Study and comparison of interaction parameters and phase behavior of epoxy/polystyrene and epoxies copolymer polystyrene‐b‐poly(methyl methacrylate) blends

Thermodynamic studies in terms of phase separation behavior and interaction parameters, in mixtures of epoxy resins (thermoset materials) with thermoplastic additives, consisting of polystyrene (PS) or polystyrene‐b‐poly(methyl methacrylate) P(S‐MMA) (with small proportion of MMA), have been carried out. It can be confirmed that the solubility of P(S‐MMA) is an improvement on that of PS, with the prepolymer epoxy resins. Moreover, the interaction parameters are positive at temperatures in which phase separation is observed, but negative at temperatures in which the phase separation window disappears, in the corresponding phase diagram. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers     

Principal component analysis applied to filtered signals for maintenance management

This paper presents an approach for detecting and identifying faults in railway infrastructure components. The method is based on pattern recognition and data analysis algorithms. Principal component analysis (PCA) is employed to reduce the complexity of the data to two and three dimensions. PCA involves a mathematical procedure that transforms a number of variables, which may be correlated, into a smaller set of uncorrelated variables called ‘principal components’. In order to improve the results obtained, the signal was filtered. The filtering was carried out employing a state–space system model, estimated by maximum likelihood with the help of the well‐known recursive algorithms such as Kalman filter and fixed interval smoothing. The models explored in this paper to analyse system data lie within the so‐called unobserved components class of models. Copyright © 2009 John Wiley & Sons, Ltd.     

Embedding security constraints into the stabilizers coordination problem

The aim of this paper is to expose a fashion to introduce transient stability constraints into the problem of stabilizers coordination solved by an optimal criterion. The problem is posed in such a way that different operating conditions and fault locations may be taken into account, leading to robust stabilizers. The proposed procedure is based on minimizing the incremental real part of modes of concern; such increments are evaluated through second order sensitivities. Inequality constraints are embedded into the problem in order to circumscribe the angular excursions by the stabilizers' action. A nine-bus power system is considered as a sample system to exhibit the main results of the proposed methodology.     

Sub-Riemannian Curvature of Carnot Groups with Rank-Two Distributions

The notion of curvature discussed in this paper is a far-going generalization of the Riemannian sectional curvature. It was first introduced by Agrachev et al. ([2015]), and it is defined for a wide class of optimal control problems: a unified framework including geometric structures such as Riemannian, sub-Riemannian, Finsler, and sub-Finsler structures. In this work, we study the generalized sectional curvature of Carnot groups with rank-two distributions. In particular, we consider the Cartan group and Carnot groups with horizontal distribution of Goursat-type. In these Carnot groups, we characterize ample and equiregular geodesics. For Carnot groups with horizontal Goursat distribution, we show that their generalized sectional curvatures depend only on the Engel part of the distribution. This family of Carnot groups contains naturally the three-dimensional Heisenberg group, as well as the Engel group. Moreover, we also show that in the Engel and Cartan groups, there exist initial covectors for which there is an infinite discrete set of times at which the corresponding ample geodesics are not equiregular.     

Biochemical changes in freshwater rainbow trout (Oncorhynchus mykiss) during chilled storage†

The sensory characteristics and biochemical freshness-indicator contents of rainbow trout (Oncorhynchus mykiss) stored for up to 12 days (a) in ice without previous gutting (group A), (b) in ice after gutting (group B) and (c) under refrigeration (4–5 °C) after gutting and vacuum-packing (group C) were compared. Acceptable freshness was maintained for five days in groups A and C, and for six days in group B. The results indicate that the hypoxanthine ratio ie hypoxanthine content: (inosine monophosphate + inosine + hypoxanthine content) and K₁ ie (inosine + hypoxanthine content): (inosine monophosphate + inosine + hypoxanthine content) are both useful indicators of the freshness of trout stored in ice, regardless of whether or not they have been gutted beforehand. © 1999 Society of Chemical Industry     

Childhood B-Cell Preleukemia Mouse Modeling

Leukemia is the most usual childhood cancer, and B-cell acute lymphoblastic leukemia (B-ALL) is its most common presentation. It has been proposed that pediatric leukemogenesis occurs through a “multi-step” or “multi-hit” mechanism that includes both in utero and postnatal steps. Many childhood leukemia-initiating events, such as chromosomal translocations, originate in utero, and studies so far suggest that these “first-hits” occur at a far higher frequency than the incidence of childhood leukemia itself. The reason why only a small percentage of the children born with such preleukemic “hits” will develop full-blown leukemia is still a mystery. In order to better understand childhood leukemia, mouse modeling is essential, but only if the multistage process of leukemia can be recapitulated in the model. Therefore, mouse models naturally reproducing the “multi-step” process of childhood B-ALL will be essential to identify environmental or other factors that are directly linked to increased risk of disease.     

The Primary Microglial Leukodystrophies: A Review

Primary microglial leukodystrophy or leukoencephalopathy are disorders in which a genetic defect linked to microglia causes cerebral white matter damage. Pigmented orthochromatic leukodystrophy, adult-onset orthochromatic leukodystrophy associated with pigmented macrophages, hereditary diffuse leukoencephalopathy with (axonal) spheroids, and adult-onset leukoencephalopathy with axonal spheroids and pigmented glia (ALSP) are different terms apparently used to designate the same disease. However, ALSP linked to dominantly inherited mutations in CSF1R (colony stimulating factor receptor 1) cause CSF-1R-related leukoencephalopathy (CRP). Yet, recessive ALSP with ovarian failure linked to AARS2 (alanyl-transfer (t)RNA synthase 2) mutations (LKENP) is a mitochondrial disease and not a primary microglial leukoencephalopathy. Polycystic membranous lipomembranous osteodysplasia with sclerosing leukoencephalopathy (PLOSL; Nasu–Hakola disease: NHD) is a systemic disease affecting bones, cerebral white matter, selected grey nuclei, and adipose tissue The disease is caused by mutations of one of the two genes TYROBP or TREM2, identified as PLOSL1 and PLOSL2, respectively. TYROBP associates with receptors expressed in NK cells, B and T lymphocytes, dendritic cells, monocytes, macrophages, and microglia. TREM2 encodes the protein TREM2 (triggering receptor expressed on myeloid cells 2), which forms a receptor signalling complex with TYROBP in macrophages and dendritic cells. Rather than pure microglial leukoencephalopathy, NHD can be considered a multisystemic “immunological” disease.     

Differences in Tau Seeding in Newborn and Adult Wild-Type Mice

Alzheimer’s disease (AD) and other tauopathies are common neurodegenerative diseases in older adults; in contrast, abnormal tau deposition in neurons and glial cells occurs only exceptionally in children. Sarkosyl-insoluble fractions from sporadic AD (sAD) containing paired helical filaments (PHFs) were inoculated unilaterally into the thalamus in newborn and three-month-old wild-type C57BL/6 mice, which were killed at different intervals from 24 h to six months after inoculation. Tau-positive cells were scanty and practically disappeared at three months in mice inoculated at the age of a newborn. In contrast, large numbers of tau-positive cells, including neurons and oligodendrocytes, were found in the thalamus of mice inoculated at three months and killed at the ages of six months and nine months. Mice inoculated at the age of newborn and re-inoculated at the age of three months showed similar numbers and distribution of positive cells in the thalamus at six months and nine months. This study shows that (a) differences in tau seeding between newborn and young adults may be related to the ratios between 3Rtau and 4Rtau, and the shift to 4Rtau predominance in adults, together with the immaturity of connections in newborn mice, and (b) intracerebral inoculation of sAD PHFs in newborn mice does not protect from tau seeding following intracerebral inoculation of sAD PHFs in young/adult mice.     

Common and Specific Marks of Different Tau Strains Following Intra-Hippocampal Injection of AD,PiD, and GGT Inoculum in hTau Transgenic Mice

Heterozygous hTau mice were used for the study of tau seeding. These mice express the six human tau isoforms, with a high predominance of 3Rtau over 4Rtau. The following groups were assessed: (i) non-inoculated mice aged 9 months (n = 4); (ii) Alzheimer’s Disease (AD)-inoculated mice (n = 4); (iii) Globular Glial Tauopathy (GGT)-inoculated mice (n = 4); (iv) Pick’s disease (PiD)-inoculated mice (n = 4); (v) control-inoculated mice (n = 4); and (vi) inoculated with vehicle alone (n = 2). AD-inoculated mice showed AT8-immunoreactive neuronal pre-tangles, granular aggregates, and dots in the CA1 region of the hippocampus, dentate gyrus (DG), and hilus, and threads and dots in the ipsilateral corpus callosum. GGT-inoculated mice showed unique or multiple AT8-immunoreactive globular deposits in neurons, occasionally extended to the proximal dendrites. PiD-inoculated mice showed a few loose pre-tangles in the CA1 region, DG, and cerebral cortex near the injection site. Coiled bodies were formed in the corpus callosum in AD-inoculated mice, but GGT-inoculated mice lacked globular glial inclusions. Tau deposits in inoculated mice co-localized active kinases p38-P and SAPK/JNK-P, thus suggesting active phosphorylation of the host tau. Tau deposits were absent in hTau mice inoculated with control homogenates and vehicle alone. Deposits in AD-inoculated hTau mice contained 3Rtau and 4Rtau; those in GGT-inoculated mice were mainly stained with anti-4Rtau antibodies, but a small number of deposits contained 3Rtau. Deposits in PiD-inoculated mice were stained with anti-3Rtau antibodies, but rare neuronal, thread-like, and dot-like deposits showed 4Rtau immunoreactivity. These findings show that tau strains produce different patterns of active neuronal seeding, which also depend on the host tau. Unexpected 3Rtau and 4Rtau deposits after inoculation of homogenates from 4R and 3R tauopathies, respectively, suggests the regulation of exon 10 splicing of the host tau during the process of seeding, thus modulating the plasticity of the cytoskeleton.