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Glaucoma is the leading cause of irreversible blindness in the world, currently impacting 80 million people. Patients suffering from primary open-angle glaucoma experience aqueous humor accumulatio...

While typical patterns of osteoid osteoma have been described on CT, MRI findings can overlap among different diseases, and atypical patterns exist. In this study, we assessed the presence of a novel dark rim sign and its utility in the MRI diagnosis of osteoid osteoma. The purpose of this retrospective study was to assess the utility of the dark rim sign seen on MRI in children with osteoid osteoma. MRI studies from 36 pediatric patients with osteoid osteoma and a control group of patients with either osteomyelitis or stress fracture were analyzed and then compared for the presence of the dark rim sign. Patients from the osteoid osteoma group were further divided based on nidus location and evaluated for the presence of the dark rim sign. The relationship between the dark rim sign and osteoid osteoma was statistically significant (P

Health disparities are defined on the basis of specific populations that, when compared to the general population, have a significant disparity on the rate of disease incidence, prevalence, morbidity, mortality, or survival. People that experience health disparities can be defined by multiple criteria. As the diversity of the United States broadens and increases, research on the origins and causes of health disparities becomes more important to support a healthy general population. Children are particularly sensitive to and vulnerable to health disparities due to the potentially life long consequences of events during periods of critical organ, intellectual and social development. The concept of health justice whereby each individual has the opportunity to realize their full health potential can only be realized with proper understanding and relevant data to frame practice, policy and actions. The National Children's Study (NCS) was a longitudinal birth cohort study designed to incorporate the principles of the Federal Collaboration on Health Disparities Research in consultation with subject matter experts, community representatives, and ongoing evaluation to ensure high quality and relevant data on factors that impact health outcomes. The NCS developed and tested a model of enrolling a diverse population, capturing and integrating data using a life course framework, constructing individual profiles, then aggregating individuals into groups based on profiles and outcomes. This approach is applicable to other longitudinal cohort studies.

Background: Personal and professional biases can affect decision-making regarding important issues in pediatric sports medicine. Gaining insight into the opinions of health care professionals who specialize in pediatric sports medicine will provide information that may be useful for directing ongoing research in this field. Hypothesis: It was hypothesized that surgeons would demonstrate bias toward early surgical intervention versus nonsurgeons. In addition, it was hypothesized that youth sports medicine professionals who were parents of a child with a previous major sports injury or concussion would be less likely to allow their child to play American tackle football or return to football after a concussion. Study Design: Cross-sectional study. Methods: An online survey was provided to the active members of the Pediatric Research in Sports Medicine Society. We used both professional background information and responses to questions related to personal experiences with youth sports injuries to determine potential factors associated with underlying biases. Survey responses among subgroups were compared using the Fisher exact test. The Pearson correlation coefficient was used to evaluate years in practice versus opioid use. Results: Of the survey participants, 62.5% were pediatric surgeons, and 37.5% represented different nonsurgical youth sports medicine professions. Surgeons were less likely than nonsurgeons to agree to allow their child to return to football after sustaining a concussion and completing a concussion protocol (48% vs 76%, P = .013). Surgeons were more likely than nonsurgeons to agree to both elective shoulder stabilization after a first-time dislocation and elective drilling of a stable knee osteochondritis dissecans (OCD) before nonoperative treatment (41% vs 10%, P = .003 and 52% vs 23%, P = .013, respectively). Those who reported having a child with a concussion history were more likely to support him or her returning to football after a concussion (65% vs 33%, P = .026). Conclusion: Surgeons were more likely to favor elective shoulder-stabilization surgery after a first-time dislocation and drilling of a stable knee OCD instead of nonoperative management. Personal experience of having a child who sustained a major sports injury or concussion did not demonstrate a bias against participation in football or return to football after a concussion.

Background Graft choice for pediatric anterior cruciate ligament reconstruction (ACLR) is determined by several factors. There is limited information on the use and outcomes of allograft ACLR in pediatric patients. The purpose of this systematic review and meta-analysis was to quantify reported failure rates of allograft versus autograft ACLR in patients ≤19 years of age with ≥2 years of follow-up. We hypothesized that there would be higher rates of failure for allograft compared with autograft ACLR in this population. Methods PubMed/MEDLINE and Embase databases were systematically searched for literature regarding allograft and autograft ACLR in pediatric/adolescent patients. Articles were included if they described a cohort of patients with average age of ≤19 years, had a minimum of 2 years of follow-up, described graft failure as an outcome, and had a Level of Evidence grade of I to III. Qualitative review and quantitative meta-analysis were performed to compare graft failure rates. A random-effects model was created to compare failure events in patients receiving allograft versus autograft in a pairwise fashion. Data analysis was completed using RevMan 5.3 software (The Cochrane Collaboration). Results The database search identified 1,604 studies; 203 full-text articles were assessed for eligibility. Fourteen studies met the inclusion criteria for qualitative review; 5 studies were included for quantitative meta-analysis. Bone-patellar tendon-bone (BTB) represented 58.2% (n = 1,012) of the autografts, and hamstring grafts represented 41.8% (n = 727). Hybrid allografts (autograft + supplemental allograft) represented 12.8% (n = 18) of all allograft ACLRs (n = 141). The unweighted, pooled failure rate for each graft type was 8.5% for BTB, 16.6% for hamstring, and 25.5% for allograft. Allografts were significantly more likely than autografts to result in graft failure (odds ratio, 3.87; 95% confidence interval, 2.24 to 6.69). Conclusions Allograft ACLR in pediatric and adolescent patients should be used judiciously, as existing studies revealed a significantly higher failure rate for allograft compared with autograft ACLR in this patient population. Additional studies are needed to improve the understanding of variables associated with the high ACLR failure rate among pediatric and adolescent patients. Level of evidence Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Purpose: Identify biases on controversial issues in pediatric sports medicine from the perspective of pediatric sports medicine professionals involved in multiple disciplines. Methods: An online survey on controversial issues in pediatric sports medicine was provided to the active members of the Pediatric Research in Sports Medicine (PRiSM) Society, which is a multidisciplinary organization that includes physicians and non-physicians interested in pediatric sports medicine research. Both the professional background of the respondents and their responses to questions related to personal experiences with youth sports injuries were used to …

Osteoid osteoma (OO) is a benign bone neoplasm consisting of a central prostaglandin-secreting nidus surrounded by a zone of reactive sclerosis. The diagnosis is suspected in children and young adults with longstanding nighttime pain that is relieved by salicylates or nonsteroidal anti-inflammatory drugs. Early studies suggested that computed tomography had a higher sensitivity and specificity in the diagnosis of OO compared to magnetic resonance imaging (MRI). More recent literature suggests MRI done with dynamic postcontrast imaging to be equal to or slightly better at detecting the nidus of OOs, particularly the ones in atypical locations. Being able to evaluate for OO utilizing MRI is important given that the majority of these lesions occur in younger patients, in whom there is greater concern to limit ionizing radiation. Furthermore, patients with atypical OOs often receive an MRI if radiographs are not suggestive of the diagnosis. Therefore, it is important for radiologists to be aware of the imaging features that can help make the diagnosis on MRI.

Introduction/Background: Lateral discoid meniscus (LDM) is the most common congenital anomaly of the knee. Due to the significant heterogeneity in pathomorphology, LDM treatment remains challenging. Treatment approaches and surgical techniques vary widely among surgeons and different types of LDM. Current classification systems inadequately describe the spectrum of pathology or dictate treatment. Hypothesis/Purpose: The Pediatric Research in Sports Medicine (PRISM) meniscal study group developed and tested the reliability of a novel classification system designed to comprehensively capture the intricacies of LDM pathomorphology and guide treatment decisions. Methods: The PRISM LDM Classification System was developed through an initial review of existing classification systems followed by group consensus method by pediatric meniscal surgeons from 20 tertiary academic centers. Four factors were evaluated: (1) meniscal width (surface area), (2) meniscal height (thickness, +/- horizontal delamination), (3) peripheral stability (and instability pattern), and (4) tearing (and tear location)(Table 1). A stepwise arthroscopic exam utilizing two standard anterior viewing portals was established for optimizing diagnosis of LDM features. From a set of 101 arthroscopic videos submitted for review, 41 were selected for quality by 3 of the authors (non-’readers’). Five ‘readers’ then performed assessments using the classification system. Interobserver reliability of the primary and secondary rating factors was assessed using the Fleiss kappa coefficient (K, 95% CI), designed for multiple readers with nominal variables (Reliability Classification: Fair 0.21-0.40 fair, Moderate 0.41-0.60, Substantial 0.61-0.80, and Excellent 0.80-1.00). Results: The majority of the primary and secondary rating factors demonstrated ‘substantial’ reliability, such as meniscal width (complete vs. incomplete, K 0.609; 0.512-0.706) and posterior horn stability (stable vs. unstable, K 0.693; 0.594-0.792), or ‘moderate’ reliability, such as meniscal height (normal vs. abnormal, K 0.444; 0.347-0.541), overall stability, (stable vs. unstable, K 0.569; 0.472-0.666), and tear presence (tear vs. no tear, K 0.541; 0.444-0.638). Several features demonstrated only ‘fair’ agreement, including anterior horn stability (stable vs. unstable, K 0.358; 0.258-0.457), meniscal body stability (stable vs. unstable, K 0.314; 0.214-0.413), and tear type (no tear, radial, vertical, complex, K 0.386; 0.325-0.446). Conclusion/Discussion: A novel classification system that more comprehensively and descriptively characterizes the spectrum of LDM pathology demonstrated moderate or substantial agreement in most diagnostic categories analyzed. Specific features demonstrating fair agreement may warrant investigation of alternative steps in the arthroscopic exam or descriptors to improve agreement. A comprehensive classification system is critical to advance LDM research from single-center, level 4 studies to prospective multicenter efforts that will enhance improve communication, research, and evidence-based treatment of LDM pathology.

Background: Effective pain management for anterior cruciate ligament (ACL) reconstruction may improve both patient satisfaction and function. However, there is limited data supporting clear guidelines regarding pain management for ACL reconstruction in the pediatric population. Hypothesis/Purpose: The purpose of this study is to survey current pain management practices for ACL reconstruction among pediatric orthopaedic surgeons. Methods: A cross-sectional survey study was conducted in which orthopaedic surgeons were asked about their pain management practices for pediatric ACL reconstruction. The voluntary survey was sent to members of the Pediatric Orthopaedic Society of North America (POSNA). Inclusion criteria were performs ACL repair or reconstruction on patients under age eighteen and willing to participate in the survey. Responses were anonymous and consisted of demographics, training, current practice, and pain management strategies. Survey data were assessed using descriptive statistics, Pearson’s chi-squared test and Fisher’s exact test for categorical variables, and two-sample t-test for continuous variables. Results: There were 77 responses, of which 64 fit the inclusion criteria. The average age of respondents was 48.9 years, 84.4% were male, and 31.3% practiced in the southern region of the US (Table 1). 39.1% of respondents utilized preemptive analgesia, 90.6% utilized perioperative blocks, 82.8% routinely advocated for scheduled non-narcotic medications post-operatively, and 93.8% recommended cryotherapy post-operatively (Table 2). Respondents that reported not using a peri-operative block and not advocating for scheduled non-narcotic pain management post-operatively were older on average than those that did (57.6 vs. 47.7 years, p=0.04; 56.7 vs. 47.0 years, p20 opioid pills, and 10.9% did not prescribe opioid pain medication at all. In total, 89.1% of respondents reported prescribing opioid pain medication post-operatively, however, only 59.4% reported counseling patients on appropriate disposal of extra pills. Prior training or experience was more frequently reported than published research as a primary factor influencing pain management protocols. Conclusion: Significant variability exists in pain management practices in pediatric ACL reconstruction. There is a need for more evidence-based practice guidelines regarding pain management. [Table: see text][Table: see text]

Cardiac catheters are a vital tool in medicine due to their widespread use in many minimally invasive procedures. To aid in advancing the catheter within the patient's vasculature, many catheters are coated with a lubricious hydrophilic coating (HPC). Although HPCs benefit patients, their delamination during use is a serious safety concern. Adverse health effects associated with HPC delamination include pulmonary and myocardial embolism, embolic stroke, infarction, and death. In order to improve patient outcomes, more consistent manufacturing methods and improved quality assurance techniques are needed to evaluate HPC medical devices. The present work investigates the efficacy of two novel methods to image and evaluate HPCs post-manufacturing, relative to industry-standard scanning electron microscopy (SEM)-based methods. We have shown that novel evaluation approaches based on optical microscopy (OM) and optical coherence tomography (OCT) are capable of imaging HPC layers and quantifying HPC thickness, saving hours of time relative to SEM sample preparation and imaging. Additionally, the nondestructive nature of OCT avoids damage and alteration to the HPC prior to imaging, leading to more reliable HPC thickness measurements. Overall, the work demonstrated the feasibility and advantages of using OM and OCT to image and measure HPC thickness relative to industry-standard SEM methods.

In the paper 'NIHAO IV: Core creation and destruction in dark matter density profiles across cosmic time' published in MNRAS main journal, Volume 456, Issue 4, p. 3542-3552, an error in table 2 came to our attention. It appears that there is a mismatch between the values on the second line of table 2 and the corresponding curve in fig. 5. Indeed the parameters given for the fit of the relation between α and Mh are incorrect. We realised that the published parameters correspond to a different fitting formula that was used internally during thiswork and that does not have the right asymptotic behavior when the mass goes to zero. We apologize for this mistake. (Table presented) The correct fitting parameters to reproduce the fitting curve on fig. 5 are given in Table Errata. These parameters were provided only to allow the reader to reproduce our work and therefore this error does not affect our conclusions.

We use a sample of 83 high-resolution cosmological zoom-in simulations and a semi-analytic model (SAM) to study the stochasticity of galaxy formation in haloes ranging from dwarf to Milky Way masses. Our simulated galaxies reproduce the observed inefficiency of galaxy formation as expressed through the stellar, gas and baryonic Tully-Fisher relations. For HI velocities in the range (70 less than or similar to V less than or similar to 220 km s(-1)), the scatter is just 0.08 to 0.14 dex, consistent with the observed intrinsic scatter at these scales. At low velocities (20 less than or similar to V less than or similar to 70 km s(-1)), the simulated scatter is 0.2-0.25 dex, which could be tested with future observations. The scatter in the stellar mass versus dark halo velocity relation is constant for 30 less than or similar to V less than or similar to 180 km s(-1), and smaller (similar or equal to 0.17 dex) when using the maximum circular velocity of the dark-matter-only simulation, V-max(DMO), compared to the virial velocity (V-200 or V-200(DMO)). The scatter in stellar mass is correlated with halo concentration, and is minimized when using a circular velocity at a fixed fraction of the virial radius similar or equal to 0.4R(200) or with V-alpha = V-200(DMO)(V-max(DMO) / V-200(DMO))(alpha) with alpha similar or equal to 0.7, consistent with constraints from halo clustering. Using the SAM we show the correlation between halo formation time and concentration is essential in order to reproduce this result. This uniformity in galaxy formation efficiency we see in our hydrodynamical simulations and an SAM proves the simplicity and self-regulating nature of galaxy formation in a Lambda cold dark matter (Lambda CDM) universe.

We study the hot and cold circum-galactic medium (CGM) of 86 galaxies of the cosmological, hydrodynamical simulation suite NIHAO. NIHAO allows a study of how the $z=0$ CGM varies across 5 orders of magnitude of stellar mass using OVI and HI as proxies for hot and cold gas. The cool HI covering fraction and column density profiles match observations well, particularly in the inner CGM. OVI shows increasing column densities with mass, a trend seemingly echoed in the observations. As in multiple previous simulations, the OVI column densities in simulations are lower than observed and optically thick HI does not extend as far out as in observations. We take a look at the collisional ionisation fraction of OVI as a function of halo mass. We make observable predictions of the bipolarity of outflows and their effect on the general shape of the CGM. Bipolar outflows can be seen out to around 40 kpc in intermediate and low mass halos ($M_{\mathrm{halo}}, 23 pages, 19 figures, accepted for publication in MNRAS

We compare the Baryonic Tully-Fisher relation (BTFR) of simulations and observations of galaxies ranging from dwarfs to spirals, using various measures of rotational velocity Vrot. We explore the BTFR when measuring Vrot at the flat part of the rotation curve, Vflat, at the extent of HI gas, Vlast, and using 20% (W20) and 50% (W50) of the width of HI line profiles. We also compare with the maximum circular velocity of the parent halo, Vmax, within dark matter only simulations. The different BTFRs increasingly diverge as galaxy mass decreases. Using Vlast one obtains a power law over four orders of magnitude in baryonic mass, with slope similar to the observed BTFR. Measuring Vflat gives similar results as Vlast when galaxies with rising rotation curves are excluded. However, higher rotation velocities would be found for low mass galaxies if the cold gas extended far enough for Vrot to reach a maximum. W20 gives a similar slope as Vlast but with slightly lower values of Vrot for low mass galaxies, although this may depend on the extent of the gas in your galaxy sample. W50 bends away from these other relations toward low velocities at low masses. By contrast, Vmax bends toward high velocities for low mass galaxies, as cold gas does not extend out to the radius at which halos reach Vmax. Our study highlights the need for careful comparisons between observations and models: one needs to be consistent about the particular method of measuring Vrot, and precise about the radius at which velocities are measured., Accepted for publication MNRAS

We study how X-rays from stellar binary systems and the hot intracluster medium (ICM) affect the radiative cooling rates of gas in galaxies. Our study uses a novel implementation of gas cooling in the moving-mesh hydrodynamics code \textsc{arepo}. X-rays from stellar binaries do not affect cooling at all as their emission spectrum is too hard to effectively couple with galactic gas. In contrast, X-rays from the ICM couple well with gas in the temperature range $10^4 - 10^6$ K. Idealised simulations show that the hot halo radiation field has minimal impact on the dynamics of cooling flows in clusters because of the high virial temperature ($> 10^7$K), making the interaction between the gas and incident photons very ineffective. Satellite galaxies in cluster environments, on the other hand, experience a high radiation flux due to the emission from the host halo. Low mass satellites ($< 10^{12}\rm{M_\odot}$) in particular have virial temperatures that are exactly in the regime where the effect of the radiation field is maximal. Idealised simulations of satellite galaxies including only the effect of host halo radiation (no ram pressure stripping or tidal effects) fields show a drastic reduction in the amount of cool gas formed ($\sim 40\%$) on a short timescale of about $0.5$ Gyrs. A galaxy merger simulation including all the other environmental quenching mechanisms, shows about $20\%$ reduction in the stellar mass of the satellite and about $\sim 30\%$ reduction in star formation rate after $1$ Gyr due to the host hot halo radiation field. These results indicate that the hot halo radiation fields potentially play an important role in quenching galaxies in cluster environments., 14 pages, 12 figures, submitted to MNRAS

We use 25 simulated galaxies from the NIHAO project to define and characterize a variety of kinematic stellar structures: thin and thick discs, large scale single discs, classical and pseudo bulges, spheroids, inner discs, and stellar haloes. These structures have masses, spins, shapes and rotational support in good agreement with theoretical expectations and observational data. Above a dark matter halo mass of $2.5\times10^{\rm~11}M_{\rm\odot}$, all galaxies have a classical bulge and 70\% have a thin and thick disc. The kinematic (thin) discs follow a power-law relation between angular momentum and stellar mass $J_{\rm *}=3.4M_{\rm *}^{\rm1.26\pm0.06}$, in very good agreement with the prediction based on the empirical stellar-to-halo mass relation in the same mass range, and show a strong correlation between maximum `observed' rotation velocity and dark matter halo circular velocity $v_{\rm c}=6.4v_{\rm max}^{0.64\pm0.04}$. Tracing back in time these structures' progenitors, we find all to lose a fraction $1-f_j$ of their maximum angular momentum. Thin discs are significantly better at retaining their high-redshift spins ($f_j\sim0.70$) than thick ones ($f_j\sim0.40$). Stellar haloes have their progenitor baryons assembled the latest ($z_{\rm~1/2}\sim1.1$) and over the longest timescales ($\tau\sim6.2$~Gyr), and have the smallest fraction of stars born in-situ ($f_{\rm in-situ}=0.35\pm0.14$). All other structures have $1.5\lesssim z_{\rm1/2}\lesssim3$, $\tau=4\pm2$~Gyr and $f_{\rm in-situ}\gtrsim0.9$., Comment: Accepted by MNRAS. First application of the methods described in arXiv:1804.05576

Given the frequent utilization of devices and implants to provide stability and/or correct deformity, infections complicating orthopedic surgery in children can present management challenges. In these cases it is necessary to ensure both the eradication of infection and the successful healing of the initial orthopedic intervention. This requires a balance between thorough debridement of infected tissue and avoidance of unnecessary surgical procedures and attendant complications. Furthermore, in the skeletally immature child, consideration must be given to ensuring continued optimal growth. Such infections are best managed through a multidisciplinary approach including the orthopedic surgeon, infectious disease specialist, and generalist guided by laboratory data, clinical assessment, and risks/benefits of implant removal.

Purpose: Deep inspiratory breath hold (DIBH) is a technique that has been increasingly utilized over the past several years for the purpose of reducing the radiation dose received by the heart and ipsilateral lung during radiotherapy (RT) for breast cancer. The purpose of this study was to provide a comparative analysis of cardiac and lung dose in patients treated with and without moderate DIBH with an active breathing control (ABC) device during RT for left-sided breast cancer at a community radiation oncology center. Methods: From June 2013 to December 2014, 83 patients with stages 0-III left-sided breast cancer were treated with RT. Of these, 45 patients underwent CT simulation with an ABC device and the remaining 38 patients underwent standard free-breathing CT simulation for RT planning. Twenty-eight patients in the ABC cohort were treated with standard tangent fields and 18 were treated with locoregional RT. The non-ABC cohort included 26 patients treated with standard tangents and 12 treated with locoregional RT. A 4- or 5-field technique was utilized in all locally advanced patients to allow for coverage of the supraclavicular fossa and internal mammary lymph nodes with inclusion of low axillary coverage based on individual risk factors. All patients were treated with 3D-conformal techniques utilizing multi-leaf collimators to block the heart. Comparisons were made between mean heart dose, heart V5, mean lung dose, and lung V5 with and without the use of ABC. Kruskal-Wallis tests were used to determine significance between groups with α for significance set at p ≤0.05. Results: On combined analysis, the use of DIBH with ABC resulted in a reduction in heart V5 (1.5 versus 5.4%; p=0.018). Mean heart dose, mean lung dose, and lung V5 were not significantly improved with the use of ABC. On subgroup analysis, patients treated with locoregional RT had reduced mean heart dose (161 cGy versus 309 cGy; p=0.014) and heart V5 (2.3% versus 14.8%; p Conclusions: The use of ABC provided a significant reduction in heart V5 in all patients with left-sided breast cancer and in mean heart dose and heart V5 in patients treated with locoregional RT. This retrospective, single-institution analysis demonstrates the feasibility of implementing moderate DIBH with ABC technology in the treatment of left-sided breast cancer in a community radiation oncology center. Citation Format: Gogineni ES, Kehrer JD, Jones GC, Premo C, Stinson S. Active breathing control in the management of left-sided breast cancer with irradiation: A dosimetric analysis of cardiac and lung dose. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P3-12-06.

We use the NIHAO simulations to investigate the effects of baryonic physics on the time evolution of Dark Matter central density profiles. The sample is made of $\approx 70$ independent high resolution hydrodynamical simulations of galaxy formation and covers a wide mass range: 1e10< Mhalo, Comment: 11 pages, 13 figures. Corrected typo in table 2 (middle row) with respect to the version published in MNRAS

We explore the chemical distribution of stars in a simulated galaxy. Using simulations of the same initial conditions but with two different feedback schemes (MUGS and MaGICC), we examine the features of the age-metallicity relation (AMR), and the three-dimensional age-metallicity-[O/Fe] distribution, both for the galaxy as a whole and decomposed into disc, bulge, halo, and satellites. The MUGS simulation, which uses traditional supernova feedback, is replete with chemical substructure. This sub- structure is absent from the MaGICC simulation, which includes early feedback from stellar winds, a modified IMF and more efficient feedback. The reduced amount of substructure is due to the almost complete lack of satellites in MaGICC. We identify a significant separation between the bulge and disc AMRs, where the bulge is considerably more metal-rich with a smaller spread in metallicity at any given time than the disc. Our results suggest, however, that identifying the substructure in observations will require exquisite age resolution, on the order of 0.25 Gyr. Certain satellites show exotic features in the AMR, even forming a 'sawtooth' shape of increasing metallicity followed by sharp declines which correspond to pericentric passages. This fact, along with the large spread in stellar age at a given metallicity, compromises the use of metallicity as an age indicator, although alpha abundance provides a more robust clock at early times. This may also impact algorithms that are used to reconstruct star formation histories from resolved stellar populations, which frequently assume a monotonically-increasing AMR., Comment: 25 pages, 14 Figures, 2 Tables. Accepted for publication in MNRAS

We show that the cool gas masses of galactic discs reach a steady state that lasts many Gyr after their last major merger in cosmological hydrodynamic simulations. The mass of disc gas, M$_{\rm gas}$, depends upon a galaxy halo's spin and virial mass, but not upon stellar feedback. Halos with low spin have high star formation efficiency and lower disc gas mass. Similarly, lower stellar feedback leads to more star formation so the gas mass ends up nearly the same irregardless of stellar feedback strength. Even considering spin, the M$_{\rm gas}$ relation with halo mass, M$_{200}$ only shows a factor of 3 scatter. The M$_{\rm gas}$--M$_{200}$ relation show a break at M$_{200}$=$2\times10^{11}$ M$_\odot$ that corresponds to an observed break in the M$_{\rm gas}$--M$_\star$ relation. The constant disc mass stems from a shared halo gas density profile in all the simulated galaxies. In their outer regions, the profiles are isothermal. Where the profile rises above $n=10^{-3}$ cm$^{-3}$, the gas readily cools and the profile steepens. Inside the disc, rotation supports gas with a flatter density profile except where supernova explosions disrupt the disc. Energy injection from stellar feedback also provides pressure support to the halo gas to prevent runaway cooling flows. The resulting constant gas mass makes simpler models for galaxy formation possible, either using a "bathtub" model for star formation rates or when modeling chemical evolution., To be submitted to MNRAS. Comments very welcome in the meantime

We introduce project NIHAO (Numerical Investigation of a Hundred Astrophysical Objects), a set of 100 cosmological zoom-in hydrodynamical simulations performed using the gasoline code, with an improved implementation of the SPH algorithm. The haloes in our study range from dwarf to Milky Way masses, and represent an unbiased sampling of merger histories, concentrations and spin parameters. The particle masses and force softenings are chosen to resolve the mass profile to below 1% of the virial radius at all masses, ensuring that galaxy half-light radii are well resolved. Using the same treatment of star formation and stellar feedback for every object, the simulated galaxies reproduce the observed inefficiency of galaxy formation across cosmic time as expressed through the stellar mass vs halo mass relation, and the star formation rate vs stellar mass relation. We thus conclude that stellar feedback is the chief piece of physics required to limit the efficiency of star formation in galaxies less massive than the Milky Way., 14 pages, 8 figures, accepted for publication in MNRAS

We use cosmological hydrodynamical zoom-in simulations with the SPH code gasoline of four haloes of mass M_{200} \sim 10^{13}\Msun to study the response of the dark matter to elliptical galaxy formation. Our simulations include metallicity dependent gas cooling, star formation, and feedback from massive stars and supernovae, but not active galactic nuclei (AGN). At z=2 the progenitor galaxies have stellar to halo mass ratios consistent with halo abundance matching, assuming a Salpeter initial mass function. However by z=0 the standard runs suffer from the well known overcooling problem, overpredicting the stellar masses by a factor of > 4. To mimic a suppressive halo quenching scenario, in our forced quenching (FQ) simulations, cooling and star formation are switched off at z=2. The resulting z=0 galaxies have stellar masses, sizes and circular velocities close to what is observed. Relative to the control simulations, the dark matter haloes in the FQ simulations have contracted, with central dark matter density slopes d\log��/d\log r \sim -1.5, showing that dry merging alone is unable to fully reverse the contraction that occurs at z>2. Simulations in the literature with AGN feedback however, have found expansion or no net change in the dark matter halo. Thus the response of the dark matter halo to galaxy formation may provide a new test to distinguish between ejective and suppressive quenching mechanisms., 21 pages, 18 figures, accepted to MNRAS

The stellar radial profiles of disk galaxies are often observed to be truncated, or anti-truncated in the galaxies’ outskirts. As of now, the literature about galaxy formation lacks a model for the formation of observed anti-truncated stellar disks which is based on secular processes. We present an attempt to fill this gap. We were able to model anti-truncated disks in numerical SPH simulations of the formation of isolated galaxies. We will show that the stars in the outskirts of the simulated galactic disk are on very eccentric orbits but were formed on circular orbits at much smaller radii. We argue that a strong central bar is the main driver of the formation of such a disk configuration. The model predicts that such outer stellar disks should show very slow rotation, but high radial dispersion. If confirmed, their existence would constitute galaxy disks of qualitatively very new kinematic properties.

The velocity anisotropy parameter, beta, is a measure of the kinematic state of orbits in the stellar halo which holds promise for constraining the merger history of the Milky Way (MW). We determine global trends for beta as a function of radius from three suites of simulations, including accretion only and cosmological hydrodynamic simulations. We find that both types of simulations are consistent and predict strong radial anisotropy (~0.7) for Galactocentric radii greater than 10 kpc. Previous observations of beta for the MW's stellar halo claim a detection of an isotropic or tangential "dip" at r~20 kpc. Using the N-body+SPH simulations, we investigate the temporal persistence, population origin, and severity of "dips" in beta. We find dips in the in situ stellar halo are long-lived, while dips in the accreted stellar halo are short-lived and tied to the recent accretion of satellite material. We also find that a major merger as early as z~1 can result in a present day low (isotropic to tangential) value of beta over a wide range of radii and angular expanse. While all of these mechanisms are plausible drivers for the beta dip observed in the MW, in the simulations, each mechanism has a unique metallicity signature associated with it, implying that future spectroscopic surveys could distinguish between them. Since an accurate knowledge of beta(r) is required for measuring the mass of the MW halo, we note significant transient dips in beta could cause an overestimate of the halo's mass when using spherical Jeans equation modeling., Comment: 14 pages, 7 figures, accepted to ApJ, companion paper to Hattori et al. (2017), appendix with Gaia specific predictions

To obtain a wide resection and safe margins in recurrent spine osteosarcoma, the surgical approach can include – posterior only, combined posterior and anterior, and combined posterior and anterior with a return to posterior in multiple stages. In our case, we used a novel approach of multiple extensile exposures circumferentially in a single stage with a single surgical prep. We present the case of a 9-year-old female with a history of metastatic osteosarcoma, who previously underwent an attempted en bloc resection with an L3 corpectomy and left below knee amputation. At 1 year follow-up, she developed a recurrent solitary spine lesion at the previous surgical resection site. An additional attempt at complete surgical resection was performed with a complex en bloc L2, L3, L4 corpectomy with removal of deep spinal implants and anterior and posterior spinal fusion with instrumentation and revision decompressive laminectomy. The patient had a good functional outcome without neurological deficits, except those resulting from resection of involved lumbar nerve roots. At last follow-up of 5 months, there was no local recurrence or distant metastasis. This approach for revision resection of recurrent spinal osteosarcoma can be performed successfully with clean margins in a safe manner.

The radial density profiles of stellar galaxy discs can be well approximated as an exponential. Compared to this canonical form, however, the profiles in the majority of disc galaxies show downward or upward breaks at large radii. Currently, there is no coherent explanation in a galaxy formation context of the radial profile per se, along with the two types of profile breaks. Using a set of controlled hydrodynamic simulations of disc galaxy formation, we find a correlation between the host halo's initial angular momentum and the resulting radial profile of the stellar disc: galaxies that live in haloes with a low spin parameter {\lambda}, Comment: 6 pages, 3 figures, adapted to the published version in MNRAS-L

Measuring quality of care delivery is essential to palliative care program growth and sustainability. We formed the Carolinas Consortium for Palliative Care and collected a quality data registry to monitor our practice and inform quality improvement efforts.We analyzed all palliative care consultations in patients with cancer in our quality registry from March 2008 through October 2011 using 18 palliative care quality measures. Descriptive metric adherence was calculated after analyzing the relevant population for measurement.We used a paper-based, prospective method to monitor adherence for quality measures in a community-based palliative care consortium.We demonstrate that measures evaluating process assessment (range 63%-100%), as opposed to interventions (range 3%-17%), are better documented.Analyzing data on quality is feasible and valuable in community-based palliative care. Overall, processes to collect data on quality using nontechnology methods may underestimate true adherence to quality measures.

We examine gas accretion and subsequent star formation in representative galaxies from the McMaster Unbiased Galaxy Simulations (Stinson et al. 2010). Accreted gas is bimodal with a natural temperature division at $10^5$ K, near the peak of the cooling curve. Cold-mode accretion dominates inflows at early times, creating a peak in total accretion at redshift z=2-4 and declining exponentially below z$\sim$2. Hot-mode accretion peaks near z=1-2 and declines gradually. Hot-mode exceeds cold-mode accretion at z$\sim$1.8 for all four galaxies rather than when the galaxy reaches a characteristic mass. Cold-mode accretion can fuel immediate star formation, while hot-mode accretion preferentially builds a large, hot gas reservoir in the halo. Late-time star formation relies on reservoir gas accreted 2-8 Gyr prior. Thus, the reservoir allows the star formation rate to surpass the current overall gas accretion rate. Stellar feedback cycles gas from the interstellar medium back into the hot reservoir. Stronger feedback results in more gas cycling, gas removal in a galactic outflow and less star formation overall, enabling simulations to match the observed star formation history. For lower mass galaxies in particular, strong feedback can delay the star formation peak to z=1-2 from the accretion peak at z=2-4., Comment: 10 pages, 7 figures. Accepted for publication in MNRAS

We analyse the structure and chemical enrichment of a Milky Way-like galaxy with a stellar mass of 2 10^{10} M_sun, formed in a cosmological hydrodynamical simulation. It is disk-dominated with a flat rotation curve, and has a disk scale length similar to the Milky Way's, but a velocity dispersion that is ~50% higher. Examining stars in narrow [Fe/H] and [\alpha/Fe] abundance ranges, we find remarkable qualitative agreement between this simulation and observations: a) The old stars lie in a thickened distribution with a short scale length, while the young stars form a thinner disk, with scale lengths decreasing, as [Fe/H] increases. b) Consequently, there is a distinct outward metallicity gradient. c) Mono-abundance populations exist with a continuous distribution of scale heights (from thin to thick). However, the simulated galaxy has a distinct and substantive very thick disk (h_z~1.5 kpc), not seen in the Milky Way. The broad agreement between simulations and observations allows us to test the validity of observational proxies used in the literature: we find in the simulation that mono-abundance populations are good proxies for single age populations (, Comment: 11 page, 10 figures, submitted. Comments welcome

We use the NIHAO (Numerical Investigation of Hundred Astrophysical Objects) cosmological simulations to study the effects of galaxy formation on key properties of dark matter (DM) haloes. NIHAO consists of $\simeq 90$ high-resolution SPH simulations that include (metal-line) cooling, star formation, and feedback from massive stars and SuperNovae, and cover a wide stellar and halo mass range: $10^6 < M_* / M_{\odot} < 10^{11}$ ( $10^{9.5} < M_{\rm halo} / M_{\odot} < 10^{12.5}$). When compared to DM-only simulations, the NIHAO haloes have similar shapes at the virial radius, R_{\rm vir}, but are substantially rounder inside $\simeq 0.1R_{\rm vir}$. In NIHAO simulations $c/a$ increases with halo mass and integrated star formation efficiency, reaching $\sim 0.8$ at the Milky Way mass (compared to 0.5 in DM-only), providing a plausible solution to the long-standing conflict between observations and DM-only simulations. The radial profile of the phase-space $Q$ parameter ($��/��^3$) is best fit with a single power law in DM-only simulations, but shows a flattening within $\simeq 0.1R_{\rm vir}$ for NIHAO for total masses $M>10^{11} M_{\odot}$. Finally, the global velocity distribution of DM is similar in both DM-only and NIHAO simulations, but in the solar neighborhood, NIHAO galaxies deviate substantially from Maxwellian. The distribution is more symmetric, roughly Gaussian, with a peak that shifts to higher velocities for Milky Way mass haloes. We provide the distribution parameters which can be used for predictions for direct DM detection experiments. Our results underline the ability of the galaxy formation processes to modify the properties of dark matter haloes., 19 pages, 17 figures, analysis strongly improved, main conclusions unchanged, accepted for publication in MNRAS

We use ~100 cosmological galaxy formation zoom-in simulations using the smoothed particle hydrodynamics code {\sc gasoline} to study the effect of baryonic processes on the mass profiles of cold dark matter haloes. The haloes in our study range from dwarf (M_{200}~10^{10}Msun) to Milky Way (M_{200}~10^{12}Msun) masses. Our simulations exhibit a wide range of halo responses, primarily varying with mass, from expansion to contraction, with up to factor ~10 changes in the enclosed dark matter mass at one per cent of the virial radius. Confirming previous studies, the halo response is correlated with the integrated efficiency of star formation: e_SF=(M_{star}/M_{200})/(\Omega_b/\Omega_m). In addition we report a new correlation with the compactness of the stellar system: e_R=r_{1/2}/R_{200}. We provide an analytic formula depending on e_SF and e_R for the response of cold dark matter haloes to baryonic processes. An observationally testable prediction is that, at fixed mass, larger galaxies experience more halo expansion, while the smaller galaxies more halo contraction. This diversity of dark halo response is captured by a toy model consisting of cycles of adiabatic inflow (causing contraction) and impulsive gas outflow (causing expansion). For net outflow, or equal inflow and outflow fractions, f, the overall effect is expansion, with more expansion with larger f. For net inflow, contraction occurs for small f (large radii), while expansion occurs for large f (small radii), recovering the phenomenology seen in our simulations. These regularities in the galaxy formation process provide a step towards a fully predictive model for the structure of cold dark matter haloes., Comment: 20 pages, 15 figures, accepted to MNRAS

Within a cosmological hydrodynamical simulation, we form a disc galaxy with sub- components which can be assigned to a thin stellar disc, thick disk, and a low mass stellar halo via a chemical decomposition. The thin and thick disc populations so selected are distinct in their ages, kinematics, and metallicities. Thin disc stars are young (

We examine the chemical properties of 5 cosmological hydrodynamical simulations of an M33-like disc galaxy which have been shown to be consistent with the morphological characteristics and bulk scaling relations expected of late-type spirals. These simulations are part of the Making Galaxies In a Cosmological Context (MaGICC) Project, in which stellar feedback is tuned to match the stellar mass -- halo mass relationship. Each realisation employed identical initial conditions and assembly histories, but differed from one another in their underlying baryonic physics prescriptions, including (a) the efficiency with which each supernova energy couples to the ISM, (b) the impact of feedback associated with massive star radiation pressure, (c) the role of the minimum shut-off time for radiative cooling of Type II SNe remnants, (d) the treatment of metal diffusion, and (e) varying the IMF. Our analysis focusses on the resulting stellar metallicity distribution functions (MDFs) in each simulated (analogous) `solar neighbourhood' and central `bulge' region. We compare the simulated MDFs' skewness, kurtosis, and dispersion (inter-quartile, inter-decile, inter-centile, and inter-tenth-percentile regions) with that of the empirical solar neighbourhood MDF and Local Group dwarfs. We find that the MDFs of the simulated discs are more negatively skewed, with higher kurtosis, than those observed locally. We can trace this difference to the simulations' tight and correlated age-metallicity relations (compared with that of the Milky Way), suggesting that these relations within `dwarf' discs might be steeper than in L* discs and/or the degree of stellar orbital re-distribution and migration inferred locally has not been captured in their entirety, at the resolution of our simulations. The important role of metal diffusion in ameliorating the over-production of extremely metal-poor stars is highlighted.

We use the same physical model to simulate four galaxies that match the relation between stellar and total mass, over a mass range that includes the vast majority of disc galaxies. The resultant galaxies, part of the Making Galaxies in a Cosmological Context (MaGICC) programme, also match observed relations between luminosity, rotation velocity, size, colour, star formation rate, H I mass, baryonic mass and metallicity. Radiation energy feedback from massive stars and supernova energy balance the complex interplay between cooling gas, regulated star formation, large-scale outflows and recycling of gas in a manner which correctly scales with the mass of the galaxy. Outflows, driven by the expansion of shells and superbubbles of overlapping supernova explosions, also play a key role in simulating galaxies with exponential surface brightness profiles, flat rotation curves and dark matter cores. Our study implies that large-scale outflows are the primary driver of the dependence of disc galaxy properties on mass. We show that the degree of outflows invoked in our model is required to meet the constraints provided by observations of O VI absorption lines in the circumgalactic media of nearby galaxies.

We compare the results of thirteen cosmological gasdynamical codes used to simulate the formation of a galaxy in the LCDM structure formation paradigm. The various runs differ in their hydrodynamical treatment (SPH, moving-mesh and AMR) but share the same initial conditions and adopt their latest published model of cooling, star formation and feedback. Despite the common halo assembly history, we find large code-to-code variations in the stellar mass, size, morphology and gas content of the galaxy at z=0, due mainly to the different implementations of feedback. Compared with observation, most codes tend to produce an overly massive galaxy, smaller and less gas-rich than typical spirals, with a massive bulge and a declining rotation curve. A stellar disk is discernible in most simulations, though its prominence varies widely from code to code. There is a well-defined trend between the effects of feedback and the severity of the disagreement with observation. Models that are more effective at limiting the baryonic mass of the galaxy come closer to matching observed galaxy scaling laws, but often to the detriment of the disk component. Our conclusions hold at two different numerical resolutions. Some differences can also be traced to the numerical techniques: more gas seems able to cool and become available for star formation in grid-based codes than in SPH. However, this effect is small compared to the variations induced by different feedback prescriptions. We conclude that state-of-the-art simulations cannot yet uniquely predict the properties of the baryonic component of a galaxy, even when the assembly history of its host halo is fully specified. Developing feedback algorithms that can effectively regulate the mass of a galaxy without hindering the formation of high-angular momentum stellar disks remains a challenge.

Encoded within the morphological structure of galaxies are clues related to their formation and evolutionary history. Recent advances pertaining to the statistics of galaxy morphology include sophisticated measures of concentration (C), asymmetry (A), and clumpiness (S). In this study, these three parameters (CAS) have been applied to a suite of simulated galaxies and compared with observational results inferred from a sample of nearby galaxies. The simulations span a range of late-type systems, with masses between ~1e10 Msun and ~1e12 Msun, and employ star formation density thresholds between 0.1 cm^-3 and 100 cm^-3. We have found that the simulated galaxies possess comparable concentrations to their real counterparts. However, the results of the CAS analysis revealed that the simulated galaxies are generally more asymmetric, and that the range of clumpiness values extends beyond the range of those observed. Strong correlations were obtained between the three CAS parameters and colour (B-V), consistent with observed galaxies. Furthermore, the simulated galaxies possess strong links between their CAS parameters and Hubble type, mostly in-line with their real counterparts.

Within a fully cosmological hydrodynamical simulation, we form a galaxy which rotates at 140 km/s, and is characterised by two loose spiral arms and a bar, indicative of a Hubble Type SBc/d galaxy. We show that our simulated galaxy has no classical bulge, with a pure disc profile at z=1, well after the major merging activity has ended. A long-lived bar subsequently forms, resulting in the formation of a secularly-formed "pseudo" bulge, with the final bulge-to-total light ratio B/T=0.21. We show that the majority of gas which loses angular momentum and falls to the central region of the galaxy during the merging epoch is blown back into the hot halo, with much of it returning later to form stars in the disc. We propose that this mechanism of redistribution of angular momentum via a galactic fountain, when coupled with the results from our previous study which showed why gas outflows are biased to have low angular momentum, can solve the angular momentum/bulgeless disc problem of the cold dark matter paradigm.

We present an analysis of the neutral hydrogen (HI) properties of a fully cosmological hydrodynamical dwarf galaxy, run with varying simulation parameters. As reported by Governato et al. (2010), the high resolution, high star formation density threshold version of this galaxy is the first simulation to result in the successful reproduction of a (dwarf) spiral galaxy without any associated stellar bulge. We have set out to compare in detail the HI distribution and kinematics of this simulated bulgeless disk with what is observed in a sample of nearby dwarfs. To do so, we extracted the radial gas density profiles, velocity dispersion (e.g., velocity ellipsoid, turbulence), and the power spectrum of structure within the cold interstellar medium from the simulations. The highest resolution dwarf, when using a high density star formation threshold comparable to densities of giant molecular clouds, possesses bulk characteristics consistent with those observed in nature, though the cold gas is not as radially extended as that observed in nearby dwarfs, resulting in somewhat excessive surface densities. The lines-of-sight velocity dispersion radial profiles have values that are in good agreement with observed dwarf galaxies, but due to the fact that only the streaming velocities of particles are tracked, a correction to include the thermal velocities can lead to profiles that are quite flat. The ISM power spectra of the simulations appear to possess more power on smaller spatial scales than that of the SMC. We conclude that unavoidable limitations remain due to the unresolved physics of star formation and feedback within pc-scale molecular clouds.

We present the analysis of a suite of simulations run with different particle-and grid-based cosmological hydrodynamical codes and compare them with observational data of the Milky Way. This is the first study to make comparisons of properties of galaxies simulated with particle and grid-based codes. Our analysis indicates that there is broad agreement between these different modelling techniques. We study the velocity dispersion - age relation for disc stars at z=0 and find that four of the simulations are more consistent with observations by Holmberg et al. (2008) in which the stellar disc appears to undergo continual/secular heating. Two other simulations are in better agreement with the Quillen & Garnett (2001) observations that suggest a "saturation" in the heating profile for young stars in the disc. None of the simulations have thin discs as old as that of the Milky Way. We also analyse the kinematics of disc stars at the time of their birth for different epochs in the galaxies' evolution and find that in some simulations old stars are born cold within the disc and are subsequently heated, while other simulations possess old stellar populations which are born relatively hot. The models which are in better agreement with observations of the Milky Way's stellar disc undergo significantly lower minor-merger/assembly activity after the last major merger - i.e. once the disc has formed. All of the simulations are significantly "hotter" than the Milky Way disc; on top of the effects of mergers, we find a "floor" in the dispersion that is related to the underlying treatment of the heating and cooling of the interstellar medium, and the low density threshold which such codes use for star formation. This finding has important implications for all studies of disc heating that use hydrodynamical codes.

We present a study of satellites in orbit around a high-resolution, smoothed particle hydrodynamics (SPH) galaxy simulated in a cosmological context. The simulated galaxy is approximately the same mass as the Milky Way. The cumulative number of luminous satellites at z = 0 is similar to the observed system of satellites orbiting the Milky Way although an analysis of the satellite mass function reveals an order of magnitude more dark satellites than luminous. Some of the dark subhalos are more massive than some of the luminous subhalos at z = 0. What separates luminous and dark subhalos is not their mass at z = 0, but the maximum mass the subhalos ever achieve. We study the effect of four mass loss mechanisms on the subhalos: ultraviolet (UV) ionising radiation, ram pressure stripping, tidal stripping, and stellar feedback, and compare the impact of each of these four mechanisms on the satellites. In the lowest mass subhalos, UV is responsible for the majority of the baryonic mass loss. Ram pressure stripping removes whatever mass remains from the low mass satellites. More massive subhalos have deeper potential wells and retain more mass during reionisation. However, as satellites pass near the centre of the main halo, tidal forces cause significant mass loss from satellites of all masses. Satellites that are tidally stripped from the outside can account for the luminous satellites that are lower mass than some of the dark satellites. Stellar feedback has the greatest impact on medium mass satellites that had formed stars, but lost all their gas by z = 0. Our results demonstrate that the missing satellite problem is not an intractable issue with the cold dark matter cosmology, but is rather a manifestation of baryonic processes.