Are Compact High-Velocity Clouds Extragalactic Objects?

Compact high-velocity clouds (CHVCs) are the most distant of the HVCs in the Local Group model and would have HI volume densities of order 0.0003/cm^3. Clouds with these volume densities and the observed neutral hydrogen column densities will be largely ionized, even if exposed only to the extragalactic ionizing radiation field. Here we examine the implications of this process for models of CHVCs. We have modeled the ionization structure of spherical clouds (with and without dark matter halos) for a large range of densities and sizes, appropriate to CHVCs over the range of suggested distances, exposed to the extragalactic ionizing photon flux. Constant-density cloud models in which the CHVCs are at Local Group distances have total (ionized plus neutral) gas masses roughly 20-30 times larger than the neutral gas masses, implying that the gas mass alone of the observed population of CHVCs is about 40 billion solar masses. With a realistic (10:1) dark matter to gas mass ratio, the total mass in such CHVCs is a significant fraction of the dynamical mass of the Local Group, and their line widths would exceed the observed FWHM. Models with dark matter halos fare even more poorly; they must lie within approximately 200 kpc of the Galaxy. We show that exponential neutral hydrogen column density profiles are a natural consequence of an external source of ionizing photons, and argue that these profiles cannot be used to derive model-independent distances to the CHVCs. These results argue strongly that the CHVCs are not cosmological objects, and are instead associated with the Galactic halo.Comment: 30 pages, 14 figures; to appear in The Astrophysical Journa

Childhood Characteristics of Adolescent Inpatients with Early-Onset and Adolescent-Onset Disruptive Behavior

Childhood characteristics are associated with life-course-persistent antisocial behavior in epidemiological studies in general population samples. The present study examines this association in an inpatient sample. The purpose is to identify easily measurable childhood characteristics that may guide choice of treatment for adolescent psychiatric inpatients with severe disruptive behavior. Patients (N = 203) were divided into two groups with either early-onset (EO) or adolescent-onset (AO) disruptive behavior, based on ages at which professional care was used for disruptive behavior, referral to special education, and criminal offences. Both groups differed on several childhood characteristics. No gender differences in these characteristics were found. Logistic regression analysis indicated that individuals with grade retention in primary school, childhood impulsive behavior, and a history of physical abuse, had the highest probability of being member of the EO group. These characteristics are reasonably easy to identify, likely apply to other clinical samples as well, and may help clinicians to target their treatment

The physics of water and wax in the pores of a working Gas-to-Liquids catalyst

The so-called Fischer-Tropsch catalysis allows to convert natural gas into liquid products and is the underlying mechanism of commercially used "Gas-to-Liquids" plants. The actual reaction takes place in millimetre sized porous pellets in which active metallic particles are dispersed as catalysts. Due to the reaction the pores of the pellets will become filled with the reaction products ("wax" and water), but it is uncertain if the fluid in the pores can be understood as a single liquid phase, a liquid-gas mixture, or multiple continuous phases. The answer to this question is important for a thorough understanding of the transport processes inside the reactor and can be utilized to improve its eciency. In this project, a theoretical analysis of the behaviour inside the pores is performed. It is concluded that a liquid water phase might well exist next to the wax phase. However, the analysis is based on very limited experimental data of unknown quality. Therefore, we propose a number of possible experiments to validate the theoretical concepts

Picosecond Fluorescence Relaxation Spectroscopy of the Calcium-Discharged Photoproteins Aequorin and Obelin

Addition of calcium ions to the Ca2+-regulated photoproteins, such as aequorin and obelin, produces a blue bioluminescence originating from a fluorescence transition of the protein-bound product, coelenteramide. The kinetics of several transient fluorescent species of the bound coelenteramide is resolved after picosecond-laser excitation and streak camera detection. The initially formed spectral distributions at picosecond-times are broad, evidently comprised of two contributions, one at higher energy (25000 cm-1) assigned as from the Ca2+-discharged photoprotein-bound coelenteramide in its neutral state. This component decays much more rapidly (t1/2 2 ps) in the case of the Ca2+-discharged obelin than aequorin (t1/2 30 ps). The second component at lower energy shows several intermediates in the 150-500 ps times, with a final species having spectral maxima 19400 cm-1, bound to Ca2+-discharged obelin, and 21300 cm-1, bound to Ca2+-discharged aequorin, and both have a fluorescence decay lifetime of 4 ns. It is proposed that the rapid kinetics of these fluorescence transients on the picosecond time scale, correspond to times for relaxation of the protein structural environment of the binding cavit

Characteristics associated with polypharmacy in people with type 2 diabetes:the Dutch Diabetes Pearl cohort

Contains fulltext : 232027.pdf (Publisher’s version ) (Open Access)AIM: To describe the prevalence and characteristics of polypharmacy in a Dutch cohort of individuals with type 2 diabetes. METHODS: We included people with type 2 diabetes from the Diabetes Pearl cohort, of whom 3886 were treated in primary care and 2873 in academic care (secondary/tertiary). With multivariable multinomial logistic regression analyses stratified for line of care, we assessed which sociodemographic, lifestyle and cardiometabolic characteristics were associated with moderate (5-9 medications) and severe polypharmacy (≥10 medications) compared with no polypharmacy (0-4 medications). RESULTS: Mean age was 63 ± 10 years, and 40% were women. The median number of daily medications was 5 (IQR 3-7) in primary care and 7 (IQR 5-10) in academic care. The prevalence of moderate and severe polypharmacy was 44% and 10% in primary care, and 53% and 29% in academic care respectively. Glucose-lowering and lipid-modifying medications were most prevalent. People with severe polypharmacy used a relatively large amount of other (i.e. non-cardiovascular and non-glucose-lowering) medication. Moderate and severe polypharmacy across all lines of care were associated with higher age, low educational level, more smoking, longer diabetes duration, higher BMI and more cardiovascular disease. CONCLUSIONS: Severe and moderate polypharmacy are prevalent in over half of people with type 2 diabetes in primary care, and even more in academic care. People with polypharmacy are characterized by poorer cardiometabolic status. These results highlight the significance of polypharmacy in type 2 diabetes

Exploring the “how” in research partnerships with young partners by experience: lessons learned in six projects from Canada, the Netherlands, and the United Kingdom

This is the final version. Available on open access from BMC via the DOI in this recordAvailability of data and materials: All data generated or analysed during this study are included in this published article.Background Involvement of young partners by experience in research is on the rise and becoming expected practice. However, literature on how to promote equitable and meaningful involvement of young people is scarce. The purpose of this paper is to describe and reflect on different approaches between researchers and young partners by experience based on six research projects conducted in Canada, Netherlands, and United Kingdom. Methods From six exemplar research projects, at least one researcher and one young partner by experience were asked to collaboratively (1) describe the project; (2) summarise the values and practicalities of the project; and (3) reflect on their partnership. Thematic analysis was applied to the findings from these reflective exercises, which included meeting summaries, recordings, and notes. Results All projects shared similar values, including mutual respect between all team members. Young partners were offered a variety of opportunities and approaches to being involved, for example in recruiting participants, co-analysing or (co-)presenting results. Supports were provided to the teams in a variety of ways, including organizing accessible meetings and having dedicated facilitators. Regular and proactive communication was encouraged by using asynchronous modes of communication, establishing reference documents, and a personal approach by facilitators. Facilitators aimed to tailor the needs of all team members by continuously discussing their preferred roles in the project. While most projects did not offer formal research training, various learning and skill development opportunities were provided throughout, including presenting skills or advocacy training. Conclusion With this paper, we demonstrated the value of reflection, and we invite others to reflect on their partnerships and share their lessons learned. Our recommendations for involvement of young people in research are: (1) Remember that it is okay to not know what the partnership might look like and there is no single recipe of how to partner; (2) Take the time to invest in partnerships; (3) Provide ongoing opportunities to reflect on partnerships; (4) Consider how to balance the power dynamics; and (5) Consider how to incorporate diversity in the background of young partners in research.Canadian Institutes of Health ResearchFNO, Amsterdam, the NetherlandsZonMWBig Lottery, UKBritish AcademyCIHR-SCA-145104Montreal Children’s Hospital FoundationFaculty of Health Sciences, McMaster UniversityNew Brunswick Health Research FoundationMcMaster Children’s Hospital FoundationHamilton Health Science

The Disk and Dark Halo Mass of the Barred Galaxy NGC 4123. II. Fluid-Dynamical Models

We report a dynamical determination of the separate contributions of disk and dark halo masses to the rotation curve of a spiral galaxy. We use fluid-dynamical models of gas flow in the barred galaxy NGC 4123 to constrain the dynamical properties of the galaxy: disk M/L, bar pattern speed, and the central density and scale radius of the dark halo. We derive a realistic barred potential directly from the light distribution. For each model we assume a value of the stellar M/L and a bar pattern speed Omega_p and add a dark halo to fit the rotation curve. We then compute the gas flow velocities with a 2-D gas dynamical code, and compare the model flow patterns to a 2-D velocity field derived from Fabry-Perot observations. The strong shocks and non-circular motions in the observed gas flow require a high stellar M/L and a fast-rotating bar. Models with I-band disk M/L of 2.0 -- 2.5 h_75, or 80 -- 100% of the maximum disk value, are highly favored. The corotation radius of the bar must be <= 1.5 times the bar semi-major axis. These results contradict some recent claimed ``universal'' galaxy disk/halo relations, since NGC 4123 is of modest size (rotation curve maximum 145 km/sec, and V_flat = 130 km/sec) yet is quite disk-dominated. The dark halo of NGC 4123 is less concentrated than favored by current models of dark halos based on cosmological simulations. Since some 30% of bright disk galaxies are strongly barred and have dust lanes indicating shock morphology similar to that of NGC 4123, it is likely that they also have high stellar M/L and low density halos. We suggest that luminous matter dominates inside the optical radius R_25 of high surface brightness disk galaxies.Comment: accepted by ApJ, 20 pages, 11 figures (2 color), uses emulateapj.sty, onecolfloat.st

Applying two-photon excitation fluorescence lifetime imaging microscopy to study photosynthesis in plant leaves

This study investigates to which extent two-photon excitation (TPE) fluorescence lifetime imaging microscopy can be applied to study picosecond fluorescence kinetics of individual chloroplasts in leaves. Using femtosecond 860 nm excitation pulses, fluorescence lifetimes can be measured in leaves of Arabidopsis thaliana and Alocasia wentii under excitation-annihilation free conditions, both for the F0- and the Fm-state. The corresponding average lifetimes are ~250 ps and ~1.5 ns, respectively, similar to those of isolated chloroplasts. These values appear to be the same for chloroplasts in the top, middle, and bottom layer of the leaves. With the spatial resolution of ~500 nm in the focal (xy) plane and 2 μm in the z direction, it appears to be impossible to fully resolve the grana stacks and stroma lamellae, but variations in the fluorescence lifetimes, and thus of the composition on a pixel-to-pixel base can be observed

An Introduction to Gas Accretion onto Galaxies

Evidence for gas accretion onto galaxies can be found throughout the universe. In this chapter, I summarize the direct and indirect signatures of this process and discuss the primary sources. The evidence for gas accretion includes the star formation rates and metallicities of galaxies, the evolution of the cold gas content of the universe with time, numerous indirect indicators for individual galaxies, and a few direct detections of inflow. The primary sources of gas accretion are the intergalactic medium, satellite gas and feedback material. There is support for each of these sources from observations and simulations, but the methods with which the fuel ultimately settles in to form stars remain murky.Comment: 14 pages, 5 figures, Invited review to appear in Gas Accretion onto Galaxies, Astrophysics and Space Science Library, eds. A. J. Fox & R. Dav\'e, to be published by Springe