Current Research of the Leiden-Turin Archaeological Mission in Saqqara. A Preliminary Report on the 2018 Season

In 2015, the Museo Egizio in Turin joined the Leiden expedition to Saqqara, in the area south of the Unas causeway. This report presents the expedition’s new approach as well as some first results of this new cooperation. In the 2018 season, the Leiden-Turin expedition worked in the northern sector of its concession, covering an area of ca. 250 sqm just north of the tomb of Maya. Here Late Antique layers overlie a windblown deposit containing some simple burials and numerous “embalmers’ caches”, some of which yielded marl clay cups with hieratic labels. An overview of both the pottery and the human remains found during this season is provided in the present report. Below the wind-blown deposit is a level with Ramesside funerary chapels and shafts. One of them has a remarkable decoration including six small-format figures carved in high relief in the middle of its back wall. The shaft of another chapel was also excavated, revealing several plundered chambers which yielded only scanty finds. A large mud-brick wall exposed during the previous season turned out to belong to the outer wall and pylon entrance of a monumental tomb, whose owner’s name has not been found yet.A photogrammetric survey by a team of the Politecnico di Milano yielded a 3D model of the dig (included in the web version of this report), as well as several 3D models of the monumental tombs (completed or in the making). During the season, conservation work was carried out on several tombs and on the newly discovered Ramesside chapel.Middle Eastern Studie

New methods to constrain the radio transient rate: results from a survey of four fields with LOFAR

We report on the results of a search for radio transients between 115 and 190 MHz with the LOw-Frequency ARray (LOFAR). Four fields have been monitored with cadences between 15 minutes and several months. A total of 151 images were obtained, giving a total survey area of 2275 deg2. We analysed our data using standard LOFAR tools and searched for radio transients using the LOFAR Transients Pipeline (TraP). No credible radio transient candidate has been detected; however, we are able to set upper limits on the surface density of radio transient sources at low radio frequencies. We also show that low-frequency radio surveys are more sensitive to steep-spectrum coherent transient sources than GHz radio surveys. We used two new statistical methods to determine the upper limits on the transient surface density. One is free of assumptions on the flux distribution of the sources, while the other assumes a power-law distribution in flux and sets more stringent constraints on the transient surface density. Both of these methods provide better constraints than the approach used in previous works. The best value for the upper limit we can set for the transient surface density, using the method assuming a power-law flux distribution, is 1.3 · 10-3 deg-2 for transients brighter than 0.3 Jy with a time-scale of 15 min, at a frequency of 150 MHz. We also calculated for the first time upper limits for the transient surface density for transients of different time-scales. We find that the results can differ by orders of magnitude from previously reported, simplified estimates

Pulsar polarisation below 200 MHz: Average profiles and propagation effects

Aims: We present the highest-quality polarisation profiles to date of 16 non-recycled pulsars and four millisecond pulsars, observed below 200 MHz with the LOFAR high-band antennas. Based on the observed profiles, we perform an initial investigation of expected observational effects resulting from the propagation of polarised emission in the pulsar magnetosphere and the interstellar medium. Methods: The polarisation data presented in this paper have been calibrated for the geometric-projection and beam-shape effects that distort the polarised information as detected with the LOFAR antennas. We have used RM Synthesis to determine the amount of Faraday rotation in the data at the time of the observations. The ionospheric contribution to the measured Faraday rotation was estimated using a model of the ionosphere. To study the propagation effects, we have compared our low-frequency polarisation observations with archival data at 240, 400, 600, and 1400 MHz. Results: The predictions of magnetospheric birefringence in pulsars have been tested using spectra of the pulse width and fractional polarisation from multifrequency data. The derived spectra offer only partial support for the expected effects of birefringence on the polarisation properties, with only about half of our sample being consistent with the model's predictions. It is noted that for some pulsars these measurements are contaminated by the effects of interstellar scattering. For a number of pulsars in our sample, we have observed significant variations in the amount of Faraday rotation as a function of pulse phase, which is possibly an artefact of scattering. These variations are typically two orders of magnitude smaller than that observed at 1400 MHz by Noutsos et al. (2009), for a different sample of southern pulsars. In this paper we present a possible explanation for the difference in magnitude of this effect between the two frequencies, based on scattering. Finally, we have estimated the magnetospheric emission heights of low-frequency radiation from four pulsars, based on the phase lags between the flux-density and the PA profiles, and the theoretical framework of Blaskiewicz et al. (1991, ApJ, 370, 643). These estimates yielded heights of a few hundred km; at least for PSR B1133+16, this is consistent with emission heights derived based on radius-to-frequency mapping, but is up to a few times larger than the recent upper limit based on pulsar timing. Conclusions: Our work has shown that models, like magnetospheric birefringence, cannot be the sole explanation for the complex polarisation behaviour of pulsars. On the other hand, we have reinforced the claim that interstellar scattering can introduce a rotation of the PA with frequency that is indistinguishable from Faraday rotation and also varies as a function of pulse phase. In one case, the derived emission heights appear to be consistent with the predictions of radius-to-frequency mapping at 150 MHz, although this interpretation is subject to a number of systematic uncertainties

The LOFAR Transients Pipeline

Contains fulltext : 143840.pdf (preprint version ) (Open Access

Impact of the COVID-19-pandemic on patients with gynecological malignancies undergoing surgery: A Dutch population-based study using data from the 'Dutch Gynecological Oncology Audit'

Objective. The COVID-19-pandemic caused drastic healthcare changes worldwide. To date, the impact of these changes on gynecological cancer healthcare is relatively unknown. This study aimed to assess the impact of the COVID-19-pandemic on surgical gynecological-oncology healthcare.Methods. This population-based cohort study included all surgical procedures with curative intent for gynecological malignancies, registered in the Dutch Gynecological Oncology Audit, in 2018-2020. Four periods were identified based on COVID-19 hospital admission rates: 'Pre-COVID-19', 'Firstwave', 'Interimperiod', and'Second wave'. Surgical volume, perioperative care processes, and postoperative outcomes from 2020 were compared with 2018-2019.Results. A total of 11,488 surgical procedureswere analyzed. For cervical cancer, surgical volume decreased by 17.2% in 2020 compared to 2018-2019 (mean 2018-2019: n= 542.5, 2020: n= 449). At nadir (interimperiod), only 51% of the expected cervical cancer procedures were performed. For ovarian, vulvar, and endometrial cancer, volumes remained stable. Patients with advanced-stage ovarian cancer more frequently received neoadjuvant chemotherapy in 2020 compared to 2018-2019 (67.7% (n = 432) vs. 61.8% (n = 783), p = 0.011). Median time to first treatmentwas significantly shorter in all four malignancies in 2020. For vulvar and endometrial cancer, the length of hospital staywas significantly shorter in 2020. No significant differences in complicated course and 30-day-mortality were observed.Conclusions. The COVID-19-pandemic impacted surgical gynecological-oncology healthcare: in 2020, surgical volume for cervical cancer dropped considerably, waiting time was significantly shorter for all malignancies, while neoadjuvant chemotherapy administration for advanced-stage ovarian cancer increased. The safety of perioperative healthcare was not negatively impacted by the pandemic, as complications and 30-day-mortality remained stable. (C) 2022 The Authors. Published by Elsevier Inc.Analysis and support of clinical decision makin