Direct interaction of FliX and FlbD is required for their regulatory activity in Caulobacter crescentus

Background: The temporal and spatial expression of late flagellar genes in Caulobacter crescentus is activated by the transcription factor FlbD and its partner trans-acting factor FliX. The physical interaction of these two proteins represents an alternative mechanism for regulating the activity of $\sigma^{54}$ transcription factors. This study is to characterize the interaction of the two proteins and the consequences of the interaction on their regulatory activity. Results: FliX and FlbD form stable complexes, which can stand the interference of 2.65 M NaCl. The stability of FliX and FlbD was affected by the co-existence of each other. Five FliX mutants (R71A, L85K, $\Delta$117-118, T130L, and L136K) were created by site-directed mutagenesis in conserved regions of the protein. All mutants were successfully expressed in both wild-type and $\Delta fliX$ Caulobacter strains. All but $FliX_{L85K}$ could rescue the motility and cell division defects of a $\Delta fliX$ mutant strain. The ability of FliX to regulate the transcription of class II and class III/IV flagellar promoters was fully diminished due to the L85K mutation. Co-immunoprecipitation experiment revealed that $FliX_{L85K}$ was unable to physically interact with FlbD. Conclusions: FliX interacts with FlbD and thereby directly regulates the activity of FlbD in response to flagellar assembly. Mutations in highly conserved regions of FliX could severely affect the recognition between FliX and FlbD and hence interrupt the normal progression of flagellar synthesis and other developmental events in Caulobacter.Molecular and Cellular Biolog

Do Black-Owned Banks Substitute for Payday Lenders? An Exploratory Study

The annualized interest rate charged on payday loans can reach 1,950 percent, whereas similar rates charged by banks are typically less than 25 percent. Also, persons borrowing from payday lenders and paying the higher interest rates are disproportionately lower-income Blacks. This provides an incentive for Blacks seeking loans to turn to banks rather than payday lenders. This may be more likely to happen when there are Black-owned banks in communities with greater percentages of Blacks. Indeed, offices of such banks may substitute for payday loan stores, providing a greater opportunity for Blacks to avoid the higher interest rates associated with payday lenders. We hypothesize that to the extent Black-owned banks substitute for payday there is a greater opportunity for lower-income Blacks to substitute/switch firms and thereby seek lower-cost loans. We do find that there are significantly fewer payday loan stores in counties where there are more Black bank offices

On covers of cyclic acts over monoids

In (Bull. Lond. Math. Soc. 33:385–390, 2001) Bican, Bashir and Enochs finally solved a long standing conjecture in module theory that all modules over a unitary ring have a flat cover. The only substantial work on covers of acts over monoids seems to be that of Isbell (Semigroup Forum 2:95–118, 1971), Fountain (Proc. Edinb. Math. Soc. (2) 20:87–93, 1976) and Kilp (Semigroup Forum 53:225–229, 1996) who only consider projective covers. To our knowledge the situation for flat covers of acts has not been addressed and this paper is an attempt to initiate such a study. We consider almost exclusively covers of cyclic acts and restrict our attention to strongly flat and condition (P) covers. We give a necessary and sufficient condition for the existence of such covers and for a monoid to have the property that all its cyclic right acts have a strongly flat cover (resp. (P)-cover). We give numerous classes of monoids that satisfy these conditions and we also show that there are monoids that do not satisfy this condition in the strongly flat case. We give a new necessary and sufficient condition for a cyclic act to have a projective cover and provide a new proof of one of Isbell’s classic results concerning projective covers. We show also that condition (P) covers are not unique, unlike the situation for projective covers

Growth of nonsymmetric operads

The paper concerns the Gelfand-Kirillov dimension and the generating series of nonsymmetric operads. An analogue of Bergman's gap theorem is proved, namely, no finitely generated locally finite nonsymmetric operad has Gelfand-Kirillov dimension strictly between $1$ and $2$. For every $r\in \{0\}\cup \{1\}\cup [2,\infty)$ or $r=\infty$, we construct a single-element generated nonsymmetric operad with Gelfand-Kirillov dimension $r$. We also provide counterexamples to two expectations of Khoroshkin and Piontkovski about the generating series of operads.Comment: 32 pages, 9 figure

Huron-to-Erie Water Quality Data Platform

To address the challenges of environmental degradation, creation of a sustainable urban environment, and increased public engagement and awareness, a mass-oriented, user-friendly and cloud-based data platform has been developed and deployed to provide integrative water quality data in one of the most critical urban corridors of the Laurentian Great Lakes system. In this paper, we describe the data platform developed for the watershed and connecting channels between Lake Huron and Lake Erie, including the St. Clair River, Lake St. Chair, and the Detroit River. This data platform greatly facilitates the access of data across data providers and agencies. Several example applications are provided of platform use for temporal and spatial characterization of intake water source quality and urban beach health through consideration of Escherichia coli, Dissolved Oxygen, pH, and blue-green algae detections along the Huron-to-Erie corridor. Although data collection for each of these parameters was designed for unique purposes and supported through varied agencies, this paper shows the collective advantages of applying the data beyond the original scope of collection

A knowledge discovery service system for provenance exploration.

Scientific research has moved from an isolated environment into a collaborated culture due to the data explosion and the experiment complexity. Several scientific workflow systems have been developed to support scientists to conduct the scientific analysis and create knowledge. They provide the ability to automatically record provenance, the process that led to a particular data, which can be used by other scientists for better understanding, re-using and verifying a data product to generate new knowledge. However, most of the existing scientific workflow systems provide poor query capability for users to effectively find relevant provenance information. It is not a trivial task due to the complexity of the workflow and the size of the provenance graphs. In this work, we propose a system architecture for provenance exploration in which querying, navigation and visualization methods are combined together. It enables effective and efficient knowledge discovery among various provenance information generated by different workflow runs