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Search Results: 1 - 10 of 235904 matches for " Robert L Wong "
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Sexual Display and Mate Choice in an Energetically Costly Environment
Megan L. Head,Bob B. M. Wong,Robert Brooks
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0015279
Abstract: Sexual displays and mate choice often take place under the same set of environmental conditions and, as a consequence, may be exposed to the same set of environmental constraints. Surprisingly, however, very few studies consider the effects of environmental costs on sexual displays and mate choice simultaneously. We conducted an experiment, manipulating water flow in large flume tanks, to examine how an energetically costly environment might affect the sexual display and mate choice behavior of male and female guppies, Poecilia reticulata. We found that male guppies performed fewer sexual displays and became less choosy, with respect to female size, in the presence of a water current compared to those tested in still water. In contrast to males, female responsive to male displays did not differ between the water current treatments and females exhibited no mate preferences with respect to male size or coloration in either treatment. The results of our study underscore the importance of considering the simultaneous effects of environmental costs on the sexual behaviors of both sexes.
Combining Likelihood Information from Independent Investigations  [PDF]
L. Jiang, A. Wong
Open Journal of Statistics (OJS) , 2015, DOI: 10.4236/ojs.2015.51007
Abstract: Fisher [1] proposed a simple method to combine p-values from independent investigations without using detailed information of the original data. In recent years, likelihood-based asymptotic methods have been developed to produce highly accurate p-values. These likelihood-based methods generally required the likelihood function and the standardized maximum likelihood estimates departure calculated in the canonical parameter scale. In this paper, a method is proposed to obtain a p-value by combining the likelihood functions and the standardized maximum likelihood estimates departure of independent investigations for testing a scalar parameter of interest. Examples are presented to illustrate the application of the proposed method and simulation studies are performed to compare the accuracy of the proposed method with Fisher’s method.
A Chi-Square Approximation for the F Distribution  [PDF]
L. Jiang, Augustine Wong
Open Journal of Statistics (OJS) , 2018, DOI: 10.4236/ojs.2018.81010
Abstract: F distribution is one of the most frequently used distributions in statistics. For example, it is used for testing: equality of variances of two independent normal distributions, equality of means in the one-way ANOVA setting, overall significance of a normal linear regression model, and so on. In this paper, a simple chi-square approximation for the cumulative distribution of the F-distribution is obtained via an adjusted log-likelihood ratio statistic. This new approximation exhibits remarkable accuracy even when the degrees of freedom of the F distribution are small.
A Screen for Selective Killing of Cells with Chromosomal Instability Induced by a Spindle Checkpoint Defect
Zeeshan Shaukat, Heidi W. S. Wong, Shannon Nicolson, Robert B. Saint, Stephen L. Gregory
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0047447
Abstract: Background The spindle assembly checkpoint is crucial for the maintenance of a stable chromosome number. Defects in the checkpoint lead to Chromosomal INstability (CIN), which is linked to the progression of tumors with poor clinical outcomes such as drug resistance and metastasis. As CIN is not found in normal cells, it offers a cancer-specific target for therapy, which may be particularly valuable because CIN is common in advanced tumours that are resistant to conventional therapy. Principal Findings Here we identify genes that are required for the viability of cells with a CIN phenotype. We have used RNAi knockdown of the spindle assembly checkpoint to induce CIN in Drosophila and then screened the set of kinase and phosphatase genes by RNAi knockdown to identify those that induce apoptosis only in the CIN cells. Genes identified include those involved in JNK signaling pathways and mitotic cytoskeletal regulation. Conclusions/Significance The screen demonstrates that it is feasible to selectively kill cells with CIN induced by spindle checkpoint defects. It has identified candidates that are currently being pursued as cancer therapy targets (e.g. Nek2: NIMA related kinase 2), confirming that the screen is able to identify promising drug targets of clinical significance. In addition, several other candidates were identified that have no previous connection with mitosis or apoptosis. Further screening and detailed characterization of the candidates could potentially lead to the therapies that specifically target advanced cancers that exhibit CIN.
Psychometric characteristics of the short form 36 health survey and functional assessment of chronic illness Therapy-Fatigue subscale for patients with ankylosing spondylitis
Dennis A Revicki, Anne M Rentz, Michelle P Luo, Robert L Wong
Health and Quality of Life Outcomes , 2011, DOI: 10.1186/1477-7525-9-36
Abstract: We analyzed clinical and patient-reported outcome (PRO) data collected during 12-week, double-blind, placebo-controlled periods of two randomized controlled trials comparing adalimumab and placebo for the treatment of active AS. The Bath Ankylosing Spondylitis Disease Activity Index, Bath Ankylosing Spondylitis Functional Index, and other clinical measures were collected during the clinical trial. We evaluated internal consistency/reliability, construct validity, and responsiveness to change for the SF-36 and FACIT-Fatigue.The SF-36 (Cronbach alpha, 0.74-0.92) and FACIT-Fatigue (Cronbach alpha, 0.82-0.86) both had good internal consistency/reliability. At baseline, SF-36 and FACIT-Fatigue scores correlated significantly with Ankylosing Spondylitis Quality of Life scores (r = -0.36 to -0.66 and r = -0.70, respectively; all p < 0.0001). SF-36 scores varied by indicators of clinical severity, with greater impairment observed for more severe degrees of clinical activity (all p < 0.0001). FACIT-Fatigue scores correlated significantly with SF-36 scores (r = 0.42 to 0.74; all p < 0.0001) and varied by clinical severity (p < 0.05 to p < 0.0001).The SF-36 is a reliable, valid, and responsive measure of health-related quality of life and the FACIT-Fatigue is a brief and psychometrically sound measure of the effects of fatigue on patients with AS. These PROs may be useful in evaluating effectiveness of new treatments for AS.ClinicalTrials.gov: NCT00085644 and NCT00195819Ankylosing spondylitis (AS) is a chronic and progressive inflammatory disorder that primarily affects the axial skeleton, sacroiliac joints of the pelvis, and thoracic cage [1,2]. Patients experience pain, joint stiffness, and the eventual loss of spinal mobility with disease progression. Patients with AS frequently experience impaired physical function and well-being, require time away from work because of disability, and suffer from diminished health-related quality of life (HRQOL) [3-7]. The impact of AS on
Feasibility, acceptability, and cost of tuberculosis testing by whole-blood interferon-gamma assay
Puneet Dewan, Jennifer Grinsdale, Sally Liska, Ernest Wong, Robert Fallstad, L Masae Kawamura
BMC Infectious Diseases , 2006, DOI: 10.1186/1471-2334-6-47
Abstract: Patients seen at six community clinics serving homeless, immigrant, or injection-drug user (IDU) populations were routinely offered IGRA (Quantiferon-TB). Per guidelines, we excluded patients who were <17 years old, HIV-infected, immunocompromised, or pregnant. We reviewed medical records for IGRA results and completion of medical evaluation for TB, and at two clinics reviewed TB screening logs for instances of IGRA refusal or phlebotomy failure.Between November 1, 2003 and February 28, 2005, 4143 persons were evaluated by IGRA. 225(5%) specimens were not tested, and 89 (2%) were IGRA-indeterminate. Positive or negative IGRA results were available for 3829 (92%). Of 819 patients with positive IGRA results, 524 (64%) completed diagnostic evaluation within 30 days of their IGRA test date. Among 503 patients eligible for IGRA testing at two clinics, phlebotomy was refused by 33 (7%) and failed in 40 (8%). Including phlebotomy, laboratory, and personnel costs, IGRA use cost $33.67 per patient tested.IGRA implementation in a routine TB control program setting was feasible and acceptable among homeless, IDU, and immigrant patients in San Francisco, with results more frequently available than the historically described performance of TST. Laboratory-based diagnosis and surveillance for M. tuberculosis infection is now possible.Providers in the United States and Europe have for many years relied on the tuberculin skin test (TST) to detect infection with Mycobacterium tuberculosis in patients. The limitations of the TST are well documented, including placement variability, inter-reader variability, boosting, and difficulty in interpreting results in patients previously vaccinated with bacille Calmette Guerin (BCG) or with non-tuberculosis mycobacterial (NTM) infection. [1,2] Patients may find the test inconvenient because they must return in 48–72 hours for result reading and interpretation. TST use poses operational challenges, such as the training and retraining of numerou
Comparison of Measured Vs. Modeled TE and TM Field Penetration Into a Slotted Circular Cylinder
Marsellas L. Waller;Thomas H. Shumpert;Robert W. Scharstein;Steven H. Wong
PIER B , 2011, DOI: 10.2528/PIERB10113006
Abstract: In implementing electromagnetic vulnerability (EMV) testing on operational helicopters fielding a variety of avionic, communication, and weapons systems, the testing levels as spelled out in MIL-STD-464A require most test labs to position the high power source antennas unreasonably close to the test item (sometimes within 2 m). Questions naturally arise concerning the efficacy of such testing with respect to both the manner of coupling of the fields to the helicopter systems as well as the levels required to achieve reasonable confidence in the coupling effects. This paper presents a comparison of the electric fields interior to an axially slotted circular cylinder and the fields in the slot aperture as a function of the distance from the source to the test item. Also, these measured interior and aperture fields are compared to two different mathematical/numerical models of the conducting cylinder with an axial slot running the length of the cylinder. Additional measurements are presented for the fields interior to a finite cylinder with conducting endcaps and a significantly reduced slot of finite length. Comparisons to one of the mathematical/numerical models for this finite length cylinder with finite length slot are presented also.
Perioperative morbidity and mortality of cardiothoracic surgery in patients with a do-not-resuscitate order
Bryan G. Maxwell,Robert L. Lobato,Molly B. Cason,Jim K. Wong
PeerJ , 2015, DOI: 10.7717/peerj.245
Abstract: Background. Do-not-resuscitate (DNR) orders are often active in patients with multiple comorbidities and a short natural life expectancy, but limited information exists as to how often these patients undergo high-risk operations and of the perioperative outcomes in this population.
Perioperative morbidity and mortality of cardiothoracic surgery in patients with a do-not-resuscitate order
Bryan G Maxwell,Robert L. Lobato,Molly B. Cason,Jim K. Wong
PeerJ , 2015, DOI: 10.7287/peerj.preprints.128v1
Abstract: Background: Do-not-resuscitate (DNR) orders are often active in patients with multiple comorbidities and a short natural life expectancy, but limited information exists as to how often these patients undergo high-risk operations and of the perioperative outcomes in this population. Methods: Using comprehensive inpatient administrative data from the Public Discharge Data file (years 2005 through 2010) of the California Office of Statewide Health Planning and Development, which includes a dedicated variable recording DNR status, we identified cohorts of DNR patients who underwent major cardiac or thoracic operations and compared them to age- and procedure-matched comparison cohorts. The primary study outcome was in-hospital mortality. Results: DNR status was not uncommon in cardiac (n=2,678, 1.1% of all admissions for cardiac surgery, age 71.6 ± 15.9 years) and thoracic (n=3,129, 3.7% of all admissions for thoracic surgery, age 73.8 ± 13.6 years) surgical patient populations. Relative to controls, patients who were DNR experienced significantly greater in-hospital mortality after cardiac (37.5% vs. 11.2%, p<0.0001) and thoracic (25.4% vs. 6.4%) operations. DNR status remained an independent predictor of in-hospital mortality on multivariate analysis after adjustment for baseline and comorbid conditions in both the cardiac (OR 4.78, 95% confidence interval 4.21-5.41, p<0.0001) and thoracic (OR 6.11, 95% confidence interval 5.37-6.94, p<0.0001) cohorts. Conclusions: DNR status is associated with worse outcomes of cardiothoracic surgery even when controlling for age, race, insurance status, and serious comorbid disease. DNR status appears to be a marker of substantial perioperative risk, and may warrant substantial consideration when framing discussions of surgical risk and benefit, resource utilization, and biomedical ethics surrounding end-of-life care.
Translation and validation of non-English versions of the Ankylosing Spondylitis Quality of Life (ASQOL) questionnaire
Lynda C Doward, Stephen P McKenna, David M Meads, James Twiss, Dennis Revicki, Robert L Wong, Michelle P Luo
Health and Quality of Life Outcomes , 2007, DOI: 10.1186/1477-7525-5-7
Abstract: The UK English ASQOL was translated into US English; Canadian French and English; French; German; Italian; Spanish; and Swedish (dual-panel methods). Cognitive debriefing interviews were conducted with AS patients. Psychometric/scaling properties were assessed using data from two Phase III studies of adalimumab. Baseline and Week-2 data were used to assess test-retest reliability. Validity was determined by correlation of ASQOL with SF-36 and BASFI and by discriminative ability of ASQOL based on disease severity. Item response theory (Rasch model) was used to test ASQOL's scaling properties.Cognitive debriefing showed the new ASQOL versions to be clear, relevant and comprehensive. Sample sizes varied, but were sufficient for: psychometric/scaling assessment for US English and Canadian English; psychometric but not scaling analyses for German; and preliminary evidence of these properties for the remaining languages. Test-retest reliability and Cronbach's alpha coefficients were high: US English (0.85, 0.85), Canadian English (0.87, 0.86), and German (0.77, 0.79). Correlations of ASQOL with SF-36 and BASFI for US English, Canadian English, and German measures were moderate, but ASQOL discriminated between patients based on perceived disease severities (p < 0.01). Results were comparable for the other languages. US English and Canadian English exhibited fit to the Rasch model (non-significant p-values: 0.54, 0.68), confirming unidimensionality.The ASQOL was successfully translated into all eight languages. Psychometric properties were excellent for US English, Canadian English, and German, and extremely promising for the other languages.Ankylosing spondylitis (AS) is a chronic rheumatic disease with a worldwide prevalence of up to 0.9% [1] and rates as high as 2.0% reported for some ethnic groups [2]. The sacroiliac joints are affected and, to a varying degree, the spinal column. The disease may also involve the peripheral joints and extra-articular structures [1]. Pat
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