Search results for "survey."
showing 10 items of 4020 documents
Use of dietary supplements and anabolic-androgenic steroids among Finnish adolescents in 1991-2005.
2009
Background : The aim of the study was to describe the prevalence, trends and associated factors of dietary supplements (DS) and anabolic-androgenic steroids (AAS) use among Finnish adolescents. Methods: The sample comprised 30 511 adolescents aged 12–18 years, of which 22 519 (74%) answered a questionnaire. We also studied associations between 14 socioeconomic, health and health behavioural variables and DS and AAS use by logistic regression. Results: The proportion of respondents using DS was 45% during the past year and it increased linearly by age. Vitamins (37%) and herbal products (13%) were the most common DSs. In 1991, 9% of the boys aged 16–18 years reported protein use, while the f…
Plant Productivity Dispersion and the College Premium: Evidence from the United States 1977-1997
2015
For the United States in 1987-2014, I document at business cycle frequencies that the high-skill workers’ employer size wage premium is high (low) in times of low (high) unemployment relative to that of the low-skill workers. Specifically, the differential employer size wage premium between high-skill and low-skill workers has an unconditional correlation of -0.4 with the unemployment rate, and varies by about 6 percent over the business cycle. The skill premium itself does not exhibit a clear business cycle pattern over the sample period.
Lifestyle changes and mental health during the COVID-19 pandemic: A repeated, cross-sectional web survey
2021
VBM acknowledges the national grant PI16/01770 from the Instituto de Salud Carlos III, ISCIII (The PROBILIFE study). EV thanks the support of the Spanish Ministry of Science and Innovation (PI15/00283, PI18/00805) integrated into the Plan Nacional de I+D+I and co-financed by the ISCIII-Subdirección General de Evaluación and the Fondo Europeo de Desarrollo Regional (FEDER); the Instituto de Salud Carlos III; the CIBER of Mental Health (CIBERSAM) (...)
Parallel and Distributed Resource Allocation With Minimum Traffic Disruption for Network Virtualization
2017
Wireless network virtualization has been advocated as one of the most promising technologies to provide multifarious services and applications for the future Internet by enabling multiple isolated virtual wireless networks to coexist and share the same physical wireless resources. Based on the multiple concurrent virtual wireless networks running on the shared physical substrate, service providers can independently manage and deploy different end-users services. This paper proposes a new formulation for bandwidth allocation and routing problem for multiple virtual wireless networks that operate on top of a single substrate network to minimize the operation cost of the substrate network. We …
Security in Mobile Wireless Sensor Networks – A Survey
2011
Published version of an article in the journal: Journal of Communications. Also available from the publisher at: http://dx.doi.org/10.4304/jcm.6.2.128-142. OA Thanks to recent advances in robotics, sensors and wireless communications, it is feasible to develop a variety of new architectures for Mobile Wireless Sensor Networks (MWSNs) that play an important role in various applications such as battlefield surveillance, harbor monitoring, etc. However, due to the dynamic of mobile network topology in MWSNs, many new security challenges have emerged. In this article, we give a survey on the state of the art technologies in security aspects of MWSNs. We review existing work that provides securi…
A Java-based Wrapper for Wireless Communications
2008
The increasing number of new applications for mobile devices in pervasive environments, do not cope with changes in the wireless communications. Developers of such applications have to deal with problems arising from the available wireless connections in the given environment. A middleware is a solution that allows to overcome some of these problems. It provides to the applications a set of functions that facilitate their development. In this paper we present a Java-based communication wrapper, called SmartTraffic, which allows programmers to seamlessly use TCP or UDP protocols over Bluetooth or any IP-based wireless network. Developers can use SmartTraffic within their Java applications, t…
A survey of wireless data center networks
2015
Data centers are becoming more and more popular for a wide variety of applications. However, the efficiency of data centers are restricted by many issues like cabling and maintenance problems in addition to performance problems like oversubscription. Wireless technology was proposed as it has the capability and the flexibility to offer feasible approaches to solve some of these problems. In this paper, we conduct a deep investigation about wireless data center networks, describe some works that enhance the performance of the network, then give some remarks and critiques. 2015 IEEE. Scopus
Implementation of green harvesting in the Sicilian wine industry: Effects on the cooperative system
2015
This paper contributes to assessing the effectiveness of the GH measure to contribute in reducing the supply of wine grapes, and thus contrasting the fall of wine prices in those years when especially abundant productions are expected. By analysing the application of this measure to the Sicilian wine sector during the three-year period (2010–2012), we assess its effects on the regional wine cooperative system. The results from the analysis of the statistical data show that the GH measure was successful in terms of the number of applications, the supported area and financial expenditures, and contributed with other factors to determining a reduction in wine grape production. The empirical su…
On building an infrastructure for mobile and wireless systems
2002
Over the last few years, there have been at least two dramatic changes in the way computers are used. The first has its origin in the fact that computers have become more and more connected to each other. The second was triggered by the increasing miniaturization and affordability of hardware components and power supplies, together with the development of wireless communication paths. These two trends combined have allowed the development of powerful, yet comparatively low-priced, portable computers. In spite of these changes, little attention has been given to reaching a common consensus and to the development of a strong infrastructure in this area.
Change and stability: Within-person life satisfaction over a 20-year period using data from the HUNT survey
2020
Background: The aim of the present study was to investigate within-person life satisfaction (LS) dynamics for two age groups, 20–29 and 30–39 years, from 1984 to 1986 and to follow them over a 20-year period. Methods: Data from 1984 to 2008 were extracted from the large, prospective, longitudinal North-Trøndelag Health Study (HUNT), Norway. This paper includes data from more than 14,500 persons. Data were analysed using logistic regression, and LS dynamics were modelled using gender, time and self-rated health. Results: The analyses revealed that about 20% of people in these age groups had a stable level in LS, also known as set point. Long-term LS change, defined as ⩾2 SDs, was reported f…