"From the moment i wake up i will use it?every day, very hour": A qualitative study on the patterns of adolescents' mobile touch screen device use from adolescent and parent perspectives

Background: The use of mobile touch screen devices, e.g. smartphones and tablet computers, has become increasingly prevalent among adolescents. However, little is known about how adolescents use these devices and potential influences on their use. Hence, this qualitative study explored adolescents' perceptions on their patterns of use and factors influencing use, and perceptions and concerns from parents. Methods: Semi-structured interviews were conducted with adolescents (n = 36; 11 to 18 years) and their parents/caregivers (n = 28) in Singapore recruited to represent males and females across a range of ages from different socioeconomic groups. Prompts covered weekday and weekend use patterns, types of activities, perspectives on amount of use, parental control measures and concerns. Interviews were recorded and transcribed. Transcripts were coded and thematic analysis was carried out. Results: Smartphone was the most common mobile device owned and used by many of the adolescents, while only some used a tablet. Many adolescents and their parents felt that adolescents' MTSD use was high, frequent and ubiquitous, with frequent checking of device and multitasking during use. Reported influences of use included functional, personal and external influences. Some of the influences were irresistibility of mobile devices, lack of self-control, entertainment or relaxation value, and high use by peers, family and for schoolwork that contributed to high use, or school/parental control measures and lack of internet availability that limited use. Most adolescents were generally unconcerned about their use and perceived their usage as appropriate, while most parents expressed several concerns about their adolescents' use and perceived their usage as excessive. Conclusions: This study has provided rich insights into the patterns and influences of contemporary mobile device use by adolescents. Mobile device use has become an integral part of adolescents' daily routines, and was affected by several functional, personal and external influences which either facilitated or limited their use. There also seemed to be a strong inclination for adolescents to frequently check and use their mobile devices. There is an urgent need to understand the implications of these common adolescent behaviours to inform advice for wise mobile device use by adolescents

A simple model of international joint venture distributorships: the American-Kuwaiti experience

The paper develops an analytical model for analyzing international joint venture distributorships in marketing channels selling highly differentiated industrial products. Regarding four alternative forms of demand functions, profits of channel members and consumer welfare under the joint venture arrangement are compared with those under the classic vertical integrated and decentralized structures. Furthermore, optimal allocation of joint venture benefits is discussed and the influence of attitude towards risk and bargaining power have been examined. A case study from international marketing is presented in relation to the theoretical work developed herein. It describes the events that have lead to the formation of a joint venture between an American manufacturer and a Kuwaiti distributor as well as the factors that have contributed to its termination. Implications of the research and its findings to management are also discussed.business strategy case study distribution joint ventures marketing optimization

D and H in the Lower and Upper Atmosphere of Mars

International audienceThe water cycle in the near-surface region of Mars is coupled to the lower atmosphere via multiple mechanisms that include seasonal dust and circulation driven processes. The variability of water and its isotopologue, HDO, vary similarly and with similar patterns near the surface as well as at altitudes up to 80 km. At higher altitudes, water molecules are broken down into atoms. Measurements of H and D, made in the upper atmosphere of Mars show variations that differ from their lower altitude parent molecules. Observations of H and D, made by the MAVEN mission, spanning four Mars Years are analyzed. Preliminary results indicate that the water-originating atoms in the upper atmosphere are decoupled from water molecules at lower altitudes. These findings can inform the water cycle on present day Mars, and provide improved estimates for water loss from the planet

Analysis and modeling of remote observations of the martian hydrogen exosphere

International audiencePast observations of the martian exosphere have given a wide range of values for the mean temperature and number density of the hydrogen population that occupies this uppermost layer. More recently, observations by HST and MEX have found large variations over short timescales exhibited by this layer, which have been attributed to seasonal effects. Here we present an analysis of the modeling techniques used to study the martian exosphere and their related uncertainties, and discuss the sensitivity of various modeling parameters for any remote observations of the martian hydrogen exosphere. Degeneracy between the two free parameters in the model, the exobase temperature and density of hydrogen at Mars introduces difficulty in accurately characterizing the properties of the martian exosphere. An independent measurement of at least one parameter is required in order to positively identify the other. The likely presence of a superthermal component of H adds another uncertainty to the modeling process, with large changes in the resulting escape flux. A study of the latitudinal symmetry of the martian exosphere found the radial emission profiles to be asymmetric below 2.5 martian radii, and then more uniform at high altitudes. Comparisons between simulated spacecraft and HST intensity profiles with altitude suggest that a larger coverage of intensity profiles is important to better determine the characteristics of the martian exosphere

Effect of the 2018 Martian global dust storm on the CO₂ density in the lower nightside thermosphere observed from MAVEN/IUVS Lyman‐alpha absorption

International audienceThe MAVEN/IUVS instrument measures Lyman‐α emissions from interplanetary and martian hydrogen at the limb and through the extended corona of Mars. In June 2018, a Global Dust Storm (GDS) surrounded Mars for a few months, heating the lower atmosphere and leading to an expansion of the Martian atmosphere. Nightside IUVS observations before and throughout this GDS showed the altitude of CO2 absorption of Lyman‐α photons in the thermosphere to increase by 4.5±1.0 km on 8 June 2018. This shift is attributed to an increase of the CO2 density by a factor 1.9±0.2 at 110 km due to the heating of the lower atmosphere. These nightside observations, not previously used to study dust storms, in an altitude range not sampled by other instruments, are consistent with dayside MAVEN observations and allow for more comprehensive determination of the global changes produced by the GDS on the Martian thermosphere