Asymptotic behavior of unstable INAR(p) processes

In this paper the asymptotic behavior of an unstable integer-valued autoregressive model of order p (INAR(p)) is described. Under a natural assumption it is proved that the sequence of appropriately scaled random step functions formed from an unstable INAR(p) process converges weakly towards a squared Bessel process. We note that this limit behavior is quite different from that of familiar unstable autoregressive processes of order p. An application for Boston armed robberies data set is presented.Comment: 35 pages; corrected and extended version: a new section on an application for Boston armed robberies data set is adde

Elastic Modulus Profiles in the Cross Sections of Drying Alkyd Coating Films: Modelling and Experiments

The temporal development of the modulus of elasticity and its profile were studied in water-borne alkyd coatings during the drying process of the coating films. Values of the Young’s moduli of elasticity of free coating films were measured using tensile tests. Since the elastic modulus is related to cross-link density, the values of the moduli give information on the advancement of the drying process. A mathematical model was developed to predict the degree of effective cross-linking and the mechanical behaviour of the drying coating films with different thicknesses. This model is based on trends observed by confocal Raman microspectroscopy, which exhibit the profile of the consumption of double bonds and thus can be used to monitor the development of cross-link density as a function of depth from the film surface. The average values of the Young’s measured moduli were successfully described by the numerical model as a function of drying time

Contribution of cardiovascular risk factors in the thrombotic complications of essential thrombocythaemia: a Hungarian single-institute retrospective analysis.

OBJECTIVE: Essential thrombocythaemia (ET) is a myeloproliferative neoplasm in which there is an increased risk of thrombotic complications. The conventional thrombosis risk assessment of these patients is based on an age over 60 and a history of thrombosis. The aim of this report is to analyse the contribution of cardiovascular risk (CV) factors as possible additional thrombotic risk factors in the thrombotic complications seen in ET. PATIENTS AND METHODS: One hundred and one ET patients (72 females and 29 males with a median age of 61 years) were enrolled between 1999 and 2011. Mann-Whitney and multivariate binary logistic regression tests were performed. The Kaplan-Meier method followed by the log-rank test was used to evaluate the probability of thrombosis-free survival. RESULTS: The presence of one or two or more CV risk factors significantly increased the risk of thrombosis. Separately, the contribution of high blood pressure and hyperlipidaemia proved to be influential, whereas tobacco use, diabetes mellitus and obesity were not significant. Significant differences were revealed in the probability of thrombosis-free survival between patients without CV risk factors and those with at least one CV risk factor, and between those with at most one CV risk factor and those with two or more CV risk factors. CONCLUSIONS: On the basis of the results on the current cohort, it is suggested that CV risk factors may influence the thrombotic complications in ET

Rotational Properties of Hilda Asteroids Observed by the K2 Mission

Hilda asteroids orbit at the outer edge, or just outside of the Main Belt, occupying the 2:3 mean motion resonance with Jupiter. It is known that the group shows a mixed taxonomy that suggests the mixed origin of Hilda members, having migrated to the current orbit both from the outer Main Belt and from the Trojans swarms. But there are still few observations for comparative studies that help in understanding the Hilda group in deeper details. We identified 125 individual light curves of Hilda asteroids observed by the K2 mission. We found that despite of the mixed taxonomies, the Hilda group highly resembles to the Trojans in the distribution of rotation periods and amplitudes, and even the LR group (mostly C and X-type) Hildas follow this rule. Contrary to the Main Belt, Hilda group lacks the very fast rotators. The ratio of extremely slow rotators (P>100 h) is a surprising 18%, which is unique in the Solar System. The occurrence rate of asteroids with multiple periods (4%) and asteroids with three maxima in the light curves (5%) can be signs of high rate of binarity, which we can estimate as 25% within the Hilda group

Ancillary science with Ariel: Feasibility and scientific potential of young stellar object observations

To investigate the feasibility of ancillary target observations with ESA's Ariel mission, we compiled a list of potentially interesting young stars: FUors, systems harbouring extreme debris discs and a larger sample of young stellar objects showing strong near/mid-infrared excess. These objects can be observed as additional targets in the waiting times between the scheduled exoplanet transit and occultation observations. After analyzing the schedule for Ariel an algorithm was constructed to find the optimal target to be observed in each gap. The selection was mainly based on the slew and stabilization time needed to observe the selected YSO, but it also incorporated the scientific importance of the targets and whether they have already been sufficiently measured. After acquiring an adequately large sample of simulation data, it was concluded that approximately 99.2% of the available -- at least one hour long -- gaps could be used effectively. With an average slewing and stabilization time of about 16.7 minutes between scheduled exoplanet transits and ancillary targets, this corresponds to an additional $2881 \pm 56$ hours of active data gathering. When this additional time is used to observe our selected 200 ancillary targets, a typical signal-to-noise ratio of $\sim$10$^4$ can be achieved along the whole spectral window covered by Ariel.Comment: Accepted for publication in Experimental Astronom

Solar System Objects Observed with TESS—First Data Release: Bright Main-belt and Trojan Asteroids from the Southern Survey

Compared with previous space-borne surveys, the Transiting Exoplanet Survey Satellite (TESS) provides a unique and new approach to observe Solar System objects. While its primary mission avoids the vicinity of the ecliptic plane by approximately six degrees, the scale height of the Solar System debris disk is large enough to place various small body populations in the field-of-view. In this paper we present the first data release of photometric analysis of TESS observations of small Solar System Bodies, focusing on the bright end of the observed main-belt asteroid and Jovian Trojan populations. This data release, named TSSYS-DR1, contains 9912 light curves obtained and extracted in a homogeneous manner, and triples the number of bodies with unambiguous fundamental rotation characteristics, namely where accurate periods and amplitudes are both reported. Our catalogue clearly shows that the number of bodies with long rotation periods are definitely underestimated by all previous ground-based surveys, by at least an order of magnitude.Comment: ApJS, in press. Data are available from https://archive.konkoly.hu/pub/tssys/dr1/ (6.36G, in total

Biomassza hasznosítás kémiai alapfolyamatainak tanulmányozása = Study of fundamental chemical processes of biomass utilization

(1) Biomassza anyagok széles skáláját vizsgáltuk termikus módszerekkel. A hőbomlásról, az égési folyamatokról, és az elgázosításról nyertünk ismereteket, valamint hozzájárultunk egyes biomassza-hasznosítási eljárások során lejátszódó folyamatok mélyebb megértéséhez. Olyan reakciókinetikai modelleket alkalmaztunk, ill. dolgoztunk ki, melyek nagyobb mérési sorozatokon, a kísérleti körülmények széles tartományában írják le a vizsgált termikus reakciókat, és tükrözték a vizsgált minták szerkezetének és felépítésének komplikált voltát. (2) Bioetanol gyártás tématerületen öt szubsztráton (gőzrobbantással előkezelt cukorcirok bagasz, kender, kender pozdorja és kontrollként két modell szubsztrát) vizsgáltuk a Tween 80 és a PEG 4000 adalékanyagok hatását különböző hőmérsékleteken. Kísérleteinkben kimutattuk, hogy ezen adalékanyagok hozzáadásával növelhető a szubsztrátok enzimes lebontásának hatékonysága. Cukorcirok alapú technológiák anyag- és energiamérlegének modellezésével igazoltuk, hogy a teljes termelési időszak alatt biztosítani lehet az üzem hőigényét a melléktermékek felhasználásával. (3) Bioszorbenseket állítottunk elő lignocellulóz típusú agro-hulladékokból (kipréselt repce pellet, keményítőmentes búzamag) kémiai módosításokkal, amelyek így alkalmasak voltak szervetlen illetve szerves anyagok (szennyezők) megkötésére. | (1) A wide range of biomass materials have been studied by thermal analysis and related methods. New knowledge was obtained on the thermal decomposition, combustion processes and gasification by CO2. The work contributed to a deeper understanding of the reactions taking place during various biomass utilization methods. Such reaction kinetic models were employed and developed that reflected the complexity of the studied materials and described larger series of experiments at various experimental conditions. (2) In the field of bioethanol production the effect of Tween 80 and PEG 4000 additives on five substrates (steam pretreated sweet sorghum bagasse, hemp, hemp hurds and two model substrates) was investigated at various temperatures. It was proven that these additives could increase the efficiency of enzymatic digestibility of these substrates. By modeling the mass and energy balances of sweet sorghum based technologies it was verified that the heat demand of the process can be covered during the whole production period by utilizing the by-products. (3) Biosorbents were prepared from lignocellulosic agricultural wastes (pressed rape seed pellet, starch free wheat seed) by chemical modifications. The products were suitable to bond organic and inorganic pollutants