Thermal history modeling of the H chondrite parent body

The cooling histories of individual meteorites can be empirically reconstructed by using ages from different radioisotopic chronometers with distinct closure temperatures. For a group of meteorites derived from a single parent body such data permit the reconstruction of the cooling history and properties of that body. Particularly suited are H chondrites because precise radiometric ages over a wide range of closure temperatures are available. A thermal evolution model for the H chondrite parent body is constructed by using all H chondrites for which at least three different radiometric ages are available. Several key parameters determining the thermal evolution of the H chondrite parent body and the unknown burial depths of the H chondrites are varied until an optimal fit is obtained. The fit is performed by an 'evolution algorithm'. Empirical data for eight samples are used for which radiometric ages are available for at least three different closure temperatures. A set of parameters for the H chondrite parent body is found that yields excellent agreement (within error bounds) between the thermal evolution model and empirical data of six of the examined eight chondrites. The new thermal model constrains the radius and formation time of the H chondrite parent body (possibly (6) Hebe), the initial burial depths of the individual H chondrites, the average surface temperature of the body, the average initial porosity of the material the body accreted from, and the initial 60Fe content of the H chondrite parent body.Comment: 16 pages, 7 figure

Deltagande Forskning – Lärdomar, resultat och erfarenheter från Växthusgruppens arbete 1999–2000

Centrum för uthålligt lantbruk (CUL) vid SLU har initierat ett pionjärarbete att få igång deltagande forskning inom lantbrukssektorn i Sverige. I denna rapport beskrivs den läro- och förändringsprocess, de framgångar och svårigheter, som en av de grupper som ingår i CUL:s satsning genomgått och mött under sitt arbete med deltagande forskning. De resultat gruppens försök och praktiska arbete lett fram till presenteras också. Rapporten är skriven av gruppens facilitator (Karin Eksvärd) efter att ha samtalat med gruppmedlemmarna enskilt och tillsammans om deltagarnas åsikter kring gruppens arbete och arbetsformer. Några av gruppdeltagarnas åsikter och uttalanden finns inlagda som citat i rapporten. Deltagarna har även haft möjlighet att kommentera rapporten under dess framtagande. Gruppens arbete har möjliggjorts genom att rådgivarna har arrangerat gruppens möten som kurser inom miljöstödsprogrammet. Det har varit ett givande och lärorikt arbete som fortsätter att öka vårt kunnande om ekologisk tomatodling, oss själva som grupp och sättet att arbeta. Vi hoppas att denna rapport skall inspirera fler lantbrukare, rådgivare och forskare att i högre grad samverka med varandra och att på detta sätt vidareutveckla svenskt lantbruk

Using olfactory media cues in e-learning – perspectives from an empirical investigation

People interact with computers using their senses. Currently, in a digital context, traditional digital media like videos and images used to convey information to users, and these media can be used as a source of information. However, relatively few studies have been conducted on olfactory media as a source of information in a digital context. In this paper, we report on a study that examined the possibility of using olfactory media as a source of information and whether its usage as informational cues enhances learning performance and user Quality of Experience (QoE). To this end, an olfactory-enhanced quiz (web-based) was developed about four countries. The quiz contained different types of questions employing four types of digital media in their contents: text, image, audio and olfactory media. Four scents were used that were considered to be related to the respective countries. Sixty-four participants were invited to our experiment to evaluate this application. Our results revealed that usage of olfactory media synchronised with traditional digital media had a significant impact on learner performance compared to the case when no olfactory media was employed. In respect of user QoE, it was found that olfactory media influenced users positively; moreover, they were passionate about engaging with enhanced olfactory applications in the future

Computer-based technology and student engagement: a critical review of the literature

Computer-based technology has infiltrated many aspects of life and industry, yet there is little understanding of how it can be used to promote student engagement, a concept receiving strong attention in higher education due to its association with a number of positive academic outcomes. The purpose of this article is to present a critical review of the literature from the past 5 years related to how web-conferencing software, blogs, wikis, social networking sites (Facebook and Twitter), and digital games influence student engagement. We prefaced the findings with a substantive overview of student engagement definitions and indicators, which revealed three types of engagement (behavioral, emotional, and cognitive) that informed how we classified articles. Our findings suggest that digital games provide the most far-reaching influence across different types of student engagement, followed by web-conferencing and Facebook. Findings regarding wikis, blogs, and Twitter are less conclusive and significantly limited in number of studies conducted within the past 5 years. Overall, the findings provide preliminary support that computer-based technology influences student engagement, however, additional research is needed to confirm and build on these findings. We conclude the article by providing a list of recommendations for practice, with the intent of increasing understanding of how computer-based technology may be purposefully implemented to achieve the greatest gains in student engagement. © 2017, The Author(s)

Accuracy in detecting major depressive episodes in older adults using the Swedish versions of the GDS-15 and PHQ-9

Objectives: The purpose of this study was to evaluate the diagnostic accuracy at different cut-off values for the Swedish versions of the 15-item Geriatric Depression Scale (GDS-15) and Patient Health Questionnaire (PHQ-9) compared with a structured clinical psychiatric interview in older adults. Methods: Community-dwelling participants (N = 113) aged 65 years or older completed the Swedish versions of the GDS-15 and PHQ-9 and were then interviewed using the Mini International Neuropsychiatric Interview (MINI) to establish the presence or absence of current major depressive episodes (MDEs). Areas under the curve (AUC) were calculated for each scale, as well as the sensitivity, specificity, and Youden's index for different cut-off values. Results: Seventeen participants met the criteria for MDEs. The AUC was 0.97 for the GDS-15 and 0.95 for the PHQ-9. A cut-off of >= 6 on the GDS-15 yielded a sensitivity of 94%, a specificity of 88%, and a Youden's index of 0.82. A cut-off of >= 5 on the PHQ-9 yielded a sensitivity of 100%, a specificity of 81%, and a Youden's index of 0.81. The proposed cut-off of >= 10 on the PHQ-9 produced excellent specificity of 95% but a lower sensitivity of 71%. Conclusions: This study indicates that the Swedish versions of the GDS-15 and PHQ-9 have comparable accuracy as screening instruments for older adults with MDEs. However, the proposed cut-off of 10 on the PHQ-9 might be too high when applied to older individuals in Sweden, and further investigations in larger samples in different healthcare settings are warranted

Étude des traces de fission fossiles dans le mica

Les traces produites par les fragments de fission de l'uranium dans les micas peuvent être étudiées en microscopie optique, après une attaque fluorhydrique. Le rapport entre les densités de traces fossiles et de traces nouvelles induites par irradiation neutronique devrait permettre de calculer l'âge du minéral. Sur onze micas étudiés, un seul échantillon fournit un âge recoupant l'âge réel de 5,2.10⁸ ans ; les dix autres micas donnent des âges beaucoup trop récents, les erreurs étant d'autant plus fortes que les minéraux sont plus anciens. Deux causes d'erreur peuvent expliquer les divergences dans les résultats : 1) un enrichissement en uranium postérieur à la cristallisation des minéraux, 2) une restauration par recuit des dommages produits dans la trace des fragments de fission.Maurette Michel, Pellas Paul, Walker Robert M. Étude des traces de fission fossiles dans le mica. In: Bulletin de la Société française de Minéralogie et de Cristallographie, volume 87, 1, 1964. pp. 6-17

Chronic treatment with cannabidiolic acid (CBDA) reduces thermal pain sensitivity in male mice and rescues the hyperalgesia in a mouse model of rett syndrome

Rett syndrome (RTT) is a rare neurologic disorder, characterized by severe behavioural and physiological symptoms. RTT is caused by mutations in the MECP2 gene in about 95% of cases and to date no cure is available. Recent evidence suggests that non-euphoric phytocannabinoids (pCBs) extracted from Cannabis sativa may represent innovative therapeutic molecules for RTT, with the cannabinoid cannabidivarin having beneficial effects on behavioural and brain molecular alterations in RTT mouse models. The present study evaluated the potential therapeutic efficacy for RTT of cannabidiolic acid (CBDA; 0.2, 2, 20 mg/kg through intraperitoneal injections for 14 days), a pCB that has proved to be effective for the treatment of nausea and anxiety in rodents. This study demonstrates that systemic treatment with the low dose of CBDA has anti-nociceptive effects and reduces the thermal hyperalgesia in 8 month-old MeCP2-308 male mice, a validated RTT mouse model. CBDA did not affect other behavioural or molecular parameters. These results provide support to the antinociceptive effects of CBDA and stress the need for further studies aimed at clarifying the mechanisms underlying the abnormal pain perception in RTT