In this paper, we present new results in the development of a broad-band spatial power-combining system implemented in a standard X-band waveguide environment. Using 24 off-the-shelf GaAs ...monolithic-microwave integrated-circuit (MMIC) power amplifiers integrated with tapered-slot antenna arrays, the new combining circuit produced up to 126-W maximum power output with a gain variation of /spl plusmn/1.9 dB within the band of interest (8-11 GHz). This hybrid circuit combiner is transparent to the device technology, and also provides an excellent heat-sinking capacity, sustaining as much as 415 W of dc power consumed by the MMIC amplifiers. The modular architecture allows easy maintenance, variable output power level, and modular assembly. Results on graceful degradation are also presented, showing superb tolerance to device failure.
This paper presents a broad-band spatial power-combining system based on tapered-slot antenna arrays integrated in a standard WR-90 waveguide environment. The system is designed using a modular tray ...architecture, providing full waveguide-band frequency coverage and an excellent thermal environment for a set of monolithic-microwave integrated-circuit (MMIC) amplifiers. The shape of the tapered-slot or finline structures was optimized to minimize return loss and provide a broad-band impedance transformation from the waveguide mode to the MMIC amplifiers. A prototype eight-element array using commercial GaAs MMIC power amplifiers yielded a maximum of 41 W output power (continuous wave) with a gain variation less than /spl plusmn/1.2 dB within the entire band of interest. The average combining efficiency over the operating band was estimated at 73%. The results suggest the efficacy of the design and a strong potential for higher powers by moving toward a greater number of MMIC's per tray and a larger number of trays. Should the 100 W system be realized in the near future, our combiner system will become a promising candidate to challenge the dominant position currently claimed by the traveling-wave tube amplifiers.
To determine whether the rate of psychiatric disorders increases in children and adolescents with IDDM.
The rate of psychiatric disorders was assessed by highly structured interviews in a group of 93 ...IDDM adolescents 17-19 yr of age and compared with a healthy (nondiabetic) age-, sex-, and socioeconomic status-matched control group.
The rate of psychiatric disorders was 33.3% in the diabetic group, more than threefold higher than in the control group (9.7%). With regard to the rate of psychiatric disorders, no sex-specific differences between the two groups were found. The diabetic adolescents suffered from significantly more introversive symptoms than their healthy counterparts, especially somatic symptoms, sleeping disturbances, compulsions, and depressive moods. In spite of the elevated rate of psychiatric disorders, the rates of life events and familial adversities did not increase in the diabetic group.
The results support the notion that IDDM adolescents should be seen as a high-risk group for psychiatric disorders.
The cosmic ray muon spectrum and charge ratio in CosmoALEPH Zimmermann, D; Grupen, C; Kotaidis, V ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
06/2004, Letnik:
525, Številka:
1
Journal Article
Recenzirano
Odprti dostop
The ALEPH experiment at the LEP e
+e
− storage ring at CERN has been used to measure the momentum spectrum of cosmic ray muons. ALEPH is located at a vertical depth of
320
m.w.e.
underground close to ...the Jura mountains. The high resolution of the time projection chamber (TPC) of ALEPH allows to reconstruct muon tracks with momenta up to the TeV region. The measured muon momentum spectrum and the charge ratio in the range from 80 to
2500
GeV
are presented. After corrections for energy loss in the overburden the sea level muon spectrum at nearly vertical incidence is obtained. The experimental data are compared to theoretical expectations and results from other experiments.
The ALEPH detector at LEP has been supplemented with five scintillator telescopes to measure the muon component of cosmic ray air showers underground. The emphasis of the present analysis of a new ...data set is to measure coincidences over distances up to about 1
km which are sensitive to the forward production of hadronic interactions and the chemical composition of primary cosmic rays in the energy range around 10
15
eV. First results indicate that the observed decoherence curve of muons is compatible with a light primary composition and the arrival directions of muons show no obvious clustering in galactic coordinates.
HERA-B data acquisition system Dam, M.; Egorytchev, V.; Essenov, S. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
06/2004, Letnik:
525, Številka:
3
Journal Article
Recenzirano
The HERA-B Data Acquisition System implements a
50
kHz
dead-timeless readout of
500
kB
events requiring unprecedented speed of storing and data processing. The system is based on Digital Signal ...Processors (DSP) minimizing the number of components. A high bandwidth, low-latency DSP switching network provides full connectivity between the readout buffers and a PC farm which runs the higher level trigger. The design of the system and the achieved performance are described in this paper.
In the last decades a significant number of so far unknown or underestimated pathogens have emerged as fundamental health hazards of the human population despite intensive research and exceptional ...efforts of modern medicine to embank and eradicate infectious diseases. Almost all incidents caused by such emerging pathogens could be ascribed to agents that are zoonotic or expanded their host range and crossed species barriers. Many different factors influence the status of a pathogen to remain unnoticed or evolves into a worldwide threat. The ability of an infectious agent to adapt to changing environmental conditions and variations in human behavior, population development, nutrition, education, social, and health status are relevant factors affecting the correlation between pathogen and host. Hantaviruses belong to the emerging pathogens having gained more and more attention in the last decades. These viruses are members of the family Bunyaviridae and are grouped into a separate genus known as Hantavirus. The serotypes Hantaan (HTN), Seoul (SEO), Puumala (PUU), and Dobrava (DOB) virus predominantly cause hemorrhagic fever with renal syndrome (HFRS), a disease characterized by renal failure, hemorrhages, and shock. In the recent past, many hantavirus isolates have been identified and classified in hitherto unaffected geographic regions in the New World (North, Middle, and South America) with characteristic features affecting the lungs of infected individuals and causing an acute pulmonary syndrome. Hantavirus outbreaks in the United States of America at the beginning of the 10th decade of the last century fundamentally changed our knowledge about the appearance of the hantavirus specific clinical picture, mortality, origin, and transmission route in human beings. The hantavirus pulmonary syndrome (HPS) was first recognized in 1993 in the Four Corners Region of the United States and had a lethality of more than 50%. Although the causative virus was first termed in connection with the geographic name of its outbreak region the analysis of the individual viruses indicate that the causing virus of HPS was a genetically distinct hantavirus and consequently termed as Sin Nombre virus. Hantaviruses are distributed worldwide and are assumed to share a long time period of co-evolution with specific rodent species as their natural reservoir. The degree of relatedness between virus serotypes normally coincides with the relatedness between their respective hosts. There are no known diseases that are associated with hantavirus infections in rodents underlining the amicable relationship between virus and host developed by mutual interaction in hundreds of thousands of years. Although rodents are the major reservoir, antibodies against hantaviruses are also present in domestic and wild animals like cats, dogs, pigs, cattle, and deer. Domestic animals and rodents live jointly in a similar habitat. Therefore the transmission of hantaviruses from rodents to domestic animals seems to be possible, if the target organs, tissues, and cell parenchyma of the co-habitat domestic animals possess adequate virus receptors and are suitable for hantavirus entry and replication. The most likely incidental infection of species other than rodents as for example humans turns hantaviruses from harmless to life-threatening pathogenic agents focusing the attention on this virus group, their ecology and evolution in order to prevent the human population from a serious health risk. Much more studies on the influence of non-natural hosts on the ecology of hantaviruses are needed to understand the directions that the hantavirus evolution could pursue. At least, domestic animals that share their environmental habitat with rodents and humans particularly in areas known as high endemic hantavirus regions have to be copiously screened. Each transfer of hantaviruses from their original natural hosts to other often incidental hosts is accompanied by a change of ecology, a change of environment, a modulation of numerous factors probably influencing the pathogenicity and virulence of the virus. The new environment exerts a modified evolutionary pressure on the virus forcing it to adapt and probably to adopt a form that is much more dangerous for other host species compared to the original one.
In this paper, we present our continued effort in the development of broadband spatial power combining systems implemented in a standard WR-90 waveguide environment. With sixteen commercial MMIC ...amplifiers integrated with tapered-slot antenna arrays, a new combining circuit renders a 61-watt maximum power output and a gain variation less than /spl plusmn/1.4 dB within the entire band of interest. Higher output power can be achieved by introducing more MMIC amplifiers but still maintaining the same circuit topology, thanks to the modular design of the spatial combiner.
Cosmic ray physics with the ALEPH detector Besier, H; Grupen, C; Kempa, J ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
11/2000, Letnik:
454, Številka:
1
Journal Article
Recenzirano
ALEPH is one of the four detectors at the Large Electron–Positron Collider (LEP) at a depth of about 320 m.w.e. Its hadron calorimeter and scintillator arrays installed at distances up to about 1 km ...away from ALEPH are used to measure cosmic muon induced time coincidences over large distances. The aim of this experiment (CosmoALEPH) is (1) to study the muon component above 70 GeV of Extensive Air Showers (EAS) and (2) to test the feasibility of searching for time correlations over even larger distances (up to 8 km) between the four LEP detectors. Layout and first results of CosmoALEPH are presented demonstrating the potential for cosmic ray physics in the LEP tunnel. The multiplicity distribution of muons in cosmic events recorded in ALEPH's tracking detector is presented.
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