Characterization of proton irradiated 3D-DDTC pixel sensor prototypes fabricated at FBK

In this paper we discuss results relevant to 3D Double-Side Double Type Column (3D-DDTC) pixel sensors fabricated at FBK (Trento, Italy) and oriented to the ATLAS upgrade. Some assemblies of these sensors featuring different columnar electrode configurations (2, 3, or 4 columns per pixel) and coupled to the ATLAS FEI3 read-out chip were irradiated up to large proton fluences and tested in laboratory with radioactive sources. In spite of the non optimized columnar electrode overlap, sensors exhibit reasonably good charge collection properties up to an irradiation fluence of 2 x 10**15 neq/cm2, while requiring bias voltages in the order of 100 V. Sensor operation is further investigated by means of TCAD simulations which can effectively explain the basic mechanisms responsible for charge loss after irradiation.Comment: Preprint submitted to Nuclear Instruments and Methods A, 11 pages, 13 fig

A conserved zinc-binding site in Acinetobacter baumannii PBP2 required for elongasome-directed bacterial cell shape

Acinetobacter baumannii is a gram-negative bacterial pathogen that causes challenging nosocomial infections. β-lactam targeting of penicillin-binding protein (PBP)–mediated cell wall peptidoglycan (PG) formation is a well-established antimicrobial strategy. Exposure to carbapenems or zinc (Zn)-deprived growth conditions leads to a rod-to-sphere morphological transition in A. baumannii, an effect resembling that caused by deficiency in the RodA–PBP2 PG synthesis complex required for cell wall elongation. While it is recognized that carbapenems preferentially acylate PBP2 in A. baumannii and therefore block the transpeptidase function of the RodA–PBP2 system, the molecular details underpinning cell wall elongation inhibition upon Zn starvation remain undefined. Here, we report the X-ray crystal structure of A. baumannii PBP2, revealing an unexpected Zn coordination site in the transpeptidase domain required for protein stability. Mutations in the Zn-binding site of PBP2 cause a loss of bacterial rod shape and increase susceptibility to β-lactams, therefore providing a direct rationale for cell wall shape maintenance and Zn homeostasis in A. baumannii. Furthermore, the Zn-coordinating residues are conserved in various β- and γ-proteobacterial PBP2 orthologs, consistent with a widespread Zn-binding requirement for function that has been previously unknown. Due to the emergence of resistance to virtually all marketed antibiotic classes, alternative or complementary antimicrobial strategies need to be explored. These findings offer a perspective for dual inhibition of Zn-dependent PG synthases and metallo-β-lactamases by metal chelating agents, considered the most sought-after adjuvants to restore β-lactam potency against gram-negative bacteria

Prototype ATLAS IBL Modules using the FE-I4A Front-End Readout Chip

The ATLAS Collaboration will upgrade its semiconductor pixel tracking detector with a new Insertable B-layer (IBL) between the existing pixel detector and the vacuum pipe of the Large Hadron Collider. The extreme operating conditions at this location have necessitated the development of new radiation hard pixel sensor technologies and a new front-end readout chip, called the FE-I4. Planar pixel sensors and 3D pixel sensors have been investigated to equip this new pixel layer, and prototype modules using the FE-I4A have been fabricated and characterized using 120 GeV pions at the CERN SPS and 4 GeV positrons at DESY, before and after module irradiation. Beam test results are presented, including charge collection efficiency, tracking efficiency and charge sharing.Comment: 45 pages, 30 figures, submitted to JINS

3D active edge silicon sensors: Device processing, yield and QA for the ATLAS-IBL production

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Paradoxos da “identidade nacional” nos discursos arquitetônicos de Lucio Costa e Sylvio de Vasconcellos

n the debate about the period and the architectural style that represented the national identity in the historiography of Brazilian architecture, in the first decades of the twentieth century, different agents took place in the consolidation of the architectural heritage idea. Important characters in cultural preservation policies, such as Rodrigo Melo Franco de Andrade and Mário de Andrade, integrated the public space emphasizing their positions of organic intellectuals in cultural policies. Given this fact, this article focuses on the consolidation in the social imaginary of eighteenth-century architecture as an effective representation of national architecture, consolidating itself as a style/period with the largest number of buildings listed until 1970. Understanding the different subjects involved in this process, this article focuses on the effective political action of Lucio Costa and Sylvio Vasconcellos on the defense of colonial heritage, based on texts and interventions in the overturned cities throughout Brazil, shaping and consolidating their strategies around an ideology of heritage and nation. In addition, we seek to understand the direct relationship established by both agents between the “elected” national heritage architecture and the precepts of the new architectural practice linked to the Modern Movement, to which they were adherents. Justifying the new from the primitive, in a perfect relationship where everything can be explained and fitted, the eclectic architecture was treated as a copy of styles, exacerbation of ornaments and link to foreignism, in opposition at the claimed nation project. We should always review concepts and guidelines, dealing more truthfully and fairly with our eclectic heritage, and consequently with our architectural historiography.No debate em torno do período e do estilo arquitetônico que representassem a identidade nacional na historiografia da arquitetura brasileira, nas primeiras décadas do século XX, diferentes agentes tomaram lugar na consolidação do ideário patrimonial arquitetônico. Figuras marcantes às políticas de preservação cultural, tais como Rodrigo Melo Franco de Andrade e Mário de Andrade, integraram o espaço público ressaltando suas posições de intelectuais inerentes às políticas culturais. Tendo em vista tal fato, este artigo se debruça sobre a consolidação no imaginário social da arquitetura setecentista enquanto efetiva representação da arquitetura nacional, concretizando-se enquanto estilo/período com o maior número de edificações tombadas até 1970. Compreendendo os diferentes sujeitos envolvidos nesse processo, centra-se, assim, na efetiva ação política de Lucio Costa e Sylvio Vasconcellos na defesa em torno do patrimônio colonial, a partir de textos e intervenções nas cidades tombadas Brasil afora, conformandoe consolidando suas estratégias em torno de um ideário de patrimônio e nação. Além disso, busca-se compreender a relação direta estabelecida por ambos os agentes entre a arquitetura “eleita” patrimônio nacional e os preceitos do novo fazer arquitetônico vinculado ao Movimento Moderno, ao qual eram adeptos. Justificando o novo a partir do primitivo, numa relação perfeita em que tudo se explica e se encaixa, a arquitetura eclética foi tratada como cópia de estilos, exacerbação de ornamentos e vinculação ao estrangeirismo, se opondo assim ao projeto de nação pleiteado. Devemos sempre rever conceitos e diretrizes, tratando de forma mais verdadeira e justa o nosso patrimônio eclético, e em consequência, nossa historiografia arquitetônica