577 research outputs found

    Tricarbonyliron(0) complexes of bio-derived η4 cyclohexadiene ligands: An approach to analogues of oseltamivir

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    We have prepared novel [η4] and [η5]+ tricarbonyliron complexes from an unusual enantiopure cyclohexadiene ligand that possesses a quaternary stereocentre; this in turn is prepared through biotransformation of an aromatic ring. The cyclohexadiene ligand initially possessed two hydroxyl groups, both of which could be substituted with other functionality by means of an overall [η4] → [η5]+ → [η4] → [η5]+ → [η4] sequence. From six novel tricarbonyliron complexes which have been prepared, three have been characterised by x-ray crystallography. The reaction sequence we describe is potentially of relevance to the synthesis of analogues of the anti-influenza drug oseltamivir. In addition, the failure of an attempted addition of a bulky nitrogen nucleophile to an [η5]+ complex sheds light on the limits of reactivity for such additions. Thus, two bulky nucleophiles which are each known to add successfully to unencumbered [η5]+ complexes seemingly cannot be added sequentially to adjacent positions on the cyclohexadiene ligand

    The surface energy balance during foehn events at Joyce Glacier, McMurdo Dry Valleys, Antarctica

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    The McMurdo Dry Valleys (MDV) are a polar desert, where glacial melt is the main source of water to streams and the ecosystem. Summer air temperatures are typically close to zero, and therefore foehn events can have a large impact on the meltwater production. A 14-month record of automatic weather station (AWS) data on Joyce Glacier is used to force a 1D surface energy balance model to study the impact of foehn events on the energy balance. AWS data and output of the Antarctic Mesoscale Prediction System (AMPS) on a 1.7 km grid are used to detect foehn events at the AWS site. Foehn events at Joyce Glacier occur under the presence of cyclones over the Ross Sea. The location of Joyce Glacier on the leeward side of the Royal Society Range during these synoptic events causes foehn warming through isentropic drawdown. This mechanism differs from the foehn warming through gap flow that was earlier found for other regions in the MDV and highlights the complex interaction of synoptic flow with local topography of the MDV. Shortwave radiation is the primary control on melt at Joyce Glacier, and melt often occurs with subzero air temperatures. During foehn events, melt rates are enhanced, contributing to 23 % of the total annual melt. Foehn winds cause a switch from a diurnal stability regime in the atmospheric surface layer to a continuous energy input from sensible heat flux throughout the day. The sensible heating during foehn, through an increase in turbulent mixing resulting from gustier and warmer wind conditions, is largely compensated for by extra heat losses through sublimation. Melt rates are enhanced through an additional energy surplus from a reduced albedo during foehn.</p

    Brain Pro-TCT:Quality improvement of delirium detection on a cardiothoracic surgical ward

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    1) Please declare any conflicts of interest below: The authors declare a potential conflict of interest but not a personal conflict of interest. Part of the costs for this study are covered by Heartcentre Twente Foundation. Prolira provided training and the DeltaScans during the study period free of charge and applied a discount to the disposable patch costs. 2) Ethics Approval: Ethical approval was waived by the Advisory committee Medisch Spectrum Twente at Enschede. The Institutional Review Board of Medisch Spectrum Twente has concluded that this study does not fall under the remit of the Medical Research Involving Human Subjects. 3) Context: The study was done on the cardiothoracic surgery ward at Thoraxcentrum Twente (Medisch Spectrum Twente, Enschede, the Netherlands), a tertiary teaching hospital. Patients 70 years or older who underwent cardiac surgery were included. The quality improvement team included nurse practitioners in cardiac surgery and psychiatry, a cardiac surgeon, nurses, a technical physician, and an epidemiologist. 4) Problem: Delirium is a common syndrome of acute brain failure, which often occurs in hospitalized older patients following cardiac surgery. Delirium after cardiac surgery is related to adverse long-term outcomes, more readmissions to hospital, and decreased cognitive and functional outcomes. Early detection of delirium allows early treatment of underlying causes. In standard care, we use a delirium observation scale score (DOSS). Recently, a single-channel electroencephalography (EEG) medical device was developed to screen delirium based on detection of delta waves (DeltaScan). Using DeltaScan in routine care may improve delirium detection and clinical outcomes. 5) Assessment of problem and analysis of its causes: Previous delirium studies in Thoraxcentrum Twente using DOSS as standard care reported an incidence of delirium of 13 to 17% in elective patients aged ≥45 years. Published and unpublished research data for cardiothoracic surgery wards show an increase of delirium detection by &gt;15% (absolute percentage growth), when DeltaScan was used in clinical studies. Nurses, nurse practitioners, and medical doctors were informed  about the aims of the study and importance of delirium screening. A nurse improvement project, including a workgroup, was started, where the importance of screening was emphasized. Before the implementation of the DeltaScan, nurses on the surgical ward received education and training. Medical doctors, residents, and nurse practitioners were trained on how to interpret the DeltaScan scores. 6) Intervention: First, we continued the DOSS as regular care for delirium screening; three measurements a day for the first three postoperative days. Second, DeltaScan was implemented as new regular care. DeltaScan measurements took place twice a day for at least three consecutive days. 7) Strategy for change: In February 2021 additional training of the DOSS for delirium screening began, and from April 2021 onwards, prospective data collection of the first group continued till May 2022. Training with DeltaScan started in March/April 2022. The DeltaScan data collection started in May 2022, and is still ongoing. 8) Measurement of improvement: The primary endpoints to measure improvement were incidence of delirium, and length of hospital stay. Secondary endpoints included delirium duration, adherence to delirium protocol, and costs related to the innovation. The innovation was deemed successful with an incidence increase from 15 to 30%, and a length of stay reduction with at least 1.5 days. This abstract is based on preliminary data until October 2022. 9) Effects of changes: In total 612 patients were included, with 450 patients in the DOSS group and 162 patients (interim results) in the DeltaScan group. Incidence of finding delirium increased from 15% to 25% (p = 0.008). Median length of hospital stay for delirium patients was reduced from 9 hospital nights to 5.5 nights (p = 0.002). Median duration of delirium decreased (not significantly) from 77 hours to 65 hours (p = 0.12). 10) Lessons learned: Involving all stakeholders early in the project helped to gain commitment to the innovation. The change was measured in a scientific study, as no formal results on effectivity are known at the moment. Introducing a new device for delirium screening arouses resistance. Reducing or removing this resistance remains difficult. 11) Messages for others: Involving all stakeholders in a working group for delirium screening helped to start an innovation, monitor benefits, and motivated colleagues to actually commit to the innovation. Screening for delirium with DeltaScan in our study leads to an increase of finding delirium, and reduced hospital stay (interim results) for patients after cardiothoracic surgery. It is unknown yet, whether this is cost-effective. We hypothesize that these results are expected to be similar for other patient groups such as geriatric or general surgical patients. 12) Please describe how you have involved patients, carers, or family members in the project: Patients and their relatives are informed about the risk of delirium and the impact of delirium before hospital admission. Relatives and patients are often informed during measurements on the importance of adequate delirium screening, where positive responses are often heard. No formal co-creation by patients was done, but informal feedback will be collected in the near future. </p

    Breaking Traditions:An Isotopic Study on the Changing Funerary Practices in the Dutch Iron Age (800-12 bc)

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    Urnfields in the Dutch river area were replaced by cemeteries with a mixture of cremation and inhumation graves around the sixth century bc. This study provides the first biogeochemical evidence that the Iron Age communities were heterogeneous in terms of geological origins. The high percentage of non-locally born individuals (~48%) supports the hypothesis that the change in burial practice was the result of the influx of foreign people, who were being allowed to keep their own burial customs, whereas some of the local inhabitants adapted the burial rites of foreign cultures, leading to a heterogeneous burial rite for some centuries

    Trends in Antarctic Peninsula surface melting conditions from observations and regional climate modeling

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    Multidecadal meteorological station records and microwave backscatter time-series from the SeaWinds scatterometer onboard QuikSCAT (QSCAT) were used to calculate temporal and spatial trends in surface melting conditions on the Antarctic Peninsula (AP). Four of six long-term station records showed strongly positive and statistically significant trends in duration of melting conditions, including a 95% increase in the average annual positive degree day sum (PDD) at Faraday/Vernadsky, since 1948. A validated, threshold-based melt detection method was employed to derive detailed melt season onset, extent, and duration climatologies on the AP from enhanced resolution QSCAT data during 1999–2009. Austral summer melt on the AP was linked to regional- and synoptic-scale atmospheric variability by respectively correlating melt season onset and extent with November near-surface air temperatures and the October–January averaged index of the Southern Hemisphere Annular Mode (SAM). The spatial pattern, magnitude, and interannual variability of AP melt from observations was closely reproduced by simulations of the regional model RACMO2. Local discrepancies between observations and model simulations were likely a result of the QSCAT response to, and RACMO2 treatment of, ponded surface water, and the relatively crude representation of coastal climate in the 27 km RACMO2 grid

    Sensitivity of the Atlantic meridional overturning circulation to South Atlantic freshwater anomalies

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    The sensitivity of the Atlantic Meridional Overturning Circulation (AMOC) to changes in basin integrated net evaporation is highly dependent on the zonal salinity contrast at the southern border of the Atlantic. Biases in the freshwater budget strongly affect the stability of the AMOC in numerical models. The impact of these biases is investigated, by adding local anomaly patterns in the South Atlantic to the freshwater fluxes at the surface. These anomalies impact the freshwater and salt transport by the different components of the ocean circulation, in particular the basin-scale salt-advection feedback, completely changing the response of the AMOC to arbitrary perturbations. It is found that an appropriate dipole anomaly pattern at the southern border of the Atlantic Ocean can collapse the AMOC entirely even without a further hosing. The results suggest a new view on the stability of the AMOC, controlled by processes in the South Atlantic. <br/

    Семантические барьеры в деловой коммуникации

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    Статья из специализированного выпуска научного журнала "Культура народов Причерноморья", материалы которого объединены общей темой "Язык и Мир" и посвящены общим вопросам Языкознания и приурочены к 80-летию со дня рождения Николая Александровича Рудякова.Стаття із спеціалізованого випуску наукового журналу "Культура народов Причерноморья", матеріали якого поєднані загальною темою "Мова і Світ" і присвячені загальним питанням мовознавства і приурочені до 80-річчя з дня народження Миколи Олександровича Рудякова
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