The fluorescence detection of ultra high energy (≳10
18
eV) cosmic rays requires a detailed knowledge of the fluorescence light emission from nitrogen molecules, which are excited by the cosmic ray ...shower particles along their path in the atmosphere. We have made a precise measurement of the fluorescence light spectrum excited by MeV electrons in dry air. We measured the relative intensities of 34 fluorescence bands in the wavelength range from 284 to 429
nm with a high resolution spectrograph. The pressure dependence of the fluorescence spectrum was also measured from a few hPa up to atmospheric pressure. Relative intensities and collisional quenching reference pressures for bands due to transitions from a common upper level were found in agreement with theoretical expectations. The presence of argon in air was found to have a negligible effect on the fluorescence yield. We estimated that the systematic uncertainty on the cosmic ray shower energy due to the pressure dependence of the fluorescence spectrum is reduced to a level of 1% by the AIRFLY results presented in this paper.
Fragile X syndrome (FXS), the most common inherited cause of intellectual disability, learning disability, and autism spectrum disorder, is associated with an increased prevalence of certain medical ...conditions including seizures. The goal of this study was to better understand seizures in individuals with FXS using the Fragile X Online Registry with Accessible Research Database, a multisite observational study initiated in 2012 involving FXS clinics in the Fragile X Clinic and Research Consortium. Seizure data were available for 1,607 participants, mostly male (77%) and white (74.5%). The overall prevalence of at least one seizure was 12%, with this rate being significantly higher in males than females (13.7 vs. 6.2%,
< 0.001). As compared to individuals with FXS without seizures, those with seizures were more likely to have autism spectrum disorder, current sleep apnea, later acquisition of expressive language, more severe intellectual disability, hyperactivity, irritability, and stereotyped movements. The mean age of seizure onset was 6.4 (SD 6.1) years of age with the great majority (>80%) having onset of seizures which was before 10. For those with epilepsy, about half (52%) had seizures for more than 3 years. This group was found to have greater cognitive and language impairment, but not behavioral disruptions, compared with those with seizures for <3 years. Antiepileptic drugs were more often used in males (60.6%) than females (34.8%), and females more often required more than one medication. The most commonly used anticonvulsants were oxcarbazepine, valproic acid, lamotrigine, and levetiracetam. The current study is the largest and first longitudinal study ever conducted to describe seizures in FXS. Overall, this study confirms previous reports of seizures in FXS and extends previous findings by further defining the cognitive and behavioral phenotype of those with epilepsy in FXS. Future studies should further investigate the natural history of seizures in FXS and the characteristics of seizures in FXS in adulthood.
Surface detector arrays are designed to measure the spectrum and composition of high energy cosmic rays by detecting the secondary particle flux of the extensive air showers (EAS) induced by the ...primary cosmic rays. Electromagnetic particles and muons constitute the dominant contribution to the ground detector signals. In this paper, we show that the ground signal deposit of an EAS can be described in terms of only very few parameters: the primary energy
E, the zenith angle
θ
, the distance of the shower maximum
X
max
to the ground, and a muon flux normalization
N
μ
. This set of physical parameters is sufficient to predict the average particle fluxes at ground level to around 10% accuracy. We show that this is valid for hadronic air showers, using the two standard hadronic interaction models used in cosmic ray physics, QGSJetII and Sibyll, and for hadronic primaries from protons to iron. Based on this model, a new approach to calibrating the energy scale of ground array experiments is developed, which factors out the model dependence inherent in such calibrations up to now. Additionally, the method yields a measurement of the average number of muons in EAS. The measured distribution of
N
μ
of cosmic ray air showers can then be analysed, in conjunction with measurements of
X
max
from fluorescence detectors, to put constraints on the cosmic ray composition and hadronic interaction models.
We are conducting tests of optical and electronics components of JEMEUSO at the Telescope Array site in Utah with a ground-based “EUSO-TA” detector. The tests will include an engineering validation ...of the detector, cross-calibration of EUSO-TA with the TA fluorescence detector and observations of air shower events. Also, the proximity of the TA’s Electron Light Source will allow for convenient use of this calibration device. In this paper, we report initial results obtained with the EUSO-TA telescope.
Compilation of papers presented by the JEM-EUSO Collaboration at the 36th International Cosmic Ray Conference (ICRC), held July 24 through August 1, 2019 in Madison, Wisconsin.
Our recent findings in vitro in the human colon adenocarcinoma cell line HCT-8 suggest that resistance to fluorouracil (5-FU) in patients with advanced colorectal cancer might be overcome by use of a ...different treatment schedule.
We tested the hypothesis that HCT-8 cells resistant to short-term 5-FU exposure retain sensitivity to continuous exposure and studied interactions between the two schedules.
HCT-8 cell lines resistant to short-term (pulse) treatment with 5-FU or to continuous exposure were obtained by six exposures to different concentrations of 5-FU for 4 hours or 7 days. We used a monolayer clonogenic assay to determine 5-FU-induced cell kill in resistant HCT-8 cells and sensitive parent cells. Parent cells were exposed to different concentrations of 5-FU for 1, 4, or 24 hours (short term), for 7 days (continuous exposure), or in a combination of both types of schedules. In a study of the mechanism of interaction between short-term and continuous exposure in parent cells, we performed flow cytometric DNA analysis to determine the percentage of cells in S phase and assays of thymidylate synthase inhibition in intact cells and of incorporation of 6-3H)5-FU nucleotides into nucleic acids.
Sensitive HCT-8 cells became fully resistant to 5-FU within five or six treatments, and low-dose continuous exposure almost immediately produced resistant clones. HCT-8 cells resistant to 5-FU given every 4 hours retained full sensitivity to continuous exposure, suggesting lack of cross-resistance between the two schedules, but cells resistant to continuous exposure were cross-resistant to short-term treatment. Parent cells showed a statistically significant (synergistic) enhancement of the cytotoxic activity for 5-FU exposure for 1 hour (100, 300, or 500 microM) followed by continuous exposure (0.5, 1, or 2 microM) or 4 hours (10, 30, or 60 microM) followed by continuous exposure (1 or 2 microM). Short-term plus continuous exposure produced a marked increase in percentage of S-phase cells, compared with the percentage for each schedule alone. The combination of 1-hour exposure and continuous exposure (1000 and 2 microM, respectively) produced a marked accumulation of cells in S phase at 24 hours (59%), which lasted up to 96 hours (53%). The combination of the two schedules produced only additive enhancement of thymidylate synthase inhibition as well as incorporation of 6-3H5-FU nucleotides into nucleic acids of HCT-8 cells.
Our findings provide a rationale for the use of bolus 5-FU and continuous infusion 5-FU in sequence.
We are conducting a clinical trial of bolus methotrexate followed by continuous-infusion 5-FU plus leucovorin.
The Transition Radiation Array for Cosmic Energetic Radiation (TRACER) cosmic-ray detector, first flown on long-duration balloon (LDB) in 2003 for observations of the major primary cosmic-ray nuclei ...from oxygen (Z = 8) to iron (Z = 26), has been upgraded to also measure the energies of the lighter nuclei, including the secondary species boron (Z = 5). The instrument was used in another LDB flight in 2006. The properties and performance of the modified detector system are described, and the analysis of the data from the 2006 flight is discussed. The energy spectra of the primary nuclei carbon (Z = 6), oxygen, and iron over the range from 1 GeV amu{sup -1} to 2 TeV amu{sup -1} are reported. The data for oxygen and iron are found to be in good agreement with the results of the previous TRACER flight. The measurement of the energy spectrum of boron also extends into the TeV amu{sup -1} region. The relative abundances of the primary nuclei, such as carbon, oxygen, and iron, above {approx}10 GeV amu{sup -1} are independent of energy, while the boron abundance, i.e., the B/C abundance ratio, decreases with energy as expected. However, there is an indication that the previously reported E {sup -0.6} dependence of the B/C ratio does not continue to the highest energies.
The fluorescence detection of ultra high energy cosmic rays requires a detailed knowledge of the fluorescence light emission from nitrogen molecules over a wide range of atmospheric parameters, ...corresponding to altitudes typical of the cosmic ray shower development in the atmosphere. We have studied the temperature and humidity dependence of the fluorescence light spectrum excited by MeV electrons in air. Results for the 313.6, 337.1, 353.7 and 391.4
nm bands are reported in this paper. We found that the temperature and humidity dependence of the quenching process changes the fluorescence yield by a sizeable amount (up to 20% for the temperature dependence in the 391.4
nm band) and its effect must be included for a precise estimation of the energy of ultra high energy cosmic rays.
Potato cyst nematodes (PCNs) are quarantine organisms, and they belong to the economically most relevant pathogens of potato worldwide. Methodologies to assess the viability of their cysts, which can ...contain 200 to 500 eggs protected by the hardened cuticle of a dead female, are either time and labor intensive or lack robustness. We present a robust and cost-efficient viability assay based on loss of membrane integrity upon death. This assay uses trehalose, a disaccharide present at a high concentration in the perivitelline fluid of PCN eggs, as a viability marker. Although this assay can detect a single viable egg, the limit of detection for regular field samples was higher, ≈10 viable eggs, due to background signals produced by other soil components. On the basis of 30 nonviable PCN samples from The Netherlands, a threshold level was defined (ΔA(trehalose) = 0.0094) below which the presence of >10 viable eggs is highly unlikely (true for ≈99.7% of the observations). This assay can easily be combined with a subsequent DNA-based species determination. The presence of trehalose is a general phenomenon among cyst nematodes; therefore, this method can probably be used for (for example) soybean, sugar beet, and cereal cyst nematodes as well.
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