140 research outputs found
Conservation of angular momentum and the existence of absolute time and space
The law of balance of angular momentum is shown to imply the existence of
absolute time, a fundamental physical quantity that is independent of the
motion or position of the observer. Absolute time implies the notion of
absolute simultaneity, which in turn leads to the notion of absolute distance
between two points. The existence of absolute space follows as a consequence.
These concepts apply to every field of physics to which the angular momentum
balance law applies, and in particular to the theory of special relativity. The
paper also shows that in a vacuum, the independence of the speed of light from
the motion of its source makes it possible to determine the absolute positions
of all points in space. The same independence also allows us to determine the
state of absolute rest or motion of a reference frame from within the frame
itself.Comment: Original version of a paper to be publisnhed in Physics Essays 36
(1), 100-107 (2023
Dental pathology in present-day and copper age samples
Dental paleopathology has become an excellent
discipline to reconstruct the oral health of ancient
populations and its trend from the past to the present
day, especially regarding dietary habits. Our preliminary
research aims to perform a comparative analysis on
dental health status of two widely chronologically
distant samples from Sardinia: the first one dates back
to the Copper Age (III mill. B.C.) and comes from a
collective hypogean burial named Scab’e Arriu (Siddi,
SU), the second one is composed by extracted teeth
of present-day individuals, collected during some
traineeships at the Department of Surgical Science of
the Dentistry School, in Cagliari
Evaluation of an automatic HPLC analyser for thalassemia and haemoglobin variants screening
In this paper the authors report the evolution of a new automatic
HPLC analyser for screening haemoglobinopathies. HbA2 and F determinations are accurate and reproducible. The analysis time is short (6.5 min) and there is a good separation between the HbA2 values of β-thalassemia carriers from normals and α-thalassemia carriers, with no overlap between these groups. In addition, the system is also able to detect and quantitate most of the haemoglobin variants, particularly those (HbS, HbC, HbE and Hb Lepore) able to interact with β-thalassemia and could make haemoglobin electrophoresis unnecessary in all samples. The ease of operation and the limited technical work make this system especially suitable for laboratories with a high workload and allow the cost of screening to be reduced
Mesonephric-Like Adenocarcinomas a Rare Tumor: The Importance of Diagnosis
Mesonephric-like adenocarcinomas (MLA) are rare neoplasms that arise in the uterine body and ovary and have been added to the World Health Organisation’s recent 2020 classification of female genital cancers. The pathogenesis of MLA is unknown and it remains debated whether they represent mesonephric carcinomas (Wolffian) arising in the endometrium/ovary or endometrioid carcinomas (Müllerian) closely mimicking mesonephric carcinomas. Here we report the case of a 57-year-old woman with an initial misdiagnosis of endometrioid adenocarcinoma on diagnostic biopsy. The patient came to our clinical evaluation for the appearance of menometrorrhagia complicated by anemia for several months. Therefore, she underwent pelvic echo-flowmetry, with indication for diagnostic hysteroscopy with endometrial biopsy, which yielded a positive result for endometrioid endometrial adenocarcinoma. Following staging CT scan and targeted examinations on pulmonary findings, the patient underwent surgery with surprise of definitive diagnosis deponent for endometrial MLA. Our intention is to establish a brief review of the scientific evidence in the literature and the tools available for a correct histological diagnosis, in the light of the scant anatomopathological evidence. Our question gives rise to the motive for the publication: is immunohistochemistry the right way to resolve the diagnostic error at histology, which is usually the only source of diagnostic certainty? This case is intended to alert of diagnostic error that risked having the patient treated as a neoplasm with a favorable prognosis and low degree of aggressiveness instead of for a very aggressive and poor prognosis tumor such as MLA
vancomycin resistant enterococcus faecium high resolution typing by core genome multilocus sequence typing
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Relationship between Antibody Susceptibility and Lipopolysaccharide O-Antigen Characteristics of Invasive and Gastrointestinal Nontyphoidal Salmonellae Isolates from Kenya
Background: Nontyphoidal Salmonellae (NTS) cause a large burden of invasive and gastrointestinal disease among young children in sub-Saharan Africa. No vaccine is currently available. Previous reports indicate the importance of the O-antigen of Salmonella lipopolysaccharide for virulence and resistance to antibody-mediated killing. We hypothesised that isolates with more O-antigen have increased resistance to antibody-mediated killing and are more likely to be invasive than gastrointestinal.
Methodology/Principal findings: We studied 192 NTS isolates (114 Typhimurium, 78 Enteritidis) from blood and stools, mostly from paediatric admissions in Kenya 2000-2011. Isolates were tested for susceptibility to antibody-mediated killing, using whole adult serum. O-antigen structural characteristics, including O-acetylation and glucosylation, were investigated. Overall, isolates were susceptible to antibody-mediated killing, but S. Enteritidis were less susceptible and expressed more O-antigen than Typhimurium (p\u3c0.0001 for both comparisons). For S. Typhimurium, but not Enteritidis, O-antigen expression correlated with reduced sensitivity to killing (r = 0.29, 95% CI = 0.10-0.45, p = 0.002). Both serovars expressed O-antigen populations ranging 21-33 kDa average molecular weight. O-antigen from most Typhimurium were O-acetylated on rhamnose and abequose residues, while Enteritidis O-antigen had low or no O-acetylation. Both Typhimurium and Enteritidis O-antigen were approximately 20%-50% glucosylated. Amount of S. Typhimurium O-antigen and O-antigen glucosylation level were inversely related. There was no clear association between clinical presentation and antibody susceptibility, O-antigen level or other O-antigen features.
Conclusion/Significance: Kenyan S. Typhimurium and Enteritidis clinical isolates are susceptible to antibody-mediated killing, with degree of susceptibility varying with level of O-antigen for S. Typhimurium. This supports the development of an antibody-inducing vaccine against NTS for Africa. No clear differences were found in the phenotype of isolates from blood and stool, suggesting that the same isolates can cause invasive disease and gastroenteritis. Genome studies are required to understand whether invasive and gastrointestinal isolates differ at the genotypic level
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