Five-analyzer Johann spectrometer for hard X-ray photon-in/photon-out spectroscopy at the Inner Shell Spectroscopy beamline at NSLS-II: design, alignment and data acquisition.

Here, a recently commissioned five-analyzer Johann spectrometer at the Inner Shell Spectroscopy beamline (8-ID) at the National Synchrotron Light Source II (NSLS-II) is presented. Designed for hard X-ray photon-in/photon-out spectroscopy, the spectrometer achieves a resolution in the 0.5-2 eV range, depending on the element and/or emission line, providing detailed insights into the local electronic and geometric structure of materials. It serves a diverse user community, including fields such as physical, chemical, biological, environmental and materials sciences. This article details the mechanical design, alignment procedures and data-acquisition scheme of the spectrometer, with a particular focus on the continuous asynchronous data-acquisition approach that significantly enhances experimental efficiency.

A library of yeast transcription factor motifs reveals a widespread function for Rsc3 in targeting nucleosome exclusion at promoters.

The sequence specificity of DNA-binding proteins is the primary mechanism by which the cell recognizes genomic features. Here, we describe systematic determination of yeast transcription factor DNA-binding specificities. We obtained binding specificities for 112 DNA-binding proteins representing 19 distinct structural classes. One-third of the binding specificities have not been previously reported. Several binding sequences have striking genomic distributions relative to transcription start sites, supporting their biological relevance and suggesting a role in promoter architecture. Among these are Rsc3 binding sequences, containing the core CGCG, which are found preferentially approximately 100 bp upstream of transcription start sites. Mutation of RSC3 results in a dramatic increase in nucleosome occupancy in hundreds of proximal promoters containing a Rsc3 binding element, but has little impact on promoters lacking Rsc3 binding sequences, indicating that Rsc3 plays a broad role in targeting nucleosome exclusion at yeast promoters.

Performance of a collimating L-shaped laterally graded multilayer mirror for the IXS analyzer system at NSLS-II.

The L-shaped laterally graded multilayer mirror is a vital part of the ultrahigh-energy and momentum-resolution inelastic X-ray scattering spectrometer at the National Synchrotron Light Source II. This mirror was designed and implemented as a two-dimensional collimating optic for the analyzer system. Its performance was characterized using a secondary large-divergence source at the 30-ID beamline of the Advanced Photon Source, which yielded an integrated reflectivity of 47% and a collimated beam divergence of 78 µrad with a source size of 10 µm. Numerical simulations of the mirror performance in tandem with the analyzer crystal optics provided details on the acceptance sample volume in forward scattering and defined the technical requirements on the mirror stability and positioning precision. It was shown that the mirror spatial and angular stability must be in the range <8.4 µm and <21.4 µrad, respectively, for reliable operation of the analyzer.

Clinical and Microbiological Evaluation of a Chlorhexidine-Modified Glass Ionomer Cement (GIC-CHX) Restoration Placed Using the Atraumatic Restorative Treatment (ART) Technique.

The aims of this study were to investigate the clinical effectiveness and patient acceptability of a modified glass ionomer cement placed using the atraumatic restorative treatment (ART) technique to treat root caries, and to carry out microbiological analysis of the restored sites. Two clinically visible root surface carious lesions per participant were restored using ART. One was restored with commercial glass ionomer cement (GIC) (ChemFil® Superior, DENTSPLY, Konstonz, Germany) which acted as the control. The other carious root lesion was restored with the same GIC modified with 5% chlorhexidine digluconate (GIC-CHX; test). Patient acceptability and restoration survival rate were evaluated at baseline and after 6 months. Plaque and saliva samples around the test and control restorations were collected, and microbiological analysis for selected bacterial and fungal viability were completed at baseline, and after 1, 3, and 6 months. In total, 52 restorations were placed using GIC and GIC-CHX in 26 participants; 1 patient was lost to follow-up. After reviewing the restorations during their baseline appointments, participants indicated that they were satisfied with the appearance of the restorations (n = 25, 96%) and did not feel anxious during the procedure (n = 24, 92%). Forty-eight percent (n = 12) of the GIC-CHX restorations were continuous with the existing anatomic form as opposed to six for the GIC restorations (24%), a difference which was statistically significant (p = 0.036). There was no statistically significant reduction in the mean count of the tested microorganisms in plaque samples for either type of restorations after 1, 3, or 6 months. Restoration of carious root surfaces with GIC-CHX resulted in higher survival rates than the control GIC. ART using GIC-CHX may therefore be a viable approach for use in outreach dental services to restore root surface carious lesions where dental services are not readily available, and for older people and special needs groups.

Synchrotron X-ray tests of an L-shaped laterally graded multilayer mirror for the analyzer system of the ultra-high-resolution IXS spectrometer at NSLS-II.

Characterization and testing of an L-shaped laterally graded multilayer mirror are presented. This mirror is designed as a two-dimensional collimating optics for the analyzer system of the ultra-high-resolution inelastic X-ray scattering (IXS) spectrometer at National Synchrotron Light Source II (NSLS-II). The characterization includes point-to-point reflectivity measurements, lattice parameter determination and mirror metrology (figure, slope error and roughness). The synchrotron X-ray test of the mirror was carried out reversely as a focusing device. The results show that the L-shaped laterally graded multilayer mirror is suitable to be used, with high efficiency, for the analyzer system of the IXS spectrometer at NSLS-II.

Design, characterization, and performance of a hard x-ray transmission microscope at the National Synchrotron Light Source II 18-ID beamline.

A transmission X-ray microscope has been designed and commissioned at the 18-ID Full-field X-ray Imaging beamline at the National Synchrotron Light Source II. This instrument operates in the 5-11 keV range, and, with the current set of optics, is capable of 30 nm spatial resolution imaging, with a field of view of about 40 µm. For absorption contrast, the minimum exposure time for a single projection image is about 20 ms and an entire 3D tomography data set can be acquired in under 1 min. The system enables tomographic reconstructions with sub-50 nm spatial resolution without the use of markers on the sample or corrections for rotation run-outs.

Beyond the income inequality hypothesis: class, neo-liberalism, and health inequalities.

This paper describes and critiques the income inequality approach to health inequalities. It then presents an alternative class-based model through a focus on the causes and not only the consequences of income inequalities. In this model, the relationship between income inequality and health appears as a special case within a broader causal chain. It is argued that global and national socio-political-economic trends have increased the power of business classes and lowered that of working classes. The neo-liberal policies accompanying these trends led to increased income inequality but also poverty and unequal access to many other health-relevant resources. But international pressures towards neo-liberal doctrines and policies are differentially resisted by various nations because of historically embedded variation in class and institutional structures. Data presented indicates that neo-liberalism is associated with greater poverty and income inequalities, and greater health inequalities within nations. Furthermore, countries with Social Democratic forms of welfare regimes (i.e., those that are less neo-liberal) have better health than do those that are more neo-liberal. The paper concludes with discussion of what further steps are needed to "go beyond" the income inequality hypothesis towards consideration of a broader set of the social determinants of health.

Diversity and complexity in DNA recognition by transcription factors.

Sequence preferences of DNA binding proteins are a primary mechanism by which cells interpret the genome. Despite the central importance of these proteins in physiology, development, and evolution, comprehensive DNA binding specificities have been determined experimentally for only a few proteins. Here, we used microarrays containing all 10-base pair sequences to examine the binding specificities of 104 distinct mouse DNA binding proteins representing 22 structural classes. Our results reveal a complex landscape of binding, with virtually every protein analyzed possessing unique preferences. Roughly half of the proteins each recognized multiple distinctly different sequence motifs, challenging our molecular understanding of how proteins interact with their DNA binding sites. This complexity in DNA recognition may be important in gene regulation and in the evolution of transcriptional regulatory networks.

Population health in Canada: a brief critique.

An internationally influential model of population health was developed in Canada in the 1990s, shifting the research agenda beyond health care to the social and economic determinants of health. While agreeing that health has important social determinants, the authors believe that this model has serious shortcomings; they critique the model by focusing on its hidden assumptions. Assumptions about how knowledge is produced and an implicit interest group perspective exclude the sociopolitical and class contexts that shape interest group power and citizen health. Overly rationalist assumptions about change understate the role of agency. The authors review the policy and practice implications of the Canadian population health model and point to alternative ways of viewing the determinants of health.