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This paper presents the results from one of the first observations of ionospheric scintillation taken using the Low-Frequency Array (LOFAR). The observation was of the strong natural radio source Cassiopeia A, taken overnight on 18–19 August 2013, and exhibited moderately strong scattering effects in dynamic spectra of intensity received across an observing bandwidth of 10–80 MHz. Delay-Doppler spectra (the 2-D FFT of the dynamic spectrum) from the first hour of observation showed two discrete parabolic arcs, one with a steep curvature and the other shallow, which can be used to provide estimates of the distance to, and velocity of, the scattering plasma. A cross-correlation analysis of data received by the dense array of stations in the LOFAR “core” reveals two different velocities in the scintillation pattern: a primary velocity of ~20–40 ms−1 with a north-west to south-east direction, associated with the steep parabolic arc and a scattering altitude in the F-region or higher, and a secondary velocity of ~110 ms−1 with a north-east to south-west direction, associated with the shallow arc and a scattering altitude in the D-region. Geomagnetic activity was low in the mid-latitudes at the time, but a weak sub-storm at high latitudes reached its peak at the start of the observation. An analysis of Global Navigation Satellite Systems (GNSS) and ionosonde data from the time reveals a larger-scale travelling ionospheric disturbance (TID), possibly the result of the high-latitude activity, travelling in the north-west to south-east direction, and, simultaneously, a smaller-scale TID travelling in a north-east to south-west direction, which could be associated with atmospheric gravity wave activity. The LOFAR observation shows scattering from both TIDs, at different altitudes and propagating in different directions. To the best of our knowledge this is the first time that such a phenomenon has been reported.

Purificación Martínez del Prado,1 Isabel Alvarez-López,2,3 Severina Domínguez-Fernández,4 Arrate Plazaola,5 Oliver Ibarrondo,6 Elena Galve-Calvo,1 Nerea Ancizar-Lizarraga,2,3 María Gutierrez-Toribio,4 Ainhara Lahuerta-Martínez,5 Javier Mar6,7 1Medical Oncology Service, Basurto University Hospital, Bilbao, Spain; 2Medical Oncology Service, Donostia University Hospital, Donostia-San Sebastián, Spain; 3Biodonostia Health Research Institute, Donostia-San Sebastián, Spain; 4Medical Oncology Service, Araba University Hospital, Vitoria-Gasteiz, Spain; 5Medical Oncology Service, Onkologikoa, Donostia-San Sebastián, Spain; 6AP-OSI Research Unit, Alto Deba Integrated Health Care Organization, Mondragon, Spain; 7Health Services Research on Chronic Patients Network, Kronikgune Group, Bilbao, Spain Purpose: The 21-gene recurrence score (RS) is a genomic test developed as a prognostic and predictive tool to improve the treatment decision making in cases of estrogen receptor-positive and human epidermal growth factor receptor 2-negative early-stage breast cancer. This study examined the clinical and economic impact of its use in 4 Basque Country university hospitals. Methods: Taking into consideration the RS result, we recorded the recommended initial systemic adjuvant therapy (endocrine therapy with or without chemotherapy) according to standard clinicopathologic factors and the final decision about chemotherapy. Then, if the RS was high, chemotherapy was recommended; it was not recommended if the RS was low; for those with an intermediate RS, clinicopathologic factors were considered, and the initial recommendation based on those factors was maintained. In addition, the probability of switching treatment was calculated. Then, we developed an economic evaluation by measuring the treatment’s incremental short-term budget impact from both the societal perspective and that of the Basque Health System. Patients’ characteristics and chemotherapy use were analyzed using logistic regressions and receiver operating characteristic curves. Results: Without an RS, chemotherapy would have been prescribed to 56% of 401 patients, but, with RS use, that percentage decreased to 25. The overall rate of decision change was 35.4%. Test inclusion led to a reduction in chemotherapy costs of €922 per patient in the total population. Although this reduction did not entirely offset the cost of the test, the productivity loss per patient was reduced by €1,977. Conclusion: The 21-gene RS test significantly changed the indication for chemotherapy. As chemotherapy treatments with no benefit were avoided, patients’ quality of life was improved. The short-term economic impact was negative for the Basque Health Service, but savings resulted when sick-leave costs were included. Keywords: early-stage breast cancer, adjuvant chemotherapy, 21-gene assay, economic evaluation, health care costs

Author(s): S. Buitink (corresponding author) [1, 2]; A. Corstanje [2]; H. Falcke [2, 3, 4, 5]; J. R. Hrandel [2, 4]; T. Huege [6]; A. Nelles [2, 7]; J. P. [...]

Author(s): S. Buitink; A. Corstanje; H. Falcke; J. R. Hrandel; T. Huege; A. Nelles; J. P. Rachen; L. Rossetto; P. Schellart; O. Scholten; S. ter Veen; S. Thoudam; T. N. [...]

We present an overview of the LOFAR Tied-Array All-Sky Survey (LOTAAS) for radio pulsars and fast transients. The survey uses the high-band antennas of the LOFAR Superterp, the dense inner part of the LOFAR core, to survey the northern sky (δ >  0°) at a central observing frequency of 135 MHz. A total of 219 tied-array beams (coherent summation of station signals, covering 12 square degrees), as well as three incoherent beams (covering 67 square degrees) are formed in each survey pointing. For each of the 222 beams, total intensity is recorded at 491.52 μs time resolution. Each observation integrates for 1 hr and covers 2592 channels from 119 to 151 MHz. This instrumental setup allows LOTAAS to reach a detection threshold of 1–5 mJy for periodic emission. Thus far, the LOTAAS survey has resulted in the discovery of 73 radio pulsars. Among these are two mildly recycled binary millisecond pulsars (P = 13 and 33 ms), as well as the slowest-spinning radio pulsar currently known (P = 23.5 s). The survey has thus far detected 311 known pulsars, with spin periods ranging from 4 ms to 5.0 s and dispersion measures from 3.0 to 217 pc cm−3. Known pulsars are detected at flux densities consistent with literature values. We find that the LOTAAS pulsar discoveries have, on average, longer spin periods than the known pulsar population. This may reflect different selection biases between LOTAAS and previous surveys, though it is also possible that slower-spinning pulsars preferentially have steeper radio spectra. LOTAAS is the deepest all-sky pulsar survey using a digital aperture array; we discuss some of the lessons learned that can inform the approach for similar surveys using future radio telescopes such as the Square Kilometre Array. [ABSTRACT FROM AUTHOR]

Context. The combined use of carbon radio recombination lines (CRRLs) and the 158μm-[CII] line is a powerful tool for the study of the energetics and physical conditions (e.g., temperature and density) of photodissociation regions (PDRs). However, there are few observational studies that exploit this synergy. Aims. Here we explore the relation between CRRLs and the 158μm-[CII] line in light of new observations and models. Methods. We present new and existing observations of CRRLs in the frequency range 0.15–230 GHz with ALMA, VLA, the GBT, Effelsberg 100m, and LOFAR towards Orion A (M 42). We complement these observations with SOFIA observations of the 158μm-[CII] line. We studied two PDRs: the foreground atomic gas, known as the Veil, and the dense PDR between the HII region and the background molecular cloud. Results. In the Veil we are able to determine the gas temperature and electron density, which we use to measure the ionization parameter and the photoelectric heating efficiency. In the dense PDR, we are able to identify a layered PDR structure at the surface of the molecular cloud to the south of the Trapezium cluster. There we find that the radio lines trace the colder portion of the ionized carbon layer, the C+/C/CO interface. By modeling the emission of the 158μm-[CII] line and CRRLs as arising from a PDR we derive a thermal pressure >5 × 107 K cm−3 and a radiation field G0 ≈ 105 close to the Trapezium. Conclusions. This work provides additional observational support for the use of CRRLs and the 158μm-[CII] line as complementary tools to study dense and diffuse PDRs, and highlights the usefulness of CRRLs as probes of the C+/C/CO interface. [ABSTRACT FROM AUTHOR]

Hardwood species are valuable biological resources that have an important role in the economy and ecology of ecosystems worldwide. Non-zygotic or somatic embryogenesis (SE) is a powerful tool in plant biotechnology as it is a form of clonal propagation, amenable to cryopreservation of valuable germplasm and genetic transformation including gene editing. The SE process involves five steps and includes somatic embryo induction, proliferation, maturation, plantlet conversion, and subsequent plant acclimatization. This review aims to provide a general overview of these steps in different SE systems developed for hardwood species. Factors that influence the induction stage such as the age of the donor plant, genotype and culture media are discussed. The role of different explant types, i.e. zygotic embryos and non-zygotic tissues, such as roots, flower tissues, nodes, internodes, leaves or shoot apices, in SE induction are especially emphasized. Histological studies of the origin of somatic embryos and the sequence of events leading to their development from initial explants are assessed. Maintenance of embryogenic capacity carried out by subculture of embryogenic inocula on semisolid or liquid media through cell suspension cultures or by temporary immersion systems is described. At present, the main concerns associated with the application of SE for large-scale propagation of elite hardwoods are related to the embryo maturation, germination, and plantlet conversion steps, and these are highlighted in this review. Finally, molecular aspects associated with somatic embryo induction and development are also described. Attempts to overcome the hurdles identified in the embryogenic process, and future lines of research are proposed. [ABSTRACT FROM AUTHOR]

Quantitative understanding of the interstellar medium requires knowledge of its physical conditions. Low-frequency carbon radio recombination lines (CRRLs) trace cold interstellar gas and can be used to determine its physical conditions (e.g. electron temperature and density). In this work, we present spatially resolved observations of the low-frequency (≤390 MHz) CRRLs centred around C268α, C357α, C494α, and C539α towards Cassiopeia A on scales of ≤1.2 pc.We compare the spatial distribution of CRRLs with other interstellar medium tracers. This comparison reveals a spatial offset between the peak of the CRRLs and other tracers, which is very characteristic for photodissociation regions and that we take as evidence for CRRLs being preferentially detected from the surfaces of molecular clouds. Using the CRRLs, we constrain the gas electron temperature and density. These constraints on the gas conditions suggest variations of less than a factor of 2 in pressure over ∼1 pc scales, and an average hydrogen density of 200-470 cm-3. From the electron temperature and density maps, we also constrain the ionized carbon emission measure, column density, and path length. Based on these, the hydrogen column density is larger than 1022 cm-2, with a peak of ∼4 × 1022 cm-2 towards the south of Cassiopeia A. Towards the southern peak, the line-of-sight length is ∼40 pc over a ∼2 pc wide structure, which implies that the gas is a thin surface layer on a large (molecular) cloud that is only partially intersected by Cassiopeia A. These observations highlight the utility of CRRLs as tracers of low-density extended HI and CO-dark gas halo's around molecular clouds. [ABSTRACT FROM AUTHOR]

The Atacama Large millimetre/submillimetre Array (ALMA) makes use of water vapour radiometers (WVR), which monitor the atmospheric water vapour line at 183 GHz along the line of sight above each antenna to correct for phase delays introduced by the wet component of the troposphere. The application of WVR derived phase corrections improve the image quality and facilitate successful observations in weather conditions that were classically marginal or poor. We present work to indicate that a scaling factor applied to the WVR solutions can act to further improve the phase stability and image quality of ALMA data. We find reduced phase noise statistics for 62 out of 75 datasets from the long-baseline science verification campaign after a WVR scaling factor is applied. The improvement of phase noise translates to an expected coherence improvement in 39 datasets. When imaging the bandpass source, we find 33 of the 39 datasets show an improvement in the signal-to-noise ratio (S/N) between a few to ~30 percent. There are 23 datasets where the S/N of the science image is improved: 6 by <1%, 11 between 1 and 5%, and 6 above 5%. The higher frequencies studied (band 6 and band 7) are those most improved, specifically datasets with low precipitable water vapour (PWV), < mm, where the dominance of the wet component is reduced. Although these improvements are not profound, phase stability improvements via the WVR scaling factor come into play for the higher frequency (>450 GHz) and long-baseline (>5 km) observations. These inherently have poorer phase stability and are taken in low PWV (< mm) conditions for which we find the scaling to be most effective. A promising explanation for the scaling factor is the mixing of dry and wet air components, although other origins are discussed. We have produced a python code to allow ALMA users to undertake WVR scaling tests and make improvements to their data. [ABSTRACT FROM AUTHOR]