619 research outputs found
Is true friendship possible on Facebook? A study from the psychological perspective of Laín Entralgo
The present work aims to analyse the meaning of the concept of friendship through the study of the work of the doctor and philosopher Pedro Laín Entralgo. The initial hypothesis of the study is that the concept of friendship has been used instrumentally by social media networks, and that these do not offer the conditions necessary to fully experience true friendship. To verify this, we focused on the study of the psychological dimensions of friendship proposed by the author, identifying a series of variables and conducting an analysis by means of a survey of university students who are active users of the platform. With these results the descriptive statistics were extracted and a nonparametric analysis was performed of the variables to determine if Facebook does in fact offer the conditions necessary for to experience true friendship in its psychological dimensions. As the results show, to experience true friendship on social networks is difficult, given that the nature of the interactions between users of the platform are not appropriate for this experience. In calling this different type of relationship friendship Facebook benefits from an attractive hook which leads users to generate contacts as a form of currency which benefits the business model of the social media platform. The concept of true friendship is altered, deformed and displaced in favour of other types of relationships.El presente trabajo tiene como objetivo analizar el significado del concepto de amistad a través del estudio de la obra del médico y filósofo Pedro Laín Entralgo. La hipótesis inicial del estudio es que el concepto de amistad ha sido utilizado instrumentalmente por las redes sociales, y que estas no ofrecen las condiciones necesarias para la vivencia plena de la verdadera amistad. Para comprobarlo, nos centramos en el estudio de las dimensiones psicológicas de la amistad que propone el autor, identificando una serie de variables y realizando un análisis mediante una encuesta a estudiantes universitarios que son usuarios activos de la plataforma. Con estos resultados se extrajo la estadística descriptiva y se realizó un análisis no paramétrico de las variables para determinar si Facebook efectivamente ofrece las condiciones necesarias para la vivencia de la verdadera amistad en sus dimensiones psicológicas. Como muestran los resultados, la experiencia de la verdadera amistad en las redes sociales es difícil, dado que la naturaleza de las interacciones entre los usuarios de la plataforma no son las adecuadas para esta experiencia. Al llamar amistad a este tipo diferente de relación, Facebook se beneficia de un atractivo gancho que lleva a los usuarios a generar contactos como moneda de cambio que favorece el modelo de negocio de la plataforma de redes sociales. El concepto de verdadera amistad se altera, deforma y desplaza a favor de otro tipo de relaciones
Failure regime in (1+1) dimensions in fibrous materials
In this paper, we introduce a model for fracture in fibrous materials that
takes into account the rupture height of the fibers, in contrast with previous
models. Thus, we obtain the profile of the fracture and calculate its
roughness, defined as the variance around the mean height. We investigate the
relationship between the fracture roughness and the fracture toughness.Comment: 4 pages, 4 figures.eps, Revte
Majority versus minority dynamics: Phase transition in an interacting two-state spin system
We introduce a simple model of opinion dynamics in which binary-state agents
evolve due to the influence of agents in a local neighborhood. In a single
update step, a fixed-size group is defined and all agents in the group adopt
the state of the local majority with probability p or that of the local
minority with probability 1-p. For group size G=3, there is a phase transition
at p_c=2/3 in all spatial dimensions. For p>p_c, the global majority quickly
predominates, while for p<p_c, the system is driven to a mixed state in which
the densities of agents in each state are equal. For p=p_c, the average
magnetization (the difference in the density of agents in the two states) is
conserved and the system obeys classical voter model dynamics. In one dimension
and within a Kirkwood decoupling scheme, the final magnetization in a
finite-length system has a non-trivial dependence on the initial magnetization
for all p.ne.p_c, in agreement with numerical results. At p_c, the exact 2-spin
correlation functions decay algebraically toward the value 1 and the system
coarsens as in the classical voter model.Comment: 11 pages, 3 figures, revtex4 2-column format; minor revisions for
publication in PR
Euclidean Approach to the Entropy for a Scalar Field in Rindler-like Space-Times
The off-shell entropy for a massless scalar field in a D-dimensional
Rindler-like space-time is investigated within the conical Euclidean approach
in the manifold C_\be\times\M^N, C_\be being the 2-dimensional cone, making
use of the zeta-function regularisation. Due to the presence of conical
singularities, it is shown that the relation between the zeta-function and the
heat kernel is non trivial and, as first pointed out by Cheeger, requires a
separation between small and large eigenvalues of the Laplace operator. As a
consequence, in the massless case, the (naive) non existence of the Mellin
transform is by-passed by the Cheeger's analytical continuation of the
zeta-function on manifold with conical singularities. Furthermore, the
continuous spectrum leads to the introduction of smeared traces. In general, it
is pointed out that the presence of the divergences may depend on the smearing
function and they arise in removing the smearing cutoff. With a simple choice
of the smearing function, horizon divergences in the thermodynamical quantities
are recovered and these are similar to the divergences found by means of
off-shell methods like the brick wall model, the optical conformal
transformation techniques or the canonical path integral method.Comment: 17 pages, LaTex. A sign error corrected and few comments adde
Population overlap and habitat segregation in wintering Black-tailed Godwits Limosa limosa
Distinct breeding populations of migratory species may overlap both spatially and temporally, but differ in patterns of habitat use. This has important implications for population monitoring and conservation. To quantify the extent to which two distinct breeding populations of a migratory shorebird, the Black-tailed Godwit Limosa limosa, overlap spatially, temporally and in their use of different habitats during winter. We use mid-winter counts between 1990 and 2001 to identify the most important sites in Iberia for Black-tailed Godwits. Monthly surveys of estuarine mudflats and rice-fields at one major site, the Tejo estuary in Portugal in 2005-2007, together with detailed tracking of colour-ringed individuals, are used to explore patterns of habitat use and segregation of the Icelandic subspecies L. l. islandica and the nominate continental subspecies L. l. limosa. In the period 1990-2001, over 66 000 Black-tailed Godwits were counted on average in Iberia during mid-winter (January), of which 80% occurred at just four sites: Tejo and Sado lower basins in Portugal, and Coto Dontildeana and Ebro Delta in Spain. Icelandic Black-tailed Godwits are present throughout the winter and forage primarily in estuarine habitats. Continental Black-tailed Godwits are present from December to March and primarily use rice-fields. Iberia supports about 30% of the Icelandic population in winter and most of the continental population during spring passage. While the Icelandic population is currently increasing, the continental population is declining rapidly. Although the estuarine habitats used by Icelandic godwits are largely protected as Natura 2000 sites, the habitat segregation means that conservation actions for the decreasing numbers of continental godwits should focus on protection of rice-fields and re-establishment of freshwater wetlands
The fraction of cancer attributable to ways of life, infections, occupation, and environmental agents in Brazil in 2020
Many human cancers develop as a result of exposure to risk factors related to the environment and ways of life. The aim of this study was to estimate attributable fractions of 25 types of cancers resulting from exposure to modifiable risk factors in Brazil. The prevalence of exposure to selected risk factors among adults was obtained from population-based surveys conducted from 2000 to 2008. Risk estimates were based on data drawn from metaanalyses or large, high quality studies. Population-attributable fractions (PAF) for a combination of risk factors, as well as the number of preventable deaths and cancer cases, were calculated for 2020. The known preventable risk factors studied will account for 34% of cancer cases among men and 35% among women in 2020, and for 46% and 39% deaths, respectively. The highest attributable fractions were estimated for tobacco smoking, infections, low consumption of fruits and vegetables, excess weight, reproductive factors, and physical inactivity. This is the first study to systematically estimate the fraction of cancer attributable to potentially modifiable risk factors in Brazil. Strategies for primary prevention of tobacco smoking and control of infection and the promotion of a healthy diet and physical activity should be the main priorities in policies for cancer prevention in the country. \ua9 2016 Azevedo e Silva et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited
Intra-Host Evolution Analyses in an Immunosuppressed Patient Supports SARS-CoV-2 Viral Reservoir Hypothesis.
Throughout the SARS-CoV-2 pandemic, several variants of concern (VOCs) have been identified, many of which share recurrent mutations in the spike glycoprotein's receptor-binding domain (RBD). This region coincides with known epitopes and can therefore have an impact on immune escape. Protracted infections in immunosuppressed patients have been hypothesized to lead to an enrichment of such mutations and therefore drive evolution towards VOCs. Here, we present the case of an immunosuppressed patient that developed distinct populations with immune escape mutations throughout the course of their infection. Notably, by investigating the co-occurrence of substitutions on individual sequencing reads in the RBD, we found quasispecies harboring mutations that confer resistance to known monoclonal antibodies (mAbs) such as S:E484K and S:E484A. These mutations were acquired without the patient being treated with mAbs nor convalescent sera and without them developing a detectable immune response to the virus. We also provide additional evidence for a viral reservoir based on intra-host phylogenetics, which led to a viral substrain that evolved elsewhere in the patient's body, colonizing their upper respiratory tract (URT). The presence of SARS-CoV-2 viral reservoirs can shed light on protracted infections interspersed with periods where the virus is undetectable, and potential explanations for long-COVID cases
Research priorities for negative emissions
Carbon dioxide removal from the atmosphere (CDR)—also known as ‘negative emissions’—features
prominently in most 2 °Cscenarios and has been under increased scrutiny by scientists, citizens, and
policymakers. Critics argue that ‘negative emission technologies’ (NETs) are insufficiently mature to
rely on them for climate stabilization. Some even argue that 2 °Cis no longer feasible or might have
unacceptable social and environmental costs. Nonetheless, the Paris Agreement endorsed an
aspirational goal of limiting global warming to even lower levels, arguing that climate impacts—
especially for vulnerable nations such as small island states—will be unacceptably severe in a 2 °C
world. While there are few pathways to 2 °Cthat do not rely on negative emissions, 1.5 °Cscenarios
are barely conceivable without them. Building on previous assessments of NETs, we identify some
urgent research needs to provide a more complete picture for reaching ambitious climate targets, and
the role that NETs can play in reaching them
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