Random-energy model in random fields

The random-energy model is studied in the presence of random fields. The problem is solved exactly both in the microcanonical ensemble, without recourse to the replica method, and in the canonical ensemble using the replica formalism. The phase diagrams for bimodal and Gaussian random fields are investigated in detail. In contrast to the Gaussian case, the bimodal random field may lead to a tricritical point and a first-order transition. An interesting feature of the phase diagram is the possibility of a first-order transition from paramagnetic to mixed phase.Comment: 18 pages, 5 figures (included

Associação entre características de desempenho de tilápia-do-nilo ao longo do período de cultivo.

O objetivo deste trabalho foi estimar as herdabilidades e a estrutura de correlações genéticas entre as características de desempenho de tilápia-do-nilo (Oreochromis niloticus) da linhagem GIFT, em diferentes estágios do ciclo de produção. As tilápias foram cultivadas em tanques - rede. Mediu-se ganho em peso diário total, peso vivo e ganho em peso diário, em quatro períodos, com intervalos de aproximadamente 30 dias. Foram realizadas análises unicaracter para as medidas, em todas as biometrias e, nas análises bicaracter, as medidas de mesma característica foram combinadas duas a duas e com o ganho em peso diário total. As estimações de herdabilidade variaram de 0,15 a 0,11 para peso vivo, 0,16 a 0,09 para ganho em peso diário e 0,17 a 0,12 para ganho em peso diário total, nas análises unicaracter. Os valores estimados de correlação genética para peso vivo e ganho em peso diário, associados ao ganho em peso diário total, variaram entre 0,37 a 0,98 e 0,74 a 0,8 respectivamente. A forte associação genética estimada entre peso vivo em biometrias intermediárias e ganho em peso diário total sugere que a seleção para velocidade de crescimento pode ser realizada de forma precoce

DMC-GRASP: A continuous GRASP hybridized with data mining

The hybridization of metaheuristics with data mining techniques has been successfully applied to combinatorial optimization problems. Examples of this type of strategy are DM-GRASP and MDM-GRASP, hybrid versions of the Greedy Randomized Adaptive Search Procedure (GRASP) metaheuristic, which incorporate data mining techniques. This type of hybrid method is called Data-Driven Metaheuristics and aims at extracting useful knowledge from the data generated by metaheuristics in their search process. Despite success in combinatorial problems like the set packing problem and maximum diversity problem, proposals of this type to solve continuous optimization problems are still scarce in the literature. This work presents a data mining hybrid version of C-GRASP, an adaptation of GRASP for problems with continuous variables. We call this new version DMC-GRASP, which identifies patterns in high-quality solutions and generates new solutions guided by these patterns. We performed computational experiments with DMC-GRASP on a set of well-known mathematical benchmark functions, and the results showed that metaheuristics for continuous optimization could also benefit from using patterns to guide the search for better solutions

Influence of different restorative materials on the stress distribution in dental implants

To assist clinicians in deciding the most suitable restorative materials to be used in the crowns and abutment in implant rehabilitation. For finite element analysis (FEA), a regular morse taper implant was created using a computer aided design software. The implant was inserted at the bone model with 3 mm of exposed threads. An anatomic prosthesis representing a first maxillary molar was modeled and cemented on the solid abutment. Considering the crown material (zirconia, chromium-cobalt, lithium disilicate and hybrid ceramic) and abutment (Titanium and zirconia), the geometries were multiplied, totaling eight groups. In order to perform the static analysis, the contacts were considered bonded and each material was assigned as isotropic. An axial load (200 N) was applied on the crown and fixation occurred on the base of the bone. Results using Von-Mises criteria and micro strain values were obtained. A sample identical to the CAD model was made for the Strain Gauge (SG) analysis; four SGs were bonded around the implant to obtain micro strain results in bone tissue. FEA results were 3.83% lower than SG. According to the crown material, it is possible to note that the increase of elastic modulus reduces the stress concentration in all system without difference for bone. Crown materials with high elastic modulus are able to decrease the stress values in the abutments while concentrates the stress in its structure. Zirconia abutments tend to concentrate more stress throughout the prosthetic system and may be more susceptible to mechanical problems than titanium

The CD6 interactome orchestrates ligand-independent T cell inhibitory signaling

Background: T-cell membrane scaffold proteins are pivotal in T cell function, acting as versatile signaling hubs. While CD6 forms a large intracellular signalosome, it is distinguished from typical scaffolds like LAT or PAG by possessing a substantial ectodomain that binds CD166, a well-characterized ligand expressed on most antigen-presenting cells (APC), through the third domain (d3) of the extracellular region. Although the intact form of CD6 is the most abundant in T cells, an isoform lacking d3 (CD6∆d3) is transiently expressed on activated T cells. Still, the precise character of the signaling transduced by CD6, whether costimulatory or inhibitory, and the influence of its ectodomain on these activities are unclear. Methods: We expressed CD6 variants with extracellular deletions or cytosolic mutations in Jurkat cells containing eGFP reporters for NF-κB and NF-AT transcription factor activation. Cell activation was assessed by eGFP flow cytometry following Jurkat cell engagement with superantigen-presenting Raji cells. Using imaging flow cytometry, we evaluated the impact of the CD6-CD166 pair on cell adhesiveness during the antigen-dependent and -independent priming of T cells. We also examined the role of extracellular or cytosolic sequences on CD6 translocation to the immunological synapse, using immunofluorescence-based imaging. Results: Our investigation dissecting the functions of the extracellular and cytosolic regions of CD6 revealed that CD6 was trafficked to the immunological synapse and exerted tonic inhibition wholly dependent on its cytosolic tail. Surprisingly, however, translocation to the synapse occurred independently of the extracellular d3 and of engagement to CD166. On the other hand, CD6 binding to CD166 significantly increased T cell:APC adhesion. However, this activity was most evident in the absence of APC priming with superantigen, and thus, in the absence of TCR engagement. Conclusions: Our study identifies CD6 as a novel ‘on/off’ scaffold-receptor capable of modulating responsiveness in two ways. Firstly, and independently of ligand binding, it establishes signaling thresholds through tonic inhibition, functioning as a membrane-bound scaffold. Secondly, CD6 has the capacity for alternative splicing-dependent variable ligand engagement, modulating its checkpoint-like activity

Reservoir engineering with arbitrary temperatures for spin systems and quantum thermal machine with maximum efficiency

Abstract Reservoir engineering is an important tool for quantum information science and quantum thermodynamics since it allows for preparing and/or protecting special quantum states of single or multipartite systems or to investigate fundamental questions of the thermodynamics as quantum thermal machines and their efficiencies. Here we employ this technique to engineer reservoirs with arbitrary (effective) negative and positive temperatures for a single spin system. To this end, we firstly engineer an appropriate interaction between a qubit system, a carbon nuclear spin, to a fermionic reservoir, in our case a large number of hydrogen nuclear spins that acts as the spins bath. This carbon-hydrogen structure is present in a polycrystalline adamantane, which was used in our experimental setup. The required interaction engineering is achieved by applying a specific sequence of radio-frequency pulses using Nuclear Magnetic Resonance (NMR), while the temperature of the bath can be controlled by appropriate preparation of the initial hydrogen nuclear spin state, being the predicted results in very good agreement with the experimental data. As an application we implemented a single qubit quantum thermal machine which operates at a single reservoir at effective negative temperature whose efficiency is always 100%, independent of the unitary transformation performed on the qubit system, as long as it changes the qubit state.Comment: 7 pages, 6 figure

Evaluation of antimicrobial activity against Enterococcus faecalis of activated chelating agents in different final rinse protocols : an ex vivo study

To evaluate the antimicrobial activity of the following chelating agents against Enterococcus faecalis using quantitative polymerase chain reaction (qPCR) analysis: 1% peracetic acid (PA), 1% peracetic acid with 0.1% cetrimide (PAC), and 17% ethylenediam