Super-resolution image reconstruction techniques: Trade-offs between the data-fidelity and regularization terms

Stochastic regularized methods are quite advantageous in super-resolution (SR) image reconstruction problems. In the particular techniques, the SR problem is formulated by means of two terms, the data-fidelity term and the regularization term. The present work examines the effect of each one of these terms on the SR reconstruction result with respect to the presence or absence of noise in the low-resolution (LR) frames. Experimentation is carried out with the widely employed L₂, L₁, Huber and Lorentzian estimators for the data-fidelity term. The Tikhonov and Bilateral (B) Total Variation (TV) techniques are employed for the regularization term. The extracted conclusions can, in practice, help to select an effective SR method for a given sequence of LR frames. Thus, in case that the potential methods present common data-fidelity or regularization term, and frames are noiseless, the method which employs the most robust regularization or data-fidelity term should be used. Otherwise, experimental conclusions regarding performance ranking vary with the presence of noise in frames, the noise model as well as the difference in robustness of efficiency between the rival terms. Estimators employed for the data-fidelity term or regularizations stand for the rival terms.     

Aluminosilicate phosphate cements – a critical review

Phosphate cements are formed by the reaction at an environmental temperature between a phosphate solution and a solid precursor. The precursors can be divided into two categories: One contains mono- or divalent cations that are dissolved and form cation-phosphate precipitates acting as a binder. The other category is based on aluminosilicates, and in these cements, covalent Al–O–P and Si–O–P bonds are formed. There is however not yet agreement on the structure and properties of these cements in the limited literature on this last category. Compressive strengths between 40 and 146?MPa were reported, but these high values were only obtained by one group. The mentioned mechanical strengths in literature render the materials promising candidates for construction purposes. More important is that phosphate cements have a neutral pH after hardening. This allows the use of low-cost glass fibers as reinforcement. The production of Textile Reinforced Cements is thus one of the important future applications. Moreover, there is some disagreement on the molecular structure formed. Some state that Al is present in VI-fold coordination. Others state that berlinite-like structures are formed. Thus, Al is in IV-fold coordination. Crystalline berlinite is however only proven to be present after thermal treatment to at least 250°C. The formation of stable crystalline phases at high temperature makes the material also suited for use as a refractory. A drawback is the scarcity of phosphate minerals to produce phosphoric acid. For this reason, the use of phosphate cement should be limited to niche applications. As phosphates can be fast setting cements, one of these applications might be in additive manufacturing.     

Lipid quality and filleting yield of reared meagre (Argyrosomus regius)

Reared meagre (Argyrosomus regius) of average weight 1278 g was evaluated for its filleting yield and fillet lipid quality. Filleting yield averaged 42.2%, while very low levels of muscle fat deposits were measured (1.06%). Analysis of lipid classes revealed a high proportion of polar lipids (48.3–59.1%) and low levels of neutral fatty acids (40.9–51.7%) when compared to corresponding values of other farmed fish species. Phosphatidyl‐choline (PC) was the dominant polar lipid (2.92 mg g^?1 muscle), while cholesterol the most abundant neutral lipid (1.68 mg g^?1 muscle). The fatty acid composition of meagre fillet generally reflects the dietary fatty acids. Among n‐3 fatty acids, eicosapentaenoic (4.58%) and docohexaenoic (15.0%) were measured to be the most abundant ones, and 18:2n‐6 (11.9%) was the most common n‐6 fatty acid. The fatty acid profiles of polar and neutral fractions differ, with monounsaturated fatty acids being predominant in the neutral and n‐3 polyunsaturates in the polar lipids. The high polar lipid contents and n‐3 fatty acids and the low atherogenic and thrombogenic indexes indicate a high quality of this species’ lipids.     

SPECTACULAR IMAGES OF THE “REFUGEE CRISIS”

The current “refugee crisis” in Europe has generated an abundance of photographs, which have been circulated in print and digital media since 2015. This article focuses on two of the most reproduced of these photographs: that taken in September 2015 of Aylan Kurdi’s dead body near the Turkish coast and a photograph of refugees walking along the Croatian?Slovenian border which was used by the UK Independence Party (UKIP) during the summer of 2016 as part of their pro-Brexit campaign. The article examines the repeated visual tropes which perpetuate stereotypes of refugees as either miserable, helpless victims or threatening subjects. It further questions the ways in which the “individual” and the “collective” have been framed in these photographs, in ways which contribute to dominant and uncontested visual narratives of the “refugee crisis”. The paper contends that the passive acceptance of these reified representations of the refugee experience in these media-saturated times equates to uncritical approval of the sociopolitical conditions from which these photographs are generated. Finally, it argues that only through the rejection of such spectacular images can we hope to open up a serious, critical, public debate about the “refugee crisis”, the necessity of which is becoming increasingly urgent.