61 research outputs found
Sharpening up Galactic all-sky maps with complementary data - A machine learning approach
Galactic all-sky maps at very disparate frequencies, like in the radio and
-ray regime, show similar morphological structures. This mutual
information reflects the imprint of the various physical components of the
interstellar medium. We want to use multifrequency all-sky observations to test
resolution improvement and restoration of unobserved areas for maps in certain
frequency ranges. For this we aim to reconstruct or predict from sets of other
maps all-sky maps that, in their original form, lack a high resolution compared
to other available all-sky surveys or are incomplete in their spatial coverage.
Additionally, we want to investigate the commonalities and differences that the
ISM components exhibit over the electromagnetic spectrum. We build an
-dimensional representation of the joint pixel-brightness distribution of
maps using a Gaussian mixture model and see how predictive it is: How well
can one map be reproduced based on subsets of other maps? Tests with mock data
show that reconstructing the map of a certain frequency from other frequency
regimes works astonishingly well, predicting reliably small-scale details well
below the spatial resolution of the initially learned map. Applied to the
observed multifrequency data sets of the Milky Way this technique is able to
improve the resolution of, e.g., the low-resolution Fermi LAT maps as well as
to recover the sky from artifact-contaminated data like the ROSAT 0.855 keV
map. The predicted maps generally show less imaging artifacts compared to the
original ones. A comparison of predicted and original maps highlights
surprising structures, imaging artifacts (fortunately not reproduced in the
prediction), and features genuine to the respective frequency range that are
not present at other frequency bands. We discuss limitations of this machine
learning approach and ideas how to overcome them
Bayesian decomposition of the Galactic multi-frequency sky using probabilistic autoencoders
All-sky observations of the Milky Way show both Galactic and non-Galactic
diffuse emission, for example from interstellar matter or the cosmic microwave
background (CMB). The different emitters are partly superimposed in the
measurements, partly they obscure each other, and sometimes they dominate
within a certain spectral range. The decomposition of the underlying radiative
components from spectral data is a signal reconstruction problem and often
associated with detailed physical modeling and substantial computational
effort. We aim to build an effective and self-instructing algorithm detecting
the essential spectral information contained Galactic all-sky data covering
spectral bands from -ray to radio waves. Utilizing principles from
information theory, we develop a state-of-the-art variational autoencoder
specialized on the adaption to Gaussian noise statistics. We first derive a
generic generative process that leads from a low-dimensional set of emission
features to the observed high-dimensional data. We formulate a posterior
distribution of these features using Bayesian methods and approximate this
posterior with variational inference. The algorithm efficiently encodes the
information of 35 Galactic emission data sets in ten latent feature maps. These
contain the essential information required to reconstruct the initial data with
high fidelity and are ranked by the algorithm according to their significance
for data regeneration. The three most significant feature maps encode
astrophysical components: (1) The dense interstellar medium (ISM), (2) the hot
and dilute regions of the ISM and (3) the CMB. The machine-assisted and
data-driven dimensionality reduction of spectral data is able to uncover the
physical features encoding the input data. Our algorithm is able to extract the
dense and dilute Galactic regions, as well as the CMB, from the sky brightness
values only.Comment: 25 pages, 8 figures, 3 tables. Submitted to Astronomy & Astrophysic
Walk on the Low Side: LOFAR explores the low-frequency radio emission of GASP jellyfish galaxies
Jellyfish galaxies, characterized by long filaments of stripped interstellar
medium extending from their disks, are the prime laboratories to study the
outcomes of ram pressure stripping. At radio wavelengths, they often show
unilateral emission extending beyond the stellar disk, and an excess of radio
luminosity with respect to that expected from their current star formation
rate. We present new 144 MHz images provided by the LOFAR Two-metre Sky Survey
for a sample of six galaxies from the GASP survey. These galaxies are
characterized by a high global luminosity at 144 MHz ( W
Hz), in excess compared to their ongoing star formation rate. The
comparison of radio and H images smoothed with a Gaussian beam
corresponding to 10 kpc reveals a sub-linear spatial correlation between
the two emissions with an average slope . In their stellar disk we
measure , which is close to the radio-to-star formation linear
relation. We speculate that, as a consequence of the ram pressure, in these
jellyfish galaxies the cosmic rays transport is more efficient than in normal
galaxies. Radio tails typically have higher radio-to-H ratios than the
disks, thus we suggest that the radio emission is boosted by the electrons
stripped from the disks. In all galaxies, the star formation rate has decreased
by a factor within the last yr. The observed radio emission
is consistent with the past star formation, so we propose that this recent
decline may be the cause of their radio luminosity-to-star formation rate
excess.Comment: 22 pages, 7 figures. Accepted for publication on ApJ on 24/08/202
The role of environment on quenching, star formation and AGN activity
Galaxies undergoing ram pressure stripping in clusters are an excellent
opportunity to study the effects of environment on both the AGN and the star
formation activity. We report here on the most recent results from the GASP
survey. We discuss the AGN-ram pressure stripping connection and some evidence
for AGN feedback in stripped galaxies. We then focus on the star formation
activity, both in the disks and the tails of these galaxies, and conclude
drawing a picture of the relation between multi-phase gas and star formation.Comment: Proceedings of the IAU Symposium 359 "Galaxy evolution and feedback
across different environments", editors T. Storchi-Bergmann, R. Overzier, W.
Forman & R. Riffel - final versio
CHANG-ES XXXI—A Decade of CHANG-ES: What We Have Learned from Radio Observations of Edge-on Galaxies
CHANG-ES (Continuum Halos in Nearby Galaxies—an EVLA Survey) is an ambitious project to target 35 nearby disk galaxies that are edge-on to the line of sight. The orientation permits both the disk and halo regions to be studied. The observations were initially at 1.5 GHz (L-band) and 6.0 GHz (C-band) in a variety of VLA array configurations, and in all four Stokes parameters, which allowed for spatially resolved images in total intensity plus polarization. The inclusion of polarization is unique to an edge-on galaxy survey and reveals the galaxies’ halo magnetic fields. This paper will summarize the results to date, some of which are new phenomena, never seen prior to CHANG-ES. For example, we see that ‘X-type’ fields, as well as rotation measure reversals, are common features of spiral galaxies. Further observations at 3.0 GHz (S-band) as well as future scientific opportunities will also be described
Microgels sensibles au glucose pour la delivrance d’insuline
Le traitement du diabète de type 1 en boucle fermée représente un enjeu majeur tant sur le plan sociétal que thérapeutique. L’une des solutions consiste en une formulation thérapeutique basée sur des microvéhicules capables de délivrer la bonne dose d’insuline selon une cinétique adaptée aux variations de la glycémie. Les microgels sont des particules de polymère réticulé formant des édifices submicrométriques tridimensionnels gonflés par un solvant, dont le taux de gonflement dépend des conditions environnementales. Leur porosité permet à la fois l’encapsulation d’espèces et leur libération à une vitesse dépendant de leur diffusion à travers le réseau. Nous avons synthétisé des microgels à base de poly(N-alkylacrylamide) fonctionnalisés par des récepteurs du glucose dérivés de l’acide phénylboronique. Ces microgels, à la base thermosensibles, présentent la propriété de changer de volume en fonction de la concentration en glucose et se présentent comme d’excellents candidats pour la délivrance auto-régulée d’insuline dans le cadre du traitement du diabète. Ils permettent la délivrance répétée de doses d’insuline modulée par la glycémie. La quantité d’insuline encapsulée a pu être améliorée en structurant les microgels en architecture cœur-écorce ou capsule.En outre, nous avons utilisé ces microgels pour développer des capteurs au glucose, sélectifs vis-à-vis des autres saccharides et quelques études de cytotoxicité ont été amorcées et ont permis d’établir avec satisfaction que certains de nos objets n’étaient pas toxiques.Les résultats obtenus ont donc permis d’affirmer que la technologie des microgels sensibles au glucose peut répondre de manière conceptuelle aux attentes des patients diabétiques pour permettre la délivrance d’insuline en boucle fermée.Bioresponsive hydrogels can change many of their physical properties in response to the recognition of a target in the solution. In particular, changes in hydrogel swelling lead in turn to controllable changes in shape, volume, pore size, mechanical and optical properties. We focus our research on the development of glucose-responsive microgels which hold promising interest in the field of both sensing and drug delivery. These cross-linked polymer particles, made of highly swollen networks, can swell proportionally to the concentration of glucose in the surrounding medium. Since they are porous, they can entrap a drug and release it a rate dependent on their swelling degree, which is of particular interest in the case of insulin as a drug. Such systems could be used as self-regulated insulin delivery systems for diabetes treatment. With that aim, we have designed microgels able to sense glucose concentrations in the patho-physiological range, under physiological conditions. Insulin was successfully loaded into the nanogels and was shown to be released at a rate dependent on glucose concentration. Furthermore, microgels with a controlled internal structure were synthesized, such as core-shell microgels and capsules. These latter developments led to improvements in terms of insulin encapsulation efficiency and glucose-triggered delivery. Besides, other nanogel formulations were investigated, in order to improve both their biocompatibility as well as the selectivity of their response to glucose compared to other saccharides
Annulate lamellae in the Sertoli cells of guinea pig testis after unilateral torsion of the spermatic cord
Microgels sensibles au glucose pour la delivrance d’insuline
Le traitement du diabète de type 1 en boucle fermée représente un enjeu majeur tant sur le plan sociétal que thérapeutique. L’une des solutions consiste en une formulation thérapeutique basée sur des microvéhicules capables de délivrer la bonne dose d’insuline selon une cinétique adaptée aux variations de la glycémie. Les microgels sont des particules de polymère réticulé formant des édifices submicrométriques tridimensionnels gonflés par un solvant, dont le taux de gonflement dépend des conditions environnementales. Leur porosité permet à la fois l’encapsulation d’espèces et leur libération à une vitesse dépendant de leur diffusion à travers le réseau. Nous avons synthétisé des microgels à base de poly(N-alkylacrylamide) fonctionnalisés par des récepteurs du glucose dérivés de l’acide phénylboronique. Ces microgels, à la base thermosensibles, présentent la propriété de changer de volume en fonction de la concentration en glucose et se présentent comme d’excellents candidats pour la délivrance auto-régulée d’insuline dans le cadre du traitement du diabète. Ils permettent la délivrance répétée de doses d’insuline modulée par la glycémie. La quantité d’insuline encapsulée a pu être améliorée en structurant les microgels en architecture cœur-écorce ou capsule.En outre, nous avons utilisé ces microgels pour développer des capteurs au glucose, sélectifs vis-à-vis des autres saccharides et quelques études de cytotoxicité ont été amorcées et ont permis d’établir avec satisfaction que certains de nos objets n’étaient pas toxiques.Les résultats obtenus ont donc permis d’affirmer que la technologie des microgels sensibles au glucose peut répondre de manière conceptuelle aux attentes des patients diabétiques pour permettre la délivrance d’insuline en boucle fermée.Bioresponsive hydrogels can change many of their physical properties in response to the recognition of a target in the solution. In particular, changes in hydrogel swelling lead in turn to controllable changes in shape, volume, pore size, mechanical and optical properties. We focus our research on the development of glucose-responsive microgels which hold promising interest in the field of both sensing and drug delivery. These cross-linked polymer particles, made of highly swollen networks, can swell proportionally to the concentration of glucose in the surrounding medium. Since they are porous, they can entrap a drug and release it a rate dependent on their swelling degree, which is of particular interest in the case of insulin as a drug. Such systems could be used as self-regulated insulin delivery systems for diabetes treatment. With that aim, we have designed microgels able to sense glucose concentrations in the patho-physiological range, under physiological conditions. Insulin was successfully loaded into the nanogels and was shown to be released at a rate dependent on glucose concentration. Furthermore, microgels with a controlled internal structure were synthesized, such as core-shell microgels and capsules. These latter developments led to improvements in terms of insulin encapsulation efficiency and glucose-triggered delivery. Besides, other nanogel formulations were investigated, in order to improve both their biocompatibility as well as the selectivity of their response to glucose compared to other saccharides
Integrative action research paper on creating company branding direction and guidelines for Healthy Hogs Brand Central
This insider action research is aimed at increasing brand awareness in a start-up business by improving brand identity, brand resonance, and consumer engagement and following. In the completed cycles, the marketing team created company branding direction and guidelines to improve the consistency and quality of Healthy Hogs’ Facebook and Instagram posts. The team used the PESTLE analysis and the ADKAR change management model to ensure that the interventions were effective.
Cycle 1 focused on the team’s lack of consumer engagement and branding guidelines. During this cycle, the objective was to give users of the manual an idea about the brand without limiting their creativity. The team completed this cycle with success and achieved the desired future state it had agreed on.
Cycle 2 addressed the team’s low level of consumer following and engagement and lack of better advertising targeting. The team’s objective was to ensure that the marketing strategies and publication materials are consistent and coherent with the brand. As in Cycle 1, the team completed Cycle 2 with success and achieved the desired future state it had agreed on.
In the broader context, the research explored the political, economic, sociocultural, technological, legal, and environmental forces that the business operates in. Through reflection, I understood the external factors that had a significant part in shaping the team’s marketing decisions. I also realized that our business decisions have an impact on the macro-environment. The team’s interventions were affected by and have affected the factors such as lifestyle trends, e-commerce, sustainable business operations, and consumer rights policies among others
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