Close encounters involving free-floating planets in star clusters

Instabilities in planetary systems can result in the ejection of planets from their host system, resulting in free-floating planets (FFPs). If this occurs in a star cluster, the FFP may remain bound to the star cluster for some time and interact with the other cluster members until it is ejected. Here, we use $N$-body simulations to characterise close star-planet and planet-planet encounters and the dynamical fate of the FFP population in star clusters containing $500-2000$ single or binary star members. We find that FFPs ejected from their planetary system at low velocities typically leave the star cluster 40% earlier than their host stars, and experience tens of close ($<1000$ AU) encounters with other stars and planets before they escape. The fraction of FFPs that experiences a close encounter depends on both the stellar density and the initial velocity distribution of the FFPs. Approximately half of the close encounters occur within the first 30 Myr, and only 10% occur after 100 Myr. The periastron velocity distribution for all encounters is well-described by a modified Maxwell-Bolzmann distribution, and the periastron distance distribution is linear over almost the entire range of distances considered, and flattens off for very close encounters due to strong gravitational focusing. Close encounters with FFPs can perturb existing planetary systems and their debris structures, and they can result in re-capture of FFPs. In addition, these FFP populations may be observed in young star clusters in imaging surveys; a comparison between observations and dynamical predictions may provide clues to the early phases of stellar and planetary dynamics in star clusters.Comment: Accepted for publication in MNRAS; 18 pages, 12 figure

Low Cost Dewatering of Waste Slurries

The U.S. Bureau of Mines has developed a technique for dewatering mineral waste slurries which utilizes polymer and a static screen. A variety of waste slurries from placer gold mines and crushed stone operations have been successfully treated using the system. Depending on the waste, a number of polymers have been used successfully with polymer costs ranging from $0.05 to$0.15 per 1,000 gal treated. The dewatering is accomplished using screens made from either ordinary window screen or wedge wire. The screens used are 8 ft wide and 8 ft long. The capacity of the screens varies from 3 to 7 gpm/sq. ft. The water produced is acceptable for recycling to the plant or for discharge to the environment. For example, a fine grain dolomite waste slurry produced from a crushed stone operation was dewatered from a nominal 2.5 pct solids to greater than 50 pct solids using $0.10 to$0.15 worth of polymer per 1,000 gal of slurry. The resulting waste water had a turbidity of less than 50 NTU and could be discharged or recycled. The paper describes field tests conducted using the polymer-screen dewatering system

Long-term stability of the HR 8799 planetary system without resonant lock

HR 8799 is a star accompanied by four massive planets on wide orbits. The observed planetary configuration has been shown to be unstable on a timescale much shorter than the estimated age of the system (~ 30 Myr) unless the planets are locked into mean motion resonances. This condition is characterised by small-amplitude libration of one or more resonant angles that stabilise the system by preventing close encounters. We simulate planetary systems similar to the HR 8799 planetary system, exploring the parameter space in separation between the orbits, planetary masses and distance from the Sun to the star. We find systems that look like HR 8799 and remain stable for longer than the estimated age of HR 8799. None of our systems are forced into resonances. We find, with nominal masses and in a narrow range of orbit separations, that 5 of 100 systems match the observations and lifetime. Considering a broad range of orbit separations, we find 12 of 900 similar systems. The systems survive significantly longer because of their slightly increased initial orbit separations compared to assuming circular orbits from the observed positions. A small increase in separation leads to a significant increase in survival time. The low eccentricity the orbits develop from gravitational interaction is enough for the planets to match the observations. With lower masses, but still comfortably within the estimated planet mass uncertainty, we find 18 of 100 matching and long-lived systems in a narrow orbital separation range. In the broad separation range, we find 82 of 900 matching systems. Our results imply that the planets in the HR 8799 system do not have to be in strong mean motion resonances.Comment: Accepted for publication in A&

Feline hypersomatotropism and acromegaly tumorigenesis: a potential role for the AIP gene

Acromegaly in humans is usually sporadic, however up to 20% of familial isolated pituitary adenomas are caused by germline sequence variants of the aryl-hydrocarbon-receptor interacting protein (AIP) gene. Feline acromegaly has similarities to human acromegalic families with AIP mutations. The aim of this study was to sequence the feline AIP gene, identify sequence variants and compare the AIP gene sequence between feline acromegalic and control cats, and in acromegalic siblings. The feline AIP gene was amplified through PCR using whole blood genomic DNA from 10 acromegalic and 10 control cats, and 3 sibling pairs affected by acromegaly. PCR products were sequenced and compared with the published predicted feline AIP gene. A single nonsynonymous SNP was identified in exon 1 (AIP:c.9T > G) of two acromegalic cats and none of the control cats, as well as both members of one sibling pair. The region of this SNP is considered essential for the interaction of the AIP protein with its receptor. This sequence variant has not previously been reported in humans. Two additional synonymous sequence variants were identified (AIP:c.481C > T and AIP:c.826C > T). This is the first molecular study to investigate a potential genetic cause of feline acromegaly and identified a nonsynonymous AIP single nucleotide polymorphism in 20% of the acromegalic cat population evaluated, as well as in one of the sibling pairs evaluated

Gravitational scattering of stars and clusters and the heating of the Galactic disk

Could the velocity spread, increasing with time, in the Galactic disk be explained as a result of gravitational interactions of stars with giant molecular clouds (GMCs) and spiral arms? Do the old open clusters high above the Galactic plane provide clues to this question? We explore the effects on stellar orbits of scattering by inhomogeneities in the Galactic potential due to GMCs, spiral arms and the Galactic bar, and whether high-altitude clusters could have formed in orbits closer to the Galactic plane and later been scattered. Simulations of test-particle motions are performed in a realistic Galactic potential. The effects of the internal structure of GMCs are explored. The destruction of clusters in GMC collisions is treated in detail with N-body simulations of the clusters. The observed velocity dispersions of stars as a function of time are well reproduced. The GMC structure is found to be significant, but adequate models produce considerable scattering effects. The fraction of simulated massive old open clusters, scattered into orbits with |z| > 400 pc, is typically 0:5%, in agreement with the observed number of high-altitude clusters and consistent with the present formation rate of massive open clusters. The heating of the thin Galactic disk is well explained by gravitational scattering by GMCs and spiral arms, if the local correlation between the GMC mass and the corresponding voids in the gas is not very strong. Our results suggest that the high-altitude metal-rich clusters were formed in orbits close to the Galactic plane and later scattered to higher orbits. It is possible, though not very probable, that the Sun formed in such a cluster before scattering occurred.Comment: 19 pages, 15 figure

Serum N-Terminal Type III Procollagen Propeptide: An Indicator of Growth Hormone Excess and Response to Treatment in Feline Hypersomatotropism

BACKGROUND: N‐terminal type III procollagen propeptide (PIIINP) is a biomarker of soft tissue proliferation. Hypersomatotropism (HS) is associated with soft tissue proliferation. HYPOTHESIS: Serum PIIINP is increased in cats with HS and decreases with effective treatment, and may be an additional tool in the diagnosis and treatment of feline HS. ANIMALS: Cats with uncomplicated diabetes mellitus (DM; n = 30) and with HS‐induced DM (HSDM; n = 30). Pre‐ and posttreatment samples were available from 5 cats undergoing radiotherapy (RT) and 16 cats undergoing hypophysectomy (HPX). METHODS: Retrospective and prospective cross‐sectional study. Analytical performance of a serum PIIINP ELISA was assessed and validated for use in cats. PIIINP and insulin‐like growth factor 1 (IGF‐1) radioimmunoassays (RIA) were performed pre‐ and post‐treatment in cats with DM and HSDM. PIIINP and IGF‐1 were compared between cats treated by RT and HPX. RESULTS: Serum PIIINP concentrations were significantly higher (P < .001) in HSDM cats (median, 19.6 ng/mL; range, 1.7–27.9) compared to DM cats (median, 5.0 ng/mL; range, 2.1–10.4). A cut‐off of 10.5 ng/mL allowed differentiation between DM and HSDM cats with 87% sensitivity and 100% specificity (area under the curve [AUC], 0.91; 95% confidence interval [CI], 0.82‐1). After RT, PIIINP increased significantly (P = .043) with no significant change in IGF‐1 concentrations. After HPX, serum PIIINP (P = .034) and IGF‐1 concentrations (P < .001) decreased significantly. CONCLUSION AND CLINICAL IMPORTANCE: PIIINP concentrations are increased in cats with untreated HSDM compared to those with DM, demonstrating the effect of excess GH on soft tissue. PIIINP concentrations decreased after HPX in most HSDM cats

Approaches to canine health surveillance

Effective canine health surveillance systems can be used to monitor disease in the general population, prioritise disorders for strategic control and focus clinical research, and to evaluate the success of these measures. The key attributes for optimal data collection systems that support canine disease surveillance are representativeness of the general population, validity of disorder data and sustainability. Limitations in these areas present as selection bias, misclassification bias and discontinuation of the system respectively. Canine health data sources are reviewed to identify their strengths and weaknesses for supporting effective canine health surveillance. Insurance data benefit from large and well-defined denominator populations but are limited by selection bias relating to the clinical events claimed and animals covered. Veterinary referral clinical data offer good reliability for diagnoses but are limited by referral bias for the disorders and animals included. Primary-care practice data have the advantage of excellent representation of the general dog population and recording at the point of care by veterinary professionals but may encounter misclassification problems and technical difficulties related to management and analysis of large datasets. Questionnaire surveys offer speed and low cost but may suffer from low response rates, poor data validation, recall bias and ill-defined denominator population information. Canine health scheme data benefit from well-characterised disorder and animal data but reflect selection bias during the voluntary submissions process. Formal UK passive surveillance systems are limited by chronic under-reporting and selection bias. It is concluded that active collection systems using secondary health data provide the optimal resource for canine health surveillance

Demography and health of Pugs under primary veterinary care in England

BACKGROUND: The Pug is an ancient dog breed and was the fifth most commonly registered UK pedigree breed in 2014. However, the breed has been reported to be predisposed to several disorders including ocular, respiratory and dermatological problems. The VetCompass Programme collates de-identified clinical data from primary-care veterinary practices in the UK for epidemiological research. Using VetCompass clinical data, this study aimed to characterise the demography and common disorders of the general population of Pugs under veterinary care in England. RESULTS: Pugs comprised 2709 (1.03 %) of 264,260 study dogs under veterinary care from September 1(st), 2009 to 30(th) April, 2015. Annual proportional birth rates showed that Pugs rose from less than 1 % of annual birth cohorts before 2008 to comprise 2.8 % of the 2013 annual birth cohort. The most common colours of Pugs were fawn (63.1 %), black (27.7 %), apricot (7.6 %) and silver (2.1 %). Of the 1009 pugs under veterinary care in the study during 2013, 688 (68.19 %) had at least one disorder recorded. The most prevalent disorders recorded overall were overweight/obesity (number of events: 133, prevalence: 13.18 %, 95 % CI: 11.12–15.43), corneal disorder (88, 8.72 %, 95 % CI: 7.05–10.63) and otitis externa (76, 7.53 %, 95 % CI: 5.98–9.34). The most prevalent disorder groups were ophthalmological (n = 164, prevalence: 16.25 %, 95 % CI: 14.03–18.68), dermatological (157, 15.60 %, 95 % CI: 13.38–17.95) and aural (152, 15.06 %, 95 % CI: 12.91–17.42). The most prevalent body locations affected were the head-and-neck (n = 439, prevalence = 43.51 %, 95 % CI: 40.42–46.63) and abdomen (195, 19.33 %, 95 % CI: 16.93–21.90). The most prevalent organ systems affected were the integument (321, 31.81 %, 95 % CI: 28.15–35.72) and digestive (257, 25.47 %, 95 % CI: 22.54–28.65). The most prevalent pathophysiologic processes recorded were inflammation (386, 38.26 %, 95 % CI: 34.39–42.27) and congenital/developmental (153, 15.16 %, 95 % CI: 12.61–18.13). CONCLUSIONS: Ownership of Pugs in England is rising steeply. Overweight/obesity, corneal disorder and otitis externa are the most common disorders in Pugs. Identification of health priorities based on VetComapss data can support evidence–based reforms to improve health and welfare within the breed. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s40575-016-0035-z) contains supplementary material, which is available to authorized users