For utilizing silicon photomultipliers (SiPMs) in space experiments, we conducted irradiation experiments of SiPMs with protons and iron ions. In particular, the relationship between the leakage ...current and the radiation dose was investigated under various irradiation conditions to determine techniques of mitigating damage caused by radiation. The leakage current was approximately proportional to the dose; however, the proportionality constant did not significantly vary with the irradiation conditions. The effects of annealing after irradiation tests indicated no substantial decrease in the leakage current. Conversely, while the leakage current increased with the dose, the SiPMs continued to operate even after 5 krad of irradiation, which corresponds to several years of radiation exposure in space at altitudes of ~400 km to 500 km. The results obtained from these irradiation tests are used to characterize a hard X-ray (> 60 keV) detector for space-based applications. This detector couples an inorganic scintillator with a high light yield, such as CsI(Tl), to a SiPM.
Allogeneic hematopoietic stem cell transplantation (allo-HSCT) has curative potential against hematological malignancies. However, there are concerns about the associated risk of non-relapse ...mortality (NRM). We performed a retrospective single-center study to assess changes in outcomes after allo-HSCT and causes of NRM over three 5-year periods. The rates of 2-year NRM and overall survival (OS) were 16% and 59%, respectively. We found a significant decrease in NRM (P<0.001), with 2-year NRM of 26, 14 and 9%, and a significant increase in OS (P=0.005), with 2-year OS of 52%, 58% and 65%, over the three periods (1998-2002, 2003-2007 and 2008-2012), respectively. Of note, a steady improvement was observed in NRM, period by period, among patients aged 50 years or older, patients who underwent HSCT from an unrelated bone marrow donor and patients who underwent HSCT with a reduced-intensity conditioning regimen. Our data showed that the improved NRM can mainly be attributed to a decreased mortality related to infection after starting systemic steroid as GVHD treatment, and a decreased mortality related to organ failure.
•Cs2HfCl6 single crystal preparation by miniaturized and standard Bridgman methods.•Cs2HfCl6 single-phase proved by XRD measurements.•Room temperature optical, luminescence, and scintillation ...properties of Cs2HfCl6.•Room temperature photoluminescence and scintillation decay kinetics of Cs2HfCl6.
Time and cost effective methods are highly desirable in research and development of new scintillators. Modern techniques like micro-pulling down (μ-PD) are suitable for material screening but are unfit for the growth of some crystals. These crystals must be grown by different methods that are usually very time demanding. Modification of halide μ-PD apparatus by custom made elements allowed us to grow cesium hafnium chloride (Cs2HfCl6) by vertical Bridgman method (VB) with significantly reduced growth time. Structural and optical properties of samples prepared from as-grown crystals were studied and compared to crystals grown by standard VB method. The X-ray diffraction confirmed the formation of cesium hafnium chloride single-phase and natural cleavage of the crystals along the (1 1 1) crystallographic plane. Photoluminescence emission, excitation, absorption, and radioluminescence spectroscopy revealed that the optical quality of the crystals grown by modified VB method was comparable to the quality of the crystals grown by standard VB method. Therefore we can use samples prepared by modified VB to estimate and optimize the performance of Cs2HfCl6 based crystals in scintillation detectors. This setup allows the time and cost-effective material screening and it is a powerful tool for the development of new halide based single crystal scintillators.
Mobile ad hoc networks (MANETs) are usually formed without any major infrastructure. As a result, they are relatively vulnerable to malicious network attacks, and therefore, security is a more ...significant issue than infrastructure-based wireless networks. In MANETs, it is difficult to identify malicious hosts as the topology of the network dynamically changes. A malicious host can easily interrupt a route for which it is one of the forming nodes in the communication path. In the literature, there are several proposals to detect such malicious hosts inside the network. In those methods, a baseline profile, which is defined as per static training data, is usually used to verify the identity and the topology of the network, thus preventing any malicious host from joining the network. Since the topology of a MANET dynamically changes, the mere use of a static baseline profile is not efficient. In this paper, we propose a new anomaly-detection scheme based on a dynamic learning process that allows the training data to be updated at particular time intervals. Our dynamic learning process involves calculating the projection distances based on multidimensional statistics using weighted coefficients and a forgetting curve. We use the network simulator 2 (ns-2) system to conduct the MANET simulations and consider scenarios for detecting five types of attacks. The simulation results involving two different networks in size show the effectiveness of the proposed techniques.
This research deals with the luminescence and physical properties of Gd3(Ga,Al)5O12:Ce single crystal set and it is a complementary study to analogous (Y,Gd)3Al5O12:Ce and (Gd,Lu)3Al5O12:Ce single ...crystal sets. Those three groups of materials show similar luminescence and physical properties. In this research, the influence of substitution Ga for Al in Gd3(Ga,Al)5O12:Ce single crystals on the luminescence and scintillation characteristics as well as thermodynamical stability of the garnet phase is studied, and it is compared to (Y,Gd)3Al5O12:Ce and (Gd,Lu)3Al5O12:Ce single crystal sets. The unbalanced substitution Ga for Al makes garnet phase thermodynamically unstable and leads to the formation of the multiphase system with luminescence centers in UV and visible spectral ranges. The wavelength-dispersive X-ray spectroscopy, X-ray powder diffraction analysis, photoluminescence and decay kinetic measurements reviled all phase types within multiphase crystals. Temperature dependent measurements were applied to determine the quenching mechanism for Ce3+ luminescence. The timing characteristics are studied as the function of Ga content.
•Instability of the garnet phase and formation of the secondary phase inclusions discussed.•Temperature dependence of the decay time of Ce3+ emissions in garnet phase studied.•Energy transfer processes between secondary phase inclusion and target garnet phase discussed.
Gene mutations were found in acute myeloid leukemia (AML) and their importance has been noted. To clarify the importance and stability of mutations, we examined gene mutations in paired samples at ...diagnosis and relapse of 34 adult AML patients. Five acquired gene mutations were detected at relapse. Of the 45 gene mutations at diagnosis, 11 of them were lost at relapse. The acquired mutations at relapse were all class I mutations as Fms-like tyrosine kinase 3 (FLT3) and rat sarcoma viral oncogene homolog (RAS) mutations. The disappeared mutations at relapse were 3 of 11 internal tandem duplications of FLT3 (FLT3-ITD) (27.3%), 3 of 3 FLT3 tyrosine kinase domain (FLT3-TKD) (100%), 3 of 13 Nucleophosmin 1 (23.1%) and 2 of 5 CCAAT/enhancer-binding protein-α (40%) mutations. However, epigenetics-modifying gene (DNMT3a, TET2 and IDH1/2) mutations had no change between diagnosis and relapse samples, and may become minimal residual disease marker. The frequency of FLT3-ITD at relapse in patients with DNMT3a mutation at diagnosis is significantly higher than those in patients without them (P=0.001). Moreover, the high frequency of FLT3-ITD at relapse is also seen in AML cases that initially present with any epigenetics-modifying gene mutations (P<0.001). Our results indicate that epigenetics-modifying gene mutations may cause genetic instability and induce FLT3-ITD, leading to resistance to therapy and relapse.
We conducted a comprehensive analysis of 28 recurrently mutated genes in acute myeloid leukemia (AML) in 271 patients with de novo AML. Co-mutations were frequently detected in the intermediate ...cytogenetic risk group, at an average of 2.76 co-mutations per patient. When assessing the prognostic impact of these co-mutations in the intermediate cytogenetic risk group, overall survival (OS) was found to be significantly shorter (P=0.0006) and cumulative incidence of relapse (CIR) significantly higher (P=0.0052) in patients with complex molecular genetic abnormalities (CMGAs) involving three or more mutations. This trend was marked even among patients aged ⩽65 years who were also FLT3-ITD (FMS-like tyrosine kinase 3 internal tandem duplications)-negative (OS: P=0.0010; CIR: P=0.1800). Moreover, the multivariate analysis revealed that CMGA positivity was an independent prognostic factor associated with OS (P=0.0007). In stratification based on FLT3-ITD and CEBPA status and 'simplified analysis of co-mutations' using seven genes that featured frequently in CMGAs, CMGA positivity retained its prognostic value in transplantation-aged patients of the intermediate cytogenetic risk group (OS: P=0.0002. CIR: P<0.0001). In conclusion, CMGAs in AML were found to be strong independent adverse prognostic factors and simplified co-mutation analysis to have clinical usefulness and applicability.
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