Environmental Changes across the Early Mississippian Carbon Isotope Excursion

The Early Mississippian K–O (Kinderhookian-Osagean) δ13C excursion or TICE (mid-Tournaisian carbon isotope excursion) is characterized by an anomalous carbonate carbon isotope value of ≥5‰ that has been documented from numerous stratigraphic sections across the globe. This δ13C excursion coincides with global cooling and sea-level fall and predicts a significant change in seawater chemistry. However, sulfate sulfur isotope data across the K-O δ13C excursion reported in previous studies seem not to be responsive to the carbon cycle. Likewise, a recent study has documented a unidirectional increase in nitrogen isotopes across this excursion, which is not anticipated considering the amount of organic carbon burial required to form the prominent positive δ13C excursion and its resultant oxygen increase and global cooling. This study aims to understand the coupling between carbon, nitrogen, sulfur and oxygen cycles at this critical transition. This research uses Early Mississippian carbonate successions from Star Range (SR), Mountain Home Range (MH), and Pahranagat Range (PR) that indicate peritidal, shallow subidal to deep subtidal depositional environment in the Great Basin of western USA. Samples from these sections are analyzed for carbon isotopes (δ13C), sulfur isotopes (δ34S), nitrogen isotopes (δ15N) and oxygen isotopes (δ18O). Additionally, SR samples are analyzed for fluid inclusions, REEs, major and trace element concentrations. Stratigraphic records from PR and MH sections indicate that the outer shelf section (PR) may be more representative of seawater isotope record. The δ34SCAS records a ≥7‰ positive anomaly near the peak of the K-O δ13C excursion. Numerical modeling suggests that pyrite burial rates 5–10 times higher than that of the modern ocean are required to produce the observed δ34SCAS anomaly in a sulfate-rich Early Mississippian ocean. The aerial and volumetric expansion of sulfate reduction and pyrite burial was likely fused by abundantly available organic matter at the peak of the K-O δ13C excursion when oxygen minimum zone (OMZ) in the ocean has substantially expanded. At the falling limb of the K-O δ13C excursion, coupled negative shifts in δ34SCAS and δ18OCAS imply increase of sulfide reoxidation in the ocean and pyrite-derived riverine sulfate input, in response to global cooling, sea-level fall, and oxygenation resulted from enhanced organic carbon and pyrite burial, resulting in gradually decreasing the volume of OMZ. Such a change in ocean redox is reflected in the carbon and nitrogen cycles. Stratigraphic records indicate that the deeper-water outer shelf section (PR) show double spikes in both δ13Ccarb and δ13Corg with a magnitude up to 7‰ and a negative shift down to 4‰ between the peaks which is more representative of the seawater isotope record. However, considering the sensitivity of δ15N to redox conditions of depositional environments, the coupled δ13Ccarb – δ15N pattern from the MH section may better record the isotope signature of the oceanic nitrate (NO3–) reservoir, while the decoupled δ13Ccarb – δ15N in the PR section reflects involvement of local N-biochemical cycling in periodically developed suboxic-euxinic environments. The increase of δ15N toward the peak of the K-O δ13C excursion may record the expansion of oxygen minimum zone (OMZ) in the ocean that promotes water-column denitrification and 15N enrichment in the marine nitrate (NO3–) reservoir. The decrease of δ15N at the falling limb of the K-O δ13C excursion reflects the shrink of the OMZ and reduces the water-column denitrification in response to more oxygenated and cooler oceans resulting from enhanced organic carbon burial. The significant amount of organic carbon burial during Early Mississippian results global cooling and possibly glaciation which is partly supported by the presence of highly depleted δ18O values, down to –34‰, in SR samples. Block samples from SR and PR are studied for carbon and oxygen isotopes, fluid inclusion, REEs, major and trace elements to investigate the origin and processes involved during carbonate diagenesis. These geochemical data suggest that the carbonate diagenesis took place from a diagenetic fluid originated form freshwater. Importantly, SR samples are from close to or below the unconformity surfaces which may have been altered by glacial melt water with δ18O values of ≤ –15‰. Then, it could have been further modified by a burial diagenesis with geothermal temperature \u3c 200°C to produce the highly depleted δ18O values down to –34‰. Collectively, carbon, nitrogen, sulfur and oxygen isotope records from Early Mississippian carbonates show a coupled variation in response to the environmental change during this time

Save The King: Human-King Cobra, Ophiophagus hannah (Cantor 1836), conflicts and the need for conservation strategies in Nepal

Abstract.—Snake research tends to have a low priority in Nepal and very little information, mostly confined to populationsin small areas, addresses the biology and threats to the King Cobra (Ophiophagus hannah). Herein we providedata that could facilitate an assessment of the species’ status in Nepal and begin to address its conservation needs.We recorded data on King Cobras from 2015–2020, crosschecking with previous studies to avoid any duplicationof records. A King Cobra from Siddhara, Arghakhachi District, was the first record of the species in the district. Werecorded a total of 50 King Cobra mortalities from 20 districts, with most of them killed near human settlementsadjacent to forested areas. We mapped the locations of all mortalities and recorded land-use changes within a 500-mbuffer around each site over a 30-year period (1990–2020), revealing extensive landscape fragmentation in previouslyconnected natural areas. Our data suggest that the major threats to King Cobras are deliberate killing by humans andlarge-scale habitat loss due to an increasing human population. We recommend increased research to better understandthe biology of this charismatic species and continued conservation education and community outreach programs tofacilitate the development of effective conservation strategies

Paired carbonate-organic carbon and nitrogen isotope variations in Lower Mississippian strata of the southern Great Basin, western United States

© 2017 Elsevier B.V. The Early Mississippian K-O (Kinderhookian-Osagean) carbon isotope (δ13C) excursion or TICE (mid-Tournaisian carbon isotope excursion) is one of the most prominent positive δ13C excursions of the Phanerozoic. Recent studies raise uncertainties about the representative shape (single vs. double spikes) and magnitude of this δ13C excursion (3‰ to ≥ 6‰ in South China; ≥ 5.5‰ in Europe; and ≥ 7‰ in North America) and the 3‰ unidirectional increase in nitrogen isotopes across the δ13C excursion, which is unanticipated considering the amount of organic carbon burial required to form the δ13C excursion and the resultant oxygen increase and global cooling. To test if stratigraphic completeness and spatial isotope variations caused such uncertainties, we have conducted paired carbonate carbon (δ13Ccarb), organic carbon (δ13Corg) and nitrogen (δ15N) isotope analyses across the K-O interval in two well-exposed sections of the southern Great Basin, western United States. The two sections represent proximal shallow-water and distal deep-water depositional settings of a west-dipping carbonate ramp. In the distal ramp section where no exposure surface is present, both δ13Ccarb and δ13Corg show double spikes with peak δ13Ccarb values up to 7‰ and a negative shift down to 4‰ between the peaks. In the proximal shallower-water section where two karstic disconformities are observed, δ13Corg shows similar double spikes but δ13Ccarb displays only a single peak with the highest value of 5.5‰. The missing δ13Ccarb spike is likely caused by diagenetic alteration below a karstic disconformity that lowered δ13Ccarb but not δ13Corg values, resulting in smaller magnitude of the δ13Ccarb excursion. These features suggest that the 7‰ magnitude and double spikes are more representative of the K-O δ13C excursion in the southern Great Basin. The smaller magnitude of the K-O δ13Ccarb excursion in some sections of the Great Basin and the TICE in other sections globally may have overprinted with local environmental/diagenetic signal or resulted from stratigraphic hiatus/truncation, which needs to be clarified in future research. The δ15N across the K-O δ13C excursion in the distal ramp section is decoupled from δ13C, with the majority of δ15N values around 4 ± 1‰ that do not show any obvious temporal trend. In contrast, δ15N values in the shallow-water section is coupled with the K-O δ13C excursion, with a 3‰ positive shift from 4‰ to 7‰ at the rising limb of the δ13C excursion and a negative shift from 7‰ to 1–2‰ at the falling limb of the δ13C excursion. The δ15N trend from the distal ramp section is, in some extent, comparable with that documented from a section in South China, while the coupled δ13C–δ15N pattern in the proximal section seems better explain the potential redox change across a prominent δ13C excursion. Considering the sensitivity of δ15N to redox conditions of depositional environments, a more comprehensive δ15N study in a broader paleogeographic context is required to better understand the interactions between carbon and nitrogen cycles across the K-O interval—a critical transition from the mid-Paleozoic greenhouse clime to Late Paleozoic Ice Age (LPIA)

Molecular Characterization of Multidrug-Resistant Mycobacterium tuberculosis Isolated in Nepal

Despite being one of the first countries globally to introduce multidrug-resistant tuberculosis (MDR-TB) case management, the number of MDR-TB cases is continuing to rise in Nepal. Rapid molecular tests applicable in this setting to identify resistant organisms would be an effective tool in reversing this trend. To develop such tools, information about the frequency and distribution of mutations that are associated with phenotypic drug resistance in Mycobacterium tuberculosis is required. In the present study, we investigated the prevalence of mutations in rpoB and katG genes and the inhA promoter region in 158 M. tuberculosis isolates, 109 phenotypically MDR and 49 non-MDR collected in Nepal, by DNA sequencing. Mutations affecting the 81-bp rifampicin (RIF) resistance-determining region (RRDR) of rpoB were identified in 106 of 109 (97.3%) RIF-resistant isolates. The codons most frequently affected were 531, 526 and 516 with percentages of 58.7%, 15.6% and 15.6%, respectively. Of 113 isoniazid (INH)-resistant isolates, 99 (87.6%) had mutations in the katG gene, with Ser315Thr being the most prevalent (81.4%) substitution. Mutations in the inhA promoter region were detected in 14 (12.4%) INH-resistant isolates. The results from this study provide an overview of the current situation of RIF and INH resistance in M. tuberculosis in Nepal and can serve as a basis for developing or improving rapid molecular-based tests to monitor drug-resistant strains in this country

Sulfur isotope change across the Early Mississippian K–O (Kinderhookian–Osagean) δ\u3csup\u3e13\u3c/sup\u3eC excursion

© 2018 Paired carbonate associate sulfate (CAS) sulfur isotopes (δ34SCAS), pyrite sulfur isotopes (δ34SPY) and CAS oxygen isotopes (δ18OCAS) across the Early Mississippian K–O δ13C excursion are documented from two sections of a west-dipping carbonate ramp in the southern Great Basin, western U.S.A. A 4–6‰ positive δ34SCAS anomaly, accompanied by negative shifts in δ34SPY and δ18OCAS is found within the K–O δ13C excursion. In the section with a broader δ13C excursion, Δ34S (Δ34S=δ34SCAS–δ34SPY) increases from 15‰ to 45‰ and δ13Ccarb drops from 7‰ to 4‰ at the same stratigraphic interval. If this δ34SCAS anomaly represents a global phenomenon, the large magnitude (4–6‰) and short duration (shorter than that of δ13C) suggest an unusual pyrite burial event that expanded from sediments to the ocean water column. In this scenario, the areal and volumetric expansion of sulfate reduction and pyrite burial was likely triggered by abundantly available organic matter near the peak of the K–O δ13C excursion, during which organic carbon production and burial may have reached a maximum, thus substantially expanding the oxygen minimum zone (OMZ). Numerical simulations suggest that pyrite burial rates 2.5–5 times higher than that of the modern ocean followed by sulfide oxidation are required to produce the observed δ34SCAS anomaly in a sulfate-rich ([SO4] ≥28 mM) Early Mississippian ocean. Alternatively, the sulfur and CAS oxygen isotope anomalies may record local sulfur cycling in a foreland basin where changes in weathering input and bottom-water redox conditions in response to sea-level fall and cooling resulted in isotope changes. In both scenarios (either local or global), the integrated carbon, sulfur, and CAS-oxygen isotope data suggest a much more dynamic sulfur cycle across the K–O δ13C excursion than has been previously suggested

Seismic vulnerability assessment of f low-rise reinforced concrete buildings affected by the 2015 Gorkha, Nepal Earthquake

Low-rise reinforced concrete (RC) frames with brick masonry infill walls up to five stories high have been used for housing construction in Nepal since the late 1980s. Many buildings of this type were damaged and/or collapsed in the April 25, 2015 Gorkha earthquake (M 7.8), even in areas characterized with moderate shaking intensity such as Kathmandu Valley. Due to inadequate design and/or construction of RC frame components, these buildings essentially behave like masonry shear wall structures with a shear-dominant failure mechanism. The paper presents the findings of a field survey of 98 RC buildings affected by the 2015 earthquake. The main objective of the study was to correlate the observed damage in the buildings, using the modified European Macroseismic Scale (EMS-98), and the Wall Index (defined as the wall area in the direction of shaking divided by the total building plan area above the level of interest). The results can be used to help establish recommendations regarding the required wall index for low-rise RC buildings in Nepal.by Svetlana Brzeva, Bishnu Pandey, Dev Kumar Maharjan and Carlos Ventura

Ecthyma gangrenosum aggravated by systemic antibiotics: A case report and literature review

Ecthyma gangrenosum is a cutaneous manifestation of systemic infection caused predominantly by Pseudomonas aeruginosa. We report a case of ecthyma gangrenosum in a child caused by P. aeruginosa who had been previously unsuccessfully treated with systemic antibiotics. A four years old boy presented with the complaints of fever and ulcers on the trunk and extremities. He had been initiated on systemic antibiotics without sending or awaiting reports of blood and skin swab culture and sensitivity. The swab samples taken from the ulcers revealed growth of P. aeruginosa. He was then started on antipseudomonal intravenous antibiotics which eventually led to full recovery. Injudicious use of systemic antibiotics can lead to colonization and infection by opportunistic organisms such as P. aeruginosa. The use of antibiotics has to be based on reports of culture and sensitivity

A Critically Ill Child with Gangrenous Appendicitis Masquerading as Hollow Viscous Perforation

Background. Severe complications of acute appendicitis (AA) hitherto well described are less common in clinical practice nowadays. When a septic child is encountered with a short history of abdominal symptoms and disproportionate signs of peritonitis further complicated by radiological findings causing a diagnostic conundrum, management becomes exceedingly demanding. Case Presentation. A 10-year-old previously healthy boy presented to the emergency room with generalized abdominal pain associated with fever and jaundice for a day. Blood workup revealed leucopenia, hyperbilirubinemia, hyponatremia, and elevated CRP. Initial radiological evaluation suggested hollow viscous perforation. He was diagnosed to have hollow viscous perforation peritonitis in severe sepsis. At laparotomy, generalized peritoneal contamination was found, the source of which could be traced down to the gangrenous perforated appendix. Conclusion. Complicated appendicitis, in children, can present with baffling findings. Timely identification of an ill child, adequate workup, prompt resuscitation, and source control are imperative for a successful outcome

Intimate partner violence, food insecurity and COVID-19 among newly married women in Nawalparasi district of Nepal: a longitudinal study

This paper examines factors associated with intimate partner violence (IPV) among newly married women in Nepal, and how IPV was affected by food insecurity and COVID-19. Given evidence that food insecurity is associated with IPV and COVID-19, we explored whether increased food insecurity during COVID-19 is associated with changes in IPV. We used data from a cohort study of 200 newly married women aged 18-25 years, interviewed five times over two years at 6-month intervals (02/2018-07/2020), including after COVID-19-associated lockdowns. Bivariate analysis and mixed-effects logistic regression models were used to examine the association between selected risk factors and recent IPV. IPV increased from 24.5% at baseline to 49.2% before COVID-19 and to 80.4% after COVID-19. After adjusting for covariates, we find that both COVID-19 (OR = 2.93, 95% CI 1.07-8.02) and food insecurity (OR = 7.12, 95% CI 4.04-12.56) are associated with increased odds of IPV, and IPV increased more for food-insecure women post COVID-19 (compared to non-food insecure), but this was not statistically significant (confidence interval 0.76-8.69, p-value = 0.131). Young, newly married women experience high rates of IPV that increase with time in marriage, and COVID-19 has exacerbated this, especially for food-insecure women in the present sample. Along with enforcement of laws against IPV, our results suggest that special attention needs to be paid to women during a crisis time like the current COVID-19 pandemic, especially those who experience other household stressors