Validation of the radiation pattern of the VHF MST radar MAARSY by scattering off a sounding rocket's payload

The Middle Atmosphere Alomar Radar System (MAARSY) is a monostatic radar with an active phased array antenna designed for studies of phenomena in the mesosphere and lower thermosphere. Its design, in particular the flexible beam forming and steering capability, makes it a powerful instrument to perform observations with high angular and temporal resolution. For the configuration and analysis of experiments carried out with the radar it is essential to have knowledge of the actual radiation pattern. Therefore, during the time since the radar was put into operation various active and passive experiments have been performed to gain knowledge of the radiation pattern. With these experiments the beam pointing accuracy, the beam width and phase distribution of the antenna array were investigated. Here, the use of a sounding rocket and its payload as a radar target is described which was launched in the proximity of the radar. The analysis of these observations allows the detailed investigation of the two-way radiation pattern for different antenna array sizes and beam pointing positions

The Geminid meteor shower during the ECOMA sounding rocket campaign: specular and head echo radar observations

The ECOMA (Existence of Charge state Of meteoric smoke particles in the Middle Atmosphere) sounding rocket campaign was conducted during the Geminid meteor shower in December 2010 in order to explore whether there is a change of the properties of meteoric smoke particles due to the stream. In parallel to the rocket flights, three radars monitored the Geminid activity located at the launch site in Northern Norway and in Northern Germany to gain information about the meteor flux into the atmosphere. The results presented here are based on specular meteor radar observations measuring the radiant position, the velocity and the meteor flux into the atmosphere during the Geminids. Further, the MAARSY (Middle Atmosphere Alomar Radar System) radar was operated to conduct meteor head echo experiments. The interferometric capabilities of MAARSY permit measuring the meteor trajectories within the radar beam and to determine the source radiant and geocentric meteor velocity, as well as to compute the meteor orbit

Drainage Needs and Returns in North-Central Iowa

Current status of drainage and estimated drainage needs of the soils in the Des Moines River basin as indicated from an extensive survey are presented. A high percentage of the area has the potential for receiving benefits by improving county mains and on-the-farm drainage. Analyses have been made of the economic potential for drainage improvements by comparing three drainage input levels. Benefit-cost ratios indicate drainage of very poorly drained and poorly drained soils is a good investment for corn and soybean production

A Parallelized Bayesian Approach To Accelerated Gravitational-Wave Background Characterization

The characterization of nanohertz-frequency gravitational waves (GWs) with pulsar-timing arrays requires a continual expansion of datasets and monitored pulsars. Whereas detection of the stochastic GW background is predicated on measuring a distinctive pattern of inter-pulsar correlations, characterizing the background's spectrum is driven by information encoded in the power spectra of the individual pulsars' time series. We propose a new technique for rapid Bayesian characterization of the stochastic GW background that is fully parallelized over pulsar datasets. This Factorized Likelihood (FL) technique empowers a modular approach to parameter estimation of the GW background, multi-stage model selection of a spectrally-common stochastic process and quadrupolar inter-pulsar correlations, and statistical cross-validation of measured signals between independent pulsar sub-arrays. We demonstrate the equivalence of this technique's efficacy with the full pulsar-timing array likelihood, yet at a fraction of the required time. Our technique is fast, easily implemented, and trivially allows for new data and pulsars to be combined with legacy datasets without re-analysis of the latter.Comment: 14 pages, 6 figures. Matches version accepted by PR

Reliability and validity of PIRLS and TIMSS: does the response format matter?

Academic achievements are often assessed in written exams and tests using selection-type (e.g., multiple-choice; MC) and supply-type (e.g., constructed-response; CR) item response formats. The present article examines how MC items and CR items differ with regard to reliability and criterion validity in two educational large-scale assessments with fourth-graders. The reading items of PIRLS 2006 were compiled into MC scales, CR scales, and mixed scales. Scale reliabilities were estimated according to item response theory (international PIRLS sample; n = 119,413). MC showed smaller standard errors than CR around the reading proficiency mean, whereas CR was more reliable for low and high proficiency levels. In the German sample (n = 7,581), there was no format-specific differential validity (criterion: German grades, r ˜ .5; ?r = 0.01). The mathematics items of TIMSS 2007 (n = 160,922) showed similar reliability patterns. MC validity was slightly larger than CR validity (criterion: mathematics grades; n = 5,111; r ˜ .5, ?r = –0.02). Effects of format-specific test-extensions were very small in both studies. It seems that in PIRLS and TIMSS, reliability and validity do not depend substantially on response formats. Consequently, other response format characteristics (like the cost of development, administration, and scoring) should be considered when choosing between MC and CR.This research was prepared with the support of the German funds “Bund-Länder-Programm für bessere Studienbedingungen und mehr Qualität in der Lehre (‘Qualitätspakt Lehre’)” [the joint program of the Federal and States Government for better study conditions and the quality of teaching in higher education (“the Teaching Quality Pact”)] at Saarland University (funding code: 01PL11012). The authors developed the topic and the content of this manuscript independently from this funding. We thank the Institute for School Development Research (IFS) at Technical University Dortmund / the Max Planck Institute for Human Development (MPIB) Berlin / the Standing Conference of the Ministers of Education and Cultural Affairs (KMK) as well as the Research Data Centre (FDZ) at the Institute for Educational Quality Improvement (IQB) for providing the raw data

Regular networks of Luttinger liquids

We consider arrays of Luttinger liquids, where each node is described by a unitary scattering matrix. In the limit of small electron-electron interaction, we study the evolution of these scattering matrices as the high-energy single particle states are gradually integrated out. Interestingly, we obtain the same renormalization group equations as those derived by Lal, Rao, and Sen, for a system composed of a single node coupled to several semi-infinite 1D wires. The main difference between the single node geometry and a regular lattice is that in the latter case, the single particle spectrum is organized into periodic energy bands, so that the renormalization procedure has to stop when the last totally occupied band has been eliminated. We therefore predict a strongly renormalized Luttinger liquid behavior for generic filling factors, which should exhibit power-law suppression of the conductivity at low temperatures E_{F}/(k_{F}a) > 1. Some fully insulating ground-states are expected only for a discrete set of integer filling factors for the electronic system. A detailed discussion of the scattering matrix flow and its implication for the low energy band structure is given on the example of a square lattice.Comment: 16 pages, 7 figure

Caracterização morfofisiológica e patogênica de isolados de Sphaeropsis sapinea e avaliação de resistência em Pinus radiata.

Resumo

Observation of Kelvin–Helmholtz instabilities and gravity waves in the summer mesopause above Andenes in Northern Norway

We present observations obtained with the Middle Atmosphere Alomar Radar System (MAARSY) to investigate short-period wave-like features using polar mesospheric summer echoes (PMSEs) as a tracer for the neutral dynamics. We conducted a multibeam experiment including 67 different beam directions during a 9-day campaign in June 2013. We identified two Kelvin–Helmholtz instability (KHI) events from the signal morphology of PMSE. The MAARSY observations are complemented by collocated meteor radar wind data to determine the mesoscale gravity wave activity and the vertical structure of the wind field above the PMSE. The KHIs occurred in a strong shear flow with Richardson numbers Ri <0.25. In addition, we observed 15 wave-like events in our MAARSY multibeam observations applying a sophisticated decomposition of the radial velocity measurements using volume velocity processing. We retrieved the horizontal wavelength, intrinsic frequency, propagation direction, and phase speed from the horizontally resolved wind variability for 15 events. These events showed horizontal wavelengths between 20 and 40km, vertical wavelengths between 5 and 10km, and rather high intrinsic phase speeds between 45 and 85ms−1 with intrinsic periods of 5–10min

Emergence of a confined state in a weakly bent wire

In this paper we use a simple straightforward technique to investigate the emergence of a bound state in a weakly bent wire. We show that the bend behaves like an infinitely shallow potential well, and in the limit of small bending angle and low energy the bend can be presented by a simple 1D delta function potential.Comment: 4 pages, 3 Postscript figures (uses Revtex); added references and rewritte