Multilevel functional principal component analysis

The Sleep Heart Health Study (SHHS) is a comprehensive landmark study of sleep and its impacts on health outcomes. A primary metric of the SHHS is the in-home polysomnogram, which includes two electroencephalographic (EEG) channels for each subject, at two visits. The volume and importance of this data presents enormous challenges for analysis. To address these challenges, we introduce multilevel functional principal component analysis (MFPCA), a novel statistical methodology designed to extract core intra- and inter-subject geometric components of multilevel functional data. Though motivated by the SHHS, the proposed methodology is generally applicable, with potential relevance to many modern scientific studies of hierarchical or longitudinal functional outcomes. Notably, using MFPCA, we identify and quantify associations between EEG activity during sleep and adverse cardiovascular outcomes.Comment: Published in at http://dx.doi.org/10.1214/08-AOAS206 the Annals of Applied Statistics (http://www.imstat.org/aoas/) by the Institute of Mathematical Statistics (http://www.imstat.org

A Unique Approach for Planar Parallel Robotic Arms

In the design of mechanism, a decision must first be taken regarding the type of mechanism to be employed. The number of links and connections required to give the desired degree of freedom must then be determined. Finally, the required dimensions needed to bring about a particular motion must be deduced. In the present study the main focus is to select a mechanism for parallel robotic arms. However there are a number of mechanisms available which can be used as robot hands. In the selection of mechanism for robotic hands, rigidity and grasping power are the main important considerations. In the present paper, a unique numerical method is used to measure the parallelism between the object and the ground link. This can be used to compare the robotic hands for rigidity and grasp

Infeksi Nosokomial Saluran Kencing (Insk) di Rumah Sakit Khusus Penyakit Menular, Jakarta

A prospective survey to establish the incidence of urinary tract nosocomial infection (UTNI) was conducted at the Infectious Diseases Hospital of Jakarta for one year duration in 1982-1983. The study was done by taking random samples from patients hospitalized for longer than 2 days through urine cultures on day 1, 3 and 7 and other necessary examination. From 2288 patients hospitalized during that period, 723 patients (aged 2 months-70 years) met the requirement to be included in the study, and 115 (15.9%) of them met the criteria for UTNI. Female patients had higher rate of UTNI compared to male patients (19.8% vs 12.4%). The age group with highest rate of UTNI was children with < 1 year of age and the rate of UTNI decreased as the age of patients increased. Febrile patients had significantly higher rate of UTNI compared to diarrhea patients (33.4% vs 2,4%, p < 0.001). Patients who had catheterization had significantly higher rate of UTNI compared to patients without catheter placement (85.7% vs 12.3% p <0.05). Antibiotics treatment prior to hospitalization was associated with higher rate of UTNI compared to patients without it (22.8% vs 12.6% p < 0.01) as it was also observed with hospitalization for 7 days or longer (15.8% vs 11.9%) of it is compared to shorter duration of hospitalization. Gram negative bacterias were the most commonly recovered from the urine cultures compared to gram positive (89.8% vs 10.2%) with E. coli (24.2%) as the leading organism. Other recovered organism, Proteus spp and Citrobacter bacilli showed high resistancy toward antibiotics commonly used in the hospital. Average duration of hospitalization for patients with UTNI (9.6 days) was longer compared to average duration for patients without UTNI (4.4 days). Six out of 115 patients with UTNI died (5.2%) compared to only 1.3% mortality in patients without UTNI. No single factor was significantly shown to be responsible for higher mortality rate of patients with UTNI, possibly was due to more severe condition of underlying disease of patients with UTNI

Infeksi Komunitas (Ik)/infeksi Luar Rumah Sakit (Ilrs) (Community Acquired Infection) di Rumah Sakit Khusus Penyakit Menular, Jakarta

A one year prospective study was conducted at the Infectious Diseases Hospital (IDH) of Jakarta in 1982-1983 to survey the rate of community acquired infection (CAI). Blood culture, rectal swab, urine culture and in some patients cerebro spinal fluid culture were obtained randomly from hospitalized patient at the time of admission. From 723 patients with age 2 months-70 years, who were examined and fulfilled the study criteria, 504 (69,7%) patients were positive for CAI resulted in total of 611 CAIs. Based on anatomical location, this number consists of 53.5% CAI of GI Tract, 20.9% CAI of Urinary Tract, 9.5% CAI bacteremia and 0.6% CAI involving central nervous system. Incidence rate was significantly higher in female (74.1%) compared to male (65.7%) (p12 years patients (73.9%) compared to children <12 years (p<0,01). Diarrhea patients had significantly higher CAI (77.4%) compared to febrile patients (55.2%) (p<0,01). Patients who had not received antibiotic prior to admission had higher rate of CAI (70.9%) compared to who received it prior to admission (67.1%) Etiologic agents most commonly recovered were gram negative bacterias (94.9%) with Vibrio cholerae (48.6%) as the leading cause, and only 5.1% were gram positive. Some of bacteria found as the etiologic agent of CAI, were Salmonella group D, Salmonella group E4, Proteus vulgaris and ruttgerii, Klebsiella pneumoniae, Mima polymorpha, Alkaligenes sp showed high rate of resistancy to commonly used antibiotics. (Ampicillin, Tetracycline, Chloramphenicol and Trimethoprim + Sulfamethoxazole). Average duration of hospitalization for CAI cases (6,4 days) was longer than in cases without CAI (4,3 days). There were 11 deaths (2.2%) in cases with CAI and 2 deaths (1.4%) in patients without CAI, with death rate was higher in males (2.4%) compared to female (1.9%), and highest was in less than 1 year old age group patient (13.6%), also significantly higher in febrile patients compared to diarrhea patients (7.2% vs 0.3%, p< 0.001). The higher mortality rate in CAI is due to more severe condition of underlying disease of patients who had CAI

Infeksi Nosokomial Saluran Nafas Bawah (Insnb) di Rumah Sakit Khusus Penyakit Menular, Jakarta

A prospective study to determine the incidence of lower respiratory tract nosocomial infection (LRNI) was conducted at the Infectious Diseases Hospital of Jakarta (IDH) in 1982-1983 for one year duration. Samples were taken randomly from 2 group of hospitalized patients: diarrheal and febrile patients. The criteria for development of lower respiratory infection were based on history, physical examination and chest x-ray examination, which was done only Li some of the patients those with duration of hospitalization &gt;2 days. From 2288 patients hospitalized during that period,723 (31.6%) patients fulfilled the criteria to be included in the nosocomial study, and from this group 34 (4.7%) of them met the criteria for LRNI. The LRNI was observed in almost similar percentage in both sexes of patients (4.5% in males and 4.9% in females). Comparison of different age group of patients showed that 5-11 years old children had highest rate of LRNI (14,5%) and significantly (p&lt;0,01) compare to &gt; 12 years old followed by children 1-4 year old (7,1%), while children &lt;1 year had 5.9%, and the lowest rate was in &gt; 12 years group with 2.7% Febrile patients had significantly higher rate of LRNI compared to diarrhea patients (11.6% vs 1.1%; p&lt; 0,001). Patients who received oxygen and bronchial mucus suction had significantly higher rate of LRNI (27.4%) vs 3.1%; p&lt;0,001) compared to those who did not (3,1%, p&lt; 0,001). Average duration of hospitalization for patients with LRNI was longer than for patients without it (11.1 vs 5.1 days). Case fatality rate in patients with LRNI was also higher 17.7%, compared only 1.2% in patients without LRNI. Factors involved in CFR was mostly due to severity of underlying disease and respiratory failure due to pneumonia in patients who developed LRNI

Pencemaran Jarum Infus Intervena (IV) di Rumah Sakit Khusus Penyakit Menular, Jakarta

A prospective survey to evaluate rate of intravenous needle contamination was conducted at Infectious Diseases Hospital of Jakarta among patients whom received intravenous (i.v.) fluid or transfusion during 1 year period in 1982-1983. The survey was conducted through random culture of the distal part of the intravenous needle placed in the patients vein after completion of intravenous treatment. The exact time for the needle placement and extraction, local and systemic reactions observed in patients, were all recorded. From 559 culture of the i.v. needles which fulfilled the survey criteria, 238 were positive, indicating 42.3% contamination rate of the i.v. needles. The rate was higher in febrile patients (47.2%) compared to diarrhea patients (41.5%) Average duration of infusion (the duration of time the needle stayed in the vein) was 38.9 hours, with average of 15.8 hours in diarrhea patients and 104,6 hours in febrile patients. Mean duration of time for local reaction development was 36.8 hours, with 24.3 hours in diarrhea patients and 65.9 hours in febrile patients. Patients with positive culture had higher rate of local reaction (17.6% vs 13.4%), systemic reaction (18.4% vs 11.8%), nosokomial bacteremia (88% vs 4,4%) and community acquired infection (5.9% vs 3.7%) compared to patients with negative cultures. For patients with longer than 48 hours infusion, 58.5% had positive culture from i.v. needles, 21.9% had local reaction, 40.2% had systemic reaction which all were higher compared to patients who had less than 48 hour infusion with p&lt;0.001, p&lt;0.02 and p&lt;0.001 respectively. Isolated bacteria from i.v. needles were 74.6% gram positive bacterias and 25.4% gram negative, with Staphylococcus epidermidis (38%) as the leading positive culture. Isolated bacteria had high rate of resistancy \u27oward commonly used antibiotics in the hospital

Pencemaran Kuman di Lingkungan Rumah Sakit Khusus Penyakit Menular, Jakarta

A survey to establish environmental contamination was conducted at the Infectious Diseases Hospital (IDH) of Jakarta by taking swabs from 90 hospital personnels who are directly involved in patients care. These swabs were taken from their hands, nails, throat and rectum. Swabs and cultures were also obtained from 167 equipments, solid and liquid material, food from the hospital, and the air in the hospital wards. From total of 437 specimen obtained, 73.7% showed presence contaminated result. There was 100% positive culture result noted in hands and nails swabs, 94.8% culture positive for any microorganism result was obtained from throat swabs while rectal swab indicated only 4.4% rate of contamination. Results of 167 swabs from material/equipments in the hospital, showed that 85.1% of them were not sterile, this included 59.1% of 54 liquid material, 37.3% from 35 liquid material which were supposed to be sterile, 100% positive culture of 17 liquid material specimen that were supposed to be clean. From solid materials 66.7% of 51 specimen were not sterile. This included 76.2% from 21 specimen that were supposed to be sterile, and 100% from 7 specimen that supposed to be clean. Also 100% non sterility was obtained from 23 other material and 62 equipment. Recovered bacterias consisted of both gram positive and negative bacterias and almost all of them represented normal human flora. Some of them potentially could became pathogen including pathogen for nosocomial infection. From the hospital personnels hand swabs, 25.4% were spore-forming bacteria and from the throat swabs 46.7% yielded Streptococcus ~ hemolyticus, and 4.4% were positive for coliform bacteria from rectal swabs. Results of material and equipment showed majority of aerobic rods (31.5%). Some of the bacteria recovered, including Pseudomonas aeruginosa and Enterobacter aerogenes were resistant to commonly used antibiotics in the hospital (Ampicillin, Tetracycline and Chloramphenicol)

AN OVERVIEW OF OBSERVATIONAL SLEEP RESEARCH WITH APPLICATION TO SLEEP STAGE TRANSITIONING

In this manuscript we give an overview of observational sleep research with a particular emphasis on sleep stage transitions. Sleep states represent a categorization of sleep electroencephalogram behavior over the night. We postulate that the rate of transitioning between sleep states is an important predictor of health. This claim is evaluated by comparing subjects with sleep disordered breathing to matched controls

Modeling multilevel sleep transitional data via Poisson log-linear multilevel models

This paper proposes Poisson log-linear multilevel models to investigate population variability in sleep state transition rates. We specifically propose a Bayesian Poisson regression model that is more flexible, scalable to larger studies, and easily fit than other attempts in the literature. We further use hierarchical random effects to account for pairings of individuals and repeated measures within those individuals, as comparing diseased to non-diseased subjects while minimizing bias is of epidemiologic importance. We estimate essentially non-parametric piecewise constant hazards and smooth them, and allow for time varying covariates and segment of the night comparisons. The Bayesian Poisson regression is justified through a re-derivation of a classical algebraic likelihood equivalence of Poisson regression with a log(time) offset and survival regression assuming piecewise constant hazards. This relationship allows us to synthesize two methods currently used to analyze sleep transition phenomena: stratified multi-state proportional hazards models and log-linear models with GEE for transition counts. An example data set from the Sleep Heart Health Study is analyzed

LASAGNA PLOTS: A SAUCY ALTERNATIVE TO SPAGHETTI PLOTS

Longitudinal repeated measures data has often been visualized with spaghetti plots for continuous out- comes. For large datasets, this often leads to over-plotting and consequential obscuring of trends in the data. This is primarily due to overlapping of trajectories. Here, we suggest a framework called lasagna plot ting that constrains the subject-specific trajectories to prevent overlapping and utilizes gradients of color to depict the outcome. Dynamic sorting and visualization is demonstrated as an exploratory data analysis tool. Supplemental material in the form of sample R code additional illustrated examples are available online