Context-sensitive spatio-temporal memory

The proposed model, called the combinatorial and competitive spatio-temporal memory or CCSTM, provides an elegant solution to the general problem of having to store and recall spatio-temporal patterns in which states or sequences of states can recur in various contexts. For example, fig. 1 shows two state sequences that have a common subsequence, C and D. The CCSTM assumes that any state has a distributed representation as a collection of features. Each feature has an associated competitive module (CM) containing K cells. On any given occurrence of a particular feature, A, exactly one of the cells in CMA will be chosen to represent it. It is the particular set of cells active on the previous time step that determines which cells are chosen to represent instances of their associated features on the current time step. If we assume that typically S features are active in any state then any state has K^S different neural representations. This huge space of possible neural representations of any state is what underlies the model's ability to store and recall numerous context-sensitive state sequences. The purpose of this paper is simply to describe this mechanism

A Cortical Sparse Distributed Coding Model Linking Mini- and Macrocolumn-Scale Functionality

No generic function for the minicolumn – i.e., one that would apply equally well to all cortical areas and species – has yet been proposed. I propose that the minicolumn does have a generic functionality, which only becomes clear when seen in the context of the function of the higher-level, subsuming unit, the macrocolumn. I propose that: (a) a macrocolumn's function is to store sparse distributed representations of its inputs and to be a recognizer of those inputs; and (b) the generic function of the minicolumn is to enforce macrocolumnar code sparseness. The minicolumn, defined here as a physically localized pool of ∼20 L2/3 pyramidals, does this by acting as a winner-take-all (WTA) competitive module, implying that macrocolumnar codes consist of ∼70 active L2/3 cells, assuming ∼70 minicolumns per macrocolumn. I describe an algorithm for activating these codes during both learning and retrievals, which causes more similar inputs to map to more highly intersecting codes, a property which yields ultra-fast (immediate, first-shot) storage and retrieval. The algorithm achieves this by adding an amount of randomness (noise) into the code selection process, which is inversely proportional to an input's familiarity. I propose a possible mapping of the algorithm onto cortical circuitry, and adduce evidence for a neuromodulatory implementation of this familiarity-contingent noise mechanism. The model is distinguished from other recent columnar cortical circuit models in proposing a generic minicolumnar function in which a group of cells within the minicolumn, the L2/3 pyramidals, compete (WTA) to be part of the sparse distributed macrocolumnar code

Prognostic impact of the number of resected lymph node on survival in colorectal cancer

Introduction Colorectal Cancer (CRC) is the third most common cancer and the second leading cause of death in Western countries. In Portugal, in the North, emerges as the second most common cancer. The presence of lymph node metastasis is an important predictor of overall and disease-free survival and several studies recommend the evaluation of at least 12–14 regional lymph nodes, as it contributes to improve cancer staging and patient outcomes. Aims Epidemiological characterization of the studied population and identify a possible relationship between the number of lymph nodes evaluated in the surgical specimen and survival. Methods We preceded to the study of 1065 CCR patients, submitted to surgical resection between 1 January 2000 and 31 August 2012, in Braga Hospital. Discussion/Conclusion The results of the epidemiological characterization of this population are coincident with those described in the literature. It was observed a significant correlation between age, tumor size, serosal invasion, differentiation, tumor penetration, venous and lymphatic invasion, metastasis, TNM stage and the number of lymph nodes evaluated. However, we did not observe a statistically significant correlation between patient survival and number of lymph nodes evaluated (p > 0.05). A possible explanation is the practice of oncologists, addressing patients with less than 12 nodes identified in the surgical specimen as “N-positive” and undergoing adjuvant therapy. A better harvest and careful analysis of lymph nodes would lead to more accurate staging, avoiding overtreatment and side effects associated, and allow better economic management of hospital resources, in real N0 patients. Npatients. patients. patients.(undefined)info:eu-repo/semantics/publishedVersio

The Salmonella Mutagenicity Assay: The Stethoscope of Genetic Toxicology for the 21st Century

Objectives: According to the 2007 National Research Council report Toxicology for the Twenty-First Century, modern methods (e.g., "omics," in vitro assays, high-throughput testing, computational methods) will lead to the emergence of a new approach to toxicology. The Salmonella mammalian microsome mutagenicity assay has been central to the field of genetic toxicology since the 1970s. Here we document the paradigm shifts engendered by the assay, the validation and applications of the assay, and how the assay is a model for future in vitro toxicology assays. Data sources: We searched PubMed, Scopus, and Web of Knowledge using key words relevant to the Salmonella assay and additional genotoxicity assays. Data extraction: We merged the citations, removing duplicates, and categorized the papers by year and topic. Data synthesis: The Salmonella assay led to two paradigm shifts: that some carcinogens were mutagens and that some environmental samples (e.g., air, water, soil, food, combustion emissions) were mutagenic. Although there are > 10,000 publications on the Salmonella assay, covering tens of thousands of agents, data on even more agents probably exist in unpublished form, largely as proprietary studies by industry. The Salmonella assay is a model for the development of 21st century in vitro toxicology assays in terms of the establishment of standard procedures, ability to test various agents, transferability across laboratories, validation and testing, and structure-activity analysis. Conclusions: Similar to a stethoscope as a first-line, inexpensive tool in medicine, the Salmonella assay can serve a similar, indispensable role in the foreseeable future of 21st century toxicology

Human-Centered Design Components in Spiral Model to Improve Mobility of Older Adults

As humans grow older, their cognitive needs change more frequently due to distal and proximal life events. Designers and developers need to come up with better designs that integrate older users’ needs in a short period of time with more interaction with the users. Therefore, the positioning of human end users in the center of the design itself is not the key to the success of design artifacts while designing applications for older adults to use a smartphone as a promising tool for journey planner while using public transportation. This study analyzed the use of human-centered design (HCD) components, the spiral model, and the design for failure (DfF) approach to improve the interactions between older users and designers/developers in gathering usability needs in the concept stage and during the development of the app with short iterative cycles. To illustrate the importance of the applied approach, a case study with particular focus on older adults is presented.The results presented in this study are based on “Assistant” project funded by AAL JP, co-funded by the European Union. The authors would like to thank Dr. Stefan Carmien, my colleague in Assistant, for mentoring and for reading and making comments in the earlier versions of this chapter; participating research institutes; funding agencies; and companies from Finland, Spain, Austria, France, and the United Kingdom for their active support throughout the project