Multi-user lattice coding for the multiple-access relay channel

This paper considers the multi-antenna multiple access relay channel (MARC), in which multiple users transmit messages to a common destination with the assistance of a relay. In a variety of MARC settings, the dynamic decode and forward (DDF) protocol is very useful due to its outstanding rate performance. However, the lack of good structured codebooks so far hinders practical applications of DDF for MARC. In this work, two classes of structured MARC codes are proposed: 1) one-to-one relay-mapper aided multiuser lattice coding (O-MLC), and 2) modulo-sum relay-mapper aided multiuser lattice coding (MS-MLC). The former enjoys better rate performance, while the latter provides more flexibility to tradeoff between the complexity of the relay mapper and the rate performance. It is shown that, in order to approach the rate performance achievable by an unstructured codebook with maximum-likelihood decoding, it is crucial to use a new K-stage coset decoder for structured O-MLC, instead of the one-stage decoder proposed in previous works. However, if O-MLC is decoded with the one-stage decoder only, it can still achieve the optimal DDF diversity-multiplexing gain tradeoff in the high signal-to-noise ratio regime. As for MS-MLC, its rate performance can approach that of the O-MLC by increasing the complexity of the modulo-sum relay-mapper. Finally, for practical implementations of both O-MLC and MS-MLC, practical short length lattice codes with linear mappers are designed, which facilitate efficient lattice decoding. Simulation results show that the proposed coding schemes outperform existing schemes in terms of outage probabilities in a variety of channel settings.Comment: 32 pages, 5 figure

Filter and nested-lattice code design for fading MIMO channels with side-information

Linear-assignment Gel'fand-Pinsker coding (LA-GPC) is a coding technique for channels with interference known only at the transmitter, where the known interference is treated as side-information (SI). As a special case of LA-GPC, dirty paper coding has been shown to be able to achieve the optimal interference-free rate for interference channels with perfect channel state information at the transmitter (CSIT). In the cases where only the channel distribution information at the transmitter (CDIT) is available, LA-GPC also has good (sometimes optimal) performance in a variety of fast and slow fading SI channels. In this paper, we design the filters in nested-lattice based coding to make it achieve the same rate performance as LA-GPC in multiple-input multiple-output (MIMO) channels. Compared with the random Gaussian codebooks used in previous works, our resultant coding schemes have an algebraic structure and can be implemented in practical systems. A simulation in a slow-fading channel is also provided, and near interference-free error performance is obtained. The proposed coding schemes can serve as the fundamental building blocks to achieve the promised rate performance of MIMO Gaussian broadcast channels with CDIT or perfect CSITComment: submitted to IEEE Transactions on Communications, Feb, 200

Cognitive Radio with Partial Channel State Information at the Transmitter

In this paper, we present the cognitive radio system design with partial channel state information known at the transmitter (CSIT).We replace the dirty paper coding (DPC) used in the cognitive radio with full CSIT by the linear assignment Gel'fand-Pinsker coding (LA-GPC), which can utilize the limited knowledge of the channel more efficiently. Based on the achievable rate derived from the LA-GPC, two optimization problems under the fast and slow fading channels are formulated. We derive semianalytical solutions to find the relaying ratios and precoding coefficients. The critical observation is that the complex rate functions in these problems are closely related to ratios of quadratic form. Simulation results show that the proposed semi-analytical solutions perform close to the optimal solutions found by brute-force search, and outperform the systems based on naive DPC. Asymptotic analysis also shows that these solutions converge to the optimal ones solved with full CSIT when the K-factor of Rician channel approaches infinity. Moreover, a new coding scheme is proposed to implement the LA-GPC in practice. Simulation results show that the proposed practical coding scheme can efficiently reach the theoretical rate performance.Comment: resubmitted to IEEE Transaction on Wireless Communications, May 200

Women with endometriosis have higher comorbidities: Analysis of domestic data in Taiwan

AbstractEndometriosis, defined by the presence of viable extrauterine endometrial glands and stroma, can grow or bleed cyclically, and possesses characteristics including a destructive, invasive, and metastatic nature. Since endometriosis may result in pelvic inflammation, adhesion, chronic pain, and infertility, and can progress to biologically malignant tumors, it is a long-term major health issue in women of reproductive age. In this review, we analyze the Taiwan domestic research addressing associations between endometriosis and other diseases. Concerning malignant tumors, we identified four studies on the links between endometriosis and ovarian cancer, one on breast cancer, two on endometrial cancer, one on colorectal cancer, and one on other malignancies, as well as one on associations between endometriosis and irritable bowel syndrome, one on links with migraine headache, three on links with pelvic inflammatory diseases, four on links with infertility, four on links with obesity, four on links with chronic liver disease, four on links with rheumatoid arthritis, four on links with chronic renal disease, five on links with diabetes mellitus, and five on links with cardiovascular diseases (hypertension, hyperlipidemia, etc.). The data available to date support that women with endometriosis might be at risk of some chronic illnesses and certain malignancies, although we consider the evidence for some comorbidities to be of low quality, for example, the association between colon cancer and adenomyosis/endometriosis. We still believe that the risk of comorbidity might be higher in women with endometriosis than that we supposed before. More research is needed to determine whether women with endometriosis are really at risk of these comorbidities

Development and Evaluation of Psychometric Properties Regarding the Whole Person Health Scale for Employees of Hospital to Emphasize the Importance of Health Awareness of the Workers in the Hospital

(1) Background: Whole person health (WPH) is important among employees in hospitals. It will affect their performance and attitude toward patient care and organization. This project was designed to develop and assess the validity and reliability of utilizing the Whole Person Health Scale for Employees of a Hospital (WPHS-EH) to determine overall employee health. (2) Methods: A mixed-methods focus group and cross-sectional survey was adopted. Employees held six focus groups, with 62 employees from different departments in medical center in Taiwan. After analyzing the interview content, five experts tested its validity, and the 14-item WPHS-EH scale was analyzed. This was followed by an additional 900 participants questionnaire survey, response rate: 94.9%. Descriptive statistics, Cronbach’s alpha, exploratory factor analysis (EFA), and items analysis were used. Additionally, the scale was implemented to conducted confirmatory factor analysis (CFA) test for validity. (3) Results: Three dimensions were extracted from the questionnaires by EFA: “hospital circumstance and system”, “professional and interpersonal interaction” and “workload and harm”. The Cronbach’s alpha of the WPHS-EH scale was 0.82, while the three sub-dimensions were all significantly correlated with total scores. CFA confirmed the scale construct validity, with a good model fit. (4) Conclusions: The WPHS-EH is a reliable measurement tool to assess the effects of hospitals’ Whole Person Health among employees. The intent of the WPHS-EH was to provide a reliable scale to analyze the work environment for hospital staff and useful information to healthcare administrators interested in improving the staff’s whole person health

Demoralization Syndrome Among Elderly Patients with Cancer Disease

Summary: Background: Demoralization is distinctive psychological distress that involves hopelessness, helplessness, loss of purpose and meaning, and existential distress. Cancer patients' demoralization has been well documented, but little is known regarding older cancer patients and the related factors. Therefore, this study evaluated demoralization syndrome in older cancer patients. Methods: Cancer patients over 61 years old (n = 113, female 59.3%, mean age 65.7 years, range 61–80) diagnosed with heterogeneous types of cancer were recruited. They completed questionnaires in a hospital's inpatient and outpatient units. Their demoralization was measured using the Demoralization Scale-Mandarin Version (DS-MV). The Patient Health Questionnaire-9 (PHQ-9), Distress Thermometer (DT), Beck Scale for Suicide Ideation (BSS), and Posttraumatic Growth Inventory (PTGI) were used to measure other psychological statuses and the association with demoralization. Results: The mean DS-MV score was 28.1 (SD = 16.3). In this sample, 57.7% had moderate to high demoralization (18.6% had moderate demoralization, and 38.1% had high demoralization). Twenty-three percent reported a DT score of five and above, 5.5% reported a PHQ-9 score of 10 and above, and 23.9% reported a BSS score greater than zero. Demoralization was associated with suicide ideation, depression, distress, lower education, and the cancer site. Demoralization was not associated with posttraumatic growth, gender, work status, or religion. Conclusion: More than half of older cancer patients have moderate to high demoralization and it is associated with depression, suicide ideation, and distress. Screening and interventions that are better tailored to older cancer patients could improve the quality of care in cancer treatment. Keywords: aged, cancer, depression, hospice care/psychology, moral

Prediction of Mortality in Older Hospitalized Patients after Discharge as Determined by Comprehensive Geriatric Assessment

Several dimensional impairments regarding Comprehensive Geriatric Assessment (CGA) have been shown to be associated with the prognosis of older patients. The purpose of this study is to investigate mortality prediction factors based upon clinical characteristics and test in CGA, and then subsequently develop a prediction model to classify both short- and long-term mortality risk in hospitalized older patients after discharge. A total of 1565 older patients with a median age of 81 years (74.0–86.0) were consecutively enrolled. The CGA, which included assessment of clinical, cognitive, functional, nutritional, and social parameters during hospitalization, as well as clinical information on each patient was recorded. Within the one-year follow up period, 110 patients (7.0%) had died. Using simple Cox regression analysis, it was shown that a patient’s Length of Stay (LOS), previous hospitalization history, admission Barthel Index (BI) score, Instrumental Activity of Daily Living (IADL) score, Mini Nutritional Assessment (MNA) score, and Charlson’s Comorbidity Index (CCI) score were all associated with one-year mortality after discharge. When these parameters were dichotomized, we discovered that those who were aged ≥90 years, had a LOS ≥ 12 days, an MNA score < 17, a CCI ≥ 2, and a previous admission history were all independently associated with one-year mortality using multiple cox regression analyses. By applying individual scores to these risk factors, the area under the receiver operating characteristics curve (AUC) was 0.691 with a cut-off value score ≧ 3 for one year mortality, 0.801 for within 30-day mortality, and 0.748 for within 90-day mortality. It is suggested that older hospitalized patients with varying risks of mortality may be stratified by a prediction model, with tailored planning being subsequently implemented