Probing Protein Folding with Sequence-Reversed α-Helical Bundles

Recurrent protein folding motifs include various types of helical bundles formed by α-helices that supercoil around each other. While specific patterns of amino acid residues (heptad repeats) characterize the highly versatile folding motif of four-α-helical bundles, the significance of the polypeptide chain directionality is not sufficiently understood, although it determines sequence patterns, helical dipoles, and other parameters for the folding and oligomerization processes of bundles. To investigate directionality aspects in sequence-structure relationships, we reversed the amino acid sequences of two well-characterized, highly regular four-α-helical bundle proteins and studied the folding, oligomerization, and structural properties of the retro-proteins, using Circular Dichroism Spectroscopy (CD), Size Exclusion Chromatography combined with Multi-Angle Laser Light Scattering (SEC-MALS), and Small Angle X-ray Scattering (SAXS). The comparison of the parent proteins with their retro-counterparts reveals that while the α-helical character of the parents is affected to varying degrees by sequence reversal, the folding states, oligomerization propensities, structural stabilities, and shapes of the new molecules strongly depend on the characteristics of the heptad repeat patterns. The highest similarities between parent and retro-proteins are associated with the presence of uninterrupted heptad patterns in helical bundles sequences.     

Patient-specific bronchoscopy visualization through BRDF estimation and disocclusion correction

This paper presents an image-based method for virtual bronchoscope with photo-realistic rendering. The technique is based on recovering bidirectional reflectance distribution function (BRDF) parameters in an environment where the choice of viewing positions, directions, and illumination conditions are restricted. Video images of bronchoscopy examinations are combined with patient-specific three-dimensional (3-D) computed tomography data through two-dimensional (2-D)/3-D registration and shading model parameters are then recovered by exploiting the restricted lighting configurations imposed by the bronchoscope. With the proposed technique, the recovered BRDF is used to predict the expected shading intensity, allowing a texture map independent of lighting conditions to be extracted from each video frame. To correct for disocclusion artefacts, statistical texture synthesis was used to recreate the missing areas. New views not present in the original bronchoscopy video are rendered by evaluating the BRDF with different viewing and illumination parameters. This allows free navigation of the acquired 3-D model with enhanced photo-realism. To assess the practical value of the proposed technique, a detailed visual scoring that involves both real and rendered bronchoscope images is conducted.     

A protection strategy for inverter-interfaced islanded microgrids with looped configuration

Electrical Engineering - Development of an efficient protection strategy is one of the main barriers in paving the way for the implementation of inverter-based microgrids. The limited fault current...     

Finding Diachronic Like‐Minded Users

User communities in social networks are usually identified by considering explicit structural social connections between users. While such communities can reveal important information about their members such as family or friendship ties and geographical proximity, just to name a few, they do not necessarily succeed at pulling like‐minded users that share the same interests together. Therefore, researchers have explored the topical similarity of social content to build like‐minded communities of users. In this article, following the topic‐based approaches, we are interested in identifying communities of users that share similar topical interests with similar temporal behavior. More specifically, we tackle the problem of identifying temporal (diachronic) topic‐based communities, i.e., communities of users who have a similar temporal inclination toward emerging topics. To do so, we utilize multivariate time series analysis to model the contributions of each user toward emerging topics. Further, our modeling is completely agnostic to the underlying topic detection method. We extract topics of interest by employing seminal topic detection methods; one graph‐based and two latent Dirichlet allocation‐based methods. Through our experiments on Twitter data, we demonstrate the effectiveness of our proposed temporal topic‐based community detection method in the context of news recommendation, user prediction, and document timestamp prediction applications, compared with the nontemporal as well as the state‐of‐the‐art temporal approaches.     

Carotenoid pattern in Blakeslea trispora grown on oil‐enriched substrates with regard to triacylglycerol species accumulation

The carotenoid pattern in Blakeslea trispora grown on oil‐enriched substrates was investigated with regard to triacylglycerol (TAG) species accumulation, to assess the interrelationship between these two processes. Analysis of individual carotenoids and TAG was carried out by HPLC. β‐Carotene production was at the expense of lycopene and γ‐carotene formation in cells grown on crude olive pomace oil (COPO) and crude soybean oil (CSO) at two levels of addition (10.0 and 30.0 g/L culture medium). A shift to γ‐carotene synthesis was observed at increased oil level. Cellular lipids produced at the low COPO or CSO levels contained more unsaturated TAG compared with those obtained on glucose as the sole carbon source. With regard to the typical soybean or olive oil TAG profile, cellular TAG had profiles dependent on the type and the amount of the co‐substrates used. In the presence of CSO, the cellular TAG profile was similar to that of the respective oil for both levels of addition. A notable desaturase activity was observed only in the presence of low COPO addition. The present study can serve as a basis for a better understanding of TAG accumulation with regard to β‐carotene production in oil‐enriched substrates.     

Classification of virgin olive oils of the two major cretan cultivars based on their fatty acid composition

Fatty acid composition was determined for 105 virgin olive oil samples of the two dominant Cretan olive cultivars, Koroneiki and Mastoides, harvested from different producing areas at different maturity stages. The oils of the Koroneiki cultivar were characterized by lower concentrations of oleic and decaheptanoic and higher concentrations of linoleic and palmitic acids. Oils obtained from high-altitude locations were rich in monounsaturated fatty acids, while oils obtained from low-altitude locations had higher content of saturated fatty acids. Palmitic and palmitoleic acids increased with increasing altitude in both cultivars examined. The statistical analysis of the compositional data showed significant potential for the classification of the samples according to cultivar and location of origin.     

Computational Approaches for Studying the Granular Dynamics of Continuous Blending Processes, 2 – Population Balance and Data‐Based Methods

The application of computationally inexpensive modeling methods for a predictive study of powder mixing is discussed. A multidimensional population balance model is formulated to track the evolution of the distribution of a mixture of particle populations with respect to position and time. Integrating knowledge derived from a discrete element model, this method can be used to predict residence time distribution, mean and relative standard deviation of the API concentration in a continuous mixer. Low‐order statistical models, including response surface methods, kriging, and high‐dimensional model representations are also presented. Their efficiency for design optimization and process design space identification with respect to operating and design variables is illustrated.

     

Automated gaze-contingent objects elicit orientation following in 8-month-old infants.

The current study tested whether the purely amodal cue of contingency elicits orientation following behavior in 8-month-old infants. We presented 8-month-old infants with automated objects without human features that did or did not react contingently to the infants' fixations recorded by an eye tracker. We found that an object's occasional orientation toward peripheral targets was reciprocated by a congruent visual orientation following response by infants only when it had displayed gaze-contingent interactivity. Our finding demonstrates that infants' gaze-following behavior does not depend on the presence of a human being. The results are consistent with the idea that, in 8-month-old infants, the detection of contingent reactivity, like other communicative signals, can itself elicit the illusion of being addressed. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

A study on corrosion‐fatigue behavior of AA7075‐T651 subjected to different surface modification treatments

Two corrosive media were used (3.5 wt% NaCl aqueous solution and distilled water) to examine the corrosion‐fatigue behavior of AA 7075‐T651, subjected to various surface modifications (wire‐EDM, blasting, and anodizing). An in‐situ corrosion‐fatigue device was used to test the corrosion‐fatigue durability. The apparatus is able to generate cyclic loads within a corrosive solution. The mechanical loading is simulated with the aid of finite element method (FEM). At both corrosive environments, a prolongation of the corrosion‐fatigue life was achieved by the blasting procedure, compared with the as‐machined specimens under same conditions. Anodizing had a deleterious impact in all examined cases.