GRASP/VND Optimization Algorithms for Hard Combinatorial Problems

Two hard combinatorial problems are addressed in this thesis. The first one is known as the ”Max CutClique”, a combinatorial problem introduced by P. Martins in 2012. Given a simple graph, the goal is to find a clique C such that the number of links shared between C and its complement C C is maximum. In a first contribution, a GRASP/VND methodology is proposed to tackle the problem. In a second one, the N P-Completeness of the problem is mathematically proved. Finally, a further generalization with weighted links is formally presented with a mathematical programming formulation, and the previous GRASP is adapted to the new problem. The second problem under study is a celebrated optimization problem coming from network reliability analysis. We assume a graph G with perfect nodes and imperfect links, that fail independently with identical probability ρ ∈ [0,1]. The reliability RG(ρ), is the probability that the resulting subgraph has some spanning tree. Given a number of nodes and links, p and q, the goal is to find the (p,q)-graph that has the maximum reliability RG(ρ), uniformly in the compact set ρ ∈ [0,1]. In a first contribution, we exploit properties shared by all uniformly most-reliable graphs such as maximum connectivity and maximum Kirchhoff number, in order to build a novel GRASP/VND methodology. Our proposal finds the globally optimum solution under small cases, and it returns novel candidates of uniformly most-reliable graphs, such as Kantor-Mobius and Heawood graphs. We also offer a literature review, ¨ and a mathematical proof that the bipartite graph K4,4 is uniformly most-reliable. Finally, an abstract mathematical model of Stochastic Binary Systems (SBS) is also studied. It is a further generalization of network reliability models, where failures are modelled by a general logical function. A geometrical approximation of a logical function is offered, as well as a novel method to find reliability bounds for general SBS. This bounding method combines an algebraic duality, Markov inequality and Hahn-Banach separation theorem between convex and compact sets

Un jardín donde los senderos se unifurcan

Sobre El crítico (si pudiera cantar, me salvaría), de Juan Mayorga. Dirigida por Guillermo Heras. Con Horacio Peña y Pompeyo Audivert. En el teatro General San Martin. Corrientes 1530. Sala Cunill Cabanellas. Funciones: de miércoles a sábados, 21 hs; domingos 20 hs. Entrada: $70. Miércoles$40

Botero perdido en la curaduría de Teresa Anchorena

Sobre Botero, dibujos en tela y en papel, muestra de 50 dibujos de Fernando Botero. Curaduría de Teresa Anchorena. En el Museo Nacional de Bellas Artes

Cuando menos por menos da más

Sobre La reconstrucción, de Juan Taratuto. Con Diego Peretti, Alfredo Casero y Claudia Fontán

Tu casa, nuestra casa

Sobre Tu casa - ritual de un deseo primitivo, de Combinado Argentino de Danza (CAD). Dirigida por Andrea Servera. Con Laura Aguerreberry, Yésica Alonso y Nelson Barrios. En el Teatro General San Marti

A 28-nm CMOS pixel read-out ASIC for real-time tracking with time resolution below 20 ps

We present the development of a test ASIC, named Timespot1, designed in CMOS 28-nm technology, featuring a 32x32 pixel matrix and a pitch of 55 μm, The ASIC is conceived as the first prototype in a series, capable to read-out pixels with timing capabilities in the range of 30 ps and below. Each pixel is endowed with a charge amplifier, a discriminator and a Time-to-Digital-Converter, capable of time resolutions below 20 ps and read-out rates (per pixel) around 3 MHz. The timing performance are obtained respecting a power budget of about 50 μW per pixel, corresponding to a power density of approximately 2 W/cm 2 · This feature makes the Timespot1 approach an interesting solution for vertex detectors of the next generation of colliders, where high space and time resolutions will be mandatory requirements to cope with the huge amount of tracks per event to be detected and processed

Timespot1: A 28nm CMOS Pixel Read-Out ASIC for 4D Tracking at High Rates

We present the first characterization results of Timespot1, an ASIC designed in CMOS 28 nm technology, featuring a $32 \times 32$ pixel matrix with a pitch of $55 ~ \mu m$. Timespot1 is the first small-size prototype, conceived to readout fine-pitch pixels with single-hit time resolution below $50 ~ ps_\text{rms}$ and input rates of several hundreds of kilohertz per pixel. Such experimental conditions will be typical of the next generation of high-luminosity collider experiments, from the LHC run5 and beyond. Each pixel of the ASIC includes a charge amplifier, a discriminator, and a Time-to-Digital Converter with time resolution indicatively of $22.6 ~ ps_\text{rms}$ and maximum readout rates (per pixel) of $3 ~ MHz$. To respect system-level constraints, the timing performance has been obtained keeping the power budget per pixel below $40 ~ \mu W$. The ASIC has been tested and characterised in the laboratory concerning its performance in terms of time resolution, power budget and sustainable rates. The ASIC will be hybridized on a matched $32 \times 32$ pixel sensor matrix and will be tested under laser beam and Minimum Ionizing Particles in the laboratory and at test beams. In this paper we present a description of the ASIC operation and the first results obtained from characterization tests concerning its performance

CMOS IC RADIATION HARDENING BY DESIGN

Design techniques for radiation hardening of integrated circuits in commercial CMOS technologies are presented. Circuits designed with the proposed approaches are more tolerant to both total dose and to single event effects. The main drawback of the techniques for radiation hardening by design is the increase of silicon area, compared with a conventional design

Wound Retractor Laparoscopic Port System for Laparoscopic Ovariectomy in Panthera leo

The aim of this study was to assess the feasibility and intraoperative complications of performing ovariectomies in African lionesses (Panthera leo) using a wound retractor laparoscopic platform. Six lionesses (n = 6) were included. The surgical procedures were carried out through three portals, with a retractor platform positioned at the umbilical port and cannulas placed 3–4 cm from the cranial and caudal regions to the device at the level of the midline. An ovariectomy was performed with a vessel-sealing device. We evaluated the surgery time and the intraoperative and early postoperative complications. The mean weight was 172.83 kg. The total surgery time was 49.33 min. The installation step took a mean of 10.33 min to complete. The mean ovariectomy time was 20 min. Controlled bleeding was observed at the tip of the uterine horn in two cases due to excessive tissue thickness. The retrieval of dissected ovarian tissue and annexes was easily performed. No other complications were observed. The use of the laparoscopic platform during three-portal surgeries for laparoscopic ovariectomy in adult overweight lionesses is feasible and without intraoperative problems. The retractor meant that there were no entry-related issues due to the 25 mm mini-laparotomy. It also made it simpler to extract thick ovaries and promptly re-establish the pneumoperitoneum