Virus infection of Lagenaria breviflora and Coccinia baiteri were observed in Calabar, Nigeria during the 2005/2006 growing season. The viruses causing the diseases were characterized in this study. ...Diagnostic tools were host range, transmission studies, cytopathology, electron microscopy, Immunosorbent Electron Microscopy (ISEM), serology and coat protein gene sequencing. Evidence from biological, serological and sequence data confirmed that both viruses belong to the genus Potyvirus, family Potyviridae. Both were mechanically transmissible and also transmitted by Myzus persicae and Aphis gossyppi in a fore-gut manner. They also induced cytoplasmic inclusions in infected leaf tissues. The Lagenaria virus isolate has a coat protein molecular weight of 32.5 kDa and 35.0 kDa for Coccinia isolate. Of the two viruses only Lagenaria virus isolate showed cross reactivity with MWMV in DAS-ELISA. Both viruses reacted negatively with antisera to some notable cucurbit viruses in the same test, showed weak to moderate decorations with antisera to PRSV, TuMV and TeMV in immunosorbent electron microscopy (ISEM) tests. The Coccinia virus was, however, strongly decorated by antiserum to MWMV but no decoration with the Lagenaria virus. Comparison of the amino acid sequence data of the N-terminal regions of the coat proteins to that of MWMV reported from Sudan indicated 92% and 93% identities for the Coccinia and Lagenaria viruses, respectively. It is suggested that the virus isolates reported in the study be considered strains of the MWMV Sudan isolate. This is the first report of the occurrence of MWMV in Nigeria.
Simultaneous measurements of O3, CO, and ultrafine aerosol particles (UFP), conducted on board of a Boeing 767‐ER passenger aircraft flying from Sri Lanka to Germany (project CARIBIC), are used to ...study two‐way cross‐tropopause mixing near a subtropical tropopause fold. On the equatorward side of the fold, downward mixing of stratospheric air into the upper troposphere is identified by enhanced concentrations of O3 and 14CO. Very high UFP number concentrations of up to 1.5×104 cm−3 (STP) were encountered inside the poleward half of the fold. This accumulation of small particles is explained by recent extensive aerosol nucleation, most likely triggered by the mixing of stratospheric air with tropospheric air injected into the fold. Further, nine particle formation events were observed outside the fold which are attributed to isolated cells of deep convection and to rising air parcels under cyclonic conditions that mix with surrounding air. In the upper troposphere O3 and CO were found to be correlated with high ΔO3/ΔCO ratios of 0.6 to 1.5. In the fold the correlation was strongly negative with ΔO3/ΔCO; = −3.5; but the high CO mixing ratios of 100 ppb at O3 mixing ratios of 250 ppb point to earlier injection of tropospheric air, in agreement with the UFP measurements.
The deployment of measurement equipment in passenger aircraft for the observation of atmospheric trace constituents is described. The package of automated instruments athat is installed in a ...one-ton-capacity aircraft freight container positioned in the forward cargo bay of a Boeing 767 ER can register a vast amount of atmospheric data during regular long-distance flight.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Simultaneous measurements of O
3
, CO, and ultrafine aerosol particles (UFP), conducted on board of a Boeing 767‐ER passenger aircraft flying from Sri Lanka to Germany (project CARIBIC), are used to ...study two‐way cross‐tropopause mixing near a subtropical tropopause fold. On the equatorward side of the fold, downward mixing of stratospheric air into the upper troposphere is identified by enhanced concentrations of O
3
and
14
CO. Very high UFP number concentrations of up to 1.5×10
4
cm
−3
(STP) were encountered inside the poleward half of the fold. This accumulation of small particles is explained by recent extensive aerosol nucleation, most likely triggered by the mixing of stratospheric air with tropospheric air injected into the fold. Further, nine particle formation events were observed outside the fold which are attributed to isolated cells of deep convection and to rising air parcels under cyclonic conditions that mix with surrounding air. In the upper troposphere O
3
and CO were found to be correlated with high ΔO
3
/ΔCO ratios of 0.6 to 1.5. In the fold the correlation was strongly negative with ΔO
3
/ΔCO; = −3.5; but the high CO mixing ratios of 100 ppb at O
3
mixing ratios of 250 ppb point to earlier injection of tropospheric air, in agreement with the UFP measurements.
Sulfur hexafluoride (SF6) is the most potent greenhouse gas known. Its atmospheric concentration has increased by 2 orders of magnitude since industrial production started in 1953. Once released into ...the atmosphere, SF6 will only be removed exceedingly slowly due to its atmospheric lifetime of about 3200 yr. These features have brought SF6 into the climatic impact discussion aimed at reduction of emissions. The dominant uses of SF6 are in gas insulated switchgear (GIS) and in blanketing or degassing molten aluminum and magnesium. From 1978 onward, the rapidly growing global SF6 burden is well-documented by atmospheric observations. Concerning the SF6 applications responsible for that, a vast range of speculations is circulating. The underlying information gapwhich preempts the design of any reduction programwill be bridged for the first time. Recently reported global sales of SF6 for end-use applications form the basis of this investigation but need various revisions. The good agreement between emissions modeled out of revised sales data and atmospheric observations since the 1970s allows the extrapolation of the atmospheric SF6 record further back to the 1950s. Our analysis also shows that the natural background of SF6 is lower than 0.04 ppt. A geographical analysis of SF6 uses suggests that the North American market needs to be better specified. With certain technological efforts, a global reduction of SF6 releases of up to 90% seems feasible, equivalent to 5500 t for the year 1995, and climatically equivalent to 132 million ton of CO2.
The ‘age’ of stratospheric air is a measure that characterizes the time scales of stratospheric transport. In this work we present and compare age‐values as determined from measurements of CO2 and ...SF6 on air‐samples obtained between 1987 and 1995 on six flights of our balloon‐borne cryo‐sampler. In the middle stratosphere for five out of six flights we find age‐values that are up to three years lower for CO2 than for SF6. This CO2‐age anomaly corresponds to an excess of 4–5 ppm CO2. Evidence is presented that this excess‐CO2 originates from rapid convective transport of near surface air. Additionally, we show that globally no compact relationship exists between the age of air and mixing‐ratios of N2O.
Using a laboratory wagon traveling along the Trans-Siberian railroad, O^sub 3^, NO, NO^sub 2^, CO, CH^sub 4^, SF^sub 6^ and black carbon aerosol have been measured during the summer of 1996. The ...expedition from Niznij Novgorod (500 km east of Moscow) to Vladivostok (and back to Moscow) has shown the great potential of the train method; here the first results are presented and discussed. A wealth of boundary layer air data was obtained during the over 18000 km travel without serious contamination problems from the electric train itself. The diurnal O^sub 3^ cycle peaked generally below 50 nmole/mole, showed the effects of changes in J(NO^sub 2^), and often dropped to a few nmole/mole at night time during inversions. Over the vast Siberian lowlands situated between the Ural mountains and the river Yenisey, CH^sub 4^ levels were consistently elevated at around 1.95 µmole/mole, which we mainly attribute to wetland emissions. Over eastern Siberia, however, CH^sub 4^ levels were generally lower at 1.85 µmole/mole. In contrast, over the west Siberian lowlands, CO levels were relatively low, often reaching values of only 110 nmole/mole, whereas over eastern Siberia CO levels were higher. Very high CO levels were detected over a 2000 km section east of Chita, along the river Amur, which represented an enormous polluted air mass. ^sup 14^C analysis performed on several CO samples confirms that the origin was biomass burning. SF^sub 6^, which was measured as a general conserved tracer, showed an eastward attenuation from 4.0 to 3.9 pmole/mole, with peaks in a number of places due to local Russian emissions.PUBLICATION ABSTRACT
Background Training simulators have been used for decades with success; however, a standardized educational strategy for diagnostic EGD is still lacking. Objective Development of a training strategy ...for diagnostic upper endoscopy. Study design Prospective, randomized trial. Settings A total of 28 medical and surgical residents without endoscopic experience were enrolled. Basic skills evaluations were performed following a structured program involving theoretical lectures and a hands-on course in diagnostic EGD. Subsequently, stratified randomization to clinical plus simulator training (group 1, n = 10), clinical training only (group 2, n = 9), or simulator training only (group 3, n = 9) was performed. Ten sessions of simulator training were conducted for groups 1 and 3 during the 4-month program. Group 2 underwent standard training in endoscopy without supplemental simulator training. The final evaluation was performed on the simulator and by observation of 3 clinical cases. Skills and procedural times were recorded by blinded and unblinded evaluators. Main Outcome Measurements Time to reach the duodenum, pylorus, or esophagus. Results All trainees demonstrated a significant reduction in procedure time during a simple manual skills test ( P < .05) and significantly better skills scores ( P = .006, P = .042 and P = .017) in the simulator independent of the training strategy. Group 1 showed shorter times to intubate the esophagus (61 ± 26 seconds vs 85 ± 30 seconds and 95 ± 36 seconds) and the pylorus (183 ± 65 seconds vs 207 ± 61 seconds and 247 ± 66 seconds) during the clinical evaluation. Blinded assessment of EGD skills showed significantly better results for group 1 compared with group 3. Blinded and unblinded evaluations were not statistically different. Limitations Small sample size. Conclusions Structured simulator training supplementing clinical training in upper endoscopy appears to be superior to clinical training alone. Simulator training alone does not seem to be sufficient to improve endoscopic skills.
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