1. Patterns in abundance and distribution of larval fish in a heavily regulated and a mildly regulated Australian lowland river were compared over four breeding seasons to gain some insight into how ...river regulation affects fish populations.
2. Larvae from a total of 13 species from nine families were recorded from the two rivers. The mildly regulated Broken River supported twice as many species as the heavily regulated Campaspe River. The two rivers shared three introduced species but only two native species. The dominant species in the Campaspe was not found in the Broken River.
3. The two most abundant species in the Campaspe were classified as `opportunists'. They are small, short‐lived species, which spawn for up to 9 months, encompassing extremes in temperature and flow. The extended spawning period may place a subset of larvae in optimal conditions for recruitment and is hypothesised as being the key to the success of these species.
4. Most species spawned each year, despite large interannual variation in flow and temperature conditions. Poor recruitment over several decades, rather than a failure to spawn, is considered the most likely explanation for differences in the larval fish faunas between the two rivers.
5. The highly regulated section of the Campaspe River downstream of the regulating impoundment is thought to provide suboptimal habitat conditions for larvae relative to the less regulated downstream sections.
6. The timing of occurrence of larvae of the dominant species varied by breeding season and may be the result of flexibility in the timing of spawning.
We present the first observation of self-amplified spontaneous emission (SASE) in a free-electron laser (FEL) in the vacuum ultraviolet regime at 109 nm wavelength (11 eV). The observed free-electron ...laser gain (approximately 3000) and the radiation characteristics, such as dependency on bunch charge, angular distribution, spectral width, and intensity fluctuations, are all consistent with the present models for SASE FELs.
The Laser Interferometer Space Antenna project (LISA) is a co-operative program between ESA and NASA to detect gravitational waves by measuring distortions in the space–time fabric. LISA Pathfinder ...is the precursor mission to LISA designed to validate the core technologies intended for LISA. One of the enabling technologies is the micro-propulsion system based on field emission thrusters necessary to achieve the uniquely stringent propulsion requirements.
A consortium consisting of Astrium GmbH and the University of Applied Sciences Wiener Neustadt (formerly AIT) was commissioned by ESA to develop and qualify the micro-propulsion system based on the Indium Needle FEEP technology. Several successful tests have verified the proper Needle Field Emission Electric Propulsion (FEEP) operation and the thermal and mechanical design of subcomponents of the developed system. For all functional tests, the flight representative Power Control Unit developed by SELEX Galileo S.p.A (also responsible for the Micro-Propulsion Subsystem (MPS) development) was used. Measurements have shown the exceptional stability of the thruster. An acceptance test of one Thruster Cluster Assembly (TCA) over 3600
h has shown the stable long term operation of the developed system. During the acceptance test compliance to all the applicable requirements have been shown such as a thrust resolution of 0.1
μN, thrust range capability between 0 and 100
μN, thrust overshoot much lower than the required 0.3
μN+3% and many others. In particular important is the voltage stability of the thruster (±1% over the duration of the testing) and the confirmation of the very low thrust noise. Based on the acceptance test the lifetime of the thruster is expected to exceed 39,000
h generating a total impulse bit of 6300
Ns at an average thrust level of 50
μN. A flight representative qualification model of the Needle FEEP Cluster Assembly (DM1) equipped with one active TCA has performed a qualification program consisting of acceptance, vibration, shock, and thermal vacuum test. During the last test, the thermal vacuum test (TVT), a performance decrease was observed. According to a preliminary analysis, this performance decrease is not linked to the thermal conditions simulated in the TVT but might be rather linked to secondary effects of the TVT set-up.
► LISA is a co-operative program of ESA & NASA detecting gravitational waves by distortion measurement in space–time fabric. ► Successful tests verified proper Needle FEEP operation and thermal and mechanical subcomponent design of the developed system. ► Acceptance test of a Thruster Cluster Assembly (TCA) over 3600
h showed stable long term operation of the developed system. ► Preliminary analysis show performance decrease is linked to the secondary effects of TVT set-up.
Start-to-end simulation of a Thomson source for mammography Oliva, P.; Bacci, A.; Bottigli, U. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
03/2010, Letnik:
615, Številka:
1
Journal Article
Recenzirano
Thomson scattering X-ray sources have many features which are of relevance for several applications: the main one is the capability to produce intense, quasi-monochromatic, tunable X-ray beams, after ...collimation, still with a reasonably small size apparatus. Applications to medical physics are straightforward, in particular in mammography where dose control in screening programs is the main relevant issue. An optimal choice of the X-ray energy to image the breast will result in a best image quality and hence will lead to a dose reduction.
A Thomson scattering source is presently under development at the Frascati National Laboratories (LNF) of INFN (Istituto Nazionale di Fisica Nucleare).
A complete simulation of the source including electron beam, laser beam, Thomson interaction and X-ray imaging is presented. The X-rays are generated in the energy range suitable for mammography and used to generate images of a mammographic phantom.
Image quality is evaluated in terms of dose efficiency and compared to those obtained by monochromatic beams and conventional X-ray tubes.
The aim of this work is to assess the morphological characteristics and parameters of biomass production, such as fresh and dry matter weight (FMW and DMW, g/plant), yield of dry matter (YDM) in ...terms of ton/ha, essential oil content (EOC, mL/100 g) and yield of essential oils (YEO) expressed as L/ha of the following plants Salvia verbenaca, Salvia argentea, Salvia lavandulifolia, Salvia pratensis, Salvia sclarea, Salvia triloba and Salvia officinalis. Except for Salvia argentea (S2) all other species have adapted to the south Brazilian climate conditions, with morphological differences among the species evaluated. In terms of DMW and YDM, S. officinalis was found to be the most productive species with 445.83 g/plant and 11.14 ton/ha. The higher essential oil content and yield was observed for S. officinalis, affording 1.99 mL/100 g and 221.74 L/ha, respectively. Chemical characterisation of the essential oils obtained from hydrodistillation was performed through GC and GC/MSD analyses, which revealed for most of the species studied, α e β-thujone, camphor and 1,8-cineole as major compounds, apart from S. sclarea, for which linalool, linalyl acetate and α-terpineol were the major components.
In this manuscript we review the challenges of Compton backscattering sources in advancing photon beam performances in the 1 – 20 MeV energy range, underlining the design criteria bringing to maximum ...spectral luminosity and briefly describing the main achievements in conceiving and developing new devices (multi-bunch RF cavities and Laser recirculators) for the case of ELI-NP Gamma Beam System (ELI-NP-GBS).
Copper‑beryllium alloys are widely used to manufacture thermoplastics injection molds due to their high thermal conductivity. Even though these alloys admit precipitation hardening at temperatures ...between 250 and 400 °C, they still call for surface coatings to enhance their abrasion resistance. However, application of these coatings can generate over-aging under specific deposition temperature ranges. This phenomenon causes a loss of substrate mechanical properties, making some industrial applications unfeasible, for example: construction of core pins with high slenderness ratio, and cores and cavities injection mold with narrow closure regions. This work proposes a solution to increase abrasive wear resistance of copper‑beryllium alloy C17200 through an electroless nickel‑phosphorus (NiP) coating. Temperature used in heat treatment of the coating was lower than substrate aging temperature. In this work, the heat treatment was carried out at 200 °C for 24 h. Hardness of coating and substrate was evaluated by measuring the cross-sectional microhardness profile after heat treatment. Microstructure, chemical composition, and crystallinity of coating and substrate were characterized using scanning electron microscopy (SEM), glow discharge optical emission spectroscopy (GD-OES), and X-ray diffraction (XRD), respectively. Wear behavior of coating-substrate systems was evaluated by micro-abrasive wear tests optical profilometry and SEM. NiP coating combined with heat treatment increased the surface hardness from 340 HV for uncoated alloy to an average of 997 HV for coated and heat treated alloy while maintaining substrate hardness. The application of this coating reduced the wear coefficient in the order of 3.03 × 10−6 to 2.04 × 10−6 (mm3 N−1 m−1). All the conditions analyzed, showed a mixed micro-abrasive wear mechanism with rolling and grooving wear characteristics.
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•Electroless nickel-phosphorus (NiP) coating applied on CuBe alloy C17200.•Coating process temperature lower than copper‑beryllium alloy aging temperature.•Coating NiP combined with heat treatment reduce the wear coefficient.•Increased wear resistance of CuBe alloy without changing substrate properties.
RESUMO Objetivou-se a padronização de testes de exercício de alta e baixa intensidades em esteira, bem como a avaliação do eletrocardiograma de cães submetidos a esses testes. Para tal fim, sete cães ...da raça Australian Cattle Dog e quatro da raça Border Collie clinicamente saudáveis foram submetidos a dois testes de exercício em esteira, com pelo menos sete dias de intervalo: T1 - teste de exercício de alta intensidade e curta duração, e T2 - teste de exercício de baixa intensidade e longa duração. A amplitude e a duração de ondas e intervalos foram avaliadas no momento antes do exercício (M0) e nos momentos imediatamente após o término dos testes (MPE) e 30 minutos após (M30). A frequência e o ritmo cardíacos foram avaliados antes dos testes e continuamente por 30 minutos após o término do exercício. Verificou-se diferença significativa somente para a duração do intervalo QT em M30 em T1, além de algumas arritmias, como complexos atriais e ventriculares prematuros isolados em três animais após o teste T1, e em quatro após T2. Os testes de exercício foram adequados para promover estimulação simpática nos cães, contudo não causaram alterações significativas no eletrocardiograma, provavelmente em razão do excelente condicionamento físico dos animais.
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