687 research outputs found
Optimization of Track Etched Makrofol Etching Conditions for Short-term Exposure Duration
AbstractExposure time of nuclear track detectors at humid environments is normally limited to a few weeks because filter used to avoid humidity is not completely waterproof and, after several months, some parts of detector start to degrade. In other really extreme measurement conditions, like high aerosol content, high or low temperatures, etc., the exposure time also requires a reduction. Then detector detection limit becomes a problem, unless radon concentrations were high. In those cases where radon levels are not high enough a better detection efficiency is required. In our laboratory we use passive detectors based on the track etched Makrofol DE foil covered with aluminized Mylar and they are analyzed by means of an electrochemical etching. Our standard etching conditions allow analyzing detectors generally exposed for periods between three and six months. We have optimized our etching conditions to reduce the exposure time down to a month for common radon concentration values
Complexes of Pd(II) and Pt(II) with 9-Aminoacridine: Reactions with DNA and Study of Their Antiproliferative Activity
Four new metal complexes {M = Pd(II) or Pt(II)} containing the ligand 9-aminoacridine (9AA) were
prepared. The compounds were characterized by FT-IR and 1H, 13C, and 195Pt NMR spectroscopies. Crystal structure of the palladium complex of formulae [Pd(9AA)(μ-Cl)]2 · 2DMF was determined by X-ray diffraction. Two 9-acridine molecules in the imine form bind symmetrically to the metal ions in a bidentate fashion through the imine nitrogen atom and the C(1) atom of the aminoacridine closing a new five-membered ring. By reaction with phosphine or pyridine, the Cl bridges broke and compounds with general formulae [Pd(9AA)Cl(L)] (where L = PPh3 or py) were formed. A mononuclear complex of platinum of formulae [Pt(9AA)Cl(DMSO)] was
also obtained by direct reaction of 9-aminoacridine and the complex [PtCl2(DMSO2]. The capacity of the compounds to modify the secondary and tertiary structures of DNA was evaluated by means of circular dichroism and electrophoretic mobility. Both palladium and platinum compounds proved active in the modification of both the secondary and tertiary DNA structures. AFM images showed noticeable modifications of the morphology of the plasmid pBR322 DNA by the
compounds probably due to the intercalation of the complexes between base pairs of the DNA molecule. Finally, the palladium complex was tested for antiproliferative activity against three different human tumor cell lines. The results suggest that the palladium complex of formula [Pd(9AA)(μ-Cl)]2 has significant antiproliferative activity, although it is less active than cisplatin
Pd(II) and Pt(II) Complexes of Schiff Thiobases Derived From 2-Carbonylpyridine
Pd(ll) and Pt(ll) complexes of three series of Schiff thiobases derived from 2- carbonylpyridine have been synthesized and characterized. The crystal structure of the Pt(ll)
derivative of methyl-3-(2-pyridylmethylene)hydrazinecarbodithioate (HFp) was resolved. The ligand
coordinates the platinum ion in tridentate fashion by heterocycle and imine nitrogen and
thiocarbonyl sulfur. The fourth ligand is a chloride ion. The structure of the complexes is suitable for
the formation of monofunctional adducts with DNA. Studies on the interaction of the complexes
with Calf thymus DNA by CD reveal modifications in the B form of lineal DNA. Interaction with
plasmid DNA was also confirmed in the images obtained by atomic force microscopy
Synthesis of merlinoite from Chinese coal fly ashes and its potential utilization as slow release K-fertilizer
This study focuses on the synthesis of merlinoite from Chinese coal fly ashes by KOH direct conversion method, with special emphasis on the application of synthetic merlinoite as fertilizer. These fly ashes were collected from two pulverized-coal combustion (PCC) power plants in Xinjiang, Northwest China. The synthesis results are influenced by fly ash characteristics and different synthesis conditions (KOH solution concentrations, activation temperature, time, and KOH/fly ash ratios). A high quality merlinoite-rich product was synthesized under optimal activation conditions (KOH concentration of 5 M, activation temperature of 150 °C, activation time of 8 h and KOH/fly ash ratio of 2 l/kg), with a cation exchange capacity (CEC) of 160 cmol kg−1. The synthetic merlinoite is proved to be an efficient slow release K-fertilizer for plant growth, indicating that it can be widely used for high-nutrient demanding crops growing in nutrient-limited soils and for large-area poor soil amendment in opencast coal mine areas around the power plants that will substantially grow with the increasing coal combustion in Xinjiang in the near future
MAGIC Observations of the Nearby Short Gamma-Ray Burst GRB 160821B
Acciari, A. V., et al.The coincident detection of GW170817 in gravitational waves and electromagnetic radiation spanning the radio to MeV gamma-ray bands provided the first direct evidence that short gamma-ray bursts (GRBs) can originate from binary neutron star (BNS) mergers. On the other hand, the properties of short GRBs in high-energy gamma-rays are still poorly constrained, with only ∼20 events detected in the GeV band, and none in the TeV band. GRB 160821B is one of the nearest short GRBs known at z = 0.162. Recent analyses of the multiwavelength observational data of its afterglow emission revealed an optical-infrared kilonova component, characteristic of heavy-element nucleosynthesis in a BNS merger. Aiming to better clarify the nature of short GRBs, this burst was automatically followed up with the MAGIC telescopes, starting from 24 s after the burst trigger. Evidence of a gamma-ray signal is found above ∼0.5 TeV at a significance of ∼ 3σ during observations that lasted until 4 hr after the burst. Assuming that the observed excess events correspond to gamma-ray emission from GRB 160821B, in conjunction with data at other wavelengths, we investigate its origin in the framework of GRB afterglow models. The simplest interpretation with one-zone models of synchrotron-self-Compton emission from the external forward shock has difficulty accounting for the putative TeV flux. Alternative scenarios are discussed where the TeV emission can be relatively enhanced. The role of future GeV-TeV observations of short GRBs in advancing our understanding of BNS mergers and related topics is briefly addressed.We would like to thank the Instituto de Astrofísica de Canarias
for the excellent working conditions at the Observatorio del
Roque de los Muchachos in La Palma. The financial support of
the German BMBF and MPG; the Italian INFN and INAF; the
Swiss National Fund SNF; the ERDF under the Spanish
MINECO (FPA2017-87859-P, FPA2017-85668-P, FPA2017-
82729-C6-2-R, FPA2017-82729-C6-6-R, FPA2017-82729-C6-5-
R, AYA2015-71042-P, AYA2016-76012-C3-1-P, ESP2017-
87055-C2-2-P, FPA2017-90566-REDC); the Indian Department
of Atomic Energy; the Japanese ICRR, the University of Tokyo,
JSPS, and MEXT; the Bulgarian Ministry of Education and
Science, National RI Roadmap Project DO1-268/16.12.2019 and
the Academy of Finland grant No. 320045 is gratefully
acknowledged. This work was also supported by the Spanish
Centro de Excelencia “Severo Ochoa” SEV-2016-0588, SEV2015-0548 and SEV-2012-0234, the Unidad de Excelencia
“María de Maeztu” MDM-2014-0369 and the “la Caixa”
Foundation (fellowship LCF/BQ/PI18/11630012), by the Croatian Science Foundation (HrZZ) Project IP-2016-06-9782 and the
University of Rijeka Project 13.12.1.3.02, by the DFG Collaborative Research Centers SFB823/C4 and SFB876/C3, the
Polish National Research Centre grant UMO-2016/22/M/ST9/
00382 and by the Brazilian MCTIC, CNPq and FAPERJ. K.N. is
thankful for the support by Marie Skłodowska-Curie actions (H2020-MSCA-COFUND-2014, Project P-Sphere GA 665919),
and JSPS KAKENHI grant No. JP20KK0067 from MEXT,
Japan. L.N. acknowledges funding from the European Union’s
Horizon 2020 research and innovation program under the Marie
Skłodowska-Curie grant agreement No. 664931. S.I. is supported
by JSPS KAKENHI grant No. JP17K05460 from MEXT, Japan,
and the RIKEN iTHEMS program
Search for Very High-energy Emission from the Millisecond Pulsar PSR J0218+4232
Acciari, V. A., et al. (MAGIC Collaboration)PSR J0218+4232 is one of the most energetic millisecond pulsars known and has long been considered as one of the best candidates for very high-energy (VHE; >100 GeV) ?-ray emission. Using 11.5 yr of Fermi Large Area Telescope (LAT) data between 100 MeV and 870 GeV, and ~90 hr of Major Atmospheric Gamma Imaging Cherenkov (MAGIC) observations in the 20 GeV to 20 TeV range, we searched for the highest energy ?-ray emission from PSR J0218+4232. Based on the analysis of the LAT data, we find evidence for pulsed emission above 25 GeV, but see no evidence for emission above 100 GeV (VHE) with MAGIC. We present the results of searches for ?-ray emission, along with theoretical modeling, to interpret the lack of VHE emission. We conclude that, based on the experimental observations and theoretical modeling, it will remain extremely challenging to detect VHE emission from PSR J0218+4232 with the current generation of Imaging Atmospheric Cherenkov Telescopes, and maybe even with future ones, such as the Cherenkov Telescope Array.The financial support of the
German BMBF, MPG and HGF; the Italian INFN and INAF; the
Swiss National Fund SNF; the ERDF under the Spanish Ministerio
de Ciencia e Innovación (MICINN) (FPA2017-87859-P,
FPA2017-85668-P, FPA2017-82729-C6-5-R, FPA2017-90566-
REDC, PID2019-104114RB-C31, PID2019-104114RB-C32,
PID2019-105510GB-C31,PID2019-107847RB-C41, PID2019-
107847RB-C42, PID2019-107988GB-C22); the Indian Department of Atomic Energy; the Japanese ICRR, the University of
Tokyo, JSPS, and MEXT; the Bulgarian Ministry of Education
and Science, National RI Roadmap Project DO1-268/16.12.2019
and the Academy of Finland grant No. 320045 is gratefully
acknowledged. This work was also supported by the Spanish
Centro de Excelencia “Severo Ochoa” SEV-2016-0588 and
CEX2019-000920-S, and “María de Maeztu” CEX2019-000918-
M, the Unidad de Excelencia “María de Maeztu” MDM-2015-
0509-18-2 and the “la Caixa” Foundation (fellowship LCF/BQ/
PI18/11630012) and by the CERCA program of the Generalitat de
Catalunya; by the Croatian Science Foundation (HrZZ) Project IP2016-06-9782 and the University of Rijeka Project 13.12.1.3.02;
by the DFG Collaborative Research Centers SFB823/C4 and
SFB876/C3; the Polish National Research Centre grant UMO2016/22/M/ST9/00382; and by the Brazilian MCTIC, CNPq
and FAPERJ
Multiwavelength variability and correlation studies of Mrk 421 during historically low X-ray and γ-ray activity in 2015-2016
Acciari, V. A., et al. (MAGIC Collaboration)We report a characterization of the multiband flux variability and correlations of the nearby (z = 0.031) blazar Markarian 421 (Mrk 421) using data from Metsähovi, Swift, Fermi-LAT, MAGIC, FACT, and other collaborations and instruments from 2014 November till 2016 June. Mrk 421 did not show any prominent flaring activity, but exhibited periods of historically low activity above 1 TeV (F>1 TeV 0.1 TeV) γ-rays, which, despite the low activity, show a significant positive correlation with no time lag. The HRkeV and HRTeV show the harder-when-brighter trend observed in many blazars, but the trend flattens at the highest fluxes, which suggests a change in the processes dominating the blazar variability. Enlarging our data set with data from years 2007 to 2014, we measured a positive correlation between the optical and the GeV emission over a range of about 60 d centred at time lag zero, and a positive correlation between the optical/GeV and the radio emission over a range of about 60 d centred at a time lag of 43+9-6 d. This observation is consistent with the radio-bright zone being located about 0.2 parsec downstream from the optical/GeV emission regions of the jet. The flux distributions are better described with a lognormal function in most of the energy bands probed, indicating that the variability in Mrk 421 is likely produced by a multiplicative process.The financial support of the German BMBF and MPG; the Italian INFN and INAF; the Swiss National Fund SNF; the ERDF under the Spanish MINECO (FPA2017-87859-P, FPA2017-85668-P, FPA2017-82729-C6-2-R, FPA2017-82729-C6-6-R, FPA2017-82729-C6-5-R, AYA2015-71042-P, AYA2016-76012-C3-1-P, ESP2017-87055-C2-2-P, FPA2017-90566-REDC); the Indian Department of Atomic Energy; the Japanese ICRR, the University of Tokyo, JSPS, and MEXT; the Bulgarian Ministry of Education and Science, National RI Roadmap Project DO1-268/16.12.2019 and the Academy of Finland grant nr. 320045 is gratefully acknowledged. This work was also supported by the Spanish Centro de Excelencia ‘Severo Ochoa’ SEV-2016-0588 and SEV-2015-0548, the Unidad de Excelencia ‘María de Maeztu’ MDM-2014-0369 and the ‘la Caixa’ Foundation (fellowship LCF/BQ/PI18/11630012), by the Croatian Science Foundation (HrZZ) Project IP-2016-06-9782 and the University of Rijeka Project 13.12.1.3.02, by the DFG Collaborative Research Centers SFB823/C4 and SFB876/C3, the Polish National Research Centre grant UMO-2016/22/M/ST9/00382 and by the Brazilian MCTIC, CNPq, and FAPERJ
Constraints on Supersymmetric Theories from
In the absence of any additional assumption it is natural to conjecture that
sizeable flavour-mixing mass entries, , may appear in the mass
matrices of the scalars of the MSSM, i.e. . This flavour
violation can still be reconciled with the experiment if the gaugino mass,
, is large enough, leading to a {\em gaugino dominance} framework
(i.e. ), which permits a remarkably model--independent
analysis. We study this possibility focussing our attention on the
decay. In this way we obtain very strong and general
constraints, in particular \frac{M_{1/2}^2}{\Delta m}\simgt 34\ {\rm TeV}. On
the other hand, we show that our analysis and results remain valid for values
of much larger than , namely for \frac{\Delta
m^2}{m^2}\simgt \frac{m^2} {10\ {\rm TeV^2}}, thus extending enormously their
scope of application. Finally, we discuss the implications for superstring
scenarios.Comment: 12 pages, Latex, 5 figures as uuencoded compressed postscript files,
uses psfig.st
The Sub-State Politics of Welfare in Italy: Assessing the Effect of Territorial Mobilization on the Development of Region-Specific Social Governance
This article demonstrates that the political mobilization of regional identities through the creation of regionalist parties has positively impacted on the development of region-specific models of welfare governance in Italy. This means that, in a decentralized country, the ‘centre-periphery’ cleavage may significantly influence the sub-state politics of welfare
Adjuvant dabrafenib and trametinib for patients with resected BRAF-mutated melanoma: DESCRIBE-AD real-world retrospective observational study
BRAF and MEK inhibitor, dabrafenib plus trametinib, adjuvant therapy is effective for high-risk resected melanoma patients with BRAF-V600 mutations. However, real-world evidence is limited. We aimed to determine the feasibility of this therapy in routine clinical practice. DESCRIBE-AD, a retrospective observational study, collected real-world data from 25 hospitals in Spain. Histologically confirmed and resected BRAF-mutated melanoma patients aged & GE;18 years who were previously treated with dabrafenib plus trametinib adjuvant therapy, were included. The primary objectives were treatment discontinuation rate and time to discontinuation. The secondary objectives included safety and efficacy. From October 2020 to March 2021, 65 patients were included. Dabrafenib and trametinib discontinuation rate due to treatment-related adverse events (TRAEs) of any grade was 9%. Other reasons for discontinuation included patients' decisions (6%), physician decisions (6%), unrelated adverse events (3%), disease progression (5%), and others (5%). The median time to treatment discontinuation was 9 months [95% confidence interval (CI), 5-11]. G3-4 TRAEs occurred in 21.5% of patients, the most common being pyrexia (3%), asthenia (3%), and diarrhoea (3%). Unscheduled hospitalisations and clinical tests occurred in 6 and 22% of patients, respectively. After 20-month median follow-up (95% CI, 18-22), 9% of patients had exitus due to disease progression, with a 12-month relapse-free survival and overall survival rates of 95.3% and 100%, respectively. Dabrafenib and trametinib adjuvant therapy proved effective for melanoma patients in a real-world setting, with a manageable toxicity profile. Toxicity frequencies were low leading to low incidence of unscheduled medical visits, tests, and treatment discontinuations
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