922 research outputs found

    HEMOPOIETIC COLONY STUDIES : V. EFFECT OF HEMOPOIETIC ORGAN STROMA ON DIFFERENTIATION OF PLURIPOTENT STEM CELLS

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    In heavily irradiated mice, bone marrow regeneration of either endogenous or exogenous origin was shown to occur in discrete foci comparable to the more intensively studied spleen colonies. The number of endogenous bone marrow colonies was inversely related to dose of whole body X-irradiation. Endogenous marrow colonies were found after higher doses of irradiation than were endogenous spleen colonies. Most of them were granulocytic in nature. Exogenous bone marrow colonies in lethally irradiated mice injected with bone marrow cells were proportional in number to the dose of cells injected, appeared at a time comparable to spleen colonies like which, at 7 or 8 days, they were of single differentiated cell line, either granuloid or erythroid or megakaryocytic, with a small percentage of "mixed" colonies. Whereas erythroid colonies outnumber granuloid colonies in spleen, either in situ or subcutaneously transplanted (E:G colony ratio of about 3.5), granuloid colonies outnumber erythroid in bone marrow (E:G colony ratio of about 0.7). The characteristic E:G colony ratios of spleen and marrow appear more likely to be the result of a hemopoietic organ stromal influence on pluripotent colony forming units (CFU's) than of selective lodgment of committed (unipotent) granuloid and erythroid CFU's in bone marrow and spleen, respectively, as indicated by the following. Bone marrow stem cells (CFU) which had reseeded the marrow cavity of irradiated primary recipients 18–24 hr earlier, were reharvested and retransplanted intravenously into irradiated secondary hosts. The E:G colony ratio of the colonies formed in the spleen of the secondary hosts was typical of primary spleen colonies (2.8), that of the colonies formed in the marrow cavity was typical of bone marrow colonies (0.6). Pieces of marrow stroma containing reseeded CPU's from the contralateral femur of these same primary recipients were implanted by trocar directly into the spleens of other irradiated secondary recipients. Those CPU's that developed in the intrasplenic-implanted marrow stroma yielded an. E:G colony ratio of 0.1. Those that migrated into the contiguous and remote portions of the spleen gave E:G colony ratios of 2.9 and 2.4, respectively. Irradiated marrow stroma and normal spleen CPU's (a 1 mm cube of spleen) were loaded into the same trocar and implanted directly into the spleens of irradiated mice. The spleen CFU's that migrated into the implanted marrow stroma yielded five granuloid and two mixed colonies. The larger number that developed in the host spleen yielded an E:G colony ratio of 2.9 or higher. Of those 19 mixed colonies that bridged the junction of spleen and implanted marrow stroma in each of the above two experiments, in every case, the erythroid portion of the colony was in the splenic stroma, the granuloid portion was in the marrow stroma

    Obtendo segurança em uma rede a partir da utilização de intrusion

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    Este trabalho tem por objetivo realizar um estudo sobre algumas soluções em segurança de redes de computadores, culminando no Intrusion Prevention System (IPS). Esse sistema possui as mesmas características de um Intrusion Detection System (IDS), porém seu maior diferencial é que ele trabalha de modo ativo na rede, ou seja, ele não fica apenas coletando tráfego, mas interagindo com a rede. A proposta desses sistemas de prevenção de intrusão surgiu recentemente devido á habilidade de coletar e analisar tráfego TCP/IP em tempo real, a fim de, sempre que necessário, executar medidas próativas ou, pelo menos, reativas.This work has for aim to carry through a study on some solutions in security of computer networks, with its final results in the Intrusion Prevention System (IPS). This system has the same characteristics of a Intrusion Detection System (IDS), however the biggest difference between them is that it works in active way in the net, or either, does not only collect traffic, but it interacts with the net. The proposal of these systems of prevention of intrusion recently appeared due to ability to collect and to analyze traffic TCP/IP in real time, so that, whenever it’s necessary, it performs pro-active or, at least, reactive actions.Eje: Arquitectura, Redes y Sistemas Operativos (ARSO)Red de Universidades con Carreras en Informática (RedUNCI

    Learning activation functions from data using cubic spline interpolation

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    Neural networks require a careful design in order to perform properly on a given task. In particular, selecting a good activation function (possibly in a data-dependent fashion) is a crucial step, which remains an open problem in the research community. Despite a large amount of investigations, most current implementations simply select one fixed function from a small set of candidates, which is not adapted during training, and is shared among all neurons throughout the different layers. However, neither two of these assumptions can be supposed optimal in practice. In this paper, we present a principled way to have data-dependent adaptation of the activation functions, which is performed independently for each neuron. This is achieved by leveraging over past and present advances on cubic spline interpolation, allowing for local adaptation of the functions around their regions of use. The resulting algorithm is relatively cheap to implement, and overfitting is counterbalanced by the inclusion of a novel damping criterion, which penalizes unwanted oscillations from a predefined shape. Experimental results validate the proposal over two well-known benchmarks.Comment: Submitted to the 27th Italian Workshop on Neural Networks (WIRN 2017

    Negative consequences of conflict-related sexual violence on survivors: a systematic review of qualitative evidence

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    BackgroundConflicts exacerbate dynamics of power and inequalities through violence normalization, which acts as a facilitator for conflict-related sexual violence. Literature addressing its negative outcomes on survivors is scant. The aim of this systematic review was to analyze the qualitative evidence reported in scientific literature and focusing on the negative consequences of conflict-related sexual violence on victims' physical, psychological, and social dimensions of health in a gender-inclusive and disaggregated form.MethodsA literature search was conducted on January 13, 2023 on Pubmed, Scopus, and PsychArticles. The search strings combined two blocks of terms related to sexual violence and conflict. A time filter was applied, limiting the search to studies published in the last ten years. Information regarding the main characteristics and design of the study, survivors and their experience, and about conflict-related sexual violence was collected. The negative consequences of conflict-related sexual violence on the physical, psychological, and social dimension of victims were extracted according to the Biopsychosocial model of health. The review followed the Joanna Briggs Institute methodology for systematic reviews and relied on the Preferred Reporting Items for Systematic reviews and Meta-Analyses.ResultsAfter full text review, 23 articles met the inclusion criteria, with 18 of them reporting negative repercussions on physical health, all of them highlighting adverse psychological outcomes, and 21 disclosing unfavorable social consequences. The negative outcomes described in multiple studies were sexual and reproductive health issues, the most mentioned being pregnancy, manifestations of symptoms attributable to post-traumatic stress disorder, and stigma. A number of barriers to access to care were presented as emerging findings.ConclusionsThis review provided an analysis of the negative consequences of conflict-related sexual violence on survivors, thus highlighting the importance of qualitative evidence in understanding these outcomes and addressing barriers to access to care. Conflict-related sexual violence is a sexual and reproductive health issue. Sexuality education is needed at individual, community, and provider level, challenging gender norms and roles and encompassing gender-based violence. Gender-inclusive protocols and services need to be implemented to address the specific needs of all victims. Governments should advocate for SRHRs and translate health policies into services targeting survivors of CRSV

    Protocolo de amostragem para determinação de atributos de raízes de plantas de campo nativo.

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