The autonomous norm on Ham(R2n) is bounded

We thank the Center for Advanced Studies in Mathematics at Ben Gurion University for supporting the visit of the second author at BGU. We also thank the anonymous referee for useful comments.Peer reviewedPostprin

Concordance group and stable commutator length in braid groups

We define a quasihomomorphism from braid groups to the concordance group of knots and examine its properties and consequences of its existence. In particular, we provide a relation between the stable four ball genus in the concordance group and the stable commutator length in braid groups, and produce examples of infinite families of concordance classes of knots with uniformly bounded four ball genus. We also provide applications to the geometry of the infinite braid group. In particular, we show that its commutator subgroup admits a stably unbounded conjugation invariant norm. This answers an open problem posed by Burago, Ivanov and Polterovich.Comment: 25 pages, 5 figure

Cancelation norm and the geometry of biinvariant word metrics

We study biinvariant word metrics on groups. We provide an efficient algorithm for computing the biinvariant word norm on a finitely generated free group and we construct an isometric embedding of a locally compact tree into the biinvariant Cayley graph of a nonabelian free group. We investigate the geometry of cyclic subgroups. We observe that in many classes of groups cyclic subgroups are either bounded or detected by homogeneous quasimorphisms. We call this property the bq-dichotomy and we prove it for many classes of groups of geometric origin.Comment: 32 pages, to appear in Glasgow Journal of Mathematic

Fragmentation norm and relative quasimorphisms

Acknowledgments. We would like to thank Lev Buhovsky, Yaron Ostrover and Leonid Polterovich for helpful discussions. We would like to thank the referees for a thorough reading of our paper and for very useful suggestions. We thank the Center for Advanced Studies in Mathematics at Ben Gurion University for supporting the visit of the second author at BGU. This work was funded by a Leverhulme Trust Research Project Grant RPG-2017-159.Peer reviewedPostprin

Scientific Standards and the Regulation of Genetically Modified Insects

Experimental releases of genetically modified (GM) insects are reportedly being evaluated in various countries, including Brazil, the Cayman Islands (United Kingdom), France, Guatemala, India, Malaysia, Mexico, Panama, Philippines, Singapore, Thailand, the United States of America, and Vietnam. GM mosquitoes (Aedes aegypti) have already been released for field trials into inhabited areas in the Cayman Islands (2009–?), Malaysia (2010–2011), and Brazil (2011–2012). Here, we assess the regulatory process in the first three countries permitting releases (Malaysia, US, and the Cayman Islands) in terms of pre-release transparency and scientific quality. We find that, despite 14 US government–funded field trials over the last 9 years (on a moth pest of cotton), there has been no scientific publication of experimental data, and in only two instances have permit applications been published. The world's first environmental impact statement (EIS) on GM insects, produced by US authorities in 2008, is found to be scientifically deficient on the basis that (1) most consideration of environmental risk is too generic to be scientifically meaningful; (2) it relies on unpublished data to establish central scientific points; and (3) of the approximately 170 scientific publications cited, the endorsement of the majority of novel transgenic approaches is based on just two laboratory studies in only one of the four species covered by the document. We find that it is not possible to determine from documents publically available prior to the start of releases if obvious hazards of the particular GM mosquitoes released in Malaysia, the Cayman Islands, and Brazil received expert examination. Simple regulatory measures are proposed that would build public confidence and stimulate the independent experimental studies that environmental risk assessments require. Finally, a checklist is provided to assist the general public, journalists, and lawmakers in determining, from documents issued by regulators prior to the start of releases, whether permit approval is likely to have a scientifically high quality basi

Evolutionary conservation of essential and highly expressed genes in Pseudomonas aeruginosa

<p>Abstract</p> <p>Background</p> <p>The constant increase in development and spread of bacterial resistance to antibiotics poses a serious threat to human health. New sequencing technologies are now on the horizon that will yield massive increases in our capacity for DNA sequencing and will revolutionize the drug discovery process. Since essential genes are promising novel antibiotic targets, the prediction of gene essentiality based on genomic information has become a major focus.</p> <p>Results</p> <p>In this study we demonstrate that pooled sequencing is applicable for the analysis of sequence variations of strain collections with more than 10 individual isolates. Pooled sequencing of 36 clinical <it>Pseudomonas aeruginosa </it>isolates revealed that essential and highly expressed proteins evolve at lower rates, whereas extracellular proteins evolve at higher rates. We furthermore refined the list of experimentally essential <it>P. aeruginosa </it>genes, and identified 980 genes that show no sequence variation at all. Among the conserved nonessential genes we found several that are involved in regulation, motility and virulence, indicating that they represent factors of evolutionary importance for the lifestyle of a successful environmental bacterium and opportunistic pathogen.</p> <p>Conclusion</p> <p>The detailed analysis of a comprehensive set of <it>P. aeruginosa </it>genomes in this study clearly disclosed detailed information of the genomic makeup and revealed a large set of highly conserved genes that play an important role for the lifestyle of this microorganism. Sequencing strain collections enables for a detailed and extensive identification of sequence variations as potential bacterial adaptation processes, e.g., during the development of antibiotic resistance in the clinical setting and thus may be the basis to uncover putative targets for novel treatment strategies.</p

On the autonomous norm on the group of Hamiltonian diffeomorphisms of the torus

We would like to thank Luis Haug for fruitful discussions and Pierre Py for comments on the first version of the paper. We thank the CRM and ISM who supported the visit of Kędra in Montreal. Kędra also thanks the Max Planck Institute for Mathematics for supporting his visit in Bonn. Part of this work has been done during Brandenbursky’s stay at IHES and CRM. We wish to express his gratitude to both institutes. Brandenbursky was supported by CRM-ISM fellowship and NSF grant No. 1002477. This work has been done during Shelukhin’s stay in CRM, ICJ Lyon 1, Institut Mittag Leffler, and IAS. He thanks these institutions for their warm hospitality. He was partially supported by CRM-ISM fellowship, ERC Grant RealUMan, Mittag Leffler fellowship, and NSF grant No. DMS-1128155.Peer reviewedPostprin

Recruitment of the ATP-dependent chromatin remodeler dMi-2 to the transcribed region of active heat shock genes

The ATP-dependent chromatin remodeler dMi-2 can play both positive and negative roles in gene transcription. Recently, we have shown that dMi-2 is recruited to the hsp70 gene in a heat shock-dependent manner, and is required to achieve high transcript levels. Here, we use chromatin immunoprecipitation sequencing (ChIP-Seq) to identify other chromatin regions displaying increased dMi-2 binding upon heat shock and to characterize the distribution of dMi-2 over heat shock genes. We show that dMi-2 is recruited to the body of at least seven heat shock genes. Interestingly, dMi-2 binding extends several hundred base pairs beyond the polyadenylation site into the region where transcriptional termination occurs. We find that dMi-2 does not associate with the entire nucleosome-depleted hsp70 locus 87A. Rather, dMi-2 binding is restricted to transcribed regions. Our results suggest that dMi-2 distribution over active heat shock genes are determined by transcriptional activity