Dynamic Control of the DNA Replication Initiation Protein DnaA by Soj/ParA

SummaryRegulation of DNA replication and segregation is essential for all cells. Orthologs of the plasmid partitioning genes parA, parB, and parS are present in bacterial genomes throughout the prokaryotic evolutionary tree and are required for accurate chromosome segregation. However, the mechanism(s) by which parABS genes ensure proper DNA segregation have remained unclear. Here we report that the ParA ortholog in B. subtilis (Soj) controls the activity of the DNA replication initiator protein DnaA. Subcellular localization of several Soj mutants indicates that Soj acts as a spatially regulated molecular switch, capable of either inhibiting or activating DnaA. We show that the classical effect of Soj inhibiting sporulation is an indirect consequence of its action on DnaA through activation of the Sda DNA replication checkpoint. These results suggest that the pleiotropy manifested by chromosomal parABS mutations could be the indirect effects of a primary activity regulating DNA replication initiation

Oliver Wyman 2018 Flight Operations Survey

Oliver Wyman would like to share training-related insights from its inaugural Flight Operations Survey, canvassing leaders from across the aviation industry, including airline flight ops departments, OEMs, and 3rd-party training & services companies. We will address topics such as technology & disruption, integrated planning, safety & compliance, leadership, and of course training

Super resolution computational saturated absorption microscopy

Imaging beyond the diffraction limit barrier has attracted wide attention due to the ability to resolve image features that were previously hidden. Of the various super-resolution microscopy techniques available, a particularly simple method called saturated excitation microscopy (SAX) requires only a simple modification of a laser scanning microscope where the illumination beam power is sinusoidally modulated and driven into saturation. SAX images are extracted from harmonics of the modulation frequency and exhibit improved spatial resolution. Unfortunately, this elegant strategy is hindered by the incursion of shot noise that prevents high resolution imaging in many realistic scenarios. Here, we demonstrate a new technique for super resolution imaging that we call computational saturated absorption (CSA) in which a joint deconvolution is applied to a set of images with diversity in spatial frequency support among the point spread functions used in the image formation with saturated laser scanning fluorescence microscope. CSA microscopy allows access to the high spatial frequency diversity in a set of saturated effective point spread functions, while avoiding image degradation from shot noise.Comment: 26 pages, 15 figure

All-optical conditional logic with a nonlinear photonic crystal nanocavity

We demonstrate tunable frequency-converted light mediated by a chi-(2) nonlinear photonic crystal nanocavity. The wavelength-scale InP-based cavity supports two closely-spaced localized modes near 1550 nm which are resonantly excited by a 130 fs laser pulse. The cavity is simultaneously irradiated with a non-resonant probe beam, giving rise to rich second-order scattering spectra reflecting nonlinear mixing of the different resonant and non-resonant components. In particular, we highlight the radiation at the sum frequencies of the probe beam and the respective cavity modes. This would be a useful, minimally-invasive monitor of the joint occupancy state of multiple cavities in an integrated optical circuit.Comment: 4 pages, 4 figure

Paper Session I-A - Unmanned Aerial Vehicles as Technology Demonstrators for Advanced Range Systems

This project consists of the development and operation of an unmanned aerial vehicle (UAV) as a technology demonstration test bed for advanced range systems under development at Kennedy Space Center. The goal is to acquire a reliable, rapidly accessible vehicle for initial flight testing of electronic payloads through a limited portion of airspace to verify basic communications, command and control, tracking, and telemetry functions. The cost and schedule benefits of the project should exceed the other available options of flight in actual manned aircraft or sounding rockets. The vehicle will be remotely piloted with a reliable command and control system independent of the devices under test. It must account for any failure modes, and have contingencies to maximize safety of the operations. The UAV will provide standardized mounting, protection, and power to the devices under test. Considerations of airspace, FAA regulations, and authorizations for UAV operations must be thoroughly evaluated. This rapid demonstration capability will expedite development and initial. testing of advanced range systems projects, and provide gains in overall UAV knowledge, at a reasonable cost. The project fits well within existing ARTWG (Advanced Range Technology Working Group) Roadmaps for the future of Range Systems

Seduced by "fakes" : Producing the excessive interplay of authentic/counterfeit from a Baudrillardian perspective

Authenticity has often been considered to be a key theme in contemporary consumer culture. One of its manifestations is how branded market offerings can maintain authentic meanings, especially in a market increasingly saturated with counterfeit substitutes. By following a Baudrillardian perspective, we focus on fashion objects in the "branded luxury" category to problematize the sanctity of the authentic/counterfeit distinction. We argue that marketing literature generally attempts to normatively maintain and impose the distinction in ways that obscure the complexities of this conceptual interplay. We posit that instead of normative accounts that attempt to sanctify the extant orders of global capitalist markets, literature on luxury consumption should instead recognize the excess of meaning in the semiotic interplay of commodified authentic/counterfeit meanings. Any view of morality in luxury consumption should thus recognize "ambivalence" and "seduction" as its intensive qualities.Peer reviewe

Second-Order Nonlinear Mixing of Two Modes in a Planar Photonic Crystal Microcavity

Polarization-resolved second-harmonic spectra are obtained from the resonant modes of a two-dimensional planar photonic crystal microcavity patterned in a free-standing InP slab. The photonic crystal microcavity is comprised of a single missing-hole defect in a hexagonal photonic crystal host formed with elliptically-shaped holes. The cavity supports two orthogonally-polarized resonant modes split by 60 wavenumbers. Sum-frequency data are reported from the nonlinear interaction of the two coherently excited modes, and the polarization dependence is explained in terms of the nonlinear susceptibility tensor of the host InP.Comment: 7 pages, 8 Postscript figures, to be presented at Photonics West Jan. 2

Dynamic Control Flow in Large-Scale Machine Learning

Many recent machine learning models rely on fine-grained dynamic control flow for training and inference. In particular, models based on recurrent neural networks and on reinforcement learning depend on recurrence relations, data-dependent conditional execution, and other features that call for dynamic control flow. These applications benefit from the ability to make rapid control-flow decisions across a set of computing devices in a distributed system. For performance, scalability, and expressiveness, a machine learning system must support dynamic control flow in distributed and heterogeneous environments. This paper presents a programming model for distributed machine learning that supports dynamic control flow. We describe the design of the programming model, and its implementation in TensorFlow, a distributed machine learning system. Our approach extends the use of dataflow graphs to represent machine learning models, offering several distinctive features. First, the branches of conditionals and bodies of loops can be partitioned across many machines to run on a set of heterogeneous devices, including CPUs, GPUs, and custom ASICs. Second, programs written in our model support automatic differentiation and distributed gradient computations, which are necessary for training machine learning models that use control flow. Third, our choice of non-strict semantics enables multiple loop iterations to execute in parallel across machines, and to overlap compute and I/O operations. We have done our work in the context of TensorFlow, and it has been used extensively in research and production. We evaluate it using several real-world applications, and demonstrate its performance and scalability.Comment: Appeared in EuroSys 2018. 14 pages, 16 figure