1,246 research outputs found

    The dual role of media internalization in adolescent sexual behavior

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    Sexualizing media content is prevalent in various media types. Sexualizing media messages and portrayals emphasize unattainable body and appearance ideals as the primary components of sexual desirability. The internalization of these ideals is positively related to self-objectification and sexual body consciousness. In turn, self-objectification and sexual body consciousness affect adolescents’ sexual behavior, albeit in opposing directions. While objectifying self-perceptions are linked to higher levels of sexual behavior, body consciousness during physical intimacy is linked to lower levels of sexual behavior. Based on this knowledge, the present three-wave panel study of 824 Belgian, predominant heterosexual adolescents (Mage = 15.33; SD = 1.45) proposes a dual-pathway model that investigates two different pathways through which the internalization of media ideals may impact adolescents’ sexual behavior. An inhibitory pathway links media internalization to lower levels of sexual behavior through sexual body consciousness, and a supportive pathway links media internalization to higher levels of sexual behavior through self-objectification. Structural equation analyses supported the proposed dual-pathway, showing that the impact of media internalization on adolescents’ sexual behavior proceeds through an inhibitory pathway and a supportive pathway. Regarding the supportive pathway, media internalization (W1) positively predicted sexual behavior (W3), through valuing appearance over competence (W2). Regarding the inhibitory pathway, media internalization (W1) positively predicted body surveillance, which, in turn, positively predicted sexual body consciousness (all W2). Sexual body consciousness (W2) is negatively related to sexual behavior (W3). From a sexual developmental perspective, these findings emphasize the importance of guiding adolescents in interpreting and processing sexualizing media messages

    Using a gamified monitoring app to change adolescents' snack intake : the development of the REWARD app and evaluation design

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    Background: As the snacking pattern of European adolescents is of great concern, effective interventions are necessary. Till now health promotion efforts in children and adolescents have had only limited success in changing adolescents' eating patterns and anthropometrics. Therefore, the present study proposes an innovative approach to influence dietary behaviors in youth based on new insights on effective behavior change strategies and attractive intervention channels to engage adolescents. This article describes the rationale, the development, and evaluation design of the 'Snack Track School' app. The aim of the app is to improve the snacking patterns of Flemish 14- to 16-year olds. Methods: The development of the app was informed by the systematic, stepwise, iterative, and collaborative principles of the Intervention Mapping protocol. A four week mHealth intervention was developed based on the dual-system model with behavioral change strategies targeting both the reflective (i.e., active learning, advance organizers, mere exposure, goal-setting, monitoring, and feedback) and automatic processes (i.e., rewards and positive reinforcement). This intervention will be evaluated via a controlled pre-post design in Flemish schools among 1400 adolescents. Discussion: When this intervention including strategies focused on both the reflective and automatic pathway proves to be effective, it will offer a new scientifically-based vision, guidelines and practical tools for public health and health promotion (i.e., incorporation of learning theories in intervention programs)

    Hydrological and climatological change associated with glacial recession in the Rwenzori Mountains of Uganda

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    The areal extent of tropical icefields in the Rwenzori Mountains of East Africa has reduced steadily over the last century from 7.5 km^{2} 2 in 1906 to <1 km^{2} in 2003. Considerable debate persists regarding the impact of deglaciation on alpine riverflow and changes in climate driving glacial recession in the East African Highlands. Recent field surveys combined with historical observations reveal continued, rapid retreat in the terminal positions of valley glaciers (Speke, Elena). Observed acceleration in the rate of termini retreat since the 1960s is shown to arise, in part, from the morphologies of the glaciers and the beds within which those glaciers reside. Historical data combined with the first measurements of alpine riverflow in the Rwenzori Mountains show that the contribution of meltwater flows from dwindling icefields to alpine riverflow is negligible, contributing <0.5% of the mean annual river discharge recorded at the base of the mountains. Preliminary high-frequency monitoring of air temperature and humidity in the vicinity of icefields on the Rwenzori Mountains indicates that elevated daily maximum air temperatures coincide with episodic reductions in relative humidity and increased meltwater fluxes observed during the dry season. A sustained reduction in humidity to account for observed deglaciation is not evident from records of lowland precipitation, humidity or river discharge. Lakelevel records in East Africa are also inconsistent with a sudden decrease in regional humidity around 1880AD that is proposed to have triggered deglaciation in the East African Highlands. Water levels in the lakes proximate to the icefields of Mount Kenya and Kilimanjaro are rising in the late 19th century when glaciers on these mountains are observed to be in retreat. Lake levels do not, furthermore, indicate that enhanced humidity over the 19th century prior to 1880AD relative to the 20th century. Evidence of warming over the latter half of the 20th century and an earlier onset of deglaciation (~1870AD) from meteorological and palaeolimnological data suggest that the timing and drivers of deglaciation in the Rwenzori Mountains are consistent with the recession of alpine icefields elsewhere in the tropics

    Isolated limb perfusion with actinomycin D and TNF-alpha results in improved tumour response in soft-tissue sarcoma-bearing rats but is accompanied by severe local toxicity

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    Previously we demonstrated that addition of Tumour Necrosis Factor-α to melphalan or doxorubicin in a so-called isolated limb perfusion results in synergistic antitumour responses of sarcomas in both animal models and patients. Yet, 20 to 30% of the treated tumours do not respond. Therefore agents that synergise with tumour necrosis factor alpha must be investigated. Actinomycin D is used in combination with melphalan in isolated limb perfusion in the treatment of patients with melanoma in-transit metastases and is well known to augment tumour cell sensitivity towards tumour necrosis factor alpha in vitro. Both agents are very toxic, which limits their systemic use. Their applicability may therefore be tested in the isolated limb perfusion setting, by which the tumours can be exposed to high concentrations in the absence of systemic exposure. To study the beneficial effect of the combination in vivo, BN-175 soft tissue sarcoma-bearing rats were perfused with various concentrations of actinomycin D and tumour necrosis factor alpha. When used alone the drugs had only little effect on the tumour. Only when actinomycin D and tumour necrosis factor alpha were combined a tumour response was achieved. However, these responses were accompanied by severe, dose limiting, local toxicity such as destruction of the muscle tissue and massive oedema. Our results show that isolated limb perfusion with actinomycin D in combination with tumour necrosis factor alpha leads to a synergistic anti-tumour response but also to idiosyncratic locoregional toxicity to the normal tissues. Actinomycin D, in combination with tumour necrosis factor alpha, should not be explored in the clinical setting because of this. The standard approach in the clinic remains isolated limb perfusion with tumour necrosis factor alpha in combination with melphalan

    Independent Set Reconfiguration in Cographs

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    We study the following independent set reconfiguration problem, called TAR-Reachability: given two independent sets II and JJ of a graph GG, both of size at least kk, is it possible to transform II into JJ by adding and removing vertices one-by-one, while maintaining an independent set of size at least kk throughout? This problem is known to be PSPACE-hard in general. For the case that GG is a cograph (i.e. P4P_4-free graph) on nn vertices, we show that it can be solved in time O(n2)O(n^2), and that the length of a shortest reconfiguration sequence from II to JJ is bounded by 4n2k4n-2k, if such a sequence exists. More generally, we show that if XX is a graph class for which (i) TAR-Reachability can be solved efficiently, (ii) maximum independent sets can be computed efficiently, and which satisfies a certain additional property, then the problem can be solved efficiently for any graph that can be obtained from a collection of graphs in XX using disjoint union and complete join operations. Chordal graphs are given as an example of such a class XX

    Comparison of LFP-Based and Spike-Based Spectro-Temporal Receptive Fields and Cross-Correlation in Cat Primary Auditory Cortex

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    Multi-electrode array recordings of spike and local field potential (LFP) activity were made from primary auditory cortex of 12 normal hearing, ketamine-anesthetized cats. We evaluated 259 spectro-temporal receptive fields (STRFs) and 492 frequency-tuning curves (FTCs) based on LFPs and spikes simultaneously recorded on the same electrode. We compared their characteristic frequency (CF) gradients and their cross-correlation distances. The CF gradient for spike-based FTCs was about twice that for 2–40 Hz-filtered LFP-based FTCs, indicating greatly reduced frequency selectivity for LFPs. We also present comparisons for LFPs band-pass filtered between 4–8 Hz, 8–16 Hz and 16–40 Hz, with spike-based STRFs, on the basis of their marginal frequency distributions. We find on average a significantly larger correlation between the spike based marginal frequency distributions and those based on the 16–40 Hz filtered LFP, compared to those based on the 4–8 Hz, 8–16 Hz and 2–40 Hz filtered LFP. This suggests greater frequency specificity for the 16–40 Hz LFPs compared to those of lower frequency content. For spontaneous LFP and spike activity we evaluated 1373 pair correlations for pairs with >200 spikes in 900 s per electrode. Peak correlation-coefficient space constants were similar for the 2–40 Hz filtered LFP (5.5 mm) and the 16–40 Hz LFP (7.4 mm), whereas for spike-pair correlations it was about half that, at 3.2 mm. Comparing spike-pairs with 2–40 Hz (and 16–40 Hz) LFP-pair correlations showed that about 16% (9%) of the variance in the spike-pair correlations could be explained from LFP-pair correlations recorded on the same electrodes within the same electrode array. This larger correlation distance combined with the reduced CF gradient and much broader frequency selectivity suggests that LFPs are not a substitute for spike activity in primary auditory cortex

    Cumulative incidence and timing of subsequent cutaneous squamous cell carcinomas stratified for patients with organ transplantation and hematologic malignancies:A nationwide cohort study

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    Background: There is lack of nationwide data on the cumulative incidence and timing of subsequent cutaneous squamous cell carcinomas (cSCCs) among patients with a first cSCC. Objective: To investigate the cumulative incidence and timing of subsequent cSCCs. Methods: Patients with a first cSCC in 2007/2008 from the Netherlands Cancer Registry were linked to the Netherlands Pathology Registry for subsequent cSCCs and the Netherlands Organ Transplant Registry. Cumulative incidence function curves were calculated for subsequent cSCCs and stratified for immune status. Results: Among the 12,345 patients, second to sixth cSCC occurred in 4325, 2010, 1138, 739, and 501 patients, with median time intervals of 1.4, 1.2, 0.9, 0.6, and 0.5 years after the previous cSCC, respectively. The cumulative incidence of a subsequent cSCC at 5 years increased from 28% to 67% for the second to sixth cSCC. For solid organ transplant recipients, the cumulative incidences increased from 74% to 92% and from 41% to 64% for patients with hematologic malignancy. Limitations: Only histopathologically confirmed cSCCs were included. Conclusion: The risk of a subsequent cSCC steeply rises with the number of prior cSCCs and immune status, while the time interval decreases. This can support more informed decisions about follow-up management.</p
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