750 research outputs found
Airline delays, congestion internalization and non-price spillover effects of low cost carrier entry
This paper develops an econometric model of flight delays to investigate the
influence of competition and dominance on the incentives of carriers to
maintain on-time performance. We consider both the route and the airport levels
to inspect the local and global effects of competition, with a unifying
framework to test the hypotheses of 1. airport congestion internalization and
2. the market competition-quality relationship in a single econometric model.
In particular, we examine the impacts of the entry of low cost carriers (LCC)
on the flight delays of incumbent full service carriers in the Brazilian
airline industry. The main results indicate a highly significant effect of
airport congestion self-internalization in parallel with route-level quality
competition. Additionally, the potential competition caused by LCC presence
provokes a global effect that suggests the existence of non-price spillovers of
the LCC entry to non-entered routes
Seatbelt: A Double-Edged Sword
Intra-abdominal vascular injury due to blunt trauma is unusual in children. Due to its rarity, detailed reports dealing with its management are scarce in paediatric literature. Diagnosis of these injuries is challenging, and a high degree of awareness is necessary for rapid identification and treatment of these injuries. We report the case of a child with seatbelt sign and mesenteric vein injury due to blunt trauma to the abdomen during a motor vehicle accident where the seatbelt was incorrectly placed. She also sustained cervical vertebral injury. The pattern of injuries in children in these situations may differ from that found in adults. While seatbelts have undoubtedly saved many lives, awareness about correct placement of these restraints is extremely necessary
Streamlined design of a self-inactivating feline immunodeficiency virus vector for transducing ex vivo dendritic cells and T lymphocytes.
BACKGROUND: Safe and efficient vector systems for delivering antigens or immunomodulatory molecules to dendritic cells (DCs), T lymphocytes or both are considered effective means of eliciting adaptive immune responses and modulating their type, extent, and duration. As a possible tool toward this end, we have developed a self-inactivating vector derived from feline immunodeficiency virus (FIV) showing performance characteristics similar to human immunodeficiency virus-derived vectors but devoid of the safety concerns these vectors have raised. METHODS: The pseudotyped FIV particles were generated with a three-plasmid system consisting of: the packaging construct, providing Gag, Pol and the accessory proteins; the vector(s), basically containing FIV packaging signal (psi), Rev responsive element, R-U5 region at both ends, and the green fluorescent protein as reporter gene; and the Env plasmid, encoding the G protein of vesicular stomatitis virus (VSV-G) or the chimeric RD114 protein. Both packaging and vector constructs were derived from p34TF10, a replication competent molecular clone of FIV. The pseudotyped particles were produced by transient transfection in the Crandell feline fibroblast kidney (CrFK) or the human epithelial (293T) cell line. RESULTS: To broaden its species tropism, the final vector construct was achieved through a series of intermediate constructs bearing a longer psi, the FIV central polypurin tract sequence (cPPT), or the woodchuck hepatitis post-regulatory element (WPRE). These constructs were compared for efficiency and duration of transduction in CrFK or 293T cells and in the murine fibroblast cell line NIH-3T3. Whereas psi elongation and cPPT addition did not bring any obvious benefit, insertion of WPRE downstream GFP greatly improved vector performances. To maximize the efficiency of transduction for ex-vivo murine DCs and T-lymphocytes, this construct was tested with VSV-G or RD114 and using different transduction protocols. The results indicated that the FIV construct derived herein stably transduced both cell types, provided that appropriate vector makeup and transduction protocol were used. Further, transduced DCs underwent changes suggestive of an induced maturation. CONCLUSION: In contrast to previously described FIV vectors that were poorly efficient in delivering genetic material to DCs and T lymphocytes, the vector developed herein has potential for use in experimental immunization strategies
StarFinder: an IDL GUI based code to analyze crowded fields with isoplanatic correcting PSF fitting
StarFinder is a new code for the deep analysis of stellar fields, designed
for well-sampled images with high and low Strehl ratio. It is organized in the
form of a self-contained IDL widget-based application, with a 'user-friendly'
graphic interface. We give here a general description of the code along with
some applications to real data with space-invariant Point Spread Function
(PSF). We present also some methods to handle anisoplanatic effects in
wide-field Adaptive Optics (AO)observations.Comment: 9 pages, to to be published on "Proceeedings of Adaptive Optical
Systems Technology",Proc.of SPIE,Vol.4007,2000. In pres
Intensive Care and Anesthesiology
AbstractThe wide range of medical disciplines afferent to anesthesiology (anesthesia, perioperative care, intensive care medicine, pain therapy, and emergency medicine), carry a great, cross-specialty opportunity to influence safety and quality of patients' care. Operating rooms and Intensive Care Units are settings burdened with a high risk of error: surgery is evolving, while the medical staff working in ICU is expected to provide high-quality care in a stressful and complex setting. It is estimated that about 1.5% of surgical interventions are complicated by critical events, but the true incidence is likely underestimated. Across medical specialties, preventable patient harm is more prevalent in the ICU.Recommendations and good practices for the safe provision of anesthesia and critical care exist and must be known and transferred into daily practice, since one of the main duties of anesthesia and critical care providers is to provide patient safety. Strategies to reduce the occurrence of medication errors, appropriate monitoring practices, equipment care and knowledge, planification and mastery of non-technical skills during emergencies, as well as designing and sustaining a healthy work environment and adopting adequate staffing policies could have an impact on patient safety and positively influence patient outcomes in this setting. The development of simulation training and cognitive aids (e.g., checklists, emergency manuals) is also changing the approach to crises and is expected to encourage a deeper cultural change
Clinical efficacy of minimally invasive surgical (MIS) and non-surgical (MINST) treatments of periodontal intra-bony defect. A systematic review and network meta-analysis of RCT's
Objective: The aim of this systematic review was to explore the efficacy of different minimal invasive surgical (MIS) and non-surgical (MINST) approaches for the treatment of intra-bony defect in terms of clinical attachment level (CAL) gain and periodontal pocket depth (PPD) reduction. /
Methods: A detailed review protocol was designed according to PRISMA guideline. Online search was conducted on PubMed, Cochrane library and Embase. Only randomized clinical trials (RCTs) testing MIS or MINST procedure, with or without the application of a regenerative tool for the treatment of intra-bony defect, were included. Cochrane checklist for risk of bias assessment was used. Network meta-Analysis (NMAs) was used to rank the treatment efficacy. /
Results: Nine RCTs accounting for 244 patients and a total of 244 defects were included. Only two studies were at low risk of bias. CAL gain for included treatment ranged from 2.58 ± 1.13 mm to 4.7 ± 2.5 mm while PPD reduction ranged from 3.19 ± 0.71 mm to 5.3 ± 1.5 mm. On the basis of the ranking curve, MINST showed the lowest probability to be the best treatment option for CAL gain. Pairwise comparisons and treatment rankings suggest superiority for regenerative approaches (CAL difference 0.78 mm, (0.14–1.41); P < 0.05) and surgical treatment elevating only the buccal or palatal flap (CAL difference: 0.95 mm, (0.33–1.57); P < 0.05). /
Conclusions: Minimally invasive surgical (MIS) and non-surgical (MINST) periodontal therapy show promising results in the treatment of residual pocket with intra-bony defect. /
Clinical relevance: MIS procedures represent a reliable treatment for isolated intra-bony defect
Development of Feline Immunodeficiency Virus ORF-A (tat) Mutants: In Vitro and in Vivo Characterization
AbstractA functional ORF-A is essential for efficient feline immunodeficiency virus replication in lymphocytes. We have characterized a series of mutants of the Petaluma strain, derived from p34TF10 and having different combinations of stop codons and increasingly long deletions in ORF-A. Six clones proved fully replicative in fibroblastoid Crandell feline kidney cells and monocyte-derived macrophage cultures but failed to replicate in T cell lines and primary lymphoblasts. Cats inoculated with three selected mutants had considerably milder infections than controls given intact ORF-A virus. In vivo, the mutants maintained growth properties similar to those in vitro for at least 7 months, except that replication in lymphoid cells was strongly reduced but not ablated. One mutant underwent extensive ORF-A changes without, however, reverting to wild-type. Antiviral immune responses were feeble in all cats, suggesting that viral loads were too low to represent a sufficiently powerful antigenic stimulus
Neutralizing antibodies in cats infected with feline immunodeficiency virus.
Sera from cats experimentally infected with five isolates of feline immunodeficiency virus (FIV) from various geographical regions and from FIV enzyme-linked immunosorbent assay-seropositive field cats from four European countries neutralized the Petaluma strain of FIV (FIV-P), originally isolated in California, at high titers. In addition, FIV-P and a European isolate proved equally susceptible to neutralization by all sera tested. Coupled with observations by Fevereiro et al. (M. Fevereiro, C. Roneker, A. Laufs, L. Tavares, and F. de Noronha, J. Gen. Virol. 72:617-622, 1991), these findings indicate that most if not all FIV strains circulating in Europe and the United States share important neutralization-inducing epitopes
On the Size Difference between Red and Blue Globular Clusters
Several recent studies have reported a mean size difference of about 20%
between the metal-rich and metal-poor subpopulations of globular clusters (GCs)
in a variety of galaxies. In this paper we investigate the possibility that the
size difference might be a projection effect, resulting from a correlation
between cluster size and galactocentric distance, combined with different
radial distributions of the GC subpopulations. We find that projection effects
may indeed account for a size difference similar to the observed one, provided
that there is a steep relation between GC size and galactocentric distance in
the central parts of the GC system and that the density of GCs flattens off
near the center in a manner similar to a King profile. For more centrally
peaked distributions, such as a de Vaucouleurs law, or for shallower
size-radius relations, projection effects are unable to produce the observed
differences in the size distributions.Comment: 30 pages, including 14 figures and 2 tables. Accepted for publication
in Ap
Heart and Lungs in COPD. Close friends in real life - separate in daily medical practice?
Chronic obstructive pulmonary disease (COPD) is associated with a 2-3 times higher rate of cardiovascular disorders (CVD) which is independent of other risk factors. A low FEV1 is a specific predictor of mortality as a result of cardiac causes, even stronger than increased cholesterol: for each 10% reduction of FEV1, cardiovascular mortality increases by 28%. The main causes of death among COPD patients are of cardiovascular origin. COPD and CVD have two major risk factors in common - advanced age and tobacco smoking. The search for a pathogenetic link between the two conditions focuses mainly on systemic extension of pulmonary inflammation. Despite such a frequent association, pulmonologists and cardiologists in both the clinical and the research settings often underestimate the importance of a correct diagnosis and severity stratification of the two combined conditions. Spirometry, in particular, is largely underprescribed. Missed diagnosis and severity stratification, incomplete knowledge of adverse drug events and lack of resources lead to undertreatment of patients combining COPD and CVD, and in particular, the underuse of beta-blockers, inhaled bronchodilators and rehabilitation. Clinical studies focusing on this group of patients should be promoted in the future to test therapies and manage options. Furthermore, efforts must be made to improve the present standards of care, which falls short of recommended levels, starting from the often-neglected use of spirometry to confirm a diagnosis of COPD
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