We present a new approach for the identification of ultra-high energy cosmic rays from sources using dynamic graph convolutional neural networks. These networks are designed to handle sparsely ...arranged objects and to exploit their short- and long-range correlations. Our method searches for patterns in the arrival directions of cosmic rays, which are expected to result from coherent deflections in cosmic magnetic fields. The network discriminates astrophysical scenarios with source signatures from those with only isotropically distributed cosmic rays and allows for the identification of cosmic rays that belong to a deflection pattern. We use simulated astrophysical scenarios where the source density is the only free parameter to show how density limits can be derived. We apply this method to a public data set from the AGASA Observatory.
Soil properties in urban settings are impacted by human activities. This study investigated human influence on dynamic soil properties including bulk density (BD), organic C (OC), pH, and inorganic C ...(IC) in the suburban environment of Ankeny, IA. Nine periods of urban development were delineated, and 10 homes from each period were randomly selected. Soils were sampled from front yards of these homes. All soils had a loamy texture. Mean BD values were significantly higher (1.70 g cm−3) in newer developments than older sites (1.23 g cm−3). Bulk density increased significantly with depth. This could be the effect of increased compaction associated with newer and heavier equipment in the case of newer developments and improved aggregation and structural development in soils in older areas. Soils from the 2003 to 2005 period had significantly lower levels of OC (0.49 g kg−1) than those from the pre‐1939 period (4.49 g kg−1). Mean OC decreased with depth. The pH ranged from 5.4 to 8.5, with a mean of 7.7, and pH increased with time of development and with depth. Disturbance at newer sites could have exposed calcareous till. Long‐term use of acid fertilizers could have decreased surface pH. The amount of IC ranged from 0.11 g kg−1 in the older development to 8.41 g kg−1 in the newest development. The IC increased with depth. These results could indicate that time has impacted the loss of IC through leaching and acid‐forming processes. We conclude that current intensive site preparation techniques significantly affect dynamic soil properties; however, this impact is reduced as the time since the initial disturbance increases.
Heavy Metals Distribution in an Iowa Suburban Landscape Langner, A.N; Manu, A; Tabatabai, M.A
Journal of environmental quality,
2011, January 2011, 2011 Jan-Feb, 2011-01-00, 20110101, Letnik:
40, Številka:
1
Journal Article
Recenzirano
This study investigated the degree to which human activities through urbanization influence heavy metal concentrations in a suburban landscape in Ankeny, IA. Residential areas from different years in ...nine time periods of development were identified from aerial photos. Soil cores were collected from the center of the front yard of 10 randomly selected homes. Cores were subdivided into 0- to 5-, 5- to 10-, and 10- to 20-cm increments from a composite of five cores. The soils were analyzed for organic C, pH, and total Cd, Co, Cr, Cu, Ni, Pb, and Zn. Results showed that organic C increased and pH decreased with time, and that there was a general decreasing trend in heavy metal concentrations from the pre-1939 period until 1983–1990, after which there was a sharp increase in the concentrations of most of the metals. The mean Cu concentration ranged from 21 mg kg−1 for the pre-1939 time period of development to 14.9 mg kg−1 for the recent period of development (2003–2005). Nickel concentrations increased significantly with depth with means of 21.3 mg kg−1 at depth 0 to 5 cm, 22.5 mg kg−1 at depth 5 to 10 cm, and 23.0 mg kg−1 at depth 10 to 20 cm. The concentrations of heavy metals were significantly intercorrelated, except Zn, suggesting their coexistence as mineral constituents or common contamination source. The concentrations of Cu and Pb in some locations could be due to anthropogenic inputs or higher organic matter content in soils adjacent to older homes. There appears to have been a source that caused an increase in Cd, Cr, Co, Cu, Pb, and Ni concentrations in soil adjacent to homes built between 1983 and 1990.
Abstract
Ultra-high-energy photons with energies exceeding 10
17
eV offer a wealth of connections to different aspects of cosmic-ray astrophysics as well as to gamma-ray and neutrino astronomy. The ...recent observations of photons with energies in the 10
15
eV range further motivate searches for even higher-energy photons. In this paper, we present a search for photons with energies exceeding 2 × 10
17
eV using about 5.5 yr of hybrid data from the low-energy extensions of the Pierre Auger Observatory. The upper limits on the integral photon flux derived here are the most stringent ones to date in the energy region between 10
17
and 10
18
eV.
Objectives Cytomegalovirus (CMV) drug resistance is a therapeutic challenge in the transplant setting. No longitudinal cohort studies of CMV resistance in a real-life setting have been published in ...the valganciclovir era. We report findings for a French multicentre prospective cohort of 346 patients enrolled at initial diagnosis of CMV infection (clinical trial registered at clinicaltrials.gov: NCT01008540). Patients and methods Patients were monitored for detection of CMV infection for ≥2 years. Real-time detection of resistance by UL97 and UL54 gene sequencing and antiviral phenotyping was performed if viral replication persisted for >21 days of appropriate antiviral treatment. Plasma ganciclovir assays were performed when resistance was suspected. Results Resistance was suspected in 37 (10.7%) patients; 18/37 (5.2% of the cohort) had virological resistance, associated with poorer outcome. Most cases involved single UL97 mutations, but four cases of multidrug resistance were due to UL54 mutations. In solid organ transplant recipients, resistance occurred mainly during primary CMV infection (odds ratio 8.78), but also in two CMV-seropositive kidney recipients. Neither CMV prophylaxis nor antilymphocyte antibody administration was associated with virological resistance. Conclusions These data show the feasibility of surveying resistance. Virological resistance was frequent in patients failing antiviral therapy. More than 1/5 resistant isolates harboured UL54 mutations alone or combined with UL97 mutations, which conferred a high level of resistance and sometimes were responsible for cross-resistance, leading to therapeutic failure.
Abstract
We present a measurement of the cosmic-ray spectrum above 100 PeV using the part of the surface detector of the Pierre Auger Observatory that has a spacing of 750 m. An inflection of the ...spectrum is observed, confirming the presence of the so-called
second-knee
feature. The spectrum is then combined with that of the 1500 m array to produce a single measurement of the flux, linking this spectral feature with the three additional breaks at the highest energies. The combined spectrum, with an energy scale set calorimetrically via fluorescence telescopes and using a single detector type, results in the most statistically and systematically precise measurement of spectral breaks yet obtained. These measurements are critical for furthering our understanding of the highest energy cosmic rays.
Purpose:
This paper aims to determine the effective point of measurement and the total perturbation correction p of parallel‐plate chambers for clinical photon dosimetry.
Methods:
The effective point ...of measurement (EPOM) was calculated using the EGSnrc Monte Carlo code system with the EGSnrc user code egs_ chamber. Depth dose curves of the ionization chambers were calculated in a water phantom for several high energy photon spectra (4, 6, 10, 15, 18 MV‐X). Different normalization criterions (normalization to the maximum of the depth dose curve and normalization to the value in 10 cm depth) have been applied. The EPOM was determined by shifting the normalized depth dose curve of a small water voxel against the depth ionization curve until the disagreement (calculated by the root mean square deviation) reaches a minimum. In addition, the total perturbation correction p was calculated by the ratio of the dose to water and the product of the dose determined in the chamber and the water to air stopping power ratio.
Results:
The EPOM varied slightly depending on the chosen normalization criterion. For all chambers the necessary shift of the EPOM decreased linearly with increasing beam quality specifier TPR20/10. For the Roos and NACP chamber, the results were positive suggesting that the chambers need to be shifted towards the focus. For the Markus chamber, the required shift was negative and for the Advanced Markus chamber partly negative and partly positive. The total perturbation correction p was almost independent of the depth. Only for regions below 1 cm the perturbation correction deviated significantly from unity.
Conclusion:
In the present study, the effective point of measurement and the total perturbation correction p was determined for four parallel‐plate ionization chambers and five clinical relevant photon spectra. Applying the calculated EPOM, the residual perturbation correction p was mostly depth independent.
The offspring of individuals with premature coronary heart disease are themselves at increased risk for myocardial infarction before the age of 55. Consensus panels have recommended that all such ...offspring undergo an evaluation of cardiovascular risk, including cholesterol testing.
To examine self-reported rates of cardiovascular risk factor assessment in this population, we conducted a telephone survey of 318 Canadian adults with premature coronary heart disease and of one offspring from 298 (94%) of the 318 families.
The median age of the offspring was 20 years (range 2 to 39 y). Among the 219 late adolescent and young adult offspring, only 97 (44%) reported having had a blood cholesterol measurement during the preceding 3 years. Thirty-seven percent reported being current smokers, 31% were overweight, and 30% exercised fewer than three times per week. Men were less likely than women to report having had their blood pressure measured in the preceding year (57% vs 80%).
These low rates of cardiac risk factor assessment families of patients with premature coronary heart disease represent missed opportunities for primary prevention. More effective strategies to prevent atherosclerosis in this population are needed.
Food consumption patterns of Inuit women Lawn, J; Langner, N; Brulé, D ...
International journal of circumpolar health,
1998, Letnik:
57 Suppl 1
Journal Article
Recenzirano
To evaluate nutrient intake and food consumption patterns of Inuit women of child-bearing age, a 24-hour diet recall and general health and food frequency questionnaire was administered to 688 Inuit ...women aged 15-44 in six isolated communities. Data were analyzed using the 1991 Canadian Nutrient File. Mean intakes of essential nutrients were expressed as percentages of Health Canada's 1990 Recommended Nutrient Intakes (RNI). Chi-square tests were used to determine relationships between categorical variables. Folacin intake ranged from 49% to 95% of the RNI in most communities (median = 76%) and was only 37% of the RNI for pregnant and 54% for lactating women. Mean calcium intake for pregnant and lactating women averaged 55% and 47% of the RNI, respectively. Average vitamin A intakes ranged from 26% to 87% of the RNI (median = 65%), with intake for pregnant Inuit women and lactating women 79% and 54% of the RNI, respectively. Country food was the major source of protein and iron, and store foods the major source of calories, calcium, folacin, and vitamin A. Low intakes of folacin, calcium, and vitamin A, especially among pregnant and lactating women, place Inuit women of childbearing age at risk. Women on social assistance are nutritionally vulnerable.
We conducted a telephone survey of 102 randomly selected Ottawa family physicians to determine their attitudes and practices regarding the treatment of hypercholesterolemia. Of the 102, 56% routinely ...measured serum cholesterol levels in all their patients over the age of 30 years, and 24% did so for patients in more restricted age ranges. The level at which they started dietary therapy averaged 6.95 mmol/L (270 mg/dl); for 25% it was less than 6.22 mmol/L (240 mg/dl). The level at which they started drug therapy averaged 8.9 mmol/L (345 mg/dl); for only 15% was it 7.23 mmol/L (280 mg/dl) or less. Two-thirds were unable to give numerical values to the serum cholesterol levels at which they started diet therapy, and 38% used the upper limits of laboratory normal values as an indication to start therapy. Our findings contrast markedly with results reported for US family physicians, who treat hypercholesterolemia much more aggressively. The variability in practices must be addressed if public campaigns to lower serum cholesterol levels are to be undertaken.
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