5,761 research outputs found
GENIE observations of small scale astrophysical processes in star forming regions and quasars
The VLTI/GENIE configuration will operate using at least 4 of the VLTI
telescopes (and possibly with one or more of the AT telescopes in the future if
adaptive optics become available on them). GENIE effectively can be thought of
as a 'smart' coronagraph, enabling high dynamic range imaging to be achieved at
moderate spatial resolution, with high rejection of the emission of a central
bright point source. However, but this bright source rejection may only provide
a rather moderate image quality (due to the few baselines and transfer function
on the sky). Operated in this way, only limited image reconstruction is
possible since classical radio and millimeter wavelength interferometry
techniques are not directly applicable to the outputs of optical
interferometers because the absolute phases are generally not measured.
However, measurements of visibility and closure phase could lead to situations
where image reconstruction becomes possible. This paper addresses the issue of
whether there are areas outside of the exoplanet search where it might be able
to make a useful impact on astronomy.Comment: Proceedings of the Genie-Darwin Workshop - Hunting for Planet
An Ensemble Model of QSAR Tools for Regulatory Risk Assessment
Quantitative structure activity relationships (QSARs) are theoretical models that relate a quantitative measure of chemical structure to a physical property or a biological effect. QSAR predictions can be used for chemical risk assessment for protection of human and environmental health, which makes them interesting to regulators, especially in the absence of experimental data. For compatibility with regulatory use, QSAR models should be transparent, reproducible and optimized to minimize the number of false negatives. In silico QSAR tools are gaining wide acceptance as a faster alternative to otherwise time-consuming clinical and animal testing methods. However, different QSAR tools often make conflicting predictions for a given chemical and may also vary in their predictive performance across different chemical datasets. In a regulatory context, conflicting predictions raise interpretation, validation and adequacy concerns. To address these concerns, ensemble learning techniques in the machine learning paradigm can be used to integrate predictions from multiple tools. By leveraging various underlying QSAR algorithms and training datasets, the resulting consensus prediction should yield better overall predictive ability. We present a novel ensemble QSAR model using Bayesian classification. The model allows for varying a cut-off parameter that allows for a selection in the desirable trade-off between model sensitivity and specificity. The predictive performance of the ensemble model is compared with four in silico tools (Toxtree, Lazar, OECD Toolbox, and Danish QSAR) to predict carcinogenicity for a dataset of air toxins (332 chemicals) and a subset of the gold carcinogenic potency database (480 chemicals). Leave-one-out cross validation results show that the ensemble model achieves the best trade-off between sensitivity and specificity (accuracy: 83.8 % and 80.4 %, and balanced accuracy: 80.6 % and 80.8 %) and highest inter-rater agreement [kappa (Îș): 0.63 and 0.62] for both the datasets. The ROC curves demonstrate the utility of the cut-off feature in the predictive ability of the ensemble model. This feature provides an additional control to the regulators in grading a chemical based on the severity of the toxic endpoint under study
Carl Philipp Emanuel Bach: A Composer on the Fault Line of Ideological Change
While there has been a renewed interest in recent years on Carl Philipp Emanuel Bach and his place as a transitional figure in Western music history, little academic thought is given to his musical philosophy. Emanuelâs father, Johann Sebastian Bach, taught him the German-Protestant view that the primary purpose of music was to highlight scripture. Through his education, Emanuel gained an appreciation for the secular philosophies of humanism and the Enlightenment. In contrast to J. S. Bachâs Protestant views, the philosophies of the Enlightenment asserted that the primary purpose of music was to highlight the essence of humanity through emotions and reasoning. During his many years of working with Frederick the Great, Emanuel developed his musical style as he was influenced by many Enlightenment philosophers and musicians, primarily RenĂ© Descartes and Jean-Philippe Rameau. Emanuelâs use of the Empfindsamer Stil in music expanded the Enlightenment musical philosophy of the Doctrine of Affections by representing the unstable nature of human emotion. Emanuelâs Versuch ĂŒber die wahre art das clavier zu spielen was not only a profound declaration of musical theory technique but also demonstrated his belief that music should be guided by emotion
Fighting the Philistines: Robert Schumann and the \u3cem\u3eDavidsbĂŒndler\u3c/em\u3e
Robert Schumann was an eccentric composer and musical critic who influenced the Romantic-era musical community through the formation of the DavidsbĂŒndler. This âleague of Davidâ was Schumannâs idea of a musical society which exemplified a distinctly pure style of modern musical composition. The style of the DavidsbĂŒndler was based on the idea that music must reflect the personal life experiences of its composer. Needing a journal to publish musical writings of DavidsbĂŒndler, Schumann created the New Journal for Music. Having himself suffered from mental instability throughout his life, Schumannâs music often displayed unique levels of polarity and passion in order to show his own life experiences. Schumannâs mental polarity and instability was directly showcased in his music through the natures of fictional characters Florestan and Eusebius. These characters are clearly displayed though the piano works Carnival and the DavidsbuÌndlertaÌnze. Through the use of modern musical compositional techniques such as chromaticism and syncopation along with clear characterizations of Florestan and Eusebius, the DavidsbuÌndlertaÌnze stands as a testament to the ideals of the DavidsbuÌndler
Fertility control as a means of controlling bovine tuberculosis in badger (Meles meles) populations in south-west England: predictions from a spatial stochastic simulation model
A spatial stochastic simulation model was used to assess the potential of fertility control, based on a yet-to-be-developed oral bait-delivered contraceptive directed at females, for the control of bovine tuberculosis in badger populations in south-west England. The contraceptive had a lifelong effect so that females rendered sterile in any particular year remained so for the rest of their lives. The efficacy of fertility control alone repeated annually for varying periods of time was compared with a single culling operation and integrated control involving an initial single cull followed by annually repeated fertility control. With fertility control alone, in no instance was the disease eradicated completely while a viable badger population (mean group size of at least one individual) was still maintained. Near eradication of the disease (less than 1% prevalence) combined with the survival of a minimum viable badger population was only achieved under a very limited set of conditions, either with high efficiency of control (95%) over a short time period (1-3 years) or a low efficiency of control (20%) over an intermediate time period (10-20 years). Under these conditions, it took more than 20 years for the disease to decline to such low levels. A single cull of 80% efficiency succeeded in near eradication of the disease (below 1% prevalence) after a period of 6-8 years, while still maintaining a viable badger population. Integrated strategies reduced disease prevalence more rapidly and to lower levels than culling alone, although the mean badger group size following the onset of control was smaller. Under certain integrated strategies, principally where a high initial cull (80%) was followed by fertility control over a short (1-3 year) time period, the disease could be completely eradicated while a viable badger population was maintained. However, even under the most favourable conditions of integrated control, it took on average more than 12 years following the onset of control for the disease to disappear completely from the badger population. These results show that whilst fertility control would not be a successful strategy for the control of bovine tuberculosis in badgers if used alone, it could be effective if used with culling as part of an integrated strategy. This type of integrated strategy is likely to be more effective in terms of disease eradication than a strategy employing culling alone. However, the high cost of developing a suitable fertility control agent, combined with the welfare and conservation implications, are significant factors which should be taken into account when considering its possible use as a means of controlling bovine tuberculosis in badger populations in the UK
Fluid flow and heat transfer in a dual-wet micro heat pipe
Micro heat pipes have been used to cool micro electronic devices, but their heat transfer coefficients are low compared with those of conventional heat pipes. In this work, a dual-wet pipe is proposed as a model to study heat transfer in micro heat pipes. The dual-wet pipe has a long and narrow cavity of rectangular cross-section. The bottom-half of the horizontal pipe is made of a wetting material, and the top-half of a non-wetting material. A wetting liquid fills the bottom half of the cavity, while its vapour fills the rest. This configuration ensures that the liquidâvapour interface is pinned at the contact line. As one end of the pipe is heated, the liquid evaporates and increases the vapour pressure. The higher pressure drives the vapour to the cold end where the vapour condenses and releases the latent heat. The condensate moves along the bottom half of the pipe back to the hot end to complete the cycle. We solve the steady-flow problem assuming a small imposed temperature difference between the two ends of the pipe. This leads to skew-symmetric fluid flow and temperature distribution along the pipe so that we only need to focus on the evaporative half of the pipe. Since the pipe is slender, the axial flow gradients are much smaller than the cross-stream gradients. Thus, we can treat the evaporative flow in a cross-sectional plane as two-dimensional. This evaporative motion is governed by two dimensionless parameters: an evaporation number E defined as the ratio of the evaporative heat flux at the interface to the conductive heat flux in the liquid, and a Marangoni number M. The motion is solved in the limit Eââ and Mââ. It is found that evaporation occurs mainly near the contact line in a small region of size Eâ1W, where W is the half-width of the pipe. The non-dimensional evaporation rate Q* ~ Eâ1 ln E as determined by matched asymptotic expansions. We use this result to derive analytical solutions for the temperature distribution Tp and vapour and liquid flows along the pipe. The solutions depend on three dimensionless parameters: the heat-pipe number H, which is the ratio of heat transfer by vapour flow to that by conduction in the pipe wall and liquid, the ratio R of viscous resistance of vapour flow to interfacial evaporation resistance, and the aspect ratio S. If HRxs226B1, a thermal boundary layer appears near the pipe end, the width of which scales as (HR)â1/2L, where L is the half-length of the pipe. A similar boundary layer exists at the cold end. Outside the boundary layers, Tp varies linearly with a gradual slope. Thus, these regions correspond to the evaporative, adiabatic and condensing regions commonly observed in conventional heat pipes. This is the first time that the distinct regions have been captured by a single solution, without prior assumptions of their existence. If HR ~ 1 or less, then Tp is linear almost everywhere. This is the case found in most micro-heat-pipe experiments. Our analysis of the dual-wet pipe provides an explanation for the comparatively low effective thermal conductivity in micro heat pipes, and points to ways of improving their heat transfer capabilities
Maternal Anxiety Associated with Newborn Hearing Screening
The purpose of this study was to determine if newborn hearing screening increases maternal anxiety. Mothers whose infants were screened for hearing were asked how worried they were prior to hospital discharge and again six weeks later. They were also asked if they were more concerned about their babyâs hearing than they were about other aspects of the infantâs health and behavior.
Results showed that mothers worried as much or more about many other aspects of their infantsâ health and behavior as about hearing. Mothers whose infants had a false positive screening result were initially more worried about hearing than other aspects of their infantâs health, but this effect disappeared within six weeks. There were no significant differences at Time 1 or Time 2 for maternal anxiety as measured by the State Trait Anxiety Inventory between mothers whose infants had a false positive hearing screen compared to mothers of infants who passed their initial hearing screen.
Participation in newborn hearing screening is not associated with undue worry among mothers of newborns
Chandra Observations of low velocity dispersion groups
Deviations of galaxy groups from cluster scaling relations can be understood
in terms of an excess of entropy in groups. The main effect of this excess is
to reduce the density and thus luminosity of the intragroup gas. Given this,
groups should also should show a steep relationship between X-ray luminosity
and velocity dispersion. However, previous work suggests that this is not the
case with many measuring slopes flatter than the cluster relation.
Examining the group L_X:\sigma relation shows that much of the flattening is
caused by a small subset of groups which show very high X-ray luminosities for
their velocity dispersions (or vice versa).
Detailed Chandra study of two such groups shows that earlier ROSAT results
were subject to significant (~30-40%) point source contamination, but confirm
that a significant hot IGM is present in these groups, although these are two
of the coolest systems in which intergalactic X-ray emission has been detected.
Their X-ray properties are shown to be broadly consistent with those of other
galaxy groups, although the gas entropy in NGC 1587 is unusually low, and its
X-ray luminosity correspondingly high for its temperature, compared to most
groups.
This leads us to suggest that the velocity dispersion in these systems has
been reduced in some way, and we consider how this might have come about.Comment: Accepted for publication in Ap
Accurate collection of reasons for treatment discontinuation to better define estimands in clinical trials
Background: Reasons for treatment discontinuation are important not only to
understand the benefit and risk profile of experimental treatments, but also to
help choose appropriate strategies to handle intercurrent events in defining
estimands. The current case report form (CRF) commonly in use mixes the
underlying reasons for treatment discontinuation and who makes the decision for
treatment discontinuation, often resulting in an inaccurate collection of
reasons for treatment discontinuation. Methods and results: We systematically
reviewed and analyzed treatment discontinuation data from nine phase 2 and
phase 3 studies for insulin peglispro. A total of 857 participants with
treatment discontinuation were included in the analysis. Our review suggested
that, due to the vague multiple-choice options for treatment discontinuation
present in the CRF, different reasons were sometimes recorded for the same
underlying reason for treatment discontinuation. Based on our review and
analysis, we suggest an intermediate solution and a more systematic way to
improve the current CRF for treatment discontinuations. Conclusion: This
research provides insight and directions on how to optimize the CRF for
recording treatment discontinuation. Further work needs to be done to build the
learning into Clinical Data Interchange Standards Consortium standards.Comment: 13 pages, 3 figures, 1 tabl
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