Probing the shape and history of the Milky Way halo with orbital spectral analysis

Accurate phase-space coordinates (three components of position and velocity) of individual stars are rapidly becoming available with current and future resolved star surveys. These data will enable the computation of the full three-dimensional orbits of tens of thousands of stars in the Milky Way’s stellar halo. We demonstrate that the analysis of stellar halo orbits in frequency space can be used to construct a ‘frequency map’ which provides a highly compact, yet intuitively informative way to represent the six-dimensional halo phase-space distribution function. This representation readily reveals the most important major orbit families in the halo, and the relative abundances of the different orbit families, which in turn reflect the shape and orientation of the dark matter halo relative to the disc. We demonstrate the value of frequency space orbit analysis by applying the method to halo orbits in a series of controlled simulations of disc galaxies. We show that the disc influences the shape of the inner halo making it nearly oblate, but the outer halo remains largely unaffected. Since the shape of the halo varies with radius, the frequency map provides a more versatile way to identify major and minor orbit families than traditional orbit classification schemes. Although the shape of the halo varies with radius, frequency maps of local samples of halo orbits confined to the inner halo contain most of the information about the global shape of the halo and its major orbit families. Frequency maps show that adiabatic growth of a disc traps halo orbits in numerous resonant orbit families (i.e. having commensurable frequencies). The locations and strengths of these resonant families are determined by both the global shape of the halo and its stellar distribution function. If a good estimate of the Galactic potential in the inner halo (within ∼ 50 kpc) is available, the appearance of strong, stable resonances in frequency maps of halo orbits will allow us to determine the degree of resonant trapping induced by the disc potential. We show that if the Galactic potential is not known exactly, a measure of the diffusion rate of a large sample of ∼ 104 halo orbits can help distinguish between the true potential and an incorrect potential. The orbital spectral analysis methods described in this paper provide a strong complementarity to existing methods for constraining the potential of the Milky Way halo and its stellar distribution function

Ion condensation on charged patterned surfaces

We study ion condensation onto a patterned surface of alternating charges. The competition between self-energy and ion-surface interactions leads to the formation of ionic crystalline structures at low temperatures. We consider different arrangements of underlying ionic crystals, including single ion adsorption, as well as the formation of dipoles at the interface between charged domains. Molecular dynamic simulation illustrates existence of single and mixed phases. Our results contribute to understanding pattern recognition, and molecular separation and synthesis near patterned surfaces.Comment: 3 figure

Clinico-radiological and histopathological study of ovarian masses at a tertiary care centre

Background: Counselling and rapid referral to a specialised facility might be improved with the use of a scoring system that could diagnose ovarian cancer. The relative simplicity of the Risk of Malignancy Index (RMI) scoring technique and the ease with which it may be applied make it a strong candidate to use as a primary diagnostic tool for individuals with pelvic masses. Methods: Prospective observations study conducted on women diagnosed with ovarian mass by clinical examination and confirmed by ultrasonography, undergoing surgery at RL Jalappa Hospital, Kolar from January 2021 to December 2022. Histopathological report was considered as Primary outcome parameter. Age group, Parity, Menstrual history, Risk Malignancy Index, etc., were considered as explanatory parameters. Results: A total of 40 subjects are included among which 22.50% are aged ≤40 years and 77.50% are aged >40 years. Using a cut off of 25, majority (88.2%) of those with malignancy had RMI≥25 and in benign histopathology report 56.5% had ≥25 RMI. Histopathology report, there was a statistically significant (p<0.05) difference in RMI values. The RMI had a sensitivity of 88.24% in predicting malignancy with specificity 43.48%, positive predictive value 53.57%, negative predictive value 83.33% with a total diagnostic accuracy of 62.50%. Conclusions: Results from RMI and histopathology correlate positively. The results of this research show that RMI is a reliable and practicable method for assessing patients with pelvic masses at the commencement of therapy and identifying those who are good candidates for centralised surgical treatment

Imprints of radial migration on the Milky Way’s metallicity distribution functions

Recent analysis of the SDSS-III/Apache Point Observatory Galactic Evolution Experiment (APOGEE) Data Release 12 stellar catalog has revealed that the Milky Way’s (MW) metallicity distribution function (MDF) changes shape as a function of radius, transitioning from being negatively skewed at small Galactocentric radii to positively skewed at large Galactocentric radii. Using a high-resolution, N-body+SPH simulation, we show that the changing skewness arises from radial migration—metal-rich stars form in the inner disk and subsequently migrate to the metal-poorer outer disk. These migrated stars represent a large fraction (>50%) of the stars in the outer disk; they populate the high-metallicity tail of the MDFs and are, in general, more metal-rich than the surrounding outer disk gas. The simulation also reproduces another surprising APOGEE result: the spatially invariant high-[α/Fe] MDFs. This arises in the simulation from the migration of a population formed within a narrow range of radii (3.2 ±1.2 kpc) and time (8.8 ± 0.6 Gyr ago), rather than from spatially extended star formation in a homogeneous medium at early times. These results point toward the crucial role radial migration has played in shaping our MW

Effect of obesity on knee joint biomechanics during gait in young adults

This article is MacLean, K. F. E., Callaghan, J. P., & Maly, M. R. (2016). Effect of obesity on knee joint biomechanics during gait in young adults. Cogent Medicine, 3(1). https://doi.org/10.1080/2331205X.2016.1173778While there are many comorbidities associated with obesity, one of the more poorly understood is knee osteoarthritis through obesity. The purpose of this study was to compare the kinematics and kinetics of gait and cumulative knee adductor load, which represents the sum of repetitive exposures to medial knee loading during daily activity, between young obese adults with young, healthy-weight adults. Eight obese and eight healthy-weight young adults participated. Data from a three-dimensional motion capture system and a synchronized floor-mounted force plate were collected during gait trials. Participants wore accelerometers to determine step counts for seven consecutive days. Dependent t-tests were used to identify differences in gait kinematics, kinetics and cumulative knee adductor load between groups. Compared to the healthy-weight participants, obese young adults demonstrated a slower walking speed, greater stance duration, less knee flexion at heel contact, greater knee adduction in early stance and less knee abduction at terminal stance (p < 0.05). The obese young adults had a greater external knee extension moment (p < 0.05) and external rotation moment (p < 0.05) in early stance. The obese group had a greater cumulative knee adductor load. These results provide insight into a potential pathway by which obesity predisposes a healthy young adult for knee osteoarthritis.This research is supported by Canada Research Chairs, Canadian Institutes of Health Research, and Natural Sciences and Engineering Research Council of Canad

Dating martian climate change

Geological evidence indicates that low-latitude polygonally-patterned grounds on Mars, generally thought to be the product of flood volcanism, are periglacial in nature and record a complex signal of changing climate. By studying the martian surface stratigraphically (in terms of the geometrical relations between surface landforms and the substrate) rather than genetically (by form analogy with Earth), we have identified dynamic surfaces across one fifth of martian longitude. New stratigraphical observations in the Elysium-Amazonis plains have revealed a progressive surface polygonisation that is destructive of impact craters across the region. This activity is comparable to the climatically-driven degradation of periglacial landscapes on Earth, but because it affects impact craters – the martian chronometer – it can be dated. Here we show that it is possible to directly date this activity based on the fraction of impact craters affected by polygon formation. Nearly 100% of craters (of all diameters) are superposed by polygonal sculpture: considering the few-100 Ma age of the substrate, this suggests that the process of polygon formation was active within the last few million years. Surface polygonisation in this region, often considered to be one of the signs of young, 'plains-forming' volcanism on Mars, is instead shown to postdate the majority of impact craters seen. We therefore conclude that it is post-depositional in origin and an artifact of thermal cycling of near-surface ground ice. Stratigraphically-controlled crater counts present the first way of dating climate change on a planet other than Earth: a record that may tell us something about climate change on our own planet. Parallel climate change on these two worlds – an ice age Mars coincident with Earth's glacial Quaternary period – might suggest a coupled system linking both. We have previously been unable to generalise about the causes of long-term climate change based on a single terrestrial example – with the beginnings of a chronology for climate change on our nearest planetary neighbour, we can

CONTROLLED RELEASE FLOATING ORAL IN SITU GEL OF ITOPRIDE HYDROCHLORIDE USING PH SENSITIVE POLYMER

Objective: In situ gels are suitable to overcome problems of immediate release and short gastrointestinal residence of liquids. These systems are liquids before administration and on contact with gastric contents are converted to gel. The present work deals with the formulation, evaluation and optimization of pH triggered floating oral in situ gel of Itopride hydrochloride by using sodium alginate as a gelling polymer and HPMC K100M as a release retardant polymer. Methods: A 32 factorial designs was carried out and the effect of variation in concentrations of sodium alginate and calcium carbonate on percent drug release at 1 h, 6 h, gel strength and T50% i. e. time required for the release 50 % of loaded drug was evaluated. The gels were studied for their viscosity, in vitro buoyancy and drug release, in vitro gelling capacity, density, gel strength. Results: The results of a 32 full factorial design revealed that the concentration of sodium alginate and concentration of calcium carbonate significantly affected the dependent variables. A controlled release profile was observed for these formulations. The dissolution data were fitted to various kinetic models which indicated diffusion controlled release profile. In vivo studies revealed higher Tmax of gel compared to plain drug which is suggestive of slower absorption. However, the AUC0-12 h was found to be nearly 90% higher than plain drug. Thus, bioavailability was found to be increased with in situ gel of Itopride hydrochloride. Conclusion: Floating oral in situ gelling system of amoxicillin can be formulated using sodium alginate as a gelling polymer to sustain the drug release for 12 h with diffusion controlled release kinetics