A Necessary and Sufficient Condition for the Existence of an (n,r)-arc in PG(2,q) and Its Applications

ACM Computing Classification System (1998): E.4.

Classification of the Maximal Subsemigroups of the Semigroup of all Partial Order-Preserving Transformations

Илинка А. Димитрова, Цветелина Н. Младенова - Моноида P Tn от всички частични преобразования върху едно n-елементно множество относно операцията композиция на преобразования е изучаван в различни аспекти от редица автори. Едно частично преобразование α се нарича запазващо наредбата, ако от x ≤ y следва, че xα ≤ yα за всяко x, y от дефиниционното множество на α. Обект на разглеждане в настоящата работа е моноида P On състоящ се от всички частични запазващи наредбата преобразования. Очевидно P On е под-моноид на P Tn. Направена е пълна класификация на максималните подполугрупи на моноида P On. Доказано е, че съществуват пет различни вида максимални подполугрупи на разглеждания моноид. Броят на всички максимални подполугрупи на POn е точно 2^n + 2n − 2.

The Maximal Number of Particles in a Branching Process with State-Dependent Immigration

AMS subject classification: 60J80, 60J15.

Maximal Number of Successors in a Nginar(1) Process

2000 Mathematics Subject Classification: 60J80, 60J20, 60J10, 60G10, 60G70, 60F99.

Classification of Maximal Optical Orthogonal Codes of Weight 3 and Small Lengths

Dedicated to the memory of the late professor Stefan Dodunekov on the occasion of his 70th anniversary. We classify up to multiplier equivalence maximal (v, 3, 1) optical orthogonal codes (OOCs) with v ≤ 61 and maximal (v, 3, 2, 1) OOCs with v ≤ 99. There is a one-to-one correspondence between maximal (v, 3, 1) OOCs, maximal cyclic binary constant weight codes of weight 3 and minimum dis tance 4, (v, 3; ⌊(v − 1)/6⌋) difference packings, and maximal (v, 3, 1) binary cyclically permutable constant weight codes. Therefore the classification of (v, 3, 1) OOCs holds for them too. Some of the classified (v, 3, 1) OOCs are perfect and they are equivalent to cyclic Steiner triple systems of order v and (v, 3, 1) cyclic difference families.

Benthic foraminiferal record of the Pleistocene uplift of the sedimentary deposits of the Burica Peninsula (Costa Rica-Panama) as a result of Cocos Ridge subduction beneath the Central American Arc

This study used paleobathymetric interpretations from benthic foraminiferal assemblages to determine the timing of the initial subduction of the Cocos Ridge beneath the Costa Rica-Panama Arc and the associated amount of uplift. Forty-seven samples from four stratigraphic sections of the Burica and the Armuelles formations yielded 217 identified species. Foraminiferal paleoecology and cluster analyses indicated paleobathymetric differences within and between the sections. Maximum and minimum uplift rates were calculated from the biochronology, elevation, paleobathymetry and estimated eustatic changes. Large decreases in paleobathymetry were mainly due to the initial middle Pleistocene subduction of the Cocos Ridge in less than 0.5 Ma. Uplift rates were uneven across the Burica Peninsula, as follows: La Vaca 4.5–0.8 m/ky, Rabo de Puerco 2.8–0.7 m/ky, San Bartolo–Chiquito 2.7–0.8 m/ky, and eastern coast 8.0–1.5 m/ky. These differences probably resulted from Cocos Ridge asymmetry and differential uplift of tectonic blocks.

Arc crust-magma interaction in the Andean Southern Volcanic Zone from thermobarometry, mineral composition, radiogenic isotope and rare earth element systematics of the Azufre-Planchon-Peteroa volcanic complex, Chile

The Andean Southern Volcanic Zone (SVZ) is a vast and complex continental arc that has been studied extensively to provide an understanding of arc-magma genesis, the origin and chemical evolution of the continental crust, and geochemical compositions of volcanic products. The present study focuses on distinguishing the magma/sub-arc crustal interaction of eruptive products from the Azufre-Planchon-Peteroa (APP 35°15'S) volcanic center and other major centers in the Central SVZ (CSVZ 37°S–42°S), Transitional SVZ (TSVZ 34.3–37.0°S), and Northern SVZ (NSVZ 33°S–34°30'S). New Hf and Nd isotopic and trace element data for SVZ centers are consistent with former studies that these magmas experienced variable depths of crystal fractionation, and that crustal assimilation is restricted to the lower crustal depths with an apparent role of garnet. Thermobarometric calculations applied to magma compositions constrain the depth of magma separation from mantle sources in all segments of the SVZ to(70-90 km). Magmatic separation at the APP complex occurs at an average depth of ~50 km which is confined to the mantle lithosphere and the base of the crust suggesting localized thermal abrasion both reservoirs. Thermobarometric calculations indicate that CSVZ primary magmas arise from a similar average depth of (~54 km) which confines magma separation to the asthenospheric mantle. The northwards along-arc Sr-Nd-Hf isotopic data and LREE enrichment accompanied with HREE depletion of SVZ mafic magmas correlates well with northward increasing crustal thickness and decreasing primary melt separation from mantle source regions indicating an increased involvement of lower crustal components in SVZ magma petrogenesis. ^ The study concludes that the development of mature subduction zones over millions of years of continuous magmatism requires that mafic arc derived melts stagnate at lower crustal levels due to density similarities and emplace at lower crustal depths. Basaltic underplating creates localized hot zone environments below major magmatic centers. These regions of high temperature/partial melting, and equilibration with underplated mafic rocks provides the mechanism that controls trace element and isotopic variability of primary magmas of the TSVZ and NSVZ from their baseline CSVZ-like precursors.^

Valutazione dosimetrica e aspetti tecnici di trattamenti VMAT (Volumetric Modulated Arc Therapy) in radioterapia oncologica

La VMAT (Volumetric Modulated Arc Therapy) è una delle più recenti tecniche radioterapiche, in cui, oltre alla modulazione geometrica della fluenza del campo di radiazione come avviene nell’IMRT (Intensity Modulated Radiotherapy), sono variati durante il trattamento anche la velocità del gantry e il rateo di dose. La radiazione è erogata senza interruzioni lungo uno o più archi continui della testata dell’acceleratore, così da ridurre i tempi di trattamento in modo sostanziale rispetto all’IMRT. Nelle tecniche ad intensità modulata, ed in particolare nella VMAT, il lettino porta paziente modifica la distribuzione di dose durante gli irraggiamenti posteriori, riducendo quella al target e aumentando quella superficiale. Il presente lavoro di tesi, che ha proprio l’obiettivo di valutare questi aspetti dosimetrici in un’ottica pre-clinica, è stato svolto presso il Servizio di Fisica Sanitaria del Policlinico S.Orsola–Malpighi, Azienda Ospedaliero-Universitaria di Bologna. Le misure sono state effettuate presso le U.O. Radioterapia-Morganti e Radioterapia-Frezza f.f. della medesima Azienda Sanitaria, al fine di caratterizzare dal punto di vista dosimetrico il lettino di trattamento iBEAM evo dell’acceleratore lineare Synergy Elekta. L’attenuazione misurata in caso di incidenza perpendicolare del fascio sul lettino, in buon accordo con gli articoli di riferimento, è stata: (2.81±0.06)% per fotoni di energia di 6 MV, (1.81±0.10)% a 10 MV e (1.38±0.05)% a 15 MV. L’attenuazione massima misurata con fotoni di energia di 6 MV si è avvicinata al 4% negli irraggiamenti obliqui. Infine, è stato analizzato il confronto con statistica gamma fra distribuzione di dose pianificata e misurata prima e dopo aver modellizzato le caratteristiche del lettino nel software per l’elaborazione del piano di trattamento. Solo dopo tale operazione, i due casi VMAT analizzati (tumore dell’orofaringe e prostatico) superano i criteri più restrittivi e affidabili utilizzati nella pratica clinica.

Claude-Nicolas Ledoux et la ville "utopique" d'Arc-et-Senans

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

Modulation du système sympathique et du système rénine-angiotensine chez le patient insuffisant cardiaque : quantification de l'effet pharmacologique par l'épreuve d'effort sous-maximal

Thèse numérisée par la Direction des bibliothèques de l'Université de Montréal.

Effets de l'entraînement physique sur la tolérance à l'effort maximal, l'incompétence chronotrope et la fréquence cardiaque de récupération

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

Claude-Nicolas Ledoux et la ville "utopique" d'Arc-et-Senans

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

Modulation du système sympathique et du système rénine-angiotensine chez le patient insuffisant cardiaque : quantification de l'effet pharmacologique par l'épreuve d'effort sous-maximal

Thèse numérisée par la Direction des bibliothèques de l'Université de Montréal.

Effets de l'entraînement physique sur la tolérance à l'effort maximal, l'incompétence chronotrope et la fréquence cardiaque de récupération

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.