Sampling Errors in Observed Gravity Wave Momentum Fluxes from Vertical and Tilted Profiles

Observations from radiosondes or from vertically pointing remote sensing profilers are often used to estimate the vertical flux of momentum due to gravity waves. For planar, monochromatic waves, these vertically integrated fluxes are equal to the phase averaged flux and equivalent to the horizontal averaging used to deduce momentum flux from aircraft data or in numerical models. Using a simple analytical solution for two-dimensional hydrostatic gravity waves over an isolated ridge, it is shown that this equivalence does not hold for mountain waves. For a vertical profile, the vertically integrated flux estimate is proportional to the horizontally integrated flux and decays with increasing distance of the profile location from the mountain. For tilted profiles, such as those obtained from radiosonde ascents, there is a further sampling error that increases as the trajectory extends beyond the localised wave field. The same sampling issues are seen when the effects of the Coriolis force on the gravity waves are taken into account. The conclusion of this work is that caution must be taken when using radiosondes or other vertical profiles to deduce mountain wave momentum fluxes

Assessment of valley cold pools and clouds in a very high-resolution numerical weather prediction model

The formation of cold air pools in valleys under stable conditions represents an important challenge for numerical weather prediction (NWP). The challenge is increased when the valleys that dominate cold pool formation are on scales unresolved by NWP models, which can lead to substantial local errors in temperature forecasts. In this study a 2-month simulation is presented using a nested model con- figuration with a finest horizontal grid spacing of 100 m. The simulation is compared with observations from the recent COLd air Pooling Experiment (COLPEX) project and the model’s ability to represent cold pool formation, and the surface energy balance is assessed. The results reveal a bias in the model long-wave radiation that results from the assumptions made about the sub-grid variability in humidity in the cloud parametrization scheme. The cloud scheme assumes relative humidity thresholds below 100 % to diagnose partial cloudiness, an approach common to schemes used in many other models. The biases in radiation, and resulting biases in screen temperature and cold pool properties are shown to be sensitive to the choice of critical relative humidity, suggesting that this is a key area that should be improved for very high-resolution modeling

A case‐study of cold‐air pool evolution in hilly terrain using field measurements from COLPEX

A case‐study investigation of cold‐air pool (CAP) evolution in hilly terrain is conducted using field measurements made during IOP 16 of the COLd‐air Pool EXperiment (COLPEX). COLPEX was designed to study cold‐air pooling in small‐scale valleys typical of the UK (∼100–200 m deep, ∼1 km wide). The synoptic conditions during IOP 16 are typical of those required for CAPs to form during the night, with high pressure, clear skies and low ambient winds. Initially a CAP forms around sunset and grows uninterrupted for several hours. However, starting 4 hr after sunset, a number of interruptions to this steady cooling rate occur. Three episodes are highlighted from the observations and the cause of disruption attributed to (a) wave activity, in the form of gravity waves and/or Kelvin–Helmholtz (KH) instability, (b) increases in the above‐valley winds resulting from the development of a nocturnal low‐level jet (NLLJ), (c) shear‐induced mixing resulting from instability of the NLLJ. A weakly stable residual layer provides the conditions for wave activity during Episode 1. This residual layer is eroded by a developing NLLJ from the top down during Episode 2. The sustained increase in winds at hill‐top levels – attributed to the NLLJ – continue to disrupt the CAP through Episode 3. Although cooling is interrupted, the CAP is never completely eroded during the night. Complete CAP break‐up occurs some 3.5 hr after local sunrise. This case‐study highlights a number of meteorological phenomena that can disrupt CAP evolution even in ideal CAP conditions. These processes are unlikely to be sufficiently represented by current operational weather forecast models and can be challenging even for high‐resolution research models

Life-Cycle Cost and Risk Analysis of Alternative Configurations for Shipping Low-Level Radioactive Waste to the Nevada Test Site

The Nevada Test Site (NTS) is a major receiver of low-level radioactive waste (LLW) for disposal. Currently, all LLW received at NTS is shipped by truck. The trucks use highway routes to NTS that pass through the Las Vegas Valley and over Hoover Dam, which is a concern of local stakeholder groups in the State of Nevada. Rail service offers the opportunity to reduce transportation risks and costs, according to the Waste Management Programmatic Environmental Impact Statement (WM-PEIS). However, NTS and some DOE LLW generator sites are not served with direct rail service so intermodal transport is under consideration. Intermodal transport involves transport via two modes, in this case truck and rail, from the generator sites to NTS. LLW shipping containers would be transferred between trucks and railcars at intermodal transfer points near the LLW generator sites, NTS, or both. An Environmental Assessment (EA)for Intermodal Transportation of Low-Level Radioactive Waste to the Nevada Test Site (referred to as the NTSIntermodal -M) has been prepared to determine whether there are environmental impacts to alterations to the current truck routing or use of intermodal facilities within the State of Nevada. However, an analysis of the potential impacts outside the State of Nevada are not addressed in the NTS Intermodal EA. This study examines the rest of the transportation network between LLW generator sites and the NTS and evaluates the costs, risks, and feasibility of integrating intermodal shipments into the LLW transportation system. This study evaluates alternative transportation system configurations for NTS approved and potential generators based on complex-wide LLW load information. Technical judgments relative to the availability of DOE LLW generators to ship from their sites by rail were developed. Public and worker risk and life-cycle cost components are quantified. The study identifies and evaluates alternative scenarios that increase the use of rail (intermodal where needed) to transport LLW from generator sites to NTS

Effect of drug utilization reviews on the quality of in-hospital prescribing: a quasi-experimental study

BACKGROUND: Drug utilization review (DUR) programs are being conducted in Canadian hospitals with the aim of improving the appropriateness of prescriptions. However, there is little evidence of their effectiveness. The objective of this study was to assess the impact of both a retrospective and a concurrent DUR programs on the quality of in-hospital prescribing. METHODS: We conducted an interrupted time series quasi-experimental study. Using explicit criteria for quality of prescribing, the natural history of cisapride prescription was established retrospectively in three university-affiliated hospitals. A retrospective DUR was implemented in one of the hospitals, a concurrent DUR in another, whereas the third hospital served as a control. An archivist abstracted records of all patients who were prescribed cisapride during the observation period. The effect of DURs relative to the control hospital was determined by comparing estimated regression coefficients from the time series models and by testing the statistical significance using a 2-tailed Student's t test. RESULTS: The concurrent DUR program significantly improved the appropriateness of prescriptions for the indication for use whereas the retrospective DUR brought about no significant effect on the quality of prescribing. CONCLUSION: Results suggest a retrospective DUR approach may not be sufficient to improve the quality of prescribing. However, a concurrent DUR strategy, with direct feedback to prescribers seems effective and should be tested in other settings with other drugs

Nepal's Response to Earthquake 2015: Experience of Emergency Responders and Humanitarian Assistance providers in Inclusive and Accessible Humanitarian Assistance Delivery

The earthquake that hit Nepal in 2015 received worldwide attention for the devastation it caused to lives and infrastructures. Yet, the impact of it on people with disabilities (PWDs) and experiences of emergency responders and humanitarian assistance providers have remained under researched. This study aims to explore first hand experiences faced by emergency responders and humanitarian assistance providers to evaluate the effectiveness in implementation of disability inclusive and accessible emergency response during disaster; and to identify good practices and barriers faced by them in facilitating inclusive and accessible recovery and rehabilitation post disaster. Lessons learnt from barriers and challenges faced by the service providers, when addressed, will promote improved policies, processes and programmes around inclusive and accessible emergency and humanitarian response, recovery and rehabilitation. This study is based on semi-structured interviews with 20 key informants/stakeholders, and thematic analysis of the data generated. Findings suggest that most stakeholders were engaged in disability inclusive disaster risk management (DiDRM), capacity building and resilience developing awareness campaigns. However, there are significant gaps in policies, training and practices. These gaps include, a dire lack of inclusive and accessible equipment and resources; lack of and failure to implement and utilise knowledge and resources available; lack of data and guidelines on disability inclusive emergency response (DIER); and lack of communication and coordination between emergency responders and DPOs. These challenges hindered search and rescue (SAR) and relief efforts resulting in inappropriate and slow recovery and rehabilitation for PWDs. This study recommends for including PWDs in planning, designing and building inclusive and accessible emergency preparedness, response, SAR toolkit and emergency shelters. Nepal now has opportunities to integrate accessible infrastructures, DiDRM and implementation at community level. One way of achieving DiDRM at community level could be building a bank of desegregated data, skilled volunteers and accessible equipment to meet the emergency needs of PWDs

How many sentinel nodes should be harvested in oral squamous cell carcinoma?

The number of harvested lymph nodes when performing sentinel lymph node (SLN) biopsy remains controversial. The aim of this study was to examine the maximum number of nodes to be harvested for histopathological analysis. We also wanted to determine if the level of radioactivity within a SLN or its size were indicators for the likelihood of nodal metastases. The SLNs from 34 neck dissection specimens from patients with T1/T2 N0 oral and oropharyngeal carcinomas were included. Altogether 76 SLNs were measured for radioactivity and lymph node dimensions and volume. Tumour was identified in 16 of 76 nodes (positive nodes), and the remaining 60 nodes were free from tumour (negative nodes). In 9 of 16 cases, metastases were in the hottest node. Two patients had more than one positive SLN: the first and fourth hottest in one and the second and fourth hottest nodes in another contained tumour. However, all patients would have been staged accurately if only the hottest three sentinel nodes had been retrieved. Lymph nodes that contained tumour had a greater maximum diameter than non-metastatic SLNs. To stage the neck accurately, only the three hottest lymph nodes required sampling

Degenerate Stars and Gravitational Collapse in AdS/CFT

We construct composite CFT operators from a large number of fermionic primary fields corresponding to states that are holographically dual to a zero temperature Fermi gas in AdS space. We identify a large N regime in which the fermions behave as free particles. In the hydrodynamic limit the Fermi gas forms a degenerate star with a radius determined by the Fermi level, and a mass and angular momentum that exactly matches the boundary calculations. Next we consider an interacting regime, and calculate the effect of the gravitational back-reaction on the radius and the mass of the star using the Tolman-Oppenheimer-Volkoff equations. Ignoring other interactions, we determine the "Chandrasekhar limit" beyond which the degenerate star (presumably) undergoes gravitational collapse towards a black hole. This is interpreted on the boundary as a high density phase transition from a cold baryonic phase to a hot deconfined phase.Comment: 75 page