Further studies on the chordal-hop theory of ionospheric long-range propagation

Summary This paper presents new results of the author's investigations on ionospheric propagation in Australia from 1952 to 1957. Considerations on path attenuation are followed by a discussion on the propagation paths to North America and Western Europe. Conclusions are in agreement with the author's previous publications in this field.

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Zusammenfassung In dieser Arbeit behandelt der Verfasser neue Ergebnisse seiner Untersuchungen über ionosphärische Ausbreitung in Australien von 1952 bis 1957. Auf eine Betrachtung über die Signalschwächung folgt eine Diskussion über die Ausbreitungswege nach Nordamerika und Westeuropa. Die Folgerungen stimmen mit den früheren Veröffentlichungen des Verfassers auf diesem Gebiet überein.

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Résumé L'auteur expose les nouveaux résultats de ses recherches sur la propagation ionosphérique en Australie de 1952 à 1957; il considère l'affaiblissement de la propagation des signaux et les chemins suivis par les ondes vers l'Amérique du Nord et vers l'Europe occidentale. Ces résultats concordent avec ceux qu'il a publiés précédemment.

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With 1 Figure     

Length‐mass models for some common New Zealand littoral‐benthic macroinvertebrates,with a note on within‐taxon variability in parameter values among published models

Regression models are developed and presented to predict dry mass (mg) from two linear dimensions (mm) for 17 benthic macroinvertebrate taxa common to littoral zones of New Zealand lakes. We also provide regression models to predict body length from head capsule width for the major insect taxa. Dry mass was best explained as a power function of all linear dimensions: M = aL _b .Parameters are presented in the log₁₀‐transformed linear form of this power function. Body length was a simple linear function of head capsule width for all insect taxa, hence parameters for these models are presented as untransformed values. We also provide family level models for the Chironomidae, and compare our chironomid body length‐mass model with other published Chrionomidae length‐mass models. There was a very high degree of variability in parameter values among published length‐mass models for the family Chironomidae (mean coefficient of variation for mass at length = 148%). We discuss the potential causes and implications of this variability.     

Die Weiterentwicklung der Meßtechnik des Wassergehalts des Bodens auf thermischer Grundlage

Zusammenfassung Durch Untersuchungen vonJ. Bracht [3] und dem Verfasser wurde im Jahre 1940 festgestellt, daß die Wärmeleitfähigkeit des Bodens nicht bei allen Bodenarten eindeutig mit dem Wassergehalt zusammenhängt. Es wird eine Erklärung für diese Erscheinung durch die Verscjiedenheit der Wasserablagerung zwischen den Bodenpartikeln bei Wasseraufnahme und Wasserabgabe gegeben. Von allen Wärmekonstanten des Bodens ist nur die Wärmekapazität wahrscheinlich eindeutig abhängig von dem Wassergehalt des Bodens. Diese Größe kann am einfachsten als der Quotient aus der Wärmeleitfähigkeit und der Temperaturleitfähigkeit des Bodens bestimmt werden. Es mu\ also außer der Wärmeleitfähigkeit auch noch die Temperaturleitfähigkeit gemessen werden.In der vorliegenden Arbeit wird ein Verfahren zur Bestimmung dieser letzteren Größe beschrieben. Hierbei wird als Geber das Doppelthermometer benutzt, das zur Messung der Wärmeleitfähigkeit des Bodens vom Verfasser [2] beschrieben wurde. Von den beiden Thermometern dieses Doppelthermometers wird das eine in halbstündigen Intervallen je eine Viertelstunde lang geheizt. Gemessen wird dann außer dem Temperaturunterschied zwischen geheiztem und ungeheiztem Thermometer auch der Temperaturgang des ungeheizten Thermometers allein. Aus dem Temperaturunterschied zwischen beiden Thermometern wird in der üblichen Weise die Wärmeleitfähigkeit und aus der Amplitude des Temperaturganges und seiner Phasenverschiebung gegen die Heizung die Temperaturleitfähigkeit des Bodens berechnet.

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Summary Researches ofJ. Bracht [3] and of the present author have shown in 1940 that the thermal conductivity of the soil is not exactly coherent with the content of water in all kinds of soil. An explanation of this phenomenon is given by the difference of water deposit between the soil particles under conditions of imbilition and desiccation of water. Of all thermal constants of the soil solely the heat capacity probably is distinctly dependent on the water content of the soil. This value can be determined in the simplest manner as the quotient of thermal conductivity and thermal diffusivity of the soil. Beside thermal conductivity therefore thermal diffusivity must be measured too.A procedure for the determination of this last value is developed in this paper. The double thermometer which has been described by the author [2] for measuring the thermal conductivity is used as indicator. One of the two thermometers of this double thermometer is being heated during a quarter of an hour at intervals of half an hour. Beside the difference of temperature between heated and unheated thermometer the variation of temperature of the unheated thermometer itself is measured. Then the thermal conductivity is calculated in the usual manner from the difference of temperature between the two thermometers and the thermal diffusivity of the soil from the amplitude of the temperature variation and its shift of phase against heating.

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Résumé Des recherches deJ. Bracht [3] et de l'auteur en 1940 ont montré que la conductibilité calorifique de certains sols ne dépend pas uniquement de leur teneur en eau. On tente d'expliquer cette anomalie par le fait que l'eau s'insère différemment entre les particules du sol lors de l'imbibition et lors de la dessication. Parmi toutes les constantes calorifiques du sol, la capacité calorifique est probablement la seule qui soit en relation univoque avec la teneur en eau. Cette grandeur peut se définir le plus simplement par le quotient de la conductivité calorifique et de la transmission thermique du sol. Il faut donc mesurer séparément ces deux grandeurs.On décrit dans le présent mémoire un procédé permettant la mesure de la transmission thermique. On se sert comme indicateur du thermomètre double décrit par l'auteur [2] en vue de la mesure de la conductibilité du sol. L'un de ces thermomètres est chauffé pendant un quart d'heure toutes les demi-heures. On note alors non seulement la différence de température entre les deux instruments, mais encore les variations du thermomètre non chauffé: la différence de température permet comme d'ordinaire le calcul de la conductibilité, tandis que l'amplitude de la variation du thermomètre non chauffé et son décalage par rapport à l'autre permettent le calcul de la transmission thermique.

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Mit 4 Textabbildungen.     

Results from the Wide Angle Search for Planets Prototype (WASP0) – II. Stellar variability in the Pegasus field

Recent wide field photometric surveys, which target a specific field for long durations, are ideal for studying both long- and short-period stellar variability. Here, we report on 75 variable stars detected during the observations of a field in Pegasus using the Wide Angle Search for Planets Prototype (WASP0) instrument, 73 of which are new discoveries. The variables detected include 16 δ Scuti stars, 34 eclipsing binaries, 3 BY Draconis stars and 4 RR Lyraes. We estimate that the fraction of stars in the field brighter than   V ∼ 13.5  exhibiting variable behaviour with an amplitude greater than 0.6 per cent rms is ∼0.4 per cent. These results are compared with other wide field stellar variability surveys, and implications for detecting transits due to extra-solar planets are discussed.     

Cosmology from 3 years of WMAP CMB data

The combined 3 year observations from the Wilkinson Microwave Anisotropy Probe (WMAP) have yielded full-sky temperature and polarization maps in five frequency bands (K, Ka, Q, V, W) between 23 and 94 GHz. In this article we discuss the cosmological implications of these observations. The combination of temperature and polarization data leads to a significant improvement in the measurement of the reionization optical depth τ = 0.093 ± 0.029. This, in turn, breaks a number of key degeneracies present in the constraints from temperature measurements alone allowing the WMAP CMB data on its own to offer a powerful insight into the universe’s constituents and the processes that generated the initial conditions for structure formation.     

Near‐infrared spectra of clinopyroxenes: Effects of calcium content and crystal structure

Abstract– Pyroxenes are among the most common minerals in the solar system and are ideally suited for remote geochemical analysis because of the sensitivity of their distinctive spectra to mineral composition. Fe²⁺ is responsible for the dominant pyroxene absorptions in the visible and near‐infrared, but substitutions of other cations such as Ca²⁺ change the crystal structure and site geometries and thus the crystal field splitting energies of the Fe cations. To define spectral systematics resulting from major pyroxene cations (Ca²⁺, Mg²⁺, and Fe²⁺), we focus on a suite of pyroxenes synthesized with only Ca²⁺, Mg²⁺, and Fe²⁺ in the two octahedral sites, specifically examining the effect of Ca²⁺ on pyroxene absorption bands. The modified Gaussian model is used to deconvolve pyroxene spectra into component bands that can then be linked directly to crystal field absorptions. In orthopyroxenes and low‐Ca clinopyroxenes, Ca²⁺‐content has a strong and predictable effect on the positions of the absorption bands. At a threshold of Wo₃₀, the crystal field environment stagnates and the M2 bands cease to change significantly as more Ca²⁺ is added. At Wo₅₀, when most of the M2 sites are filled by Ca²⁺, band positions do not change drastically, although the presence and strengths of the 1 and 2 μm bands are affected by even trace amounts of Fe²⁺ in the M2 site. It is thus apparent that next‐nearest neighbors and the distortions they impose on the pyroxene lattice affect the electronic states around the Fe²⁺ cations and control absorption band properties.     

Halo masses for optically selected and for radio-loud AGN from clustering and galaxy–galaxy lensing

We compute two-point correlation functions and measure the shear signal due to galaxy–galaxy lensing for 80 000 optically identified and 5700 radio-loud active galactic nuclei (AGN) from Data Release 4 of the Sloan Digital Sky Survey. Halo occupation models are used to estimate halo masses and satellite fractions for these two types of AGN. The large sample size allows us to separate AGN according to the stellar mass of their host galaxies. We study how the halo masses of optical and radio AGN differ from those of the parent population at fixed   M _*  . Halo masses deduced from clustering and from lensing agree satisfactorily. Radio AGN are found in more massive haloes than optical AGN: in our samples, their mean halo masses are  1.6 × 10¹³  and  8 × 10¹¹  h ⁻¹ M_⊙  , respectively. Optical AGN follow the same relation between stellar mass and halo mass as galaxies selected without regard to nuclear properties, but radio-loud AGN deviate significantly from this relation. The dark matter haloes of radio-loud AGN are about twice as massive as those of control galaxies of the same stellar mass. This boost is independent of radio luminosity, and persists even when our analysis is restricted to field galaxies. The large-scale gaseous environment of the galaxy clearly plays a crucial role in producing observable radio emission. The dark matter halo masses that we derive for the AGN in our two samples are in good agreement with recent models in which feedback from radio AGN becomes dominant in haloes where gas cools quasi-statically.