The Avatar-Self Relationship: Enacting Presence in Second Life

Avatars are technological artifacts that provide communicators a body in virtual spaces. It is through this affordance of embodiment that people, places and things are made concrete, tangible, and present. Presence consists of two interrelated phenomena: (i) telepresence: the sense of being there, and (ii) social presence: the sense of being together with others. In the context of virtual worlds, telepresence or the degree of immersion and engagement in the computer-mediated space is achieved through communicators’ interaction with their avatar, and social presence through their interaction with others as an avatar. Building on this typology, we develop a multidimensional conceptual framework of the avatar-self relationship, that is, the interaction between a communicator and his/her virtual (re)presentation. Relying on data collected via photo-diary interviews from residents of Second Life, a virtual world, we then identify and empirically describe various enactments of the avatar-self relationship. Our results highlight that Second Life residents enacted multiple avatar-self relationships and cycled through them in quick succession, suggesting that these avatar-self relationships might be shaped and activated strategically in order to achieve the desired educational, commercial or therapeutic outcomes

Managerial performance evaluation and organizational form

We study the relative efficiency of centralized versus decentralized organizational forms given optimized managerial performance evaluation within an incomplete contracting framework with risk-averse agents under moral hazard. Decentralization and performance evaluation are complementary control choices and the efficiency of an organizational form depends on the design of performance evaluation. Divisions can make relationship-specific investments that not only improve firm performance, but also increase compensation risk. We find that pure divisional performance evaluation is optimal under centralization, whereas under decentralization, optimal compensation contracts include a combination of divisional and firm-wide performance evaluation. When comparing both organizational forms, we find that the optimal form depends on managers’ degree of risk-aversion and the uncertainty of the business environment. Contrary to previous literature, we find that centralization dominates in many situations, particularly at high degrees of risk-aversion and high uncertainty

Real versus accounting earnings management: the effect of performance measure timing constraints

We study the influence of stricter rules for determining performance measures for compensation contracts on managers' choice between real and accounting earnings management. Constraints, like accounting regulation or corporate governance, limit managers' influence on performance measures. We find that tighter constraints intensify real earnings manipulation, because they reduce incentives for managers to supply effort on investment activities. In turn, discretion allows managers to anticipate future benefits of investment and reduces real earnings management. The results hold when contracts include forward-looking information and suggest that constraints on managers' influence on performance measures drive the choice between accounting and real earnings management

Lessons from Silage Adoption Studies in Honduras

Silage adoption has so far been low in the tropics, particularly under smallholder conditions. Innovation and adoption processes of silage technologies were promoted in drought-constrained areas of Honduras using a flexible, site-specific and participatory research and extension approach. A total of about 250 farmers participated in training workshops and field days conducted in 13 locations. Smallholders successfully ensiled maize, sorghum and/or Pennisetum spp. mainly in heap and earth siloswhereas little bag silage (LBS) adoption was low. LBS proved useful as a demonstration, experimentation and learning tool. A ‘silage boom’ occurred in five locations where favourable adoption conditions included the presence of demonstration farms and involvement of key innovators, lack of alternative dry season feeds, perceived benefits of silage feeding, a favourable milk market and both extension continuity and intensity. The lack of chopping equipment was the main reason for non-adoption by low-income smallholders. The study showed that when targeting production systems needs and farmer demands, silage promotion can lead to significant adoption, including at smallholder level, in the tropics. This experience could contribute to increase the effectiveness and sustainability of silage extension in similar situations elsewhere

Fetal calf serum heat inactivation and lipopolysaccharide contamination influence the human T lymphoblast proteome and phosphoproteome

<p>Abstract</p> <p>Background</p> <p>The effects of fetal calf serum (FCS) heat inactivation and bacterial lipopolysaccharide (LPS) contamination on cell physiology have been studied, but their effect on the proteome of cultured cells has yet to be described. This study was undertaken to investigate the effects of heat inactivation of FCS and LPS contamination on the human T lymphoblast proteome. Human T lymphoblastic leukaemia (CCRF-CEM) cells were grown in FCS, either non-heated, or heat inactivated, having low (< 1 EU/mL) or regular (< 30 EU/mL) LPS concentrations. Protein lysates were resolved by 2-DE followed by phospho-specific and silver nitrate staining. Differentially regulated spots were identified by nano LC ESI Q-TOF MS/MS analysis.</p> <p>Results</p> <p>A total of four proteins (EIF3M, PRS7, PSB4, and SNAPA) were up-regulated when CCRF-CEM cells were grown in media supplemented with heat inactivated FCS (HE) as compared to cells grown in media with non-heated FCS (NHE). Six proteins (TCPD, ACTA, NACA, TCTP, ACTB, and ICLN) displayed a differential phosphorylation pattern between the NHE and HE groups. Compared to the low concentration LPS group, regular levels of LPS resulted in the up-regulation of three proteins (SYBF, QCR1, and SUCB1).</p> <p>Conclusion</p> <p>The present study provides new information regarding the effect of FCS heat inactivation and change in FCS-LPS concentration on cellular protein expression, and post-translational modification in human T lymphoblasts. Both heat inactivation and LPS contamination of FCS were shown to modulate the expression and phosphorylation of proteins involved in basic cellular functions, such as protein synthesis, cytoskeleton stability, oxidative stress regulation and apoptosis. Hence, the study emphasizes the need to consider both heat inactivation and LPS contamination of FCS as factors that can influence the T lymphoblast proteome.</p

Circadian Plasticity in Photoreceptor Cells Controls Visual Coding Efficiency in Drosophila melanogaster

In the fly Drosophila melanogaster, neuronal plasticity of synaptic terminals in the first optic neuropil, or lamina, depends on early visual experience within a critical period after eclosion [1]. The current study revealed two additional and parallel mechanisms involved in this type of synaptic terminal plasticity. First, an endogenous circadian rhythm causes daily oscillations in the volume of photoreceptor cell terminals. Second, daily visual experience precisely modulates the circadian time course and amplitude of the volume oscillations that the photoreceptor-cell terminals undergo. Both mechanisms are separable in their molecular basis. We suggest that the described neuronal plasticity in Drosophila ensures continuous optimal performance of the visual system over the course of a 24 h-day. Moreover, the sensory system of Drosophila cannot only account for predictable, but also for acute, environmental changes. The volumetric changes in the synaptic terminals of photoreceptor cells are accompanied by circadian and light-induced changes of presynaptic ribbons as well as extensions of epithelial glial cells into the photoreceptor terminals, suggesting that the architecture of the lamina is altered by both visual exposure and the circadian clock. Clock-mutant analysis and the rescue of PER protein rhythmicity exclusively in all R1-6 cells revealed that photoreceptor-cell plasticity is autonomous and sufficient to control visual behavior. The strength of a visually guided behavior, the optomotor turning response, co-varies with synaptic-terminal volume oscillations of photoreceptor cells when elicited at low light levels. Our results show that behaviorally relevant adaptive processing of visual information is performed, in part, at the level of visual input level

Letters to the Editor: Correspondence re R. Lapointe et al., CD40-stimulated B Lymphocytes Pulsed with Tumor Antigens Are Effective Antigen-presenting Cells That Can Generate Specific T Cells. Cancer Res 2003;63:2836–43.

La réplique provient de Réjean Lapointe, Jacques Thibodeau et Patrick Hwu; Réjean Lapointe et Jacques Thibodeau sont affiliés à la faculté de médecine de l'Université de Montréa

OPM magnetorelaxometry in the presence of a DC bias field

Spatial quantitative information about magnetic nanoparticle (MNP) distributions is a prerequisite for biomedical applications like magnetic hyperthermia and magnetic drug targeting. This information can be gathered by means of magnetorelaxometry (MRX) imaging, where the relaxation of previously aligned MNP’s magnetic moments is measured by sensitive magnetometers and an inverse problem is solved. To remove or minimize the magnetic shielding in which MRX imaging is carried out today, the knowledge of the influence of background magnetic fields on the MNP’s relaxation is a prerequisite. We show MRX measurements using an intensity-modulated optically pumped magnetometer (OPM) in background magnetic fields of up to 100μT. We show that the relaxation parameters alter or may be intentionally altered significantly by applying static fields parallel or antiparallel to the MNP’s alignment direction. Further, not only the relaxation process of the MNP’s magnetic moments could be measured with OPM, but also their alignment due to the MRX excitation field. © 2020, The Author(s)