Search results for "varieties"
showing 10 items of 67 documents
The ACM property for unions of lines in P1×P2
2021
This paper examines the Arithmetically Cohen-Macaulay (ACM) property for certain codimension 2 varieties in P1×P2 called sets of lines in P1×P2 (not necessarily reduced). We discuss some obstacles to finding a general characterization. We then consider certain classes of such curves, and we address two questions. First, when are they themselves ACM? Second, in a non-ACM reduced configuration, is it possible to replace one component of a primary (prime) decomposition by a suitable power (i.e. to “fatten” one line) to make the resulting scheme ACM? Finally, for our classes of such curves, we characterize the locally Cohen-Macaulay property in combinatorial terms by introducing the definition …
English Dialect “Default Singulars,” Was versus Were, Verner's Law, and Germanic Dialects
2008
A current suggestion in the variationist literature is that the predominance of forms like we was in nonstandard varieties of English is predictable in that was-generalization represents a case of the “default singular.” I argue that while the principle of the default singular is a sound one, it is not appropriate as an explanation for was-generalization. What is involved is not a matter of singular versus plural but of r-forms of the past tense of to be versus s-forms, with forms like were, war , wor representing the r-variant and was, wiz , wus the s-variant. The ancient Germanic s/r alternation has been leveled out in most dialects over the past millennium. Examination of Germanic dialec…
Valutazione bioagronomica e stabilità produttiva in genotipi di veccia comune (Vicia sativa L.).
2013
La Veccia (Vicia sativa L.) rappresenta per le regioni caldo-aride del bacino del Mediterraneo una specie di notevole interesse sia per la produzione di biomassa utile per l’alimentazione dei ruminanti, sia per la produzione di granella e sia per il posto che occupa all’interno degli avvicendamenti colturali asciutti. In Italia nonostante la produzione di seme certificato è abbastanza diffusa in quasi tutte le regioni del centro-sud, annualmente una quantità significativa di granella per uso zootecnico viene importata da Paesi europei ed extra-europei e poi utilizzata anche come seme non certificato. Per questo motivo si è ritenuto opportuno avviare uno studio del comportamento bio-agronomi…
Surfaces of minimal degree of tame representation type and mutations of Cohen–Macaulay modules
2017
We provide two examples of smooth projective surfaces of tame CM type, by showing that any parameter space of isomorphism classes of indecomposable ACM bundles with fixed rank and determinant on a rational quartic scroll in projective 5-space is either a single point or a projective line. For surfaces of minimal degree and wild CM type, we classify rigid Ulrich bundles as Fibonacci extensions. For the rational normal scrolls S(2,3) and S(3,3), a complete classification of rigid ACM bundles is given in terms of the action of the braid group in three strands.
Hyperbolic actions of the multiplicative group on affine varieties : exotic spaces and local structures
2015
This thesis is devoted to the study of affine T-varieties using the Altmann-Hausen presentation. We are especially interested in the case of hyperbolic actions of the multiplicative group Gm. In the first part, exotic affine spaces are studied, that is, smooth contractible affine varieties, assuming in addition that they are endowed with a Gm-action. In particular, in the case of dimension 3, we reinterpret the construction of Koras-Russell threefolds in terms of polyhedral divisors andwe give constructions of smooth contractible affine varieties and in dimensionslarger than 3.In the second part we consider the property of G-uniform rationality for a G-variety. This means that every point o…
Soil organic carbon storage capacity of old and modern wheat varieties
2022
Despite the possible mitigation of carbon emissions by favoring carbon transfer to terrestrial carbon sinks, little is knownabout the capacity of different crop genotypes to enhance soil carbon sequestration. We hypothesize that carbon sequestrationpotential linked to old wheat varieties (released before 1960) is higher than the one linked to modern ones while old varietiesare known to develop bigger and deeper root systems. Moreover, modern varieties are often cultivated using syntheticchemical inputs known to modify soil carbon dynamics. We conducted a field experiment by cultivating four modern andfour old wheat varieties, with and without chemical inputs (nitrogen, herbicide and fungici…
Carbon storage in soils by ancient and modern wheat varieties
2022
Les émissions anthropiques de gaz à effet de serre sont le principal moteur du changement climatique. Le plan Climat, issu de la COP 21 tenue à Paris en 2015, vise à atteindre la neutralité carbone à l'horizon 2050. Pour atteindre cette neutralité carbone, les gaz à effet de serre doivent d'abord être stabilisés, puis fortement réduits au cours du siècle prochain. Dans cette dynamique, l'initiative « 4 pour 1000 » fixe comme objectif d'atteindre un taux de croissance annuel du stock de carbone dans les sols de 0,4% par an. Ce stockage additionnel devrait compenser les émissions de CO2 dans l'atmosphère liée aux activités humaines. Les sols agricoles sont identifiés comme un compartiment de …
Il ruolo del contatto tra varietà tedesche e romanze nella costruzione «verbo più locativo»
2016
In this article we examine some effects of language contact in the multilingual province of Trento, where Romance and Germanic varieties have been in contact for centuries. We focus on the syntax of phrasal verbs (e. g. ‘go out’, ‘get away’) in Trentin, a Romance dialect group, in Fassan, a Rhaeto-romance variety, and in Cimbrian, a German(ic) minority language. In particular, we deal with two word order phenomena which might be attributed to contact with the more prestigious or widespread varieties spoken in the area: (i) in some Fassan phrasal verbs we find the order «Verb – XP – Locative element», which resembles the German order; (ii) in Cimbrian various syntactic positions are possible…
Vārdu savienojumu variācijas angļu valodas variantu tīmekļa korpusos
2020
Kopš pasaulē internets ir kļuvis aizvien pieejamāks, palielinājusies arī saziņa starp cilvēkiem visā pasaulē. Šāda informācijas apmaiņa var izraisīt globalizācijas efektu valodās vai valodu variantos, it īpaši valstiskajā līmenī. Neraugoties uz to, dažādi pētnieki ir analizējuši dažādās pasaules valstīs lietotās angļu valodas variāciju atšķirības, nevis līdzības. Tādējādi šā, uz korpusu balstītā pētījuma mērķis ir analizēt kolokācijas, pamatojoties uz izvēlēto lietvārdu sarakstu, kas veidots, izmantojot četras nacionālās angļu valodas variantus – amerikāņu, austrāliešu, britu un kanādiešu. Analīze tika veikta divos korpusos – Corpus of Global Web-Based English (GloWbE) un Corpus of Four Nat…
Nitrogen uptake and nitrogen fertilizer recovery in old and modern wheat genotypes grown in the presence or absence of interspecific competition
2015
Choosing genotypes with a high capacity for taking up nitrogen (N) from the soil and the ability to efficiently compete with weeds for this nutrient is essential to increasing the sustainability of cropping systems that are less dependent on auxiliary inputs. This research aimed to verify whether differences exist in N uptake and N fertilizer recovery capacity among wheat genotypes and, if so, whether these differences are related to a different competitive ability against weeds of wheat genotypes. To this end, 12 genotypes, varying widely in morphological traits and year of release, were grown in the presence or absence of interspecific competition (using Avena sativa L. as a surrogate wee…