Search for Dark-Matter-Nucleon Interactions via Migdal Effect with DarkSide-50.

Dark matter elastic scattering off nuclei can result in the excitation and ionization of the recoiling atom through the so-called Migdal effect. The energy deposition from the ionization electron adds to the energy deposited by the recoiling nuclear system and allows for the detection of interactions of sub-GeV/c^{2} mass dark matter. We present new constraints for sub-GeV/c^{2} dark matter using the dual-phase liquid argon time projection chamber of the DarkSide-50 experiment with an exposure of (12 306±184) kg d. The analysis is based on the ionization signal alone and significantly enhances the sensitivity of DarkSide-50, enabling sensitivity to dark matter with masses down to 40 MeV/c^{2}. Furthermore, it sets the most stringent upper limit on the spin independent dark matter nucleon cross section for masses below 3.6 GeV/c^{2}.

Search for Dark Matter Particle Interactions with Electron Final States with DarkSide-50.

We present a search for dark matter particles with sub-GeV/c^{2} masses whose interactions have final state electrons using the DarkSide-50 experiment's (12 306±184) kg d low-radioactivity liquid argon exposure. By analyzing the ionization signals, we exclude new parameter space for the dark matter-electron cross section σ[over ¯]_{e}, the axioelectric coupling constant g_{Ae}, and the dark photon kinetic mixing parameter κ. We also set the first dark matter direct-detection constraints on the mixing angle |U_{e4}|^{2} for keV/c^{2} sterile neutrinos.

Variability of the discrepancy between manufacturer and measured CTDI100 values by scanner type, acquisition parameters and phantom size.

According to the EU directive 2013/59, the computed tomography (CT) equipments shall be able to inform the practitioner of parameters for assessing the patient dose. The aim of this study was to measure the accuracy of the CTDI100 with respect to the values stipulated in the manufacturer manual for different manufacturers/models of CT and to assess the impact of acquisition parameters on CTDI100 accuracy. Ten CT from 4 different manufacturers were included in the study. The discrepancy with the manufacturer value CTDI100 was checked with a dosimeter with traceable calibration. Manufacturer values for the CTDI100 were derived from the equipment's manual. The impact of the kVp, CT model, primary collimation and phantom size on the discrepancy of the CTDI100, was assessed by a four-way ANOVA. All the factors had a statistically significant impact on CTDI100 discrepancy (P < 0.05). In a head to head comparison, the greater discrepancies were found on average for 80 kV (15.4 ±â€¯10.7%), sixteen channels CT (10.3 ±â€¯5.1%) and for thick collimations (13.2 ±â€¯6.8%), whilst no significant differences were found between head and body phantoms. For sixteen channels CT and acquisition protocols involving the use of low kV or thick primary collimation, the discrepancies with the manufacturer value CTDI100 can be higher than 20%, which is the suspension level indicated in the EC RP N.162 Publication. This suggests the need of individual calibration of CT X-ray tubes by the manufacturers and the necessity of including this check in the quality control programs for CT.

Assessment of radiation protection awareness and knowledge about radiological examination doses among Italian radiographers.

OBJECTIVES: To evaluate radiation protection basic knowledge and dose assessment for radiological procedures among Italian radiographers METHODS: A validated questionnaire was distributed to 780 participants with balanced demographic characteristics and geographic distribution. RESULTS: Only 12.1 % of participants attended radiation protection courses on a regular basis. Despite 90 % of radiographers stating to have sufficient awareness of radiation protection issues, most of them underestimated the radiation dose of almost all radiological procedures. About 5 % and 4 % of the participants, respectively, claimed that pelvis magnetic resonance imaging and abdominal ultrasound exposed patients to radiation. On the contrary, 7.0 % of the radiographers stated that mammography does not use ionising radiation. About half of participants believed that radiation-induced cancer is not dependent on age or gender and were not able to differentiate between deterministic and stochastic effects. Young radiographers (with less than 3 years of experience) showed a higher level of knowledge compared with the more experienced radiographers. CONCLUSIONS: There is a substantial need for radiographers to improve their awareness of radiation protection issues and their knowledge of radiological procedures. Specific actions such as regular training courses for both undergraduate and postgraduate students as well as for working radiographers must be considered in order to assure patient safety during radiological examinations. MAIN MESSAGES: • Radiographers should improve their knowledge on radiation protection issues. • Only 12.1 % of participants attended radiation protection courses on a regular basis. • Specific actions must be considered in order to increase knowledge and awareness.

[Carotid-carotid bypass. Indications and results]. / Bypass carotido-carotideo. Indicazioni e risultati.

AIM: The aim of this study is to evaluate the indications for a carotid-carotid bypass and its therapeutic efficacy. METHODS: Between January 1995 and December 2001, 42 out of 782 patients with obstructive lesions of carotid vessels were submitted to carotid-carotid bypass. Preoperative investigations included Duplex scanning, transcranial Doppler and cerebral CT in all the patients, angiography in 24, spiral CT in 8, MR angiography in 6. Carotid bypass was planned pre-operatively in 13 cases due to internal carotid occlusion in 4, to pseudo-occlusion in 8 and to restenosis in 1. In the remaining 29, due to a too thin residual wall or to the lack of a good clivage plane, a carotid bypass was planned intraoperatively. A PTFE graft was employed in 30 cases while the autologous saphenous vein in 12. Four patients were lost in a 12-80-month follow-up. No intra or postoperative mortality was recorded. RESULTS: Three patients died during the follow-up. In 1 patient the death followed an ischemic stroke due to bypass occlusion. Four bypasses became occluded, in 3 cases without clinical signs. Eight patients suffered by transient superior laryngeal nerve iniury. CONCLUSIONS: Carotid bypass, as an alternative to CEA, provides good results in the treatment of the patients with carotid stenosis, pseudo-occlusion or segmental occlusion. In most of the cases the surgical technique is planned intraoperatively but in selected cases angiographic findings, spiral CT and color flow duplex can suggest in the preoperative phase that carotid bypass is the best choice.

Direct and indirect mutation analyses in patients with ornithine transcarbamylase deficiency.

Ornithine transcarbamylase (OTC) is one of 5 enzymes in the detoxification of ammonia to urea, and its deficiency, an X-linked disease, is the most common inborn error of urea genesis in humans. Because of the devastating nature of the disease there is a strong demand for reliable and rapid molecular analyses in OTC families in order to offer carrier detection and prenatal diagnosis. This paper presents the efficiency of direct and indirect mutation analyses in 22 OTC families using Southern blotting and polymerase chain reaction (PCR) amplification. For 89% of the mothers with an affected child, at least 1 RFLP of the OTC locus was informative concerning prenatal diagnosis. 100% informativity was reached by using the additional flanking markers 754 and LI.28. In total, 3 deletions (14%) and 1 TaqI site mutation (4.5%) in exon 3 were detected. 13 (60%) of our 22 mothers were found to be carriers, 9 of them being obligate carriers and 4 detected by biochemical testing. 4 mothers were excluded as carriers by DNA analyses, and in 5 mothers the carrier status could not be assessed positively. DNA analyses permitted carrier detection in 32% and carrier exclusion in 55% of 22 female relatives. Prenatal diagnosis was performed in 4 families: in 1 family by direct mutation detection and in 3 families by linkage analyses. It was possible to determine the mutation origin in 6 families, all of them with male probands. In 4 families the mutation had occurred during grandpaternal spermiogenesis, suggesting higher mutation rates in males, but in 2 cases it was the result of an event during maternal oogenesis, proving that new mutations in the OTC gene do also occur in eggs. Our recommended strategy for carrier detection and prenatal diagnosis in OTC deficiency is to examine routinely Southern blots of BamHI, EcoRI, HindIII, MspI, PstI and TaqI digestions using the OTCcDNA probe pH0731 and the flanking markers 754 and LI.28, as well as the TaqI-digested PCR products of exons 3, 5 and 9.