Evidence on the Efficacy of School-Based Incentives for Healthy Living

We analyze the effects of a school-based incentive program on children's exercise habits. The program offers children an opportunity to win prizes if they walk or bike to school during prize periods. We use daily child-level data and individual fixed effects models to measure the impact of the prizes by comparing behavior during prize periods with behavior during non-prize periods. Variation in the timing of prize periods across different schools allows us to estimate models with calendardate fixed effects to control for day-specific attributes, such as weather and proximity to holidays. On average, we find that being in a prize period increases riding behavior by sixteen percent, a large impact given that the prize value is just six cents per participating student. We also find that winning a prize lottery has a positive impact on ridership over subsequent weeks; consider heterogeneity across prize type, gender, age, and calendar month; and explore differential effects on the intensive versus extensive margins.health; exercise; children; school; incentives; active commuting

The 2.5 m Telescope of the Sloan Digital Sky Survey

We describe the design, construction, and performance of the Sloan Digital Sky Survey Telescope located at Apache Point Observatory. The telescope is a modified two-corrector Ritchey-Chretien design which has a 2.5-m, f/2.25 primary, a 1.08-m secondary, a Gascoigne astigmatism corrector, and one of a pair of interchangeable highly aspheric correctors near the focal focal plane, one for imaging and the other for spectroscopy. The final focal ratio is f/5. The telescope is instrumented by a wide-area, multiband CCD camera and a pair of fiber-fed double spectrographs. Novel features of the telescope include: (1) A 3 degree diameter (0.65 m) focal plane that has excellent image quality and small geometrical distortions over a wide wavelength range (3000 to 10,600 Angstroms) in the imaging mode, and good image quality combined with very small lateral and longitudinal color errors in the spectroscopic mode. The unusual requirement of very low distortion is set by the demands of time-delay-and-integrate (TDI) imaging; (2) Very high precision motion to support open loop TDI observations; and (3) A unique wind baffle/enclosure construction to maximize image quality and minimize construction costs. The telescope had first light in May 1998 and began regular survey operations in 2000.Comment: 87 pages, 27 figures. AJ (in press, April 2006

The Sloan Digital Sky Survey: Technical Summary

The Sloan Digital Sky Survey (SDSS) will provide the data to support detailed investigations of the distribution of luminous and non- luminous matter in the Universe: a photometrically and astrometrically calibrated digital imaging survey of pi steradians above about Galactic latitude 30 degrees in five broad optical bands to a depth of g' about 23 magnitudes, and a spectroscopic survey of the approximately one million brightest galaxies and 10^5 brightest quasars found in the photometric object catalog produced by the imaging survey. This paper summarizes the observational parameters and data products of the SDSS, and serves as an introduction to extensive technical on-line documentation.Comment: 9 pages, 7 figures, AAS Latex. To appear in AJ, Sept 200

Two-Dimensional Frameworks Based on Ag(I)–N Bond Formation: Single Crystal to Single Molecular Sheet Transformation

A series of new two-dimensional coordination framework materials, based on Ag­(I)–N bond formation, has been synthesized and structurally characterized by single crystal methods. Reactions between the poly-monodentate bridging ligand <i>N</i>,<i>N</i>′-((1r,4r)-cyclohexane-1,4-diyl)­bis­(1-(pyridin-3-yl)­methanimine), <b>L1</b>, and silver salts yield compounds {[Ag­(<b>L1</b>)­(MeCN)]­(CF₃SO₃^–)}_<i>n</i>, <b>1</b>, {[Ag­(<b>L1</b>)­(PF₂O₂^–)]·H₂O}_<i>n</i>, <b>2</b>, and {Ag₂(<b>L1</b>)­(tosylate)₂}_<i>n</i>, <b>3</b>. The frameworks of these materials exhibit two distinct net topologies: 3⁶.4⁶.5³ (<b>1</b> and <b>2</b>) and 4⁴.6² (<b>3</b>). In all cases, <b>L1</b> ligands are found to be fully saturated, in terms of metal ion binding, with both sets of pyridyl and imino N atoms involved, though in <b>1</b> and <b>2</b>, crystallographically independent <b>L1</b> moieties also display pyridyl-only binding. Either solvent (<b>1</b>) or the anion (<b>2</b> and <b>3</b>) acts as a terminal ligand to support interlayer interactions in the solid state. For <b>2</b> and <b>3</b> the molecular sheet orientation lies in the plane of the largest crystal face, indicating that crystal growth is preferentially driven by coordinate bond formation. Despite the relatively labile nature, typical of such Ag­(I)–N bonds, solvent-based exfoliation of crystals of <b>3</b> was shown to provide dispersions of large, μm², flakes which readily deposit on oxide surfaces as single-molecule sheets, as revealed by atomic force microscopy

Two-Dimensional Frameworks Based on Ag(I)–N Bond Formation: Single Crystal to Single Molecular Sheet Transformation

A series of new two-dimensional coordination framework materials, based on Ag­(I)–N bond formation, has been synthesized and structurally characterized by single crystal methods. Reactions between the poly-monodentate bridging ligand <i>N</i>,<i>N</i>′-((1r,4r)-cyclohexane-1,4-diyl)­bis­(1-(pyridin-3-yl)­methanimine), <b>L1</b>, and silver salts yield compounds {[Ag­(<b>L1</b>)­(MeCN)]­(CF₃SO₃^–)}_<i>n</i>, <b>1</b>, {[Ag­(<b>L1</b>)­(PF₂O₂^–)]·H₂O}_<i>n</i>, <b>2</b>, and {Ag₂(<b>L1</b>)­(tosylate)₂}_<i>n</i>, <b>3</b>. The frameworks of these materials exhibit two distinct net topologies: 3⁶.4⁶.5³ (<b>1</b> and <b>2</b>) and 4⁴.6² (<b>3</b>). In all cases, <b>L1</b> ligands are found to be fully saturated, in terms of metal ion binding, with both sets of pyridyl and imino N atoms involved, though in <b>1</b> and <b>2</b>, crystallographically independent <b>L1</b> moieties also display pyridyl-only binding. Either solvent (<b>1</b>) or the anion (<b>2</b> and <b>3</b>) acts as a terminal ligand to support interlayer interactions in the solid state. For <b>2</b> and <b>3</b> the molecular sheet orientation lies in the plane of the largest crystal face, indicating that crystal growth is preferentially driven by coordinate bond formation. Despite the relatively labile nature, typical of such Ag­(I)–N bonds, solvent-based exfoliation of crystals of <b>3</b> was shown to provide dispersions of large, μm², flakes which readily deposit on oxide surfaces as single-molecule sheets, as revealed by atomic force microscopy

Structural Diversity and Argentophilic Interactions in One-Dimensional Silver-Based Coordination Polymers

A series of new one-dimensional coordination polymer materials, based on Ag­(I)–N bond formation, has been synthesized and structurally characterized by single crystal X-ray diffraction. Reactions between the poly-monodentate ligands based on (<i>1E</i>,<i>1</i>′<i>E</i>′)<i>-N</i>,<i>N</i>′<i>-</i>(-bis­(1-pyridin-3-yl)­methanimine and Ag­(I) salts give products that feature simple coordination chains or metallacyclic- and tape-based structures. For the simple chains these are as either isolated units, or assembled in dimeric and tetrameric arrangements through intermetallic, argentophilic interactions. However, crystal packing effects and solvent inclusion are found to readily disrupt this type of bonding. Density functional theory calculations provide an assessment of the bond order and the influence of anion binding on these interactions

Oleoyl coenzyme A regulates interaction of transcriptional regulator RaaS (Rv1219c) with DNA in mycobacteria

We have recently shown that RaaS (regulator of antimicrobial-assisted survival), encoded by Rv1219c in Mycobacterium tuberculosis and by bcg_1279c in Mycobacterium bovis bacillus Calmette-Guérin, plays an important role in mycobacterial survival in prolonged stationary phase and during murine infection. Here, we demonstrate that long chain acyl-CoA derivatives (oleoyl-CoA and, to lesser extent, palmitoyl-CoA) modulate RaaS binding to DNA and expression of the downstream genes that encode ATP-dependent efflux pumps. Moreover, exogenously added oleic acid influences RaaS-mediated mycobacterial improvement of survival and expression of the RaaS regulon. Our data suggest that long chain acyl-CoA derivatives serve as biological indicators of the bacterial metabolic state. Dysregulation of efflux pumps can be used to eliminate non-growing mycobacteria

Transforming knowledge systems for life on Earth : Visions of future systems and how to get there

Formalised knowledge systems, including universities and research institutes, are important for contemporary societies. They are, however, also arguably failing humanity when their impact is measured against the level of progress being made in stimulating the societal changes needed to address challenges like climate change. In this research we used a novel futures-oriented and participatory approach that asked what future envisioned knowledge systems might need to look like and how we might get there. Findings suggest that envisioned future systems will need to be much more collaborative, open, diverse, egalitarian, and able to work with values and systemic issues. They will also need to go beyond producing knowledge about our world to generating wisdom about how to act within it. To get to envisioned systems we will need to rapidly scale methodological innovations, connect innovators, and creatively accelerate learning about working with intractable challenges. We will also need to create new funding schemes, a global knowledge commons, and challenge deeply held assumptions. To genuinely be a creative force in supporting longevity of human and non-human life on our planet, the shift in knowledge systems will probably need to be at the scale of the enlightenment and speed of the scientific and technological revolution accompanying the second World War. This will require bold and strategic action from governments, scientists, civic society and sustained transformational intent.Peer reviewe