The Effect of Flow at Maud Rise on the Sea Ice Cover - Numerical Experiments

The role of seamounts in the formation and evolution of sea ice isinvestigated in a series of numerical experiments with a coupled seaice-ocean model. Bottom topography, stratification and forcing areconfigured for the Maud Rise region in the Weddell Sea. The specificflow regime that develops at the seamount as the combined response tosteady and tidal forcing consists of free and trapped waves and aTaylor column, which is caused by mean flow and tidal flowrectification. The enhanced variability through tidal motion inparticular is capable of modifying the mixed layer above the seamountenough to delay and reduce sea ice formation throughout the winter.The induced sea ice anomaly spreads and moves westward and affects anarea of several 100~000 km$^{2}$. Process studies reveal the complexinteraction between wind, steady and periodic ocean currents: allthree are required in the process of generation of the sea ice andmixed layer anomalies (mainly through tidal flow), their detachmentfrom the topography (caused by steady oceanic flow), and the westwardtranslation of the sea ice anomaly (driven by the time-mean wind)

Managment of diabetic ketoacidosis in children and adolescents in sub-Saharan Africa: A review

Background: Diabetic ketoacidosis (DKA) is a complex metabolic state of hyperglycaemia, ketosis, and acidosis. Diabetes in sub-Saharan Africa is, in many patients a serious disease with a poor prognosis. Most deaths, however, are due to preventable causes.Objective: To improve knowledge on the management of DKA in sub-Saharan Africa.Data sources: Literature review from different published sources. Data synthesis: Health systems in sub-Saharan Africa are currently organised for the treatment of episodes of illness and not long-term conditions like diabetes. Therefore the high rates of DKA is essentially due to lack of training of health professionals, lack of facilities in most hospitals, lack of public awareness as well as lack of health education to individual patients/families. In addition erratic insulin supply coupling with infections, low parental education, poor insulin storage and lack of facilities for self monitoring of blood glucose.Conclusion: A complex unfavourable social and economic environment is the basis of the high prevalence of DKA in sub-Saharan Africa. Several episodes of DKA can be prevented by effective public awareness programmes and education to healthcare providers

One-hour post-load plasma glucose levels associated with decreased insulin sensitivity and secretion and early makers of cardiometabolic risk.

PURPOSE: Obese adults with normal glucose tolerance (NGT) but with 1-hour post-load plasma glucose (1hPG) ≥ 155 mg/dl are at higher risk of developing type 2 diabetes (T2D) and cardiometabolic complications. Little information is available for the pediatric population, where recently, a lower cutoff, 132.5 mg/dl, has been suggested as being more sensitive to identify subjects at risk of T2D. Our aim was to assess whether obese Caucasian youth with 1hPG ≥ 132.5 mg/dl have worse insulin sensitivity and secretion and a worse cardiometabolic profile compared to obese youth with 1hPG < 132.5 mg/dl. METHODS: Medical records of 244 (43% male; age: 11.1 ± 2.7years) overweight/obese children and adolescents, who had undergone an oral glucose tolerance test (OGTT), were retrieved. Anthropometric and biochemical data were collected from the hard copy archive. Indexes of insulin resistance (HOMA-IR), insulin sensitivity (WBISI), and insulin secretion (Insulinogenic Index, Disposition Index) were calculated. RESULTS: Of the 244 records analyzed, 215 fulfilled criteria for NGT and had complete biochemical data. Among NGT patients, 42 (19.5%) showed 1hPG ≥ 132.5 mg/dL (high-NGT), while the remaining had 1hPG < 132.5 mg/dL (low-NGT). The high-NGT group showed a higher male prevalence (59.5 vs 37%), lower Disposition Index (0.54 [0.39-0.71] vs 0.79 [0.47-1.43]), and WBISI (0.24 [0.18-0.35] vs 0.33 [0.23-0.50]) than the low-NGT group. High-NGT subjects also showed a trend towards lower HDL-cholesterol and higher triglycerides/HDL-cholesterol ratio (2.13 [1.49-3.41] vs 1.66 [1.24-2.49]). CONCLUSIONS: In overweight/obese NGT Caucasian youth a 1hPG ≥ 132.5 mg/dL was able to identify those with impaired insulin sensitivity and secretion and a trend towards a worse cardio-metabolic profile, a group likely at risk for future T2D

Integrated Management of Industrial and Municipal Wastewater in China. - Demonstration Project in Jiaxing, Zhejiang Province

Årsliste 2000The city of Jiaxing in Zhejiang Province is a medium-size, rapidly expanding Chinese city located in a flat landscape with numerous canals. These are used for navigation, fishing, aquaculture and as drinking and industrial water source, but also as recipients for domestic and industrial wastewater and runoff from agriculture, paved roads and solid waste landfills in the area. The canals are severely polluted. NIVA has been assisting Jiaxing Environmental Protection Bureau (JEPB) in finding solutions to the local wastewater problems. The industry in the area discharges substantial quantities of potentially toxic wastewater to the sewer systems. There are, however, good possibilities for cleaner production routines in various factories. Several measures facilitate the transport of sewage to the nearby Hangzhou Bay, and sewage treatment processes before final disposal have been identified. The project has identified current and future wastewater production and recipient status. Based on pilot-plant operation and computer models a complete system for sewage collection and treatment has been suggested. This is based on transport of untreated sewage to Hanfzhou Bay where the construction of a sewage treatment plant is planned. The treatment methodology is based on a flexible chemically enhanced primary treatment (CEPT), followed by a biological step at a later stage. The project findings put emphasis on knowledge transfer and strengthening of JEPB resources to find solutions to the water-related problems in the city. In addition a detailed abatement plan should be developed, taking existing water quality, user interests and future water quality objectives into account.Direktoratet for Utviklingshjelp (NORAD

Emergence of magnetism in graphene materials and nanostructures

Magnetic materials and nanostructures based on carbon offer unique opportunities for future technological applications such as spintronics. This article reviews graphene-derived systems in which magnetic correlations emerge as a result of reduced dimensions, disorder and other possible scenarios. In particular, zero-dimensional graphene nanofragments, one-dimensional graphene nanoribbons, and defect-induced magnetism in graphene and graphite are covered. Possible physical mechanisms of the emergence of magnetism in these systems are illustrated with the help of computational examples based on simple model Hamiltonians. In addition, this review covers spin transport properties, proposed designs of graphene-based spintronic devices, magnetic ordering at finite temperatures as well as the most recent experimental achievements.Comment: tutorial-style review article -- 18 pages, 19 figure

Performance of a 229 Thorium solid-state nuclear clock

The 7.8 eV nuclear isomer transition in 229 Thorium has been suggested as an etalon transition in a new type of optical frequency standard. Here we discuss the construction of a "solid-state nuclear clock" from Thorium nuclei implanted into single crystals transparent in the vacuum ultraviolet range. We investigate crystal-induced line shifts and broadening effects for the specific system of Calcium fluoride. At liquid Nitrogen temperatures, the clock performance will be limited by decoherence due to magnetic coupling of the Thorium nucleus to neighboring nuclear moments, ruling out the commonly used Rabi or Ramsey interrogation schemes. We propose a clock stabilization based on counting of flourescence photons and present optimized operation parameters. Taking advantage of the high number of quantum oscillators under continuous interrogation, a fractional instability level of 10^{-19} might be reached within the solid-state approach.Comment: 28 pages, 9 figure

Asymmetric Dimethylarginine in Obese Youth: Relationship with 24-hour Ambulatory Blood Pressure

The incidence of amputation worldwide is 1.5 per 1000 habitants and the total number of amputees is about 10 million..

N2O isotopocule measurements using laser spectroscopy:analyzer characterization and intercomparison

For the past two decades, the measurement of nitrous oxide (N2O) isotopocules – isotopically substituted molecules 14N15N16O, 15N14N16O and 14N14N18O of the main isotopic species 14N14N16O – has been a promising technique for understanding N2O production and consumption pathways. The coupling of non-cryogenic and tuneable light sources with different detection schemes, such as direct absorption quantum cascade laser absorption spectroscopy (QCLAS), cavity ring-down spectroscopy (CRDS) and off-axis integrated cavity output spectroscopy (OA-ICOS), has enabled the production of commercially available and field-deployable N2O isotopic analyzers. In contrast to traditional isotope-ratio mass spectrometry (IRMS), these instruments are inherently selective for position-specific 15N substitution and provide real-time data, with minimal or no sample pretreatment, which is highly attractive for process studies. Here, we compared the performance of N2O isotope laser spectrometers with the three most common detection schemes: OA-ICOS (N2OIA-30e-EP, ABB – Los Gatos Research Inc.), CRDS (G5131-i, Picarro Inc.) and QCLAS (dual QCLAS and preconcentration, trace gas extractor (TREX)-mini QCLAS, Aerodyne Research Inc.). For each instrument, the precision, drift and repeatability of N2O mole fraction [N2O] and isotope data were tested. The analyzers were then characterized for their dependence on [N2O], gas matrix composition (O2, Ar) and spectral interferences caused by H2O, CO2, CH4 and CO to develop analyzer-specific correction functions. Subsequently, a simulated two-end-member mixing experiment was used to compare the accuracy and repeatability of corrected and calibrated isotope measurements that could be acquired using the different laser spectrometers. Our results show that N2O isotope laser spectrometer performance is governed by an interplay between instrumental precision, drift, matrix effects and spectral interferences. To retrieve compatible and accurate results, it is necessary to include appropriate reference materials following the identical treatment (IT) principle during every measurement. Remaining differences between sample and reference gas compositions have to be corrected by applying analyzer-specific correction algorithms. These matrix and trace gas correction equations vary considerably according to N2O mole fraction, complicating the procedure further. Thus, researchers should strive to minimize differences in composition between sample and reference gases. In closing, we provide a calibration workflow to guide researchers in the operation of N2O isotope laser spectrometers in order to acquire accurate N2O isotope analyses. We anticipate that this workflow will assist in applications where matrix and trace gas compositions vary considerably (e.g., laboratory incubations, N2O liberated from wastewater or groundwater), as well as extend to future analyzer models and instruments focusing on isotopic species of other molecules.ISSN:1867-1381ISSN:1867-854

N2_{2}O isotopocule measurements using laser spectroscopy: analyzer characterization and intercomparison

For the past two decades, the measurement of nitrous oxide (N2O) isotopocules – isotopically substituted molecules $^{14}$N$^{15}$N$^{16}$O, $^{15}$N$^{14}$N$^{16}$O and $^{14}$N$^{14}$N$^{18}$O of the main isotopic species $^{14}$N$^{14}$N$^{16}$O – has been a promising technique for understanding N2O production and consumption pathways. The coupling of non-cryogenic and tuneable light sources with different detection schemes, such as direct absorption quantum cascade laser absorption spectroscopy (QCLAS), cavity ring-down spectroscopy (CRDS) and off-axis integrated cavity output spectroscopy (OA-ICOS), has enabled the production of commercially available and field-deployable N$_{2}$O isotopic analyzers. In contrast to traditional isotope-ratio mass spectrometry (IRMS), these instruments are inherently selective for position-specific $^{15}$N substitution and provide real-time data, with minimal or no sample pretreatment, which is highly attractive for process studies. Here, we compared the performance of N$_{2}$O isotope laser spectrometers with the three most common detection schemes: OA-ICOS (N$_{2}$OIA-30e-EP, ABB – Los Gatos Research Inc.), CRDS (G5131-i, Picarro Inc.) and QCLAS (dual QCLAS and preconcentration, trace gas extractor (TREX)-mini QCLAS, Aerodyne Research Inc.). For each instrument, the precision, drift and repeatability of N$_{2}$O mole fraction [N$_{2}$O] and isotope data were tested. The analyzers were then characterized for their dependence on [N$_{2}$O], gas matrix composition (O$_{2}$, Ar) and spectral interferences caused by H$_{2}$O, CO$_{2}$, CH$_{4}$ and CO to develop analyzer-specific correction functions. Subsequently, a simulated two-end-member mixing experiment was used to compare the accuracy and repeatability of corrected and calibrated isotope measurements that could be acquired using the different laser spectrometers. Our results show that N$_{2}$O isotope laser spectrometer performance is governed by an interplay between instrumental precision, drift, matrix effects and spectral interferences. To retrieve compatible and accurate results, it is necessary to include appropriate reference materials following the identical treatment (IT) principle during every measurement. Remaining differences between sample and reference gas compositions have to be corrected by applying analyzer-specific correction algorithms. These matrix and trace gas correction equations vary considerably according to N$_{2}$O mole fraction, complicating the procedure further. Thus, researchers should strive to minimize differences in composition between sample and reference gases. In closing, we provide a calibration workflow to guide researchers in the operation of N$_{2}$O isotope laser spectrometers in order to acquire accurate N$_{2}$O isotope analyses. We anticipate that this workflow will assist in applications where matrix and trace gas compositions vary considerably (e.g., laboratory incubations, N$_{2}$O liberated from wastewater or groundwater), as well as extend to future analyzer models and instruments focusing on isotopic species of other molecules