1,252 research outputs found
Revealing the architecture and composition of the sperm flagellum tip
No full textThe eukaryotic flagellum is a membrane-bound protruding organelle with a cytoskeleton of microtubules. Flagella are found in unicellular as well as multicellular organisms, performing a variety of functions. Motile flagella enable cell locomotion, like in protists or spermatozoa, but can also create flows of fluids or mucus, like in respiratory airways. Flagella also act as cellular “antennas”, as their surface can probe the environment with sensorial receptors. The flagellar ultrastructure is often regarded as widely conserved among eukaryotes, however significant differences have been reported for the structure of the distal flagellar tip between organisms. The tip is where the flagellum grows and where intra-flagellar transport must unload and load cargo, making it a hub of flagellar-specific processes that are still relatively under-explored.
In humans, genetic mutations that impair proper flagellar function cause primary ciliary dyskinesia, a collective term for numerous pathologies which are still not fully characterized. To elucidate the ultrastructure of the human flagellar tip, we performed cryo-electron tomography on intact spermatozoa, plunge-frozen in their native environment. The results revealed drastic differences compared to commonly studied model organisms. Additionally, a novel extensive structure (named TAILS) was discovered decorating the lumen of sperm tip microtubules. These results together highlight the power of cryo-electron tomography in displaying complex cellular structures in their native environment, as well as the importance of studying the human system directly.
Lastly, a multi-pronged approach was designed to biochemically identify and characterize TAILS, based on a reverse structural biology perspective. This included obtaining high-resolution structures of TAILS produced with different cryo-electron microscopy techniques, the first ever flagellar tip proteome and an evolutionary overview of TAILS conservation
Correction to: When terminology hinders research: the colloquialisms of transitions of control in automated driving (Cognition, Technology & Work, (2022), 10.1007/s10111-022-00705-3)
No full textIn the original article, author affiliation published with error. The correct affiliations are: Davide Maggi—Institute for Transport Studies, Leeds, UK. Richard Romano—Institute for Transport Studies, Leeds, UK. Oliver Carsten—Institute for Transport Studies, Leeds, UK. Joost C. F. De Winter—Faculty of Mechanical, Maritime and Materials Engineering, Delft University of Technology, Delft, The Netherlands. The original article has been corrected.Human-Robot Interactio
Admiel Kosman, Siamo giunti a Dio
No full textInternational audienceSix poems from Israeli poet Admiel Kosman translated from the Hebrew into Italian. Selection of poems, presentation of the author, translation and notes by Davide Mano
Admiel Kosman, Siamo giunti a Dio
No full textInternational audienceSix poems from Israeli poet Admiel Kosman translated from the Hebrew into Italian. Selection of poems, presentation of the author, translation and notes by Davide Mano
Starchitecture: Scenes, Actors and Spectacles in Contemporary Cities
No full textHow and why do spectacular buildings get commissioned and procured? What are their visible urban effects? What can urban planners, architects, and policymakers learn in order to engage in more successful citymaking?
In recent years, media and critical attention has been lavished on famous architects, and the contributions of their designs to the branding of cities. The post-“Bilbao effect” global landscape is one where cities compete for the highest-profile skyscrapers, cultural projects, and high-profile developments designed by star architects whom even casual readers know by first name: Frank Gehry, Bjarke Ingels, Jean Nouvel, Zaha Hadid, Norman Foster, Rem Koolhaas. Far less is known about the decision-making processes behind these projects and their subsequent urban effects.
A unique combination of urban studies and photography, Starchitecture investigates projects designed by star architects in cities including Paris, New York, Abu Dhabi, Bilbao, and the architectural microcosm of the Vitra campus in Weil am Rhein, Germany. Author Davide Ponzini and photographer Michele Nastasi seek to explain and critique a growing global condition by revealing how starchitecture has been and continues to be deployed in cities around the world. The arguments they raise are vital to understanding the urban landscapes of today, and tomorrow
Revealing the architecture and composition of the sperm flagellum tip
No full textThe eukaryotic flagellum is a membrane-bound protruding organelle with a cytoskeleton of microtubules. Flagella are found in unicellular as well as multicellular organisms, performing a variety of functions. Motile flagella enable cell locomotion, like in protists or spermatozoa, but can also create flows of fluids or mucus, like in respiratory airways. Flagella also act as cellular “antennas”, as their surface can probe the environment with sensorial receptors. The flagellar ultrastructure is often regarded as widely conserved among eukaryotes, however significant differences have been reported for the structure of the distal flagellar tip between organisms. The tip is where the flagellum grows and where intra-flagellar transport must unload and load cargo, making it a hub of flagellar-specific processes that are still relatively under-explored. In humans, genetic mutations that impair proper flagellar function cause primary ciliary dyskinesia, a collective term for numerous pathologies which are still not fully characterized. To elucidate the ultrastructure of the human flagellar tip, we performed cryo-electron tomography on intact spermatozoa, plunge-frozen in their native environment. The results revealed drastic differences compared to commonly studied model organisms. Additionally, a novel extensive structure (named TAILS) was discovered decorating the lumen of sperm tip microtubules. These results together highlight the power of cryo-electron tomography in displaying complex cellular structures in their native environment, as well as the importance of studying the human system directly. Lastly, a multi-pronged approach was designed to biochemically identify and characterize TAILS, based on a reverse structural biology perspective. This included obtaining high-resolution structures of TAILS produced with different cryo-electron microscopy techniques, the first ever flagellar tip proteome and an evolutionary overview of TAILS conservation
Design and characterization of a fractal-inspired multi-frequency piezoelectric energy converter
No full textA promising harvesting technique, in terms of simplicity and efficiency, is the conversion of ambient kinetic energy through piezoelectric materials. This work aims to design and investigate a piezoelectric converter conform to a fractal-inspired, multi-frequency structure previously presented by the author. A physical prototype of the converter is built and experimentally examined, up to 120 Hz, in terms of modal response and power output. Three eigenfrequencies are registered and the power output is particularly good at the fundamental eigenfrequency. Also the effect of the resistive load applied to the converter is investigated
Checking Flavour Models at Neutrino Facilities
No full textAbstractIn the recent years, the industry of model building has been the subject of the intense activity, especially after the measurement of a relatively large values of the reactor angle. Special attention has been devoted to the use of non-abelian discrete symmetries, thanks to their ability of reproducing some of the relevant features of the neutrino mixing matrix. In this Letter, we consider two special relations between the leptonic mixing angles, arising from models based on S4 and A4, and study whether, and to which extent, they can be distinguished at superbeam facilities, namely T2K, NOνA and T2HK
La rilevanza del rischio economico nella definizione dell’ambito soggettivo di applicazione della disciplina sui contratti pubblici e del diritto della concorrenza
No full textL’articolo si propone di analizzare il ruolo del rischio economico come criterio
idoneo a delineare l’ambito soggettivo di applicazione del diritto europeo dei
contratti pubblici e del regime della concorrenza. L’analisi si incentra sull’in-
terpretazione delle nozioni di “organismo di diritto pubblico” e di “impresa”. Il
contributo intende evidenziare la crescente importanza dell’analisi economica
come criterio ermeneutico utile a segnare il confine tra “pubblico” e “privato”,
tra “attività amministrativa” e “attività d’impresa”.The essay examines the role of economic risk in identifying the scope of public
procurement and competition law. The widespread use of private law institutions
by the public sector creates uncertainty about whether to apply public procurement
or competition law or both. According to the author, the concept of economic risk
could represent a decisive criterion for marking the boundaries between the two
areas of law. Consistently, the author highlights the importance of a “more
economic approach” in the application of European internal market law
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