A fine-grained analysis of a Monk parakeet (Myiopsitta monachus) nest suggests a nonhomogeneous internal structure

We report first data on the fine-grained structure (branch diameter, length and diversity) in three different sectors [core (central side), buffer (peripheral side), and nest chamber)] of a nest of Monk Parakeets (Myiopsitta monachus) from a non-native breeding site located in an urban park (Rome, central Italy). The central core sector was characterized by longer and thicker branches capable of supporting the nest. The peripheral part (buffer) was characterized by less long and less thick branches with the function of completing the structure. Branches building the nest chamber were shorter and less thick but very diversified in size, because they included both small branches supplied inside the chamber and longer branches covering it. This diversification of the internal chamber (nest chamber) could be functional to maintain stable temperatures of incubator chambers compared to large fluctuations outside the nest. The presence of leaves of herbaceous species (Hordeum leporinum) could play a bactericidal role for the nest plant material.

Ocean Energy Systems Wave Energy Modeling Task 10.4: Numerical Modeling of a Fixed Oscillating Water Column

This paper reports on an ongoing international effort to establish guidelines for numerical modeling of wave energy converters, initiated by the International Energy Agency Technology Collaboration Program for Ocean Energy Systems. Initial results for point absorbers were presented in previous work, and here we present results for a breakwater-mounted Oscillating Water Column (OWC) device. The experimental model is at scale 1:4 relative to a full-scale installation in a water depth of 12.8 m. The power-extracting air turbine is modeled by an orifice plate of 1–2% of the internal chamber surface area. Measurements of chamber surface elevation, air flow through the orifice, and pressure difference across the orifice are compared with numerical calculations using both weakly-nonlinear potential flow theory and computational fluid dynamics. Both compressible- and incompressible-flow models are considered, and the effects of air compressibility are found to have a significant influence on the motion of the internal chamber surface. Recommendations are made for reducing uncertainties in future experimental campaigns, which are critical to enable firm conclusions to be drawn about the relative accuracy of the numerical models. It is well-known that boundary element method solutions of the linear potential flow problem (e.g., WAMIT) are singular at infinite frequency when panels are placed directly on the free surface. This is problematic for time-domain solutions where the value of the added mass matrix at infinite frequency is critical, especially for OWC chambers, which are modeled by zero-mass elements on the free surface. A straightforward rational procedure is described to replace ad-hoc solutions to this problem that have been proposed in the literature.

Comparisons of Respiratory Pupal Gill Development in Black Flies (Diptera: Simuliidae) Shed Light on the Origin of Dipteran Prothoracic Dorsal Appendages

During the transformation of immature aquatic dipteran insects to terrestrial adults, the prothoracic pupal respiratory organ enables pupae to cope with flood-drought alternating environments. Despite its obvious importance, the biology of the organ, including its development, is poorly understood. In this study, the developing gills of several Simulium Latreille (Diptera: Simuliidae) spp. were observed using serial histological sections and compared with data on those of other dipteran families published previously. The formation of some enigmatic features that made the Simulium gill unique is detailed. Through comparisons between taxa, we describe a common developmental pattern in which the prothoracic dorsal disc cells not only morph into the protruding respiratory organ, which is partially or entirely covered with a cuticle layer of plastron, but also invaginate to form a multipart internal chamber that in part gives rise to the anterior spiracle of adult flies. The gill disc resembles wing and leg discs and undergoes cell proliferation, axial outgrowth, and cuticle sheath formation. The overall appendage-like characteristics of the dipteran pupal respiratory organ suggest an ancestral form that gave rise to its current forms, which added more dimensions to the ways that arthropods evolved through appendage adaptation. Our observations provide important background from which further studies into the evolution of the respiratory organ across Diptera can be carried out.

Corrosivity Evaluation of Copper-Nickel Alloy (90/10) in Pumps Used in Offshore Platforms for Seawater Pumping

This work discusses the case of corrosion in a copper-nickel alloy used in seawater, where chlorination is necessary to control micro- and macro-organism growth that can render inoperable the seawater supply system used in an offshore platform. Studies developed in the last 30 years have shown copper-nickel’s adequateness in seawater, with a corrosion rate of about 0.001mm/year. However, annual equipment inspection showed localized corrosion in an internal chamber in a stand-by pump. Such corrosion occurred due to high-concentration of sodium hypochlorite (NaClO) injection into the operational system, even for pumps that were out of operation. To evaluate this corrosive process, gravimetric (mass loss) and electrochemical tests were developed in synthetic seawater with NaClO at concentrations of 100, 500, 1000 and 5000mg/L. The results indicated that the corrosiveness varied from low to moderate. The presence of pitting and crevices observed in the laboratory tests derails or compromises material use in seawater. It was concluded that there is a need for continuous monitoring of the NaClO injection in seawater pumps, and a method was proposed in order to minimize or avoid a high concentration of chlorine in standby pumps.

A New Strategy Against Peri-Implantitis: Antibacterial Internal Coating

The bacterial biofilm formation in the oral cavity and the microbial activity around the implant tissue represent a potential factor on the interface between bone and implant fixture that could induce an inflammatory phenomenon and generate an increased risk for mucositis and peri-implantitis. The aim of the present clinical trial was to investigate the bacterial quality of a new antibacterial coating of the internal chamber of the implant in vivo at six months. The PIXIT implant (Edierre srl, Genova Italy) is prepared by coating the implant with an alcoholic solution containing polysiloxane oligomers and chlorhexidine gluconate at 1%. A total of 15 healthy patients (60 implants) with non-contributory past medical history (nine women and six men, all non-smokers, mean age of 53 years, ranging from 45–61 years) were scheduled to receive bilateral fixed prostheses or crown restorations supported by an implant fixture. No adverse effects and no implant failure were reported at four months. All experimental sites showed a good soft tissue healing at the experimental point times and no local evidence of inflammation was observed. Real-Time Polymerase Chain Reaction (PCR) analysis on coated and uncoated implants showed a decrease of the bacterial count in the internal part of the implant chamber. The mean of total bacteria loading (TBL) detected in each PCR reaction was lower in treated implants (81038 units/reaction) compared to untreated implants (90057 units/reaction) (p < 0.01). The polymeric chlorhexydine coating of the internal chamber of the implant showed the ability to control the bacterial loading at the level of the peri-implant tissue. Moreover, the investigation demonstrated that the coating is able to influence also the quality of the microbiota, in particular on the species involved in the pathogenesis of peri-implantitis that are involved with a higher risk of long-term failure of the dental implant restoration.

The Influence of Cylindrical Spray Chamber Geometry on the Evolution of High Pressure Diesel Sprays

While much is known on the effect of combustion chamber geometry on spray evolution in engines, less is known about its role in laboratory combustion chambers. This paper reports on a study, which investigates the effect of internal chamber geometry on the penetration and spreading angle of common rail nonreacting diesel sprays at room temperature conditions in a cylindrical constant volume chamber. This chamber has dimensions similar to those used in the literature. Spray chamber geometry was modified to yield three different chamber height-to-diameter ratios and two different nozzle stand-off distances. Sprays from three nozzles, two single-hole nozzles with different diameter and one twin-hole nozzle (THN), were examined for two injection pressures of 100 MPa and 150 MPa into two chamber pressures of 0.1 MPa and 5 MPa. To characterize the spray structure, a volume illumination method was used to study the spray tip penetration/speed and spread angle. For both injection pressures used with chamber pressure of 5 MPa, little sensitivity to vessel geometry was found in penetration distance and tip speed for variation in height to diameter ratio from 0.6 to 2.6 and variation in nozzle stand-off distance from 2 mm to 54 mm. For atmospheric chamber pressure, sensitivity to chamber geometry was evident and found to vary with nozzle type. Spread angle was found more largely affected by the calculation method and very sensitive to the image intensity threshold value for the cases investigated.

Mechanisms of opening and closing of the bacterial replicative helicase

Assembly of bacterial ring-shaped hexameric replicative helicases on single-stranded (ss) DNA requires specialized loading factors. However, mechanisms implemented by these factors during opening and closing of the helicase, which enable and restrict access to an internal chamber, are not known. Here, we investigate these mechanisms in the Escherichia coli DnaB helicase•bacteriophage λ helicase loader (λP) complex. We show that five copies of λP bind at DnaB subunit interfaces and reconfigure the helicase into an open spiral conformation that is intermediate to previously observed closed ring and closed spiral forms; reconfiguration also produces openings large enough to admit ssDNA into the inner chamber. The helicase is also observed in a restrained inactive configuration that poises it to close on activating signal, and transition to the translocation state. Our findings provide insights into helicase opening, delivery to the origin and ssDNA entry, and closing in preparation for translocation.

Insect galls on Myrtaceae: richness and distribution in brazilian restingas

Inventories in Brazilian restingas have been indicating that Myrtaceae are the plant family with the greatest richness of insect galls. A compilation of published data plus new records was elaborated with the aim of stablishing the number of gall morphotypes on this family in this physiognomy of the Atlantic Forest, producing a list of galled species, pointing out the predominant gall features, evaluating the taxonomical knowledge of the gallers, listing the associated fauna, and based on host plant endemisms and monophagy proposing the endemism of some galling species. Myrtaceae harbor 111 morphotypes of insect gall (about 75% induced by Cecidomyiidae, Diptera) on 25 host plant species, 15 endemic. Eugenia L. highlights as the plant genus with the highest number of galled species and gall richness. Leaves are the most galled organ. There is a predominance of globoid and fusiform shapes, green color, glabrous surface and a single internal chamber. The taxonomical data on gallers is deficient as many records have been presented at supraspecific levels. The associated fauna is rich and includes parasitoids, inquilines and predators. Twelve species of Cecidomyiidae, a single species of Curculionidae (Coleoptera) and one species of Eriococcidae (Hemiptera) have been associated exclusively with endemic hosts and then are proposed in the present study as endemic too. The geographical distribution of many galls and respective gallers are restricted to the State of Rio de Janeiro, where most inventories have been carried out. For the first time, Eugeniamyia dispar, previously known from a rural area of Rio Grande do Sul and restinga areas of São Paulo, is recorded in the State of Rio de Janeiro.