98%
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Objectives:: (1) To find a safe reference transmission factor for the remnant beam to be used when assessing the remnant beam during intra-oral radiography. (2) To identify factors such as exposure type, side (left or right), gender and age that might significantly affect transmission.
Methods:: Measurements were performed in the remnant beam during 323 intra-oral exposures of 43 patients. The exposure parameters were 60 kV and 7 mA. These measurements were compared with values in the same setting, but without a patient present to arrive at a transmission value. Differences between types of exposure [bitewing (BW), incisor and canine (IC) periapical, premolar and molar (PM) periapical], exposure side (left or right), gender and age were statistically analysed. The reference value was based on the exposure yielding the highest transmission value, to which a safety margin of two standard deviations (SDs) was added, and then rounding up.
Results:: The respective mean transmission values (SD) for BW, IC and PM exposures were as follows: 1.78% (1.15%), 0.639% (0.63%) and 2.60% (0.98%). The differences between PM and IC and between BW and IC were significant (p > 0.01). The differences between exposure side, gender and age were not significant. The reference transmission value, which was calculated from the highest mean transmission percentage for PM (2.60%) plus twice the SD (0.98%) and rounding up, was 5%.
Conclusions:: A transmission factor of 5% could be used to assess the remnant beam during intra-oral radiography. Anterior exposures led to significantly lower transmission values than posterior exposures.
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http://dx.doi.org/10.1259/dmfr.20180205 | DOI Listing |
Nat Astron
June 2025
Department of Astrophysics, School of Physics and Astronomy, Tel-Aviv University, Tel-Aviv, Israel.
The formation of the first stars and the subsequent population of X-ray binaries represents a fundamental transition in the state of the Universe as it evolves from near homogeneity to being abundant in collapsed structures such as galaxies. Due to a lack of direct observations, the properties of these stars remain highly uncertain. Here, by considering the impact of the first stars and their remnant X-ray binaries on the cosmological 21-cm signal, we demonstrate that upcoming observations have the potential to improve our understanding of these objects.
View Article and Find Full Text PDFProc Natl Acad Sci U S A
August 2025
Krantz Family Center for Cancer Research, Massachusetts General Hospital Cancer Center and Harvard Medical School, Charlestown, MA 02129.
E3 ubiquitin ligases mediating turnover of proteins engaged in cancer progression point to key regulatory nodes. To uncover modifiers of metastatic competency, we conducted an in vivo genome-wide CRISPR-inactivation screen using cultured breast circulating tumor cells, following intravascular seeding and lung colonization. We identified HECTD4, a previously uncharacterized gene encoding a conserved potential homologous to E6AP C-terminus domain-containing ubiquitin transferase, as a potent tumor and metastasis suppressor.
View Article and Find Full Text PDFBMC Oral Health
June 2025
Oral and Maxillofacial Surgery Department, Faculty of Dentistry, Cairo University, 11 Saraya Street, Manial, Cairo, Egypt.
Objectives: This study aims to evaluate the quality and quantity of gained and maintained bone width after Ridge splitting utilizing autogenic bone wedge versus mixed bone particles for horizontal ridge augmentation in the anterior aesthetic zone.
Materials And Methods: This randomized clinical trial included 20 patients with horizontally deficient anterior maxillary alveolar ridges. Patients were divided equally into two groups.
Beijing Da Xue Xue Bao Yi Xue Ban
April 2025
Department of Cariology and Endodontology, Peking University School and Hospital of Stomatology & National Center for Stomatology & National Clinical Research Center for Oral Diseases & National Engineering Research Center of Oral Biomaterials and Digital Medical Devices & Beijing Key Laboratory of
Objective: To evaluate the filling quality of single cone obturation in root canal model with irregular structure (Hus&Kim Ⅴ, Yin Ⅱ-type isthmus) which established by 3D printing technology using slices and radiographic methods, in order to provide reference for clinical practice.
Methods: (1) Extracted fresh premolars with Hus&Kim Ⅴ and Yin-type Ⅱ isthmus were collected and scanned by cone-beam computed tomography (CBCT), then standard root canal models were designed and printed. Rhodamine B staining and bias fitting were used to verify the availability of the models.
N Am Spine Soc J
December 2024
Department of Neurosurgery, University of Iowa Carver, College of Medicine, Iowa City, IA, United States.
Background: Chordomas are rare, slow growing, locally aggressive malignant bone tumors that arise from remnants of the embryonic notochord with variable presenting symptoms depending on tumor location.
Methods: All patients with craniospinal chordoma managed at our institution between 1982 and 2023 were retrospectively reviewed. Demographics, tumor characteristics, clinical course and treatment, and long-term neurological and survival outcomes were collected.