Publications
35
Thesis
2
Department
27
Researchers
183
Recent Additions
  • Publication
    Modules for Experiments in Stellar Astrophysics (MESA): Time-dependent Convection, Energy Conservation, Automatic Differentiation, and Infrastructure
    (2023-03-01)
    Jermyn, Adam S.
    ;
    Bauer, Evan B.
    ;
    Schwab, Josiah
    ;
    Farmer, R.
    ;
    Ball, Warrick H.
    ;
    Bellinger, Earl P.
    ;
    Dotter, Aaron
    ;
    Joyce, Meridith
    ;
    Marchant, Pablo
    ;
    Mombarg, Joey S.G.
    ;
    Wolf, William M.
    ;
    Sunny Wong, Tin Long
    ;
    Cinquegrana, Giulia C.
    ;
    Farrell, Eoin
    ;
    Smolec, R.
    ;
    Thoul, Anne
    ;
    Cantiello, Matteo
    ;
    Herwig, Falk
    ;
    ;
    Bildsten, Lars
    ;
    Townsend, Richard H.D.
    ;
    Timmes, F. X.
    Abstract We update the capabilities of the open-knowledge software instrument Modules for Experiments in Stellar Astrophysics (MESA). The new auto_diff module implements automatic differentiation in MESA, an enabling capability that alleviates the need for hard-coded analytic expressions or finite-difference approximations. We significantly enhance the treatment of the growth and decay of convection in MESA with a new model for time-dependent convection, which is particularly important during late-stage nuclear burning in massive stars and electron-degenerate ignition events. We strengthen MESA’s implementation of the equation of state, and we quantify continued improvements to energy accounting and solver accuracy through a discussion of different energy equation features and enhancements. To improve the modeling of stars in MESA, we describe key updates to the treatment of stellar atmospheres, molecular opacities, Compton opacities, conductive opacities, element diffusion coefficients, and nuclear reaction rates. We introduce treatments of starspots, an important consideration for low-mass stars, and modifications for superadiabatic convection in radiation-dominated regions. We describe new approaches for increasing the efficiency of calculating monochromatic opacities and radiative levitation, and for increasing the efficiency of evolving the late stages of massive stars with a new operator-split nuclear burning mode. We close by discussing major updates to MESA’s software infrastructure that enhance source code development and community engagement.
  • Publication
    Identifying the Needs of Older Adults Associated with Daily Activities: A Qualitative Study
    (2023-03-01) ;
    Radici Fraga, Paula Görgen
    ;
    Schilling-Norman, Mary Jane
    ;
    Pérez-Villalobos, Cristhian
    Introduction: By 2050, older adults will constitute 16% of the world population; hence, there is an urgent demand and challenge to design solutions (products and services) that meet the needs of this age group. This study sought to analyse the needs that impact the well-being of Chilean older adults and present possible solutions through the design of products. Methodology: A qualitative study was used, where focus groups were held with older adults, industrial designers, health professionals, and entrepreneurs on the needs and design of solutions for older adults. Results: A general map was obtained that linked the categories and subcategories related to the relevant needs and solutions, which were then classified in a framework. Conclusions: The resulting proposal places the needs in different fields of expertise; and thus, enables positioning, broadening, and expanding upon the map to share knowledge, between the user and key experts, to co-create solutions.
  • Publication
    Probing R-parity violation in B-meson decays to a baryon and a light neutralino
    (2023-02-01) ;
    Helo, Juan Carlos
    ;
    Lyubovitskij, Valery E.
    ;
    Neill, Nicolás A.
    ;
    Soffer, Abner
    ;
    Wang, Zeren Simon
    Abstract We propose a search for B meson decays to a baryon plus missing energy at the Belle II experiment to probe supersymmetry with a GeV-scale lightest neutralino $$ {\overset{\sim }{\chi}}_1^0 $$ χ ~ 1 0 and R-parity violation (RPV). We perform analytic computations of the signal branching fractions in the framework of effective field theory, with a single nonzero RPV operator $$ {\lambda}_{ij3}^{\prime \prime }{\overline{U}}_i^c{\overline{D}}_j^c{\overline{D}}_3^c $$ λ ij 3 ′ ′ U ¯ i c D ¯ j c D ¯ 3 c , where i, j = 1, 2. The hadronic form factors are calculated using an SU(3) phenomenological Lagrangian approach for the proton, as well as several hyperons and charmed baryons. Since the decay of the neutralino is kinematically and CKM suppressed in this theoretical scenario, it decays outside the detector and appears experimentally only as missing energy. We detail the analysis techniques at the experimental level and estimate the background in the $$ {B}^{+}\to p{\overset{\sim }{\chi}}_1^0 $$ B + → p χ ~ 1 0 search using published results for $$ {B}^{+}\to {K}^{+}\nu \overline{\nu} $$ B + → K + ν ν ¯ . Our final sensitivity plots are shown for both $$ {\lambda}_{113}^{\prime \prime } $$ λ 113 ′ ′ versus the squark mass $$ {m}_{\tilde{q}} $$ m q ~ and $$ {\lambda}_{113}^{\prime \prime }/{m}_{\tilde{q}}^2 $$ λ 113 ′ ′ / m q ~ 2 versus the neutralino mass $$ {m}_{{\overset{\sim }{\chi}}_1^0} $$ m χ ~ 1 0 . We find that the search at Belle II could probe $$ {\lambda}_{113}^{\prime \prime }/{m}_{\tilde{q}}^2 $$ λ 113 ′ ′ / m q ~ 2 down to the order of 10−8 GeV−2 in the kinematically allowed $$ {m}_{{\overset{\sim }{\chi}}_1^0} $$ m χ ~ 1 0 range. We also obtain current limits on $$ {\lambda}_{123}^{\prime \prime } $$ λ 123 ′ ′ by recasting an existing search interpreted as $$ {B}^0\to {\Lambda}^0{\overset{\sim }{\chi}}_1^0 $$ B 0 → Λ 0 χ ~ 1 0 , and comment about searches for $$ {B}^{+}\to {\Sigma}^{+}{\overset{\sim }{\chi}}_1^0 $$ B + → Σ + χ ~ 1 0 , $$ {B}^0\to {\Sigma}^0{\chi}_1^0 $$ B 0 → Σ 0 χ 1 0 , $$ {B}^{+}\to {\Lambda}_c^{+}{\overset{\sim }{\chi}}_1^0 $$ B + → Λ c + χ ~ 1 0 , and $$ {B}^{+}\to {\Xi}_c^{+}{\overset{\sim }{\chi}}_1^0 $$ B + → Ξ c + χ ~ 1 0 . In closing, we briefly discuss potential searches at the LHCb and BESIII experiments.
  • Publication
    Older Adults’ Thermal Comfort in Nursing Homes: Exploratory Research in Three Case Studies
    (2023-02-01)
    Neira-Zambrano, Karina
    ;
    Trebilcock-Kelly, Maureen
    ;
    There are two types of occupants in nursing homes: older adults and caregivers. Because the former has different physiological qualities, they are more sensitive to high and low temperatures, presenting discrepancies with caregivers regarding thermal sensation. The objective of this exploratory research was to determine to what extent the range of thermal comfort differed between older adults and caregivers in three nursing homes in Gran Concepción. Indoor and outdoor temperature and relative humidity were monitored during winter and spring. Simultaneously, a thermal sensation and preference survey was applied while clothing insulation, metabolic rate, and adaptive responses were observed. Neutral temperature was calculated using Griffiths’ method for both groups to determine the comfort ranges and compare them. The older adults presented a higher neutral temperature than the caregivers with a difference of 0.8 °C in winter and 1.74 °C in spring. Regarding the adaptive response, both occupant types performed the same actions to achieve comfort, but older adults had less control over these. It is hoped that this study can lay the groundwork regarding comfort temperatures for older adults in Chile and integrate a discussion regarding their well-being on a local and global scale.
  • Publication
    XGAPS: a sub-arcsec cross-match of galactic plane surveys
    (2023-01-01)
    Scaringi, S.
    ;
    Monguió, M.
    ;
    Knigge, C.
    ;
    Fratta, M.
    ;
    Gänsicke, B.
    ;
    Groot, P. J.
    ;
    Rebassa-Mansergas, A.
    ;
    ABSTRACT We present a sub-arcsec cross-match of Gaia Data Release 3 (DR3) against the INT Galactic Plane Surveys (IGAPS) and the United Kingdom Infrared Deep Sky Survey (UKIDSS). The resulting cross-match of Galactic Plane Surveys (XGAPS) provides additional precise photometry (URGO, g, r, i, Hα, J, H, and K) to the Gaia photometry. In building the catalogue, proper motions given in Gaia DR3 are wound back to match the epochs of the IGAPS constituent surveys (INT Photometric HαSurvey of the Northern Galactic Plane, IPHAS, and the UV-Excess Survey of the Northern Galactic Plane, UVEX) and UKIDSS, ensuring high-proper motion objects are appropriately cross-matched. The catalogue contains 33 987 180 sources. The requirement of >3σ parallax detection for every included source means that distances out to 1–1.5 kpc are well covered. In producing XGAPS, we have also trained a Random Forest classifier to discern targets with problematic astrometric solutions. Selection cuts based on the classifier results can be used to clean colour-magnitude and colour–colour diagrams in a controlled and justified manner, as well as producing subsets of astrometrically reliable targets. We provide XGAPS as a 111 column table. Uses of the catalogue include the selection of Galactic targets for multi-object spectroscopic surveys as well as identification of specific Galactic populations.