Effects of feeding system and pre-partum supplementation on the β-carotene status of South African Holstein cows

AbstractThe objectives were to investigate the β-carotene status of dairy cows under various production systems, and to determine the effect of pre-partum β-carotene supplementation on their post-partum β-carotene status. Ten farms were selected from each of the three  production systems, namely pasture-based, hay-based total mixed ration (TMR) and silage-based TMR. Twenty cows per farm were sampled in each system, and blood plasma β-carotene concentration was determined with a portable spectrophotometer (n = 200 cows per system). Mean blood β-carotene concentrations of pasture-fed cows were 5.54 mg/L, and were higher (P <0.05) than concentrations of cows on hay-based (2.98 mg/L) and maize silage-based TMR systems (1.71 mg/L); in β-carotene status, therefore, these systems were optimal, marginal, and deficient, respectively. In the second experiment, 10 cows received a hay-based control TMR, and 10 were  supplemented with 1.2 g/day of β-carotene pre-partum from day -56 to calving and monitored until day 56 postpartum. The supplemented cows were in optimal β-carotene status until calving, with a minor carry-over effect until 10 days post partum, and then declined gradually in status until they needed supplementation. The β-carotene status between the groups differed from three weeks pre-partum to two weeks post partum, with the control group being marginal to deficient from three weeks pre-partum onwards. Forage type and its β-carotene content play a major role in the β-carotene status of cows and more research is needed on the potential storage and mobilization of β-carotene in cows

Sequential feeding of Ixodes rubicundus on its natural host, Elephantulus myurus : effects on tick mass and on engorgement and moulting success

Engorgement, mass at repletion and moulting success of immature Ixodes rubicundus after sequential infestations of their natural hosts, rock elephant shrews (Elephantulus myurus) , were investigated under laboratory conditions. The reaction of E. myurus is characterized by inefficient or non-existent anti-tick immunity which enables immature I. rubicundus to attach and engorge successfully and ensures a high moulting success rate.The articles have been scanned in colour with a HP Scanjet 5590; 600dpi. Adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format.mn201

Detachment rhythms of immature Ixodes rubicundus from their natural host, the rock elephant shrew (Elephantulus myurus)

Detachment rhythms of immature Karoo paralysis ticks (Ixodes rubicundus) from their natural host, the rock elephant shrew (Elephantulus myurus) , were investigated under laboratory and natural conditions. Larvae and nymphs detach mainly during the day. Peak detachment always occurred after the commencement of artificial as well as natural light cycles. The detachment of larvae appears to be more synchronous than that of nymphs, with a larger percentage of larvae detaching over a shorter period of time. The detachment rhythms of I. rubicundus are strongly correlated with the activity patterns of their hosts. This enhances not only the survival, but also the dispersion and host contact of subsequent stages.The articles have been scanned in colour with a HP Scanjet 5590; 600dpi. Adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format.mn201

The SARAO MeerKAT 1.3 GHz Galactic Plane Survey

We present the SARAO MeerKAT Galactic Plane Survey (SMGPS), a 1.3 GHz continuum survey of almost half of the Galactic Plane (251○ ≤l ≤ 358○ and 2○ ≤l ≤ 61○ at |b| ≤ 1 5). SMGPS is the largest, most sensitive and highest angular resolution 1 GHz survey of the Plane yet carried out, with an angular resolution of 8″ and a broadband RMS sensitivity of ∼10–20 μJy beam−1. Here we describe the first publicly available data release from SMGPS which comprises data cubes of frequency-resolved images over 908–1656 MHz, power law fits to the images, and broadband zeroth moment integrated intensity images. A thorough assessment of the data quality and guidance for future usage of the data products are given. Finally, we discuss the tremendous potential of SMGPS by showcasing highlights of the Galactic and extragalactic science that it permits. These highlights include the discovery of a new population of non-thermal radio filaments; identification of new candidate supernova remnants, pulsar wind nebulae and planetary nebulae; improved radio/mid-IR classification of rare Luminous Blue Variables and discovery of associated extended radio nebulae; new radio stars identified by Bayesian cross-matching techniques; the realisation that many of the largest radio-quiet WISE H II region candidates are not true H II regions; and a large sample of previously undiscovered background H I galaxies in the Zone of Avoidance

The MeerKAT Galaxy Cluster Legacy Survey: I. Survey overview and highlights

Please abstract in the article.The South African Radio Astronomy Observatory (SARAO), the National Research Foundation (NRF), the National Radio Astronomy Observatory, US National Science Foundation, the South African Research Chairs Initiative of the DSI/NRF, the SARAO HCD programme, the South African Research Chairs Initiative of the Department of Science and Innovation.http://www.aanda.orghj2022Physic

DUAL POLARIZED LINEAR MICROSTRIP PATCH ARRAY.

The preliminary design and results for a low-cost, dual-polarized, fan-beam antenna are presented. The antenna is a linear array of square microstrip patches excited by a coplanar corporate feed network. The feed network has two ports and allows independent radiation of orthogonal linearly polarized far fields.Conference Pape

Equivalent circuits for an electrically thick square patch directly fed by a coaxial probe or by a microstrip line

The authors present lumped-element equivalent circuits for two specific square patches on an electrically thick (0.05 λ0) substrate. The equivalent circuits were derived from experimental data and could be useful in the verification of theoretical techniques. For the particular geometry studied the probe fed patch requires sidelengths approximately 6% shorter than the microstrip fed patch, for the same resonant frequency. The microstrip-fed patch has a sharper resonance and approximately half the bandwidth of the probe-fed patch. Presumably the probe introduces more losses than the microstrip, thus damping the patch resonance.Conference Pape

Linear patch array pattern degradation due to corporate feed radiation

A specific linear array of square patches is considered. The array, measured feed radiation, and sources of feed radiation are examined. It is shown that radiation from a coplanar microstrip feed network can degrade the patterns of a linear patch array to an extent that is unacceptable in many applications. The problem arises when the microstrip substrate parameters are chosen to maximize radiation at the patch edges, thus undermining the ability of the feed network to guide waves. One solution is to use a relatively thin, high-relative-permittivity substrate. This has the disadvantage of reduced bandwidth. Another approach is to sacrifice the low-cost coplanar feed by placing the feed on the opposite side of the ground plane from the radiating elements, and using coaxial pins to drive the patches. In this way, the radiation and guided wave functions are separated and the substrate parameters can be separately optimized for each. The feed can also be screened.Conference Pape

Design process for Jaumann absorbers

Results of an investigation into the design of Jaumann absorbers are reported. Jaumann absorbers are effective in minimizing plane wave reflection from a conducting metal surface and exhibit reasonably wide frequency and incidence angle bandwidths. The spacers between the resistive sheets are usually assumed to be lossless and a quarter-wavelength long at the center frequency. It is shown that the numerical minimization technique can result in a design which improves upon the purely analytical methods. Some representative results are shown.Conference Pape