514 research outputs found
Recommended from our members
Information systems assessment: development of a comprehensive framework and contingency theory to assess the effectiveness of the information systems function.
The purpose of this research is to develop a comprehensive, IS assessment framework using existing IS assessment theory as a base and incorporating suggestions from other disciplines. To validate the framework and to begin the investigation of current IS assessment practice, a survey instrument was developed. A small group of subject matter experts evaluated and improved the instrument. The instrument was further evaluated using a small sample of IS representatives. Results of this research include a reexamination of the IS function measurement problem using new frameworks of analyses yielding (a) guidance for the IS manager or executive on which IS measures might best fit their organization, (b) a further verification of the important measures most widely used by IS executives, (c) a comprehensive, theoretically-derived, IS assessment framework, and by (d) the enhancement of IS assessment theory by incorporating ideas from actual practice. The body of knowledge gains a comprehensive, IS assessment framework that can be further tested for usefulness and applicability. Future research is recommended to substantiate and improve on these findings. Chapter 2 is a complete survey of prior research, subdivided by relevant literature divisions, such as organizational effectiveness, quality management, and IS assessment. Chapter 3 includes development of and support for the research questions, IS assessment framework, and the research model. Chapter 4 describes how the research was conducted. It includes a brief justification for the research approach, a description of how the framework was evaluated, a description of how the survey instrument was developed and evaluated, a description of the participants and how they were selected, a synopsis of the data collection procedures, a brief description of follow-up procedures, and a summary. Chapter 5 presents the results of the research. Chapter 6 is a summary and conclusion of the research. Finally, included in the appendices are definitions of terms, and copies of the original and improved survey instruments
The Fontan operation in infants less than 2 years of age
AbstractYoung age remains a reported risk factor for a successful Fontan operation despite improved survival rates. Since March 1978, the Fontan operation has been performed in 47 patients. To avoid a primary or secondary polliative shunt, an early Fontan procedure (Group 1: mean age 1.5 ± 0.5 years, range 0.6 to 2) has been performed in 17 children with the outcome similar to that of the remaining 30 older patients (Group 2: mean age 7.5 ± 5 years, range 2.4 to 23 years). Preoperatively both groups had acceptable hemodynamic status for a successful Fontan result.Operative variables including cardiopulmonary bypass time, aortic cross-clamp time and core temperature were similar between groups and did not affect mortality. The postoperative mortality rate including early surgical (0% vs. 13%, respectively), late (18% vs. 12%) and total (18% vs. 23%) was similar between Groups 1 and 2 (p > 0.05). Immediate postoperative arrhythmias were more frequent in Group 1 (71% vs. 25%, p < 0.01) with no related mortality, while late arrhythmias occurred with equal frequency (29% vs. 39%, p > 0.05). Group 1 infants required a longer hospital stay (22 ± 9 vs. 14 ± 5 days, p < 0.01).Thus, young age is not a risk factor for successful outcome of the Fontan operation in patients with acceptable preoperative hemodynamic status. An early Fontan operation may also avoid prolonged palliative procedures and their potential deleterious effects
Down-regulation of OPA1 in patients with primary open angle glaucoma
PURPOSE: Heterozygous optic atrophy type1 (OPA1) mutations are responsible for dominant optic atrophy, and the down regulation of OPA1 expression in patients with Leber hereditary optic neuropathy may imply that Opa1 protein levels in mitochondria play a role in other spontaneous optic neuropathies as well. Mitochondrial and metabolic abnormalities may put the optic nerve at risk in primary open angle glaucoma (POAG), and this preliminary study was designed to investigate whether altered OPA1 expression might be present in the progressive optic neuropathy of POAG.
METHODS: Patients were eligible for inclusion if they met standard clinical criteria for POAG, including age greater than 40 years, intraocular pressure â„ 21 mmHg in at least one eye before treatment, normal-appearing anterior chamber angles bilaterally on gonioscopy, and optic nerve injury characteristic of POAG. RNA was extracted from leukocytes and converted to cDNA by reverse transcriptase enzyme, and real time PCR was used to assess expression levels of OPA1 and the ÎČ-globulin (HBB) housekeeping gene. The ratio of OPA1 expression to HBB expression (OPA1/HBB) for POAG patients was compared to that of controls and to clinical characteristics of POAG patients.
RESULTS: Forty-three POAG patients and 27 controls were completely phenotyped with a full ophthalmologic examination and static perimetry. Mean age (POAG 67.9 years; controls 61.8 years) and sex (POAG 26 males/17 females; controls 11/16) were similar for the two groups. Mean OPA1/HBB of POAG patients (1.16, SD 0.26) was 18% lower than controls (1.41, SD 0.50), and this difference was statistically significant (pâ€0.021). OPA1 expression differed between the groups (pâ€0.037), but HBB expression did not differ (pâ€0.24). OPA1/HBB was not correlated with any clinical feature of POAG patients.
CONCLUSIONS: Transcriptional analysis of peripheral blood leucocytes is a limited model system for studying the consequences of mitochondrial abnormalities in the optic nerve. Nevertheless, OPA1 is known to affect mitochondrial stability and has now been implicated in several spontaneous optic neuropathies. Decreased OPA1 expression in POAG patients is another indication that mitochondrial function, and possibly mitochondrially-induced apoptosis, may play a role in the development of POAG
Mid-infrared spectra of PAH emission in Herbig AeBe stars
We present spectra of four Herbig AeBe stars obtained with the Infrared
Spectrograph (IRS). on the Spitzer Space Telescope. All four of the sources
show strong emission from polycyclic aromatic hydrocarbons (PAHs), with the 6.2
um emission feature shifted to 6.3 um and the strongest C-C skeletal-mode
feature occuring at 7.9 um instead of at 7.7 um as is often seen. Remarkably,
none of the four stars have silicate emission. The strength of the 7.9 um
feature varies with respect to the 11.3 um feature among the sources,
indicating that we have observed PAHs with a range of ionization fractions. The
ionization fraction is higher for systems with hotter and brighter central
stars. Two sources, HD 34282 and HD 169142, show emission features from
aliphatic hydrocarbons at 6.85 and 7.25 um. The spectrum of HD 141569 shows a
previously undetected emission feature at 12.4 um which may be related to the
12.7 um PAH feature. The spectrum of HD 135344, the coolest star in our sample,
shows an unusual profile in the 7-9 um region, with the peak emission to the
red of 8.0 um and no 8.6 um PAH feature.Comment: Accepted by ApJ 23 June, 2005, 8 pages (emulateapj), 5 figures (3 in
color
Sex differences in physiological progression of idiopathic pulmonary fibrosis
In idiopathic pulmonary fibrosis, incidence is higher in males, and females may have
better survival. The aim of the present study was to determine whether the rate of increase in
desaturation during serial 6-min walk testing would be greater, and survival worse, for males
versus females.
Serial changes in the percentage of maximum desaturation area (DA) over 1 yr were estimated
using mixed models in 215 patients. DA was defined as the total area above the curve created
using desaturation percentage values observed during each minute of the 6-min walk test.
Multivariate Cox regression assessed survival differences.
Adjusting for baseline DA, 6-min walk distance, change in 6-min walk distance over time and
smoking history, the percentage of maximum DA increased by an average of 2.83 and 1.37% per
month for males and females, respectively. Females demonstrated better survival overall, which
was more pronounced in patients who did not desaturate below 88% on ambulation at baseline
and after additionally adjusting for 6-month relative changes in DA and forced vital capacity.
These data suggest that differences in disease progression contribute to, but do not completely
explain, better survival of females with idiopathic pulmonary fibrosis.This work was supported by National
Institutes of Health grants
5P50HL56402, U10HL080371,
2K24HL04212, K12RR024987 and
K23HL68713, and the Alberta
Heritage Medical Foundation.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/91966/1/2008 ERJ - Sex Differences in Physiologic Progression of Idiopathic Pulmonary Fibrosis.pd
Pulmonary function measures predict mortality differently in IPF versus combined pulmonary fibrosis and emphysema
The composite physiologic index (CPI) was derived to represent the extent of
fibrosis on high-resolution computed tomography (HRCT), adjusting for emphysema in patients
with idiopathic pulmonary fibrosis (IPF). We hypothesised that longitudinal change in CPI would
better predict mortality than forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC) or
diffusing capacity of the lung for carbon monoxide (DLCO) in all patients with IPF, and especially
in those with combined pulmonary fibrosis and emphysema (CPFE).
Cox proportional hazard models were performed on pulmonary function data from IPF patients at
baseline (n=321), 6 months (n=211) and 12 months (n=144). Presence of CPFE was determined by
HRCT.
A five-point increase in CPI over 12 months predicted subsequent mortality (HR 2.1, p=0.004). At
12 months, a 10% relative decline in FVC, a 15% relative decline in DLCO or an absolute increase in
CPI of five points all discriminated median survival by 2.1 to 2.2 yrs versus patients with lesser
change. Half our cohort had CPFE. In patients with moderate/severe emphysema, only a 10%
decline in FEV1 predicted mortality (HR 3.7, p=0.046).
In IPF, a five-point increase in CPI over 12 months predicts mortality similarly to relative
declines of 10% in FVC or 15% in DLCO. For CPFE patients, change in FEV1 was the best predictor
of mortality.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/91949/1/2011 ERJ - Pulmonary function measures predict mortality differently in IPF versus combined pulmonary fibrosis and emphysema.pd
Identifying the optimal exercise prescription for patients with coronary artery disease undergoing cardiac rehabilitation: protocol for a systematic review and network meta-analysis of randomized control trials
Coronary artery disease (CAD) is one of the leading causes of mortality and morbidity. Exercise-based cardiac rehabilitation (EBCR) has been shown to improve clinical outcomes in these patients, and yet clinicians are often challenged to prescribe the most effective type of exercise training. Therefore, this systematic review and network meta-analysis (NMA) aims to formally quantify the optimal dose of exercise training interventions to improve exercise capacity and quality of life by undertaking direct and indirect pooled comparisons of randomized controlled trials. A detailed search will be conducted on PubMed/MEDLINE, Cumulative Index to Nursing and Allied Health (CINAHL), EMBASE and Web of Science. Two reviewers will screen the existing literature and assess the quality of the studies. Disagreements will be resolved through consensus. We anticipate that the analysis will include pairwise and Bayesian network meta-analyses. Most of the trials have studied the impact of exercise training comparing one or two modalities. As a result, little evidence exists to support which interventions will be most effective. The current NMA will address this gap in the literature and assist clinicians and cardiac rehabilitation specialists in making an informed decision. Results will be disseminated through peer-reviewed journals. Ethical approval is not applicable, as no research participants will be involved. PROSPERO Registration number: CRD42022262644
The Second-Generation Guide Star Catalog: Description and Properties
The GSC-II is an all-sky database of objects derived from the uncompressed
DSS that the STScI has created from the Palomar and UK Schmidt survey plates
and made available to the community. Like its predecessor (GSC-I), the GSC-II
was primarily created to provide guide star information and observation
planning support for HST. This version, however, is already employed at some of
the ground-based new-technology telescopes such as GEMINI, VLT, and TNG, and
will also be used to provide support for the JWST and Gaia space missions as
well as LAMOST, one of the major ongoing scientific projects in China. Two
catalogs have already been extracted from the GSC-II database and released to
the astronomical community. A magnitude-limited (R=18.0) version, GSC2.2, was
distributed soon after its production in 2001, while the GSC2.3 release has
been available for general access since 2007.
The GSC2.3 catalog described in this paper contains astrometry, photometry,
and classification for 945,592,683 objects down to the magnitude limit of the
plates. Positions are tied to the ICRS; for stellar sources, the all-sky
average absolute error per coordinate ranges from 0.2" to 0.28" depending on
magnitude. When dealing with extended objects, astrometric errors are 20% worse
in the case of galaxies and approximately a factor of 2 worse for blended
images. Stellar photometry is determined to 0.13-0.22 mag as a function of
magnitude and photographic passbands (B,R,I). Outside of the galactic plane,
stellar classification is reliable to at least 90% confidence for magnitudes
brighter than R=19.5, and the catalog is complete to R=20.Comment: 52 pages, 33 figures, to be published in AJ August 200
The state of protoplanetary material 10 Myr after stellar formation: circumstellar disks in the TW Hydrae association
We have used the Spitzer Infrared Spectrograph to observe seven members of
the TW Hya association, the nearest stellar association whose age ( 10
Myr) is similar to the timescales thought to apply to planet formation and disk
dissipation. Only two of the seven targets display infrared excess emission,
indicating that substantial amounts of dust still exist closer to the stars
than is characteristic of debris disks; however, in both objects we confirm an
abrupt short-wavelength edge to the excess, as is seen in disks with
cleared-out central regions. The mid-infrared excesses in the spectra of Hen
3-600 and TW Hya include crystalline silicate emission features, indicating
that the grains have undergone significant thermal processing. We offer a
detailed comparison between the spectra of TW Hya and Hen 3-600, and a model
that corroborates the spectral shape and our previous understanding of the
radial structure of these protoplanetary disks.Comment: To appear in the Spitzer special issue of ApJS; 12 pages, 2 figure
- âŠ