712 research outputs found
DNA target sequence and FNR-dependent gene expression.
FNR proteins are global transcription regulators that respond to fluctuations in environmental oxygen. They recognise a DNA target consisting of an inverted repeat, TTGATN(1)N(2)N(3)N(4)ATCAA (where N(1-4) represents a non-conserved tetrad, NCT). Analysis of 68 known and predicted FNR sites from the Escherichia coli K12 genome revealed a bias toward A or T at positions N(2) and N(3) of the NCT. The effect of the NCT sequence on FNR-dependent transcription in vivo was assessed using a series of class II and class I model promoters with different NCT sequences. Changing the NCT sequence did not affect basal activity but altered anaerobic induction by as much as an order of magnitude. Thus, the NCT sequence is a fundamental component in setting the dynamic range of the FNR switch
A Model for the Analysis of Caries Occurrence in Primary Molar Tooth Surfaces
Recently methods of caries quantification in the primary dentition have moved away from summary âwhole mouthâ measures at the individual level to methods based on generalised linear modelling (GLM) approaches or survival analysis approaches. However, GLM approaches based on logistic transformation fail to take into account the time-dependent process of tooth/surface survival to caries. There may also be practical difficulties associated with casting parametric survival-based approaches in a complex multilevel hierarchy and the selection of an optimal survival distribution, while non-parametric survival methods are not generally suitable for the assessment of supplementary information recorded on study participants. In the current investigation, a hybrid semi-parametric approach comprising elements of survival-based and GLM methodologies suitable for modelling of caries occurrence within fixed time periods is assessed, using an illustrative multilevel data set of caries occurrence in primary molars from a cohort study, with clustering of data assumed to occur at surface and tooth levels. Inferences of parameter significance were found to be consistent with previous parametric survival-based analyses of the same data set, with gender, socio-economic status, fluoridation status, tooth location, surface type and fluoridation status-surface type interaction significantly associated with caries occurrence. The appropriateness of the hierarchical structure facilitated by the hybrid approach was also confirmed. Hence the hybrid approach is proposed as a more appropriate alternative to primary caries modelling than non-parametric survival methods or other GLM-based models, and as a practical alternative to more rigorous survival-based methods unlikely to be fully accessible to most researchers
Exploiting Imine Photochemistry for Masked NâCentered Radical Reactivity
This report details the development of a masked Nâcentered radical strategy that harvests the energy of light to drive the conversion of cyclopropylimines to 1âaminonorbornanes. This process employs the Nâcentered radical character of a photoexcited imine to facilitate the homolytic fragmentation of the cyclopropane ring and the subsequent radical cyclization sequence that forms two new CâC bonds en route to the norbornane core. Achieving bondâforming reactivity as a function of the Nâcentered radical character of an excited state Schiff base is unique, requiring only violet light in this instance. This methodology operates in continuous flow, enhancing the potential to translate beyond the academic sector. The operational simplicity of this photochemical process and the structural novelty of the (hetero)arylâfused 1âaminonorbornane products are anticipated to provide a valuable addition to discovery efforts in pharmaceutical and agrochemical industries.The Nâcentered openâshell character of photoexcited cyclopropylimines is utilized to initiate a radical fragmentationâcyclization sequence that generates bridgeheadâfunctionalized norbornanes. This unique mode of reactivity requires only violet light to proceed, and the 1âaminonorbornane products are valuable building blocks for drug and agrochemical discovery programs.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/153143/1/anie201909492_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/153143/2/anie201909492.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/153143/3/anie201909492-sup-0001-misc_information.pd
Determining Training Needs for Cloud Infrastructure Investigations using I-STRIDE
As more businesses and users adopt cloud computing services, security
vulnerabilities will be increasingly found and exploited. There are many
technological and political challenges where investigation of potentially
criminal incidents in the cloud are concerned. Security experts, however, must
still be able to acquire and analyze data in a methodical, rigorous and
forensically sound manner. This work applies the STRIDE asset-based risk
assessment method to cloud computing infrastructure for the purpose of
identifying and assessing an organization's ability to respond to and
investigate breaches in cloud computing environments. An extension to the
STRIDE risk assessment model is proposed to help organizations quickly respond
to incidents while ensuring acquisition and integrity of the largest amount of
digital evidence possible. Further, the proposed model allows organizations to
assess the needs and capacity of their incident responders before an incident
occurs.Comment: 13 pages, 3 figures, 3 tables, 5th International Conference on
Digital Forensics and Cyber Crime; Digital Forensics and Cyber Crime, pp.
223-236, 201
Neutron Correlations in the Decay of the First Excited State of 11Li
The decay of unbound excited 11Li was measured after being populated by a two-proton removal from a 13B beam at 71 MeV/nucleon. Decay energy spectra and Jacobi plots were obtained from measurements of the momentum vectors of the 9Li fragment and neutrons. A resonance at an excitation energy of âŒ1.2 MeV was observed. The kinematics of the decay are equally well fit by a simple dineutron-like model or a phase-space model that includes final state interactions. A sequential decay model can be excluded
Social physique anxiety and physical activity in early adolescent girls : the influence of maturation and physical activity motives
This study considered the influence of maturation on social physique anxiety (SPA), the relationship between SPA and current and future physical activity (PA) levels and the influence of motives for physical activity on this relationship in early adolescent girls (n=162; mean age=11.80±0.33 years). Participants completed the Pubertal Development Scale, the modified Social Physique Anxiety Scale and the Motives for Physical Activity Scale at baseline and the Physical Activity Questionnaire for Older Children at baseline and 6 months later. The girls became less active across the 6 months and girls in the early stages of maturation had significantly lower SPA than the girls in the middle and late stages of maturation. SPA was not related to current or future physical activity in the sample as a whole. Cluster analysis identified four groups with different motive profiles and the High Appearance and Fitness group demonstrated a moderate negative relationship between SPA and PA at phase 1, whereas the other groups did not. These findings indicate that SPA may increase with maturation and the relationship between SPA and PA is dependent on reasons for being active. For girls who are motivated to be active primarily by body-related reasons SPA is likely to lead to lower levels of PA
Microscopic calculations of medium effects for 200-MeV (p,p') reactions
We examine the quality of a G-matrix calculation of the effective
nucleon-nucleon (NN) interaction for the prediction of the cross section and
analyzing power for 200-MeV (p,p') reactions that populate natural parity
states in O, Si, and Ca. This calculation is based on a
one-boson-exchange model of the free NN force that reproduces NN observables
well. The G-matrix includes the effects of Pauli blocking, nuclear binding, and
strong relativistic mean-field potentials. The implications of adjustments to
the effective mass ansatz to improve the quality of the approximation at
momenta above the Fermi level will be discussed, along with the general quality
of agreement to a variety of (p,p') transitions.Comment: 36 pages, TeX, 18 figure
Zero temperature string breaking in lattice quantum chromodynamics
The separation of a heavy quark and antiquark pair leads to the formation of
a tube of flux, or "string", which should break in the presence of light
quark-antiquark pairs. This expected zero-temperature phenomenon has proven
elusive in simulations of lattice QCD. We study mixing between the string state
and the two-meson decay channel in QCD with two flavors of dynamical sea
quarks. We confirm that mixing is weak and find that it decreases at level
crossing. While our study does not show direct effects of internal quark loops,
our results, combined with unitarity, give clear confirmation of string
breaking.Comment: 20 pages, 7 figures. With small clarifications and two additions to
references. Submitted to Phys. Rev.
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