8,555 research outputs found
A New Polymorph of <em>tert</em>-Butyl (2-Aminophenyl)Carbamate
\ua9 The Author(s) 2024.A new polymorph of tert-butyl (2-aminophenyl)carbamate was identified using single crystal X-ray diffraction. The compound crystallised in the centrosymmetric, monoclinic space group P21/n with an asymmetric unit comprising two crystallographically-independent molecules (Zʹ = 2). This new structure was compared to that of the known polymorph with the differences between the two being attributed to a combination of space group symmetry, conformational variation, hydrogen bonding network dimensionality and crystal packing
DRD4 polymorphism moderates the effect of alcohol consumption on social bonding
Development of interpersonal relationships is a fundamental human motivation, and behaviors facilitating social bonding are prized. Some individuals experience enhanced reward from alcohol in social contexts and may be at heightened risk for developing and maintaining problematic drinking. We employed a 3 (group beverage condition) ×2 (genotype) design (N = 422) to test the moderating influence of the dopamine D4 receptor gene (DRD4 VNTR) polymorphism on the effects of alcohol on social bonding. A significant gene x environment interaction showed that carriers of at least one copy of the 7-repeat allele reported higher social bonding in the alcohol, relative to placebo or control conditions, whereas alcohol did not affect ratings of 7-absent allele carriers. Carriers of the 7-repeat allele were especially sensitive to alcohol's effects on social bonding. These data converge with other recent gene-environment interaction findings implicating the DRD4 polymorphism in the development of alcohol use disorders, and results suggest a specific pathway by which social factors may increase risk for problematic drinking among 7-repeat carriers. More generally, our findings highlight the potential utility of employing transdisciplinary methods that integrate genetic methodologies, social psychology, and addiction theory to improve theories of alcohol use and abuse. © 2012 Creswell et al
Clinic visits and cervical cancer screening in Accra
Objective: To determine the factors that increase the chances of a woman in Accra having a Pap smear and whether women who have recently visited clinics have higher chances of having had Pap smears.Design: A cross-sectional studyMethods: A representative sample of women in Accra, Ghana was interviewed and the clinical and demographic factors influencing cervical cancer screening was assessed.Results: Out of 1193 women with complete data, only 25 (2.1%) had ever had a Pap smear performed though 171 (14.3%) had their last outpatient clinic visit for either a gynaecological consultation or a regular checkup. Simple logistic regression showed that a high educational level, high socioeconomic status and a history over the past month of postmenopausal or intermenstrual bleeding significantly increased the odds of ever having a pap smear. Neither monthly income nor lastclinic visit for a gynaecological consultation or regular check up increased the odds of having a pap smear. Multiple logistic regression showed that a high educational level and experiencing postmenopausal or intermenstrualbleeding were the most important determinants of ever having a Pap smear.Conclusion: While we wait for a national program for cervical cancer screening, there is a need for clinicians to put more individual effort into ensuring that asymptomatic women are screened for cervical cancer
Sexually transmitted infections and health seeking behaviour among Ghanaian women in Accra
The study was to measure the prevalence of sexually transmitted infection (STI) symptoms among women in Accra, Ghana, to identify characteristics that predispose to STI symptoms and to identify factors that influence health-seeking behaviour of women with STI symptoms. Data were collected by trained interviewers through questionnaire interviews of 3183 women. Data analysis was restricted to 1329 women with complete data. Only 19% of our study group had STI symptoms. Only 35% of the women with STI symptoms received care. Having high wealth index, being older and having no history of condom use were protective factors for experiencing STI symptoms. Seeking care was associated with increased by high wealth index and the presence of an offensive vaginal odour. Income level on its own did not affect health seeking behavior. Wealth index is the most significant determinant of a woman having STI symptoms and seeking care in Accra (Afr J Reprod Health 2008; 12[3]:151-158)
Socio-cultural challenges in collections digital infrastructures
Purpose
This paper aims to explore the accelerations and constraints libraries, archives, museums and heritage organisations (“collections-holding organisations”) face in their role as collection data providers for digital infrastructures. To date, digital infrastructures operate within the cultural heritage domain typically as data aggregation platforms, such as Europeana or Art UK.
Design/methodology/approach
Semi-structured interviews with 18 individuals in 8 UK collections-holding organisations and 2 international aggregators.
Findings
Discussions about digital infrastructure development often lay great emphasis on questions and problems that are technical and legal in nature. As important as technical and legal matters are, more latent, yet potent challenges exist too. Though less discussed in the literature, collections-holding organisations' capacity to participate in digital infrastructures is dependent on a complex interplay of funding allocation across the sector, divergent traditions of collection description and disciplinaries’ idiosyncrasies. Accordingly, we call for better social-cultural and trans-sectoral (collections-holding organisations, universities and technological providers) understandings of collection data infrastructure development.
Research limitations/implications
The authors recommend developing more understanding of the social-cultural aspects (e.g. disciplinary conventions) and their impact on collection data dissemination. More studies on the impact and opportunities of unified collections for different audiences and collections-holding organisations themselves are required too.
Practical implications
Sustainable financial investment across the heritage sector is required to address the discrepancies between different organisation types in their capacity to deliver collection data. Smaller organisations play a vital role in diversifying the (digital) historical canon, but they often struggle to digitise collections and bring catalogues online in the first place. In addition, investment in existing infrastructures for collection data dissemination and unification is necessary, instead of creating new platforms, with various levels of uptake and longevity. Ongoing investments in collections curation and high-quality cataloguing are prerequisites for a sustainable heritage sector and collection data infrastructures. Investments in the sustainability of infrastructures are not a replacement for research and vice versa.
Social implications
The authors recommend establishing networks where collections-holding organisations, technology providers and users can communicate their experiences and needs in an ongoing way and influence policy.
Originality/value
To date, the research focus on developing collection data infrastructures has tended to be on the drive to adopt specific technological solutions and copyright licensing practices. This paper offers a critical and holistic analysis of the dispersed experience of collections-holding organisations in their role as data providers for digital infrastructures. The paper contributes to the emerging understanding of the latent factors that make infrastructural endeavours in the heritage sector complex undertakings
Density compensated diodes for small field dosimetry: Comprehensive testing and implications for design
Purpose. In small megavoltage photon fields, the accuracies of an unmodified PTW 60017-type diode dosimeter and six diodes modified by adding airgaps of thickness 0.6-1.6 mm and diameter 3.6 mm have been comprehensively characterized experimentally and computationally. The optimally thick airgap for density compensation was determined, and detectors were micro-CT imaged to investigate differences between experimentally measured radiation responses and those predicted computationally. Methods. Detectors were tested on- and off-axis, at 5 and 15 cm depths in 6 and 15 MV fields ≥ 0.5 0.5 cm2. Computational studies were carried out using the EGSnrc/BEAMnrc Monte Carlo radiation transport code. Experimentally, radiation was delivered using a Varian TrueBeam linac and doses absorbed by water were measured using Gafchromic EBT3 film and ionization chambers, and compared with diode readings. Detector response was characterized via the formalism, choosing a 4 4 cm2 reference field. Results. For the unmodified 60017 diode, the maximum error in small field doses obtained from diode readings uncorrected by factors was determined as 11.9% computationally at +0.25 mm off-axis and 5 cm depth in a 15 MV 0.5 0.5 cm2 field, and 11.7% experimentally at -0.30 mm off-axis and 5 cm depth in the same field. A detector modified to include a 1.6 mm thick airgap performed best, with maximum computationally and experimentally determined errors of 2.2% and 4.1%. The 1.6 mm airgap deepened the modified dosimeter's effective point of measurement by 0.5 mm. For some detectors significant differences existed between responses in small fields determined computationally and experimentally, micro-CT imaging indicating that these differences were due to within-tolerance variations in the thickness of an epoxy resin layer. Conclusions. The dosimetric performance of a 60017 diode detector was comprehensively improved throughout 6 and 15 MV small photon fields via density compensation. For this approach to work well with good detector-to-detector reproducibility, tolerances on dense component dimensions should be reduced to limit associated variations of response in small fields, or these components should be modified to have more water-like densities
Analytical and numerical analyses of the micromechanics of soft fibrous connective tissues
State of the art research and treatment of biological tissues require
accurate and efficient methods for describing their mechanical properties.
Indeed, micromechanics motivated approaches provide a systematic method for
elevating relevant data from the microscopic level to the macroscopic one. In
this work the mechanical responses of hyperelastic tissues with one and two
families of collagen fibers are analyzed by application of a new variational
estimate accounting for their histology and the behaviors of their
constituents. The resulting, close form expressions, are used to determine the
overall response of the wall of a healthy human coronary artery. To demonstrate
the accuracy of the proposed method these predictions are compared with
corresponding 3-D finite element simulations of a periodic unit cell of the
tissue with two families of fibers. Throughout, the analytical predictions for
the highly nonlinear and anisotropic tissue are in agreement with the numerical
simulations
Associations between reliable changes in depression and changes in BMI, total body fatness and visceral adiposity during a 12-month weight loss trial.
We investigated associations between changes in depression and body composition over a 12-month weight loss trial. Of the 298 adults (BMI > 27 m/kg2), 219 with complete depression and body composition data were included. A 10-item Center for Epidemiologic Studies Depression Scale measured depression; dual-energy X-ray absorptiometry measured body composition. Multinomial logistic regression predicted reliable changes in depression by BMI, body fat (BF) and visceral adiposity (VAT). Multiplicative interaction terms tested modification by sex and ethnicity. Participants with increases in body composition were less likely to experience improvements in depression (BMI: RRR = 0.79 (0.68-0.91), p < 0.01; BF: RRR = 0.97 (0.94 - 0.99), p = 0.01; VAT: RRR = 0.99 (0.98-1.00), p = 0.02), but not worsening of depression (BMI: RRR = 1.29 (0.96-1.73), p = 0.10; BF: RRR = 1.04 (0.99-1.09), p = 0.15; VAT: RRR = 1.01 (1.00-1.03), p = 0.18). Sex and ethnicity interaction terms were not significant. However, the relationship was only significant among females, among non-Latinos for BMI and BF, and among Latinos for VAT. Our study supports the association between depression and obesity and highlights the need for longitudinal studies investigating VAT and depression in diverse ethnic groups
Untangling free carrier and exciton dynamics in layered hybrid perovskites using ultrafast optical and terahertz spectroscopy
\ua9 2024 The Author(s). Published by IOP Publishing Ltd.Layered hybrid perovskites (LPKs) are promising as alternatives or additives to 3D metal halide perovskites for optoelectronic applications including photovoltaic cells, LEDs and lasers due to their increased stability. However, high exciton binding energies in these materials mean that excitons are the majority species under the operating conditions of many devices. Although the efficiency of devices that incorporate LPKs has been increasing, much is still unknown about the interplay of excitons and free charge-carriers in these materials, which is vital information for understanding how optoelectronic properties dictate device efficiency. In this work, we employ optical pump/THz probe spectroscopy (OPTP) and visible transient absorption spectroscopy (TAS) to analyse the optoelectronic properties and charge-carrier dynamics of phenylethylammonium lead iodide (PEA)2PbI4. By combining these techniques, we are able to disentangle the contributions from excitons and free charge-carriers. We observe fast cooling of free charge-carriers and exciton formation on a timescale of ∼400 fs followed by slower bimolecular recombination of residual free charge-carriers with a rate constant k 2 ∼ 109 cm3s−1. Excitons recombine via two monomolecular processes with lifetimes t 1 ∼ 11 ps and t2 ∼ 83 ps. Furthermore, we detect signatures of exciton-phonon coupling in the transient absorption kinetic traces. These findings provide new insight into the interplay between free charge-carriers and excitons as well as a possible mechanism to further understand the charge-carrier dynamics in LPKs
- …