scholarly journals Reconstruction of Projective Curves from the Derived Category

2021 ◽  
Vol -1 (-1) ◽  
Author(s):  
Dylan Spence
2021 ◽  
pp. 000183922110123
Author(s):  
Johnny Boghossian ◽  
Robert J. David

Categories are organized vertically, with product categories nested under larger umbrella categories. Meaning flows from umbrella categories to the categories beneath them, such that the construction of a new umbrella category can significantly reshape the categorical landscape. This paper explores the construction of a new umbrella category and the nesting beneath it of a product category. Specifically, we study the construction of the Quebec terroir products umbrella category and the nesting of the Quebec artisanal cheese product category under this umbrella. Our analysis shows that the construction of umbrella categories can unfold entirely separately from that of product categories and can follow a distinct categorization process. Whereas the construction of product categories may be led by entrepreneurs who make salient distinctive product attributes, the construction of umbrella categories may be led by “macro actors” removed from the market. We found that these macro actors followed a goal-derived categorization process: they first defined abstract goals and ideals for the umbrella category and only subsequently sought to populate it with product categories. Among the macro actors involved, the state played a central role in defining the meaning of the Quebec terroir category and mobilizing other macro actors into the collective project, a finding that suggests an expanded role of the state in category construction. We also found that market intermediaries are important in the nesting of product categories beneath new umbrella categories, notably by projecting identities onto producers consistent with the goals of the umbrella category. We draw on these findings to develop a process model of umbrella category construction and product category nesting.


2021 ◽  
pp. 000313482110111
Author(s):  
Ryan C. Pickens ◽  
Angela M. Kao ◽  
Mark A. Williams ◽  
Andrew C. Herman ◽  
Jeffrey S. Kneisl

Background In response to the COVID-19 pandemic, children’s hospitals across the country postponed elective surgery beginning in March 2020. As projective curves flattened, administrators and surgeons sought to develop strategies to safely resume non-emergent surgery. This article reviews challenges and solutions specific to a children’s hospital related to the resumption of elective pediatric surgeries. We present our tiered reentry approach for pediatric surgery as well as report early data for surgical volume and tracking COVID-19 cases during reentry. Methods The experience of shutdown, protocol development, and early reentry of elective pediatric surgery are reported from Levine’s Children’s Hospital (LCH), a free-leaning children’s hospital in Charlotte, North Carolina. Data reported were obtained from de-identified hospital databases. Results Pediatric surgery experienced a dramatic decrease in case volumes at LCH during the shutdown, variable by specialty. A tiered and balanced reentry strategy was implemented with steady resumption of elective surgery following strict pre-procedural screening and testing. Early outcomes showed a steady thorough fluctuating increase in elective case volumes without evidence of a surgery-associated positive spread through periprocedural tracking. Conclusion Reentry of non-emergent pediatric surgical care requires unique considerations including the impact of COVID-19 on children, each children hospital structure and resources, and preventing undue delay in intervention for age- and disease-specific pediatric conditions. A carefully balanced strategy has been critical for safe reentry following the anticipated surge. Ongoing tracking of resource utilization, operative volumes, and testing results will remain vital as community spread continues to fluctuate across the country.


1998 ◽  
Vol 174 (1) ◽  
pp. 241-251
Author(s):  
E. Ballico ◽  
C. Keem ◽  
S. J. Kim

2020 ◽  
Vol 2020 (762) ◽  
pp. 167-194
Author(s):  
Salim Tayou

AbstractWe prove the equidistribution of the Hodge locus for certain non-isotrivial, polarized variations of Hodge structure of weight 2 with {h^{2,0}=1} over complex, quasi-projective curves. Given some norm condition, we also give an asymptotic on the growth of the Hodge locus. In particular, this implies the equidistribution of elliptic fibrations in quasi-polarized, non-isotrivial families of K3 surfaces.


2011 ◽  
Vol 54 (3) ◽  
pp. 520-526
Author(s):  
A. Polishchuk

AbstractBuilding on the work of Nogin, we prove that the braid groupB4acts transitively on full exceptional collections of vector bundles on Fano threefolds withb2= 1 andb3= 0. Equivalently, this group acts transitively on the set of simple helices (considered up to a shift in the derived category) on such a Fano threefold. We also prove that on threefolds withb2= 1 and very ample anticanonical class, every exceptional coherent sheaf is locally free.


1998 ◽  
Vol 69 (1) ◽  
pp. 62-79 ◽  
Author(s):  
Katherine F Stevenson
Keyword(s):  

2001 ◽  
Vol 131 (3) ◽  
pp. 459-472 ◽  
Author(s):  
ALEXANDER ZIMMERMANN

In an earlier paper we studied the impact of equivalences between derived categories of group rings on their cohomology rings. Especially the group of auto-equivalences TrPic(RG) of the derived category of a group ring RG as introduced by Raphaël Rouquier and the author defines an action on the cohomology ring of this group. We study this action with respect to the restriction map, transfer, conjugation and the local structure of the group G.


2001 ◽  
Vol 44 (3) ◽  
pp. 549-569 ◽  
Author(s):  
Benjamin Steinberg

AbstractAdapting the theory of the derived category to ordered groupoids, we prove that every ordered functor (and thus every inverse and regular semigroup homomorphism) factors as an enlargement followed by an ordered fibration. As an application, we obtain Lawson’s version of Ehresmann’s Maximum Enlargement Theorem, from which can be deduced the classical theory of idempotent-pure inverse semigroup homomorphisms and $E$-unitary inverse semigroups.AMS 2000 Mathematics subject classification: Primary 20M18; 20L05; 20M17


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