2,858 research outputs found
Diquat Derivatives: Highly Active, Two-Dimensional Nonlinear Optical Chromophores with Potential Redox Switchability
In this article, we present a detailed study of structureâactivity relationships in diquaternized 2,2â˛-bipyridyl (diquat) derivatives. Sixteen new chromophores have been synthesized, with variations in the amino electron donor substituents, Ď-conjugated bridge, and alkyl diquaternizing unit. Our aim is to combine very large, two-dimensional (2D) quadratic nonlinear optical (NLO) responses with reversible redox chemistry. The chromophores have been characterized as their PF_6^â salts by using various techniques including electronic absorption spectroscopy and cyclic voltammetry. Their visible absorption spectra are dominated by intense Ď â Ď^* intramolecular charge-transfer (ICT) bands, and all show two reversible diquat-based reductions. First hyperpolarizabilities β have been measured by using hyper-Rayleigh scattering with an 800 nm laser, and Stark spectroscopy of the ICT bands affords estimated static first hyperpolarizabilities β_0. The directly and indirectly derived β values are large and increase with the extent of Ď-conjugation and electron donor strength. Extending the quaternizing alkyl linkage always increases the ICT energy and decreases the E_(1/2) values for diquat reduction, but a compensating increase in the ICT intensity prevents significant decreases in Stark-based β_0 responses. Nine single-crystal X-ray structures have also been obtained. Time-dependent density functional theory clarifies the molecular electronic/optical properties, and finite field calculations agree with polarized HRS data in that the NLO responses of the disubstituted species are dominated by âoff-diagonalâ β_(zyy) components. The most significant findings of these studies are: (i) β_0 values as much as 6 times that of the chromophore in the technologically important material (E)-4â˛-(dimethylamino)-N-methyl-4-stilbazolium tosylate; (ii) reversible electrochemistry that offers potential for redox-switching of optical properties over multiple states; (iii) strongly 2D NLO responses that may be exploited for novel practical applications; (iv) a new polar material, suitable for bulk NLO behavior
LensPerfect: Gravitational Lens Massmap Reconstructions Yielding Exact Reproduction of All Multiple Images
We present a new approach to gravitational lens massmap reconstruction. Our
massmap solutions perfectly reproduce the positions, fluxes, and shears of all
multiple images. And each massmap accurately recovers the underlying mass
distribution to a resolution limited by the number of multiple images detected.
We demonstrate our technique given a mock galaxy cluster similar to Abell 1689
which gravitationally lenses 19 mock background galaxies to produce 93 multiple
images. We also explore cases in which far fewer multiple images are observed,
such as four multiple images of a single galaxy. Massmap solutions are never
unique, and our method makes it possible to explore an extremely flexible range
of physical (and unphysical) solutions, all of which perfectly reproduce the
data given. Each reconfiguration of the source galaxies produces a new massmap
solution. An optimization routine is provided to find those source positions
(and redshifts, within uncertainties) which produce the "most physical" massmap
solution, according to a new figure of merit developed here. Our method imposes
no assumptions about the slope of the radial profile nor mass following light.
But unlike "non-parametric" grid-based methods, the number of free parameters
we solve for is only as many as the number of observable constraints (or
slightly greater if fluxes are constrained). For each set of source positions
and redshifts, massmap solutions are obtained "instantly" via direct matrix
inversion by smoothly interpolating the deflection field using a recently
developed mathematical technique. Our LensPerfect software is straightforward
and easy to use and is made publicly available via our website.Comment: 17 pages, 18 figures, accepted by ApJ. Software and full-color
version of paper available at http://www.its.caltech.edu/~coe/LensPerfect
Evolution of Linear Absorption and Nonlinear Optical Properties in V-Shaped Ruthenium(II)-Based Chromophores
In this article, we describe a series of complexes with electron-rich cis-{Ru^(II)(NH_3)_4}^(2+) centers coordinated to two pyridyl ligands bearing N-methyl/arylpyridinium electron-acceptor groups. These V-shaped dipolar species are new, extended members of a class of chromophores first reported by us (Coe, B. J. et al. J. Am. Chem. Soc. 2005, 127, 4845â4859). They have been isolated as their PF_6â salts and characterized by using various techniques including ^1H NMR and electronic absorption spectroscopies and cyclic voltammetry. Reversible Ru^(III/II) waves show that the new complexes are potentially redox-switchable chromophores. Single crystal X-ray structures have been obtained for four complex salts; three of these crystallize noncentrosymmetrically, but with the individual molecular dipoles aligned largely antiparallel. Very large molecular first hyperpolarizabilities β have been determined by using hyper-Rayleigh scattering (HRS) with an 800 nm laser and also via Stark (electroabsorption) spectroscopic studies on the intense, visible d â Ď^* metal-to-ligand charge-transfer (MLCT) and Ď â Ď^* intraligand charge-transfer (ILCT) bands. The latter measurements afford total nonresonant β_0 responses as high as ca. 600 Ă 10^(â30) esu. These pseudo-C_(2v) chromophores show two substantial components of the β tensor, β_(zzz) and β_(zyy), although the relative significance of these varies with the physical method applied. According to HRS, β_(zzz) dominates in all cases, whereas the Stark analyses indicate that β_(zyy) is dominant in the shorter chromophores, but β_(zzz) and β_(zyy) are similar for the extended species. In contrast, finite field calculations predict that β_(zyy) is always the major component. Time-dependent density functional theory calculations predict increasing ILCT character for the nominally MLCT transitions and accompanying blue-shifts of the visible absorptions, as the ligand Ď-systems are extended. Such unusual behavior has also been observed with related 1D complexes (Coe, B. J. et al. J. Am. Chem. Soc. 2004, 126, 3880â3891)
Primary healthcare policy and vision for community pharmacy and pharmacists in the united states
Š 2020, Grupo de Investigacion en Atencion Farmaceutica. All rights reserved. The United States (US) has a complex healthcare system with a mix of public, private, nonprofit, and for-profit insurers, healthcare institutions and organizations, and providers. Unlike other developed countries, there is not a single payer healthcare system or a national pharmaceutical benefits scheme/plan. Despite spending over USD 10,000 per capita in healthcare, the US is among the worst performers compared to other developed countries in outcomes including life expectancy at birth, infant mortality, safety during childbirth, and unmanaged chronic conditions (e.g., asthma, diabetes). Primary care is delivered by physicians and advanced practice providers (i.e., nurse practitioners and physician assistants) in a variety of settings including large health systems, federally qualified health centers or free clinics that provide care to the underserved, or specific facilities for veterans or American Indian and Alaska native peoples. Since 2010, primary care delivery has shifted toward providing patient-centered, coordinated, comprehensive care focused on providing proactive, rather than reactive, population health management, and on the quality, versus volume, of care. Community pharmacy comprises a mix of independently owned, chain, supermarket and mass merchant pharmacies. Community pharmacies provide services such as immunizations, medication therapy management, medication packaging, medication synchronization, point-of-care testing and, in specific states where legislation has been passed, hormonal contraception, opioid reversal agents, and smoking cessation services. There has been criticism regarding the lack of standard terminology for services such as medication synchronization and medication therapy management, their components and how they should be provided, which hampers comparability across studies. One of the main challenges for pharmacists in the US is the lack of provider status at the federal level. This means that pharmacists are not allowed to use existing fee-for-service health insurance billing codes to receive reimbursement for non-dispensing services. In addition, despite there being regulatory infrastructure in multiple states, the extent of service implementation is either low or unknown. Research found that pharmacists face numerous barriers when providing some of these services. State fragmentation and the lack of a single pharmacy organization and vision for the profession are additional challenges
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Femininity, Childhood and the Non-Making of a Sporting Celebrity: The Beth Tweddle Case
Gymnastics is regularly classified as a feminine-appropriate sport, embodying grace and elegance and is an Olympic sport which has regularly produced female sporting celebrities. Beth Tweddle is the most successful British gymnast of all time and the first to achieve international success, culminating in a medal at London 2012, yet she has received relatively little media coverage and few corporate endorsements. Employing a 'negative case' methodology, this athlete's relative lack of celebrity is investigated. The article suggests that it can be explained by (a) contradictions underpinning the gender-designation of gymnastics, and (b) the social invisibility of a core audience for the sport: young girls. An implication is that the achievement of celebrity within 'feminine' sport may be increasingly unattainable, especially for female athletes. The article uses mixed methods, including primary analysis of print and social media and secondary analysis of a national survey of young people in the UK
Systematic review of interventions for reducing stigma experienced by children with disabilities and their families in low- and middle-income countries: state of the evidence.
OBJECTIVES: To identify and assess the evidence for interventions to reduce stigma experienced by children with disabilities and their families in low- and middle-income settings. METHODS: Systematic review of seven databases (MEDLINE, EMBASE, Global Health, PsycINFO, Social Policy and Practice, CINAHL, IBSS) for studies of interventions that aimed to reduce stigma for children with disabilities published from January 2000 to April 2018. Data were extracted on study population, study design, intervention level(s) and target group, and type(s) of stigma addressed. A narrative approach was used to synthesise the results. RESULTS: Twenty studies were included. The majority (65%) of interventions targeted enacted stigma (negative attitudes) and the most common intervention approach was education/training (63%). Over half (54%) of interventions were delivered at the organisational/institutional level, and only four studies targeted more than one social level. The most common disability targeted was epilepsy (50%) followed by intellectual impairment (20%). The majority of studies (n = 18/20, 90%) found a reduction in a component of stigma; however, most (90%) studies had a high risk of bias. CONCLUSIONS: This review highlights the lack of quality evidence on effective stigma-reduction strategies for children with disabilities. Validation and consistent use of contextually relevant scales to measure stigma may advance this field of research. Studies that involve people with disabilities in the design and implementation of these strategies are needed
The Bright End of the z~9 and z~10 UV Luminosity Functions using all five CANDELS Fields
The deep, wide-area (~800-900 arcmin**2) near-infrared/WFC3/IR + Spitzer/IRAC
observations over the CANDELS fields have been a remarkable resource for
constraining the bright end of high redshift UV luminosity functions (LFs).
However, the lack of HST 1.05-micron observations over the CANDELS fields has
made it difficult to identify z~9-10 sources robustly, since such data are
needed to confirm the presence of an abrupt Lyman break at 1.2 microns. We
report here on the successful identification of many such z~9-10 sources from a
new HST program (z9-CANDELS) that targets the highest-probability z~9-10 galaxy
candidates with observations at 1.05 microns, to search for a robust
Lyman-break at 1.2 microns. The potential z~9-10 candidates are preselected
from the full HST, Spitzer/IRAC S-CANDELS observations, and the
deepest-available ground-based optical+near-infrared observations. We
identified 15 credible z~9-10 galaxies over the CANDELS fields. Nine of these
galaxies lie at z~9 and 5 are new identifications. Our targeted follow-up
strategy has proven to be very efficient in making use of scarce HST time to
secure a reliable sample of z~9-10 galaxies. Through extensive simulations, we
replicate the selection process for our sample (both the preselection and
follow-up) and use it to improve current estimates for the volume density of
bright z~9 and z~10 galaxies. The volume densities we find are 5(-2)(+3)x and
8(-3)(+9)x lower, respectively, than found at z~8. When compared with the
best-fit evolution (i.e., dlog_{10} rho(UV)/dz=-0.29+/-0.02) in the UV
luminosities densities from z~8 to z~4 integrated to 0.3L*(z=3) (-20 mag),
these luminosity densities are 2.6(-0.9)(+1.5)x and 2.2(-1.1)(+2.0)x lower,
respectively, than the extrapolated trends. Our new results are broadly
consistent with the "accelerated evolution" scenario at z>8, as seen in many
theoretical models.Comment: 23 pages, 15 figures, 7 tables, updated to match the version in
press, including some minor textual corrections identified at the proof stag
Beyond 'Global Production Networks': Australian Fashion Week's Trans-Sectoral Synergies
When studies of industrial organisation are informed by commodity chain, actor network, or global production network theories and focus on tracing commodity flows, social networks, or a combination of the two, they can easily overlook the less routine trans-sectoral
associations that are crucial to the creation and realisation of value. This paper shifts attention to
identifying the sites at which diverse specialisations meet to concentrate and amplify mutually reinforcing circuits of value. These valorisation processes are demonstrated in the case of Australian Fashion Week, an event in which multiple interests converge to synchronize different expressions
of fashion ideas, actively construct fashion markets and enhance the value of a diverse range of fashionable commodities. Conceptualising these interconnected industries as components of a trans-sectoral fashion complex has implications for understanding regional development, world cities, production location, and the manner in which production systems âtouch downâ in different
places
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