8,235 research outputs found
Blending single beam RoxAnn and multi-beam swathe QTC hydro-acoustic discrimination techniques for the Stonehaven area, Scotland, UK
Surface properties of the seabed in a 180 km2 area of coastal waters (14-57 m depth) off northeast Scotland were mapped by hydro-acoustic discrimination using single and multi-beam echosounders linked to signal processing systems (RoxAnn for the single beam, and Questor Tangent Corporation (QTC) Multiview for the multibeam). Subsequently, two ground truthing surveys were carried out, using grab and TV sampling. The RoxAnn and QTC-Multiview outputs showed strong similarity in their classifications of seabed types. Classifications generated by QTC-Multiview were used to supervise those based on seabed roughness and hardness indices produced by the RoxAnn system and thereby develop a ‘blended’ map based on both systems. The resulting hydro-acoustic classes agreed well with a cluster analysis of data on sediment grain sizes from the grab sampling, and indicated that the area could be described by distinct regions of surface texture and surficial sediments ranging from muddy sand to boulders and rock
Efficient implementation of the Gutzwiller variational method
We present a self-consistent numerical approach to solve the Gutzwiller
variational problem for general multi-band models with arbitrary on-site
interaction. The proposed method generalizes and improves the procedure derived
by Deng et al., Phys. Rev. B. 79 075114 (2009), overcoming the restriction to
density-density interaction without increasing the complexity of the
computational algorithm. Our approach drastically reduces the problem of the
high-dimensional Gutzwiller minimization by mapping it to a minimization only
in the variational density matrix, in the spirit of the Levy and Lieb
formulation of DFT. For fixed density the Gutzwiller renormalization matrix is
determined as a fixpoint of a proper functional, whose evaluation only requires
ground-state calculations of matrices defined in the Gutzwiller variational
space. Furthermore, the proposed method is able to account for the symmetries
of the variational function in a controlled way, reducing the number of
variational parameters. After a detailed description of the method we present
calculations for multi-band Hubbard models with full (rotationally invariant)
Hund's rule on-site interaction. Our analysis shows that the numerical
algorithm is very efficient, stable and easy to implement. For these reasons
this method is particularly suitable for first principle studies -- e.g., in
combination with DFT -- of many complex real materials, where the full
intra-atomic interaction is important to obtain correct results.Comment: 19 pages, 7 figure
Haemophilus influenzae type b reemergence after combination immunization
An increase in Haemophilus influenzae type b (Hib) in
British children has been linked to the widespread use of a
diphtheria/tetanus/acellular pertussis combination vaccine
(DTaP-Hib). We measured anti-polyribosyl-ribitol phos-
phate antibody concentration and avidity before and after a
Hib booster in 176 children 2–4 years of age who had
received 3 doses of DTP-Hib (either DT whole cell pertus-
sis-Hib or DTaP-Hib) combination vaccine in infancy. We
also measured pharyngeal carriage of Hib. Antibody con-
centrations before and avidity indices after vaccination
were low (geometric mean concentration 0.46μg/mL, 95%
confidence interval [CI] 0.36–0.58; geometric mean avidity
index 0.16, 95% CI 0.14–0.18) and inversely related to the
number of previous doses of DTaP-Hib (p = 0.02 and
p<0.001, respectively). Hib was found in 2.1% (95% CI
0.7%–6.0%) of study participants. Our data support an
association between DTaP-Hib vaccine combinations and
clinical Hib disease through an effect on antibody concen-
tration and avidit
The Dynamical Mean Field Theory phase space extension and critical properties of the finite temperature Mott transition
We consider the finite temperature metal-insulator transition in the half
filled paramagnetic Hubbard model on the infinite dimensional Bethe lattice. A
new method for calculating the Dynamical Mean Field Theory fixpoint surface in
the phase diagram is presented and shown to be free from the convergence
problems of standard forward recursion. The fixpoint equation is then analyzed
using dynamical systems methods. On the fixpoint surface the eigenspectra of
its Jacobian is used to characterize the hysteresis boundaries of the first
order transition line and its second order critical end point. The critical
point is shown to be a cusp catastrophe in the parameter space, opening a
pitchfork bifurcation along the first order transition line, while the
hysteresis boundaries are shown to be saddle-node bifurcations of two merging
fixpoints. Using Landau theory the properties of the critical end point is
determined and related to the critical eigenmode of the Jacobian. Our findings
provide new insights into basic properties of this intensively studied
transition.Comment: 11 pages, 12 figures, 1 tabl
Measuring Motivation and Reward-Related Decision Making in the Rodent Operant Touchscreen System.
This is the author accepted manuscript. The final version is available from Wiley via http://dx.doi.org/10.1002/0471142301.ns0834s74This unit is designed to facilitate implementation of the fixed and progressive ratio paradigms and the effort-related choice task in the rodent touchscreen apparatus to permit direct measurement of motivation and reward-related decision making in this equipment. These protocols have been optimized for use in the mouse and reliably yield stable performance levels that can be enhanced or suppressed by systemic pharmacological manipulation. Instructions are also provided for the adjustment of task parameters to permit use in mouse models of neurodegenerative disease. These tasks expand the utility of the rodent touchscreen apparatus beyond the currently available battery of cognitive assessment paradigms.The protocols presented in this Unit were developed and optimized as part of a research program funded by Wellcome Trust grant 089703/Z/09/Z awarded to TJB and LMS. TJB and LMS also received funding from the Innovative Medicine Initiative Joint Undertaking under grant agreement n° 115008 of which resources are composed of EFPIA in-kind contribution and financial contribution from the European Union’s Seventh Framework Programme (FP7/2007- 2013). TJB and LMS consult for Campden Instruments Ltd
Singular del Pezzo surfaces that are equivariant compactifications
We determine which singular del Pezzo surfaces are equivariant
compactifications of G_a^2, to assist with proofs of Manin's conjecture for
such surfaces. Additionally, we give an example of a singular quartic del Pezzo
surface that is an equivariant compactification of a semidirect product of G_a
and G_m.Comment: 14 pages, main result extended to non-closed ground field
Selective effects of 5-HT2C receptor modulation on performance of a novel valence-probe visual discrimination task and probabilistic reversal learning in mice.
RATIONALE: Dysregulation of the serotonin (5-HT) system is a pathophysiological component in major depressive disorder (MDD), a condition closely associated with abnormal emotional responsivity to positive and negative feedback. However, the precise mechanism through which 5-HT tone biases feedback responsivity remains unclear. 5-HT2C receptors (5-HT2CRs) are closely linked with aspects of depressive symptomatology, including abnormalities in reinforcement processes and response to stress. Thus, we aimed to determine the impact of 5-HT2CR function on response to feedback in biased reinforcement learning. METHODS: We used two touchscreen assays designed to assess the impact of positive and negative feedback on probabilistic reinforcement in mice, including a novel valence-probe visual discrimination (VPVD) and a probabilistic reversal learning procedure (PRL). Systemic administration of a 5-HT2CR agonist and antagonist resulted in selective changes in the balance of feedback sensitivity bias on these tasks. RESULTS: Specifically, on VPVD, SB 242084, the 5-HT2CR antagonist, impaired acquisition of a discrimination dependent on appropriate integration of positive and negative feedback. On PRL, SB 242084 at 1 mg/kg resulted in changes in behaviour consistent with reduced sensitivity to positive feedback. In contrast, WAY 163909, the 5-HT2CR agonist, resulted in changes associated with increased sensitivity to positive feedback and decreased sensitivity to negative feedback. CONCLUSIONS: These results suggest that 5-HT2CRs tightly regulate feedback sensitivity bias in mice with consequent effects on learning and cognitive flexibility and specify a framework for the influence of 5-HT2CRs on sensitivity to reinforcement
Language and theory of mind in autism spectrum disorder : the relationship between complement syntax and false belief task performance.
This study aimed to test the hypothesis that children with autism spectrum disorder (ASD) use their knowledge of complement syntax as a means of “hacking out” solutions to false belief tasks, despite lacking a representational theory of mind (ToM). Participants completed a “memory for complements” task, a measure of receptive vocabulary, and traditional location change and unexpected contents false belief tasks. Consistent with predictions, the correlation between complement syntax score and location change task performance was significantly stronger within the ASD group than within the comparison group. However, contrary to predictions, complement syntax score was not significantly correlated with unexpected contents task performance within either group. Possible explanations for this pattern of results are considered
Meropenem vs standard of care for treatment of neonatal late onset sepsis (NeoMero1): A randomised controlled trial.
BACKGROUND: The early use of broad-spectrum antibiotics remains the cornerstone for the treatment of neonatal late onset sepsis (LOS). However, which antibiotics should be used is still debatable, as relevant studies were conducted more than 20 years ago, recruited in single centres or countries, evaluated antibiotics not in clinical use anymore and had variable inclusion/exclusion criteria and outcome measures. Moreover, antibiotic-resistant bacteria have become a major problem in many countries worldwide. We hypothesized that efficacy of meropenem as a broad-spectrum antibiotic is superior to standard of care regimens (SOC) in empiric treatment of LOS and aimed to compare meropenem to SOC in infants aged 44 weeks meeting the Goldstein criteria of sepsis, were randomized in a 1:1 ratio to receive meropenem or one of the two SOC regimens (ampicillin+gentamicin or cefotaxime+gentamicin) chosen by each site prior to the start of the study for 8-14 days. The primary outcome was treatment success (survival, no modification of allocated therapy, resolution/improvement of clinical and laboratory markers, no need of additional antibiotics and presumed/confirmed eradication of pathogens) at test-of-cure visit (TOC) in full analysis set. Stool samples were tested at baseline and Day 28 for meropenem-resistant Gram-negative organisms (CRGNO). The primary analysis was performed in all randomised patients and in patients with culture confirmed LOS. Proportions of participants with successful outcome were compared by using a logistic regression model adjusted for the stratification factors. From September 3, 2012 to November 30th 2014, total of 136 patients (instead of planned 275) in each arm were randomized; 140 (52%) were culture positive. Successful outcome at TOC was achieved in 44/136 (32%) in the meropenem arm vs. 31/135 (23%) in the SOC arm (p = 0.087). The respective numbers in patients with positive cultures were 17/63 (27%) vs. 10/77 (13%) (p = 0.022). The main reason of failure was modification of allocated therapy. Treatment emergent adverse events occurred in 72% and serious adverse events in 17% of patients, the Day 28 mortality was 6%. Cumulative acquisition of CRGNO by Day 28 occurred in 4% of patients in the meropenem and 12% in the SOC arm (p = 0.052). CONCLUSIONS: Within this study population, we found no evidence that meropenem was superior to SOC in terms of success at TOC, short term hearing disturbances, safety or mortality were similar in both treatment arms but the study was underpowered to detect the planned effect. Meropenem treatment did not select for colonization with CRGNOs. We suggest that meropenem as broad-spectrum antibiotic should be reserved for neonates who are more likely to have Gram-negative LOS, especially in NICUs where microorganisms producing extended spectrum- and AmpC type beta-lactamases are circulating
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