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Increased anthropogenic-induced aerosol concentrations over the Himalayas and Tibetan Plateau have affected regional climate, accelerated snow/glacier melting, and influenced water supply and quality in Asia. Although sulfate is a predominant chemical component in aerosols and the hydrosphere, the contributions from different sources remain contentious. Here, we report multiple sulfur isotope composition of sedimentary sulfates from a remote freshwater alpine lake near Mount Everest to reconstruct a two-century record of the atmospheric sulfur cycle. The sulfur isotopic anomaly is utilized as a probe for sulfur source apportionment and chemical transformation history. The nineteenth-century record displays a distinct sulfur isotopic signature compared with the twentieth-century record when sulfate concentrations increased. Along with other elemental measurements, the isotopic proxy suggests that the increased trend of sulfate is mainly attributed to enhancements of dust-associated sulfate aerosols and climate-induced weathering/erosion, which overprinted sulfur isotopic anomalies originating from other sources (e.g., sulfates produced in the stratosphere by photolytic oxidation processes and/or emitted from combustion) as observed in most modern tropospheric aerosols. The changes in sulfur cycling reported in this study have implications for better quantification of radiative forcing and snow/glacier melting at this climatically sensitive region and potentially other temperate glacial hydrological systems. Additionally, the unique Δ33S-δ34S pattern in the nineteenth century, a period with extensive global biomass burning, is similar to the Paleoarchean (3.6-3.2 Ga) barite record, potentially providing a deeper insight into sulfur photochemical/thermal reactions and possible volcanic influences on the Earth's earliest sulfur cycle.
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Aire/análisis , Isótopos de Azufre/químicaRESUMEN
The extent to which stratospheric intrusions on synoptic scales influence the tropospheric ozone (O3) levels remains poorly understood, because quantitative detection of stratospheric air has been challenging. Cosmogenic 35S mainly produced in the stratosphere has the potential to identify stratospheric air masses at ground level, but this approach has not yet been unambiguously shown. Here, we report unusually high 35S concentrations (7,390 atoms m-3; â¼16 times greater than annual average) in fine sulfate aerosols (aerodynamic diameter less than 0.95 µm) collected at a coastal site in southern California on May 3, 2014, when ground-level O3 mixing ratios at air quality monitoring stations across southern California (43 of 85) exceeded the recently revised US National Ambient Air Quality Standard (daily maximum 8-h average: 70 parts per billion by volume). The stratospheric origin of the significantly enhanced 35S level is supported by in situ measurements of air pollutants and meteorological variables, satellite observations, meteorological analysis, and box model calculations. The deep stratospheric intrusion event was driven by the coupling between midlatitude cyclones and Santa Ana winds, and it was responsible for the regional O3 pollution episode. These results provide direct field-based evidence that 35S is an additional sensitive and unambiguous tracer in detecting stratospheric air in the boundary layer and offer the potential for resolving the stratospheric influences on the tropospheric O3 level.
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Carbonate minerals provide critical information for defining atmosphere-hydrosphere interactions. Carbonate minerals in the Martian meteorite ALH 84001 have been dated to â¼ 3.9 Ga, and both C and O-triple isotopes can be used to decipher the planet's climate history. Here we report Δ(17)O, δ(18)O, and δ(13)C data of ALH 84001 of at least two varieties of carbonates, using a stepped acid dissolution technique paired with ion microprobe analyses to specifically target carbonates from distinct formation events and constrain the Martian atmosphere-hydrosphere-geosphere interactions and surficial aqueous alterations. These results indicate the presence of a Ca-rich carbonate phase enriched in (18)O that formed sometime after the primary aqueous event at 3.9 Ga. The phases showed excess (17)O (0.7) that captured the atmosphere-regolith chemical reservoir transfer, as well as CO2, O3, and H2O isotopic interactions at the time of formation of each specific carbonate. The carbon isotopes preserved in the Ca-rich carbonate phase indicate that the Noachian atmosphere of Mars was substantially depleted in (13)C compared with the modern atmosphere.
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Sulfur-isotopic anomalies have been used to trace the evolution of oxygen in the Precambrian atmosphere and to document past volcanic eruptions. High-precision sulfur quadruple isotope measurements of sulfate aerosols extracted from a snow pit at the South Pole (1984-2001) showed the highest S-isotopic anomalies (Δ(33)S = +1.66 and Δ(36)S = +2) in a nonvolcanic (1998-1999) period, similar in magnitude to Pinatubo and Agung, the largest volcanic eruptions of the 20th century. The highest isotopic anomaly may be produced from a combination of different stratospheric sources (sulfur dioxide and carbonyl sulfide) via SOx photochemistry, including photoexcitation and photodissociation. The source of anomaly is linked to super El Niño Southern Oscillation (ENSO) (1997-1998)-induced changes in troposphere-stratosphere chemistry and dynamics. The data possess recurring negative S-isotope anomalies (Δ(36)S = -0.6 ± 0.2) in nonvolcanic and non-ENSO years, thus requiring a second source that may be tropospheric. The generation of nonvolcanic S-isotopic anomalies in an oxidizing atmosphere has implications for interpreting Archean sulfur deposits used to determine the redox state of the paleoatmosphere.
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The ability of sulfate aerosols to reflect solar radiation and simultaneously act as cloud condensation nuclei renders them central players in the global climate system. The oxidation of S(IV) compounds and their transport as stable S(VI) in the Earth's system are intricately linked to planetary scale processes, and precise characterization of the overall process requires a detailed understanding of the linkage between climate dynamics and the chemistry leading to the product sulfate. This paper reports a high-resolution, 22-y (1980-2002) record of the oxygen-triple isotopic composition of sulfate (SO4) aerosols retrieved from a snow pit at the South Pole. Observed variation in the O-isotopic anomaly of SO4 aerosol is linked to the ozone variation in the tropical upper troposphere/lower stratosphere via the Ozone El-Niño Southern Oscillations (ENSO) Index (OEI). Higher (17)O values (3.3, 4.5, and 4.2) were observed during the three largest ENSO events of the past 2 decades. Volcanic events inject significant quantities of SO4 aerosol into the stratosphere, which are known to affect ENSO strength by modulating stratospheric ozone levels (OEI = 6 and (17)O = 3.3, OEI = 11 and (17)O = 4.5) and normal oxidative pathways. Our high-resolution data indicated that (17)O of sulfate aerosols can record extreme phases of naturally occurring climate cycles, such as ENSOs, which couple variations in the ozone levels in the atmosphere and the hydrosphere via temperature driven changes in relative humidity levels. A longer term, higher resolution oxygen-triple isotope analysis of sulfate aerosols from ice cores, encompassing more ENSO periods, is required to reconstruct paleo-ENSO events and paleotropical ozone variations.
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Aerosoles/química , Clima , El Niño Oscilación del Sur , Isótopos de Oxígeno/análisis , Sulfatos/química , Erupciones Volcánicas/análisis , Regiones Antárticas , Modelos Químicos , Oxidación-Reducción , Nieve/químicaRESUMEN
RATIONALE: Triple oxygen isotopes of sulfate and nitrate are useful metrics for the chemistry of their formation. Existing measurement methods, however, do not account for oxygen atom exchange with quartz during the thermal decomposition of sulfate. We present evidence for oxygen atom exchange, a simple modification to prevent exchange, and a correction for previous measurements. METHODS: Silver sulfates and silver nitrates with excess (17)O were thermally decomposed in quartz and gold (for sulfate) and quartz and silver (for nitrate) sample containers to O(2) and byproducts in a modified Temperature Conversion/Elemental Analyzer (TC/EA). Helium carries O(2) through purification for isotope-ratio analysis of the three isotopes of oxygen in a Finnigan MAT253 isotope ratio mass spectrometer. RESULTS: The Δ(17)O results show clear oxygen atom exchange from non-zero (17)O-excess reference materials to zero (17)O-excess quartz cup sample containers. Quartz sample containers lower the Δ(17)O values of designer sulfate reference materials and USGS35 nitrate by 15% relative to gold or silver sample containers for quantities of 2-10 µmol O(2). CONCLUSIONS: Previous Δ(17)O measurements of sulfate that rely on pyrolysis in a quartz cup have been affected by oxygen exchange. These previous results can be corrected using a simple linear equation (Δ(17)O(gold) = Δ(17)O(quartz) * 1.14 + 0.06). Future pyrolysis of silver sulfate should be conducted in gold capsules or corrected to data obtained from gold capsules to avoid obtaining oxygen isotope exchange-affected data.
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BACKGROUND: The use of beta-blockers is limited by adverse effects such as bronchospasm in asthmatics. Third generation beta-blockers such as celiprolol may show better respiratory tolerability because they lack beta-blocker induced broncho-constriction. METHOD: Effect of celiprolol on the histamine induced contraction of tracheal muscle strips prepared from ovalbumin-sensitised guinea pigs was studied. Using oxygenated Krebs-Henseleit solution as the nutrient medium, the trachealis muscle activity was measured with isometric force displacement transducer and recorded on 4-channel Oscillograph. RESULT: Celiprolol 10(-4) M shifted the concentration-response curve of histamine downwards and to the right. Mean of amplitude of contraction, percent responses and deviations when compared with the control group were significantly different (p < 0.05). CONCLUSION: Celiprolol antagonised histamine-induced contractions of tracheal muscle of guinea pigs. So it may be considered safe in patients with asthma. However, further clinical evaluation and exploratory work is required.
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Antagonistas de Receptores Adrenérgicos beta 1/farmacología , Celiprolol/farmacología , Músculo Liso/efectos de los fármacos , Tráquea/efectos de los fármacos , Resistencia de las Vías Respiratorias/efectos de los fármacos , Animales , Modelos Animales de Enfermedad , CobayasRESUMEN
BACKGROUND: Homocysteine (Hcy) is an intermediate formed during the catabolism of sulphur containing essential amino acid, methionine and Less than one percent of tHcy is found as the free form. Development of atherosclerotic changes and thrombo-embolism are common features in patients with homocysteinuria. This study was conducted to assess the relationship of Hcy and coronary heart disease (CHD) in our population. METHODS: The cross-sectional analytical study was carried out at the Department of Biochemistry, Hazara University Mansehra and Ayub Medical College, Abbottabad. A total of 80 subjects were included in this study and were divided into 2 groups. Cases Group consisted of 40 patients who had confirmed Myocardial Infarction (MI) coming for routine follow-up (first re-visit) after the acute attack. Control Group consisted of 40 matching healthy individuals. Demographic data including age, gender, dietary habits, height and weight as documented in preformed proforma. Blood pressure was taken in sitting posture. Serum total Hcy were measured. Data was entered into computer using SPSS 16.0 for analysis. RESULTS: The mean age of the cases was 59.68 +/- 8.06 (30-70) years and that of the controls was 58.93 +/- 6.93 (48-76) years. The average BMI of cases was 27.70 +/- 3.61 Kg/m2 and of the controls was 25.66 +/- 2.98 Kg/m2. This increase of BMI from controls to cases was statistically significant (p < 0.050). The mean systolic BP of the cases was 153.88 +/- 11.90 mmHg in comparison with 142.62 +/- 11.65 mmHg for the controls. This difference was statistically significant (p < 0.001). Mean tHcy level of the cases was 17.15 +/- 4.45 micromol/l while that of controls was 12.20 +/- 2.53 micromol/l. There is a statistically significant difference between cases and controls with respect to Hcy levels (p < 0.001). CONCLUSION: Plasma tHcy level has a powerful predictor value of CHD and routine screening for elevated Hcy concentrations is advisable especially for individuals who manifest atherothrombotic disease without their traditional risk factors.
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Enfermedad Coronaria/sangre , Homocisteína/sangre , Adulto , Anciano , Estudios de Casos y Controles , Estudios Transversales , Femenino , Humanos , Masculino , Persona de Mediana Edad , Infarto del Miocardio/sangre , Factores de RiesgoRESUMEN
Background: The ideal urological method for treating complex, large renal calculi is Percutaneous nephrolithotomy (PCNL). Its instruments, surgical techniques, and positions have all been adjusted as a result of its ever-changing nature. In PCNL, the supine position is advantageous compared to the prone position due to its several advantages, including the absence of cardiopulmonary risks, fewer post operative complications and shorter operative time. This study was designed for comparison of PCNL in prone and supine positions. Methods: After receiving ethical and research committee approval, this retrospective review from secondary data was conducted from April 2015 to December 2021. Out of 623 patients, PCNL in prone position was performed on 258 patients and365 patients inmodifiedsupine position. The patients' demographics, stone size and location, number of tracts, operating time, hospital stay, stone clearance rate, and post-operative complications were all compared. Results: The gender and age of the patients, the size and number of tracts, and location of the stones were all comparable (p>0.05). Operative time for prone position was 82 min ±2.49 SD VS 65 min ±2.95 SD, for modified supine position, p<0.001), hospital stay was 58 hrs. ±1.66 SD for prone VS 51 Hrs. ±1.65 SD, for modified supine position, p<0.01) and analgesia requirements for prone position was 41% VS 23% for modified supine position, p<0.001). The stone clearance rate was 87% in supine position and 89% in the prone positioning group (p=0.47). Urinary leakage from tract site was 0.38% in prone vs. 0% in supine position and temperature >99 °F was 12.4% in prone vs. 11.3% in supine position were the most common post-operative complications. Angioembolization was not observed in either group. Blood transfusions were given to 4.26% in prone position and in 3.58% of cases in supine PCNL. Conclusion: Percutaneous nephrolithotomy in the supine position had a short operating time, short hospital stays, and less analgesia requirements than PCNL in the prone position. In view of the above findings, supine PCNL is easy, quick to perform and having less complications rate as compare to Prone PCNL.
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Cálculos Renales , Nefrolitotomía Percutánea , Nefrostomía Percutánea , Humanos , Posición Supina , Posición Prona , Nefrostomía Percutánea/métodos , Posicionamiento del Paciente/métodos , Cálculos Renales/cirugía , Complicaciones Posoperatorias/epidemiología , Resultado del TratamientoRESUMEN
BACKGROUND: Pakistan is home to approximately 10 million HCV infected people. HCV prevalence is expected to be higher in the earthquake affected area of Tehsil Oghi. The aim of this study was to estimate HCV prevalence in three Union Councils of Tehsil Oghi, i.e., Oghi, Shamdhara and Kathai, and to assess HCV knowledge and awareness in the population. METHODS: This is an observational study carried out during June 2010. Blood samples of 648 participants were analysed for the presence of anti HCV antibodies using Immuno-chromatographic method and a knowledge and awareness questionnaire was administered to the participants. RESULTS: 394 (61%) participants were females, while 254 (39%) were males. The overall prevalence of HCV in the study area was recorded as 67 (10.3%). Prevalence among male participants was 30 (11.8%), whereas, that among female participants was 37 (9.4%). Prevalence estimates in Oghi, Shamdhara and Kathai were 10.3%, 11% and 9% respectively. Knowledge and awareness regarding HCV was inadequate among the study population. CONCLUSIONS: HCV prevalence in the study area is higher than the overall prevalence in Pakistan. HCV related knowledge and awareness among population in the area is inadequate. There is a need to undertake a large scale population based epidemiological study and to introduce health interventions to control and reverse the spread of HCV in the area and to impart health education and awareness to the masses.
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Conocimientos, Actitudes y Práctica en Salud , Hepatitis C/epidemiología , Hepatitis C/psicología , Adolescente , Adulto , Terremotos , Femenino , Humanos , Masculino , Persona de Mediana Edad , Observación , Pakistán/epidemiología , Prevalencia , Encuestas y CuestionariosRESUMEN
BACKGROUND: Preoperative surgical planning assumes a central role in avoiding catastrophic outcomes of a surgery in the field of renal transplantation, and other urological procedures. This study was aimed to study the different anatomic patterns of human renal venous system. METHODS: It is a descriptive cross-sectional study including 50 adult male cadavers with well-preserved kidneys, renal vasculature and the inferior vena cava. Cadavers with deformed or congenitally anomalous kidney, evidence of surgery, solitary kidney, tumours of kidneys or injured renal vessels / inferior vena cava were excluded from the study. The kidneys, renal veins and the inferior vena cava were exposed. After securing inferior vena cava fifty ml mixture of Indian ink and gelatine was injected into renal veins via inferior vena cava and was allowed to solidify. Following this, the renal venous anatomy was studied. RESULTS: Twenty-eight cadavers had their right renal vein formed by 2 tributaries (56%), 13 (26%) had 3 tributaries, 5 (10%) had 4 tributaries, 1 cadaver had a posterior tributary (2%), while 3 cadavers had other numbers of tributaries (6%). Out of total 50 cadavers 40 (80%) had normal distribution of right renal vein. Additional renal veins were found in 14 (7%) cadavers, double renal veins in 1 (2%) and proximally double renal veins in 2 cadavers (4%).. CONCLUSIONS: There is considerable variation in renal venous anatomy. Knowledge of common venous patterns is necessary for minimizing intraoperative damage to renal anatomy and to prevent intra- and post-operative complications..
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Venas Renales/anatomía & histología , Adulto , Estudios Transversales , Humanos , Riñón/anatomía & histología , Riñón/irrigación sanguínea , Masculino , Vena Cava Inferior/anatomía & histologíaRESUMEN
We report data on the martian meteorite Northwest Africa (NWA) 7034, which shares some petrologic and geochemical characteristics with known martian meteorites of the SNC (i.e., shergottite, nakhlite, and chassignite) group, but also has some unique characteristics that would exclude it from that group. NWA 7034 is a geochemically enriched crustal rock compositionally similar to basalts and average martian crust measured by recent Rover and Orbiter missions. It formed 2.089 ± 0.081 billion years ago, during the early Amazonian epoch in Mars' geologic history. NWA 7034 has an order of magnitude more indigenous water than most SNC meteorites, with up to 6000 parts per million extraterrestrial H(2)O released during stepped heating. It also has bulk oxygen isotope values of Δ(17)O = 0.58 ± 0.05 per mil and a heat-released water oxygen isotope average value of Δ(17)O = 0.330 ± 0.011 per mil, suggesting the existence of multiple oxygen reservoirs on Mars.