Combed 3-Manifolds with Concave Boundary, Framed Links, and Pseudo-Legendrian Links

We provide combinatorial realizations, according to the usual objects/moves scheme, of the following three topological categories: (1) pairs (M,v) where M is a 3-manifold (up to diffeomorphism) and v is a (non-singular vector) field, up to homotopy; here possibly the boundary of M is non-empty and v may be tangent to the boundary, but only in a concave fashion, and homotopy should preserve tangency type; (2) framed links L in M, up to framed isotopy; (3) triples (M,v,L), with (M,v) as above and L transversal to v, up to pseudo-Legendrian isotopy (transversality-preserving simultaneous homotopy of v and isotopy of L). All realizations are based on the notion of branched standard spine, and build on results previously obtained. Links are encoded by means of diagrams on branched spines, where the diagram is smooth with respect to the branching. Several motivations for being interested in combinatorial realizations of the topological categories considered in this paper are given in the introduction. The encoding of links is suitable for the comparison of the framed and the pseudo-Legendrian categories, and some applications are given in connection with contact structures, torsion and finite-order invariants. An estension of Trace's notion of winding number of a knot diagram is introduced and discussed.Comment: 38 pages, 33 figure

Volume and homology of one-cusped hyperbolic 3-manifolds

Let M be a complete, finite-volume, orientable hyperbolic manifold having exactly one cusp. If we assume that pi_1(M) has no subgroup isomorphic to a genus-2 surface group, and that either (a) H_1(M;Z_p) has dimension at least 5 for some prime p, or (b) H_1(M;Z_2) has dimension at least 4, and the subspace of H^2(M;Z_2) spanned by the image of the cup product has dimension at most 1, then vol M > 5.06 If we assume that H_1(M;Z_2) has dimension at least 7, and that the compact core of M does not contain a genus-2 closed incompressible surface, then vol M > 5.06.Comment: 31 pages. This version agrees with the published version of the paper, except that an error in the published abstract has been corrected. In particular, the result which applies to manifolds with mod 2 homology of dimension at least 7 is stronger and has a shorter proof than the corresponding result in version

Noncyclic covers of knot complements

Hempel has shown that the fundamental groups of knot complements are residually finite. This implies that every nontrivial knot must have a finite-sheeted, noncyclic cover. We give an explicit bound, $\Phi (c)$, such that if $K$ is a nontrivial knot in the three-sphere with a diagram with $c$ crossings and a particularly simple JSJ decomposition then the complement of $K$ has a finite-sheeted, noncyclic cover with at most $\Phi (c)$ sheets.Comment: 29 pages, 8 figures, from Ph.D. thesis at Columbia University; Acknowledgments added; Content correcte

Experimental Brain Death Models in Liver Transplantation

Most organs for transplantation are currently procured from brain-dead donors; however, brain death is an important risk factor in liver transplantation. In addition, to counteract the shortage of liver grafts, transplant centers accept the use of sub-optimal livers, which may show higher risk of primary non-function or initial poor function. Very few literatures exist regarding liver transplantation using brain-dead donors, or about brain death and its effects on sub-optimal grafts in such surgical situation. This chapter aims to describe the pathophysiological changes occurring in liver grafts during brain death and focuses on the strengths and limitations of experimental models used to study the effect of brain death on optimal and sub-optimal (specially steatotic) liver grafts. Depending on the use of experimental models that simulate as much as possible the surgical conditions present in clinical practice, therapeutic strategies designed in animal models could be more successfully translated to the bedside

Ischemic Preconditioning Directly or Remotely Applied on the Liver to Reduce Ischemia-Reperfusion Injury in Resections and Transplantation

Ischemia-reperfusion (I/R) injury is an important cause of liver damage occurring during surgical procedures. In liver resection, I/R causes post-operative transaminasemia and liver function failure. In liver transplantation, I/R causes graft dysfunction, ranging from biochemical abnormalities to primary non-function of the transplanted organ. Ischemic preconditioning is a surgical strategy to reduce the severity of I/R and improve post-operative outcomes by prior exposure to a brief period of vascular occlusion directly to the target organ or remotely to a distant vascular bed. This chapter aims to discuss the different ischemic preconditioning strategies in both liver resection surgery and liver transplantation. In addition, we will describe the differences of such surgical strategies in both steatotic and non-steatotic livers in both preclinical experiments and clinical practice. Such information may be useful to guide the design of the effective ischemic preconditioning methods in the surgery of hepatic resections and liver transplantation

Current Knowledge about the Effect of Nutritional Status, Supplemented Nutrition Diet, and Gut Microbiota on Hepatic Ischemia-Reperfusion and Regeneration in Liver Surgery

Ischemia-reperfusion (I/R) injury is an unresolved problem in liver resection and transplantation. The preexisting nutritional status related to the gut microbial profile might contribute to primary non-function after surgery. Clinical studies evaluating artificial nutrition in liver resection are limited. The optimal nutritional regimen to support regeneration has not yet been exactly defined. However, overnutrition and specific diet factors are crucial for the nonalcoholic or nonalcoholic steatohepatitis liver diseases. Gut-derived microbial products and the activation of innate immunity system and inflammatory response, leading to exacerbation of I/R injury or impaired regeneration after resection. This review summarizes the role of starvation, supplemented nutrition diet, nutritional status, and alterations in microbiota on hepatic I/R and regeneration. We discuss the most updated effects of nutritional interventions, their ability to alter microbiota, some of the controversies, and the suitability of these interventions as potential therapeutic strategies in hepatic resection and transplantation, overall highlighting the relevance of considering the extended criteria liver grafts in the translational liver surgery.This research was supported by the Ministerio de Ciencia, Innovacion y Universidades (RTI2018-095114-B-I00) Madrid, Spain; European Union (Fondos Feder, “una manera de hacer Europa”); CERCA Program/Generalitat de Catalunya and Secretaria d’Universitats I Recerca del Departament d’Economia I Coneixement (2017 SGR-551) Barcelona, Spain

Hepatic Regeneration Under Warm or Cold Ischemia Conditions: Controversies and New Approaches

Ischemia-reperfusion (I/R) associated with hepatic resection and living related liver transplantation is an unsolved problem in clinical practice. Indeed, I/R induces damage and regenerative failure in clinical liver surgery. Signaling pathways regarding the pathophysiology of liver I/R and regeneration making clear distinction between situations of cold and warm ischemia, as well as liver regeneration with or without vascular occlusion, will be addressed. The different experimental models used to date to improve the postoperative outcomes in clinical liver surgery will be also described. Furthermore, the most updated therapeutic strategies, as well as the clinical and scientific controversies in the field, will be discussed. Such information may be useful to guide the design of better experimental models as well as the effective therapeutic strategies in liver surgery that can succeed in achieving its clinical application

New Perspectives on the Use of Sub-Optimal Donor Livers

Liver transplantation is the therapy of choice for patients with end-stage liver disease. However, a shortage of donor organs remains a major obstacle to the widespread application of liver transplantation. To overcome this problem, transplant centers have developed strategies to expand the organ donor pool, including the routine use of sub-optimal donor livers. However, these have an increased risk of initial poor function or primary non-function that may cause greater risk of morbidity in the recipient. This chapter aims to describe the pathophysiological changes that may occur in sub-optimal donor livers, focusing on viral infections, since, after transplantation, infection of the graft is almost universal and can lead to chronic hepatitis, cirrhosis, and graft failure. The different experimental models as well as the clinical outcomes of the transplantation of sub-optimal donor livers with viral infections will be discussed. Such information may be useful to guide the design of better experimental models than those described to date as well as the effective use of sub-optimal livers with successful clinical application

"Not wishing to be the white rhino in the crowd" : disability-disclosure at University

This article reports on a qualitative study identifying the drivers for and boundaries to disability-disclosure in interability interactions as experienced by 13 students with physical impairments at five Belgian higher education institutions. Through surveys and in-depth interviews, the study explored whether the students experience, prefer, and expect differences in communication about their impairments with temporarily able-bodied peers, instructors, and staff. Interviews provided insight into the nuances of disclosure and topic avoidance decisions that differ by disclosure target: disabilitydisclosure is mainly a balancing act between fulfilling physical needs and maintaining a normal, positive identity. The visibility of impairments seems to play a minor role in the students’ initial orientation toward disclosing. The functions of disability-disclosure as posited by the Communication Predicament of Disability Model and the CARE-keys to effective interability communication (i.e., Contact, Ask, Respect, Empathy) are discussed as well as the implications of the findings for Communication Accommodation Theory

Un approccio innovativo per una migliore comprensione dell’interazione sismica tra suolo e strutture: il test site di Ferrara

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