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1.
Opt Express ; 32(10): 17911-17921, 2024 May 06.
Article in English | MEDLINE | ID: mdl-38858959

ABSTRACT

Conventional radar jamming and deception systems typically necessitate the custom design of complex circuits and algorithms to transmit an additional radio signal toward a detector. Consequently, they are often cumbersome, energy-intensive, and difficult to operate in broadband electromagnetic environment. With the ongoing trend of miniaturization of various devices and the improvement of radar system performance, traditional techniques no longer meet the requirements for broadband, seamless integration, and energy efficiency. Time-varying metasurfaces, capable of manipulating electromagnetic parameters in both temporal and spatial domains, have thus inspired many contemporary research studies to revisit established fields. In this paper, we introduce a time-varying metasurface driven radar jamming and deception system (TVM-RJD), which can perfectly overcome the aforementioned intrinsic challenges. Leveraging a programmable bias voltage, the TVM-RJD can alter the spectrum distribution of incident waves, thereby deceiving radar into making erroneous judgments about the target's location. Experimental outcomes affirm that the accuracy deviation of the TVM-RJD system is less than 0.368 meters, while achieving a remarkable frequency conversion efficiency of up to 96.67%. The TVM-RJD heralds the expansion into a wider application of electromagnetic spatiotemporal manipulation, paving the way for advancements in electromagnetic illusion, radar invisibility, etc.

2.
Int Heart J ; 65(1): 39-46, 2024.
Article in English | MEDLINE | ID: mdl-38296577

ABSTRACT

It is unclear whether the atherogenic index of plasma (AIP) is associated with major adverse cardiovascular events (MACEs) in the general population. A total of 361,644 participants (aged 56.19 ± 8.09 years; 44.79% male) free of a history of MACEs at baseline from the UK Biobank data were included in the analysis. The AIP was calculated using log (triglyceride/high-density lipoprotein-cholesterol). Over a mean follow-up of 12.19 ± 1.60 years, 16,683 participants developed MACEs. After adjustment for traditional risk factors, each 1 unit increase in AIP was associated with a 45.3% higher risk of incident MACEs (hazard ratio (HR), 1.453 [95% confidence interval (CI) 1.371-1.540], P < 0.001). Results were similar when individuals were categorized by the AIP quartiles (HR, 1.283 [95% CI 1.217-1.351]; comparing extreme quartiles). The subgroup analyses showed that the association between AIP and risk of incident MACEs was more obvious in female participants who are < 60 years old and free of hypertension or diabetes. Sensitivity analysis included participants without any lipid-lowering medication or excluded incident MACEs in the first 2 years of follow-up confirming the robustness of the findings. Elevated AIP is a risk factor of incident MACEs in the general population, independent of traditional risk factors.Dynamic monitoring of the AIP may help select the population at high risk of cardiovascular events and guide primary prevention.


Subject(s)
Atherosclerosis , Diabetes Mellitus , Hypertension , Humans , Male , Female , Middle Aged , Triglycerides , Risk Factors , Diabetes Mellitus/epidemiology
3.
Parasitol Res ; 122(10): 2451-2452, 2023 Oct.
Article in English | MEDLINE | ID: mdl-37555856

ABSTRACT

This case report describes a 62-year-old male fisherman who presented with persistent vomiting, headache, and behavior changes. Despite initial antibiotic and corticosteroid treatment, his condition worsened, leading to coma and subsequent death. Macro-genome sequencing of cerebrospinal fluid (CSF) revealed the presence of Naegleria fowleri infection, which had been missed during initial laboratory tests. The patient's exposure history included sea-swimming near Zhoushan Island.


Subject(s)
Amebiasis , Central Nervous System Protozoal Infections , Meningoencephalitis , Naegleria fowleri , Male , Humans , Middle Aged , Central Nervous System Protozoal Infections/diagnosis , Amebiasis/diagnosis , Swimming , Naegleria fowleri/genetics , Fatal Outcome , Seawater , Meningoencephalitis/diagnosis
4.
Water Sci Technol ; 87(1): 318-335, 2023 Jan.
Article in English | MEDLINE | ID: mdl-36640040

ABSTRACT

At present, the method of using coupled models to model different frequency subseries of precipitation series separately for prediction is still lacking in the research of precipitation prediction, thus in this paper, a coupled model based on Ensemble Empirical Mode Decomposition (EEMD), Long Short-Term Memory neural network (LSTM) and Autoregressive Integrated Moving Average (ARIMA) is proposed for month-by-month precipitation prediction. The monthly historical precipitation data of Luoyang City from 1973 to 2021 were used to build the model, and the modal components of different frequencies obtained by EEMD decomposition were divided into high-frequency series part and low-frequency series part using the Permutation Entropy (PE) algorithm, the LSTM model is used to predict the high-frequency sequence part, while the ARIMA model is used to predict the low-frequency sequence part. Monthly precipitation forecasts are obtained by superimposing the results of the two models. Finally, the predictive performance is evaluated using several assessment metrics. The indicators show that the model predictive performance outperforms the EMD-LSTM (Empirical Mode Decomposition), EEMD-LSTM, EEMD-ARIMA combined models and the single models, and the model has high confidence in the prediction results of future precipitation.


Subject(s)
Algorithms , Neural Networks, Computer , Forecasting , Entropy , Models, Statistical
5.
Water Sci Technol ; 88(4): 1015-1038, 2023 Aug.
Article in English | MEDLINE | ID: mdl-37651335

ABSTRACT

The accurate forecasting of precipitation in the upper reaches of the Yellow River is imperative for enhancing water resources in both the local and broader Yellow River basin in the present and future. While many models exist for predicting precipitation by analyzing historical data, few consider the impact of different frequency sequences on model accuracy. In this study, we propose a coupled monthly precipitation prediction model that leverages the adaptive noise complete ensemble empirical mode decomposition with adaptive noise (CEEMDAN), gated recurrent unit neural network (GRU), and attention mechanism-based transformer model. The permutation entropy (PE) algorithm is employed to partition the data processed by CEEMDAN into different frequencies, with different models utilized to predict different frequencies. The predicted results are subsequently combined to obtain the monthly precipitation prediction value. The model is applied to precipitation prediction in four regions in the upper reaches of the Yellow River and compared with other models. Evaluation results demonstrate that the CEEMDAN-GRU-Transformer model outperforms other models in predicting precipitation for these regions, with a coefficient of determination R2 greater than 0.8. These findings suggest that the proposed model provides a novel and effective method for improving the accuracy of regional medium and long-term precipitation prediction.


Subject(s)
Algorithms , Neural Networks, Computer , Entropy , Rivers , Water Resources
6.
J Neurochem ; 163(6): 500-516, 2022 12.
Article in English | MEDLINE | ID: mdl-35997641

ABSTRACT

Ischemic stroke is a major global health issue. Ischemia and subsequent reperfusion results in stroke-related brain injury. Previous studies have demonstrated that nuclear-enriched abundant transcript 1 (NEATa and early growth response 1 (EGR1) are involved in ischemia reperfusion (IR) injury). In this study, we aimed to explore the roles of NEAT1/EGR1 axis as well as its downstream effector RNA binding motif protein 25 (RBM25) in cerebral IR injury. Oxygen-glucose deprivation/reperfusion (OGD/R) and middle cerebral artery occlusion (MCAO) were used to establish in vitro and in vivo models of cerebral IR injury, respectively. According to our data, NEAT1, EGR1, and RBM25 levels were elevated in OGD/R-exposed SK-N-SH and SH-SY5Y cells and cerebral cortex of MCAO mice. NEAT1, EGR1, or RBM25 knockdown effectively reduced infarct volumes and apoptosis, and improved neurological function. Mechanistically, NEAT1 directly interacted with EGR1, which restrained WW domain containing E3 ubiquitin protein ligase 1 (WWP1)-mediated ubiquitination of EGR1 and subsequently caused EGR1 accumulation. EGR1 bound to RBM25 promoter and transcriptionally activated RBM25. Rescue experiments indicated that RBM25 overexpression abolished the therapeutic effects of NEAT1 knockdown. In conclusion, this work identified a novel NEAT1/EGR1/RBM25 axis in potentiating brain injury after IR insults, suggesting a potential therapeutic target for ischemic stroke.


Subject(s)
Brain Injuries , Brain Ischemia , Ischemic Stroke , MicroRNAs , Neuroblastoma , RNA, Long Noncoding , Reperfusion Injury , Humans , Mice , Animals , RNA, Long Noncoding/genetics , Reperfusion Injury/metabolism , Infarction, Middle Cerebral Artery , Oxygen/metabolism , Apoptosis/genetics , Glucose/metabolism , RNA-Binding Motifs , Brain Ischemia/metabolism , MicroRNAs/metabolism , Ubiquitin-Protein Ligases/metabolism
7.
Arthroscopy ; 38(2): 489-497.e17, 2022 02.
Article in English | MEDLINE | ID: mdl-34624500

ABSTRACT

PURPOSE: To rank Knee Injury and Osteoarthritis Outcome Score (KOOS) questions from most to least improvement after arthroscopic partial meniscectomy (APM) and compare improvement of meniscal versus mechanical symptoms. METHODS: A secondary analysis of the Chondral Lesions and Meniscus Procedures (ChAMP) Trial was performed. Inclusion criteria were age 30 years or older with degenerative meniscal tear failing nonoperative management, with or without associated unstable chondral lesions. No chondral debridement was performed. Responses to the 42 KOOS questions ranged from 0 (extreme problems) to 4 (no problems), and were answered preoperatively and at 1 year after isolated APM. The 1-year mean change, or delta (Δ), was calculated for each KOOS question and the Δ for meniscal and mechanical symptoms were statistically compared. RESULTS: Greatest improvement in 135 eligible patients was observed for questions about (1) awareness of knee problems (Δ = 1.93, standard deviation [SD] = 1.38), (2) frequency of knee pain (Δ = 1.93, SD = 1.29), (3) degree of difficulty while twisting/pivoting on the injured knee (Δ = 1.88, SD = 1.13), (4) degree of difficulty while running (Δ = 1.67, SD = 1.30), and (5) being troubled by lack of confidence in the knee (Δ = 21.67, SD = 1.11). Least improvement was observed for questions about: (1) degree of difficulty while getting on/off the toilet (Δ = 0.94, SD = 0.96), (2) feel grinding or hear clicking when the knee moves (Δ= 0.90, SD = 1.25), 3) degree of difficulty while getting in/out of the bath (Δ= 0.88, SD = 1.00), (4) knee catches/hangs up during movement (Δ= 0.80, SD = 1.09), and (5) the ability to straighten the knee fully (Δ= 0.54, 1.44). There was greater improvement for the KOOS questions pertaining to meniscal versus mechanical symptoms (P < .00001). CONCLUSIONS: KOOS symptoms as reported by subjects' responses to the questions pertaining to the frequency of knee pain, twisting/pivoting, running, squatting, and jumping showed the most improvement 1 year after isolated APM, whereas those relating to mechanical symptoms improved the least. Focusing on meniscal rather than mechanical symptoms may help surgeons better identify patients expected to benefit from APM. LEVEL OF EVIDENCE: IV, retrospective analysis of prospectively collected data.


Subject(s)
Meniscus , Tibial Meniscus Injuries , Adult , Arthroscopy/methods , Humans , Meniscectomy/methods , Menisci, Tibial/surgery , Retrospective Studies , Tibial Meniscus Injuries/complications , Tibial Meniscus Injuries/surgery
8.
Arthroscopy ; 38(3): 936-944, 2022 03.
Article in English | MEDLINE | ID: mdl-34265389

ABSTRACT

PURPOSE: To compare 5-year outcomes among patients with and without unstable chondral lesions undergoing arthroscopic partial meniscectomy (APM). METHODS: Using data from the Chondral Lesions And Meniscal Procedures (ChAMP) Trial, we compared outcomes for patients with unstable chondral lesions found at the time of APM and left in situ (CL-noDeb, N = 71) versus patients without unstable chondral lesions (NoCL, N = 47) at 5 years after APM. Outcomes included the Western Ontario and McMaster Universities Arthritis Index (WOMAC), Knee Injury and Osteoarthritis Outcome Score (KOOS), visual analog pain scale, Short-form Health Survey (SF-36), physical knee measurements, progressive joint space narrowing on radiographs, and the rate of additional knee surgery. Multivariate linear regression was used to obtain mean differences (MDs) with corresponding 95% confidence intervals (CIs) adjusted for age, body mass index, and preoperative score (for postoperative scores). RESULTS: Compared with CL-noDeb, NoCL subjects had significantly greater improvement at 5 years in the KOOS score for function in sport and recreation (MD = 9.9 [95% CI, 0.7-19.1]), SF-36 pain (MD = 13.9 [95% CI, 5.5-22.3]), knee extension (MD = 0.8 [95% CI, 0.1-1.5]), and decreased quadriceps circumference at the mid-portion of the patella (MD = -1.5 [95% CI, -2.7 to -0.3). A greater proportion of patients in the NoCL group achieved the MCID for all outcome scores except for the WOMAC pain score (89% CL-NoDeb vs 87% NoCL) and SF-36 general (29% CL-NoDeb vs 23% NoCL). There were no significant group differences in measures of progressive radiographic joint space narrowing in any compartments of the operative knee and no significant difference in the rate of additional knee surgery within 5 years of the initial APM. CONCLUSIONS: Patients undergoing APM without unstable chondral lesions had statistically significantly better outcomes than patients with unstable chondral lesions at 5 years after surgery; however, there were no group differences in progressive radiographic joint space narrowing. LEVEL OF EVIDENCE: Level II, prospective comparative study.


Subject(s)
Osteoarthritis, Knee , Tibial Meniscus Injuries , Arthroscopy/methods , Humans , Knee Joint/surgery , Meniscectomy/methods , Osteoarthritis, Knee/surgery , Prospective Studies , Quality of Life , Tibial Meniscus Injuries/etiology , Tibial Meniscus Injuries/surgery
9.
Int Ophthalmol ; 42(8): 2323-2333, 2022 Aug.
Article in English | MEDLINE | ID: mdl-35094230

ABSTRACT

PURPOSE: We describe a portable practice model for acquisition of microsurgical skills using widely available inexpensive tools and materials as a model in learning ophthalmic corneal suturing skills. METHODS: Interested participants without prior microsurgery experience affiliated with the Jacobs School of Medicine and Biomedical Sciences with no prior microsurgical experience qualified to participate. Each participant completed written informed consent. We developed a 3-dimensional micro-stellated icosahedron model using microtubules, monofilament fishing line, jewelers' forceps, and a basic laboratory dissection microscope. We tested this model in improving microsurgical skills in a randomized, controlled intervention trial. Following a pre-assessment task of passing a microsurgical needle and performing a tie, participants were randomized to a control or an intervention (building the micro-stellated icosahedrons) group. The assessment task was repeated after two weeks. Videos of pre- and post-assessments were rated by two masked ophthalmologists. Technique scores and time to complete microsurgical tasks were analyzed to determine improvement in skills. RESULTS: A total of 27 microsurgically naïve participants were recruited and randomized (14 Intervention / 13 Control). Comparing pre- and post-assessments, the intervention group showed significant decrease in time required to pass the needle (P = 0.018) and significant improvement in technical scores. (P = 0.001). In the control group, there was no significant decrease in time or improvement in technical scores. CONCLUSIONS: The portable inexpensive micro-stellated icosahedron skills acquisition model is an effective practice model to acquire skills necessary to perform a microsurgical tie. The similarity in dimensions between the model and the eye suggests translatability to ophthalmic surgery.


Subject(s)
Microsurgery , Models, Educational , Ophthalmology , Clinical Competence , Humans , Microsurgery/education , Ophthalmology/education
10.
J Nutr ; 151(6): 1618-1627, 2021 06 01.
Article in English | MEDLINE | ID: mdl-33982106

ABSTRACT

BACKGROUND: Prospective evidence on associations between diet quality indices and lung cancer risk is limited, particularly among older women. OBJECTIVES: We investigated associations between 4 diet quality indices [Healthy Eating Index-2015 (HEI-2015), Alternate Healthy Eating Index 2010 (AHEI-2010), alternate Mediterranean Diet (aMED), and Dietary Approaches to Stop Hypertension (DASH)] and lung cancer incidence and mortality in the Women's Health Initiative Observational Study. METHODS: Postmenopausal women aged 50-79 y at baseline (1993-1998) self reported their diet intake and information on relevant covariates. We used Cox proportional hazards regression models to estimate HRs and 95% CIs after controlling for age, smoking, and other relevant covariates. RESULTS: During ∼17 y of follow-up among 86,090 participants, 1491 lung cancer cases and 1393 lung cancer deaths were documented. Dietary indices were not associated with overall lung cancer incidence but were protective against squamous cell carcinoma (12.8% of total lung cancer) cases (HEI-2015: HR: 0.85; 95% CI: 0.76, 0.96; AHEI-2010: HR: 0.87; 95% CI: 0.78, 0.98; aMED: HR: 0.90; 95% CI: 0.81, 0.99; DASH: HR: 0.87; 95% CI: 0.77, 0.98). Among the indices, only HEI-2015 showed an inverse trend (P-trend = 0.02) with overall lung cancer mortality. Smoking status or participant age at baseline did not modify the association between dietary indices and lung cancer incidence or mortality. CONCLUSIONS: After comprehensive control of smoking exposure, we found that diet quality was not associated with overall lung cancer among postmenopausal women. However, a high-quality diet was inversely related to incident lung cancer of the squamous cell subtype. Future studies in populations with diverse age, smoking history, and dietary intake may further elucidate the relation between diet quality indices and lung cancer, especially by histological subtype.


Subject(s)
Diet , Lung Neoplasms , Aged , Female , Humans , Lung Neoplasms/epidemiology , Middle Aged , Postmenopause , Proportional Hazards Models , Prospective Studies , Women's Health
11.
Analyst ; 146(24): 7627-7634, 2021 Dec 06.
Article in English | MEDLINE | ID: mdl-34787597

ABSTRACT

Peroxynitrite (ONOO-), a highly reactive oxygen species (ROS), is implicated with many physiological and pathological processes including cancer, neurodegenerative diseases and inflammation. In this regard, developing effective tools for highly selective tracking of ONOO- is urgently needed. Herein, we constructed a concise and specific fluorescent probe NA-ONOO for sensing ONOO- by conjugating an ONOO--specific recognition group ((4-methoxyphenylthio)carbonyl, a thiocarbonate derivative) with a naphthalene fluorophore. The probe, NA-ONOO, was in a dark state because the high electrophilicity of (4-methoxyphenylthio)carbonyl disturbs the intramolecular charge transfer (ICT) in the fluorophore. Upon treatment with ONOO-, the fluorescent emission was sharply boosted (quantum yield Φ: 3% to 56.6%) owing to an ONOO- triggered release of (4-methoxyphenylthio)carbonyl from NA-ONOO. Optical analyses showed that NA-ONOO presented high selectivity and sensitivity toward ONOO-. With good cell permeability and biocompatibility, the NA-ONOO probe was successfully applied to imaging and tracing exogenous and endogenous ONOO- in living cells and zebrafish. The probe NA-ONOO presents a new recognition group and a promising method for further investigating ONOO- in living systems.


Subject(s)
Fluorescent Dyes , Peroxynitrous Acid , Animals , Fluorescent Dyes/toxicity , Zebrafish
12.
J Strength Cond Res ; 35(5): 1338-1344, 2021 May 01.
Article in English | MEDLINE | ID: mdl-33651739

ABSTRACT

ABSTRACT: Gannon, EA, Higham, DG, Gardner, BW, Nan, N, Zhao, J, and Bisson, LJ. Changes in neuromuscular status across a season of professional men's ice hockey. J Strength Cond Res 35(5): 1338-1344, 2021-To quantify changes in neuromuscular function over a full professional men's ice hockey season, 27 players (n = 18 forwards and 9 defensemen) performed 3 countermovement jumps (CMJ) each week over 30 sessions separated into 4 phases: preseason, early-season, midseason, and late-season. Outcome variables represented jump performance (jump height), kinematics (mean velocity and peak velocity), and movement strategy (countermovement depth). Mixed models characterized relationships between positional group, season phase, and CMJ outcomes. Statistical significance was set at p ≤ 0.05. Concentric peak velocity (p = 0.02), jump height (p = 0.001), and countermovement depth (p < 0.001) displayed a significant reduction across the season. Peak velocity was lower during the early-season than the preseason (-0.10 ± 0.06 m·s-1, mean change ± 95% confidence limit, p = 0.05). Countermovement depth was reduced during the early-season (-0.06 ± 0.03 m, p = 0.02), midseason (-0.10 ± 0.04 m, p = 0.002), and late-season (-0.15 ± 0.04 m, p < 0.001) relative to the preseason. Reductions in CMJ variables from preseason to in-season ranged from trivial to large. Changes in countermovement depth differed for forwards and defensemen by the season phase (p = 0.04). A professional ice hockey season decreases CMJ performance, with the effects of fatigue most prominent during the late-season phase. Countermovement depth was most sensitive to fatigue and differentiated positional-group responses. Frequent CMJ testing is useful for identifying the neuromuscular status of team-sport athletes relative to season-specific phases. Fatigue monitoring should incorporate movement-strategy variables alongside traditional measures of performance and kinematics.


Subject(s)
Athletic Performance , Hockey , Athletes , Humans , Male , Muscle Fatigue , Seasons
13.
Entropy (Basel) ; 22(10)2020 Oct 14.
Article in English | MEDLINE | ID: mdl-33286923

ABSTRACT

We study how to conduct statistical inference in a regression model where the outcome variable is prone to missing values and the missingness mechanism is unknown. The model we consider might be a traditional setting or a modern high-dimensional setting where the sparsity assumption is usually imposed and the regularization technique is popularly used. Motivated by the fact that the missingness mechanism, albeit usually treated as a nuisance, is difficult to specify correctly, we adopt the conditional likelihood approach so that the nuisance can be completely ignored throughout our procedure. We establish the asymptotic theory of the proposed estimator and develop an easy-to-implement algorithm via some data manipulation strategy. In particular, under the high-dimensional setting where regularization is needed, we propose a data perturbation method for the post-selection inference. The proposed methodology is especially appealing when the true missingness mechanism tends to be missing not at random, e.g., patient reported outcomes or real world data such as electronic health records. The performance of the proposed method is evaluated by comprehensive simulation experiments as well as a study of the albumin level in the MIMIC-III database.

14.
Alzheimer Dis Assoc Disord ; 33(2): 124-128, 2019.
Article in English | MEDLINE | ID: mdl-31094709

ABSTRACT

PURPOSE: The aim of this study was to evaluate the relationship between olfactory function and hippocampal volume in patients with mild cognitive impairment (MCI). METHODS: We enrolled a total of 31 MCI patients and 9 normal control subjects. All participants underwent 3.0 T-magnetic resonance imaging scanning. The scan results were processed using GE ADW4.6 processing software and V0xar 3D workstation to acquire the hippocampal volume. The University of Pennsylvania Smell Identification Test (UPSIT) was used to evaluate the olfactory function of MCI patients. The correlations of UPSIT score with hippocampal volume and hippocampal head volume were evaluated by Pearson correlation coefficient analysis. RESULTS: MCI patients had significantly smaller left (2.78±0.50 vs. 3.19±0.31 cm(3)) and right (2.97±0.42 vs. 3.31±0.25 cm(3)) hippocampal volumes compared with normal controls (P<0.05). In addition, patients with olfactory dysfunction had smaller volumes of the hippocampus (left hippocampal volume, 2.57±0.39 vs. 3.23±0.40 cm(3); right hippocampal volume, 2.86±0.43 vs. 3.22±0.30 cm(3)) and hippocampal head (left hippocampal head volume, 1.18±0.16 vs. 1.53±0.25 cm(3); right hippocampal head volume, 1.25±0.22 vs. 1.54±0.22 cm(3)) compared with those with normal olfactory function (P<0.05). No significant difference in the hippocampal body volume and hippocampal tail volume was found between MCI patients with olfactory loss and those with normal olfactory function. The UPSIT score was significantly positively correlated with left hippocampal volume (r=0.55, P<0.05), right hippocampal volume (r=0.42, P<0.05), left hippocampal head volume (r=0.53, P<0.05), and right hippocampal head volume (r=0.45, P<0.05). CONCLUSIONS: Olfactory function correlates well with hippocampal volume among patients with MCI.


Subject(s)
Cognitive Dysfunction/physiopathology , Hippocampus/physiopathology , Image Processing, Computer-Assisted , Olfaction Disorders , Aged , Case-Control Studies , China , Female , Humans , Magnetic Resonance Imaging , Male , Middle Aged , Smell/physiology
15.
J Nonparametr Stat ; 31(4): 911-931, 2019.
Article in English | MEDLINE | ID: mdl-33013146

ABSTRACT

Nonignorable missing-data is common in studies where the outcome is relevant to the subject's behavior. Ibrahim et al. (2001) fitted a logistic regression for a binary outcome subject to nonignorable missing data, and they proposed to replace the outcome in the mechanism model with an auxiliary variable that is completely observed. They had to correctly specify a model for the auxiliary variable; unfortunately the outcome variable subject to nonignorable missingness is still involved. The correct specification of this model is mysterious. Instead, we propose two unconventional likelihood based estimation procedures where the nonignorable missingness mechanism model could be completely bypassed. We apply our proposed methods to the children's mental health study and compare their performance with existing methods. The large sample properties of the proposed estimators are rigorously justified, and their finite sample behaviors are examined via comprehensive simulation studies.

16.
J Clin Microbiol ; 56(10)2018 10.
Article in English | MEDLINE | ID: mdl-30045868

ABSTRACT

Little is known about interactions between nontypeable Haemophilus influenzae, Moraxella catarrhalis, Streptococcus pneumoniae, and Pseudomonas aeruginosa in the lower respiratory tract in chronic obstructive pulmonary disease (COPD) patients. We characterized colonization by these four bacterial species, determined species-specific interactions, and estimated the effects of host factors on bacterial colonization among COPD patients. We conducted a prospective cohort study in veterans with COPD that involved monthly clinical assessment and sputum cultures with an average duration of follow-up of 4.5 years. Cultures were used for bacterial identification. We analyzed bacterial interactions using generalized linear mixed models after controlling for clinical and demographic variables. The outcomes of interest were the relationships between bacteria based on clinical status (stable or exacerbation). One hundred eighty-one participants completed a total of 8,843 clinic visits, 30.8% of which had at least one of the four bacteria isolated. H. influenzae was the most common bacterium isolated (14.4%), followed by P. aeruginosa (8.1%). In adjusted models, S. pneumoniae colonization was positively associated with H. influenzae colonization (odds ratio [OR], 2.79; 95% confidence interval [CI], 2.03 to 3.73). We identified negative associations between P. aeruginosa and H. influenzae (OR, 0.15; 95% CI, 0.10 to 0.22) and P. aeruginosa and M. catarrhalis (OR, 0.51; 95% CI, 0.35 to 0.75). Associations were similar during stable and exacerbation visits. Recent antimicrobial therapy was associated with a lower prevalence of S. pneumoniae, H. influenzae, and M. catarrhalis, but not P. aeruginosa Our findings support the presence of specific interspecies interactions between common bacteria in the lower respiratory tracts of COPD patients. Further work is necessary to elucidate the mechanisms of these complex interactions that shift bacterial species.


Subject(s)
Bacteria/growth & development , Microbial Interactions , Pulmonary Disease, Chronic Obstructive/microbiology , Sputum/microbiology , Aged , Bacteria/metabolism , Female , Haemophilus influenzae/isolation & purification , Humans , Longitudinal Studies , Male , Middle Aged , Moraxella catarrhalis/isolation & purification , Prospective Studies , Pseudomonas aeruginosa/isolation & purification , Pulmonary Disease, Chronic Obstructive/pathology , Streptococcus pneumoniae/isolation & purification
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