2,174 research outputs found

    Primary and secondary dissociation pathways in the ultraviolet photolysis of Cl_2O

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    The photodissociation of dichlorine monoxide (Cl_2O) at 308, 248, and 193 nm was studied by photofragment translational energy spectroscopy. The primary channel upon excitation at 308 and 248 nm was Cl–O bond fission with production of ClO+Cl. A fraction of the ClO photoproducts also underwent spontaneous secondary dissociation at 248 nm. The center-of-mass translational energy distribution for the ClO+Cl channel at 248 nm appeared to be bimodal with a high energy component that was similar in shape to the 308 nm distribution and a second, low energy component with a maximum close to the threshold for the 2Cl+O(3P) channel. Observation of a bimodal distribution suggests that two pathways with different dissociation dynamics lead to ClO+Cl products. The high product internal energy of the second component raises the possibility that ClO is formed in a previously unobserved spin-excited state a 4∑−. Following excitation at 193 nm, a concerted dissociation pathway leading to Cl_2+O was observed in addition to primary Cl–O bond breakage. In both processes, most of the diatomic photofragments were formed with sufficient internal energy that they spontaneously dissociated. The time-of-flight distributions of the Cl_2+O products suggest that these fragments are formed in two different channels Cl_2(3II)+O(3P) and Cl_2(X1∑)+O(1D)

    Patient hopes for diagnostic genomic sequencing: roles of uncertainty and social status

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    For patients with unexplained or undiagnosed conditions, genomic sequencing offers the hope of resolving unanswered questions. With the growth of clinical genomic sequencing, understanding factors that shape patients' hope for information could have important implications for developing patient education guidelines. Based on the goal-directed theory of hope, we investigated illness uncertainty as a form of motivation and subjective social status as a form of perceived resources to predict the amount and kinds of information that adult patients (N=191) and parents of pediatric patients (N=79) hoped to receive from diagnostic sequencing results. Participants were part of a larger longitudinal study on clinical genomic sequencing, but the current study focuses on their hopes for diagnostic sequencing results. Hopes for information were assessed through close-ended and open-ended responses. Findings from mixed methods analyses indicated that although patients and parents hoped to learn multiple kinds of information from diagnostic sequencing results, their hopes appeared to be influenced by their illness uncertainty and perceptions of their social and economic resources. These findings suggest that patients' illness uncertainty and perceived resources could be useful avenues for discussing patient hopes and educating patients about strengths and limitations of genomic sequencing

    Cultural ecosystem services in protected areas: understanding bundles, trade-Offs, and synergies

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    The concept of ecosystem services (ES) provides a potentially useful tool for decision-making in natural area management. Provisioning and regulating ES often occur in "bundles" that are cohesive because of coprovisioning or codependence. We asked whether individual preferences for cultural benefits also define service bundles. Data from a large survey of visitor preferences (n = 3,131 respondents) from all 19 South African National Parks indicated five bundles of cultural ecosystem services: (1) "natural history," (2) "recreation," (3) "sense of place," (4) "safari experiences," and (5) "outdoor lifestyle." Tradeoffs and synergies between bundles of services depended on the ecosystem providing them and on alignment between demand for services and the supply of particular service bundles in specific ecosystems. Our results show that identifying demand for multiple services can both help us to understand why people visit and value protected areas, and better inform the management choices that influence service provision

    Assessment and practical science:identifying generalizable characteristics of written assessments that reward and incentivise effective practices in practical science lessons

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    High-stakes assessments prominently influence what is done in secondary school science lessons (‘washback’ effects). It is therefore important that assessments of knowledge and understanding gained from practical work are constructed to reward and incentivise effective practices in practical work. To do that, they must differentiate between pupils who have experienced practical work in different ways. This empirical, mixed-methods study identifies generalizable characteristics of written assessments that differentially reward pupils who experienced practical activities through hands-on work, teacher demonstration, video demonstration, or reading about the activity. Conclusions are drawn from 1486 post-intervention tests completed by pupils aged 14–15 in England, from lesson observations and teacher interviews. This study also identifies pedagogical practices that were more noticeable in practical work that was most rewarded by the written assessments: the work was teacher-guided; and pupils were encouraged to be active participants. Existing literature describes negative washback effects of high-stakes, written assessments that limit the use and effectiveness of practical work as a pedagogical tool. We describe ways in which written assessments could be constructed to better reward effective practices in practical work (practices that better support learning), with the intention of having positive washback effects on pedagogy by better incentivising these practices

    Methodology for reliable and reproducible cryopreservation of human cervical tissue

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    BACKGROUND: In order to conduct laboratory studies on donated cervical tissue at suitable times an effective and reliable cryopreservation protocol for cervical tissue is required. METHODS: An active freezing approach was devised utilising 10% dimethyl sulfoxide in foetal bovine serum as a cryoprotective agent with a cooling rate of 1 °C/min to -50 °C then 10 °C/min to -120 °C; a related thawing protocol was also optimised which would allow for the bio-banking of cervical tissue. Viability of freshly harvested cervical tissue was compared to frozen-thawed samples utilising colorimetric MTT assay. In parallel, fresh and freeze-thawed samples were cultured and tested on days 1, 7 and 14 to determine whether bio-banking had detrimental effects on tissue viability over time. RESULTS: Repeat testing revealed that tissue viability between fresh and freeze-thawed wasand freeze-thawed samples was comparable at all four time points (days 0, 1, 7 and 14) with no apparent reductions of viability, thus demonstrating this method of cryopreserving cervical tissue is reliable and reproducible, without detrimental effects on live tissue culture. We believe this methodology creates the opportunity for bio-banking donated cervical tissues, which aids improved experimental design and reduces time pressures and wastage

    The Wyoming Survey for H-alpha. I. Initial Results at z ~ 0.16 and 0.24

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    The Wyoming Survey for H-alpha, or WySH, is a large-area, ground-based, narrowband imaging survey for H-alpha-emitting galaxies over the latter half of the age of the Universe. The survey spans several square degrees in a set of fields of low Galactic cirrus emission. The observing program focuses on multiple dz~0.02 epochs from z~0.16 to z~0.81 down to a uniform (continuum+line) luminosity at each epoch of ~10^33 W uncorrected for extinction (3sigma for a 3" diameter aperture). First results are presented here for 98+208 galaxies observed over approximately 2 square degrees at redshifts z~0.16 and 0.24, including preliminary luminosity functions at these two epochs. These data clearly show an evolution with lookback time in the volume-averaged cosmic star formation rate. Integrals of Schechter fits to the extinction-corrected H-alpha luminosity functions indicate star formation rates per co-moving volume of 0.009 and 0.014 h_70 M_sun/yr/Mpc^3 at z~0.16 and 0.24, respectively. The formal uncertainties in the Schechter fits, based on this initial subset of the survey, correspond to uncertainties in the cosmic star formation rate density at the >~40% level; the tentative uncertainty due to cosmic variance is 25%, estimated from separately carrying out the analysis on data from the first two fields with substantial datasets.Comment: To appear in the Astronomical Journa

    Cosmological Consequences of Slow-Moving Bubbles in First-Order Phase Transitions

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    In cosmological first-order phase transitions, the progress of true-vacuum bubbles is expected to be significantly retarded by the interaction between the bubble wall and the hot plasma. We examine the evolution and collision of slow-moving true-vacuum bubbles. Our lattice simulations indicate that phase oscillations, predicted and observed in systems with a local symmetry and with a global symmetry where the bubbles move at speeds less than the speed of light, do not occur inside collisions of slow-moving local-symmetry bubbles. We observe almost instantaneous phase equilibration which would lead to a decrease in the expected initial defect density, or possibly prevent defects from forming at all. We illustrate our findings with an example of defect formation suppressed in slow-moving bubbles. Slow-moving bubble walls also prevent the formation of `extra defects', and in the presence of plasma conductivity may lead to an increase in the magnitude of any primordial magnetic field formed.Comment: 10 pages, 7 figures, replaced with typos corrected and reference added. To appear in Phys. Rev.

    Science Communication Demands a Critical Approach That Centers Inclusion, Equity, and Intersectionality

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    We live in an era of abundant scientific information, yet access to information and to opportunities for substantive public engagement with the processes and outcomes of science are still inequitably distributed. Even with increasing interest in science communication and public engagement with science, historically marginalized and minoritized individuals and communities are largely overlooked and undervalued in these efforts. To address this gap, this paper aims to define inclusive science communication and clarify and amplify the field. We present inclusive science communication as one path forward to redress the systemic problems of inequitable access to and engagement with STEMM (science, technology, engineering, mathematics, and medicine). We describe the first national Inclusive Science Communication (InclusiveSciComm) Symposium held in the U.S. Based on the experience of organizing the symposium, we discuss recommendations for other convenings to help build a community of practice for inclusive science communication. In both research and practice, we advocate for more experimentation to help make inclusive science communication the future of science communication writ large, in order to engage diverse publics in their multiple ways of knowing and expand a sense of belonging in STEMM
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