Video TFRC

TCP-friendly rate control (TFRC) is a congestion control technique that trade-offs responsiveness to the network conditions for a smoother throughput variation. We take advantage of this trade-off by calculating the rate gap between the theoretical TCP throughput and the smoothed TFRC throughput. Any rate gain from this rate gap is then opportunistically used for video coding. We define a frame complexity measure to determine the additional rate to be used from the rate gap and then perform a rate negotiation to determine the target rate for the encoder and the final sending rate. Results show that although this method has a more aggressive sending rate compared to TFRC, it is still TCP friendly, does not contribute too much to network congestion and achieves a reasonable video quality gain over the conventional method

Promoting the use of reliable rate based transport protocols: the Chameleon protocol

Rate-based congestion control, such as TFRC, has not been designed to enable reliability. Indeed, the birth of TFRC protocol has resulted from the need for a congestion-controlled transport protocol in order to carry multimedia traffic. However, certain applications still prefer the use of UDP in order to implement their own congestion control on top of it. The present contribution proposes to design and validate a reliable rate-based protocol based on the combined use of TFRC, SACK and an adapted flow control. We argue that rate-based congestion control is a perfect alternative to window-based congestion control as most of today applications need to interact with the transport layer and should not be only limited to unreliable services. In this paper, we detail the implementation of a reliable rate-based protocol named Chameleon and bring out to the networking community an ns-2 implementation for evaluation purpose

The Untold Story of the Clones: Content-agnostic Factors that Impact YouTube Video Popularity

Video dissemination through sites such as YouTube can have widespread impacts on opinions, thoughts, and cultures. Not all videos will reach the same popularity and have the same impact. Popularity differences arise not only because of differences in video content, but also because of other "content-agnostic" factors. The latter factors are of considerable interest but it has been difficult to accurately study them. For example, videos uploaded by users with large social networks may tend to be more popular because they tend to have more interesting content, not because social network size has a substantial direct impact on popularity. In this paper, we develop and apply a methodology that is able to accurately assess, both qualitatively and quantitatively, the impacts of various content-agnostic factors on video popularity. When controlling for video content, we observe a strong linear "rich-get-richer" behavior, with the total number of previous views as the most important factor except for very young videos. The second most important factor is found to be video age. We analyze a number of phenomena that may contribute to rich-get-richer, including the first-mover advantage, and search bias towards popular videos. For young videos we find that factors other than the total number of previous views, such as uploader characteristics and number of keywords, become relatively more important. Our findings also confirm that inaccurate conclusions can be reached when not controlling for content.Comment: Dataset available at: http://www.ida.liu.se/~nikca/papers/kdd12.htm

Gender Differences of Perceived Fresh Produce Retail Outlet Attributes in Trinidad and Tobago

In the Caribbean there is a dearth of literature on food marketing despite the significant changes taking place in food retailing in many developing countries. Traditionally, food shopping was considered woman’s work. Today a casual stroll in the supermarket or public market will reveal a large number of males undertaking the household food shopping task. This study focuses on the difference in perceived importance of outlet attributes by male and female primary household food shoppers in the context of fresh produce shopping in Trinidad and Tobago. The results obtained indicated that the two most important attributes for both males and females were – cleanliness of place and quality of fresh produce, though in different order of perceived importance. Only two of the twenty attributes analyzed were statistically significant for males and females – presentation of fresh produce and ease of getting to and from the retail outlet. This study makes an attempt to understand purchase behavior as traditional gender roles change and marketers try to develop strategies to better match the contemporary food market in Trinidad and Tobago. Keywords: Gender, Retail outlet attributes, Trinidadian and Tobagonian shoppers, Fresh produc

Ground-based measurements of immersion freezing in the eastern Mediterranean

Ice nuclei were measured in immersion-freezing mode in the eastern Mediterranean region using the FRIDGE-TAU (FRankfurt Ice-nuclei Deposition freezinG Experiment, the Tel Aviv University version) chamber. Aerosol particles were sampled during dust storms and on clean and polluted days (e.g., Lag BaOmer). The aerosol immersion-freezing potential was analyzed in the laboratory using a drop-freezing method. Droplets from all the samples were found to freeze between −11.8 °C and −28.9 °C. Immersion-freezing nuclei (FN) concentrations range between 0.16 L⁻¹ and 234 L⁻¹, while the activated fraction (AF) ranges between 8.7 × 10^&minus;8 and 4.9 × 10^&minus;4. The median temperature at which the drops from each filter froze was found to be correlated with the corresponding daily average of PM₁₀, PM_2.5 and PM₁₀–PM_2.5. A higher correlation value between FN concentrations and PM₁₀–PM_2.5 suggests that the larger particles are generally more effective as FN. <br><br> The measurements were divided into dust storms and "clean" conditions (this is a relative term, because dust particles are always present in the atmosphere is this region) based on the air mass back trajectories and the aerosol mass concentrations (PM₁₀). Droplets containing ambient particles from dust storm days froze at higher temperatures than droplets containing particles from clean days. Statistically significant differences were found between dust storms and clean conditions primarily in terms of the initial temperature at which the first drops froze, the median freezing temperature and the aerosol loading (PM values). FN concentrations and AF values in dust storms were larger by more than a factor of 2 than in the clean conditions. This observation agrees with previous studies showing that some dust particles are almost always present in the atmosphere in this region. <br><br> Measurements of aerosol particles emitted from wood burning bonfires during a Lag BaOmer holiday showed that although a high concentration of particles was emitted, those particles' effectiveness as FN was relatively poor. The most likely reason for the low FN efficiency is the combination of relatively low fire temperatures and high organic carbon fraction in the aerosols

Purchase Frequency of Roots and Tubers in Trinidad and Tobago.

Many of the non-communicable diseases (NCDs), such as obesity, colon cancer, diabetes and heart diseases being experienced in the Caribbean today can be attributed to changing lifestyles and urbanization. Roots and Tubers have been identified as having a beneficial role in the human diet against some of these diseases. Efforts to increase the purchase frequency and ultimately their consumption in the Caribbean with a view of reducing the current food import bill require the input of researchers. This study focuses on the socioeconomic variables that influence the purchase frequency of roots and tubers in Trinidad and Tobago. The results obtained indicated that the statistically significant variables were age, employment status and marital status. It is therefore concluded that income, gender, educational level attained, ethnicity, and household size does not influence the purchase frequency of roots and tubers in Trinidad and Tobago. Keywords: Socio-demographic variables, Trinidadian and Tobagonians, Purchase frequency, Roots and Tuber

Retail Outlet Attributes Influencing Store Choice for Roots and Tubers in Trinidad and Tobago

From a retail outlet perspective, traditionally fresh produce, including Roots and Tuber (R&amp;Ts) was predominantly sold in the public markets and roadside stalls in the Caribbean. Today a casual stroll in the supermarket will reveal the wide array of R&amp;Ts available to consumers. A review of the food marketing literature reveals that though there have been extensive studies undertaken in developed countries on patronage of traditional and modern food retail outlets, there is a dearth of research on the changing food market in the Caribbean and why some people still visit the public markets. This study focuses on the outlet attributes as factors influencing shoppers’ retail outlet choice for R&amp;Ts in Trinidad and Tobago. The results obtained indicated that the traditional outlet is still the preferred outlet for R&amp;Ts. In the opinion of the customers Price of R&amp;Ts, Variety of R&amp;Ts, Quality of R&amp;Ts, Ability to self select R&amp;Ts, Ability to haggle over price, Outlet near home, and Friendliness of sales persons were statistically different and play an important role in the customers’ decision regarding the choice of retail outlet. Keywords: Retail outlet attributes, Retail outlet choice, Roots and Tubers, Traditional outlet, Modern outle