Two-component galaxies with flat rotation curve

Dynamical properties of two-component galaxy models whose stellar density distribution is described by a gamma-model while the total density distribution has a pure r^(-2) profile, are presented. The orbital structure of the stellar component is described by Osipkov-Merritt anisotropy, while the dark matter halo is isotropic. After a description of minimum halo models, the positivity of the phase-space density (the model consistency) is investigated, and necessary and sufficient conditions for consistency are obtained analytically as a function of the stellar inner density slope gamma and anisotropy radius. The explicit phase-space distribution function is recovered for integer values of gamma, and it is shown that while models with gamma>4/17 are consistent when the anisotropy radius is larger than a critical value (dependent on gamma), the gamma=0 models are unphysical even in the fully isotropic case. The Jeans equations for the stellar component are then solved analytically; in addition, the projected velocity dispersion at the center and at large radii are also obtained analytically for generic values of the anisotropy radius, and it is found that they are given by remarkably simple expressions. The presented models, even though highly idealized, can be useful as starting point for more advanced modeling of the mass distribution of elliptical galaxies in studies combining stellar dynamics and gravitational lensing.Comment: 11 pages, 5 figures, accepted by MNRA

Elliptical galaxies with rapidly decreasing velocity dispersion profiles: NMAGIC models and dark halo parameter estimates for NGC 4494

NGC 4494 is one of several intermediate-luminosity elliptical galaxies inferred to have an unusually diffuse dark matter halo. We use the chi^2-made-to-measure particle code NMAGIC to construct axisymmetric models of NGC 4494 from photometric and various kinematic data. The extended kinematics include light spectra in multiple slitlets out to 3.5 R_e, and hundreds of planetary nebulae velocities out to ~7 R_e, thus allowing us to probe the dark matter content and orbital structure in the halo. We use Monte Carlo simulations to estimate confidence boundaries for the halo parameters, given our data and modelling set-up. We find that the true potential of the dark matter halo is recovered within Delta G (merit function)<26 (Delta chi^2<59) at 70% confidence level (C.L.), and within Delta G<32 (Delta chi^2<70) at 90% C.L.. These numbers are much larger than the usually assumed Delta chi^2=2.3 (4.6) for 70% (90%) C.L. for two free parameters, perhaps case-dependent, but calling into question the general validity of the standard assumptions used for halo and black hole mass determinations. The best-fitting models for NGC 4494 have a dark matter fraction of about 0.6\pm0.1 at 5R_e (70% C.L.), and are embedded in a dark matter halo with circular velocity ~200 km/s. The total circular velocity curve (CVC) is approximately flat at v_c=220 km/s outside ~0.5R_e. The orbital anisotropy of the stars is moderately radial. These results are independent of the assumed inclination of the galaxy, and edge-on models are preferred. Comparing with the halos of NGC 3379 and NGC 4697, whose velocity dispersion profiles also decrease rapidly from the center outwards, the outer CVCs and dark matter halos are quite similar. NGC 4494 shows a particularly high dark matter fraction inside ~3R_e, and a strong concentration of baryons in the center.Comment: 21 pages, 23 figures, 1 table. Accepted for publication in MNRA

Made-to-measure particle models of intermediate-luminosity elliptical galaxies

Dynamische Modelle sind wichtige Hilfsmittel, um aus projizierten Beobachtungsdaten auf die Massenverteilung und die Phasenraumstruktur von Galaxien zu schließen, und dabei ihre Entstehungs- und Entwicklungsprozesse zu verstehen. Eine relativ neue und vielversprechende Technik, dynamische Modelle zu konstruieren, ist die “made-to-measure” Methode, bei der ein System von Teilchen sukzessive einer beobachteten Lichtverteilung und gemessenen projizierten stellaren Kinematik angeglichen wird. Da die intrinsische, dreidimensionale Struktur der Modelle dann bekannt ist, können sie verwendet werden, um die Massenverteilung und Bahnstruktur der Galaxie zu verstehen. In dieser Arbeit verwenden wir den “made-to-measure particle” Code NMAGIC, um die spezielle Klasse der schwach im Röntgenbereich strahlenden elliptischen Galaxien von mittlerer Leuchtkraft zu erforschen, deren Geschwindigkeitsdispersionsprofile stark mit dem Radius abfallen, was auf sehr diffuse dunkle Materie Halos hindeutet, die möglicherweise in Konflikt zu Vorhersagen von Galaxienentstehungsmodellen stehen. Im ersten Teil der Arbeit führen wir eine “moving prior” Regularisierungsmethode in NMAGIC ein, welche eine korrekte und von systematischen Fehlern freie Rekonstruktion der dynamischen Struktur der beobachteten Galaxie ermöglicht. Im sphärischen Fall, in welchem theoretisch eine eindeutige Invertierung der Daten möglich ist, zeigen wir, dass NMAGIC mit der neuen Regularisierungsmethode die Verteilungsfunktion und intrinsische Kinematik einer Zielgalaxie (mit idealen Daten) mit hoher Genauigkeit reproduziert, unabhängig von der ursprünglich als Startmodell gewählten Teilchenverteilung. Weiterhin untersuchen wir, wie sich unvollständige und verrauschte kinematische Daten auswirken, und kommen zu dem Schluss, dass die Zuverläßigkeit der Modelle auf Gebiete mit guten Beobachtungsdaten beschränkt ist. Schließlich werden mit einer Version der moving-prior Regularisierung für axialsymmetrische Systeme die am besten passenden NMAGIC Modelle der zwei elliptischen, mittelstark leuchtenden Galaxien NGC 4697 und NGC 3379 aus früheren Arbeiten rekonstruiert, um einen glatteren Fit an die Beobachtungsdaten zu erhalten. Im zweiten Teil der Arbeit untersuchen wir die rätselhafte elliptische Galaxie NGC 4494 mittlerer Leuchtkraft. Wir konstruieren axialsymmetrische NMAGIC Modelle mit unterschiedlichen dunkle Materie Halos und Inklinationen, um etwas über ihre Massenverteilung und Bahnstruktur zu erfahren. Die Modelle werden eingegrenzt durch Radialgeschwindigkeiten von planetarischen Nebeln und kinematischen Absorptionsliniendaten in “slitlets”, was uns ermöglicht, zu erforschen, bei welchen Radien die dunkle Materie anfängt zu dominieren bzw. Spuren des Entstehungsmechanismus sichtbar werden. Mit geeigneten Monte-Carlo-Simulationen bestimmen wir mit NMAGIC die ��Werte verschiedener Konfidenzniveaus für die Schätzung der Parameter der dunklen Halos und finden andere Werte, als in der Literatur über dynamische Modellierung normalerweise verwendet. Unsere best-fit NMAGIC Modelle für NGC 4494 innerhalb dieser Konfidenzniveaus schließen einen diffusen dunklen Halo aus; sie haben einen Anteil dunkler Materie von ungefähr 0, 6±0, 1 bei 5 Effektivradien und eine näherungsweise flache (konstante) totale Kreisgeschwindigkeit von � 220 km/s außerhalb des Effektivradius. Die Anisotropie der Sternbahnen ist mässig radial. Diese Ergebnisse sind unabhängig von der angenommenen Inklination der Galaxie, aber edge-on Modelle werden bevorzugt. Schließlich vergleichen wir die dunklen und stellaren Halos von den bisher modellierten elliptischen Galaxien mittlerer Leuchtkraft und folgern, dass ihre Kreisgeschwindigkeiten ähnlich sind. Die genaue Wechselwirkung zwischen dunkler und leuchtender Materie war während der Entstehung jeder Galaxie wahrscheinlich unterschiedlich – und NGC 4494 zeigt einen besonders hohen Anteil an dunkler Materie, speziell im Zentrum, was vielleicht das Ergebniss vergangener Verschmelzungsereignisse sein könnte.Dynamical models are an important tool to infer the mass distribution and phase-space structure of galaxies from projected observational data, and thereby learn about the processes driving their formation and evolution. A recent and promising technique to build dynamical models is through made-to-measure particle methods, in which a system of particles is trained to match the observed light distribution and projected stellar kinematics of a galaxy. Because the intrinsic, three-dimensional structure of such models is then known, they can be used to understand the mass distribution and orbital structure of the galaxy. In this thesis we use the made-to-measure particle code NMAGIC to investigate the particular class of X-ray-faint, intermediate-luminosity elliptical galaxies, whose velocity dispersion profiles decline strongly with radius, suggesting very diffuse dark matter halos in possible tension with the predictions of galaxy formation models. In the first part of the work, we introduce a moving prior regularization method in NMAGIC which facilitates a correct and unbiased recovery of the dynamical structure of the observed galaxy. In the spherical case in which theoretically a unique inversion of (idealized) data exists, we show that NMAGIC with the new regularization method recovers the distribution function and intrinsic kinematics of the target galaxy with high accuracy, independent of the initial particle model. We then investigate the effects of less complete and noisier kinematic data, and conclude that the reliability of the models is limited to those regions in which good observational constraints exist. A version of the moving prior regularization suited for axisymmetric systems is then used to reconstruct the best-fitting NMAGIC models determined in previous works for the two intermediate-luminosity elliptical galaxies NGC 4697 and NGC 3379, obtaining smoother fits to the observational data. In the second part of the work, we explore the enigmatic intermediate-luminosity elliptical galaxy NGC 4494. We construct axisymmetric NMAGIC models with different dark matter halos and inclinations, in order to learn about its mass distribution and orbital structure. The kinematic constraints include radial velocities of Planetary Nebulae and absorption line kinematics data in slitlets, and allow us to probe those radii where dark matter starts to dominate and the imprint of formation mechanisms becomes apparent. Using suitable Monte Carlo simulations, we determine the �various confidence levels for the estimation of the dark halo parameters with NMAGIC, and find that these are different from the values usually employed in the dynamical modeling literature. Our best-fitting NMAGIC models for NGC 4494 within these confidence levels rule out a diffuse dark halo; they have a dark matter fraction of about 0.6 ± 0.1 at 5 effective radii, and an approximately flat total circular velocity � 220 km/s outside 1 effective radius. The orbital anisotropy of the stars is moderately radial. These results are independent on the assumed inclination of the galaxy, but edge-on models are preferred. Finally, we compare the dark and stellar halos of the intermediate-luminosity ellipticals modeled so far, and conclude that their circular velocity curves are similar. The detailed interaction between dark and luminous matter during galaxy formation was probably different for each galaxy, and NGC 4494 shows a particularly high dark matter fraction, especially in the center, which might be a reminiscence of merger events

Evaluation on prognostic efficacy of lymph nodes ratio (LNR) and log odds of positive lymph nodes (LODDS) in complicated colon cancer: The first study in emergency surgery

Background: Lymph node involvement is one of the most important prognostic factors in colon cancer. Twelve is considered the minimum number of lymph nodes necessary to retain reliable tumour staging, but several factors can potentially influence the lymph node harvesting. Emergent surgery for complicated colon cancer (perforation, occlusion, bleeding) could represent an obstacle to reach the benchmark of 12 nodes with an accurate lymphadenectomy. So, an efficient classification system of lymphatic involvement is crucial to define the prognosis, the indication to adjuvant therapy and the follow-up. This is the first study with the aim to evaluate the efficacy of lymph nodes ratio (LNR) and log odds of positive lymph nodes (LODDS) in the prognostic assessment of patients who undergo to urgent surgery for complicated colonic cancer. Methods: This is a retrospective study carried out on patients who underwent urgent colonic resection for complicated cancer (occlusion, perforation, bleeding, sepsis). We collected clinical, pathological and follow-up data of 320 patients. Two hundred two patients met the inclusion criteria and were distributed into three groups according to parameter N of TNM, LNR and LODDS. Survival analysis was performed by Kaplan-Meier curves, investigating both overall survival (OS) and disease-free survival (DFS). Results: The median number of harvested lymph nodes was 17. In 78.71% (n = 159) of cases, at least 12 lymph nodes were examined. Regarding OS, significant differences from survival curves emerged for ASA score, surgical indication, tumour grading, T parameter, tumour stage, N parameter, LNR and LODDS. In multivariate analysis, only LODDS was found to be an independent prognostic factor. Concerning DFS, we found significant differences between survival curves of sex, surgical indication, T parameter, tumour stage, N parameter, LNR and LODDS, but none of these confirmed its prognostic power in multivariate analysis. Conclusions: We found that N, LNR and LODDS are all related to 5-year OS and DFS with statistical significance, but only LODDS was found to be an independent prognostic factor for OS in multivariate analysis

Intraoperative β-Detecting probe for radio-guided surgery in tumour resection

The development of the β− based radio-guided surgery aims to extend the technique to those tumours where surgery is the only possible treatment and the assessment of the resection would most profit from the low background around the lesion, as for brain tumours. Feasibility studies on meningioma and gliomas already estimated the potentiality of this new treatment. To validate the technique, a prototype of the intraoperative probe detecting β− decays and specific phantoms simulating tumour remnant patterns embedded in healthy tissue have been realized. The response of the probe in this simulated environment is tested with dedicated procedures. This document discusses the innovative aspects of the method, the status of the developed intraoperative β− detecting probe and the results of the preclinical tests

An Intraoperative β−\beta^- Detecting Probe For Radio-Guided Surgery in Tumour Resection

The development of the $\beta^-$ based radio-guided surgery aims to extend the technique to those tumours where surgery is the only possible treatment and the assessment of the resection would most profit from the low background around the lesion, as for brain tumours. Feasibility studies on meningioma, glioma, and neuroendocrine tumors already estimated the potentiality of this new treatment. To validate the technique, prototypes of the intraoperative probe required by the technique to detect $\beta^-$ radiation have been developed. This paper discusses the design details of the device and the tests performed in laboratory. In such tests particular care has to be taken to reproduce the surgical field conditions. The innovative technique to produce specific phantoms and the dedicated testing protocols is described in detail.Comment: 7 pages, 15 figure

Effects of balloon angioplasty and stent implantation on intrarenal echo-Doppler velocimetric indices

Effects of balloon angioplasty and stent implantation on intrarenal echo-Doppler velocimetric indices. This study was aimed at examining whether four intrarenal echo-Doppler velocimetric indices (pulsatility and resistive indices, acceleration and acceleration time) can be useful for assessing the effects of renal artery dilation obtained with either angioplasty or stent implantation. Echo-Doppler studies were performed in 63 hypertensive patients with 68 renal artery stenoses (39 atherosclerotic and 29 fibromuscular) prior to and within five days after the dilation procedures (55 angioplasties, 13 stent implantations), which resulted in an average reduction of arterial narrowing from 79% to 20%. In 24 patients, the velocimetric indices were also examined in relationship to the venoarterial differences of plasma renin activity and of angiotensin II across the stenotic kidneys. We found that after dilation the values of the four indices had returned within the normal range in all but three arteries (one false negative for resistive index and two for acceleration time). However, decrements in acceleration time was the only factor to be significantly correlated with the reduction of arterial narrowing. Moreover, post-dilation values of this index were, on average, slightly but significantly higher in arteries that at follow-up developed restenosis rather than in those that remained patent. For similar reductions in arterial narrowing the absolute changes of all indices were similar in atherosclerotic and fibromuscular stenotic arteries and, in a subset of the atheromatous arteries, were also similar after angioplasty and stent implantation. No relationship was found with the changes in the venoarterial differences of plasma renin activity and angiotensin II. It appears that these intrarenal velocimetric indices and, in particular, acceleration time reliably reflect the technical success of renal artery dilation. The acceleration time index may also be valuable for predicting the restenosis of the dilated vessel. None of the indices, however, mirrors the functional consequences of removal of renal artery stenosis as expressed through the changes in transrenal gradients of the components of the renin-angiotensin system

Monitoring of hadrontherapy treatments by means of charged particle detection

The interaction of the incoming beam radiation with the patient body in hadrontherapy treatments produces secondary charged and neutral particles, whose detection can be used for monitoring purposes and to perform an on-line check of beam particle range. In the context of ion-therapy with active scanning, charged particles are potentially attractive since they can be easily tracked with a high efficiency, in presence of a relatively low background contamination. In order to verify the possibility of exploiting this approach for in-beam monitoring in ion-therapy, and to guide the design of specific detectors, both simulations and experimental tests are being performed with ion beams impinging on simple homogeneous tissue-like targets (PMMA). From these studies, a resolution of the order of few millimeters on the single track has been proven to be sufficient to exploit charged particle tracking for monitoring purposes, preserving the precision achievable on longitudinal shape. The results obtained so far show that the measurement of charged particles can be successfully implemented in a technology capable of monitoring both the dose profile and the position of the Bragg peak inside the target and finally lead to the design of a novel profile detector. Crucial aspects to be considered are the detector positioning, to be optimized in order to maximize the available statistics, and the capability of accounting for the multiple scattering interactions undergone by the charged fragments along their exit path from the patient body. The experimental results collected up to now are also valuable for the validation of Monte Carlo simulation software tools and their implementation in Treatment Planning Software packages

Extended calibration range for prompt photon emission in ion beam irradiation

Monitoring the dose delivered during proton and carbon ion therapy is still a matter of research. Among the possible solutions, several exploit the measurement of the single photon emission from nuclear decays induced by the irradiation. To fully characterize such emission the detectors need development, since the energy spectrum spans the range above the MeV that is not traditionally used in medical applications. On the other hand, a deeper understanding of the reactions involving gamma production is needed in order to improve the physic models of Monte Carlo codes, relevant for an accurate prediction of the prompt-gamma energy spectrum.This paper describes a calibration technique tailored for the range of energy of interest and reanalyzes the data of the interaction of a 80MeV/u fully stripped carbon ion beam with a Poly-methyl methacrylate target. By adopting the FLUKA simulation with the appropriate calibration and resolution a significant improvement in the agreement between data and simulation is reported.Comment: 4 pages, 7 figures, Submitted to JINS