The late-time development of the Richtmyer–Meshkov instability

Measurements have been made of the growth by the Richtmyer–Meshkov instability of nominally single-scale perturbations on an air/sulfur hexafluoride (SF6) interface in a large shock tube. An approximately sinusoidal shape is given to the interface by a wire mesh which supports a polymeric membrane separating the air from the SF6. A single shock wave incident on the interface induces motion by the baroclinic mechanism of vorticity generation. The visual thickness delta of the interface is measured from schlieren photographs obtained singly in each run and in high-speed motion pictures. Data are presented for delta at times considerably larger than previously reported, and they are tested for self-similarity including independence of initial conditions. Four different initial amplitude/wavelength combinations at one incident shock strength are used to determine the scaling of the data. It is found that the growth rate decreases rapidly with time, ddelta/dt[proportional]t–p (i.e., delta[proportional]t1–p), where 0.67<~p<~0.74 and that a small dependence on the initial wavelength lambda0 persists to large time. The larger value of the power law exponent agrees with the result of the late-time-decay similarity law of Huang and Leonard [Phys. Fluids 6, 3765–3775 (1994)]. The influence of the wire mesh and membrane on the mixing process is assessed

Surgical management of posterior fossa metastases

The diagnosis of brain metastases is associated with a poor prognosis reflecting uncontrolled primary disease that has spread to the relative sanctuary of the central nervous system. 20 % of brain metastases occur in the posterior fossa and are associated with significant morbidity. The risk of acute hydrocephalus and potential for sudden death means these metastases are often dealt with as emergency cases. This approach means a full pre-operative assessment and staging of underlying disease may be neglected and a proportion of patients undergo comparatively high risk surgery with little or no survival benefit. This study aimed to assess outcomes in patients to identify factors that may assist in case selection. We report a retrospective case series of 92 consecutive patients operated for posterior fossa metastases between 2007 and 2012. Routine demographic data was collected plus data on performance status, primary cancer site, details of surgery, adjuvant treatment and survival. The only independent positive prognostic factors identified on multivariate analysis were good performance status (if Karnofsky performance score >70, hazard ratio (HR) for death 0.36, 95 % confidence interval (CI) 0.18–0.69), adjuvant whole brain radiotherapy (HR 0.37, 95 % CI 0.21–0.65) and adjuvant chemotherapy where there was extracranial disease and non-synchronous presentation (HR 0.51, 95 % CI 0.31–0.82). Patients presenting with posterior fossa metastases may not be investigated as thoroughly as those with supratentorial tumours. Staging and assessment is essential however, and in the meantime emergencies related to tumour mass effect should be managed with steroids and cerebrospinal fluid diversion as required

A novel methodology for in vivo endoscopic phenotyping of colorectal cancer based on real-time analysis of the mucosal lipidome: a prospective observational study of the iKnife

Background: This pilot study assessed the diagnostic accuracy of rapid evaporative ionization mass spectrometry (REIMS) in colorectal cancer (CRC) and colonic adenomas. Methods: Patients undergoing elective surgical resection for CRC were recruited at St. Mary’s Hospital London and The Royal Marsden Hospital, UK. Ex vivo analysis was performed using a standard electrosurgery handpiece with aspiration of the electrosurgical aerosol to a Xevo G2-S iKnife QTof mass spectrometer (Waters Corporation). Histological examination was performed for validation purposes. Multivariate analysis was performed using principal component analysis and linear discriminant analysis in Matlab 2015a (Mathworks, Natick, MA). A modified REIMS endoscopic snare was developed (Medwork) and used prospectively in five patients to assess its feasibility during hot snare polypectomy. Results: Twenty-eight patients were recruited (12 males, median age 71, range 35–89). REIMS was able to reliably distinguish between cancer and normal adjacent mucosa (NAM) (AUC 0.96) and between NAM and adenoma (AUC 0.99). It had an overall accuracy of 94.4 % for the detection of cancer versus adenoma and an adenoma sensitivity of 78.6 % and specificity of 97.3 % (AUC 0.99) versus cancer. Long-chain phosphatidylserines (e.g., PS 22:0) and bacterial phosphatidylglycerols were over-expressed on cancer samples, while NAM was defined by raised plasmalogens and triacylglycerols expression and adenomas demonstrated an over-expression of ceramides. REIMS was able to classify samples according to tumor differentiation, tumor budding, lymphovascular invasion, extramural vascular invasion and lymph node micrometastases (AUC’s 0.88, 0.87, 0.83, 0.81 and 0.81, respectively). During endoscopic deployment, colonoscopic REIMS was able to detect target lipid species such as ceramides during hot snare polypectomy. Conclusion: REIMS demonstrates high diagnostic accuracy for tumor type and for established histological features of poor prognostic outcome in CRC based on a multivariate analysis of the mucosal lipidome. REIMS could augment endoscopic and imaging technologies for precision phenotyping of colorectal cancer

Is there such a thing as agile IT program management?

This paper presents early evidence of agile methods in IT enabled transformational programs of high strategic significance and substantial complexity in large organisations. Based on interviews of top management, and program and project managers, we discuss the key drivers that lead to agile IT enabled programs and some of the barriers encountered while managing IT enabled programs in an agile manner. In addition to the need for fast response to environmental changes, strong IT-business collaboration, and efficient resource use by minimising governance burden, we found that organisations are adopting agile practices in program management as transitory step towards achieving enterprise agility. In doing so agile and non-agile projects co-exist within a program thus creating new coordination challenges. Programs with high degree of agile methods adoption face similar challenges in coordinating with the rest of the organisation which operates in non-agile manner. The paper aims to contribute to fostering scholarly discussion on implementation of agile practices in major projects and programs, an emerging area of research with scarce academic literature

Seagrass communities of the Great Barrier Reef and their desired state: applications for spatial planning and management

The research program reported here evolved from an interest in developing ecologically relevant target criteria that, if met, correspond to desired ecological outcomes (e.g. desired state) for the Great Barrier Reef World Heritage Area (GBRWHA) and to achieving the overarching objective of the Great Barrier Reef Marine Park Authority’s Long-term Sustainability Plan. The objective of the original National Environment Science Program (NESP) Tropical Water Quality Hub (TWQ) Project 3.2.1 Deriving ecologically relevant load targets to meet desired ecosystem condition for the Great Barrier Reef: a case study for seagrass meadows in the Burdekin region was to examine relationships between catchment inputs of sediment and seagrass desired state, and to compare these against the 2018 Water Quality Improvement Plan’s ecological targets. This objective was met using a case study in Cleveland Bay based on sediment loads from the Burdekin River and other smaller catchments that discharge into the bay (Collier et al., 2020). The techniques developed in the Cleveland Bay case study are used in the present report at the scale of the whole GBRWHA for NESP TWQ Hub Project 5.4. To achieve this we followed three steps: (1) a consolidation and verification of seagrass data at the GBRWHA scale, (2) an analysis of the distribution of GBRWHA seagrass habitat and communities, and (3) an estimation of a desired state target for communities with sufficient data. To achieve step 1, we compiled and standardised 35 years of seagrass survey data in a spatial database, including 81,387 georeferenced data points. Twelve seagrass species were recorded, the deepest of which (Halophila spinulosa) was found at 76 m. This database is a valuable resource that provides coastal managers, researchers and the global marine community with a long-term spatial resource describing seagrass populations from the mid1980s against which to benchmark change. For step 2, we identified 88,331 km2 of potential seagrass habitat within the GBRWHA; 1,111 km2 in estuaries, 16,276 km2 in coastal areas, and 70,934 km2 in reef areas. Thirty-six seagrass community types were defined by species assemblages. The environmental conditions that structure the location and extent of these communities included depth, tidal exposure, latitude, current speed, benthic light, proportion of mud, water type, water temperature, salinity, and wind speed. Environmental parameters interact with the topography of the reef and changes in the coastal plain, its watersheds, and its development with latitude. We describe seagrass distributions and communities that are shaped by multiple combinations of these environmental complexities and how that may influence marine spatial planning and environmental protection initiatives (Chapter 3). For step 3, we used more than 20 years of historical data (1995-2018) on seagrass biomass for the diverse seagrass communities of the GBRWHA to develop desired state benchmarks. Of the 36 seagrass communities, desired state was identified for 25 of them, with the remainder having insufficient data. Desired state varied by more than one order of magnitude between community types, and was influenced by the mix of species in the communities and the range of environmental conditions that define community boundaries. We identified a historical, decadal-scale cycle of decline and recovery. Recovery to desired state has occurred for coastal intertidal communities following the most recent declines in 2008 - 2012. A number of the estuarine and coastal subtidal communities have not recovered to desired state biomass in recent years (Chapter 4). This body of work provides a huge step forward in our understanding of the complexities of GBRWHA seagrass communities. We discuss the relevance of these research outputs to future marine spatial planning and management. This includes zoning in “representative areas”, hierarchical monitoring design (e.g. RIMReP), and the setting of ecologically relevant sediment load targets for desired state (e.g. Lambert et al., 2019). The updated seagrass data, seagrass distribution, community classification and desired state targets provides important new information for incorporation into marine spatial planning and management that is discussed in Chapter 5. These applications include: • Future assessments of non-reef habitats within the GBRWHA and GBRMP. • Assessing how risk and spatial protection intersect with seagrass communities and the role they play in protecting seagrass, e.g. Queensland State and Commonwealth marine parks, Fish Habitat Areas, Dugong Protected Areas, Port Exclusion Zones. • Expanding our spatial analysis to areas ecologically connected but outside of the GBRWHA such as Torres Strait, the Gulf of Carpentaria, and Fraser Island coast, where we already have seagrass data. • Designing a hierarchical seagrass monitoring design with coarse scales (intertidal, subtidal, estuary, coast, reef) and fine scales (36 communities). We have identified significant knowledge gaps that should guide future monitoring efforts (e.g. RIMReP and Queensland Land and Sea Ranger Program), including a lack of consistent and recent data for reef seagrass communities. • We identified communities where data is deficient, such as in estuaries where important seagrass communities have potential exposure to multiple threats for which more consistent environmental data would be valuable. • Identifying potential restoration sites. Our work has highlighted the critical role of historical data in understanding spatial complexity and for making informed management decisions on the current state of seagrass in the GBRWHA. Our approach can be adapted for monitoring, management and assessment of pressures at other relevant scales and jurisdictions. Our results guide conservation planning through prioritisation of at-risk communities that are continuing to fail to attain desired state

Modeling the trend of Iraqi GDP for 1970-2020

The study of economic growth indicators is of fundamental importance in estimating the effectiveness of economic development plans, as well as the great role it plays in determining appropriate economic policies in order to optimally use the factors that lead to the dynamics of growth in Iraq, especially during a certain period of time. The gross domestic product (GDP) at current prices), which is considered a part of the national accounts, which is considered as an integrated dynamic of statistics that produces in front of policy makers the possibility of determining whether the economy is witnessing a state of expansion or evaluating economic activity and its efficiency in order to reach the size of the overall economy. The research aims to determine the best and most efficient statistical model to be used in forecasting the GDP in Iraq based on time series data for the period from (1970-2020) years. Where the general trend models (Linear trend, Quadratic trend and Exponential Trend) were applied, and the three models were compared to choose the best model using some statistical criteria, including the Akiaki Information Standard (AIC) and Schwartz Standard (SBS). The results showed that the appropriate model is the Quadratic trend model, were predicting and forecasting values are close to the real values of the GDP series

Dental crowding and its relationship to tooth size and arch dimensions

Background: Well alignments of the teeth in the dental arches achieves good esthetics  and  stability,  and a perfect  tooth  position  provides  ideal conditions  for  good  health  and  optimal  care of teeth. However, crowding of teeth is considered as the most common type of malocclusion. Aims: To quantify crowding by assessing the tooth size arch size discrepancy in crowded and non crowded arches. Materials and methods: The study was conducted on study casts obtained from sixty randomly selected students from College of Dentistry– University of Sulaimani in Kurdistan of Iraq with their age ranged from 19-24 years who were divided into crowded and noncrowded groups. For each group cumulative and individual tooth width and arch length were measured. They have been diagnosed and selected according to some specific criteria. Results: The study showed significant difference in the arch length measurement between the non crowded &amp; crowded (P&gt;0.01). No significant difference of the mesiodistal sums of entire arches between the non crowded and crowded samples (P&gt;0.05) was observed while by individual measurements of tooth mesiodistal dimension highly significant difference were found only in the right lateral incisor (P=0.001) Conclusion: The arch length was the associated factors in contribution of dental crowding. Keywords: Dental crowding, malocclusion, arch dimensions

Tuning parameter selectors for bridge penalty based on particle swarm optimization method

The bridge penalty is widely used as a penalty for selecting and shrinking predictors in regression models. Although its effectiveness is sensitive to the parameters you decide to use for shrinking and adjusting. The shrinkage and tuning parameters of the bridge penalty are chosen concurrently, and a continuous optimization process called particle swarm optimization is proposed as a means to do this. If implemented, the proposed method will greatly facilitate regression modeling with superior prediction performance. The results show that the proposed method is effective in comparison to other well-known methods, but this varies greatly depending on the simulation setup and the real data application