Mean-Field Theory of Meta-Learning

We discuss here the mean-field theory for a cellular automata model of meta-learning. The meta-learning is the process of combining outcomes of individual learning procedures in order to determine the final decision with higher accuracy than any single learning method. Our method is constructed from an ensemble of interacting, learning agents, that acquire and process incoming information using various types, or different versions of machine learning algorithms. The abstract learning space, where all agents are located, is constructed here using a fully connected model that couples all agents with random strength values. The cellular automata network simulates the higher level integration of information acquired from the independent learning trials. The final classification of incoming input data is therefore defined as the stationary state of the meta-learning system using simple majority rule, yet the minority clusters that share opposite classification outcome can be observed in the system. Therefore, the probability of selecting proper class for a given input data, can be estimated even without the prior knowledge of its affiliation. The fuzzy logic can be easily introduced into the system, even if learning agents are build from simple binary classification machine learning algorithms by calculating the percentage of agreeing agents.Comment: 23 page

HIV testing practices among men who have sex with men in Buenos Aires, Argentina

The objective of the study was to explore HIV-testing practices among men who have sex with men (MSM) in Buenos Aires, Argentina, in light of current international health guidelines that recommend frequent HIV testing for MSM who engage in high-risk behavior. Participants, who were recruited using respondent-driven sampling (RDS), were 500 mostly young, nongay-identified MSM of low socioeconomic status, high levels of unemployment, living mainly in the less-affluent areas surrounding Buenos Aires, and lacking health insurance. They provided blood samples for HIV testing and responded to a Computer Assisted Self Interview. Fifty-two percent had never been tested for HIV, and 20% had been tested only once; 17% were found to be HIV infected, of whom almost half were unaware of their status. Main reasons for never having tested previously were: not feeling at risk, fear of finding out results, and not knowing where to get tested. Among those previously tested, men had been tested a median of 2 times with their most recent test having occurred a median of 2.7 years prior to study enrollment. Of those who had not tested positive before entering the study, only 41% returned for their results. HIV testing was infrequent and insufficient for early detection of infection, entry into treatment, and protection of sexual partners. This was particularly the case among nongay-identified MSM. Testing campaigns should aim to help MSM become aware of their risk behavior, decrease fear of testing by explaining available treatment resources and decreasing the stigma associated with HIV, and by publicizing information about free and confidential testing locations. Rapid HIV testing should be made available to eliminate the need for a return visit and make results immediately available to individuals who are tested.Fil: Carballo Diéguez, Alex. Columbia University; Estados UnidosFil: Balán, Iván C.. Columbia University; Estados UnidosFil: Dolezal, Curtis. Columbia University; Estados UnidosFil: Pando, María de los Ángeles. Universidad de Buenos Aires. Facultad de Medicina. Departamento de Microbiología. Centro Nacional de Referencia para el Sida; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas en Retrovirus y Sida. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Biomédicas en Retrovirus y Sida; ArgentinaFil: Marone, Ruben. Nexo Asociación Civil; ArgentinaFil: Barreda, Victoria. Nexo Asociación Civil; ArgentinaFil: Ávila, María Mercedes. Universidad de Buenos Aires. Facultad de Medicina. Departamento de Microbiología. Centro Nacional de Referencia para el Sida; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas en Retrovirus y Sida. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Biomédicas en Retrovirus y Sida; Argentin

Childhood sexual experiences with an older partner among men who have sex with men in Buenos Aires, Argentina

This study sought to describe childhood sexual experiences with older partners (CSEOP) among men who have sex with men (MSM) in Buenos Aires, Argentina. MSM were recruited through respondent driven sampling. They responded to a computer administered self-interview with questions on CSEOP, operationalized as manual, oral, genital, or anal contact prior to age 13 with a partner at least 4 years older. Of the 500 respondents, only 25% identified as gay. Eighteen percent of the respondents reported CSEOP, the majority of whom did not feel they were hurt by the experience and did not consider it to be childhood sexual abuse (CSA). Over two-thirds of MSM who reported CSEOP said that their older partner was a female. Only 4% of those with a female partner felt their experience was CSA compared to 44% of those who had a male partner. Among all men reporting CSEOP, those who felt sexually abused were more likely to have been physically forced or threatened, physically hurt, and emotionally hurt than those who did not feel sexually abused. Having CSEOP, being hurt by the experiences, and perceiving the experiences as sexual abuse were not associated with current HIV sexual risk or substance use behavior. In this sample of MSM in Argentina, a substantial minority reported CSEOP. Those who felt they had been sexually abused were much more likely to have had an older male partner than an older female partner, and were more likely to report having been physically forced and threatened by their older partner.Fil: Dolezal, Curtis. Columbia University; Estados UnidosFil: Carballo Diéguez, A.. Columbia University; Estados UnidosFil: Balán, Iván C.. Columbia University; Estados UnidosFil: Pando, María de los Ángeles. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas en Retrovirus y Sida. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Biomédicas en Retrovirus y Sida; ArgentinaFil: Mabragaña, Marina. Columbia University; Estados UnidosFil: Marone, Ruben. Nexo Asociación Civil; ArgentinaFil: Barreda, Victoria. Nexo Asociación Civil; ArgentinaFil: Ávila, María Mercedes. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas en Retrovirus y Sida. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Biomédicas en Retrovirus y Sida; Argentin

The ASEAN community-based tourism standards: looking beyond certification

This paper reports findings from an opportunity study on the appropriateness of implementing community-based tourism standards (CBTS) certification through the Association of Southeast Asian Nations (ASEAN) criteria, as a way to improve sustainable tourism provision in the region. Framed by critical reflections on community-based tourism (CBT) literature and existing sustainable tourism standards (STS) practices, qualitative research consisting of interviews with six key industry experts provided core insights into a number of CBTS’ implementation challenges. Findings indicate the main hindering factors for the implementation of CBTS to be the lack of adequate governance, limited funding and insufficient community capacity. The study concluded that although at the moment the full implementation of CBTS as a certification programme would be premature, ASEAN-CBTS’ criteria are a useful benchmarking and strategic planning tool for local communities, which would eventually lead to improved CBT benefits, standards and performance in the region. At the same time, this paper argues that aspects including CBT competitiveness and service delivery need to be tackled first to create fruitful grounding for CBT certification

Cell-Type-Specific Cytokinin Distribution within the Arabidopsis Primary Root Apex

Cytokinins (CKs) play a crucial role in many physiological and developmental processes at the levels of individual plant components (cells, tissues, and organs) and by coordinating activities across these parts. High-resolution measurements of intracellular CKs in different plant tissues can therefore provide insights into their metabolism and mode of action. Here, we applied fluorescence-activated cell sorting of green fluorescent protein (GFP)-marked cell types, combined with solid-phase microextraction and an ultra-high-sensitivity mass spectrometry (MS) method for analysis of CK biosynthesis and homeostasis at cellular resolution. This method was validated by series of control experiments, establishing that protoplast isolation and cell sorting procedures did not greatly alter endogenous CK levels. The MS-based method facilitated the quantification of all the well known CK isoprenoid metabolites in four different transgenic Arabidopsis thaliana lines expressing GFP in specific cell populations within the primary root apex. Our results revealed the presence of a CK gradient within the Arabidopsis root tip, with a concentration maximum in the lateral root cap, columella, columella initials, and quiescent center cells. This distribution, when compared with previously published auxin gradients, implies that the well known antagonistic interactions between the two hormone groups are cell type specific

Microwave Components with MEMS Switches

RF MEMS switches with metal-metal contacts are being developed for microwave applications where broadband, high linearity performance is required. These switches provide less than 0.2 dB insertion loss through 40 GHz. This paper describes the integration of these switches into selected microwave components such as reconfigurable antenna elements, tunable filters, switched delay lines, and SPDT switches. Microwave and millimeter wave measured results from these circuits are presented