61 research outputs found
Quantum modularity and complex Chern-Simons theory
No full textThe Quantum Modularity Conjecture of Zagier predicts the existence of a formal power series with arithmetically interesting coefficients that appears in the asymptotics of the Kashaev invariant at each root of unity. Our goal is to construct a power series from a Neumann-Zagier datum (i.e., an ideal triangulation of the knot complement and a geometric solution to the gluing equations) and a complex root of unity ζ. We prove that the coefficients of our series lie in the trace field of the knot, adjoined a complex root of unity. We conjecture that our series are those that appear in the Quantum Modularity Conjecture and confirm that they match the numerical asymptotics of the Kashaev invariant (at various roots of unity) computed by Zagier and the first author. Our construction is motivated by the analysis of singular limits in Chern-Simons theory with gauge group SL(2,C) at fixed level k, where ζk=1
Variations in the Number of Circulating Tumor Cells During the Surgical Sequence for Locally Advanced Rectal Cancer
No full textNew experimental model for single liver lobe hyperthermia in small animals using non-directional microwaves.
No full textOur aim was to develop a new experimental model for in vivo hyperthermia using non-directional microwaves, applicable to small experimental animals. We present an affordable approach for targeted microwave heat delivery to an isolated liver lobe in rat, which allows rapid, precise and stable tissue temperature control.A new experimental model is proposed. We used a commercial available magnetron generating 2450 MHz, with 4.4V and 14A in the filament and 4500V anodic voltage. Modifications were required in order to adjust tissue heating such as to prevent overheating and to allow for fine adjustments according to real-time target temperature. The heating is controlled using a virtual instrument application implemented in LabView® and responds to 0.1° C variations in the target. Ten healthy adult male Wistar rats, weighing 250-270 g were used in this study. The middle liver lobe was the target for controlled heating, while the rest of the living animal was protected.In vivo microwave delivery using our experimental setting is safe for the animals. Target tissue temperature rises from 30°C to 40°C with 3.375°C / second (R2 = 0.9551), while the increment is lower it the next two intervals (40-42°C and 42-44°C) with 0.291°C/ s (R2 = 0.9337) and 0.136°C/ s (R2 = 0.7894) respectively, when testing in sequences. After reaching the desired temperature, controlled microwave delivery insures a very stable temperature during the experiments.We have developed an inexpensive and easy to manufacture system for targeted hyperthermia using non-directional microwave radiation. This system allows for fine and stable temperature adjustments within the target tissue and is ideal for experimental models testing below or above threshold hyperthermia
Categorical aspects of BPS states
No full textThis dissertation is devoted to the study of categorical aspects of BPS states in two-dimensional quantum field theories with N=(2,2) supersymmetry. The basic aim of a categorical discussion is to study spaces of BPS states, which carry much more refined information than their traditionally studied characters. In a two-dimensional theory, whereas BPS states are supersymmetric states defined on a one-dimensional spatial slice, carrying out the discussion at a categorical level requires one to incorporate two-dimensional supersymmetric instantons. We motivate these instantons and the differential equations they obey in a broader physical context. We show how these instanton effects can be incorporated to result in a categorification of the Cecotti-Vafa wall-crossing formula. We generalize the discussion to incorporate two-dimensional theories with non-trivial twisted mass terms. The presence of twisted masses require us to incorporate Fock spaces of periodic solitons into the discussion, and we show how these Fock spaces affect the categorical wall-crossing formalism. We sketch two important future directions. The first involves the application of the ideas of this thesis to the study of three-manifolds and homological knot invariants. The second has us graduate from two-dimensional theories and enter the world of four-dimensional N=2 theories and their BPS states.Ph.D.Includes bibliographical reference
Histopathology report on colon cancer specimens; measuring surgical quality, an increasing stress for surgeons
No full textIntroduction. Improving the quality of surgical resections by evaluating surgical specimens is probably the most important feedback a surgeon can receive. Moreover, prognosis of patients with colon cancer is based on achieving appropriate resection margins and assessment of lymph node status. For these reasons we aim to provide a retrospective analysis on colon cancer specimens operated by a single surgical team.
Materials and Methods. 88 patients operated between 2013 and 2016 were included in the study. Data were gathered prospectively and assessed by multivariate analysis for the main variables (age, gender, tumor staging, specimen length, distance to closest resection margin, number of lymph nodes, and number of positive lymph nodes).
Results. The mean number of lymph nodes excised was 31,9, with more after right colectomies (39.6) than after left colonic resections (29.1). The average specimen length was 29.2cm after right colectomies, 35.6cm after left hemicolectomies and 18cm after segmental colectomies. There was a significant correlation between the number of lymph nodes, specimen length, and age of patients.
Conclusion. Lymph node status is correlated with specimen length and age. The standard of 12 lymph nodes was achieved and surpassed, being comparable to the benchmark literature. Standards on colon resections need to be reevaluated as many surgeons are pressured by quality measurements which do not always reflect sound oncologic principles
Solid-Phase Synthesized Copolymers for the Assembly of pH-Sensitive Micelles Suitable for Drug Delivery Applications
No full textDiblock copolymers of polyhistidine are known for their self-assembly into micelles and their pH-dependent disassembly due to the amphiphilic character of the copolymer and the unsaturated imidazole groups that undergo a hydrophobic-to-hydrophilic transition in an acidic pH. This property has been largely utilized for the design of drug delivery systems that target a tumor environment possessing a slightly lower extracellular pH (6.8–7.2). The main purpose of this study was to investigate the possibility of designed poly(ethylene glycol)-polyhistidine sequences synthesized using solid-phase peptide synthesis (SPPS), to self-assemble into micelles, to assess the ability of the corresponding micelles to be loaded with doxorubicin (DOX), and to investigate the drug release profile at pH values similar to a malignant extracellular environment. The designed and assembled free and DOX-loaded micelles were characterized from a physico-chemical point of view, their cytotoxicity was evaluated on a human breast cancer cell line (MDA-MB-231), while the cellular areas where micelles disassembled and released DOX were assessed using immunofluorescence. We concluded that the utilization of SPPS for the synthesis of the polyhistidine diblock copolymers yielded sequences that behaved similarly to the copolymeric sequences synthesized using ring-opening polymerization, while the advantages of SPPS may offer facile tuning of the histidine site or the attachment of a large variety of functional molecules
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