9,122 research outputs found

    Interacting Dark Energy: Possible Explanation for 21-cm Absorption at Cosmic Dawn

    Full text link
    A recent observation points to an excess in the expected 21-cm brightness temperature from cosmic dawn. In this paper, we present an alternative explanation of this phenomenon, an interaction in the dark sector. Interacting dark energy models have been extensively studied recently and there is a whole variety of such in the literature. Here we particularize to a specific model in order to make explicit the effect of an interaction.Comment: 5 pages, 2 figures. Discussion improved, new references, conclusions unchanged. Accepted in EPJ

    (2+1) Resonance Enhanced Ionization Spectroscopy of a State Selected Beam of OH Radicals

    Get PDF
    A state-selected beam of hydroxyl radicals is generated using a pulsed discharge source and hexapole field. The OH radicals are characterized by resonance-enhanced multiphoton ionization (REMPI) spectroscopy via the nested Dā€‰ and 3ā€‰ Rydberg states. Simplified spectra are observed from the selected āˆ£MJāˆ£ = 3/2 component of the upper Ī›-doublet level of the lowest rotational state (J = 3/2) in ground (vā€³ = 0) and excited(vā€³ = 1ā€“3) vibrational levels of the OH Xā€‰ state. Two-photon transitions are observed to the Dā€‰(vā€² = 0ā€“3) and 3ā€‰(vā€² = 0,1) vibronic levels, extending previous studies to higher vibrational levels of the Rydberg states. Spectroscopic constants are derived for the Rydberg states and compared with prior experimental studies. Complementary first-principle theoretical studies of the Dā€‰ and 3ā€‰ Rydberg states [see M. P. J. van der Loo and G. C. Groenenboom, J. Chem. Phys. 123, 074310 (2005), following paper ] are used to interpret the experimental findings and examine the utility of the (2+1) REMPI scheme for sensitive detection of OH radicals

    Ultrafast Resonant Polarization Interferometry: Towards the First Direct Detection of Vacuum Polarization

    Full text link
    Vacuum polarization, an effect predicted nearly 70 years ago, is still yet to be directly detected despite significant experimental effort. Previous attempts have made use of large liquid-helium cooled electromagnets which inadvertently generate spurious signals that mask the desired signal. We present a novel approach for the ultra-sensitive detection of optical birefringence that can be usefully applied to a laboratory detection of vacuum polarization. The new technique has a predicted birefringence measurement sensitivity of Ī”nāˆ¼1020\Delta n \sim 10^{20} in a 1 second measurement. When combined with the extreme polarizing fields achievable in this design we predict that a vacuum polarization signal will be seen in a measurement of just a few days in duration.Comment: 9 pages, 2 figures. submitted to PR

    Greek-Letter Membership and College Graduation: Does Race Matter?

    Get PDF
    Research, utilizing a nationally representative sample of 3,712 Americans, revealed that Greek-letter membership increases the probability of college graduation more for African Americans than for European Americans. Conversely, father\u27s education is a more robust predictor of educational outcomes for European Americans compared to their African American counterpart

    Deep learning techniques applied to skin lesion classification: a review

    Get PDF
    Skin cancer is one of the most common cancers in the world. The most dangerous type of skin cancer is melanoma, which can be lethal if not treated early. However, diagnosing skin lesions can be a difficult task. Therefore, deep learning techniques applied to the diagnosis of skin lesions have been explored by researchers, given their effectiveness in extracting features and classifying input data. In this work, we present a review of latest approaches that apply deep learning techniques to skin lesion classification task. In addition, some datasets used for training and validating the models are introduced, informing their characteristics and specificities, as well as popular pre-processing steps and skin lesion segmentation approaches. Finally, we comment the effectiveness of the proposed models.info:eu-repo/semantics/publishedVersio

    The Parallel Encounter: An Alternative to the Traditional Serial Traineeā€“Attending Patient Evaluation Model

    Full text link
    BackgroundThe emergency department environment requires the clinicianā€educator to use adaptive teaching strategies to balance education with efficiency and patient care. Recently, alternative approaches to the traditional serial traineeā€“attending patient evaluation model have emerged in the literature.MethodsThe parallel encounter involves the attending physician and resident seeing the patient independently. Instead of the trainee delivering a traditional oral case presentation, the trainee does not present the history and examination to the attending physician. Rather, the attending and trainee come together following their independent evaluations to jointly discuss and formulate the assessment and plan.ResultsThe parallel encounter has the potential to enhance the teaching encounter by emphasizing clinical reasoning, reduce cognitive bias by integrating two independent assessments of the same patient, increase attending workflow flexibility and efficiency, and improve patient satisfaction and outcomes by reducing time to initial provider contact. The attending must be mindful of protecting resident autonomy. This model tends to work better for more senior learners.ConclusionsThe parallel encounter represents a novel approach to the traditional serial traineeā€“attending patient evaluation model that may enhance the teaching encounter and improve patient care.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/163487/2/aet210491_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/163487/1/aet210491.pd

    Photodissociation of the OD radical at 226 and 243 nm

    Get PDF
    The photodissociation dynamics of state selected OD radicals has been examined at 243 and 226 nm using velocity map imaging to probe the angleā€“speed distributions of theD(2S) and O(3P2) products. Both experiment and complementary first principle calculations demonstrate that photodissociation occurs by promotion of OD from high vibrational levels of the ground Xā€Š2Ī  state to the repulsive 1ā€Š2Ī£āˆ’ state
    • ā€¦
    corecore