Technion – Israel Institute of Technology

About: Technion – Israel Institute of Technology is a education organization based out in Haifa, Israel. It is known for research contribution in the topics: Population & Upper and lower bounds. The organization has 31714 authors who have published 79377 publications receiving 2603976 citations. The organization is also known as: Technion Israel Institute of Technology & Ṭekhniyon, Makhon ṭekhnologi le-Yiśraʼel.

Spatiotemporal microbial evolution on antibiotic landscapes

Abstract: A key aspect of bacterial survival is the ability to evolve while migrating across spatially varying environmental challenges. Laboratory experiments, however, often study evolution in well-mixed systems. Here, we introduce an experimental device, the microbial evolution and growth arena (MEGA)–plate, in which bacteria spread and evolved on a large antibiotic landscape (120 × 60 centimeters) that allowed visual observation of mutation and selection in a migrating bacterial front. While resistance increased consistently, multiple coexisting lineages diversified both phenotypically and genotypically. Analyzing mutants at and behind the propagating front, we found that evolution is not always led by the most resistant mutants; highly resistant mutants may be trapped behind more sensitive lineages. The MEGA-plate provides a versatile platform for studying microbial adaption and directly visualizing evolutionary dynamics.

Prochlorococcus: the structure and function of collective diversity.

Abstract: The marine cyanobacteriumProchlorococcusis the most abundant photosynthetic organism on earth. In this Review, Chisholm and colleagues highlight the enormous genomic diversity of this phototroph, discuss the factors that contribute to this diversity and consider its ecological consequences. The marine cyanobacterium Prochlorococcus is the smallest and most abundant photosynthetic organism on Earth. In this Review, we summarize our understanding of the diversity of this remarkable phototroph and describe its role in ocean ecosystems. We discuss the importance of interactions of Prochlorococcus with the physical environment, with phages and with heterotrophs in shaping the ecology and evolution of this group. In light of recent studies, we have come to view Prochlorococcus as a 'federation' of diverse cells that sustains its broad distribution, stability and abundance in the oceans via extensive genomic and phenotypic diversity. Thus, it is proving to be a useful model system for elucidating the forces that shape microbial populations and ecosystems.

Statistics of spectra of disordered systems near the metal-insulator transition

Abstract: We study the nearest-level-spacing distribution function P(s) in a disordered system near the metal-insulator transition. We claim that in the limit of an infinite system there are only three possible functions P(s): Wigner surmise ${\mathit{P}}_{\mathit{W}}$(s) in a metal, Poisson law ${\mathit{P}}_{\mathit{P}}$(s) in an insulator, and a third one ${\mathit{P}}_{\mathit{T}}$(s), exactly at the transition. The function ${\mathit{P}}_{\mathit{T}}$ is an interesting hybrid of ${\mathit{P}}_{\mathit{W}}$(s) and ${\mathit{P}}_{\mathit{P}}$(s), it has the small-s behavior of the former and the large-s behavior of the latter one. A scaling theory of critical behavior of P(s) in finite samples is proposed and verified numerically.

Atomic snapshots of shared memory

Abstract: This paper introduces a general formulation of atomic snapshot memory, a shared memory partitioned into words written (updated) by individual processes, or instantaneously read (scanned) in its entirety. This paper presents three wait-free implementations of atomic snapshot memory. The first implementation in this paper uses unbounded (integer) fields in these registers, and is particularly easy to understand. The second implementation uses bounded registers. Its correctness proof follows the ideas of the unbounded implementation. Both constructions implement a single-writer snapshot memory, in which each word may be updated by only one process, from single-writer, n-reader registers. The third algorithm implements a multi-writer snapshot memory from atomic n-writer, n-reader registers, again echoing key ideas from the earlier constructions. All operations require Θ(n2) reads and writes to the component shared registers in the worst case. —Authors' Abstract