Influence of the geometrical shape on the structural behavior of diagrid tall buildings under lateral and torque actions

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New trends towards enhanced structural efficiency and aesthetic potential in tall buildings: The case of diagrids

Due to the increasing number of people and activities within the cities, tall buildings are exploited worldwide to address the need for new living and commercial spaces, while limiting the amount of used land. In recent decades, the design of tall buildings has undergone a remarkable improvement, thanks to the development of new computational tools and technological solutions. This has led to the realization of innovative structural systems, like diagrids, which allow the achievement of high structural performances and remarkable architectural effects. In this paper, a thorough and updated review of diagrid structural systems is provided. Simplified methodologies for the preliminary design and structural analysis are reported. Special attention is also paid to the optimization of the structural response based on the geometrical pattern. A discussion of the effect of local deformability, stability and shear-lag phenomenon is carried out. Results from nonlinear and dynamic analyses for the seismic assessment of diagrid systems are reported, and attention is also paid to the recent research on diagrid nodes. Eventually, an overview of twisted, tapered, tilted and freeform diagrid towers is carried out, with a final mention of hexagrids, another recent evolution of tubular systems for tall buildings

Low-frequency harmonic perturbations drive protein conformational changes

Protein dynamics has been investigated since almost half a century, as it is believed to constitute the fundamental connection between structure and function. Elastic network models (ENMs) have been widely used to predict protein dynamics, flexibility and the biological mechanism, from which remarkable results have been found regarding the prediction of protein conformational changes. Starting from the knowledge of the reference structure only, these conformational changes have been usually predicted either by looking at the individual mode shapes of vibrations (i.e., by considering the free vibrations of the ENM) or by applying static perturbations to the protein network (i.e., by considering a linear response theory). In this paper, we put together the two previous approaches and evaluate the complete protein response under the application of dynamic perturbations. Harmonic forces with random directions are applied to the protein ENM, which are meant to simulate the single frequency-dependent components of the collisions of the surrounding particles, and the protein response is computed by solving the dynamic equations in the underdamped regime, where mass, viscous damping and elastic stiffness contributions are explicitly taken into account. The obtained motion is investigated both in the coordinate space and in the sub-space of principal components (PCs). The results show that the application of perturbations in the low-frequency range is able to drive the protein conformational change, leading to remarkably high values of direction similarity. Eventually, this suggests that protein conformational change might be triggered by external collisions and favored by the inherent low-frequency dynamics of the protein structure

The first record in Italy of Trichogramma cordubense Vargas & Cabello 1985 (Hymenoptera: Trichogrammatidae) emerging from the eggs of Lobesia botrana (Denis & Schiffermüller, 1775) (Lepidoptera: Tortricidae)

This study investigated the egg parasitoids of Lobesia botrana (Denis & Schiffermüller, 1775) feeding on Daphne gnidium L. (Malvales, Thymelaeaceae) in the San Rossore-Migliarino-Massaciuccoli Nature Reserve (Tuscany, Italy). Four species of egg parasitoids of the genus Trichogramma spp. were obtained. The parasitization rate gradually increased over the season, reaching its maximum level in September 2015, with a percentage of parasitized eggs close to 55 %. Three of the species obtained were already known as L. botrana parasitoids, whereas the finding of Trichogramma cordubense Vargas & Cabello, 1985 represents the first recording in Italy, as well as the first report of this species among the natural enemies of L. botrana

Modal analysis of the lysozyme protein considering all-atom and coarse-grained finite element models

Proteins are the fundamental entities of several organic activities. They are essential for a broad range of tasks in a way that their shapes and folding processes are crucial to achieving proper biological functions. Low-frequency modes, generally associated with collective movements at terahertz (THz) and sub-terahertz frequencies, have been appointed as critical for the conformational processes of many proteins. Dynamic simulations, such as molecular dynamics, are vastly applied by biochemical researchers in this field. However, in the last years, proposals that define the protein as a simplified elastic macrostructure have shown appealing results when dealing with this type of problem. In this context, modal analysis based on different modelization techniques, i.e., considering both an all-atom (AA) and coarse-grained (CG) representation, is proposed to analyze the hen egg-white lysozyme. This work presents new considerations and conclusions compared to previous analyses. Experimental values for the B-factor, considering all the heavy atoms or only one representative point per amino acid, are used to evaluate the validity of the numerical solutions. In general terms, this comparison allows the assessment of the regional flexibility of the protein. Besides, the low computational requirements make this approach a quick method to extract the protein’s dynamic properties under scrutiny

Structural compliance: A new metric for protein flexibility

Proteins are the active players in performing essential molecular activities throughout biology, and their dynamics has been broadly demonstrated to relate to their mechanisms. The intrinsic fluctuations have often been used to represent their dynamics and then compared to the experimental B-factors. However, proteins do not move in a vacuum and their motions are modulated by solvent that can impose forces on the structure. In this paper, we introduce a new structural concept, which has been called the structural compliance, for the evaluation of the global and local deformability of the protein structure in response to intramolecular and solvent forces. Based on the application of pairwise pulling forces to a protein elastic network, this structural quantity has been computed and sometimes is even found to yield an improved correlation with the experimental B-factors, meaning that it may serve as a better metric for protein flexibility. The inverse of structural compliance, namely the structural stiffness, has also been defined, which shows a clear anticorrelation with the experimental data. Although the present applications are made to proteins, this approach can also be applied to other biomolecular structures such as RNA. This present study considers only elastic network models, but the approach could be applied further to conventional atomic molecular dynamics. Compliance is found to have a slightly better agreement with the experimental B-factors, perhaps reflecting its bias toward the effects of local perturbations, in contrast to mean square fluctuations. The code for calculating protein compliance and stiffness is freely accessible at https://jerniganlab.github.io/Software/PACKMAN/Tutorials/compliance

Braconinae parasitoids (Hymenoptera, Braconidae) emerged from larvae of Lobesia botrana (Denis & Schiffermüller) (Lepidoptera, Tortricidae) feeding on Daphne gnidium L.

The Bracon Fabricius, 1804 species, B. admotus Papp, 2000, and three species of the genus Habrobracon Ashmead, 1895, H. concolorans (Marshall, 1900), H. hebetor (Say, 1836) and H. pillerianae Fischer, 1980, were obtained from the larvae of Lobesia botrana (Denis & Schiffermüller, 1775) (Lepidoptera, Tortricidae) living on Daphne gnidium Linnaeus, 1753 (Thymelaeaceae) in the natural reserve of Migliarino-San Rossore- Massaciuccoli (Pisa - Central Italy). Bracon admotus, Habrobracon concolorans and H. pillerianae were found for the first time to be associated with L. botrana, while H. hebetor was reared for the first time from the larvae of Cryptoblabes gnidiella (Milliere, 1867) (Lepidoptera, Pyralidae, Phycitinae). Bracon admotus and H. pillerianae are new fauna to Italy and Western Europe. A key is proposed for the determination of Habrobracon species reared from L. botrana and related Palaearctic species of this genus. Bracon (Habrobracon) lineatellae Fisher, 1968 is considered as a valid species

Genotype characterisation of Giardia duodenalis isolates from domestic and farm animals by SSU-rRNA gene sequencing

In order to investigate the genotypes of Giardia duodenalis from domestic and farm animals in Italy, 21 Giardia isolates, 17 from dogs, 1 from cat and 3 from dairy calves, were genetically characterised by SSU-rRNA gene sequencing. Among dogs, 76.5% of isolates showed the dog-specific genotypes (Assemblages C, D and C/D mixed Assemblage) and 23.5% exhibit potential zoonotic genotypes (Assemblage A and A/C mixed Assemblages). The cat isolate belonged to assemblage A, whereas the sequences among the isolates from calves were found to correspond to hoofed-livestock genotype, namely Assemblage E. These findings suggest that infection of humans by zoonotic genotypes from domestic animals could be of low epidemiological significance, although possible. The present study represents the first contribute to the knowledge of G. duodenalis genotypes in domestic and farm animals from Italy. (C) 2004 Elsevier B.V. All rights reserved

A study of the prevalence and genotypes of Giardia duodenalis infecting kennelled dogs

Giardia duodenalis is a protozoan parasite of animals that is zoonotic. Given the capacity of this organism to spread via the faecal–oral route, animals held in overcrowded and unhygienic conditions are at high risk of infection. Faecal samples from dogs in three kennels in Rome were examined by microscopy and PCR for G. duodenalis, and the prevalence data generated were correlated with variables such as kennel identity, age of dog, length of time the dog had been kennelled and clinical signs. The overall prevalence of the parasite in the faecal samples was 20.5% and was higher in samples from the largest kennel, which had the greatest turnover of dogs, and in faecal samples from younger animals. Giardia cysts were found more frequently in diarrhoeic animals but were also found in dogs with no clinical signs. Although the finding that the majority of isolates were dog-specific rather than zoonotic genotypes suggests that the zoonotic risk from this pathogen is less than previously thought, the higher prevalence of infection in younger dogs may pose a specific public health issue as such animals are more frequently re-homed with families. 2008 Elsevier Ltd. All rights reserved