Publications

Microbial sensors for small molecules: Development of a mevalonate biosensor

Adolescent Sleep Barriers: Profiles within a Diverse Sample of Urban Youth

American Grandparents Providing Extensive Child Care to Their Grandchildren

Areas for future research, policy, and practice are highlighted, including the potential impact of welfare reform legislation on extensively caregiving grandparents.

The role of testosterone and estradiol in brain volume changes across adolescence: A longitudinal structural MRI study

Abstract It has been postulated that pubertal hormones may drive some neuroanatomical changes during adolescence, and may do so differently in girls and boys. Here, we use growth curve modeling to directly assess how sex hormones [testosterone (T) and estradiol (E 2 )] relate to changes in subcortical brain volumes utilizing a longitudinal design. 126 adolescents (63 girls), ages 10 to 14, were imaged and restudied ∼2 years later. We show, for the first time, that best‐fit growth models are distinctly different when using hormones as compared to a physical proxy of pubertal maturation (Tanner Stage) or age, to predict brain development. Like Tanner Stage, T and E 2 predicted white matter and right amygdala growth across adolescence in both sexes, independent of age. Tanner Stage also explained decreases in both gray matter and caudate volumes, whereas E 2 explained only gray matter decreases and T explained only caudate volume decreases. No pubertal measures were related to hippocampus development. Although specificity was seen, sex hormones had strikingly similar relationships with white matter, gray matter, right amygdala, and bilateral caudate volumes, with larger changes in brain volume seen at early pubertal maturation (as indexed by lower hormone levels), followed by less robust, or even reversals in growth, by late puberty. These novel longitudinal findings on the relationship between hormones and brain volume change represent crucial first steps toward understanding which aspects of puberty influence neurodevelopment. Hum Brain Mapp 35:5633–5645, 2014 . © 2014 Wiley Periodicals, Inc .

First National Survey Of ACOs Finds That Physicians Are Playing Strong Leadership And Ownership Roles

The extent to which physicians lead, own, and govern accountable care organizations (ACOs) is unknown. However, physicians' involvement in ACOs will influence how clinicians and patients perceive the ACO model, how effective these organizations are at improving quality and costs, and how future ACOs will be organized. From October 2012 to May 2013 we fielded the National Survey of Accountable Care Organizations, the first such survey of public and private ACOs. We found that 51 percent of ACOs were physician-led, with another 33 percent jointly led by physicians and hospitals. In 78 percent of ACOs, physicians constituted a majority of the governing board, and physicians owned 40 percent of ACOs. The broad reach of physician leadership has important implications for the future evolution of ACOs. It seems likely that the challenge of fundamentally changing care delivery as the country moves away from fee-for-service payment will not be accomplished without strong, effective leadership from physicians.

The Molecular Surface Science of Heterogeneous Catalysis: History and Perspective

Comunidades Carcerárias na América Latina: Desconcertando mundos prisionais no século XXI

Texto da contracapa: COMUNIDADES CARCERÁRIAS NA AMÉRICA LATINA - Desconcertando Mundos Prisionais no Século XXI oferece uma poderosa amostra representativa de pesquisa etnográfica voltada para os multifacetados problemas práticos e éticos do crescente e acelerado encarceramento massivo verificado n

When is scene recognition just texture recognition?

It remains unclear whether humans recognize scenes by using “diagnostic objects” or by using global attributes of the scene. Based on our work, we argue that not all scenes are created equal and that varying levels of information are needed for recognition at different category levels. We hypothesize that there is a time course to scene processing. Global scene information may be accessed early and can be used for superordinate-level categorization, but recognition of “diagnostic objects” takes longer and is necessary for basic-level categorization. EXPERIMENT ONE: Subjects were asked to divide grayscale images into multiple sub-groups based on global visual similarity, while ignoring the object and scene content of the image. We found that the resulting sub-groups could be categorized at the superordinate-level as natural or man-made scenes, but categorization beyond that level was not achieved. EXPERIMENT TWO: Subjects were shown grayscale images of scenes, followed by two basic-level category choices. The task was to select the category that best described the image. When subjects were allowed to view the images for 150ms, they demonstrated nearly perfect performance. When the viewing time was reduced to 30ms, subjects made more errors categorizing man-made scenes than natural scenes. The distribution of errors revealed a higher level of confusion among indoor scenes. EXPERIMENT THREE: A simple texture-based classifier was tested and compared to human performance at 30ms. The classifier made similar errors, but was outperformed overall. Based on this result, it is clear that subjects are using more than just global texture to do basic-level scene classification in 30ms. CONCLUSIONS: Global properties of a scene, such as texture and shape, may be instructive in the early, superordinate-level categorization of scenes. Basic-level categorization may require more time and more information, such as the processing of “diagnostic objects”.

Reproducibility of code behavior across different implementations for flux processing pipelines

The rotator—A new network component

This paper presents a new linear, reciprocal, active two-port network element called a rotator, of which there are three types: an R- rotator, an L-rotator, and a C-rotator. They have the unique property that whenever a nonlinear resistor, inductor, or capacitor is connected to one port of an R-, L-, or C-rotator, respectively, the resulting two-terminal network behaves as a new resistor, inductor, or capacitor whose characteristic curve is that of the original resistor, inductor, or capacitor, rotated by a prescribed angle about the origin. The rotator is realizable by either a π-network or a T-network of linear resistances, inductances, or capacitances. It can also be realized by a balanced lattice network of linear elements. Operational laboratory models are reported, and experimental data agree remarkably well with theoretical predictions. The sensitivity, power rating, and stability performances of rotators are considered in detail in this paper, and practical stability criteria are given. They are shown to be indispensable building blocks for realizing multivalued elements, and some potential applications are described.

CCDC 841919: Experimental Crystal Structure Determination

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Scanning Nanobeam Diffraction and Energy Dispersive Spectroscopy Characterization of a Model Mn-Promoted Co/Al₂O₃ Nanosphere Catalyst for Fischer–Tropsch Synthesis

Manganese oxide is an effective promoter for enhancing the activity and selectivity of cobalt-based Fischer-Tropsch synthesis (FTS) catalysts. Previous studies suggest that Co atoms located at the Co-MnO perimeter adsorb CO more strongly and undergo C-O bond cleavage more readily than CO adsorbed on Co sites, which leads to improved C5+ selectivity. Thus, direct characterization of the formation and structure of the active interface between Co nanoparticles and MnO is essential for a full understanding of the FTS promotion effect. Scanning transmission electron microscopic (STEM) methods are well-suited for direct characterization of nanoscale features through imaging, energy dispersive spectroscopy (EDS) elemental mapping, and spatially resolved electron diffraction, a technique known as scanning nanobeam diffraction. However, these techniques require that the catalytic nanoparticles are non-overlapping and well-defined, which is not typical for nanoparticles on porous metal oxide FTS supports. In the present study, we addressed these challenges by synthesizing catalysts composed of cobalt dispersed on nonporous alumina nanospheres (Co/ANS), which yielded isolated nanoparticles that are amenable to elemental and phase mapping by STEM-EDS and scanning nanobeam diffraction. Then, manganese oxide-promoted Co/ANS (Mn-Co/ANS) was characterized using these two techniques, which provided direct evidence for the transformation of a Co-Mn oxide spinel present in the as-prepared catalyst into closely associated Co3O4 and MnO2 nanoparticles in the passivated catalyst after its use for FTS.

Search for gravitational lenses in a large sample of highly luminous quasars and statistical determination of cosmological parameters

Results on gravitational lensing statistics applied to a sample of 469 highly luminous quasars are reported.

Aqueous corrosion problems in energy systems

Synthesis of Aryldifluoroamides by Copper‐Catalyzed Cross‐Coupling

Abstract A copper‐catalyzed coupling of aryl, heteroaryl, and vinyl iodides with α‐silyldifluoroamides is reported. The reaction forms α,α‐difluoro‐α‐aryl amides from electron‐rich, electron‐poor, and sterically hindered aryl iodides in high yield and tolerates a variety of functional groups. The aryldifluoroamide products can be transformed further to provide access to a diverse array of difluoroalkylarenes, including compounds of potential biological interest.

The carbon cycle under stress

An embedded interfacial network stabilizes inorganic CsPbI3 perovskite thin films

Abstract The black perovskite phase of CsPbI 3 is promising for optoelectronic applications; however, it is unstable under ambient conditions, transforming within minutes into an optically inactive yellow phase, a fact that has so far prevented its widespread adoption. Here we use coarse photolithography to embed a PbI 2 -based interfacial microstructure into otherwise-unstable CsPbI 3 perovskite thin films and devices. Films fitted with a tessellating microgrid are rendered resistant to moisture-triggered decay and exhibit enhanced long-term stability of the black phase (beyond 2.5 years in a dry environment), due to increasing the phase transition energy barrier and limiting the spread of potential yellow phase formation to structurally isolated domains of the grid. This stabilizing effect is readily achieved at the device level, where unencapsulated CsPbI 3 perovskite photodetectors display ambient-stable operation. These findings provide insights into the nature of phase destabilization in emerging CsPbI 3 perovskite devices and demonstrate an effective stabilization procedure which is entirely orthogonal to existing approaches.

On the Damage Tolerance of Bioinspired Gradient Composites with Nacre‐Like Architecture

The evolution of natural armor materials has led to gradient structures with specific architectures to achieve high damage tolerance, thus offering valuable inspiration for the design of man‐made materials. Here, bioinspired gradient composites with a nacre‐like brick‐and‐mortar architecture are fabricated by infiltrating a polymer phase into porous ceramic scaffolds with position‐specific ceramic content. These composites demonstrate an integrated structure with notable several‐fold variations in local hardness and modulus across the thickness. The asymmetric mechanical properties and toughening mechanisms of the composites are investigated and compared to those of uniform composites. Specifically, when loaded along the direction of decreasing stiffness – resembling the typical loading configuration of natural armors, the gradient composites exhibit superior damage tolerance compared to the opposite direction and a uniform composite with equivalent ceramic content. This is attributed to the decreased peak stress, broader stress distribution, and increased deformation capacity, along with enhanced toughening effects that impede crack growth through mechanisms of crack deflection, crack bridging by uncracked ligaments, together with their frictional pull‐out from crack surfaces. This study deepens the understanding of the damage tolerance of gradient materials and offers insights for the bioinspired design of highly damage‐tolerant materials.