Design Manual for Low Water Stream Crossings, October 1983

The purpose of this manual is to provide design guidelines for low water stream crossings (LWSCs). Rigid criteria for determining the applicability of a LWSC to a given site are not established since each site is unique in terms of physical, social, economic, and political factors. Because conditions vary from county to county, it is not the intent to provide a "cook-book" procedure for designing a LWSC. Rather, engineering judgment must be applied to the guidelines contained in this manual.

Low Water Stream Crossing: Design and Construction Recommendations, December 2001

Most counties have bridges that are no longer adequate, and are faced with large capital expenditure for replacement structures of the same size. In this regard, low water stream crossings (LWSCs) can provide an acceptable, low cost alternative to bridges and culverts on low volume and reduced maintenance level roads. In addition to providing a low cost option for stream crossings, LWSCs have been designed to have the additional benefit of stream bed stabilization. Considerable information on the current status of LWSCs in Iowa, along with insight of needs for design assistance, was gained from a survey of county engineers that was conducted as part of this research (Appendix A). Copies of responses and analysis are included in Appendix B. This document provides guidelines for the design of LWSCs. There are three common types of LWSCs: unvented ford, vented ford with pipes, and low water bridges. Selection among these depends on stream geometry, discharge, importance of road, and budget availability. To minimize exposure to tort liability, local agencies using low water stream crossings should consider adopting reasonable selection and design criteria and certainly provide adequate warning of these structures to road users. The design recommendations included in this report for LWSCs provide guidelines and suggestions for local agency reference. Several design examples of design calculations are included in Appendix E.

The Design of Forest Taxation: A Synthesis with New Directions

Summary

The Macklin effect: a frequent etiology for pneumomediastinum in severe blunt chest trauma.

STUDY OBJECTIVES: To review the etiology and pathophysiology of pneumomediastinum in severe blunt trauma, with a special interest in one of its possible origins, the Macklin effect. The Macklin effect relates to a three-step pathophysiologic process: blunt traumatic alveolar ruptures, air dissection along bronchovascular sheaths, and spreading of this blunt pulmonary interstitial emphysema into the mediastinum. The clinical relevance of the Macklin effect was also evaluated. SETTING: A university hospital serving as a reference trauma center. PATIENTS: A selection of 51 patients with severe blunt trauma between 1995 and 2000. Inclusion criteria: Severe trauma or high-speed deceleration justifying chest CT; if chest CT demonstrated a pneumomediastinum, bronchoscopy and esophagoscopy were performed to rule out tracheobronchial or esophageal injury. DESIGN: Retrospective analysis of patients' clinical files, chest CT, and bronchoscopy and esophagoscopy reports. The Macklin effect was diagnosed when an air collection adjacent to a bronchus and a pulmonary vessel could be clearly identified on the chest CT. Clinical relevance of the Macklin effect was statistically evaluated regarding its repercussions on the pulmonary gas exchange function, the respective durations of intensive care and total hospital stay, and the associated injuries. RESULTS: Twenty (39%) Macklin effects and 5 tracheobronchial injuries (10%) were identified. One tracheobronchial injury occurred simultaneously with the Macklin effect. The presence of the Macklin effect affected neither the clinical profile nor the result of pulmonary gas analysis on hospital admission, but was associated with a significant (p < 0.001) lengthening of the intensive care stay. CONCLUSIONS: The Macklin effect is present in 39% of severe blunt traumatic pneumomediastinum detected by CT. Its identification does not rule out a tracheobronchial injury. The Macklin effect reflects severe trauma, since it is associated with significantly prolonged intensive care stay.

Cost-effective experimental design to support modeling of concentration-response functions

Modeling concentration-response function became extremely popular in ecotoxicology during the last decade. Indeed, modeling allows determining the total response pattern of a given substance. However, reliable modeling is consuming in term of data, which is in contradiction with the current trend in ecotoxicology, which aims to reduce, for cost and ethical reasons, the number of data produced during an experiment. It is therefore crucial to determine experimental design in a cost-effective manner. In this paper, we propose to use the theory of locally D-optimal designs to determine the set of concentrations to be tested so that the parameters of the concentration-response function can be estimated with high precision. We illustrated this approach by determining the locally D-optimal designs to estimate the toxicity of the herbicide dinoseb on daphnids and algae. The results show that the number of concentrations to be tested is often equal to the number of parameters and often related to the their meaning, i.e. they are located close to the parameters. Furthermore, the results show that the locally D-optimal design often has the minimal number of support points and is not much sensitive to small changes in nominal values of the parameters. In order to reduce the experimental cost and the use of test organisms, especially in case of long-term studies, reliable nominal values may therefore be fixed based on prior knowledge and literature research instead of on preliminary experiments

Randomized controlled trial of interventions for young people at ultra-high risk of psychosis: study design and baseline characteristics.

OBJECTIVE: Intervention during the pre-psychotic period of illness holds the potential of delaying or even preventing the onset of a full-threshold disorder, or at least of reducing the impact of such a disorder if it does develop. The first step in realizing this aim was achieved more than 10 years ago with the development and validation of criteria for the identification of young people at ultra-high risk (UHR) of psychosis. Results of three clinical trials have been published that provide mixed support for the effectiveness of psychological and pharmacological interventions in preventing the onset of psychotic disorder. METHOD: The present paper describes a fourth study that has now been undertaken in which young people who met UHR criteria were randomized to one of three treatment groups: cognitive therapy plus risperidone (CogTher + Risp: n = 43); cognitive therapy plus placebo (CogTher + Placebo: n = 44); and supportive counselling + placebo (Supp + Placebo; n = 28). A fourth group of young people who did not agree to randomization were also followed up (monitoring: n = 78). Baseline characteristics of participants are provided. RESULTS AND CONCLUSION: The present study improves on the previous studies because treatment was provided for 12 months and the independent contributions of psychological and pharmacological treatments in preventing transition to psychosis in the UHR cohort and on levels of psychopathology and functioning can be directly compared. Issues associated with recruitment and randomization are discussed.

A multi-center study: intra-scan and inter-scan variability of diffusion spectrum imaging.

The objective of this study was to investigate whether it is possible to pool together diffusion spectrum imaging data from four different scanners, located at three different sites. Two of the scanners had identical configuration whereas two did not. To measure the variability, we extracted three scalar maps (ADC, FA and GFA) from the DSI and utilized a region and a tract-based analysis. Additionally, a phantom study was performed to rule out some potential factors arising from the scanner performance in case some systematic bias occurred in the subject study. This work was split into three experiments: intra-scanner reproducibility, reproducibility with twin-scanner settings and reproducibility with other configurations. Overall for the intra-scanner and twin-scanner experiments, the region-based analysis coefficient of variation (CV) was in a range of 1%-4.2% and below 3% for almost every bundle for the tract-based analysis. The uncinate fasciculus showed the worst reproducibility, especially for FA and GFA values (CV 3.7-6%). For the GFA and FA maps, an ICC value of 0.7 and above is observed in almost all the regions/tracts. Looking at the last experiment, it was found that there is a very high similarity of the outcomes from the two scanners with identical setting. However, this was not the case for the two other imagers. Given the fact that the overall variation in our study is low for the imagers with identical settings, our findings support the feasibility of cross-site pooling of DSI data from identical scanners.

Design of Optical Systems With Extended Depth of Field: an Educational Approach to Wavefront Coding Techniques

A practical activity designed to introduce wavefront coding techniques as a method to extend the depth of field in optical systems is presented. The activity is suitable for advanced undergraduate students since it combines different topics in optical engineering such as optical system design, aberration theory, Fourier optics, and digital image processing. This paper provides the theoretical background and technical information for performing the experiment. The proposed activity requires students able to develop a wide range of skills since they are expected to deal with optical components, including spatial light modulators, and develop scripts to perform some calculations.

New multiple matched filter: design and experimental realization

A method of making a multiple matched filter which allows the recognition of different characters in successive planes in simple conditions is proposed. The generation of the filter is based on recording on the same plate the Fourier transforms of the different patterns to be recognized, each of which is affected by different spherical phase factors because the patterns have been placed at different distances from the lens. This is proved by means of experiments with a triple filter which allows satisfactory recognition of three characters.

Application of fuzzy-rule-based postprocessing to correlation methods in pattern recognition

One of the most important problems in optical pattern recognition by correlation is the appearance of sidelobes in the correlation plane, which causes false alarms. We present a method that eliminate sidelobes of up to a given height if certain conditions are satisfied. The method can be applied to any generalized synthetic discriminant function filter and is capable of rejecting lateral peaks that are even higher than the central correlation. Satisfactory results were obtained in both computer simulations and optical implementation.

Design of surface forces apparatus for tribology studies combined with nonlinear optical spectroscopy

We describe the design, calibration, and performance of surface forces apparatus with the capability of illumination of the contact interface for spectroscopic investigation using optical techniques. The apparatus can be placed in the path of a Nd-YAG laser for studies of the linear response or the second harmonic and sum-frequency generation from a material confined between the two surfaces. In addition to the standard fringes of equal chromatic order technique, which we have digitized for accurate and fast analysis, the distance of separation can be measured with a fiber-optic interferometer during spectroscopic measurements (2 Å resolution and 10 ms response time). The sample approach is accomplished through application of a motor drive, piezoelectric actuator, or electromagnetic lever deflection for variable degrees of range, sensitivity, and response time. To demonstrate the operation of the instrument, the stepwise expulsion of discrete layers of octamethylcyclotetrasiloxane from the contact is shown. Lateral forces may also be studied by using piezoelectric bimorphs to induce and direct the motion of one surface.

Ruling out coronary artery disease in primary care: development and validation of a simple prediction rule.

BACKGROUND: Chest pain can be caused by various conditions, with life-threatening cardiac disease being of greatest concern. Prediction scores to rule out coronary artery disease have been developed for use in emergency settings. We developed and validated a simple prediction rule for use in primary care. METHODS: We conducted a cross-sectional diagnostic study in 74 primary care practices in Germany. Primary care physicians recruited all consecutive patients who presented with chest pain (n = 1249) and recorded symptoms and findings for each patient (derivation cohort). An independent expert panel reviewed follow-up data obtained at six weeks and six months on symptoms, investigations, hospital admissions and medications to determine the presence or absence of coronary artery disease. Adjusted odds ratios of relevant variables were used to develop a prediction rule. We calculated measures of diagnostic accuracy for different cut-off values for the prediction scores using data derived from another prospective primary care study (validation cohort). RESULTS: The prediction rule contained five determinants (age/sex, known vascular disease, patient assumes pain is of cardiac origin, pain is worse during exercise, and pain is not reproducible by palpation), with the score ranging from 0 to 5 points. The area under the curve (receiver operating characteristic curve) was 0.87 (95% confidence interval [CI] 0.83-0.91) for the derivation cohort and 0.90 (95% CI 0.87-0.93) for the validation cohort. The best overall discrimination was with a cut-off value of 3 (positive result 3-5 points; negative result <or= 2 points), which had a sensitivity of 87.1% (95% CI 79.9%-94.2%) and a specificity of 80.8% (77.6%-83.9%). INTERPRETATION: The prediction rule for coronary artery disease in primary care proved to be robust in the validation cohort. It can help to rule out coronary artery disease in patients presenting with chest pain in primary care.

Blood pressure and LDL-cholesterol targets for prevention of recurrent strokes and cognitive decline in the hypertensive patient: design of the European Society of Hypertension-Chinese Hypertension League Stroke in Hypertension Optimal Treatment randomized trial.

BACKGROUND AND OBJECTIVES: The SBP values to be achieved by antihypertensive therapy in order to maximize reduction of cardiovascular outcomes are unknown; neither is it clear whether in patients with a previous cardiovascular event, the optimal values are lower than in the low-to-moderate risk hypertensive patients, or a more cautious blood pressure (BP) reduction should be obtained. Because of the uncertainty whether 'the lower the better' or the 'J-curve' hypothesis is correct, the European Society of Hypertension and the Chinese Hypertension League have promoted a randomized trial comparing antihypertensive treatment strategies aiming at three different SBP targets in hypertensive patients with a recent stroke or transient ischaemic attack. As the optimal level of low-density lipoprotein cholesterol (LDL-C) level is also unknown in these patients, LDL-C-lowering has been included in the design. PROTOCOL DESIGN: The European Society of Hypertension-Chinese Hypertension League Stroke in Hypertension Optimal Treatment trial is a prospective multinational, randomized trial with a 3 × 2 factorial design comparing: three different SBP targets (1, <145-135; 2, <135-125; 3, <125 mmHg); two different LDL-C targets (target A, 2.8-1.8; target B, <1.8 mmol/l). The trial is to be conducted on 7500 patients aged at least 65 years (2500 in Europe, 5000 in China) with hypertension and a stroke or transient ischaemic attack 1-6 months before randomization. Antihypertensive and statin treatments will be initiated or modified using suitable registered agents chosen by the investigators, in order to maintain patients within the randomized SBP and LDL-C windows. All patients will be followed up every 3 months for BP and every 6 months for LDL-C. Ambulatory BP will be measured yearly. OUTCOMES: Primary outcome is time to stroke (fatal and non-fatal). Important secondary outcomes are: time to first major cardiovascular event; cognitive decline (Montreal Cognitive Assessment) and dementia. All major outcomes will be adjudicated by committees blind to randomized allocation. A Data and Safety Monitoring Board has open access to data and can recommend trial interruption for safety. SAMPLE SIZE CALCULATION: It has been calculated that 925 patients would reach the primary outcome after a mean 4-year follow-up, and this should provide at least 80% power to detect a 25% stroke difference between SBP targets and a 20% difference between LDL-C targets.

I-74 Iowa/Illinois Corridor Study Aesthetic Design Guideline April 6, 2009

The I-74 Aesthetic Design Guideline (ADG) document has two primary goals: To establish and identify an overall design theme To prioritize enhancement opportunities within the framework of corridor elements The recommendations of this report have been developed based on an “unconstrained” framework for future corridor–wide enhancements. Future funding availability, along with the recommendations of this report, will guide the final design process. ADG Future Uses: This document is intended to be used as a reference to future processes in the following ways: Guidance for I-74 final design teams Reference document for future local community redevelopment initiatives Inspiration for identification and development of other I-74 corridor aesthetic enhancement opportunities Process: As illustrated in Figure 1.3, the overall process for corridor aesthetics began traditionally with inventory and identification of potential aesthetic applications. The ADG does not document all the reports and presentations related to these early design stages, but has incorporated these efforts into the design theme, guiding principles and prioritized enhancements shown on the following pages of this report. The I-74 final design phase will incorporate these recommendations into the project. The consultant design team and representatives of the DOTs have worked with the CAAT members to facilitate community input and have helped develop recommendations for improving I-74 corridor aesthetics. CAAT recommendations have been advanced to the I-74 Advisory Committee for review and endorsement. Both DOTs have reviewed the CAAT recommendations and have endorsed the contents of this report. Figure 1.4 illustrates the status of corridor aesthetic design development. As of the date of this report, aesthetic design is approximately 50% complete. Future detailed design, cost evaluation, feasibility and prioritizations all need to occur for this process to be successfully completed.