5,911 research outputs found
Prometheus unbound: A study of the Dallas/Fort Worth Regional Airport
The history of the controversies in the development of the Dallas/Fort Worth Regional Airport is detailed. Present technological and organizational management problems are outlined. Maps and illustrations are included
Technology and politics: The regional airport experience
The findings of a comparative study of the following six regional airports were presented: Dallas/Fort Worth, Kansas City, Washington, D.C., Montreal, Tampa, and St. Louis. Each case was approached as a unique historical entity, in order to investigate common elements such as: the use of predictive models in planning, the role of symbolism to heighten dramatic effects, the roles of community and professional elites, and design flexibility. Some of the factors considered were: site selection, consolidation of airline service, accessibility, land availability and cost, safety, nuisance, and pollution constraints, economic growth, expectation of regional growth, the demand forecasting conundrum, and design decisions. The hypotheses developed include the following: the effect of political, social, and economic conflicts, the stress on large capacity and dramatic, high-technology design, projections of rapid growth to explain the need for large capital outlays
ORGANIZATIONAL DESIGN, ORGANIZATIONAL LEARNING, AND THE MARKET VALUE OF THE FIRM
We compare market returns associated with firms' creation of new units focused on e-business. Two aspects of organization design - governance and leadership - are considered with regard to exploitation - and exploration-oriented organization learning. We find that exploitation in governance (high centralization) is associated with a lower mean and variance in returns; that exploitation in leadership (appointment of outsiders) is associated with the same mean yet higher variance; and, among units exhibiting both modes of learning, the variance of returns are not equal
In search of progenitors for supernova-less GRBs 060505 and 060614: re-examination of their afterglows
GRB060505 and GRB060614 are nearby long-duration gamma-ray bursts (LGRBs)
without accompanying supernovae (SNe) down to very strict limits. They thereby
challenge the conventional LGRB-SN connection and naturally give rise to the
question: are there other peculiar features in their afterglows which would
help shed light on their progenitors? To answer this question, we combine new
observational data with published data and investigate the multi-band temporal
and spectral properties of the two afterglows. We find that both afterglows can
be well interpreted within the framework of the jetted standard external shock
wave model, and that the afterglow parameters for both bursts fall well within
the range observed for other LGRBs. Hence, from the properties of the
afterglows there is nothing to suggest that these bursts should have another
progenitor than other LGRBs. Recently, Swift-discovered GRB080503 also has the
spike + tail structure during its prompt gamma-ray emission seemingly similar
to GRB060614. We analyse the prompt emission of this burst and find that this
GRB is actually a hard-spike + hard-tail burst with a spectral lag of
0.80.4 s during its tail emission. Thus, the properties of the prompt
emission of GRB060614 and GRB080503 are clearly different, motivating further
thinking of GRB classification. Finally we note that, whereas the progenitor of
the two SN-less bursts remains uncertain, the core-collapse origin for the
SN-less bursts would be quite certain if a wind-like environment can be
observationally established, e.g, from an optical decay faster than the X-ray
decay in the afterglow's slow cooling phase.Comment: 15 pages, 7 figures, 4 tables, ApJ in press; added Fig. 7 of the
lag-luminosity relatio
Influence of Sacubitril/Valsartan (LCZ696) on 30-day readmission after heart failure hospitalization
Background:
Patients with heart failure (HF) are at high risk for hospital readmission in the first 30 days following HF hospitalization.
Objectives:
This study sought to determine if treatment with sacubitril/valsartan (LCZ696) reduces rates of hospital readmission at 30-days following HF hospitalization compared with enalapril.
Methods:
We assessed the risk of 30-day readmission for any cause following investigator-reported hospitalizations for HF in the PARADIGM-HF trial, which randomized 8,399 participants with HF and reduced ejection fraction to treatment with LCZ696 or enalapril.
Results:
Accounting for multiple hospitalizations per patient, there were 2,383 investigator-reported HF hospitalizations, of which 1,076 (45.2%) occurred in subjects assigned to LCZ696 and 1,307 (54.8%) occurred in subjects assigned to enalapril. Rates of readmission for any cause at 30 days were 17.8% in LCZ696-assigned subjects and 21.0% in enalapril-assigned subjects (odds ratio: 0.74; 95% confidence interval: 0.56 to 0.97; p = 0.031). Rates of readmission for HF at 30-days were also lower in subjects assigned to LCZ696 (9.7% vs. 13.4%; odds ratio: 0.62; 95% confidence interval: 0.45 to 0.87; p = 0.006). The reduction in both all-cause and HF readmissions with LCZ696 was maintained when the time window from discharge was extended to 60 days and in sensitivity analyses restricted to adjudicated HF hospitalizations.
Conclusions:
Compared with enalapril, treatment with LCZ696 reduces 30-day readmissions for any cause following discharge from HF hospitalization
Picoradian deflection measurement with an interferometric quasi-autocollimator using weak value amplification
We present an "interferometric quasi-autocollimator" that employs weak value
amplification to measure angular deflections of a target mirror. The device has
been designed to be insensitive to all translations of the target. We present a
conceptual explanation of the amplification effect used by the device. An
implementation of the device demonstrates sensitivities better than 10
picoradians per root hertz between 10 and 200 hertz.Comment: To be published in Optics Letter
Repurposing the (super)crip: media representations of disability at the Rio 2016 Paralympic Games
Mega-events attract ever larger media audiences, and the 2016 Rio Paralympics were no exception. As audiences grow, media coverage extends to ever more varied domains, which are themselves then colonised by an increasing range of discourses. One of main discourses to develop since the early 2000s has been that of the so-called “supercrip”, one which challenges the notion of “impairment” often connected with disability by foregrounding the para-athletes’ triumph over adversity, celebrating instead their courage, grit and perseverance leading to athletic success and personal and increasingly national prestige. In this article we analyse the continuing importance of the supercrip discourse in coverage of the Rio Paralympics, but also move on to highlight its tactical alignment with other – both competing and complementary – discourses of nationalism, sexualisation, militarisation and celebritisation. We analyse textual and visual manifestations of these discourses using both Critical Discourse Analysis and Foucauldian discourse analysis. We conclude by paying particular attention to the increasing visibility of discourses which, while acknowledging the potentially positive role of the supercrip discourse in focussing on athletic success, repurpose that discourse by foregrounding instead the day-to-day experiences of belittling misrepresentation and neglect, including political neglect
Swift captures the spectrally evolving prompt emission of GRB 070616
The origins of Gamma-ray Burst prompt emission are currently not well
understood and in this context long, well-observed events are particularly
important to study. We present the case of GRB 070616, analysing the
exceptionally long-duration multipeaked prompt emission, and later afterglow,
captured by all the instruments on-board Swift and by Suzaku WAM. The high
energy light curve remained generally flat for several hundred seconds before
going into a steep decline. Spectral evolution from hard to soft is clearly
taking place throughout the prompt emission, beginning at 285 s after the
trigger and extending to 1200 s. We track the movement of the spectral peak
energy, whilst observing a softening of the low energy spectral slope. The
steep decline in flux may be caused by a combination of this strong spectral
evolution and the curvature effect. We investigate origins for the spectral
evolution, ruling out a superposition of two power laws and considering instead
an additional component dominant during the late prompt emission. We also
discuss origins for the early optical emission and the physics of the
afterglow. The case of GRB 070616 clearly demonstrates that both broadband
coverage and good time resolution are crucial to pin down the origins of the
complex prompt emission in GRBs.Comment: 13 pages, 11 figures (2 in colour), MNRAS accepte
Extensive telomere repeat arrays in mouse are hypervariable
In this study we have analysed mouse telomeres by Pulsed Field Gel Electrophoresis (PFGE). A number of specific restriction fragments hybridising to a (TTA-GGG)4 probe in the size range 50-150kb can be detected. These fragments are devoid of sites for most restriction enzymes suggesting that they comprise simple repeats; we argue that most of these are likely to be (TTAGGG)n. Each discrete fragment corresponds to the telomere of an individual chromosome and segregates as a Mendelian character. However, new size variants are being generated in the germ line at very high rates such that inbred mice are heterozygous at all telomeres analysable. In addition we show that specific small (approximately 4-12kb) fragments can be cleaved within some terminal arrays by the restriction enzyme MnII which recognises 5'(N7)GAGG3'. Like the complete telomere-repeat arrays (TRA's) these fragments form new variants at high rates and possibly by the same process. We speculate on the mechanisms that may be involved
Risk Assessment and Comparative Effectiveness of Left Ventricular Assist Device and Medical Management in Ambulatory Heart Failure Patients The ROADMAP Study 2-Year Results
OBJECTIVES The authors sought to provide the pre-specified primary endpoint of the ROADMAP (Risk Assessment and Comparative Effectiveness of Left Ventricular Assist Device and Medical Management in Ambulatory Heart Failure Patients) trial at 2 years. BACKGROUND The ROADMAP trial was a prospective nonrandomized observational study of 200 patients (97 with a left ventricular assist device [LVAD], 103 on optimal medical management [OMM]) that showed that survival with improved functional status at 1 year was better with LVADs compared with OMM in a patient population of ambulatory New York Heart Association functional class IIIb/IV patients. METHODS The primary composite endpoint was survival on original therapy with improvement in 6-min walk distance \u3e= 75 m. RESULTS Patients receiving LVAD versus OMM had lower baseline health-related quality of life, reduced Seattle Heart Failure Model 1-year survival (78% vs. 84%; p = 0.012), and were predominantly INTERMACS (Interagency Registry for Mechanically Assisted Circulatory Support) profile 4 (65% vs. 34%; p \u3c 0.001) versus profiles 5 to 7. More LVAD patients met the primary endpoint at 2 years: 30% LVAD versus 12% OMM (odds ratio: 3.2 [95% confidence interval: 1.3 to 7.7]; p = 0.012). Survival as treated on original therapy at 2 years was greater for LVAD versus OMM (70 +/- 5% vs. 41 +/- 5%; p \u3c 0.001), but there was no difference in intent-to-treat survival (70 +/- 5% vs. 63 +/- 5%; p = 0.307). In the OMM arm, 23 of 103 (22%) received delayed LVADs (18 within 12 months; 5 from 12 to 24 months). LVAD adverse events declined after year 1 for bleeding (primarily gastrointestinal) and arrhythmias. CONCLUSIONS Survival on original therapy with improvement in 6-min walk distance was superior with LVAD compared with OMM at 2 years. Reduction in key adverse events beyond 1 year was observed in the LVAD group. The ROADMAP trial provides risk-benefit information to guide patient- and physician-shared decision making for elective LVAD therapy as a treatment for heart failure. (Risk Assessment and Comparative Effectiveness of Left Ventricular Assist Device and Medical Management in Ambulatory Heart Failure Patients [ROADMAP]; NCT01452802
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