440 research outputs found
A comparison of methodological frameworks for digital learning game design
Methodological frameworks guide the design of digital learning game based on well founded learning theories and instructional strategies. This study presents a comparison of five methodological frameworks for digital learning game design, highlighting their similarities and differences. The objective is to support the choice of an adequate framework, aiming to promote them as a way to foster principled digital learning games design. This paper concludes that: (i) interactivity, engagement and increasing complexity of challenges are fundamental factors to digital learning game design; (ii) the pedagogical base, the target, the possibility of doing game assessment and the presence of practical guidelines are the selection criteria that influence most the choice of a methodological framework, and (iii) the development of digital learning games - preferably by different research teams - is needed to provide empirical evidence of the utility of framework-based design
A nighttime temperature maximum in the thermosphere above Saint Santin in winter
International audienceThe Saint Santin (45 N) incoherent scatter radar data base shows a local enhancement in nighttime ion temperature that occurs in winter only. Its amplitude can exceed 100 K and averages 40 K on the basis of a conservative computation. The enhancement peaks near 4 LT and has a duration of about 4 hours. We discuss two possible explanations for this feature: (1) it is caused by the convergence of global winds at the global pressure minimum, under which Saint Santin rotates at winter solstice, and (2) it is an extension or propagation of the well-known low-latitude midnight temperature maximum to midlatitudes, perhaps to that pressure minimum
West African equatorial ionospheric parameters climatology based on Ouagadougou ionosonde station data from June 1966 to February 1998
This study is the first which gives the climatology of West African equatorial ionosphere by using Ouagadougou station through three solar cycles. It has permitted to show the complete morphology of ionosphere parameters by analyzing yearly variation, solar cycle and geomagnetic activity, seasonal evolution and diurnal development. This work shows that almost all ionospheric parameters have 11-year solar cycle evolution. Seasonal variation shows that only <I>fo</I>F2 exhibits annual, winter and semiannual anomaly. <I>fo</I>F2 seasonal variation has permitted us to identify and characterize solar events effects on F2 layer in this area. In fact (1) during quiet geomagnetic condition <I>fo</I>F2 presents winter and semiannual anomalies asymmetric peaks in March/April and October. (2) The absence of winter anomaly and the presence of equinoctial peaks are the most visible effects of fluctuating activity in <I>fo</I>F2 seasonal time profiles. (3) Solar wind shock activity does not modify the profile of <I>fo</I>F2 but increases ionization. (4) The absence of asymmetry peaks, the location of the peaks in March and October and the increase of ionization characterize recurrent storm activity. F1 layers shows increasing trend from cycle 20 to cycle 21. Moreover, E layer parameters seasonal variations exhibit complex structure. It seems impossible to detect fluctuating activity effect in E layer parameters seasonal variations but shock activity and wind stream activity act to decrease E layer ionization. It can be seen from Es layer parameters seasonal variations that wind stream activity effect is fairly independent of solar cycle. E and Es layers critical frequencies and virtual heights diurnal variations let us see the effects of the greenhouse gases in these layers
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Preferential associations in an unstable social network: applying social network analysis to a dynamic sow herd
Preferential associations are fitness-enhancing ties between individuals, documented in a range of taxa. Despite this, research into preferential associations remains underrepresented in commercial species, particularly pigs. This study investigates the development of preferential associations in a dynamic sow herd. Preferential associations were defined as approaching a resting sow and then sitting or lying with physical contact with the selected sow, separated by 60 s. For individual identification, each sow was marked with colored dots, stripes, or both, corresponding to their ear-tag number. Preferential associations were measured over one production cycle of 21 days. Behavioral observations took place on 7 days of the study, with 3 h of behavior per day recorded during peak activity times (08:00-09:00, 15:00-16:00, 20:00-21:00 h). Behaviors were recorded using five cameras, each positioned within the barn to provide coverage of the functional areas. The network metrics applied included in-degree centrality (received ties), out-degree centrality (initiated ties), centralization (the extent to which an individual is central within the network), clustering coefficient (a measure of tie strength), and the E-I Index (a measure of assortment by trait: parity, familiarity, and sociality). Individuals were added and removed during the study, so the centrality metrics of missing sows were weighted. To describe the structure of the network, brokerage typologies were applied. Brokerage typologies include five positions, including coordinators, gatekeepers, representatives, consultants, and liaisons. The results revealed social discrimination in assortment by connectedness even when ties were not reciprocal, and the most connected sows were significantly more likely to be approached than less connected individuals. The most connected sows had significantly higher in-degree and out-degree centrality. With the application of brokerage typologies, the results showed a relationship between connectedness and brokering type, with the most connected sows predominantly engaging in coordinating behavior. The results suggest that the motivation for discrimination in the unstable preferential association network was not founded upon bidirectional interactions. These findings highlight the complexities involved when forming social preferences and present a platform for further exploring the motivations for preferential associations among intensively farmed pigs
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The effect of preferential associations on the reproductive performance of group-housed sows
The investigation of social bonds as a measure to improve reproduction in farmed species is an underrepresented research area. This study investigated the effects of preferential associations between group housed sows (average herd size, n = 59) on stillborn and crushed piglet numbers. Preferential associations were described as resting within 60 s. The study occurred over 63 consecutive days, broken down into three 21-day periods referred to as cycles. The 21-day cycles represent the time between reintegrating events. Seven days per cycle were selected for observations providing 63 h of footage covering the functional areas of the barn. Production data were taken from one farrowing that occurred after a sow had been transferred from the barn to the farrowing house during the study period. For group-level analysis, the sows were categorised as socially prominent or non-socially prominent. Social prominence is defined as an individual that engages in significantly higher levels of interactions than their sub-group conspecifics. The subgroups were determined by our previous work that identified assortment by social connectivity within the same study herd. Each subgroup was defined as a k-core, in which the k-value represents the level of connectivity of those in the group (i.e., subgroup K1 means sows are connecting with at least one other conspecific). For individual-level analysis, sows were categorised as a sow with stillborn (at least one stillborn piglet) or a sow without stillborn (no stillborn piglets) and as a crushing sow (at least one crushed piglet) or a non-crushing sow (no crushed piglets). Degree centrality was applied to determine the number of interactions that individuals initiated and received. Results showed no overall effects of social prominence on live-born piglets (p = 0.436). Socially prominent sows demonstrated a lower mean rate of stillborn than non-socially prominent sows. Sows with stillborn had significantly lower degree centrality than sows without stillborn (p < 0.05). The numbers of crushed piglets between socially prominent and non-socially prominent sows were variable with crushing sows demonstrating significantly higher degree centrality than non-crushing sows (p < 0.05). Overall, the evidence does not provide a clear relationship between social prominence during gestation and the reproductive outputs of sows. Therefore, further work is required to validate the effects of social position in affiliative networks on the production indices of farmed pigs
Mitochondrial DNA footprints from Western Eurasia in modern Mongolia
Mongolia is located in a strategic position at the eastern edge of the Eurasian Steppe. Nomadic populations moved across this wide area for millennia before developing more sedentary communities, extended empires, and complex trading networks, which connected western Eurasia and eastern Asia until the late Medieval period. We provided a fine-grained portrait of the mitochondrial DNA (mtDNA) variation observed in present-day Mongolians and capable of revealing gene flows and other demographic processes that took place in Inner Asia, as well as in western Eurasia. The analyses of a novel dataset (N = 2,420) of mtDNAs highlighted a clear matrilineal differentiation within the country due to a mixture of haplotypes with eastern Asian (EAs) and western Eurasian (WEu) origins, which were differentially lost and preserved. In a wider genetic context, the prevalent EAs contribution, larger in eastern and central Mongolian regions, revealed continuous connections with neighboring Asian populations until recent times, as attested by the geographically restricted haplotype-sharing likely facilitated by the Genghis Khan’s so-called Pax Mongolica. The genetic history beyond the WEu haplogroups, notably detectable on both sides of Mongolia, was more difficult to explain. For this reason, we moved to the analysis of entire mitogenomes (N = 147). Although it was not completely possible to identify specific lineages that evolved in situ, two major changes in the effective (female) population size were reconstructed. The more recent one, which began during the late Pleistocene glacial period and became steeper in the early Holocene, was probably the outcome of demographic events connected to western Eurasia. The Neolithic growth could be easily explained by the diffusion of dairy pastoralism, as already proposed, while the late glacial increase indicates, for the first time, a genetic connection with western Eurasian refuges, as supported by the unusual high frequency and internal sub-structure in Mongolia of haplogroup H1, a well-known post-glacial marker in Europe. Bronze Age events, without a significant demographic impact, might explain the age of some mtDNA haplogroups. Finally, a diachronic comparison with available ancient mtDNAs made it possible to link six mitochondrial lineages of present-day Mongolians to the timeframe and geographic path of the Silk Route
Cellular and humoral immune responses and protection against schistosomes induced by a radiation-attenuated vaccine in chimpanzees
The radiation-attenuated Schistosoma mansoni vaccine is highly effective in rodents and primates but has never been tested in humans, primarily for safety reasons. To strengthen its status as a paradigm for a human recombinant antigen vaccine, we have undertaken a small-scale vaccination and challenge experiment in chimpanzees (Pan troglodytes). Immunological, clinical, and parasitological parameters were measured in three animals after multiple vaccinations, together with three controls, during the acute and chronic stages of challenge infection up to chemotherapeutic cure. Vaccination induced a strong in vitro proliferative response and early gamma interferon production, but type 2 cytokines were dominant by the time of challenge. The controls showed little response to challenge infection before the acute stage of the disease, initiated by egg deposition. In contrast, the responses of vaccinated animals were muted throughout the challenge period. Vaccination also induced parasite-specific immunoglobulin M (IgM) and IgG, which reached high levels at the time of challenge, while in control animals levels did not rise markedly before egg deposition. The protective effects of vaccination were manifested as an amelioration of acute disease and overall morbidity, revealed by differences in gamma-glutamyl transferase level, leukocytosis, eosinophilia, and hematocrit. Moreover, vaccinated chimpanzees had a 46% lower level of circulating cathodic antigen and a 38% reduction in fecal egg output, compared to controls, during the chronic phase of infection
Vegetative endocarditis in equids (1994--2006).
peer reviewedBACKGROUND: Endocarditis is a rare heart condition with variable clinical expressions in equids. Risk factors for this disease are incompletely understood. OBJECTIVE: Describe risk factors for endocarditis in equids. ANIMALS: One hundred and fifty-three equids admitted to Liège University, 9 diagnosed with endocarditis and 144 free from endocarditis but admitted to the hospital with a differential diagnosis including this disease. METHODS: Retrospective case-control study. RESULTS: Equids with endocarditis were significantly younger (mean age = 4.84 +/- 5.74 years) than control equids (mean age = 10.8 +/- 7.73 years) (P = .01). No sex or breed predisposition was observed. Animals with hyperthermia (odds ratio [OR] = 24.4; confidence interval [CI] = 1.40-428), synovial distension (OR = 13.4; CI = 3.00-59.8), lameness (OR = 6.52; CI = 1.63-26.1), hyperglobulinemia (OR = 26.4; CI = 3.03-229), hypoalbuminemia (OR = 11.4; CI = 1.34-96.8), hyperfibrinogenemia (OR = 9.81; CI = 1.16-82.7), or leukocytosis (OR = 7.12; CI = 1.40-36.4) presented a significantly higher risk of having endocarditis than control horses. The presence of two of the clinical signs mentioned above significantly increased the probability of a diagnosis of endocarditis (P< or = .05). CONCLUSIONS AND CLINICAL IMPORTANCE: Age is associated with equine endocarditis. The diagnostic value of certain clinical signs and abnormalities in blood parameters in this disease are described
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