BACKGROUND
Serologic determination of the Vel– phenotype is challenging due to variable Vel expression levels. In this study we investigated the genetic basis for weak Vel expression levels and ...developed a high‐throughput genotyping assay to detect Vel– donors.
STUDY DESIGN AND METHODS
In 548 random Caucasian and 107 Vel+w donors genetic variation in the SMIM1 gene was studied and correlated to Vel expression levels. A total of 3366 Caucasian, 621 black, and 333 Chinese donors were screened with a high‐throughput genotyping assay targeting the SMIM1*64_80del allele.
RESULTS
The Vel+w phenotype is in most cases caused by the presence of one SMIM1 allele carrying the major allele of the rs1175550 SNP in combination with a SMIM1*64_80del allele or in few cases caused by the presence of the SMIM1*152T>A or SMIM1*152T>G allele. In approximately 6% of Vel+w donors genetic factors in SMIM1 could not explain the weak expression. We excluded the possibility that lack of expression of another blood group system was correlated with weak Vel expression levels. Furthermore, using a high‐throughput Vel genotyping assay we detected two Caucasian Vel– donors.
CONCLUSION
Weak Vel expression levels are caused by multiple genetic factors in SMIM1 and probably also by other genetic or environmental factors. Due to the variation in Vel expression levels, serologic determination of the Vel– phenotype is difficult and a genotyping assay targeting the c.64_80del deletion in SMIM1 should be used to screen donors for the Vel– phenotype.
The central region of the Milky Way is one of the foremost locations to look for dark matter (DM) signatures. We report the first results on a search for DM particle annihilation signals using new ...observations from an unprecedented gamma-ray survey of the Galactic Center (GC) region, i.e., the Inner Galaxy Survey, at very high energies (& GSIM;100 GeV) performed with the H.E.S.S. array of five ground-based Cherenkov telescopes. No significant gamma-ray excess is found in the search region of the 2014-2020 dataset and a profile likelihood ratio analysis is carried out to set exclusion limits on the annihilation cross section (sigma v). Assuming Einasto and Navarro-Frenk-White (NFW) DM density profiles at the GC, these constraints are the strongest obtained so far in the TeV DM mass range. For the Einasto profile, the constraints reach (sigma v) values of 3.7 x 10-26 cm3 s-1 for 1.5 TeV DM mass in the W+W- annihilation channel, and 1.2 x 10-26 cm3 s-1 for 0.7 TeV DM mass in the tau+tau- annihilation channel. With the H.E.S.S. Inner Galaxy Survey, ground-based gamma-ray observations thus probe (sigma v) values expected from thermal-relic annihilating TeV DM particles.
BACKGROUND
The RHCE allele is highly polymorphic; more than 60 variants have been described leading to diminished expression of C, c, E, and e antigens. Not much is known about the prevalence of RHCE ...variants in the Chinese population. Individuals carrying a variant are at risk to develop alloantibodies in response to mismatched pregnancy or transfusion. In this study, phenotyping and genotyping of the RHCE allele in Chinese donors revealed a new clinically relevant mutation.
STUDY DESIGN AND METHODS
Blood samples from 200 D– and 200 D+ Chinese donors were analyzed by the RH multiplex ligation–dependent probe amplification (MLPA) assay and compared to serologically typed RhCE phenotypes, when available. All exons of the RHCE gene were sequenced in samples with aberrant genotyping results. The phenotype of the new variant RHCE allele was tested by transducing cultured human erythroblasts.
RESULTS
Aberrant copy numbers for Exon 2 of the RHCE gene were discovered by MLPA in six D– donors (6/200), but not in D+ donors (0/200). Sequencing of the RHCE gene in these six donors identified a new variant RHCE*ce308C>T (p.103Pro>Leu) allele with an allele frequency of 0.015 within the D– individuals in this study. This variant was not detected in D+ individuals showing linkage with the D– haplotype. Serologically weak C expression and loss of c expression was demonstrated on donor red blood cells. In vitro transfection studies of the RHCE*ce308T variant in cDe/ce and CDe/CDe erythroblasts confirmed that the variant is associated with anti‐C reactivity while abolishing c expression.
CONCLUSION
Genotyping of individuals carrying this variant by standard RHCE genotyping might falsely predict a C– phenotype or a c+ phenotype. This new variant should be taken into account in RHCE genotyping assays designed for the Chinese population.
The Large Magellanic Cloud, a satellite galaxy of the Milky Way, has been observed with the High Energy Stereoscopic System (H.E.S.S.) above an energy of 100 billion electron volts for a deep ...exposure of 210 hours. Three sources of different types were detected: the pulsar wind nebula of the most energetic pulsar known, N 157B; the radio-loud supernova remnant N 132D; and the largest nonthermal x-ray shell, the superbubble 30 Dor C. The unique object SN 1987A is, unexpectedly, not detected, which constrains the theoretical framework of particle acceleration in very young supernova remnants. These detections reveal the most energetic tip of a γ-ray source population in an external galaxy and provide via 30 Dor C the unambiguous detection of γ-ray emission from a superbubble.
The extragalactic background light (EBL) is the diffuse radiation with the second highest energy density in the Universe after the cosmic microwave background. The aim of this study is the ...measurement of the imprint of the EBL opacity to γ-rays on the spectra of the brightest extragalactic sources detected with the High Energy Stereoscopic System (H.E.S.S.). The originality of the method lies in the joint fit of the EBL optical depth and of the intrinsic spectra of the sources, assuming intrinsic smoothness. Analysis of a total of ~105γ-ray events enables the detection of an EBL signature at the 8.8σ level and constitutes the first measurement of the EBL optical depth using very-high energy (E > 100 GeV) γ-rays. The EBL flux density is constrained over almost two decades of wavelengths 0.30 μm, 17 μm and the peak value at 1.4 μm is derived as λFλ = 15 ± 2stat ± 3sys nW m-2 sr-1.
The measurement of an excess in the cosmic-ray electron spectrum between 300 and 800 GeV by the ATIC experiment has – together with the PAMELA detection of a rise in the positron fraction up to ...≈100 GeV – motivated many interpretations in terms of dark matter scenarios; alternative explanations assume a nearby electron source like a pulsar or supernova remnant. Here we present a measurement of the cosmic-ray electron spectrum with H.E.S.S. starting at 340 GeV. While the overall electron flux measured by H.E.S.S. is consistent with the ATIC data within statistical and systematic errors, the H.E.S.S. data exclude a pronounced peak in the electron spectrum as suggested for interpretation by ATIC. The H.E.S.S. data follow a power-law spectrum with spectral index of 3.0±0.1(stat.)± 0.3(syst.), which steepens at about 1 TeV.
Observations of astrophysical transients have brought many novel discoveries and provided new insights into the physical processes at work under extreme conditions in the Universe. Multi-wavelength ...and multi-messenger observations of variable objects require dedicated procedures and follow-up systems capable of digesting and reacting to external alerts to execute coordinated follow-up campaigns. The main functions of such follow-up systems are the processing, filtering, and ranking of the incoming alerts, the fully automated rapid execution of the observations according to an observation strategy tailored to the instrument, and real-time data analysis with feedback to the operators and other instruments. The High Energy Stereoscopic System (H.E.S.S.) has been searching for transient phenomena since its inauguration in 2003. In this paper, we describe the transients follow-up system of H.E.S.S. which became operational in 2016. The system allows H.E.S.S. to conduct a more versatile, optimised, and largely autonomous transient follow-up programme, combining all major functionalities in one systematic approach. We describe the design, central functionalities, and interfaces of the follow-up system in general and its three main components in detail: the Target of Opportunity (ToO) alert system, the data acquisition and central control system, and the real-time analysis. We highlight architectural decisions and features that enable fully automatic ToO follow-up and indicate key performance metrics of the subsystems. We discuss the system's capabilities and highlight the need for a fine-tuned interplay of the different subsystems in order to react quickly and reliably. Lessons learnt from the development, integration, and operation of the follow-up system are reviewed in light of new and large science infrastructures and associated challenges in this exciting new era of inter-operable astronomy.
The High Energy Stereoscopic System (H.E.S.S.) is one of the three arrays of imaging atmospheric Cherenkov telescopes (IACTs) currently in operation. It is composed of four 12-meter telescopes and a ...28-meter one, and is sensitive to gamma rays in the energy range ~ 30 GeV – 100 TeV. The cameras of the 12-m telescopes recently underwent a substantial upgrade, with the goal of improving their performance and robustness. The upgrade involved replacing all camera components except for the photomultiplier tubes (PMTs). This meant developing new hardware for the trigger, readout, power, cooling and mechanical systems, and new software for camera control and data acquisition. Several novel technologies were employed in the cameras: the readout is built around the new NECTAr digitizer chip, developed for the next generation of IACTs; the camera electronics is fully controlled and read out via Ethernet using a combination of FPGA and embedded ARM computers; the software uses modern libraries such as Apache Thrift, ØMQ and Protocol buffers. This work describes in detail the design and the performance of the upgraded cameras.
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