Opportunistic Interference Mitigation Achieves Optimal Degrees-of-Freedom in Wireless Multi-cell Uplink Networks

We introduce an opportunistic interference mitigation (OIM) protocol, where a user scheduling strategy is utilized in $K$-cell uplink networks with time-invariant channel coefficients and base stations (BSs) having $M$ antennas. Each BS opportunistically selects a set of users who generate the minimum interference to the other BSs. Two OIM protocols are shown according to the number $S$ of simultaneously transmitting users per cell: opportunistic interference nulling (OIN) and opportunistic interference alignment (OIA). Then, their performance is analyzed in terms of degrees-of-freedom (DoFs). As our main result, it is shown that $KM$ DoFs are achievable under the OIN protocol with $M$ selected users per cell, if the total number $N$ of users in a cell scales at least as $\text{SNR}^{(K-1)M}$. Similarly, it turns out that the OIA scheme with $S$($<M$) selected users achieves $KS$ DoFs, if $N$ scales faster than $\text{SNR}^{(K-1)S}$. These results indicate that there exists a trade-off between the achievable DoFs and the minimum required $N$. By deriving the corresponding upper bound on the DoFs, it is shown that the OIN scheme is DoF optimal. Finally, numerical evaluation, a two-step scheduling method, and the extension to multi-carrier scenarios are shown.Comment: 18 pages, 3 figures, Submitted to IEEE Transactions on Communication

Nano- and micro-scale studies of exocytosis

The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file.Title from title screen of research.pdf file (viewed on March 24, 2009)Vita.Thesis (Ph.D.) University of Missouri-Columbia 2007.Neurons and neuroendocrine cells contain vesicles packed with hormones or neurotransmitters. Upon appropriate stimulation, a rise in intracellular Ca2+ concentration triggers the fusion of vesicles with the outer membrane of cells and release of vesicle contents into the extracellular space in a process called exocytosis. In this thesis, we developed three new nano- and micro- techniques to study exocytosis. 1. We used scanning ion conductance microscopy (SICM) to image changes in the surface membrane of adrenal chromaffin cells after stimulation of exocytosis. Punctate depressions were noted in clusters of two or more. Increases in membrane surface area, consistent with the fusion and collapse of one or more vesicles into the surface membrane, were observed 64% of the cells. 2. We used a microcontact printing method with PDMS stamps by "soft" lithography to pattern microislands of rat hippocampal neurons to form autapses. Neurons on microstamped microislands survived and grew neurites for more than 21 days and resembled microisland cultures formed by the traditional method of spraying collagen on agarose coated substrates. 3. Microfabricated devices were developed to electrochemically measure quantal catecholamine release from an array of individual cells. Here we report patterning of cellsized holes in [tilde operator] 15 m-thick films. These films are placed on transparent indium tin oxide electrodes to insulate the unused part of the electrode whereas the holes in the film both determine the location of the working electrode and serve as pockets for cell trapping. We found that this approach represents a simple and effective way to target cells to electrodes to record amperometric spikes.Includes bibliographical reference

Can One Achieve Multiuser Diversity in Uplink Multi-Cell Networks?

We introduce a distributed opportunistic scheduling (DOS) strategy, based on two pre-determined thresholds, for uplink $K$-cell networks with time-invariant channel coefficients. Each base station (BS) opportunistically selects a mobile station (MS) who has a large signal strength of the desired channel link among a set of MSs generating a sufficiently small interference to other BSs. Then, performance on the achievable throughput scaling law is analyzed. As our main result, it is shown that the achievable sum-rate scales as $K\log(\text{SNR}\log N)$ in a high signal-to-noise ratio (SNR) regime, if the total number of users in a cell, $N$, scales faster than $\text{SNR}^{\frac{K-1}{1-\epsilon}}$ for a constant $\epsilon\in(0,1)$. This result indicates that the proposed scheme achieves the multiuser diversity gain as well as the degrees-of-freedom gain even under multi-cell environments. Simulation results show that the DOS provides a better sum-rate throughput over conventional schemes.Comment: 11 pages, 3 figures, 2 tables, to appear in IEEE Transactions on Communication

Optimal Multiuser Diversity in Multi-Cell MIMO Uplink Networks: User Scaling Law and Beamforming Design

We introduce a distributed protocol to achieve multiuser diversity in a multicell multiple-input multiple-output (MIMO) uplink network, referred to as a MIMO interfering multiple-access channel (IMAC). Assuming both no information exchange among base stations (BS) and local channel state information at the transmitters for the MIMO IMAC, we propose a joint beamforming and user scheduling protocol, and then show that the proposed protocol can achieve the optimal multiuser diversity gain, i.e., KM log (SNR log N), as long as the number of mobile stations (MSs) in a cell, N, scales faster than SNRKM-L/1-epsilon for a small constant epsilon &gt; 0, where M, L, K, and SNR denote the number of receive antennas at each BS, the number of transmit antennas at each MS, the number of cells, and the signal-to-noise ratio, respectively. Our result indicates that multiuser diversity can be achieved in the presence of intra-cell and inter-cell interference even in a distributed fashion. As a result, vital information on how to design distributed algorithms in interference-limited cellular environments is provided

Examining the links between burnout and suicidal ideation in diverse occupations

IntroductionIt is uncertain whether burnout is associated with suicidal ideation among workers not in health care services. The aim of this study was to identify how burnout and suicidal ideation are linked among employees in various occupations and whether depression affects this link.MethodsThis cross-sectional study collected data from 12,083 participants aged 19–65 years from 25 companies and public institutions who underwent workplace mental health screening. Burnout and depression were assessed using both the Oldenburg Burnout Inventory and the Center for Epidemiologic Studies Depression Scale. Suicidal ideation was assessed by a self-rated questionnaire from the Korea National Health and Nutrition Examination Survey.ResultsExhaustion but not the cynicism dimension of burnout was associated with increased odds of suicidal ideation after adjustment for depression and other covariates (odds ratio [OR] = 1.47, 95% CI = 1.26–1.72). The association of exhaustion with suicidal ideation was significant in both depressed (OR = 1.36, 95% CI = 1.14–1.61) and not depressed (OR = 1.77, 95% CI = 1.13–2.76) participants. In exhausted participants, insufficient job control, an unfavorable occupational climate, low educational level, and depression were associated with increased odds of suicidal ideation.ConclusionExhaustion is linked with risk of suicidal ideation in employees not in health care service, regardless of depression status. Exhausted employees, particularly those having poor job resources, should be recognized as an at-risk group

A Case of Necrotizing Keratoscleritis in Primary Sjogren's Syndrome

We report on a case of necrotizing keratoscleritis in primary Sjogren's syndrome. A 66-year-old female patient who was complaining of ocular pain, tearing and decreased vision in her right eye for the previous two days was admitted to our hospital. Visual acuity in the right eye was hand movement, and initial examination showed a 3.0 × 1.8 mm uveal mass bulging through a corneoscleral melting site in the nasal region of the right eye. Positive anti-nuclear antibody was identified at a titer of 1:320 with a speckled pattern, and both Sjogren's syndrome A and Sjogren's syndrome B antibody tests were positive, with titers >200 U/mL. A technetium 99m pertechnetate salivary scan revealed chronic sialoadenitis in the submandibular glands. We diagnosed the lesion as necrotizing keratoscleritis due to primary Sjogren's syndrome. A corneoscleral patch graft was performed, followed by immunosuppression including oral cyclosporin and topical prednisolone. During a follow-up period of 12 months, the corneoscleral graft was well maintained with no recurrence

Importância dos Saca-Rabos (Herpestes Ichneumon) como Reservatório de Mycobacterium avium subsp. paratuberculosis. Deteção por Técnicas Tradicionais e Moleculares

Poster apresentado nas IV Jornadas de Genética, realizadas na UTAD, Vila Real, nos dias 1,2 e 3 de Março de 2012.Os saca-rabos (Herpestes ichneumon) também conhecidos por mangustos, são carnívoros diurnos selvagens que juntamente com a geneta (Genetta genetta) representam os exemplares da família Viverridae em Portugal. É uma espécie cinegética de caça menor que se alimenta de coelhos, roedores, aves, cobras, insectos e ovos. Neste estudo colheram-se amostras de 8 animais mortos por atropelamento e em ações de controlo de predadores, durante os anos de 2010 e 2011, nos concelhos de Idanha-a-Nova e Penamacor do distrito de Castelo Branco. As amostras colhidas foram fígado, pulmão, baço, intestino, rim, gânglio mesentérico, retrofaríngeo, mediastínico, amígdalas e fezes. As amostras foram submetidas à técnica de PCR e a cultura microbiológica em meios específicos. Em três saca-rabos (37,5%) detectou-se Mycobacterium avium subsp. paratuberculosis (Map) através da técnica de biologia molecular. Dois eram machos e um era fêmea. Map foi confirmado também em cultura nos dois machos. Sete saca-rabos (87,5%) apresentaram bactérias álcool-ácido resistentes compatíveis com Map em esfregaços de diferentes tecidos, quando corados pelo método de Ziehl-Neelsen. Estes resultados preliminares confirmam os saca-rabos como reservatório de Map no nosso país. Atualmente, estão a ser desenvolvidos mais estudos para a avaliação dos saca-rabos na dinâmica da infeção de Map em mamíferos selvagens