3,489 research outputs found

    Users’ Continued Usage of Online Healthcare Virtual Communities: An Empirical Investigation in the Context of HIV Support Communities

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    This study uses data from an online HIV/AIDS health support virtual community to examine whether users’ emotional states and the social support they receive influence their continued usage. We adopt grief theory to conceptualize the negative emotions that people living with HIV/AIDS could experience. Linguistic analysis is used to measure the emotional states of the users and the informational and emotional support that they receive. Results show that users showing a higher level of disbelief and yearning are more likely to leave the community while those with a high level of anger and depression are more likely to stay on. Users who receive more informational support are more likely to leave once they have obtained the information they sought, but those who receive more emotional support are more likely to stay on. The findings of this study can help us better understand users’ support seeking behavior in online support VCs

    Foreign Lobbies and US Trade Policy

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    In popular discussion much has been made recently of the susceptibility of government policies to lobbying by foreigners. The general presumption has also been that such interactions have a deleterious effect on the home economy. However, it can be argued that, in a trade policy context, bending policy in a direction that would suit foreigners may not in fact be harmful: If the policy outcome absent any lobbying by foreigners is characterized by welfare-reducing trade barriers, lobbying by foreigners may result in reductions in such barriers and raise consumer surplus (and possibly improve welfare). Using a new data set on foreign political activity in the US, this paper investigates the relationship between trade protection and lobbying activity empirically. The approach taken in this paper is primarily a structural one. To model the role of foreign and domestic lobbies in determining trade policy, we develop first a theoretical framework building on the well-known work of Grossman and Helpman (1994); the econometric work that follows is very closely linked to the theory. Our analysis of the data suggests that foreign lobbying activity has significant impact on trade policy - and in the predicted direction: Tariffs and non-tariff barriers (NTBs) are both found to be negatively related with foreign lobbying activity. We consider also extended specifications in which we include a large number of additional explanatory variables that have been suggested in the literature as determinants of trade policy (but that emerge from outside of the theoretical structure described above) and confirm the robustness of our findings in this setting.

    The Gene Ontology: enhancements for 2011

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    The Gene Ontology (GO) (http://www.geneontology.org) is a community bioinformatics resource that represents gene product function through the use of structured, controlled vocabularies. The number of GO annotations of gene products has increased due to curation efforts among GO Consortium (GOC) groups, including focused literature-based annotation and ortholog-based functional inference. The GO ontologies continue to expand and improve as a result of targeted ontology development, including the introduction of computable logical definitions and development of new tools for the streamlined addition of terms to the ontology. The GOC continues to support its user community through the use of e-mail lists, social media and web-based resources

    Comparison of lower order and higher order nonclassicality in photon added and photon subtracted squeezed coherent states

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    Nonclassical properties of photon added and photon subtracted squeezed coherent states have been compared with specific focus on the higher order nonclassicalities, such as higher order squeezing, higher order sub-Poissonian photon statistics, higher order antibunching. It is observed that both photon added and photon subtracted squeezed coherent states are highly nonclassical as they satisfy criteria for all of the above mentioned nonclassicalities and a set of other criteria including negativity of Wigner function, Klyshko's criterion and Agarwal's (A3)(A_{3}) parameter. Further, the amount of nonclassicality present in these two types of states has been compared quantitatively using a measure of nonclassicality known as nonclassical volume. Variation in the amount of nonclassicality with the number of photon(s) added/subtracted is also investigated, and it is found that the addition of photons makes the squeezed coherent state more nonclassical than what is done by the subtraction of photons.Comment: 23 pages 11 figure

    Soft Handoff and Uplink Capacity in a Two-Tier CDMA System

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    This paper examines the effect of soft handoff on the uplink user capacity of a CDMA system consisting of a single macrocell in which a single hotspot microcell is embedded. The users of these two base stations operate over the same frequency band. In the soft handoff scenario studied here, both macrocell and microcell base stations serve each system user and the two received copies of a desired user's signal are summed using maximal ratio combining. Exact and approximate analytical methods are developed to compute uplink user capacity. Simulation results demonstrate a 20% increase in user capacity compared to hard handoff. In addition, simple, approximate methods are presented for estimating soft handoff capacity and are shown to be quite accurate.Comment: To appear in IEEE Transactions on Wireless Communication

    Uplink Throughput in a Single-Macrocell/Single-Microcell CDMA System, with Application to Data Access Points

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    This paper studies a two-tier CDMA system in which the microcell base is converted into a data access point (DAP), i.e., a limited-range base station that provides high-speed access to one user at a time. The microcell (or DAP) user operates on the same frequency as the macrocell users and has the same chip rate. However, it adapts its spreading factor, and thus its data rate, in accordance with interference conditions. By contrast, the macrocell serves multiple simultaneous data users, each with the same fixed rate. The achieveable throughput for individual microcell users is examined and a simple, accurate approximation for its probability distribution is presented. Computations for average throughputs, both per-user and total, are also presented. The numerical results highlight the impact of a desensitivity parameter used in the base-selection process.Comment: To appear in IEEE Transactions on Wireless Communication

    Uplink User Capacity in a CDMA System with Hotspot Microcells: Effects of Finite Transmit Power and Dispersion

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    This paper examines the uplink user capacity in a two-tier code division multiple access (CDMA) system with hotspot microcells when user terminal power is limited and the wireless channel is finitely-dispersive. A finitely-dispersive channel causes variable fading of the signal power at the output of the RAKE receiver. First, a two-cell system composed of one macrocell and one embedded microcell is studied and analytical methods are developed to estimate the user capacity as a function of a dimensionless parameter that depends on the transmit power constraint and cell radius. Next, novel analytical methods are developed to study the effect of variable fading, both with and without transmit power constraints. Finally, the analytical methods are extended to estimate uplink user capacity for multicell CDMA systems, composed of multiple macrocells and multiple embedded microcells. In all cases, the analysis-based estimates are compared with and confirmed by simulation results.Comment: To appear in IEEE Transactions on Wireless Communication

    Transcriptional factor PU.1 regulates decidual C1q expression in early pregnancy in human

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    "Copyright: © 2015 Madhukaran, Kishore, Jamil, Teo, Choolani and Lu. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms."C1q is the first recognition subcomponent of the complement classical pathway, which in addition to being synthesized in the liver, is also expressed by macrophages and dendritic cells (DCs). Trophoblast invasion during early placentation results in accumulation of debris that triggers the complement system. Hence, both early and late components of the classical pathway are widely distributed in the placenta and decidua. In addition, C1q has recently been shown to significantly contribute to feto-maternal tolerance, trophoblast migration, and spiral artery remodeling, although the exact mechanism remains unknown. Pregnancy in mice, genetically deficient in C1q, mirrors symptoms similar to that of human preeclampsia. Thus, regulated complement activation has been proposed as an essential requirement for normal successful pregnancy. Little is known about the molecular pathways that regulate C1q expression in pregnancy. PU.1, an Ets-family transcription factor, is required for the development of hematopoietic myeloid lineage immune cells, and its expression is tissue-specific. Recently, PU.1 has been shown to regulate C1q gene expression in DCs and macrophages. Here, we have examined if PU.1 transcription factor regulates decidual C1q expression. We used immune-histochemical analysis, PCR, and immunostaining to localize and study the gene expression of PU.1 transcription factor in early human decidua. PU.1 was highly expressed at gene and protein level in early human decidual cells including trophoblast and stromal cells. Surprisingly, nuclear as well as cytoplasmic PU.1 expression was observed. Decidual cells with predominantly nuclear PU.1 expression had higher C1q expression. It is likely that nuclear and cytoplasmic PU.1 localization has a role to play in early pregnancy via regulating C1q expression in the decidua during implantation

    Developing an object detection and gripping mechanism algorithm using machine learning

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    Localizing and recognition of objects are critical problems for indoor manipulation tasks. This paper describes an algorithm based on computer vision and machine learning that does object detection and gripping tasks. Detection of objects is carried out using a combination of a camera and depth sensor using a Kinect v1 depth sensor. Moreover, machine learning algorithms (YOLO) are used for computer vision. The project presents a method that allows the Kinect sensor to detect objects' 3D location. At the same time, it is attached to any robotic arm base, allowing for a more versatile and compact solution to be used in stationary places using industrial robot arms or mobile robots. The results show an error of locating an object to be 5 mm. and more than 70% confidence in detecting objects correctly. There are many possibilities in which this project can be used, such as in industrial fields, to sort, load, and unload different kinds of objects based on their type, size, and shape. In agriculture fields, to collect or sort different kinds of fruits, in kitchens and cafes where sorting objects like cups, bottles, and cans can occur. Also, this project can be added to mobile robots to do indoor human services or collect trash from different places
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