Similarity of Options and the Measurement of Diversity

This paper analyzes the measurement of the diversity of sets based on the dissimilarity of the objects contained in the set. We discuss axiomatic approaches to diversity measurement and examine the considerations underlying the application of specific measures. Our focus is on descriptive issues: rather than assuming a specific ethical position or restricting attention to properties that are appealing in specific applications, we address the foundations of the measurement issue as such in the context of diversity.Cet article s'occupe des mesures de la diversité. Pour une notion donnée de similarité des objets dans les ensembles à mesurer, nous caractérisons des mesures de diversité descriptives

Spectral and picosecond temporal properties of flared guide Y‐coupled phase‐locked laser arrays

Spatio‐spectral and spatio‐temporal properties of flared waveguide ‘‘Y’’‐coupled laser arrays are investigated in both cw and pulsed operation. In each case, regular sustained self‐pulsations are exhibited. Destabilization of phase locking, caused by amplitude phase coupling, is thought to be the origin of the pulsations.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/70525/2/APPLAB-53-24-2380-1.pd

Systemic corticosteroids for the management of cancer-related breathlessness (dyspnoea) in adults

BACKGROUND: Dyspnoea is a common symptom in advanced cancer, with a prevalence of up to 70% among patients at end of life. The cause of dyspnoea is often multifactorial, and may cause considerable psychological distress and suffering. Dyspnoea is often undertreated and good symptom control is less frequently achieved in people with dyspnoea than in people with other symptoms of advanced cancer, such as pain and nausea. The exact mechanism of action of corticosteroids in managing dyspnoea is unclear, yet corticosteroids are commonly used in palliative care for a variety of non-specific indications, including pain, nausea, anorexia, fatigue and low mood, despite being associated with a wide range of adverse effects. In view of their widespread use, it is important to seek evidence of the effects of corticosteroids for the management of cancer-related dyspnoea. OBJECTIVES: To assess the effects of systemic corticosteroids for the management of cancer-related breathlessness (dyspnoea) in adults. SEARCH METHODS: We searched CENTRAL, MEDLINE, Embase, CINAHL, Science Citation Index Web of Science, Latin America and Caribbean Health Sciences (LILACS) and clinical trial registries, from inception to 25 January 2018. SELECTION CRITERIA: We included randomised controlled trials that included adults aged 18 years and above. We included participants with cancer-related dyspnoea when randomised to systemic corticosteroids (at any dose) administered for the relief of cancer-related dyspnoea or any other indication, compared to placebo, standard or alternative treatment. DATA COLLECTION AND ANALYSIS: Five review authors independently assessed trial quality and three extracted data. We used means and standard deviations for each outcome to report the mean difference (MD) with 95% confidence interval (CI). We assessed the risk of bias and quality of evidence using GRADE. We extracted primary outcomes of sensory-perceptual experience of dyspnoea (intensity of dyspnoea), affective distress (quality of dyspnoea) and symptom impact (burden of dyspnoea or impact on function) and secondary outcomes of serious adverse events, participant satisfaction with treatment and participant withdrawal from trial. MAIN RESULTS: Two studies met the inclusion criteria, enrolling 157 participants (37 participants in one study and 120 in the other study), of whom 114 were included in the analyses. The studies compared oral dexamethasone to placebo, followed by an open-label phase in one study. One study lasted seven days, and the duration of the other study was 15 days.We were unable to conduct many of our predetermined analyses due to different agents, dosages, comparators and outcome measures, routes of drug delivery, measurement scales and time points. Subgroup analysis according to type of cancer was not possible.Primary outcomesWe included two studies (114 participants) with data at one week in the meta-analysis for change in dyspnoea intensity/dyspnoea relief from baseline. Corticosteroid therapy with dexamethasone resulted in an MD of lower dyspnoea intensity compared to placebo at one week (MD -0.85 lower dyspnoea (scale 0-10; lower score = less breathlessness), 95% CI -1.73 to 0.03; very low-quality evidence), although we were uncertain as to whether corticosteroids had an important effect on dyspnoea as results were imprecise. We downgraded the quality of evidence by three levels from high to very low due to very serious study limitations and imprecision.One study measured affective distress (quality of dyspnoea) and results were similar between groups (29 participants; very low-quality evidence). We downgraded the quality of the evidence three times for imprecision, inconsistency, and serious study limitations.Both studies assessed symptom impact (burden of dyspnoea or impact on function) (113 participants; very low-quality evidence). In one study, it was unclear whether dexamethasone had an effect on dyspnoea as results were imprecise. The second study showed more improvement for physical well-being scores at days eight and 15 in the dexamethasone group compared with the control group, but there was no evidence of a difference for FACIT social/family, emotional or functional scales. We downgraded the quality of the evidence three times for imprecision, inconsistency, and serious study limitations.Secondary outcomesDue to the lack of homogenous outcome measures and inconsistency in reporting, we could not perform quantitative analysis for any secondary outcomes. In both studies, the frequency of adverse events was similar between groups, and corticosteroids were generally well tolerated. The withdrawal rates for the two studies were 15% and 36%. Reasons for withdrawal included lost to follow-up, participant or carer (or both) refusal, and death due to disease progression. We downgraded the quality of evidence for these secondary outcomes by three levels from high to very low due to serious study limitations, inconsistency and imprecision.Neither study examined participant satisfaction with treatment. AUTHORS' CONCLUSIONS: There are few studies assessing the effects of systemic corticosteroids on cancer-related dyspnoea in adults with cancer. We judged the evidence to be of very low quality that neither supported nor refuted corticosteroid use in this population. Further high-quality studies are needed to determine if corticosteroids are efficacious in this setting

Numerical modeling of a multiscale gravity wave event and its airglow signatures over Mount Cook, New Zealand, during the DEEPWAVE campaign

A 2-D nonlinear compressible model is used to simulate a large-amplitude, multiscale mountain wave event over Mount Cook, NZ, observed as part of the Deep Propagating Gravity Wave Experiment (DEEPWAVE) campaign and to investigate its observable signatures in the hydroxyl (OH) layer. The campaign observed the presence of a _x=200ækm mountain wave as part of the 22nd research flight with amplitudes of \u3e20æK in the upper stratosphere that decayed rapidly at airglow heights. Advanced Mesospheric Temperature Mapper (AMTM) showed the presence of small-scale (25_28ækm) waves within the warm phase of the large mountain wave. The simulation results show rapid breaking above 70ækm altitude, with the preferential formation of almost-stationary vortical instabilities within the warm phase front of the mountain wave. An OH airglow model is used to identify the presence of small-scale wave-like structures generated in situ by the breaking of the mountain wave that are consistent with those seen in the observations. While it is easy to interpret these feature as waves in OH airglow data, a considerable fraction of the features are in fact instabilities and vortex structures. Simulations suggest that a combination of a large westward perturbation velocity and shear, in combination with strong perturbation temperature gradients, causes both dynamic and convective instability conditions to be met particularly where the wave wind is maximized and the temperature gradient is simultaneously minimized. This leads to the inevitable breaking and subsequent generation of smaller-scale waves and instabilities which appear most prominent within the warm phase front of the mountain wave. ©2017. American Geophysical Union. All Rights Reserved

Behavioral implications of shortlisting procedures

We consider two-stage “shortlisting procedures” in which the menu of alternatives is first pruned by some process or criterion and then a binary relation is maximized. Given a particular first-stage process, our main result supplies a necessary and sufficient condition for choice data to be consistent with a procedure in the designated class. This result applies to any class of procedures with a certain lattice structure, including the cases of “consideration filters,” “satisficing with salience effects,” and “rational shortlist methods.” The theory avoids background assumptions made for mathematical convenience; in this and other respects following Richter’s classical analysis of preference-maximizing choice in the absence of shortlisting

Secondary gravity wave generation over New Zealand during the DEEPWAVE campaign

Multiple events during the Deep Propagating Gravity Wave Experiment measurement program revealed mountain wave (MW) breaking at multiple altitudes over the Southern Island of New Zealand. These events were measured during several research flights from the National Science Foundation/National Center for Atmospheric Research Gulfstream V aircraft, utilizing a Rayleigh lidar, an Na lidar, and an Advanced Mesospheric Temperature Mapper simultaneously. A flight on 29 June 2014 observed MWs with horizontal wavelengths of ~80_120ækm breaking in the stratosphere from ~10 to 50ækm altitude. A flight on 13 July 2014 observed a horizontal wavelength of ~200_240ækm MW extending from 20 to 90ækm in altitude before breaking. Data from these flights show evidence for secondary gravity wave (SGW) generation near the breaking regions. The horizontal wavelengths of these SGWs are smaller than those of the breaking MWs, indicating a nonlinear generation mechanism. These observations reveal some of the complexities associated with MW breaking and the implications this can have on momentum fluxes accompanying SGWs over MW breaking regions. ©2017. American Geophysical Union. All Rights Reserved

Large-amplitude mesospheric response to an orographic wave generated over the Southern Ocean Auckland Islands (50.7°S) during the DEEPWAVE project

The Deep Propagating Gravity Wave Experiment (DEEPWAVE) project was conducted over New Zealand and the surrounding regions during June and July 2014, to more fully understand the generation, propagation, and effects of atmospheric gravity waves. A large suite of instruments collected data from the ground to the upper atmosphere (~100 km), with several new remote-sensing instruments operating on board the NSF Gulfstream V (GV) research aircraft, which was the central measurement platform of the project. On 14 July, during one of the research flights (research flight 23), a spectacular event was observed as the GV flew in the lee of the sub-Antarctic Auckland Islands (50.7°S). An apparent ship wave pattern was imaged in the OH layer (at ~83.5 km) by the Utah State University Advanced Mesospheric Temperature Mapper and evolved significantly over four successive passes spanning more than 4 h. The waves were associated with orographic forcing generated by relatively strong (15-20 m/s) near-surface wind flowing over the rugged island topography. The mountain wave had an amplitude T_ ~ 10 K, a dominant horizontal wavelength ~40 km, achieved a momentum flux exceeding 300 m2 s-2, and eventually exhibited instability and breaking at the OH altitude. This case of deep mountain wave propagation demonstrates the potential for strong responses in the mesosphere arising from a small source under suitable propagation conditions and suggests that such cases may be more common than previously believed. © 2016. American Geophysical Union. All Rights Reserved

Momentum flux estimates accompanying multiscale gravity waves over Mount Cook, New Zealand, on 13 July 2014 during the DEEPWAVE campaign

Observations performed with a Rayleigh lidar and an Advanced Mesosphere Temperature Mapper aboard the National Science Foundation/National Center for Atmospheric Research Gulfstream V research aircraft on 13 July 2014 during the Deep Propagating Gravity Wave Experiment (DEEPWAVE) measurement program revealed a large-amplitude, multiscale gravity wave (GW) environment extending from ~20 to 90 km on flight tracks over Mount Cook, New Zealand. Data from four successive flight tracks are employed here to assess the characteristics and variability of the larger- and smaller-scale GWs, including their spatial scales, amplitudes, phase speeds, and momentum fluxes. On each flight, a large-scale mountain wave (MW) having a horizontal wavelength ~200-300 km was observed. Smaller-scale GWs over the island appeared to correlate within the warmer phase of this large-scale MW. This analysis reveals that momentum fluxes accompanying small-scale MWs and propagating GWs significantly exceed those of the large-scale MW and the mean values typical for these altitudes, with maxima for the various small-scale events in the range ~20-105 m2 s-2. Key Points Mountain waves penetrate the mesosphere under suitable propagation conditions Small-scale gravity waves can attain very large momentum fluxes Occurrence of peak momentum fluxes is often dictated by multiscale environments. © 2015. American Geophysical Union. All Rights Reserved