Sea ice and millennial-scale climate variability in the Nordic seas 90 kyr ago to present

Publisher's version, source http://doi.org/10.1038/ncomms12247In the light of rapidly diminishing sea ice cover in the Arctic during the present atmospheric warming, it is imperative to study the distribution of sea ice in the past in relation to rapid climate change. Here we focus on glacial millennial-scale climatic events (Dansgaard/Oeschger events) using the sea ice proxy IP25 in combination with phytoplankton proxy data and quantification of diatom species in a record from the southeast Norwegian Sea. We demonstrate that expansion and retreat of sea ice varies consistently in pace with the rapid climate changes 90 kyr ago to present. Sea ice retreats abruptly at the start of warm interstadials, but spreads rapidly during cooling phases of the interstadials and becomes near perennial and perennial during cold stadials and Heinrich events, respectively. Low-salinity surface water and the sea ice edge spreads to the Greenland–Scotland Ridge, and during the largest Heinrich events, probably far into the Atlantic Ocean

Wave climate and power distribution around a rocky island: Alcatrazes, Brazil

We investigate the distribution of the wave power around the Alcatrazes island, a protected marine reserve in southeastern Brazil, located at 20 nautical miles from the coast of São Sebastião/SP. A 14-year wave time series (2005-2018) extracted from the global WaveWatch III model, was used to obtain the offshore wave climate. Based on the wave climate, a wave propagation model (Delft3D) was applied in order to obtain nearshore information. The most frequent waves are from the east, southeast and south, with heights between 1.0 and 2.0 m and periods of 7 to 10 s. Due to dominant wave direction incidence, the wave power is higher at the more exposed eastern side of the island, with its lee side becoming shadowed from the main wave trains. Magnitudes vary seasonally, with winter and autumn presenting more energetic southerly waves and consequent higher wave power along the rocky island. The wave power distribution is a consequence of the incident wave characteristics and the geomorphology of the island. Our findings are the first assessment of the local wave climate and wave power distribution along the rocky shores of Alcatrazes island, providing important background information for understanding different aspects of its functioning and management

Global Solutions of the Navier-Stokes Equations for Isentropic Flow with Large External Potential Force

We prove the global-in-time existence of weak solutions to the Navier-Stokes equations of compressible isentropic flow in three space dimensions with adiabatic exponent $\gamma\ge1$. Initial data and solutions are small in $L^2$ around a non-constant steady state with densities being positive and essentially bounded. No smallness assumption is imposed on the external forces when $\gamma=1$. A great deal of information about partial regularity and large-time behavior is obtained.Comment: 17 page

Detecting reciprocity at a global scale

Reciprocity stabilizes cooperation from the level of microbes all the way up to humans interacting in small groups, but does reciprocity also underlie stable cooperation between larger human agglomerations, such as nation States? Famously, evolutionary models show that reciprocity could emerge as a widespread strategy for achieving international cooperation. However, existing studies have only detected reciprocity-driven cooperation in a small number of country pairs. We apply a new method for detecting mutual influence in dynamical systems to a new large-scale data set that records state interactions with high temporal resolution. Doing so, we detect reciprocity between many country pairs in the international system and find that these reciprocating country pairs exhibit qualitatively different cooperative dynamics when compared to nonreciprocating pairs. Consistent with evolutionary theories of cooperation, reciprocating country pairs exhibit higher levels of stable cooperation and are more likely to punish instances of noncooperation. However, countries in reciprocity-based relationships are also quicker to forgive single acts of noncooperation by eventually returning to previous levels of mutual cooperation. By contrast, nonreciprocating pairs are more likely to exploit each other’s cooperation via higher rates of defection. Together, these findings provide the strongest evidence to date that reciprocity is a widespread mechanism for achieving international cooperation

Functional Characterization of the Eukaryotic Cysteine Desulfurase Nfs1p from Saccharomyces cerevisiae

Previous studies have indicated that the essential protein Nfs1 performs a crucial role in cellular iron-sulfur (Fe/S) protein maturation. The protein is located predominantly in mitochondria, yet low amounts are present in cytosol and nucleus. Here we examined several aspects concerning the molecular function of yeast Nfs1p as a model protein. First, we demonstrated that purified Nfs1p facilitates the in vitro assembly of Fe/S proteins by using cysteine as its specific substrate. Thus, eukaryotic Nfs1 is a functional orthologue of the bacterial cysteine desulfurase IscS. Second, we showed that only the mitochondrial version but not the extramitochondrial version of Nfs1p is functional in generating cytosolic and nuclear Fe/S proteins. Mutation of the nuclear targeting signal of Nfs1p did not affect the maturation of cytosolic and nuclear Fe/S proteins, despite a severe growth defect under this condition. Nfs1p could not assemble an Fe/S cluster on the Isu scaffold proteins when they were located in the yeast cytosol. The lack of function of these central Fe/S cluster assembly components suggests that the maturation of extramitochondrial Fe/S protein does not involve functional copies of the mitochondrial Fe/S cluster assembly machinery in the yeast cytosol. Third, the extramitochondrial version of Nfs1p was shown to play a direct role in the thiomodification of tRNAs. Finally, we identified a highly conserved N-terminal {beta}-sheet of Nfs1p as a functionally essential part of the protein. The implication of these findings for the structural stability of Nfs1p and for its targeting mechanism to mitochondria and cytosol/nucleus will be discussed

"Drop in" gastroscopy outpatient clinic - experience after 9 months

<p>Abstract</p> <p>Background</p> <p>Logistics handling referrals for gastroscopy may be more time consuming than the examination itself. For the patient, "drop in" gastroscopy may reduce uncertainty, inadequate therapy and time off work.</p> <p>Methods</p> <p>After an 8-9 month run-in period we asked patients, hospital staff and GPs to fill in a questionnaire to evaluate their experience with "drop in" gastroscopy and gastroscopy by appointment, respectively. The diagnostic gain was evaluated.</p> <p>Results</p> <p>112 patients had "drop in" gastroscopy and 101 gastroscopy by appointment. The number of "drop in" patients varied between 3 and 12 per day (mean 6.5). Mean time from first GP consultation to gastroscopy was 3.6 weeks in the "drop in" group and 14 weeks in the appointment group. The half-yearly number of outpatient gastroscopies increased from 696 before introducing "drop in" to 1022 after (47% increase) and the proportion of examinations with pathological findings increased from 42% to 58%. Patients and GPs expressed great satisfaction with "drop in". Hospital staff also acclaimed although it caused more unpredictable working days with no additional staff.</p> <p>Conclusions</p> <p>"Drop in" gastroscopy was introduced without increase in staff. The observed increase in gastroscopies was paralleled by a similar increase in pathological findings without any apparent disadvantages for other groups of patients. This should legitimise "drop in" outpatient gastroscopies, but it requires meticulous observation of possible unwanted effects when implemented.</p

Blood volume measurement with indocyanine green pulse spectrophotometry: dose and site of dye administration

(1) To determine the optimal administration site and dose of indocyanine green (ICG) for blood volume measurement using pulse spectrophotometry, (2) to assess the variation in repeated blood volume measurements for patients after subarachnoid hemorrhage and (3) to evaluate the safety and efficacy of this technique in patients who were treated for an intracranial aneurysm. Four repeated measurements of blood volume (BV) were performed in random order of bolus dose (10 mg or 25 mg ICG) and venous administration site (peripheral or central) in eight patients admitted for treatment of an intracranial aneurysm. Another five patients with subarachnoid hemorrhage underwent three repeated BV measurements with 25 mg ICG at the same administration site to assess the coefficient of variation. The mean +/- SD in BV was 4.38 +/- 0.88 l (n = 25) and 4.69 +/- 1.11 l (n = 26) for 10 mg and 25 mg ICG, respectively. The mean +/- SD in BV was 4.59 +/- 1.15 l (n = 26) and 4.48 +/- 0.86 l (n = 25) for central and peripheral administration, respectively. No significant difference was found. The coefficient of variance of BV measurement with 25 mg of ICG was 7.5% (95% CI: 3-12%). There is no significant difference between intravenous administration of either 10 or 25 mg ICG, and this can be injected through either a peripheral or central venous catheter. The 7.5% coefficient of variation in BV measurements determines the detectable differences using ICG pulse spectrophotometr

A synthetic, spatially decorrelating solar irradiance generator and application to a LV grid model with high PV penetration

Residential photovoltaic (PV) technology is expected to have mass global deployment. With widespread PV in the electricity distribution grids, the variable nature of the solar resource must be understood to facilitate reliable operation. This research demonstrates that synthetic, 1-min resolution irradiance time series that vary on a spatial dimension can be generated based on the following inputs: mean hourly meteorological observations of okta, wind speed, cloud height and atmospheric pressure. The synthetic time series temporally validate against observed 1-min irradiance data for four locations—Cambourne, UK; Lerwick, UK; San Diego, CA USA; and Oahu, HI USA—when analysing 4 metrics of variability indices, ramp-rate size, irradiance magnitude frequency and clear-sky index frequency. Each metric is calculated for the modelled and observed data at each location and CDF profile correlation compared as well as applying the Kolmogorov-Smirnov (K–S) test with 99% confidence limits. CDF correlation coefficients of each metric are all above R⩾0.908, and a minimum of 90.96% of daily irradiance time series passed the K–S test. A spatial validation was performed comparing the model outputs to real observation data. The spatial correlation coefficient regression with site separation was successfully recreated with MAPE = 0.865%, RMSE = 0.01 and R=0.955. The spatial instantaneous correlation was shown to behave anisotropically when using fixed cloud direction, with different correlation in along and cross wind directions. Cloud cover states of 40–60% showed the most spatial decorrelation while 0% and 100% had the least. The model outputs are applied to a distribution grid impact model using the IEEE-8500 node test feeder. PV scenarios of 25%,50%, and 75% uptake were modelled across a 1.5×1.5 km grid. The magnitude and frequency of severe tap changing events are found to be significantly higher when using a single irradiance time series for all PV systems versus individually assigning spatially decorrelating time series

Comparative genomics of chlamydomonas

Despite its role as a reference organism in the plant sciences, the green alga Chlamydomonas reinhardtii entirely lacks genomic resources from closely related species. We present highly contiguous and well-annotated genome assemblies for three unicellular C. reinhardtii relatives: Chlamydomonas incerta, Chlamydomonas schloesseri, and the more distantly related Edaphochlamys debaryana. The three Chlamydomonas genomes are highly syntenous with similar gene contents, although the 129.2 Mb C. incerta and 130.2 Mb C. schloesseri assemblies are more repeat-rich than the 111.1 Mb C. reinhardtii genome. We identify the major centromeric repeat in C. reinhardtii as a LINE transposable element homologous to Zepp (the centromeric repeat in Coccomyxa subellipsoidea) and infer that centromere locations and structure are likely conserved in C. incerta and C. schloesseri. We report extensive rearrangements, but limited gene turnover, between the minus mating type loci of these Chlamydomonas species. We produce an eight-species core-Reinhardtinia whole-genome alignment, which we use to identify several hundred false positive and missing genes in the C. reinhardtii annotation and >260,000 evolutionarily conserved elements in the C. reinhardtii genome. In summary, these resources will enable comparative genomics analyses for C. reinhardtii, significantly extending the analytical toolkit for this emerging model system

Migration of Th1 Lymphocytes Is Regulated by CD152 (CTLA-4)-Mediated Signaling via PI3 Kinase-Dependent Akt Activation

Efficient adaptive immune responses require the localization of T lymphocytes in secondary lymphoid organs and inflamed tissues. To achieve correct localization of T lymphocytes, the migration of these cells is initiated and directed by adhesion molecules and chemokines. It has recently been shown that the inhibitory surface molecule CD152 (CTLA-4) initiates Th cell migration, but the molecular mechanism underlying this effect remains to be elucidated. Using CD4 T lymphocytes derived from OVA-specific TCR transgenic CD152-deficient and CD152-competent mice, we demonstrate that chemokine-triggered signal transduction is differentially regulated by CD152 via phosphoinositide 3-kinase (PI3K)-dependent activation of protein kinase B (PKB/Akt). In the presence of CD152 signaling, the chemoattractant CCL4 selectively induces the full activation of Akt via phosphorylation at threonine 308 and serine 473 in pro-inflammatory Th lymphocytes expressing the cognate chemokine receptor CCR5. Akt signals lead to cytoskeleton rearrangements, which are indispensable for migration. Therefore, this novel Akt-modulating function of CD152 signals affecting T cell migration demonstrates that boosting CD152 or its down-stream signal transduction could aid therapies aimed at sensitizing T lymphocytes for optimal migration, thus contributing to a precise and effective immune response