Determination of nitrogen in titanium nitride

Quantitative determination of nitrogen in titanium nitride involves dissolution of TiN in 10M hydrofluoric acid containing an oxidant. Released nitrogen is determined as ammonia. Best oxidizers are ferric chloride, potassium iodate, and potassium dichromate

Detecting groundwater discharge dynamics from point-to-catchment scale in a lowland stream : Combining hydraulic and tracer methods

Acknowledgements. We would like to thank members of the Northern Rivers Institute, Aberdeen University, for helpful discussions of data. We also thank Lars Rasmussen, Jolanta Kazmierczak and Charlotte Ditlevsen for help in the field. This study is part of the Hydrology Observatory, HOBE (http://www.hobe.dk), funded by the Villum Foundation and was as well funded by the Aarhus University Research Foundation.Peer reviewedPublisher PD

Signal Propagation in Feedforward Neuronal Networks with Unreliable Synapses

In this paper, we systematically investigate both the synfire propagation and firing rate propagation in feedforward neuronal network coupled in an all-to-all fashion. In contrast to most earlier work, where only reliable synaptic connections are considered, we mainly examine the effects of unreliable synapses on both types of neural activity propagation in this work. We first study networks composed of purely excitatory neurons. Our results show that both the successful transmission probability and excitatory synaptic strength largely influence the propagation of these two types of neural activities, and better tuning of these synaptic parameters makes the considered network support stable signal propagation. It is also found that noise has significant but different impacts on these two types of propagation. The additive Gaussian white noise has the tendency to reduce the precision of the synfire activity, whereas noise with appropriate intensity can enhance the performance of firing rate propagation. Further simulations indicate that the propagation dynamics of the considered neuronal network is not simply determined by the average amount of received neurotransmitter for each neuron in a time instant, but also largely influenced by the stochastic effect of neurotransmitter release. Second, we compare our results with those obtained in corresponding feedforward neuronal networks connected with reliable synapses but in a random coupling fashion. We confirm that some differences can be observed in these two different feedforward neuronal network models. Finally, we study the signal propagation in feedforward neuronal networks consisting of both excitatory and inhibitory neurons, and demonstrate that inhibition also plays an important role in signal propagation in the considered networks.Comment: 33pages, 16 figures; Journal of Computational Neuroscience (published

XMM-Newton observation of PSR B2224+65 and its jet

We have investigated the pulsar PSR B2224+65 and its X-ray jet with XMM-Newton. Apart from the long X-ray jet which is almost perpendicular to the direction of proper motion, a putative extended feature at the pulsar position, which oriented in the opposite direction of the proper motion, is also suggested by this deep X-ray imaging. Non-detection of any coherent X-ray pulsation disfavors the magnetospheric origin of the X-rays observed from the position of PSR B2224+65 and hence suggest that the interpretation of pulsar wind nebula is more viable. We have also probed the origin of PSR B2224+65 and identified a runaway star, which possibly originated from the Cygnus OB9 association, as a candidate for the former binary companion of the neutron star's progenitor.Comment: 24 pages, 8 figures, 3 tables, accepted for publication in Ap

Prioritization of fish communities with a view to conservation and restoration on a large scale European basin, the Loire (France)

The hierarchical organization of important sites for the conservation or the restoration of fish communities is a great challenge for managers, especially because of financial or time constraints. In this perspective, we developed a methodology, which is easy to implement in different locations. Based on the fish assemblage characteristics of the Loire basin (France), we created a synthetic conservation value index including the rarity, the conservation status and the species origin. The relationship between this new synthetic index and the Fish-Based Index allowed us to establish a classification protocol of the sites along the Loire including fish assemblages to be restored or conserved. Sites presenting disturbed fish assemblages, a low rarity index, few threatened species, and a high proportion of non-native species were considered as important for the restoration of fish biodiversity. These sites were found mainly in areas where the assemblages are typical of the bream zone, e.g. with a higher number of eurytopic and limnophilic species. On the contrary, important sites for conservation were defined as having an important conservation potential (high RI, a lot of threatened species, and few nonnatives fish species) and an undisturbed fish assemblage similar to the expected community if habitats are undisturbed. Important sites for conservation were found in the Loire basin’s medium reaches which host assemblages typical for the grayling and the barbell zones, e.g. with a higher number of rheophilic species. The synthetic conservation value index could be adapted and completed with other criteria according to management priorities and capacities

Diaspirin-crosslinked hemoglobin reduces blood transfusion in noncardiac surgery: a multicenter, randomized, controlled, double-blinded trial.

UNLABELLED: In this randomized, prospective, double-blinded clinical trial, we sought to investigate whether diaspirin-crosslinked hemoglobin (DCLHb) can reduce the perioperative use of allogeneic blood transfusion. One-hundred-eighty-one elective surgical patients were enrolled at 19 clinical sites from 1996 to 1998. Selection criteria included anticipated transfusion of 2-4 blood units, aortic repair, and major joint or abdomino-pelvic surgery. Once a decision to transfuse had been made, patients received initially up to 3 250-mL infusions of 10% DCLHb (n = 92) or 3 U of packed red blood cells (PRBCs) (n = 89). DCLHb was infused during a 36-h perioperative window. On the day of surgery, 58 of 92 (64%; confidence interval [CI], 54%-74%) DCLHb-treated patients received no allogeneic PRBC transfusions. On Day 1, this number was 44 of 92 (48%; CI, 37%-58%) and decreased further until Day 7, when it was 21 of 92 (23%; CI, 15%-33%). During the 7-day period, 2 (1-4) units of PRBC per patient were used in the DCLHb group compared with 3 (2-4) units in the control patients (P = 0.002; medians and 25th and 75th percentiles). Mortality (4% and 3%, respectively) and incidence of suffering at least one serious adverse event (21% and 15%, respectively) were similar in DCLHb and PRBC groups. The incidence of jaundice, urinary side effects, and pancreatitis were more frequent in DCLHb patients. The study was terminated early because of safety concerns. Whereas the side-effect profile of modified hemoglobin solutions needs to be improved, our data show that hemoglobin solutions can be effective at reducing exposure to allogeneic blood for elective surgery. IMPLICATIONS: In a randomized, double-blinded red blood cell controlled, multicenter trial, diaspirin-crosslinked hemoglobin spared allogeneic transfusion in 23% of patients undergoing elective noncardiac surgery. The observed side-effect profile indicates a need for improvement in hemoglobin development

Ventilation-perfusion inequality in the human lung is not increased following no-decompression-stop hyperbaric exposure

Venous gas bubbles occur in recreational SCUBA divers in the absence of decompression sickness, forming venous gas emboli (VGE) which are trapped within pulmonary circulation and cleared by the lung without overt pathology. We hypothesized that asymptomatic VGE would transiently increase ventilation-perfusion mismatch due to their occlusive effects within the pulmonary circulation. Two sets of healthy volunteers (n = 11, n = 12) were recruited to test this hypothesis with a single recreational ocean dive or a baro-equivalent dry hyperbaric dive. Pulmonary studies (intrabreath VA/Q (iV/Q), alveolar dead space, and FVC) were conducted at baseline and repeat 1- and 24-h after the exposure. Contrary to our hypothesis VA/Q mismatch was decreased 1-h post-SCUBA dive (iV/Q slope 0.023 ± 0.008 ml−1 at baseline vs. 0.010 ± 0.005 NS), and was significantly reduced 24-h post-SCUBA dive (0.000 ± 0.005, p < 0.05), with improved VA/Q homogeneity inversely correlated to dive severity. No changes in VA/Q mismatch were observed after the chamber dive. Alveolar dead space decreased 24-h post-SCUBA dive (78 ± 10 ml at baseline vs. 56 ± 5, p < 0.05), but not 1-h post dive. FVC rose 1-h post-SCUBA dive (5.01 ± 0.18 l vs. 5.21 ± 0.26, p < 0.05), remained elevated 24-h post SCUBA dive (5.06 ± 0.2, p < 0.05), but was decreased 1-hr after the chamber dive (4.96 ± 0.31 L to 4.87 ± 0.32, p < 0.05). The degree of VA/Q mismatch in the lung was decreased following recreational ocean dives, and was unchanged following an equivalent air chamber dive, arguing against an impact of VGE on the pulmonary circulation

A Fokker-Planck formalism for diffusion with finite increments and absorbing boundaries

Gaussian white noise is frequently used to model fluctuations in physical systems. In Fokker-Planck theory, this leads to a vanishing probability density near the absorbing boundary of threshold models. Here we derive the boundary condition for the stationary density of a first-order stochastic differential equation for additive finite-grained Poisson noise and show that the response properties of threshold units are qualitatively altered. Applied to the integrate-and-fire neuron model, the response turns out to be instantaneous rather than exhibiting low-pass characteristics, highly non-linear, and asymmetric for excitation and inhibition. The novel mechanism is exhibited on the network level and is a generic property of pulse-coupled systems of threshold units.Comment: Consists of two parts: main article (3 figures) plus supplementary text (3 extra figures

Co-transplantation of Human Embryonic Stem Cell-derived Neural Progenitors and Schwann Cells in a Rat Spinal Cord Contusion Injury Model Elicits a Distinct Neurogenesis and Functional Recovery

Co-transplantation of neural progenitors (NPs) with Schwann cells (SCs) might be a way to overcome low rate of neuronal differentiation of NPs following transplantation in spinal cord injury (SCI) and the improvement of locomotor recovery. In this study, we initially generated NPs from human embryonic stem cells (hESCs) and investigated their potential for neuronal differentiation and functional recovery when co-cultured with SCs in vitro and co-transplanted in a rat acute model of contused SCI. Co-cultivation results revealed that the presence of SCs provided a consistent status for hESC-NPs and recharged their neural differentiation toward a predominantly neuronal fate. Following transplantation, a significant functional recovery was observed in all engrafted groups (NPs, SCs, NPs+SCs) relative to the vehicle and control groups. We also observed that animals receiving co-transplants established a better state as assessed with the BBB functional test. Immunohistofluorescence evaluation five weeks after transplantation showed invigorated neuronal differentiation and limited proliferation in the co-transplanted group when compared to the individual hESC-NPs grafted group. These findings have demonstrated that the co-transplantation of SCs with hESC-NPs could offer a synergistic effect, promoting neuronal differentiation and functional recovery