Anthropogenic Space Weather

Anthropogenic effects on the space environment started in the late 19th century and reached their peak in the 1960s when high-altitude nuclear explosions were carried out by the USA and the Soviet Union. These explosions created artificial radiation belts near Earth that resulted in major damages to several satellites. Another, unexpected impact of the high-altitude nuclear tests was the electromagnetic pulse (EMP) that can have devastating effects over a large geographic area (as large as the continental United States). Other anthropogenic impacts on the space environment include chemical release ex- periments, high-frequency wave heating of the ionosphere and the interaction of VLF waves with the radiation belts. This paper reviews the fundamental physical process behind these phenomena and discusses the observations of their impacts.Comment: 71 pages, 35 figure

Advances in prevention and therapy of neonatal dairy calf diarrhoea : a systematical review with emphasis on colostrum management and fluid therapy

Neonatal calf diarrhoea remains the most common cause of morbidity and mortality in preweaned dairy calves worldwide. This complex disease can be triggered by both infectious and non-infectious causes. The four most important enteropathogens leading to neonatal dairy calf diarrhoea are Escherichia coli, rota-and coronavirus, and Cryptosporidium parvum. Besides treating diarrhoeic neonatal dairy calves, the veterinarian is the most obvious person to advise the dairy farmer on prevention and treatment of this disease. This review deals with prevention and treatment of neonatal dairy calf diarrhoea focusing on the importance of a good colostrum management and a correct fluid therapy

Effects of continuous milking during a field trial on productivity, milk protein yield and health in dairy cows

The objective of this field study with an automatic milking system was to evaluate the effects of omitting the dry period on health and productivity during the subsequent lactation in dairy cows. A total of 98 German Simmental cows of six Southern German farms were assigned randomly to two experimental groups: The first group was dried-off 56 days before calving (D for dried-off, n=49), and the second group was milked continuously during this period until calving (CM for continuous milking, n=49). From the latter a third group emerged, including cows that dried-off themselves spontaneously (DS for dried-off spontaneously, n=14). Blood serum values of glucose, β-hydroxybutyrate (BHBA), non-esterified fatty acids (NEFA) and IGF-1 showed most pronounced fluctuations in D cows. Over the entire study period, the concentrations of BHBA and NEFA were markedly lower in the CM and DS groups. Furthermore, IGF-1 concentration was lowest for D cows and also decrease in back fat thickness was more pronounced. Mean concentration of milk protein was markedly higher in CM and DS cows (3.70% and 3.71%) compared with D cows (3.38%). Owing to the lower 305-day milk yield (−15.6%) and the lower total milk yield (−3.1%), the total amount of produced protein in the subsequent lactation was 2.5% (6.8 kg) lower, although the additional protein amount in CM cows from week −8 to calving was 35.7 kg. The greatest benefit resulted from positive effects on fertility and the lower incidence of diseases: CM cows had their first oestrus 1 week earlier compared with D cows, they also conceived earlier and showed a significantly lower risk of developing hypocalcaemia, ketosis and puerperal disorders. The present study showed that the costs of medical treatment and milk losses were twice as high in D cows, compared with CM and DS cows, and thus the reduced costs because of the more stable health outweighed the financial losses of milk yield by +18.49 € per cow and lactation

Grating Outcoupling From Large Area Rib Waveguide Arrays Fabricated on Titanium Indiffused Lithium Niobate Substrates

The Integrated Optical Synthetic Aperture Radar (IOSAR) Processor [1] is one of a number of potentially powerful optical signal processing components that combine many of the throughput characteristics of bulk optical processors with the cost, size, and power advantages of guided wave optical devices. One of several novel features of the IOSAR processor is the capability of performing an inherently two dimensional image formation function in an integrated optical configuration by a combination of spatial and temporal integration. This can be accomplished as shown schematically in Fig. 1. The radar return (a linear FM chirp) is input to the processor by means of a surface acoustic wave transducer. Coherent light from a pulsed laser diode is collimated by lens L1 and focused on an array of rib waveguides by lens L2 (a spatial integration). The large area waveguide array performs an image dissection in the range dimension. Light propagating in a given rib waveguide (a given range bin) is then selectively outcoupled through a mask encoded with the azimuth doppler history onto a two dimensional CCD detector operated in the shift-and-add mode. Sequential radar returns are then integrated with appropriate shifts (a temporal integration) to perform the required azimuth compression.</jats:p

Arrays of focused beams generated by the integration of Fresnel microlenses with vertical cavity surface-emitting laser arrays

The advent of vertical cavity surface emitting laser arrays (VC-SELAs) creates new possibilities of integration and miniaturization in a host of optical information processing and interconnection applications.1,2 Beams of individual lasers in a VC-SELA exit through the substrate while diverging due to diffraction causing beam overlap after short distances. Here, we present results of integrating an easy to fabricate binary phase Fresnel microlens array (BP-FMA) on the substrate of a VC-SELA to focus individual beams making them suitable for above applications. A VC-SELA with 10 m aperture laser on 100 m pitch was first fabricated detail of which is given elsewhere.2 By the selective ion beam milling of the substrate, the BP- FMA pattern was fabricated in the exit interface. The generated step height was 0.19 m (to induce 180 phase shift between neighboring zones of Fresnel microlenses). Each microlens in the array has an aperture of 80 m situated 100 m apart. In one case, we used such microlenses to reduce the beam divergence of 10 m aperture lasers (situated 200 m away) from 11 (diffraction without the lens) to 4 (with the lens). In this paper, we will present the quality of beams generated in addition to the diffraction and the throughput efficiencies of the fabricated microlenses. The effect of back reflection on the performance of laser resonators will also be examined.</jats:p

Arrays of Focused Beams Generated by the Integration of Fresnel Microlenses with Vertical Cavity Surface-Emitting Laser Arrays

Availability of two-dimensional source arrays with focused (or collimated) beams is essential for a host of optical information processing, interconnection and communication applications. The advent of vertical cavity surface emitting laser arrays (VC-SELAs)[1,2], for example, creates new possibilities of integration and miniaturization in above applications. In addition, the trend in making such laser arrays matrix addressable could eliminate the need for external amplitude spatial light modulators (SLMs)[3]. In order to make the beams from VC-SELAs suitable for applications such as interconnection, however, their output beams need to be focused (or collimated) (which would otherwise be diverging due to diffraction). Here, we present results of integrating easy to fabricate Fresnel microlens arrays (FMAs) with VC-SELAs by patterning the former on the laser substrate. We used such lenses to collimate beams of individual lasers.(We note that collimation is a case of focusing.)</jats:p