112 research outputs found
Optimising the observation of optical kilonovae with medium size telescopes
We consider the optimisation of the observing strategy (cadence, exposure
time and filter choice) using medium size (2-m class) optical telescopes in the
follow-up of kilonovae localised with arcminute accuracy to be able to
distinguish among various kilonova models and viewing angles. To develop an
efficient observation plan, we made use of the synthetic light curves obtained
with the Monte Carlo radiative transfer code POSSIS for different kilonova
models and as a function of different viewing angles and distances. By adding
the appropriate photon counting noise to the synthetic light curves, we
analysed four alternative sequences having the same total time exposure of 8
hours, with different time windows (0.5, 1, 2, 4 h), each with , , and
filters, to determine the observing sequence that maximises the chance of a
correct identification of the model parameters. We suggest to avoid filter
and to avoid the use of colour curves. We also found that, if the error on
distance is 2%, 0.5, 1, 2-hour time window sequences are equivalent, so
we suggest to use 2-hour one, because it has 1 day cadence, so it can be easily
realised. When the distance of the source is unknown, 0.5 h time window
sequence is preferable.Comment: 9 pages, 8 figures, published in MNRA
Copper-modified carbon nano-onions as electrode modifiers for the electroanalysis of the antiretroviral drug Efavirenz
The high prescription and consumption rate of antiretroviral drugs (ARV) such as Efavirenz (EFV) in South Africa
for the treatment of the human immunodeficiency virus (HIV) has resulted in its presence in wastewater and
surface water. Herein we report the electroanalysis of EFV at oxidised boron-nitrogen doped carbon nano-onions
(oxi-BNCNO) and microscale branched copper cluster (CuC) modified glassy carbon electrodes. Potentiostatic
electrodeposition of CuC on the oxi-BNCNO/GCE platform resulted in a stable and electrocatalytic surface that
accelerated electron transfer between the analyte and the CuC/oxi-BNCNO/GCE surface, making quantification
efficient. The electroactive surface area of CuC/oxi-BNCNO/GCE was estimated as being 3 times higher than bare
GCE and twice that of oxi-BNCNO/GCE. The electrooxidation of EFV on a CuC/oxi-BNCNO/GCE sensor resulted
in a pH-dependant anodic peak in the potential range of 0.8 to 1.2 V vs Ag/AgCl (3M KCl). The EFV voltammetric
signal increased linearly with increasing concentration of EFV in the linear dynamic range (LDR) of 0.01 – 1.0 µM
and 0.5 – 20 µM with a limit of detection (LOD) and quantification (LOQ) of 1.2 and 3.97 nM, respectively.
Moreover, the sensor had a sensitivity of 23 µA • cm− 2 • µM− 1 and was selective to 100-fold of interferents
including heavy metal ions and other ARVs with the exception of high concentrations of nevirapine. The
developed electroanalytical method was successfully applied for the determination of EFV in real samples such as
wastewater influent and effluent, drinking/tap water, and a pharmaceutical formulation with recovery ranging
from 97.8% to 109.5%
GRB minimum variability timescale with Insight-HXMT and Swift: implications for progenitor models, dissipation physics and GRB classifications
The dissipation process of GRB prompt emission is still unknown. Study of
temporal variability may provide a unique way to discriminate the imprint of
the inner engine activity from geometry and propagation related effects. We
define the minimum variability timescale (MVT) as the shortest duration of
individual pulses that shape a light curve for a sample of GRBs and test
correlations with peak luminosity, Lorentz factor, and jet opening angle. We
compare these correlations with predictions from recent numerical simulations
for a relativistic structured -- possibly wobbling -- jet and assess the value
of MTV as probe of prompt-emission physics. We used the peak detection
algorithm mepsa to identify the shortest pulse within a GRB time history and
estimate its full width half maximum (FWHM). We applied this framework to two
sets of GRBs: Swift (from 2005 to July 2022) and Insight-HXMT (from June 2017
to July 2021, including 221009A). We then selected 401 GRBs with measured z to
test for correlations. On average short GRBs have significantly shorter MVT
than long GRBs. The MVT distribution of short GRBs with extended emission such
as 060614 and 211211A is compatible only with that of short GRBs. This provides
a new clue on the progenitor's nature. The MVT for long GRBs anticorrelates
with peak luminosity. We confirm the anticorrelation with the Lorentz factor
and find a correlation with the jet opening angle as estimated from the
afterglow, along with an inverse correlation with the number of pulses. The MVT
can identify the emerging putative new class of long GRBs that are suggested to
be produced by compact binary mergers. For otherwise typical long GRBs, the
different correlations between MVT and peak luminosity, Lorentz factor, jet
opening angle, and number of pulses can be explained within the context of
structured, possibly wobbling, weakly magnetised relativistic jets.
(summarised)Comment: 18 pages, 15 figures, accepted by A&
Identification of thyroid tumor cell vulnerabilities through a siRNA-based functional screening
The incidence of thyroid carcinoma is rapidly increasing. Although generally associated with good prognosis, a fraction of thyroid tumors are not cured by standard therapy and progress to aggressive forms for which no effective treatments are currently available. In order to identify novel therapeutic targets for thyroid carcinoma, we focused on the discovery of genes essential for sustaining the oncogenic phenotype of thyroid tumor cells, but not required to the same degree for the viability of normal cells (non-oncogene addiction paradigm). We screened a siRNA oligonucleotide library targeting the human druggable genome in thyroid cancer BCPAP cell line in comparison with immortalized normal human thyrocytes (Nthy-ori 3-1). We identified a panel of hit genes whose silencing interferes with the growth of tumor cells, while sparing that of normal ones. Further analysis of three selected hit genes, namely Cyclin D1, MASTL and COPZ1, showed that they represent common vulnerabilities for thyroid tumor cells, as their inhibition reduced the viability of several thyroid tumor cell lines, regardless the histotype or oncogenic lesion. This work identified non-oncogenes essential for sustaining the phenotype of thyroid tumor cells, but not of normal cells, thus suggesting that they might represent promising targets for new therapeutic strategies
Primary biliary cirrhosis
Primary biliary cirrhosis (PBC) is an immune-mediated chronic cholestatic liver disease with a slowly progressive course. Without treatment, most patients eventually develop fibrosis and cirrhosis of the liver and may need liver transplantation in the late stage of disease. PBC primarily affects women (female preponderance 9–10:1) with a prevalence of up to 1 in 1,000 women over 40 years of age. Common symptoms of the disease are fatigue and pruritus, but most patients are asymptomatic at first presentation. The diagnosis is based on sustained elevation of serum markers of cholestasis, i.e., alkaline phosphatase and gamma-glutamyl transferase, and the presence of serum antimitochondrial antibodies directed against the E2 subunit of the pyruvate dehydrogenase complex. Histologically, PBC is characterized by florid bile duct lesions with damage to biliary epithelial cells, an often dense portal inflammatory infiltrate and progressive loss of small intrahepatic bile ducts. Although the insight into pathogenetic aspects of PBC has grown enormously during the recent decade and numerous genetic, environmental, and infectious factors have been disclosed which may contribute to the development of PBC, the precise pathogenesis remains enigmatic. Ursodeoxycholic acid (UDCA) is currently the only FDA-approved medical treatment for PBC. When administered at adequate doses of 13–15 mg/kg/day, up to two out of three patients with PBC may have a normal life expectancy without additional therapeutic measures. The mode of action of UDCA is still under discussion, but stimulation of impaired hepatocellular and cholangiocellular secretion, detoxification of bile, and antiapoptotic effects may represent key mechanisms. One out of three patients does not adequately respond to UDCA therapy and may need additional medical therapy and/or liver transplantation. This review summarizes current knowledge on the clinical, diagnostic, pathogenetic, and therapeutic aspects of PBC
Post-Traumatic Stress Related to Pediatric Illness and Injury
The chapter describes the peculiarities of individual and family responses to the experience of children's medical illness, injury and medical treatment as referred to the construct of traumatic stress. On the basis of the most recent literature, author exoplores the precitive role of a series of factors considered to favor or to inhibit the onset of traumatic stress in peditric illness and injuries; these include: sociodemographic variables preceding the traumatic event; the objective nature of the traumatic event and its subjective evaluation; acute distress and physiological arousal reactions; and finally the parent-child relationship, family functioning and social support
Negative Co-Parenting and Children's Adjustment: The Role of Children's Appraisals and Triangulation
Existing literature has outlined how negative co-parenting could affect children's adjustment through children's subjective appraisals and triangulation. However, no studies have investigated whether children's cognitive appraisals and two distinct forms of children's triangulation (feelings and involvement) could be serial mediators of the associations between negative co-parenting and children's adjustment. Mediation analyses were performed using a sample of 125 Italian families of children aged 8-14. Results showed that negative co-parenting was linked to children's threat and self-blame appraisals. Data also suggested how both children's subjective appraisals (threat and self-blame) were associated with the two forms of children's triangulation (direct involvement and subjective triangulation). Finally, the results indicated two specific pathways for the serial mediation of children's cognitive appraisals and triangulation in the association between negative coparenting and children's adjustment. On the one hand, subjective triangulation predicts children's internalizing behaviors. On the other hand, triangulation involvement promotes children's externalizing behaviors
- …