Low-temperature magnetism of KAgF3

KAgF3 is a quasi-one-dimensional quantum antiferromagnet hosting a series of intriguing structural and magnetic transitions. Here we use powder neutron diffraction, μSR spectroscopy, and density functional theory calculations to elucidate the low-temperature magnetic phases. Below TN1 = 29 K we find that the material orders as an A-type antiferromagnet with an ordered moment of 0.52 μ B . Both neutrons and muons provide evidence for an intermediate phase at temperatures TN1 < T < TN2 with TN2 ≈ 66 K from a previous magnetometry study. However, the evidence is at the limit of detection and its nature remains an open problem

Epidemiology and Treatment Guidelines of Negative Symptoms in Schizo-phrenia in Central and Eastern Europe: A Literature Review

AIM: To gather and review data describing the epidemiology of schizophrenia and clinical guidelines for schizophrenia therapy in seven Central and Eastern European countries, with a focus on negative symptoms. Methods : A literature search was conducted which included publications from 1995 to 2012 that were indexed in key databases. Results : Reports of mean annual incidence of schizophrenia varied greatly, from 0.04 to 0.58 per 1,000 population. Lifetime prevalence varied from 0.4% to 1.4%. One study reported that at least one negative symptom was present in 57.6% of patients with schizophrenia and in 50-90% of individuals experiencing their first episode of schizophrenia. Primary negative symptoms were observed in 10-30% of patients. Mortality in patients with schizophrenia was greater than in the general population, with a standardized mortality ratio of 2.58-4.30. Reasons for higher risk of mortality in the schizophrenia population included increased suicide risk, effect of schizophrenia on lifestyle and environment, and presence of comorbidities. Clinical guidelines overall supported the use of second-generation antipsychotics in managing negative symptoms of schizophrenia, although improved therapeutic approaches are needed. Conclusion : Schizophrenia is one of the most common mental illnesses and poses a considerable burden on patients and healthcare resources alike. Negative symptoms are present in many patients and there is an unmet need to improve treatment offerings for negative symptoms beyond the use of second-generation antipsychotics and overall patient outcomes

Femtosecond tunneling of polarons in Pb5Cr3F19

The complex dielectric constant/ac electrical conductivity was investigated as a function of frequency and temperature in Pb5Cr3F19. The system undergoes a ferroelectric phase transition at higher temperatures. At lower temperatures the real part of the complex ac electric conductivity was found to follow the universal dielectric response (UDR) σ′ ∝ νs, typical for hopping or tunneling of localized charge carriers. A detailed analysis of the temperature dependence of the UDR parameter s in terms of the theoretical model for tunneling of small polarons revealed that, at low temperatures, this mechanism governs the charge transport in Pb5Cr3F19. The value of the inverse attempt frequency τ0 indicates the femtosecond tunneling of polarons in the system similar to the Büttiker–Landauer transversal time

Polarons in magnetoelectric K

The ac electrical conductivity of magnetoelectric K3Fe5F15 was investigated as a function of frequency and temperature. While at higher temperatures charge transport is governed by a thermally activated process, at lower temperatures the real part of the complex ac electric conductivity was found to follow the universal dielectric response $\sigma^\prime\propto\nu^{s}$, being typical for hopping or tunnelling of localized charge carriers. A detailed analysis of the temperature dependence of the UDR parameter s in terms of the theoretical model for tunnelling of small polarons revealed that, below 80 K, this mechanism governs the charge transport in the K3Fe5F15 magnetoelectric fluoride system

A real time capable quasi 3D system level model of PEM fuel cells

System level simulations, which are gaining on importance in the product concept design process and in the Hardware-in-the-Loop (HiL) applications, require models that feature high level of accuracy, high level of prediction capability and short computational times. This paper presents an innovative mechanistic quasi 3D model capable of real time computation of steady state and transient fuel cell operation. This model relies on a hybrid 3D analytic-numerical model (HAN) approach, which models species transport by taking 1D numerical model for pipe gas-flow and superimposing onto it a 2D analytic solution for concentration and velocity distribution in the plane perpendicular to the gas-flow. The main innovative contribution of this paper comprises a significant mathematical reduction of the previously published HAN approach to a computationally optimized approach featuring a minimal amount of computational points yielding a real-time capable model (denoted HAN-RT), which complies with 1kHz HiL constraints while retaining HAN\u27s quasi 3D nature. Presented results confirm that the computationally optimized HAN-RT model displays real-time capabilities at sampling rates above 1 kHz while producing results that agree very well with spatially resolved results generated by the 3D multiphase CFD tool and with the experimental results of steady state and transient fuel cell operation