PKS 1004+13: A High-Inclination, Highly-Absorbed Radio-Loud QSO -- The First Radio-Loud BAL QSO at Low Redshift?

The existence of BAL outflows in only radio-quiet QSOs was thought to be an important clue to mass ejection and the radio-loud - radio-quiet dichotomy. Recently a few radio-loud BAL QSOs have been discovered at high redshift. We present evidence that PKS 1004+13 is a radio-loud BAL QSO. It would be the first known at low-redshift (z = 0.24), and one of the most radio luminous. For PKS 1004+13, there appear to be broad absorption troughs of O VI, N V, Si IV, and C IV, indicating high-ionization outflows up to about 10,000 km/s. There are also two strong, broad (~500 km/s), high-ionization, associated absorption systems that show partial covering of the continuum source. The strong UV absorption we have detected suggests that the extreme soft-X-ray weakness of PKS 1004+13 is primarily the result of absorption. The large radio-lobe dominance indicates BAL and associated gas at high inclinations to the central engine axis, perhaps in a line-of-sight that passes through an accretion disk wind.Comment: To appear in Ap.J. Letters, 1999 (June or July); 4 pages, 5 figure

The Electron Glass in a Switchable Mirror: Relaxation, Aging and Universality

The rare earth hydride YH$_{3-\delta}$ can be tuned through the metal-insulator transition both by changing $\delta$ and by illumination with ultraviolet light. The transition is dominated by strong electron-electron interactions, with transport in the insulator sensitive to both a Coulomb gap and persistent quantum fluctuations. Via a systematic variation of UV illumination time, photon flux, Coulomb gap depth, and temperature, we demonstrate that polycrystalline YH$_{3-\delta}$ serves as a model system for studying the properties of the interacting electron glass. Prominent among its features are logarithmic relaxation, aging, and universal scaling of the conductivity

Methodological tests of the use of trace elements as tracers to assess root activity

peer-reviewedN.J.H. was funded by the Irish Research Council, co-funded by Marie Curie Actions under FP7. The field experiments A, B and G were supported by the European Community's Seventh Framework Programme (FP7/2007-2013) under the grant agreements FP7-266018 (AnimalChange) and FP7- 244983 (MultiSward). Experiment F was supported by the German Science Foundation (FOR 456).Background and aims There is increasing interest in how resource utilisation in grassland ecosystems is affected by changes in plant diversity and abiotic conditions. Research to date has mainly focussed on aboveground responses and there is limited insight into belowground processes. The aim of this study was to test a number of assumptions for the valid use of the trace elements caesium, lithium, rubidium and strontium as tracers to assess the root activity of several grassland species. Methods We carried out a series of experiments addressing the reliability of soil labelling, injection density, incubation time, application rate and the comparability of different tracers in a multiple tracer method. Results The results indicate that it is possible to achieve a reliable labelling of soil depths. Tracer injection density affected the variability but not the mean level of plant tracer concentrations. Tracer application rates should be based on pilot studies, because of site- and species-specific responses. The trace elements did not meet prerequisites to be used in a multiple tracer method. Conclusions The use of trace elements as tracers is potentially a very useful tool to give insight into plant root activity at different soil depths. This work highlights some of the main benefits and pitfalls of the method and provides specific recommendations to assist the design of tracer experiments and interpretation of the results.N.J.H. was funded by the Irish Research Council, co-funded by Marie Curie Actions under FP7. The field experiments A, B and G were supported by the European Community's Seventh Framework Programme (FP7/2007-2013) under the grant agreements FP7-266018 (AnimalChange) and FP7- 244983 (MultiSward). Experiment F was supported by the German Science Foundation (FOR 456).European Unio

Measuring the Reduced Shear

Neglecting the second order corrections in weak lensing measurements can lead to a few percent uncertainties on cosmic shears, and becomes more important for cluster lensing mass reconstructions. Existing methods which claim to measure the reduced shears are not necessarily accurate to the second order when a point spread function (PSF) is present. We show that the method of Zhang (2008) exactly measures the reduced shears at the second order level in the presence of PSF. A simple theorem is provided for further confirming our calculation, and for judging the accuracy of any shear measurement method at the second order based on its properties at the first order. The method of Zhang (2008) is well defined mathematically. It does not require assumptions on the morphologies of galaxies and the PSF. To reach a sub-percent level accuracy, the CCD pixel size is required to be not larger than 1/3 of the Full Width at Half Maximum (FWHM) of the PSF. Using a large ensemble (> 10^7) of mock galaxies of unrestricted morphologies, we find that contaminations to the shear signals from the noise of background photons can be removed in a well defined way because they are not correlated with the source shapes. The residual shear measurement errors due to background noise are consistent with zero at the sub-percent level even when the amplitude of such noise reaches about 1/10 of the source flux within the half-light radius of the source. This limit can in principle be extended further with a larger galaxy ensemble in our simulations. On the other hand, the source Poisson noise remains to be a cause of systematic errors. For a sub-percent level accuracy, our method requires the amplitude of the source Poisson noise to be less than 1/80 ~ 1/100 of the source flux within the half-light radius of the source, corresponding to collecting roughly 10^4 source photons.Comment: 18 pages, 3 figures, 4 tables, minor changes from the previous versio

Vrijloopstallen in winterse omstandigheden

Het succes van vrijloopstallen in Nederland hangt erg af van het klimaat. Vooral in koude en vochtige winters is het lastig om de bodem droog en schoon te houden. Studenten van Van Hall Larenstein beschrijven de ervaringen van vier pioniers in Nederland met een vrijloopstal

Rural-urban linkage in market oriented dairy development in Ethiopia: lessons from the Ada'a District

Addis Ababa, with an estimated human population of over 3 million, has a high demand for cereals, pulses, fresh vegetables, fruits, milk and milk products and meat and eggs. The Ada’a Woreda is one of the important areas that supply the well known ‘maja’ teff, chickpeas, fresh vegetables, eggs and chicken, meat and milk. The Woreda capital, Debre Zeit town, is only 45 km southeast of Addis Ababa and has a very good road and railway connection. The Ada’a Dairy Cooperative was established in 1998 in Debre Zeit based on its comparative market advantage, the conducive agro-ecological conditions for dairy production and the available support services. The cooperative was established with 34 members and an initial capital of 3,400 Birr. The main objectives are to minimize transaction costs, reduce price fluctuations over seasons, increase production efficiency, improve incomes and create job opportunities. Milk collection and marketing started in January 2000, with a daily total of 308 liters. The association has made significant progress so far and currently has over 850 members (about 50% female) who individually own over 3000 dairy cows. The current capital of the association has increased to USD 138,029. The number of milk collection sites has increased to 10 and job opportunity has been created for 62 staff. Daily milk collection has increased to over 8,000 liters and is mainly sold to the Dairy Development Enterprise (DDE) in Addis Ababa. The cooperative has established a small processing unit for the production of butter, yoghurt and cottage cheese during periods of excess supply. Members use mainly crossbred animals and the management level is relatively intensive with limited land area. Most animals are stall fed. The cooperative supplies inputs such as grass hay, concentrate feeds, veterinary drugs and services, and artificial insemination service to members at reasonable prices. Rural dairy farmers are joining the cooperative, taking advantage of market access for their milk. Inputs required in dairy production include feeds and water, labour, veterinary drugs and services, artificial insemination and equipment and utensils. The largest input in terms of volume and financial requirements is feed. These involve roughages and concentrate feeds. The main rural areas that provide roughage feeds (grass hay and crop residues) include Selale, Ada’a and adjacent Woredas, and Arsi. Concentrate feeds such as bran, middlings, oil seed cakes, molasses are supplied by ago-industries around Addis Ababa, Debre Zeit and Nazareth, but the row materials come from various parts of the country. Molasses is supplied from Wonji and Shoa Sugar Estates. Another major input is water which is used for animal consumption, washing and cleaning purposes. Most dairy farmers use expensive municipal water supply. Most of the milk collected is supplied to DDE. Pasteurized and processed products are mainly sold in Addis. Some fresh milk is also sold directly to hotels and restaurants in Addis Ababa, Debre Zeit, Dukem and Nazareth towns. In addition, milk collected from Ada’a by the Sebeta agro-industry is processed and supplied to urban centres as far as Bahir Dar. Manure produced from dairy farms is also supplied to a limited extent to rural areas, particularly to horticultural crops producing farms. A strong and organized rural-urban linkage is evolving informally at the moment and this should be recognized and strengthened to benefit both rural and urban dwellers in taking advantage of the value chain. Although urban and peri-urban dairy production system plays important role in the national economy, the system has been marginalized and there is limited research and institutional support addressing this issue. This paper presents the activities and achievements of the Ada’a dairy cooperative and also highlights the rural and urban linkages through the value chain of milk production, processing and marketing

Galaxy cluster aperture masses are more robust to baryonic effects than 3D halo masses

Systematic uncertainties in the mass measurement of galaxy clusters limit the cosmological constraining power of future surveys that will detect more than $10^5$ clusters. Previously, we argued that aperture masses can be inferred more accurately and precisely than 3D masses without loss of cosmological constraining power. Here, we use the Baryons and Haloes of Massive Systems (BAHAMAS) cosmological, hydrodynamical simulations to show that aperture masses are also less sensitive to changes in mass caused by galaxy formation processes. For haloes with $m_\mathrm{200m,dmo} > 10^{14} \, h^{-1} \, \mathrm{M}_\odot$, binned by their 3D halo mass, baryonic physics affects aperture masses and 3D halo masses similarly when measured within apertures similar to the halo virial radius, reaching a maximum reduction of $\approx 3 \, \%$. For lower-mass haloes, $10^{13.5} < m_\mathrm{200m,dmo} / (h^{-1} \, \mathrm{M}_\odot) < 10^{14}$, and aperture sizes $\sim 1 \, h^{-1} \, \mathrm{cMpc}$, representative of weak lensing observations, the aperture mass is consistently reduced less ($\lesssim 5 \, \%$) than the 3D halo mass ($\lesssim 10 \, \%$ for $m_\mathrm{200m}$). The halo mass reduction evolves only slightly, by up to $2$ percentage points, between redshift 0.25 and 1 for both the aperture mass and $m_\mathrm{200m}$. Varying the strength of the simulated feedback so the mean simulated hot gas fraction covers the observed scatter inferred from X-ray observations, we find that the aperture mass is consistently less biased than the 3D halo mass, by up to $2 \,$ percentage points at $m_\mathrm{200m,dmo} = 10^{14} \, h^{-1} \, \mathrm{M}_\odot$. Therefore, cluster aperture mass calibrations provide a fruitful path forward for future cluster surveys to reduce their sensitivity to systematic uncertainties.Comment: 9 pages, 6 figures, updated to accepted version from MNRA