Constraint Effective Potential of the Staggered Magnetization in an Antiferromagnet

We employ an improved estimator to calculate the constraint effective potential of the staggered magnetization in the spin $\tfrac{1}{2}$ quantum Heisenberg model using a loop-cluster algorithm. The first and second moment of the probability distribution of the staggered magnetization are in excellent agreement with the predictions of the systematic low-energy magnon effective field theory. We also compare the Monte Carlo data with the universal shape of the constraint effective potential of the staggered magnetization and study its approach to the convex effective potential in the infinite volume limit. In this way the higher-order low-energy parameter $k_0$ is determined from a fit to the numerical data

Revision of an open-split-based dual-inlet system for elemental and isotope ratio mass spectrometers with a focus on clumped-isotope measurements

In this work, we present a revision of an open-split-based dual-inlet system for elemental and isotope ratio mass spectrometers (IRMSs), which was developed by the division of Climate and Environmental Physics of the University of Bern 2 decades ago. Besides discussing the corresponding improvements we show that with this inlet system (NIS-II, New Inlet System II) external precisions can be achieved that are high enough to perform measurements of multiply substituted isotopologues (clumped isotopes) on pure gases. For clumped-isotope ratios 35/32 and 36/32 of oxygen, we achieved standard deviations of 3.4×10-9 and 4.9×10-9, respectively, that we calculated from 60 interval means (20 s integration) of pure-oxygen gas measurements. Moreover, we report various performance tests and show that delta values of various air components can be measured with precisions of the order of tens of per meg and higher with the NIS-II. In addition, we demonstrate that our new open-split-based dual-inlet system allows us to measure some of these delta values with significantly higher precisions than an NIS-I (precursor of the NIS-II) and conventional changeover-valve-based dual-inlet systems (tests performed with two dual-inlet systems built by Elementar and Thermo Finnigan). Especially, our measurements point out that our inlet system provides reliable results at short idle times (20 s) and that the corresponding data do not need to be corrected for non-linearity. However, the sample consumption of our open-split-based dual-inlet system is several orders of magnitude higher than that of changeover-valve-based ones (0.33 sccm versus 0.005 sccm; standard cubic centimetres per minute). Due to the successful preliminary tests regarding measurements of clumped-isotope ratios, we will continue our work in this area to perform clumped-isotope studies according to common practices.</p

Higher Yield and Fewer Weeds in Four-Species Grass/Legume Mixtures Than in Monocultures: Results from the First Year at 20 Sites of Cost Action 852

Utilisation of grass/legume mixtures instead of grass monocultures is a sensible alternative for low input, efficient agricultural systems that reduce production costs, promote environmental policy and maintain a living countryside. Consequently, widely adapted forage legumes will become increasingly important. Instability of simple grass / legume mixtures with only one grass and one legume species is a major problem (Wachendorf et al., 2001). An experiment was established in 39 sites in Europe, Australia and Canada within COST Action 852 to: (1) assess the benefits of grass / legume mixtures in terms of forage production, (2) test whether the combination of fast and slow-growing species improves the stability of the mixtures and (3) assess response patterns over a large environmental gradient

Civil Aircraft for the regular investigation of the atmosphere based on an instrumented container: The new CARIBIC system

An airfreight container with automated instruments for measurement of atmospheric gases and trace compounds was operated on a monthly basis onboard a Boeing 767-300 ER of LTU International Airways during long-distance flights from 1997 to 2002 (CARIBIC, Civil Aircraft for Regular Investigation of the Atmosphere Based on an Instrument Container, http://www.caribic-atmospheric.com). Subsequently a more advanced system has been developed, using a larger capacity container with additional equipment and an improved inlet system. CARIBIC phase #2 was implemented on a new long-range aircraft type Airbus A340-600 of the Lufthansa German Airlines (Star Alliance) in December 2004, creating a powerful flying observatory. The instrument package comprises detectors for the measurement of O3, total and gaseous H2O, NO and NOy, CO, CO2, O2, Hg, and number concentrations of sub-micrometer particles (>4 nm, >12 nm, and >18 nm diameter). Furthermore, an optical particle counter (OPC) and a proton transfer mass spectrometer (PTR-MS) are incorporated. Aerosol samples are collected for analysis of elemental composition and particle morphology after flight. Air samples are taken in glass containers for laboratory analyses of hydrocarbons, halocarbons and greenhouse gases (including isotopic composition of CO2) in several laboratories. Absorption tubes collect oxygenated volatile organic compounds. Three differential optical absorption spectrometers (DOAS) with their telescopes mounted in the inlet system measure atmospheric trace gases such as BrO, HONO, and NO2. A video camera mounted in the inlet provides information about clouds along the flight track. The flying observatory, its equipment and examples of measurement results are reported

Measurement of the Bottom-Strange Meson Mixing Phase in the Full CDF Data Set

We report a measurement of the bottom-strange meson mixing phase \beta_s using the time evolution of B0_s -> J/\psi (->\mu+\mu-) \phi (-> K+ K-) decays in which the quark-flavor content of the bottom-strange meson is identified at production. This measurement uses the full data set of proton-antiproton collisions at sqrt(s)= 1.96 TeV collected by the Collider Detector experiment at the Fermilab Tevatron, corresponding to 9.6 fb-1 of integrated luminosity. We report confidence regions in the two-dimensional space of \beta_s and the B0_s decay-width difference \Delta\Gamma_s, and measure \beta_s in [-\pi/2, -1.51] U [-0.06, 0.30] U [1.26, \pi/2] at the 68% confidence level, in agreement with the standard model expectation. Assuming the standard model value of \beta_s, we also determine \Delta\Gamma_s = 0.068 +- 0.026 (stat) +- 0.009 (syst) ps-1 and the mean B0_s lifetime, \tau_s = 1.528 +- 0.019 (stat) +- 0.009 (syst) ps, which are consistent and competitive with determinations by other experiments.Comment: 8 pages, 2 figures, Phys. Rev. Lett 109, 171802 (2012

Soluble NgR Fusion Protein Modulates the Proliferation of Neural Progenitor Cells via the Notch Pathway

NogoA, myelin-associated glycoprotein (MAG) and oligodendrocyte myelin glycoprotein are CNS myelin molecules that bind to the neuronal Nogo-66 receptor (NgR) and inhibit axon growth. The NgR antagonist, soluble NgR1-Fc protein (sNgR-Fc), facilitates axon regeneration by neutralizing the inhibitory effects of myelin proteins in experimental models of CNS injury. Here we aim to investigate the effect of sNgR-Fc on the proliferation of neural progenitor cells (NPCs). The hippocampus cells of embryonic rats were isolated and cultured in vitro. The expression of nestin, βIII-Tubulin, GFAP and Nogo-A on these cells was observed using immunocytochemistry. In order to investigate the effect on proliferation of NPCs, sNgR-Fc, MAG-Fc chimera and Notch1 blocker were added respectively. The total cell number for the proliferated NPCs was counted. BrdU was applied and the rate of proliferating cells was examined. The level of Notch1 was analyzed using Western blotting. We identified that NogoA is expressed in NPCs. sNgR-Fc significantly enhanced the proliferation of NPCs in vitro as indicated by BrdU labeling and total cell count. This proliferation effect was abolished by the administration of MAG suggesting specificity. In addition, we demonstrate that sNgR-Fc is a potent activator for Notch1 and Notch1 antagonist reversed the effect of sNgR-Fc on NPC proliferation. Our results suggest that sNgR-Fc may modulate Nogo activity to induce NPC proliferation via the Notch pathway

Measured and Simulated Nitrous Oxide Emissions from Ryegrass- and Ryegrass/White Clover-Based Grasslands in a Moist Temperate Climate

There is uncertainty about the potential reduction of soil nitrous oxide (N2O) emission when fertilizer nitrogen (FN) is partially or completely replaced by biological N fixation (BNF) in temperate grassland. The objectives of this study were to 1) investigate the changes in N2O emissions when BNF is used to replace FN in permanent grassland, and 2) evaluate the applicability of the process-based model DNDC to simulate N2O emissions from Irish grasslands. Three grazing treatments were: (i) ryegrass (Lolium perenne) grasslands receiving 226 kg FN ha−1 yr−1 (GG+FN), (ii) ryegrass/white clover (Trifolium repens) grasslands receiving 58 kg FN ha−1 yr−1 (GWC+FN) applied in spring, and (iii) ryegrass/white clover grasslands receiving no FN (GWC-FN). Two background treatments, un-grazed swards with ryegrass only (G–B) or ryegrass/white clover (WC–B), did not receive slurry or FN and the herbage was harvested by mowing. There was no significant difference in annual N2O emissions between G–B (2.38±0.12 kg N ha−1 yr−1 (mean±SE)) and WC-B (2.45±0.85 kg N ha−1 yr−1), indicating that N2O emission due to BNF itself and clover residual decomposition from permanent ryegrass/clover grassland was negligible. N2O emissions were 7.82±1.67, 6.35±1.14 and 6.54±1.70 kg N ha−1 yr−1, respectively, from GG+FN, GWC+FN and GWC-FN. N2O fluxes simulated by DNDC agreed well with the measured values with significant correlation between simulated and measured daily fluxes for the three grazing treatments, but the simulation did not agree very well for the background treatments. DNDC overestimated annual emission by 61% for GG+FN, and underestimated by 45% for GWC-FN, but simulated very well for GWC+FN. Both the measured and simulated results supported that there was a clear reduction of N2O emissions when FN was replaced by BNF

Stem cells of ependymoma

Ependymomas are tumours that arise throughout the central nervous system. Little is known regarding the aberrant cellular and molecular processes that generate these tumours. This lack of knowledge has hampered efforts to reduce the significant mortality and morbidity that are associated with ependymoma. Here, we review recent data that suggest that radial glia are cells of origin of ependymoma, and discuss the processes that might transform these neural progenitors into ependymoma cancer stem cells

Th1 type lymphocyte reactivity to metals in patients with total hip arthroplasty

<p>Abstract</p> <p>Background</p> <p>All prostheses with metallic components release metal debris that can potentially activate the immune system. However, implant-related metal hyper-reactivity has not been well characterized. In this study, we hypothesized that adaptive immunity reaction(s), particularly T-helper type 1 (Th1) responses, will be dominant in any metal-reactivity responses of patients with total joint replacements (TJAs). We tested this hypothesis by evaluating lymphocyte reactivity to metal "ions" in subjects with and without total hip replacements, using proliferation assays and cytokine analysis.</p> <p>Methods</p> <p>Lymphocytes from young healthy individuals without an implant or a history of metal allergy (Group 1: n = 8) were used to assess lymphocyte responses to metal challenge agents. In addition, individuals (Group 2: n = 15) with well functioning total hip arthroplasties (average Harris Hip Score = 91, average time in-situ 158 months) were studied. Age matched controls with no implants were also used for comparison (Group 3, n = 8, 4 male, 4 female average age 70, range 49–80). Group 1 subjects' lymphocyte proliferation response to Aluminum⁺³, Cobalt⁺², Chromium⁺³, Copper⁺², Iron⁺³, Molybdenum⁺⁵, Manganeese⁺², Nickel⁺², Vanadium⁺³and Sodium⁺²chloride solutions at a variety of concentrations (0.0, 0.05, 0.1, 0.5, 1.0 and 10.0 mM) was studied to establish toxicity thresholds. Mononuclear cells from Group 2 and 3 subjects were challenged with 0.1 mM CrCl₃, 0.1 mM NiCl₂, 0.1 mM CoCl₂and approx. 0.001 mM titanium and the reactions measured with proliferation assays and cytokine analysis to determine T-cell subtype prominence.</p> <p>Results</p> <p>Primary lymphocytes from patients with well functioning total hip replacements demonstrated a higher incidence and greater magnitude of reactivity to chromium than young healthy controls (p < 0.03). Of the 15 metal ion-challenged subjects with well functioning total hip arthroplasties, 7 demonstrated a proliferative response to Chromium, Nickel, Cobalt and/or Titanium (as defined by a statistically significant >2 fold stimulation index response, p < 0.05) and were designated as metal-reactive. Metals such as Cobalt, Copper, Manganese, and Vanadium were toxic at concentrations as low as 0.5 mM while other metals, such as Aluminum, Chromium, Iron, Molybdenum, and Nickel, became toxic at much higher concentrations (>10 mM). The differential secretion of signature T-cell subsets' cytokines (Th1 and Th2 lymphocytes releasing IFN-gamma and IL-4, respectively) between those total hip arthroplasty subjects which demonstrated metal-reactivity and those that did not, indicated a Th1 type (IFN-gamma) pro-inflammatory response.</p> <p>Conclusion</p> <p>Elevated proliferation and production of IFN-gamma to metals in hip arthroplasty subjects' lymphocytes indicates that a Th1 (vs. Th2) type response is likely associated with any metal induced reactivity. The involvement of an elevated and specific lymphocyte response suggests an <it>adaptive </it>(macrophage recruiting) immunity response to metallic implant debris rather than an <it>innate </it>(nonspecific) immune response.</p

PKA regulatory subunits mediate synergy among conserved G-protein-coupled receptor cascades

G-protein-coupled receptors sense extracellular chemical or physical stimuli and transmit these signals to distinct trimeric G-proteins. Activated Gα-proteins route signals to interconnected effector cascades, thus regulating thresholds, amplitudes and durations of signalling. Gαs- or Gαi-coupled receptor cascades are mechanistically conserved and mediate many sensory processes, including synaptic transmission, cell proliferation and chemotaxis. Here we show that a central, conserved component of Gαs-coupled receptor cascades, the regulatory subunit type-II (RII) of protein kinase A undergoes adenosine 3′-5′-cyclic monophosphate (cAMP)-dependent binding to Gαi. Stimulation of a mammalian Gαi-coupled receptor and concomitant cAMP-RII binding to Gαi, augments the sensitivity, amplitude and duration of Gαi:βγ activity and downstream mitogen-activated protein kinase signalling, independent of protein kinase A kinase activity. The mechanism is conserved in budding yeast, causing nutrient-dependent modulation of a pheromone response. These findings suggest a direct mechanism by which coincident activation of Gαs-coupled receptors controls the precision of adaptive responses of activated Gαi-coupled receptor cascades