2,644 research outputs found
Examination of coalescence as the origin of nuclei in hadronic collisions
The origin of weakly bound nuclear clusters in hadronic collisions is a key question to be addressed by heavy-ion collision (HIC) experiments. The measured yields of clusters are approximately consistent with expectations from phenomenological statistical hadronization models (SHMs), but a theoretical understanding of the dynamics of cluster formation prior to kinetic freeze-out is lacking. The competing model is nuclear coalescence, which attributes cluster formation to the effect of final state interactions (FSI) during the propagation of the nuclei from kinetic freeze-out to the observer. This phenomenon is closely related to the effect of FSI in imprinting femtoscopic correlations between continuum pairs of particles at small relative momentum difference. We give a concise theoretical derivation of the coalescence-correlation relation, predicting nuclear cluster spectra from femtoscopic measurements. We review the fact that coalescence derives from a relativistic Bethe-Salpeter equation, and recall how effective quantum mechanics controls the dynamics of cluster particles that are nonrelativistic in the cluster center-of-mass frame. We demonstrate that the coalescence-correlation relation is roughly consistent with the observed cluster spectra in systems ranging from PbPb to pPb and pp collisions. Paying special attention to nuclear wave functions, we derive the coalescence prediction for the hypertriton and show that it, too, is roughly consistent with the data. Our work motivates a combined experimental programme addressing femtoscopy and cluster production under a unified framework. Upcoming pp, pPb, and peripheral PbPb data analyzed within such a program could stringently test coalescence as the origin of clusters
Wear predictions for reverse total shoulder replacements
Reverse total shoulder arthroplasty (RTSA) has
become the gold standard to treat rotator cuff tear
arthropathy. RTSA is performed by
substituting the humeral head and the glenoid cavity by
a plastic cup in UHMWPE and a metallic head,
respectively, in a geometrical reversed
configuration with respect to the anatomical one. Major
complications affect 27% of cases and mainly regard
scapular notching due to cup-bone impingement and
wear debris. Unfortunately, wear in shoulder
prosthesis has not been largely studied as for hip and
knee implants. Indeed, no wear test standards or even
shoulder simulators exist, also because of a limited
knowledge on shoulder/RTSA dynamics. Additionally,
only a few numerical wear models for RTSA can be
found in the literature, mainly focused on
the comparison between anatomical and reverse
solutions, and which often simulates simplified
conditions, such as planar unloaded motions even
neglecting fundamental aspects of wear process, i.e.
cross-shearing (CS).
The aim of the present study is to numerically
investigate wear in RTSAs analysing the effect of: a)
wear factor and wear law; a) implant geometry; b)
inversion of bearing materials, i.e. plastic head +
metallic cup, which should reduce the risks associated
to scapular notching
Delayed neonatal visual evoked potentials are associated to asymmetric growth pattern in twins
Objectives: To study the association between intrauterine growth and visual pathways maturation by neonatal visual evoked potentials (VEPs) in twins, in view of a possible prognostic role. Methods: Seventy-four twin neonates from 37 pregnancies were selected based on gestational age of more than 30 weeks and uneventful perinatal clinical course. Flash VEPs were recorded at the same postmenstrual age in each twin pair. The association between P2 latency and anthropometric variables at birth was analyzed by comparison within each twin pair and regarding each variable as ordered difference between the two twins. Results: Analysis of differences within each twin pair highlighted that inter-twin difference in P2 latency was significantly related to difference in ponderal index (PI) (p = 0.048). Expressing the difference in latency as a categorical binary variable, the correlation was significant for both difference in PI, (median difference = −0.36, 95% CI −0.54 to −0.14, p = 0.001) and difference in body mass index (BMI), (median difference = −1.06, 95% CI −1.74 to −0.29, p = 0.006). Conclusions: Lower values of PI and BMI differences are associated to delayed VEP latency in twin pairs. Significance: VEP latency suggests reduced myelination of visual pathways when difference in growth pattern occurs in twins
Genomic and transcriptomic comparison between Staphylococcus aureus strains associated with high and low within herd prevalence of intra-mammary infection
Background: Staphylococcus aureus (Staph. aureus) is one of the major pathogens causing mastitis in dairy ruminants worldwide. The chronic nature of Staph. aureus infection enhances the contagiousness risk and diffusion in herds. In order to identify the factors involved in intra-mammary infection (IMI) and diffusion in dairy cows, we investigated the molecular characteristics of two groups of Staph. aureus strains belonging to ST8 and ST398, differing in clinical properties, through comparison of whole genome and whole transcriptome sequencing.
Results: The two groups of strains, one originated from high IMI prevalence herds and the other from low IMI prevalence herds, present a peculiar set of genes and polymorphisms related to phenotypic features, such as bacterial invasion of mammary epithelial cells and host adaptation. Transcriptomic analysis supports the high propensity of ST8 strain to chronicity of infection and to a higher potential cytotoxicity.
Conclusions: Our data are consistent with the invasiveness and host adaptation feature for the strains GTB/ST8 associated to high within-herd prevalence of mastitis. Variation in genes coding for surface exposed proteins and those associated to virulence and defence could constitute good targets for further research
Visuo-spatial attention deficit in children with reading difficulties
Although developmental reading disorders (developmental dyslexia) have been mainly associated with auditory-phonological deficits, recent longitudinal and training studies have shown a possible causal role of visuo-attentional skills in reading acquisition. Indeed, visuo-attentional mechanisms could be involved in the orthographic processing of the letter string and the graphemic parsing that precede the grapheme-to-phoneme mapping. Here, we used a simple paper-and-pencil task composed of three labyrinths to measure visuo-spatial attention in a large sample of primary school children (n = 398). In comparison to visual search tasks requiring visual working memory, our labyrinth task mainly measures distributed and focused visuo-spatial attention, also controlling for sensorimotor learning. Compared to typical readers (n = 340), children with reading difficulties (n = 58) showed clear visuo-spatial attention impairments that appear not linked to motor coordination and procedural learning skills implicated in this paper and pencil task. Since visual attention is dysfunctional in about 40% of the children with reading difficulties, an efficient reading remediation program should integrate both auditory-phonological and visuo-attentional interventions
Surface activated chemical ionization - Electrospray mass spectrometry in the analysis of urinary thiodiglycolic acid
RATIONALE
Thiodiglycolic acid (TDGA) is a urinary metabolite of the oxazaphosphorine class of chemotherapeutics, in particular of ifosfamide. Ifosfamide metabolism generates chloroacetaldehyde (CAA), a toxic compound associated with neurotoxicity, nephrotoxicity, urotoxicity and cardiotoxicity. CAA, in turn, interacts with cellular thiol groups leading to GSH depletion, cell death and generation of thiodiglycolic acid (TDGA), as a final product. TDGA is mainly excreted in the urine. The ability to accurately measure TDGA in urine, therefore, will be a useful way of monitoring the ifosfamide exposure during chemotherapy.
METHODS
TDGA in urine samples was measured with liquid chromatograpy coupled to mass spectrometry (LC-MS) by means of a novel Surface Activated Chemical Ionization - Electrospray (SACI-ESI) or a classical ESI ion source alone.
RESULTS
The SACI - ESI and ESI alone based methods for analysis of urinary TDGA were optimized and compared. A strong reduction in matrix effect together with enhanced quantification performances was obtained with the SACI \u2013 ESI when compared with the ESI. In particular, an increase in quantification precision (from 85 to 95%) and accuracy (from 59 to 90%) were observed, which allowed for optimal detection of TDGA.
CONCLUSIONS
The LC-SACI-ESI-MS approach provides a very sensitive and quantitative method for the analysis of TDGA. Thanks to sensitivity enhancement and matrix effect reduction, the SACI \u2013 ESI enables the use of a relatively low cost ion-trap mass spectrometer in the analysis of this toxicity biomarker in urine. Due to these characteristics, this approach would constitutes an invaluable tool in the clinical laboratory, for measuring TDGA and other toxicity related biomarkers of chemotherapy with proper sensitivity and accuracy
Earlier appearance of the ossification centre of the femoral head in breast fed versus formula fed infants.
Wind of change: Better air for microbial environmental control
Background: The COVID19 epidemic highlighted the importance of air in the transmission of pathogens. Air
disinfection is one of the key points to reduce the risk of transmission both in the health sector and in public, civil
and industrial environments. All bacteria and viruses tested to date can be inactivated by UV-C rays. Laboratory
tested UV-C systems are increasingly popular and proposed as effective technologies for air purification; few
studies have evaluated their performance in populated indoor environments. The aim of this investigation was to
evaluate the effectiveness of a UV-C disinfection system for air in a real working context.
Methods: This experimental study was conducted between December 2020 and February 2021 in an office of the
Department of Molecular and Developmental Medicine of the University of Siena, Italy. A pre-final version air
purifier (Cleaning Air T12), capable of treating 210 m3/h of air, was first tested for its ability to filter particulates
and reduce microbial air contamination in the absence of people. Subsequently, the experiments were conducted
in the presence of 3–5 subjects who worked for several hours in an office. During the tests, microbiological
samples of air were collected in real time, switching the system on and off periodically. Air samples were
collected and incubated on Petri dishes at 36 â—¦C and 22 â—¦C. Statistical analysis was performed with Stata 16
software assuming a significance level of 95%. An interpolating model was identified to describe the dynamics of
contamination reduction when the device operates.
Results: Preliminary tests showed a significant 62.5% reduction in Colony-Forming Units (CFUs) with 36 â—¦C
incubation. Reductions in the particulate component were also observed. In the main test, comparison of CFU
data, between the device-on phase (90 min) and the subsequent device-off phase (60 min), showed statistically
significant increase (p = 0.001) of environmental contamination passing from a mean of 86.6 (65.8–107.4) to
171.1 (143.9–198.3) CFU/m3, that is a rise of about 100%. The interpolating model exhibited a good fit of CFU
reduction trend with the device on.
Conclusions: The system, which mainly uses UV-C lamps for disinfection, was able to significantly reduce envi-
ronmental and human contamination in real time. Experimental tests have shown that as soon as the device is
switched off, after at least half an hour of operation, the healthiness of the air decreases drastically within 10
minutes, bringing the airborne microbial contamination (induced by the presence of operators in the environ-
ment) to levels even higher than 150% of the last value with the device on. Re-engineering strategies for system
improvement were also discusse
Epidemiology of Toxoplasma and CMV serology and of GBS colonization in pregnancy and neonatal outcome in a Sicilian population
Background: Aim of our study is to analyze the immunological status in pregnancy for two main TORCH agents, Toxoplasma and Cytomegalovirus (CMV), and the results of group B streptococcus (GBS) screening, assessing the risk for congenital infection in a population from Palermo, Italy.
Methods: We retrospectively analyzed the medical records of all inborn live newborns who were born in our division during 2012, gathering information about the mother, the pregnancy and neonatal hospitalization at birth. Whenever data were available, we categorized the serologic status of the mothers for Toxoplasma and CMV. We also considered the results of rectal and vaginal swabs for GBS. We compared the results in Italian and immigrant mothers. The neonatal outcome was evaluated in all cases at risk.
Results: Prevalence of anti-Toxo IgG antibodies was 17.97%, and was significantly higher in immigrant women (30% vs 16.4% in Italian women; p = 0.0008). Prevalence of anti-CMV IgG antibodies was 65.87%. Again, it was significantly higher in immigrant women (91.4% vs 62.5%, p = 3.31e-08). We compared those data with a previous study performed in our hospital in 2005-2006, and found that the prevalence of anti-Toxoplasma and anti-CMV antibodies in our population has remained stable, both in the immigrant and in the local population. Seroconversion rates and neonatal infections were rare: no seroconversions were observed for Toxoplasma, 4 seroconversions for CMV. One neonatal Toxoplasma infection and two neonatal CMV infections were documented. In some cases with dubious patterns or probable persistence of IgM, we performed additional tests and follow-up. Vaginal and rectal swabs were positive for GBS in 7.98% of cases, with no significant difference between the Italian and the immigrant population. No GBS neonatal sepsis was documented.
Conclusions: The prevalence of Toxoplasma IgG antibodies in pregnant women was low in our population, if compared with European countries and with other parts of Italy, and is significantly higher in immigrant women. The prevalence of CMV IgG antibodies was intermediate if compared to other countries, and it was higher in immigrant women. GBS positivity was low, and comparable in Italian and immigrant mothers. Neonatal infection was rare for all these agents
Transcriptome changes induced by Arbuscular mycorrhizal symbiosis in leaves of durum wheat (Triticum durum Desf.) promote higher salt tolerance
The salinity of soil is a relevant environmental problem around the world, with climate change raising its relevance, particularly in arid and semiarid areas. Arbuscular Mycorrhizal Fungi (AMF) positively affect plant growth and health by mitigating biotic and abiotic stresses, including salt stress. The mechanisms through which these benefits manifest are, however, still unclear. This work aimed to identify key genes involved in the response to salt stress induced by AMF using RNA-Seq analysis on durum wheat (Triticum turgidum L. subsp. durum Desf. Husn.). Five hundred sixty-three differentially expressed genes (DEGs), many of which involved in pathways related to plant stress responses, were identified. The expression of genes involved in trehalose metabolism, RNA processing, vesicle trafficking, cell wall organization, and signal transduction was significantly enhanced by the AMF symbiosis. A downregulation of genes involved in both enzymatic and non-enzymatic oxidative stress responses as well as amino acids, lipids, and carbohydrates metabolisms was also detected, suggesting a lower oxidative stress condition in the AMF inoculated plants. Interestingly, many transcription factor families, including WRKY, NAC, and MYB, already known for their key role in plant abiotic stress response, were found differentially expressed between treatments. This study provides valuable insights on AMF-induced gene expression modulation and the beneficial effects of plant-AMF interaction in durum wheat under salt stress
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