Measurements of the fraction of contemporary carbon (f sub(C)) in organic carbon (OC) of ambient aerosols are presented using radiocarbon ( super(14)C). This value directly represents the biogenic ...contribution to OC, as the biosphere releases organic compounds with the present super(14)C/ super(12)C level (f sub(C)=1), whereas super(14)C has become extinct in anthropogenic emissions of fossil carbon (f sub(C)=0). This simple model assumes biomass burning to be negligible. Daytime and nighttime samples were collected at an urban location in Zuerich (Switzerland) in August 2002. Measured f sub(C) values ranged from 0.51 to 0.80, which indicates a major biogenic influence. This demonstrates that carbonaceous aerosol at this site is more dominated by the rural vicinity of Zuerich rather than direct urban sources. Furthermore, this investigation enabled an insight into the processes of particle formation, accumulation, and deposition for biogenic and anthropogenic emission sources. On the one hand, biogenic OC depends on the activity of plants to emit reactive volatile species like monoterpenes and on atmospheric oxidants that promote secondary organic aerosol formation. On the other hand, anthropogenic OC correlates with black carbon or elemental carbon.
GPS observations along three profiles across the Ethiopian Rift and Afar triple junction record differences in the length scale over which extension is accommodated. In the Afar region, where the ...mantle lithosphere is nearly or entirely absent, measurable extension occurs over ∼175 km; in the northern Ethiopian Rift, where the mantle lithosphere is anomalously thin and hot, extensional strain occurs over ∼85 km, extending beyond the structural rift valley; in the southern Ethiopian Rift, where the mantle lithosphere approaches standard continental thickness, extensional strain occurs over <10 km. This trend of increasingly distributed deformation contrasts with the standard model where continental rifts become mid‐ocean spreading centers through strain localization.
Key Points
Rifting does not progress toward greater and greater localization
The deformation in all continental tectonics depends on lithospheric rheology
Extension is more distributed in more evolved parts of the African Rift
We have performed measurements of particle formation and growth in a setup consisting of a plant and a reaction chamber, using live plants as well as an α-pinene source. The nucleation rates observed ...varied between 0.04 and 260 cm-3s-1, while the growth rates were 10–30 nm/h. We found that the formation and growth rates of particles increased with increasing amounts of carbon emitted by the plants, but there was significant variation between the plants. We have also modeled the formation of the aerosol using a continuously stirred tank reactor concept, and found that the basic physics and chemistry of the chamber are captured well.
Keywords Aerosol formation, nucleation rates, modeling
This study evaluates simulated vertical ozone profiles produced in the framework of the third phase of the Air Quality Model Evaluation International Initiative (AQMEII3) against ozonesonde ...observations in North America for the year 2010. Four research groups from the United States (US) and Europe have provided modeled ozone vertical profiles to conduct this analysis. Because some of the modeling systems differ in their meteorological drivers, wind speed and temperature are also included in the analysis. In addition to the seasonal ozone profile evaluation for 2010, we also analyze chemically inert tracers designed to track the influence of lateral boundary conditions on simulated ozone profiles within the modeling domain. Finally, cases of stratospheric ozone intrusions during May-June 2010 are investigated by analyzing ozonesonde measurements and the corresponding model simulations at Intercontinental Chemical Transport Experiment Ozonesonde Network Study (IONS) experiment sites in the western United States. The evaluation of the seasonal ozone profiles reveals that, at a majority of the stations, ozone mixing ratios are underestimated in the 1-6 km range. The seasonal change noted in the errors follows the one seen in the variance of ozone mixing ratios, with the majority of the models exhibiting less variability than the observations. The analysis of chemically inert tracers highlights the importance of lateral boundary conditions up to 250 hPa for the lower-tropospheric ozone mixing ratios (0-2 km). Finally, for the stratospheric intrusions, the models are generally able to reproduce the location and timing of most intrusions but underestimate the magnitude of the maximum mixing ratios in the 2-6 km range and overestimate ozone up to the first kilometer possibly due to marine air influences that are not accurately described by the models. The choice of meteorological driver appears to be a greater predictor of model skill in this altitude range than the choice of air quality model.
We investigated the stable carbon isotope ratios of selected VOCs in both the gas phase and particulate phase during beta pinene-ozone reaction. The experiments were performed in a large indoor ...chamber. Gas phase samples were collected in Silcosteel canisters (SilcoCan), with a time interval of 30min. Aerosol samples were collected on quartz fiber filters (Whatman) at a flow rate of 25l/min for 1h. All filters were pretreated at a temperature of 600 deg C overnight before sampling. A customized thermal desorption system combined with cryofocusing (from Gerstel) was used for desorbing the compounds. 2-D gas chromatography coupled with isotope ratio mass spectrometry (GC-IRMS) system was used for investigations of the compound specific stable carbon isotope ratios. In addition the stable carbon isotope ratio of the total carbon from the filter samples was measured. We observed a progressing enrichment of the beta pinene as it diminishes in concentration. One of the major oxidation products of beta pinene, nopinone, on the other hand, did not show a significant change in its isotope composition both in the gas and aerosol phase. The total carbon isotope ratio from the aerosol samples showed enrichment in the heavy isotope than the initial beta pinene. The combined measurement of gas and aerosol phase isotope ratios gives additional constraints to carbon balances in SOA formation.
Background and Aims. Hepatocellular carcinoma is a major cause of cancer death worldwide, accounting for over half a million deaths per year. Its incidence varies with geographic locations and the ...type of etiologic factors. In Ethiopia, unidentified causes of liver disease are of sizeable proportion. Recent studies have shown an association of H. pylori infection with different spectrums of chronic liver disease. This study was conducted at St. Paul’s Hospital Millennium Medical College in Ethiopia and assesses liver cancer and the association with H. pylori infection. Method. A prospective case-control study conducted on patients with chronic liver disease presenting with a suspicious liver lesion and diagnosed to have HCC in the Gastrointestinal (GI) Clinic of St. Paul’s Hospital MMC from Dec 30, 2016, to Nov 1, 2017 G.C. Descriptive surveys on clinical history and physical examination and laboratory profiles were obtained, and the clinical course of the patients including the type of treatment was followed prospectively. Control cases were taken from adult patients without evidence of liver disease in the internal medicine clinic coming for routine evaluation. After collection data were analyzed using SPSS version 23 and associations were assessed using chi-square test. Binary logistic regression was used to assess the association of HCC with different variables and H. pylori infection. All variables with p-value <0.05 were considered as statistically significant. Results. One hundred twenty patients were analyzed with equal representation of cases and controls. The majority of patients with HCC were male with a mean age of 36 years. Older age adjusted Odds Ratio (AOR) (95%CI, p-value) 1.07(1.03-1.09, <0.001), viral hepatitis B (AOR) (95%CI, p-value) 6.19 (1.92-19.93, 0.002), and H. pylori infection (AOR) (95%CI, p-value) 5.22 (2.04–13.31, <0.001) were statistically significantly associated with HCC. Conclusion. H. pylori infection is associated with HCC in this case-control study. This study supports the emerging evidence of H. pylori association with other extra-gastric manifestations.
Low‐income households and minority communities in the US are considered highly vulnerable to diet‐and nutrition‐related adverse health effects. Households' food‐related decisions may entail real or ...perceived tradeoffs among price, preference, access and availability, and other factors. We use a sample of low‐income households, mostly from African American communities, from the Nashville metropolitan area of Tennessee to assess fruit and vegetable purchasing behavior. We found that the vast majority of household shops for fruits and vegetables (F&Vs) less than two to three times per month. Using probit and nested logit models, we analyzed purchase decisions and investigated reasons and factors determining “not to buy” F&Vs by low‐income households.
Carbapenemase Inactivation Method (CIM) is a test to detect presence of the carbapenemase in Gram-negative bacteria. Determination of the carbapenemase production by inactivation of meropenem ...requires that a zone of control E. coli inhibition be measured approximately 6–24 h after plating. We have modified the CIM test by developing a rapid method which instead measures the growth of E. coli indicator strain ATCC 25922 using real-time PCR, referred to as a nucleic acid testing CIM (natCIM). Our natCIM, therefore reduces the detecting time from 6 to 24 h to approximately 4 h.
Efforts to remediate the multiple cognitive function impairments in schizophrenia should consider white matter as one of the underlying neural mechanisms.
To determine whether altered structural ...brain connectivity is responsible for 2 of the core cognitive deficits in schizophrenia- reduced information processing speed and impaired working memory.
This cross-sectional study design took place in outpatient clinics from August 1, 2004, to August 31, 2015. Participants included 166 patients with schizophrenia and 213 healthy control individuals. These participants were from 3 independent cohorts, each of which had its own healthy control group. No participant had current or past neurological conditions or major medical conditions. Patients were diagnosed with either schizophrenia or schizoaffective disorder as defined by the DSM-IV. Controls had no Axis I psychiatric disorder.
Mediation analyses and structural equation modeling were used to analyze the associations among processing speed, working memory, and white matter microstructures. Whole-brain and regional diffusion tensor imaging fractional anisotropy were used to measure white matter microstructures.
Of the study participants, the 166 patients with schizophrenia had a mean (SD) age of 38.2 (13.3) years and the 213 healthy controls had a mean (SD) age of 39.2 (14.0) years. There were significantly more male patients than controls in each of the 3 cohorts (117 70% vs 91 43%), but there were no significant differences in sex composition among the 3 cohorts. Patients had significantly reduced processing speed (Cohen d = 1.24; P = 6.91 × 10-30) and working memory deficits (Cohen d = 0.83; P = 1.10 × 10-14) as well as a significant whole-brain fractional anisotropy deficit (Cohen d = 0.63; P = 2.20 × 10-9). In schizophrenia, working memory deficit was mostly accounted for by processing speed deficit, but this deficit remained when accounting for working memory (Cohen d = 0.89; P = 2.21 × 10-17). Mediation analyses showed a significant association pathway from fractional anisotropy to processing speed to working memory (P = 5.01 × 10-7). The strength of this brain-to-cognition pathway in different white matter tracts was strongly associated with the severity of schizophrenia-associated fractional anisotropy deficits in the corresponding white matter tracts as determined by a meta-analysis (r = 0.85-0.94; all P < .001). The same pattern was observed in patients and controls either jointly or independently.
Study findings suggest that (1) processing speed contributes to the association between white matter microstructure and working memory in schizophrenia and (2) white matter impairment in schizophrenia is regional tract-specific, particularly in tracts normally supporting processing speed performance.
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