2,256 research outputs found
Ocean ensemble forecasting. Part II: Mediterranean Forecast System response
This article analyzes the ocean forecast response to surface vector wind (SVW)
distributions generated by a Bayesian hierarchical model (BHM) developed in Part
I of this series. A new method for ocean ensemble forecasting (OEF), the socalled
BHM-SVW-OEF, is described. BHM-SVW realizations are used to produce
and force perturbations in the ocean state during 14 day analysis and 10 day
forecast cycles of the Mediterranean Forecast System (MFS). The BHM-SVW-OEF
ocean response spread is amplified at the mesoscales and in the pycnocline of
the eddy field. The new method is compared with an ensemble response forced
by European Centre for Medium-Range Weather Forecasts (ECMWF) ensemble
prediction system (EEPS) surface winds, and with an ensemble forecast started from
perturbed initial conditions derived froman ad hoc thermocline intensified random
perturbation (TIRP) method. The EEPS-OEF shows spread on basin scales while the
TIRP-OEF response is mesoscale-intensified as in the BHM-SVW-OEF response.
TIRP-OEF perturbations fill more of the MFS domain, while the BHM-SVW-OEF
perturbations are more location-specific, concentrating ensemble spread at the sites
where the ocean-model response to uncertainty in the surface wind forcing is largest
Ocean Ensemble Forecasting, Part II: Mediterranean Forecast System Response
This paper analyzes the ocean forecast response to surface vector wind (SVW) distributions
generated by a Bayesian Hierarchical Model (BHM) developed in Part I (Milliff et al., 2009).
A new method for Ocean Ensemble Forecasting (OEF), so-called BHM-SVW-OEF, is described.
BHM-SVW realizations are used to produce and force perturbations in the ocean
state during 14-day analysis and 10-day forecast cycles of the Mediterranean Forecast System
(MFS). The BHM-SVW-OEF ocean response spread is amplified at the mesoscales and
pycnocline of the eddy field. The new method is compared to an ensemble response forced by
ECMWF Ensemble Prediction System (EEPS) surface winds, and to an ensemble forecast
started from perturbed initial conditions derived from an ad hoc Thermocline Intensified
Random Perturbation (TIRP) method. The EEPS-OEF shows spread at the basin scales
while the TIRP-OEF response is mesoscale intensified as in the BHM-SVW-OEF response.
TIRP-OEF perturbations fill more of the MFS domain while the BHM-SVW-OEF perturbations
are more location-specific, concentrating ensemble spread at the sites where the ocean
model response to uncertainty in the surface wind forcing is largest. The BHM-SVW-OEF
method offers a practical and objective means for producing short-term forecast spread by
modeling surface atmospheric forcing uncertainties that have maximum impact at the ocean
mesoscales
The Advanced LIGO Photon Calibrators
The two interferometers of the Laser Interferometry Gravitaional-wave
Observatory (LIGO) recently detected gravitational waves from the mergers of
binary black hole systems. Accurate calibration of the output of these
detectors was crucial for the observation of these events, and the extraction
of parameters of the sources. The principal tools used to calibrate the
responses of the second-generation (Advanced) LIGO detectors to gravitational
waves are systems based on radiation pressure and referred to as Photon
Calibrators. These systems, which were completely redesigned for Advanced LIGO,
include several significant upgrades that enable them to meet the calibration
requirements of second-generation gravitational wave detectors in the new era
of gravitational-wave astronomy. We report on the design, implementation, and
operation of these Advanced LIGO Photon Calibrators that are currently
providing fiducial displacements on the order of
m/ with accuracy and precision of better than 1 %.Comment: 14 pages, 19 figure
Better Nonlinear Models from Noisy Data: Attractors with Maximum Likelihood
A new approach to nonlinear modelling is presented which, by incorporating
the global behaviour of the model, lifts shortcomings of both least squares and
total least squares parameter estimates. Although ubiquitous in practice, a
least squares approach is fundamentally flawed in that it assumes independent,
normally distributed (IND) forecast errors: nonlinear models will not yield IND
errors even if the noise is IND. A new cost function is obtained via the
maximum likelihood principle; superior results are illustrated both for small
data sets and infinitely long data streams.Comment: RevTex, 11 pages, 4 figure
A Support Group for Inpatient Abused Adolescents
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/75359/1/j.1744-6171.1990.tb00438.x.pd
Surgical Management of Inguinal Hernias at Bugando Medical Centre in Northwestern Tanzania: Our Experiences in a Resource-Limited Setting.
Inguinal hernia repair remains the commonest operation performed by general surgeons all over the world. There is paucity of published data on surgical management of inguinal hernias in our environment. This study is intended to describe our own experiences in the surgical management of inguinal hernias and compare our results with that reported in literature. A descriptive prospective study was conducted at Bugando Medical Centre in northwestern Tanzania. Ethical approval to conduct the study was obtained from relevant authorities before the commencement of the study. Statistical data analysis was done using SPSS software version 17.0. A total of 452 patients with inguinal hernias were enrolled in the study. The median age of patients was 36 years (range 3 months to 78 years). Males outnumbered females by a ratio of 36.7:1. This gender deference was statistically significant (P=0.003). Most patients (44.7%) presented late (more than five years of onset of hernia). Inguinoscrotal hernia (66.8%) was the commonest presentation. At presentation, 208 (46.0%) patients had reducible hernia, 110 (24.3%) had irreducible hernia, 84 (18.6%) and 50(11.1%) patients had obstructed and strangulated hernias respectively. The majority of patients (53.1%) had right sided inguinal hernia with a right-to-left ratio of 2.1: 1. Ninety-two (20.4%) patients had bilateral inguinal hernias. 296 (65.5%) patients had indirect hernia, 102 (22.6%) had direct hernia and 54 (11.9%) had both indirect and direct types (pantaloon hernia). All patients in this study underwent open herniorrhaphy. The majority of patients (61.5%) underwent elective herniorrhaphy under spinal anaesthesia (69.2%). Local anaesthesia was used in only 1.1% of cases. Bowel resection was required in 15.9% of patients. Modified Bassini's repair (79.9%) was the most common technique of posterior wall repair of the inguinal canal. Lichtenstein mesh repair was used in only one (0.2%) patient. Complication rate was 12.4% and it was significantly higher in emergency herniorrhaphy than in elective herniorrhaphy (P=0.002). The median length of hospital stay was 8 days and it was significantly longer in patients with advanced age, delayed admission, concomitant medical illness, high ASA class, the need for bowel resection and in those with surgical repair performed under general anesthesia (P<0.001). Mortality rate was 9.7%. Longer duration of symptoms, late hospitalization, coexisting disease, high ASA class, delayed operation, the need for bowel resection and presence of complications were found to be predictors of mortality (P<0.001). Inguinal hernias continue to be a source of morbidity and mortality in our centre. Early presentation and elective repair of inguinal hernias is pivotal in order to eliminate the morbidity and mortality associated with this very common problem
A Single Dermatome Clinical Prediction Rule for Independent Walking 1 Year After Spinal Cord Injury
Objective: To derive and validate a simple, accurate CPR to predict future independent walking ability after SCI at the bedside that does not rely on motor scores and is predictive for those initially classified in the middle of the SCI severity spectrum. Design: Retrospective cohort study. Binary variables were derived, indicating degrees of sensation to evaluate predictive value of pinprick and light touch variables across dermatomes. The optimal single sensory modality and dermatome was used to derive our CPR, which was validated on an independent dataset. Setting: Analysis of SCI Model Systems dataset. Participants: Individuals with traumatic SCI. The data of 3679 participants (N=3679) were included with 623 participants comprising the derivation dataset and 3056 comprising the validation dataset. Interventions: Not applicable. Main Outcome Measures: Self-reported ability to walk both indoors and outdoors. Results: Pinprick testing at S1 over lateral heels, within 31 days of SCI, accurately identified future independent walkers 1 year after SCI. Normal pinprick in both lateral heels provided good prognosis, any pinprick sensation in either lateral heel provided fair prognosis, and no sensation provided poor prognosis. This CPR performed satisfactorily in the middle SCI severity subgroup. Conclusions: In this large multi-site study, we derived and validated a simple, accurate CPR using only pinprick sensory testing at lateral heels that predicts future independent walking after SCI
Business unusual: collective action against bribery in international business
Collective action initiatives in which governments and companies make anti-corruption commitments have proliferated in recent years. This apparently prosocial behavior defies the logic of collective action and, given that bribery often goes undetected and unpunished, is not easily explained by principal-agent theory. Club theory suggests that the answer lies in the institutional design of anti-corruption clubs: collective action can work as long as membership has high entry costs, members receive selective benefits, and compliance is adequately policed. This article contributes to the debate by examining how these conditions manifest in the case of anti-corruption clubs in the realm of international business, with particular focus on the international dimension of many initiatives. This vertical aspect of institutional design creates a richer, more complex set of reputational and material benefits for members, as well as allowing for more credible and consistent monitoring and enforcement
Identifying a Typology of High Schools Based on Their Orientation Toward STEM: A Latent Class Analysis of HSLS:09
The purpose of this study is to investigate the extent that there is a typology of high schools based on their orientation toward STEM, as well as the extent to which school-level demographic variables and student high school outcomes are associated with subgroup membership in the typology, by analyzing data from a large nationally representative sample of high schools (n=940) from the High School Longitudinal Study of 2009 (HSLS:09) using latent class analysis (LCA). We used a three-step LCA approach to identify significantly different subgroups of STEM-oriented high schools, what covariates predict subgroup membership, and how subgroup membership predicts observed distal outcomes. We find that there are four significantly different subgroups of STEM-oriented high schools based on their principal’s perceptions: Abundant (12.3%), Support (23.3%), Bounded (10.1%), and Comprehensive (54.3%). In addition, we find that these subgroups are associated with school demographics, such as the percent of students eligible for free and reduced-price lunch, school locale, and control (public or private). Subgroup membership is also associated with student outcomes, such as postsecondary program enrollment and intent to pursue a STEM degree.
Keywords: STEM Education, High Schools, Multivariate Analysi
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