatic systems and are often model species for parasite-mediated host manipulation.
Genetic characterization has recently resurrected Pomphorhynchus tereticollis as a distinct species from Pomphorhynchus laevis, with potential implications for fisheries management and
host manipulation research. Morphological and molecular examinations of parasites from 7
English rivers across 9 fish species revealed that P. tereticollis was the only Pomphorhynchus
parasite present in Britain, rather than P. laevis as previously recorded. Molecular analyses
included two non-overlapping regions of the mitochondrial gene â cytochrome oxidase
and generated 62 sequences for the shorter fragment (295 bp) and 74 for the larger fragment
(583 bp). These were combined with 61 and 13 sequences respectively, from Genbank. A
phylogenetic analysis using the two genetic regions and all the DNA sequences available
for P. tereticollis identified two distinct genetic lineages in Britain. One lineage, possibly associated with cold water tolerant fish, potentially spread to the northern parts of Britain from
the Baltic region via a northern route across the estuarine area of what is now the North
Sea during the last Glaciation. The other lineage, associated with temperate freshwater fish,
may have arrived later via the Rhine/Thames fluvial connection during the last glaciation
or early Holocene when sea levels were low. These results raise important questions on this
generalist parasite and its variously environmentally adapted hosts, and especially in relation
to the consequences for parasite vicariance
Normal-superconducting transition induced by high current densities in YBa2Cu3O7-d melt-textured samples and thin films: Similarities and differences
Current-voltage characteristics of top seeded melt-textured YBa2Cu3O7-d are
presented. The samples were cut out of centimetric monoliths. Films
characteristics were also measured on microbridges patterned on thin films
grown by dc sputtering. For both types of samples, a quasi-discontinuity or
quenching was observed for a current density J* several times the critical
current density Jc. Though films and bulks much differ in their magnitude of
both Jc and J*, a proposal is made as to a common intrinsic origin of the
quenching phenomenon. The unique temperature dependence observed for the ratio
J*/Jc, as well as the explanation of the pre-quenching regime in terms of a
single dissipation model lend support to our proposal.Comment: 10 pages, 10 figures, submitted to Physical Review
Transport Properties, Thermodynamic Properties, and Electronic Structure of SrRuO3
SrRuO is a metallic ferromagnet. Its electrical resistivity is reported
for temperatures up to 1000K; its Hall coefficient for temperatures up to 300K;
its specific heat for temperatures up to 230K. The energy bands have been
calculated by self-consistent spin-density functional theory, which finds a
ferromagnetic ordered moment of 1.45 per Ru atom. The measured
linear specific heat coefficient is 30mJ/mole, which exceeds the
theoretical value by a factor of 3.7. A transport mean free path at room
temperature of is found. The resistivity increases nearly
linearly with temperature to 1000K in spite of such a short mean free path that
resistivity saturation would be expected. The Hall coefficient is small and
positive above the Curie temperature, and exhibits both a low-field and a
high-field anomalous behavior below the Curie temperature.Comment: 6 pages (latex) and 6 figures (postscript, uuencoded.) This paper
will appear in Phys. Rev. B, Feb. 15, 199
Environmental DNA as a nonâinvasive sampling tool to detect the spawning distribution of European anadromous shads (Alosa spp.)
1. Populations of the European shads Alosa alosa (Linnaeus, 1758) and Alosa fallax LacĂŠpède, 1800 (Alosa spp.) are protected under legislation because of their vulnerability to human disturbances. In particular, river impoundments block their upstream migration, preventing access to spawning areas. Knowledge on the spatial extent of their spawning is important for informing conservation and river management plans. 2. Determining the spatial extent of Alosa spp. spawning is challenging. They enter rivers over a 2â3âmonth period and the species potentially migrate different distances upstream. Capture and handling can be problematic, spawning events generally occur at night, and kickâsampling for eggs is limited to shallow water. Assessing their spatial extent of spawning could, however, incorporate nonâinvasive sampling tools, such as environmental DNA (eDNA). 3. An eDNA assay for Alosa spp. was successfully developed, based on the cytochrome c oxidase subunit I gene segment and quantitative polymerase chain reaction (qPCR). Application in spring 2017 to the River Teme (River Severn catchment, western England) revealed high sensitivity in both laboratory and field trials. Field data indicated Alosa spp. spawning between May and June, with migrants mainly restricted to areas downstream of the final impoundment. 4. eDNA can thus be used as a nonâinvasive sampling tool to determine the freshwater distribution of these fishes in Europe, enhancing their conservation at local and regional scales
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