Origin of spectral broadening in pi-conjugated amorphous semiconductors

We present a study of the picosecond fluorescence dynamics of pi-conjugated semiconducting organic dendrimers in the solid state. By varying the degree of branching within the dendrons, referred to as the dendrimer generation, a control of intermolecular spacing of the emissive core and therefore of the lattice parameter for Forster-type energy transfer is achieved. This allows a distinction between spectral diffusion and excimer formation as the two main sources of spectral broadening in organic semiconductors. Whereas Forster-type dispersive spectral relaxation is independent of temperature but strongly dependent on the interchromophore distance, excimer formation is also strongly thermally activated due to temperature-dependent conformational changes and the influence of thermally activated dynamic disorder. The rapid spectral diffusion allows a determination of the excimer rise in the emission, which is shown to have a profound impact on the steady state luminescence properties of dendrimer films. We show that the dendrimer generation not only allows a microscopic control of intermolecular interactions but also a direct control of the rate of spectral diffusion. Implications for the design of novel materials for optoelectronic devices are discussed

Mass Producing Food Traditions for West Africans Abroad

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65677/1/aa.2007.109.4.616.pd

Doing calories: the practices of dieting using calorie counting app MyFitnessPal

The existing literature on fatness has critically discussed meanings and morals associated with body weight and explored people’s experiences of weight loss attempts. However, little attention has been paid to the practices of dieting – how it is ‘done’. Based on an interview study involving 31 participants, who shared their self-tracking experience of using the MyFitnessPal calorie counting app, we focus on the practices of ‘doing’ calories. First, we discuss the practices of temporality of logging food, showing that the use of MyFitnessPal not only has to be fitted into daily routines but can also transform them. Then, we look at the practices of precision or users’ various ways of turning the ‘messiness’ of food into precise numbers. Lastly, we explore users’ practices of adjustments – their attitudes to adherence to their daily calorie goal and ways of dealing with going above it. Based on our findings we suggest calorie counting is not a straightforward data collection, but one that involves constant practical strategies and negotiations, and can both influence and be influenced by other everyday practices

Statistical Determination of Bulk Flow Motions

We present here a new parameterization for the bulk motions of galaxies and clusters (in the linear regime) that can be measured statistically from the shape and amplitude of the two-dimensional two-point correlation function. We further propose the one-dimensional velocity dispersion (v_p) of the bulk flow as a complementary measure of redshift-space distortions, which is model-independent and not dependent on the normalisation method. As a demonstration, we have applied our new methodology to the C4 cluster catalogue constructed from Data Release Three (DR3) of the Sloan Digital Sky Survey. We find v_p=270^{+433}km/s (also consistent with v_p=0) for this cluster sample (at z=0.1), which is in agreement with that predicted for a WMAP5-normalised LCDM model (i.e., v_p(LCDM=203km/s). This measurement does not lend support to recent claims of excessive bulk motions (\simeq1000 km/s) which appear in conflict with LCDM, although our large statistical error cannot rule them out. From the measured coherent evolution of v_p, we develop a technique to re-construct the perturbed potential, as well as estimating the unbiased matter density fluctuations and scale--independent bias.Comment: 8 pages, 5 figure

The Sloan Digital Sky Survey Quasar Lens Search. III. Constraints on Dark Energy from the Third Data Release Quasar Lens Catalog

We present cosmological results from the statistics of lensed quasars in the Sloan Digital Sky Survey (SDSS) Quasar Lens Search. By taking proper account of the selection function, we compute the expected number of quasars lensed by early-type galaxies and their image separation distribution assuming a flat universe, which is then compared with 7 lenses found in the SDSS Data Release 3 to derive constraints on dark energy under strictly controlled criteria. For a cosmological constant model (w=-1) we obtain \Omega_\Lambda=0.74^{+0.11}_{-0.15}(stat.)^{+0.13}_{-0.06}(syst.). Allowing w to be a free parameter we find \Omega_M=0.26^{+0.07}_{-0.06}(stat.)^{+0.03}_{-0.05}(syst.) and w=-1.1\pm0.6(stat.)^{+0.3}_{-0.5}(syst.) when combined with the constraint from the measurement of baryon acoustic oscillations in the SDSS luminous red galaxy sample. Our results are in good agreement with earlier lensing constraints obtained using radio lenses, and provide additional confirmation of the presence of dark energy consistent with a cosmological constant, derived independently of type Ia supernovae.Comment: 9 pages, 3 figures, 2 tables, accepted for publication in A

Clinical prioritisation questions: A novel assessment tool to encourage tolerance of uncertainty?

Uncertainty is a common and increasingly acknowledged problem in clinical practice. Current single best answer (SBA) style assessments test areas where there is one correct answer, and as the approach to assessment impacts on the approach to learning, these exams may poorly prepare our future doctors to handle uncertainty. We therefore, need to modify our approach to assessment to emphasize reasoning and introduce the possibility of more than one ‘correct’ answer. We have developed clinical prioritization questions (CPQs), a novel formative assessment tool in which students prioritize possible responses in order of likelihood. This assessment format was piloted with a group of medical students and evaluated in comparison with the more traditional SBA question format in a team-based learning setting. Students reported that they felt ongoing use would help improve their tolerance of uncertainty (p < 0.01). Furthermore, over 80% of students felt that CPQs were more reflective of real-life clinical practice. Group based discussions were significantly longer when answering CPQs (p < 0.01), suggesting they may promote richer discourse. CPQs may have a role in formative assessment to help equip students with the skills to cope with ambiguity and strengthen clinical reasoning and decision-making. Institutions may find them more practical to implement compared with other clinical reasoning assessment tools

The Rate of Type Ia Supernovae at z~0.2 from SDSS-I Overlapping Fields

In the course of the Sloan Digital Sky Survey (SDSS-I), a large fraction of the surveyed area was observed more than once due to field tiling overlap, usually at different epochs. We utilize some of these data to perform a supernova (SN) survey at a mean redshift of z=0.2. Our archival search, in ~ 5% of the SDSS-I overlap area, produces 29 SN candidates clearly associated with host galaxies. Using the Bayesian photometric classification algorithm of Poznanski et al., and correcting for classification bias, we find 17 of the 29 candidates are likely Type Ia SNe. Accounting for the detection efficiency of the survey and for host extinction, this implies a Type Ia SN rate of R=14.0+(2.5,1.4}-(2.5,1.1}+/-2.5 10^-14 h(70)^2 yr^-1 L_sun^-1, where the errors are Poisson error, systematic detection efficiency error, and systematic classification error, respectively. The volumetric rate is R=1.89+(0.42,0.18)-(0.34,0.15)+/-0.42 10^-5 yr^-1 h(70)^3 Mpc^-3. Our measurement is consistent with other rate measurements at low redshift. An order of magnitude increase in the number of SNe is possible by analyzing the full SDSS-I database.Comment: 11 pages, 7 figures, Accepted by MNRA

Compatibility and combination of world W -boson mass measurements

The compatibility of W-boson mass measurements performed by the ATLAS, LHCb, CDF, and D0 experiments is studied using a coherent framework with theory uncertainty correlations. The measurements are combined using a number of recent sets of parton distribution functions (PDF), and are further combined with the average value of measurements from the Large Electron–Positron collider. The considered PDF sets generally have a low compatibility with a suite of global rapidity-sensitive Drell–Yan measurements. The most compatible set is CT18 due to its larger uncertainties. A combination of all mW measurements yields a value of mW=80, 394.6±11.5 MeV with the CT18 set, but has a probability of compatibility of 0.5% and is therefore disfavoured. Combinations are performed removing each measurement individually, and a 91% probability of compatibility is obtained when the CDF measurement is removed. The corresponding value of the W boson mass is 80, 369.2±13.3 MeV, which differs by 3.6σ from the CDF value determined using the same PDF set

Mechanism of injury and special considerations as predictive of serious injury: A systematic review.

Objectives: The Centers for Disease Control and Prevention\u27s field triage guidelines (FTG) are routinely used by emergency medical services personnel for triaging injured patients. The most recent (2011) FTG contains physiologic, anatomic, mechanism, and special consideration steps. Our objective was to systematically review the criteria in the mechanism and special consideration steps that might be predictive of serious injury or need for a trauma center. Methods: We conducted a systematic review of the predictive utility of mechanism and special consideration criteria for predicting serious injury. A research librarian searched in Ovid Medline, EMBASE, and the Cochrane databases for studies published between January 2011 and February 2021. Eligible studies were identified using a priori inclusion and exclusion criteria. Studies were excluded if they lacked an outcome for serious injury, such as measures of resource use, injury severity scores, mortality, or composite measures using a combination of outcomes. Given the heterogeneity in populations, measures, and outcomes, results were synthesized qualitatively focusing on positive likelihood ratios (LR+) whenever these could be calculated from presented data or adjusted odds ratios (aOR

Fertility and digital technology: narratives of using smartphone app ‘Natural Cycles’ while trying to conceive

Fertility awareness apps, which help to identify the 'fertile window' when conception is most likely, have been hailed as 'revolutionising' women's reproductive health. Despite rapidly growing popularity, little research has explored how people use these apps when trying to conceive and what these apps mean to them. We draw on in-depth, qualitative interviews, adopting a critical digital health studies lens (a sub-field of science and technology studies), to explore the experiences of cisgender women and partners with one such app, Natural Cycles, in the context of their daily lives. We found that many women valued the technology as a 'natural', inobtrusive alternative to biomedical intervention, and a means of controlling and knowing their bodies, amid a dearth of fertility-related education and care. Yet this technology also intervened materially and affectively into the spaces of their lives and relationships and privileged disembodied metrics (temperature) over embodied knowledge. Meanwhile, app language, advertising and cost have contributed to characterising 'typical' users as white, heterosexual, affluent, cisgender women without disabilities. In the context of neoliberal shifts towards bodily self-tracking, technologies appealing as novel, liberating and 'natural' to individuals who can access them may nevertheless reproduce highly gendered reproductive responsibilities, anxieties and broader health and social inequalities