A Hierarchy of Approximations of the Master Equation Scaled by a Size Parameter

Solutions of the master equation are approximated using a hierarchy of models based on the solution of ordinary differential equations: the macroscopic equations, the linear noise approximation and the moment equations. The advantage with the approximations is that the computational work with deterministic algorithms grows as a polynomial in the number of species instead of an exponential growth with conventional methods for the master equation. The relation between the approximations is investigated theoretically and in numerical examples. The solutions converge to the macroscopic equations when a parameter measuring the size of the system grows. A computational criterion is suggested for estimating the accuracy of the approximations. The numerical examples are models for the migration of people, in population dynamics and in molecular biology. Financial support has been obtained from the Swedish Foundation for Strategic Research and the Swedish Graduate School in Mathematics and Computing.     

The nutritional supplement Active Hexose Correlated Compound (AHCC) has direct immunomodulatory actions on intestinal epithelial cells and macrophages involving TLR/MyD88 and NF-κB/MAPK activation

Active Hexose Correlated Compound (AHCC) is an immunostimulatory nutritional supplement. AHCC effects and mechanism of action on intestinal epithelial cells or monocytes are poorly described. AHCC was added to the culture medium of intestinal epithelial cells (IEC18 and HT29 cells) and monocytes (THP-1 cells) and assessed the secretion of proinflammatory cytokines by ELISA. Inhibitors of NFκB and MAPKs were used to study signal transduction pathways while TLR4 and MyD88 were silenced in IEC18 cells using shRNA. It was found that AHCC induced GROα and MCP1 secretion in IEC18 and IL-8 in HT29 cells. These effects depended on NFκB activation, and partly on MAPKs activation and on the presence of MyD88 and TLR4. In THP-1 cells AHCC evoked IL-8, IL-1β and TNF-α secretion. The induction of IL-8 depended on JNK and NFκB activation. Therefore, AHCC exerts immunostimulatory effects on intestinal epithelial cells and monocytes involving TLR4/MyD88 and NFκB/MAPK signal transduction pathways.     

Improved extraction of carrageenan from red seaweed (Chondracantus canaliculatus) using ultrasound-assisted methods and evaluation of the yield,physicochemical properties and functional groups

Food Science and Biotechnology - Red seaweed Chondracanthus canaliculatus, an underexploited algae species, was used as a potential source for the obtaining of carrageenan. Seaweed was treated...     

Layer-by-Layer assembly and redox properties of undoped HPHT diamond particles

The surface properties of undoped diamond particles are investigated by a combination of zeta potential measurements in solution and electrochemical studies in thin layer assemblies. High-Pressure High-Temperature (HPHT) 500 nm diamond particles exhibit positive and negative zeta potentials depending on pH. The estimated point of zero zeta potential (pzzp) was 6.6, while mobility measurements provided an average charge per particle of ?(843 ± 31)e at high pH. The charge indicates that approximately 50 ppm of surface atoms involves ionisable impurities. The positive charge measured at low pH is of similar magnitude and could be related to nitrogen impurities. The surface charge in basic solutions allows the electrostatic adsorption of diamond particles on poly(diallyldimethylammonium chloride) (PDADMAC) modified In-doped SnO₂ electrodes (ITO). The particle number density shows a strong dependence on pH, with a maximum value of (1.7 ± 0.3) × 10⁸ cm^?2. Electrochemical studies carried out in the absence of redox species in solution revealed signals associated with sp² type surface states. Analysis of electrochemical responses concluded that 1 × 10⁴ redox centres per particle are involved in a single electron transfer process. We demonstrate that this simple yet versatile approach is rather sensitive to the extent of sp² hybridisation at the surface of diamond powders.     

A comparative study of classifier combination applied to NLP tasks

The paper is devoted to a comparative study of classifier combination methods, which have been successfully applied to multiple tasks including Natural Language Processing (NLP) tasks. There is variety of classifier combination techniques and the major difficulty is to choose one that is the best fit for a particular task. In our study we explored the performance of a number of combination methods such as voting, Bayesian merging, behavior knowledge space, bagging, stacking, feature sub-spacing and cascading, for the part-of-speech tagging task using nine corpora in five languages. The results show that some methods that, currently, are not very popular could demonstrate much better performance. In addition, we learned how the corpus size and quality influence the combination methods performance. We also provide the results of applying the classifier combination methods to the other NLP tasks, such as name entity recognition and chunking. We believe that our study is the most exhaustive comparison made with combination methods applied to NLP tasks so far.     

Losses of precision associated with simplified designs of milk recording for dairy ewes

Simplified designs of milk yield recording based on the yield of a single monthly milking, adjusted or not for interval between milkings and for production level, were simulated and evaluated for 3173 ewe-test-day records belonging to 155 lactations of Churra dairy ewes. Losses of precision associated with simplified methods were evaluated by comparing estimated lactation yields with those observed both in a reference plan, where the two daily milkings were recorded at weekly intervals, and in the official A4 milk recording (monthly records of the two daily milkings). Estimates of lactation yields were less precise when the usual monthly designs were compared with a weekly sampling of both a.m. and p.m. milkings. The losses of precision were high at 9.4-36.2% including the A4 plan. The yield from only the milking period was more predictable than milk yield from the whole lactation (suckling and milking periods) and should consequently be adopted in dairy ewes. All options with one daily milking every month were more accurate when the corresponding plan was based on, or began with, the a.m. milking (loss of precision 14.9-15.8%). There was no evidence of improvement in sampling accuracy by adjusting for the preceding interval between milkings or production level. For practical and economic reasons, the design alternating a.m. and p.m. milkings every month, without adjustment, is suggested for ovine milk recording.     

Ronchi test with equivalent wavelength

In this work we present an experimental proposal to evaluate optical surfaces with high slopes or with infrared wavelengths based on the Ronchi test as well as on the concept of equivalent wavelength. A spatial modulator is used in the implementation of the Ronchi test, and a white LED with different color filters is employed in order to generate different wavelengths. Two Ronchigrams with incoherent light, each one for a different color, are registered and computationally processed, thus generating a third one with an equivalent wavelength. The results obtained show that it is possible to generate patterns with traditional rulings and substructured sequences of Katyl. Additionally, we discuss some of the limitations of employing different rulings. Finally, we found that appropriate image enhancing algorithms allow us to improve the visibility of the resulting fringes and thus obtain a better analysis.     

The effect of zinc borate in combination with ammonium octamolybdate or zinc stannate on smoke suppression in flexible PVC

The effect of combinations of zinc borate with ammonium octamolybdate or zinc stannate on smoke suppression upon combustion of flexible PVC was studied. Effects on Oxygen Index and on residual char after ten minutes at 560°C were also evaluated. These studies were done using both a conventional dioctyl phthalate (DOP) plasticizer and a mixed plasticizer consisting of a 1:1 combination of DOP and an alkyl aryl phosphate ester. For both plsticizer systems, results showed that combinations of the zinc borate with either ammonium octamolybdate or zinc stannate gave an improved effect with respect to smoke reduction upon combustion. Thermogravimetric analysis (TGA) of PVC containing these additives showed no indication of interactions to explain this effect. TGA analyses indicated that PVC samples made with the mixed plasticizer had final decompositon temperatures which were slightly higher than those made with DOP as the plasticizer.     

On the Geometry of Visual Correspondence

Image displacement fields—optical flow fields, stereo disparity fields, normal flow fields—due to rigid motion possess a global geometric structure which is independent of the scene in view. Motion vectors of certain lengths and directions are constrained to lie on the imaging surface at particular loci whose location and form depends solely on the 3D motion parameters. If optical flow fields or stereo disparity fields are considered, then equal vectors are shown to lie on conic sections. Similarly, for normal motion fields, equal vectors lie within regions whose boundaries also constitute conics. By studying various properties of these curves and regions and their relationships, a characterization of the structure of rigid motion fields is given. The goal of this paper is to introduce a concept underlying the global structure of image displacement fields. This concept gives rise to various constraints that could form the basis of algorithms for the recovery of visual information from multiple views.